Webbing retractor

Abstract

To suppress a temporal rise of a force limiter load.SOLUTION: A webbing winding device 10 is equipped with a spool 20 that can draw out and wind up a webbing 20A, and a rotator 50 that is disposed oppositely to the spool 20, and is prevented from rotating at emergency. The webbing winding device 10 is equipped with a wire 40 that has a base end portion 42 held, is disposed between the rotator 50 and the spool 20, and is wound around an inner rib 26 of the spool 20 when being deformed at emergency and the webbing 20A is drawn out, and an escaping portion 24B where a tip end portion 48 of the wire 40 escapes when the wire 40 is wound around an inner rib 26.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a webbing take-up device. [Background technology]

[0002] It is known that webbing take-up devices are provided with a force limiter mechanism that reduces the load applied to the webbing when the load exceeds a certain level, in order to prevent the load on the webbing from increasing and compressing the chest (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a technology in which an energy absorption pin is fitted into an axial hole in a spool, and in the event of an emergency, the torsion bar is twisted and the energy absorption pin is pulled out of the spool, absorbing energy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-331563 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, in such a webbing take-up device, it is preferable to suppress a temporary increase in the force limiter load.

[0006] In consideration of the above, an object of the present invention is to provide a webbing take-up device that can suppress a temporary increase in force limiter load. [Means for solving the problem]

[0007] A webbing take-up device according to a first aspect of the present invention includes a spool capable of withdrawing and retracting a webbing, and a webbing take-up device disposed opposite the spool, In the event of a vehicle collision The rotor is prevented from rotating at the base end. To the rotating body and is disposed between the rotor and the spool. In the event of a vehicle collision When the webbing is pulled out Deformed A wire wound around the winding portion of the spool, and when the wire is wound around the winding portion, the tip of the wire is From the applied load and an escape portion for escaping.

[0008] A webbing take-up device according to a second aspect of the present invention is the webbing take-up device according to the first aspect of the present invention, wherein the relief portion is formed in a slope shape in the winding portion.

[0009] A webbing take-up device according to a third aspect of the present invention is the webbing take-up device according to the first or second aspect of the present invention, wherein the relief portion is formed in a recessed shape around the winding portion.

[0010] In a webbing take-up device of a fourth aspect of the present invention, in the webbing take-up device of any one of the first to third aspects of the present invention, the winding portion is formed to be recessed inward in the winding direction on the side of the escape portion.

[0011] In a webbing take-up device of a fifth aspect of the present invention, in the webbing take-up device of any one of the first to fourth aspects of the present invention, the escape portion is formed around the accommodating hole of the spool in which the tip end of the wire is accommodated.

[0012] A webbing take-up device according to a sixth aspect of the present invention is the webbing take-up device according to any one of the first to fifth aspects of the present invention, wherein a plurality of the wires are provided. [Effects of the Invention]

[0013] In the webbing take-up device of the first aspect of the present invention, when the wire is wound around the winding portion, the tip of the wire From the applied loadThe provision of the escape portion prevents the tip of the wire from scraping the wound portion. This prevents a temporary increase in the load acting from the wire on the spool when winding the wire. As a result, it is possible to prevent a temporary increase in the force limiter load.

[0014] In the webbing take-up device of the second aspect of the present invention, the relief portion is formed in a sloped shape on the winding portion, so that when the wire is wound around the winding portion, the tip of the wire is guided by the relief portion formed in a sloped shape. This prevents the tip of the wire from being pressed strongly against the winding portion. As a result, the winding portion is prevented from being scraped by the tip of the wire. Therefore, with a simple configuration, it is possible to prevent a temporary increase in the force limiter load.

[0015] In the webbing take-up device of the third aspect of the present invention, the relief portion is formed in a concave shape around the winding portion, so that when the wire is wound around the winding portion, the tip of the wire escapes into the relief portion formed in a concave shape. This prevents the tip of the wire from being pressed strongly against the winding portion. As a result, the winding portion is prevented from being scraped by the tip of the wire. Therefore, with a simple configuration, it is possible to prevent a temporary increase in the force limiter load.

[0016] In the webbing take-up device of the fourth aspect of the present invention, the winding portion is recessed inward in the winding direction on the escape portion side, thereby forming a space inward in the winding direction into which the tip of the wire escapes. This further prevents the winding portion from being scraped by the tip of the wire. This further prevents a temporary increase in the load acting from the wire on the spool when the wire is wound. As a result, it is possible to further prevent a temporary increase in the force limiter load.

