Patent Publication Number: US-2013240655-A1

Title: Webbing retractor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under  35  USC  119  from Japanese Patent Application No. 2012-060306 filed Mar. 16, 2012, the disclosure of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a webbing retractor equipped with a seat belt device employed for example in a vehicle. 
     2. Related Art 
     In a seat belt retractor disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2002-104134 an axial direction hole is formed with a substantially hexagonal shaped cross-section in an axial center portion of a webbing take-up reel. A torque transmission shaft formed with a substantially hexagonal shaped cross-section to a torsion bar axial direction end portion is press-fitted to the axial direction hole. The torsion bar axial direction end portion is thereby connected so as to be capable of rotating as one with the reel. Moreover, rattle suppression ribs are respectively formed to three mutually non-adjacent sides of the inner peripheral face of the axial direction hole, such that rattling between the reel and the torsion bar is suppressed by the rattle suppression ribs. 
     In the seat belt retractor as described above, there is the possibility of unwanted burrs being generated by sliding contact between the rattle suppression ribs and the torque transmission shaft during press-fitting of the torque transmission shaft of the torsion bar (press insertion member) to the axial direction hole of the reel (pressed insertion member). 
     SUMMARY OF THE INVENTION 
     In consideration of the above circumstances, the present invention is to provide a webbing retractor capable of preventing or suppressing burrs from generating during press insertion of a press insertion member to a pressed insertion member. 
     In order to address the above issue, a webbing retractor according to a first aspect of the invention is a webbing retractor including: a press insertion member that is provided at a webbing take-up shaft supported rotatably at a frame, and that includes a press insertion portion; and a pressed insertion member that is formed from a material harder than the press insertion member, and that includes a pressed insertion portion to which the press insertion portion is press-inserted, and a rib that is provided on a face of the pressed insertion portion facing the press insertion portion, wherein an end face of the rib, which end face is on the opposite side to a press insertion direction of the press insertion portion to the pressed insertion portion, is a sloping face that slopes along the press insertion direction or is a curved face that curves along the press insertion direction. 
     Note that in the first aspect “that slopes (curves) along the press insertion direction” means “that slopes (curves) towards the press insertion direction on progression towards the press insertion portion”. 
     Moreover, “harder” in the first aspect means any configuration in which the press insertion portion is deformed (including being cut or shaved) by sliding contact between the rib and the press insertion portion during press insertion of the press insertion member to the pressed insertion member. 
     In the first aspect of the invention, the press insertion portion of the press insertion member provided to the webbing take-up shaft is press inserted (press fit) to the pressed insertion portion of the pressed insertion member. The pressed insertion member is formed from a material harder than the press insertion member. The rib is provided on the face of the pressed insertion portion of the pressed insertion member, facing the press insertion portion of the press insertion member, enabling rattling (looseness) between the press insertion member and the pressed insertion member to be suppressed by the rib. Moreover, the end face of the rib on the opposite side to the press insertion direction of the press insertion portion is configured by the sloping face that slopes along the press insertion direction of the press insertion portion or the curved face that curves along the press insertion direction of the press insertion portion. The sloping face or the curved face makes sliding contact with the press insertion portion during insertion of the press insertion member to the pressed insertion member. Burrs can thereby be prevented or suppressed from being generated by cutting of the press insertion portion by the rib, enabling easy press insertion of the press insertion portion to the pressed insertion portion. 
     A webbing retractor according to a second aspect of the invention is the first aspect wherein the press insertion portion is press-inserted to the pressed insertion portion from one end side of the press insertion portion, and an abutting portion for positioning, that is provided at another end side of the press insertion portion, abuts an abutted portion which is provided at the pressed insertion member. 
     The second aspect of the invention can prevent or suppress burrs from being generated by the press insertion portion being cut by the rib during press insertion of the press insertion portion of the press insertion member to the pressed insertion portion from the one end side. As a result, good assembly precision can be achieved between the press insertion member and the pressed insertion member since burrs can be prevented from being sandwiched between the abutting portion which is for positioning and which is provided to the other end side of the press insertion portion and the abutted portion which is provided to the pressed insertion member. 
     A webbing retractor according to a third aspect of the invention is the second aspect wherein a space is formed between the end face of the rib and the abutting portion. 
     In the third aspect of the invention, the space is formed between the end face (the sloping face or the curved face) of the rib provided at the pressed insertion portion, which is on the opposite side to the press insertion direction of the press insertion portion, and the abutting portion provided at the press insertion member. Thus even were a burr to be generated at the press insertion portion due to sliding contact between the end face of the rib and the press insertion portion, such a burr can be confined (pocketed) within the space. As a result, the burr can be effectively prevented from becoming sandwiched between the abutting portion of the press insertion member and the abutted portion of the pressed insertion member. 
     A webbing retractor of a fourth aspect of the invention is the third aspect wherein the end face of the rib is provided so as to be separated, in the press insertion direction, from the abutted portion. 
     In the fourth aspect of the invention, the end face which is on the opposite side to the press insertion direction of the press insertion portion of the rib formed to the pressed insertion portion is provided so as to be separated in the press insertion direction from the abutted portion. The space between the end face of the rib and the abutting portion of the press insertion member is accordingly made larger. Thus even were a burr to be generated at the press insertion portion by sliding contact between the end face of the rib and the press insertion portion, the burrs can be well made closed within the space. Moreover, due to providing the end face of the rib separated in this manner from the abutted portion as described above, the length of sliding contact between the rib and the press insertion portion can be made shorter. Thus even in cases in which a burr is generated due to sliding contact between the rib and the press insertion portion, the volume of the burr can be reduced, with this being effective in such cases in which there is a long press insertion stroke of the press insertion portion with respect to the pressed insertion portion. 
     A webbing retractor according to a fifth aspect of the invention is any one of the first aspect to the fourth aspect, wherein the press insertion portion is press-inserted to the pressed insertion portion from one end side of the press insertion portion, a concave portion is formed at the one end side of the press insertion portion, into which the rib is inserted when the press insertion portion is press-inserted to the pressed insertion portion; and an end face of the concave portion on the opposite side to the press insertion direction of the press insertion portion is configured by a sloping face that slopes such that the concave portion becomes shallower on progression towards another end side of the press insertion portion. 
     In the fifth aspect of the invention, the rib formed to the pressed insertion portion is inserted into the concave (indentation) portion formed to the one end side of the press insertion portion during press insertion of the press insertion portion of the press insertion member to the pressed insertion portion of the pressed insertion member from the one end side. The end face of the concave portion on the opposite side to the press insertion direction of the press insertion portion is configured with a sloping face that slopes such that the concave portion becomes shallower on progression towards the other end side of the press insertion portion. Burrs are accordingly suppressed from being generated by sliding contact of the sloping face of the concave portion with the end face of the rib (the curved face or the sloping face) when the other end side of the press insertion portion is press inserted to the pressed insertion portion (when the rib comes out from the concave portion). Namely, were a step portion (corner portion, for example, vertical portion) to be formed to the concave portion in place of the sloping face, there would be a possibility of a burr being generated by the step portion (corner portion) being cut by the rib, however, such a situation can be avoided in the present aspect. Moreover, even in a case in which for example the press insertion member is formed by forging, bulging up (building up) of the press insertion portion in the vicinity of the sloping face of the concave portion accompanying formation of the concave portion can be suppressed. Burrs can accordingly be suppressed from being generated by sliding contact between such bulging up portion and the rib. 
     A webbing retractor of a sixth aspect of the invention is any one of the first aspect to the fifth aspect, wherein the webbing take-up shaft comprises a spool on which webbing is taken up, and a torsion shaft that has one end portion connected to the spool; the press insertion member is a sleeve that is attached to another end portion of the torsion shaft; and the pressed insertion member is a clutch base that is attached to the sleeve and that connects a ring portion provided on a side of the frame and the sleeve via a pawl. 
