Webbing winding device

Abstract

To dispense with a stopper member for restricting rotation of a torsion shaft to a spool.SOLUTION: A webbing winding device includes a spool, a trigger wire 40, a sub-torsion shaft 44 for permitting rotation of the spool 20 in a drawing direction by twisting, and a clutch 52. The sub-torsion shaft 44 is engage with the clutch 52, and the trigger wire 40 is engaged therewith. The clutch 52 restricts rotation of the sub-torsion shaft 44 to the spool by engaging a part of a member engaged with the sub-torsion shaft 44 in a relatively non-rotatable manner with the trigger wire 40.SELECTED DRAWING: Figure 12

Description

[Technical field]

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

[0002] The following Patent Document 1 discloses a webbing take-up device that includes a stopper member for limiting rotation of the torsion shaft relative to the spool when the torsion shaft is engaged with the spool.

[0003] From the viewpoint of reducing the number of parts of the webbing take-up device, it is desirable to be able to eliminate the stopper member that limits the rotation of the torsion shaft relative to the spool. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-1315 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 webbing take-up device that can dispense with a stopper member for limiting the rotation of the torsion shaft relative to the spool. [Means for solving the problem]

[0006] The webbing take-up device of the first aspect includes a spool around which a webbing to be worn by an occupant is wound and which rotates in the pull-out direction as the webbing is pulled out, a trigger member and a torsion shaft provided on the spool, which engages with the spool and twists to allow rotation of the spool in the pull-out direction, and a clutch that engages the torsion shaft and engages the trigger member, and a part of a member engaged with the torsion shaft so as not to rotate relative to the torsion shaft is engaged with the trigger member, thereby restricting rotation of the torsion shaft relative to the spool, and that is activated and engaged with a locking member when the trigger member is activated and disengaged, thereby restricting rotation relative to the locking member.

[0007] A webbing take-up device according to a second aspect is the webbing take-up device of the first aspect, wherein the clutch is supported in a state where it can rotate relative to the torsion shaft, and includes a clutch guide whose rotation is restricted by engagement of the trigger member, a clutch cover fixed to the torsion shaft in a state where it cannot rotate relative to the torsion shaft, and a clutch plate provided between the clutch guide and the clutch cover, and displaced and engaged with the locking member when the clutch guide rotates relative to the sleeve, and wherein a part of the clutch cover is engaged with the trigger member, thereby restricting the rotation of the torsion shaft relative to the spool. A webbing take-up device according to a third aspect is the webbing take-up device of the second aspect, wherein a part of the clutch cover extends towards the trigger member and serves as a locking piece that is engaged with the trigger member.

[0008] The webbing take-up device of the fourth aspect is the webbing take-up device of the third aspect, wherein a recess is formed on both sides of the locking piece portion in the rotational circumferential direction of the clutch cover, the recess being open on the radially outward side, and the trigger member is capable of being positioned in one of the recesses, while the locking piece portion is engaged with the trigger member, and the trigger member is unable to be positioned in the other recess. Effect of the Invention

[0009] In the webbing take-up device according to the first aspect, the webbing to be worn by an occupant is taken up on the spool. When the webbing is pulled out, the spool rotates in the pull-out direction. When the trigger member is actuated and the trigger member is disengaged from the clutch, the clutch is actuated. When the clutch is actuated, the clutch engages with the locking member, and the rotation of the clutch relative to the locking member is restricted. When the webbing is pulled by the occupant, a rotational force in the pull-out direction is input to the spool. When this rotational force exceeds the torsional load resistance of the torsion shaft, the torsion shaft is twisted. This allows the rotation of the spool in the pull-out direction relative to the locking member. In the webbing take-up device according to the first aspect, a part of the member in the clutch that is engaged with the torsion shaft so as not to rotate relative to the torsion shaft is engaged with the trigger member. This makes it possible to restrict the rotation of the torsion shaft relative to the spool. In this way, in the webbing take-up device according to the first aspect, it is possible to eliminate the need to provide a stopper member for restricting the rotation of the torsion shaft relative to the spool. In other words, the stopper member for limiting the rotation of the torsion shaft relative to the spool can be eliminated.

[0010] In the webbing take-up device according to the second aspect, when the trigger member is actuated to disengage the trigger member from the clutch guide and rotate the clutch guide, the clutch plate engages with the locking member, and the rotation of the clutch relative to the locking member is restricted. Meanwhile, in the webbing take-up device according to the second aspect, a part of the clutch cover is engaged with the trigger member. This makes it possible to restrict the rotation of the torsion shaft relative to the spool. In this way, the webbing take-up device according to the second aspect can eliminate the need to provide a stopper member for restricting the rotation of the torsion shaft relative to the spool. In other words, the stopper member for restricting the rotation of the torsion shaft relative to the spool can be eliminated.

