Abstract:
A differential for racing cars that travel in a given direction around a closed circular or oval track, including an overrunning clutch arrangement for disengaging from the drive train of the differential an outside wheel shaft that overruns the inside wheel shaft during a turn by a given amount, and a locking device for continuously locking the inside wheel shaft to the differential drive train. Preferably, the locking device comprises a locking gear that is non-rotatably splined to the inside wheel shaft and that has pinion teeth that are in continuous engagement with the central drive member of the differential.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     A locking differential mechanism for racing cars that travel in a given direction around a circular or oval track is disclosed, including locking means for continuously locking the inside wheel shaft to the differential drive train, and normally-engaged overrunning clutch means that are operable during a turn to disengage the outside wheel shaft to a free-running condition when the velocity thereof exceeds that of the inside wheel shaft by a predetermined amount. 
     2. Brief Description of the Prior Art 
     As shown by the prior U.S. patents to Knoblock U.S. Pat. Nos. 2,638,794 and 3,397,593, Bokovoy U.S. Pat. No. 3,791,238 and Dissett et al U.S. Pat. No. 4,557,158, it is well known in the patented prior art to provide locking differential mechanisms for vehicles that are operable during a turn in either direction to disengage the overunning outside wheel shaft to a free-wheeling condition when the rotational velocity thereof exceeds the rotational velocity of the inside wheel shaft by a predetermined amount. Center cam means serve to axially displace the overrunning clutch gear away from the central drive member against the force of restoring clutch spring means as long as the overrunning condition exists. When the turn is completed and the velocity of the outside wheel shaft decreases to that of the inside wheel shaft, the clutch gear member is returned by the clutch spring means to its original driven condition in engagement with the central drive member. It is also known to provide holdout ring means for maintaining the outside wheel in the disengaged condition as long as the overrunning condition exists. This type of differential mechanism has utility in all types of on-road and off-road motor driven vehicles. 
     In the racing car industry, in many types of races, it is common for the racing cars to travel in only one given direction (generally, counterclockwise) along a closed circular or oval track, and consequently the same wheel is always the outside wheel. The present invention was developed to provide an improved locking differential for use with race cars that travel only in a given direction around a closed circular or oval track, which differential affords a rugged durable construction having a low maintenance cost. 
     SUMMARY OF THE INVENTION 
     Accordingly, a primary object of the present invention is to provide a differential mechanism for race cars that travel in one direction around a closed circular or oval track, including overrunning clutch means that effect disengagement from the drive train of the outer wheel shaft when the rotational velocity thereof exceeds that of the inside wheel shaft by a predetermined amount, and locking means for continuously connecting the inner wheel shaft with the drive train of the differential. 
     According to a more specific object of the invention, the inside wheel shaft locking means includes an annular locking gear that is non-rotatably splined to the end of the inside wheel shaft, said locking gear including pinion teeth that are in continuous driven engagement with corresponding pinion teeth on one end face of the central driver member that is splined with the differential housing. Pinion teeth on the other end of the center driver member are normally engaged by corresponding pinion teeth on an overrunning clutch member that is connected with the outside wheel shaft. Center cam means are provided for disengaging the clutch member from the center driver member upon the occurrence of an overrunning condition of the outside wheel shaft during a turn. Holdout ring means may be provided for maintaining the clutch member in the disengaged condition as long as the overrunning condition exists. 
     According to a more specific object of the invention, the pinion teeth on the center drive member, the overrunning clutch member, and the locking gear have a relatively shallow depth, and the remote ends of the side gear of the overrunning clutch means and the locking member are enlarged and extend within counterbores formed in the opposed output shaft openings contained in the end walls of the differential housing. In an embodiment of the invention including holdout ring means, the depth of the pinion teeth each of on the center driver member, the overrunning clutch member, and the locking gear is relatively great. Thrust washer means are provided at the remote ends of the side gear and the locking gear. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in the light of the accompanying drawings, in which: 
     FIG. 1 is a longitudinal sectional view of a first embodiment of the racing car differential of the present invention taken along line  1 — 1  of FIG. 2, and FIG. 2 is a left hand end view of the differential housing assembly of FIG. 1; 
     FIG. 3 is longitudinal sectional view of the locking gear component of FIG. 1, and FIGS. 4 and 5 are left hand and right hand end views, respectively, of the locking gear component of FIG. 3; 
     FIG. 6 is a longitudinal sectional view of a second embodiment of the racing car differential of the present invention; 
     FIG. 7 is a longitudinal sectional view of the locking gear of FIG. 6, taken along line  7 — 7  of FIG. 8, and FIG. 8 is a right hand end view of the locking gear of FIG. 7; 
     FIG. 9 is a detailed end view of a tooth of the locking gear, taken in the direction shown by the arrow A in FIG. 8; 
     FIG. 10 is a longitudinal sectional view of a third embodiment of the racing car differential of the present invention; 
     FIG. 11 is a longitudinal sectional view of the locking gear of FIG. 10 taken along line  11 — 11  of FIG. 12; and 
     FIG. 12 is a right hand end view of the locking gear of FIG.  11 . 
