Abstract:
A take-up reel for winding and storing an elongate hose or electrical cable comprises a reel supported by a stationary support shaft and urged in a first direction by a torsional spring. A viscous clutch assembly comprising multiple disks housed in a chamber filled with a viscous fluid is coupled to the reel to provide a retarding force that is proportional to velocity. The velocity proportional retarding force causes the rewind velocity of the reel to stabilize at a constant velocity. A one-way clutch is provided to decouple the viscous clutch from the reel when the hose or cable is being payed-out thereby permitting the hose or cable to be payed-out without resistance from the viscous clutch. By providing a unidirectional viscous clutch that acts to retard only the take-up velocity of the hose reel, it is possible to provide an apparatus that permits the hose to be payed-out at any speed while providing the substantial safety benefits of a viscous speed governor during take-up.

Description:
BACKGROUND 
     The present invention relates to take-up reels of the type for winding and paying out an elongated flexible member such as a cable, rope, hose or the like, and which automatically rewind the flexible member when it is released. 
     The art is replete with applications in which a flexible member such as a cable, rope, hose, electrical cord or the like is wound about a take-up reel for storage when not in use, and which is paid out by unwinding from the take-up reel to the appropriate length as required. A popular application for this arrangement is use of a flexible hose for carrying air, water, oil, grease, and the like from a reservoir to a dispensing nozzle at an automobile service station. For example, in the typical automobile service station, air is delivered from a compressor tank through a long pipe to a spring-loaded take-up reel about which is stored a length of tubular air hose. When air is needed, the air hose is pulled from the reel until the desired length is paid out. When the air hose is no longer in use, the end is released and a torsional spring acting on the hose reel rewinds the hose onto the reel. 
     The torque exerted by the torsional spring on the take-up reel causes the take-up reel, and with it the payed-out hose, to accelerate as the hose is taken up, with result that the terminal velocity of the hose may be quite high as the last bit of hose is retracted. The sudden stop of the mechanism when the end of the hose is reached can cause damage to the rewind mechanism and/or the hose. Moreover, the whipping action that occurs as a result of the uncontrolled rewinding speed can cause personal injury. Various breaking mechanisms have been proposed for automatically limiting the rewind rate of the take-up reel. For example, U.S. Pat. No. 4,446,884 to  Rader, Jr.  proposes use of a viscous dampening mechanism coupled between the spool and its support shaft. Being a viscous dampener, the retarding force exerted by the viscous dampener is directly proportional to the rotational speed of the reel. Accordingly, the reel will tend to seek a velocity at which the retarding force is equal to the force exerted on the reel by the torsional spring, such that the spool will attain a constant velocity. The viscous dampener disclosed in  Rader,  however, is rigidly attached to the support shaft and therefore exerts a retarding force on the hose reel irrespective of whether the hose is being payed-out or being retracted. In most applications, it is not necessary to regulate the speed at which the hose is payed-out. Accordingly, a viscous dampener that operates in both directions such as disclosed by  Rader  unnecessarily loads the hose as it is being payed-out, potentially leading to premature failure of the hose and/or the rewind mechanism. Accordingly, what is needed is a take-up reel with a viscous clutch that operates only when the hose is being retracted and therefore allows the hose reel to be decoupled from the viscous dampener when the hose is being payed-out. 
     SUMMARY OF THE INVENTION 
     The present invention satisfies the foregoing need by providing a hose reel assembly having a viscous clutch that is coupled between the hose reel and the stationary support shaft by means of a one-way clutch that engages the viscous clutch only when the hose reel is rewinding, not when the hose reel is paying-out the hose. In a preferred embodiment, the take-up reel comprises a stationary support shaft attached to a frame and a one-way clutch assembly supported for rotation by the stationary support shaft. The one-way clutch assembly is capable of rotating freely in one direction about the stationary support shaft but engages the stationary support shaft to prevent rotation in the opposite direction. The one-way clutch, in turn, is secured to a plurality of stator disks of a multi-disk viscous clutch. The rotor disks of the viscous clutch, in turn, are coupled to the hose reel. A chamber filled with a viscous fluid encloses the stator and rotor disks. The viscous fluid provides a sheering action to retard the relative motion between the stator disks attached to the one-way clutch assembly and the rotor disks attached to the hose reel. The multi-plate construction of the viscous clutch provides a highly efficient and compact retarding mechanism. A conventional torsional spring provides a biased urging the reel to fully rewind the hose wound thereon. 
