Retractor for seat belt

Abstract

To provide a retractor for a seat belt that allows for fine adjustment of a drawing amount of webbing during impact energy absorption in an arrangement that uses an impact energy absorbing wire.SOLUTION: A retractor for a seat belt includes a winding drum, a rocking base 4D and at least one impact energy absorbing wire 4B. The winding drum and the rocking base 4D are connected by an impact energy absorbing member, and at least one slot for the impact energy absorbing wire 4B is provided in the winding drum. Three or more holding parts 54 spaced apart from each other in a circumferential direction about the rotation center of the winding drum are provided in the locking base 4D, the number of the holding parts 54 being greater than the number of the slots. A head part 43 of the impact energy absorbing wire 4B is installed in at least one of these holding parts 54.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a seat belt retractor that can absorb impact energy of an occupant while the webbing is being pulled out in an emergency such as a vehicle collision, and can limit the amount of webbing that is pulled out. [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 that includes a torsion bar, which is an impact energy absorbing member, and an impact energy absorbing wire formed in a substantially U-shape (referred to as a "bending element" in Patent Document 1).

[0004] Specifically, in the seat belt retractor of Patent Document 1, a winding drum (referred to as a "spindle" in Patent Document 1) has a central hole that opens to one end surface, and a locking base (referred to as a "tread head" in Patent Document 1) is disposed so as to face one end surface of the winding drum. A torsion bar is inserted into the central hole of the winding drum, and one end side opposite the locking base is connected to the winding drum so as not to rotate relative thereto, and the other end side is connected to the locking base so as not to rotate relative thereto. In the event of a vehicle emergency, the torsion bar absorbs impact energy by plastic deformation due to twisting.

[0005] Furthermore, the winding drum is provided with two storage grooves that open on one end surface facing the locking base, spaced 180 degrees apart around the center of rotation of the winding drum. The roughly U-shaped impact energy absorbing member includes both end portions that are parallel to each other and a central portion that connects the both end portions, and both end portions are respectively accommodated in the storage grooves of the winding drum with the base end portions of the both end portions on the central portion side projecting out. Meanwhile, the locking base is provided with two through holes as holding portions, and the base end portions of both end portions of the impact energy absorbing wire are inserted and attached into these through holes. In the event of a vehicle emergency, both end portions of the impact energy absorbing wire are pulled out of the storage grooves while undergoing plastic deformation, and absorb impact energy.

[0006] Furthermore, Patent Document 2 discloses a seat belt retractor that includes, in addition to a torsion bar and one impact energy absorbing wire (referred to as an "energy absorbing pin" in Patent Document 2), a stopper member that determines the allowable amount of relative rotation between the winding drum (referred to as a "spool" in Patent Document 2) and the locking base when the torsion bar absorbs impact energy.

[0007] The stopper member is held within the center hole of the winding drum so as to be unable to rotate relative to the winding drum but movable in the axial direction of the winding drum. The locking base has a shaft portion coaxial with the winding drum, and a male thread is formed on the outer circumferential surface of this shaft portion, with the stopper member screwed onto this male thread. In the event of a vehicle emergency, the stopper member restricts the relative rotation between the winding drum and the locking base to a predetermined amount. This limits the amount of webbing that can be pulled out, preventing the occupant from moving forward more than a predetermined distance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5339042 [Patent Document 2] JP 2020-104777 A Summary of the Invention [Problem to be solved by the invention]

[0009] When a seat belt retractor includes a stopper member as in Patent Document 2, it is desirable to adjust the initial position of the stopper member in the axial direction of the winding drum to adjust the amount of webbing pulled out when absorbing impact energy. However, in the structure of Patent Document 2, the impact energy absorbing wire extends across the winding drum and the locking base, so the mounting angle of the locking base relative to the winding drum cannot be changed. Note that, without the impact energy absorbing wire, the initial position of the stopper member in the axial direction of the winding drum can be adjusted by changing the mounting angle of the locking base relative to the winding drum.

