US 20080163910 A1
Umbrellas with improvements that make the umbrella easier to control. The improvements include an edge of the umbrella canopy that presents a convex surface to the flow of air across the canopy and that also may direct the flow of air away from the underside of the canopy and away from the user of the umbrella, gutters for directing the flow of water on the canopy, spoilers for modifying the flow of air across the canopy, windsocks that release air pressure under the canopy by inflating, and canopies with streamlined shapes, including shapes that may be modified by the user or modify themselves in response to the flow of air.
21. A canopy for an umbrella comprising:
an upper surface and a lower surface,
the upper surface including
a leading end and
a trailing end,
the upper surface having a shape which is substantially the shape of a portion of the surface of a teardrop, the portion's shape having a leading end and a trailing end and the portion's shape being bluffer in the leading end and more gradual in the trailing end, the leading end of the portion corresponding to the leading end of the upper surface and the trailing end of the portion corresponding to the trailing end of the upper surface.
22. The canopy set forth in
the canopy is attached to a pole; and
the pole is attached nearer the leading end of the canopy's shape than the trailing end thereof.
23. The canopy set forth in
the pole is not vertical when the canopy is substantially level.
24. The canopy set forth in
a hub at the canopy's leading end; and
longerons attached to the hub which support the canopy, the longerons being attached such that the longerons are rotatable around the hub, whereby the canopy is made foldable.
25. The canopy set forth in
a gutter on the canopy that causes water falling on the canopy to flow in a particular direction.
26. The canopy set forth in
the gutter causes the water to flow towards the trailing end of the canopy's shape.
27. The canopy set forth in
a rainwater escape chute; and
the gutter causes the water to flow into the rainwater escape chute.
28. The canopy set forth in
the gutter provides a channel for the water.
29. The canopy set forth in
the gutter is a guide which causes the water to flow predominantly in the given direction.
30. The canopy set forth in
the gutter further functions as a spoiler that acts on an airflow across the canopy.
31. The canopy set forth in
a spoiler on the canopy, the spoiler acting on an airflow across the canopy.
32. The canopy set forth in
the spoiler is on the leading end of the canopy.
33. The canopy set forth in
an edge that presents a convex surface to an air flow that strikes the edge.
34. The canopy set forth in
a rainwater escape chute at the trailing end of the canopy.
35. A canopy for an umbrella comprising:
an upper surface and
a lower surface, the upper surface including
a gutter on the canopy that causes water falling on the canopy to flow in a particular direction.
36. The canopy set forth in
the gutter causes the water to flow away from the canopy's front.
37. The canopy set forth in
the gutter provides a channel for the water.
38. The canopy set forth in
the gutter is a guide which causes the water to flow predominantly in the given direction.
39. The canopy set forth in
the gutter further functions as a spoiler with regard to a flow of air over the canopy.
40. The canopy set forth in
the canopy has a rounded head and a tapering tail.
41. The canopy set forth in
the gutter is on the rounded head and causes the water to flow away from the head's front.
42. The canopy set forth in
the canopy further includes a rainwater escape chute; and
the gutter causes the water to flow into the rainwater escape chute.
43. A canopy for an umbrella comprising:
an upper surface and
a lower surface,
the upper surface having a spoiler that acts on an airflow across the upper surface.
44. The canopy set forth in
the spoiler is a set of protuberances on the canopy which roughen the canopy with regard to the airflow.
45. A canopy for an umbrella comprising:
an upper surface,
a lower surface, and
a windsock having two ends, an end of the windsock being attached to the upper surface above a hole in the canopy and the windsock inflating when air pressure under the canopy is greater than air pressure above the canopy to release the air pressure under the canopy and otherwise collapsing.
46. The canopy set forth in
the windsock is additionally attached to the upper surface at a point other than above the hole in the canopy.
47. A canopy for an umbrella comprising:
a fabric cover;
one or more fabric pieces that are attached to the cover and act on the cover to prevent deformation of the canopy.
48. A canopy for an umbrella comprising:
a fabric cover; and
one or more ribs attached to the cover that support the cover when the cover is in use, the ribs being attached to the cover and having forms such that the canopy becomes substantially a disk when not in use.
49. A canopy for an umbrella comprising:
a non-deformable area; and
a deformable area which is capable of being deformed to give the canopy a shape that improves controllability of the canopy by a user of the umbrella with regard to airflow across the canopy.
50. The umbrella canopy set forth in
the deformable area is deformed such that the edge of the canopy which is the leading edge with regard to the airflow presents a convex surface to the airflow.
51. The umbrella canopy set forth in
the deformable area is deformed such that the canopy has a streamlined shape with regard to the airflow.
52. The umbrella canopy set forth in
the deformable area is deformed by a user of the umbrella.
53. The umbrella canopy set forth in
the deformable area deforms itself in response to the airflow.
54. An umbrella comprising:
a pole attached to the canopy; and
an edge of the canopy that presents a convex surface to an airflow that strikes the edge, the convex surface acting to substantially increase controllability of the umbrella by a user who is holding the umbrella by the pole.
55. The umbrella set forth in
the entire edge of the canopy presents the convex surface.
56. The umbrella set forth in
the convex surface deflects the airflow away from the canopy's under side.
57. The umbrella set forth in
the convex surface deflects the airflow away from the canopy's under side such that the canopy becomes a virtual double-surfaced airfoil.
58. The umbrella set forth in
a first portion of the canopy's edge presents the convex surface to the airflow; and a second portion of the canopy's edge which is opposite to the first portion does not present the convex surface to the air flow.
59. The umbrella set forth in
the convex surface deflects the airflow away from the user of the umbrella.
60. An umbrella comprising:
a canopy which is supported by at least one rib and by
a pole which continues the rib.
61. The umbrella set forth in
the rib and pole support the canopy from above.
62. A foldable canopy for an umbrella, the foldable canopy comprising:
an upper surface;
an area of the upper surface which becomes an end of the canopy when the canopy is folded; and
a tube attached to the area of the upper surface which is capable of serving as a cover to the folded canopy.
63. The foldable canopy set forth in
the tube is a windsock;
the windsock is attached around a hole in the area of the upper surface,
the windsock inflating when air pressure under the open canopy is greater than air pressure above the canopy to release the air pressure under the canopy and otherwise collapsing.
64. A pole for an umbrella, the pole comprising:
a handle on the shaft which permits the user to grip the shaft; and
an extension of the shaft which engages the user's forearm,
whereby the user may better resist an effect of a force applied to the umbrella's canopy on the pole.
65. A canopy for an umbrella, the canopy having a surface and the canopy comprising:
a hub; and
longerons attached to the hub which support the canopy's surface, the longerons being attached such that the longerons are rotatable around the hub, whereby the canopy is made foldable.
66. The canopy set forth in
the canopy's surface has a leading end and a trailing end; and
the hub is at the canopy's leading edge.
67. The canopy set forth in
a hub at the canopy's trailing end to which the longerons are attached such that the longerons are rotatable around the hub at the canopy's trailing end.
68. The canopy set forth in
a handle for the umbrella,
the handle being attached to the hub at the leading edge.
This patent application claims priority from U.S. provisional patent application 60/642,542, Steve Hollinger, Improved Umbrella Design, filed Jan. 10, 2005. That entire provisional patent application is incorporated by reference into the present patent application.
1. Field of the Invention
The invention has generally to do with umbrellas, and more particularly an umbrella with a canopy and support structure that renders the canopy more stable with regard to wind.
2. Description of Related Art
A conventional umbrella is made up of a fabric-covered canopy substantially symmetric to a longitudinal plane; a pole; a plurality of ribs extending radially from a central point on the canopy and extending to the canopy's perimeter; and a plurality of struts corresponding to the ribs as an aid in deploying and supporting the canopy cantilevered at the top of the pole. The improvements to umbrellas described in the following will be described in the context of rain umbrellas; many of the improvements are however applicable to umbrellas of all kinds, including parasols and stationary umbrellas.
Unless otherwise noted, descriptions that follow assume a canopy in its deployed state.
A conventional rain umbrella is operated by one user. The user applies force on the handle in order to counter the forces of rain and wind acting on the canopy, while seeking to maintain a canopy orientation that provides an adequate area of shielding from direct exposure to the wind and rain. Force applied by the user on the handle is transferred through the pole, struts and ribs to the canopy. Other possible interfaces between a user and a canopy are taught in prior art, and are contemplated by the umbrella of this invention.
As used in the following, wind means any flow of air relative to an umbrella's canopy. The flow of air may be caused by motion of the air itself, by motion of the umbrella through the air, or by a combination of these causes. The edge or surface of the canopy which faces into the wind is termed in the following the canopy's windward or leading edge or surface; the edge or surface of the canopy which faces away from the wind is termed the canopy's leeward or trailing edge or surface. A headwind is defined as a wind moving towards the front-facing umbrella user.
An umbrella user as shown at 101 in
A canopy is substantially convex on its exterior surface, and may have sub-surfaces that are planar, convex or concave. Unless otherwise noted, general curvature and shape of a canopy is discussed irrespective of isolated canopy elements such as clasps, fabric strips or other aesthetic adornments.
For the purpose of the discussion that follows, a set of definitions is proposed to aid in identifying and comparing portions of an umbrella canopy, irrespective of the support structure, pole, handle and adornments.
Longitudinal plane 201 as shown in
A canopy's fore section may also be referred to herein as the canopy's head and its aft-section may be referred to as the canopy's tail.
The canopy is typically symmetrical about the yaw axis, and the umbrella handle is typically located along this axis. This arrangement ensures that the canopy is balanced around the pole and handle.
Roll axis 219 is on the longitudinal plane, perpendicular to the face-plane, intersecting the canopy at two points 221 and 223. The two points are endpoints of line segment 227, named longitudinal-chord.
Pitch axis as shown at 301 in
For any orientation of a canopy fixed about its roll, pitch and yaw axes, the canopy's position with respect to user 351 is further described by a translational offset. The translational offset is changed by extension of the user's arm, and expressed as a forward, rearward, downward, upward and sideward change as shown at 353.
A canopy has an upper side exposed directly to elemental forces of wind and rain, and a under side generally protected from these elemental forces. As shown in
As defined, a pitch axis is not required to intersect with a yaw axis or a roll axis. Such a definition allows, for example, a canopy's area of maximum width to exist forward of its face-plane.
With the exception of the translational offset, the above definitions describe an umbrella independent of its user. It is expected, but not required, that a user will stand with shoulders aligned in parallel to the pitch axis.
The definitions permit description of a canopy independently from its pole, handle and support structure.
It is understood that roll, pitch and yaw axes, as defined for the purpose of this discussion, may not exactly correspond with axes of mass, axes of force and other axes defined by quantitative characteristics. For example, accessories or counterweights attached to the canopy and the support structure may alter an umbrella's center of gravity.
Canopy Shape Vis-À-Vis Handle Location
An umbrella must achieve several, often competing objectives. It is expected to be large enough to provide protection from falling raindrops, small enough to be manageable, contoured to minimize drag, and ergonomic in design to suit the user's hand and arm. Each of these objectives depends on the ability of the umbrella user to hold and apply force on the handle.
Because the handle is the point at which the user applies force in opposition to the forces acting on the canopy, the location of the handle is a critical factor in meeting the aforementioned objectives. For any given umbrella, a number of optimal handle locations exist, depending on intended use.
