Retractor for seat belt

Abstract

To provide a retractor for a seat belt that can prevent falling off of an energization member from a winding drum without impairing assemblability.SOLUTION: A retractor for a seat belt includes a winding drum, a lock member 61, an energization member 9A and a shaft member 9. The lock member 61 is arranged at a first end part of the winding drum. The energization member 9A has one end part 9a to be installed at the first end part of the winding drum, other end part 9b to be installed at the lock member 61 and a connection part 9c connecting the one end part 9a with the other end part 9b. The shaft member 9B has a shaft part 91 coaxial with the winding drum and an arm 92 extending outward in a radial direction from the shaft part 91. The arm 92 can make contact with the connection part 9c of the energization member 9A from the opposite side of the winding drum.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a seat belt retractor that prevents the webbing from being pulled out in an emergency such as a vehicle collision. [Background technology]

[0002] 2. Description of the Related Art There has been known a seat belt retractor that prevents the webbing from being pulled out in the event of a vehicle emergency. In the seat belt retractor, a take-up drum that takes up the webbing is rotatably housed between a pair of side walls of a housing.

[0003] For example, Patent Document 1 discloses a seat belt retractor in which a locking member (referred to as a "locking plate" in Patent Document 1) is provided at a first end of the winding drum on one side of the axial direction of the winding drum to prevent the winding drum from rotating in the pull-out direction in the event of a vehicle emergency.

[0004] Specifically, in the seat belt retractor of Patent Document 1, the winding drum includes a drum body and a locking base (referred to as a "lock base" in Patent Document 1) attached to one end surface of the drum body, and a locking member is attached to the locking base so as to be capable of swinging.

[0005] In addition, in the seatbelt retractor of Patent Document 1, the drum body is hollow, the take-up drum includes a torsion bar disposed inside the drum body, and the torsion bar passes through the locking base. A return spring is attached to the tip of the torsion bar that protrudes outward beyond the locking base. The return spring biases the locking member to maintain the disengaged position that allows rotation of the take-up drum in the pull-out direction.

[0006] The housing has internal teeth formed on one side wall, and the locking member has a plurality of engagement teeth that can engage with the internal teeth. In the event of a vehicle emergency, the locking member moves against the biasing force of the return spring to an engagement position that prevents the rotation of the take-up drum in the unwinding direction, and the engagement teeth of the locking member engage with the internal teeth formed on one side wall of the housing.

[0007] The return spring includes a spiral spring portion attached to the tip of the above-mentioned torsion bar, a locking portion attached to a guide projection provided on the locking member, and an arm portion connecting the spring portion and the locking portion.

[0008] Furthermore, in the seat belt retractor of Patent Document 1, a thin, circular lock cover is attached to the locking base to prevent the locking member from falling off. This lock cover has a larger diameter than the locking base and also serves to prevent the return spring from falling off. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 4118667 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in a structure in which a large lock cover is used to prevent the return spring, which is a biasing member, from falling off the winding drum, as in the seat belt retractor of Patent Document 1, the worker cannot visually check the biasing member after attaching the lock cover, which makes assembly work less efficient. In addition, there is also the problem that a large lock cover has a lot of wasted space.

[0011] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a seat belt retractor that can prevent the biasing member from falling off the take-up drum without impairing the ease of assembly. [Means for solving the problem]

[0012] The present invention relates to a housing including a pair of side walls opposed to each other, a take-up drum that takes up a webbing and is accommodated between the pair of side walls so as to be rotatable in a take-up direction and an unwinding direction of the webbing, a locking member that is provided at a first end of the take-up drum on one side in the axial direction of the take-up drum, and that is movable between an engagement position where the take-up drum engages with the housing or a member attached to the housing to prevent rotation of the take-up drum in the unwinding direction and a disengagement position where the take-up drum is permitted to rotate in the unwinding direction, and that is moved to the engagement position in the event of a vehicle emergency, and a locking member that is attached to the first end of the take-up drum. the locking member has one end attached to a first end of the take-up drum, the other end attached to the locking member, and a connecting portion connecting the one end and the other end, and the biasing member biases the locking member to maintain the locking member in the disengaged position; a shaft member attached to a first end of the take-up drum and having a shaft portion coaxial with the take-up drum; and a cover member attached to the housing and rotatably supporting the shaft portion of the shaft member, the shaft member having an arm extending radially outward from the shaft portion, and the arm being capable of contacting the connecting portion of the biasing member from the side opposite the take-up drum. Effect of the Invention

