Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/613,948 filed Feb. 4, 2015, issued on Oct. 17, 2017 as U.S. Pat. No. 9,791,031, which is a continuation of U.S. patent application Ser. No. 14/049,513 filed Oct. 9, 2013, issued on Feb. 10, 2015 as U.S. Pat. No. 8,951,159, which claims the benefit of U.S. Patent Application Nos. 61/712,239 filed on Oct. 10, 2012, 61/843,592 filed on Jul. 8, 2013, 61/843,623 filed on Jul. 8, 2013, and 61/870,832 filed on Aug. 28, 2013. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates generally to differential gear assemblies and more particularly to a differential gear assembly having a cross shaft retaining configuration. 
       BACKGROUND 
       [0003]    A differential gear mechanism can be provided in an axle assembly and used to transfer torque from a driveshaft to a pair of output shafts. The driveshaft can drive the differential through the use of a bevel gear that meshes with a ring gear mounted to a housing of the differential. In automotive applications, a differential allows the tires mounted at either end of the axle assembly to rotate at different speeds. This is important when the vehicle is turning because the outer tire travels over an arc of greater distance than the inner tire. Thus, the outer tire must rotate at a faster speed than the inner tire to compensate for the greater distance of travel. The differential includes a differential case and a gear arrangement that allows torque to be transferred from the driveshaft to the output shafts while concurrently allowing the output shafts to rotate at different speeds as needed. The gear arrangement can generally include a pair of side gears that are mounted for rotation with the respective output shafts. A series of cross pins or pinion gear shafts are fixedly mounted to the differential case for rotation therewith. A corresponding plurality of pinion gears are mounted for rotation with the pinion gear shafts and are in meshing relationship with both of the side gears. 
         [0004]    The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
       SUMMARY 
       [0005]    A differential gear mechanism constructed in accordance to one example of the present disclosure can include a differential casing defining first and second output shaft openings that are coaxially aligned along an axis of rotation of the differential casing. First and second side gears are rotatably mounted within the differential casing. The first and second side gears can be co-axially aligned along the axis of rotation of the differential casing. The first side gear can define a first shaft opening configured to provide a first torque transmitting connection with a first output shaft received within the first output shaft opening. The second side gear can define a second shaft opening configured to provide a second torque transmitting connection with a second output shaft received within the second output shaft opening. A plurality of pinion gears can be mounted between the first and second side gears. Each of the plurality of pinion gears can be rotatably mounted on a respective pinion gear shaft. Each pinion gear shaft can have first and second ends. The first ends can be positioned for engagement with the differential casing. The plurality of pinion gears can be intermeshed with the first and second side gears to form a torque transfer arrangement configured for transferring torque between the pinion gears and the first and second side gears to rotate the first and second side gears about the axis of rotation. The torque transfer arrangement can be configured for allowing the first and second side gears to rotate at different rotational speeds with respect to one another about the axis of rotation. A retainer can be disposed within the differential casing that couples the second ends of the pinion gear shafts relative to each other. 
         [0006]    According to additional features, the pinion gear shafts can comprise a plurality of single and independently formed pinion gear shafts for each pinion gear. In one example three pairs of pinion gear shafts are provided. Each pair of pinion gear shafts can include first and second pinion gear shafts that are coaxial relative to each other. In one example, the pinion gear shafts can include a groove formed along an outer circumferential surface. 
         [0007]    According to other features, each second end of the pinion gear shafts has a distal tip including a distal end having a first outer diameter and a neck having a second outer diameter. The second outer diameter is less than the first outer diameter. The retainer can further include a center block defining a plurality of openings. Each pinion gear shaft can have a snap ring arranged around the neck. Each snap ring can be configured to compress during installation through the openings and subsequently expand upon clearing the openings thereby locking the pinion shafts into the center block. The distal tips can be bulbous. Each pinion gear shaft can extend along a pinion gear axis and further comprise an intermediate portion that connects the first and second ends. The intermediate portion can have a third outer diameter that is greater than the first outer diameter. 