     In the sixth aspect of the invention, the press insertion portion provided to the sleeve is press inserted to the pressed insertion portion provided to the clutch base, and the clutch base connects together the ring portion provided on the frame side and the sleeve via the pawl, restricting rotation of the sleeve with respect to the frame. The sleeve is attached to the other end portion of the torsion shaft that has its one end connected to the spool, and the torsion shaft thereby undergoes twisting deformation when excess tension force acts on the webbing in the sleeve rotation restricted state. Energy absorption can thereby be achieved. Moreover, since in the present aspect, burrs can be prevented or suppressed from being generated during press insertion of the press insertion portion provided to the sleeve into the pressed insertion portion provided to the clutch base, good assembly precision can be achieved for example between the sleeve and the clutch base. As a result, the engagement precision can be raised when the clutch base engages the pawl and the ring portion. 
     A webbing retractor of a seventh aspect of the invention is any one of the first aspect to the fifth aspect, wherein the webbing take-up shaft comprises a spool on which webbing is taken up, and a torsion shaft that is connected to the spool; the press insertion member is the spool, the pressed insertion member is the torsion shaft, and the rib is formed on the pressed insertion portion provided at an end portion in an axial direction of the torsion shaft. 
     In any one of the first aspect to the seventh aspect, it is possible that the rib is formed so as to protrude from the pressed insertion portion toward a side of the press insertion portion, and a protruding height of the sloping face of the rib or the curved face of the rib becomes lower on progression towards the opposite side to the press insertion direction of the press insertion portion. 
     In the sixth aspect, it is possible that the pressed insertion portion is a hole that passes through the pressed insertion member in an axial direction of the webbing take-up shaft, the rib is formed so as to protrude from an inner peripheral face of the hole toward a side of an outer peripheral face of the press insertion portion, and a protruding height of the sloping face of the rib or the curved face of the rib becomes lower on progression towards the opposite side to the press insertion direction of the press insertion portion. 
     In the seventh aspect, it is possible that the press insertion portion is a hole portion that is provided at an axial center portion of the press insertion member, the rib is formed so as to protrude from an outer peripheral face of the pressed insertion portion toward a side of an inner peripheral face of the hole portion, and a protruding height of the sloping face of the rib or the curved face of the rib becomes lower on progression towards the opposite side to the press insertion direction of the press insertion portion. 
     As explained above, in the webbing retractor according to the present invention, burrs can be prevented or suppressed from being generated during press insertion of the press insertion member to the pressed insertion member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will be described in detail with reference to the following figures, wherein: 
         FIG. 1  is an exploded perspective view illustrating a configuration of relevant portions of a webbing retractor according to a first exemplary embodiment of the present invention; 
         FIG. 2  is an exploded perspective view illustrating a configuration of a clutch mechanism that is a configuration member of the webbing retractor; 
         FIG. 3  is a diagram of the clutch mechanism as viewed from the opposite side to that of a spool; 
         FIG. 4A  is a diagram illustrating a state when clutch plates of the clutch mechanism have started to rotate towards a lock ring side; 
         FIG. 4B  is a diagram illustrating a state in which the clutch plates have meshed with a lock ring; 
         FIG. 5  is an exploded perspective view illustrating a configuration of a switching mechanism that is a configuration member of the webbing retractor; 
         FIG. 6  is a face-on view of a clutch base that is a configuration member of the clutch member; 
         FIG. 7  is a perspective view illustrating a configuration of part of the clutch base; 
         FIG. 8  is a cross-section illustrating a section along line  8 - 8  of  FIG. 6 ; 
         FIG. 9A  is a perspective view illustrating a state partway through press insertion of a sleeve of the clutch mechanism into the clutch base; 
         FIG. 9B  is a perspective view illustrating a fully press-inserted state of the sleeve into the clutch base 
         FIG. 10A  is a cross-section illustrating a state partway through press insertion of the sleeve of the clutch mechanism into the clutch base; 
         FIG. 10B  is a cross-section illustrating a fully press-inserted state of the sleeve of the clutch mechanism into the clutch base; 
         FIG. 11  is a cross-section for explaining a state when a rib of the clutch base makes sliding contact with the press insertion portion of the sleeve; 
         FIG. 12  is a perspective view corresponding to  FIG. 7  and illustrating a configuration of portions of a clutch base provided to a clutch mechanism that is a configuration member of a webbing retractor according to a second exemplary embodiment of the present invention; 
         FIG. 13  is a cross-section illustrating a cross-section taken along line  13 - 13  of  FIG. 12 ; 
         FIG. 14A  is a cross-section illustrating a state partway through press insertion of a sleeve of the clutch mechanism into the clutch base; 
         FIG. 14B  is a cross-section illustrating a fully press-inserted state of the sleeve into the clutch base; 
         FIG. 15  is a cross-section illustrating part of a configuration of a webbing retractor according to a third exemplary embodiment of the present invention; and 
         FIG. 16  is a cross-section illustrating a modified exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
     A webbing retractor  10  relating to a first embodiment of the present invention is described hereinafter by using  FIG. 1  through  FIG. 11 . 
     As shown in  FIG. 1  through  FIG. 5 , the webbing retractor  10  relating to the present first embodiment has a frame  12 , a webbing  22 , a webbing take-up shaft  11 , and a switching mechanism  120 . 
     As shown in  FIG. 1 , the frame  12  has a plate-shaped back plate  14  that is fixed to the vehicle body. Leg pieces  16 ,  18  extend substantially orthogonally from the vehicle transverse direction both end portions of the back plate  14 , and the frame  12  is formed in a substantially concave shape as seen in plan view. Note that a known locking mechanism is mounted to the outer side of the leg piece  18 . Further, the webbing  22  is applied to the body of a passenger, and is formed in an elongated belt shape. 
     Structure of Webbing Take-Up Shaft  11   
     The webbing take-up shaft  11  has a spool  20 , a lock gear  24  serving as a lock section, a main torsion shaft  32 , a trigger wire  40 , a sub torsion shaft  44  and a clutch mechanism  52 . The main torsion shaft  32  and the sub torsion shaft  44  configure a force limiter mechanism  31 . 
     The spool  20  is formed in a cylindrical tube shape having a through-hole  21  that passes through in the axial direction, and is disposed between the leg piece  16  and the leg piece  18  of the frame  12 . The spool  20  is disposed in a state in which the axial direction thereof is along the direction in which the leg piece  16  and the leg piece  18  oppose one another. The spool  20  is rotatably supported at the frame  12  via the main torsion shaft  32 , the sub torsion shaft  44  and the like. A longitudinal direction one end portion (a proximal (base) end portion) of the webbing  22  is anchored on the spool  20 . Due to the spool  20  rotating in a take-up direction (the direction of arrow A in  FIG. 1  and the like) that is one rotating direction, the webbing  22  is taken-up and accommodated from the proximal end side thereof. 
     The lock gear  24  is disposed coaxially to the spool  20  at an axial direction one side of the spool  20  (the arrow E direction side in  FIG. 1  and  FIG. 2 ). A gear portion  26  is formed at the outer peripheral portion of the lock gear  24 . Further, a through-hole  28 , that passes through in the axial direction, is formed at the axially central portion of the lock gear  24 . An engaged portion  30  that is spline-shaped is formed at the inner peripheral portion of the through-hole  28 . 
