JPH10226313A - Webbing winding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a webbing winding device whereby at sudden deceleration time, a spool, after it is once rotated in a webbing winding direction by a pretensioner, can be rotated in a webbing draw out direction, by an energy absorbing means, tensile force applied to a webbing is prevented from increasing to a prescribed value or more. SOLUTION: In this webbing winding device, a shaft part 26 for pretension in one end side of a spool 18 is arranged with a prescribed space apart in the inside of a drum 64, at rapid deceleration time, the drum 64 is wind fastened by a wire 94, to bite in the shaft part 26 for pretension, the spool 18 is rotated in a winding direction of a webbing 20. Next, draw out force acting in the webbing 20 acts in the drum 64, a breaking part of an engaging piece 76 is broken. The pretension shaft part 26 can be relatively rotated relating to a drive plate 80, the spool 18 is rotated, a torsion bar 24 is twist deformed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a webbing take-up device provided with a pretensioner for tensioning a webbing at the time of rapid deceleration of a vehicle and a force limiter for preventing a webbing from being subjected to a pulling force exceeding a predetermined value.

[0002]

2. Description of the Related Art A webbing take-up device mounted on a vehicle is provided with a pretensioner that takes up and tensions the webbing when a large deceleration greater than a predetermined value is applied to the vehicle, and restrains the wearer without loosening. (See JP-A-4-92748). FIG. 12 shows a webbing retractor 30 having such a pretensioner.
0 is shown.

In the webbing take-up device 300, a cylindrical spool 306 on which a webbing 304 is wound is rotatably supported on a frame 302.

[0004] A pretensioning shaft portion 308 integrally provided at one end of a spool 306 is provided with a drum 310.
Has been inserted into the play. The drum 310 is formed into a substantially cylindrical shape as a whole by connecting a substantially semicircular holding portion 312 with a connection portion 314 curved in a substantially S-shape. Drum 31
An intermediate portion of a wire 318 whose one end is connected to the drive plate 316 is wound around the outer periphery of the zero. An insertion hole 320 into which the drum 310 is inserted is formed at the center of the drive plate 316. The engaging portion 322 protruding from the drum 310 is housed in the enlarged diameter portion 320A formed in the insertion hole 320, and rotates integrally with the drum 310.

The other end of the wire 318 is connected to the cylinder 3
24 is connected to a piston (not shown). This piston, when the deceleration more than the predetermined value acts on the vehicle,
The gas generator operates and is rapidly drawn into the cylinder.

A lock portion (not shown) is provided at the other end of the spool 306. When a deceleration equal to or more than a predetermined value is detected, the lock portion locks the rotation of the spool 306 in the pulling-out direction of the webbing 304, and Rotation is allowed only in the 304 winding direction.

Accordingly, when a deceleration of a predetermined value or more acts on the vehicle body, the wire 318 is pulled, so that the drum 31
0 is wound around the wire 318, the connecting portion 314 is deformed, and the holding portion 312 approaches. The holding portion 312 holds the pretension shaft portion 308, and the drum 310 is integrated with the spool 306. When the wire 318 is further pulled, the spool 306 is rotated by this pulling force, and the webbing 304 is pulled.

On the other hand, there has been proposed a webbing winding device provided with a force limiter for preventing a tensile force applied to the webbing from exceeding a predetermined value.

A webbing take-up device equipped with a so-called torsion bar type force limiter (Japanese Patent Laid-Open No.
No. 47923), in a cylindrical spool,
A cylindrical torsion bar which can be torsionally deformed in the circumferential direction is inserted coaxially with the spool, and one end of the torsion bar is fixed to the spool. During rapid deceleration of the vehicle, the other end of the torsion bar is locked by the lock mechanism. Since one end of the torsion bar is fixed to the spool, when the pulling force acts on the webbing in the pull-out direction when the vehicle is suddenly decelerated, the torsion bar is twisted to rotate the spool, and the tensile load applied to the webbing is reduced to a predetermined value. I try not to be more.

In the webbing take-up device 300, the drum 310 is wound around the wire 318 at the time of rapid deceleration of the vehicle, the holding portion 312 holds the pretensioning shaft portion 308, and the drum 310 rotates together with the spool 306. Therefore, when the wire 318 is pulled out to the maximum, the spool 306 cannot be further rotated in the webbing 304 pulling-out direction due to the tension of the wire 318. Therefore, if the above-described force limiter is simply attached to the webbing take-up device 300, the torsion bar cannot be sufficiently twisted.

