Patent Publication Number: US-2015087430-A1

Title: Series-to-parallel damper assembly including two flanges

Description:
This claims the benefit to U.S. Provisional Patent Application No. 61/881,796, filed on Sep. 24, 2013, which is hereby incorporated by reference herein. 
    
    
     The present disclosure relates generally to torque converters and more specifically to damper assemblies for torque converters. 
     BACKGROUND 
     U.S. Pat. No. 7,658,679 discloses a series-parallel damper assembly. 
     SUMMARY OF THE INVENTION 
     A damper assembly for a torque converter is provided. The damper assembly includes a first cover plate; a second cover plate, the first cover plate and second cover plate supporting springs therebetween; a first flange between the first cover plate and the second cover plate; and a second flange between the first cover plate and the second plate, the first flange and second flange being arranged with respect to the first and second cover plates and the springs such that the springs transition during operation of the damper assembly from initially operating in series to operating in parallel. 
     A torque converter is also provided. The torque converter includes the damper assembly and a turbine connected to the damper assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described below by reference to the following drawings, in which: 
         FIG. 1  shows cross-sectional side view of a torque converter for a motor vehicle drive train including a damper assembly in accordance with an embodiment of the present invention; 
         FIGS. 2   a  and  2   b  are exploded perspective views of the damper assembly; 
         FIGS. 3   a  to  3   d  each show two views illustrating the operation of the damper assembly; and 
         FIG. 4  shows a damper assembly in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure provides an embodiment of a multi-stage damper which, when compared to a conventional damper using the same springs and overall envelope, is capable of providing the same capacity while providing a multi-stage design with greater overall travel and reduced rates. Such conventional series to parallel dampers are more complex, expensive and space consuming. By adding a second flange to a first flange, the multi-stage damper creates two dampers within a single envelope, allowing the first and second flanges to create two to three primary spring stages, initially working in series and finally transitioning to parallel operation. 
       FIG. 1  shows cross-sectional side view of a torque converter  10  for a motor vehicle drive train including a damper assembly  12  in accordance with an embodiment of the present invention. Torque converter  10  includes a cover  14  including a front cover  16  for connecting to a crankshaft of an internal combustion engine and a rear cover  18  forming a shell  20  of an impeller  22 . Impeller shell  20  is nonrotatably fixed to a hub  24 . Torque converter  10  also includes a turbine  26  that is connected to damper assembly  12  and a lockup clutch  28  for rotationally connecting damper assembly  12  with front cover  16 . Lockup clutch  28  includes a piston  29  that is axially movable toward and away from front cover  16  to rotationally engage damper assembly  12  with and rotationally disengage damper assembly  12  from front cover  16 . Lockup clutch  28  is rotationally coupled to damper assembly  12 . More specifically, piston  29  of lockup clutch  28  is rotationally connected to a second flange  38  of damper assembly  12 . 
     Damper assembly  12  is disposed in an envelope or space  30  formed between turbine  26  and front cover  16 . Damper assembly  12  includes a first cover plate  32 , a second cover plate  34  connected to first cover plate  32  and also connected to turbine  26 , and a first flange  36  and a second flange  38  between cover plates  32 ,  34 . In this embodiment, cover plates  32 ,  34  are riveted together by rivets  35 . Damper assembly  12  includes two spring sets, each including a least one spring. In this embodiment, springs sets include a first spring set including two springs  44  and a second spring set including two springs  46 . Springs  44 ,  46  are held axially between cover plates  32 ,  34  at the same radial distance such that springs  44 ,  46  limit the rotation of first flange  36  and second flange  38  with respect to cover plates  32 ,  34  by circumferentially contacting circumference contact surfaces  66   a,    66   b,    67   a,    67   b  of flange  36  and contact surfaces  68   a ,  68   b,    69   a,    69   b  of flange  38  (see  FIGS. 2   a ,  2   b ,  3   a  to  3   d ). 
     First flange  36  includes a substantially flat plate portion  52  and a hub portion  54  protruding axially from plate portion  52 . Hub portion  54  is nonrotatably connected to a rotatable input shaft  56  of a transmission, which rotates radially inside of impeller hub  24  about axis A. Second flange  38  is positioned on hub portion  54  such that second flange  38  may move rotationally with respect to first flange  36 , as limited by springs  44 ,  46 . 
