Patent Publication Number: US-2013233958-A1

Title: Webbing retractor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC 119 from Japanese Patent Application No. 2012-052053 filed Mar. 8, 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 that a seatbelt device for a vehicle or the like is provided with. 
     2. Related Art 
     In the retractor for a seatbelt that is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 11-105671, a tubular retainer is mounted to one end portion of a bobbin, and the bobbin is supported so as to be able to rotate at a side plate of a retractor base via the retainer. One end side of the retainer projects-out further toward the outer side than the side plate of the retractor base, and one end portion of a torsion bar is anchored on the one end portion of the retainer. One end side of a torsionally deforming portion, that is provided at the intermediate portion of the torsion bar, is inserted through (inserted with play in) the inner side of the retainer, and the other end portion of the torsion bar is anchored at a locking base at the other end side of the bobbin. When this locking base is engaged with the retractor base by an emergency locking unit at the time of an emergency of the vehicle, rotation of the one end portion of the torsion bar is impeded. In this state, when the tension that is applied from the passenger to the webbing exceeds a predetermined value, the torsionally deforming portion of the torsion bar torsionally deforms, and due thereto, the bobbin rotates in the webbing pull-out direction, and a predetermined amount of the webbing is pulled out. Due thereto, the load on the passenger is reduced. 
     The length of the torsion bar being longer, the number of times of torsion of the above-described torsion bar increases. Therefore, in the above-described retractor for a seatbelt, the length of the torsion bar is made to be long by making the one end side of the torsion bar project-out further toward the outer side than the side plate of the retractor base. 
     In the above-described retractor for a seatbelt (webbing take-up device), when the bobbin (take-up shaft) is pulled by excessive tension that is applied to the webbing at the time of operating of the emergency locking unit, there is the possibility that the take-up shaft would tilt with respect to the retainer (torsion bar anchoring member) that is supported at the retractor base (frame). As a result, there is the possibility that the inner peripheral surface of the torsion bar anchoring member and the torsionally deforming portion of the torsion bar would interfere with one another. 
     SUMMARY OF THE INVENTION 
     The present invention is made in view of the above-described problem, and the present invention is to provide a webbing retractor that, even when a take-up shaft tilts with respect to a torsion bar anchoring member through which a torsionally deforming portion of a torsion bar is inserted, can make it such that the torsionally deforming portion does not interfere with the inner peripheral surface of the torsion bar anchoring member. 
     In order to overcome the above-described problem, a webbing retractor relating to an invention of a first aspect has: a take-up shaft that is rotatably supported at a frame, and that takes-up a webbing for restraining a passenger; a torsion bar, one end portion of which is connected to the take-up shaft so as to be unable to rotate relative to the take-up shaft, the torsion bar comprising a torsionally deforming portion, that is provided at an intermediate portion of the torsion bar, torsionally deforming when tension of a set value or more is applied to the webbing in a state in which another end portion of the torsion bar is connected to the frame via a rotation impeding mechanism; and a torsion bar anchoring member that is rotatably supported at the frame, and that includes an anchor portion at which the one end portion or the other end portion of the torsion bar is anchored, and an insert-through hole including an opening that is open at a side of the torsion bar anchoring member opposite a side at which the anchor portion is provided, through which the torsionally deforming portion is inserted in a state of not contacting an inner side of the insert-through hole, an inner diameter of the insert-through hole being enlarged at the opening side. 
     Note that “connect” recited in the first aspect includes a case of being connected directly and a case of being connected indirectly. 
     Similarly, “support” recited in the first aspect includes a case of being supported directly and a case of being supported indirectly. 
     Further, the invention of the first aspect includes a structure in which the one end portion of the torsion bar, that is anchored at the anchor portion of the torsion bar anchoring member, is connected via the torsion bar anchoring member to the take-up shaft so as to be unable to rotate relative thereto. 
     In the invention of the first aspect, at the time of rapid deceleration of the vehicle for example, the other end portion of the torsion bar is connected to the frame via the rotation impeding mechanism. In this state, when tension of the set value or more is applied from the passenger to the webbing, the intermediate portion (the torsionally deforming portion) of the torsion bar, whose one end portion is connected to the take-up shaft so as to be unable to rotate relative thereto, torsionally deforms, and, due thereto, the take-up shaft rotates in the webbing pull-out direction, and a predetermined amount of the webbing is pulled-out. Due thereto, the load on the passenger is decreased. 