[0017] In the webbing take-up device of the fifth aspect of the present invention, the relief portion is formed around the spool housing hole, so that when the tip end of the wire is pulled out from the housing hole, the tip end of the wire escapes into the relief portion. Therefore, when the tip end of the wire is pulled out from the spool housing hole, the tip end of the wire is prevented from scraping the wound portion. As a result, it is possible to prevent a temporary increase in the force limiter load.

[0018] In the webbing take-up device of the sixth aspect of the present invention, by providing multiple wires, even if the movement of the tip of the wire radially outward of the spool is hindered by other wires, the relief portion can prevent the tip from scraping the winding portion. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is an exploded perspective view showing a webbing take-up device according to a first embodiment. FIG. [Figure 2] FIG. 2 is a perspective view showing a spool and a pinion according to the first embodiment. [Figure 3] 3 is a cross-sectional view showing the webbing take-up device according to the first embodiment, showing the cross section taken along line AA in FIG. 2. [Figure 4] 1 is an exploded perspective view showing a state before a wire is inserted into an accommodating hole formed in a spool according to a first embodiment. FIG. [Figure 5] 5A and 5B are cross-sectional views showing one end side of a webbing take-up device according to a first embodiment, in which FIG. 5A shows a spool, and FIG. 5B shows the spool, a wire, and a pinion. [Figure 6] FIG. 2 is a side view showing the spool according to the first embodiment as viewed from one end side. [Figure 7] 7A and 7B are side views showing a spool according to the first embodiment as viewed from one end, in which FIG. 7A shows a state in which the webbing has been pulled out and the spool has rotated in the pulling-out direction, and FIG. 7B shows a state in which the webbing has been further pulled out and the spool has further rotated in the pulling-out direction. [Figure 8] FIG. 10 is a side view showing a spool according to a second embodiment as viewed from one end side. [Figure 9] 9A and 9B are diagrams showing a spool according to a second embodiment, in which FIG. 9A is a side view showing a state in which the webbing is pulled out and the spool is rotated in the pulling-out direction, as viewed from one end of the spool, and FIG. 9B is a cross-sectional view showing the BB cross section of FIG. 9A. DETAILED DESCRIPTION OF THE INVENTION

[0020] [First embodiment] A webbing take-up device according to the first embodiment will be described below with reference to the drawings. In each drawing, arrow FR indicates the front in the longitudinal direction of the vehicle, arrow OUT indicates the outward direction in the vehicle width direction, and arrow UP indicates the upward direction in the vertical direction of the vehicle. In each drawing, arrow A indicates a take-up direction A, which is the rotation direction of the spool 20 when the spool 20 takes up the webbing 20A, and arrow B indicates an unwinding direction B, which is opposite to the take-up direction A. In each drawing, the axial direction of the spool 20 is referred to as axial direction D. In addition, when simply referring to one end side and the other end side, this refers to the axial direction D of the spool 20 unless otherwise specified.

[0021] [Webbing take-up device configuration] As shown in FIG. 1, the webbing take-up device 10 mainly includes a frame 12, a cover plate 14, a biasing mechanism 16, a sensor mechanism 18, a spool 20, a shaft 30, a rotating body 50, and a cylinder 60.

[0022] (Frame 12) The frame 12 is made of metal and is fixed to the underside of a center pillar (not shown) of the vehicle body. The frame 12 is formed in a rectangular cylindrical shape when viewed in the vertical direction of the vehicle, and has a leg plate 12A formed on the front side of the vehicle and a leg plate 12B formed on the rear side of the vehicle. A circular through-hole 12C is formed in the leg plate 12A and passes through it in the longitudinal direction of the vehicle. A circular through-hole 12D is formed in the leg plate 12B and passes through it in the longitudinal direction of the vehicle. A spool 20 inserted into the through-hole 12C of the leg plate 12A and the through-hole 12D of the leg plate 12B is rotatably supported by the leg plates 12A and 12B.

[0023] (spool 20) The spool 20 is formed in a substantially cylindrical shape and is rotatable in a winding direction A and an unwinding direction B around a central axis C as a rotation axis. A longitudinal base end of a long strip-shaped webbing 20A is engaged with the spool 20. When the spool 20 is rotated in the winding direction A, the webbing 20A is wound onto the spool 20. When the webbing 20A is unwound from the spool 20, the webbing 20A is rotated in the unwinding direction B. When the webbing 20A is unwound from the spool 20, the webbing 20A is applied to an occupant seated in a vehicle seat.

