Abstract:
A hybrid transmission including two electric motors and a plurality of planetary gear sets operatively connectable to the motors and to an engine is provided. Novel motor features are provided including structure adapted to improve reliability and to facilitate assembly. More precisely, a method is provided for locating and installing the components of a motor, including a rotor and a stator, within a covered housing to form a motor module. A plurality of rotor bearings and a position/speed sensor are also preferably added to the motor module. After the motor module is assembled, the motor may be tested and thereafter the motor module can be installed into a hybrid transmission as a single component utilizing conventional transmission assembly methods.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/555,270, filed Mar. 22, 2004, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates to a motor module for a hybrid electro-mechanical vehicular transmission.  
       BACKGROUND OF THE INVENTION  
       [0003]     Assembling a hybrid transmission typically includes individually installing the electric motor components into the transmission housing and thereafter testing the electric motors to ensure they perform satisfactorily. As the electric motors are magnetized, precisely assembling the components thereof within the hybrid transmission can be difficult and labor intensive.  
       SUMMARY OF THE INVENTION  
       [0004]     A hybrid transmission including two electric motors and a plurality of planetary gear sets operatively connectable to the motors and to an engine is provided. Novel motor features are provided including structure adapted to improve reliability and to facilitate assembly. More precisely, a method is provided for locating and installing the components of a motor, including a rotor and a stator, within a covered housing to form a motor module. A plurality of rotor bearings and a position/speed sensor are also preferably added to the motor module. After the motor module is assembled, the motor may be tested and thereafter the motor module can be installed into a transmission housing as a single component.  
         [0005]     The apparatus of the present invention includes a motor module for a hybrid transmission. The motor module includes a generally cylindrical module housing defining an outer diameter and an inner diameter. The module housing has an open end and an enclosed end opposite the open end. The module housing includes a spline at an internal portion of the outer diameter of the housing. The module housing also includes a locating shoulder at the internal portion of the outer diameter of the housing. A motor assembly is disposed within the module housing such that the motor assembly is axially located by the locating shoulder and radially oriented by the spline. The motor assembly includes a stator and a rotor circumscribed by the stator. A housing cover is preferably attached to the open end of the module housing to enclose the motor assembly. The housing cover includes a plurality of tabs adapted to facilitate the attachment of the motor module to the transmission housing. According to a preferred embodiment, the rotor bearings and position/speed sensor are integrally retained by the module housing and/or housing cover.  
         [0006]     The motor assembly is preferably interference fit into the housing, and the housing is preferably slip fit into the hybrid transmission. The housing may be covered by bolting the housing cover thereto after the motor has been inserted so that the cover may be removed, for example, if it becomes necessary to repair the motor. According to a preferred embodiment, a spring washer is mounted between one of the plurality of rotor bearings and the housing cover.  
         [0007]     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  
       [0008]      FIG. 1  is a schematic fragmentary cross-sectional view of a hybrid electromechanical transmission;  
         [0009]      FIG. 2  is a schematic fragmentary cross-sectional view of a frontward portion of the transmission of  FIG. 1 ;  
         [0010]      FIG. 2A  is a schematic fragmentary cross-sectional view of a motor assembly and a module housing of the transmission of  FIG. 1 ;  
         [0011]      FIG. 3  is a schematic fragmentary cross-sectional view of a rearward portion of the transmission of  FIG. 1 ; and  
         [0012]      FIG. 4  is a schematic perspective view of a housing and attached cover for a motor module used in the 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 the upper half of a transmission  10 , in -cross sectional view. The lower half of the transmission (not shown) is disposed on the opposite side of center axis  12 . First and second electric motor modules  14 ,  16 , respectively, are disposed about the center axis  12  within the transmission  10 . A main shaft  20  is longitudinally disposed, rotatable about the center axis  12 . A plurality of inner shafts, such as inner shaft  22 , are concentrically disposed about the main shaft  20 , and are likewise rotatable about the center axis. An input shaft  24  is disposed forward of the main shaft  20  and is operable for transferring power from an engine (not shown) to the transmission  10 . Engagement of one or more of a plurality of clutches included in the transmission  10  (first, second, third and fourth clutches,  26 ,  28 ,  30  and  32  respectively, being shown) interconnects one or more of first, second and third planetary gear sets  34 ,  36 , and  38 , respectively, to transfer power at varying ratios to an output member (not shown). As will be readily understood by those skilled in the art, each of the planetary gear sets includes a sun gear member, a planet carrier assembly member and a ring gear member. A fifth clutch, referred to as a lockout clutch  42 , is operable for locking out torsion isolator  44  (also referred to as damper springs) from surrounding structural elements, and to provide a direct connection between the engine and transmission.  
         [0014]     Referring to  FIGS. 2 and 3 , the first and second motor modules  14 ,  16 , respectively, are each self-contained assemblies. The motor modules  14 ,  16  each include a motor  46 A,  46 B, respectively. The motors  46 A,  46 B each include a rotor  48 A,  48 B and a stator  50 A,  50 B, respectively.  
