Abstract:
A stroking constant velocity universal joint assembly is provided including a drive member having a plurality of circumferentially spaced rotatable drive elements, and a drive housing disposed about the drive elements. The drive housing has an inner wall formed with a plurality of circumferentially spaced drive channels. The drive channels have running surfaces extending axially of the housing to an open end thereof and which guide the rotatable drive elements for stroking movement within the drive housing. A retainer assembly is provided including a ramped surface extending along each drive channel for gradually narrowing a span of the drive channel, to maintain a respective drive element within the housing. In another aspect of the invention, a retainer assembly is provided for retaining a drive member within a drive housing of a stroking universal joint. The retainer assembly includes a base portion and a plurality of ears projecting from the base portion. Each ear has a first surface and a second surface opposite the first surface, the second surface being inclined with respect to the first surface. The second surface is adapted for engaging a portion of the drive member to retain the drive member within the drive housing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of provisional application Ser. No. 60/689,707 filed on Jun. 10, 2005. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to a retainer assemblies for use with a stroking universal joints and, more particularly, to a system for retaining a spider assembly within a housing in a tripot-type universal joint.  
       BACKGROUND OF THE INVENTION  
       [0003]     Stroking universal joints are well-known in the art. One such type of stroking joint is a tripot-type joint, which generally includes a housing defining a plurality of elongated drive channels and a spider assembly retained within the housing. The spider assembly includes rollers disposed in the drive channels for allowing relative longitudinal movement along the drive channels between the spiders and the housing. A splined shaft is typically connected to an interior hub in the spider assembly. Similarly, a splined shaft is connected to the housing. Relative rotational movement is transmitted between the splined shafts through the spider and housing assembly. The movable spider assembly allows for relative longitudinal movement between the two splined shafts. This axial movement or stroke is required for changes in distance during normal suspension movement.  
         [0004]     One issue with tripot joints is the possibility that they may become over-extended during the assembly process or during motion of the vehicle in which they are installed. This over-extension occurs when the spider assembly is forced to stroke beyond the end of the housing, thereby exiting the drive channels and resulting in loss of function of the joint. It is desirable to prevent the spider assembly from exiting the housing during stroking of the joint.  
       SUMMARY OF THE INVENTION  
       [0005]     A stroking constant velocity universal joint assembly is provided including a drive member having a plurality of circumferentially spaced rotatable drive elements, and a drive housing disposed about the drive elements. The drive housing has an inner wall formed with a plurality of circumferentially spaced drive channels. The drive channels have running surfaces extending axially of the housing to an open end thereof and which guide the rotatable drive elements for stroking movement within the drive housing. A retainer assembly is provided including a ramped surface extending along each drive channel for gradually narrowing a span of the drive channel, to maintain a respective drive element within the housing.  
         [0006]     In another aspect of the invention, a retainer assembly is provided for use in a stroking universal joint of the type having a drive spider assembly with a plurality of circumferentially spaced trunnions and a drive housing member having an interior wall surrounding the spider assembly. A plurality of elongated drive channels is formed in the interior wall of the housing member, and each of the spider assembly trunnions has a drive roller rotatably mounted thereon and respectively disposed for linear travel in an associated one of the drive channels. The retainer assembly includes a plurality of ears, each of the ears being adapted for extending along a running surface of a corresponding drive channel. Each of the ears includes an end portion positioned spaced apart from the housing open end and a ramped surface extending away from the running surface along a first direction proceeding from the ear end portion toward the housing open end so as to engage a drive element moving in the first direction, to urge the drive element away from the running surface.  
