Abstract:
A torque transmission device which can rotate an output shaft for transmitting the rotation from the operation side to he device and cannot rotate the output shaft form the device side. The torque transmission device excels in the durability with less wear-out by preventing the generation of the load concentration by the line contact of each component.

Description:
[0001]    This application is based on and claim priority under 35 U.S. C. § 119 with respect to Japanese Application NO. 2001-160471 filed on May 29, 2001, the entire content of which is incorporated herein by reference.  
         FIELD OF THE INVENTION  
         [0002]    This invention generally relates to a torque transmission device. More particularly, the present invention pertains to a torque transmission device which is applied as an operational force transmission mechanism of a window regulator and a height adjustment device of a vehicle seat, in which an output shaft can be rotated for transmitting the rotation from the operation side to the device and the output shaft cannot be rotated from the device side.  
         BACKGROUND OF THE INVENTION  
         [0003]    A known torque transmission device for achieving foregoing characteristics is disclosed in U.S. Pat. No. 5,460,253. The known torque transmission device according to the U.S. Pat. No. 5,460,253 includes an inside ring connected to a fixed member, an outside ring positioned keeping a clearance from the inside ring, two pairs of rollers positioned in the clearances between the outside ring and the inside ring, a spring positioned between the pair of rollers for increasing the distance between the rollers, a pawl portion inserted from a hole provided on a side wall of the outside ring for sandwiching the pair of rollers from the different side from the spring, an operation lever rotatably supported on a circumference of the inside ring, and a shaft fixed to the outside ring and positioned to be penetrated into a bore of the inside ring. The clearance between the inside ring and the outside ring includes a gradually narrowed portion. The spring provided between the pair of rollers pushes each roller towards the narrowed clearance. According to the torque transmission device with this construction, the large load is generated between the rollers and the inside ring and the outside ring by the wedge effect to obtain the large frictional force accompanied with the load. Thus, the relative rotation between the inside ring and the outside ring is checked strongly. When the torque transmission device with the foregoing construction is assembled to an application device for providing the rotational torque, a stress on the shaft of the torque transmission device is caused by a gear of the application device. The rotational torque is transmitted from the shaft to the outside ring, notwithstanding, the shaft is not rotated because the relative rotation between the outside ring, the roller, and the inside ring is strongly checked and the inside ring is connected to the fixed member.  
           [0004]    On the other hand, when the operational lever is operated, the pawl portion displaces the roller to be released from the condition sandwiched in the clearance between the inside ring and the outside ring against the biasing force of the spring. The operational lever also has a construction for rotating the shaft with lighter operational force by rotating the outside ring by the contact between the pawl portion and the hole on the outside ring side wall.  
           [0005]    According to the foregoing known torque transmission device with the construction for locking the outside ring and the inside ring by sandwiching the roller in the clearance between the outside ring and the inside ring, the respective rings and the roller are in line contact each other when the torque is transmitted from the outside ring to the inside ring via the roller. The large stress is generated because the load is concentrated on the contacted line portion. In addition, because the inside ring, the outside ring and the roller under operation contact each other at approximately the same position on every checking operations, the wear-out of the inside ring and the outside ring is increased.  
           [0006]    A need thus exists for a torque transmission device which does not cause the concentration of the load applied to the inside ring and the outside ring and achieves high durability.  
         SUMMARY OF THE INVENTION  
         [0007]    According to one aspect, A torque transmission device comprises an inside support member having a first contact surface portion positioned on an outer periphery of the inside support member, an outside support member having a second contact surface portion positioned on an inner periphery of the outside support member, a first holding portion in which a clearance between the first contact surface portion and the second contact surface portion is gradually decreased in one peripheral direction, a second holding portion in which a clearance between the first contact surface portion and the second contact surface portion is gradually decreased in the other peripheral direction, a pair of interposition members which is supported on the first holding portion and the second holding portion respectively, an elastic member positioned between the pair of interposition members for biasing each interposition member in a direction in which the each clearance of the first and the second holding portion is decreased, an operation member for moving one of the pair of interposition members in a direction for increasing the clearance of the first or the second holding portion against a biasing force of the elastic member.  
           [0008]    Each interposition member comprises a third contact surface portion being in surface contact with the first contact surface portion and a fourth contact surface portion being in surface contact with the second contact surface portion.  
