US 20050221961 A1
A stabilizing tracking system for a spinner exercise bicycle includes a spool that is attached to the bike in the loop path of the drive belt between the drive and flywheel sprockets. The spool is located such that the belt is forced to travel below the top dead center of the flywheel sprocket. The spool also has flanges such that the standard poly-V-belt is caused to track within the spool. Forcing the belt below top-dead center of the flywheel sprocket and keeping the belt in tack reduces belt wear, stretching, and the tendency of the belt to wobble or sway as it is driving a flywheel. The spool utilizes inner bearings for smooth rotation of the stability tracking spool. The spool compensates for the differential in the thrust from the top, dead center position of the drive sprocket. The spool picks up the slack in the drive belt that and keeps the belt in a close track. The spool also compensates for slippage during start up of the flywheel and keeps the belt from slipping or wobbling.
1. A stabilizing and tracking system for an exercise bike having frame, pedal drive sprocket rotatably mounted to said frame, and a flywheel drive sprocket linked to a flywheel that is rotatably mounted to said frame, a belt interconnecting the pedal drive sprocket and the flywheel drive sprocket, comprising a spool rotatably connected to said frame, said spool being fixed at a position vertically between the pedal drive sprocket and the flywheel drive sprocket such that a bottom dead center point of said spool is below a top dead center point of said flywheel drive sprocket, and such that an axis of said spool is horizontally positioned from about 1.5 to about 5.5 inches from an axis of said flywheel drive sprocket toward said pedal drive sprocket.
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This invention relates to stationary exercise bicycles used for group cycling, spinning, or other exercise uses. More particularly, an advanced belt stability tracking system is presented that stabilizes the belt drive of such exercise bicycles to improve operation, belt functions, and belt life.
Adjustable stationary exercise bicycles have been in common use throughout the exercise industry for many years. Numerous patents have been issued for exercise bicycles, all directed to different aspects of the structure of exercise bicycles. For example, the applicant has several patents issued to him for adjustable, stationary exercise bicycles. These include U.S. Pat. No. 6,612,970, disclosing a quick-brake disengagement mechanism and a vertical handle bar adjustment, and U.S. Pat. No. 6,669,603, provides for the vertical adjustment of the seat as well as the horizontal adjustment of the seat and handle bars. Other inventors have disclosed different inventions and improvements to other aspects of the structure of spinner exercise bicycles.
Adjustable exercise bicycles utilize the structure of a regular bicycle placed on a stationary base. The base does not move, hence the term stationary exercise bicycle. The front wheel of a standard bicycle is most often replaced with a weighted flywheel, and is connected to the pedals and drive sprocket of the bicycle, usually by an endless chain or belt. The interconnection of the drive sprocket to the flywheel sprocket through use of a chain or belt causes certain problems, with the most significant problem being addressed by the instant invention.
A preferred type of drive mechanism, used to connect the drive sprocket to the flywheel sprocket, is the use of a flexible belt. Such belts are commonly referred to as a poly-V-belt because of its trapezoidal cross-section. However, flat or rectangular cross-section belts are also used. These flexible belts are common throughout the industry and their use is well known. As noted, the cross section of such flexible belts can take a variety of forms, and where a poly-V-belt is used with its trapezoidal cross-section the larger, flat portion of the belt is usually on top, and the smaller portion of the belt being on the bottom and in contact with the drive and flywheel sprockets. My new invention is directed mainly to the belt-driven type of exercise bikes now currently in use.
One problem with flexible belt systems is that the belt may stretch over time. Belt stretching necessarily degrades the entire drive mechanism, since the belt will loose tension, and as it becomes loose the belt will wobble or otherwise become unstable in use due to the looseness from stretching. Many known systems employ a belt tensioner which can operate either manually, automatically, or by a spring assembly to take up slack associated with any such belt stretching. It is an object of this invention to decrease the amount of stretching which a belt may experience during the life of the belt.