    
    
     DETAILED DESCRIPTION 
     Referring fist more particularly to the embodiment of FIGS. 1-5, the racing car differential mechanism of the present invention includes a sectional housing  2  that is supported for rotation about its longitudinal axis L within the differential casing  4  by bearing means  6 , as is known in the art. The housing is rotatably driven by the vehicle drive shaft  8  via pinion gear  10  and ring gear  12  that is bolted to the outer flange portion of the housing  2 . 
     The housing  2  contains a chamber  14  having opposed end walls containing output shaft openings  16  and  18  for receiving the wheel shafts or axles of the racing car. In the illustrated embodiment of FIG. 1, it is assumed that the direction of travel of the racing car around a closed circular or oval track causes wheel shaft  20  to be the inside wheel shaft on a turn, and the wheel shaft  22  to be the outside wheel shaft. The outside wheel shaft  22  has a splined end extending within the chamber  14  that is non-rotatably connected with the internally splined annular side gear  24  that is supported within housing section  2   b  for rotation about the longitudinal axis L. Mounted for axial sliding displacement concentrically about the side gear  24  by spline means  26  is an annular-internally splined overrunning clutch member  28 . The clutch member  28  is normally biased to the left by the helical compression clutch spring  30 , thereby to cause driven pinion clutch teeth on the left hand face of the clutch member to engage corresponding drive pinion teeth on the right hand end of the annular central driver gear  32 . The central driver gear  32  is arranged concentrically about the housing rotational axis L and is non-rotatably connected with the housing section  2   b  by spline means  34 . Arranged concentrically within the central driver gear  32  and rotatably connected by resilient clip  36  is an annular cam member  38  the right hand end of which is provided with cam teeth that engage corresponding cam teeth on the left hand end of the clutch member  28 , as is known in the art. 
     In accordance with a characterizing feature of the present invention, the central driver gear  32  is provided on its left hand end face with driver pinion teeth that are in continuous engagement with corresponding driver teeth on an annular locking gear  40 , that is mounted for rotation within the housing  2  concentrically about the longitudinal axis L thereof. The locking gear  40  is internally splined for non-rotational connection with the splined end of the inside wheel shaft  20  that extends within the chamber  14  via the first output shaft opening  16 . 
     Referring to FIGS. 3-5, the left hand end of the locking gear  40  is stepped to define an annular first journal portion  40   a  that is journaled within a corresponding counterbore  16   a  formed in the first output shaft opening  16  contained in housing section  2   a . At its right hand end, the locking gear  40  is provided with pinion teeth  42  that continuously engage corresponding pinion teeth on the center driver member  38 . In the illustrated embodiment, the pinion teeth extend radially inwardly for engagement with corresponding cam teeth on the left hand end of the center cam member, thereby to lock the cam member  38  against rotation relative to the central driver gear  32 . As shown in FIG. 5, the locking gear  40  is provided with a relatively large number (i.e., twenty) of pinion teeth each having a relatively shallow tooth depth, thereby to effect quicker engagement and disengagement of the pinion teeth, as is customary for racing car differentials. The locking gear includes internal splines  44  that non-rotatably connect the locking gear with the inside wheel shaft  20 . 
     As is customary in the art, the right hand end of the side gear  24  is provided with an external annular flange portion  24   a  that supports the annular spring retainer  46 . This flange portion  24   a  is spaced from the end extremity of the side gear to define a stepped annular extension that is journaled within a corresponding counterbore formed in the second output shaft opening  18 . 
