US 3628463 A
Description (OCR text may contain errors)
United States Patent 3,206,560 9/1965 Parmenter Primary ExaminerArthur L. La Point Assistant ExaminerGeorge H. Libman Attorney Bair, Freeman & Molinare ABSTRACT: A speed-control device for controlling the speed of a moveable assembly at a given point in a predetermined path of travel along a guidance rail includes an inclined cam adjacent the point. At least a pair of cam followers are mounted on a support member, which is mounted on and moveable relative to the moveable assembly, so as to engage the guidance rail to establish'a first reference plane and the inclined cam which establishes a second reference plane. Both followers are continuously spaced a given distance from each other and are simultaneously moveable as the distance between the assembly and the guidance rail varies to maintain said given distance. When one of the followers contacts the inclined cam, it is moved so as tovary the distance between the respective followers and variably actuate a rheostat to reduce the speed of the assembly.
PATENTEDUEBZI ml v 3628;463
INVENTORS GERALD M. mm moms/w BY PAUL E. REDELMA/V ATTORNEYS SPEED-CONTROL DEVICE BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to a speed control device and, more particularly to a device for variably controlling the speed of an assembly which is moveable relative to another assembly.
It is frequently desirable to slow down or stop various assemblies which are moveable over a predetermined path at some point in the path of travel, e.g. at either end of the path to prevent overrun of the assembly. One such assembly is found in storage installations wherein a load carrier is provided to move horizontally up and down aisles of a storage frame construction to store and retrieve articles therein. In such installation, some form of end-of-aisle slowdown and/or stop switch is highly desirable to prevent overrun of the load carrier at the end of the aisle. It is preferable that such switch be capable of gradually slowing the speed of the load carrier, rather than abruptly stopping the load carrier, in order to prevent damage to the articles which are being carried and/or to operating personnel.
The speed-control device incorporating the principles of the invention is capable of gradually slowing and/or stopping a moveable assembly at some point along its path of travel and may be readily adapted for installation on presently installed assemblies without substantial reworking of the assembly. The speed-control device of the invention is not only simple in construction and in operation, but also may operate in conjunction with a guidance member of conventional construction which normally guides the assembly along its path of travel. Moreover, even though the distance between the moveable assembly and such guidance member may vary over the course of travel of the assembly, the speed-control device of the invention will remain uneffected thereby. The speedcontrol device incorporating the principles of the invention continuously establishes a reference plane and a follower, carried by the assembly, is moveable by way of a cam surface inclined to the reference plane to vary a control device which varies the power to the prime mover of the moveable assembly.
In a preferred aspect of the invention, a device for variably controlling the speed of a moveable assembly includes first and second reference plane establishing means which establish respective reference planes, one of which is variably spaced relative to the other. First follower means is positioned in a first of the reference planes and means is provided for normally positioning second follower means a given distance relative to the first follower means, but which is responsive to the contact of the second follower means with the second reference plane to vary the given distance so as to actuate control means to provide a variable control output.
These and other objects, features and advantages of the present invention will be more clearly understood through a consideration of the following detailed description.
BRIEF DESCRIPTION OF THE DRAWING In the course of this description, reference will be frequently made to the attached drawing in which:
FIG. 1 is a perspective view of a storage installation having a plurality of storage frames and a moveable load carrier for storing and retrieving articles therein; and
FIG. 2 is a cross sectioned elevation view taken substantially along line 22 of FIG. I and showing a load carrier speedcontrol device incorporating the principles of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, a storage installation is shown in which the speed speed-control device of the invention is employed as an end-of-aisle slowdown switch. The storage installation includes a plurality of upstanding racks or frames which form a plurality of horizontally and vertically spaced storage bins 11 and 11' for the storage of articles A therein. Each series of bins is spaced from the other so as to provide an aisle l2 therebetween. An overhead guidance rail 14 is stationarily mounted adjacent the top of the racks in the overhead of the aisle and a load carrier, indicated generally as 16, is moveable in the horizontal plane back and forth upon the floor of the aisle 12 by suitable electric drive means (not shown) and under the guidance of the guidance rail 14. The load carrier also includes an elevatable lift platform 17 having one or more laterally extendible forks l8 thereon for inserting or removing articles into or from specific ones of the bins. The construction of the load carrier will not be set forth herein in detail, since such detailed load carrier construction forms no part of the invention.