[0024] (Biasing mechanism 16) A biasing mechanism 16 is provided on the vehicle rear side of the frame 12. The biasing mechanism 16 is provided with a spool biasing means (not shown) such as a power spring. The spool biasing means is directly or indirectly engaged with the spool 20, and the spool 20 is biased in the winding direction A by the biasing force of the spool biasing means.

[0025] (Shaft 30) As shown in FIG. 3, the shaft 30 is made up of a torsion shaft 32 serving as a first energy absorbing member and a sub-shaft .

[0026] The torsion shaft 32 is made of metal and is formed in a generally cylindrical shape. The torsion shaft 32 is disposed within the spool 20 so as to be coaxial with the central axis C of the spool 20. The other end of the torsion shaft 32 (on the vehicle rear side) is connected to the spool 20 so as to be integrally rotatable. The other end of the torsion shaft 32 is rotatably supported by the biasing mechanism 16.

[0027] One end side (vehicle front side) of the torsion shaft 32 is coaxially connected to a sub-shaft 34. The sub-shaft 34 is made of metal and formed in a substantially cylindrical shape. One end side of the sub-shaft 34 is rotatably supported by the sensor mechanism 18. The torsion shaft 32 constitutes a first force limiter mechanism serving as a force limiter mechanism.

[0028] (rotating body 50) 1 and 3, a rotating body 50 constituting the locking mechanism is disposed opposite the spool 20 in the axial direction D. The rotating body 50 is composed of a pinion 52 and a lock base 54. The lock base 54 is disposed closer to the front of the vehicle than the pinion 52. The lock base 54 is formed into a disk shape by, for example, aluminum die-casting, and is disposed coaxially with the central axis C of the spool 20.

[0029] 2 and 3, the pinion 52 is formed into a disk shape by, for example, aluminum die casting, and is disposed coaxially with the central axis C of the spool 20. The pinion 52 is coupled to a lock base 54 so as to be rotatable integrally therewith.

[0030] One end of the torsion shaft 32 is fitted into the pinion 52, restricting relative rotation between the pinion 52 and one end of the torsion shaft 32. This allows the spool 20, torsion shaft 32, lock base 54, and pinion 52 to rotate integrally.

[0031] 1, the lock base 54 includes a lock pawl 56. The lock pawl 56 is supported by the lock base 54 so as to be rotatable.

[0032] 2, the pinion 52 is formed with two through holes 52A penetrating in the axial direction D. The through holes 52A may be elongated holes.

[0033] (Cover plate 14) 1 and 3, a metal cover plate 14 that covers the pinion 52 and lock base 54 is fixed to the leg plate 12A on the vehicle front side of the frame 12. The cover plate 14 has ratchet teeth 14A formed in a ratchet hole that penetrates the cover plate 14 in the longitudinal direction of the vehicle.

[0034] (Sensor mechanism 18) A sensor mechanism 18 is provided on the vehicle front side of the cover plate 14. In an emergency, the sensor mechanism 18 is activated, causing the lock pawl 56 to rotate and move radially outward from the lock base 54, and the tip of the lock pawl 56 to engage with the ratchet teeth 14A. This restricts the rotation of the lock base 54 in the unwinding direction B, and indirectly restricts the rotation of the spool 20 in the unwinding direction B. An emergency is when the vehicle crashes, the vehicle suddenly decelerates, or the webbing 20A is suddenly unwound from the spool 20, etc.

[0035] (cylinder 60) As shown in Fig. 1, the webbing retractor 10 includes a cylinder 60 that constitutes a pretensioner. A micro gas generator 62 (hereinafter referred to as MGG 62) is inserted into the base end of the cylinder 60. The MGG 62 is electrically connected to a collision detection sensor (not shown) provided in the vehicle via an ECU (not shown). A seal ball 64 as a piston and a moving member 66 are arranged inside the cylinder 60.

[0036] When the collision detection sensor detects an impact during a vehicle collision, the MGG 62 generates gas, and the moving member 66 is pressed by the seal ball 64 and moved toward the tip side of the cylinder 60. Then, the moving member 66 is moved in a state in which the teeth of the pinion 52 and the lock base 54 are stuck into it (in a biting or engaged state), causing the spool 20 to rotate in the winding direction A, winding up the webbing 20A and securing the occupant in the vehicle seat.

[0037] [Configuration of the second force limiter mechanism] As shown in FIG. 3, the spool 20 is provided with two wires 40 as second energy absorbing members that constitute a second force limiter mechanism serving as a force limiter mechanism.