[0011] In the webbing take-up device according to the third aspect, for example, when the clutch is assembled to the spool, the locking piece of the clutch cover can be easily locked to the trigger wire.

[0012] In the webbing take-up device according to the fourth aspect, recesses that are open radially outward are formed on both sides of the locking piece in the rotational circumferential direction of the clutch cover. The locking piece is locked to the trigger member in a state in which the trigger member can be placed in one of the recesses. Here, the trigger member cannot be placed in the other recess. This makes it possible to prevent the locking piece from being locked to the trigger member in a state in which the trigger member is placed in the other recess. In other words, it is possible to prevent incorrect assembly during manufacture of the webbing take-up device. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is an exploded perspective view showing a configuration of a main part of the webbing take-up device according to the embodiment. [Diagram 2] 2 is a view of the spool shown in FIG. 1 as viewed from the other axial side. [Diagram 3] 2 is an enlarged perspective view showing a sub-torsion shaft housing portion of the spool shown in FIG. 1. [Figure 4] FIG. 4 is a perspective view showing a state before the sub torsion shaft is inserted into the spool. [Diagram 5] FIG. 2 is a partially cutaway perspective view showing an initial state of a process of inserting the sub torsion shaft into the spool. [Figure 6] FIG. 13 is a partially cutaway perspective view showing a state upon completion of a process of inserting the sub torsion shaft into the spool. [Figure 7] 2 is an exploded perspective view showing a configuration of a clutch of the webbing take-up device shown in FIG. 1. [Figure 8] 2 is an exploded perspective view of a clutch of the webbing take-up device shown in FIG. 1, as viewed from the spool side. [Figure 9] 4 is a view of the clutch cover as seen from the other axial side. FIG. [Figure 10] FIG. 4 is a view of the clutch cover as seen from one axial side. [Figure 11] FIG. 13 is a diagram showing the locking piece portion in a state before being bent. [Figure 12] 4 is a cross-sectional view showing the clutch and other components cut at a location corresponding to the clutch cover. FIG. [Figure 13] 13 is a cross-sectional view showing the clutch and the like taken along the line AA shown in FIG. 12. [Figure 14] 1 is a cross-sectional view showing a main torsion shaft and a sub torsion shaft to which a structure for facilitating screwing of a screw into the sub torsion shaft is applied. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A webbing take-up device according to an embodiment of the present invention will be described with reference to Figs. 1 to 13.

[0015] 1, a webbing take-up device 10 according to an embodiment of the present invention includes a frame 12, a spool 20, a webbing 22, a lock gear 24, and a main torsion shaft 32, a trigger wire 40, a sub torsion shaft 44, and a clutch 52 that constitute a force limiter mechanism 31. The webbing take-up device 10 also includes a force limiter load switching mechanism (not shown). The frame 12 will be first described below, and then the spool 20, the webbing 22, the lock gear 24, the main torsion shaft 32, the trigger wire 40, the sub torsion shaft 44, the clutch 52, and the force limiter load switching mechanism will be described in this order.

[0016] 1, the frame 12 is formed in a generally concave shape in a plan view and includes a plate-like back plate 14 that is fixed to the vehicle body. Leg pieces 16, 18 extend at a generally right angle from both ends in the width direction of the back plate 14. A well-known locking mechanism (not shown) is attached to the outer side of the leg piece 18.

[0017] The spool 20 is formed in a cylindrical shape having a through hole 21 that passes through in the axial direction, and is disposed between the leg pieces 16 and 18 of the frame 12. The spool 20 is disposed with its axial direction aligned with the opposing direction of the leg pieces 16 and 18, and is rotatably supported by the frame 12 via a main torsion shaft 32, a sub torsion shaft 44, etc., which will be described later.

[0018] The webbing 22 is attached to the body of an occupant, and a base end portion, which is one end portion in the longitudinal direction, of the webbing 22 is engaged with the spool 20. The spool 20 is configured to rotate in one rotation direction, that is, a winding direction (the direction of arrow A in FIG. 1, etc.), to wind up and store the webbing 22 from the base end side.

[0019] The lock gear 24 is disposed coaxially with the spool 20 on one axial side of the spool 20. A gear portion 26 is formed on the outer periphery of the lock gear 24. A through hole 28 is formed in the axial center of the lock gear 24, penetrating in the axial direction, and a spline-shaped engaged portion 30 is formed on the inner periphery of the through hole 28.

[0020] The lock gear 24 engages with a lock member (not shown) when the vehicle suddenly decelerates or when the spool 20 suddenly rotates in the pull-out direction. As a result, the rotation of the lock gear 24 in the pull-out direction (the direction of arrow B in FIG. 1, etc.) is restricted (locked), and the rotation of the spool 20 in the pull-out direction is restricted.