[0010] Therefore, it may be considered to provide the locking base of Patent Document 2 with two retaining portions spaced 180 degrees apart, like the locking base of the seat belt retractor of Patent Document 1. However, in this case, the mounting angle of the locking base relative to the winding drum can only be changed by 180 degrees, and the amount of webbing pulled out cannot be finely adjusted.

[0011] SUMMARY OF THE PRESENT DISCLOSURE ... In view of the above, an object of the present invention is to provide a seat belt retractor using an impact energy absorbing wire, which is capable of finely adjusting the amount of webbing pulled out when impact energy is absorbed. [Means for solving the problem]

[0012] The present invention relates to a housing including a pair of side walls opposed to each other, a winding drum that winds up a webbing and is accommodated between the pair of side walls to be rotatable in a winding direction and an unwinding direction of the webbing, the winding drum having a center hole that opens to at least one end face, a locking base that is arranged to face the one end face of the winding drum and is prevented from rotating in the unwinding direction in the event of a vehicle emergency, the locking base having a male thread formed on an outer circumferential surface of a shaft portion that is coaxial with the winding drum, an impact energy absorbing member that is coupled to the winding drum at one end and to the locking base at the other end, so as to connect the winding drum and the locking base so as to be rotatable together under normal conditions, and that plastically deforms when the unwinding force of the webbing exceeds a predetermined value in a state in which rotation of the locking base in the unwinding direction is prevented, thereby absorbing impact energy while allowing relative rotation between the winding drum and the locking base, and a shock energy absorbing member provided on the winding drum in front of the winding drum. The present invention provides a seat belt retractor comprising: at least one impact energy absorbing wire that is housed in at least one slot that opens onto the one end surface, with a head portion that protrudes from the opening of the slot being attached to the locking base, and that is pulled out from the opening while undergoing plastic deformation when the winding drum and the locking base rotate relative to each other to absorb impact energy; and a stopper member that is held within the central hole so as to be unable to rotate relative to the winding drum but able to move in the axial direction of the winding drum, and that screws into the male thread of the locking base to determine the allowable amount of relative rotation between the winding drum and the locking base when the impact energy absorbing member absorbs impact energy, wherein the locking base is provided with three or more retaining portions that are spaced apart from each other in the circumferential direction around the center of rotation of the winding drum and that are greater than the number of the slots, and a head portion of the at least one impact energy absorbing wire is attached to at least one of these retaining portions. Effect of the Invention

[0013] According to the present invention, in a configuration using an impact energy absorbing wire, a seat belt retractor is provided that is capable of finely adjusting the amount of webbing pulled out when impact energy is absorbed. [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. 4 is an exploded perspective view of a portion of the take-up drum unit. [Figure 7] FIG. 4 is an exploded perspective view of the remainder of the take-up drum unit and a synchronizing gear. [Figure 8] FIG. [Figure 9] FIG. 4 is a cross-sectional view of the locking base. [Figure 10] FIG. [Figure 11] FIG. 2 is an exploded perspective view of a locking base body and a locking member. [Figure 12] 13 is an exploded perspective view of a locking base body and a locking member as viewed from the opposite side. FIG. [Figure 13] 1A shows the state of the return spring when the locking member is in the disengaged position, and FIG. 1B shows the state of the return spring 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 unit 1B, a pretensioner 1C, and a lock unit 1D. The winding drum unit 1B includes a winding drum 3 that winds up the webbing 10, and the housing 2 includes a first side wall 21 and a second side wall 22 that face each other in the axial direction of the winding drum 3.

[0017] The winding drum 3 is accommodated between the first side wall 21 and the second side wall 22 so as to be rotatable in the winding direction and the pull-out direction of the webbing 10. 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. For convenience of explanation, the axial direction of the winding drum 3 will be referred to as the left-right direction (the first side wall 21 side will be referred to as the left, and the second side wall 22 side will be referred to as the right), and the thickness direction of the back plate 23 will be referred to as the front-rear direction (the side walls 21, 22 side will be referred to as the front, and the opposite side will be referred to as the rear). As shown 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.