     In operation, as the hose is payed out, a sheering force develops between the rotor disks coupled to the hose reel and the stator disks coupled to the one-way clutch. The sheering force exerts a slight torque on the one-way clutch causing the one-way clutch to disengage and freewheel about the stationary support shaft. Thus, the only resistance force exerted by the viscous clutch opposing this direction of motion is the torque necessary to overcome the friction inherent in the one-way clutch. Conversely, when the reel is being retracted under the urging of the torsional spring, a sheering force is developed between the rotor disks attached to the hose reel and the stator disks attached to the one-way clutch. In this direction, however, the one-way clutch engages the stationary support shaft thereby preventing rotation of the stator disks. The sheering force developed between the now static stator disks and rotor disks is proportional to the relative velocity between the stator disks and the rotor disks. Accordingly, as the rewind velocity of the hose reel builds, a counteracting torque is developed by the sheering of the viscous fluid between the stator and rotor disks until at a certain velocity, the forces balance and the hose reel attains a steady state velocity. The steady state velocity may be adjusted by, among other things, adjusting the viscosity of the fluid in the viscous clutch and/or varying the number of stators and rotors and their relative spacing. 
     By providing a uni-directional viscous clutch that acts to retard only the take-up velocity of the hose reel, it is possible to provide an apparatus that permits the hose to be payed-out at any speed without resistance from the viscous clutch while providing the substantial benefits of a viscous speed governor during take-up. The invention thus provides all of the safety benefits of a viscous speed governor without the unnecessary wear and tear inherent in a conventional bi-directional viscous clutch. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The present invention will be better understood from reading of the following detailed description, taken in conjunction with the accompanying drawing figures in which like references designate like elements, and in which: 
     FIG. 1 is a perspective view of typical application of a hose reel retractor incorporating features of the present invention; 
     FIG. 2 is an exploded perspective view of a hose reel incorporating features of the present invention; 
     FIG. 2A is an exploded perspective view of a hose reel incorporating features of a second embodiment of the present invention; 
     FIG. 3 is an exploded perspective view of the viscous clutch and one-way clutch assemblies of the hose reel of FIG. 2; and 
     FIG. 4 is an end view of a one-way clutch assembly incorporating features of the present invention. 
    
    
     DETAILED DESCRIPTION 
     The drawing figures are intended to illustrate the general manner of construction and are not necessarily to scale. In the description and in the claims, the terms left, right, front and back and the like are used for descriptive purposes. However, it is understood that the embodiment of the invention described herein is capable of operation in other orientations that is shown and the terms so used are only for the purpose of describing relative positions and are interchangeable under appropriate circumstances. 
     With reference to FIG. 1, a reel assembly  10  having a uni-directional viscous clutch incorporating features of the present invention is illustrated, by way of example, as use for paying out and taking up a length of an elongate member such as high-pressure air hose  12  from a cabinet  14  mounted to a service station island  16 . In this application, high-pressure air is delivered from an air compressor (not shown) to a conventional swivel joint  44  which delivers it to the inlet of air hose  12 . The terminal end  20  of air hose  12  is fitted with a conventional air chuck or other terminal apparatus  22 . When it is desired to provide high-pressure air service, the terminal end  20  of air hose  12  is pulled from the reel assembly  10  to the desired length. When the length of air hose  12  is no longer needed, terminal end  20  is released by the user to allow reel assembly  10  to rewind the hose under the urging of a torsional spring acting on the reel  24  of reel assembly  10 . 