     At the time of an emergency of the vehicle (a predetermined occasion such as rapid deceleration or the like), due to the aforementioned locking mechanism detecting that the acceleration (in particular, the decelerating acceleration) of the vehicle is greater than or equal to a predetermined acceleration, or detecting that the pull-out acceleration of the webbing  22  from the spool  20  is greater than or equal to a specific acceleration, and operating, a locking member (not illustrated in the drawings) of the locking mechanism engages with the gear portion  26  of the lock gear  24 , and rotation of the lock gear  24  in the pull-out direction (the direction of arrow B in  FIG. 1  and the like) is impeded (locked). 
     The main torsion shaft  32  is disposed coaxially with the spool  20  and the lock gear  24 , and is inserted through the through-hole  21  of the spool  20  and the through-hole  28  of the lock gear  24 , respectively. A first engagement portion  34  that is spline-shaped is formed at the longitudinal direction central portion of the main torsion shaft  32 . A second engagement portion  36  that is similarly spline-shaped is formed at the distal end portion of the main torsion shaft  32 . 
     Further, due to the first engagement portion  34  being fit-together with and anchored by the engaged portion  30  of the lock gear  24 , the main torsion shaft  32  is connected to (anchored on) the lock gear  24  so as to be able to rotate integrally therewith. Further, due to the second engagement portion  36  being fit-together with and anchored by an unillustrated engaged portion that is formed at the axial direction intermediate portion of the inner peripheral portion of the spool  20 , the main torsion shaft  32  is connected to (anchored on) the spool  20  so as to be able to rotate integrally therewith. 
     The portion between the first engagement portion  34  and the second engagement portion  36  at the main torsion shaft  32  is structured as a first energy absorbing portion  38  that is for absorbing kinetic energy of the passenger that is used to pull the webbing  22  as is described later. 
     A proximal end portion  40 A of the trigger wire  40  is inserted in a hole portion  29  that is formed at a position that is further toward the radial direction outer side than the through-hole  28  at the lock gear  24 , and is anchored at the lock gear  24 . On the other hand, the portion of the trigger wire  40  that is further toward the distal end side than the proximal end portion  40 A thereof is inserted in a hole portion  42  that is formed in the spool  20  in parallel with the through-hole  21 . A distal end portion  40 B of the trigger wire  40  projects-out from the spool  20  toward the axial direction other side (the arrow F direction side in  FIG. 1  and  FIG. 2 ). 
     The sub torsion shaft  44  is disposed coaxially with the main torsion shaft  32 . The portion of the sub torsion shaft  44  that is further toward the proximal end side than the longitudinal direction central portion thereof is inserted in the through-hole  21  of the spool  20 . On the other hand, the portion of the sub torsion shaft  44  that is further toward the distal end side than the longitudinal direction central portion thereof projects-out from the spool  20  toward the axial direction other side. 
     A first engagement portion  46  that is spline-shaped at least one portion thereof is formed at the proximal end portion of the sub torsion shaft  44 . A second engagement portion  48  that is similarly spline-shaped is formed at the distal end portion of the sub torsion shaft  44 . The first engagement portion  46  is engaged with an engaged portion (not shown in the drawings) that is formed at the axial direction intermediate portion of the inner peripheral portion of the spool  20 . Due thereto, the sub torsion shaft  44  is connected to (anchored on) the spool  20  so as to be able to rotate integrally therewith. 
     Further, the portion between the first engagement portion  46  and the second engagement portion  48  at the sub torsion shaft  44  is structured as a second energy absorbing portion  50  for absorbing the kinetic energy of the passenger that is used to pull the webbing  22  as is described later. 
     As illustrated in  FIG. 1  and  FIG. 2 , the clutch mechanism  52  includes a sleeve  54  serving as a press insertion (press fit) member, a clutch guide  64 , a clutch base  82  serving as a pressed insertion (pressed fit) member, a clutch cover  88 , a pair of clutch plates  100  serving as pawls, a screw  108  and a pair of coil springs  98 . Note that a state in the midst of operation of the clutch mechanism  52  is shown in  FIG. 4A , and a state after operation of the clutch mechanism  52  is completed is shown in  FIG. 4B . 
     The sleeve  54  is disposed coaxially to the sub torsion shaft  44 . A through hole  56  is formed to an axial center potion of the sleeve  54 , passing through along the axial direction. The sub torsion shaft  44  is inserted into the through hole  56  with play therebetween. A spline shaped engaged portion  58  is formed at the distal end side of an inner peripheral portion of the sleeve  54 . The sleeve  54  is connected (anchored) so as to be capable of rotation as integrally with the sub torsion shaft  44  due to the second engagement portion  48  of the sub torsion shaft  44  engaging with the engaged portion  58   
     The proximal end side of the sleeve  54  is structured as a supporting portion  60  having a circular cylinder shaped external profile, and a portion of the sleeve  54  that is further toward the distal end side than the supporting portion  60  is structured as a press insertion (press fit) portion  62  that is formed in a regular hexagonal shape in cross-section. 
     The clutch guide  64  is made of resin, and is formed in an annular shape having a through-hole  66  that passes through in the axial direction. The above-described supporting portion  60  is inserted in this through-hole  66 , and due thereto, the clutch guide  64  is supported at the sleeve  54  so as to be able to rotate relative thereto. 
     As shown in  FIG. 3 , a pair of coil spring accommodating portions  68 , that accommodate the coil springs  98 , are formed at positions at two places in the peripheral direction at the clutch guide  64 . These coil spring accommodating portions  68  are formed in shapes having point symmetry around the central portion of the clutch guide  64 . Each of the coil spring accommodating portions  68  is formed in a substantial U-shape having an outer side wall portion  70  and an inner side wall portion  72  that extend in the peripheral direction of the clutch guide  64 , and a connecting wall portion  74  that extends in the radial direction of the clutch guide  64  and connects respective end portions of the outer side wall portion  70  and the inner side wall portion  72 . 
     Further, a pair of clutch plate accommodating portions  76  that accommodate the clutch plates  100  are formed in the clutch guide  64  adjacent to the respective coil spring accommodating portions  68 . A first supporting wall portion  78  that extends from the connecting wall portion  74  toward the side opposite the inner side wall portion  72 , and a second supporting wall portion  80  that is apart from the connecting wall portion  74  at the side of the connecting wall portion  74  opposite the side at which the outer side wall portion  70  is located, are formed at these clutch plate accommodating portions  76 . 
     The clutch base  82  is structured to have a base main body  84  that is annular. A press insertion (press fit) hole  85  (pressed insertion (pressed fit) portion) that is shaped as a regular hexagon in cross-section is formed in the base main body  84 . The press insertion portion  62  of the sleeve  54  is press-inserted into (fit to) this press insertion hole  85 , and, due thereto, the clutch base  82  is fixed to the sleeve  54  so as to be able to rotate integrally therewith. Further, a pair of anchor portions  86  that project-out toward the outer side from the base main body  84  are formed at the clutch base  82 . These anchor portions  86  are anchored on the proximal end portions of arm portions  102  that are formed at the clutch plates  100  that are described later. 
     The clutch cover  88  is disposed coaxially to the sleeve  54 , and is disposed so as to face the clutch guide  64 , at the side of the clutch guide  64  opposite the side at which the spool  20  is located. The clutch cover  88  is formed in an annular shape having a through-hole  90  that passes through in the axial direction. Plural fit-together claws  92 , that project-out toward the radial direction inner side, are formed at the inner peripheral portion of the clutch cover  88 . Further, due to the press insertion portion  62  of the sleeve  54  being inserted into the through-hole  90  and the plural fit-together claws  92  being fit-together with the press insertion portion  62 , the clutch cover  88  is fixed to the sleeve  54 , and accordingly to the sub torsion shaft  44 , so as to be able to rotate integrally therewith. Further, cross-shaped claws  96 , that are described later, of the clutch cover  88  engage with the clutch guide  64  in the peripheral direction, and the clutch guide  64  is made able to rotate relative to the clutch cover  88  between an operation position shown in  FIG. 4B  and a non-operation position shown in  FIG. 3 . 