The center of pressure is the center of aerodynamic forces acting on the canopy. Because the canopy is extremely lightweight, aerodynamic forces easily exceed forces related to mass such as gravity or inertia. The handle, as a fixed point, is a fulcrum around which aerodynamic forces are torqued. The pole, in defining the distance from the center of pressure to the handle, represents a moment arm of force torqued at the handle. In this regard, the placement of the handle with respect to the center of pressure is critical for a particular canopy shape in maintaining a particular orientation, maintaining stability, and protection. For any given canopy shape, it is possible to improve aerodynamic performance by simply relocating the handle. Ergonomic factors and other considerations, however, must balance aerodynamic optimizations.
For example, conventional umbrellas at 501 and 511 of
Although handle 505 may be more comfortable than handle 515, handle 515 may be advantageous when headwinds are considered. As headwind 503 interacts with the canopy, force is applied perpendicular to the top of pole 507. Pole 507 acts as a lever and a firm grip of the user's hand becomes a fulcrum, resulting in torque on the user's wrist as seen at 509.
By comparison, as headwind 513 applies pressure on the canopy, the user experiences negligible torque on handle 515 because the moment arm between the center of pressure and handle is relatively small. The user experiences air pressure on the canopy as a pushing force 519. While wrist, hand, arm and body strength may be tested to resist the pushing force shown at 519, the user of the umbrella of 501 must additionally resist torque 509 leveraged as an uncomfortable twisting force on the wrist.
As this illustration demonstrates, umbrella canopy improvements may be of particularly significant value with a corresponding change in the support structure, pole and handle. Canopy improvements described herein must therefore be considered in the context of various possible support structures and handle locations.
A rain umbrella must also effectively manage droplets of rainwater that fall on its canopy surface. A conventional rain umbrella has a contoured canopy, which enables water droplets to gravitate outward and downward toward the canopy edge where they fall off of the canopy. Rain droplets may gather or be pushed laterally along the canopy surface by wind, but ultimately they fall off the canopy at its edge.
Even when a user is shielded effectively from falling raindrops, the runoff of water droplets at the edges of an umbrella is problematic. The user and bystanders may be subjected to dripping of runoff at all edges of the canopy perimeter.
In windy conditions, water droplets falling off the canopy are blown onto the user, compromising the protected area below the canopy. Bystanders are also impacted, as water droplets that have been redirected to the canopy perimeter are blown into their path.
When the user walks or runs, water droplets falling off the front portion of the canopy descend directly into the path of the user and compromise the protected area below the canopy. The user must adjust the canopy orientation to maintain suitable shielding.
Drag and lift are factors in umbrella design because an umbrella canopy interacts with aerodynamic forces resulting from the wind. To deal with the effects of the wind on the canopy, the user adjusts the position of the canopy. The range of possible positions is limited by the requirement that the user be protected from the rain.
Because of the canopy's instability in windy conditions, the user of a rain umbrella typically negotiates a balance between a canopy orientation that provides shielding from rain and wind—the umbrella's primary purpose—and a canopy orientation that prevents the underside of the umbrella from being exposed to the wind and otherwise minimizes forces of drag and lift acting to destabilize the umbrella.
A conventional umbrella is a badly behaved airfoil. Elements of a well-functioning airfoil are distinguished by promotion of laminar airflow from leading edge to trailing edge; by an upper surface and lower surface dominated by friction drag rather than pressure drag; and by upper and lower surfaces contoured to produce lift for a particular purpose. Conversely, the conventional umbrella has a sharp leading edge which promotes high-drag turbulence rather than laminar flow; a highly contoured canopy which produces a high-drag pocket of back-pressure in the under-canopy region behind the sharp leading edge; a high-drag bluff shape dominated by pressure drag as air is forced against its windward surface while a low-pressure wake forms aft of its leeward surface; and poor use of lift to improve directional stability or provide a force advantage experienced at the handle. In particular, a conventional umbrella is incapable of responding to wind as a functional single surface airfoil.
A conventional umbrella's rain shielding ability is especially disadvantaged by its aerodynamic deficiencies. An extreme example helps visualize this suggestion. In this example, an umbrella has a canopy of conventional dome shape, with an oversized, 8-foot diameter. The user of this umbrella is holding the umbrella parallel to the ground-plane, in the generally preferred orientation for low wind conditions. The canopy is subject to a headwind and raindrops approaching at the same inclination as the headwind. Although the umbrella user is completely shielded from the raindrops without having to reorient the umbrella, the headwind remains problematic. To deal with the headwind, the user pitches the umbrella to face the headwind wind to reduce torque on the handle resulting from the drag and lift resulting from the interaction between the canopy and the headwind. This example suggests that an umbrella user may pitch the umbrella in response to a particular aerodynamic force, not simply to maintain protection from falling rainwater.
The conventional rain umbrella has many other severe shortcomings. The under side is concave and, if accidentally exposed to wind, acts as a parachute. As air is captured, pressure increases on the under side. Even in moderate wind conditions, pressure on the under side may be substantial, and may result in the umbrella tipping up and exposing the user to the rain or even in tearing or reversal of the canopy or breakage of the support structure.
A conventional umbrella whose canopy is positioned edge-on to the wind subjects the smallest area to the wind and therefore has lower resulting drag by comparison with to other orientations. Unfortunately, in this orientation, the canopy's sharply defined edge leaves the under-canopy region susceptible to exposure and the canopy to the tipping up resulting from such exposure. Such problems are compounded when a user walks or runs. Headwind acting on the upper side results in a force perpendicular to the pole, and is torqued on the handle below.
Conventional umbrella canopy 521 as shown at
If the front edge of an umbrella is pitched upwards as shown at 531, the under-canopy region is exposed at 533. An increase in pressure on the under side at 535 pushes the under side upwards at 537. The combined effect of high-pressure in the under-canopy region, downward force 539 as air is redirected off of the upper side at 541, drag on the canopy, and turbulence produced as airflow is separated by a sharp canopy edge, exert an unpredictable force on the pole. This force is torqued on handle 543. Resistive force applied by the user at the handle stresses the support structure, and can cause reversal of, or damage to, the canopy.
To compensate for this problem, the user of a conventional umbrella must carefully adjust the orientation of the canopy's leading edge. In an edge-to-the-wind orientation, the under side is susceptible to exposure, so the user generally compensates by pitching the upper side towards the wind. The resulting choice of orientations to handle aerodynamic forces may not be the most optimal for protection from falling raindrops.
The most stable orientation of a conventional umbrella in moderate wind is one that disposes the umbrella's upper side towards the wind, as shown at 545. This orientation is effective because a) the umbrella has some stability as its symmetric, convex upper side is centered on the wind; b) the concave under side is protected from exposure and c) the handle is on axis with force acting at the center of pressure so the user is not subjected to torque leveraged by the pole.
Unfortunately, when the upper side is held in its most stable orientation to the wind, the upper side's largest area is exposed to the wind's direct attack, resulting in maximum pressure and maximum drag. A corresponding increase in resistive force by the user on the umbrella handle is required to counter the effects of drag. These opposing forces produce significant stresses on the canopy, support structure and pole.
Slight changes in wind direction, or slight changes to orientation made by the user, cause the canopy to be pushed aside. The canopy handle, distanced from the center of pressure of the canopy, requires torqued force to restabilize the deflected canopy. As the canopy is pushed aside, torque at the handle increases. This torque must be resisted using additional wrist strength.
To compound these problems, when the upper side of a conventional umbrella is pitched to face wind, a large portion of the upper side serves no protective purpose while contributing to stability problems resulting from drag.
Visibility is also impaired. When the umbrella is pitched forward to face approaching wind, the front-facing view of the user is obstructed as the canopy is lowered directly in front of the path, presenting an extraordinary and unnecessary risk to this user and other pedestrians. This is a severe shortcoming of a conventional umbrella.
U.S. Pat. Nos. D0359614 and D0390696 describe umbrellas with a transparent window that may improve visibility. The transparent windows of these umbrellas provide enhanced protection from rain, but would be disadvantaged in windy conditions by pressure drag resulting from the inefficient displacement of aerodynamic forces acting on the exterior surfaces of their respective canopies and by the capture of air under their respective canopies.
U.S. Pat. No. 5,642,747 describes a hand-held aerodynamic umbrella that employs a stabilizer to direct the orientation of its asymmetric canopy. The canopy of this umbrella pivots about the yaw axis as directed by the stabilizer. With a pivoting canopy, this umbrella is able to adapt to winds from varying directions. The umbrella has a sharply-defined leading edge and is thus subject to being tipped up in the same manner as a conventional umbrella. Furthermore, because the umbrella of U.S. Pat. No. 5,642,747 pivots around a fixed point like a weathervane, the user and bystanders must interact with a canopy that continually changes its orientation relative to the user.
With respect to lift, the umbrella of U.S. Pat. No. 5,642,747 teaches a lateral portion of the canopy that causes a slight upward lifting effect on the front of the canopy. A lifting effect on the front of the canopy, forward of the handle, results in a torqued force on the handle that directs the top of the umbrella handle rearward. This particular force is unhelpful and uncomfortable on the umbrella user's wrist, because the direction of torque caused by this lifting effect is the same as the direction of torque caused by drag on the canopy, stabilizer and lateral side portions. Rather than helping the user counter torque produced by drag on the canopy, stabilizer and lateral portions, the upward force on the front of the canopy introduces additional torqued force on the handle.
An illustration of such a lift disadvantage of the umbrella of U.S. Pat. No. 5,642,747 is shown at 547 in
An article at http://www.gizmag.com/go/3967/ describes an umbrella called a “Lotus 23” by inventor Andy Wana. This umbrella has a canopy of amorphous shape, capable of flexing in response to aerodynamic pressure. The Lotus 23 does not offer a minimally protective area for the user in strong wind, nor does it ensure a deformed canopy resulting in low-pressure drag, or an upper side dominated by friction drag. The flexible canopy of this umbrella is unrestrained from blowing into the user, up over the pole top, or flattening onto the pole.
A conventional umbrella and the umbrella of U.S. Pat. No. 6,196,244 are capable of some deformation and restoration due to aerodynamic forces. Both umbrellas have ribs that are cantilevered from either a central point or a point of juncture with struts. Both have ribs with points of varying flexure outwardly from a central hub and outwardly from a cantilevered point at a connection with support struts. When force is applied to the canopy of these umbrellas, the underlying ribs flex with increasing displacement possible in proportion to their respective distance from their fixed, cantilevered point.
The umbrellas of the prior art do not provide any particular deformation in response to aerodynamic force by which a low-drag advantage is achieved. Pressure on a windward surface of the canopy of these umbrellas presses the surface towards the user, flattening the windward surface of curvature and increasing the angle of attack of wind to this surface, resulting in an increase in pressure drag. This effect occurs in part because the ribs, by attachment to the perimeter of the canopy, are prevented from spreading apart at the perimeter of the canopy. It also occurs in part because no underlying structure exists to ensure a canopy shape that is both low in pressure drag and offers good protection from falling raindrops.
As shown in a top view of conventional umbrella 561 in
It is an object of the invention disclosed herein to provide an umbrella with a canopy shape so as to adequately shield the user from raindrops; to be lightweight and manageable as force is exerted by the user on the handle; and to provide stability about the canopy's yaw, pitch and roll axes to help sustain a manageable orientation. Further objects of this invention are to provide a low-drag canopy shape, a canopy that is designed to prevent accidental exposure of the under-canopy region, and a canopy capable of releasing air pressure in the under-canopy region.