     In operation, assume that the racing car is traveling in a given direction around a closed circular or oval track, such that the driven shafts  20  and  22  are the inside and outside wheel shafts, respectively. On a straightaway portion of the track, the wheel shafts  20  and  22  are driven at the same speed from the vehicle drive shaft  8  via pinion gear  10 , ring gear  12 , central driver gear  32 , and the locking gear  40  on the one hand, and via pinion gear  10 , ring gear  12 , central drive gear  32 , and clutch member  28  and the side gear  24  on the other hand, respectively. When the racing car enters a turn, the overrunning clutch member  28  is cammed out and displaced to the right against the restoring biasing force of clutch spring  30  by the cooperation between the cam teeth on the center cam member  38  and the corresponding cam teeth on the clutch member  24 . The outside wheel shaft  22  is thus placed in a disconnected free-wheeling condition as long as the rotational velocity of the outside wheel shaft exceeds that of the inside wheel shaft by a predetermined amount. Upon completion of the turn and the corresponding slowing down of the outside wheel shaft relative to the rotational velocity of the inside wheel shaft, the clutch member  28  is biased by spring  30  to the left to return the pinion teeth on the side gear into return engagement with the pinion teeth on the central driver member. Both wheel shafts are again driven at the same speed by the drive shaft  8 . 
     Although the pinion teeth  42  on the locking gear  40  have been disclosed as being in engagement with both the pinion teeth on the center drive gear  32  and the cam teeth on the left hand end of the center cam member  38 , it will be apparent that if the cam member is to be maintained free for rotation relative to the central driver member  32 , the radially inwardly extending length of the pinion teeth  42  is reduced so that the inner ends of the pinion teeth terminate short of the cum teeth of the cam member  32 . 
     Referring now to the second embodiment of the invention illustrated in FIGS. 6-9, the differential includes a holdout ring  100  for maintaining the overrunning clutch member  128  in the disengaged condition as long as the velocity of the outside wheel shaft  122  exceeds that of the inside wheel shaft  120  by a predetermined amount. As is known in the art, the holdout ring is a resilient split generally annular member that is biased radially inwardly into engagement with the annular slot  101  contained in the face of the overrunning clutch member  128 . When an overrunning condition exists, the clutch member is displaced to the right by the cooperation between the cam teeth  150  on the clutch member  128  and the corresponding cam teeth on the center cam member  138 . As the clutch member is angularly displaced relative to the center drive member  132 , the holdout ring is similarly angularly displaced (owing to the frictional engagement between the holdout ring and the clutch member slot  101 ) to a position relative to the cam member as to maintain the clutch member in the disengaged condition, whereby the disturbing noise of teeth chatter is avoided. When the overrunning condition ceases, the holdout ring is slightly angularly displaced to a position that permits re-engagement of the clutch pinion teeth  142  with the corresponding teeth on the center driver gear. 
     In this embodiment, the number of pinion teeth on the clutch member  128  is reduced (i.e., to fifteen in the embodiment shown in FIG.  8 ), and the depth of the tooth is increased, as shown in FIG. 9, thereby providing a sturdy durable clutch member, together with the provision of adequate space for operating the holdout ring  150 . Also provided in this embodiment are annular thrust washer means  152 ,  154  that support the shoulder portions formed at the remote ends of the locking gear  140  and the side gear  124 , respectively. 
     Again, the inwardly directed length of the pinion teeth  142  could be reduced to permit free rotation of the center cam member  138  relative to the central drive member  132 . 
     Referring now to the third embodiment of FIGS. 10-12, the locking gear  240  has an enlarged end portion  240   a  that is journaled in a corresponding counterbore  217  contained in the first outlet shaft opening  216  contained in the housing section  202   a , and the side gear  224  has an enlarged end portion  224   a  that is journaled in the second output shaft opening defined in the housing section  202   b . The enlarged end flange portion  224   a  of the side gear supports the annular spring retainer  246  for the clutch spring  230 . This design accommodates axles fitted with larger bearings. Consequently, larger diameters for the side gear and the locking gear ends are required. The larger bearings and added case material increase torque and axial load capacity of the differential casing. 
     While in accordance with the provisions of the patent statutes the preferred forms and embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made without deviating from the inventive concepts set forth above.