As the belt stretches, it can also become unstable in its tracking and may sway laterally. The more the belt stretches, the more the wobble and lateral sway occurs. This wobbling and swaying is detrimental to the smooth functioning and spinning of the flywheel, and the belt may also move laterally off the drive pulleys, or otherwise become disengaged from, the drive sprocket or flywheel sprocket. It is another object of this invention to provide a mechanism to reduce the wobble and sway of a belt in a an exercise bike.
Other and further objects of this invention will become obvious upon reading the following specification.
A stability tracking hub is introduced into a standard exercise bicycle drive train. The stability tracking hub is preferably comprised of a spool with flanges at the outer edges, and is rotatably connected to the bike frame at a fixed position. From a horizontal standpoint, it is preferred that the drive-surface of the stabilizing and tracking spool, in contrast with the belt, is located below the top dead center of the flywheel sprocket. Such an arrangement permits the drive belt, as it passes around and under the tracking spool, to be forced below or beneath a point equal to the top dead center of the flywheel sprocket before it engages the flywheel sprocket as the belt continues to move it in its forward or clockwise motion. The tracking spool is fastened to the bike frame by a hanger bracket or other fixed structure.
Forcing the belt to move under the tracking spool and then up and over the top, dead center of the flywheel sprocket reduces the stress in the belt. This reduces stretching and also stabilizes the way the belt tracks toward the flywheel sprocket. It is also preferred to employ an improved flat reinforced drive belt that is extremely strong in its longitudinal direction to minimize belt stretching.
An exercise bicycle used for individual or group exercise, and the like, is shown in
Turning now to
The pedal drive sprocket 9 is connected to the front flywheel drive sprocket 10 by means of flexible belt 11 such as Gatorback poly-v rib series. The preferred belt is a Goodyear K6-500, industrial series multiple-ply belt. This belt is comprised of a composition including polyester fiber and rubber, and has about a 24 mm width and a thickness of about 4 mm. This flat multi-ply polyester fiber and rubber poly-V rib belt is included to make the belt seem to be pre-stretched, and so that stretching of the belt in normal use will be prevented or minimized. The front flywheel sprocket 10 is typically smaller than the rear drive sprocket 9.
Important points of force are applied between the belt 11 and the spools and sprockets over which belt 11 moves as the belt 11 contacts the top, dead center 16 of the flywheel drive sprocket circumference, and when the belt contacts the top, dead center 17 a of the pedal drive sprocket 9.
The working flywheel 5 is normally quite heavy and has a standard diameter of approximately eighteen inches. Due to the disparity between the size and weight of the pedal drive sprocket 9, the flywheel drive sprocket 10, and the working flywheel 5, a significant amount of force is exerted on the working flywheel 5. This force, applied initially top dead center of the flywheel drive sprocket 10, can result in damaging and/or stretching of the belt 11. It is this stretching and the resultant wobbling and loss of tracking ability in the belt to which this invention is directed.
Belts utilized in bicycles prior to this invention frequently stretched and became contorted due to the relationship between the forces exerted on the belt. In Lo, U.S. Pat. No. 5,310,392, for example, an expensive tensioning system was used to keep the drive belt sufficiently taught to effectively transmit drive forces. This tensioning system included a tensioning wheel mounted on one end of a rocker arm with a spring connected to the opposite end of the rocker arm. The spring would cause the tensioning wheel to push down on the drive belt and apply pressure on the belt to keep the belt taught. Such pressure can also cause additional belt stretching over time, which is automatically taken up by the spring.
Without the introduction of the present stability tracking system to a belt-driven exercise bike, the force exerted by the pedals 4 on the normal belt arrangement at the top dead center point 17 a on pedal drive sprocket 9 will exert a huge amount of force on the belt at point 16, the top dead center of the flywheel drive sprocket circumference. Because the pedal drive sprocket 9 is about twice as big as the flywheel drive sprocket 10, and because the flywheel drive sprocket 10 must drive a much larger and heavier working flywheel 5, the usual belt arrangement will subject the belt to stretching forces, and when actual stretching occurs slippage can occur between the belt and drive sprockets 9 and 10. This stretching of the belt could damage and ultimately necessitate the replacement of the belt. Slippage of the belt relative to flywheel drive sprocket 10 is also a source of concern since it provides an uncomfortable and possibly dangerous experience on the spinner bike. The stability and tracking system described here ameliorates both of those problems.
