US20070295851A1

US20070295851A1 - Recoil speed control

Info

Publication number: US20070295851A1
Application number: US11/471,803
Authority: US
Inventors: Donald L. Metz; Wendell K. Moulton
Original assignee: DL Manufacturing Inc
Current assignee: DL Manufacturing Inc
Priority date: 2006-06-21
Filing date: 2006-06-21
Publication date: 2007-12-27

Abstract

In a spring loaded shaft for automatically rewinding a cord or the like after it has been unwound for temporary use, provision is made for reducing the whipping effect by slowing the speed in which the rewinding occurs. An elongate member is attached to an end of the shaft and is disposed within a liquid substance contained in a housing such that rotation of the shaft is slowed by the interaction of the elongate member with the liquid substance.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to winding mechanisms and, more particularly, to a device for retarding the speed of a spring-loaded retracting mechanism.
There are various types of portable electrical powered appliances which are provided with a considerable length of electrical cord to allow for the appliance to be moved a substantial distance from the electrical outlet and then providing a spring loaded cord take-up mechanism for retracting and storing the cord. A vacuum cleaner was one of the earliest appliances to provide such an arrangement, but other appliances such as hair dryers, irons and kitchen appliances such as toasters and the like are now provided with this feature. Although such an apparatus provides a convenient storage apparatus for the cord which is not in use, the “whipping” of the cord as it is being rewound can be quite severe and dangerous to someone in the vicinity. This is especially true for longer cords where the spring tension of the recoil apparatus must be stronger to accommodate the longer length.
In addition to the portable devices as discussed hereinabove, there are various stationary installations where automatic rewinding mechanisms are used. For example, there may be areas that need to be temporarily closed off from entry or exit, with a line or tape being strung across an area to temporarily close it off but later allow the line or tape to be removed and stored in a housing to get it out of the way. An example of such a device is at the dock of a warehouse. Although the safest approach is to have a solid door that is open only at times when the truck is backed up to the opening and closed at all other times, there are occasions when this is not practical, such as where there is a need for ventilation in the warehouse, for example. Thus, a tape or strap across the opening provides a visual indication that the space is not open for use, and caution should be taken when one is in that vicinity. For these installations, it is very desirable to have an automatic retracting mechanism to get the strap out of the way, but, because of its substantial length, the “whipping” of the strap can be dangerous to bystanders.

SUMMARY OF THE INVENTION

Briefly, in accordance with one aspect of the invention, a rewinding storage mechanism is provided with apparatus for retarding the speed in which the rewinding occurs, thus reducing the “whipping” effect of the cord or strap that is being rewound.
By another aspect of the invention, a drag mechanism is applied to the reel of the rewinding apparatus such that the rewinding of the cord or strap occurs at a safe speed.
By yet another aspect of the invention, the drag mechanism comprises a rotating arm on the axle of the reel, with resistance being provided to the rotation of the arm, and thus, to rotation of the reel.
By still another aspect of the invention, the drag arm is located in a housing with the housing then being filled with a fluid which offers resistance to rotation of the arm within the housing. A preferred form of the fluid is a grease.
In the drawings as hereinafter described, a preferred embodiment is depicted; however, various other modifications and alternate constructions can be made thereto without departing from the spirit and scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the invention as applied to a cargo door opening.

FIG. 2 is an exploded perspective view of the storage and dispensing receptacle thereof.

FIG. 3 is an exploded perspective view of the receiving receptacle thereof.

FIG. 4 is a perspective view of the storage and dispensing receptacle as assembled.