         [0007]     In yet another aspect of the invention, a retainer assembly is provided for retaining a drive member within a drive housing of a stroking universal joint. The retainer assembly includes a base portion and a plurality of ears projecting from the base portion. Each ear has a first surface and a second surface opposite the first surface, the second surface being inclined with respect to the first surface. The second surface is adapted for engaging a portion of the drive member to retain the drive member within the drive housing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     In the drawings illustrating embodiments of the present invention:  
         [0009]      FIG. 1  is an exploded view of a tripot-type universal joint assembly showing an embodiment of a retainer system in accordance with the present invention;  
         [0010]      FIG. 2  is a partial cross-sectional end view showing a spider assembly inserted into a housing, with a retainer system in accordance with the present invention secured to the housing;  
         [0011]      FIG. 3  is a partial perspective view showing the spider assembly inserted into the housing, with a retainer system in accordance with the present invention secured to the housing;  
         [0012]      FIG. 4  is a perspective view of one embodiment of a retainer system in accordance with the present invention;  
         [0013]      FIGS. 5A-5C  include a plan view and various side views of the retainer system shown in  FIG. 4 ;  
         [0014]      FIG. 5D  is an enlarged cross-sectional view of a retaining ear as shown in  FIG. 5C ;  
         [0015]      FIG. 6  is a schematic view showing attachment of the retainer system to a housing of a tripot joint system;  
         [0016]      FIG. 7  is a partial cross-sectional view showing a portion of a retaining ear of the retainer system in accordance with the present invention extending into a drive channel; and  
         [0017]      FIG. 8  is a schematic view showing engagement between the retainer system and a drive roller during movement of a spider assembly within the tripot joint housing. 
     
    
     DETAILED DESCRIPTION  
       [0018]      FIGS. 1-3  show the basic elements of a tripot-type universal joint assembly, generally designated  10 . The tripot joint  10  includes a generally cylindrical housing  12  closed at an inboard end  12   a  thereof by an end wall  14 . The joint  10  includes a drive shaft  16  integral with the end wall  14  that extends axially therefrom. The drive shaft  16  is preferably splined.  
         [0019]     The housing  12  is open at an outboard end  12   b  and has an endface  13  and three substantially equally circumferentially spaced and longitudinally extending drive channels  18  formed in an interior wall of the housing  12 . The drive channels  18  are substantially concentric about a longitudinal axis A of the housing  12  and the drive shaft  16 . Each of the longitudinally extending channels  18  is bounded by a pair of opposing concave side walls  20  and a concave endwall  21  extending between sidewalls  20  which forms part of the tracks or guides that engage the curved surfaces of associated drive rollers  22  of a spider assembly, generally designated  24 . Side walls  20  form running surfaces for spider assembly drive rollers  22 .  
         [0020]     The spider assembly  24  includes a hub  28  and three trunnions  26  extending radially from the hub  28 . The hub  28  includes a central bore  30  that is splined for receiving a splined shaft (not shown) in any known manner. Preferably, the splined shaft is fixed within the central bore  30  and is used for transmitting rotational movement between the shaft and the hub  28 .  
         [0021]     Each of the drive rollers  22  is mounted on a trunnion  26  extending from the hub  28 . Preferably, the rollers  22  are mounted on the trunnions  26  with a complement of needle bearings  32  interposed between the inner diameter of the roller  22  and the outer cylindrical surface of the associated trunnion  26 . Annular retainers  36  are secured to the outer end of each trunnion  26  to retain the needle bearings  32  in location and to limit the radial outward movement of the associated roller  22  on the trunnion  26 . The drive rollers  22  are thus rotatable on the trunnions  26  to allow axial movement of the spider  24  in the housing  12 , thereby permitting universal stroking and pivotal movement of the joint. With the above described assembly, each drive roller  22  is captured in the radial direction in its associated drive channel and is maintained substantially equidistant from the longitudinal axis A during joint operation.  
         [0022]     While the above-described embodiment uses drive rollers  22  and needle bearings  32  to facilitate motion of the spider assembly along the housing interior, it will be appreciated that other types of roller systems capable of facilitating rolling motion along the drive channels may be used in accordance with the present invention.  