           [0009]    According to another aspect, a torque transmission device comprises an inside support member having a first contact surface portion positioned on an outer periphery of the inside support member, an outside support member having a second contact surface portion positioned on an inner periphery of the outside support member, a first holding portion in which a clearance between the first contact surface portion and the second contact surface portion is gradually decreased in one peripheral direction, a second holding portion in which a clearance between the first contact surface portion and the second contact surface portion is gradually decreased in the other peripheral direction, a pair of interposition members which is supported on the first holding portion and the second holding portion respectively, an elastic member positioned between the pair of interposition members for biasing each interposition member to a direction in which the each clearances of the first holding portion and the second holding portion is,decreased, an operation member for moving, one of the pair of interposition members to a direction in which the clearance of the first or the second holding portion is increased against a biasing force of the elastic member, a gear formed on the inside support member for transmitting an operational force to an external device, a shaft inserted through the inside support member, the operation member, the outside support member, and an operation handle, for transmitting the operational force from the operational handle to the external device.  
           [0010]    Each interposition member comprises a third contact surface portion being in surface contact with the first contact surface portion and a fourth contact surface portion being in surface contact with the second contact surface portion.  
           [0011]    According to further aspect, a torque transmission device comprises an inside support member having a first contact surface portion positioned on an outer periphery of the inside support member, an outside support member having a second contact surface portion positioned on an inner periphery of the outside support member, a first inclined surface provided on the inside support member, the first inclined surface gradually increasing a height in one peripheral direction, a second inclined surface provided on the inside support member, the second inclined surface gradually increasing a height in the other peripheral direction, a pair of interposition members which are disposed on the first inclined surface and the second inclined surface, an elastic member positioned between the pair of interposition members for biasing each interposition member to a direction in which each clearances between the inside support member and the outside support member at the first and the second inclined surface is decreased, an operation member for moving one of the paired interposition members to a direction in which the clearance between the inside support member and the outside support member at the first and the second inclined surface is increased selectively against a biasing force of the elastic member, a gear formed on the inside support member for transmitting an operational force to an external device, a shaft inserted through the inside support member, the operation member, the outside support member, and an operation handle, for transmitting the operational force from the operational handle to the external device.  
           [0012]    Each interposition member comprises a third contact surface portion being in surface contact with the first contact surface portion and a fourth contact surface portion being in surface contact with the second contact surface portion. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0013]    The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered reference to the accompanying drawing figures in which like reference numerals designate like elements.  
         [0014]    [0014]FIG. 1 is an exploded perspective view of a torque transmission device according to an embodiment of the present invention.  
         [0015]    [0015]FIG. 2 is a plane view of the torque transmission device according to the embodiment of the present invention.  
         [0016]    [0016]FIG. 3 is a cross-sectional view of a central portion of the torque transmission device according to the embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    An embodiment of a torque transmission device according to the present invention will be explained referring to FIGS.  1 - 3  as follows.  
         [0018]    A torque transmission device  1  includes a housing  20 . The housing  20  is formed with a space portion  2  by a cylinder portion  25 , one end thereof is blocked up with a longitudinal wall surface portion  26 , and the other end thereof is open. A bearing hole  22  is formed on the central portion of the longitudinal wall surface portion  26 . A flange portion  24  outwardly extended in radial direction is formed on the open end side of the cylinder portion  25 . The flange portion  24  includes plural fitting holes  23  which are used for installing the torque transmission device  1  to an application device  80  (FIG. 3).  
         [0019]    An operation plate  30  is positioned at a bottom portion closest to the longitudinal wall portion  26  in the back of the space portion  2  of the hosing  20 . The operation plate  30  is formed with a plane plate in a circular shape whose diameter is slightly smaller than an internal diameter of the cylinder portion  25 . Four recess portions  32  with a predetermined width are provided on the periphery of the operation plate  30 . A hole  33  is formed on the central portion of the operation plate  30 . The hole  33  includes a pair of plane surfaces  33   a  which are opposed and in parallel each other.  
