Patent Publication Number: US-7900529-B2

Title: Startup torque transmitting mechanism of an internal combustion engine

Description:
FIELD OF THE INVENTION 
     The invention relates to a startup torque transmitting mechanism for an internal combustion engine, which, by means of a one-way clutch, both transmits torque generated by a starter motor to a crankshaft side in one direction and prevents the transmission of torque in the other direction. 
     BACKGROUND OF THE INVENTION 
     In an internal combustion engine for a vehicle or the like, when a ring gear is provided for transmitting torque from a starter motor to a crankshaft, that ring gear is usually formed on an outer peripheral portion of a flywheel. Also, when a torque converter is provided, the ring gear may be formed on an outer peripheral portion of a drive plate which is fixed to a cover of the torque converter and transmits the rotation of the crankshaft. 
     Japanese Patent Application Publication No. JP-A-2000-274337, for example, discloses one such startup torque transmitting mechanism of an internal combustion engine, in which a one-way clutch is interposed between a ring gear and a flywheel so that a pinion gear on the starter motor side can be in constant mesh with the ring gear. Accordingly, the torque of the ring gear when the ring gear is rotated by the starter motor is transmitted to the crankshaft via the one-way clutch and the flywheel. When the crankshaft rotates from the output of the internal combustion engine, the one-way clutch releases so that torque from the crankshaft is not transmitted to the ring gear side. 
     In an internal combustion engine provided with a torque converter, it is possible to connect the ring gear to a drive plate, which transmits torque from the crankshaft to a cover of the torque converter, via the one-way clutch instead of connecting the ring gear to the flywheel. If the one-way clutch can be arranged on the drive plate in this way, torque from the ring gear that is rotated by the starter motor can be transmitted to the crankshaft via the drive plate while the ring gear is in constant mesh with the starter motor side, just as when a flywheel is used. 
     However, when employing a structure which transmits torque from the ring gear to a flywheel or a drive plate via a one-way clutch as described above, impact noise produced at the moment the one-way clutch engages immediately after the starter motor starts to be driven is directly transmitted to the flywheel or the drive plate. Therefore, noise may result from noise radiation from the flywheel or noise radiation from the drive plate itself or from the cover of the torque converter that is connected to the drive plate. 
     It is thus an object of the invention to reduce noise produced during engagement of a one-way clutch in a startup torque transmitting mechanism of an internal combustion engine which employs a one-way clutch. 
     DISCLOSURE OF THE INVENTION 
     In order to achieve the foregoing object, this invention thus provides a startup torque transmitting mechanism of an internal combustion engine, which, by means of a one-way clutch, both transmits torque generated by a starter motor to a crankshaft side in one direction and prevents the transmission of torque in the other direction, and which includes a race connecting member which is provided separately from a flywheel or a drive plate, is mounted to the crankshaft side, not via the flywheel or the drive plate, so as to rotate in conjunction with a crankshaft, and is connected to one race of the one-way clutch; and a ring gear which rotates upon receiving torque from the starter motor and is connected to another race of the one-way clutch. 
     As described above, the race connecting member to which torque generated by the starter motor is transmitted from the ring gear via the one-way clutch is provided separately from the flywheel or the drive plate, and is mounted to the crankshaft not via the flywheel or the drive plate. 
     Therefore, impact noise produced when the one-way clutch engages is not directly transmitted to the flywheel or the drive plate. As a result, it is possible to suppress noise radiation from the flywheel or the drive plate itself, or from a cover of the torque converter which is connected to the drive plate, which in turn enables noise to be reduced. 
     Furthermore, the fact that the race connecting member is separate from the flywheel or the drive plate also enables the following additional effects to be achieved. That is, regardless of the shape of the flywheel or the shape of the drive plate, or regardless of the type of transmission used, i.e., regardless of whether a manual transmission which uses a flywheel or an automatic transmission which uses a torque converter is used, component parts can be common by structuring the startup torque transmitting mechanism of an internal combustion engine as a common startup torque transmitting mechanism of an internal combustion engine. 