[0011]

In view of the above fact, the present invention makes it possible to rotate the spool in the webbing take-out direction after the spool is once rotated by the pretensioner at the time of rapid deceleration, and to make the spool rotatable in the webbing pull-out direction. It is an object of the present invention to obtain a webbing take-up device that prevents a pulling force applied to a webbing from exceeding a predetermined value.

[0012]

According to the first aspect of the present invention, the spool on which the webbing is wound is deformed by the spool when a rotational force in the webbing pull-out direction acts on the spool during rapid deceleration of the vehicle. An energy absorbing member for preventing an increase in webbing tension, a pretensioner for connecting to the spool and rotating in the webbing winding direction when a deceleration of a predetermined value or more acts, and an energy absorbing member deformed by a rotational force in the webbing unwinding direction. And a release unit for receiving the rotational force in the webbing pull-out direction in the case where the rotation has been performed, and releasing the rotation prevention in the webbing pull-out direction by the pretensioner.

In a normal running state of the vehicle in which the deceleration equal to or more than the predetermined value is not applied, the pretensioner does not restrain the spool.

When the deceleration exceeds a predetermined value, the pretensioner and the spool are connected, and the webbing is wound around the spool, so that the webbing restrains the wearer without loosening.

Next, when the webbing is pulled in the pull-out direction, the pulling force is transmitted from the spool to the energy absorbing member. Due to the energy absorbing action such as the deformation of the energy absorbing member, the action of the force limiter for preventing the mounting force on the webbing wearer from exceeding a predetermined value is started. When the webbing is further pulled against this, the pulling force acts on the release portion. When the pulling force exceeds a predetermined value, the release unit enables the spool to rotate relative to the pretensioner. Therefore, in this state, the energy absorption further continues, the operation of the force limiter is continued, and the mounting force of the webbing to the wearer does not exceed a predetermined value.

The release section may be any release section that allows the spool to rotate relative to the pretensioner, such as a plastically deformable member, an elastically deformable member, a breakable member, a clutch, and a friction plate. Etc.

According to a second aspect of the present invention, the release portion is a break portion that separates the spool and the pretensioner by breaking.

Since the breaking portion is broken and the spool is separated from the pretensioner, the spool can freely rotate with respect to the pretensioner.

[0019]

1 to 3 show a webbing winding device 10 according to an embodiment of the present invention.

The webbing take-up device 10 has a frame 12 mounted on a vehicle (not shown). A pair of support plates 14 and 16 are arranged on the frame 12 in parallel. Between the support plates 14 and 16, there is provided a spool 18 which is formed into a substantially cylindrical shape and has flanges projecting from both ends in the axial direction in the radial direction. This spool 1
8, one end of a webbing 20 is fixed, and the webbing 20 is wound up.
FIG. 3 shows a state in which the webbing 20 is wound around the spool 18 in this manner. FIG. 3 shows a state in which the webbing 20 is pulled out from the spool 18.

Inside the spool 18, a torsion portion 22 is arranged coaxially with the center axis of the spool 18. The torsion portion 22 has a substantially columnar torsion bar 24 that is slightly longer than the axial length of the spool 18. The torsion bar 24 is made of a plastically deformable material such as a metal, and is plastically deformed and twisted when a torsional force of a predetermined value or more acts in the circumferential direction.

At one end of the torsion bar 24, a hexagonal columnar insertion portion 24A is formed. The insertion portion 24A
The torsion bar 24 and the pretension shaft portion 26 are integrally inserted into a hexagonal insertion hole 34 formed in the pretension shaft portion 26 constituting the torsion portion 22.

This pretension shaft portion 26
A holding portion 28 having a substantially cylindrical shape, and a cylindrical gear portion 30 having a smaller diameter than the holding portion 28 and integrally formed coaxially with the holding portion 28 (see FIGS. 2 and 3). doing. A plurality of projections 32 (see FIG. 1) having the same direction as the central axis direction of the torsion bar 24 and having a sharply pointed tip project on the outer periphery of the held portion 28 at predetermined intervals in the circumferential direction. A holding portion 66 of a drum 64, which will be described later,
When the clamp 68 clamps the clamped portion 28, it bites into the inner surface of the drum 64 to prevent the drum 64 from running idle.