     Here, in the present invention, in the state in which the other end portion of the torsion bar is connected to the frame as described above, when the take-up shaft is pulled by excessive tension applied to the webbing, there is the possibility that the take-up shaft will tilt with respect to the torsion bar anchoring member that is supported at the frame. The one end portion or the other end portion of the torsion bar is anchored at the anchor portion of this torsion bar anchoring member, and the torsionally deforming portion of the torsion bar is inserted-through the inner side of the insert-through hole of the torsion bar anchoring member in a non-contacting state. Therefore, due to the take-up shaft tilting with respect to the torsion bar anchoring member, the distance between the torsionally deforming portion of the torsion bar and the inner peripheral surface of the insert-through hole changes. This change in distance becomes large at the side of the torsion bar anchoring member that is opposite the anchor portion is provided, i.e., at the opening side of the insert-through hole. However, the inner diameter of the insert-through hole is enlarged at the opening side. Due thereto, it can be made such that the torsionally deforming portion of the torsion bar does not interfere with the inner peripheral surface of the insert-through hole of the torsion bar anchoring member. 
     In a webbing retractor relating to an invention of a second aspect, in the first aspect, the inner diameter of the insert-through hole is enlarged in a tapered shape toward the opening. 
     In the invention of the second aspect, the inner diameter of the insert-through hole of the torsion bar anchoring member is enlarged in a tapered shaped toward the opening of the insert-through hole, i.e., toward the side at which the change in the distance between the torsionally deforming portion of the torsion bar and the inner peripheral surface of the insert-through hole, at the time when the take-up shaft tilts with respect to the torsion bar anchoring member, becomes large. Due thereto, the rigidity of the torsion bar anchoring member can be ensured while interference between the torsionally deforming portion of the torsion bar and the inner peripheral surface of the insert-through hole is prevented well. 
     In a webbing retractor relating to an invention of a third aspect, in the first aspect or the second aspect, an outer diameter of the torsion bar anchoring member is enlarged at the opening side. 
     In the invention of the third aspect, the outer diameter of the torsion bar anchoring member is enlarged at the opening side of the insert-through hole, i.e., at the side where the inner diameter of the insert-through hole is enlarged (in a tapered shape). Due thereto, the rigidity of the torsion bar anchoring member, at the side at which the inner diameter of the insert-through hole is enlarged, can be improved. 
     In a webbing retractor relating to an invention of a fourth aspect, in any one of the first through third aspects, the torsion bar anchoring member is a structural member of the rotation impeding mechanism, and is mounted to the take-up shaft so as to be able to rotate relative to the take-up shaft, and the other end portion of the torsion bar is anchored at the anchor portion, and the rotation impeding mechanism is structured so as to, by connecting the torsion bar anchoring member and the frame, impede rotation of the torsion bar anchoring member in a webbing pull-out direction. 
     In the invention of the fourth aspect, due to the torsion bar anchoring member being connected to the frame at the time of rapid deceleration of the vehicle for example, rotation of the torsion bar anchoring member in the webbing pull-out direction is impeded. As a result, rotation in the webbing pull-out direction of the other end portion of the torsion bar, that is anchored to the anchor portion of the torsion bar anchoring member, is impeded. In this state, when tension of the set value or more is applied from the passenger to the webbing, the intermediate portion (the torsionally deforming portion) of the torsion bar, whose one end portion is connected to the take-up shaft so as to be unable to rotate relative thereto, torsionally deforms, and, due thereto, the take-up shaft rotates in the webbing pull-out direction, and a predetermined amount of the webbing is pulled-out. Due thereto, the load on the passenger is decreased. 
     It is possible in the third aspect that a length along an axial direction of a portion of the torsion bar anchoring member, at which the outer diameter is enlarged at the opening side, is substantially the same as a length along the axial direction of a portion of the torsion bar anchoring member, at which the inner diameter of the insert-through hole is enlarged at the opening side. 
     It is possible in the fourth aspect that a length along an axial direction of a portion of the torsion bar anchoring member, at which the outer diameter is enlarged at the opening side, is substantially the same as a length along the axial direction of a portion of the torsion bar anchoring member, at which the inner diameter of the insert-through hole is enlarged in the tapered shape toward the opening. 