The guidance rail 14 preferably takes the form of an elongated member which extends the length of the storage rack aisle l2 and into an article handling area at one or both ends thereof, indicated generally as 20 in FIG. 1. Referring to FIG. 2, the rail 14 may preferably comprise an elongated channel member, the web 22 of which is attached to the overhead and the exterior faces 23 of the downward extending side flanges 24 of which form guide surfaces along which rollers 26 rotatably mounted to the overhead beam 28 of the carrier, rollably engage to guide the load carrier over its path of travel.
A preferred embodiment of speed-control device of the invention, indicated generally as 30, will now be described and is employed to slow and, if desired, to stop the load carrier as the load carrier reaches the end of the guidance rail I4. Referring particularly to FIG. 2, the control device includes a plate 32 which is positioned adjacent the underside of the upper beam 28 of the load carrier and is moveably mounted relative thereto by way of a downward extending pin 34 which is welded to the underside of the web 36 of the beam. The pin 34 passes through an aperture 38 in the center of the plate and a compression spring 40 extends between a transverse pin 42 adjacent one end of pin 34 and the underside of the plate, normally urging the plate 32 in an upward direction, as viewed in FIG. 2.
Adjacent each end of plate 32 is a pair of followers 44 which comprise an upstanding mounting bracket 45 which is firmly mounted at one end on the plate 32 and which carries a rotatable roller 46 at the other end. The rollers 46 are positioned to rollably engage the longitudinal edges 48 of the guidance rail flanges 24. The follower brackets 45 freely pass through apertures 50 in web 36 of overhead beam 28.
Extending through the plate 32 and apertures S l in beam 28 between the followers 44 and the pin 34, are another pair of followers 52. These followers each include a tubular member 53 which is also rigidly mounted to the plate 32 as by welding. Each of the tubular members 53 are longitudinally slotted at 54 over a portion of their length beneath the plate 32 so as to receive a rheostat actuating lever arm 56 therein, the rheostats 58 also being mounted beneath the plate by brackets 60. The rheostats are part of the drive motor control circuit and varia tion of the resistance of one or the other of the rheostats will vary the power supplied to the drive motor of the load carrier. The ends of the lever arms 56 each extend between one end of a follower plunger 62 which is moveable axially in the tubular member 53 and a short cap member 64 which is normally urged in an upward direction by a spring 66 which bears against a closed end 68 of the tubular member. The plungers 62 each have a follower roller 70 rotatably mounted at its ex terior end and the extent of the upward motion of the plungers are limited by a laterally extending pin 72 which extends through a second slot 74 longitudinally extending over a portion of the length of the tubular member between the upper face of plate 32 to just short of the upper end of the tubular member.
At the end of the aisle at the point where the carrier is to be slowed, an inclined cam surface 76 is attached internally of the guidance rail 14 to one of its flanges 24. The cam surface of the cam 76 is inclined so as to variably decrease the distance between it and the plane defined by the flange edges 48 as the end of the rail is approached. The cam 76 is positioned so as to be engaged by one of the rollers 70. The cam surface may either be linear in nature or curvilinear, depending upon the resistance change characteristics desired.
IOIOIS 0203 A suitable enclosure 78 is preferably formed about the rheostats and other portions of the speed-control device underlying beam 28 so as to protect them from dust or severe environmental conditions.
In operation, when the load carrier 16 is in a position intermediate ends of the guidance rail 14, the spring 40 will normally urge the plate 32 upward, as viewed in FIG. 2, so that rollers 46 are continuously in contact with the edges 48 of the flanges 24, the edges 48 defining a reference plane over the entire path of operation of the load carrier. Since the inclined cam 76 is attached only at the ends of the rail 14, springs 66 will urge plungers 62 and their rollers 70 upward until pins 72 engage the upper end of the slots 74 in the tubular members 53, spacing the rollers 70 a given distance above rollers 46 and their reference plane. Since the tubular members 53 are fixed to the plate 32, any movement of plate relative to beam 28 will also cause simultaneous and equal movement to occur in the follower rollers 46, the plungers 62 and their rollers 70, and rheostats 58. Therefore, during normal operation, rollers 70 will remain extended in their fully upward position and continuously spaced at a given distance from rollers 46 and the reference plane defined by flange edges 48 even through the overhead beam 28 of the load carrier may move relative to the guidance rail 14 during operation.
