Abstract:
The pinion gear assembly thus includes a first and a second pinion gear arranged with generally parallel axes of rotation. A first and a second washer, referred to herein as stationary washers, are provided. Each of the washers has two openings spaced to generally align with two predetermined, spaced mounting locations on the planet carrier member. The first and the second washers are positioned on opposing sides of the first and second pinion gears, with the axes of rotation of the first and second pinion gears generally centered at the respective spaced openings of the washers. Because the stationary washer spans the two pinion gears, which are secured to the carrier member, the stationary member is operatively connected at two locations to the carrier member, eliminating the need for anti-rotation features and corresponding carrier features.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a pinion gear subassembly for a planet carrier assembly and a method of assembling a planet carrier assembly. 
       BACKGROUND OF THE INVENTION 
       [0002]    Planet carrier assemblies are an integral portion of planetary gear sets used in automatic transmissions on motor vehicles. Planet carrier assemblies include a cage-like carrier member with pinion gears rotatably mounted thereon. In a simple planet carrier assembly, the pinion gears mesh with both a ring gear member and a sun gear member. The carrier member may be rotatable, or may be grounded to a stationary (non-rotatable) member, such as the transmission casing. In either case, the pinion gears rotate relative to the carrier member. Accordingly, washers are used between the components. Typically, each pinion gear has a rotating washer placed adjacent either side. Stationary washers are placed between each of the rotating washers and the carrier member. The stationary washers are referred to as such as they are held stationary with respect to the carrier member by anti-rotation tabs, such as may be formed by secondary stamping operations. The carrier member is forged or machined with mating features to retain the tabs. Precise orientation is required to assemble the stationary washers to the carrier member by aligning the tabs with the mating feature. The anti-rotation tabs and mating features adds manufacturing expense and assembly time. Additionally, the anti-rotation tabs typically cause an increase in the outer diameter of the carrier assembly, requiring additional packaging space in the transmission. 
         [0003]    Thus, a typical pinion gear has four dedicated washers (two rotating and two stationary). The pinion gears with dedicated washers are preassembled in a subassembly, which is then inserted into the carrier member and secured thereto. Each pinion gear subassembly is inserted separately into the carrier member. 
       SUMMARY OF THE INVENTION 
       [0004]    A pinion gear subassembly for a planet carrier assembly with a planet carrier member is provided that enables a reduction of components, and eliminates manufacturing and assembly steps. Specifically, double-holed stationary washers span two adjacent pinion gears, with one stationary washer per side of the gears, and are secured to the carrier member at each of the holes, eliminating the need for two separate stationary washers for each pinion gear. The pinion gear assembly thus includes a first and a second pinion gear arranged with generally parallel axes of rotation. A first and a second washer, referred to herein as stationary washers, are provided. Each of the washers has two openings spaced to generally align with two predetermined, spaced mounting locations on the planet carrier member. The first and the second washers are positioned on opposing sides of the first and second pinion gears, with the axes of rotation of the first and second pinion gears generally centered at the respective spaced openings of the washers. Because the stationary washer spans the two pinion gears, which are secured to the carrier member, the stationary member is operatively connected at two locations to the carrier member, eliminating the need for anti-rotation features and corresponding carrier features. 
         [0005]    The reduced part count pinion gear subassembly allows a method of assembling a planetary carrier assembly that includes inserting a pair of pinion gears through a circumferential opening in a planet carrier member, with the pair of pinion gears being connected via the stationary washers so that the pair of pinion gears with washers are inserted together. The method of assembly may be carried out using tooling components such as a guide member inserted in the carrier member and a stop held at one of the circumferential openings of the carrier member. The pinion gear subassembly is pushed off of the guide member (i.e., contacts and is redirected by the carrier member) towards the stop during the insertion, and then contacts the stop to reach a final position at which it may be secured to the carrier member. 