FIG. 5 is a perspective view of the receiving receptacle as assembled.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is shown generally at 10 as applied to the framework 11 of a doorway on the outer wall of warehouse wherein the unloading and loading of trucks can be conducted. The system includes a storage/dispensing apparatus 13 mounted on one side of the doorway, a receiving apparatus 14 mounted on the other side thereof, and a strap 16 which can be temporarily extended between the two when in use or stored in the storage apparatus 13 when not in use.
In practice, the preferred approach in the loading dock industry is to provide doors that can be closed in the doorway during periods when the dock is not in use and to open the doors only during periods when loading or unloading is taking place. However, there may be various reasons, such as the need to provide ventilation to the warehouse during hot ambient conditions, when it is desired to leave the door open when the dock is not in use. At such times, it is desirable to present some form of visual barrier at the doorway 12 in order to prevent accidents. For that purpose it has become common to extend a strap across the doorway 12 during such periods. It has become an industry standard that such an extended strap must be capable of withstanding a force of 200 pounds. Therefore, the mechanism and the components must be relatively robust to meet these requirements.
During periods in which the strap 16 is not in use, it is highly desirable to provide some kind of storing facility so that the strap 16 does not become an obstacle to the workers operating in the area. For that reason, it has been a common procedure to provide a recoil or rewinding mechanism in the storage/dispensing apparatus 13. One approach is to use a coil spring that is loaded during periods in which the strap is being extended, such that, it can be automatically rewound into the storage/dispensing apparatus when desired. The problem that has been recognized by the applicants is that during the rewinding process, the strap tends to be “whipped” around and can be dangerous to a worker in the vicinity. That is, because of the substantial length of the strap 16, the tension of the coil spring must be relatively high in order to ensure a complete rewinding of the strap 16 and, with this higher tension, the strap is necessarily rewound at a relatively high rate. The danger of this whipping effect is exacerbated by the fact that a fairly robust retaining pin is connected to the end thereof. The present invention is designed to solve this problem.
Referring now to FIGS. 2 and 4, the storage/dispensing apparatus is shown with is various components in an exploded position and in the assembled position respectively. It includes a U-shape spacer 17 that is attached to the wall in such a manner as to provide a space to allow clearance for the strap to pass in front of the door track. Attached to the U-shaped spacer 17 is a U-shaped housing 18 that is secured to an outer edge of the U-shaped spacer 17 by a plurality of fasteners 19. The U-shaped housing 18 has a slot 20 formed therein for the strap 16 to pass therethrough.
Mounted by fasteners in the upper portion of the U-shaped housing 18 is an upper plate 21 that closes the top portion of the U-shaped housing 18. The upper plate 21 has a round depression or cavity 22 formed in it upper surface, and a central opening 23 is formed in the bottom thereof as shown. A coil spring 24 is disposed within the cavity 22 with its outer end 26 fitting into an indention 27 adjacent the edge of the cavity 22. The inner end 28 of the coil spring 24 is secured to a shaft as will be described hereinafter.
With the coil spring 24 installed in place, a cover 29 is secured to the top surface of the upper plate by fasteners 31. A central opening 32 may be provided in the cover 29 for the purpose of having the end of a shaft extending therethrough but this is not a necessary feature.
Formed on one edge of the cover 29 is a notch 33 which registers with a groove 34 on one edge of the upper plate 21 for receiving a guide member as will be described hereinafter.
Secured to the lower end of the U-shaped housing 18 is a lower plate 36 so as to close the lower end of the housing 18. A lower cavity 37 and central opening 38 are centrally formed in the lower plate as shown. A lower slot 39 is formed in one edge of the lower plate 36 for a purpose to be described hereinafter.
A vertically orientated shaft 41 is mounted within the housing 18 with an upper end thereof passing through the opening 23 and a lower end thereof passing through the opening 38. A shaft seal 42 is disposed on shaft 41 and fits into the lower cavity 37 with the shaft 41 being rotatable therein.
Formed near the top end of the shaft 41 is a flat surface 43 and an associated opening 44 for securing the inner end 28 of the coil spring 24 therein. With this connection being made, as the shaft 21 is rotated in the clockwise direction, the coil spring 24 will be stressed to a load condition as will be more fully described hereinafter.
Formed in the lower end of the shaft 41 is an axially extending slot 46 that passes through the central opening 38 and is attached to an element that plays an important part in the present invention as will be described hereinafter.
Mounted to the lower surface of the lower plate 36 is a bottom cover 47 which is secured thereto by a plurality of fasteners 48 with a gasket 49 therebetween. The bottom cover 47 has a centrally disposed depression or cavity 51 formed therein. Disposed within the cavity 51 is an S-shaped wire 52 that is centered within the cavity 51 such that the slot 37 at the lower end of the shaft 41, slips over the wire and causes it to rotate within the cavity 51 as the shaft 41 rotates. It is a feature of the present invention that a liquid material be placed within the cavity 51 so as offer resistance to the rotation of the wire 52 as it rotates within the cavity 51. For that purpose any type of liquid will suffice and is preferred over any type of solid material which will cause wear and noise. A thick or viscous liquid material is preferred and, in particular, grease has been found to be quite satisfactory in performance. Since the handling of food products often occurs around loading docks, a food grease is preferred over an industrial grease. The gasket 49 presents a tight fit between the lower plate 36 and the lower cover 47 to ensure that leakage of the grease does not occur.
The particular shape and material of the wire element 52 can vary substantially while still serving the function as intended. It could be formed of plastic and could be in the form of a flat ribbon, for example. It could also be formed of metal and be flat or round in shape. It should be flexible but not so pliable that when bent that it will not spring back to it original shape. A material which has been found to be very suitable is stainless steel.
Although the S-shape has been found to be helpful in centering the wire in the cavity 51 such that the shaft slot may be easily slid over the wire, other shapes can be used, such as a straight wire that extends linearly across the cavity 51. The diameter of the wire 52 and the depth of the cavity 51 have been found to be somewhat related in considering the amount of grease that is to be used and the amount of resistance that is desired. Generally, it has been found that a cavity with a depth of about twice the diameter of the wire 52 is quite suitable in practice.
In practice, the strap 16 is wound onto the shaft 41 such that it is stored within the housing 18 with an end passing through the slot 20 and available to be pulled out when needed. As the strap 16 is extended outwardly, the shaft 41 is rotated in a clockwise direction to place the coil spring 24 in a stressed condition. When use of the strap 16 has been completed, the tension on the strap 16 is released and the coil spring 24 is free to move to an unstressed or unwound condition, while at the same time, the shaft 41 acts to rewind the strap 16 into a coiled and stored position. As the shaft 41 rotates for that purpose, the wire 52 is also caused to rotate, with the grease 53 offering resistance and slowing the rotation of both the wire 52 and the shaft 41 such that the strap moves relatively slowly in passing from its outstretched position to its stored position.
The material for the upper plate 21 is preferably formed of an MD nylon since MD nylon offers low friction to both movement of the coil spring 24 within the cavity 22 and also rotation of the shaft 41 within the opening 23. Similarly, the lower plate 36 is preferably formed of an MD nylon so as to provide long wear and little friction for the shaft 41 rotating within the opening 38 and also offer little friction to the movement of the strap 16 over the top surface of the lower plate 36.
The guide 54 with a vertically extending slot 56 is attached to and extends between the upper plate 21 and the lower plate 36 and fits into the respective slots 34 and 39. The central slot 56 provides a guide for the strap 16 that extends therethrough.
Considering now what occurs at the other end of the strap 16, the receiving apparatus 14 is shown in FIGS. 3 and 5 and includes a spacer element 57 that is attached to and extends the unit outwardly from a door framework. A housing 58 is attached to the spacer 57 by fasteners 59. Formed in the upper wall 61 of the housing 58 is an opening 62 that is aligned with an opening 63 formed in a block 64 that is located within the housing 58.
Attached at the end of the strap 16 is a securing device 66 which comprises an L-shaped element that is secured to the strap 16 by plate 68 and associated fasteners 69. A securing pin 71 is attached, as by welding to the end of the L-shaped element 67 as shown. To place the strap 16 in the secured position, the pin 71 is inserted through the opening 62 and into the opening 63 of the block 64.
A sensor 72 which is mounted by way of bracket 73 includes a proximity switch to sense when the pin 71 is in place such that appropriate warning devices may be activated. A cover 74 is provided to complete the covering of the housing.
Although the present invention has been described in terms of use with a storage/dispensing apparatus for a strap to be extended across a dock door opening, it should be recognized that the present invention may as well as be used with any type of spring loaded recoil apparatus where it is desired to avoid the whipping effect of the item being recoiled. For example, there are various types of electrical appliances such as vacuum cleaners, hair dryers, irons and the like which provide a recoiling feature for the electrical cord, with a plug on the end being subject to the whipping effect as the cord is recoiled. The present invention is intended to slow the recoiling process such that the whipping effect is reduced or eliminated.

