Abstract:
A take-up reel for winding and storing an elongate hose or electrical cable comprises a reel that is rewound by a torsional spring. A viscous clutch is coupled to the reel by means of a unidirectional clutch, which engages the viscous clutch to the reel to rewind the reward speed, but disengages the viscous clutch from the reel when the hose or cable is being payed-out. This permits the hose or cable to be payed-out without resistance from the viscous clutch. The uni-directional viscous clutch assembly thus allows the hose to be payed-out at any speed while providing the substantial safety benefits of a viscous speed governor during rewind.

Description:
This application is a continuation-in-part of application Ser. No. 09/323,300 filed Jun. 1, 1999, now U.S. Pat. No. 6,234,417. 
    
    
     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, cord or hose, and which automatically rewind the flexible member when it is released. 
     The art is replete with apparatus 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, or grease 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, it would be advantageous to reduce the possibility that the whipping action occurring as a result of the uncontrolled rewinding speed might cause personal injury. Various braking 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 damping mechanism coupled between the spool and its support shaft. Being a viscous damper, the retarding force exerted by the viscous damper 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 damper 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 damper 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 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 unidirectional viscous damper assembly. In the illustrative embodiment, the unidirectional viscous damper assembly consists of a viscous clutch and a unidirectional clutch. The viscous clutch is operatively coupled between the hose reel and the stationary support by means of the unidirectional clutch that engages the viscous clutch only when the hose reel is rewinding, not when the hose reel is paying-out the hose. The take-up reel comprises a stationary support shaft attached to a frame and a unidirectional clutch assembly supported for rotation by the stationary support shaft. The unidirectional 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 unidirectional clutch, in turn, is secured to a plurality of stator disks of a multidisk 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 shearing action to retard the relative motion between the stator disks attached to the unidirectional 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 shearing force develops between the rotor disks coupled to the hose reel and the stator disks coupled to the unidirectional clutch. The shearing force exerts a slight torque on the unidirectional clutch causing the unidirectional clutch to disengage and freewheel about the stationary support shaft. Thus, the only resistance force exerted by the viscous clutch assembly opposing this direction of motion is the torque necessary to overcome the friction inherent in the unidirectional clutch. Conversely, when the reel is being retracted under the urging of the torsional spring, a shearing force is developed between the rotor disks attached to the hose reel and the stator disks attached to the unidirectional clutch. In this direction, however, the unidirectional clutch engages the stationary support shaft thereby preventing rotation of the stator disks. The shearing 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 shearing 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 an alternative embodiment of a take-up reel incorporating features of the present invention; 
     FIG. 3 is an exploded perspective view of the viscous clutch and unidirectional clutch assemblies of the hose reel of FIG. 2; 
     FIG. 4 is an end view of a ramp-and-ball unidirectional clutch assembly incorporating features of the present invention; 
     FIG. 5 is an end view of a ratchet and pawl unidirectional clutch assembly incorporating features of the present invention; 
     FIG. 6 is a perspective view of a saw tooth axial gear coupling unidirectional clutch assembly incorporating features of the present invention; 
     FIG. 7 is an exploded side elevation view of a helical spring clutch unidirectional clutch assembly incorporating features of the present invention; and 
     FIG. 8 is an end view of an alternative embodiment of a viscous clutch incorporating features of the present invention. 
     FIG. 9 is an end view of an alternative embodiment of a viscous clutch 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 assembly incorporating features of the present invention is illustrated, by way of example, as used for paying out and taking up a length of 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 . (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 . In another alternative embodiment of reel assembly  10  in which rope or cable is wound about reel  24 , no rotating connection is required). 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 a viscous clutch assembly  50  incorporating principles of the present invention. 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 unidirectional clutch assembly  66  includes a collar member  68  and a unidirectional clutch  70 . Unidirectional clutch  70  is a press-fit in bore  72  of collar member  68  and/or may be retained by conventional anaerobic adhesives such as LOCTITE, such that unidirectional clutch  70  is rigidly attached to collar member  68  without the possibility of rotation therebetween. Unidirectional 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 vanes are disposed in chamber  60  to provide the viscous damping action, for example, in the illustrative embodiment, the vanes constitute stator disks  82  and rotor disks  84  each comprising disks of a hollow substantially circular cross-section that 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 one unidirectional clutch assembly  66  comprising a ramp-and-ball or ramp-and-roller overrunning clutch assembly. In the embodiment of FIG. 4, collar member  68  and unidirectional clutch  70  are disposed about support shaft  32 . Unidirectional clutch  70  comprises a plurality of balls or rollers  104  disposed within a cavity  106  defined by outer surface  108  of support shaft  32  and inner cylindrical surface  110  of unidirectional 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 . 