As the load carrier 16 approaches the end of the guidance rail 14, one of the upward extending rollers 70 will come into contact with cam surface 76. Since the cam surface is inclined relative to the plane defined by the edges 48 of the flanges, further movement toward the end of the rail, will urge one of the plungers 62 downward as shown in the right plunger in FIG. 2, the roller 70 rolling along the underside of the cam surface. Downward movement of the plunger will effect rota tion of lever arm 56 of one of the rheostats 58 in a counterclockwise direction, as viewed in the right assembly of FIG. 2, progressively varying the resistance of the rheostat to gradually slow the load carrier and ultimately, if desired, stop the load carrier at the end of the rail.
The left plunger and roller shown in FIG. 2 is positioned for cooperation with another inclined cam surface (not shown) at the other end of the aisle to slow down and stop the load carrier when it is in motion in the opposite direction.
From the above description it will be seen that the speedcontrol device constructed in accordance with the principles of the invention is positioned ready at all times during the course of operation in a first reference plane, such that slowdown operation can be commenced at any time that one of the follower rollers 70 contacts an inclined cam which is positioned relative to the reference plane.
Although the speed-control device of the invention has been described as being employed as an end-of-run slowdown device, the principles of the invention may be employed at any point along the path of travel where it is desired to slow a moveable assembly. Moreover, the speed-control device need not be mounted at the top of the moveable assembly, but may be readily employed either in conjunction with floor rails or other lateral guidance structure, the top mounting arrangement being preferred, since the components of the speed-control device are less susceptible to damaged lt will also be understood that the embodiment of the present invention which has been described is merely illustrative of an application of the principles of the invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention.
What is claimed is:
l. A device for variably controlling the speed of an assembly which is movable relative to another assembly, comprising:
first reference plane establishing means defining a first reference plane,
second reference plane establishing means defining a second reference plane, the distance between said first and second reference planes being variable,
follower positioning means including means mounting said follower positioning means for movement toward said first reference plane when the distance therebetween is varied, said follower positioning means positioning first follower means in said first reference plane and also normally positioning second follower means a given distance relative to said first follower means, said positioning means including means responsive to the contact and movement of one of said second follower means and said second reference plane relative to the other to vary said given distance between said first and second follower means, and
control means which provides a variable output in response to the variation of distance between said first and second follower means.
2. The device of claim 1 wherein said second reference plane establishing means comprises an elongated cam surface inclined relative to said first reference plane.
3. The device of claim 1 wherein said follower positioning means comprises:
first mounting means stationarily mounting said first follower means on said support means and second mounting means mounting said second follower means on said support means for movement relative to said support means and including urging means normally urging said second follower means into a first position in which said second follower means is spaced said given distance from said first follower means, said urging means being overcome when said second follower means contacts and moves relative to said second reference plane so that said second follower means is moved to a second position in which the distance between said first and second follower means is varied.
4. The device of claim 1 wherein said control means is a variable rheostat.
5. The device of claim 1 wherein at least one of said first and second follower means includes a roller which is rollably moveable in its respective reference plane.
6. In an installation in which an assembly is moveable by drive means along a predetermined path, a device for slowing the movement of said assembly when the assembly approaches a given point in said path, comprising in combination therewith:
first stationary plane means,
second stationary plane means adjacent said point in said path and inclined relative to said first plane means, follower support means on said assembly carrying first and second follower means,
first mounting means mounting said follower support means for movement relative to said assembly so that said first follower means are continuously positioned in the plane of said first stationary plane means when the distance between the plane and the assembly is varied,
second mounting means mounting said second follower means so that said second follower means are moveable between a first position in which said first and second follower means are spaced a given distance from each other and a second position in which the distance between said follower means is varied in response to contact with said second plane means, and
control means for variably controlling said drive means in response to the movement of said second followers means between said positions.
7. The installation of claim 6 including stationary guidance means for guiding said assembly along said predetermined path, said guidance means defining said first stationary plane means.
8. The installation of claim 7 wherein said second plane means is attached to said guidance means.
9. The installation of claim 6 including an elongated stationary channel member, the edge of at least one flange of said channel member defining said first plane means and said second plane means being carried by said channel member.
10. The installation of claim 6 wherein said follower means include rollers for rollably contacting said first and second lOlOl 5 0204 3 ,628 ,463 5 6 plane means and said control means comprises a variable rheostat the resistance of which is varied in response to the movement of said second follower means between said positions.
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