[0013] According to the present invention, there is provided a seat belt retractor that can prevent the urging member from falling off the take-up drum without impairing the efficiency of assembly. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view of a seat belt retractor according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an exploded perspective view of the seat belt retractor shown in FIG. [Diagram 3] FIG. 2 is a cross-sectional view of the seat belt retractor shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 4 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 2 is an exploded perspective view of a portion of the winding drum. [Figure 7] 4 is an exploded perspective view of the remainder of the winding drum, a biasing member, a shaft member, and a guide member. FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. 2 is a cross-sectional view of the drive wheel and the locking base. [Figure 11] FIG. 4 is an exploded perspective view of a locking base and a locking member. [Figure 12] 13 is an exploded perspective view of the locking base and the locking member as viewed from the opposite side. FIG. [Figure 13] 8 is a perspective view of the shaft member as viewed from the opposite side to that in FIG. 7. [Figure 14] 13 is a cross-sectional view of the shaft member and the locking base at a position passing through the arm of the shaft member. FIG. [Figure 15] 1A shows the state of the urging member when the locking member is in the disengaged position, and FIG. 1B shows the state of the urging member when the locking member is in the engaged position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1 and 2 show a seat belt retractor 1 according to one embodiment of the present invention. This seat belt retractor 1 prevents a webbing 10, which is a seat belt, from being pulled out in the event of an emergency such as a vehicle collision.

[0016] Specifically, the seat belt retractor 1 includes a housing 2, a winding spring unit 1A, a winding drum 1B, a pretensioner 1C, and a lock unit 1D. The housing 2 includes a first side wall 21 and a second side wall 22 opposed to each other in the axial direction of the winding drum 1B.

[0017] The winding drum 1B winds up the webbing 10, and is housed between a first side wall 21 and a second side wall 22 so as to be rotatable in the winding direction and the unwinding direction of the webbing 10.

[0018] The housing 2 includes a back plate 23 perpendicular to the first side wall 21 and the second side wall 22, which is formed by sheet metal processing together with the first side wall 21 and the second side wall 22. Hereinafter, for convenience of explanation, the axial direction of the winding drum 1B will be referred to as the left-right direction (the side on the first side wall 21 side will be referred to as the left side, and the other side on the second side wall 22 side will be referred to as the right side), and the thickness direction of the back plate 23 will be referred to as the front-rear direction (the side of the side walls 21, 22 will be referred to as the front side, and the opposite side will be referred to as the rear side). As illustrated in Figs. 1 and 2, one of the directions perpendicular to the left-right direction and the front-rear direction will be referred to as the up direction, and the other will be referred to as the down direction.

[0019] The lower and upper parts of the front edges of the first and second side walls 21 and 22 of the housing 2 are connected to each other by connecting bars 24 and 25. The first and second side walls 21 and 22 are provided with openings 21a and 22a, respectively, through which the winding drum 1B is inserted. In addition, the back plate 23 is provided with an opening 23a through which the winding drum 1B is exposed.

[0020] A winding spring unit 1A is attached to the second side wall 22 of the housing 2, and a pretensioner 1C is attached to the first side wall 21. A lock unit 1D is attached to the pretensioner 1C.

[0021] The winding drum 1B includes a drum body 3, a locking base 6 disposed to the left of the drum body 3 and rotatable relative to the drum body 3 in the event of a vehicle emergency, and an annular (see FIG. 3) drive wheel 5 attached to the locking base 6. That is, the locking base 6 constitutes the left end (first end on one side in the axial direction) of the winding drum 1B. The drive wheel 5 is also a component of a pretensioner 1C.

[0022] As shown in Fig. 3, the drum body 3 has a first end face 31 on the first side wall 21 side of the housing 2 and a second end face 32 on the second side wall 22 side. In this embodiment, the drum body 3 has a shaft portion 33 protruding rightward from the second end face 32, and this shaft portion 33 is rotatably supported by the winding spring unit 1A. However, a torsion bar 4A described later may pass through the drum body 3, and a right end portion of this torsion bar 4A may be rotatably supported by the winding spring unit 1A. Note that the configuration of the winding spring unit 1A is known, so a detailed description thereof will be omitted.

[0023] The winding drum 1B includes, in addition to the above-mentioned drum body 3, locking base 6, and drive wheel 5, a bush 3A, a bearing 3B, a torsion bar 4A, an impact energy absorbing wire 4B, and a stopper member 4C, as shown in Figures 6 and 7. A biasing member 9A and a shaft member 9B are attached to the locking base 6 that constitutes the left end portion of the winding drum 1B.

[0024] The bush 3A and the bearing 3B are emergency means for smoothly rotating the take-up drum 1B even if the relative position of the take-up drum 1B with respect to the housing 2 is shifted in the event of a vehicle emergency. As shown in Fig. 3, the bush 3A is attached to the right end portion located within the opening 22a of the second side wall 22 of the drum body 3, and the bearing 3B is attached to the left end portion located within the opening 21a of the first side wall 21 of the drum body 3. Furthermore, the bearing 3B includes a folded-back portion 3Ba (see Fig. 6) folded back inwardly at the left end portion of the drum body 3, which slides against the drive wheel 5 attached to the locking base 6 so as not to rotate relative to it when the drum body 3 and the locking base 6 rotate relative to each other.