[0018] 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 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 3 is inserted. In addition, the back plate 23 is provided with an opening 23a through which the winding drum 3 is exposed.

[0019] 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.

[0020] As shown in Fig. 3, the winding drum 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 winding drum 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, which is an impact energy absorbing member 4A described later, may penetrate the winding drum 3, and a right end portion of this torsion bar may be rotatably supported by the winding spring unit 1A. Note that the configuration of the winding spring unit 1A is publicly known, so a detailed description thereof will be omitted.

[0021] In addition to the winding drum 3, the winding drum unit 1B includes a bushing 3A, a bearing 3B, an impact energy absorbing member 4A, an impact energy absorbing wire 4B, a stopper member 4C, a locking base 4D, a return spring 9A, and a rotating shaft 9B, as shown in Figures 6 and 7.

[0022] The locking base 4D is disposed so as to face the first end surface 31 of the winding drum 3, and is prevented from rotating in the pull-out direction in the event of a vehicle emergency. The locking base 4D includes a locking base main body 6 and a drive wheel 5 attached to the locking base main body 6.

[0023] The bush 3A and the bearing 3B are emergency means for smoothly rotating the winding drum 3 even if the relative position of the winding drum 3 with respect to the housing 2 is displaced in the event of a vehicle emergency. As shown in Fig. 3, the bush 3A is attached to the right end portion of the winding drum 3 located within the opening 22a of the second side wall 22, and the bearing 3B is attached to the left end portion of the winding drum 3 located within the opening 21a of the first side wall 21. Furthermore, the bearing 3B includes a folded-back portion 3Ba (see Fig. 6) folded back inwardly at the left end portion of the winding drum 3, which slides against the drive wheel 5 when the winding drum 3 and the locking base 4D rotate relatively to each other.

[0024] The winding drum 3 has a central hole 30 extending along the central axis of the winding drum 3. In this embodiment, the central hole 30 has a bottom and is open only to the first end face 31. However, as described above, when a torsion bar which is the impact energy absorbing member 4A penetrates the winding drum 3, the central hole 30 may be open not only to the first end face 31 but also to the second end face 32.

[0025] In this embodiment, the impact energy absorbing member 4A is a torsion bar inserted into the central hole 30 of the winding drum 3. One end of the impact energy absorbing member 4A opposite the locking base 4D is connected to the winding drum 3 so as to be non-rotatable relative to the winding drum 3, and the other end is connected to the locking base 4D so as to be non-rotatable relative to the winding drum 3.

[0026] More specifically, one end and the other end of the impact energy absorbing member 4A, which is a torsion bar, are provided with spline-shaped coupling parts 41, 42. A spline-shaped recess for coupling with the coupling part 41 is provided at the bottom of the central hole 30 of the winding drum 3, and the coupling part 41 fits into this recess.

[0027] The impact energy absorbing member 4A normally connects the take-up drum 3 and the locking base 4D so that they can rotate together, and when the pull-out force of the webbing 10 exceeds a predetermined value while rotation of the locking base 4D in the pull-out direction is prevented, it plastically deforms to absorb impact energy while allowing relative rotation between the take-up drum 3 and the locking base 4D.

[0028] The impact energy absorbing wire 4B absorbs impact energy at the initial stage when the winding drum 3 and the locking base 4D rotate relative to each other. In this embodiment, as shown in Fig. 8, the winding drum 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 winding drum 3, but the slots 35 may be holes that extend in the axial direction of the winding drum 3.

[0029] 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 head 43 of the impact energy absorbing wire 4B is attached to the locking base 4D. When the winding drum 3 and the locking base 4D rotate relative to each other, the impact energy absorbing wire 4B is pulled out from the opening 36 while undergoing plastic deformation, and absorbs impact energy.