[0021] The main torsion shaft 32 is disposed coaxially with the spool 20 and the lock gear 24, and is inserted into the through hole 21 of the spool 20 and the through hole 28 of the lock gear 24, respectively. The main torsion shaft 32 has a first spline-shaped engaging portion 34 formed in the longitudinal center thereof, and a second spline-shaped engaging portion 36 formed at the tip thereof. The first engaging portion 34 is engaged with the engaged portion 30 of the lock gear 24, whereby the main torsion shaft 32 is fixed to the lock gear 24 so as to be rotatable together with the lock gear 24. The second engaging portion 36 is engaged with an engaged portion (not shown) formed in the axial middle portion of the inner periphery of the spool 20, whereby the main torsion shaft 32 is fixed to the spool 20 so as to be rotatable together with the spool 20. The portion of the main torsion shaft 32 between the first engaging portion 34 and the second engaging portion 36 is configured as a first energy absorbing portion 38 for absorbing the kinetic energy of the occupant used to pull the webbing 22, as described later.

[0022] A base end 40A of a trigger wire 40 serving as a trigger member is inserted into a hole 29 formed in the lock gear 24 at a position radially outward of the through hole 28, and is engaged with the lock gear 24. On the other hand, the tip side of the trigger wire 40 beyond the base end 40A is inserted into a hole 42 formed in the spool 20 in parallel with the through hole 21, and the tip end 40B protrudes from the spool 20 to the other axial side.

[0023] The sub torsion shaft 44 is disposed coaxially with the main torsion shaft 32, and a portion of the sub torsion shaft 44 on the base end side from the longitudinal center is inserted into the through hole 21 of the spool 20. On the other hand, a portion of the sub torsion shaft 44 on the tip end side from the longitudinal center protrudes from the spool 20 to the other axial direction side. The sub torsion shaft 44 has a first engagement portion 46 at least partially splined at its base end, and a second engagement portion 48 also splined at its tip end. The first engagement portion 46 is engaged with an axial middle portion of the inner periphery of the spool 20. As a result, the sub torsion shaft 44 is fixed to the spool 20 so as to be rotatable together with the spool 20. Furthermore, a portion of the sub torsion shaft 44 between the first engagement portion 46 and the second engagement portion 48 is configured as a second energy absorbing portion 50 for absorbing the kinetic energy of the occupant who is used to pull the webbing 22, as described later.

[0024] 2 and 3, a plurality of (four in this embodiment) insertion grooves 21B are formed in the inner periphery of the sub torsion shaft accommodating portion 21A in which the sub torsion shaft 44 is accommodated in the through hole 21 of the spool 20. The insertion grooves 21B are formed in a substantially trapezoidal shape when viewed from the axial direction of the spool 20, and open to the radially inner side of the spool 20. The insertion grooves 21B are disposed at predetermined intervals along the circumferential direction of the spool 20, and extend along the axial direction of the spool 20.

[0025] Further, a plurality of (four in this embodiment) engagement grooves 21C are formed in the sub-torsion shaft accommodating portion 21A of the spool 20. Each engagement groove 21C extends from the insertion groove 28 along the winding direction of the spool 20 and opens to the radially inner side of the spool 20. Each engagement groove 21C is connected to one axial side portion of the spool 20 of the insertion groove 21B. The engagement groove 21C does not extend from the connected insertion groove 28 to the adjacent insertion groove 21B. As a result, the surface of the engagement groove 21C on the other axial side of the spool 20 is the axial locking surface 21D, and the surface of the engagement groove 21C on the winding direction side of the spool 20 is the circumferential locking surface 21E. The axial locking surface 21D and the engagement groove 21C are formed to be engageable with the engaged protrusion 46A of the sub-torsion shaft 44, which will be described later in detail.

[0026] 4, the first engagement portion 46 of the sub torsion shaft 44 is configured to be able to be inserted into the sub torsion shaft accommodating portion 21A. A plurality of engaged projections 46A (four in this embodiment) having a substantially trapezoidal cross section are provided on the outer periphery of the first engagement portion 46, and the engaged projections 46A protrude from the outer periphery of the first engagement portion 46 to the radially outward side of the first engagement portion 46. The engaged projections 46A are also arranged at predetermined intervals in the circumferential direction of the first engagement portion 46 corresponding to the insertion groove portion 21B, and are configured to be able to be inserted into the insertion groove portion 28.