     With reference to FIG. 2, reel  24  of reel assembly  10  comprises outer-reel half  24 A and inner-reel half  24 B which are secured together to form a reel  24  having a substantially cylindrical body portion  26  with radially extending flange portions  28  and  30  at the respective inner and outer ends thereof. Reel  24  is supported for rotation by a stationary support shaft  32  attached to subframe  34 . Subframe  34  in turn may be mounted to a wall, frame, or to the interior surface of an enclosure such as enclosure  14  shown in FIG.  1 . Disposed within cylindrical body portion  26  is a spring can  36  in which is housed a conventional multiple turn torsional spring  38 . Spring  38  may be a spiral wound spring similar to a watch spring, or may be a conventional negator spring. The outer end of torsional spring  38  is secured to spring can  36 . The inner end of torsional spring  38  is secured to stationary shaft  32  by means of a slot and setscrew, keyed hub, or other conventional means. Spring can  36  is secured within body portion  26  by a plurality of studs  40  passing through corresponding apertures  42  in inner and outer reel halves  24 A and  24 B. Inner-end  42  of air hose  12  is coupled to inlet line  18  by means of a conventional swivel joint  44  via elbow fitting  46 . (As shown in FIG. 2 a,  in an alternative embodiment of reel assembly  10  in which an electrical cord is wound about reel  24 , a conventional slip-ring connector  47  is substituted for swivel joint  44 ). With reference again to FIG. 2, terminal end  22  of air hose  12  may be equipped with a conventional hose stop  48  to prevent air hose  12  from being withdrawn completely into cabinet  14 . A snubbing roller  52  is attached to subframe  34  to act as a guide to constrain air hose  12  to wind onto reel  24 . A uni-directional viscous clutch assembly  50  discussed more fully hereinafter, is disposed between reel  24  and support shaft  32  to provide a viscous retarding force that governs the retraction speed of reel  24  but does not inhibit the free paying-out of hose  12  from reel  24 . 
     FIG. 3 is an exploded perspective view of the unidirectional viscous clutch assembly  50  incorporating principles of the present invention. Uni-directional viscous clutch assembly  50  comprises a housing  54  having apertures  56  adapted to be bolted to corresponding apertures  58  passing through outer and inner reel halves  24 A and  24 B (FIG.  2 ). Housing  54  includes an annular chamber  60  having a radially inward wall  62  and a radially outward wall  64 . A one-way clutch assembly  66  includes a collar member  68  and a one-way clutch  70 . One-way clutch  70  is a press-fit in bore  72  of collar member  68  and/or may be retained by conventional anaerobic thread locking adhesives such as LOCTITE, such that one-way clutch  70  is rigidly attached to collar member  68  without the possibility of rotation therebetween. One-way clutch assembly is disposed in chamber  60  such that keyed surface  74  is completely within chamber  60  while sealing surface  76  protrudes beyond flush with surface  78  of housing  54 . A radial seal such as a conventional O-ring  80  seals inner-bore  72  of collar member  68  to radially inward wall  62  of chamber  60  thereby providing a fluid tight seal therebetween. 
     A plurality of stator disks  82  and rotor disks  84  each comprising disks of a hollow substantially circular cross-section are disposed in chamber  60  in an alternating fashion with the rotor disks attached to the housing  54  and the stator disks  82  interleaved therebetween and attached to the collar member  68  to form a plurality of annular gaps between stator disks  82  and rotor disks  84 . In the embodiment of FIG. 3, the rotor disks are attached to housing  54  by means of a plurality of tabs  86  extending radially outward from rotor disks  84  engaging a plurality of corresponding slots  88  formed in radially outward wall  64  of chamber  60 , however, other means of attaching the rotor disks  84  to housing  54  such as splines, clips, adhesives, or other conventional methods are within the scope of the invention. Accordingly, as used herein, the term “attached” when used with reference to the interaction between the housing  54  and the rotor disks  84  means rigidly attached or attached in such a way so as to preclude substantial rotation therebetween. As used herein with reference to stator disks  82  and rotor disks  84 , a hollow “substantially circular” cross-section means that the majority of the surface area of the disks lie within a hollow circular region defined by an inner radius and an outer radius, but does not preclude the presence of splines, tabs or other irregularities along the inner and outer radii. 
     The stator disks  82  are attached to collar member  68  by means of a plurality of tabs  90  that engage a plurality of corresponding slots  92  formed in keyed surface  74  of collar member  68 . As with the attachment of the rotor disks  82  to housing  54 , the attachment of stator disks  84  to collar member  68  may be accomplished with splines, clips, adhesives, or other conventional methods that preclude substantial rotational motion between the stator disks  82  and the collar member  68 . Accordingly, as used herein with respect to the attachment of the stator disks  82  to the collar member  68 , the word “attachment” means, when used with reference to the interaction between the collar member  68  and the rotor disks  84 , rigidly attached or attached in such a way so as to preclude substantial rotation therebetween such as with splines or the tabs  86  and slots  88  of the embodiment of FIG. 3 by “substantially” precluding relative motion between the stator and rotor disks and the housing and collar member, respectively, what is meant is that the relative motion is not so great as to prevent the viscous dampener from acting to retard the velocity of the reel in a multiple revolution application. Accordingly, a quarter-turn, a half-turn or even more of tolerance between the disks and their respective housing  54  and collar member  68  is tolerable so long as the disks would be precluded from making more than one revolution relative to their respective housing  54  and collar member  68 . 
