Abstract:
A support structure for a rotor within a transmission system is provided. The cantilevered support structure is umbrella-shaped to create an area of space between the rotor and the main shaft where other vehicle components, such as a gear set or system of clutches, may be packaged. The cantilevered support structure may be a true cantilever or a steady-rested cantilever. The support structure maintains the rotor at a distance from the transmission main shaft to maintain torque within the system while compacting packaging requirements. A second cantilevered support structure is wineglass-shaped to create a second area of packaging space between the rotor and the main shaft. The support structures may be telescoped to further compact the transmission.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application claims the benefit of U.S. Provisional Application No. 60/602,983, filed Aug. 19, 2004, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This invention relates to a support system for a rotor in a vehicle transmission system. 
     BACKGROUND OF THE INVENTION 
     An electrically-variable vehicle transmission typically includes a motor/generator module having a rotor and stator. In previous designs the rotor and stator are supported by a support system referred to as a “can” design. The “can” design supports the stator and maintains an internal area for the rotor to rotate around the transmission center axis while supported by a rotor support structure. The “can” design surrounds or encloses the stator, rotor, and rotor support structure on all sides and, thus, may limit the range of other mechanisms or components that can reside in the space within the “can” by restricting the available space for packaging between the motor/generator module and the center axis of the transmission system. 
     SUMMARY OF THE INVENTION 
     The support structure of the present invention supports a rotor at a distance from a transmission center axis to maintain torque within a vehicle transmission system while reducing packaging requirements by increasing available space adjacent to the support structure, particularly between the transmission main shaft and the rotor. The support structure provides improved packaging while supporting the rotor in the transmission system. 
     The support structure is a cantilevered system, wherein “cantilevered system” includes both a true cantilever and a steady-rested cantilever. A steady-rested cantilever is a cantilevered system wherein one or more bearings lend additional support to the support structure. The support structure is connected to the rotatable main shaft such that the support structure and the connected rotor rotate therewith. The cantilevered nature of the support structure creates a packaging space radially within the rotor, adjacent to the support structure. The packaging space may be used to house vehicle components such as a gear set or a system of clutches. 
     The support structure of the present invention is adapted to support a rotor in a vehicle transmission system. The support structure may have a substantially umbrella-shaped body that is rotatable about the main axis of the transmission system. The umbrella-shaped body supports the rotor at a radial distance and concentric with the center axis of the main shaft of the transmission system. By supporting the rotor at a radial distance, the umbrella-shaped body creates a packaging space between the rotor and the main shaft where transmission components may be packaged and retained. 
     The support structure of the present invention, which is adapted to support a rotor in a vehicle transmission system, also has a first portion adapted to connect to the transmission main shaft for rotation therewith. A second portion of the support structure is configured as an annular skirt substantially as long as the rotor. The second portion extends axially from the first portion in an unsupported cantilevered manner. The second portion is spaced sufficiently from the transmission main shaft to form an unobstructed packaging space for the length of the skirt. The packaging space is open on one axial end to provide a housing for vehicle components within the packaging space. 
     Accordingly, packaging space and a rotor support structure for a transmission and its other components are provided. A first embodiment includes a first structure with a shaft portion adapted to connect with an internal transmission driveshaft. The first structure also has a first skirt portion configured to circumscribe the shaft portion and support a first rotor. The first embodiment also includes a second structure having a sleeve portion configured to telescopingly receive the shaft portion of the first structure. The second structure has a second skirt portion configured to support a second rotor. The first and second skirt portions are sufficiently spaced from the axis of the mainshaft such that the installed shaft portions of the first and second structures overlap and concentrically align with the bearings, and other transmission components may be compactly packaged beneath the skirt portions. Additionally, the first structure may be substantially umbrella-shaped and the second structure may be substantially wineglass-shaped. 
     The present invention provides a support structure adapted to support a rotor in a vehicle transmission system having a rotatable main shaft. The support structure comprises an annular-skirted body connected with the main shaft. The annular-skirted body of the support structure maintains the rotor at a radial distance from the center axis of the transmission system. The radial distance of the annular-skirted body is sufficient to create a packaging space between the rotor and the main shaft where at least one transmission component may be packaged and retained. 