[0027] As shown in FIG. 5, the sub torsion shaft 44 is inserted into the sub torsion shaft accommodating portion 21A of the spool 20 from the other axial side of the spool 20. At this time, the first engaging portion 46 of the sub torsion shaft 44 is inserted into the sub torsion shaft accommodating portion 21A, and the engaged protrusion 46A of the sub torsion shaft 44 is inserted into the insertion groove portion 21B of the spool 20. Then, as shown in FIG. 6, after the engaged protrusion 46A reaches the one axial side portion of the spool 20 of the insertion groove portion 21B, the sub torsion shaft 44 is rotated in the winding direction. As a result, the engaged protrusion 46A is disposed in the engagement groove portion 30 of the spool 20, and the engaged protrusion 46A is engaged with the axial locking surface 21D and the circumferential locking surface 21E of the engagement groove portion 21C. Therefore, the movement of the sub torsion shaft 44 to the other axial side and the winding direction is restricted. Through the above steps, the sub torsion shaft 44 is assembled to the spool 20.

[0028] As shown in FIGS. 7 and 8, the clutch 52 includes a sleeve 54, a clutch guide 64, a clutch base 82, a clutch cover 88, a pair of clutch plates 100, a screw 108, and a pair of coil springs 98.

[0029] As shown in FIG. 8, the sleeve 54 is disposed coaxially with the sub torsion shaft 44. A through hole 56 penetrating in the axial direction is formed in the axial center of the sleeve 54, and the sub torsion shaft 44 is inserted into the through hole 56. As shown in FIG. 7, a spline-shaped engaged portion 58 is formed on the tip side of the inner periphery of the sleeve 54. The second engaging portion 48 (see FIG. 1) of the sub torsion shaft 44 engages with the engaged portion 58, so that the sleeve 54 is engaged with the sub torsion shaft 44 so as to be rotatable together with the sub torsion shaft 44. The base end side of the sleeve 54 is a support portion 60 having a circular outer shape, and the tip side of the sleeve 54 from the support portion 60 is an engagement portion 62 having a hexagonal outer shape.

[0030] The clutch guide 64 is made of resin, for example, and is formed in an annular shape having a through hole 66 penetrating in the axial direction. The above-mentioned support portion 60 is inserted into this through hole 66, whereby the clutch guide 64 is supported so as to be rotatable relative to the sleeve 54. A pair of coil spring accommodating portions 68 for accommodating coil springs 98 are formed at two positions in the circumferential direction of the clutch guide 64. These coil spring accommodating portions 68 are arranged point-symmetrically with respect to the center of the clutch guide 64, and each is formed in a substantially J-shape having an outer wall portion 70 and an inner wall portion 72 extending in the circumferential direction of the clutch guide 64, and a connecting wall portion 74 extending in the radial direction of the clutch guide 64 and connecting each end of the outer wall portion 70 and the inner wall portion 72. In addition, an elongated guide hole 70A having a longitudinal direction in the circumferential direction is formed in the outer wall portion 70.

[0031] In addition, in the clutch guide 64, a pair of clutch plate accommodating portions 76 for accommodating clutch plates 100 are formed adjacent to each coil spring accommodating portion 68. In each clutch plate accommodating portion 76, a first support wall portion 78 extending from the connecting wall portion 74 toward the opposite side to the inner wall portion 72, and a second support wall portion 80 spaced apart from the connecting wall portion 74 on the opposite side to the outer wall portion 70 with respect to the connecting wall portion 74 are provided.

[0032] The clutch base 82 is configured to have an annular fitted portion 84. The fitting portion 62 of the sleeve 54 is fitted (press-fitted) into the inside of this fitted portion 84, whereby the clutch base 82 is fixed to the sleeve 54 so as to be rotatable integrally with it. In addition, the clutch base 82 is formed with a pair of locking portions 86 that protrude outward from the fitted portion 84. These locking portions 86 are engaged with base ends of arms 102 formed on a clutch plate 100, which will be described later.

[0033] 7, 8, 9, and 10, the clutch cover 88 is formed, for example, by pressing a metal plate cut into a predetermined shape. The clutch cover 88 is disposed coaxially with the sleeve 54, and is disposed on the opposite side of the clutch guide 64 from the spool 20 and opposed to the clutch guide 64.

[0034] The clutch cover 88 includes a base plate portion 88A formed in an annular shape having a through hole 90 penetrating in the axial direction, and a plurality of engagement claws 92 extending from the base plate portion 88A toward the inner peripheral side of the through hole 90. The plurality of engagement claws 92 are arranged at intervals in the circumferential direction and are inclined toward the other axial side with respect to the base plate portion 88A. The engagement portion 62 of the sleeve 54 is inserted into the through hole 90, and the plurality of engagement claws 92 are engaged with the engagement portion 62, so that the clutch cover 88 is fixed to the sleeve 54 and, by extension, the sub torsion shaft 44 so as to be rotatable together with the sleeve 54. The clutch cover 88 also includes a pair of sector-shaped portions 88B extending radially outward from the base plate portion 88A and arranged at intervals in the circumferential direction. The pair of sector-shaped portions 88B are adapted to cover the pair of clutch plate accommodating portions 76 formed in the clutch guide 64 from the other axial side.

