Buckle device

Abstract

To increase an allowable pull-out load of a connection member.SOLUTION: In a buckle device 10, after torsional deformation of a torsion shaft 32 is started and allowance for pull-out of a belt is started, deformation of a fracture part 36 of a shear plate 34 is started by a side face of a connection hole 24B of a spool 24, whereby the fracture part 36 allows rotation of the spool 24 and allows pull-out of the belt. Therefore, an allowable pull-out load of the belt can be so made as to be a total of a load for torsional deformation of the torsion shaft 32 and a load for deformation of the fracture part 36, and can be increased.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a buckle device in which a buckle body and a winding shaft are connected via a connecting member. [Background technology]

[0002] In the buckle device described in Patent Document 1 below, the tip side of the webbing is connected to the buckle body, the base end side of the webbing is wound onto a spool, and a torsion shaft is connected to the spool to restrict the webbing from being pulled out from the spool. Furthermore, the torsion shaft is deformed to allow the webbing to be pulled out from the spool, thereby allowing the buckle body to extend.

[0003] Here, in such a buckle device, it is preferable that the allowable pull-out load of the webbing can be increased. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-125010 A Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE PRESENT INVETION The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a buckle device capable of increasing the allowable withdrawal load of a connecting member. [Means for solving the problem]

[0006] A buckle device of a first aspect of the present invention includes a buckle body with which a tongue provided on a webbing worn by a occupant engages, a connecting member whose tip side is connected to the buckle body, a winding shaft around which the connecting member is wound from its base end side, a limiting member that is capable of restricting the pulling-out of the connecting member from the winding shaft and that can be deformed to allow the connecting member to be pulled-out from the winding shaft, thereby allowing the buckle body to extend, and a breaking member that is capable of restricting the pulling-out of the connecting member from the winding shaft and that begins to deform after the limiting member starts to deform, allowing the connecting member to be pulled-out from the winding shaft, and that breaks to allow the connecting member to be pulled-out from the winding shaft.

[0007] A buckle device according to a second aspect of the present invention is the buckle device according to the first aspect of the present invention, in which the deformation of the breaking member starts after the plastic deformation of the limiting member starts.

[0008] A buckle device according to a third aspect of the present invention is the buckle device according to the first or second aspect of the present invention, further comprising a locking body to which the limiting member and the breaking member are locked.

[0009] A buckle device of a fourth aspect of the present invention is a buckle device of any one of the first to third aspects of the present invention, which is provided with a blocking portion that blocks the broken pieces of the breaking member from entering at least one side of the winding shaft and the limiting member.

[0010] A buckle device of a fifth aspect of the present invention includes a buckle body with which a tongue provided on a webbing worn by a occupant engages, a connecting member whose tip side is connected to the buckle body, a winding shaft around which the connecting member is wound from its base end side, a limiting member that is capable of restricting withdrawal of the connecting member from the winding shaft and that can be deformed to allow withdrawal of the connecting member from the winding shaft, thereby allowing extension of the buckle body, a breaking member that is capable of restricting withdrawal of the connecting member from the winding shaft and that can be deformed to allow withdrawal of the connecting member from the winding shaft and that can be broken to allow withdrawal of the connecting member from the winding shaft, and a blocking portion that blocks broken pieces of the breaking member from entering at least one side of the winding shaft and the limiting member. Effect of the Invention

[0011] In the buckle device of the first aspect of the present invention, a tongue provided on a webbing worn by a vehicle occupant is engaged with a buckle body. A tip end side of a connecting member is connected to the buckle body, and the connecting member is wound around a winding shaft from a base end side, and a limiting member is capable of limiting the withdrawal of the connecting member from the winding shaft. Furthermore, the limiting member is deformed to allow the connecting member to be withdrawn from the winding shaft, thereby allowing the buckle body to extend.

[0012] Here, the breaking member is capable of restricting the pulling out of the connecting member from the winding shaft, and after the restricting member starts to deform (the restricting member starts to allow the connecting member to be pulled out of the winding shaft), the breaking member starts to deform to allow the connecting member to be pulled out of the winding shaft. Then, the breaking member breaks to allow the connecting member to be pulled out of the winding shaft. Therefore, the allowable pull-out load of the connecting member can be increased to the sum of the load for deforming the restricting member and the load for deforming the breaking member.

