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 retaining a clutch hub and providing hydraulic fluid to actuate a clutch.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This Application claims the benefit of U.S. Provisional Application 60/613,557, filed Sep. 27, 2004, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates to a dual function apparatus for a hybrid electro-mechanical vehicular transmission.  
       BACKGROUND OF THE INVENTION  
       [0003]     A hybrid electro-mechanical vehicular transmission utilizes interactive planetary gear arrangements that are operatively connected to an engine and two motor/generators. Selective utilization of torque transfer devices such as a clutch enable power transfer via the planetary gear arrangements from the engine and/or motor/generators to the output member of the transmission.  
         [0004]     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  
       [0005]     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 retaining a clutch hub and providing hydraulic fluid to actuate a clutch.  
         [0006]     The apparatus of the present invention includes a fluid source in fluid communication with a pump adapted to draw fluid therefrom. A housing member defines a first flow passage in fluid communication with the pump. A center support is disposed within the housing member and defines a second flow passage in fluid communication with the first flow passage. A clutch hub is attached to the center support and a clutch is disposed within the clutch hub. A plurality of fasteners attach the center support to the clutch hub. At least one of the fasteners is a hollow fastener defining a third flow passage in fluid communication with both the second flow passage and the clutch such that the clutch may be actuated by fluid from the fluid source.  
         [0007]     In one aspect of the present invention, the apparatus of the present invention includes a valve body disposed between the pump and the first flow passage to selectively allow fluid from the fluid source to be transferred to the clutch.  
         [0008]     In another aspect of the present invention, the plurality of fasteners include a plurality of threaded fasteners adapted to attach the center support and the clutch hub.  
         [0009]     In yet another aspect of the present invention, the plurality of fasteners include five fasteners evenly distributed in a circular pattern.  
         [0010]     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  
       [0011]      FIG. 1  is a schematic cross-sectional illustration in fragmentary view of a hybrid electrical/mechanical transmission; and  
         [0012]      FIG. 2  is a schematic cross-sectional illustration in fragmentary view of a portion of the hybrid electrical/mechanical transmission of  FIG. 1 .  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     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 .  
         [0014]     Referring now to  FIG. 2 , a valve body  34  is in fluid communication with a fluid source  35  and a pump  37 , and is capable of delivering pressurized fluid. The fluid source  35  and pump  37  may be located anywhere on the vehicle and fluidly connected with the valve body  34 , as will be understood by those skilled in the art.  
         [0015]     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. A first flow passage  38  and a second flow passage  40  are formed within the center support  36  and are in fluid communication with the valve body  34  through a third flow passage  42  formed in the first portion  30  of the transmission case.  
         [0016]     The clutch  15  is disposed within a housing or clutch hub  44  adapted to rotate about the center axis  14 . The clutch hub  44  is mounted to the center support  36  by a plurality of fasteners  46 . One or more of the fasteners  46  includes a fourth flow passage  48  disposed therein. In a preferred embodiment there are five fasteners  46  evenly distributed in a circular pattern. Four of the fasteners  46  are preferably solid fasteners  46   a  and one of the fasteners  46  is a hollow fastener  46   b  defining a flow passage  48  which is in fluid communication with the flow passage  40  and the clutch  15 . The four solid fasteners  46   a  each preferably include a threaded end portion  47  to maintain engagement between the clutch hub  44  and the center support  36 , whereas the hollow fastener  46   b  is preferably press fit into position between the clutch hub  44  and the center support  36 . While the number and configuration of fasteners  46  have been described in the context of a preferred embodiment, it should be appreciated that alternate quantities and configurations of the fasteners  46  may be envisioned, and that the fasteners  46  may include different combinations of fasteners  46   a  and/or  46   b.    
         [0017]     Having described the structure of the present invention, it should be appreciated by one skilled in the art that the clutch  15  may be actuated by hydraulic fluid from the fluid source  35  in the following manner. Fluid from the fluid source  35  is delivered by the pump  37  through valve body  34 , then through flow passages  42 ,  38 ,  40  and  48 , and finally to the clutch  15  for the actuation thereof. Accordingly, the fasteners  46  serve a dual purpose. More precisely, the solid fasteners  46   a  serve to retain the clutch hub  44  to the center support  36  and the hollow fastener  46   b  provides pressurized hydraulic fluid for the actuation of the clutch  15 .  
         [0018]     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.