         [0020]    A shaft  10  which is provided with a stepped portion  12  having portions  12   a  with plane surfaces in parallel each other so that the stepped portion  12  may be engaged with the hole  33  to fix the shaft  10  in the hole  33 . The shaft  10  is inserted into the hole  33  and penetrating the bearing hole  22  of the housing  20 . The shaft  10  is formed with a large diameter shaft portion  11  for rotatably supporting one side of the shaft  10  to the housing  20 . The shaft  10  includes a projecting portion on one end portion formed with a serration  15  with plural slits extended in axial direction. The serration  15  projects to the outside of the housing  20  when the shaft  10  is assembled in the housing  20 . An operation handle  90  (shown in FIG. 3) for operating the shaft  10  is fixed on the serration  15  by engaging another serration formed on an internal surface of the operation handle  90 . A boss portion  13  contacting the stepped portion  12  is formed on the shaft  10 . A small diameter shaft portion  14  is formed on the other end portion of the shaft  10  opposite to the serration  15 .  
         [0021]    A disc shaped inside support member  50  is positioned on the portion closest to the open end side of the space portion  2  of the housing  20 . The external diameter of the inside support member  50  corresponds to the size which is fitted into the internal diameter surface  21  of the cylinder portion  25 , of the housing  20  and is rotatably supported. A gear  53  is integratedly formed on one side surface of the inside support member  50  in axial direction to be projected to the outside of the space portion  2 . The gear  53  is, for example, provided to be geared with an operational gear  70  of a seat height adjustment device  80  (shown in FIG. 3) for operating the seat height adjustment device  80 . A ring portion  58  is formed on the other side surface of the inside support member  50  to be projected in axial direction in the space portion  2 . The internal diameter of the ring portion  58  includes a shape for accommodating the boss portion  13  of the shaft  10 . As shown in FIG. 2, the outer profile of the ring portion  58  includes four inclined surfaces  51  symmetric with respect to the center of the ring portion  58 . The four inclined surfaces  51  are provided on the-top-right, top-left, bottom-right, and bottom-left of the ring portion  58  of FIG. 2. Two inclined surfaces  51 ,  51  on the right side of FIG. 2 make a pair of the inclined surfaces  51 ,  51  and the other two inclined surfaces  51 ,  51  on the left side of FIG. 2 make an another pair of inclined surfaces  51 ,  51 . The inclined surfaces  51 ,  51  of the pair are connected via a connecting portion  51   a  therebetween. The inclined surfaces  51 ,  51  have the largest clearance relative to the internal diameter surface  21  of the cylinder portion  25  of the housing  20  at the position of connecting portions  51   a.  Each inclined surface  51  shown on the top right and on the bottom left of FIG. 2 has a shape whose clearance relative to the internal diameter surface  21  is gradually reduced in the counterclockwise direction. The clearance of each inclined surface  51  shown on the top left and on the bottom right of FIG. 2 relative to the internal diameter surface  21  is gradually reduced in the clockwise direction. In other words, the height of each inclined surface  51  in radial direction is gradually increased in the counterclockwise direction regarding the inclined surfaces  51 ,  51  on the top right and the bottom Left of FIG. 2. And the height of each inclined surface  51  in radial direction is gradually increased in the clockwise direction regarding the inclined surfaces  51 ,  51  on the top left and bottom right of FIG. 2. Peripheral length of each inclined surface  51  corresponds to a sector of 50 degrees. As shown in FIG. 2, a stepped diameter portion  56  with arc shaped surface is formed on a position closer to the center of the ring portion  58  compared to the inclined surface  51  between each pair of inclined surfaces  51 ,  51  positioned on the right and left of FIG. 2. A shoulder portion  55  is formed on the boarder between the inclined surface  51  and the stepped diameter portion  56 .  
         [0022]    As shown in FIG. 2, four interposition members  40  are placed in a holding portion  51   b  formed between the internal diameter surface  21  of the cylinder portion  25  of the housing  20  and each inclined surface  51 . The interposition members  40  contact the inclined surfaces  51  for covering each pair of the inclined surfaces  51 . Each interposition member  40  includes an inside contact surface  44  contacting the corresponding inclined surface  51  within the range up to approximately 40 degrees. A projecting portion  42  is formed on one end portion of the interposition member  40  which is engageable with the shoulder portion  55 . Normally, the projecting portion  42  is positioned keeping a small clearance “d” from the shoulder portion  55 . The interposition member  40  contacts on the inclined surface  51  and contacts on the internal diameter surface  21  by an outside contact surface  45 . The interposition member  40  is tightly contacted on both of the inclined surface  51  and the internal diameter surface  21  simultaneously, because the interposition member  40  has a wedge shape whose width is gradually narrowed.  