     A cover  94  seals against surface  78  of housing  54 . A conventional radial seal such as O-ring  96  is disposed in an O-ring groove  98 . O-ring  96  seals cover  94  against sealing surface  76  of collar member  68  thereby providing a completely sealed chamber  60 . Chamber  60  is then filled with a viscous fluid such as 30,000 CS silicone fluid through fill plugs  100  and  102 . It should be noted that use of a plurality of stator and rotor disks in a single chamber enables viscous clutch assembly  50  to be of substantially more compact construction than the single plate viscous dampener of the prior art. 
     FIG. 4 is an end view of a preferred one-way clutch assembly  66  comprising collar member  68  and one-way clutch  70  disposed about support shaft  32 . One-way clutch  70  comprises a plurality of rollers  104  disposed within a cavity  106  defined by outer surface  108  of support shaft  32  and inner cylindrical surface  110  of one-way clutch  70 . Outer surface  108  comprises a series of ramps  112  arranged in a saw tooth pattern around the perimeter of surface  110 . The ramps are arranged such that the radial clearance between outer surface  108  of support shaft  32  at each of the tips  114  of ramps  112  is less than the diameter of rollers  104  and the radial clearance between surface  108  of shaft  32  and the root  116  of ramps  112  are greater than the diameter of rollers  114 . Accordingly, as collar member  68  is rotated in the direction indicated by arrow A in FIG. 4, rollers  104  are jammed between outer-surface  108  of shaft  32  and inner-surface  110  of collar member  68  thus preventing substantial rotational motion between collar member  68  and shaft  32  (i.e. no more rotation than is necessary to effect the initial lock-up). Conversely as collar member  68  is rotated opposite the direction indicated by arrow A, roller members are freed to assume the orientation shown in FIG. 4 which permits them to slide easily over shaft  32  thereby providing substantially no resistance (i.e. other than ordinary friction) between collar member  68  and shaft  32  thereby permitting collar member  68  to freewheel about shaft  32 . 
     As is evident from the foregoing, with the one-way clutch  70  oriented such that the direction indicated by arrow A in FIG. 4 corresponds to the take-up direction, as hose  12  is unwound from the reel  24 , roller member  104  of one-way clutch  70  disengage from shaft  32  thereby permitting collar member  68  (and with it the rest of reel assembly  10 ) to freewheel about support shaft  32  resisted only by the torque exerted by torsional spring  38 . When hose  12  is released, the rewind force developed by torsional spring  38  causes rotation of reel  24  in the take-up direction indicated by arrow A of FIG.  4 . As this occurs, roller members  104  of one-way clutch  70  assume the engaged position against shaft  32  thereby preventing relative motion between collar member  68  and shaft  32 . Stator disks  82 , which are attached to collar member  68  therefore are held stationary within chamber  60  of housing  54 , while rotor disks  84  rotate with housing  54  and reel  24  under the urging of torsional spring  38 . As this occurs, the silicone fluid filling the gaps between rotors  84  and stators  82  is sheared, thereby giving rise to a viscous retarding force that is proportional to the relative velocity between rotor disks  84  and stator disks  82 . Since this viscous retarding force is proportional to velocity, the retarding force will be small as the hose reel begins to move and will build as the velocity of the hose reel increases, until the retarding force balances the torque exerted by the torsion spring  38 . Once the torques are equal, the hose reel will assume a constant rotational velocity thereby smoothly retracting the hose  12  onto reel  24  at a controlled retraction rate. As is evident from the foregoing, use of a uni-directional viscous clutch assembly  50  enables a controlled retraction rate to be effected without limiting the rate at which the hose may be payed-out, thus achieving the safety advantages of a viscous retarding mechanism without the deleterious effects of a bi-directional viscous dampener on the life of the hose and/or the remaining components of the hose reel assembly. 
     Although certain preferred embodiments and methods have been disclosed herein, it will be apparent from the foregoing disclosure to those skilled in the art that variations and modifications of such embodiments and methods may be made without departing from the spirit and scope of the invention. For example, if collar member  68  is keyed, splined or otherwise fixed to support shaft  32  to prevent rotation in either direction, the advantages of the multi-plate viscous clutch (i.e. compact construction) will still be realized although the advantages of the uni-directional viscous clutch would be sacrificed. Accordingly, it is intended that the invention shall be limited only to the extent required by the appended claims and the rules and principles of applicable law.