     The present invention provides a support arrangement adapted to support a pair of rotors in a vehicle transmission system having a rotatable main shaft. The support arrangement comprises first and second grounded support structures for respectively supporting one of the pair of rotors. Each of the first and second support structures maintains a respective radial distance from the center axis of the transmission system. Each radial distance creates a packaging space between the respective rotor and the main shaft sufficient to retain at least one respective transmission component. 
     The present invention provides a support structure adapted to support a rotor in a vehicle transmission system having a rotatable main shaft. The support structure includes a first portion of the support structure having a shaft portion adapted to be connected to the main shaft for rotation with the main shaft and a second portion of the support structure configured as an annular skirt. The annular skirt is substantially as long as the rotor and extends axially from the first portion in an unsupported cantilever manner spaced sufficiently from the shaft portion to form an unobstructed packaging space for the length of the annular skirt. The annular skirt is open on one axial end to house at least one transmission component within the packaging space. 
     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 
         FIG. 1  is a fragmentary vertical cross-sectional view, partly in elevation, of a transmission system including the first and second support structures of the present invention; 
         FIG. 2  is a schematic cross-sectional half-view of the first umbrella-shaped structure of the present invention; 
         FIG. 3  is a schematic cross-sectional half-view of the second wineglass-shaped structure of the present invention; and 
         FIG. 4  is an exploded schematic perspective view with parts broken away to show both the umbrella-shaped and wineglass-shaped rotor support structures of this invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a fragmentary vertical cross-sectional view of a vehicle transmission system  10  having two motor/generator modules  14   a ,  14   b . Each motor/generator module  14   a ,  14   b  comprises a rotor  18   a ,  18   b  and a stator  22   a ,  22   b . The stators  22   a ,  22   b  are connected to the transmission housing  26  and, thus, remain stationary within the transmission housing  26 . The stators  22   a ,  22   b  may be connected to the transmission housing  26  either directly or indirectly, such as being connected to the end cover  27  or center support  28  which is, then, connected to the transmission housing  26 . The rotors  18   a ,  18   b  are supported by support structures  30   a ,  30   b  that are connected to shafts  42   a ,  42   b  which are concentric with the main shaft  34  of the transmission system  10  and, thus, may rotate about the center axis  38 . The connecting portion of support structure  30   b  is a center shaft portion  42   b . The connecting portion of support structure  30   a  is a hollow shaft portion  42   a  configured for telescopingly nesting with the adjacent center shaft portion  42   b  of support structure  30   b  as shown in  FIG. 1 . This telescoping nesting provides additional alignment support for the rotors. The shaft connections of  42   a ,  42   b  may be by a spline, clutch, or gear, as required by the transmission schematic selected. 
     The support structures  30   a ,  30   b  may be true cantilevers or steady-rested cantilevers. A “true” cantilever is a structure that is supported at one end and is subject to a load along the length of the structure, such as the annular skirt portions  46   a ,  46   b , as shown in  FIGS. 2-4 , of the support structures  30   a  and  30   b . A “steady-rested” cantilever is similar to a true cantilever with at least one additional bearing for additional support. Bearings  58   a ,  58   b  provide support to the transmission housing  26 , and therefore ground, providing radial positioning of structures  30   a  and  30   b . Bearing sets  54   a ,  54   b  in  FIGS. 1 ,  2 , and  3  are steady rest bearings providing a second radial support, thereby defining a centerline of rotation of each assembly. Axial positioning is maintained with a combination of ball and thrust roller bearings as shown in  FIG. 1 . Other arrangements of roller and thrust or multiple ball bearings may also be substituted. Decreasing the axial distance between two or more bearings may decrease the dimensional control of the support structures  30   a ,  30   b.    
       FIGS. 1 and 4  illustrate the support structures  30   a ,  30   b  in accordance with the present invention, wherein one support structure  30   b  (also illustrated in  FIG. 2 ) is a substantially “umbrella-shaped” design  62  and the other support structure  30   a  (also illustrated in  FIG. 3 ) is a substantially “wineglass-shaped” design  66 . The terms “umbrella” and “wineglass” refer to loose approximations of the general shapes of the support structures  30   a ,  30   b , such as shown in the perspective views of  FIG. 4 .  FIG. 4  illustrates the shape of the support structures  30   a ,  30   b  as generated by a full rotation of the structures shown in  FIGS. 2 and 3  about the center axis  38  of the transmission. 
