Patent Abstract:
A system producing force reactions in a transmission includes a case including front and rear surfaces, a reaction component, a gearset including a ring gear and a sun gear that transmits a forward force to the front surface, a first path for transmitting a rearward force from the ring gear to the rear surface, a second path for transmitting a forward force from the ring gear to the reaction component, and a third path for transmitting a rearward force from the sun gear to the reaction component.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates generally to an apparatus for producing thrust force reactions in an automatic transmission, particularly such forces due to transmitting torque between meshing helical gear teeth. 
         [0003]    2. Description of the Prior Art 
         [0004]    In an automatic transmission a planet pinion carrier supports a set of planet pinions, each member of the set being engaged with a sun gear and a ring gear. Typically, an axial force component, i.e., thrust load, produced due to the helix angle of the meshing gears and pinions and torque transmitted between them, is captured between the sun gear and the ring gear. Thrust load from the sun gear is directed at the ring gear hub, and the thrust load from the ring gear hub is directed at the sun gear. This allows the thrust loads to be cancelled, i.e., reacted by a force of equal magnitude and opposite direction. 
         [0005]    Between the ring gear hub and the sun gear hub, a thrust needle bearing is typically used to react the thrust loads and handle the relative speed between the two components. Under coast load conditions, the planetary ring gear and sun gear may thrust apart from each other. Therefore, thrust from the ring and sun must be captured in both directions. 
         [0006]    In some transmission applications, the speed differential between the ring gear and the sun gear is very high. That high speed differential across a thrust bearing causes significant frictional loss and adversely affects fuel economy. 
       SUMMARY OF THE INVENTION 
       [0007]    A system producing force reactions in a transmission includes a case including front and rear surfaces, a reaction component, a gearset including a ring gear and a sun gear that transmits a forward force to the front surface, a first path for transmitting a rearward force from the ring gear to the rear surface, a second path for transmitting a forward force from the ring gear to the reaction component, and a third path for transmitting a rearward force from the sun gear to the reaction component. 
         [0008]    The system provides an alternate way to transmit ring gear-to-sun gear thrust loads in cases where the speed differential between the ring gear and sun gear is high. 
         [0009]    No thrust bearing between the sun gear and the ring gear is required or used. 
         [0010]    The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood, that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0011]    The invention will be more readily understood by reference to the following description, taken with the accompanying drawings, in which: 
           [0012]      FIG. 1  is a schematic diagram showing a side view of the kinematic assembly for an automatic transmission for a motor vehicle; 
           [0013]      FIG. 2  is a cross section of an intermediate portion of the kinematic assembly of  FIG. 1 ; 
           [0014]      FIG. 3  is a front view of the thrust washer shown in  FIG. 4 ; and 
           [0015]      FIG. 4  is a cross section of a front intermediate portion of the kinematic assembly of  FIG. 1 ; 
           [0016]      FIG. 5  is a cross section of a rear portion of the kinematic assembly of  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    The assembly  10   FIG. 1  includes an input  12 ; output  14 ; intermediate shaft  16 ; a first planetary gear set  20  having a first sun gear  22 , a first ring gear  24 , a first carrier  26 ; and a set of planet pinions  30  supported on carrier  26  and in continuous meshing engagement with the sun gear  22  and the ring gear  24 . 
         [0018]    A second planetary gear set  32  includes a second sun gear  34  fixedly coupled to sun gear  22 ; a second ring gear  36 ; a second carrier  38  fixedly coupled to the input  12 ; and a set of planet pinions  40  in supported on carrier  38  and in continuous meshing engagement with sun gear  34  and ring gear  36 . 
         [0019]    A third planetary gear set  42  includes a third sun gear  44  fixedly coupled to ring gear  36 ; a third ring gear  46 ; a third carrier  48 ; and a set of planet pinions  50  supported on carrier  48  and in continuous meshing engagement with sun gear  44  and ring gear  46 . 