[0035] The clutch cover 88 also includes a pair of locking claw support plate portions 88C extending from the outer periphery of the base plate portion 88A and spaced apart in the circumferential direction. The locking claw support plate portion 88C includes a first extending portion 88C1 extending radially outward from the outer periphery of the base plate portion 88A, a second extending portion 88C2 extending from a radially outer end of the first extending portion 88C1 toward one axial direction side, and a guide claw portion 96 extending radially outward from an end of the second extending portion 88C2 on one axial direction side. The clutch cover 88 also includes a pair of spring locking claw portions 94 extending from the second extending portions 88C2 of the pair of locking claw support plate portions 88C toward the winding direction side. The pair of spring locking claw portions 94 are arranged point symmetrically with respect to the center of the clutch cover 88. One end of a coil spring 98 disposed in the coil spring housing portion 68 of the clutch guide 64 is respectively engaged with the pair of spring locking claws 94. Also, the guide claws 96 are disposed in guide holes 70A provided in the clutch guide 64 and moved along the guide holes 70A, thereby allowing the clutch guide 64 to rotate relatively within a specified range.

[0036] The clutch cover 88 also includes a pair of locking pieces 88D extending from the outer periphery of the base plate 88A and spaced apart from each other in the circumferential direction. One of the locking pieces 88D is disposed on the pull-out direction side of one of the locking claw support plates 88C and on the winding direction side of one of the sector-shaped parts 88B. The other of the locking pieces 88D is disposed on the pull-out direction side of the other of the locking claw support plates 88C and on the winding direction side of the other sector-shaped part 88B. More specifically, the locking pieces 88D include a base end 88D1 extending radially outward from the outer periphery of the base plate 88A, and an inclined part 88D2 extending radially outward from the radially outer end of the base end 88D1 toward one axial side. Here, FIG. 11 shows the clutch cover 88 before the inclined part 88D2 is bent relative to the base end 88D1. As shown in this figure, the circumferential width dimension W1 of the base end 88D1 gradually increases from the boundary portion 88E between the inclined portion 88D2 and the base end 88D1 toward the opposite side of the inclined portion 88D2. Also, the circumferential width dimension W2 of the inclined portion 88D2 gradually increases from the boundary portion 88E between the inclined portion 88D2 and the base end 88D1 toward the opposite side of the base end 88D1.

[0037] As shown in Figs. 9 and 10, a recess 88F with an open radial outer side is formed between the locking piece 88D and the sector-shaped portion 88B when viewed from the axial direction. The circumferential distance between the locking piece 88D and the sector-shaped portion 88B that constitute both circumferential edges of this recess 88F is set to be larger than the outer diameter of the tip of the trigger wire 40 (see Fig. 1). In addition, a recess 88G with an open radial outer side is formed between the locking piece 88D and the locking claw portion support plate portion 88C when viewed from the axial direction. The circumferential distance between the locking piece 88D and the locking claw portion support plate portion 88C that constitute both circumferential edges of this recess 88G is set to be smaller than the outer diameter of the tip of the trigger wire 40 (see Fig. 1).

[0038] 12 and 13, when the sub torsion shaft 44 to which the clutch 52 is attached is assembled to the spool 20, the end face on the pull-out direction side of one locking piece portion 88D of the clutch cover 88 is locked to the tip portion 40B of the trigger wire 40. This restricts rotation of the sub torsion shaft 44, which is rotatable integrally with the sub torsion shaft 44, in the pull-out direction side. This allows the sub torsion shaft 44 to be maintained in an assembled state with the spool 20 as shown in FIG.

[0039] As shown in Fig. 7, the clutch plate 100 is disposed between the clutch cover 88 and the clutch guide 64. The clutch plate 100 has an arm portion 102 and an arc portion 104 formed at the tip of the arm portion 102. A rotating shaft 106 is formed at the base end of the arm portion 102, protruding toward the clutch cover 88 and extending along the axial direction of the sub torsion shaft 44. The rotating shaft 106 is inserted into a hole 89 formed in the clutch cover 88, so that the clutch plate 100 is rotatably supported by the clutch cover 88. In addition, spur-toothed knurled teeth 104A are formed on the outer periphery of the arc portion 104 (the tip of the clutch plate 100).

[0040] As shown in FIG. 8, the screw 108 is configured to have a threaded portion 110 and a pressing portion 112 having a diameter larger than that of the threaded portion 110. The threaded portion 110 is screwed into a screw hole 45 (see FIG. 1) formed in the tip portion of the sub torsion shaft 44, whereby the screw 108 is fixed to the tip portion of the sub torsion shaft 44. In addition, in this state in which the screw 108 is fixed to the tip portion of the sub torsion shaft 44, the pressing portion 112 abuts against the tip portion of the sleeve 54. As a result, the movement of the sleeve 54 in the removal direction relative to the sub torsion shaft 44 is restricted. In this state, the clutch guide 64 is restricted in its axial movement by the clutch cover 88 and the spool 20.