[0038] (Wire 40) The wire 40 is made of a metal (for example, piano wire) that is stronger than the spool 20. The wire 40 is made of a metal that is less susceptible to chipping than the spool 20. The two wires 40 can be made to have the same length and shape.

[0039] As shown in FIG. 4, the wire 40 is formed into a generally crank shape by a base end portion 42, a first intermediate portion 44, a second intermediate portion 45, a third intermediate portion 46, and a tip portion 48.

[0040] The base end portion 42 is formed in a disk shape. The outer diameter of the base end portion 42 is larger than at least the minimum inner diameter of the through hole 52A formed in the pinion 52. at least

[0041] The first intermediate portion 44 is formed in a round bar shape extending from the base end portion 42 toward the other end. The second intermediate portion 45 is formed in a round bar shape extending from the end portion on the other end side of the first intermediate portion 44 in a direction approximately perpendicular to the axial direction D. The third intermediate portion 46 is formed in a round bar shape extending from the end portion of the second intermediate portion 45 in the axial direction D. The first intermediate portion 44, the second intermediate portion 45, and the third intermediate portion 46 can have approximately the same diameter.

[0042] The tip portion 48 is formed in a truncated cone shape whose diameter decreases in the axial direction D from the end portion on the other end side of the third intermediate portion 46. The tip portion 48 is formed in a shape that tapers toward the tip of the wire 40.

[0043] (spool 20) As shown in FIG. 4, the spool 20 includes a substantially cylindrical spool body 21 and a flange 22 formed on one end side of the spool body 21 in the axial direction D.

[0044] The flange portion 22 is formed in a disk shape with an outer shape larger than that of the spool body portion 21, and has an outer rib 23, an inner rib 26 that constitutes the winding portion, and a groove portion 28.

[0045] The outer rib 23 is formed on the outer edge of the flange portion 22 so as to protrude toward one end in the axial direction D. The outer rib 23 is formed in an annular shape. The inner rib 26 is formed on the inner edge of the flange portion 22 so as to protrude toward one end in the axial direction D. The inner rib 26 is formed in an annular shape. The groove portion 28 is formed between the outer rib 23 and the inner rib 26 as an annular groove recessed toward the other end in the axial direction D. The groove portion 28 accommodates the second intermediate portion 45 of the wire 40.

[0046] 3 and 6, two accommodating holes 29 are formed in the groove portion 28 to accommodate the third intermediate portion 46 and the tip portion 48 of the wire 40. In a cross section perpendicular to the central axis C of the spool 20, the two accommodating holes 29 are provided substantially symmetrically with respect to the central axis C. In other words, in a cross section perpendicular to the central axis C of the spool 20, two wires 40 are provided substantially symmetrically with respect to the central axis C.

[0047] 3, the accommodating hole 29 may be a circular through-hole that penetrates the spool 20 in the axial direction D. The inner diameter of the accommodating hole 29 is formed to be slightly larger than the outer diameter of the third intermediate portion 46 of the wire.

[0048] 6, the accommodating hole 29 is formed in a radially inner portion of the groove portion 28. At least a portion of the accommodating hole 29 is formed in a portion of the spool 20 in the radial direction where the inner rib 26 is formed. The accommodating hole may also be a blind hole (non-through hole).

[0049] As shown in FIGS. 4 and 6, the inner rib 26 is composed of an inner portion 25 and an outer portion 24.

[0050] The inner portion 25 is formed in a substantially annular shape and has a substantially uniform thickness in the radial direction.

[0051] Two outer portions 24 are formed outside the inner portion 25 so as to connect the two accommodating holes 29. The outer portion 24 includes a main body portion 24A and a recess portion 24B. The main body portions 24A are formed to extend from the two accommodating holes 29 at a predetermined angle (e.g., 120 degrees) in the drawing direction B. The height of the main body portions 24A in the axial direction D can be made approximately constant.

[0052] The relief portions 24B are formed to extend at a predetermined angle (e.g., 30 degrees) in the pull-out direction B from the ends of the main body portion 24A in the pull-out direction B. The relief portions 24B are formed in the vicinity of the accommodation hole 29 of the spool 20 in which the tip portion 48 of the wire 40 is accommodated. The radial width of the relief portions 24B is formed to become narrower as they approach the accommodation hole 29. In other words, the inner rib 26 that constitutes the winding portion is formed to be recessed inward in the winding direction (circumferential direction of the inner rib 26) on the relief portion 24B side.

