Abstract:
A method of forming a damper assembly for a motor vehicle drive train is provided. The method includes providing a damper flange including a pocket at an inner circumferential surface thereof and cutting an outer circumferential surface of a damper hub using the inner circumferential surface of the damper flange. The cutting results in a displaced damper hub material of the outer circumferential surface of the damper hub being displaced into the pocket. A damper assembly also provided that includes a damper flange including a pocket at an inner circumferential surface thereof and a damper hub including an outer circumferential surface fixed to the inner circumferential surface of damper flange. The outer circumferential surface of the damper hub includes a displaced damper hub material extending radially into the pocket.

Description:
[0001]    This claims the benefit to U.S. Provisional Patent Application No. 62/029,336 filed on Jul. 25, 2014, which is hereby incorporated by reference herein. 
         [0002]    The present disclosure relates generally to damper assemblies and more specifically to methods for fixing damper flanges to damper hubs. 
     
    
     BACKGROUND 
       [0003]      FIGS. 1   a  to  1   c  show a conventional method of forming a damper assembly  10 , specifically forming a flange-hub sub-assembly of damper assembly  10  formed by staking a damper flange  11  onto a damper hub  12 . Damper hub  12  is formed of a forging material and damper flange  11  is formed of a case hardened stamped flange for forging damper hub  12 . As damper flange  11  is pressed onto damper  12 , an inner circumferential splined surface  14  of damper flange  11  spline cuts an outer circumferential surface  16 , displacing material  18  (i.e., creating chips), of outer circumferential surface  16  of damper hub  12 . Damper hub  12  is provided with a chip pocket  20  at outer circumferential surface  16  to receive displaced material  18 . Following the storage of displaced material  18  in pocket  20 , damper hub  12  is staked or coined to fix damper flange  11  axially on damper hub  12 . 
         [0004]      FIG. 1   d  shows a damper sub-assembly  80  including a damper flange  82  and a damper hub  84  integrally formed together in a one-piece design that typically requires more processing (machining and stamping) than damper assembly  10  and is typically more costly than the hub design  10 . 
       SUMMARY OF THE INVENTION 
       [0005]    A method of forming a damper assembly for a motor vehicle drive train is provided. The method includes providing a damper flange including a pocket at an inner circumferential surface thereof and cutting an outer circumferential surface of a damper hub using the inner circumferential surface of the damper flange. The cutting results in a displaced damper hub material of the outer circumferential surface of the damper hub being displaced into the pocket. 
         [0006]    A damper assembly for a motor vehicle drive train is also provided. The damper assembly includes a damper flange including a pocket at an inner circumferential surface thereof and a damper hub including an outer circumferential surface fixed to the inner circumferential surface of damper flange. The outer circumferential surface of the damper hub includes a displaced damper hub material extending circumferentially into the pocket. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention is described below by reference to the following drawings, in which: 
           [0008]      FIGS. 1   a  to  1   c  show views of a conventional method of forming a damper assembly by staking a damper flange onto a damper hub; 
           [0009]      FIG. 1   d  shows a cross-sectional side view of a conventional damper sub-assembly; 
           [0010]      FIG. 2   a  shows a partial cross-sectional side view of an inner circumferential surface of the conventional damper flange and  FIG. 2   b  shows a partial cross-sectional side view of the conventional damper hub shown in  FIGS. 1   a  to  1   c;    
           [0011]      FIG. 3   a  shows a partial cross-sectional side view of a damper flange and  FIG. 3   b  shows a partial cross-sectional side view of a damper hub in accordance with an embodiment of the present invention; 
           [0012]      FIG. 4  shows a partial cross-sectional side view illustrating further details of the method of forming the damper assembly shown in  FIGS. 1   a  to  1   c;    
           [0013]      FIG. 5  shows a partial cross-sectional side view of a method of forming a damper assembly in accordance with an embodiment of the present invention; 
           [0014]      FIG. 6  shows a partial cross-sectional side view of further details of damper assembly shown in  FIGS. 1   a  to  1   c  and  4 ; and 
           [0015]      FIG. 7  shows a partial cross-sectional side view of further details of the damper assembly shown in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]      FIG. 2   a  shows a partial cross-sectional side view of conventional damper flange  11  and  FIG. 2   b  shows a partial cross-sectional side view of conventional damper hub  12  described in  FIGS. 1   a  to  1   c . Inner circumferential splined surface  14  of damper flange  11  has a constant radius as viewed side cross-sectionally, because as noted above, chip pocket  20  is provided on damper hub  12 . Damper hub  12  is provided with pocket  20  on outer circumferential surface  16  for receiving chips when damper flange  11  is connected to damper hub  12 , as discussed below with respect to  FIG. 4 . 