       FIGS. 2   a  and  2   b  are exploded perspectives view of damper assembly  12 . The only difference between  FIGS. 2   a  and  2   b  is that springs  44 ,  46  are shown in different places to fully illustrate damper assembly  12 , and hub portion  54  is disconnected from and below plate portion  52  of first flange  36 . As noted above, damper assembly  12  includes two spring sets including respective springs  44 ,  46 , which alternate circumferentially about axis A. Each cover plate  32 ,  34  includes four respective slots formed therein - cover plate  32  includes two slots  58 , each for receiving one of springs  44 , and two slots  59 , each for receiving one of springs  46 ; while cover plate  34  includes two slots  60 , each for receiving one of springs  44 , and two slots  61 , each for receiving one of springs  46 . Slots  58  are each defined in cover plate  32  by two respective circumferential contact surfaces  58   a,    58   b;  slots  59  are each defined in cover plate  32  by two respective circumferential contact surfaces  59   a,    59   b;  slots  60  are each defined in cover plate  34  by two respective circumferential contact surfaces  60   a,    60   b;  and slots  61  are each defined in cover plate  34  by two respective circumferential contact surfaces  61   a,    61   b.  Slots  58 ,  59 ,  60 ,  61  may come in and out of contact with corresponding ends  44   a,    44   b  of springs  44  and corresponding ends  46   a,    46   b  of springs  46  during operation of torque converter  10 , as further described below with respect to  FIGS. 3   a  to  3   d . In this embodiment, slots  58 ,  60  are all of the same length and slots  59 ,  61  are all of the same length. Slots  58 ,  60  may be a different length than or the same length as slots  59 ,  61 . 
     First flange  36  includes four slots—two slots  66  of a first length for receiving springs  46  and two slots  67  of a second length which is smaller than the first length for receiving springs  44 —and second flange  38  also includes four slots—two slots  68  of a third length for receiving springs  44  and two slots  69  of a fourth length smaller than the third length for receiving springs  46 . Each slot  66  includes two contact surfaces  66   a,    66   b  for contacting ends  46   a,    46   b,  respectively, of springs  46  and each slot  67  includes two contact surfaces  67   a,    67   b  for contacting ends  44   a,    44   b,  respectively, of springs  44 . Similarly, each slot  68  includes two contact surfaces  68   a,    68   b  for contacting ends  44   a ,  44   b,  respectively, of springs  44  and each slot  69  includes two contact surfaces  69   a,    69   b  for contacting ends  46   a,    46   b,  respectively, of springs  46 . Second flange  38  also includes four slots  70  radially outside of slots  68 ,  69 , through which rivets  35  connecting cover plates  32 ,  34  to each other pass. Slots  70  are of a length such that rivets  35  can slide circumferentially in slots  70  as second flange  38  rotates relative to cover plates  32 ,  34 . A radial outer surface of second flange  38  further includes indentations  72  therein for radially engaging piston  29 . The radial outer surface of second flange  38  extends radially outside of cover plates  32 ,  34 . In this embodiment, slots  67  are of the same length as slots  58 ,  60  and slots  69  are of the same length as slots  59 ,  61 . Slots  66  may be a different length than or the same length as slots  68 . 
       FIGS. 3   a  to  3   d  each show two views illustrating the operation of damper assembly  12 . The view of the left is a plan view (springs  44 ,  46  are omitted, but are identified by their reference numbers  44 ,  46  and their effect is taken into consideration) of flanges  36 ,  38  and first cover plate  32  (both cover plates  32 ,  34  have the same alignment as each other throughout  FIGS. 3   a  to  3   d ; accordingly, all discussion below of plate  32  also applies to plate  34 ) and the view on right is a schematic view illustrating movement and compression of one of springs  44  and one of springs  46  in relation to cover plates  32 ,  34  and flanges  36 ,  38 . 
