Abstract:
A clutch assembly includes a housing defining an axis. A plurality of plates disposed within the housing are in driving engagement with the housing around the axis. The housing defines a housing wall circumscribing the axis and having a sinusoidal configuration including a wall crest and a wall trough. The wall crest and the wall trough are substantially parallel to the axis defined by the housing. The plates have teeth complimentary of the sinusoidal configuration of the housing wall for engaging the housing wall enabling the driving engagement between the housing wall and the plates.

Description:
[0001]    The present application claims priority to U.S. Provisional Patent Application No. 61/723,483 filed Nov. 7, 2012. 
     
    
     BACKGROUND 
       [0002]    Clutch housings have been used in transmissions for transferring motive force between components of a vehicle for many years. A clutch assembly typically includes a number of clutch plates received by a clutch housing that are disposed in driven engagement with an annular wall of the clutch housing. As is known to those of skill in the art, clutch plates are coated with a frictional material, the compression of which causes the clutch plates disposed within the clutch housing to transfer motive force between a spindle axial aligned with the housing and mated to a clutch hub as is known to those of skill in the art of transmission assembly design and manufacturing. Modern performance requirements have resulted in an increase in the number of clutch assemblies in transmission. Manufacturers are presently attempting to design transmissions for motor vehicles having eight, nine, and even ten clutch assemblies. However, the space allowed in a motor vehicle for these transmissions has not been increased. 
         [0003]    One configuration of a known clutch housing wall is generally shown at  10 . A prior art wall  12  of the clutch housing at  10  includes splines  14 . The splines  14  define a trapezoidal configuration having a limited work surface  16  identified along line  18  of  FIG. 1 . Due to the limited work surface  16  of the prior art housing, a high number of clutch plates are required to transfer enough force between the axle (not shown) and the housing  10 . Therefore, it has been necessary to include a significant number of plates in each clutch housing adding to the axial length of the housing, which has a negative impact upon overall size of modern transmissions. Therefore, it would be desirable to develop a clutch assembly having a reduced number of clutch plates enabling the reduction of the axial length of typical clutch assembly. 
       SUMMARY 
       [0004]    A clutch assembly includes a housing defining an axis. A plurality of plates disposed within the housing are in driving engagement with the housing around the axis. The housing defines a housing wall circumscribing the axis and having a sinusoidal configuration including a wall crest and a wall trough. The wall crest and the wall trough are substantially parallel to the axis defined by the housing. The plates have teeth complimentary of the sinusoidal configuration of the housing wall for engaging the housing wall enabling the driving engagement between the housing wall and the plates. 
         [0005]    The inventive clutch assembly solves the problem of reducing axial length by way of increasing the work surface area between the teeth of the clutch plate and the splines defined by the clutch housing. The increased work surface area allows for the reduction of the number of clutch plates required of present clutch assemblies enabling the reduction of the axial length of the housing. The reduction of the axial length of the housing enables modern transmission design to include an increased number of clutches without increasing packaging space required of the transmission. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0007]      FIG. 1  shows a partial cross sectional view of a housing wall of a prior art clutch housing; 
           [0008]      FIG. 2  shows a perspective view of the clutch housing of the present invention; 
           [0009]      FIG. 3  shows a partial cross sectional view of the housing wall of the present invention; 
           [0010]      FIG. 4  shows plan view of the clutch housing of the present invention; 
           [0011]      FIG. 5  shows a partial cross sectional view of the clutch assembly of the present invention with a clutch plate engaging a wall of the clutch housing; 
           [0012]      FIG. 6  shows a partial cross sectional view of a housing wall of a prior art clutch housing; 
           [0013]      FIG. 7  shows an overlay of cross sections of the prior art clutch housing wall and the clutch housing wall of the present invention; 
           [0014]      FIG. 8  shows an a cross sectional view of an alternative embodiment of the present invention; and 
           [0015]      FIG. 9  shows a perspective view of further embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Referring to  FIG. 2 , a perspective view of an inventive clutch housing is generally shown at  20 . The clutch housing  20  defines an axis a (shown in  FIG. 3 ) around which a housing wall  22  is disposed. The housing wall  22  takes a sinusoidal configuration and includes a wall crest  24  and a wall trough  26 . The housing  20  defines a distal end  28  and a floor  30  disposed at an opposite end of the housing wall  22  from the distal end  28 . 