         [0020]    A fourth planetary gear set  52  includes a fourth sun gear  54  fixedly coupled to ring gear  46 ; a fourth ring gear  56  fixedly coupled by a shell  58  to carrier  26 ; a fourth carrier  60  fixedly coupled to output  14 ; and a set of planet gears  62  supported on carrier  60  and in continuous meshing engagement with sun gear  54  and ring gear  56 . 
         [0021]    A first brake  64  selectively holds ring gear  24  against rotation. 
         [0022]    A second brake  66  selectively holds sun gears  22 ,  34  against rotation on the transmission case  124 . 
         [0023]    A first clutch  68  selectively couples ring gear  36  to a clutch housing  70  rotation also on the transmission case  124 . 
         [0024]    A second clutch  72  selectively couples carrier  48  to clutch housing  70 . 
         [0025]    A third clutch  74  selectively couples ring gear  46  to input  12 . 
         [0026]    A fourth clutch  76  selectively couples shell  58  to clutch housing  70 . 
         [0027]      FIG. 2  shows that carrier  26  is secured to shell  58 . 
         [0028]    Clutch housing  70  includes an axial arm  82  formed with internal spine teeth, to which external teeth on the spacer plates  84  of clutch  68  are fixed for rotation with clutch housing  70 . The friction plates of clutch  68  are splined to external spline teeth formed on a ring  85 , which is formed with ring gear  36 . 
         [0029]    Intermediate shaft  16 , which extends along axis  86  on the radial outer side of input  12 , is secured to ring  84  where a snap ring  88  completes the connection. Clutch housing  70  is supported by axially spaced bushings  90 ,  92  on the radial outer surface of intermediate shaft  16 . 
         [0030]    Clutch housing  70  includes another axial arm  94  formed with external spine teeth, to which internal teeth on the spacer plates  96  of clutch  76  are fixed for rotation with clutch housing  70 . The friction plates of clutch  76  are splined to internal spline teeth formed on a shell  58 . 
         [0031]    External teeth  98  on the spacer plates of clutch  72  engage internal spline teeth formed on arm  94  of the clutch housing  70 . The friction plates of clutch  72  are splined to external spline teeth formed on carrier  48 . 
         [0032]    Located between bushings  90 ,  92  and formed in the hub  100  of clutch housing  70  are four feed circuits. A single balance oil feed supplies automatic transmission fluid (ATF) to the pressure balance volumes  102 ,  104 ,  106  of clutches  68 ,  72 ,  76 . Balance dams  103 ,  105 ,  107  seal the pressure balance volumes  102 ,  104 ,  106  at the pistons  110 ,  112 ,  114  of the clutches  68 ,  72 ,  76 . 
         [0033]    Each of the servo cylinders  69 ,  73 ,  77  of clutches  68 ,  72 ,  76  is supplied with actuating pressure through individual circuits formed in the clutch housing  70 . When no actuating pressure is applied to clutches  68 ,  72 ,  76 , the clutch housing  70  has no fixed connection to any other component of assembly  10 . 
         [0034]      FIG. 4  shows a pump support  120  secured by bolts  122  to the transmission case  124  and supporting the input shaft  12  on a bushing  126 . A hub  128  for brakes  64 ,  66  includes a radial arm  130 , secured to the pump support, and an axial arm formed with external and internal axial splines, to which the spacer plates of the two brakes  64 ,  66  are secured, respectively. 
         [0035]    The friction discs  132  of brake  66  are connected to external, axial spline teeth formed on a disc  134 , which is secured to the sun gears  22 ,  34  through intermediate shaft  18 . The friction discs  136  of brake  64  are connected to internal, axial spline teeth formed on a disc  138 , which is secured to ring gear  24  and is supported between two thrust bearings  140 ,  141  located on the carrier  26 . 
         [0036]    The planet pinions  30  of gearset  20  are supported for rotation on a pinion shaft  142 , which is supported on carrier  26 . 
         [0037]    Pump support  120  is formed with a first cylinder  144  containing a piston  146 , which extends though openings  148  into contact with one of the spacer plates of brake  64 . Brake-apply pressure is carried through passages  150 ,  151  to cylinder  144 . The openings  148  in hub arm  130  allow an assembler of the brake hub assembly to see though the arm  130  while aligning friction plates  136  with disc  138 . 