       FIG. 3   a  shows damper assembly  12  in a 0° windup condition. In this condition, first ends  44   a  and second ends  44   b  of springs  44  are in contact with both contact surfaces  58   a,    58   b  of both slots  58  of cover plate  32  (and both contact surfaces  60   a,    60   b  of both slots  60  of cover plate  34 ); first ends  44   a  and second ends  44   b  of springs  44  are in contact with both of the contact surfaces  67   a,    67   b  of both slots  67  in first flange  36 ; and first ends  44   a  and second ends  44   b  of springs  44  are spaced away from both of contact surfaces  68   a,    68   b  of slots  68  in second flange  38 . Also, first ends  46   a  and second ends  46   b  of springs  46  are in contact with both contact surfaces  59   a,    59   b  of both slots  59  of cover plate  32  (and both contact surfaces  61   a,    61   b  of both slots  61  of cover plate  34 ); first ends  46   a  and second ends  46   b  of springs  46  are in contact with both of the contact surfaces  69   a,    69   b  of slots  69  in second flange  38 ; and first ends  46   a  and second ends  46   b  of springs  46  are spaced away from both of contact surfaces  66   a,    66   b  of slots  66  in first flange  36 . Accordingly, with respect to springs  44 , in the plan view show in  FIG. 3   a , contact surfaces  67   a,    67   b  of slots  67  are coincident with contact surfaces  58   a,    58   b  of slots  58  and, because slots  68  are longer than slots  58 ,  67 , contact surfaces  68   a,    68   b  of slots  68  are positioned circumferentially outside of contact surfaces  67   a,    67   b,  respectively, of slots  67  and circumferentially outside of contact surfaces  58   a,    58   b,  respectively, of slots  58 . Also, with respect to springs  46 , in the plan view show in  FIG. 3   a , contact surfaces  69   a,    69   b  of slots  69  are coincident with contact surfaces  59   a,    59   b  of slots  59  and, because slots  66  are longer than slots  59 ,  69 , contact surfaces  66   a,    66   b  of slots  66  are positioned circumferentially outside of contact surfaces  69   a,    69   b,  respectively, of slots  69  and circumferentially outside of contact surfaces  59   a,    59   b,  respectively, of slots  59 . 
       FIG. 3   b  shows damper assembly  12  at the end of a first windup stage. In the first windup stage, which occurs between the views of  FIGS. 3   a  and  3   b , second flange  38  is rotated clockwise with respect to first flange  36  and cover plate  32  in the plan view shown. During the first windup stage, springs  44  work in series with springs  46  at a reduced spring rate until one of springs  44 ,  46  comes into contact with both flanges  36 ,  38 . At the end of the first windup stage, each surface  68   a  of slots  68  in second flange  38  contact the first end  44   a  of one of springs  44 . The rotation of second flange  38  with respect to first flange  36  and cover plate  32  has also caused each contact surface  69   a  of slots  69  in second flange  38  to move springs  46  such that second end  46   b  of each spring  46  is closer to corresponding contact surface  66   b  of slots  66 . Additionally, during the first windup stage, the rotation of second flange  38  with respect to cover plate  32  has caused contact surfaces  69   a  of slots  69  to move ends  46   a  of springs  46  out of contact with the corresponding contact surfaces  59   a  of slots  59  in cover plate  32 . Accordingly, with respect to springs  44 , in the plan view show in  FIG. 3   b , contact surfaces  58   a,    68   a  of respective slots  58 ,  67  both contact end  44   a  of spring  44  and are coincident and  67   a  is spaced away from end  44   a  of spring, while only contact surface  67   b  contacts end  44   b  of spring  44 , contact surface  58   b  is spaced from end  44   b  of spring  44  and contact surface  68   b  is spaced further away from end  44   b  of spring  44  than contact surface  58   b.  Also, with respect to springs  46 , in the plan view show in  FIG. 3   b , only contact surface  69   a  contacts end  46   a  of spring  46 , contact surface  59   a  is spaced from end  46   a  of spring  46  and contact surface  66   a  is spaced further away from end  46   a  of spring  46  than contact surface  59   a,  while only contact surface  59   b  contacts end  46   b  of spring  46 , contact surface  66   b  is spaced from end  46   b  of spring  46  and contact surface  69   b  is spaced further away from end  46   b  of spring  46  further than contact surface  66   b.    
