Abstract:
An output bearing assembly of a transmission includes a housing, and a pair of bearings. At least one speedometer sensor is mounted between the bearings. The arrangement allows the output bearings to be spaced axially by a relatively great distance.

Description:
BACKGROUND OF THE INVENTION 
     This invention generally relates to an output bearing assembly in a vehicle transmission and, more particularly, to an output bearing assembly having an intermediate speedometer sensor. 
     A transmission of a vehicle typically includes a main section and an auxiliary section which each contain gears to provide several speed ratios on an output shaft. An output bearing assembly mounts the output shaft beyond the auxiliary section. Typically, the output bearing assembly includes a pair of tapered output bearings supporting the output shaft relative to the housing of the auxiliary section. Part of the function of the output bearing assembly is to support and limit radial displacement of the output shaft. Space constraints typically require that the two output bearings be placed relatively close to each other. Because the bearings are in close proximity, conventional output bearings may allow undesirable radial displacements of the output shaft. 
     In addition, the typical transmission of a vehicle includes a speedometer rotor and a speedometer sensor both located beyond the output bearing assembly. The speedometer sensor measures the rotational speed of the speedometer rotor which is mounted on the output shaft. The sensed rotational speed is used as an indication of vehicle speed. 
     It would be desirable to provide an output bearing assembly which is better able to reduce radial displacement of the output shaft. 
     SUMMARY OF THE INVENTION 
     This invention provides an output bearing assembly for a vehicle transmission in which a pair of output bearings are spaced apart and at least one speedometer sensor is mounted between the two output bearings. Generally, by placing the sensor between the bearings, the bearings may be separated by a greater distance without any necessary increase in the total length of the transmission. 
     Preferably, an output bearing cup spacer integral with a housing of the auxiliary section spaces the bearings. In a second embodiment the output bearing cup spacer is a separate part from the housing. Both the output bearing cup spacer and the housing of the auxiliary section are spaced radially about an output shaft. 
     The bearings are preferably tapered roller bearings. The output bearing cup spacer is positioned between outer races of the output bearings and a speedometer rotor is mounted around the output shaft between inner races of the output bearings. Most preferably, the spacer extends radially inwardly beyond an outermost surface of the outer races of the bearings. 
     At least one speedometer sensor is mounted with a first end extending through the bearing cup spacer and spaced adjacent to the speedometer rotor. 
     The speedometer sensor typically includes a set of external threads to be received in an internally threaded hole provided in the auxiliary section housing. A washer and a nut are threaded onto the speedometer sensor. The speedometer sensor is then threaded into the housing to a predetermined depth and then the nut and washer are tightened against the housing to lock the speeedometer sensor in place. The speedometer sensor is capable of detecting the rotational speed of the speedometer rotor and to thereby enable the speed of the vehicle to be calculated. 
     The invention provides an output bearing cup spacer for separating the output bearings of the output bearing assembly in the transmission of a vehicle. This increases the distance between the output bearings such that radial displacement of the output shaft is reduced. The total length of the transmission is not increased since the space for mounting the sensor is now between the bearings. 
     These and other features and advantages of this invention will become more apparent to those skilled in the art from the following detailed description of the presently preferred embodiment. The drawings that accompany the detailed description can be described as follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a schematic diagram illustrating the components of the prior art vehicle transmission. 
     FIG. 1B is a cross-sectional view of a first embodiment of the invention shown mounted on a half-view of an output shaft of a transmission. 
     FIG. 2 is a cross-sectional illustration taken along lines  2 — 2  from FIG.  1 B. 
     FIG. 3 is a cross-sectional view of a second embodiment of the invention shown mounted on a half-view of an output shaft of a transmission. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1A schematically illustrates a known vehicle transmission  10  including a main section  12 , an auxiliary section  14 , an output bearing assembly  16 , and a yoke  18 . A speedometer sensor  20  is able to detect the rotational speed of a speedometer rotor  22  mounted around an output shaft  24  which extends through the components and is fixed to the yoke  18 . The speedometer sensor  20  and the speedometer rotor  22  are spaced axially beyond output bearing assembly  16  and auxiliary section  14 . 