The object of the invention is achieved by an umbrella whose canopy has an edge that presents a convex surface to an airflow that strikes the edge, the convex surface acting to substantially increase controllability of the umbrella by a user who is holding the umbrella by its pole.
In other aspects of the invention, the entire edge of the canopy presents the convex surface to the airflow, the convex surface deflects the airflow away from the canopy's under side, and the convex surface deflects the airflow such that the canopy becomes a virtual double-surfaced airfoil. A first portion of the canopy's edge presents the convex surface to the airflow and a second portion which is opposite to the first portion does not present the convex surface to the airflow. The canopy may have a streamlined form, with the first portion of the canopy's edge being at the head of the streamlined form and the second portion being at the tail of the streamlined form. The convex surface may also serve to deflect the airflow away from the user of the umbrella.
In still other aspects, the canopy may include a spoiler that acts on the airflow across the canopy's upper side. The spoiler may be a microspoiler. The canopy may also include a windsock that inflates to release air pressure under the canopy and otherwise collapses. The canopy may also include a gutter for rainwater. The gutter may be a plurality of microgutters and the direction in which the water flows because of the gutter may lead to an escape chute for the water. The gutter may further function as a spoiler.
In a further aspect, the object of the invention in achieved by a canopy for an umbrella that includes a non-deformable area and a deformable area which is capable of being deformed to give the canopy a shape that improves controllability of the canopy by a user of the umbrella with regard to a flow of air passing over the canopy. The deformable area is deformed such that the edge of the canopy which is the leading edge with regard to the flow of air presents a convex surface to the flow of air. The deformable area is further deformed such that the canopy has a streamlined shape with regard to the flow of air. Deformation of the canopy may be done by a user of the umbrella or the canopy may deform itself in response to the flow of air.
Reference numbers in the drawing have three or more digits: the two right-hand digits are reference numbers in the drawing indicated by the remaining digits. Thus, an item with the reference number 203 first appears as item 203 in
As an object interacting with wind, a conventional umbrella may be defined and improved according to its aerodynamic properties. An understanding of the dynamics of low-speed airflow around moving bodies has helped produce optimal designs for bike helmets, flying discs and model airplanes.
In the field of low-speed aerodynamics, spherical and cylindrical shapes are known as bluff body shapes, dominated by pressure drag distinguished by a high pressure region on the windward side and a low pressure wake on the leeward side. Objects that are dominated by friction drag rather than pressure drag are considered streamlined. To maintain canopy position or to make forward progress while walking, the umbrella user must resist drag by applying a counter force on the handle. Depending on the position of the handle with respect to the center of pressure, forces of drag may be leveraged by the umbrella pole around the handle. For this reason, drag is a critical consideration in the design of an optimal canopy shape.
Stability is also a critical factor in the design of an optimal canopy shape. The user of a conventional umbrella often struggles to control the canopy in the wind. Aerodynamic forces of lift may be used to aid in control of the canopy by changing the center of pressure with respect to the handle.
While a canopy shape with low drag and high stability are desirable in any kind of umbrella, the primary purpose of a rain umbrella is to shield the user from falling raindrops. The flow of rainwater and the release of air pressure in the event of accidental exposure of the under side to high air pressure are critical to the success of a reshaped canopy, especially since a streamlined canopy may exacerbate problems generally accepted on a conventional umbrella. For example, rainwater dripping from the edges of a narrow, elongated canopy is much more problematic than rainwater dripping from the edges of a large, dome-shaped canopy.
In the design of an improved umbrella, other criteria must be considered. A shape designed to perform well in headwinds must be balanced by an expectation that wind come from other directions. Umbrella weight and scale are critical factors in evaluating performance. Lastly, it is important to consider existing manufacturing processes in the development of an improved design.
A gutter facilitates the flow of raindrops under the influence of gravity toward one or more desired release locations aft of the canopy's face-plane, where raindrops fall to the ground. Multiple gutters may be implemented to improve management of waterflow in heavy rain and to improve handling of waterflow as the canopy is held in various inclinations. Water moved from the exit of one gutter may drip into another gutter to achieve a complete transfer to the desired release location.
In the present context, a gutter is any arrangement in the canopy which alters the normal flow of water on the canopy. Kinds of gutters disclosed in the following include gutters that provide channels in which the water flows and gutters that provide guides for the flow of water. The former are termed in the following hard gutters, though they may be made of flexible materials, and the latter are termed soft gutters. A gutter may be made up of one or more hard gutters and/or soft gutters and may direct water to a rainwater escape chute. The combination of gutters and/or escape chutes in a canopy may form a system for moving water from fore to aft of the umbrella's face-plane and toward one or more desired exit locations aft of the face-plane.
A hard gutter is a channel that captures and directs raindrops until they are released at an exit location at any point on the canopy surface. The hard gutter is distinguished by a retaining wall, functioning as a groove in which raindrops are captured and channeled. The upper edge of a retaining wall may have points or portions attached to the canopy to provide structural stability and to reduce drag on the canopy surface. The retaining wall may be formed using the canopy material, or by attachment to the canopy surface.
The retaining wall and channel of a hard gutter may be substantially above the upper side, below the under side, or integrated as a seamless pocket into the canopy.
A hard gutter, constructed substantially above the upper side is shown at 601 in
As shown at 701 in
As shown at 801 in
An internal hard gutter may be covered on the upper side by a mesh, screen or other permeable membrane. As shown at 813, a screen is stitched into the canopy surface, allowing water to run down into the hard gutter while maintaining tension on the fabric of the upper side.
The hard gutter of the umbrella shown at 821 is similar to the mesh covered hard gutter 813. This gutter uses canopy fabric to form a series of holes as entrances to the channel beneath the surface. As shown at 831, raindrops enter these holes, and flow along a channel beneath the canopy. An enlarged view of region 833 is shown at 841, which depicts the hole and the underlying channel. A side view of region 841 is shown at 851, illustrating the pouch-like construction of the channel. This example of a hard gutter allows for greater canopy fabric tension than hard gutter 813. It may be paired in parallel with another hard gutter with staggered holes to capture water running between the first row of holes.
A soft gutter is made up of contoured bumps, indentations or ridges on the upper side that guides raindrops towards an exit location without capturing the raindrops in a channel. Unlike a hard gutter, a soft gutter does not present a retaining wall in opposition to the canopy surface. A single raindrop may flow over or around a soft gutter. A soft gutter may be formed from the existing canopy surface, or may exist as part of an attached accessory.
As shown at 901 in
One form of the soft gutter is the microgutter. A microgutter is a bump, ridge, indentation or track that serves as part of a system that facilitates the movement of rainwater along the canopy towards a desired exit location. A number of microgutters together produce a finely textured surface, herein referred to as a microgutter system, that functions to redirect water towards a desired location on the canopy. A microgutter system may resemble a set of ribbed, parallel tracks as shown at 931 in
Each individual bump, ridge, indentation or track of a microgutter system may be of any length across the canopy surface, but may have height and width at a fraction of the radius of a single raindrop. A single raindrop is likely to flow over and around a single microgutter while being redirected towards the desired location. Raindrops 935 are directed towards a desired exit location aft of the canopy. Along the way, raindrops 939 flow over the microgutter system and off the canopy before they reach the desired exit location. Many raindrops, as shown at 937, flow toward the exit location and fall off the aft-section of the canopy.
Microgutters are especially useful at the front of the canopy, aligned generally in parallel to the longitudinal plane. A microgutter system of this type adds little drag to the canopy while using aerodynamic forces to direct raindrops upward and to a location higher on the upper side. At a higher point, gravity functions to deposit these raindrops into a downward-sloped soft or hard gutter for eventual release at the exit location.
In a preferred embodiment as shown at 941, microgutter system 943 is a series of parallel tracks running from the front of the canopy at 945 to the rear. Two symmetric hard gutters 947 and 949 run along side-halves of the canopy to rainwater exit locations at the rear of the canopy. A falling raindrop hits the canopy at front lower canopy point 951, and is pushed upward along the microgutter tracks by wind. Downward gravitational force overcomes upward aerodynamic force at point 953 and the raindrop falls over the microgutter system into hard gutter 949 for transfer and release aft of the face-plane, at exit location 955.
As discussed in more detail later, hard gutters, soft gutters and microgutters may serve a dual purpose, functioning as spoilers to increase or decrease lift, or to facilitate laminar airflow over a thin layer of turbulence.
A rainwater escape chute is an enclosed pathway or tube used to carry rainwater to a defined exit location away from the canopy and user. Unlike a hard gutter, a rainwater escape chute is enclosed along its length, with openings at either end. A rainwater escape chute may exist above the upper side, beneath the under side or integrated between the upper side and under side.
The rainwater escape chute has an opening portion, an enclosed rainwater transfer tube and an exit portion. The opening portion may be funnel-shaped to improve rainwater capture along a wider area of the canopy.
As shown at 1001 in
The rainwater escape chute may be constructed as an extension of the canopy fabric, or as an attached accessory. The rainwater escape chute may require independent support members, or supported by an extension of the canopy's ribs.
Hard gutters, soft gutters and rainwater escape chutes may be combined to form a complete gutter from fore to aft of a canopy.
The guard flaps of this invention are shields that extend downward from the canopy perimeter, improving protection from rain and wind, and improving visibility in foul weather. Guard flaps are symmetric with respect to the vertical plane of the roll axis.
Guard flaps may be attached to the canopy so as to be substantially indistinguishable from a unified component. Alternatively, guard flaps may be attached as a distinctly separate element of the canopy.
As shown at 1101 in
As shown at 1131, the front portion of guard flaps 1133 and 1135 may be joined together below the fore-section of the canopy to form a convex surface. As shown at 1141, the resulting canopy and guard flaps form a convex surface The convex surface deflects wind away from the body of the umbrella user. This deflection both protects the user and results in lower pressure drag on the user's body.
Guard flaps, or a portion thereof, may be constructed using transparent material to improve visibility in foul weather.
Guard flaps may be constructed of a stiff material, or may have a skeletal support structure, or may be held taut by the application of opposing force on two or more edges.
Guard flaps may be supported by one or more guard flap rib members integrated at the perimeter of the canopy as extensions of existing ribs for manual or automatic deployment or retraction. The flaps may be automatically deployed and retracted when the umbrella is opened and closed.
Guard flaps and support members may be stored in a pocket along the canopy perimeter, and released in foul weather.
In an umbrella of heavy-duty construction suitable for storm conditions, the guard flaps may be entirely detached from the canopy. The guard flaps would be adjoined to the canopy using a zipper or similar method, attached for foul weather protection and removed for normal conditions.
Guard flaps may extend downward, making contact with the ground. When used in combination with a telescoping extension of pole and means to secure the pole such as a tripod or base, the canopy and flaps can provide a freestanding protective area, suitable for shielding a substantial portion of the user's body.
Alternatively, guard flaps may be extended towards, or fastened to, a portion of the user's torso, creating an enclosed interior dome. The hand-held pole of this embodiment may be complemented, or replaced, by one or more support poles attached to the user's body to reduce dependence on the user's arm.
A windsock facilitates the release of increased air pressure in the under-canopy region. The windsock is manufactured as part of the canopy, or as a separate attachment. The components of the windsock include a base portion that meets a corresponding hole in the canopy, a sheath that captures and redirects airflow, and an exit location in the sheath for the release of air. The sheath of a windsock is made of fabric, or similar material that allows for an inflated state and a collapsed, deflated state.
The windsock functions as a valve, allowing for the release of air pressure away from the under-canopy region while preventing the entry of raindrops into the under-canopy region.