         [0023]    As shown in FIG. 2, springs  60  for affecting of increasing the distance between the paired interposition members  40  are positioned between the paired interposition members  40  between the outer surface of the ring portion  58  and the internal diameter surface  21  of the cylinder portion  25 . The spring  60  is a W-shaped leaf spring, and is always pushing the interposition members  40  by contact portions  61  on the both sides of the spring  60  to the direction in which the clearance between the inclined surface  51  and the internal diameter surface  21  is decreased. The pushing force of the spring  60  generates the large pressing load on both of the ring potion  58  and the cylinder portion  25  by the wedge effect. Thus, the housing  20  and the ring portion  58  are strongly fixed via the interposition members  40  by the frictional force accompanied by the large pressing load.  
         [0024]    Projections  41  projecting to be respectively inserted into four recess portions  32  formed on the periphery of the operation plate  30  is formed in the approximately center of the interposition members  40 . The width of the projection  41  is narrower than the width of the recess portion  32 . The projection  41  is positioned to be opposing to an end surface of the recess portion  32  keeping a small clearance “e” on one side and leaving the large clearance on the other side. Each clearance “e” is positioned for the operation plate  30  to contact one side of the projection  41  for pushing the interposition member  40  to the direction in which the clearance between the inclined surface  51  and the internal diameter surface  21  is increased. When the operation plate  30  is rotated to either the clockwise direction or the counterclockwise direction of FIG. 2 more than the angle corresponding to the clearance “e”, the interposition member  40  is moved along the inclined surface  51  by the rotation of the operation plate  30 . Then the tight contact between the inclined surface  51  and the internal diameter surface  21  is released because the interposition member  40  is pushed to the direction in which the clearance between the inclined surface  51  and the internal diameter surface  21  is increased.  
         [0025]    As explained above, the operation handle  90  is connected to the operation plate  30  via the shaft  10 . When the operation handle  90  is rotated, the operation plate  30  and one of the interposition members  40  of the paired interposition members  40 ,  40  are contacted to be rotated. Thus, the tight contact of one of the interposition members  40  of the paired interposition members  40 ,  40  relative to the inclined surface  51  and the internal diameter surface  21  is released. When one of the paired interposition members  40 ,  40  is moved by the clearance “d”, the corresponding projection  42  provided on the interposition member  40  engages with the corresponding shoulder portion  55  of the ring portion  58  for rotating the ring potion  58  in the rotational direction of the operation handle  90 . By the rotation of the ring portion  58  relative to the housing  20 , the clearance between the inclined surface  51  and the internal diameter surface  21  which are sandwiching the other interposition member  40  of the paired interposition members  40 ,  40  which does not contact on the operation plate  30  increases. Thus, the tight contact of the other interposition member  40  of the paired interposition members  40 ,  40  relative to the inclined surface  51  and the internal diameter surface  21  is also released. Accordingly, the tight contact at all four positions is released. The gear  53  integratedly formed on the ring portion  58  can be rotated by the light rotational operation force by the operation handle  90 .  
         [0026]    The operation of the torque transmission device  1  with the forgoing construction applied to, for example, the seat height adjustment device  80 . The seat height adjustment device  80  includes the gear  70  for operating the mechanisms (not shown) which is geared with the gear  53  of the torque transmission device  1 . The occupant of the seat operates the operation handle  90  in order to achieve the appropriate seat height for rotating the gear  70  and for operating the mechanism of the seat height adjustment device  80 . Load generated in the mechanism due to such as vibration during the vehicle running is transmitted to the gear  53 , the appropriate height is maintained by the strong biding force between the interposition members  40  and the housing  20  and the ring portion  58  which construct the torque transmission device  1 .  
         [0027]    Although the seat height adjustment device  80  is applied in this embodiment, a window regulator device or other devices may be applied as the application device  80 .  
         [0028]    According to the torque transmission device of the embodiment of the present invention, because of the strong biding force of the inside support portion and the outside support portion relative to the interposition member which are contacted via surfaces, the generation of the large stress on the inside support portion, the outside support portion and the interposition member are prevented by avoiding the concentration of the load on the contact portions. Thus, the torque transmission device which excels in high durability with less wear-out is achieved. In addition, because the interposition member includes the integratedly formed engagement portion which is enagegable with the inside support portion, the number of the parts is reduced, thus the strong torque transmission device is achieved with less manufacturing cost.  
         [0029]    The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.