Abstract:
A torque converter including a cover and a bridging clutch for selective connection to the cover, the bridging clutch including a clutch plate fixed to the cover and having an inner radial surface and having a piston having an outer radial surface opposite the inner radial surface. A method for assembling a torque converter is also provided.

Description:
[0001]    Priority to U.S. Provisional Patent Application Ser. No. 60/962,734, filed Jul. 31, 2007, is claimed, the entire disclosure of which is hereby incorporated by reference herein. 
         [0002]    The present invention relates generally to hydraulic torque converters, and more particularly to hydraulic torque converters having bridging clutches. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    U.S. Pat. No. 7,011,196, hereby incorporated by reference herein, describes a hydraulic torque converter with a bridging clutch. 
         [0004]    In  FIG. 1 , a prior art torque converter  10  contains a cover  12 , an impeller  14 , a turbine  16 , and a bridging clutch  18 . Torque converter  10  is driven by an engine connected at hole  20 . Cover  12  has a front cover  22  and a back cover  24 , secured and sealed together, for example welded. Impeller  14  is rigidly attached to back cover  24 . Turbine  16  is rigidly attached to a turbine hub  26  with, for example, rivets  28 . Turbine hub  26  is non-rotatably attached to a shaft  30  with, for example, splines  32 . Shaft  30  may be the input shaft of a transmission, for example. 
         [0005]    Leaf springs have been known to connect the piston of bridging clutch  18  to a separate piece later welded to front cover  22 . Alternately, the piston, which can be in the form of a plate, splines to front cover  22  which can cause a rattle or noise complaint. Another method is to attach the piston to front cover  22  with leaf springs, typically positioned radially outside of friction surfaces. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a torque converter comprising a cover; and a bridging clutch for selective connection to the cover, the bridging clutch including a clutch plate fixed to the cover and having an inner radial surface and having a piston having an outer radial surface opposite the inner radial surface. 
         [0007]    The present invention also provides a method for assembling a torque converter comprising: providing a cover, connecting a clutch plate to the cover, the clutch plate having an inner radial surface, and pressing the piston into the inner radial surface. 
         [0008]    The present invention advantageously can simplify the connection of the piston and clutch plate to the cover. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]      FIG. 1  shows a prior art torque converter. 
           [0010]    One embodiment of the present invention is shown with respect to the drawings in which: 
           [0011]      FIG. 2  shows one embodiment of a torque converter according to the present invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0012]      FIG. 2  describes a torque converter  110  for connection to a shaft  130 , which may be the input shaft of a transmission for example, according to the present invention. Torque converter  110  has a front cover  122 , a bridging clutch  118 , and a cover flange  162 . An engine, attached to front cover  122 , rotates front cover  122  about center axis CA. Torque from front cover  122  is transmitted in one mode hydraulically using an impeller and turbine to a turbine hub non-rotatably connected to shaft  130 . Cover flange  162  is rigidly attached to front cover  122  and may be supported for example via a bearing on shaft  130  (shown schematically) located within cover flange  162 . 
         [0013]    Bridging clutch  118  includes a piston  134 , a clutch plate  164 , and a friction surface carrier  140 . Cover  122  can have a friction surface  174 , friction surface carrier  140  can have friction surfaces  176 ,  178  and clutch plate  164  can have a friction surface  180 . In an assembly step, annular friction surface carrier  140  can be placed against cover  122 , and then the pot-shaped clutch plate  164  can be attached to cover  122  with, for example, leaf springs  173 . Clutch plate  164  can be riveted to cover  122 , for example by rivets  175  through leaf springs  173 . Clutch plate  164  has an axially-extending inner radial surface  170 . 
         [0014]    Piston  134  is an annular piston plate and has a base  144  supported by cover flange  162  and sealed with a seal  166 . An axially-extending outer radial surface  168  of piston  134  is centered within surface  170  of clutch plate  164 . The region between surfaces  168  and  170  is sealed with a seal  172 . Because piston  134 , cover flange  162 , and clutch plate  164  have the same angular velocity, seals  166 ,  172  are rotationally static seals. By contrast, because cover flange  162  and shaft  130  do not necessarily have the same angular velocity, cover flange  162  seals to shaft  130  with a dynamic seal. 
         [0015]    Piston  134  and clutch plate  164  can move axially within torque converter  110  according to a controlled pressure difference between regions  148  and  150 . By sealing piston  134  and clutch plate  164  with seal  172 , the area of clutch plate  164  as well as piston  134  becomes the effective area in applying the clutch. 
         [0016]    Bridging clutch  118  can be engaged by introducing a higher pressure in region  150  than in region  148 . This pressure difference moves piston  134  and clutch plate  164  axially towards cover  122  to compress springs  173  and engage friction surfaces  174 ,  176 ,  178 ,  180 . Engagement of friction surfaces  174 ,  176 ,  178 ,  180  engages bridging clutch  118 . When bridging clutch  118  is engaged, torque from the engine is transmitted by torque converter  110  to shaft  130  through a direct mechanical connection. By contrast, when bridging clutch  118  is not engaged, torque from the engine is transmitted by torque converter  110  to shaft  130  through hydraulic fluid using an impeller and a turbine. 
         [0017]    Piston  134  advantageously can be assembled by pressing the piston within the already assembled pot-shaped clutch plate  164 . No further connections in this embodiment are necessary. 
         [0018]    Centering piston  134  between cover flange  162  and clutch plate  164  also avoids problems associated with using splines and welding. Assembly is simplified. 
         [0019]    Rivets  175  are radially positioned between cover flange  162  and axially-extending surface  168 . The radial locations of rivets  175 , an axially-extending outer surface  163  of cover flange  162 , and axially-extending surface  168  are R 1 , R 2 , and R 3 , respectively, in  FIG. 2 . 
         [0020]    By positioning rivets  175  at location R 3  radially inside friction surfaces  174 ,  176 ,  178 ,  180 , the radial location R 4  of friction surfaces  174 ,  176 ,  178 ,  180  can be maximized, thus advantageously maximizing friction surface area.