[0053] 5(A), the relief portion 24B is formed so as to incline from an end face on one end side of the main body portion 24A in the axial direction D toward the bottom surface of the groove portion 28. In other words, the end face on one end side of the relief portion 24B in the axial direction D is formed in a slope shape that inclines from the end face on one end side of the main body portion 24A in the axial direction D toward the bottom surface of the groove portion 28.

[0054] The length of the sloped relief portion 24B can be approximately the same as the length of the tip portion 48. Note that the length of the sloped relief portion 24B may be longer or shorter than the length of the tip portion 48.

[0055] An end face on one end side of the relief portion 24B in the axial direction D is formed at a predetermined angle θ1 (for example, 15°) with respect to a vertical plane perpendicular to the axial direction D. As will be described later, when the tip portion 48 of the wire 40 comes out of the accommodating hole 29, as shown in FIG. 5(B), a line L1 connecting a contact point P1 where the tip portion 48 of the wire 40 comes into contact with the groove portion 28 around the accommodating hole 29 and a contact point P2 where the base of the tip portion 48 of the wire 40 comes into contact with the pinion 52 is formed at an angle θ2 (for example, 15°) that is the same as the angle θ1 with respect to a vertical plane perpendicular to the axial direction D. Note that the angles θ1 and θ2 may be different angles.

[0056] 2 and 3 , the first intermediate portion 44, the second intermediate portion 45, the third intermediate portion 46, and the tip portion 48 are inserted into a through hole 52A formed in the pinion 52, and the base end portion 42 is held by the pinion 52. The third intermediate portion 46 and the tip portion 48 are inserted into the accommodation hole 29. The second intermediate portion 45 is accommodated in the groove portion 28. That is, the second intermediate portion 45 is disposed between the pinion 52 and the spool 20.

[0057] [Operation of the force limiter mechanism] In the webbing take-up device 10, the webbing 20A is pulled out from the spool 20 and attached to the occupant. Additionally, the spool 20 is rotated in the retracting direction A by the biasing force of the power spring of the biasing mechanism 16, and the webbing 20A is retracted onto the spool 20, thereby removing slack from the webbing 20A attached to the occupant.

[0058] In the event of a vehicle collision, the sensor mechanism 18 is activated, causing the lock pawl 56 to rotate in a direction approaching the ratchet teeth 14A of the cover plate 14, and the lock pawl 56 engages with the ratchet teeth 14A, thereby restricting the rotation of the lock base 54 in the pull-out direction B and restricting the rotation of the spool 20 in the pull-out direction B.

[0059] In this way, by restricting the rotation of the spool 20 in the unwinding direction B, the unwinding of the webbing 20A wound on the spool 20 is restricted, and the body of the occupant that tends to move inertially toward the front of the vehicle when the vehicle suddenly decelerates is restrained by the webbing 20A.

[0060] In this state, when the occupant's body, which is attempting to move inertially toward the front of the vehicle, pulls on the webbing 20A, the rotational force applied to the spool 20 in the unwinding direction B exceeds the mechanical strength of the torsion shaft 32 and the wire 40, causing the torsion shaft 32 to begin to twist and undergo plastic deformation, and the spool 20 begins to rotate in the unwinding direction B relative to the lock base 54, whose rotation is restricted.

[0061] Furthermore, when the spool 20 begins to rotate in the withdrawal direction B relative to the lock base 54 in this manner, the third intermediate portion 46 of the wire 40 comes out of the accommodating hole 29 while the base end portion 42 is held by the pinion 52, as shown in Figure 7(A).

[0062] In this way, the third intermediate portion 46 that has come out of the accommodating hole 29 is squeezed by the opening edge 29A of the accommodating hole 29 (see FIG. 4 ) and is pressed against the outer peripheral wall of the outer portion 24, and is curved to follow this outer peripheral wall, and the second intermediate portion 45 and the third intermediate portion 46 of the wire 40 are wound around the outer portion 24. In other words, the wire 40 is deformed in an emergency, and is wound around the outer portion 24 of the spool 20 when the webbing 20A is pulled out.

[0063] Here, when the load applied by the occupant to pull the webbing 20A from the spool 20 (rotational load in the unwinding direction B of the spool 20) is equal to or greater than the sum of the torsional load resistance of the torsion shaft 32 (first force limiter load) and the deformation resistance load of the pair of wires 40 (second force limiter load), the torsion shaft 32 is torsionally deformed and the pair of wires 40 are deformed, allowing the spool 20 to rotate in the unwinding direction B relative to the lock base 54 and the pinion 52. As a result, the kinetic energy of the occupant is absorbed by the torsional deformation of the torsion shaft 32 and the deformation of the pair of wires 40, thereby protecting the occupant.