[0013] In the buckle device according to the second aspect of the present invention, the breaking member starts to deform after the limiting member starts to plastically deform, and therefore the breaking member deforms after the load for deforming the limiting member becomes large, so that the allowable pull-out load of the connecting member can be effectively increased.

[0014] In the buckle device of the third aspect of the present invention, the restricting member and the breaking member are locked to the locking body, which allows for high accuracy in the relative positions of the restricting member and the breaking member, and high accuracy in the relative timing between when the restricting member starts to deform and when the breaking member starts to deform.

[0015] In the buckle device of the fourth aspect of the present invention, the blocking portion blocks the broken pieces of the breaking member from entering at least one of the winding shaft and the limiting member, thereby preventing the broken pieces from interfering with the operation of at least one of the winding shaft and the limiting member.

[0016] In a buckle device according to a fifth aspect of the present invention, a tongue provided on a webbing worn by a vehicle occupant is engaged with the buckle body. A tip end side of a connecting member is connected to the buckle body, and the connecting member is wound around a winding shaft from a base end side, and a limiting member is capable of limiting withdrawal of the connecting member from the winding shaft. The limiting member is deformed to allow withdrawal of the connecting member from the winding shaft, thereby allowing extension of the buckle body. Moreover, a breaking member is capable of limiting withdrawal of the connecting member from the winding shaft, and the breaking member is deformed to allow withdrawal of the connecting member from the winding shaft, and the breaking member is broken to allow withdrawal of the connecting member from the winding shaft.

[0017] Incidentally, in the buckle device described in Patent Document 1 above, if a breaking member is provided that breaks to allow the webbing to be pulled out from the spool, it is preferable to prevent broken fragments of the breaking member from interfering with the operation of at least one of the spool and the torsion shaft.

[0018] In the buckle device according to the fifth aspect of the present invention, the blocking portion blocks the broken pieces of the breaking member from entering at least one of the winding shaft and the limiting member, thereby preventing the broken pieces from interfering with the operation of at least one of the winding shaft and the limiting member. [Brief description of the drawings]

[0019] [Figure 1] 1 is an exploded perspective view showing a buckle device according to an embodiment of the present invention, as viewed from diagonally front right. [Diagram 2] 1A and 1B are perspective views showing a buckle device according to an embodiment of the present invention, viewed from diagonally forward to the right, where 1A shows the entire buckle device and 1B shows the inside of the buckle device. [Diagram 3] 4(A) is a cross-sectional view showing a main part of a buckle device according to an embodiment of the present invention as viewed from the right side (cross-sectional view taken along line 3-3 in FIG. 4(A)). [Figure 4] 1A to 1C are diagrams showing the main parts of a buckle device according to an embodiment of the present invention, in which (A) is a side view seen from the front, (B) is a side view seen from the rear, and (C) is a cross-sectional view showing broken pieces of a shear plate and an opening to an inner hole of a regulating recess in a case. [Diagram 5] 1A and 1B are diagrams showing a shear plate of a buckle device according to an embodiment of the present invention, where 1A is a front view and 1B is a perspective view. [Figure 6] 4 is a graph showing the relationship between the belt withdrawal stroke (horizontal axis) and the allowable belt withdrawal load (vertical axis) in the buckle device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Fig. 1 shows an exploded perspective view of a buckle device 10 according to a first embodiment of the present invention as viewed from the right front. Fig. 2(A) shows a perspective view of the buckle device 10 as viewed from the right front, and Fig. 2(B) shows a perspective view of the inside of the buckle device 10 as viewed from the right front. In the drawings, the front of the buckle device 10 is indicated by an arrow FR, the right side (front side) of the buckle device 10 is indicated by an arrow RH, and the upper side of the buckle device 10 is indicated by an arrow UP.