         [0023]     To maintain spider assembly  24  within the housing  12 , a novel retaining system is used. In the embodiment shown in  FIGS. 4 and 5 A- 5 C, the retaining system comprises an annular structure  100  having a base portion and a plurality of flaps or ears  110  projecting from the base portion. The base portion also has a plurality of circumferentially spaced-apart first arcuate segments  102   a - 102   c  and a plurality of circumferentially spaced-apart second arcuate segments  104   a - 104   c . Each one of first segments  102   a - 102   c  is connected at an end thereof to a respective one of second segments  104   a - 104   c . In the embodiment shown in  FIGS. 4 and 5 A- 5 C, second segments  104   a - 104   c  are generally coplanar with each other and with first segments  102   a - 102   c . However, depending on design requirements, any of second segments  104   a - 104   c  may lie on a plane different from any of the other second segments  104   a - 104   c , and any of first segments  102   a - 102   c  may lie on a plane different from any of the other first segments  102   a - 102   c . In addition, any of the first segments  102   a - 102   c  may lie on a plane different from any of second segments  104   a - 104   c . First segments  102   a - 102   c  and second segments  104   a - 104   c  are substantially concentric about a longitudinal axis B (as shown in  FIG. 4 ). When annular structure  100  is secured to housing  12 , axis B is substantially coaxial with axis A of housing  12 .  
         [0024]     Referring again to  FIGS. 4 and 5 A- 5 D, retainer assembly  100  includes a flap or ear  110  formed at each end of each of first segments  102   a - 102   c . In general, each ear  110  is formed integral with the remainder of annular structure  100  as shown in  FIG. 5D , so as to extend inward into a corresponding drive channel  18  along respective drive channel sidewalls or running surfaces  20  (see  FIG. 1 ) when annular structure  100  is positioned and retained against housing endface  13 , as described below. Referring in particular to  FIG. 5D , each ear  110  has a first relatively straight surface  111  extending generally parallel with axis B ( FIG. 4 ) and a second surface  114  opposite first surface  111  and inclined with respect to the first surface. Surface  114  is coined or otherwise suitably deformed to provide an angle or ramp extending away from first surface  111  and away from an associated running surface  20  the drive channel  18  proceeding along the direction indicated by arrow F (see  FIG. 4 ) from a free end  109  of ear  110  toward the open end  12   b  of housing  12  (see  FIG. 1 ). Ramped surface  114  is configured to engage a drive element moving in the direction of arrow F, to urge the associated drive element  22  away from running surface  18 . As defined herein, an ear  110  is considered to extend “along” an associated running surface  20  if the ear is either in contact with the running surface, or extends adjacent the running surface and is spaced a sufficiently small distance apart from the running surface such that a drive roller moving along an associated drive channel  18  toward housing open end  12   b  will engage ramped surface  114  and be urged away from the running surface as it proceeds toward housing open end  12   b . A third surface  112  intersects second surface  114  and extends substantially parallel to first surface  111 . In a particular embodiment, shown in  FIGS. 2 and 3 , ramped surfaces  114  are positioned in opposition to each other across the width or span of an associated drive channel  18 .  
         [0025]     In alternative embodiments (not shown), ears  110  may be formed at each end of each second segment  104 , or instead of an ear formed at each end of first segments  102   a - 102   c , one or more of first segments  102  or second segments  104  may have a single ear formed at a single end thereof.  
         [0026]     In all, the annular structure  100  shown in  FIGS. 4 and 5 A has a trilobal shape with three first segments  102   a - 102   c  and three second segments  104   a - 104   c . In the embodiment shown in  FIGS. 4 and 5 A, first segments  102   a - 102   c  have respective inner radii of curvature  103   a - 103   c  and second segments  104   a - 104   c  have respective inner radii of curvature  105   a - 105   c . In addition, the inner radii of curvature  103   a - 103   c  of respective first segments  102   a - 102   c  are substantially equal to each other, the inner radii of curvature  105   a - 105   c  of respective second segments  104   a - 104   c  are substantially equal to each other, and the inner radii of curvature  103   a - 103   c  of respective first segments  102   a - 102   c  are smaller than the inner radii of curvature  105   a - 105   c  of respective second segments  104   a - 104   c.    
         [0027]     In additional alternative embodiments (not shown), depending on design considerations, inner radii of curvature  103   a - 103   c  of respective first segments  102   a - 102   c  may be different from each other, and inner radii of curvature  105   a - 105   c  of respective second segments  104   a - 104   c  may be different from each other. In addition, an inner radius of curvature of one or more of second segments  104   a - 104   c  may be the same as or larger than an inner radius of curvature of one or more of first segments  102   a - 102   c . However, any chosen combination of first segment inner radii, second segment inner radii, the positions of first segments  102  and second segments  104  with respect to central axis B, and the locations of ears  110  should not interfere with motion of a splined shaft (not shown) attached to hub central bore  30 .  
