Patent Abstract:
A wet clutch ( 1 ) with at least one friction disk ( 8 ) that can be clamped by an axially displaceable piston ( 5 ) against an end disk ( 7 ). In order to provide a cost-effective and more silent design, the end disk is permanently attached at the housing. Several variants are proposed for the attachment of the end disk.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is filed under 35 U.S.C. §120 and §365(c) as a continuation of International Patent Application No. PCT/DE2009/001531 filed Oc. 29, 2009 which application claims priority from Germany Patent Application No. 10 2008 056 640.3 filed on Nov. 10, 2008 which applications are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a wet clutch with at least one friction disc that is loadable by a piston relative to an end disc. 
       BACKGROUND OF THE INVENTION 
       [0003]    Wet clutches are known e.g. from DE 10 2007 053 974 A1 as converter lockup clutches for hydrodynamic torque converters, as separate wet clutches, as startup clutches or as twin clutches for twin clutch transmissions. Thus plural friction discs associated with an input side and an output side of the wet clutch are stacked in an alternating manner to form a disc packet and are received torque-proof and axially moveable with limits on two radially offset disc supports as a function of their input side or output side association. Thus, an end disc is arranged on a disc support. An axial travel of the end disc is limited at a stop of the disc support. The disc packet is pressed or clamped against the end disc by an axially moveable pressure loadable piston for torque transfer through the wet clutch. By receiving the end disc on the disc support and axially supporting it at this location a particular configuration can cause noise, in particular when there is no load or in a load range of the drive unit with small to medium torque. Furthermore the deformation properties of the end disc that is not fixated axially can cause undesirable disadvantages on the load. Eventually the cost for an inner and an outer disc carrier is comparatively high. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    Thus, it is the object of the invention to provide a wet clutch which is cost-effective, low noise and suitable for transferring high torque. 
         [0005]    The object is achieved through a wet clutch with a housing driven by a drive unit and with at least one friction disc that is configured to be clamped against an end disc through a piston that is axially moveable through a pressure. The end disc is axially and radially fixed and received torque-proof at a housing. Through this attachment of the end disc at the housing a radially outer disc support can be omitted. Additionally, higher torques can be transferred through the diameter, thus achievable with the same number of friction discs due to the larger friction diameter of the friction discs. A smaller number of friction discs can be used for the same transferable torque. Where necessary the input side friction discs can also be engaged at accordingly provided circumferential profiles like inner teethings of the housing. Through omitting the outer disc support lower noise configurations can be proposed since e.g. the interior of the wet clutch can be configured in a more homogenous manner. 
         [0006]    Thus, it has proven particularly advantageous when the end disc is not welded, but received through form locking or friction locking Thus, the attachment of the end disc with the respect to the movement degrees of freedom of the non-connected end disc relative to the housing can be provided through different attachment methods. In particular, for movement degrees of freedom in axial direction and in circumferential direction the same or different friction locking or form locking methods can be used. 
         [0007]    For example, a torque transfer of the end disc, thus an attachment of the end disc in circumferential direction relative to the housing, can be provided through friction locking in that the end disc is radially clamped relative to the housing in that the end disc is pressed into the inner circumference of the housing or attached forming a plastic deformation of the housing and/or the end disc. Alternatively, form locking can be provided between the end disc and the housing in that the end disc is radially or axially cut into the housing. Furthermore, profiles that are complementary to one another like material recesses, recesses or threads like fine threads, standard threads or trapezoid threads can be provided. 
         [0008]    The axial fixation of the end disc can be provided e.g. in case of friction locking through impressing or forming a plastic connection or in case of form locking through a plastic connection. Furthermore, when forming the housing from two housing shells, one housing shell, e.g. the pump of a torque converter, can be used as an axial stop for the friction disc. 
         [0009]    In order to provide a plastic deformation between the end disc and the housing the end disc, the housing, e.g. one of the two housing shells, or both housing shells can be deformed plastically. 
         [0010]    In order to configure the connection furthermore, the end disc and the housing can be caulked together. Alternatively, the housing can be roller-burnished about the end disc. The end disc can be permanently inserted into the housing through a wobbling process. The housing can be deformed through forging or embossing, so that the end disc can be permanently received in the housing. In another advantageously configured embodiment, an end disc can be provided that is riveted together with the housing. In particular, for cost reasons and for maintaining tightness of the housing, seal buds can protrude from the housing at which the end disc is riveted together with the housing. 
         [0011]    A plastic deformation for attaching the end disc at the housing can thus be provided completely over the entire circumference and/or in sections by providing circular segments that are distributed over the circumference. A plastic deformation is provided at the circular segments. For example the end disc can be received through friction locking like e.g. through roller-burnishing over the entire circumference for torque-proof reception and can be caulked along the circumference in segments or partially for axial attachment to the housing. 