     It is possible in the third aspect that a length along an axial direction of a portion of the torsion bar anchoring member, which portion is fit with the take-up shaft so as to rotate freely, is substantially the same as a length along the axial direction of a portion of the torsion bar anchoring member, at which the inner diameter of the insert-through hole is enlarged at the opening side. 
     It is possible in the first aspect that the other end portion of the torsion bar is anchored at the anchor portion of the torsion bar anchoring member, and the inner diameter of the insert-through hole is enlarged between the opening and the anchor portion. Further, it is possible that the inner diameter of the insert-through hole is enlarged in a tapered shape toward the opening from the anchor portion. 
     As described above, in the webbing retractor relating to the present invention, it can be made such that the torsionally deforming portion does not interfere with the inner peripheral surface of the torsion bar anchoring member, even when the take-up shaft tilts with respect to the torsion bar anchoring member through which the torsionally deforming portion of the torsion bar is inserted. 
    
    
     
       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 showing the structures of main portions of a webbing retractor relating to a first embodiment of the present invention; 
         FIG. 2  is an exploded perspective view showing the structure of a clutch mechanism that is a structural member of the webbing retractor; 
         FIG. 3  is an exploded perspective view showing the structure of a switching mechanism that is a structural member of the webbing retractor; 
         FIG. 4  is a drawing in which the clutch mechanism is viewed from a side opposite a spool; 
         FIG. 5A  is a drawing showing a state in which clutch plates of the clutch mechanism start to rotate toward a lock ring side, and  FIG. 5B  is a drawing showing a state in which the clutch plates are meshed with the lock ring; 
         FIG. 6A  is a cross-sectional view showing the structures of the spool, a sub torsion shaft, a sleeve and a screw of the webbing retractor, and  FIG. 6B  is a cross-sectional view showing a state in which the spool is tilted with respect to the sleeve; 
         FIG. 7  is a perspective view showing the structure of the sleeve; and 
         FIG. 8A  is a cross-sectional view showing the structures of a spool, a sub torsion shaft, a sleeve and a screw of a webbing retractor relating to a second embodiment of the present invention, and  FIG. 8B  is a cross-sectional view showing a state in which the spool is tilted with respect to the sleeve. 
     
    
    
     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. 7 . 
     As shown in  FIG. 1  through  FIG. 3 , the webbing retractor  10  relating to the present first embodiment has a frame  12 , a spool  20  that serves as a take-up shaft, a webbing  22 , a lock gear  24 , a main torsion shaft  32 , a trigger wire  40 , a sub torsion shaft  44  that serves as a torsion bar, a clutch mechanism  52 , and a switching mechanism  120 . The main torsion shaft  32  and the sub torsion shaft  44  structure a force limiter mechanism  31 , and the clutch mechanism  52  and the switching mechanism  120  structure a rotation impeding mechanism  27 . 
     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  33  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. 
     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 that are described later. 
     The webbing  22  is applied to the body of a passenger, and the proximal (base) end portion, that is a longitudinal direction one end portion thereof, 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 anchor 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  35  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  35  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 anchored portion  34  that is spline-shaped is formed at the longitudinal direction central portion of the main torsion shaft  32 . A second anchored 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 anchored portion  34  being fit-together with and anchored by the anchor portion  30  of the lock gear  24 , the main torsion shaft  32  is connected to the lock gear  24  so as to be able to rotate integrally therewith. Further, due to the second anchored portion  36  being fit-together with and anchored by an unillustrated anchor 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 the spool  20  so as to be able to rotate integrally therewith. 
     The proximal end portion of the main torsion shaft  32  (the end portion at the side opposite the second anchored portion  36 ) is rotatably supported at an unillustrated shaft-receiving hole that is formed in the sensor cover  35  (case) that is made of resin and that the locking mechanism  33  is provided with. The sensor cover  35  is mounted to the leg piece  18  of the frame  12 . Due thereto, the axial direction one side of the spool  20  is rotatably supported at the frame  12  via the main torsion shaft  32  and the sensor cover  35 . 
     The portion between the first anchored portion  34  and the second anchored 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 anchored portion  46  that is spline-shaped at least one portion thereof is formed at the proximal end portion (one end portion) of the sub torsion shaft  44 . A second anchored portion  48  that is similarly spline-shaped is formed at the distal end portion (other end portion) of the sub torsion shaft  44 . The first anchored portion  46  is fit-together with and anchored by an anchor portion  20 A (refer to  FIG. 6A ) 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 the spool  20  so as to be able to rotate integrally therewith. 
