Abstract:
A cover assembly for a torque converter is also provided. The cover assembly includes a front cover and a drive plate connected to an outer surface of the front cover for coupling to the front cover to an engine crankshaft. The drive plate includes elastic preloading elements pressing against the outer surface of the front cover. A method of forming a cover assembly for a torque converter is also provided.

Description:
[0001]    This claims the benefit to U.S. Provisional Patent Application No. 61/862,707, filed on Aug. 6, 2013, which is hereby incorporated by reference herein. 
     
    
       [0002]    The present disclosure relates generally to torque converters and more specifically to cover assemblies for torque converters. 
       BACKGROUND 
       [0003]    U.S. Pat. No. 7,011,196 discloses a torque converter having a drive plate welded to a front cover at two radial locations. 
       SUMMARY OF THE INVENTION 
       [0004]    A cover assembly for a torque converter is provided. The cover assembly includes a front cover and a drive plate connected to an outer surface of the front cover for coupling to the front cover to an engine crankshaft. The drive plate includes elastic preloading elements pressing against the outer surface of the front cover. 
         [0005]    Embodiments of the cover assembly may also include one or more of the following advantageous features: 
         [0006]    Each elastic preloading element may be formed in an interior of the drive plate. The elastic preloading elements may be formed by tabs formed into the interior of the drive plate and bent toward the front cover. The tabs may extend radially away from a center axis of the drive plate. The drive plate may include radial protrusions at an outer circumference thereof and the tabs may extend into the radial protrusions. The drive plate may be connected to the front cover by rivets. The rivets may be extruded from the front cover through holes in the drive plate. The elastic preloading elements may be radially outside of the rivets. 
         [0007]    A method of forming a cover assembly is also provided. The method includes fixing a drive plate to an outer surface of a front cover of the torque converter such that elastic preloading elements of the drive plate press against the outer surface and are compressed. 
         [0008]    Embodiments of the method may also include one or more of the following advantageous features: 
         [0009]    The method may further include forming the elastic preloading elements within an interior of the drive plate. The forming the elastic preloading elements may include forming slots in the interior of the drive plate to form tabs and bending the tabs away from the interior of the drive plate. The drive plate may include radial protrusions at an outer circumference thereof and the slots may be formed to extend into the radial protrusions. The fixing the drive plate to the front cover may include riveting the drive plate to the front cover. The riveting the drive plate to front cover may include extruding the front cover through holes in the drive plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The present invention is described below by reference to the following drawings, in which: 
           [0011]      FIG. 1  shows a half plan view of a cover assembly of a torque converter in accordance with an embodiment of the present invention; and 
           [0012]      FIG. 2  shows a cross-sectional view of the cover assembly along A-A of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Embodiments of the present disclosure show a drive plate that is preloaded by elastic preloading elements when the drive plate is fixed to the front cover of a torque converter by for example riveting or welding. The elastic preloading element may limit the cyclic loading at the connection between the drive plate and the front cover (i.e., for example at the weld or rivets) to mostly when in compression. 
         [0014]      FIG. 1  shows a half plan view of a cover assembly  10  of a torque converter  12  in accordance with an embodiment of the present invention. Cover assembly  10  includes a drive plate  14 , a front cover  16  and a pilot  18 . Cover assembly  10  is connectable to a crankshaft of an internal combustion engine via pilot  18  at a center axis  20  and lugs  22  circumferentially spaced about center axis  20  that are fixed to drive plate  14 . Front cover  16  is connectable to a rear cover is form a housing, which may house a lockup clutch, a damper, a turbine, an impeller and a shaft for connecting to a variable speed transmission. Drive plate  14  and front cover  16  are fixed together by a plurality of rivets  24  spaced circumferentially about center axis  20 . 
         [0015]    In order to preload drive plate  14  when drive plate  14  is fixed to front cover  16 , drive plate  14  includes a plurality of elastic preloading elements  26  circumferentially spaced about center axis  20 .  FIG. 1  shows two preloading elements circumferentially aligned with one of radial protrusions  28 , which extend radially outward at an outer circumference of drive plate  14 . While only two elastic preloading elements  26  are shown in  FIG. 1 , preferred embodiments of the present invention include more than two preloading elements. For example, drive plate  14  may include two elastic preloading elements  26  circumferentially aligned with each of radial protrusions  28 , such that drive plate  14 , which include six radial protrusions  28 , includes twelve elastic preloading elements  26 . 
         [0016]    In this embodiment, elastic preloading elements  26  are formed in an interior  30  of drive plate  14 . Drive plate  14  is formed by a metal plate processed to remove material therefrom to form slots  32  that define preload tabs  34  in drive plate  14  and provide preload tabs  34  with a flexible geometry. Preload tabs  34  each include a free end  36  connected to interior  30  of drive tab  14  by a base end  38 . A radially extending portion of each preload tab  34  extends radially from base end  38  away from center axis  20  such that each preload tab  34  is substantially finger-shaped. As shown in  FIG. 1 , tabs  34  extend into radial protrusions  28  on opposite sides of the respective lug  22  in radial protrusion  28 . Drive plate  14  and front cover  16  are arranged such that radial protrusions  28  extend radially outward past an outer circumference of front cover  16  and lugs  22  are centered along the outer circumference of front cover  16 . 
         [0017]      FIG. 2  shows a cross-sectional view of cover assembly  10  along A-A shown in  FIG. 1 . As shown in  FIG. 2 , front cover  16  is substantially cup shaped so as to include a first portion  40  extending radially and a second portion  42  extending axially from a radially outer end of first portion  40 . Pilot  18  is welded to first portion  40  by a weld  44 , In embodiment shown in  FIG. 2 , drive plate  14  is riveted to front cover  16  by extruding front cover  16  with such a force that each rivet  24  is formed as an extruded rivet, installing the rivet into a respective hole  46  formed in drive plate, and expanding the rivet to form a head  48 . For each rivet  24 , a punch may be used to extrude a portion of front cover  16 , leaving an indentation  50  in an inner surface  52  of first portion  40  of front cover  16 . In alternative embodiments, instead of extruded rivets, rivets  24  may be conventional, cold headed rivets. 
         [0018]    One elastic preloading element  26  is illustrated in  FIG. 2  by dotted lines, as preloading element  26  is offset from A-A in  FIG. 1 . As shown in  FIG. 2 , preloading element  26  is formed by bending tab  34  away from interior  30  of drive plate  14  so that the bent tab  34  contacts and presses against outer surface  54  of first portion  40  of front cover  16  with free end  36  of tab  34  when drive plate  14  is fixed to front cover  16 . Tab  34  is compressed by the connection between drive plate  14  and front cover  16  and is urging front cover  16  away from drive plate  14 . 
         [0019]    To form cover assembly  10 , elastic preloading element are formed in interior  30  of drive plate  14  by cutting slots  32  into interior  30  so as to define tabs  34 . Tabs  34  are then bent axially away from interior  30 . Drive plate  14  may then be fixed to outer surface  54  of front cover  16  such that elastic preloading elements  26  of drive plate  14  press against outer surface  54  and are compressed. 
         [0020]    In alternative embodiments of the present invention, instead of being fixed together by rivets  24 , drive plate  14  and front cover  16  may be welded together. 
         [0021]    In the preceding specification, the invention has been described with reference to specific exemplary embodiments and examples thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative manner rather than a restrictive sense.