         [0015]     The motors  46 A,  46 B are preferably enclosed within a drum comprised of a generally cylindrical module housing  54 A,  54 B and a module housing cover  56 A,  56 B. Each module housing  54 A,  54 B includes an open end  58 A,  58 B adapted to facilitate the insertion of a motor, and an enclosed end  60 A,  60 B. The module housings  54 A,  54 B define outer diameters  80 A,  80 B, and inner diameters  82 A,  82 B, respectively. The outer diameters  80 A,  80 B of the module housings  54 A,  54 B include an internal surface  84 A,  84 B and an external surface  86 A,  86 B. The module housing covers  56 A,  56 B are -respectively attached to the open end  58 A,  58 B of the module housing  54 A,  54 B after the motors  46 A,  46 B have been inserted therein as will be described in detail hereinafter. According to a preferred embodiment, the housing  54 A,  54 B is composed of formed steel and the cover  56 A,  56 B is stamped steel, however, it should be appreciated that the housing and cover may be composed of alternate materials and/or fabricated according to other known manufacturing processes. As the motors  46 A,  46 B are completely enclosed, the risk of contamination by debris is reduced. This is particularly advantageous for the electric motors  46 A,  46 B of the present invention in that the motors are magnetized and therefore prone to attracting contaminants. [ 0016 ] The modules  14 ,  16  are preferably pre-assembled prior to installation in the transmission  10 . Additionally, the pre-assembled modules may be independently tested for compliance with performance requirements prior to installation. In this manner, assembly of the hybrid transmission is simplified by the installation of pre-assembled and pre-tested modules  14 ,  16  instead of a plurality of motor components that require additional testing.  
         [0016]     Referring to  FIG. 2 , the stator  50 A is preferably interference fit into the module housing  54 A. As is known in the art, an interference fit is one wherein the outer diameter of the stator  50 A is larger than the inner diameter of the module housing  54 A such that there is an interference therebetween when the parts are assembled. According to a preferred embodiment of the present invention, the size of the module housing  54 A is increased by heating, and the size of the stator  50 A is reduced by cooling. Thereafter, the undersized stator  50 A is inserted into the oversized module housing  54 A such that when the components reach ambient temperature there is an interference fit maintaining engagement. The motor module  14  is preferably slip fit into the transmission housing  74 , which allows simple installation and removal of the stator  50 A. A slip fit is a more conventional type fit wherein there is clearance between components such that they are easily assembled and disassembled. The module housing  54 A includes an internal locating shoulder  68  adapted to axially locate the stator  50 A. As shown in  FIG. 2A , the module housing  54 A also includes an internal spline  96 A (shown in  FIG. 2A ) adapted to engage a corresponding feature  98 A of the motor assembly  46 A for radial orientation.  
         [0017]     Referring again to  FIG. 2 , the housing  54 A includes an external shoulder portion  100 A adapted to provide integral support for a rotor bearing  62 A. The housing  54 A also preferably includes an internal shoulder portion  102 A adapted to integrally retain a position/speed sensor  130 . A second rotor bearing  64 A is supported by an external shoulder portion  104 A of the housing cover  56 A. A spring washer  63 A is preferably disposed between the rotor bearing  64 A and either the housing cover  56 A or the housing  54 A, and applies a pre-load adapted to control axial motion of the motor module  14 . The housing  54 A and housing cover  56 A with integral rotor bearings  62 A,  64 A will more precisely control the concentricity of the stator  50 A and rotor  48 A than could be accomplished with non-integral bearings because the present design implements fewer components (devices for mounting and retaining the rotor bearing are unnecessary), such that the tolerance stack-up is reduced. This leads to improved performance of the motor  46 A by allowing a smaller air gap  66  between the stator  50 A and the rotor  48 A.  
         [0018]     The cover  56 A is preferably piloted on and bolted to the open end  58 A of the module housing  54 A with bolts  70  so that the cover  56 A is removable if, for example, it becomes necessary to repair the motor  46 A. It should be appreciated, however, that the cover  56 A may alternatively be attached to the module housing  54 A in any-conventional manner.  
         [0019]     As best shown in  FIG. 4 , the attached housing  54 A and cover  56 A, containing the rotor/stator assembly  48 A,  50 A (shown in  FIG. 2 ) create a self-contained motor module  14  that may be tested prior to installation in the transmission housing  74  (shown in  FIG. 2 ). Additionally, the attached housing  54 A and cover  56 A will help exclude debris from the motor module  14 , both during shipping and handling and after installation. Debris will be prevented from entering the air gap  66  between the rotor  48 A and stator  50 A (shown in  FIG. 2 ), thereby enhancing motor performance.  
         [0020]     The housing cover  56 A also has three external mounting tabs  72  (one shown) radially spaced about the cover that allow the motor module  14  to be bolted to the transmission main housing  74 . The mounting tabs  72  provide easily accessible attachment and facilitate the absorption of stator torque by the transmission housing  74 . The second motor module  16  of  FIGS. 1 and 3  has structural characteristics similar to those described hereinabove for motor module  14 .  
         [0021]     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.