         [0012]    The end disc can have a planar, conical or dish shape. Thus, the dish-shaped end disc can be partially applied to the housing. In particular for stabilizing the end disc beads, embossings and/or ribs can be provided thereon. Furthermore, the end disc can include at least one material recess at least at one of its circumferences or radially there between. Material recesses of this type can be provided through holes, punching, teething and/or notching and can be used for better flow through of pressure medium for controlling the piston and/or cooling the friction discs, in particular their liners. 
         [0013]    Furthermore it has proven advantageous to vary the material thickness of the friction disc. Thus in particular material thicknesses can be advantageous that vary over the radius of the end disc. Thus e.g. a higher stiffness can be achieved for minimum material use. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0014]    The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which: 
           [0015]      FIG. 1  illustrates a wet clutch with an end disc with an axial stop and plastically generated friction locking in rotation direction; 
           [0016]      FIG. 2  illustrates a wet clutch with an end disc with an axial stop and teething in rotation direction; 
           [0017]      FIG. 3  illustrates a wet clutch with an end disc provided with holes; 
           [0018]      FIG. 4  illustrates a wet clutch with a riveted end disc; 
           [0019]      FIG. 5  illustrates a wet clutch with a notched end disc; 
           [0020]      FIG. 6  illustrates a wet clutch with a caulked end disc; and 
           [0021]      FIG. 7  illustrates a wet clutch with an end disc that is caulked in an alternative manner compared to the embodiment of the wet clutch of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]      FIG. 1  illustrates the upper half of the wet clutch  1  arranged about the rotation axis  2 . The wet clutch  1  is formed from an input component  3  and an output component  4 . The input component  3  includes the piston  5  connected torque-proof with the housing  6  that is moveable within limits relative to the housing. The input component  3  includes the end disc  7  permanently received at the housing. The output component  4  forms the friction disc  8  that is clampable between the piston  5  and the end disc  7 . The friction disc is connected torque-proof through the inner teething  9  with the input component  12  of the torsion vibration damper  11  through an outer teething  10  embossed in the input component  12 . 
         [0023]    The end disc  7  is received at the housing  6  in an axially fixated and torque-proof manner. Thus, the end disc is configured dish-shaped and axially fixed on one side through a radially inner radially extending portion  13  at a radially extended portion  15  with shoulders of the housing shell  14  of the housing  6 . In the other direction the end disc  7  is axially fixed at a stop  16  of the housing shell  17  that is radially reduced relative to the inner diameter of the housing shell  14 . The two housing shells  14 ,  15  are welded together during final assembly and form the housing  6  of the wet clutch  1 , wherein the housing shell  17  can simultaneously form the pump of the torque converter when using the wet clutch  1  as a converter lockup clutch. 
         [0024]    After installing the piston  5  and the friction disc  8  the end disc  7  is inserted torque-proof through a plastic deformation  18  of the inner surface of the housing shell  14  of the housing  6 . Thus, a fine profile  19  can be fabricated at the inner surface of the housing shell  14 . The fine profile has a smaller inner diameter than the outer diameter of the end disc  7 . When axially inserting the end disc  7  at the stop of the portion  15 , the fine profile  19  of the housing shell  14  is plastically deformed and a frictional engagement is formed, so that the end disc  7  is rotationally fixated and after completing the remaining inner portions of the housing  6  the housing shell  17  is axially fixated at the housing  6  through the stop  16 . 
         [0025]      FIG. 2  illustrates an embodiment of a similar wet clutch  1 A that is an alternative to the wet clutch  1  of  FIG. 1 . Differently from the wet clutch  FIG. 1  the end disc  7 A is received in a form locking manner at the housing  6 . Thus, the outer circumference of the end disc  7 A includes an axial teething  20  which is in engagement with a face teething  21  of the housing shell  17 . Thus, the face teething  21  simultaneously forms the stop for the end disc  7   a  in the direction of the torsion vibration damper  11 . In a direction of the piston  5  the radial portion  15  of the housing shell  14  forms an axial stop for the radially inner portion  13  of the dish shaped end disc  7   a.  The end disc  7   a  is thus inserted into the housing shell  14  and centered at the inner circumference of the housing shell  14 . The form locking to the housing shell  14  is thus configured when joining the two housing shells  14 ,  17 . 
         [0026]      FIG. 3  illustrates a wet clutch lb that is similar to the wet clutch  1  of  FIG. 1  with the difference that the end disc  7   b  includes at least a recess  22  like e.g. a punched out recess. Besides mass savings at the end disc  7   b  the recesses  22  facilitate an improved exchange of pressure medium for cooling the friction liners  23  of the friction disc  8 . Thus, a separation into the pressure chambers  25 ,  26  is provided for accordingly configured wet clutches or in a three channel torque converter, wherein the separation takes over the cooling and the activation of the wet clutch  1   b  (also of the remaining illustrated wet clutches). For closing the wet clutch  1   b  the pressure chamber  26  is loaded with a pressure medium with higher pressure than the pressure applied to the pressure chamber  25 . Thus the piston  5  moves axially and loads the friction disc  8  against the end disc  7 B so that a frictional engagement is formed between the two components and torque is transferred to the torsion vibration damper  11 . Additionally the pressure of the pressure cavity  24  is increased over the pressure of the pressure cavity  25  and a pressure medium flow is provided over the recess  22  and the friction liners  23  wherein the pressure medium flow cools the friction liners  23 . 
