Abstract:
An improved hybrid transmission including two electric motor/generator modules and a plurality of planetary gear sets operatively connectable to the motor/generators and to an engine is provided. Novel structural and packaging schemes enhance the function and efficiency of the transmission. More precisely, the present invention relates to an improved apparatus for applying an adjustable load to internal rotating components of the hybrid transmission to maximize efficiency thereof.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application claims the benefit of U.S. Provisional Application 60/612,559, filed Sep. 23, 2004, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This invention relates to a ball bearing retention apparatus for a hybrid electro-mechanical vehicular transmission that utilizes interactive planetary gear arrangements that are operatively connected to an engine and two motor/generators. 
     BACKGROUND OF THE INVENTION 
     A hybrid electro-mechanical vehicular transmission utilizes interactive planetary gear arrangements that are operatively connected to an engine and two motor/generators. A power transmission in an electro-mechanical transmission is described in commonly owned United States Provisional Application entitled Electrically Variable Transmission with Selective Fixed Ratio Operation, attorney docket No. GP-305519, Holmes et al., filed Jul. 22, 2004, and hereby incorporated by reference in its entirety. 
     SUMMARY OF THE INVENTION 
     An improved hybrid transmission including two electric motor/generator modules and a plurality of planetary gear sets operatively connectable to the motor/generators and to an engine is provided. Novel structural and packaging schemes enhance the function and efficiency of the transmission. More precisely, the present invention relates to an improved apparatus for applying an adjustable load to internal rotating components of the hybrid transmission to maximize efficiency thereof. 
     The improved hybrid transmission includes a plurality of fasteners adapted to mount a clutch hub to a center support. Inner and outer runners disposed between the center support and the clutch hub preferably retain first and second ball bearings. An adjustable load applied to the ball bearings may be increased by tightening the fasteners such that the ball bearings remain on a consistent track, noise is minimized, and rotational efficiency is maximized. 
     In one aspect of the present invention, the inner runner includes a first portion engaged by the clutch hub and a second portion engaged by the center support. 
     In another aspect of the present invention, the first portion of said inner bearing runner includes a ramped shoulder adapted to engage the first ball bearing, and the second portion of the inner bearing runner includes a ramped shoulder adapted to engage the second ball bearing such that the ramped shoulders translate the adjustable load applied by the fasteners into a first component tending to draw the first and second ball bearings together and a second component tending to push the first and second ball bearings into engagement with the outer bearing runner. 
     In yet another aspect of the present invention, the fasteners include at least one hollow fastener adapted to provide hydraulic fluid to operate a clutch. 
     The above features 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 
         FIG. 1  is a schematic cross-sectional illustration in fragmentary view of a hybrid electrical/mechanical transmission; 
         FIG. 2  is an enlarged schematic cross-sectional illustration in fragmentary view of a portion of the hybrid electrical/mechanical transmission of  FIG. 1 ; and 
         FIG. 3  is a further enlarged schematic cross-sectional illustration in fragmentary view of a portion of the hybrid electrical/mechanical transmission of  FIG. 2 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is adapted for use in conjunction with commonly owned U.S. Provisional Application 60/613,557, Burgman et al., filed Sep. 17, 2004, and hereby incorporated by reference in its entirety. It should, however, be appreciated that the present invention may also be used in other transmission configurations. 
     Referring to the drawings wherein like reference numbers refer to like components,  FIG. 1  shows a vehicle  10  having an electro-mechanical transmission  11 . An input shaft  12  is disposed about a center axis  14  and is operable for transferring power from an engine (not shown) to the transmission  11 . A main shaft  16  is longitudinally disposed and rotatable about the center axis  14  and is engageable with the input shaft  12 . The engagement of one or more of a plurality of clutches such as clutch  15  interconnects one or more of a plurality of planetary gear sets such as planetary gear set  17  to transfer power at varying ratios to an output member  18 . Two electric motor/generators  20 A and  20 B are coaxially oriented about the center axis  14 . Each motor/generator  20 A,  20 B is operatively connectable to a member of one of the planetary gear sets to provide a range of continuously variable speed ratios between the input shaft  12  and the output member  18 , as will be readily understood by those skilled in the art. Each of the motor/generators  20 A,  20 B includes a generally ring-shaped stator  22 A,  22 B, respectively, and a generally ring-shaped rotor  24 A,  24 B rotatable with respect to the respective stator  22 A,  22 B. An end cover  26  is mounted with respect to the main shaft  16  to partially encase the motor/generators  20 A,  20 B within and partially define an interior space  28 . The end cover  26  cooperates with a first portion  30  of a housing member (i.e., an upper portion of a transmission case) and a second portion  32  of the housing member (i.e., a lower portion of the transmission case) to further encase the motors/generators  20 A,  20 B within the interior space  28 . 