         [0028]     Annular structure  100  may be formed from a metallic material using conventional stamping and bending techniques well-known to those skilled in the art. Alternatively, the annular structure may be formed partly from a polymer material and partly from a metallic material insert molded or otherwise attached to the polymer portion of the retaining system.  
         [0029]     Referring to  FIG. 6 , when coupled to housing  12 , annular structure  100  is held against housing endface  13  in a conventional manner using, for example, a boot  150  or bushing  160  secured to housing  12  using a clamp  170 . Alternatively, ears  110  may be formed so as to generate an interference fit between annular structure  100  and housing  12 , to aid in retention of annular structure  100  to endface  13 .  
         [0030]      FIG. 7  shows extension of one of ears  110  into an associated drive channel of housing  12 , and  FIG. 8  shows engagement between ears  110  and a drive roller  22  during stroking motion of a drive roller within a single drive channel  18 . However, it will be understood that the retaining system shown in  FIG. 8  operates in a similar manner in all drive channels  18  of the tripot joint assembly. Referring to  FIG. 8 , as drive roller  22  moves in the direction indicated by arrow D (toward an open end  12   b  of housing  12 ), the drive roller engages ramps  114 - 1 ,  114 - 2  formed along ears  110 - 1 ,  110 - 2  and rides along the ramps toward the respective ear surfaces  112 - 1 ,  112 - 2 , thereby exerting forces on the ramps in the directions indicated by arrows X and Y (substantially perpendicular to the ramped surfaces  114 - 1 ,  114 - 2 .) These forces press ears  110 - 1 ,  110 - 2  firmly against sidewalls  20  of drive channel  18 , thereby wedging the ears between the drive roller  22  and drive channel walls  20 . In this respect, retaining ring  100  is self-securing during use, because attempted withdrawal of drive roller  22  from housing  12  (which annular structure  100  is designed to prevent) provides forces for securing the annular structure to housing  12  during the attempted withdrawal of the drive roller. This minimizes the force required for securing annular structure  100  to housing endface  13  by the bushing or boot and the accompanying housing clamp.  
         [0031]     Also, as seen From  FIG. 8 , ramped surfaces  114 - 1 ,  114 - 2  effectively gradually narrow the effective width or span of the drive channel during movement of an associated drive roller  22  in direction D within the channel, because the drive roller will not fit through the gap between the respective surfaces  112 - 1  and  112 - 2  of opposing ears  110 - 1  and  110 - 2 . Thus, the drive roller becomes wedged between ramped surfaces  114 - 1  and  114 - 2  and withdrawal of drive rollers  22  and inner drive spider  14  from housing  12  is prevented.  
         [0032]     In an alternative embodiment (not shown), in an embodiment where a single ear  110  is formed at one respective end of each of first segments  102   a - 102   c , engagement between a ramped surface  114  and an associated drive roller  22  produces abutting engagement between the drive roller and an interior surface of the drive channel, thereby wedging the drive roller between the ramped surface and the interior surface of the drive channel and preventing withdrawal of the drive roller from housing  12 . In this embodiment, engagement with the ramped surface may force the drive roller into engagement with a surface of the drive channel located directly opposite the ramped surface and/or with one or more other interior surfaces of the drive channel not positioned directly opposite the ramped surface.  
         [0033]     It may be seen that, as drive rollers  22  move toward housing open end  12   b , ramped surfaces  114  engage the drive rollers such that impact of the rollers into the otherwise relatively blunt ends of ears  110  is either eliminated or substantially reduced. This provides smoother operation of the tripot joint, and reduces the likelihood of spalling occurring along the outer faces of drive rollers  22  due to impact with end portions of the retaining ears. In addition, the retaining system described above does not require the formation of special retaining grooves on the housing, thereby making the retainer assembly easier to couple to the housing than existing retainer designs, and also reducing the manufacturing cost of the housing.  
         [0034]     It will be understood that the foregoing description of the present invention is for illustrative purposes only, and that the various structural and operational features herein disclosed are susceptible to a number of modifications, none of which departs from the spirit and scope of the present invention. The preceding description, therefore, is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined only by the appended claims and their equivalents.