When air pressure in the under-canopy region increases, the windsock inflates and allows air to exit, thereby lowering air pressure under the canopy. Pressure in the windsock, exerted upwards towards the windsock exit, prevents raindrops from entering the windsock.
When air pressure in the under-canopy region is lower than or equal to air pressure on the upper side, the windsock is deflated, folding onto the upper side. In the deflated position, raindrops are unable to enter the windsock because the windsock is folded over onto the canopy.
As shown at 1201 in
When air pressure is reduced in the under-canopy region of umbrella of 1221, windsock 1223 begins to collapse. When air pressure on the under-canopy region reaches equilibrium with air pressure above the canopy, the windsock is completely collapsed as shown at 1231. In this completely collapsed position, the windsock folds over the opening in the canopy, acting as a valve to prevent the entry of raindrops.
The windsock shape may be further refined to prevent the entry of raindrops. For example, the exit location of the windsock may be protected by the addition of a shield, valve or cap.
As shown at 1241, multiple windsocks may be implemented about the canopy to further reduce air pressure under the canopy. The windsocks are shown in an inflated position, with air escaping from multiple chimney-like tubes. A similar arrangement of windsocks in a deflated state is shown at 1251.
In a preferred embodiment of this invention, the windsock is integrated as part of the canopy fabric into a design that provides adequate air release while minimizing drag on the windsock surface. As shown on the canopy at 1241, tubular windsock 1243 follows the contour of the upper side as shown at region of juncture 1245.
As shown at 1301 in
A windsock may be attached to the canopy along the length of the sheath. In this embodiment, the windsock is integrated into canopy fabric to create a seamless air entry opening, sheath and air exit. As shown at 1311 in
As shown at 1321, air 1323 enters the under-canopy region and is pressured into air entry opening 1325 (ordinarily not visible from above as shown). Because sheath 1327 is attached to the canopy, air captured within the sheath is forced to change direction at towards exit opening 1329. Such a change in the direction of airflow, if forced by a tapered tube, vent or fabric pocket would ordinarily produce unwanted friction and a substantial increase in air pressure within the confined space, counterproductive to the objective of a rapid release of air pressure under the canopy. To prevent such a buildup of air pressure, the billowing capacity of sheath 1327 and the size of exit opening 1329 may exceed the capacity and size of entry opening 1325.
A completely integrated windsock sheath is shown at 1331, as viewed from under the umbrella. Air 1333 is pressured into entry opening 1335 and moves through sheath 1337 to air exit 1339. In this embodiment, sheath 1337 is completely integrated into the canopy as an extra layer of fabric. In its deflated state, a sheath as shown at 1337 may collapse to a flattened state so as to be substantially indistinguishable from the canopy surface. In the example shown at 1337, moderate pressure redirects air towards the exit. In a high-pressure state, the sheath's ability to rapidly unfold or billow allows for quick release of air pressure under the canopy while changing the direction of airflow towards the exit. In this regard, the bottleneck of air pressure may be at the opening 1335, not within the sheath or exit.
As shown at 1401 in
Aerodynamic forces acting on an umbrella canopy are significant enough to consider the effects of drag, lift and turbulence on the canopy. Spoilers may be used to alter the aerodynamic performance of an umbrella.
The spoiler of this invention is a surface that is attached to the upper side or under side at an inclination different from that of the canopy surface. The spoiler may be integrated as a seamless part of the canopy fabric, but exists substantially on the surface of the canopy such that the canopy surface continues on either side of the spoiler.
Air moving over a surface at a higher speed than under the surface creates lift. A spoiler creates turbulence by disturbing or “spoiling” airflow along a surface, thereby shifting the center of lift.
A spoiler may be employed to displace air in one direction while producing pressure in an opposing direction. For example, a spoiler on a racecar improves traction by reducing lift and producing downward pressure on the rear of the vehicle.
A spoiler may be employed to form an aerodynamic shape with low drag. Drag on the rear of a moving body may be caused by the creation of a low-pressure void, or recirculation bubble, in the wake of air moving over the sides of this body. The arc of a conventional umbrella canopy is highly cambered and poorly suited to promote or maintain unseparated airflow across its surface. As airflow separates away from the upper side surface, a separation bubble is formed on the leeward side of the upper side. The resulting drag on the canopy is significant. A spoiler may be employed to disrupt the airflow that otherwise would contribute to the creation of the low-pressure wake, resulting in lower drag.
A spoiler may also be employed to form an aerodynamic profile with low drag by functioning as a trip wire. A trip wire perturbs laminar airflow along an object surface, forming a thin turbulent layer between the skin and the high-velocity layer of moving air. Examples of trip wires, also referred to as microspoilers, are the indentations on a golf ball and the fine ribbing circumscribed on the top of the flying disc disclosed in U.S. Pat. No. 3,359,678.
Each of these advantages of a spoiler may be applied to an umbrella. A spoiler may improve stability about the handle by changing the center of lift; or may disrupt the low-pressure wake caused by the umbrella's bluff shape to create a low-drag umbrella; or may be implemented as microspoilers in the formation of an unseparated boundary layer to reduce resulting drag as a thin turbulent layer creates a buffer between the canopy surface and the high-velocity airstream.
The user ordinarily applies an opposing force to the canopy through its support structure in order to counter the combined effects of lift and drag on the canopy. An undesirable upward lift on one portion of the canopy may be countered by downward pressure on another portion of the canopy surface. Downward pressure exerted by a spoiler may be leveraged against the support structure to raise the canopy on the opposing side.
As an umbrella interacts with aerodynamic forces, a small reduction in resulting drag may present a substantial improvement in umbrella control because drag is torqued on the handle by the pole.
The simplest effect of a spoiler is illustrated by comparison of the conventional umbrella with a raised handle described as prior art, shown at 511 in
For the purpose of this comparison, it is assumed that the only difference between the umbrellas of 511 and 1551 is the spoiler on canopy 1553. The headwinds are identical, and if canopy 1553 did not have a spoiler, the canopies would have the same resulting drag.
By the addition of spoiler 1555 to canopy 1553, some new drag from the spoiler results. This drag could be considered a disadvantage in that it must be resisted at the handle. The spoiler is inclined upwards and aft-wards, and redirects the headwinds upward, producing a downward force on the front of the canopy. This downward force on the front of the canopy may produce a stability advantage that actually outweighs the disadvantage of added drag.
Headwind 513 slightly pitches canopy 517 around handle 515, resulting in a torquing force as shown at 519. Headwind 1559 is redirected by spoiler 1555 to produce a downward force on the front of the canopy. This downward force produced by the spoiler, experienced as a forward pitching at the handle, produces torque at the handle in counter-rotation to torque produced as a result of drag. The spoiler's forward torque on the handle helps counterbalance the canopy's normally aft-ward torque on the handle. As indicated by the resulting force shown at 1561, the spoiler may exert some increased pressure on the handle, but the torque advantage may outweigh the force disadvantage. An umbrella user is more capable of controlling a canopy by applying a nominal pushing force on the handle rather than trying to resist leveraged torque.
Spoilers may be constructed as an extension of existing canopy fabric, or as an attached component. Spoilers may be constructed using a material of particular low-friction qualities, for example smooth plastic.
One or more spoilers may have a dual use as tensioners or dampeners to improve structural integrity and performance. For example, when fabric portions of the canopy are exposed to wind, a resonance of low and high-pressure areas may result in flapping or vibration. One or more spoilers may be implemented to dampen such a condition. In another use, spoilers running laterally across the under side region could provide tension between opposing ribs to reduce canopy deformation.
Gutters may be used in combination with spoilers. For example, a spoiler running along the side of a canopy in an upward inclination from fore to aft may move rainwater to a forward point, where a gutter may capture the water and move it to a rear exit location.
Gutters and spoilers may be integrated into the canopy surface so there is no obvious distinction in appearance. Alternatively, a gutter may serve a dual purpose as a spoiler, and vice-versa. For example, a microgutter system on the canopy's upper surface may have a primary purpose in moving raindrops to the rear on the canopy while acting as microspoilers to produce a turbulent, unseparated boundary layer resulting in a lower drag advantage, or acting to change the center of lift in order to reduce torque on the handle.
A purpose of the spoiler of the present invention is to help the user control the canopy at the handle by decreasing the torque on the handle. Such a decrease in torque may be effected by a spoiler that produces a torque at the handle in counter-rotation to the torque produced by drag on the canopy. A spoiler at the front of the canopy may thus be expected to produce a downward force at the front of the canopy to produce a forward pitch in opposition to the rearward pitching force of drag.
The umbrella of this invention improves stability and performance by providing an aerodynamic leading edge at the perimeter of its canopy. An aerodynamic leading edge is a convex surface at an edge of the canopy. An aerodynamic leading edge shields the under side from exposure to high-pressure force; provides a range of angles of attack while protecting the under side; improves directional stability by providing lift in opposition to downward force on the upper side; reduces wind resistance on an upper portion of the user's body; promotes laminar flow around its rounded shape, with lower resulting drag; and presents a smooth, safe perimeter condition by comparison with the sharp edges and pointed rib ends of a conventional umbrella.
Problems at the edge of a conventional umbrella are described in the prior art section, and illustrated in examples of
The aerodynamic leading edge adds a lower-leading-surface to an umbrella. A lower-leading-surface is a surface of downward and inward inclination below the upper side of the canopy that improves aerodynamic performance and directional stability by providing a range of angles of attack, reducing turbulent airflow normally associated with the sharp edge of a conventional canopy. The aerodynamic leading edge also functions to promote laminar airflow on the upper side, allowing the canopy to function efficiently as a single-surface airfoil or parasail.
An aerodynamic leading edge may be used to promote laminar airflow across the under side, or may be implemented to redirect air downward and away from the under-canopy region. In either implementation, the under side is protected from wind directly approaching the lower-leading-surface and also from wind approaching a boundary of airflow under the canopy created by the lower-leading-surface. This boundary of airflow under the canopy may also form a virtual second surface of a double-surface airfoil. The virtual second surface of the streamlined airflow reduces instability, lowers the resulting drag, and diverts the direct attack of wind away from the under side.
A lower-leading-surface, if curved under the canopy and back upward for reattachment to the under side may be implemented to promote laminar airflow across the under side, allowing the canopy to perform as a streamlined single-surface airfoil.
As shown in an exploded view at 1651 in
View 1671 of the underside of the canopy reveals an exterior surface of aerodynamic leading edge 1673, curving below the perimeter of under side 1675.
Because the aerodynamic leading edge redirects the wind away from the under side, the under side becomes less susceptible to exposure to the wind and subsequent buildup of air pressure under the canopy. When the umbrella user positions the umbrella with an edge-to-the-wind orientation, the aerodynamic leading edge will promote streamlined airflow rather than introducing turbulence and instability. This gives the user improved control in the edge-to-the-wind orientation.
For an umbrella with a handle positioned near the canopy's center of pressure, or a handle aligned with the direction of force acting on the canopy at its center of pressure, the lower-leading-surface has other advantages regarding stability. Lift produced by the lower-leading-surface in response to the wind helps resist downward pressure from the wind on the upper side. The aerodynamic leading edge presents a streamlined form, balancing airflow above and below the canopy.