Connected to the front handle bar support 12 is a hanger bracket 13, as shown in
The stability and tracking spool 15 compensates for the differential in the thrust from the top, dead center position 16 of the flywheel drive sprocket 10. In addition, the stability and tracking spool 15 picks up the slack in the drive belt 11 and keeps the belt in a confined track. The stability and tracking spool 15 also compensates for slippage during start up of the flywheel 5, and keeps the drive belt 11 from slipping or wobbling.
Turning now to
The stabilizing and tracking spool 15 has left 19 and right 19′ spool flanges. The stabilizing and tracking spool 15 thus takes the shape of a spool of thread. The angle between the interior hub surface 23 and each of the flanges 19 and 19′ can range from 95° to 150°. Thus, the cross-sectional shape of the belt channel can vary from a U-shaped channel to one that is trapezoidal in its cross-sectional shape. The particular angle between the bottom surface 23 and the two opposing side flanges should approximate the angular shape of the sides of the opposing belt to be used. The range of angles for the flanges relative to the bottom surface 23 that best accommodates the K6-500 Goodyear belt is about 120° to about 140°, with the preferred angle adjacent to each flange being about 128°.
The cylindrical stabilizing and tracking spool 15 fits over the spool axle hub 18 and rotates thereon. In order to provide for the smooth rotational motion of the spool 15, left and right spool hub bearings, 20 and 20′ respectively, are inserted inside the cylindrical spool 15, and these bearings are shown in an exploded condition in
As clearly demonstrated in
The location of tracking spool 15 relative to flywheel drive sprocket 10 is important. First, the vertical distance between lines, or planes, 50 and 52 is preferably about half an inch, but can range between about ⅛ inch to about 1.5 inches. The horizontal spacing between the axes of tracking spool 15 and flywheel drive sprocket 10, defined by vertical lines 54 and 56, is preferably about 2.5 inches, but can vary from about 1.5 inches to about 5.5 inches.
By using the two preferred locations for tracking spool 15 relative to flywheel drive sprocket 10, and by using the non-stretch belt 11, the tension on belt 11 will be reduced from about 180 psi, to about 135 psi while still maintaining the desired drive force on flywheel 5. Further, this relative position of tracking spool 15 and flywheel drive sprocket 10 relative to the bike's other operating structures, maintains the stability and tracking of belt 11 around flywheel drive sprocket 10 without wobble, without causing stretching of belt 11, and without belt 11 becoming disengaged from flywheel sprocket 10.
Due to this significant relationship of the belt drive and support structures, the belt 11 is forced below the top, dead center 16 of the flywheel sprocket 10, and belt 11 then moves upward in its movement towards the flywheel sprocket 10 as the pedals are rotated in a standard clockwise fashion. Forcing belt 11 to move upwardly to the top, dead center position 16 of the flywheel sprocket 10 prolongs the life of belt 11, reduces stretching and creates more stability in the entire drive system. In addition, the flanges 19 and 19′ on spool 15 keep the belt in a stable tracking mode for smooth, efficient, and long-lasting operation of the belt drive system.
It has been shown that the use of this device and approach greatly prolongs and enhances the belt drive system described above. It is to be noted that the dimensions given for the drive sprocket, flywheel sprocket, and working flywheel are meant as means of illustration only and not as limitation. Obviously, different manufacturers use sprockets and flywheels of different dimensions. However, the use of the stabilizing and tracking spool in the manner shown and described is of general application to belt driven and chain driven applications. Special attention herein is directed towards the belt driven embodiments of spinning exercise bicycles.