[0030] The stopper member 4C determines the allowable amount of relative rotation between the winding drum 3 and the locking base 4D when the impact energy absorbing member 4A absorbs impact energy. The stopper member 4C is held within the center hole 30 of the winding drum 3 so as to be unable to rotate relative to the winding drum 3 and to be movable in the left-right direction.

[0031] 6, the stopper member 4C is tubular, into which the impact energy absorbing member 4A, which is a torsion bar, is inserted. A female screw 47 is formed on the inner peripheral surface of the stopper member 4C.

[0032] In this embodiment, the stopper member 4C can be inserted into the central hole 30 of the winding drum 3 in a plurality of mounting positions rotated at a predetermined angular interval α. More specifically, the stopper member 4C includes an annular portion 45 and three claw portions 46 protruding to the right from the annular portion 45. Meanwhile, three guide grooves 34 are provided in the central hole 30 of the winding drum 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 winding drum 3 so as not to rotate relative to the winding drum 3 and to be movable in the left-right direction. In addition, since the three claw portions 46 and the three guide grooves 34 are provided at equal angular intervals, the stopper member 4C can be inserted into the central hole 30 of the winding drum 3 at any angular position as long as the positions of the claw portions 46 and the guide grooves 34 match. That is, the above-mentioned predetermined angular interval α is 120 degrees, and the number of mounting positions of the stopper member 4C is three.

[0033] However, the number of claw portions 46 and guide grooves 34 can be changed, and in this case, the predetermined angular interval α and the number of mounting positions of the stopper member 4C change according to the number of claw portions 46 and guide grooves 34. Also, 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 winding drum 3 may be polygonal. Alternatively, the stopper member 4C may be inserted into the central hole 30 of the winding drum 3 in only one mounting position.

[0034] 3 and 9, the locking base 4D has a shaft portion 72a that protrudes rightward from the drive wheel 5 and is coaxial with the winding drum 3, and a male thread 73 that screws into the female thread 47 of the stopper member 4C is formed on the outer circumferential surface of this shaft portion 72a. In this embodiment, as shown in Fig. 3, when the winding drum 3 and the locking base 4D rotate relative to each other, the stopper member 4C moves from a position separated from the drive wheel 5 to a position in contact with the drive wheel 5, thereby restricting the relative rotation between the winding drum 3 and the locking base 4D to a predetermined amount.

[0035] As shown in Figures 7 and 10, 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] 3, the flange 53 of the drive wheel 5 faces the first end face 31 of the winding drum 3. The flange 53 is provided with a plurality of holding portions 54 that are spaced apart from each other in the circumferential direction about the rotation center of the winding drum 3. The number of holding portions 54 is greater than the number of the slots 35 described above, and is three or more.

[0037] In this embodiment, six holding portions 54 are provided at equal angular intervals. In other words, the angular interval β at which the holding portions 54 are spaced apart from one another is 60 degrees. The head 43 of the above-mentioned impact energy absorbing wire 4B is attached to one of these holding portions 54. As described above, in this embodiment, the angular interval α regarding the mounting posture of the stopper member 4C is 120 degrees, so the angular interval β of the holding portions 54 is smaller than the angular interval α.

[0038] In this embodiment, each of the retaining portions 54 is a groove that opens radially outward. The head 43 of the impact energy absorbing wire 4B has a retaining portion 44 (see FIG. 6) that is located on the opposite side of the flange 53 from the winding drum 3 and is larger than the width of the groove that is the retaining portion 54.

[0039] 3, in this embodiment, the drive wheel 5 abuts against the first end face 31 of the winding drum 3 via a rib 55. The impact energy absorbing wire 4B is pulled out from the opening 36 of the slot 35 while being wound around the rib 55. When the winding drum 3 and the locking base 4D rotate relatively to each other, the winding drum 3 and the drive wheel 5 rotate relatively while the rib 55 of the drive wheel 5 contacts the first end face 31 of the winding drum 3 in the axial direction of the winding drum 3 and the outer periphery of the flange 53 of the drive wheel 5 contacts the folded-back portion 3Ba of the bearing 3B attached to the winding drum 3 in the radial direction of the winding drum 3.