An umbrella interacting with a headwind is advantaged by a canopy having an aerodynamic leading edge, as shown at 1701 in
Slight upward or downward calibrations in canopy orientation do not easily expose the under side. For example, if the canopy is pitched slightly backward as shown at 1721, the aerodynamic leading edge at 1723 continues to redirect air away from the under-canopy region. Headwinds in direct contact with the lower-leading-surface at 1727 continue to shape a virtual boundary that prevents headwinds shown at 1725 from directly entering the under-canopy region. As demonstrated at 1701 and 1721, the range of orientations that are possible without exposing the under side provides the umbrella user with added stability.
For a canopy that would be expected to manage wind approaching from all directions, a lower-leading-surface would be useful along the entire underside perimeter of the canopy. In a preferred embodiment of an aerodynamic leading edge, the lower-leading-surface tapers off from the fore-section to the aft-section as shown in 1701. Such a configuration is termed herein a canopy nose and will be described in detail later.
As defined, a lower-leading-surface has a downward and inward inclination, away from the top-plane and toward the yaw axis. While a lower-leading-surface has downward and inward inclination, its surface exposed at the outer perimeter of the canopy may be of positive, negative or no curvature as shown at 1751, and in enlarged views of cross-section 1753 shown with positive curvature at 1755, negative curvature at 1757 and no curvature at 1759.
Side cross-sectional views of four example umbrella canopies with various aerodynamic leading edges are shown at 1761. Here, each canopy view is a vertical cross-section at the longitudinal plane. As shown at 1763, convex aerodynamic leading edges exist on either side of this canopy, perhaps running around the entire canopy perimeter. As shown at 1765, an asymmetric implementation of a convex aerodynamic leading edge is shown with a positive external curvature that extends inward and upwards towards the upper side. As shown at 1767, an outwardly sharp leading edge, similar to the sharp edge of a conventional umbrella, may exist on the canopy at a separate location from aerodynamic leading edge 1765.
The lower-leading-edge may continue in curvature for reattachment to the under side, as shown at 1769 and 1771. By attachment to the under side, the lower-leading surface may thus function as the undersurface of a double-surface airfoil. The pocket formed by reconnection of the lower-leading surface to the under side is similar in advantage to the luff pocket or sleeve used on boat sails to prevent the backflow of air behind the mast, with lower resulting drag. The reattachment of a lower-leading edge to the under side may also promote unseparated airflow along the under side, with all the associated benefits of a cambered, two-surface airfoil. As shown at 1771, the aerodynamic leading edge leads under and upward to the under side with a slight negative curvature.
In the fourth example cross-section of an umbrella with an aerodynamic leading edge, upper side 1773 is the first surface of a complete two-surface airfoil, with separate first and second surfaces from leading edge to trailing edge. In this example, lower-leading-surface 1781 curves under the canopy and is joined at the opposing perimeter edge of the upper side at 1783. This undersurface creates the second surface of the two-surface, cambered airfoil. The undersurface has exterior surface 1775 facing the under-canopy region and umbrella user, and has an interior reverse surface 1777 facing underside 1779 of canopy 1773. This undersurface may be structurally supported by the extension of existing rib members; or by the addition of new rib members; or by upper side tension around the perimeter of the undersurface; or by inflation through the addition of air intake slots as on a parafoil. Having the aerodynamic characteristics of a double-surface airfoil, an umbrella of this type may produce sufficient lift and minimal pressure drag to achieve combined advantages of an umbrella and flying wing. Such an umbrella-airfoil may be manufactured, for example, as a beach amusement that combines the scale, portability, structure, collapsibility and sun-protection function of a beach umbrella with near-airborne thrills as its user runs along the sand to produce and experience the force of lift.
Lower-leading-surfaces may be joined to one another at an acute angle to form a vertical wedge, or along a surface of curvature to form a smooth transition. As shown at 1791, canopy 1793 has two lower-leading-surfaces 1795 and 1797 joined at distinct, vertical edge 1799. Air approaching this wedge is sharply separated on either side of edge 1799 and directed according to the particular inclination of the lower-leading-surface. Although a wedge-shaped juncture may result in some instability about the yaw axis as air is forced on either side of the edge, an advantage may be achieved by the deflection of air away from the user's body. An exploration of this type of improvement is described further with respect to the present invention in a section regarding the canopy nose.
An aerodynamic leading edge may be formed by fabric attachment to extensions of existing canopy rib ends to match the inward contour of the lower-leading-surface; or by attachment of additional support members to form the lower-leading-surface; or by attachment of a distinctly separate surface of self-supporting material such as a plastic; or formed using tension between opposing canopy edges to stretch the lower-leading surface into the under-canopy region.
The contoured perimeter presented by the aerodynamic leading edge and the corresponding inward curvature of underlying ribs with hidden rib endpoints enable the umbrella of this invention to present a softer perimeter condition than the sharp edge and pointed ribs of a conventional umbrella. This softly contoured edge condition offers an important safety advantage, and allows for an umbrella to be manufactured for safe use by children and adults in urban environments walking in close contact with one another.
An aerodynamic leading edge may be formed with a flexible lower-leading-surface that would adapt in response to wind to curve under the canopy. Without the pressure of wind on its surface, this adaptive lower-leading-surface would be functionally indistinguishable from the perimeter of the canopy's upper side. In response to wind, the lower-leading-surface would flex to curve under the canopy, functioning as an aerodynamic leading edge.
Aerodynamic leading edges of various shapes may be combined. An upper side's entire edge or select portions thereof may have an aerodynamic leading edge. An aerodynamic leading edge may serve other functions, for example, it may serve as a portion of a gutter. An aerodynamic leading edge may be constructed using canopy material so as to provide a seamless construction with the canopy. Alternatively, an aerodynamic leading edge may be constructed using a material of substantial smoothness, such as plastic, to reduce friction. An aerodynamic leading edge may be joined with the canopy using glue, seaming or other attachment method.
A number of reasons exist for considering asymmetric improvements to an umbrella. These include the fact that the user's line of sight is front-facing; the user has a forward stride; and the user cannot wield the umbrella to the rear of the body as easily as he or she can wield it to the front. It is also clear that an umbrella user makes complex choices in the use of an umbrella. For example, a user may choose a particular path, tack and stride speed according to direction and speed of wind and rain. The user's choices are often dictated by the limitations of the canopy, providing protection while allowing the umbrella to be held comfortably. If an umbrella is unwieldy in strong winds, the user chooses a safe tack towards a particular destination. Over the life of an umbrella, the umbrella is far more likely to be wielded in some positions than in others.
Because umbrellas are wielded asymmetrically from fore to aft according to the approach of headwinds, improved management of headwinds are considered by the present invention.
When using an asymmetric umbrella, the left and right side-halves of the canopy are held aloft respective to the left and right sides of the user. The side-halves are typically disposed horizontally to the ground-plane. As wind or rain direction shifts away from a headwind attack, it is expected that the umbrella user will maintain a fairly constant pitch and yaw while adjusting roll and translational offset, effectively raising one side-half and lowering the other, while shifting the umbrella left or right.
A canopy nose is an asymmetric example of an aerodynamic leading edge. A canopy nose is a surface of curvature inward and downward at the front of the canopy, joining an umbrella's upper side in the fore-section of the face-plane and tapering off along the edge of the side-halves.
As an asymmetric implementation of an aerodynamic leading edge, the canopy nose offers number of advantages to an umbrella. These include improved protection of the under side from direct exposure to headwind; improved forward-directional stability in the elimination of a turbulent-inducing sharp edge; promotion of laminar airflow over and under the canopy; and control of the canopy over a wide range of angles of attack. All of these advantages make it easier to manage the umbrella. Visibility is also improved because the user is no longer required to lower the canopy to protect the under side from exposure.
A canopy nose promotes laminar flow of headwind across the upper side. A canopy nose may be implemented to promote laminar flow across the surface of the under side or may divert air away from the under side. In either case, a boundary layer of air is created under the canopy. This boundary layer acts as the second surface of a virtual double-surface airfoil, streamlining airflow while diverting wind away from direct attack on the under side. Lift produced by laminar airflow across an extended aft-section of a canopy may be used to reduce net torque on the umbrella handle by producing torque in counter-rotation to torque resulting from drag on the canopy.
A canopy nose is an aerodynamic leading edge, forming a convex cone, wedge or rounded surface of inward curvature at the front-most area of a canopy, forward of the face-plane and substantially symmetric on either side of the longitudinal plane.
A canopy nose has a number of unique components. The canopy nose is an aerodynamic leading edge at the fore-section of the canopy, providing a downward and inward sloping portion below the upper side. The canopy nose has an upper-leading-surface, leading-edge-rim and lower-leading-surface. Example canopy nose shapes are shown at 1801, 1811 and 1821 in
As shown at 1803, 1813 and 1823 in
Canopy nose shapes may be more or less pronounced in curvature than these examples, depending on intended use. A conventional canopy might benefit from a canopy nose with a relatively small radius of inward curvature as shown at 1831. Two highly pronounced examples of canopy nose side profiles are shown at 1841.
The canopy nose is capable of directing headwind upward and over the upper side; and downward and away from the under side; and laterally to either side, away from the centrally located user. While increasing efficiency of a front-facing approach, the canopy nose may be shaped to contribute only a negligible addition of drag when the canopy is exposed to winds arriving from other directions.
As described earlier and illustrated at 1791 in
As describer earlier regarding an aerodynamic leading edge, the leading-edge-rim of a canopy nose may provide a smooth contour between the upper-leading-surface and the lower-leading-surface. As another possibility, the canopy nose may be shaped as a pointed or rounded snout. Further possibilities for a canopy nose are possible within the scope of the definition of an aerodynamic leading edge.
To improve control of the canopy nose over a range of angles of attack as the user attempts to maintain a front-facing approach in strong headwinds, either a vertical wedge-shaped, horizontal wedge-shaped or conical-shaped canopy nose will generally be moderated by some rounding curvature as seen at 1825 in
Although the canopy nose is generally symmetric with respect to the longitudinal plane, it may be modified to enable the attachment of an off-center pole. A pole and support structure may be combined with a canopy nose, or extend frontward of the canopy nose, without substantially compromising airflow. The canopy nose may be integrated with the pole to further streamline airflow. An example of a canopy nose with an asymmetric pole is shown in a front view at 1851.
The canopy nose may be constructed as a seamless extension of the canopy material, an integration of multiple materials, or constructed and attached to the canopy material. The canopy nose, or a portion thereof, may be constructed using a substantially smooth material, such as plastic, to reduce friction.
The aerodynamic leading edge of a canopy nose may extend along the sides of the canopy to improve handling of wind approaching from an attack parallel to the longitudinal axis. This extension may be tapered to a point of juncture with the upper side of the canopy.
An opening in the canopy nose may be possible to allow for an air current to pass into the under-canopy region, providing a streamlined contour along the under side for entry and exit of air from fore to aft, in order to reduce the effects of turbulence or pressure buildup in the under-canopy region.
The canopy tail is the portion of the upper side in the aft-section.
The canopy tail of this invention serves multiple functions. Its primary purpose is to shield the user from raindrops and wind conditions, primarily those that approach from a direction aft of the user.
Other functions of the canopy tail are to improve handling in windy conditions. These functions include acting as a vertical stabilizer about the yaw axis; acting as a horizontal stabilizer about the pitch axis; acting as a surface of lift as the canopy is shaped to promote laminar airflow in order to perform as an airfoil; aiding in creating a low-drag airfoil advantaged by a reduction in pressure drag and the promotion of friction drag on the leeward side of the upper side; and, if textured in combination with spoilers, aiding in creating a low-drag airfoil by promoting the formation of a thin, turbulent unseparated layer of air, as on a flying disc or golf ball.
