Abstract:
A drive assembly for a drive assembly or transmission is provided. The drive assembly includes a front cover; a piston plate slidable axially toward and away from the front cover; a connection plate axially between the front cover and the piston plate elastically connecting the front cover and piston plate to each other; and at least one seal along at least one radial end of the piston plate, the connection plate and the piston plate retaining the at least one seal axially therebetween. A method of forming a drive assembly is also provided.

Description:
This claims the benefit to U.S. Provisional Patent Application No. 61/822,945, filed on May 14, 2013, which is hereby incorporated by reference herein. 
    
    
     The present disclosure generally relates to a drive assembly and more specifically to a connection between a front cover and a piston plate of a drive assembly. 
     BACKGROUND 
     U.S. Publication No. 2011/0290612 discloses a clip seal with integrated clutch pack return spring. 
     U.S. Pat. Nos. 6,293,380 and 6,640,945 disclose flexible plates with integrated leaf springs. 
     U.S. Pat. No. 8,056,692 discloses a clip seal piston. 
     U.S. Publication No. 2009/0032351 discloses a plate arranged to seal a piston and provide a drive surface for attachment of the leaf springs. 
     SUMMARY OF THE INVENTION 
     A drive assembly for a torque converter or transmission is provided. The drive assembly includes a front cover; a piston plate slidable axially toward and away from the front cover; a connection plate axially between the front cover and the piston plate elastically connecting the front cover and piston plate to each other; and at least one seal along at least one radial end of the piston plate, the connection plate and the piston plate retaining the at least one seal axially therebetween. 
     Embodiments of the drive assembly may also include one or more of the following advantageous features: 
     The connection plate may include at least one leaf spring formed therein elastically connecting the front cover and the piston plate. At least one of the front cover and the piston plate may be riveted to the at least one leaf spring. The at least one of the front cover and the piston plate may be riveted to the at least one leaf spring by rivets extruded from the front cover. The at least one leaf spring may include a circumferentially inner hole and a circumferentially outer hole formed therein, the front cover being riveted through the circumferentially outer holes, the piston plate being riveted through the circumferentially inner hole. The connection plate and the piston plate may define at least one coined groove retaining the at least one seal axially therebetween. The at least one seal may include an inner radial seal and an outer radial seal, the at least one coined groove including a radially outer coined groove retaining the radial outer seal axially therebetween and a radially inner coined groove retaining the radial inner seal axially therebetween. The drive assembly may further include an inner radial support surface and the at least one seal may include a radial inner seal slidable along the inner radial support surface via movement of the piston plate. The drive assembly may further include an outer radial support surface, the at least one seal including a radial outer seal slidable along the outer radial support surface via movement of the piston plate. The drive assembly may further include a clutch plate, the piston plate and the connection plate being axially movable away from the front cover so the piston plate engages the clutch plate. 
     A method of forming a drive assembly is also provided. The method includes connecting a piston plate to a front cover with a connecting plate axially between the front cover and the piston plate such that the piston plate is slidable axially toward and away from the front cover; and retaining at least one seal axially between the connection plate and the piston plate along at least one radial end of the piston plate. 
     Embodiments of the method may also include one or more of the following advantageous features: 
     The method may further include providing a clutch plate for engagement with the piston plate, the piston plate being axially between the clutch plate and the front cover. The connection plate may include at least one leaf spring formed therein, the at least one leaf spring connecting the piston plate to the front cover. The connecting may include riveting the front cover to the at least one leaf spring with a rivet extruded from the front cover. The connecting may include riveting the piston plate to the at least one leaf spring. The retaining may include holding the at least one seal in at least one coined groove defined by at least one radial end of the piston plate and at least one radial end of the connection plate. The at least one seal may include an inner radial seal and an outer radial seal, the at least one coined groove may include a radial inner coined groove defined by radial inner ends of the piston plate and the connection plate. The at least one coined groove may include a radial outer coined groove defined by radial outer ends of the piston plate and the connection plate. The retaining may include holding the inner radial seal in the radial inner coined groove and holding the outer radial seal in the radial outer coined groove. The method may further include providing the connection plate and piston plate between an inner radial support surface and an outer radial support surface such that the inner radial seal slides axially along the inner radial support surface and the outer radial seal slides axially along the outer radial support surface as the connection plate and piston plate move axially toward and away from the front cover. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described below by reference to the following drawings, in which: 
         FIG. 1  shows a cross-sectional side view of a torque converter or a transmission of a motor vehicle including a drive assembly according to an embodiment of the present invention; 
         FIG. 2  shows plan view of a connection plate of the drive assembly shown in  FIG. 1 ; and 
         FIG. 3  shows two unattached leaf springs in a nested arrangement. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a cross-sectional view of a torque converter  100  or a transmission  102  of a motor vehicle including a drive assembly  10  according to an embodiment of the present invention. Drive assembly  10  includes a front cover  12  and a piston plate  14  that is moveable axially toward and away from front cover  12  to engage a friction surface  16  on a first surface of a clutch plate  18  and press a friction surface  20  on a second surface of clutch plate  18 , opposite of the first surface, against a clutch backing plate  22 . A connection plate  24  is provided axially between piston plate  14  and front cover  12  to elastically connect piston plate  14  to front cover  12 . Connection plate  24  includes at least one leaf spring  26  formed therein by cutting spaces  28  into an interior  29  of connecting plate  24  between a radial inner end  30  and a radial outer end  32  of connecting plate  24 , as shown in  FIG. 2 .  FIG. 2  shows a plan view of connection plate  24 , which in this embodiment includes four leaf springs  26 . In other embodiments, connection plate  24  may include more or less than four leaf springs  26 . In this embodiment, leaf springs  26  are not stepped, but they may be stepped in other embodiments. 