A gear 36 is formed on the outer periphery of the gear portion 30. The gear 36 meshes with a gear 38 formed on the inner periphery of the spool 18, so that the spool 18 and the pretensioning shaft portion 26 are integrated. Rotate with. Accordingly, the torsion bar 24 rotates integrally with the spool 18 via the pretensioning shaft portion 26 at one end thereof.

On the other end side of the torsion bar 24 (the upper left side in FIG. 1, the right side in FIGS. 2 and 3), a locking shaft section 40 constituting the torsion section 22 is arranged. The lock shaft portion 40 is formed in a substantially cylindrical shape, a hexagonal insertion hole 44 is formed in the axial direction from one end side, and a cylindrical portion 42 having an external thread 46 cut on the outer periphery. It is formed on the other end side, closes the insertion hole 44 and
, And a locked piece 50 protruding bifurcated from the circular plate 48.
A hexagonal columnar insertion portion 24B formed at the other end of the torsion bar 24 is inserted into the insertion hole 44, and the torsion bar 24 and the lock shaft portion 40 rotate integrally. FIG. 1 shows a state in which the insertion portion 24B is inserted into the insertion hole 44.

With the insertion portion 24B of the torsion bar 24 inserted into the insertion hole 44 in this manner, the spool 18 is disposed between the support plates 14 and 16, and the pretension shaft portion is positioned from the support plate 14 side. 26 is engaged with the gear 38 of the spool 18, and the torsion bar 24 integrated with the locking shaft 40 is inserted into the spool 18 from the support plate 16 side, as shown in FIGS. As shown, the torsion bar 24 is
8 is disposed coaxially with the spool 18. At this time,
The cylindrical portion 42 side of the outer peripheral surface of the disk 48 from the substantially central portion in the axial direction abuts on the inner peripheral surface of the spool 18, and the torsion portion 22 is moved in a state where the central axis of the spool 18 and the central axis of the torsion bar 24 match. Positioned. Further, the locked piece 50 side of the outer peripheral surface of the disk 48 from substantially the center in the axial direction is rotatably supported by the support plate 16 of the frame 12 via the ring 52. The pretension shaft portion 26
A portion of the gear portion 30 where the gear 36 is not formed is rotatably supported by a cover drum 58 described later. Thereby, the spool 18 is rotatably supported by the frame 12.

The male screw 46 of the cylindrical portion 42 is formed into a substantially annular shape, a part of which is cut in the circumferential direction, and is screwed with a ring-shaped ring 54 having a female screw cut inside. With the torsion portion 22 disposed inside the spool 18,
The circumferential end face 54A of the ring-break ring 54 is
Abuts on a ridge 56 (see FIGS. 2 and 3) protruding from the inner periphery of the spool 18 along the axial direction of the spool 18. In a normal state, the ring-opening ring 54 is located at one end of the male screw 46 (the pretensioning shaft 26 side, the position shown in FIG. 2), but when the spool 18 rotates relatively to the locking shaft 40. The ring ring 54 also rotates with the spool 18 and moves to the other end (the disk 48 side, the position shown in FIG. 3). This movement is stopped when the ring-opening ring 54 comes into contact with the disk 48, and the rotation of the spool 18 with respect to the locking shaft 40 is also stopped.

An inertia lock mechanism (not shown) is provided outside the support plate 16 (on the side opposite to the side on which the spool 18 is provided, on the right side in FIGS. 2 and 3). This inertial lock mechanism is used to rotate the torsion portion 22 in the direction in which the webbing 20 is pulled out when a deceleration of a predetermined value or more acts on the vehicle to which the webbing take-up device 10 is attached or when the webbing 20 is pulled out rapidly. Is locked, but the locked piece 50 is not locked in the webbing 20 winding direction.