         [0027]      FIG. 4  illustrates an embodiment of a wet clutch  1   c  in which the end disc  7   c  is riveted radially outside the friction disc  8  at the radially aligned portion  15  of the housing shell  14  of the housing  6  and is thus attached torque proof or axially fixed and in a centered manner at the housing  6 . In the illustrated embodiment, the rivets  27  are formed from rivet buds which are pressed out of the housing shell  14 . In the following the only partially illustrated input component  12  of the non-illustrated torsion vibration damper and the disc support  28  with the outer teething for torque proof connection of the friction disc  8  are configured in two portions. 
         [0028]      FIG. 5  illustrates the wet clutch ld in which the end disc  7   d  in the housing  6  is fixed through material displacement of the end disc  7   d  in an axially fixated and torque-proof manner. An axial stop  29  is thus configured in the housing  6  for axially contacting the end disc  7   d.  A circumferential groove  30  can be provided at the housing  6  into which material of the end disc  7   d  in the form of an annular protrusion  31  is displaced into the annular groove  30  through axial force loading through one or plural rollers distributed over the circumference or through a pressure loaded chisel. Differently from the end discs  7 ,  7   a,    7   b  of  FIGS. 1 through 3  the end disc  7   d  is configured planar in the illustrated embodiment. 
         [0029]      FIGS. 6 and 7  illustrate wet clutches le and if in which the end discs  7   e,    7   f  that are configured planar are respectively caulked with the housing  6  in axial direction. The end discs  7   e,    7   f  thus include an outer profile like an outer teething  32 ,  32   a  which forms a form locking engagement with an inner profile that is provided in a complementary manner in the inner circumference of the housing  6  so that the end disc  7   e,    7   f  is received torque-proof in the housing  6 . After applying the end disc  7   e,    7   f  at the stop  29  of the housing  6  the end disc  7   e,    7   f  is caulked with the housing  6  for axial safety. Thus, caulking lugs  33  are formed through radially displacing material of the housing  6  in the wet clutch le of  FIG. 6 . The caulking lugs are distributed over the circumference. The caulking lugs  33   a  are formed in the wet clutch if of  FIG. 7  through an axial displacement of material of the housing  6 . As evident e.g. from the view of the end disc  7 F of  FIG. 7 , the outer teething  32   a  of the end discs can include relief openings  34  through which pressure medium balancing can be provided between the pressure cavities  24 ,  25  for cooling the friction disc  8 . In order to increase the torque that is transferrable through the connection of the end disc  7   f  and the housing  6 , the material displacements of the housing  6  can at least partially reach over the relief openings  34 . 
       REFERENCE NUMERALS AND DESIGNATIONS 
       [0030]      1  Wet clutch 
         [0031]      1   a  Wet clutch 
         [0032]      1   b  Wet clutch 
         [0033]      1   c  Wet clutch 
         [0034]      1   d  Wet clutch 
         [0035]      1   e  Wet clutch 
         [0036]      1   f  Wet clutch 
         [0037]      2  Rotation axis 
         [0038]      3  Input component 
         [0039]      4  Output component 
         [0040]      5  Piston 
         [0041]      6  Housing 
         [0042]      7  End disc 
         [0043]      7   a  End disc 
         [0044]      7   b  End disc 
         [0045]      7   c  End disc 
         [0046]      7   d  End disc 
         [0047]      7   e  End disc 
         [0048]      7   f  End disc 
         [0049]      8  Friction liner 
         [0050]      9  Inner teething 
         [0051]      10  Outer teething 
         [0052]      11  Torsion vibration damper 
         [0053]      12  Input component 
         [0054]      13  Portion 
         [0055]      14  Housing shell 
         [0056]      15  Portion 
         [0057]      16  Stop 
         [0058]      17  Housing shell 
         [0059]      18  Plastic deformation 
         [0060]      19  Fine profile 
         [0061]      20  Axial teething 
         [0062]      21  Face teething 
         [0063]      22  Recess 
         [0064]      23  Friction liner 
         [0065]      24  Pressure cavity 
         [0066]      25  Pressure cavity 
         [0067]      26  Pressure cavity 
         [0068]      27  Rivet 
         [0069]      28  Disc support 
         [0070]      29  Stop 
         [0071]      30  Circumferential groove 
         [0072]      31  lug 
         [0073]      32  Outer teething 
         [0074]      32   a  Outer teething 
         [0075]      33  Caulking lug 
         [0076]      33   a  Caulking lug 
         [0077]      34  Relief opening

Technology Classification (CPC): 5