     As illustrated in  FIG. 2 , the “umbrella-shaped” support structure  30   b  has a center shaft portion  42   b , where the support structure  30   b  is attachable to the main shaft  34 , as shown in  FIG. 1 . The main shaft  42   b  is engaged to at least one transmission component as described in commonly assigned co-pending U.S. Provisional Application No. 60/602,976, filed Aug. 19, 2004, entitled “Main Shaft Dog Clutch and Method,” to Diemer et al., which is incorporated in its entirety herein. The functionality of the dog clutch  70  of  FIG. 1  is also described in the above incorporated application. Referring back to  FIGS. 1 and 2 , the support structure  30   b  may have a first bearing  54   b  located along the center shaft portion  42   b  to lend extra support to the support structure  30   b . The umbrella-shaped structure  30   b  also has an annular skirt portion  46   b  where a rotor  18   b  is attachable. The skirt portion  46   b  has a closed end portion  50   b  which is affixed to the center shaft portion  42   b . A second bearing  58   b  may be located in an annular pocket  59  on the closed end portion  50   b . The term “umbrella-shaped” generally refers to a support structure  30   b  wherein the closed end portion  50   b  and skirt portion  46   b  are situated similar to an umbrella cover on a center shaft portion  42   b , which can be compared to an umbrella handle. More specifically, it refers to a support structure  30   b  wherein the skirt portion  46   b  and center shaft portion  42   b  rotate about the axis  38  of the main shaft  34 , and the center shaft portion  42   b  extends axially from the closed end portion  50   b  within the skirt portion  46   b.    
     As illustrated in  FIGS. 3 and 4 , the “wineglass-shaped” support structure  30   a  has a shaft portion  42   a , which telescopes over the shaft portion  42   b  of the support structure  30   b  for relative rotation on bearings  54   a  and  58   a , as shown in  FIG. 1 . Referring back to  FIG. 3 , the support structure  30   a  may be associated with a first bearing  54   a  located along the hollow shaft portion  42   a , which is a telescoping stem portion, to lend extra support to the wineglass structure  30   a . The wineglass shape also has an annular skirt portion  46   a  where a rotor  18   a  may attach. The skirt or bowl portion  46   a  is connected to the shaft or hollow shaft portion  42   a , which is the wineglass stem portion, extending from the closed end or bowl bottom portion  50   a  of the wineglass. A second bearing  58   a  may be located in an annular pocket  60  on the closed end portion  50   a . The term “wineglass shape” generally refers to a support structure  30   a  wherein the skirt or bowl portion  46   a  and the stem portion  42   a  rotate about the main axis  38  of the transmission and the stem portion  42   a  extends axially away from the interior of the skirt or bowl portion  46   a . The shaft portion connects to at least one transmission component determined by the transmission gear arrangement. 
     Referring to  FIGS. 1-3 , both support structures  30   a ,  30   b  support a respective rotor  18   a ,  18   b  at a respective radial distance A, B from the center axis  38  of the transmission system  10 . An increased respective radial distance A, B is associated with increased speed, which is calculated as the square of the respective radial distance A, B between the transmission system center axis  38  and its respective rotor  18   a ,  18   b . Thus, the skirt portions of the support structures  30   a ,  30   b  are spaced sufficiently from the main shaft  34  when the telescoped shaft portions  42   a ,  42   b  are drivably connected with the main shaft  34  to compactly package other components of the transmission therewithin. Transmission components, such as a clutch  72  or a gear set  74 , may be compactly packaged in the space  76  defined by skirt  46   a  and the open end of the wineglass bowl. Likewise, transmission components, such as a system of clutches  78 ,  80 , may be compactly packaged in the space  82  defined by skirt  46   b  and the open end of the umbrella cover. Spaces  76 ,  82  may also be sufficiently unobstructed to accommodate such compact packaging of transmission components. 
     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.