On the other hand, outside the support plate 14 (the left side in FIGS. 2 and 3), a cover drum having storage portions 60 and 62 whose diameters are increased stepwise from the rotation axis of the torsion bar 24 toward the outside in the radial direction. 58 is fixed. A drum 64 around which a wire 94 to be described later is wound is accommodated in the accommodation portion 60 having a smaller diameter (the side closer to the support plate 14).
4 and are arranged coaxially. The drum 64 is formed of a metal (for example, aluminum or the like) that is softer than the lock shaft portion 40 and the pretension shaft portion 26. Further, as shown in detail in FIG. 4, the drum 64 is arranged such that the substantially semi-annular holding portions 66 and 68 face each other to form a substantially cylindrical shape.
Corresponding portions at both ends in the circumferential direction of 6 and 68 are
6 and 68 are connected by a substantially S-shaped compression part 70 integrally formed. Usually, as shown in FIG.
In a state where the drum 64 is disposed in the storage portion 60 (see FIGS. 2 and 3), the inner surfaces of the holding portions 66 and 68 and the held portion 28
There is a predetermined slight gap with the tip of the projection 32 of
Although the drum 64 is separated from the pretensioning shaft portion 26 in the housing portion 60, a force in a direction approaching each other acts on the sandwiching portions 66, 68 to compress and deform the compression portion 70 (see FIG. 4). As shown in FIG. 6A, the holding portions 66, 68
Are closer to each other, the holding portions 66 and 68
8 is pinched. Since the drum 64 is formed of a metal softer than the pretensioning shaft portion 26, the projections 32 bite into the inner surfaces of the holding portions 66 and 68. For this reason, the drum 64 and the pretension shaft 26 rotate integrally.

At one end of the holding portions 66 and 68, the outer peripheral surface is cut radially inward to form a reduced diameter portion 72, and the surface between the portion not reduced in diameter and the reduced diameter portion 72 is formed. The positioning step 74 is provided. An engagement piece 76 protrudes radially outward from a substantially central portion in the circumferential direction of the reduced diameter portion 72. The engaging piece 76 includes a narrow breaking portion 76A on the side of the holding portions 66 and 68, and a wide engaging portion 76B formed on the distal end side of the breaking portion 76A. The engagement portion 76B is thicker and reinforced toward one axial end of the drum 64 than the break portion 76A. Engaging portion 76
When a force greater than or equal to a predetermined value in the circumferential direction of the drum 64 is applied to B, the breaking portion 76A is broken, and the engaging portion 76B
Separate from 4.

A flange 78 projecting outward is formed on the other end side of the holding portions 66, 68, and the holding portions 66, 68 are reinforced.

A substantially disk-shaped drive plate 80 is disposed outside the cover drum 58 (opposite to the support plate 14, left side in FIGS. 2 and 3). Surrounding three places, it is rotatable coaxially with the torsion bar 24. FIG.
As shown in (A), a substantially circular insertion hole 82 into which the reduced diameter portion 72 of the drum 64 is inserted is formed in the center of the drive plate 80, and when the reduced diameter portion 72 is inserted,
The positioning step 74 of the drum 64 is
, The drum 64 is positioned in the axial direction. The insertion hole 82 has an enlarged diameter portion 82A into which the engagement piece 76 is inserted, and the engagement piece 7 inserted into the enlarged diameter portion 82A is formed.
6, the drive plate 80 and the drum 64 rotate integrally.

The drive plate 80 has a fixing portion 84 into which a tubular body attached to one end of the wire 94 is fitted and fixed. The wire 94 having one end fixed to the fixing portion 84 is wound around the drum 64 a plurality of times (almost twice in this embodiment), and the other end is connected to a piston 88 in a cylinder 86 provided on the frame 12. (FIG. 5
(A) and is fixed to the outside of the cylinder 86. When a sensor (not shown) detects that a deceleration of a predetermined value or more has acted on the vehicle to which the webbing take-up device 10 is attached, a gas generator (not shown) in the base cartridge 90 provided on the frame 12 operates. 6 (B), FIG. 7 (B) and FIG.
As shown in (B), the piston 88 is quickly moved to the cylinder 86.
To the back of. Due to the movement of the piston 88, the wire 94 is rapidly pulled in, and a rotational force is applied to the drive plate 80.

As shown in FIGS. 1 and 5A, a shear pin 92 is projected from the frame 12 so as to penetrate through the cover drum 58. The shear pin 92 is formed in a recess formed in the drive plate 80. Normally, the drive plate 80 does not rotate in the webbing 20 winding direction (the direction of the arrow A in FIG. 5A) because the wire 94 is engaged with the webbing 20. When a rotation force equal to or greater than a predetermined value acts on the drive pin 80, the shear pin 92 is pushed by the recess 101 and is broken, so that the drive plate 80 rotates.