     The ring gear may also be rotatably supported by the crankshaft via a bearing. 
     Because the ring gear is rotatably supported by the crankshaft in this manner, impact noise produced by the one-way clutch engaging is not directly transmitted to the flywheel or the drive plate from the ring gear side either. Accordingly, noise radiation from the flywheel or the drive plate itself, or from a cover of the torque converter, can be suppressed, making it possible to reduce noise when the one-way clutch engages. 
     The one race of the one-way clutch may be an outer race and the other race of the one-way clutch may be an inner race, the race connecting member may be connected to the outer race of the one-way clutch, and the ring gear may be connected to the inner race of the one-way clutch. 
     In this way, the race connecting member is connected to the outer race of the one-way clutch and the ring gear is connected to the inner race. As a result, the one-way clutch and the mechanism such as the bearing which is between the ring gear and the crankshaft can be completely covered by the connecting body of the race connecting member and the outer race when viewed from one direction. Thus, because the one-way clutch and the bearing and the like which require an oil seal are able to be completely covered in this way, good sealability of the startup torque transmitting mechanism of an internal combustion engine can be easily realized. 
     The race connecting member may also be arranged on the opposite side of the ring gear from an internal combustion engine main body. 
     Having the ring gear on the internal combustion engine main body side and the race connecting member on the side of the ring gear opposite the internal combustion engine main body in this way makes it possible to completely cover the one-way clutch and the bearing and the like from outside of the internal combustion engine, and in particular, from the transmission side, by the race connecting member and the outer race. As a result, good sealability of the startup torque transmitting mechanism of an internal combustion engine with respect to the outside of the internal combustion engine can be easily realized. In addition, the startup torque transmitting mechanism of an internal combustion engine can be sealed so that oil will not leak out when the startup torque transmitting mechanism is completely separated from the transmission side. Accordingly, oil that is used to lubricate the internal combustion engine can also be used to lubricate the startup torque transmitting mechanism of an internal combustion engine. 
     A first oil seal member may be arranged in a gap between the outer race of the one-way clutch and the ring gear, and a second oil seal member may be arranged in a gap between the ring gear and an internal combustion engine main body side member. 
     Arranging the first oil seal member and the second oil seal member in this way makes it possible to seal the inside of the startup torque transmitting mechanism of an internal combustion engine against oil leaking out both easily and with good sealability. As a result, oil that is used to lubricate the internal combustion engine can also be used to lubricate the startup torque transmitting mechanism of an internal combustion engine. 
     The race connecting member may be fastened to a crankshaft end surface while being sandwiched between the crankshaft end surface and the drive plate, and a first load relieving portion which prevents deformation of the race connecting member that occurs due to pressure from the drive plate side may be formed on a flat surface side of the race connecting member on which the drive plate is arranged. 
     When the race connecting member is fastened in place by the drive plate while being sandwiched between the drive plate and the crankshaft end surface, deformation on the drive plate side may applied as pressure to the race connecting member. When this pressure is applied, the race connecting member side may also deform, which may affect the function of the one-way clutch and the sealability. Providing the first load relieving portion on the side on which the drive plate is arranged, however, makes it possible to prevent the race connecting member from deforming, thus preventing the sealability and the one-way clutch from being affected. 
     The first load relieving portion may be formed as a separated surface region in which a surface of the race connecting member is separated from the drive plate. 
     This structure easily enables the load generated by the pressure from the drive plate to be relieved, thereby making it possible to prevent the race connecting member from deforming. 
     A boundary between the separated surface region and a contacting surface region in which the surface of the race connecting member is contacting the drive plate may be within a region where the crankshaft end surface and the drive plate oppose one another. 
     Providing the boundary of the surface region within the region where the crankshaft end surface and the drive plate oppose one another enables an increase in load due to deformation of the drive plate to be released to the crankshaft side from the crankshaft end surface that supports the race connecting member from the opposite side, thus making it possible to prevent deformation of the outer race support plate. 