[0041] 7 and 8, a hole 65 is formed in the clutch guide 64. The tip 40B (see FIG. 1) of the trigger wire 40 is inserted into this hole 65. As a result, the clutch guide 64 is restricted from rotating relative to the spool 20 and the clutch cover 88 when placed in the inoperative position (the clutch guide 64 is restrained in the inoperative position).

[0042] Furthermore, when the clutch guide 64 is restrained in the non-operating position as described above, the coil spring 98 is compressed between the coil spring accommodating portion 68 (connecting wall portion 74) of the clutch guide 64 and the spring locking claw portion 94 of the clutch cover 88.

[0043] Meanwhile, in this state, a sufficient gap is secured between the hole 89 (rotation shaft 106 of the clutch plate 100) of the clutch cover 88 and the connecting wall 74, and the clutch plate 100 is accommodated in the clutch plate accommodating portion 76 such that the knurled teeth 104A are accommodated inside the outer periphery of the clutch guide 64. Also, in this state, the connecting wall 74 abuts against the tip of the arc portion 104.

[0044] (Actions and Effects of the Present Embodiment) Next, the operation and effects of this embodiment will be described.

[0045] As shown in Figs. 1, 7 and 8, in the webbing take-up device 10 according to the present embodiment, the spool 20, the lock gear 24, the main torsion shaft 32, the sub torsion shaft 44, and the clutch 52 (including the sleeve 54, the clutch base 82, the clutch plate 100, and the screw 108) are configured to be rotatable together in the winding direction and the unwinding direction. Therefore, the webbing 22 is pulled out from the spool 20, so that the webbing 22 is attached to the body of the vehicle occupant. In addition, when the vehicle is suddenly decelerated in a state in which the webbing 22 is attached to the body of the vehicle occupant, for example, the lock mechanism is activated, and the rotation of the lock gear 24 in the unwinding direction is restricted. As a result, the rotation of the spool 20 connected to the lock gear 24 via the main torsion shaft 32 in the unwinding direction is restricted, and the unwinding of the webbing 22 from the spool 20 is restricted. Therefore, the body of the occupant attempting to move forward of the vehicle is restrained by the webbing 22.

[0046] Furthermore, with the rotation of the lock gear 24 in the pull-out direction restricted, if the occupant's body pulls the webbing 22 with even greater force and the rotational force of the spool 20 in the pull-out direction based on this pulling force exceeds the torsional load (deformation resistance load) of the first energy absorption section 38 of the main torsion shaft 32, the force limiter mechanism 31 is activated, and the twisting (deformation) of the first energy absorption section 38 allows the spool 20 to rotate in the pull-out direction above the force limiter load (the torsional load resistance of the first energy absorption section 38).

[0047] Therefore, the twisting of the first energy absorbing portion 38 rotates the spool 20 in the unwinding direction and the webbing 22 is unwound from the spool 20, thereby reducing the load (burden) on the chest of the occupant caused by the webbing 22. In addition, the kinetic energy of the occupant contributing to the pulling of the webbing 22 is absorbed by an amount equivalent to the twisting of the first energy absorbing portion 38.

[0048] On the other hand, as described above, the rotation of the spool 20 in the pull-out direction relative to the lock gear 24 means that the lock gear 24 is rotated in the winding direction relative to the spool 20. Therefore, when the lock gear 24 is rotated in the winding direction relative to the spool 20, the base end 40A of the trigger wire 40 moves in the circumferential direction of the main torsion shaft 32 while the tip side of the base end 40A of the trigger wire 40 remains inserted in the hole 42 of the spool 20, so that the tip side of the base end 40A of the trigger wire 40 is pulled toward the lock gear 24 with respect to the hole 42.

[0049] As a result, the tip portion 40B of the trigger wire 40 is pulled out of the hole 65 of the clutch guide 64 and released, and the restricted state of relative rotation of the clutch guide 64 with respect to the spool 20 and the clutch cover 88 is released.

[0050] When the clutch guide 64 is rotated from the non-operating position to the operating position by the biasing force of the coil spring 98, the distance between the hole 89 (rotating shaft 106 of the clutch plate 100) of the clutch cover 88 and the connecting wall 74 of the clutch guide 64 becomes shorter, and the tip of the arcuate portion 104 of the clutch plate 100 is pressed (guided) in the tangential direction of the clutch guide 64 by the connecting wall 74. As a result, the clutch plate 100 is rotated toward the locking member (not shown), and the knurled teeth 104A of the clutch plate 100 mesh with the locking member. As a result, the clutch plate 100 and the lock ring 190 are joined together. At this time, the locking portion 86 formed on the clutch base 82 pushes the base end of the arm portion 102 of the clutch plate 100 in the pull-out direction, so that the clutch plate 100 is pressed against the lock ring 190, and the joined state of the two is maintained.