[0021] The buckle device 10 according to this embodiment constitutes a seat belt device 12 for a vehicle (automobile), and the seat belt device 12 is applied to a seat (not shown) in the vehicle cabin. The seat belt device 12 is provided with a retracting device (not shown), which is installed on the outer side and lower side of the rear part of the seat in the vehicle width direction. A long strip-shaped webbing 14 (see FIG. 1) is retracted from the base end side of the retracting device, and the webbing 14 is biased toward the retracting device and is pulled out upward from the retracting device. The retracting device is provided with a locking mechanism, which locks the withdrawal of the webbing 14 from the retracting device in the event of a vehicle emergency (such as a collision).

[0022] The webbing 14 is movably passed through a through anchor (not shown) on the tip side of the take-up device, and the through anchor is installed on the outer side and upper side of the rear part of the seat in the vehicle width direction. An anchor (not shown) is fixed to the tip of the webbing 14, and the anchor is installed on the outer side and lower side of the rear part of the seat in the vehicle width direction. The webbing 14 is movably passed through a tongue 16 (see FIG. 1) between the through anchor and the anchor.

[0023] The buckle device 10 is installed on the inside and below the rear of the seat in the vehicle width direction, and the front, right and top of the buckle device 10 face the front or rear of the vehicle, and the inside and top of the vehicle width direction, respectively.

[0024] As shown in Fig. 1, Fig. 2 (A) and Fig. 2 (B), a buckle body 18 having a substantially rectangular parallelepiped shape is provided on the upper part of the buckle device 10. The tongue 16 can be engaged with the buckle body 18 from above, and the webbing 14 is attached to the occupant seated on the seat by engaging the tongue 16 with the buckle body 18. As a result, the portion of the webbing 14 between the through anchor and the tongue 16 (shoulder webbing) is hung diagonally from the occupant's shoulder to the waist (including the chest), and the portion of the webbing 14 between the tongue 16 and the anchor (lap webbing) is hung laterally around the occupant's waist. The engagement of the tongue 16 with the buckle body 18 can be released, and the engagement of the tongue 16 with the buckle body 18 is released, and the webbing 14 is released from the occupant's attachment. The lower part of the buckle body 18 is gradually smaller in the left-right direction as it goes downward.

[0025] A tip end portion (upper portion) of a band-shaped belt 20 (webbing) serving as a connecting member is connected to the lower portion of the buckle body 18, and the belt 20 is made of, for example, the same material as the webbing 14. A base end portion (lower end portion) of the belt 20 is folded back and sewn to the vicinity of the base end portion of the belt 20, whereby the base end portion (lower portion) of the belt 20 is made into a loop.

[0026] A metal frame 22 is provided as a support at the bottom of the buckle device 10, and the frame 22 has a U-shaped cross section. A back plate 22A is provided on the left side of the frame 22, and the frame 22 is fixed to the vehicle body (for example, the rear part of the lower part of the seat) at the lower end of the back plate 22A. A leg plate 22B and a leg plate 22C are provided at the front and rear parts of the frame 22, respectively, and the leg plate 22B and the leg plate 22C protrude to the right from the back plate 22A. A substantially circular support hole 22D and a circular support hole 22E are formed through the leg plate 22B and the leg plate 22C, respectively, and the support hole 22D and the support hole 22E are opposed to each other in the front-rear direction.

[0027] A metallic, substantially cylindrical spool 24 serving as a winding shaft passes through the support holes 22D and 22E of the frame 22, and the spool 24 is supported by the frame 22. The axial direction of the spool 24 is parallel to the front-rear direction, and the spool 24 is rotatable about its central axis. A long rectangular insertion hole 24A (see FIG. 4(A)) is formed through the spool 24 except for its front portion, and the insertion hole 24A extends in the axial direction of the spool 24 and opens to the rear side. A plurality of rectangular connecting holes 24B (three in this embodiment) serving as connected portions are formed through the front portion of the spool 24, and the plurality of connecting holes 24B are disposed at equal intervals in the circumferential direction of the spool 24 and each opens to the front side. The dimension of the connecting holes 24B in the circumferential direction of the spool 24 is larger than the dimension of the insertion holes 24A in the circumferential direction (width direction) of the spool 24, and one connecting hole 24B communicates with one insertion hole 24A.