     The ring gear may be rotatably supported by the crankshaft via the bearing, and a boundary between the separated surface region and a contacting surface region in which the surface of the race connecting member is contacting the drive plate may be within a region that includes both a region where the drive plate opposes the crankshaft end surface and a region where the drive plate opposes an inner race end surface of the bearing. 
     There are cases in which the bearing is on the outside of the crankshaft and the inner race end surface of this bearing also sandwiches the race connecting member. In this case, the boundary of the surface region may also be within the region that includes both the region where the drive plate opposes the crankshaft end surface and the region where the drive plate opposes the inner race end surface of the bearing. As a result, an increase in load due to deformation of the drive plate can be released to the crankshaft side from the crankshaft end surface or from the inner race of the bearing, thus making it possible to prevent the race connecting member from deforming. 
     The drive plate may also be fastened in place by being pressed to the race connecting member side by a washer plate, a second load relieving portion to prevent a load produced by deformation of the drive plate from being applied to the race connecting member may be formed, as a separated surface region in which a surface of the washer plate is separated from the drive plate, on the washer plate, and the boundary between the separated surface region and the contacting surface region on the race connecting member side may be arranged offset in the radial direction with respect to a boundary between the separated surface region and a contacting surface region, in which the surface of the washer plate is contacting the drive plate, on the washer plate side. 
     When the drive plate is fastened in place by being pressed to the race connecting member side by a washer plate in this way, the boundary of the surface region on the race connecting member side is arranged offset in the radial direction with respect to the boundary of the surface region on the washer plate side. As a result, the point of contact of the washer plate side boundary that easily deforms when it receives a reaction force from the washer plate is different from the point of contact of the race connecting member side boundary that easily deforms when it receives a reaction force from the race connecting member. Thus, by inhibiting a deformation-causing reaction force from concentrating in one location in this way, it is possible to prevent the drive plate from cracking or the like, thus improving its durability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and further objects, features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein: 
         FIG. 1  is a longitudinal sectional view of a startup torque transmitting mechanism of an internal combustion engine according to a first embodiment of the invention; 
         FIG. 2  is a longitudinal sectional view of a startup torque transmitting mechanism of an internal combustion engine according to a second embodiment of the invention; 
         FIG. 3  is a longitudinal sectional view of a startup torque transmitting mechanism of an internal combustion engine according to a third embodiment of the invention; and 
         FIG. 4A  and  FIG. 4B  are longitudinal sectional views of a startup torque transmitting mechanism of an internal combustion engine, which show a modified example of the position of a stepped portion that determines the range of a load relieving portion in the third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a longitudinal sectional view of a startup torque transmitting mechanism of an internal combustion engine for a vehicle according to a first embodiment, and shows the area on the rear side of the internal combustion engine where power is output to the transmission side. 
     According to the first embodiment, as shown in  FIG. 1 , a rear end (i.e., the right end in the drawing) of a crankshaft  6  that is rotatably supported on a cylinder block side by a ladder beam  4  is arranged above a rear end (i.e., right end in the drawing) of an oil pan  2  of an internal combustion engine. As shown in the drawing, a flywheel  8 , an outer race support plate  10  (which can be regarded as a race connecting member in the claims), and a ring gear  12  are all mounted to the rear end portion of the crankshaft  6 . 
     The flywheel  8 , the portion of which is below the center axis C being shown in  FIG. 1 , is substantially disc-shaped, with the center portion being open in the shape of a circle. A ring-shaped clutch disc  8   a , which serves as a portion of a clutch mechanism for transmitting torque to and from a transmission, is mounted to a surface of the flywheel  8  on the side opposite the side contacting the outer race support plate  10 . The clutch mechanism may also be formed separately from the flywheel  8 . 