     Cut-out portions  94 , that are formed in concave shapes as seen in the axial direction and that open toward the radial direction outer side, are respectively formed at positions of two places in the peripheral direction at the clutch cover  88 . Further, the pair of cross-shaped claws  96  are formed at the clutch cover  88  so as to be positioned at the inner sides of the respective cut-out portions  94 . This pair of cross-shaped claws  96  is formed in shapes that are point symmetrical around the central portion of the clutch cover  88 . Moreover, these cross-shaped claws  96  are bent in crank shapes as seen from the radial direction of the clutch cover  88 , and the distal end sides thereof project-out further toward the clutch guide  64  side than the proximal end sides thereof. 
     An inner side projecting portion that projects-out toward the radial direction inner side of the clutch guide  64 , an outer side projecting portion that projects-out toward the radial direction outer side of the clutch guide  64 , and a peripheral direction projecting portion that projects-out in one peripheral direction of the clutch guide  64  (the take-up direction), are provided at the distal end sides of each of the cross-shaped claws  96 . The distal end sides of each of the cross-shaped claws  96  are formed in the shape of a cross as seen from the axial direction of the clutch guide  64 . 
     The clutch plates  100  are disposed between the clutch cover  88  and the clutch guide  64 . The clutch plates  100  have the arm portions  102 , and arc-shaped portions  104  that are formed at the distal end portions of the arm portions  102 . Rotating shafts  106 , that project-out toward the clutch cover  88  side and extend along the axial direction of the sub torsion shaft  44 , are formed at the proximal end portions of the arm portions  102 . The clutch plates  100  are rotatably supported at the clutch cover  88  due to the rotating shafts  106  being inserted in hole portions  89  that are formed in the clutch cover  88 . Further, flat-tooth-shaped knurled teeth  104 A are formed at the outer peripheral portions of the arc-shaped portions  104  (the distal end portions of the clutch plates  100 ). 
     The screw  108  has a screw portion  110 , and a pushing portion  112  that has a larger diameter than the screw portion  110 . The screw portion  110  is screwed-together with a screw hole  45  that is formed in the distal end portion of the sub torsion shaft  44 . Due thereto, the screw  108  is fixed to the distal end portion of the sub torsion shaft  44 . Further, in the state in which the screw  108  is fixed to the distal end portion of the sub torsion shaft  44  in this way, the pushing portion  112  abuts the distal end portion of the sleeve  54 . Due thereto, movement of the sleeve  54  in the direction of coming-off from the sub torsion shaft  44  is limited. In this state, axial direction movement of the clutch guide  64  is limited by the clutch cover  88  and the spool  20 . 
     Further, hole portions  65 ,  91  are formed in the above-described clutch guide  64  and clutch cover  88 , respectively. These hole portions  65 ,  91  are formed so as to face one another in the state in which the clutch guide  64  is disposed at the non-operation position with respect to the clutch cover  88 . The distal end portion  40 B of the trigger wire  40  is inserted respectively into these hole portions  65 ,  91 . Due thereto, in the state in which the clutch guide  64  is disposed at the non-operation position, relative rotation of the clutch guide  64  with respect to the spool  20  and the clutch cover  88  is limited (the clutch guide  64  is restrained at the non-operation position). 
     Still further, in the state in which the clutch guide  64  is restrained at the non-operation position as described above, the respective cross-shaped claws  96  of the clutch cover  88  are disposed in vicinities of the opening portions at the respective coil spring accommodating portions  68  of the clutch guide  64 . Further, the peripheral direction projecting portions of the respective cross-shaped claws  96  are inserted into the inner sides of the coil springs  98  from axial direction one end portions of the coil springs  98  that are accommodated in the respective coil spring accommodating portions  68 . The inner side projecting portions and the outer side projecting portions of the respective cross-shaped claws  96  abut the axial direction one end portions of the coil springs  98 . Due thereto, the axial direction one end portions of the coil springs  98  are anchored on the respective cross-shaped claws  96 . Further, the axial direction other end portions of the coil springs  98  are anchored on the connecting wall portions  74  (see  FIG. 3 ) of the coil spring accommodating portions  68 . 
     In this state, the intervals between the cross-shaped claws  96  and the connecting wall portions  74  are shorter than the full lengths in the free states of the coil springs  98 , and, due thereto, the coil springs  98  are in compressed states. Further, due thereto, urging force in the take-up direction is imparted to the clutch guide  64 , and the clutch guide  64  is urged toward the operation position. 
     On the other hand, in this state, there is a state in which the intervals between the hole portions  89  of the clutch cover  88  (the rotating shafts  106  of the clutch plates  100 ) and the connecting wall portions  74  are sufficiently ensured, and the clutch plates  100  are accommodated in the clutch plate accommodating portions  76  such that the knurled teeth  104 A are kept further toward the inner side than the outer peripheral portion of the clutch guide  64 . Further, in this state, the connecting wall portions  74  abut the distal ends of the arc-shaped portions  104 . 
     (Structure of Switching Mechanism  120 ) 
     As shown in  FIG. 5 , the switching mechanism  120  has the body  122  that is box shaped. The interior of the body  122  is open toward the leg piece  16  side of the frame  12 , and the body  122  is fixed to the outer side of the leg piece  16 . A lock ring  190  (link portion) that is substantially annular plate shaped is supported so as to rotate freely at the interior of the body  122 . The lock ring  190  serving as a ring portion is disposed coaxially to the clutch mechanism  52 , at the outer peripheral side of the clutch mechanism  52 . Further, flat-tooth-shaped knurled teeth  190 A are formed at the inner peripheral portion of the lock ring  190 . Moreover, a lock hole  192 , that is substantially triangular in cross-section, is formed to pass through the outer peripheral portion of the lock ring  190 . The lock hole  192  opens toward the radial direction outer side of the lock ring  190 . 
     A case portion  124 , that serves as a housing portion that houses a pawl  150 , a piston  160 , and a gas generator  194  that are described later, is provided at the upper portion of the body  122 . Further, a substantially plate-shaped sheet  126  is provided at the leg piece  16  side of the body  122 , and the sheet  126  closes-off the opening portion of the body  122 . 
     A concave portion  130  that opens toward the leg piece  16  side is provided at the case portion  124 . A supporting portion  132 , that is substantially C-shaped in cross-section, is formed at the concave portion  130 . The supporting portion  132  supports a shaft portion  152  of the pawl  150 , that is described later, so as to rotate freely. Further, a shear pin  134  that is solid cylindrical is provided integrally with the case portion  124  at the interior of the concave portion  130 , and the shear pin  134  projects-out toward the leg piece  16  side. A piston accommodating portion  136  is provided within the concave portion  130 . The piston  160 , that is manufactured of resin, is accommodated within the piston accommodating portion  136  so as to be able to move rectilinearly in the longitudinal direction of the piston accommodating portion  136  (the arrow C direction and the arrow D direction in  FIG. 5 ). 
     The pawl  150  that is substantially plate-shaped is accommodated within the concave portion  130  of the case portion  124 . The shaft portion  152 , that is substantially circular in cross-section, is provided at the pawl  150  at the portion thereof at the supporting portion  132  side of the concave portion  130 , and the shaft portion  152  is supported at the supporting portion  132  so as to rotate freely. Further, the pawl  150  has a substantially L-shaped arm portion  154 . An engaging portion  156  is provided at the proximal end portion of the arm portion  154 . The distal end of the engaging portion  156  is disposed within the lock hole  192  of the lock ring  190  (at a locking position), and is engaged with the lock ring  190 . Moreover, an anchor hole  158 , that is circular in cross-section, is formed so as to pass through the proximal end portion of the arm portion  154 . The aforementioned shear pin  134  is inserted through the anchor hole  158  interior, and rotation of the pawl  150  is limited. 