     Further, the portion between the first anchored portion  46  and the second anchored portion  48  at the sub torsion shaft  44  is structured as a second energy absorbing portion  50  (torsionally deforming portion) for absorbing the kinetic energy of the passenger that is used to pull the webbing  22  as is described later. 
     (Structure of Clutch Mechanism  52 ) 
     As shown in  FIG. 1  and  FIG. 2 , the clutch mechanism  52  has a sleeve  54  that serves as a torsion bar anchoring member, a clutch guide  64 , a clutch base  82 , a clutch cover  88 , a pair of clutch plates  100 , a screw  108 , and a pair of coil springs  98 . Note that a non-operating state of the clutch mechanism  52  is shown in  FIG. 4 . A state in the midst of operation of the clutch mechanism  52  is shown in  FIG. 5A , and a state after operation of the clutch mechanism  52  is completed is shown in  FIG. 5B . 
     The sleeve  54  is formed by cold forging, and is disposed coaxially to the sub torsion shaft  44 . An insert-through hole  56  that passes through in the axial direction is formed in the axially central portion of the sleeve  54 . The second energy absorbing portion  50  of the above-described sub torsion shaft  44  is inserted-through (inserted with play in) the insert-through hole  56  in a state of non-contact. Further, an anchor portion  58  that is spline-shaped is formed at the distal end side (the arrow F direction side in  FIG. 1  and  FIG. 2 ) at the inner peripheral portion of the sleeve  54 . Due to the second anchored portion  48  of the sub torsion shaft  44  being fit-together with and anchored by the anchor portion  58 , the sleeve  54  is connected to the sub torsion shaft  44  so as to be able to rotate integrally therewith. 
     As shown in  FIG. 6A  and  FIG. 7 , an opening  56 A side, that is at the side opposite the anchor portion  58 , of the insert-through hole  56  of the sleeve  54  is made to be a tapered enlarged diameter portion  56 B. At this tapered enlarged diameter portion  56 B, the inner diameter of the insert-through hole  56  is enlarged in a tapered shaped toward the opening  56 A (the proximal end side of the sleeve  54 ). Due thereto, the interval (distance) between the outer peripheral surface of the second energy absorbing portion  50  of the sub torsion shaft  44  and the inner peripheral surface of the insert-through hole  56  is structured so as to gradually increase toward the opening  56 A. Note that, in the present embodiment, the length of the tapered enlarged diameter portion  56 B along the axial direction of the sleeve  54  is set to be about ⅓ of the axial direction length of the sleeve  54 . The tapered enlarged diameter portion  56 B is formed simultaneously at the time when the sleeve  54  is formed by cold forging. Note that, in  FIG. 6A  and  FIG. 6B , illustration of the main torsion shaft  32  and the like is omitted for easy viewing of the drawings. 
     Further, the proximal end side of the sleeve  54  is structured as a support portion  60  that has a cylindrical-tube-shaped outer peripheral surface. The supporting portion  60  is fit-together with the through-hole  21  of the spool  20  so as to rotate freely. A step portion  20 B is formed such that the through-hole  21  is expanded in the form of a step at the axial direction other end side of the spool  20 . Due to the supporting portion  60  (the proximal end portion of the sleeve  54 ) abutting this step portion  20 B, relative displacement of the sleeve  54  toward the axial direction one side with respect to the spool  20  is restricted. Note that, in the present embodiment, the length of the supporting portion  60  along the axial direction of the sleeve  54  is set to be substantially equal to the length of the tapered enlarged diameter portion  56 B along the axial direction of the sleeve  54  (around ⅓ of axial direction length of the sleeve  54 ). 
     Moreover, the 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. This press-fit portion  62  is formed to have a smaller diameter than the supporting portion  60 , and a step portion is formed between the press-fit portion  62  and the supporting portion  60 . Namely, the outer diameter of the sleeve  54  at the proximal end side (the opening  56 A side) is made to be large, and the inner periphery of this region where the outer diameter is made to be large (the supporting portion  60 ) is made to be the tapered enlarged diameter portion  56 B. 