     The outer race support plate  10 , the portion of which is below the center axis C being shown in  FIG. 1 , is formed in a flat circular shape with the center portion open. The outer race support plate  10  is fixed in place by a bolt both to the flywheel  8  and to a rear end surface (i.e., the right end surface in the drawing)  6   a  of the crankshaft  6  at the peripheral portion of the center opening, as shown in  FIG. 1 . As a result, the outer race support plate  10  rotates in conjunction with both the flywheel  8  and the crankshaft  6 . 
     The ring gear  12 , the portion of which is below the center axis C being shown in  FIG. 1 , is a circular disc in which the center portion is largely open and which has bent portions (a cylindrical stepped portion  12   b  and a curved portion  12   e , which will be described later) in the radial direction. The ring gear  12  includes a flange-shaped inner race  16  of a one-way clutch  14  in the center open portion and a ring-shaped gear portion  12   a  on the outer peripheral portion. This ring gear  12  is mounted to the outer periphery of the crankshaft  6  via a bearing  18  (a roller bearing in this embodiment) on the center side, which is the side of the inner race  16  opposite the one-way clutch  14 . Therefore, when the one-way clutch  14  is released, the ring gear  12  can rotate freely, independent of the rotation of the crankshaft  6 . 
     The gear portion  12   a  of the ring gear  12  is in constant mesh with a pinion gear  20  of a starter motor. When torque from the starter motor is applied via the pinion gear  20  to this gear portion  12   a , the ring gear  12  rotates. A plurality of hole portions  13  are formed in the ring gear  12  around the center axis C in a region between the cylindrical stepped portion  12   b  and the gear portion  12   a . These hole portions  13  both reduce the weight of the ring gear  12  as well as make it possible to verify the state of the inside oil seal after the ring gear  12  has been arranged on the rear end surface  6   a  of the crankshaft  6 , and the like. 
     An outer race  22  is mounted to the outer peripheral portion of the outer race support plate  10  on the outside side (i.e., the lower side in  FIG. 1 ), opposing the inner race  16  which is mounted to the center open portion of the ring gear  12  such that a one-way clutch  14  is formed between the ring gear  12  and the outer race support plate  10 . Thus, the bearing  18  is arranged on an inner peripheral surface  16   a  side of the inner race  16  and the one-way clutch  14  is formed on an outer peripheral side surface  16   b  side of the inner race  16 , which is on the opposite side of the inner race  16  from the inner peripheral surface  16   a . In this specification, the inner peripheral surface refers to the surface on the side facing (i.e, closest to) the center axis C. Conversely, the outer peripheral surface refers to the surface on the side that is farthest from the crankshaft. 
     The one-way clutch  14  engages the outer race support plate  10  with the ring gear  12  when the starter motor rotates the ring gear  12  via the pinion gear  20  during startup of the internal combustion engine, i.e., when the ring gear  12  is rotated in the direction that will enable torque to be transmitted to the outer race support plate  10 . As a result, the starter motor can rotate the crankshaft  6 . 
     When the internal combustion engine starts to operate under its own power and the rotation speed of the outer race support plate  10  which rotates in conjunction with the crankshaft  6  becomes faster than the rotation speed of the ring gear  12  from the starter motor due to the output of the internal combustion engine, the ring gear  12  side effectively rotates in the opposite direction relative to the outer race support plate  10  so the one-way clutch  14  releases. Therefore, even if the pinion gear  20  and the ring gear  12  are in a state of constant mesh, overspeed of the starter motor after startup of the internal combustion engine can be prevented. 
     In this case, engine oil is supplied via an oil passage in the cylinder block or the crankshaft  6  in order to lubricate the bearing  18  and the one-way clutch  14 . However, the outer race support plate  10  and the ring gear  12  are arranged so as to sandwich the one-way clutch  14  so it is necessary to prevent oil from leaking out. Accordingly, a ring-shaped first oil seal member  24  is arranged between the outer race  22  of the one-way clutch  14 , which is integrally mounted to the outer race support plate  10 , and the cylindrical stepped portion  12   b  of the ring gear  12 . This first oil seal member  24  is fixed to the ring gear  12  side by being fitted to an inner peripheral surface  12   c  of the cylindrical stepped portion  12   b . A seal lip  24   a  which is formed on the inner peripheral side of the first oil seal member  24  is thus urged to slidably contact the outer peripheral surface of the outer race  22 , thereby providing an oil seal. 