[0064] When the spool 20 further rotates in the pull-out direction B relative to the lock base 54, the tip portion 48 of the wire 40 comes out of the accommodating hole 29 while the base end 42 is held by the pinion 52, as shown in Figure 7(B) . When the tip portion 48 of the wire 40 comes out of the accommodating hole 29 and the second intermediate portion 45 and the third intermediate portion 46 of the wire 40 are wound around the outer portion 24 of the spool 20, the tip portion 48 of the wire 40 is guided by the end face on one end side in the axial direction D of the sloped relief portion 24B.

[0065] At this time, the wire 40 tries to rotate around the base end 42 held by the pinion 52 as the center of rotation. Then, the second intermediate portion 45 or the third intermediate portion 46 radially presses the tip end 48 of the other wire 40. At this time, a space is formed between the tip end 48 and the inner rib 26, as the inner rib 26 is recessed inward in the winding direction on the side of the relief portion 24B.

[0066] Here, when the load (rotational load in the unwinding direction B of the spool 20) exerted by the occupant on the webbing 20A from the spool 20 is equal to or greater than the torsional load (first force limiter load) of the torsion shaft 32, the torsion shaft 32 is torsionally deformed.

[0067] As a result, the kinetic energy of the occupant is absorbed by the torsional deformation of the torsion shaft 32, thereby protecting the occupant.

[0068] That is, the kinetic energy of the occupant is absorbed in two stages, first by the torsional deformation of the torsion shaft 32 and the deformation of the pair of wires 40, and then by the torsional deformation of the torsion shaft 32, thereby protecting the occupant.

[0069] [Operation of the first embodiment] Next, the operation of the first embodiment will be described.

[0070] The webbing take-up device 10 of the first embodiment includes a spool 20 that can unwind and rewind a webbing 20A, and a rotating body 50 that is disposed opposite the spool 20 and is prevented from rotating in an emergency. The webbing take-up device 10 includes a wire 40 that is held at a base end 42 and disposed between the rotating body 50 and the spool 20, and that is wound around the inner rib 26 of the spool 20 when the webbing 20A is unwound by being deformed in an emergency, and an escape portion 24B from which a tip end 48 of the wire 40 escapes when the wire 40 is wound around the inner rib 26.

[0071] If the inner rib 26 does not have the relief portion 24B, when the tip end 48 of the wire 40 is removed from the accommodation hole 29 accommodated in the spool 20, the retention of the tip end 48 of the wire 40 is released, and the tip end 48 of the wire 40 is pressed strongly against the inner rib 26. Furthermore, because the base end 42 of the wire 40 is held in an eccentric position relative to the spool 20, when the wire 40 is wound around the inner rib 26, the wire 40 attempts to rotate inward in the winding direction around the base end 42 held by the pinion 52, but the tip end 48 of the wire 40 cannot completely avoid the inner rib 26. Furthermore, because the tip end 48 of the pulled-out wire 40 is bent inward in the winding direction, the tip end 48 of the wire 40 is pressed strongly against the inner rib 26. Here, the wire 40 formed from a piano wire is less susceptible to abrasion than the spool 20 formed from aluminum die-casting. Therefore, the tip end 48 of the wire 40 is pressed strongly against the inner rib 26, which causes the inner rib 26 of the spool 20 to be scraped. As a result, the force limiter load by the wire 40 temporarily increases.

[0072] In the first embodiment, when the wire 40 is wound around the inner rib 26, the escape portion 24B into which the tip portion 48 of the wire 40 escapes is provided, thereby preventing the tip portion 48 of the wire 40 from scraping the inner rib 26. Therefore, when the wire 40 is wound around the spool 20, a temporary increase in the load acting from the wire 40 on the spool 20 is prevented. As a result, a temporary increase in the force limiter load due to the wire 40 can be prevented.

[0073] In the webbing take-up device 10 of the first embodiment, the relief portion 24B is formed in the inner rib 26 in a sloped shape.

[0074] By forming the relief portion 24B in a sloped shape on the inner rib 26, when the wire 40 is wound around the inner rib 26, the tip 48 of the wire 40 is guided by the relief portion 24B formed in a sloped shape. This prevents the tip 48 of the wire 40 from being pressed strongly against the inner rib 26. As a result, the tip 48 of the wire 40 is prevented from scraping the inner rib 26. This makes it possible to suppress a temporary increase in the force limiter load caused by the wire 40 with a simple configuration without increasing the size.