       FIG. 3   c  shows damper assembly  12  at the end of a second windup stage. In the second windup stage, which occurs between the views of  FIGS. 3   b  and  3   c , second flange  38  is rotated further clockwise with respect to first flange  36  and cover plate  32  in the plan view shown. The second windup stage is the equivalent to the second windup stage of a conventional series damper assembly. This stage only cycles springs  44 , via compression by both flanges  36 ,  38 , while springs  46  remains clamped between cover plates  32 ,  34  and flange  38 . This continues until the total damper travel is equal to the distance between contact surface  68   a  of slot  68  and end  44   a  of spring  44  a a +the distance between contact surface  66   b  of slot  66  and end  46   b  of spring  46  a b  (see  FIG. 3   a ). It should be noted that if the force required to cycle springs  44  by a a  is equal to the force required to cycle springs  46  by a b , then the second windup stage is skipped. During the second windup stage, the rotational movement of second flange  38  with respect to first flange  36  and cover plate  32  has caused second flange  38  to compress springs  44 , due to the decrease in circumferential distance between surface  68   a  of each slot  68  and contact surface  67   b  of each slot  67 . At the end of the second windup stage, the end  46   b  of each spring  46  has contacted surface  66   b  of the corresponding slot  66 . Accordingly, with respect to springs  44 , in the plan view show in  FIG. 3   c , contact surfaces  68   a,    58   a  of respective slots  68 ,  58  still contact end  44   a  of spring  44  and are coincident and contact surface  67   a  of slot  67  is spaced away from end  44   a  of spring  44 , while only contact surface  67   b  contacts end  44   b  of spring  44 , contact surface  58   b  is spaced from end  44   b  of spring  44  and contact surface  68   b  is spaced further away from end  44   b  of spring  44  than contact surface  58   b.  Also, with respect to springs  46 , in the plan view show in  FIG. 3   c , contact surface  69   a  contacts end  46   a  of spring  46 , contact surface  59   a  is spaced from end  46   a  of spring  46  and contact surface  66   a  is spaced further away from end  46   a  of spring  46  than contact surface  59   a,  while contact surfaces  59   b,    66   b  contact end  46   b  of spring  46  and are coincident with each other and contact surface  69   b  is spaced away from end  46   b  of spring  46 . 
       FIG. 3   d  shows damper assembly  12  at the end of a third windup stage. In the third windup stage, which occurs between the views of  FIGS. 3   c  and  3   d , second flange  38  is rotated further clockwise with respect to first flange  36  and cover plate  32  in the plan view shown. In the third windup stage, the damper reaches the travel of a a +a b  and the torque is calculated both in series and in parallel. The difference between the torque in series and the torque in parallel determines the force/torque required to transition into the third windup stage. During the third windup stage, no force/torque is transmitted through cover plates  32 ,  34 , and springs  44 ,  46  instead contact directly from flange  36  to flange  38  in parallel arrangement. 
     During the third windup stage, the rotational movement of second flange  38  with respect to first flange  36  and cover plate  32  has caused second flange  38  to further compress springs  44 , due to a further decrease in circumferential distance between surface  68   a  of each slot  68  and contact surface  67   b  of each slot  67 . The rotational movement of second flange  38  with respect to first flange  36  and cover plate  32  during the third windup stage has also caused second flange  38  to compress springs  46 , due to the decrease in circumferential distance between surface  69   a  of each slot  69  and contact surface  66   b  of each slot  66 . Additionally, during the third windup stage, the rotation of second flange  38  with respect to cover plate  32  has caused contact surfaces  68   a  of slots  68  to move ends  44   a  of springs  44  out of contact with the corresponding contact surface  58   a  of cover plate  32 . Accordingly, with respect to springs  44 , in the plan view show in  FIG. 3   d , only contact surface  68   a  contacts end  44   a  of spring  44 , contact surface  58   a  is spaced from end  44   a  of spring  44  and contact surface  67   a  is spaced further away from end  44   a  of spring  44  than contact surface  58   a,  while only contact surface  67   b  contacts end  44   b  of spring  44 , contact surface  58   b  is spaced from end  44   b  of spring  44  and contact surface  68   b  is spaced further away from end  44   b  of spring  44  than contact surface  58   b . Also, with respect to springs  46 , in the plan view show in  FIG. 3   d , only contact surface  69   a  contacts end  46   a  of spring  46 , contact surface  59   a  is spaced from end  46   a  of spring  46  and contact surface  66   a  is spaced further away from end  46   a  of spring  46  than contact surface  59   a,  while only contact surface  66   b  contacts end  46   b  of spring  46 , contact surface  59   b  is spaced from end  46   b  of spring  46  and contact surface  69   b  is spaced further away from end  46   b  of spring  46  than contact surface  59   b.    
       FIG. 4  shows a damper assembly  112  in accordance with another embodiment of the present invention. Damper  112  is formed in substantially the same manner as damper assembly  112 , except that springs  44 ,  46  are used in series with another set of arc springs  140  and flange  38  is replaced by a flange  138  having a spring retainer  142  formed at a radial outer end thereof. Spring retainer  142  retains arc springs  140 . A drive portion  150  of a lock up clutch circumferentially engages springs  140 . When this configuration is used the preload stage can be eliminated and another useful stage can be added to the damper. In one preferred embodiment, the capacity of the arc springs  140  shown in this design have a capacity equal to the torque required to enter the final stage of the base damper formed by springs  44 ,  46 . 
     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.