[0025] The drum body 3 has a central hole 30 extending along the central axis of the drum body 3. In this embodiment, the central hole 30 has a bottom and is open only to the first end face 31. However, when the torsion bar 4A penetrates the drum body 3 as described above, the central hole 30 may be open not only to the first end face 31 but also to the second end face 32.

[0026] The torsion bar 4A is inserted into a central hole 30 of the drum body 3. The locking base 6 described above is disposed so as to face a first end surface 31 of the drum body 3. One end of the torsion bar 4A opposite the locking base 6 is connected to the drum body 3 so as not to rotate relative to the drum body 3, and the other end is connected to the locking base 6 so as not to rotate relative to the drum body 3.

[0027] More specifically, one end and the other end of the torsion bar 4A are provided with spline-shaped coupling parts 41 and 42, respectively. A spline-shaped recess for coupling with the coupling part 41 is provided at the bottom of the central hole 30 of the drum body 3, and the coupling part 41 fits into this recess.

[0028] When the pull-out force of the webbing 10 exceeds a predetermined value while the rotation of the locking base 6 in the pull-out direction is prevented, the torsion bar 4A undergoes plastic deformation, absorbing impact energy while allowing relative rotation between the drum body 3 and the locking base 6.

[0029] The impact energy absorbing wire 4B absorbs impact energy at the initial stage when the drum body 3 and the locking base 6 rotate relative to each other. In this embodiment, as shown in Fig. 8, the drum body 3 is provided with two slots 35 that open to the first end face 31. In this embodiment, each slot 35 is a groove that is obliquely recessed from the outer circumferential surface of the drum body 3, but the slots 35 may be holes that extend in the axial direction of the drum body 3.

[0030] The impact energy absorbing wire 4B is housed in one of the slots 35 with its head 43 (see FIG. 6) protruding from the opening 36 of the slot 35. The impact energy absorbing wire 4B is pulled out from the opening 36 while undergoing plastic deformation during relative rotation between the drum body 3 and the locking base 6, and absorbs impact energy. The impact energy absorbing wire 4B can be omitted.

[0031] The stopper member 4C determines the allowable amount of relative rotation between the drum body 3 and the locking base 6 when the torsion bar 4A absorbs impact energy. The stopper member 4C is held within the central hole 30 of the drum body 3 so as to be unable to rotate relative to the drum body 3 but movable in the left-right direction.

[0032] 6, the stopper member 4C is tubular, through which the torsion bar 4A is inserted. A female screw 47 is formed on the inner peripheral surface of the stopper member 4C.

[0033] In this embodiment, the stopper member 4C includes an annular portion 45 and three claw portions 46 protruding rightward from the annular portion 45. Meanwhile, three guide grooves 34 are provided in the central hole 30 of the drum body 3. The three claw portions 46 are fitted into the three guide grooves 34, respectively, so that the stopper member 4C is held on the drum body 3 so as to be unable to rotate relative to the drum body 3 and to be movable in the left-right direction. However, instead of the stopper member 4C including the claw portions 46, the cross-sectional shape of the outer shape of the stopper member 4C and the cross-sectional shape of the left end portion of the central hole 30 of the drum body 3 may be polygonal.

[0034] 3 and 7, the locking base 6 is formed with a male thread 73 into which the female thread 47 of the stopper member 4C screws. In this embodiment, as shown in Fig. 3, when the drum body 3 and the locking base 6 rotate relative to each other, the stopper member 4C moves from a position separated from the drive wheel 5 to a position abutting the drive wheel 5, thereby restricting the relative rotation between the drum body 3 and the locking base 6 to a predetermined amount.

[0035] As shown in Figures 7 and 9, the drive wheel 5 includes a main body portion 51 having a mating hole with a hexagonal cross-section, a plurality of teeth 52 formed on the outer peripheral surface of the main body portion 51, an annular flange 53 protruding radially outward from the main body portion 51 to the right of the teeth 52, and a ring-shaped rib 55 protruding to the right from the flange 53.

[0036] The flange 53 is provided with a plurality of (six in the illustrated example) holding grooves 54. The head 43 of the impact energy absorbing wire 4B described above is attached to one of these holding grooves 54. The head 43 of the impact energy absorbing wire 4B has a retaining portion 44 (see FIG. 6) that is wider than the holding groove 54.

[0037] 3, in this embodiment, the driving wheel 5 abuts against the first end surface 31 of the drum body 3 via a rib 55. The impact energy absorbing wire 4B is wound around the rib 55 and pulled out from the opening 36 of the slot 35. When the drum body 3 and the locking base 6 rotate relatively, the driving wheel 5, which is attached to the locking base 6 so as not to rotate relatively, rotates relative to the drum body 3 while the rib 55 of the driving wheel 5 contacts the first end surface 31 of the drum body 3 in the axial direction of the drum body 3 and the outer periphery of the flange 53 of the driving wheel 5 contacts the folded-back portion 3Ba of the bearing 3B attached to the drum body 3 in the radial direction of the drum body 3.