         [0038]    Support  120  is also formed with a second cylinder  154  containing a piston  156 , which contacts one of the spacer plates of brake  66 . Brake-apply pressure is carried through passage  158  to cylinder  154 . 
         [0039]    The radial arm  130  of the brake hub  128  is secured to the transmission case  124  such that the arm contacts an axial stop  152 , which limits axial displacement of the arm and provides an axial reaction force to the force of piston  146  applied to the plates of brake  64  and the force of piston  156  applied to the plates of brake  66 . 
         [0040]    Shell  58  is fixed to the carrier  26  of gearset  20  at a snap ring  160 . 
         [0041]    The thrust washer  162  of  FIG. 3  is formed with tabs  164 , which engage the forward disc  166  of carrier  26 . A retaining ring  168  secures the thrust washer  162  to carrier disc  166 . 
         [0042]    The lower arrow represents the direction of the thrust force applied to the teeth of sun gear  22  of gearset  20  during positive drive conditions, i.e., when the engine is driving the driven wheels located at the rear of the vehicle. 
         [0043]    The upper arrow represents the direction of the thrust force applied to the teeth of ring gear  24  of gearset  20  during positive torque conditions. 
         [0044]    The forward directed thrust force of sun gear  22  is transmitted directly through a thrust bearing, located between sun gear  22  and the front surface at the pump support  120 , through the pump support  120 , to bolts  122  and into the transmission case  124 , with which bolts  122  are engaged. 
         [0045]    The rearward directed thrust force of ring gear  24  is transmitted by disc  138  to thrust bearing  141 , which applies that thrust force to disc  166  of carrier  26 . Carrier  26  transmits the force to shell  58 . 
         [0046]    The rearward thrust force of ring gear  24  is transmitted axially rearward by shell  58  to ground at a rear surface of the transmission case  124  near the rear of the transmission. No thrust bearing between sun gear  22  and ring gear  24  is required or used. 
         [0047]    As shown in  FIG. 5 , shell  58  is secured to a disc  174 , which extends radially toward axis  86  between thrust bearings  176 ,  177 . The discs  180 ,  182  of carrier  60  are secured mutually. A bearing  184  is secured to the transmission case  124  by a retaining ring  186 . A ring  188  fitted over the outer diameter of output shaft  14 , contacts the carrier  60  and the inner and outer races of bearing  184  where the rearward thrust force of ring gear  24  is reacted at the rear surface of the transmission case  124 . 
         [0048]    Under positive torque conditions, the thrust force of ring gear  24  is transmitted axially rearward by shell  58  to ground on the transmission case  124  near the rear of the transmission. The rearward thrust force of ring gear  24  is transmitted through a path that includes disc  174 , thrust bearing  176 , disc  180  of carrier  60 , disc  182  of carrier  60 , ring  188 , and bearing  184  to an axial thrust force reaction on transmission case  124 . 
         [0049]    Under negative torque conditions, i.e., when the wheels are transmitting torque to the engine, the direction of the ring gear thrust force and sun gear thrust force is reversed relative to the direction of the arrows shown in  FIG. 2 . 
         [0050]    Under negative torque conditions, the forward thrust force of ring gear  24  is transmitted through a path that includes disc  138 , thrust bearing  140 , thrust washer  162 , retaining ring  168 , carrier  26 , shell  58 , ring gear  56 , disc  174  and thrust bearing  177  to disc  190 . 
         [0051]    Under negative torque conditions, the rearward thrust force of sun gear  22  is transmitted through a path that includes sun gear  34 , thrust bearing  192 , carrier  38 , input shaft  12 , thrust bearing  202  to disc  190 . 
         [0052]    Disc  190  is an intermediate reaction component, to which the rearward thrust force of sun gear  22  and the forward thrust force of ring gear  24  are applied under negative torque conditions and within which these oppositely directed forces are mutually reacted. 
         [0053]    In accordance with the provisions of the patent statutes, the preferred embodiment has been described. However, it should be noted that the alternate embodiments can be practiced otherwise than as specifically illustrated and described.

Technology Classification (CPC): 5