         [0017]      FIG. 3   a  shows a partial cross-sectional side view of a damper flange  111  and  FIG. 3   b  shows a partial cross-sectional side view of a damper hub  112  in accordance with an embodiment of the present invention. Damper flange  111  includes an inner circumferential surface  115  having a stepped inner radius as viewed side cross-sectionally —to provide a pocket  120  for receiving material displaced by using damper flange  111  to spline cut a damper hub  112  ( FIG. 5 ). Pocket  120  may be formed by machining a radially and circumferentially extending groove into inner circumferential surface  115 . Inner circumferential surface  115  of damper flange  111  includes a first section  122 , which is splined, for contacting an outer circumferential surface  116  of damper hub  112  and a second section  126 , which is smooth and does not includes splines, radially offset from first section  122 . Second section  126  defines an outer radius of pocket  120  and connects with a first axial surface  144  of damper flange  111 . As a result of pocket  120 , first axial surface  144  of damper flange has a shorter radial length than a second axial surface  145  of damper flange  111  opposite of first axial surface  144 . First section  122  of inner circumferential surface  115  connects with second axial surface  145 . Damper flange  111  also includes a radially extending section  128  connecting first section  122  and second section  126  of inner circumferential surface  114 . In this embodiment, first and second sections  122 ,  126  extend parallel to each other and to a center axis of damper flange  111 , which damper flange  111  rotates about during operation of damper assembly  110 , and radially extending section  128  extends perpendicular to the center axis of damper flange  111 . Because damper flange  111  is provided with pocket  120  for receiving chips when damper flange  111  is connected to damper hub  112 , as discussed below with respect to  FIG. 5 , damper hub  112  does not include a pocket for receiving chips on outer circumferential surface  116 . 
         [0018]      FIG. 4  shows further details of the method of forming damper assembly  10  shown in  FIGS. 1   a  to  1   c , specifically forming a flange-hub sub-assembly of damper assembly  10 . As noted above, damper hub  12  is provided with a pocket  20  on outer circumferential surface  16 . Damper flange  11  is axially pressed onto outer circumferential surface  16  of damper hub  12  with a force F 1  such that damper flange  11 , by inner circumferential splined surface  14 , cuts splines into outer circumferential surface  16 . An axial surface of pocket  20  acts as a backstop for damper flange  11  during the pressing and displaced material  18  of damper hub  12  is displaced into pocket  20 . After damper flange  11  is pressed onto damper hub  12 , staking tooling, in the form of a staking section  30  and a support section  32 , is used to stake damper hub  12  to fix damper flange  11  axially in place on damper hub  12 . Damper hub  12  is held against support section  32  such that support section  32  contacts a stop surface  34  of damper hub  12  adjacent to pocket  20 . Staking section  30 , on the opposite side of damper hub  12  as support section  32 , is then pressed against damper hub  12  with a force F 2  to displace further material of outer circumferential surface  14  to form a radially extending lip  36 . After the staking, damper flange  11  is axially fixed on damper hub  12  and sandwiched between the axial surface of pocket  20  and radially extending lip  36 . 
         [0019]      FIG. 5  shows a method of forming a damper assembly  110  in accordance with an embodiment of the present invention, specifically forming a flange-hub sub-assembly of damper assembly  110 . Damper hub  112  is formed of a forging material and damper flange  111  is formed of a case hardened stamped flange for forging damper hub  112 . As damper flange  111  is pressed onto damper  112 , an inner circumferential splined surface  114  of damper flange  111  spline cuts an outer circumferential surface  116 , axially and radially displacing material  118  (i.e., creating chips) of an outer circumferential surface  116  of damper hub  114 . 