     A second oil seal member  26  which has a larger diameter than the first oil seal member  24  is arranged on the opposite side (the lower side in  FIG. 1 ) of the cylindrical stepped portion  12   b  from the first oil seal member  24  such that the first oil seal member  24  and the second oil seal member  26  sandwich the cylindrical stepped portion  12   b . This second oil seal member  26  is fixed in the position shown in the drawing by being fitted both to an inner peripheral surface  2   b  of the rear end (i.e., the right end in  FIG. 1 )  2   a  of mainly the oil pan  2  (which can be regarded as an internal combustion engine main side member in the claims) on the lower side in  FIG. 1  of the crankshaft  6 , and to the inner peripheral surface of the rear end (i.e., the right end in  FIG. 1 ) of mainly the cylinder block (which can be regarded as an internal combustion engine main body side member in the claims) on the upper side in  FIG. 1  of the crankshaft  6 . Accordingly, a seal lip  26   a  which is formed on the inner peripheral side of the second oil seal member  26  slidably contacts an outer peripheral surface  12   d  of the cylindrical stepped portion  12   b , thus providing an oil seal. 
     As described above, the outer race support plate  10  is formed separately from the flywheel  8  and is provided independently from the crankshaft  6  not via the flywheel  8 . Therefore, impact noise produced when the one-way clutch  14  engages is not directly transmitted to the flywheel  8 . Also, impact noise produced on the outer race support plate  10  side is not directly transmitted to the flywheel  8  because it must travel through the portion that is fastened by the bolt B. 
     The ring gear  12  is supported by the crankshaft  6  via the beating  18  so impact noise from the ring gear  12  is also not directly transmitted to the flywheel  8 . 
     Furthermore, the positional relationship of the outer race support plate  10  and the ring gear  12  is such that the outer race support plate  10  is arranged on the opposite side of the ring gear  12  from the internal combustion engine main body side (i.e., the left side of the oil pan  2  in  FIG. 1 ). Therefore, the one-way clutch  14  and the bearing  18  are both completely covered from the outside of the internal combustion engine by the connecting body of the outer race support plate  10  and the outer race  22 . 
     The first embodiment described above can achieve the following effects. 
     (I) The outer race support plate  10  to which torque from the pinion gear  20  is transmitted from the ring gear  12  via the one-way clutch  14  and thus rotates the crankshaft  6  is provided separately from the flywheel  8  and is mounted to the crankshaft  6  not via the flywheel  8 . Therefore, as described above, impact noise produced when the one-way clutch  14  engages is not directly transmitted to the flywheel  8 . Accordingly, sound radiation from the flywheel  8  can be suppressed, making it possible to reduce noise. 
     (II) The ring gear  12  is rotatably supported by the crankshaft  6  via the bearing  18 . Therefore, as described above, impact noise that is produced when the one-way clutch  14  engages is not directly transmitted to the flywheel  8  from the ring gear  12  side either. As a result, sound radiation from the flywheel  8  can be suppressed, making it possible to more effectively reduce noise. 
     (III) The outer race support plate  10  is connected to the outer race  22  of the one-way clutch  14 , and the ring gear  12  is connected to the inner race  16  of the one-way clutch  14 . Moreover, the Outer race support plate  10  is arranged on the opposite side of the ring gear  12  from the internal combustion engine main body. Therefore, the connecting body of the outer race support plate  10  and the outer race  22  can completely cover the bearing  18  and the one-way clutch  14  with from the outside of the internal combustion engine. As a result, good sealability of the startup torque transmitting mechanism of an internal combustion engine can be easily realized. 