     Further, the gas generator  194 , that is substantially solid cylindrical, is incorporated within the case portion  124  at a region that is at the side of the piston accommodating portion  136  opposite the side at which the leg piece  16  is located. The gas generator  194  communicates with the piston accommodating portion  136 . The control device (not illustrated in the drawings) of the vehicle is electrically connected to this gas generator  194 . At the time when the gas generator  194  is operated due to control of the control device, the gas generator  194  generates gas, and this gas is supplied to a cylinder portion  140  of the piston accommodating portion  136 . 
     The aforementioned control device is electrically connected to a collision detection unit that is not illustrated in the drawings. The collision detection unit predicts a collision of the vehicle by, for example, an acceleration sensor that senses the acceleration (a sudden deceleration in particular) of the vehicle, or a distance measuring sensor that detects the distance to an obstacle in front of the vehicle, or the like. Further, the collision detection unit is structured so as to detect that the vehicle has collided, due to the acceleration sensor sensing a collision acceleration that is greater than or equal to a predetermined reference value. 
     Moreover, the control device is electrically connected to a physique detection unit that is not illustrated in the drawings. The physique detection unit detects the physique of the passenger seated in the seat by, for example, a load sensor, a belt sensor, a seat position sensor, or the like. Concretely, a load sensor detects the load that is applied to a seat of the vehicle, and the physique detection unit detects the physique of the passenger in accordance with the detected load. Further, a belt sensor detects the amount of the webbing  22  that is pulled-out from the spool  20 , and the physique detection unit detects the physique of the passenger in accordance with the detected pulled-out amount. Moreover, a seat position sensor is structured by a position detection sensor that detects the slid position of the vehicle seat in the front-back direction, or by a camera sensor that is provided in the vehicle cabin, and the physique detection unit detects the physique of the passenger in accordance with the position of the seat detected by the seat position sensor. 
     The gas generator  194  is operated by the control device in a case in which the control device judges, on the basis of a signal from the physique detection unit, that the physique of the passenger is less than a predetermined reference value, and judges, on the basis of a signal from the collision detection unit, that the vehicle has collided. Due thereto, gas is supplied from the gas generator  194  to the interior of the piston accommodating portion  136 . When gas is supplied to the interior of the piston accommodating portion  136 , due to the pressure of this gas, the piston  160  moves toward the arm portion  154  side of the pawl  150 . Due thereto, the piston  160  pushes the arm portion  154 , and rotational force is thereby applied to the pawl  150 . Due to the pawl  150  rotating toward a lock releasing position while breaking the shear pin  134  due to this rotational force, the engaging portion  156  of the pawl  150  is pulled-out from the lock hole  192  of the lock ring  190 . Note that due to an elastic hook, that is provided at the outer peripheral portion of the piston  160 , catching on a step portion that is formed at the inner peripheral portion of the piston accommodating portion  136 , movement of the piston  160 , that has moved toward the arm portion  154  side, toward the side opposite the arm portion  154  is restricted. 
     Main Portions of a First Embodiment 
     In a first exemplary embodiment, the press insertion hole  85  of regular hexagonal shaped cross-section is formed to the base main body  84  of the clutch base  82  which is provided at the clutch mechanism  52 . The press insertion portion  62  of regular hexagonal shaped cross-section provided to the sleeve  54  is press-inserted (press fit) into the press insertion hole  85 . The sleeve  54  is formed from a metal material (for example from a cold forging steel member), and the clutch base  82  is formed from a metal material harder than the sleeve  54  (for example from a high tensile steel plate). 
     As illustrated in  FIG. 6 , the inner peripheral face of the press insertion hole  85  of the clutch base  82 , namely the face facing to the press insertion portion  62 , is formed with plural (three in this case) ribs  91 . The ribs  91  are provided to suppress rattling (looseness) between the sleeve  54  and the clutch base  82 , and are formed at three mutually non-adjacent sides (faces)  85 A,  85 C,  85 E on the inner peripheral face of the press insertion hole  85 . The ribs  91  are not formed on the other three sides (faces)  85 B,  85 D,  85 F. The ribs  91  are formed with semicircular shaped cross-sections as viewed along the thickness direction of the clutch base  82  (a direction perpendicular to the plane of the paper in  FIG. 6 ). (The ribs  91  are formed so as to protrude toward the axial center side of the press insertion hole  85 .) The ribs  91  are also, as illustrated in  FIG. 7 , formed in elongated shapes along the clutch base  82  thickness direction. Note that, as shown in  FIG. 6 , each of the ribs  91  is disposed further to the pull-out direction side (the arrow B direction in  FIG. 6 ) than the center of the respective three sides  85 A,  85 C,  85 E. 
     As illustrated in  FIG. 8 , one length direction end face of each of the ribs  91  (the face on the lower side in  FIG. 8 ) is formed in the same plane as one thickness direction end face  84 A of the clutch base  82 . The other length direction end face of each of the ribs  91  (the face on the upper side in  FIG. 8 ) is configured with a sloping face  91 A (C face (Chamfer-face)) that slopes downwards on progression towards the center side of the press insertion hole  85  from another thickness direction end face  84 B of the clutch base  82 . The angle of slope of the sloping faces  91  A with respect to the other thickness direction end face  84 B of the clutch base  82  is set at, for example,  45  degrees, so as to slope along the press insertion direction of the press insertion portion  62  (the arrow F direction in  FIG. 8 ). Namely, in a state in which the press insertion portion  62  is press inserted into the press insertion hole  85 , each of the sloping faces  91 A slopes towards the press insertion direction of the press insertion portion  62  on progression towards the outer peripheral face of the press insertion portion  62 , in the other words, a protruding height of each of the sloping faces  91 A (ribs  91 ) becomes lower on progression towards the opposite side to the press insertion direction of the press insertion portion  62 . 
     When press-insert the press insertion portion  62  of the sleeve  54  into the press insertion hole  85  of the clutch base  82 , configuration is such that the press insertion portion  62  is inserted from the side formed with the sloping faces  91  A of the ribs  91 . Namely configuration is made such that the press insertion portion  62  is press inserted into the press insertion hole  85  from the other thickness direction end face  84 B side of the clutch base  82  (see  FIG. 9A  and  FIG. 9B ). 
     Plural (six in this case) indentation portions (concave portions)  67  are formed on the outer peripheral face of the press insertion portion  62  of the sleeve  54  to correspond to the plural ribs  91 . The indentation portions  67  are formed respectively to the six faces configuring the outer peripheral face of the press insertion portion  62 . The indentation portions  67  are formed in rectangular shapes as viewed along the sleeve  54  radial direction, and are each formed extending from the leading end portion (the end portion on the opposite side to the supporting portion  60 ) of the press insertion portion  62  to the vicinity of intermediate portion of the press insertion portion  62 . Each of the indentation portions  67  is, as illustrated in  FIG. 10A , configured such that an end face at the opposite side of the indentation portion  67  to the leading end portion of the press insertion portion  62  is a sloping face  67 A that slopes with respect to the sleeve  54  axial direction (the arrow E direction and the arrow F direction in  FIG. 10A ). The sloping faces  67 A are formed to slope such that the indentation portions  67  become shallower on progression towards the base end side of the press insertion portion  62 . A bottom face  67 B of each of the indentation portions  67  is connected to the outer peripheral face of the base end side of the press insertion portion  62  though the sloping face  67 A. Note that indentation portions (concave portions)  69  are formed to the outer peripheral face of the press insertion portion  62  of the sleeve  54  respectively adjacent to each of the above indentations  67 . Configuration is such that the fitting claws  92  of the clutch cover  88  are engaged with the indentation portions  69 . 