[0028] A metallic, substantially cylindrical bar 26 serving as a locking member is coaxially inserted into the spool 24, and both axial ends of the bar 26 are coaxially expanded in diameter and fitted into the spool 24. The base end portion (annular portion) of the belt 20 is inserted into an insertion hole 24A of the spool 24, and the axial middle portion of the bar 26 is inserted therein, whereby the base end portion of the belt 20 is locked in the spool 24 by the bar 26 and connected to the spool 24. The belt 20 is wound around the spool 24, and is pulled out upward from the left side of the spool 24.

[0029] A resin protector 28 having a substantially U-shaped cross section is fitted into the upper part of the frame 22, and the left wall, front wall, and rear wall of the protector 28 cover the back plate 22A, leg plate 22B, and leg plate 22C of the frame 22, respectively. The upper end of the protector 28 protrudes outside the protector 28, and the upper end of the protector 28 is placed on the upper side of the frame 22. A substantially semicircular insertion hole 28A is formed through the lower part of the front wall and rear wall of the protector 28, and the insertion hole 28A is opened downward, and the upper part of the spool 24 is inserted into the insertion hole 28A. The belt 20 is inserted into the protector 28, and the protector 28 limits the contact of the belt 20 with the frame 22.

[0030] A metal case 30 (see FIG. 3) serving as a locking body is disposed in front of the frame 22 (leg plate 22B). A substantially rectangular shaped restricting plate 30A serving as a restricting portion is provided in the case 30, and the restricting plate 30A is fixed to the leg plate 22B, thereby fixing the case 30 to the leg plate 22B. A substantially bottomed cylindrical locking tube 30B is integrally formed in front of the restricting plate 30A, and the axial direction of the locking tube 30B is parallel to the front-rear direction.

[0031] The locking tube 30B has an approximately cylindrical inner hole 30C penetrating the regulating plate 30A and opening to the rear side of the regulating plate 30A, and the front part of the spool 24 is inserted coaxially into the rear part of the inner hole 30C. The diameter of the front part of the inner hole 30C is smaller than the diameter of the rear part of the inner hole 30C, and a plurality of (three in this embodiment) approximately trapezoidal columnar locking holes 30D (see FIG. 4(B)) are formed as locking parts on the circumferential surface of the front part of the inner hole 30C. The axial direction of the locking holes 30D is parallel to the front-rear direction (axial direction of the inner hole 30C) and is integrated with the front wall (bottom wall) of the locking tube 30B, and the plurality of locking holes 30D are arranged at equal intervals in the circumferential direction of the inner hole 30C. A plurality of (three in this embodiment) generally trapezoidal regulating recesses 30E (see FIG. 4(B)) are formed on the rear surface of the regulating plate 30A as blocking portions, and the plurality of regulating recesses 30E are disposed at equal intervals in the circumferential direction of the locking tube 30B, and the rear side of the regulating recesses 30E is closed by the leg plate 22B of the frame 22. The regulating recesses 30E are open to the inner hole 30C, and the widthwise dimension of the regulating recesses 30E (circumferential direction of the inner hole 30C) becomes smaller toward the radially inward direction of the inner hole 30C.

[0032] A metallic, generally cylindrical torsion shaft 32 (see Figs. 3 and 4(B)) serving as a limiting member (energy absorbing member) is coaxially arranged in the inner hole 30C. A plurality of (three in this embodiment) generally trapezoidal, columnar locking projections 32A serving as locking portions are integrally formed at the front end of the torsion shaft 32, and the axial direction of each of the locking projections 32A is parallel to the front-rear direction (axial direction of the torsion shaft 32) and is arranged at equal intervals in the circumferential direction of the torsion shaft 32. The locking projections 32A are inserted into locking holes 30D of the case 30 (inner hole 30C) and fitted in the circumferential direction of the torsion shaft 32, and the torsion shaft 32 is locked to the case 30 (inner hole 30C) so as not to rotate relative to the case 30. A plurality of (three in this embodiment) substantially trapezoidal columnar connecting projections 32B are integrally formed as connecting portions at the rear end of the torsion shaft 32, and the axial direction of each of the connecting projections 32B is parallel to the front-rear direction (the axial direction of the torsion shaft 32) and is disposed at equal intervals in the circumferential direction of the torsion shaft 32. The connecting projections 32B are inserted into connecting holes 24B of the spool 24 and fitted in the circumferential direction of the torsion shaft 32, and the torsion shaft 32 is connected to the spool 24 so as not to rotate relative to the spool 24, thereby restricting the rotation of the spool 24.