     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. 4 , 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-fit hole  85  that is shaped as a regular hexagon in cross-section is formed in the base main body  84 . The press-fit portion  62  of the above-described sleeve  54  is press-fit into this press-fit 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-fit 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-fit 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. 5B  and a non-operation position shown in  FIG. 4 . 
     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  (pawls) 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 ). 
     As shown in  FIG. 1  and  FIG. 2 , the screw  108  has a screw portion  110 , and a pushing portion  112  that has a larger diameter than the screw portion  110 . As shown in  FIG. 6A , 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  (the arrow F direction) is limited, and the sleeve  52  is pushed against the step portion  20 B of the spool  20  by the pushing portion  112  of the screw  108 . Therefore, the sleeve  54  is mounted without play (backlash) to the spool  20 . Further, in this state, axial direction movement of the clutch guide  64  is limited by the clutch cover  88  and the spool  20 . (Note that, in  FIG. 6A  and  FIG. 6B , illustration of members other than the sleeve  54  and the screw  108  among the structural members of the clutch mechanism  52  is omitted.) 
     Further, a connecting portion  111  that is spline-shaped is provided at the screw  108  at the side of the pushing portion  112  opposite the side at which the screw portion  110  is located. This connecting portion  111  is provided coaxially to the screw portion  110 . The connecting portion  111  is fit into a connecting hole  115  of an adapter  113  that is disposed at the side of the switching mechanism  120  (see  FIG. 3 ) that is described later, which side is opposite the side at which the leg piece  16  of the frame  12  is located. The adapter  113  is rotatably supported at a spring cover  117  that is made of resin. The spring cover  117  is mounted to the leg piece  16  of the frame  12  via a body  122  of the switching mechanism  120 . Due thereto, the axial direction other side of the spool  20  is rotatably supported at the frame  12  via the sub torsion shaft  44 , the sleeve  54 , the screw  108 , the adapter  113 , the spring cover  117  and the body  122 . Note that the other end portion of an unillustrated spiral spring, whose one end portion is anchored on the spring cover  117 , is anchored on the above-described adapter  113 , and the spool  20  is urged in the take-up direction by this spiral spring. 
     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. 4 ) 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. 3 , 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  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. 3 ). 
     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. 
     (Operation) 
     The operation and effects of the present first embodiment are described next. 
     In the webbing retractor of the above-described structure, 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. 5A ), 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. 5B ). 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 , i.e., the other end portion of the sub torsion shaft  44  (the second anchored portion  48 ), 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. 
     Here, in the present embodiment, in the state in which rotation, in the pull-out direction, of the other end portion of the sub torsion shaft  44  (the second anchored portion  48 ) is impeded, i.e., in the state in which the second anchored portion  48  of the sub torsion shaft  44  is connected to the frame  12  via the rotation impeding mechanism  27  (the clutch mechanism  52  and the switching mechanism  120 ), when the spool  20  is pulled by excessive tension that is applied to the webbing  22 , there is the possibility that the spool  20  will tilt with respect to the sleeve  54  that is supported at the frame  12  via the rotation impeding mechanism  27 . 
     Namely, the sleeve  54  is usually mounted to the spool  20  without play, but, when the length of the second energy absorbing portion  50  of the sub torsion shaft  44  increases slightly due to the second energy absorbing portion  50  torsionally deforming, there may be a case in which a slight gap arises between the supporting portion  60  of the sleeve  54  and the step portion  20 B of the spool  20 . Therefore, as shown in  FIG. 6B , there is the possibility that the spool  20  will tilt with respect to the sleeve  54  due to pulling force T from the webbing  22 . In this case, the distance between the second energy absorbing portion  50  of the sub torsion shaft  44  and the inner peripheral surface of the insert-through hole  56  changes. This change in distance is large at the opening  56 A side of the insert-through hole  56 , but the inner diameter of the insert-through hole  56  is enlarged at the opening  56 A side. Due thereto, it is possible to make it such that the second energy absorbing portion  50  of the sub torsion shaft  44  does not interfere with the inner peripheral surface of the insert-through hole  56  of the sleeve  54 . 
     In other words, even in a case in which the length of the second energy absorbing portion  50  disposed within the insert-through hole  56  becomes long by setting the length of the sub torsion shaft  44  to be long, interference between the second energy absorbing portion  50  and the inner peripheral surface of the insert-through hole  56  can be prevented by the tapered enlarged diameter portion  56 B of the sleeve  54 . Due thereto, the number of times of torsion (number of times of twisting) of the sub torsion shaft  44  can be increased. Further, because the diameter of the second energy absorbing portion  50  can be made to be large, a high torsional torque can be obtained. 