         [0020]    As noted above, damper flange  111  includes an inner circumferential surface  115  having a stepped inner radius as viewed side cross-sectionally—to provide a pocket  120  for receiving material displaced by using damper flange  111  to spline cut damper hub  112 . Damper flange  111  is axially pressed onto outer circumferential surface  116  of damper hub  112  with a force F 3  such that damper flange  111 , by inner circumferential splined surface  114 , cuts splines into an outer circumferential surface  116  of damper hub  112 . Before flange  111  is pressed onto hub  112 , first axial support surface  134  of support section  132  of a staking tooling contacts an axial outermost edge  138  of damper hub  112 . Then, damper flange  111  is axially pressed onto outer circumferential surface  116  of damper hub  112  with force F 3  to spline cut damper hub  111  and displace material  118 . After flange  111  has been pressed onto hub  112 , a second axial support surface  140  is axially spaced from first axial surface  144  of damper flange  111  by a distance X 1 . A third axial surface  142  of support section  132  acts as a backstop for a displaced material  118  of damper hub  112 , which is formed by the cutting of outer circumferential surface  116  of damper hub  112 . Third axial surface  142  is positioned inside pocket  120  at the end of the spline cutting and third axial surface  142  is axially offset from first axial surface  144  of damper flange by a distance X 2 . The formation of displaced material  118  and the contact between displaced material  118  and third axial surface  142  axially spaces second axial support surface  140  from first axial surface  144  of damper flange  111  by distance X 1 . Accordingly, support section  132  is formed such that axial surface  142  protrudes axially from support surface  140  by a distance equal to X 1 +X 2 , ensuring that displaced material  118  is always held away from the plane of axial surface  144 . 
         [0021]    After damper flange  111  is pressed onto damper hub  112 , staking tooling, in the form of a staking section  130  and support section  132 , is used to stake damper hub  112  to fix damper flange  111  axially in place on damper hub  112 . Support section  132  contacts the displaced damper hub material  118  at a first axial side first axial side of damper flange  111  including pocket  120  and staking section  130  coins damper hub  112  against a second axial side of damper flange  111  opposite the first axial side to form a coined damper hub section and a radially extending lip  136 . Damper hub  112  is held against support section  132  such that support surface  138  contacts axial outermost edge  138  of damper hub  112  and support surface  142  contacts displaced material  118 . Staking section  130 , on the opposite side of damper hub  112  as support section  132 , is pressed against damper hub  112  with a force F 4  to displace further material of outer circumferential surface  114  to form radially extending lip  136 , which contacts second axial surface  145  of damper flange  111 . After the staking, damper flange  111  is axially fixed on damper hub  112  and sandwiched between and contacting the displaced material  118  and radially extending lip  136 . The staking may cause axial surface  140  of support section  132  to contact axial surface  144  of flange  111 . 
         [0022]      FIG. 6  shows further details of damper assembly  10  shown in  FIGS. 1   a  to  1   c  and  4 . In addition to damper flange  11  and damper hub  12 , damper assembly  10  includes a first cover plate  50  contacting damper hub  12  adjacent to pocket  20  on a first axial side of damper flange  11  and a second cover plate  52 , which is fixed to cover plate  50  by fasteners  54 , on a second axial side of damper flange  11  opposite the first axial side. Cover plates  50 ,  52  support damping elements, for example springs, for driving flange  11 . A clutch disc  60  including friction material  62  on both sides thereof is connected to second over plate  52 . 
         [0023]      FIG. 7  shows further details of damper assembly  110  shown in  FIG. 5 . In addition to damper flange  111  and damper hub  112 , damper assembly  110  includes a first cover plate  150  contacting damper hub  112  adjacent to pocket  120  on a first axial side of damper flange  111  and a second cover plate  152 , which is fixed to cover plate  150  by fasteners  154 , on a second axial side of damper flange  111  opposite the first axial side. Cover plates  150 ,  152  support damping elements, for example springs, for driving flange  111 . A clutch disc  160  including friction material  162  on both sides thereof is connected to damper flange  111  via second cover plate  152 . A comparison of the damper assembly  110  of  FIG. 7  with the damper assembly of  FIG. 6  illustrates that damper assembly  110  advantageously takes up less axial space than damper assembly  10 . Damper assembly  110  thus has a more preferred installation boundary  170  than an installation boundary  70  of damper assembly  10 . 
         [0024]    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.