[0051] Here, with the rotation of the locking member stopped, if the occupant's body pulls the webbing 22 with an even greater force and the rotational force of the spool 20 in the unwinding direction based on this pulling force exceeds the sum of the torsional load (deformation resistance load) of the first energy absorbing portion 38 of the main torsion shaft 32 and the torsional load (deformation resistance load) of the second energy absorbing portion 50 of the sub torsion shaft 44, the torsion (deformation) of the first energy absorbing portion 38 and the second energy absorbing portion 50 will allow rotation of the spool 20 in the unwinding direction above the force limiter load (the sum of the torsional load resistance of the first energy absorbing portion 38 and the torsional load resistance of the second energy absorbing portion 50).

[0052] Therefore, the twisting of the first energy absorbing portion 38 and the second energy absorbing portion 50 causes the spool 20 to rotate in the pull-out direction and the webbing 22 to be pulled out from the spool 20, thereby reducing the load (burden) on the occupant's chest caused by the webbing 22 and absorbing the kinetic energy of the occupant used to pull the webbing 22 by an amount equivalent to the twisting of the first energy absorbing portion 38 and the second energy absorbing portion 50.

[0053] On the other hand, when the rotation of the locking member is permitted, the locking member can rotate in the pull-out direction together with the clutch 52 (sleeve 54, clutch base 82, and clutch plate 100) and the spool 20. For this reason, no twisting occurs in the second energy absorbing portion 50, and so the twisting (deformation) of the first energy absorbing portion 38 allows the spool 20 to rotate in the pull-out direction at or above the force limiter load (the torsional load resistance of the first energy absorbing portion 38).

[0054] That is, when the rotation of the locking member is stopped, the force limiter load is set to the sum of the torsional load resistance of the first energy absorbing portion 38 and the torsional load resistance of the second energy absorbing portion 50, and the load value of the force limiter load is set to a high load. On the other hand, when the rotation of the locking member is permitted, the force limiter load is set to the torsional load resistance of the first energy absorbing portion 38, and the load value of the force limiter load is set to a low load.

[0055] 6, 12 and 13, in this embodiment, when the sub torsion shaft 44 to which the clutch 52 is attached is assembled to the spool 20, the end face on the pull-out direction side of one locking piece portion 88D of the clutch cover 88 is engaged with the tip portion 40B of the trigger wire 40. This restricts the rotation of the sub torsion shaft 44, which is rotatable integrally with the sub torsion shaft 44, in the pull-out direction. This maintains the assembled state of the sub torsion shaft 44 in the spool 20. In this way, in this embodiment, it is possible to eliminate the need for a stopper member for restricting the rotation of the sub torsion shaft 44 assembled to the spool 20 in the pull-out direction relative to the spool 20.

[0056] Furthermore, in this embodiment, the clutch cover 88 having the locking pieces 88D can be easily formed by performing a press work or the like on a metal plate.

[0057] Further, in this embodiment, as shown in Figs. 9, 10, 12 and 13, recesses 88F and 88G, each of which is open on the outer side in the rotational radial direction, are formed on both sides of the locking piece portion 88D in the rotational circumferential direction of the clutch cover 88. Here, the circumferential distance between the locking piece portion 88D and the sector-shaped portion 88B constituting both edges in the circumferential direction of one recess 88F is set to be larger than the outer diameter of the tip of the trigger wire 40 (see Fig. 1). Also, the circumferential distance between the locking piece portion 88D and the locking claw portion support plate portion 88C constituting both edges in the circumferential direction of the other recess 88G is set to be smaller than the outer diameter of the tip of the trigger wire 40 (see Fig. 1). Therefore, the locking piece portion 88D is locked to the tip of the trigger wire 40 in a state in which the trigger wire 40 can be placed in one recess 88F. Also, the tip 40B of the trigger wire 40 cannot be placed in the other recess 88G. This makes it possible to prevent the locking piece 88D from being locked to the tip end 40B of the trigger wire 40 when the tip end 40B of the trigger wire 40 is disposed in the other recess 88G. In other words, it is possible to prevent erroneous assembly during manufacture of the webbing take-up device 10.

[0058] In this embodiment, as shown in Figures 9, 10 and 11, the circumferential width W1 of the base end 88D1 gradually increases from the boundary 88E between the inclined portion 88D2 and the base end 88D1 toward the opposite side of the inclined portion 88D2. The circumferential width W2 of the inclined portion 88D2 gradually increases from the boundary 88E between the inclined portion 88D2 and the base end 88D1 toward the opposite side of the base end 88D1. With this configuration, it is possible to ensure the durability of the base end 88D1 against a load in the circumferential direction, and to improve the press workability when punching out the outer shape of the clutch cover 88.