     Leaf springs  26  extend circumferentially in connection plate  24  and each include two holes  34 ,  36  formed therein. First hole  34  is formed at a free end  38  of leaf spring  26  and second hole  36  is formed at a base end  40  of leaf spring  26 , which connects leaf spring  26  to interior  29  of connection plate  24 . In an alternative embodiment, second holes  36  may be formed in the interior  29  of connection plate  24  instead of in leaf springs  26 . Free end  38  of leaf spring  26  directly connects connection plate  24  to front cover  12  and base end  40  of leaf spring  26  directly connects connection plate  24  to piston plate  14 . To accomplish such connections, front cover  12  may be riveted to connection plate  24  via first hole  34  and piston plate  14  may be riveted to connection plate  24  via second hole  36 . 
     In embodiment shown in  FIG. 1 , front cover  12  is riveted to connection plate  24  by extruding front cover  12  with such a force that an extruded rivet  42  is formed, installing the rivet into hole  34 , and expanding the rivet to form a head. Rivet  42  fixedly connects free end  38  of leaf spring  26  and front cover  12  together. A punch may be used to extrude a portion of front cover  12 , leaving an indentation  44  in an outer surface  46  of front cover  12 . In this embodiment, after front cover  12  is riveted to connection plate  24 , piston plate  14  is riveted to connection plate  24 . In alternative embodiments, instead of extruded rivets  42 , front cover  12  may be connected to connection plate  14  by conventional, cold headed rivets. 
     In embodiment shown in  FIG. 1 , piston plate  14  is riveted to connection plate  24  by a rivet  48 , fixedly connecting base end  40  of leaf spring  26  and piston plate  14  together. As rivet  48  is extruded into hole  36 , an inner surface  54  of front cover  12  may be used as a back stop. 
     Before piston plate  14  is connected to connection plate  24 , an inner radial seal  56  is provided along an inner radial support surface  61  and an outer radial seal  58  is provided along an outer radial support surface  63 . After piston plate  14  is connected to connection plate  24 , piston plate  14  and connection plate  24  retain radial seals  56 ,  58 . Connection plate  24  and piston plate  14  are shaped such that after piston plate  14  is connected to connection plate  24 , radial inner end  30  of connecting plate  24  and a radial inner end  60  of piston plate  14  define an inner radial coined groove  64  holding inner radial seal  56  and a radial outer end  32  of connecting plate  24  and a radial outer end  62  of piston plate  14  define an outer radial coined groove  66  holding outer radial seal  58 . While shown spaced apart from seals  56 ,  58  in  FIG. 1  for clarity, one or both of radial inner ends  30 ,  60  may contact inner radial seal  56  to axially retain seal  56  and one or both of radial outer ends  32 ,  62  may contact outer radial seal  58  to axially retain seal  58 . In this embodiment, half grooves  68 ,  70  are stamped into radial ends  60 ,  62  of piston plate  14  to define respective radial edges of coined grooves  64 ,  66 . In other embodiments, connection plate  24  may be shaped to define respective radial edges of coined grooves  64 ,  66 . 
     After piston plate  14  is connected to connection plate  24 , clutch plate  18  may be provided adjacent to piston plate  14  and clutch backing plate  22  may be provided, such that clutch plate  18  is positioned axially between piston plate  14  and clutch backing plate  22 . Clutch backing plate  22  is axially retained by a retainer  71  held in a groove in outer radial support surface  63  to axially stop clutch plate  18 . The connection of piston plate  14  to connection plate  24  causes seals  56 ,  58  to seal a first pressure region  72  defined by front cover  12 , connection plate  24  and support surfaces  61 ,  63  from a second pressure region  74  partially defined by surface  52  of piston plate  14 . When the fluid pressure in first pressure region  72  is greater than the fluid pressure in second pressure region  74 , piston plate  14  engages clutch plate  18 . The engagement of clutch plate  18  by piston plate  16  allows for the transmission of torque from front cover  12  to clutch plate  18  via at least one leaf spring  26 . 
     In additional embodiments, if stacked leaf springs are desired, unattached leaf springs  126  may be stamped from the inner diameter and the outer diameter of connection plate  24 . That is, because connection plate  24  is a round plate, a rectangular blank from which it is formed includes scrap metal at the four quadrants between an outer diameter of the plate and an outer perimeter of the blank. Furthermore, the blank includes a scrap metal portion within an inner diameter of the connection plate. In order to conserve material, leaf springs  126  may be formed in these scrap portions. Leaf springs  126  may be oriented in the scrap metal portion end to end, or in a nested arrangement, which is shown in  FIG. 3 . Otherwise stated, durability of the plate connection may be improved by stacking leaf spring  126  on top of leaf spring  26  during assembly such that hole  134  is aligned with hole  34  and hole  136  is aligned with hole  36  and riveting the springs together so that torque load transferred between cover  12  and piston plate  14  by plate  24  is shared evenly by each spring. Alternatively, hole  136  in leaf spring  126  may be fixed to hole  34  in leaf spring  24  (i.e., by riveting) and hole  134  in leaf spring  126  may be fixed to cover rivet  42 , extending a circumferential length of the leaf spring and reducing an axial force acting on piston plate  14 . 
     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.