     When press-insert the press insertion portion  62  of the sleeve  54  into the press insertion hole  85  of the clutch base  82 , the press insertion portion  62  is inserted into the press insertion hole  85  from the leading end side (one end side). When this occurs, the three ribs  91  of the press insertion hole  85  are inserted from the sloping face  91 A side into the three mutually non-adjacent indentation portions  67  out of the six indentation portions  67  of the press insertion portion  62 . Then, as illustrated in  FIG. 10A , when the sloping faces  91 A of the plural ribs  91  make contact with (abuts with) the sloping faces  67 A of the plural indentation portions  67 , the load required to press-insert the press insertion portion  62  into the press insertion hole  85  increases. When the press insertion portion  62  is pushed from this state further into the press insertion hole  85 , sliding contact portions of the press insertion portion  62  with the plural ribs  91  are deformed by the sloping faces  91  A of the ribs  91  making sliding contact with the outer peripheral face of the base end side (other end side) of the press insertion portion  62 . In such case, as illustrated in  FIG. 11 , each portion at the base end side of the press insertion portion  62 , where is in sliding contact with each of the ribs  91 , deforms so as to bulge (build) up at both sides of the rib  91  due to the sloping face  91 A of the rib  91  pressing (pushing) the each portion of the press insertion portion  62  towards the sleeve  54  radial direction inside. Namely, the rib  91  is press-inserted into the press insertion hole  85  while the portion of the press insertion portion  62  is pushed out around the rib  91  by the sloping face  91 A. 
     When a hole edge portion  84 B 1  (abutted portion) of the press insertion hole  85 , which is on the other thickness direction end face  84 B of the clutch base  82  makes contact with (abuts with) a step portion  63  (abutting portion) between the press insertion portion  62  and the supporting portion  60  of the sleeve  54 , the press insertion portion  62  cannot be press-inserted any further into the press insertion hole  85 . The clutch base  82  is thereby positioned in the axial line direction with respect to the sleeve  54 . In this state, the clutch base  82  is assembled to the sleeve  54  without rattling due to portions at the base end side of the press insertion portion  62  where are in sliding contact with the ribs  91  deforming in the manner described above. In this state, as illustrated in  FIG. 10B , spaces  99  that are triangular shaped as viewed along the sleeve  54  circumferential direction are formed between the sloping faces  91 A of the ribs  91  (the end faces of ribs  91 , which are on the opposite side to the press insertion portion  62  insertion direction) and the step portion  63 . Namely, configuration is such that the triangular shaped space  99  is formed between the sloping face  91 A of the rib  91 , the base end portion of the press insertion portion  62 , and the step portion  63  since the width direction dimension W 1  of the press insertion hole  85  is set larger than the width direction dimension W 2  of the press insertion portion  62 . 
     (Operation and Effect) 
     The operation and effects of the present first embodiment are described next. In the webbing retractor of the above-described structure, the webbing take-up shaft, namely, the spool  20 , the lock gear  24 , the main torsion shaft  32 , the sub torsion shaft  44  and the clutch mechanism  52  (including the sleeve  54 , the clutch base  82 , the clutch plates  100  and the screw  108 ) are able to rotate integrally in the take-up direction and the pull-out direction. 
     Due to the webbing  22  being pulled-out from the spool  20 , the webbing  22  is applied to the body of a passenger of the vehicle. In the state in which the webbing  22  is applied to the body of a passenger of the vehicle, when, for example, the vehicle enters into a state of rapid deceleration and the locking mechanism  33  operates, rotation of the lock gear  24  in the pull-out direction is impeded. 
     Due thereto, rotation, in the pull-out direction, of the spool  20  that is connected to the lock gear  24  via the main torsion shaft  32  is limited, and pulling-out of the webbing  22  from the spool  20  is limited. Accordingly, due thereto, the body of the passenger, that starts to move toward the vehicle front, is restrained by the webbing  22 . 
     In the state in which rotation, in the pull-out direction, of the lock gear  24  is impeded, when the body of the passenger pulls the webbing  22  by an even greater force, and the rotational force of the spool  20  in the pull-out direction, that is based on this pulling force, exceeds the twist resisting load (the deformation resisting load) of the first energy absorbing portion  38  of the main torsion shaft  32 , the force limiter mechanism  31  is operated. Due to the twisting (deformation) of the first energy absorbing portion  38 , rotation, in the pull-out direction and that is greater than or equal to the force limiter load (the twist resisting load of the first energy absorbing portion  38 ), of the spool  20  is permitted. 
     Accordingly, due to the twisting of the first energy absorbing portion  38 , the spool  20  is rotated in the pull-out direction, and the webbing  22  is pulled-out from the spool  20 . Due thereto, the load (burden) on the chest portion of the passenger due to the webbing  22  is reduced, and the kinetic energy of the passenger, that is used to pull the webbing  22 , is absorbed by an amount corresponding to the amount of twisting of the first energy absorbing portion  38 . 
     On the other hand, as described above, the spool  20  being rotated in the pull-out direction with respect to the lock gear  24  means that the lock gear  24  is rotated in the take-up direction relative to the spool  20 . Accordingly, when the lock gear  24  is rotated relative to the spool  20  in the take-up direction, the proximal end portion  40 A of the trigger wire  40  is moved in the peripheral direction of the main torsion shaft  32  while the portion of the trigger wire  40 , which portion is further toward the distal end side than the proximal end portion  40 A, remains inserted in the hole portion  42  of the spool  20 . Therefore, the portion of the trigger wire  40 , which portion is further toward the distal end side than the proximal end portion  40 A, is pulled toward the lock gear  24  side with respect to the hole portion  42 . 
     Due thereto, the distal end portion  40 B of the trigger wire  40  is pulled-out from the hole portion  65  of the clutch guide  64  and the hole portion  91  of the clutch cover  88 , and the state, in which relative rotation of the clutch guide  64  with respect to the spool  20  and the clutch cover  88  is impeded, is cancelled. 
     Then, when the clutch guide  64  is rotated from the non operation position to the operation position due to the urging forces of the coil springs  98 , the intervals between the hole portions  89  of the clutch cover  88  (the rotating shafts  106  of the clutch plates  100 ) and the connecting wall portions  74  of the clutch guide  64  become short, and the distal ends of the arc-shaped portions  104  of the clutch plates  100  are pushed (guided) in tangent directions of the clutch guide  64  by the connecting wall portions  74 . Due thereto, the clutch plates  100  are rotated toward the lock ring  190  side (refer to arrow R in  FIG. 4A ), and the knurled teeth  104 A of the clutch plates  100  mesh-together with the knurled teeth  190 A of the lock ring  190  (the state shown in  FIG. 4B ). Due thereto, the clutch plates  100  and the lock ring  190  are joined. Further, at this time, due to the anchor portions  86 , that are formed at the clutch base  82 , pushing the proximal end portions of the arm portions  102  of the clutch plates  100  in the pull-out direction, the clutch plates  100  are pushed against the lock ring  190 , and the state in which the clutch plates  100  and the lock ring  190  are joined is maintained. Due thereto, the lock ring  190  attempts to rotate in the pull-out direction integrally with the rotation in the pull-out direction of the clutch mechanism  52  (the sleeve  54 , the clutch base  82 , and the clutch plates  100 ). 
     Further, on the basis of a signal from the physique detection unit, the control device judges whether or not the physique of the passenger is greater than or equal to a predetermined reference value, and, on the basis of a signal from the collision detection unit, the control device judges whether or not the vehicle has collided. When the control devices judges that the physique of the passenger is greater than or equal to the predetermined reference value, the gas generator  194  is not operated, and therefore, the engaging portion  156  of the pawl  150  is disposed at the locking position and is engaged with the lock hole  192  of the lock ring  190 . Thus, rotation of the lock ring  190  in the pull-out direction is locked (impeded), and due thereto, rotation of the clutch mechanism  52  (the sleeve  54 , the clutch base  82  and the clutch plates  100 ) in the pull-out direction is impeded. 