Another function of the canopy tail is to provide a remote release location for water flowing through a gutter.
The upward force of lift created as air moves at a higher velocity across the upper surface of the tail-section may result in a useful production of torque on the umbrella handle, in counter-rotation to torque on the handle resulting from drag on the canopy. The net effect of this counterbalancing of torque at the handle is pitch stability in exchange for a nominal increase in force.
The canopy tail may be v-shaped, as a boat hull or inverted boat hull, to improve stability of the canopy about its yaw axis and to reduce flapping or vibration.
As shown at 1901 in
As shown at 1911, rainwater flowing along upper surface 1913 of a forked canopy tail may be diverted from entering the under-canopy region by the addition of gutter 1915. As shown in top view 1921, rainwater 1923 enters the gutter 1925 and flows towards desired exit location 1927 at the rear of the upper side.
Split-tail canopies as shown at 1951 and 1961 in
The canopy tail may have a downward surface of curvature extending it away from the yaw axis and canopy top-plane. This rear, downward curved portion would serve to produce lift on the rear of the canopy, as an aid to stabilizing the umbrella about its pitch axis.
The canopy tail may have a slight upward curvature, or include a slightly upward curved portion, to serve as a spoiler as air passes over the canopy, or as an aid in stabilizing the umbrella about its pitch axis.
For the purpose of this discussion, an umbrella is said to be streamlined if it is designed to reduce resistance to a flow of air across the canopy. One way of streamlining an umbrella's canopy is to give it the shape of a teardrop that is cut lengthwise by a planar or curved surface; another way is to replace edges with convex surfaces. These approaches can be combined in a teardrop shaped umbrella with a rounded canopy nose.
The dome-shaped canopy of a conventional umbrella is known in the field of low-speed aerodynamics as a bluff body shape, dominated by pressure-friction and distinguished by a high-drag low-pressure wake. An umbrella having an exposed under side and a user's body beneath is incapable of acting as an airfoil dominated by friction drag. The present invention employs a streamlined canopy shape to overcome this problem. At the same time, the present invention ensures that the canopy continues to provide protection from falling raindrops.
The conventional umbrella and umbrellas of prior art have canopy shapes which are either dominated by pressure drag, or are unable to assume a an orientation to the wind that is low in pressure drag or dominated by friction drag while still providing protection from falling rain. Umbrellas of the prior art do not have laminar airflow across the entire canopy while functioning to protect the user from rain and wind. A conventional umbrella promotes turbulent separation of airflow at the leading edge and at the crown-point, and also as wind moves aft of the widest spread across its sides. An umbrella with a substantially flat canopy promotes turbulent separation of airflow at the leading edge, and is poorly shaped to protect its user from rain and wind when the canopy is oriented such that wind is flowing laterally across its flat surface.
The canopy of this invention is a teardrop-shaped surface. The canopy is extended along its longitudinal plane to provide a larger surface area fore to aft. The extended canopy acts as an airfoil, as air moves at a higher velocity over the upper side than past the under-canopy region. Separation of airflow away from the skin of the upper side, especially as air moves fore to aft of the canopy, is greatly reduced by the shape of the present invention. The canopy also has a teardrop-shaped perimeter, further reducing airflow separation aft of the widest spread of the sides of the canopy.
The primary purpose of an umbrella, including the umbrella of this invention, is to shield its user from approaching raindrops, and to effectively streamline the flow of wind approaching the canopy from any possible direction. The relationship between canopy chord lengths of maximum width, length and height must be calibrated to meet these objectives. While a low-drag airfoil may have a maximum thickness approximating 15% of its chord length, an umbrella would be unwieldy if defined with such a profile.
An example streamlined canopy may have the following characteristics:
In the above example canopy, the canopy's widest area and crown-point are both at the forward end of the longitudinal-chord.
The drag-streamlined canopy shape definition produces a teardrop-shaped lateral profile and a half-teardrop shaped side profile. The elongated tail-section of this canopy shape is thought to inhibit formation of the low-pressure wake ordinarily associated with a bluff body interacting with low to moderate headwinds. The teardrop-shape promotes laminar flow across the upper side. Consequently, in certain wind conditions, airflow over this upper side will be dominated by friction drag. The teardrop shape may be further complemented and streamlined by the addition of a canopy nose, split tail and other improvements.
An umbrella's canopy may be designed so that its shape changes to deal with winds of varying force and direction. Such an umbrella is termed in the following an adaptive umbrella. As with a conventional umbrella, the primary objective of an adaptive umbrella is to provide shielding from rain and wind. As with the other aerodynamic umbrella improvements discussed herein, a further objective of the adaptive umbrella is to improve handling and stability, by providing a low-drag shape.
The advantages of an adaptive shape are multifold. A primary advantage is that the umbrella assumes a low-drag shape by comparison with an inflexible umbrella. Another advantage may be the improved protection from rainwater as the adaptive shape conforms around the user to protect the user's body. Another advantage may be in the creation of an asymmetric, low-drag umbrella with excellent folding and storage capability due to its articulated or amorphous structure.
The varying methods of providing an adaptive umbrella described herein may be used independently or in combination with one another, and in combination with other improvements such as an aerodynamic leading edge or spoiler.
The pressure articulated umbrella has a canopy, articulated in segments substantially parallel to the face-plane. While maintaining the umbrella's primary function as a shield from rain, the segments flex in response to pressure in order to produce a shape with lower drag than a fixed-canopy umbrella. The articulated canopy has two or more segments joined fore or aft by a respective series of flexible joints, hinges or other similar means of providing independent articulation of segments. A pole is fixed to one of the segments, which is termed the head segment. Aft of the head segment, the canopy may have one or more tail segments. Forward of the head segment, the canopy may have one or more further segments joined for articulation as an extension to the head or to flex inwards as an aerodynamic leading edge. In addition to a head segment and at least one other head or tail segment, the canopy may have one or more pairs of symmetric side segments.
The joints between the segments are water resistant, so that rainwater is unable to enter the under-canopy region. The joints may be made waterproof by an extension of the fabric that covers the segment, or an added portion of fabric folded as an accordion. An elastic fabric may be employed to stretch across the joint. Alternatively, an extension of one segment may overlap with an adjoining segment so as to produce a water resistant joint.
In one embodiment of the pressure articulated umbrella, the canopy shape resembles the domed carapace and articulated exoskeleton of horseshoe crab. As shown at 2101 in
In another embodiment of the umbrella of this invention, as shown at 2121, the canopy is articulated into multiple segments, including a forehead, head, mid-segment and tail segment. As shown at 2131, forehead 2133 is capable of flexing downward and inward to form an aerodynamic leading edge. Tail-segment 2135 is capable of flexing downward to protect the rear of the user while streamlining airflow around the user's body.
In each of these examples, flexing occurs as a result of either gravitational force or aerodynamic pressure on a particular segment. A series of springs may be used to provide adequate resistance in a no-pressure and a full-pressure state. A set of stops is used to limit articulation of each segment.
The size and number of segments may be large enough to be substantially indistinguishable from a smooth, continuous contoured surface capable of flexing from fore to aft. An example of a smooth, pressure articulated canopy is shown in a no-wind condition at 2141 and exposed to headwind at 2151.
The umbrella of this invention is similar to the pressure articulated umbrella in the use of one or more independently hinging segments from fore to aft. The manually articulated umbrella differs from the pressure articulated umbrella in the provision of a manual control at the umbrella handle to extend, retract, or to deform a series of segments.
An interface to the user is provided at the handle, either as a mechanical cable or rod that pushes or pulls a segment into a particular position, or using electrical or other communication means to extend or retract a segment.
In one embodiment of the umbrella of this invention, the manual control is provided to deform the curvature of a canopy nose. This umbrella would be useful, for example, by a runner interested in dynamically calibrating canopy's profile and resulting drag in order to exercise leg muscles.
A manual articulation of canopy shape may be employed in expectation of a pending aerodynamic force, not necessarily in immediate response. The user of a manually articulated canopy is capable of changing and retaining a canopy shape in anticipation of a particular weather condition.
The retraction and extension of one or more articulated segments may provide the added benefit of compact retraction, folding for storage, and rapid deployment of the canopy. This retraction and extension of segments may be automated by the addition of spring-loaded tension or other means commonly used for extension, folding and retraction of segmented structures. An adaptive umbrella may of course have some segments that are manually articulated and others that are pressure articulated.
The adaptive amorphous umbrella (herein referred to as “AAU”) changes shape in response to air pressure incidental to its surface from a wide range of directions. The function of the AAU is to provide ample protection from rain while making control in windy conditions easier. Stability is achieved by changing canopy shape to one with lower drag than a resistive canopy.
The AAU permits winds from any direction to deform the canopy shape so as to be narrowed in alignment with the direction of wind, resulting in a canopy shape that has both low pressure drag and is capable of protecting the umbrella user from falling raindrops.
The canopy of an AAU has surfaces of varying resistance to pressure, which enable the canopy to change its shape in response to the wind. In static weather conditions, the AAU may resemble a conventional umbrella. In windy conditions, the perimeter of the umbrella flexes, resulting in a narrow, streamlined shape with low pressure drag. The deformation of the perimeter, by flexing with a downward extension of canopy material, may result in improved protection from falling raindrops.
When aerodynamic forces are applied to the AAU, the direction of the wind on the canopy dynamically determines the canopy's head-portion, side-portions and tail-portion. The portion on the windward side of the canopy is the head portion and the portion on the lee side is the tail portion. When aerodynamic forces are directed at the canopy off-axis with the central yaw axis of the canopy, the AAU is advantaged in that its head-portion increases in positive curvature with its apex extended outwardly in opposition the direction of force, the side-portions contract towards the center of the AAU, and the tail-portion is extended outwardly, downwind along the direction of force. The resulting narrowed shape efficiently redirects air around the canopy, resulting in a shape with low pressure drag.
The AAU includes a non-deformable-area, resistive to aerodynamic force, and a deformable-area, capable of changing shape in mild and moderate winds. These two areas function together produce the desired shape of the AAU. It is important to note that the non-deformable-area and deformable-area are defined to include canopy surfaces and support structures.
An AAU may benefit from having a canopy nose or gutter. It is important to note that a canopy nose is a distinctly separate invention from the non-deformable-area of an AAU. An AAU may have a non-deformable-area at its crown and a distinctly separate canopy nose at its perimeter. Deformation of the canopy nose may be possible while retaining the advantages of an aerodynamic leading edge. An advantage of the AAU is its ability to increase positive curvature at the apex of its head-portion in proportion to the strength of the wind. As shown in a top view at 2241 in
When the wind contacts the AAU's canopy as shown at 2255, side-portions 2257 and 2259 are contracted. The surface of head-portion 2261 increases in positive curvature to produce a convex surface with its apex directed towards approaching force. Tail-portion 2263 also increases in positive curvature to produce a convex surface with an apex directed downwind. Non-deformable-area 2265 remains unchanged in its shape. The resulting shape has substantially lower pressure drag than a conventional umbrella, and in some conditions, the shape's friction drag may dominate over its pressure drag.
The non-deformable-area of an AAU has as much or more resistance to the wind as the canopy of a conventional umbrella. The purpose of the non-deformable-area is to define a minimum envelope of under-canopy protection from rain and wind that is capable of functioning in the harshest of weather conditions, with added protection provided in mild and moderate conditions by the deformable-area. The non-deformable-area may have an asymmetric shape, but tends towards the circular and will generally be substantially smaller than a conventional umbrella canopy. In a preferred embodiment of the AAU, the non-deformable-area is circular, with a diameter approximately equal to the shoulder-to-shoulder width of an average user.