Outside the drive plate 80, a substantially annular stopper plate 96 is arranged. The stopper plate 96 is supported by a positioning member (not shown) so as to be coaxial with the torsion bar and rotatable about the central axis J of the torsion bar 24. (Note that
2 and 3, the stopper plate 96 and a cover plate 102 described later are omitted for convenience of illustration. A moving projection 98 is formed from the stopper plate 96 and extends outward in the radial direction and has a distal end portion bent at a substantially right angle toward the drive plate 80 side. The tip of the moving projection 98 is
Are positioned in a long groove 100 that is hollowed out in a substantially circular arc shape along the circumferential direction, and the movable protrusion 98 is moved by the relative rotation between the stopper plate 96 and the drive plate 80.
Move within 00. The central angle of the long groove 100 is set to about 90 °, and the stopper plate 96 and the drive plate 80 rotate relative to each other by about 90 °.

Further outside the stopper plate 96,
The cover plate 102 is disposed and the cover drum 58
It is fixed to. The cover plate 102 maintains the state in which the drum 64, the drive plate 80, and the stopper plate 96 are housed in the housing portions 60 and 62 of the cover drum 58.

A stopper projection 104 projects from the cover plate 102 toward the stopper plate 96. The stopper projection 104 has a length that abuts the moving projection 98 but does not enter the long groove 100. As shown in FIG. 5A, the webbing take-up device 10
When the deceleration of a predetermined value or more is not acting on the stopper projection 104, the moving projection 98 of the stopper plate 96 is located on the lower right side of the paper of the stopper projection 104 (on the webbing 20 winding direction side),
Further, an end wall 100A of the long groove 100 of the drive plate 80 is located on the lower right side of the drawing.

When the wire 94 is pulled into the cylinder 86 and the drive plate 80 rotates in the webbing winding direction (the direction of arrow A in FIG. 5A), the long groove 100 is formed.
Is moved, and the moving protrusion 98 is moved
Hit B. When the drive plate 80 is further rotated, as shown in FIG.
The moving projection 98 is pushed by 0B, and the stopper plate 96 rotates together with the drive plate 80. Further, the drive plate 80 rotates to the state shown in FIG.
The wire 94 is drawn into the cylinder 86 by the piston 88, and the piston 88 bottoms out in the cylinder 86,
When the wire 94 has been pulled in, the drive plate 80
Stops rotating.

As described above, the drive plate 80 rotates about 90 ° with the stopper plate 96 stopped at the initial stage of rotation, and then rotates about 360 ° together with the stopper plate 96, so that the drive plate 80 rotates about 450 ° from the start of rotation to the end of rotation. ° rotate. The rotation amount of the drive plate 80 can be changed by changing the length of the long groove 100, thereby changing the rotation amount of the relative rotation between the drive plate 80 and the stopper plate 96. During the rotation of the drive plate 80, the moving projection 98 may be located at any position in the long groove 100, and the drive plate 80 may be rotated by about 450 ° from the start of rotation to the end of rotation.

Next, the operation and operation of the webbing retractor 10 according to the present embodiment will be described.

In a normal state, that is, when the deceleration of the vehicle to which the webbing take-up device 10 is attached is less than a predetermined value, the inertia locking mechanism (not shown) uses the locked piece 5.
0 is not locked. Since the gas generator in the base cartridge 90 is not operating, the wire 94 is not drawn into the cylinder 86. Therefore, the spool 18 (see FIGS. 1 to 3) freely rotates, and the webbing 20 can be pulled out and taken up.

When a deceleration exceeding a predetermined value acts on the vehicle,
The inertia lock mechanism pulls out the webbing 20 (FIG. 5A).
In order to lock the rotation of the locked piece 50 in the direction of arrow B), the spool 18 that rotates together with the torsion portion 22 also
The rotation of the webbing 20 in the pulling-out direction is locked, and the webbing 20 cannot be further pulled out.

Further, the gas generator operates, and FIG.
As shown in (B), in order to move the piston 88 toward the inner side of the cylinder 86, the wire 94
It is quickly drawn into 6. Here, since the rotation of the drive plate 80 is stopped by the shear pin 92, the drum 64 also does not rotate. For this reason, the drum 64 around which the wire 94 is wound is sharply wound by the wire, and the compressing portion 70 (see FIG. 4) is compressed and deformed, and as shown in FIG. Approach each other and clamp the clamped portion 28 of the pretensioning shaft portion 26. Since the drum 64 is formed of a metal softer than the clamped portion 28, the protrusion 32 of the clamped portion 28
Bites into the inner surfaces of the holding portions 66 and 68, and the drum 64 and the pretension shaft portion 26 are integrated.