[0040] 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 main body 6 in this manner, a large contact area with the stopper member 4C can be ensured.

[0041] In the event of a vehicle emergency, the pretensioner 1C rotates the take-up drum 3 in the take-up direction via the drive wheel 5, the locking base main body 6, and the impact energy absorbing member 4A. 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.

[0042] In this embodiment, the moving member 13 is rod-shaped and is plastically deformed by the engagement of 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 main body 6, the impact energy absorbing member A, and the winding drum 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.

[0043] 2 and 5, the pretensioner casing 11 is provided with an opening 11a through which the locking base body 6 is inserted, and internal teeth 11b are formed on the periphery of the opening 11a. Meanwhile, the locking base body 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 4D in the pull-out direction.

[0044] 9, 11 and 12, the locking base body 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 first base member 7 from the winding drum 3 so as to be relatively unrotatable. The lock member 61 is held between the first base member 7 and the second base member 8.

[0045] 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 winding drum 3, and the protruding portion 72 penetrates the drive wheel 5. A portion of the protruding portion 72 to the right of the flange 56 of the drive wheel 5 constitutes the above-mentioned shaft portion 72a of the locking base 4D.

[0046] The base portion of the protrusion 72 is formed to have a hexagonal cross section, and this base portion fits into a fitting hole in the main body 51 of the drive wheel 5, which also has a hexagonal cross section, thereby attaching the drive wheel 5 to the first base member 7 so as not to rotate relative to the first base member 7. In addition, the outer circumferential surface of the tip side of the protrusion 72 is formed with the male thread 73 described above.

[0047] 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 impact energy absorbing member 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.

[0048] 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.

[0049] 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 and to an outer diameter substantially equal to the inner diameter of the crimping recess 78 (in FIGS. 11 and 12, the crimping projections 85 are depicted in a shape before crimping).

[0050] The locking member 61 has a generally arc-shaped, plate-like 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 example) formed on the outer surface of the main body portion 62 which can engage with the above-mentioned internal teeth 11b, and an operating shaft 64 protruding to the left from the main body portion 62.

[0051] A pin 84 protruding to the left is provided on the second main body portion 81 of the second base member 8. The above-mentioned return spring 9A is substantially arc-shaped as shown in Fig. 7, and one end of the return spring 9A engages with the operating shaft 64 of the locking member 61, and the other end engages with the pin 84. The return spring 9A plays a role in maintaining the locking member 61 in the non-engaged position shown in Fig. 13(a).

[0052] Furthermore, the second base member 8 is provided with an engagement hole 83 that opens to the left coaxially with the fitting protrusion 82. In this embodiment, the engagement hole 83 penetrates the second base member 8 and also opens to the right. The cross-sectional shape of the engagement hole 83 is hexagonal.

[0053] The locking member 61 is operated by the synchronous gear 14 (see Figs. 2 and 7). As shown in Fig. 2, the locking unit 1D includes a cover member 17 that houses the synchronous gear 14 and the vehicle sensor 16. The synchronous gear 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 synchronous gear 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 synchronous gear 14 from rotating in the pull-out direction.

[0054] When the rotation of the synchronous gear 14 in the pull-out direction is prevented, the locking base 4D rotates relative to the synchronous gear 14 together with the winding drum 3, and the operating shaft 64 of the locking member 61 is operated by the guide hole 14a (see Figure 7) of the synchronous gear 14, thereby moving the locking member 61 from the disengaged position shown in Figure 13(a) to the engaged position shown in Figure 13(b).