         [0008]    In other configurations, the retainer can comprise a first retainer portion and a second retainer portion. The first and second retainer portions can oppose each other and cooperatively engage the respective distal tips of the pinion gear shafts. The retainer can inhibit movement of the respective pinion gear shafts along respective pinion gear axes while permitting rotational movement about the respective pinion gear axes. The retainer can further comprise a connecting member that couples the first and second retainer portions together. The connecting member can include a screw that threadably engages at least one of the first and second retainer portions. In another example, the connecting member comprises a rivet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0010]      FIG. 1  is schematic of an exemplary vehicle driveline incorporating a differential gear mechanism constructed in accordance to one example of the present disclosure; 
           [0011]      FIG. 2  is perspective view of a differential gear assembly of  FIG. 1 ; 
           [0012]      FIG. 3  is an exploded perspective view of the differential gear assembly of  FIG. 2 ; 
           [0013]      FIG. 4  is a cross-sectional view of the differential gear assembly taken along lines  4 - 4  of  FIG. 2 ; 
           [0014]      FIG. 5  is a cross-sectional view of the differential gear assembly taken along lines  5 - 5  of  FIG. 2 ; 
           [0015]      FIG. 6  is a perspective view of a retainer constructed in accordance to one example of the present disclosure and shown retaining a plurality of pinion gear shafts; 
           [0016]      FIG. 7  is an exploded perspective view of the retainer and pinion gear shafts of  FIG. 6 ; 
           [0017]      FIG. 8  is a perspective view of a retainer constructed in accordance to another example of the present disclosure and shown retaining a plurality of pinion gear shafts; 
           [0018]      FIG. 9  is a cross-sectional view of the differential gear mechanism of  FIG. 8 ; 
           [0019]      FIG. 10  is a perspective view of a retainer constructed in accordance to another example of the present disclosure and shown retaining a plurality of pinion gear shafts; 
           [0020]      FIG. 11  is a cross-sectional view of the differential gear mechanism of  FIG. 10 ; 
           [0021]      FIG. 12  is a perspective view of another retainer constructed in accordance to an additional example of the present disclosure and shown retaining a plurality of pinion gear shafts; 
           [0022]      FIG. 13  is an exploded perspective view of the retainer and pinion gear shafts of  FIG. 12 ; 
           [0023]      FIG. 14  is a plan view of the retainer and pinion gear shafts shown in  FIG. 12 ; and 
           [0024]      FIG. 15  is a sectional view of the retainer and pinion gear shafts shown in  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    With initial reference to  FIG. 1 , an exemplary vehicle driveline is shown and generally identified with reference numeral  10 . The exemplary vehicle driveline  10  described herein is for a front wheel drive vehicle having a transversely mounted engine  12 , although other configurations can be utilized with the present disclosure. The engine  12  provides a rotary output to a transmission  14 . 
         [0026]    The driveline  10  can further include a transaxle  22  and a limited slip differential assembly  30  having a planetary gear assembly  16 , a clutch assembly  32  and a differential gear assembly  34 . The limited slip differential assembly  30  is received in a housing  36  and operates to drive a pair of axle shafts  40  and  42  that are connected to front drive wheels  44  and  48 , respectively. In general, the limited slip differential assembly  30  functions as a traditional open differential during normal operating conditions until an event occurs where a bias torque is required. When a loss in traction is detected or anticipated, the clutch assembly  32  can be selectively actuated in order to generate the optimum bias ratio for the situation. 
         [0027]    The transmission  14  can receive the rotary output from the engine  12  and provide a rotary input to the limited slip differential assembly  30 . Further, the transmission  14  can be operable to provide various gear ratios between the rotary output of the engine  12  and the rotary input of the limited slip differential assembly  30 . 
         [0028]    The planetary gear assembly  16  includes a ring gear  46 , a sun gear  20  and a plurality of planet gears  50  carried by a planet carrier  52 . The ring gear  46  is non-rotatably fixed to the housing  36 , and the sun gear  20  is meshingly engaged with the plurality of planet gears  50  carried by the planet carrier  52 . The planet gears  50  are meshed with the ring gear  46 . The planet carrier  52  is coupled for rotation with a differential case  54  of the differential gear assembly  34 . The planetary gear assembly  16  provides a gear ratio reduction from the sun gear  20  to the planetary carrier  52  and, therefore, to the differential case  54 . The sun gear  20  is rotatably coupled to the transmission  14  via a coupling device, such as a chain or belt, such that an output of the transmission  14  drivingly rotates the sun gear  20 , which translates rotational output from the transmission  14  into rotational input of the sun gear  20 . 
         [0029]    The differential gear assembly  34  includes a pair of side gears  60  and  62  that are mounted for rotation with the axle shafts  40  and  42  (and first and second drive wheels  44  and  48 ), respectively. The side gears  60  and  62  define first and second axle shaft openings  64  and  65  ( FIG. 3 ). A plurality of cross pins or pinion gear shafts  66  are fixedly mounted to the differential case  54  for rotation therewith. A corresponding plurality of pinion gears  70  are mounted for rotation with the pinion gear shafts  66  and are in meshing relationship with both of the side gears  60  and  62 . In an open configuration, described more fully below, the differential gear assembly  34  acts to allow the axle shafts  40  and  42  to rotate at different speeds. 