[0038] Furthermore, an annular flange 56 protrudes from the inner peripheral surface of the main body 51. This flange 56 is the portion that comes into contact with the stopper member 4C. By making the stopper member 4C come into contact with the flange 56 of the driving wheel 5 instead of the stepped portion of the locking base 6 in this manner, a large contact area with the stopper member 4C can be ensured.

[0039] The pretensioner 1C rotates the take-up drum 1B in the take-up direction in the event of a vehicle emergency. As shown in Figures 2 to 4, the pretensioner 1C includes a pretensioner casing 11 attached to a first side wall 21 of the housing 2, a pipe 12 extending while bending from the pretensioner casing 11, a moving member 13 disposed within the pipe 12, and a gas generator 18 disposed within an end portion of the pipe 12.

[0040] In this embodiment, the moving member 13 is rod-shaped and is plastically deformed by being bitten into by the teeth 52 of the drive wheel 5. However, the moving member 13 may be composed of a plurality of divided bodies (for example, spheres) arranged at the same pitch as the teeth 52 of the drive wheel 5. In the event of a vehicle emergency, the moving member 13 engages with the teeth 52 of the drive wheel 5 while being pushed out of the pipe 12 by the gas generated by the gas generator 18, causing the drive wheel 5 to rotate in the winding direction. As the drive wheel 5 rotates, the locking base 6, the torsion bar 4A, and the drum body 3 also rotate. After the pretensioner 1C is activated, the moving member 13 is prevented from being pushed back into the pipe 12 by the pressure of the gas in the pipe 12, and therefore the drive wheel 5 is prevented from rotating in the pull-out direction.

[0041] 2 and 5, the pretensioner casing 11 is provided with an opening 11a through which the locking base 6 is inserted, and internal teeth 11b are formed on the periphery of the opening 11a. Meanwhile, the locking base 6 is provided with a locking member 61 that can engage with the internal teeth 11b. In the event of a vehicle emergency, the locking member 61 engages with the internal teeth 11b to prevent rotation of the locking base 6 in the pull-out direction.

[0042] 10 to 12, the locking base 6 includes a first base member 7 to which the drive wheel 5 is attached, and a second base member 8 attached to the first base member 7 on the opposite side of the drum body 3 to the first base member 7 so as to be non-rotatable relative to the first base member 7. The locking member 61 is held between the first base member 7 and the second base member 8.

[0043] More specifically, the first base member 7 has a disk-shaped first main body portion 71 and a protruding portion 72 protruding rightward from the first main body portion 71. As shown in FIG. 3, the drive wheel 5 is disposed between the first main body portion 71 and the first end face 31 of the drum body 3, and the protruding portion 72 penetrates the drive wheel 5. The root portion of the protruding portion 72 is formed in a hexagonal cross section, and this root portion fits into a fitting hole in the main body portion 51 of the drive wheel 5, which also has a hexagonal cross section, so that the drive wheel 5 is attached to the first base member 7 so as not to rotate relative to the first base member 7. In addition, the male thread 73 described above is formed on the outer circumferential surface on the tip side of the protruding portion 72.

[0044] Furthermore, the first base member 7 is provided with a first recess 74 recessed from the tip surface of the protruding portion 72, and a second recess 75 recessed from the surface of the first main body portion 71 opposite the driving wheel 5 on the same axis as the first recess 74. The first recess 74 is a spline-shaped recess for coupling with the coupling portion 42 of the torsion bar 4A, and the coupling portion 42 fits into the first recess 74. The second recess 75 has a circular cross section in this embodiment. In this embodiment, the first base member 7 has a partition 76 separating the first recess 74 and the second recess 75. In other words, the first recess 74 and the second recess 75 have bottoms.

[0045] The second base member 8 has a plate-shaped second body portion 81 that overlaps with the first body portion 71, and a fitting protrusion 82 that protrudes rightward from the second body portion 81. In this embodiment, the second body portion 81 is provided with three engagement recesses 87, and the three engagement protrusions 79 provided on the first body portion 71 engage with the engagement recesses 87, respectively, so that the second base member 8 is attached to the first base member 7 in a manner that prevents relative rotation. The cross-sectional shape of the fitting protrusion 82 is circular, and the fitting protrusion 82 fits into the second recess 75. However, the second recess 75 and the fitting protrusion 82 may have a non-circular cross-sectional shape, and the fitting protrusion 82 may fit into the second recess 75, so that the second base member 8 is attached to the first base member 7 in a manner that prevents relative rotation. In this case, the engagement recesses 87 and the engagement protrusions 79 can be omitted.

