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  
       [0001]    This invention relates generally to winding mechanisms and, more particularly, to a device for retarding the speed of a spring-loaded retracting mechanism. 
         [0002]    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. 
         [0003]    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  
       [0004]    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. 
         [0005]    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. 
         [0006]    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. 
         [0007]    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. 
         [0008]    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  
         [0009]      FIG. 1  is a perspective view of the invention as applied to a cargo door opening. 
           [0010]      FIG. 2  is an exploded perspective view of the storage and dispensing receptacle thereof. 
           [0011]      FIG. 3  is an exploded perspective view of the receiving receptacle thereof. 
           [0012]      FIG. 4  is a perspective view of the storage and dispensing receptacle as assembled. 
           [0013]      FIG. 5  is a perspective view of the receiving receptacle as assembled. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]    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. 
         [0015]    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. 
         [0016]    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. 
         [0017]    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. 
         [0018]    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. 
         [0019]    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. 
         [0020]    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. 
         [0021]    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. 
         [0022]    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. 
         [0023]    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. 
         [0024]    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. 
         [0025]    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. 
         [0026]    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. 
         [0027]    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. 
         [0028]    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. 
         [0029]    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 . 
         [0030]    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. 
         [0031]    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 . 
         [0032]    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 . 
         [0033]    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. 
         [0034]    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.