When the wire 94 is further drawn into the cylinder 86, a rotational force acts on the drive plate 80,
The recess 101 presses the shear pin 92 to break it. Thus, as shown in FIG. 7A, the drive plate 80 is moved in the webbing winding direction (the direction of arrow A in FIG. 7A).
To rotate. Since the engaging piece 76 of the drum 64 is inserted into the enlarged diameter portion 82A of the insertion hole 82 of the drive plate 80, the drum 64 rotates together with the drive plate 80. A gear 36 formed on the gear portion 30 of the pretensioning shaft portion 26 is engaged with a gear 38 on the inner periphery of the spool 18, and an inertial lock mechanism (not shown) is provided with a webbing 20 of the locking shaft portion 40. Since the rotation in the take-up direction is not locked, the rotation of the drum 64 causes the spool 18 to rotate in the take-up direction of the webbing 20 (the direction of arrow A in FIG. 7A) via the pretensioning shaft portion 26. As shown in FIG. 8B, when the piston 88 moves to the back in the cylinder 86 and the wire 94 is most drawn into the cylinder 86, as shown in FIG. By rotating about 450 ° from the initial state, the webbing 20 is tense most. Thereby, the webbing 20 is attached to the wearer of the webbing 20 without slack.

Next, when a withdrawal force equal to or more than a predetermined value acts on the webbing 20 due to the inertia force of the wearer of the webbing 20, this force is applied to the spool 18 in the webbing 20 withdrawal direction (the direction of arrow B in FIG. 8A). Acts as a turning force.
Here, since the inertial lock mechanism (not shown) locks the rotation of the lock shaft 40 in the direction in which the webbing 20 is pulled out, the insertion portion 24B at the other end is inserted into the insertion hole 44 of the lock shaft 40. Torsion bar 24
Is also locked at the other end. On the other hand, the insertion portion 24A at one end of the torsion bar 24 is inserted into the pretension shaft portion 26, and the pretension shaft portion 26 rotates integrally with the spool 18 by engagement of the gears 36 and 38. I do. The rotational force of the spool 18 is transmitted to the torsion bar 24 via the pretensioning shaft portion 26, and the torsion bar 24 starts to be plastically deformed and twisted, so that a tensile force exceeding a predetermined value does not act on the webbing 20. Start limiter action. At this time, when the spool 18 rotates with respect to the locking shaft 40, the end surface 54A
Is pressed by the ridge 56 to rotate the ring-open ring 54, and the disk 4
Start moving towards 8.

The drum 64 that has been cut by the pinched portion 28 of the pretensioning shaft portion 26 is also
Since the drive plate 80 rotates in the pull-out direction (the arrow B direction in FIG. 9A), the drive plate 80 also rotates in the pull-out direction of the webbing 20, and the wire 94 is pulled in the cylinder 86.
(B) The piston 88 moves inside the cylinder 86 to the left in FIG.

At this time, since the drive plate 80 relatively rotates with respect to the stopper plate 96, the rotation of the drive plate 80 causes the one end wall 100A of the long groove 100 to rotate.
Corresponds to the moving projection 98. Thereafter, the moving protrusion 98 is pushed by the one end wall 100A of the long groove 100, and the stopper plate 96 rotates integrally with the drive plate 80.

As shown in FIG. 10A, when the drive plate 80 is rotated to almost the initial state (the same state as the state shown in FIG. 5A), the movable projection 98
04, the rotation of the drive plate 80 is stopped. In this state, the webbing 2 is further attached to the spool 18.
When a rotational force is applied in the zero withdrawal direction (the direction of arrow B in FIG. 10A), the drum 64 tries to rotate in the withdrawal direction of the webbing 20, so that the rotation of the drive plate 8 is prevented.
A rotational force acts on the engagement piece 76 housed in the 0-diameter enlarged portion 82A, and the breaking portion 76A (see FIG. 4) is broken. As a result, the pretensioning shaft portion 26 is separated from the drive plate 80 and becomes rotatable relative to the drive plate 80, so that the torsion bar 24 is further twisted and the operation of the force limiter is continued, and the spool 18 Rotates in the webbing 20 pull-out direction. And
Until the rotational force acting on the pretensioning shaft portion 26 via the spool 18 by pulling out the webbing 20 and the torsional reaction force of the torsion bar 24 are balanced.
The torsion bar 24 is torsionally deformed.