[0046] Furthermore, in this embodiment, the second main body portion 81 of the second base member 8 is provided with three crimping projections 85 protruding to the right, while the first main body portion 71 of the first base member 7 is provided with three through holes 77 through which the crimping projections 85 are inserted. A crimping recess 78 is formed on the opposite side of the first main body portion 71 from the second main body portion 81, the crimping recess 78 being coaxial with the through hole 77 and having a larger diameter than the through hole 77. The portion of each crimping projection 85 protruding from the through hole 77 is crimped in the crimping recess 78 to a larger diameter than the through hole 77 (in FIGS. 11 and 12, the crimping projections 85 are depicted in a shape before crimping).

[0047] The locking member 61 has a plate-like, substantially arc-shaped main body portion 62 held by the first main body portion 71 of the first base member 7 and the second main body portion 81 of the second base member 8, a plurality of engagement teeth 63 (three in the illustrated example) formed on the outer surface of the main body portion 62 and engageable with the above-mentioned internal teeth 11b, and an operating shaft 64 protruding leftward from the main body portion 62. In other words, the operating shaft 64 is parallel to the axial direction of the winding drum 1B. The operating shaft 64 is operated by a guide member 14 (see FIGS. 2 and 7).

[0048] The locking member 61 is movable between a disengaged position shown in Fig. 15(a) where the rotation of the winding drum 1B in the pull-out direction is permitted, and an engaged position shown in Fig. 15(b) where the rotation of the winding drum 1B in the pull-out direction is prevented. The locking member 61 is moved between the disengaged position and the engaged position by the guide member 14.

[0049] The second main body portion 81 of the second base member 8 of the locking base 6 is provided with an attachment protrusion 84 that protrudes leftward from the second main body portion 81. That is, the attachment protrusion 84 protrudes leftward from the left end portion of the winding drum 1B. The above-mentioned urging member 9A is hung between the attachment protrusion 84 and the operating shaft 64 of the locking member 61.

[0050] In this embodiment, the biasing member 9A is a return spring having a substantially arcuate shape as shown in Fig. 7. Specifically, the biasing member 9A has one end 9a attached to the attachment projection 84, the other end 9b attached to the operating shaft 64 of the locking member 61, and a connecting portion 9c connecting the one end 9a and the other end 9b. The biasing member 9A biases the locking member 61 so as to maintain it in the disengaged position shown in Fig. 15(a).

[0051] 7 and 13, the above-mentioned shaft member 9B has a shaft portion 91 coaxial with the winding drum 1B and an arm 92 extending radially outward from the shaft portion 91. The cross-sectional shape of the right side (base end side) portion of the shaft portion 91 is hexagonal.

[0052] On the other hand, the second base member 8 of the locking base 6 is provided with a fitting hole 83 that is coaxial with the fitting protrusion 82 and opens to the left, as shown in Fig. 11. In this embodiment, as shown in Fig. 12, the fitting hole 83 penetrates the second base member 8 and also opens to the right. The cross-sectional shape of the fitting hole 83 is hexagonal. The right portion of the shaft portion 91 of the shaft member 9B fits into this fitting hole 83.

[0053] 3, a left side (tip side) portion of shaft portion 91 of shaft member 9B penetrates guide member 14 and rotatably supports guide member 14. In addition, a left end (tip) portion of shaft portion 91 located to the left of guide member 14 is rotatably supported by a cover member 17 of lock unit 1D, which will be described later.

[0054] As shown in FIG. 7, the arm 92 of the shaft member 9B can contact the connecting portion 9c of the urging member 9A from the side opposite to the winding drum 1B. As shown in FIG. 14, between the second main body portion 81 of the second base member 8 and the arm 92, there is a gap larger than the thickness of the connecting portion 9c of the urging member 9A in the axial direction of the winding drum 1B. For example, the cross-sectional diameter of the connecting portion 9c is about 1.0 mm, and the gap between the second main body portion 81 of the second base member 8 and the arm 92 is about 1.5 mm. In this way, a movement space for the urging member 9A is secured between the second base member 8, which is a part of the winding drum 1B, and the arm 92 of the shaft member 9B, so that the operation of the lock member 61 is not hindered.

[0055] A hook 93 extending to the right is provided at the tip of the arm 92. Meanwhile, an engagement hole 86 (see Figs. 11 and 12) with which the hook 93 engages is provided in the second main body portion 81 of the second base member 8. The engagement hole 86 extends in a direction perpendicular to the extension direction of the arm 92. As shown in Fig. 13, a pair of engagement claws 95 protruding in the width direction of the hook 93 is formed at the tip of the hook 93, and as shown in Fig. 12, a pair of first recesses 88 are provided on both sides of the engagement hole 86 in the longitudinal direction on the right side of the engagement hole 86. When the hook 93 is inserted into the engagement hole 86 and the pair of engagement claws 95 engage with the first recesses 88, the arm 92 is prevented from moving to the left and the hook 93 is prevented from coming out of the engagement hole 86.