     Although the embodiment of FIG. 4 comprises a ramp-and-ball or ramp-and-roller type of unidirectional clutch, other unidirectional clutch assemblies may be advantageously used in accordance with the principles of the present invention. As shown in FIG. 5, a ratchet and pawl clutch comprising ratchet gear  140  and ratchet pawl  142  may advantageously be used to provide the desired unidirectional clutching action. In the embodiment of FIG. 5, ratchet pawl  142  is attached to outer reel  24 A and engages ratchet gear  140 , which is keyed to shaft  144 . Shaft  144  is in turn keyed to stator disks  82  (FIG. 3) of viscous clutch assembly  50  which, in turn, is supported by subframe  34 . Although both the embodiment of FIG.  3  and the embodiment of FIG. 4 effect an operative unidirectional viscous damping between the reel and the support, in the embodiment of FIG. 3 the unidirectional viscous damping is effected by the unidirectional clutch disengaging the viscous damper from the support. In contradistinction, in the embodiment of FIG. 4, the unidirectional viscous damping is effected by the unidirectional clutch disengaging the reel from the viscous clutch. 
     FIG. 6 depicts an alternative embodiment in which the unidirectional clutch comprises a saw tooth axial gear coupling  160 . Coupling  160  comprises hubs  162  and  164  each having a plurality of mating axially-engaging gear teeth  166  and  168  having a saw tooth profile. Flange  170  of coupling  160  is attached to outer reel  24 A while hub  162  is keyed to stator disks  82  of viscous clutch assembly  50  (FIG. 3) as discussed above. Hub  162  and  164  are biased together by an axial spring (not shown) acting on hub  162  such that the engagement of axially-engaging gear teeth  166  and  168  is maintained when hub  164  is rotated in a first direction, but the axially-engaging gear teeth  166  and  168  disengage and skip relative to each other when hub  164  is rotated in the opposite direction. 
     FIG. 7 depicts an alternative embodiment in which the unidirectional clutch comprises a helical spring clutch  170 . Helical spring clutch  170  comprises a helical spring  172  that has a slight interference fit over hub  174  and hub  176 . As can be determined with reference to FIG. 7 if the relative rotation of hub  174  relative to hub  176  is opposite the direction of wind of helical spring  172 , spring  172  will tend to expand and transmit very little torque, whereas if the rotation reverses, spring  172  will tend to contract and will transmit substantial torque between hub  174  and  176 . Where, as in the present invention, the disengaged rotational speeds are relatively low, frictional heating is not of concern and, therefore a simple inexpensive clutch such as the embodiment of FIG. 7 may be preferred. 
     With reference again to the embodiment of FIGS. 1-4, with the unidirectional 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 members  104  of unidirectional clutch  70  disengage from shaft  32  thereby permitting collar member  68  (and with it the rest of reel assembly  10 ) to freewheel without substantial resistance from viscous clutch assembly  50  (by substantial resistance, what is meant herein is that only nominal rotating friction associated with the freewheeling parts of viscous clutch assembly  50  as opposed to the substantial viscous damping caused by shearing of the fluid within viscous clutch assembly is exerted). When operated in this direction, reel assembly  10  rotates about support shaft  32  resisted primarily 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 unidirectional 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, although in the illustrative embodiment of FIGS. 1-4 the vanes that provide the viscous dampening comprise rotors and stators that shear a viscous fluid, other velocity-proportional viscous dampening assemblies may be advantageously used in accordance with the present invention, such as turbine vanes or, as shown in FIG. 7, a plurality of vanes  190  attached to a hub  192  disposed within chamber  60  containing the viscous fluid. Each of vanes  190  has a pivot  194  that permits the vane  190  to fold radially inward when reel  24  is rotated in a first direction, thereby disengaging the damping apparatus from reel  24 . Each of vanes  190  also has a stop  196  that allows the vane  190  to deploy radially outward and stop when reel  24  is rotated in a second direction, thereby causing the vanes  190  to exert a viscous retarding torque on reel  24  when it is rotated in the second direction. 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.