The umbrella pole is affixed to the non-deformable-area, either by direct attachment or by attachment through ribs and struts affixed to the non-deformable-area.
The non-deformable-area transitions to the deformable-area. The deformable-area includes the area of the canopy outside of the non-deformable-area, and any support structure integrated with this area of the canopy. In a no-wind state, the canopy in the deformable-area is fully extended to provide protection from falling raindrops at all sides of the AAU. In this state, the AAU may resemble a conventional umbrella. When the AAU encounters wind, the deformable-area, including the canopy and corresponding support structure, changes shape. The direction of the wind defines the canopy's head-portion, side portions and tail-portion, as already described. The side-portions and underlying support structure contract, aligning themselves with the wind. The apex of the head-portion increases in positive curvature and extends upwind. The apex of the tail-portion increases in positive curvature and extends outwardly downwind.
To ensure adequate protection from wind and rain, the deformable-area has a deformation range and a maximum deformation state. These properties define the ability of the AAU to be effective in moderate and harsh weather conditions.
In harsh weather conditions, the deformable-area shape is limited by a maximum deformation state. The maximum deformation state is such that the side-portions of the deformable-area are not substantially contracted so as to come in contact with the user. The maximum deformation state may be formed by the resistance of the canopy and underlying support structure to withstand the wind; or by the addition of a fixed mechanical limit to the canopy and underlying structure; or by the addition of parts that limit maximum deformation.
A range of deformations is expected depending on the direction and intensity of the wind. The deformable-area must be of substantial elasticity so as to not easily be deformed to the maximum deformation state or to have the canopy billow uncontrollably, vibrate or flap. The deformable-area has an elasticity that enables its shape to change in shape in proportion to the intensity of wind.
The ability of the deformable-area to change shape may be achieved using canopy fabrics of varying elasticity; or by the use of canopy fabrics of varying thickness; or by variations in the resistive strength of underlying rib members; or by the addition or elimination of ribs to vary canopy support strength; or by the use of conventional ribs with an unconventional central hub that allows for lateral rib movement about the yaw axis.
A deformable-area may be constructed using a combination of conventional ribs along with flexing ribs that employ hinges or similarly flexing junctures at one or more locations along each rib extending outward from the resistive area of the non-deformable-area. These flexing ribs allow for deformation of the canopy, and restoration to an original shape.
Alternatively, the deformable-area of the canopy may be supported without ribs radiating from a central hub. A canopy material may be employed that has sufficient strength to maintain form and desired elasticity. One or more hoop-shaped rib members, similar to the concentric hoop-shaped ribs of a hoop skirt or farthingale or may be employed to provide structural support. As an added benefit, hoop-shaped ribs enable the canopy to be flattened to a substantially planar shape for storage. Elliptical hoops or curved boning, for example those used to provide structural support to a French panier or basket skirt, may be employed for an AAU that is asymmetric in static weather conditions.
An AAU may be constructed by using structural members other than conventional ribs and struts. In one possible embodiment shown in a bottom view of the canopy of an AAU at 2271 in
A possible alternative structure of an AAU to the embodiment of 2271 in
A preferred embodiment of an AAU is shown at 2351 in
As shown in an enlarged view at 2411, an example deformation control rod has enclosed housing 2413. In a view of the deformation control rod as shown at 2421, the face of housing 2423 has been removed and the interior exposed.
The deformation control rod consists of piston 2425; wheels 2427 and 2429 rotating freely on respective axles at either end of the piston; spring 2431 freely located on the piston; spring stop 2433 and piston stop 2435 fixed to the piston; finger 2437 which is a rod within the housing fixed at one end to the housing and having a concave tip at the end facing the piston; support rod 2439 fixed to the housing at one end and fixed to the canopy pole or a hub on the canopy pole as at the opposite end as shown at 2369 on the AAU of 2361. Housing 2423 has opening 2441 through which the piston enters the interior area. The housing forms an enclosed space for unobstructed retraction and containment of the piston.
In a no-wind condition, a deformation control rod is said to be at an equilibrium state. At this state, spring 2431 is fully extended and at equilibrium. Piston 2425 is fully extended outside of the housing and generally collinear with finger 2437. Wheel 2427 is in contact with the under side of the AAU, and is free to roll along the under side.
As shown at 2451, upon the application of inward force 2453 on piston 2455 collinear with finger 2457, the finger prevents the piston from entering the housing at 2459. As shown at 2461, upon the application of inward force 2463 on piston 2465 at a direction off-axis to finger 2467, the piston is leveraged at housing opening 2469, avoiding contact with the finger and is pushed into the housing. As shown at 2471, spring 2473 is compressed as inward force 2475 drives piston 2477 into the housing. When inward force 2475 decreases, spring 2473 pushes piston 2475 back to its equilibrium state, as shown at 2421.
Wheel 2429, as shown at 2421, reduces friction between the piston and the finger, allowing a force at off-axis from the piston to roll the piston away from the concave tip of the finger. Wheel 2427 is normally in contact with the under side, rolling along the surface of the under side. In some instances, for example when the leeward-portion of a canopy is pushed downwind by aerodynamic forces acting on the windward side, the under side at the leeward side is temporarily separated from the piston wheel of the closest deformation control rod.
The main purpose of the deformation control rod is to restrict inward deformation at the apex of the windward-portion of the canopy. As shown at 2481, deformation control rod 2483 is most closely aligned with direction of aerodynamic force 2485 and is restricted from being compressed because of the alignment of its piston with its corresponding finger. Other deformation control rods, for example deformation control rod 2487, receive an inward force on their respective pistons misaligned with corresponding fingers. The pistons of these deformation control rods are pushed inwards. At the leeward-portion of the canopy as shown at 2489, the under side is out of contact with the deformation control rod 2491. The shape of non-deformable-area 2493 remains unchanged from its original, no-wind condition.
As inward deformation of the canopy is restricted by one or more deformation control rods at the apex of the windward-portion, the canopy forms a pointed shape. The side-portions of the canopy are pressed inward, as corresponding deformation control rods receive an inward force on their respective pistons off-axis with their respective restraining fingers. The leeward-portion of the canopy is elongated downwind, unaffected and out of reach of its nearest deformation control rods.
Asymmetric areas of an AAU in a no-wind condition may be identified to describe asymmetric improvements useful in all wind conditions. For example, the identification of a head-section and tail-section allows for the addition of gutters, a canopy nose and other asymmetric improvements. While the AAU benefits from its ability to deform in response to winds approaching from a range of possible directions, an AAU may have asymmetric variations along its longitudinal axis. For example, it would be possible for an AAU to have an off-center non-deformable-area located in the fore-section of the canopy.
Force applied to a conventional umbrella by wind striking the canopy substantially head on and resisted at the handle by the umbrella user, compresses the pole. A conventional tubular pole is generally well suited to absorb the force of compression.
Because wind often interacts with a canopy at an acute angle with respect to the pole, torqued forces are exerted on the pole. Torque is leveraged on end of the pole closest to the top of the canopy and must be resisted at the handle end. Fulcrum points of leveraged force along the pole, for example at the point of juncture between the pole and handle or at the point of interface between the pole and struts, are susceptible to damage if the pole is unable to resist or flex.
Substantial flexure of an umbrella pole is undesirable because the canopy is expected to shield the user, not to sway or move away from the user. For this reason, a conventional umbrella pole is constructed to provide as much resistive strength as possible while ensuring that it is lightweight and easily managed.
Because the resistive strength of a pole is often unable to absorb forces leveraged on it in moderate wind conditions, the user must carefully govern how much force to apply to the handle without bending or breaking the pole. As the user relaxes force on the pole, the umbrella's purpose in shielding the user from raindrops may be compromised, or in a worst case the canopy's underside may be inadvertently exposed to the wind.
To manage force on the canopy, the umbrella user may attempt to hold an upper area of the pole, closer to the struts. At this point, the moment arm between the center of pressure and the grip point is shorter, resulting in a reduction of torqued force.
Pole improvements may be made including increased flex strength or resistive strength; increased resistive strength at the handle end; reducing leverage by the use of a shortened pole; additional poles; and additional support structure elements.
To reduce torqued force, the pole may be inclined in an orientation that is better aligned with the force expected to be exerted on the canopy. The vector of expected force would perhaps consider anticipated wind speeds, wind directions, canopy shape and resulting drag for the given wind conditions, lift and canopy weight (wet and dry).
For the purpose of illustration, umbrella 2501 as shown in
Of course, a pole suited to one particular direction or strength of canopy pressure would not be extremely effective. An understanding of anticipated forces, for example forces expected based on the proclivity of umbrella users to tack in headwinds, or the creation of an umbrella specifically for active pedestrians, must inform the design.
In mild weather conditions, when umbrella weight is a major factor, the user expects an umbrella to be balanced in weight about its handle. The handle should be located along an axis, perpendicular to the ground-plane and intersecting the umbrella's center of gravity. Held at any point on this axis, the umbrella is balanced and exerts only negligible torque on the user's wrist.
In addition to balance, ergonomic expectations must also be considered. A conventional umbrella handle at the user's hand is distanced from the canopy held aloft above the user's head. As described earlier in this section, a handle located closer to the canopy's center of pressure could improve stability by reducing torque. Such a handle location would conflict with ergonomic expectations and would not necessarily correspond with the center of force anticipated in moderate or harsh weather conditions.
Clearly, improvements to pole and handle design must address balance expectations for static weather conditions, force expectations for windy conditions, and ergonomic expectations for comfort.
For an umbrella that has a pole and handle primarily suited to address powerful aerodynamic forces acting on its canopy surface, a secondary pole or handle could be integrated for balancing the canopy in static conditions. This secondary pole may be of lesser strength than the primary pole. Alternatively, this secondary pole could be of sufficient strength and connection to the primary pole to provide leveraging force for wind conditions that vary from those anticipated.
Two points of access, one to provide gravitational balance in no-wind conditions and another to provide a force advantage in windy conditions, may be accommodated by a single handle, a pivoting shaft and a locking mechanism, or similarly adjustable handle relocating and locking system. Such a handle could be locked at one of two locations or swivel to provide a range of positions.
For an umbrella expected to counter a variety of asymmetric air pressures on its canopy surface, a primary pole might offer a number of handles as control points. To shift the point of oppositional force, these handles might be offset by a series of secondary poles.
For an umbrella expected to counter a variety of powerful asymmetric air pressures, these multiple handles may be suited for use by multiple hands, or the additional aid of shoulders or other body parts.
An umbrella that offers protection for multiple users is taught by prior art (Sefton, http://www.newhousenews.com/archive/sefton060903.html). The present invention may employ multiple handles or other points of control for multiple users.
For a conventional umbrella, with a canopy that is radially symmetric about its pole, torsion force on the pole is negligible. For an asymmetric umbrella, which may be subjected to force that pushes its canopy about its yaw axis, torsion strength must be considered. U.S. Pat. No. 5,642,747 teaches an asymmetric umbrella canopy that pivots about a central axis, using a stabilizer to maintain a front-facing orientation.
The junctures between the handle and pole, pole and canopy, pole and support structure, and support structure and canopy may each allow for some flexing to absorb forces on the canopy. The addition of springs or similarly flexing components may be used to produce these flexing junctures.
Flex or torsional rotation about the yaw axis enables the umbrella to calibrate itself with slight changes in the direction of headwinds. In an unsustained gust, a flexing system would enable the canopy to shift slightly and subsequently return to a generally front-facing orientation.