[0075] In the webbing take-up device 10 of the first embodiment, the inner rib 26 is formed on the side of the relief portion 24B so as to be recessed inward in the winding direction.

[0076] The inner rib 26 is recessed inward in the winding direction on the side of the recess 24B, thereby forming a space inward in the winding direction for the tip 48 of the wire 40 to escape. Therefore, even when the outer wire 40 applies a force pressing the tip 48 of the wire 40 radially inward of the spool 20, a space inward in the winding direction for the tip 48 of the wire 40 to escape is formed. As a result, scraping of the inner rib 26 by the tip 48 of the wire 40 is further suppressed. Furthermore, a temporary increase in the load acting from the wire 40 on the spool 20 when winding the wire 40 is further suppressed. As a result, a temporary increase in the force limiter load due to the wire 40 can be further suppressed.

[0077] In the webbing take-up device 10 of the first embodiment, the relief portion 24B is formed in the vicinity of the accommodation hole 29 of the spool 20 in which the tip portion 48 of the wire 40 is accommodated.

[0078] By forming the relief portion 24B near the accommodating hole 29 of the spool 20, the tip portion 48 of the wire 40 escapes to the relief portion 24B when the tip portion 48 of the wire 40 is pulled out from the accommodating hole 29. Therefore, when the tip portion 48 of the wire 40 is pulled out from the accommodating hole 29 of the spool 20, scraping of the inner rib 26 by the tip portion 48 of the wire 40 is suppressed. As a result, a temporary increase in the force limiter load due to the wire 40 can be suppressed.

[0079] In the webbing take-up device 10 of the first embodiment, two wires 40 are provided.

[0080] By providing two wires 40, even if the movement of the tip end 48 of one wire 40 radially outward of the spool 20 is hindered by another wire 40, the relief portion 24B can prevent the tip end 48 from scraping the inner rib 26. Furthermore, because a force limiter load can be applied to the two wires 40, a force limiter structure can be achieved that generates two high-load force limiter loads.

[0081] Furthermore, by using a long wire 40, the stroke over which the force limiter load acts can be lengthened. Furthermore, because the width of the main body portion 24A of the inner rib 26 is constant and the width of the relief portion 24B is recessed inward in the winding direction, the shape of the two wires 40 when wound around can be prevented from becoming elliptical. In other words, the shape of the two wires 40 when wound around can be maintained as a circle. Therefore, a temporary increase in the force limiter load can be prevented.

[0082] Second Embodiment The webbing take-up device of the second embodiment differs from the webbing take-up device of the first embodiment in that the configuration of the relief portion is different.

[0083] The configuration of the webbing take-up device of the second embodiment will be described below. Note that the same terms or symbols will be used to describe parts that are the same as or equivalent to those described in the first embodiment.

[0084] [Webbing take-up device configuration] As shown in Fig. 8, the inner rib 126 constituting the wound portion is formed on the inner edge of the flange portion 22 so as to protrude toward one end side in the axial direction D. The inner rib 126 is formed in an annular shape. The inner rib 126 is composed of an inner portion 25 and an outer portion 124.

[0085] Two outer portions 124 are formed on the outside of the inner portion 25 so as to connect the two receiving holes 29. The height of the outer portions 124 in the axial direction D can be made approximately constant.

[0086] As shown in Figures 8 and 9(B), the relief portion 128 is formed in a concave shape recessed from the bottom surface of the groove portion 28 toward the other end side in the axial direction D. The relief portion 128 is provided so as to extend from the accommodating hole 29 in the winding direction A. The relief portion 128 is provided on the radially outer side of the inner portion 25. The relief portion 128 is formed so as to extend from the accommodating hole 29 until it reaches the outer wire 40 when the wire 40 is wound radially overlappingly around the inner rib 126 configured as a winding portion. In other words, the relief portion 128 is formed in a concave shape around the outer portion 124.

[0087] The length of the relief portion 128 in the winding direction A can be approximately the same as the length of the tip portion 48. The axial depth of the relief portion 128 is formed to be approximately the maximum diameter of the tip portion 48. The relief portion 128 is formed so as to be connected to the accommodating hole 29, and an opening edge 29A is formed between the relief portion 128 and the accommodating hole 29.