         [0006]    The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a schematic side view of a pinion gear subassembly; 
           [0008]      FIG. 2  is a schematic exploded perspective view of a planet carrier assembly connected with a park gear and an output member, with the pinion gear subassembly of  FIG. 1  aligned for insertion into a carrier member; 
           [0009]      FIG. 3  is a schematic perspective view of the planet carrier assembly of  FIG. 2 , with the park gear removed for clarity, and with one pinion gear subassembly secured to the carrier member and the pinion gear subassembly of  FIG. 2  partially inserted into the carrier member using a guide member and a stop; 
           [0010]      FIG. 4  is a top view of the carrier assembly of  FIG. 2 , with the pinion gear subassembly partially inserted therein; 
           [0011]      FIG. 5  is a schematic perspective view of the planet carrier assembly with the pinion subassembly stopped against the stop and secured to the carrier member with pins; and 
           [0012]      FIG. 6  is a flow diagram of a method of assembling a planet carrier assembly such as that of  FIG. 5 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    Referring to the drawings, wherein like reference numbers refer to like components throughout the several views,  FIG. 1  shows a pinion gear subassembly  10 A. The pinion gear subassembly  10 A includes two pinion gears  12 A and  12 B connected together by two double-holed stationary washers  14 A,  14 B, with four separate rotating washers  16 A,  16 B,  16 C and  16 D sandwiched between the stationary washers and respective sides  17 A,  17 B,  17 C and  17 D of the pinion gears  12 A,  12 B. Temporary plugs or pins  18 A,  18 B are inserted through aligned openings in the stationary washers  14 A,  14 B, the rotating washers  16 A,  16 B,  16 C and  16 D, and the pinion gears  12 A,  12 B to hold the subassembly  10 A together until it is secured to the carrier member  20 . The pinion gears  12 A,  12 B have axes of rotation A 1 , A 2 , respectively, that are generally parallel with one another when assembled in the pinion gear assembly  10 A. The stationary washers  14 A,  14 B and rotating washers  16 A,  16 B,  16 C and  16 D are referred to as stationary and rotating, respectively, because of their ability or inability to rotate relative to a planet carrier member  20 , also referred to as a planet spider, shown in  FIG. 2 , once inserted into and secured thereto with pins  22 A,  22 B. 
         [0014]    Referring to  FIG. 2 , a planet carrier assembly  11  includes the subassembly  10 A, the pins  22 A,  22 B, a like subassembly  10 B (best shown in  FIGS. 3 and 5 ), and the planet carrier member  20 . In  FIG. 2 , the planet carrier member  20  is shown connected for rotation with an output shaft  24  and a park gear  26 , such as for use on a vehicle transmission. The planet carrier member  20  has circumferentially-spaced openings  28 A,  28 B,  28 C and  28 D (see  FIG. 3 ) sized to permit the pinion gear subassembly  10 A to be inserted therethrough into the center of the carrier member  20 , with gear teeth  30  of each of the pinion gears  12 A,  12 B and of pinion gears  12 C,  12 D on a substantially identical pinion gear subassembly  10 B, extending out of the openings  28 A- 28 D as best shown in  FIGS. 3 and 4 . 
         [0015]    The rotating washers  16 A,  16 B,  16 C and  16 D are flat annular discs, without flanges or other orientation features other than the respective central openings  32 A,  32 B,  32 C and  32 D therethrough. The stationary washers  14 A,  14 B have no orientation features to orient them with respect to the carrier member  20 , other than by aligning the respective openings  34 A,  34 B,  34 C and  34 D of the stationary washers  14 A,  14 B with predetermined locations, i.e., pin openings, of the carrier member  20  (two pin openings  36 A,  36 B shown in  FIG. 2  spaced near the circumferential openings  28 A,  28 B, with like, equally-spaced pin openings (not shown, hidden by pinion gear assembly  10 B), also corresponding with the circumferential openings  28 C,  28 D). 
         [0016]    Referring to  FIG. 3 , a guide member  40  and stop  42  are used to help orient the pinion gear subassembly  10 A to the correct position with respect to the carrier member  20  during insertion of the pinion gear subassembly  10 A into the carrier member  20 . Specifically, the guide member  40  is lowered on a rod (not shown) through a central opening  44  of the park gear  26  (see  FIG. 2 ) to rest against an inner surface of the carrier member  20 , as shown in  FIG. 3 . The stop  42  is moved via a rod (not shown) to a position against the carrier member  20  in which the stop  42  spans the opening  28 B. Positioning of the guide member  40  and the stop  42  may be automated. The subassembly  10 A is inserted with the pinion gear  12 B forward-most or leading through the circumferential opening  28 A. A robotic arm may be used to insert the subassembly  10 A, or it may be inserted manually. The prepositioned guide member  40  has a curved contact surface  46  that will interfere with the forward-most pinion gear  12 B and redirect the pinion gear  12 B toward the opening  28 B as the pinion gear subassembly  10 A is pushed further into the carrier member  20 . The interference will allow the pinion gear  12 B to rotate about the plug  18 B during insertion, promoting ease of assembly. 