     Moreover, in the present embodiment, the inner diameter of the insert-through hole  56  of the sleeve  54  is enlarged in a tapered shape toward the opening  56 A side of the insert-through hole  56 . Due thereto, the rigidity of the sleeve  54  can be ensured while interference between the second energy absorbing portion  50  of the sub torsion shaft  44  and the inner peripheral surface of the insert-through hole  56  is prevented well. Namely, in a case in which the inner diameter of the insert-through hole  56  is enlarged in a stepped form, there is the possibility that stress will concentrate at the step portion. However, in the present embodiment, concentration of stress such as that described above can be avoided due to the tapered enlarged diameter portion  56 B. 
     Further, in the present embodiment, the sleeve  54 , at which the inner diameter of the insert-through hole  56  is enlarged in a tapered shape at the opening  56 A side, is formed (molded) by forging. Therefore, a cutting process for enlarging the inner diameter of the insert-through hole  56  in a tapered shape is not needed. Due thereto, a decrease in the cost of the sleeve  54  can be achieved. 
     Moreover, in the present embodiment, at the sleeve  54 , the opening  56 A side is made to be the supporting portion  60  at which the outer diameter is greater than that of the press-fit portion  62 , and, at the side where the inner diameter of the insert-through hole  56  is enlarged, the outer diameter is enlarged. Due thereto, the angle of inclination of the tapered enlarged diameter portion  56 B can be set to be large, while ensuring the rigidity of the sleeve  54  at the side where the inner diameter of the insert-through hole  56  is enlarged. Therefore, interference between the torsionally deforming portion  50  and the inner peripheral surface of the insert-through hole  56  can be prevented well. 
     Another embodiment of the present invention is described next. Note that structures and operations that are basically similar to those of the above-described first embodiment are denoted by the same reference numerals as in the first embodiment, and description thereof is omitted. 
     Second Embodiment  
     The partial structure of a webbing retractor relating to a second embodiment of the present invention is shown in cross-sectional views in  FIG. 8A  and  FIG. 8B . In this embodiment, the structure of a sleeve  54 ′ is slightly different than that of the sleeve  54  relating to the above-described first embodiment. This sleeve  54 ′ has a structure that is basically similar to that of the sleeve  54 , but the entire region of the sleeve  54 ′ between the anchor portion  58  and the opening  56 A (preferably, between the opening  56 A side end (or the vicinity thereof) of the anchor portion  58  and the opening  56 A) is made to be enlarged diameter portion, preferably, to be a tapered enlarged diameter portion  56 B′. The length of the tapered enlarged diameter portion  56 B′ along the axial direction of the sleeve  54 ′ is set to be larger than that of the tapered enlarged diameter portion  56 B relating to the above-described first embodiment. 
     Supplementary Description of the Embodiments  
     The above-described respective embodiments describe cases in which the present invention is applied to the sleeve  54 ,  54 ′ (torsion bar anchoring member) at which the second anchored portion  48  (other end portion) of the sub torsion shaft  44  (torsion bar) is anchored. However, the present invention is not limited to the same, and may be applied to the retainer (torsion bar anchoring member) disclosed in JP-A No. 11-105671 that is described in the Related Art. In this case, the locking base, at which the other end portion of the torsion bar in that publication is anchored, and the emergency locking unit are made to be the rotation impeding mechanism. 
     Further, the above-described respective embodiments are structured such that the outer diameter of the sleeve  54 ,  54 ′ (torsion bar anchoring member) is enlarged at the opening  56 A side. However, the present invention is not limited to the same, and the shape of the torsion bar anchoring member can be changed appropriately. 
     Further, although the above-described respective embodiments are structured such that the inner diameter of the insert-through hole  56  is enlarged in a tapered shape toward the opening  56 , the present invention is not limited to the same, and may be structured such that the inner diameter of the insert-through hole is enlarged in a stepped form toward the opening (for example, having a single step portion or plural step portions that are enlarged gradually toward the opening). 
     In addition, the present invention can be implemented by changed in various ways within a scope that does not deviate from the gist thereof Further, the scope of the right of the present invention is, of course, not limited to the above-described embodiments.