A curve-shaped pole is well suited to an asymmetric canopy shape. A curve-shaped pole is aesthetically significant, complementing the contours of a curve-shaped canopy. A curve-shaped pole is also advantaged because it can be positioned away from interference with the user. The user's upper body and head are fully shielded in the under side region.
Some mechanical advantage may be achieved by a curve-shaped pole in the distribution of force. Because a curve-shaped pole, as shown at 2521 in
The juncture between the handle and pole may be strengthened, and may be integrated as one functional unit. Because the lower portion of a curve-shaped pole may approach an inclination similar to the user's lower arm, a straight extension to this portion of the pole may exist to use the forearm to leverage force on the handle. This forearm portion of the pole may be accessorized, widened or padded, to improve its interface with the user's forearm. As shown at 2531, a forearm extension and forearm grip is added to a curved pole at 2533, and shown in an enlarged view at 2541.
The juncture between the pole and support structure may be similar to a conventional umbrella, with struts that improve the transfer of force from the canopy surface. For an asymmetric canopy, these struts may be asymmetric in shape and length with respect to each other to correspond with anticipated pressures on the canopy.
Whereas existing art teaches that a pole is generally employed to push the canopy, or the portion of the canopy aft of the pole, an umbrella may be advantaged by having a pole that substantially pulls the canopy. By changing this orientation between the pole and canopy, the pole may be more closely integrated with a canopy nose. A pole-pulled canopy may be further advantaged by the conversion of the canopy's support structure from a conventional compression-based system to an extension-based system.
In a preferred embodiment of a curved pole, the pole is curved to correspond with the curvature of the canopy, and connecting to a rib of matching curvature that continues along the canopy to its trailing edge. The canopy as shown at 2551 of
In a second embodiment of a curved pole and spine, the pole top extends in front of the canopy nose, and connects to a rib that continues to run along the upper side on the external, exposed surface of the canopy. In this embodiment, additional ribs may also run along the exposed upper side, leaving the under side free of any structural encumbrance. As shown at 2561, curved pole 2563 and spine 2565 runs outside of canopy nose 2567 and upper side 2569. In this illustration, spine 2565 is attached to upper side 2569 by a series of fabric loops such as shown at 2571 and fabric pocket 2573.
The pole, spine or combined pairing of the pole and spine may be telescoping, and may employ conventional means for folding and unfolding.
The pole may be hollow, allowing for the manual or spring-loaded retraction, storage and deployment of the canopy and ribs.
The pole may be joined at the canopy nose by a pivot or similarly rotating system that enables the umbrella to be folded by rotating the pole and ribs into a single compressed curve shape.
The pole may be a tapered tube, with the largest diameter at the handle end, and the narrowest diameter at the canopy end. This tapered shape allows for increased flexing at the canopy, with minimal flexing nearest the users arm.
The pole may house mechanical controls, interfacing with the user through the handle, for pivoting the canopy pitch, roll and yaw while maintaining a static pole and handle position.
An umbrella's ribs provide structural support along the surface of its canopy. Struts provide strength by reducing torque on the top of the pole, distributing force from the canopy to the pole, increasing the beam strength of each rib, and shortening the cantilevered length of each rib. The canopies disclosed herein may employ ribs, and struts radiating from the pole.
Alternatively, the canopies may employ a number of ribs extending from the forward area of the roll axis to distant points along the canopy perimeter in the aft-section. In the field of aerodynamics, ribs running along the longitudinal length of an aerodynamic body are referred to as longerons. As shown at 2601 in
Longerons may be connected fore and aft. As shown at 2621 longerons run from front 2623 to a connection point at rear 2625. A set of similar longerons is shown with an attached canopy at 2631.
Because longerons may be similar in curvature to one another, they may be folded together into a united group. To aid in folding, longerons may be connected to a hub located at the front of the canopy, around which the longerons are able to pivot, spreading apart when the umbrella is opened. The pole may be connected to the hub. Alternatively, the united longerons may be retracted into a hollow pole. A second hub may be located at the tail of the canopy, at which the endpoints from each longeron may be connected.
To improve the spread of longerons, one or more lateral ribs may be employed on either side of a central longeron, or spine. These lateral ribs may be retracted, folded and deployed by connection with the spine, hinging into position and retaining position by fabric tension or other locking means.
Canopy fabric may be used to restrict extension of ordinarily straight ribs, including longerons, thereby providing adequate tension to define the canopy's form and limiting motion of these ribs. Tension on canopy fabric strengthens the umbrella by distributing aerodynamic forces acting upon the canopy and underlying support structure. When canopy fabric tension is relaxed for retraction of the umbrella, ribs may reflex to a substantially straight shape for easy grouping, folding and retraction. When canopy tension increases during deployment of the umbrella, ribs are forced into a desired curvature and desired tension.
Fabric cross-sectional pieces seamed to the under side substantially perpendicular to the surface of the under side may be used as tensioners to limit expansion between side-halves of a canopy, providing structural strength and defining a desired form.
Fabric tensioners running parallel to the longitudinal plane, perpendicular to the surface of the under side, limit longitudinal deformation. A set of such tensioners is shown at 2641, each attached along a respective longeron.
Fabric reinforcements running parallel to the face-plane, perpendicular to the surface of the under side, limit lateral deformation. As shown at 2651, fabric reinforcement 2653 runs across a set of longerons, ready for attachment to a canopy.
Fabric tensioners in the under side region are shielded by the canopy surface so as to limit direct exposure to aerodynamic forces.
An umbrella, especially of the adaptive, amorphous type described earlier, may benefit from an extremely flexible support structure. As an example, one or more spiraling ribs may provide a desired decrease in resistance from the crown-point to the outer canopy perimeter. Spiraling ribs may radiate from a central point on the canopy, for example the crown-point, providing structure for the entire canopy. Alternatively, spiraling ribs may radiate from the outer perimeter of a resistive area circumscribing the crown-point, or they may radiate from the outward tip of a series of short conventional ribs, providing structural support for the remaining portion of the canopy approaching the perimeter. Spiraling ribs spiral outward from a central location, enabling the canopy to be easily flattened for storage or other useful purpose.
An embodiment of an umbrella with a spiraling rib structure is shown in a view of its under side at 2701 in
A second embodiment of an umbrella with spiraling ribs is illustrated in a bottom view at 2731. Here, spiraling ribs as shown at 2733 are connected to the end of a set of shortened conventional ribs as shown at 2735, and extending to the perimeter of the canopy. The spiraling ribs of this canopy enable it to be flattened for storage, as shown in a perspective view at 2741. In a side view of this canopy at 2751, a spiraling rib can be seen curving inward at the outermost perimeter of the canopy at 2753, lending structure to canopy fabric in the formation of canopy nose 2755.
An aerodynamic canopy, especially one that is asymmetric from front to rear, may require multiple poles, rods ribs, longerons, handles and other support members that function together or independently during deployment, during use and as an interface to the canopy's user. The addition of these components is possible without departing from the scope of the invention described herein.
The improvements to the canopy, pole, and support structure described herein may be combined in different fashions in different embodiments of the improved umbrella. One useful combination of improvements is shown in
As shown in a side view at 2811, the aerodynamic canopy profile is subjected to headwind at 2813. As suggested by the arrows depicting airflow, the canopy is dominated by friction drag in certain headwind conditions. Air encountering the canopy nose moves along the contoured skin of the canopy, continuing in laminar flow over the upper side and across the tail-section. The rounded canopy nose and streamlined tail-section inhibit separation of airflow away from the canopy surface, preventing turbulent separation at the leading edge and formation of a low-pressure wake aft of the canopy. Air moving along the lower-leading surface of the canopy nose is directed away from the under-canopy region.
It is important to note that although the canopy profile shown at 2811 is efficient in headwinds, it is also well-designed for side-winds and tailwinds. As seen from the side, the canopy has a bluff, snub-nosed front-section and extended tail-section, with a cross-sectional profile of a teardrop shape. In side-winds, torsional force on the yaw axis is minimized as torque resulting from drag on the bluff head is countered by torque resulting from drag on the extended tail-section. The tail-section is elongated and curved slightly downward, far better suited to protect the user in tail-winds than a conventional umbrella. The tail-section is flattened, protecting the under side from capture of air and potential damage from a buildup of air pressure.
As shown in a side view at 2821, this particular combination umbrella has pole that is collinear to the yaw axis of the canopy and connects to the canopy's crown-point. This combination design includes hard gutter 2823 to carry rainwater to the tail-section. Microgutter system 2825 is a finely ribbed surface that, in headwind conditions, will use aerodynamic force to push raindrops falling on the front-most portion of the canopy upward and toward the hard gutter. The canopy nose, with lower-leading-surface 2827, offers a number of advantages. In headwinds, it enables the user to orient the umbrella in a range of pitch and roll positions without exposing the under-canopy region to a buildup of air pressures. The canopy nose also directs air away from the under side to reduce pressure drag on the upper body of the user. As mentioned earlier with respect to illustration 2811, the canopy nose also eases control of the canopy by preventing the turbulent separation of air normally associated with the sharp leading edge of a conventional umbrella oriented in attack to aerodynamic forces.
As shown in a view of the umbrella underside at 2831, this combination umbrella has a pole, rib and strut structure similar to the structure of a conventional umbrella. Here, the ribs extend from the crown-point to the perimeter of its asymmetric canopy. The lower-leading-surface of the canopy nose is visible at 2833. Unlike a conventional umbrella that typically has a segments radiating from its crown-point, this canopy has fabric canopy segments running from nose to tail as illustrated by patterned fabric segment 2835. The use of nose-to-tail fabric panels reduces the total number of segments and seams required to manufacture a highly streamlined shape.
This combination umbrella has an asymmetric handle, with an ergonomic grip that ensures comfort while helping the user maintain a forward-facing canopy orientation. With an asymmetric handle, the user is able to orient the umbrella without looking up at the canopy. The handle may also include an index-finger trigger, conventional thumb trigger, or squeezable rubber grip with an internal trigger for activating an automated opening or closing mechanism.
The foregoing Detailed description has disclosed to those skilled in the relevant disciplines how to make and use the umbrellas of the invention and has also disclosed the best mode presently known to the inventor of making and using such umbrellas. It will however be immediately apparent to those skilled in the relevant disciplines that umbrellas made according to the principles of the invention may be implemented in many ways other than the ways disclosed herein. For example, the canopy may be made of any present or future material that serves the purpose, as may the support system for the canopy. Further, the convex surface at the edge of the canopy may have many forms and may or may not be part of a canopy that is otherwise streamlined and may have additional purposes such as directing the wind away from the underside of the canopy or away from the user. The streamlining of the canopy may also take many forms, including partially-streamlined canopies, canopies which do not have a teardrop surface, and canopies which are virtual or real two-sided airfoils. Gutters may take any form which directs the flow of water and spoilers may take any form which affects the flow of air over the canopy in the desired fashion. With adaptive canopies, the adaptations may be any that serve the purpose and the adaptations may be made either by the user or automatically in response to the winds to which the umbrella is exposed. The mechanisms by which the adaptations are made may be those disclosed herein or any others with serve the purpose.
For all of the foregoing reasons, the Detailed Description is to be regarded as being in all respects exemplary and not restrictive, and the breadth of the invention disclosed herein is to be determined not from the Detailed Description, but rather from the claims as interpreted with the full breadth permitted by the patent laws.