[0033] A metal shear plate 34 (see Fig. 3, Figs. 4(A) and (B), and Fig. 5(A) and (B)) is disposed between the spool 24 and the torsion shaft 32 as a breaking member, and the shear plate 34 is disposed coaxially with the inner hole 30C of the case 30. A disk-shaped base 34A is provided coaxially at the center of the shear plate 34, and the base 34A is inserted coaxially into the spool 24 on the rear side of the torsion shaft 32. A plurality of (three in this embodiment) substantially elongated rectangular plate-shaped breaking portions 36 are integrally formed on the outer periphery of the base 34A, and the breaking portions 36 each extend radially outward from the base 34A and are disposed at equal intervals in the circumferential direction of the base 34A. The base end side portion of the breaking portion 36 is rectangular, and the base end side portion of the breaking portion 36 is inserted through the connecting hole 24B of the spool 24 and is spaced from both side surfaces of the connecting hole 24B in the circumferential direction of the spool 24. The tip end portion 36A of the breaking portion 36 (a portion excluding the base end side portion) is trapezoidal plate-shaped, and the width direction (circumferential direction of the share plate 34) dimension of the tip end portion 36A of the breaking portion 36 increases toward the radial outside of the share plate 34. The tip end portion 36A of the breaking portion 36 is inserted into the restricting recess 30E of the case 30 (restricting plate 30A), and the tip end portion 36A of the breaking portion 36 abuts against the side surface of the restricting recess 30E, restricting (locking) the rotation of the share plate 34.

[0034] A generally rectangular tubular boot 38 (cover) is provided as a covering member in the range from the buckle body 18 to the frame 22, and the boot 38 is made of soft resin and has flexibility. The upper part of the boot 38 is gradually smaller in the left-right direction toward the lower side, and the lower part of the buckle body 18 is fitted into the upper part of the boot 38 to restrict the downward movement of the buckle body 18. The belt 20 is inserted into the vertical middle part of the boot 38, and the lower part of the boot 38 is opened to the front side and the frame 22 (including the protector 28, the spool 24, and the bar 26) is fitted into it. The boot 38 is integrally formed with a rectangular frame-shaped abutment frame 38A directly above the lower part, and the belt 20 is inserted into the abutment frame 38A. The upper end of the protector 28 abuts against the lower side of the abutment frame 38A, thereby restricting the downward movement of the boot 38. As described above, when the belt 20 is wound around the spool 24, an elastic contraction force is applied to the boot 38 between the buckle body 18 and the frame 22 with tension being applied to the belt 20, and the boot 38 urges the frame 22 downward to stand on its own with respect to the frame 22, and urges the buckle body 18 upward to stand on its own. A clip 40 made of soft resin penetrates the left wall of the lower part of the boot 38 and the back plate 22A of the frame 22, and the clip 40 clamps the left wall and the back plate 22A of the boot 38 to fix the boot 38 to the frame 22.

[0035] Next, the operation of this embodiment will be described.

[0036] In the seat belt device 12 configured as described above, the torsion shaft 32 in the buckle device 10 limits the rotation of the spool 24, thereby restricting the pull-out of the belt 20 from the spool 24 and the upward extension of the buckle body 18, and the tongue 16 of the webbing 14 engages with the buckle body 18, thereby attaching the webbing 14 to the occupant.