[0055] The above-mentioned rotating shaft 9B has a rod-shaped main body 91 and an arm 92 extending radially outward from the main body 91, as shown in Fig. 7. The cross-sectional shape of the right side portion of the main body 91 is hexagonal, and this right side portion fits into and engages with an engagement hole 83 of the second base member 8. The arm 92 is for holding down the return spring 9A, and a hook 93 provided at the tip of the arm 92 engages with an engagement hole 86 provided in the second main body 81 of the second base member 8. The left side portion of the rotating shaft 9B penetrates the synchronizer gear 14, as shown in Fig. 3, and is rotatably supported by the cover member 17 of the lock unit 1D.

[0056] As described above, in the seat belt retractor 1 of this embodiment, the locking base 4D is provided with more holding portions 54 for the impact energy absorbing wire 4B than the number of slots 35, so that it is possible to select which holding portion 54 the impact energy absorbing wire 4B is to be attached to. Moreover, since three or more holding portions 54 are provided, it is possible to change the mounting angle of the locking base 4D with respect to the winding drum 3 by an angle less than 180 degrees (60 degrees in this embodiment). In other words, by selecting the holding portion 54 to which the impact energy absorbing wire 4B should be attached, it is possible to adjust the initial position of the stopper member 4C at a pitch according to the angular interval of the holding portions 54. Therefore, it is possible to finely adjust the amount of pull-out of the webbing 10 when absorbing impact energy.

[0057] Furthermore, in this embodiment, the interval at which the mounting angle of the stopper member 4C relative to the winding drum 3 is changed is 120 degrees, while the interval at which the mounting angle of the locking base 4D relative to the winding drum 3 is changed when one of the six retaining portions 54 is aligned with the opening 36 of the slot 35 is 60 degrees, the latter being smaller than the former.

[0058] Incidentally, the holding portion 54 does not necessarily have to be a groove, and may be a through hole. However, if the holding portion 54 is a through hole, the impact energy absorbing wire 4B needs to be passed through the through hole over almost the entire length, which makes assembly time-consuming. In contrast, since the holding portion 54 is a groove in this embodiment, the holding portion 54 can be formed more easily than when the holding portion 54 is a through hole. Moreover, since the impact energy absorbing wire 4B can be inserted into the holding portion 54 from the radial outside of the flange 53, the impact energy absorbing wire 4B can be easily attached to the holding portion 54.

[0059] Furthermore, in this embodiment, the head 43 of the impact energy absorbing wire 4B has the retaining portion 44, which prevents the impact energy absorbing wire 4B from being axially removed from the holding portion 54. Therefore, the impact energy absorbing wire 4B can be reliably pulled out from the opening 36 by the relative rotation between the winding drum 3 and the locking base 4D.

[0060] <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.

[0061] For example, the number of slots 35 provided in the winding drum 3 may be one or three or more. Furthermore, when there are multiple slots 35, there may also be multiple impact energy absorbing wires 4B. In this case, the number of impact energy absorbing wires 4B may be the same as the number of slots 35, or may be less than the number of slots 35.

[0062] Furthermore, the impact energy absorbing member 4A is not limited to a torsion bar, so long as it absorbs impact energy due to the relative rotation between the winding drum 3 and the locking base 4D. For example, the impact energy absorbing member 4A may be a wire that is bent and deformed due to the relative rotation between the winding drum 3 and the locking base to absorb impact energy.

[0063] The configuration of the locking base 4D can be changed as appropriate. For example, the drive wheel 5 may be integrated with the first base member 7 of the locking base main body 6. Alternatively, the locking base 4D may include a separate member located on the winding drum 3 side with respect to the drive wheel 5, and this separate member may be provided with three or more holding parts 54. In contrast, if the drive wheel 5 is provided with three or more holding parts 54 as in the above embodiment, the dimensions of the retractor in the axial direction of the winding drum 3 can be made smaller than when the locking base 4D includes a member having a holding part 54 in addition to the drive wheel 5. Moreover, if the drive wheel 5 is provided with the holding part 54, the number of parts does not increase and there is little backlash between the parts, so the energy absorption load is stable.