         [0017]    Referring to  FIG. 5 , as the pinion gear subassembly  10 A is further inserted into the carrier member  20 , the forward-most pinion gear  12 B eventually encounters the stop  42 , and insertion is terminated, the subassembly  10 A having reached a final position within the carrier member  20 . Specifically, when the pinion gear  12 B contacts the stop  42 , the plugs  18 A,  18 B, shown in  FIG. 2 , and associated openings of the washers  14 A,  14 B,  16 A- 16 D and pinion gears  12 A,  12 B will be aligned with the pin openings  36 A,  36 B (shown in  FIG. 2 ) of the carrier member  20 . 
         [0018]    Once the pinion gear subassembly  10 A has reached the final position described above, the pins  22 A,  22 B are inserted through openings  48 A,  48 B (see  FIG. 2 ) of the park gear  26 , through the aligned openings of the stationary washers  14 A,  14 B and rotating washers  16 A- 16 D as well as the axial openings through the pinion gears  12 A,  12 B. The pins  22 A,  22 B push the plugs  18 A,  18 B out of the subassembly  10 A and secure the subassembly  10 A to the carrier member  20  and the park gear  26 , similar to pins  22 C,  22 D used to secure the subassembly  10 B to the carrier member  20  and park gear  26 , as shown in  FIG. 4 . In  FIGS. 3-5 , the subassembly  10 B has been assembled to the carrier member  20  in a like manner as described with respect to subassembly  10 B, using the guide member  40  and stop  42 , with the guide member  40  positioned so that the curved surface  46  faces the opposite direction than shown in  FIG. 3 , and with the stop  42  positioned at circumferential opening  28 D. 
         [0019]    Referring to  FIG. 6 , a method  100  of assembling a planet carrier assembly is shown in block diagram form, and is described with respect to the planet carrier assembly  11  of  FIGS. 2-5 . The method  100  begins with block  102 , placing a guide member  40  within a carrier member  20 . The method  100  then proceeds to block  104 , holding a stop  42  against a circumferential opening  28 B of the carrier member  20 . 
         [0020]    Optionally, the method may include block  106 , assembling a pinion gear subassembly  10 A (and also pinion gear subassembly  10 B) to be used in the carrier assembly  11 . Alternatively, the subassemblies  10 A,  10 B may be obtained in a preassembled form, so that their assembly is not carried out under the method  100 . Optional block  106  includes blocks  108 ,  110  and  112 . In block  108 , the rotatable washers  16 A- 16 D are stacked on the respective sides  17 A- 17 D of the pinion gears  12 A,  12 B. Next, in block  110 , the double-holed stationary washers  14 A,  14 B are stacked against the rotatable washers as shown in  FIG. 1 . Finally, in block  112 , plugs  18 A,  18 B are inserted through the aligned openings of the washers  14 A- 14 B,  16 A- 16 B and pinion gears  12 A- 12 B to hold the components together as a subassembly  10 A. 
         [0021]    The pinion gear subassembly  10 A is then inserted through circumferential opening  28 A into the carrier member  20  in block  114 . The previously positioned guide member  40  and stop  42  ensure that the pinion gear subassembly  10 A is properly aligned with respect to predetermined locations (i.e., openings  36 A,  36 B) of the carrier member  20  at the completion of the insertion. In block  116 , pins  22 A,  22 B are then pushed through the aligned openings of the pinion gear subassembly  10 A and carrier member  20  (and in the embodiment shown, also through openings in park gear  26 ) to secure the subassembly  10 A to the carrier member  20 . Finally, in block  118 , the guide member  40  and stop  42  may then be withdrawn from the carrier member  20 . The method  100  is also performed in order to secure the pinion gear subassembly  10 B to the carrier member  20 . 
         [0022]    While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.