Claims

1. Apparatus for controlling the recoil speed of a spring loaded shaft of the type which is mounted in a housing and adapted to have wound thereon a length of material for storage and allow the length of material to be unwound for use and automatically rewound for storage, comprising:

an elongate member attached to said shaft and extending radially outwardly therefrom;

a housing surrounding said elongate member and allowing said elongate member to be rotated therein as the shaft rotates; and

a liquid substance disposed in said housing and offering resistance to rotation of said elongate member when rewinding occurs.

2. Apparatus as set forth in claim 1 wherein said shaft is centered in said housing and said elongate member extends substantially radially outwardly in opposite directions therefrom.

3. Apparatus as set forth in claim 1 wherein said elongate member is round in cross sectional shaped.

4. Apparatus as set forth in claim 3 wherein said elongate member comprises a wire.

5. Apparatus as set forth in claim 1 wherein said liquid substance is a grease.

6. Apparatus as set forth in claim 5 wherein said grease is a food grease.

7. Apparatus as set forth in claim 1 wherein said housing includes a cavity in which the liquid substance is disposed.

8. Apparatus as set forth in claim 7 wherein the depth of said cavity is substantially two times the height of the elongate member.

9. Apparatus as set forth in claim 1 wherein said string is attached to one end of said shaft and said elongate member is attached to the other end thereof.

10. Apparatus as set forth in claim 1 wherein said elongate member is a strap.

11. A storage assembly for storing a windable length of material, comprising:

a rotatable reel for winding and unwinding the length of material;

a spring attached to said reel for allowing the reel to rotate in one direction to unwind the length of material while loading the spring and in the other direction to wind up the length of material while unloading the spring; and

a drag mechanism associated with said reel to cause winding up of the length of material to occur at a reduced speed so as to thereby reduce the whipping effect that occurs in the length of material.

12. A storage assembly as set forth in claim 11 wherein said spring comprises a coil spring.

13. A storage mechanism as set forth in claim 11 wherein said drag mechanism includes a paddle arm attached to an axis of said rotatable reel.

14. A storage assembly as set forth in claim 13 wherein said drag mechanism also includes a liquid material surrounding said paddle.

15. A storage assembly as set forth in claim 14 wherein said liquid material comprises a grease.

16. A storage assembly as set forth in claim 15 wherein said grease comprises a food grease.

17. A storage assembly as set forth in claim 13 wherein said paddle is arcuately shaped and mounted such that there is greater resistance during the rewinding than during the unwinding.

18. A storage assembly as set forth in claim 11 wherein said spring is mounted on one end of said reel axes and said drag mechanism is mounted on the other end thereof.