     Referring now to  FIG. 2 , a center support  36  is rigidly supported with respect to the main shaft  16  about the center axis  14  and preferably supports the stator  22 A. The clutch  15  is disposed within a housing or clutch hub  38  adapted to rotate about the center axis  14 . The clutch hub  38  is mounted to the center support  36  by a plurality of fasteners  40 . Rotation about the center axis  14  is facilitated by a ball bearing  42  retained by inner and outer bearing runners  44  and  46 , respectively. The ball bearing  42  will hereinafter be described according to a preferred dual ball bearing embodiment, however, alternate configurations may be envisioned. 
     In a preferred embodiment there are five fasteners  40  evenly distributed in a circular pattern. For purposes of this disclosure, the present invention will be described in conjunction with the apparatus of the incorporated patent application 60/613,557, however, it should be appreciated that the present invention does not require the incorporated disclosure. Accordingly, four of the fasteners  40  are preferably solid fasteners  40   a  and one of the fasteners  40  is a hollow fastener  40   b  adapted to provide hydraulic fluid for the actuation of clutch  15 . The four solid fasteners  40   a  each preferably include a threaded end portion  41  to maintain engagement between the clutch hub  38  and the center support  36 , whereas the hollow fastener  40   b  is preferably press fit into position between the clutch hub  38  and the center support  36 . While the number and configuration of fasteners  40  have been described in the context of a preferred embodiment, it should be appreciated that alternate quantities and configurations of the fasteners  40  may be envisioned, and that the fasteners  40  may include different combinations of fasteners  40   a  and/or  40   b . Additionally, in an alternate embodiment the fasteners  40  may include solid fasteners  40   a  exclusively. 
     As best seen in  FIG. 3 , according to the preferred dual ball bearing embodiment, ball bearing  42  includes a first ball bearing  42   a  and a second ball bearing  42   b . The inner bearing runner  44  is split at the midpoint thereof about the center axis  14  (shown in  FIGS. 1-2 ) to provide a first portion  44   a  and a second portion  44   b . The first portion  44   a  of the inner bearing runner  44  is adapted to retain the first ball bearing  42   a , and the second portion  44   b  of the inner bearing runner  44  is adapted to retain the second ball bearing  42   b . The first and second portions  44   a ,  44   b  of the inner bearing runner  44  each include a ramped shoulder  48   a ,  48   b , respectively. 
     The fasteners  40   a  (shown in  FIG. 2 ) apply an axial load to the inner ball bearing runner  44  which is translated to the ball bearing  42 . More precisely, as the fasteners  40   a  are tightened, the clutch hub  38  and center support  36  are drawn together such that the clutch hub  38  engages the first portion  44   a  of the inner bearing runner  44  and the center support  36  engages the second portion  44   b  of the inner bearing runner  44 . Therefore, as the clutch hub  38  and center support  36  are drawn together, the first and second portions  44   a ,  44   b  of the inner bearing runner  44  are correspondingly drawn together. As the first and second portions  44   a ,  44   b  of the inner bearing runner  44  are drawn together, the shoulder  48   a  of the first portion  44   a  engages the ball bearing  42   a  and the shoulder  48   b  of the second portion  44   b  engages the ball bearing  42   b . As the first and second ball bearings  42   a ,  42   b  are engaged, the geometry of the ramped shoulders  48   a ,  48   b  imparts both an axial load tending to draw the first and second ball bearings  42   a ,  42   b  together, and a radial load tending to push the first and second ball bearings  42   a ,  42   b  toward the outer bearing runner  46 . 
     Accordingly, a variable load is imparted by the fasteners  40   a  to the first and second ball bearings  42   a ,  42   b  through the first and second portions  44   a ,  44   b  of the inner bearing runner  44 . The variable load may be increased by tightening the fasteners  40   a  such that the first and second ball bearings  42   a ,  42   b  are compressed between the inner and outer bearing runners  44 ,  46 . In this manner, the variable load applied to the first and second ball bearings  42   a ,  42   b  may be optimized such that the ball bearings remains on a consistent track, noise is minimized, and rotational efficiency is maximized. 
     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.