[0056] 13, the arm 92 is provided with an intermediate protrusion 94 that protrudes from the arm 92 toward the second main body portion 81 of the second base member 8 at a position between the shaft portion 91 and the hook 93. When the shaft member 9B is attached to the second base member 8, the tip of the intermediate protrusion 94 abuts against the main body portion 81 of the second base member. Since the connecting portion 9c of the urging member 9A is disposed between this intermediate protrusion 94 and the hook 93 (see FIGS. 15(a) and (b)), unexpected movement of the urging member 9A to both sides in the radial direction of the take-up drum 1B can be prevented.

[0057] 13, the hook 93 is provided with a pair of tip projections 96 projecting toward the shaft portion 91 on the base end side of the hook 93 relative to the engaging claws 95, and a second recess 89 recessed toward the fitting hole 83 side is provided on the left side of the engaging hole 86 as shown in FIGS. 10 and 14. When the shaft member 9B is attached to the second base member 8, there is a slight gap (for example, 0.1 to 0.2 mm) between the right side of the tip projection 96 and the bottom of the second recess 89, but when the arm 92 is bent and the hook 93 moves to the right, the right side of the tip projection 96 can abut against the bottom of the second recess 89 in the axial direction of the winding drum 1B. That is, the tip projection 96 functions as an abutment portion with the locking base 6.

[0058] In this way, not only does the tip of the intermediate projection 94 abut against the main body portion 81 of the second base member, but the right side of the tip projection 96 also abuts against the bottom of the second recess 89, so that the gap between the second main body portion 81 of the second base member 8 and the arm 92 in the axial direction of the winding drum 1B is maintained in a state larger than the thickness of the connecting portion 9c of the urging member 9A in the axial direction of the winding drum 1B. Furthermore, with such a structure, the strength required for the arm 92 can be reduced, and the shaft member 9B can be made smaller and lighter.

[0059] 2, the lock unit 1D includes a cover member 17 that houses the guide member 14 and the vehicle sensor 16. The cover member 17 is attached to the first side wall 21 of the housing 2 via the above-mentioned pretensioner casing 11 as shown in FIG.

[0060] The guide member 14 is provided with a webbing sensor 15. The webbing sensor 15 is activated when the webbing 10 is suddenly pulled out, thereby preventing the guide member 14 from rotating in the pull-out direction. The vehicle sensor 16 is activated when there is a large change in the acceleration of the vehicle, thereby preventing the guide member 14 from rotating in the pull-out direction.

[0061] When the rotation of the guide member 14 in the pull-out direction is prevented, the locking base 6 rotates together with the drum main body 3 relative to the guide member 14, and the operating shaft 64 of the locking member 61 is operated in the guide hole 14a (see FIG. 7) of the guide member 14, whereby the locking member 61 moves from the disengaged position shown in FIG. 15(a) to the engaged position shown in FIG. 15(b) against the biasing force of the biasing member 9A. As a result, the locking member 61 engages with the internal teeth 11b of the pretensioner casing 11, and the rotation of the take-up drum 1B (of which, in this embodiment, the locking base 6) in the pull-out direction is prevented.

[0062] As described above, in the seat belt retractor 1 of this embodiment, by attaching the shaft member 9B to the locking base 6 constituting the left end of the winding drum 1B, the arm 92 located on the opposite side of the winding drum 1B with respect to the connecting portion 9c of the urging member 9A prevents the urging member 9A from falling off the winding drum 1B. Moreover, since the urging member 9A is not entirely covered by the arm 92, during the assembling work, a worker can visually check the urging member 9A or hold the urging member 9A with his / her fingers so as not to move it. Therefore, it is possible to prevent the urging member 9A from falling off the winding drum 1B without impairing the workability of the assembly.

[0063] In addition, in this embodiment, the mounting protrusion 84 of the locking base 6 and the operating shaft 64 of the locking member 61 face in the same direction, and one end 9a and the other end 9b of the urging member 9A can be attached to the take-up drum 1B and the locking member 61 from the same direction, making it easy to install the urging member 9A.

[0064] Furthermore, in this embodiment, the shaft member 9B can be attached to the winding drum 1B by inserting the shaft portion 91 of the shaft member 9B into the fitting hole 83 of the winding drum 1B. Moreover, since the attachment direction of the shaft member 9B is the same as the direction in which the arm 92 of the shaft member 9B can come into contact with the connecting portion 9c of the urging member 9A, the attachment work of the shaft member 9B is facilitated.

[0065] In addition, in this embodiment, the hook 93 of the shaft member 9B can prevent unexpected movement of the urging member 9A radially outward of the winding drum 1B, and the intermediate protrusion 94 of the shaft member 9B can prevent unexpected movement of the urging member 9A radially inward of the winding drum 1B.

[0066] <Modification> The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0067] For example, the torsion bar 4A may be omitted, and the locking base 6 may be integrated with the drum body 3.