         [0030]    The clutch assembly  32  couples the planetary gear assembly  16  with the differential gear assembly  34 . The clutch assembly  32  includes a clutch pack and a clutch actuator. The clutch pack includes a plurality of annular plates  74  interleaved between a plurality of annular friction disks  78 . The plurality of annular plates  74  can be coupled for rotation with one of the differential case  54  and the differential gear assembly  34 . The plurality of annular friction disks  78  can be coupled for rotation with the other one of the differential case  54  and the differential gear assembly  34 . In the illustrated embodiment, the plurality of annular plates  74  are coupled for rotation to the differential case  54  (e.g., splined to an inner diameter  76  of the differential case  54 ) and the plurality of annular friction disks  78  are coupled for rotation with the differential gear assembly  34  (e.g., splined to an outer diameter  80  of the side gear  60 ). It will be appreciated that the annular friction disks  78  may be supported for rotation by either of the side gears  60  or  62 , or both. 
         [0031]    The plurality of annular plates  74  and annular friction disks  78  are interleaved between one another and act to rotate past one another in substantially non-contacting relationship when the clutch assembly  32  is in its open position. However, it will be appreciated by those skilled in the art that the term “non-contacting” as used herein is relative and is not meant to necessarily indicate that the annular plates  74  and annular friction disks  78  have absolutely no contact when the clutch assembly  32  is in the open condition. The annular plates  74  and annular friction disks  78  are axially movable into frictional engagement relative to one another, thereby reducing relative rotation between the annular plates  74  and annular friction disks  78  when the clutch assembly  32  is in the closed or partially closed configurations. In this manner, when the clutch assembly  32  is in its closed position, the side gears  60  and  62 , as well as the axle shafts  40  and  42  and the drive wheels  44  and  48  rotate together. 
         [0032]    The clutch assembly  32  can operate in an open configuration to allow the side gears  60  and  62  to rotate independently from each other, e.g., at different speeds. The clutch assembly  32  can also operate in a closed or partially closed configuration where the side gears  60  and  62  rotate together or partially together (that is, not independently), e.g., at substantially the same speed. The clutch assembly  32  can, for example, be a hydraulic clutch assembly  32  that utilizes pressurized hydraulic fluid to selectively actuate the clutch pack between the open, closed and partially closed configurations. 
         [0033]    With additional reference now to  FIGS. 2-7 , additional features of the differential gear assembly  34  will be described. The differential case  54  can include a first differential casing portion  90  and a second differential casing portion  92 . A ring gear  94  can be disposed around the first differential casing portion  90 . The first differential casing portion  90  can include a first axle hub  96 . A plurality of bores  98  are defined in the first differential casing portion  90 . The second differential case portion  92  can include a second axle hub  102 . A plurality of rings  106  can be provided between the respective pinion gears  70  and the first differential casing portion  90 . Washers  110  can be disposed outboard of the side gears  60  and  62 . 
         [0034]    A retainer  120  can be disposed in the differential case  54 . The retainer  120  can retain the respective pinion shafts  66  relative to each other and within the differential case  54 . The retainer  120  can include a center block  122 . The center block  122  can include a ring-shaped member  126  that defines a plurality of openings  130  ( FIG. 7 ). 
         [0035]    Each pinion shaft  66  can extend along a pinion gear axis  131  ( FIG. 7 ). Each pinion shaft  66  can generally include a first end  132 , a second end  134  and an intermediate portion  136  that connects the first and second ends  132  and  134 . Each pinion shaft  66  can define a spiral groove  140  formed along an outer circumferential surface. The spiral groove  140  can facilitate oil flowing along the length of the pinion shafts  66 . Each second end  134  has a distal tip or end  150  having a first outer diameter  152  ( FIG. 5 ) and a neck  154  having a second outer diameter  156 . The second outer diameter  156  is less that the first outer diameter  152 . The intermediate portion  136  has a third outer diameter  158 . The first outer diameter  152  is less than the third outer diameter  158 . 
         [0036]    A snap ring or bang ring  160  is arranged around each neck  154 . In one example, the pinion shafts  66  can be installed through the bores  98  and into the first differential casing  54 . During installation, each snap ring  160  can compress during installation through the openings  130  of the center block  122  and subsequently expand ( FIGS. 5 and 6 ) thereby locking the pinion shafts  66  axially. Explained further, the snap rings  160  can expand to a greater outer diameter than the openings  130  while still being journaled around the neck  154  thereby inhibiting axial movement of the pinion shafts  66 . The center block  122  can be hardened and provide the necessary lead in geometry (radial ramp etc.) at the openings  130  to influence each snap ring  160  to compress as they are inserted. In one configuration, the pinion shafts  66  are free to rotate around their axes  131  subsequent to assembly into the retainer  120 . The second ends  134  of the pinion shafts  66  can align with the bores  98  ( FIG. 5 ). 