     Further, in the state in which rotation, in the pull-out direction, of the sleeve  54 , is impeded, when the body of the passenger pulls the webbing with even greater force, and the rotational force of the spool  20  in the pull-out direction that is based on this pulling force exceeds the total of the twist resisting load (the deformation resisting load) of the first energy absorbing portion  38  of the main torsion shaft  32  and the twist resisting load (the deformation resisting load) of the second energy absorbing portion  50  of the sub torsion shaft  44 , due to the twisting (deformation) of the first energy absorbing portion  38  and the second energy absorbing portion  50 , rotation, in the pull-out direction and that is greater than or equal to the force limiter load (the total of the twist resisting load of the first energy absorbing portion  38  and the twist resisting load of the second energy absorbing portion  50 ), of the spool  20  is permitted. 
     Accordingly, due to the spool  20  being rotated in the pull-out direction by the twisting the first energy absorbing portion  38  and the second energy absorbing portion  50 , and the webbing  22  being pulled-out from the spool  20 , the load (burden) on the chest portion of the passenger due to the webbing  22  is reduced, and the kinetic energy of the passenger, that is used to pull the webbing  22 , is absorbed by an amount corresponding to the amounts of twisting of the first energy absorbing portion  38  and the second energy absorbing portion  50 . 
     On the other hand, when the control device judges, on the basis of a signal from the physique detection unit, that the physique of the passenger is less than the predetermined reference value, and judges, on the basis of a signal from the collision detection unit, that the vehicle has collided, the gas generator  194  is operated by control of the control device. 
     When the gas generator  194  is operated, gas is supplied from the gas generator  194  into the cylinder portion  140  of the piston accommodating portion  136 . When gas is supplied into the cylinder portion  140 , the piston  160  moves toward the arm portion  154  side of the pawl  150  and pushes the arm portion  154 . Therefore, rotational force around the shaft portion  152  is applied to the pawl  150 . Due to this rotational force, the inner peripheral portion of the anchor hole  158  of the pawl  150  abuts the shear pin  134  and breaks the shear pin  134 , and due thereto, rotation of the pawl  150  around the shaft portion  152  is permitted, and the pawl  150  is rotated from the locking position to the releasing position. Due thereto, the engaging portion  156  of the pawl  150  moves away from the lock hole  192  of the lock ring  190 , and rotation of the lock ring  190  in the pull-out direction is permitted. Due thereto, the lock ring  190  is made able to rotate in the pull-out direction together with the clutch mechanism  52  (the sleeve  54 , the clutch base  82  and the clutch plates  100 ) and the spool  20 . Therefore, twisting does not arise at the second energy absorbing portion  50 , and thus, due to the twisting (deformation) of the first energy absorbing portion  38 , rotation, in the pull-out direction and of greater than or equal to the force limiter load (the twist resisting load of the first energy absorbing portion  38 ), of the spool  20  is permitted. 
     Namely, when the physique of the passenger is greater than or equal to the predetermined reference value, the force limiter load is made to be the total of the twist resisting load of the first energy absorbing portion  38  and the twist resisting load of the second energy absorbing portion  50 , and the load value of the force limiter load is made to be a high load. On the other hand, when the physique of the passenger is less than the predetermined reference value and collision of the vehicle is detected, the force limiter load is made to be the twist resisting load of the first energy absorbing portion  38 , and the load value of the force limiter load is made to be a low load. Therefore, the passenger can be protected appropriately in accordance with his/her physique. 
     In the present exemplary embodiment, the press insertion portion  62  of the sleeve  54  provided to the webbing take-up shaft  11  is press inserted from the leading end side into the press insertion hole  85  of the clutch base  82 , and the step portion  63  (abutting portion) provided on the base end side of the press insertion portion  62  makes contact with the abutted portion of the clutch base  82 . The clutch base  82  is formed from a material harder than the sleeve  54 . 
     The ribs  91  are provided at the press insertion hole  85  of the clutch base  82  on faces facing the press insertion portion  62  of the sleeve  54 , enabling rattling between the sleeve  54  and the clutch base  82  to be suppressed by the ribs  91 . The end faces of the ribs  91  on the opposite side to the press insertion direction of the press insertion portion  62  are configured by the sloping faces  91 A that slope along the press insertion direction of the press insertion portion  62 . Thus, the sloping faces  91 A of the ribs  91  make sliding contact with the press insertion portion  62  when the press insertion portion  62  is being press inserted into the press insertion hole  85 . In this case, the portion of the press insertion portion  62  is pushed out around the rib  91  by the sloping face  91 A as the rib  91  is press-inserted into the press insertion hole  85 . Burrs from cutting the press insertion portion  62  by the ribs  91  can accordingly be prevented or suppressed from generating. Load when the press insertion portion  62  is press-inserted into the press insertion hole  85  can also be made smaller, enabling the press insertion portion  62  to be readily press-inserted into the press insertion hole  85 . 
     Moreover, in the present exemplary embodiment, due to being able to prevent or suppress burrs from generating as described above, burrs can be prevented from becoming trapped (sandwiched) between the step portion  63  and the hole edge portion  84 B 1  of the press insertion hole  85 . As a result good assembly precision in the axial line direction can be achieved between the sleeve  54  and the clutch base  82 , so enabling, for example, the engagement precision to be raised when the clutch plates  100  are engaged with the lock ring  190  by the clutch base  82 . 
     Moreover, in the present exemplary embodiment, the space  99  is formed between the sloping face  91 A of the rib  91  and the step portion  63  of the sleeve  54 . Hence even if a burr was to be generated on the press insertion portion  62  due to sliding contact between the sloping face  91 A of the rib  91  and the press insertion portion  62 , such a burr could be trapped (closed) inside the space  99 . As a result burr can be effectively prevented from getting sandwiched between the step portion  63  of the sleeve  54  and the hole edge portion  84 B 1  of the press insertion hole  85  of the clutch base  82 . 
     Moreover, in the present exemplary embodiment, the ribs  91  provided at the press insertion hole  85  are inserted into the indentation portions  67  formed at the leading end side of the press insertion portion  62  when the press insertion portion  62  of the sleeve  54  is being press inserted from the leading end side into the press insertion hole  85  of the clutch base  82 . In the indentation portions  67 , the end faces of the indentation portions  67  at the opposite side to the press insertion portion  62  insertion direction are configured as the sloping faces  67 A, the sloping faces  67 A sloping such that the indentation portions  67  become shallower towards the base end side of the press insertion portion  62 . Burrs are accordingly suppressed from generating due to sliding contact of the sloping faces  67 A of the indentation portions  67  against the sloping faces  91 A of the ribs  91  when the base end side of the press insertion portion  62  is being press inserted into the press insertion hole  85  (when the ribs  91  are coming out from the indentation portions  67 ). Namely, in case in which step portions (corner portions, for example, vertical portions) were formed in place of the above sloping faces  67 A at the indentation portions  67 , there would be the possibility of burrs generating due to these step portions (corner portions) being cut by the ribs  91 , however this can be avoided in the present exemplary embodiment. Moreover, since bulging up of the press insertion portion  62  in the vicinity of the sloping faces  67 A of the indentation portions  67  accompanying forming the indentation portions  67  can be suppressed from occurring in a case in which the sleeve  54  is for example formed by forging, burrs can also be suppressed from generating due to sliding contact between such raised portions and the ribs  91 . 