     Therefore, as shown in  FIG. 1 , because the first oil seal member  24  is arranged in the gap between the outer race  22  and the ring gear  12 , and the second oil seal member  26  is arranged in the gap between the ring gear  12  and the rear end (i.e., the right end in the drawing)  2   a  of the oil pan  2 , it is possible to seal the inside of the startup torque transmitting mechanism of an internal combustion engine against oil leaking out both easily and with good sealability. 
     (IV) In the ring gear  12 , the curved portion  12   e  is provided between the gear portion  12   a  and the cylindrical stepped portion  12   b . When there is impact noise transmitted from the pinion gear  20  which is produced when the starter motor starts to drive or when there is impact noise transmitted from the one-way clutch  14  when the engine rotates in reverse, the ring gear  12  bends at the portion of this curved portion  12   e,  thus reducing the impact force, which protects the startup torque transmitting mechanism of an internal combustion engine, as well as the mechanism related to the startup torque transmitting mechanism, from impact force. 
     Also, when the bend in the curved portion  12   e  is large due to excessive impact force, the ring gear  12  deforms within the limitations of elastic deformation and contacts the flywheel  8 . More specifically, as shown in  FIG. 1 , the inside portion  12   f  of the gear portion  12   a  contacts the outer peripheral portion  8   b  of the flywheel  8 , which produces sliding resistance. This sliding resistance prevents damage to the ring gear  12  itself as well as damage to the bearing  18  when excessive impact force is input to the ring gear  12 . 
     (V) The outer race support plate  10  is formed separately from the flywheel  8 . As a result, even if the shape of the flywheel  8  with which it is combined is different, the outer race support plate  10  and the like can still be used as a common component part. Furthermore, the startup torque transmitting mechanism of an internal combustion engine according to this embodiment can be structured as a common startup torque transmitting mechanism of an internal combustion engine regardless of the type of transmission used, i.e., regardless of whether a manual transmission which uses a flywheel or an automatic transmission which uses a torque converter is used. 
     (VI) The outer race support plate  10  is formed separately from the flywheel  8  on which the clutch disc  8   a  is arranged. Moreover, on the outer peripheral side of the outer race support plate  10 , the outer race support plate  10  and the flywheel  8  are separated from one another. As a result, heat from the clutch disc  8   a  that is generated when the clutch engages is not easily transferred particularly to the first oil seal member  24  that slidably contacts the outer race  22 . Therefore, thermal degradation of the first oil seal member  24  does not easily occur so durability of the oil seal is improved. 
       FIG. 2  is a sectional view of a startup torque transmitting mechanism of an internal combustion engine for a vehicle according to a second embodiment of the invention, and shows the area on the rear side of the internal combustion engine where power is output to the transmission side. 
     According to the second embodiment, as shown in  FIG. 2 , a drive plate  30 , not the flywheel, is fastened by a bolt to the outer race support plate  10  and the crankshaft  6 . The outer race support plate  10  and the drive plate  30  are both fastened, together with a washer plate  32 , to the rear end surface (i.e., the right end surface in  FIG. 2 )  6   a  of the crankshaft  6  by a bolt B. 
     The drive plate  30  is fastened by a bolt at the outer peripheral portion of a cover  34  of a torque converter. As a result, rotation of the crankshaft  6  is transmitted to the torque converter side by the drive plate  30 . 
     The other structure is the same as that in the first embodiment described above and will therefore be denoted by the same reference numerals used in the first embodiment. 
     The second embodiment described above can achieve the following effects. 
     (I) The drive plate  30 , instead of the flywheel, is mounted to the crankshaft  6 , and the outer race support plate  10  is provided separately from this drive plate  30  and is mounted to the crankshaft  6  not via the drive plate  30 . Therefore, as described above, impact noise produced when the one-way clutch  14  engages is not directly transmitted to the drive plate  30 . Accordingly, sound radiation from the drive plate  30  itself or the cover  34  of the torque converter can be suppressed, making it possible to reduce noise. 