[0068] In addition, the pretensioner 1C may be omitted. In this case, internal teeth 11b may be formed on the periphery of the opening 21a of the first side wall 21 of the housing 2, and the locking member 61 may engage with the internal teeth 11b in the event of a vehicle emergency.

[0069] Moreover, the urging member 9A does not necessarily have to be a substantially arc-shaped spring, and may be a tension coil spring having one end attached to the left end of the winding drum 1B and the other end attached to the locking member 61. In this case, the connecting portion is a coil portion, and the coil portion is stretched when the locking member 61 moves from the non-engaged position to the engaged position. Alternatively, the urging member 9A may be a compression coil spring having one end attached to the left end of the winding drum 1B and the other end attached to the locking member 61. In this case, the connecting portion is a coil portion, and the coil portion is compressed when the locking member 61 moves from the non-engaged position to the engaged position.

[0070] In addition, the hook 93 of the shaft member 9B does not necessarily need to be provided with a tip protrusion 96 as an abutment portion, and the tip of the hook 93 can be used as an abutment portion and abut against the first main body portion 71 of the first base member 7 in the axial direction of the winding drum 1B, whereby the gap between the second main body portion 81 of the second base member 8 and the arm 92 in the axial direction of the winding drum 1B can be maintained in a state larger than the thickness of the connecting portion 9c of the urging member 9A in the axial direction of the winding drum 1B.

[0071] <Summary> As a first aspect, the present disclosure provides a seatbelt retractor including a housing including a pair of side walls facing each other, a take-up drum rotatably accommodated between the pair of side walls in a take-up direction and a draw-out direction of the webbing for taking up the webbing, a locking member provided at a first end on one axial side of the take-up drum in the axial direction of the take-up drum, movable between an engagement position that engages with the housing or a member attached to the housing to prevent rotation of the take-up drum in the draw-out direction and a non-engagement position that allows rotation of the take-up drum in the draw-out direction, and moved to the engagement position in an emergency of the vehicle, a biasing member having one end attached to the first end of the take-up drum, the other end attached to the locking member, and a connecting portion connecting the one end and the other end, and biasing the locking member to maintain the non-engagement position, a shaft member attached to the first end of the take-up drum and having a shaft portion coaxial with the take-up drum, and a cover member attached to the housing and rotatably supporting the shaft portion of the shaft member, wherein the shaft member has an arm extending radially outward from the shaft portion, and the arm can contact the connecting portion of the biasing member from the side opposite to the take-up drum.

[0072] According to the above configuration, by attaching the shaft member to the first end of the take-up drum, the arm located on the side opposite to the take-up drum with respect to the connecting portion of the biasing member prevents the biasing member from falling off the take-up drum. Moreover, since not all of the biasing member is covered by the arm, it is possible for an operator to visually check the biasing member or hold it with a finger to prevent it from moving during the assembly operation. Therefore, it is possible to prevent the biasing member from falling off the take-up drum without impairing the workability of the assembly operation.

[0073] As a second aspect, the seat belt retractor according to the first aspect may further include a guide member rotatably supported on a shaft portion of the shaft member to move the locking member between the engaged position and the disengaged position, the locking member includes an operating shaft parallel to the axial direction of the winding drum and operated by the guide member, a first end of the winding drum is provided with an attachment protrusion protruding from the first end to one side in the axial direction of the winding drum, one end of the biasing member is attached to the attachment protrusion, and the other end of the biasing member is attached to the operation shaft. According to this configuration, the one end and the other end of the biasing member can be attached to the winding drum and the locking member from the same direction, making it easy to attach the biasing member.

[0074] As a third aspect, in the first or second aspect, a fitting hole that opens to one side in the axial direction of the winding drum is provided at the first end of the winding drum, and the shaft portion of the shaft member may be fitted into the fitting hole. According to this configuration, the shaft member can be attached to the winding drum by inserting the shaft portion of the shaft member into the fitting hole of the winding drum. Moreover, since the mounting direction of the shaft member is the same as the direction in which the arm of the shaft member can contact the connecting portion of the biasing member, the installation work of the shaft member is easy.

[0075] As a fourth aspect, in any of the first to third aspects, the shaft member may have a hook extending from a tip of the arm to the other side in the axial direction of the winding drum, and an engagement hole with which the hook engages may be provided at a first end of the winding drum. With this configuration, the hook of the shaft member can prevent unexpected movement of the urging member radially outward of the winding drum.

[0076] As a fifth aspect, in the fourth aspect, the arm may be provided with an intermediate protrusion that protrudes from the arm toward the winding drum and has a connection portion of the urging member disposed between the arm and the hook. With this configuration, the intermediate protrusion of the shaft member can prevent unexpected movement of the urging member radially inward of the winding drum.