[0037] In the event of a vehicle emergency (such as a collision), a locking mechanism of the retractor locks the webbing 14 from being pulled out from the retractor, thereby restraining the occupant with the webbing 14. Then, for example, when an inertial force acts on the occupant and the occupant pulls the webbing 14, a pulling force from the spool 24 acts on the belt 20 from the webbing 14 via the tongue 16 and the buckle body 18, and a rotational force acts on the spool 24. Furthermore, when the torsion shaft 32 is twisted between the front end and the rear end by the rotational force acting on the spool 24, the rotation of the spool 24 is permitted, and the belt 20 is permitted to be pulled out from the spool 24, thereby permitting the buckle body 18 (including the tongue 16) to extend upward. As a result, the load applied to the occupant (particularly the chest area) from the webbing 14 is reduced (limited to the load that causes the torsional deformation of the torsion shaft 32), and the kinetic energy of the occupant is absorbed by the torsional deformation of the torsion shaft 32.

[0038] Also, the allowable pull-out load of the belt 20, which is the load at which the pull-out of the belt 20 is permitted (the allowable extension load of the buckle body 18, which is the load at which the extension of the buckle body 18 is permitted, the force limiter load), is set to a load at which the torsion shaft 32 is twisted. Furthermore, as shown in Fig. 6, the torsion deformation of the torsion shaft 32 starts after the belt 20 (including the portion wound around the spool 24) is stretched by removing slack. Then, when the torsion shaft 32 is twisted, the torsion shaft 32 is temporarily elastically deformed to gradually increase the load at which the torsion shaft 32 is twisted, and then the torsion shaft 32 is plastically deformed to maintain the load at which the torsion shaft 32 is twisted.

[0039] Incidentally, when the side surface of the connecting hole 24B of the spool 24 abuts against the breaking portion 36 of the share plate 34, the breaking portion 36 restricts the rotation of the spool 24, thereby making it possible to restrict the withdrawal of the belt 20.

[0040] Here, after the torsion shaft 32 starts to twist and starts to allow the belt 20 to be pulled out, the breaking portion 36 starts to deform (including partially breaking) due to the side surface of the connecting hole 24B (particularly the portion at the outer periphery of the spool 24), so that the breaking portion 36 allows the spool 24 to rotate and the belt 20 to be pulled out (see FIG. 6). Then, the tip portion 36A of the breaking portion 36 is broken from the base end portion of the breaking portion 36 by the side surface of the connecting hole 24B, so that the breaking portion 36 allows the spool 24 to rotate and the belt 20 to be pulled out.

[0041] Therefore, when the belt 20 starts to be allowed to be pulled out, the allowable pull-out load of the belt 20 can be increased to the sum of the load for torsional deformation of the torsion shaft 32 and the load for deformation of each breaking portion 36. This makes it possible to suppress the torsional deformation of the torsion shaft 32 when the rotational force applied to the spool 24 by the occupant via the webbing 14, the tongue 16, the buckle body 18, and the belt 20 is small, for example, during a minor vehicle collision. Therefore, it is possible to suppress the torsional deformation of the torsion shaft 32 from being unnecessarily twisted, and to suppress the buckle body 18 from being unnecessarily extended.

[0042] Furthermore, the allowable pull-out load of the belt 20 when the belt 20 starts to be allowed to be pulled out is not only the load for each breaking portion 36 to be deformed, but is the sum of the load for each breaking portion 36 to be deformed and the load for the torsion shaft 32 to be twisted and deformed. Therefore, the need to increase the strength of the shear plate 34 (breaking portion 36) in order to increase the allowable pull-out load of the belt 20 when the belt 20 starts to be allowed to be pulled out can be reduced, and the shear plate 34 can be made smaller and lighter. Moreover, the allowable pull-out load of the belt 20 when the belt 20 starts to be allowed to be pulled out can be prevented from being affected by variations in the physical properties of the shear plate 34 (breaking portion 36), and variations in the allowable pull-out load of the belt 20 when the belt 20 starts to be allowed to be pulled out can be suppressed.

[0043] Furthermore, after the plastic deformation of the torsion shaft 32 starts (in this embodiment, after the plastic deformation of the torsion shaft 32 starts), the breaking portion 36 starts to deform due to the side surface of the connecting hole 24B, and the breaking portion 36 allows the spool 24 to rotate, thereby allowing the belt 20 to be pulled out (see Figure 6).