         [0037]    With reference now to  FIGS. 8 and 9  a differential gear assembly  234  constructed in accordance to additional features will be described. The differential gear assembly  234  has a differential case  236 . The differential gear assembly  234  further includes a pair of side gears  260  and  262  having first and second shaft openings  264  and  265 , respectively. A plurality of cross pins or pinion gear shafts  266  are fixedly mounted to the differential case  236  for rotation therewith. A corresponding plurality of pinion gears  270  are mounted for rotation with the pinion gear shafts  266  and are in meshing relationship with both of the side gears  260  and  262 . The differential gear assembly  234  operates similar to the differential gear assembly  34  discussed above. 
         [0038]    A plurality of bores  298  are defined in the differential case  236  and are configured to receive the pinion gear shafts  266 . A plurality of rings  306  can be provided between the respective pinion gears  270  and the differential case  236 . Washers  310  can be disposed outboard of the side gears  260  and  262 . 
         [0039]    A retainer  320  can be disposed in the differential case  236 . The retainer  320  can retain the respective pinion shafts  266  relative to each other and within the differential case  236 . The retainer  320  can include a first retainer portion  330  and a second retainer portion  332 . The first retainer portion  330  can define a plurality of bores  333  configured to receive the pinion shafts  266 . A connecting member  334  can include a fastener that can selectively couple the first and second retainer portions  330  and  332  together. In one example, the connecting member  334  can threadably engage complementary threads on the first retainer portion  330 . The second retainer portion  332  can have one or a series of retaining lips  338  that can be configured to overhang and capture the distal ends  250  of the respective pinion shafts  266 . 
         [0040]    Turning now to  FIGS. 10 and 11 , a differential gear assembly  434  constructed in accordance to additional features will be described. The differential gear assembly  434  has a differential case  236 . The differential gear assembly  434  further includes a pair of side gears  260  and  262  having first and second shaft openings  264  and  265 , respectively. A plurality of cross pins or pinion gear shafts  366  are fixedly mounted to the differential case  236  for rotation therewith. The pinion gear shafts  366  can include distal ends  368 . The distal ends  368  can be bulbous in one example. A corresponding plurality of pinion gears  270  are mounted for rotation with the pinion gear shafts  366  and are in meshing relationship with both of the side gears  260  and  262 . A plurality of bores  298  are defined in the differential case  236 . A plurality of rings  306  can be provided between the respective pinion gears  270  and the differential case  236 . Washers  310  can be disposed outboard of the side gears  260  and  262 . The differential gear assembly  334  operates similar to the differential gear assembly  34  discussed above. 
         [0041]    A retainer  420  can be disposed in the differential case  236 . The retainer  420  can retain the respective pinion shafts  366  relative to each other and within the differential case  236 . The retainer  420  can include a first retainer portion  430  and a second retainer portion  432 . A connecting member  434  can include a rivet that can selectively couple the first and second retainer portions  430  and  432  together. In one configuration, the rivet can include a buck rivet. The first and second retainer portions  430  and  432  can be positioned intermediate first and second disks  440  and  442 . The first retainer portion  430  can have one or a series of retaining lips  436  that can be configured to overhang and capture the distal ends  368  of the respective pinion shafts  366 . The second retainer portion  432  can have one or a series of retaining lips  438  that can be configured to overhang and capture the distal ends  368  of the respective pinion shafts  366 . 
         [0042]    With reference now to  FIGS. 12-15 , a retainer  520  constructed in accordance to additional features will be described. The retainer  520  can retain respective pinion shafts  566  relative to each other and within the differential case. The retainer  520  can include a center block  522  and a snap insert  530 . The center block  522  can include a central opening  524  and a plurality of radial openings  526 . The pinion shafts  566  can include a distal tip  570  that can be in the form of a ball, teardrop or other geometry. While not specifically shown, the pinion shafts  566  can include grooves formed along outer surfaces as described above with respect to the pinion shafts  66 . The snap insert  530  can be received within the central opening  524  of the center block  522 . The snap insert  530  can define a plurality of pockets  580 . The distal tips  570  of the pinion shafts  566  are configured to expand the respective pockets  580  during insertion. The pockets  580  subsequently collapse around the distal tips  570  and retain the pinion shafts  566  in the retainer  520 . The distal tips  570  can form a snap fit with the respective pockets  580  of the snap insert  530 . 
         [0043]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. For example, while the various retainers described herein for retaining pinion shafts have been described in relation with a front wheel drive limited slip differential, they are not so limited. In this regard, the retainers described herein can be used in any differential mechanism. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Technology Category: 2