[0064] The pretensioner 1C and the drive wheel 5 may be omitted. In this case, the first base member 7 may be provided with a flange facing the first end face 31 of the take-up drum 3, and this flange may be provided with three or more holding portions 54. Furthermore, when the pretensioner 1C is not provided, internal teeth 11b may be formed on the periphery of the opening 21a of the first side wall 21 of the housing 2, and a locking member 61 may engage with the internal teeth 11b in the event of a vehicle emergency.

[0065] Furthermore, external teeth may be formed on the locking base 4D, and a locking member that engages with the external teeth may be provided on the first side wall 21 of the housing 2.

[0066] <Summary> As a first aspect, the present disclosure provides a vehicle safety device including a housing including a pair of side walls opposed to each other, a winding drum that winds up a webbing and is accommodated between the pair of side walls to be rotatable in a winding direction and an unwinding direction of the webbing, the winding drum having a center hole that opens to at least one end face, a locking base that is arranged to face the one end face of the winding drum and is prevented from rotating in the unwinding direction in the event of a vehicle emergency, the locking base having a male thread formed on an outer circumferential surface of a shaft portion that is coaxial with the winding drum, an impact energy absorbing member that is coupled to the winding drum at one end and to the locking base at the other end, so as to connect the winding drum and the locking base so as to be rotatable together under normal conditions, and that plastically deforms when the unwinding force of the webbing exceeds a predetermined value in a state in which rotation of the locking base in the unwinding direction is prevented, thereby absorbing impact energy while allowing relative rotation between the winding drum and the locking base, and The present invention provides a seat belt retractor comprising: at least one impact energy absorbing wire that is housed in at least one slot that opens into the one end surface of the drum, with a head portion that protrudes from the opening of the slot being attached to the locking base, and that is pulled out from the opening while undergoing plastic deformation when the winding drum and the locking base rotate relative to each other to absorb impact energy; and a stopper member that is held in the central hole so as to be unable to rotate relative to the winding drum but able to move in the axial direction of the winding drum, and that screws into the male thread of the locking base to determine the allowable amount of relative rotation between the winding drum and the locking base when the impact energy absorbing member absorbs impact energy, wherein the locking base is provided with three or more retaining portions that are spaced apart from each other in the circumferential direction around the center of rotation of the winding drum and that are greater than the number of the slots, and a head portion of the at least one impact energy absorbing wire is attached to at least one of these retaining portions.

[0067] According to the above configuration, the locking base is provided with more holding portions for the impact energy absorbing wire than the number of slots, so that it is possible to select which holding portion the impact energy absorbing wire is to be attached to. Moreover, since three or more holding portions are provided, it is possible to change the mounting angle of the locking base with respect to the winding drum by an angle less than 180 degrees (120 degrees, 90 degrees, 60 degrees, etc., when the holding portions are evenly spaced). In other words, by selecting the holding portion to which the impact energy absorbing wire is to be attached, it is possible to adjust the initial position of the stopper member at a pitch according to the angular interval of the holding portions. Therefore, it is possible to finely adjust the amount of webbing pulled out when impact energy is absorbed.

[0068] As a second aspect, in the first aspect, the locking base has a flange facing the one end face of the winding drum, and the three or more holding portions may be grooves provided in the flange and opening radially outward. With this configuration, the holding portions can be formed more easily than when the holding portions are through holes. Moreover, since the impact energy absorbing wire can be inserted into the holding portions from the radial outside of the flange, it is easy to attach the impact energy absorbing wire to the holding portions.

[0069] As a third aspect, in the first or second aspect, the head of the at least one impact energy absorbing wire may have a retaining portion larger than the width of the groove, located on the opposite side of the flange from the winding drum. With this configuration, the impact energy absorbing wire is prevented from coming off the retaining portion in the axial direction, so that the impact energy absorbing wire can be reliably pulled out from the opening by the relative rotation of the winding drum and the locking base.