[0077] As a sixth aspect, in any of the first to fifth aspects, a gap larger than a thickness of the connecting portion of the urging member may be provided between the first end of the winding drum and the arm of the shaft member. With this configuration, a movement space for the urging member is secured between the winding drum and the arm of the shaft member, so that the operation of the locking member is not hindered.

[0078] As a seventh aspect, in the sixth aspect, the hook of the shaft member is provided with an abutment portion capable of abutting against a first end of the winding drum in the axial direction of the winding drum, and a gap in the axial direction of the winding drum between the first end of the winding drum and the arm of the shaft member when the intermediate protrusion of the arm and the abutment portion of the hook abut against the first end of the winding drum may be larger than a thickness in the axial direction of the winding drum of the connecting portion of the urging member. According to this configuration, the intermediate protrusion and the abutment portion of the shaft member abut against the first end of the winding drum, thereby ensuring a movement space for the urging member between the winding drum and the arm of the shaft member, thereby reducing the strength required for the arm and enabling the shaft member to be made smaller and lighter.

[0079] As an eighth aspect, in any of the first to seventh aspects, for example, the above-mentioned seat belt retractor includes a pretensioner casing attached to the housing, and further includes a pretensioner that rotates the winding drum in the winding direction in the event of a vehicle emergency, and the locking member may engage with the pretensioner casing. [Explanation of symbols]

[0080] 1 Seat belt retractor 1B Winding drum 1C Pretensioner 14 Guide member 17 Cover member 2. Housing 21,22 side wall 6 Locking base (first end of winding drum) 61 Locking member 64 Operation axis 83 Fitting hole 84 Mounting protrusion 86 Engagement hole 9A Pressurizing member 9a One end 9b Other end 9c Connecting part 9B Shaft member 91 Shaft 92 Arm 93 Hook 94 Middle protrusion 96 Tip protrusion (contact part)

Claims

1. a housing including a pair of opposing side walls; a winding drum that winds up the webbing and is accommodated between the pair of side walls so as to be rotatable in a winding direction and a pulling-out direction of the webbing; a locking member provided at a first end of the winding drum on one side in the axial direction of the winding drum, movable between an engagement position where the locking member engages with the housing or a member attached to the housing to prevent rotation of the winding drum in the pull-out direction and a disengagement position where the locking member allows rotation of the winding drum in the pull-out direction, and moved to the engagement position in the event of a vehicle emergency; a biasing member having one end attached to a first end of the winding drum, another end attached to the locking member, and a connecting portion connecting the one end and the other end, the biasing member biasing the locking member to maintain the locking member in the disengaged position; a shaft member attached to a first end of the winding drum and having a shaft portion coaxial with the winding drum; a cover member attached to the housing and rotatably supporting a shaft portion of the shaft member, The shaft member has an arm extending radially outward from the shaft portion, the arm being capable of contacting the connecting portion of the urging member from the side opposite the take-up drum.

2. a guide member rotatably supported on a shaft portion of the shaft member to move the locking member between the engaged position and the disengaged position, The locking member includes an operating shaft that is operated by the guide member and is parallel to an axial direction of the winding drum, A mounting protrusion is provided at a first end of the winding drum and protrudes from the first end to one side in an axial direction of the winding drum, 2. The seat belt retractor according to claim 1, wherein one end of the biasing member is attached to the mounting projection, and the other end of the biasing member is attached to the operating shaft.

3. 3. The seat belt retractor according to claim 1, wherein a fitting hole is provided at a first end of the winding drum, the fitting hole opening to one side in the axial direction of the winding drum, and the shaft portion of the shaft member is fitted into the fitting hole.

4. the shaft member has a hook extending from a tip of the arm to the other side in the axial direction of the winding drum, 3. The seat belt retractor according to claim 1, wherein the first end of the winding drum is provided with an engagement hole with which the hook is engaged.

5. 5. The seat belt retractor according to claim 4, wherein the arm is provided with an intermediate protrusion that protrudes from the arm toward the take-up drum and has a connection portion of the urging member disposed between the intermediate protrusion and the hook.

6. 3. The seat belt retractor according to claim 1, wherein a gap larger than a thickness of the connecting portion of the biasing member is provided between the first end of the winding drum and the arm of the shaft member.

7. 7. The seat belt retractor of claim 6, wherein the hook of the shaft member is provided with an abutment portion capable of abutting against a first end of the winding drum in the axial direction of the winding drum, and when the intermediate protrusion of the arm and the abutment portion of the hook abut against the first end of the winding drum, a gap in the axial direction of the winding drum between the first end of the winding drum and the arm of the shaft member is larger than a thickness in the axial direction of the winding drum of the connecting portion of the urging member.

8. a pretensioner including a pretensioner casing attached to the housing, the pretensioner rotating the winding drum in the winding direction in the event of a vehicle emergency; 3. The seat belt retractor according to claim 1, wherein the locking member engages with the pretensioner casing.

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