     FIG. 1B is a cross-sectional view of a first embodiment of the invention mounted on a half-view of the output shaft  24  of the transmission  10 . An output bearing assembly  25  includes a first bearing  26  and a second bearing  28 . Both the bearings  26  and  28  include an inner race  30 , an outer race  32 , and a set of roller bearings  34  disposed between the inner race  30  and the outer race  32 . Roller bearings  34  are preferably tapered roller bearings. A housing  38  having a shoulder  40  is integral with a wall  42  of the auxiliary section  14 . The inner race  30  and the outer race  32  are press fitted into place on the output shaft  24  and against the housing  38  respectively. A bearing and seal retainer  46  is attached to housing  36  with a set of bolts  48 . The retainer  46  supports a seal  44  for preventing oil leakage around the rotating yoke  18 . The shoulder  40  in the housing  38  and a first side  50  of an output bearing cup spacer  52  position the outer race  32  of the first bearing  26 . A second side  54  of the output bearing cup spacer  52  and the retainer  46  position the outer race  32  of the second bearing  28 . Note, spacer  52  extends radially inwardly beyond a radially outermost extent of the outer faces  32 . 
     In a preferred embodiment the output bearing cup spacer  52  is made of powdered metal. 
     The output shaft  24  has a shoulder  56  and the inner race  30  of the first bearing  26  is positioned between the shoulder  56  of the output shaft  24  and the speedometer rotor  22 . The inner race  30  of the second bearing  28  is positioned between the speedometer rotor  22  and the yoke  18 . A plurality of fins  58  project from the speedometer rotor  22 . In the preferred embodiment there are sixteen fins  58  and the speedometer rotor  22  is made of powdered metal. 
     The speedometer sensor  20  has external threads  60  adapted to be received in threads  62  in the housing  38 . A hole  64  in the output bearing cup spacer  52  permits a first end  66  of the speedometer sensor  20  to extend through the housing  38  and the output bearing cup spacer  52  and to be at a predetermined depth in close proximity to the speedometer rotor  22 . The top of the threads  62  in the housing  38  includes a straight thread O-ring port  67  as is well known in the art. A nut  68  is threaded onto the speedometer sensor  20  and holds a washer  70  against the output bearing cup spacer  52 . An O-ring  71  is enclosed in the space defined by the washer  70 , the straight thread O-ring port  67 , and the speedometer sensor  20 . The O-ring  71  seals the speedometer sensor  20  in the housing  38 . In the preferred embodiment there are three speedometer sensors  20  mounted in the housing  38 . The first end  66  of each speedometer sensor  20  is spaced radially outwardly of the speedometer rotor  22  and the output shaft  24 . The sensors  20  may operate as is known in the art. It is the positioning of the sensors  20  which is inventive here. 
     FIG. 2 is a cross-sectional illustration taken along line  2 — 2  in FIG. 1B; The housing  38  and the output bearing cup spacer  52  are disposed radially around the output shaft  24 . The output bearing cup spacer  52  has a tab  72  which is received in a groove  73  in housing  38  to position spacer  52 . The speedometer rotor  22  is mounted around the output shaft  24 . In the most preferred embodiment there are three speedometer sensors  20  mounted in the housing  38 . 
     FIG. 3 is a cross-sectional view of a preferred embodiment of the invention shown mounted on a half-view of the output shaft of the transmission. In this embodiment the output bearing cup spacer  52  is integral with the housing  38 . Because the output bearing cup spacer  52  is integral with the housing  38 , the shoulder  40  on the housing  38  is no longer necessary to position the outer race  32  of the first bearing  26 . Instead, the design of the roller bearing  34  forces the outer race  32  of the first bearing  26  against the first side  50  of the output bearing cup spacer  52 . The inner race  30  of the first bearing  26  is still positioned between the shoulder  56  of the output shaft  24  and the speedometer rotor  22 . In all other respects, this embodiment is the same as that shown in FIG.  1 B. 
     An output bearing assembly designed according to this invention offers the advantages of allowing the output bearings to be further spaced apart thereby reducing radial displacement of the output shaft of the vehicle. The assembly further provides for integration of the speedometer sensor and speedometer rotor into the assembly thus reducing the number of components in the transmission. 
     The foregoing description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and do come within the scope of this invention. Accordingly, the scope of legal protection afforded this invention can only be determined by studying the following claims.