[0088] [Operation of the force limiter mechanism] In the webbing take-up device 110 of the second embodiment, with the base end 42 held by the pinion 52, the webbing take-up device 110 operates in the same manner as the webbing take-up device 10 of the first embodiment until the tip end 48 of the wire 40 comes out of the storage hole 29.

[0089] The tip portion 48 of the wire 40 comes out of the accommodating hole 29, and the second intermediate portion 45 and the third intermediate portion 46 of the wire 40 are wound around the outer portion 124 of the spool 20. At this time, as shown in Figures 9(A) and 9(B), the tip portion 48 of the wire 40 is guided by the relief portion 128 and slips into the other end side of the second intermediate portion 45 of the other wire 40 in the axial direction D.

[0090] [Operation of the second embodiment] In the webbing take-up device 10 of the second embodiment, the relief portion 128 is formed in the vicinity of the accommodation hole 29 of the spool 20 in a concave shape in the axial direction D of the spool 20.

[0091] The relief portion 128 is formed in a concave shape in the axial direction D of the spool 20 near the housing hole 29 of the spool 20. This allows the wire 40 to be wound around the inner rib 126, and when the tip end 48 of the wire 40 comes out of the housing hole 29, the second intermediate portion 45 of the other wire 40 acts to hold down the tip end 48 of the wire 40. That is, the tip end 48 of one wire 40 can be slipped under the other wire 40. This prevents the tip end 48 of the wire 40 from being pressed strongly against the inner rib 126. As a result, the tip end 48 of the wire 40 is prevented from scraping the inner rib 126. This simple configuration can therefore prevent a temporary increase in the force limiter load caused by the wire 40.

[0092] The other configurations and effects are substantially the same as those of the first embodiment, and therefore the description thereof will be omitted.

[0093] The webbing take-up device of the present invention has been described above based on the above-mentioned embodiments. However, the specific configuration is not limited to these embodiments, and design changes are permitted as long as they do not deviate from the gist of the invention according to the claims. In addition, the relief portion 24B of the first embodiment and the relief portion 128 of the second embodiment can be combined.

[0094] In each of the above embodiments, the tip portion 48 is formed in a shape that tapers toward the tip of the wire 40. However, the tip portion is not limited to this form and may be formed in a round bar shape.

[0095] In each of the above embodiments, the wire 40 is formed in a generally crank shape. However, the wire is not limited to this shape and may be formed in a straight rod shape, for example.

[0096] In each of the above embodiments, an example has been shown in which the accommodating hole 29 is formed in the radially inner portion of the groove portion 28. However, the accommodating hole may be formed in the radially outer portion of the groove portion 28 or in the radially intermediate portion.

[0097] In the above embodiments, the two wires 40 have the same length and the same shape. However, the two wires may have different lengths. This allows the occupant's kinetic energy to be absorbed in three stages: first by the torsional deformation of the torsion shaft 32 and the deformation of the two wires 40, then by the torsional deformation of the torsion shaft 32 and the deformation of one wire 40, and then by the torsional deformation of the torsion shaft 32, thereby protecting the occupant. The two wires 40 may also have different diameters.

[0098] In each of the above embodiments, an example has been shown in which two wires 40 are provided on the spool 20. However, the spool 20 may be provided with one wire 40, or three or more wires 40. [Explanation of symbols]

[0099] 10 webbing take-up device, 20A webbing, 20 spool, 50 rotating body, 42 base end portion, 26 inner rib (an example of a winding portion), 24B relief portion, 29 accommodation hole

Claims

1. a spool that can unwind and retract the webbing; a rotating body that is disposed opposite the spool and whose rotation is prevented in the event of a vehicle collision; a wire whose base end is held by the rotating body, which is disposed between the rotating body and the spool, which deforms when the webbing is pulled out in the event of a vehicle collision, and which is wound around a winding portion of the spool; a relief portion through which a tip end of the wire is relieved from a load applied when the wire is wound around the winding portion; A webbing take-up device comprising:

2. The relief portion is formed in a sloped shape on the winding portion. The webbing take-up device according to claim 1 .

3. The relief portion is formed in a recessed shape around the wound portion. The webbing take-up device according to claim 1 or 2.

4. The winding portion is formed to be recessed inward in the winding direction on the side of the relief portion. The webbing take-up device according to any one of claims 1 to 3.

5. The relief portion is formed around the receiving hole of the spool in which the tip end of the wire is received. The webbing take-up device according to any one of claims 1 to 4.

6. The wire is provided in plurality. The webbing take-up device according to any one of claims 1 to 5.

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