[0044] Therefore, after the load for torsional deformation of the torsion shaft 32 becomes large, each breaking portion 36 is deformed, so that the allowable pull-out load of the belt 20 can be effectively increased when pull-out of the belt 20 is permitted to begin.

[0045] Furthermore, the torsion shaft 32 and the shear plate 34 (breaking portion 36) are prevented from rotating by the same case 30. This makes it possible to increase the accuracy of the relative circumferential positions of the torsion shaft 32 and the breaking portion 36, and to increase the accuracy of the relative timing between when the torsion shaft 32 starts to deform and when the breaking portion 36 starts to deform.

[0046] In addition, the rear side of the regulating recess 30E of the case 30 is closed by the leg plate 22B of the frame 22, so that the broken tip 36A (broken piece 36A) of the breaking portion 36 cannot pass through the opening to the inner hole 30C of the regulating recess 30E in the case 30, and the broken piece 36A is prevented from entering the inner hole 30C from the regulating recess 30E (see FIG. 4(C)). This makes it possible to suppress the broken piece 36A from interfering with the rotation of the spool 24 in the inner hole 30C, the torsional deformation of the torsion shaft 32, and the rotation of the parts of the shear plate 34 other than the broken piece 36A.

[0047] Moreover, the width dimension of the tip 36A (fractured piece 36A) of the breaking portion 36 becomes larger toward the radial outside of the shear plate 34 (the radial outside of the inner hole 30C), and the width dimension of the regulating recess 30E becomes smaller toward the radial inside of the inner hole 30C. Therefore, it is possible to effectively disable the passage of the broken piece 36A through the opening of the regulating recess 30E to the inner hole 30C, and it is possible to effectively prevent the broken piece 36A from entering the inner hole 30C from the regulating recess 30E.

[0048] In this embodiment, the fractured portion 36 starts to deform after the start of plastic deformation of the torsion shaft 32. However, the fractured portion 36 may start to deform before the start of plastic deformation of the torsion shaft 32, as long as it is after the start of torsional deformation of the torsion shaft 32. [Explanation of symbols]

[0049] 10 buckle device, 14 webbing, 16 tongue, 18 buckle body, 20 belt (connecting member), 24 spool (winding shaft), 30 case (retaining body), 30E regulating recess (blocking portion), 32 torsion shaft (limiting member), 34 shear plate (breaking member), 36A broken pieces

Claims

1. a buckle body with which a tongue provided on a webbing attached to a vehicle occupant is engaged; A connecting member whose tip side is connected to the buckle body; a winding shaft around which the connecting member is wound from a base end side; a limiting member that is capable of limiting withdrawal of the connecting member from the winding shaft and that is deformed to allow withdrawal of the connecting member from the winding shaft, thereby allowing extension of the buckle body; a breaking member that is capable of restricting the pulling out of the connecting member from the winding shaft, and that starts to deform after the restricting member starts to deform to allow the connecting member to be pulled out of the winding shaft, and breaks to allow the connecting member to be pulled out of the winding shaft; a locking body to which the limiting member and the breaking member are locked; A buckle device comprising:

2. 2. The buckle device according to claim 1, wherein the breaking member starts to deform after the limiting member starts to plastically deform.

3. A buckle device as described in claim 1 or claim 2, which is provided with a blocking portion that prevents the broken fragments of the breaking member from entering at least one side of the winding shaft and the limiting member.

4. A buckle body with which a tongue provided on a webbing attached to a passenger is engaged; A connecting member whose tip side is connected to the buckle body; a winding shaft around which the connecting member is wound from a base end side; a limiting member that is capable of limiting withdrawal of the connecting member from the winding shaft and that is deformed to allow withdrawal of the connecting member from the winding shaft, thereby allowing extension of the buckle body; a breaking member that is disposed between the winding shaft and the restricting member, that is capable of restricting the pulling out of the connecting member from the winding shaft, that starts to deform after the restricting member starts to deform to allow the connecting member to be pulled out from the winding shaft, and that breaks to allow the connecting member to be pulled out from the winding shaft; A buckle device comprising:

Images