         [0017]    A groove  32  is disposed in the housing wall  22  proximate the distal end  28 . The groove  32  retains a snap ring  34  used to retain a plurality of clutch plates  36  ( FIG. 5 ). Each clutch plate  36  defines a plurality of teeth  38  having a sinusoidal configuration that is complementary to the sinusoidal configuration of the housing wall  22 . Therefore, the teeth  38  disposed on each clutch plate  36  is disposed in driving engagement with the housing wall  22 . As such, the teeth  38  of the plates  36  defined at teeth crests  40  and teeth troughs  42 . The teeth crests  40  engage the wall troughs  26  and the wall crest  24  engage the teeth troughs  42 . Each clutch plate  36  includes frictional material  37  covering substantially its full contact surface. Therefore, the frictional material  37  covers substantially the full extent of its teeth  38 . 
         [0018]    Referring now to  FIG. 6 , a work surface of the housing wall  22  is clearly is clearly shown at  44 . The work surface  44  is defined between the wall crest  24  and the wall trough  26 . The work surface  44  engages the teeth  38  of the clutch plates  36  to transfer motive force between the clutch plates  36  and the housing  20 . The work surface  44  defines a length  46  that is significantly longer than the prior art length  18  ( FIG. 4 ) of the prior art work surface  16  due to the truncation of the prior art spline  14  setting forth a trapezoidal cross section. In one embodiment, the work surface  44  of the housing wall  22  includes a thirty degree from a line extending radially outwardly from the axis a defined by the housing wall  22 . Additionally, the angle of the work surface  44  is contemplated by the inventor to fall within forty five and twenty degrees from the radial line set forth above. 
         [0019]    The configuration of the housing wall  22  and the teeth  38  provide benefits best represented by reviewing  FIG. 7 . As set forth above, the length of work surface  44  of the inventive housing wall shown at  22  is represented by line  46  in  FIG. 6 . The prior art wall  12  is overlaid upon the present inventive wall  22  showing a work surface having a length  18 . It should be obvious to those of ordinary skill in the art that a work surface Y of the present inventive housing wall  22  provides a greater surface area than the prior art work surface X of the prior art wall  12 . The greater work surface area allows for the decrease of the number of clutch plates  36  required to transfer force between the various components of the transmission. Additionally, nearly two wall crests  24  of the inventive housing wall  22  is provided in the same circumferential area as the tetrahedral spline  14  of the prior art wall  12 . This increase in the number of work surfaces  14  defined by the wall crest  24  and wall trough  26  of the present inventive housing wall  22  allowing for the further decrease in the number of clutch plates  36  required to transfer requisite force between components of the transmission assembly. Additionally, the sinusoidal wall  22  of the present invention is stronger than the prior art wall allowing for a decrease in wall  22  thickness. Maintaining constant out diameter of the housing  20  allows for an increase in the size of the plates  36 . Additionally, it is contemplated by the inventor that the housing wall  22  is merely a sleeve received either on the internal surface or the external surface of the housing  20  for providing additional strength to the housing  20 . This is particularly advantageous when the housing  20  is made from aluminum and the sleeve can provide a hardened surface based upon material selection. 
         [0020]    Referring again to  FIG. 6 , an inner surface  48  of each wall trough  26  defines a circulation element  50  to provide a venue for lubricant circulating through the housing  20 . Additionally, a plurality of apertures  52  are defined by the housing wall  22  to allow lubricant to pass inwardly and outwardly of the housing  20  in a desired manner. 
         [0021]    A cross sectional view of an alternative snap ring groove  132  of the housing  20  is shown in  FIGS. 8 . The housing  20  includes splines defined by wall crest  24  and wall trough  26  that are spaced from the distal end  28  of the housing wall  22 . The snap ring groove  312  is formed by forming a flange in the distal end  28  of the housing wall  22 . The snap ring is disclosed in U.S. Pat. No. 8,240,446, the contents of which are incorporated herein by reference. 
         [0022]    An alternative housing is shown in  FIG. 9  at  120 , wherein like elements of the prior embodiment include the same numbers only in the  100  series. In this embodiment, the housing  120  includes a substantially smooth outer surface  121  of the housing wall  122 . In this embodiment, the sinusoidal surface  123  of the inventive housing wall  122  is disposed only where driving engagement is required with the teeth  38  of the clutch plates  36  as shown in  FIG. 5 . Therefore, the wall crest  124  and the wall trough  126  are disposed solely upon the inner surface  123  of the housing wall  122 . The housing  120  defines a distal end  128  and a floor  130  disposed upon at an opposite end of the housing wall  122  from the distal end  128 . The snap ring groove is formed in the housing wall  122  proximate the distal end  128  of the housing wall  122 . The circulation element  150  is disposed at the wall trough  126  to facilitate the circulation of lubricant through the housing  120 . It is contemplated by the inventor that his embodiment of the housing  120  is formed by either by casting or roll forming sheet metal. However, other methods or combinations of methods of forming the housing  120  are also contemplated, such as, for example, forming the housing  120  from a tube. 
         [0023]    While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation while material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention but that the invention will include all embodiments falling within the scope of the appended claims.