     (II) The effects described in II., III., IV, and V. in the first embodiment can also be obtained by this second embodiment. In particular, with respect to IV., sliding resistance occurs when the ring gear  12  contacts the drive plate  30 , not the flywheel. This sliding resistance prevents damage to the ring gear  12  itself as well as damage to the bearing  18  when excessive impact force is input to the ring gear  12 . 
       FIG. 3  is a sectional view of a startup torque transmitting mechanism of an internal combustion engine for a vehicle according to a third embodiment of the invention, and shows the area on the rear side of the internal combustion engine where power is output to the transmission side. Compared to  FIG. 1  or  FIG. 2 ,  FIG. 3  shows an enlarged view of the area near the bolt B.  FIG. 4A  and  FIG. 4B  are views showing a modified example of the position of a stepped portion  50   c  which determines the range of the load relieving portion in the third embodiment. 
     The structure of the third embodiment shown in  FIG. 3  differs from that of the second embodiment shown in  FIG. 2  in that a load relieving portion  52 , shown in the enlarged view of  FIG. 3 , is provided on a flat surface side of an outer race support plate  50  (which can be regarded as a race connecting member in the claims) on which the drive plate  30  is arranged. The other structure is the same as it is in the second embodiment and therefore will be denoted by like reference numerals. 
     Here, as shown in  FIG. 3 , the load relieving portion  52  is formed by a separated surface region  50   a  in which the surface of the outer race support plate  50  is separated from the surface of the drive plate  30 , as compared to a portion of the outer race support plate  50  (i.e., a contacting surface region  50   b ) that is fasted to the drive plate  30  by the bolt B. As a result, with this load relieving portion  52 , the drive plate  30  floats above the outer race support plate  50  so even if the drive plate  30  deforms, no load from the drive plate  30  will be applied to the outer race support plate  50  at the load relieving portion  52 . 
     Here, a stepped portion  50   c , which is the boundary between the separated surface region  50   a  and the contacting surface region  50   b , is set in a position in which, when fastened by the bolt B, sufficient pressing force is applied to the contacting surface region  50   b  around the bolt B without it buckling. In the third embodiment, the position of a through-hole  50   d  for the bolt B which is farthest from the center axis C (see  FIG. 1  or  FIG. 2 ) is designated as a limit position Pi. This limit position Pi may be closer to the center axis C side than the position shown in  FIG. 3 . 
     A limit position Po to the outside (i.e., the lower side in  FIG. 3 ) of the stepped portion  50   c  is located on the outermost side (i.e., the lower side in  FIG. 3 ) of the inner race  18   a  of the bearing  18  that is press-fit to the outer periphery of the crankshaft  6 . Therefore, the stepped portion  50   c  (the starting point P on the inside of the load relieving portion  52 ) may be set to the position Pi, as shown in  FIG. 4A , or set to the position Po, as shown in  FIG. 4B . The stepped portion  50   c  may also be arranged in any position (i.e., Aio) between the position Pi and the position Po. 
     Furthermore, as shown in  FIGS. 3 ,  4 A, and  4 B, a load relieving portion  32   a  is also formed in the washer plate  32 . It is important to note that the starting point P of the stepped portion  50   c  is offset in the radial direction from the starting point Q of the load relieving portion  32   a  on the washer plate  32  side. 
     The separated surface region  50   a  can be regarded as a surface region that is separated from the drive plate (i.e., a separated surface region) in the claims. The contacting surface region  50   b  can be regarded as a surface region that is contacting the drive plate (i.e., a contacting surface region) in the claims. The stepped portion  50   c  can be regarded as a boundary between the separated surface region and the contacting surface region in the claims. The starting point Q of the load relieving portion  32   a  formed on the washer plate  32  can be regarded as a boundary between the separated surface region on the washer plate side ( 32   c  in  FIG. 3 ) and the contacting surface region ( 32   b  in  FIG. 3 ) in the claims. 
     The third embodiment described above can achieve the following effects. 