[0059] In the above-described embodiment, an example has been described in which the tip 40B of the trigger wire 40 cannot be placed in the other recess 88G, thereby preventing erroneous assembly during the manufacture of the webbing take-up device 10, but the present invention is not limited to this. For example, erroneous assembly during the manufacture of the webbing take-up device 10 may be prevented by employing a clutch cover 88 configured in such a way that the other recess 88G is not formed.

[0060] In the present embodiment, the clutch cover 88 is formed by pressing a metal plate, but the present invention is not limited to this. The material for forming the clutch cover 88 may be appropriately selected in consideration of the strength required for the clutch cover 88, etc.

[0061] Furthermore, in the present embodiment, an example has been described in which a stopper member for limiting rotation of the sub torsion shaft 44 in the pull-out direction relative to the spool 20 is eliminated by engaging a part of the clutch cover 88 (locking piece portion 88D) with the tip portion 40B of the trigger wire 40, but the present invention is not limited to this. For example, a stopper member for limiting rotation of the sub torsion shaft 44 in the pull-out direction relative to the spool 20 may be eliminated by engaging a part of another member (e.g., the sleeve 54 or the clutch base 82) engaged with the sub torsion shaft 44 so as not to rotate relative to it with the tip portion 40B of the trigger wire 40.

[0062] (Configuration for making it easier to screw the screw into the sub-torsion shaft) Next, a configuration for facilitating screwing of the screw 108 into the sub torsion shaft 44 will be described with reference to Fig. 14. Note that, among the members and parts shown in Fig. 14, the members and parts corresponding to those of the webbing take-up device 10 described above are denoted by the same reference numerals as those of the webbing take-up device 10 described above, and descriptions thereof may be omitted.

[0063] 14, the main torsion shaft 32 is provided with a cylindrical shaft portion 33 that protrudes from the axis of the second engagement portion 36 toward the sub torsion shaft 44. When the main torsion shaft 32 is faced downward, the first engagement portion 46 side of the sub torsion shaft 44 abuts against the shaft portion 33. This limits downward displacement of the sub torsion shaft 44 relative to the sleeve 54, and ensures an engagement allowance between the threaded portion 110 of the screw 108 and the screw hole 45 of the sub torsion shaft 44. As a result, the screw 108 can be easily screwed into the sub torsion shaft 44.

[0064] Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and it is of course possible to implement the present invention in various other modified forms without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0065] 10 Webbing take-up device 20 spools 22 Webbing 40 Trigger wire (trigger member) 44 Sub-torsion shaft (torsion shaft) 52 Clutch 54 Sleeve 64 Clutch guide 88 Clutch cover 88D Locking piece 88F Depression 88G Depression 100 clutch plate

Claims

1. a spool around which a webbing to be worn by an occupant is wound and which rotates in a pull-out direction as the webbing is pulled out; a trigger member provided on the spool; a torsion shaft that is engaged with the spool and that is twisted to allow rotation of the spool in the pull-out direction; a clutch in which the torsion shaft is engaged and the trigger member is engaged, a part of a member engaged with the torsion shaft so as not to rotate relatively to the torsion shaft is locked by the trigger member, thereby restricting the rotation of the torsion shaft relative to the spool, and which is actuated and engaged with a locking member by actuating and disengaging the trigger member, thereby restricting the rotation of the torsion shaft relative to the locking member; A webbing take-up device comprising:

2. The clutch is a clutch guide supported in a state capable of rotating relative to the torsion shaft and the rotation of which is restricted by engagement of the trigger member; a clutch cover fixed to the torsion shaft in a state in which the clutch cover cannot rotate relative to the torsion shaft; a clutch plate provided between the clutch guide and the clutch cover, the clutch plate being displaced and engaged with the lock member when the clutch guide rotates relative to the sleeve; The present invention relates to a method for manufacturing a computer-implemented ... The webbing take-up device according to claim 1, wherein a portion of the clutch cover is engaged with the trigger member, thereby restricting rotation of the torsion shaft relative to the spool.

3. The webbing take-up device according to claim 2, wherein a portion of the clutch cover extends toward the trigger member and serves as a locking piece that is locked to the trigger member.

4. In the clutch cover, recesses are formed on both sides in the rotational circumferential direction of the locking piece portion, the recesses being open radially outward, The locking piece is locked to the trigger member in a state in which the trigger member can be placed in one of the recesses, The webbing take-up device according to claim 3 , wherein the trigger member cannot be positioned in the other of the recesses.

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