     Moreover, in the present exemplary embodiment, the end faces of the ribs  91  formed to the press insertion hole  85  on the opposite side to the press insertion direction of the press insertion portion  62  are configured with sloping faces  91 A rather than with curved faces, and so the sloping faces  91 A make sliding contact with the press insertion portion  62 . In this case, since the sliding contact angle between the sloping face  91 A of the rib  91  and the press insertion portion  62  can be made constant, the manner in which a portion of the press insertion portion  62  in sliding contact with the rib  91  deforms can be stabilized. 
     Next, explanation follows regarding other exemplary embodiment of the present invention. Note that configuration and operation that is basically the same as that of the first exemplary embodiment is allocated the same reference numerals as those of the first exemplary embodiment and further explanation thereof is omitted. 
     Second Exemplary Embodiment 
       FIG. 12  is a perspective view corresponding to  FIG. 7  that illustrates a portion of a clutch base  82 ′ that is a configuration member of a webbing retractor according to a second exemplary embodiment of the present invention.  FIG. 13  is a cross-section taken along line  13 - 13  of  FIG. 12 . This exemplary embodiment is configured basically the same as the first exemplary embodiment, but ribs  91 ′ of the clutch base  82 ′ differ from the ribs  91  according to the first exemplary embodiment. The ribs  91 ′ are configured basically the same as the ribs  91  of the first exemplary embodiment, except that sloping faces  91 A′ that are the end faces of the ribs  91 ′ on the opposite side to the press insertion portion  62  press insertion direction (to the arrow F direction of  FIG. 13  and  FIG. 14 ) are provided separated in the press insertion direction from a hole edge portion  84 B 1  (abutted portion) of a press insertion hole  85  of the clutch base  82 ′. Thus in the press-inserted state of the press insertion portion  62  in the press insertion hole  85 , as illustrated in  FIG. 14B , trapezoidal spaces  101  are formed between the sloping faces  91 A′ of the ribs  91 ′ and the step portion  63  of the sleeve  54  as viewed along the sleeve  54  circumferential direction. 
     Other parts of the configuration of the present exemplary embodiment are configured similarly to in the first exemplary embodiment. Basically the same operation and advantageous effects are accordingly exhibited to those of the first exemplary embodiment. Further, due to the sloping faces  91 A′ of the ribs  91 ′ being provided separated in the press insertion direction of the press insertion portion  62  from the hole edge portion  84 B 1  of the press insertion hole  85 , the spaces  101  formed between the sloping faces  91 A′ and the step portion  63  are larger than the spaces  99  according to the first exemplary embodiment. Therefore, as illustrated in  FIG. 14B , even supposing a burr  103  was to be generated on the press insertion portion  62  due to sliding contact between the rib  91 ′ and the press insertion portion  62 , the burr  103  can be well confined (pocketed) within the space  101 . As a result, good assembly precision can be achieved between the sleeve  54  and the clutch base  82  due to being able to prevent the burr  103  from becoming trapped (sandwiched) between the step portion  63  of the sleeve  54  and the hole edge portion  84 B 1  of the press insertion hole  85  of the clutch base  82 . 
     Moreover, due to providing the sloping faces  91 A′ of the ribs  91 ′ at positions separated from the hole edge portion  84 B 1  of the press insertion hole  85 , the length of sliding contact of the ribs  91 ′ with the press insertion portion  62  can be made shorter. Thus even were a burr  103  to be generated by sliding contact between the rib  91 ′ and the press insertion portion  62 , the volume of the burr  103  can be made smaller, with this being effective in such situations as when the press insertion stroke of the press insertion portion  62  with respect to the press insertion hole  85  is longer. 
     Third Exemplary Embodiment 
       FIG. 15  is a cross-section illustrating a configuration of part of a webbing retractor according to a third exemplary embodiment of the present invention. In the present exemplary embodiment, a press insertion portion  202  (hole portion) is provided at an axial center portion of a spool  200  that serves as a press insertion member is press-inserted (press-fit) from an opening side over a pressed insertion portion  206  that is provided at one axial direction end portion of a torsion shaft  204  serving as a pressed insertion member. The torsion shaft  204  is formed from a metal material harder than the spool  200 . Ribs  208  are also provided to an outer peripheral face of the pressed insertion portion  206  (a face that faces the press insertion portion  202 ). An end face of the rib  208  on the opposite side to the press insertion direction of the press insertion portion  202  (to the arrow G direction of  FIG. 15 ) is configured as a sloping face  208 A (C (chamfer) face) that slopes along the press insertion direction. The torsion shaft  204  is positioned in the axial line direction with respect to the spool  200  by abutting between a bottom face  202 A (abutting portion) of the press insertion portion  202  of the spool  200  and a leading end face  206 A (abutted portion) of the pressed insertion portion  206  of the torsion shaft  204 . 
     In the present exemplary embodiment, rattling between the spool  200  and the torsion shaft  204  can be suppressed by the ribs  208  provided to the pressed insertion portion  206  of the torsion shaft  204 . Moreover, due to the end face on the opposite side to the press insertion portion  202  press insertion direction of the rib  208  being configured by the sloping face  208 A, the sloping face  208 A of the rib  208  makes sliding contact with the inner peripheral face of the press insertion portion  202  when the press insertion portion  202  is press-inserted onto the pressed insertion portion  206 . Thus similarly to in each of the above exemplary embodiments, due to preventing or suppressing burrs from being generated on the press insertion portion  202 , burrs can be prevented from becoming trapped (sandwiched) between the bottom face  202 A (abutting portion) of the press insertion portion  202  and the leading end face  206 A (abutted portion) of the pressed insertion portion  206 . As a result, good assembly precision can be achieved in the axial direction between the spool  200  and the torsion shaft  204 . 
     Supplementary Explanation to each of the Exemplary Embodiments 
     In each of the exemplary embodiments, configuration is made with the sloping faces  91 A,  91 A,  208 A provided to the ribs  91 ,  91 ′,  208  on the end faces on the opposite side to the press insertion direction of the press insertion portion  62 ,  202 , however the present invention is not limited thereto. Configuration may be made such that the end faces of the ribs  91 ,  91 ′,  208  on the opposite side to the press insertion direction of the press insertion portion  62 ,  202  are curved faces  91 B that curve along the press insertion direction of the press insertion portion  62 ,  202  ( FIG. 16 ). In such cases the press insertion portion  62 ,  202  can also be prevented or suppressed from being cut by the ribs  91 ,  91 ′,  208 , and so burrs can prevented or suppressed from being generated at the press insertion portion  62 ,  202 . 
     Moreover, in each of the exemplary embodiments explanation has been given of cases in which the sleeve  54  and the spool  200  serve as press insertion members, and the clutch base  82 ,  82 ′ and the torsion shaft  204  serve as pressed insertion members. However the present invention is not limited thereto and configuration may be made such that the press insertion member and the pressed insertion member are provided to a webbing take-up shaft. For example, in each of the exemplary embodiments, configuration may be made such that the main torsion shaft  32  serves as the press insertion member, and the lock gear  24  serves as the pressed insertion member. In such cases configuration is made such that the first engagement portion  34  of the main torsion shaft  32  serves as the press insertion portion, and the engaged portion  30  (the through hole  28 ) of the lock gear  24  serves as the pressed insertion member, and rib(s) are formed to the inner peripheral face of the engaged portion  30 . 
     Moreover, although in the first and the second exemplary embodiments configuration is made with the indentation portions  67  formed to the press insertion portion  62  of the sleeve  54 , the present invention is not limited thereto and configuration may be made with the indentation portions  67  omitted. 
     In addition, various other modifications may be implemented in the present invention within a scope not departing from the spirit of the present invention. Moreover, it should be understood that the scope of rights of the present invention is not limited by the above exemplary embodiments.