     (I) The same effects obtained with the second embodiment are also obtained with this third embodiment. 
     (II) The outer race support plate  50  is fastened by the drive plate  30  by being sandwiched between it and the rear end surface (i.e., the right end surface in  FIG. 3 )  6   a  of the crankshaft  6 . Therefore, if the cover  34  deforms (see  FIG. 2 ) from a load applied to the torque converter such that the drive plate  30  deforms, that deformation may be applied to the outer race support plate  50  as pressure. Because the load relieving portion  52  is provided on the side of the outer race support plate  50  that contacts the drive plate  30 , the load relieving portion  52  prevents that deformation from reaching the outer race support plate  50  side when that pressure is applied. As a result, in particular, it is possible to prevent that deformation from affecting the sealability of the first oil seal member  24  and one-way clutch  14 . 
     Even if a load from the deformation of the drive plate  30  is applied to the contacting surface region  50   b , the stepped portion  50   c  is positioned between the inside limit position Pi which is across from the rear end surface (i.e., the right end surface in  FIG. 3 )  6   a  of the crankshaft  6 , and the outermost position Po (i.e., the lower side in  FIG. 3 ) which is across from the inner race end surface  18   b  of the bearing  18 . In this way, the stepped portion  50   c  is within a region that includes the region where the drive plate  30  opposes the rear end surface (i.e., the right end surface in  FIG. 3 )  6   a  of the crankshaft  6  and the region where the drive plate  30  opposes the inner race end surface  18   b  of the bearing  18 . Therefore, regardless of which region the stepped portion  50   b  is in between the inside limit position Pi and the outside limit position Po, the load will be applied to either the crankshaft  6  or the inner race  18   a  of the bearing. Accordingly, the load from the pressure from the drive plate  30  is reliably released to the crankshaft  6  and the bearing  18  side, thereby making it possible to prevent deformation of the outer race support plate  50 . 
     In  FIGS. 3 and 4A , the position of the stepped portion  50   c  in the radial direction is entirely within the region where the drive plate  30  opposes the rear end surface (i.e., the right end surface in the drawings)  6   a  of the crankshaft  6 . Therefore, an increase in load due to deformation of the drive plate  30  can be released to the crankshaft  6  from the rear end surface (i.e., the right end surface in the drawings)  6   a  of the crankshaft  6 , thus making it possible to effectively prevent deformation of the outer race support plate  50 . 
     In the example shown in  FIG. 4B  as well, the position of the stepped portion  50   c  in the radial direction is within the region where the drive plate  30  opposes the inner race end surface  18   b  of the bearing  18 . Therefore, an increase in load due to deformation of the drive plate  30  can be released to the inner race  18   a  side of the bearing  18 . This structure thus also makes it possible to prevent deformation of the outer race support plate  50 . 
     (III) Moreover, in the examples shown in  FIGS. 4A and 4B , the stepped portion  50   c  is arranged offset in the radial direction with respect to the starting point Q on the inside (the center axis C side) of the load relieving portion  32   a  of the washer plate  32  so that they do not overlap at the front and back of the drive plate  30  in the radial direction. 
     As a result, deformation of the drive plate  30  radially offsets the position of the drive plate  30  itself that easily deforms from the washer plate  32  side with respect to the position that easily deforms from the outer race support plate  50  side at the front and back of the drive plate  30 . 
     In the third embodiment, the limit position Po on the outside of the stepped portion  50   c  is the outermost position in the region where the drive plate  30  and the inner race end surface  18   b  of the bearing oppose one another. Alternatively, however, the outside limit position Po may also be set to the outermost position in the region where the drive plate  30  and the rear end surface  6   a  of the crankshaft  6  oppose one another. This structure allows an increase in load due to deformation of the drive plate  30  to be reliably released from the rear end surface  6   a  of the crankshaft  6  to crankshaft  6  side, thereby making it possible to more reliably prevent deformation of the outer race support plate  50 . 
     While the invention has been described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the exemplary embodiments are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the invention.