[0070] As a fourth aspect, in any one of the first to third aspects, the locking base includes a locking base body and a drive wheel attached to the locking base body, and the seat belt retractor further includes a pretensioner that rotates the winding drum in the winding direction via the drive wheel, the locking base body, and the energy absorbing member in the event of a vehicle emergency, and the three or more holding parts may be provided on the drive wheel. With this configuration, the size of the retractor in the axial direction of the winding drum can be reduced compared to when the locking base includes a member having a holding part separate from the drive wheel.

[0071] As a fifth aspect, in any of the first to fourth aspects, for example, the stopper member may be insertable into the central hole in a plurality of mounting positions rotated at a predetermined angular interval, and the three or more retaining portions may be spaced apart from one another at an angular interval smaller than the predetermined angular interval. [Explanation of symbols]

[0072] 1 Seat belt retractor 1C Pretensioner 10 Webbing 2. Housing 21,22 side wall 3 Winding drum 30 center hole 31,32 End face 35 Slots 36 Aperture 4A Impact energy absorbing material 4B Impact energy absorbing wire 4C Stopper member 4D Locking Base 43 Head 44 Stopper 5 Drive wheels 53 Flange 54 Holding part 6 Locking base body 72a Shaft 73 Male thread

Claims

1. A housing including a pair of opposing side walls, A winding drum for winding webbing, rotatably housed between a pair of side walls in the winding and unwinding directions of the webbing, the winding drum having a central hole opening to at least one end face, A locking base positioned opposite one end face of the winding drum, which prevents rotation in the pulling direction in the event of a vehicle emergency, comprising a locking base having a male screw formed on the outer circumferential surface of a shaft portion coaxial with the winding drum, An impact energy absorbing member having one end coupled to the winding drum and the other end coupled to the locking base, which under normal conditions allows the winding drum and the locking base to rotate integrally, and which plastically deforms when the pulling force of the webbing exceeds a predetermined value while the rotation of the locking base in the pulling direction is prevented, thereby absorbing impact energy while allowing relative rotation between the winding drum and the locking base, The winding drum is provided with at least one impact energy absorbing wire, which is housed in at least one slot opening on one end face of the winding drum, and whose head protruding from the opening of the slot is attached to the locking base, and which is pulled out from the opening while undergoing plastic deformation during relative rotation between the winding drum and the locking base to absorb impact energy, The locking base includes a stopper member that is held within the central hole so as to be unable to rotate relative to the winding drum and movable in the axial direction of the winding drum, and which is screwed onto the male thread of the locking base to define the permissible amount of relative rotation between the winding drum and the locking base when the impact energy absorbing member absorbs impact energy, A seat belt retractor, wherein the locking base is provided with three or more retaining parts, more than the number of slots, spaced apart from each other in the circumferential direction with respect to the rotation center of the winding drum, and the head of the at least one impact energy absorbing wire is attached to at least one of these retaining parts.

2. The locking base has a flange facing the one end face of the winding drum, The seat belt retractor according to claim 1, wherein the three or more retaining portions are grooves provided in the flange that open radially outward.

3. The seat belt retractor according to claim 2, wherein the head of at least one impact energy absorbing wire has a retaining portion that is located on the opposite side of the flange from the winding drum and is larger than the width of the groove.

4. The locking base includes a locking base body and a drive wheel attached to the locking base body. The vehicle further includes a pretensioner that rotates the winding drum in the winding direction via the drive wheel, the locking base body, and the impact energy absorbing member in the event of a vehicle emergency, The seat belt retractor according to any one of claims 1 to 3, wherein the three or more retaining parts are provided on the drive wheel.

5. The stopper member can be inserted into the central hole in multiple mounting positions rotated at predetermined angular intervals. The seat belt retractor according to any one of claims 1 to 3, wherein the three or more holding parts are spaced apart from each other at an angular interval smaller than the predetermined angular interval.

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