As shown in FIG. 11A, the holding portions 7 correspond to the rotation angle of the torsion bar 24 due to the torsional deformation.
6. Pretension shaft section 26 and spool 18
The webbing 20 is also pulled out by rotation (see FIGS. 1 to 3), and acts as a force limiter to prevent the tensile load applied to the webbing 20 from exceeding a predetermined value.

When the rotational force acting on the spool 18 is large, the ring-shaped ring 54 moved toward the disk 48 hits the disk 48 (see FIG. 3), and the ring-shaped ring 54 moves further. No longer. Thereby, the spool 18
Is also stopped, so that excessive torsional deformation of the torsion bar 24 is prevented, and the torsion bar 24 is prevented from being twisted. In addition, since the rotation of the spool 18 can be stopped by rotating the ring-shaped ring 54 and hitting the disk 48 in this manner, by adjusting the initial position of the ring-shaped ring 54, the rotation of the spool The relative rotation amount of the spool 18 can be changed. Thereby, the amount of torsion of the torsion bar 24 can be adjusted, and the amount of withdrawal of the webbing 20 when the force limiter operates can be adjusted.

As described above, in the webbing take-up device 10 according to the present embodiment, when the rotating force in the webbing 20 pulling-out direction acts on the spool 18 after the drum 64 sandwiches the pretension shaft portion 26, the drum 64 The breaking portion 76A is broken and the pretensioning shaft portion 26
Can be relatively rotated with respect to the drive plate 80 of the pretensioner, so that the torsion bar 24 can be sufficiently twisted and deformed to act as a force limiter.

It should be noted that, as the release portion, the above-described break portion 7 is used.
6A, webbing with pretensioner 2
The pretensioner and the spool 18 are integrated with each other when the load is in the pull-out direction, and the spool 18 can be rotated relative to the pretensioner with the load in the pull-out direction. sell.
For example, instead of the breaking portion 76A, a deforming portion that undergoes plastic deformation or elastic deformation is formed, and the deforming portion is deformed by the shearing force or bending force applied to the engaging piece 76, and the webbing 20 is pulled out by the pretensioner. May be released so that the pretensioning shaft portion 26 is rotatable relative to the drive plate 80 of the pretensioner. Also, instead of the engagement piece 76,
Outer circumference of drum 64 and insertion hole 82 of drive plate 80
A gear that engages with each other may be formed on the inner periphery of the shaft, and the gear may be crushed so that the pretensioning shaft portion 26 can be relatively rotated with respect to the drive plate 80. Further, a clutch, a friction plate or the like may be used.

The energy absorbing member is not limited to the above-mentioned torsion bar 24, but may be deformed by the rotation of the spool 18 in the direction in which the webbing 20 is pulled out, or may move by causing a viscous fluid that has caused friction to flow. Any material that absorbs energy and prevents an increase in the tension of the webbing 20 may be used. For example, the webbing 20 may be moved in the axial direction of the spool 18 by the rotation of the spool 18, and the movement may receive resistance due to deformation, friction, or the like, thereby preventing the tension of the webbing 20 from increasing. In addition, these energy absorbing members
It does not have to be coaxial with the spool 18.

Further, in the above description, when the deceleration equal to or more than the predetermined value is detected, the spool
Although a lock portion that locks the rotation of the spool 18 and allows rotation only in the winding direction of the webbing 20 is provided at the other end of the spool 18, this lock portion is not necessarily required. Webbing 2
After the 0 is mounted, the rotation of the spool 18 in the pulling-out direction may be locked, and the rotation of the webbing 20 may be allowed only in the winding direction. Further, if the rotation of the spool 18 can be locked, it is not necessary to be provided at the other end of the spool 18 and it is sufficient that the spool 18 is attached to the spool 18 via an energy absorbing member.

In addition, in the above description, the torsion bar 2
4 rotates with the spool via a pretension shaft portion 26 attached to one end of the spool 18, but the torsion bar 24, the spool 18
The connection structure of the pretension shaft portion 26 is not limited to this, and the pretension shaft portion 26 or the pretensioner is connected to the spool 18, and the torsion bar 24 is attached to the spool 18 separately from this. Just do it. For example, the torsion bar 24 may be attached to the other end of the spool 18 and rotate together with the spool 18.

[0056]

According to the present invention, since the spool is once rotated in the webbing winding direction during sudden deceleration,
The spool can be rotated in the webbing pull-out direction, and the torsion bar can be sufficiently torsionally deformed so that the pulling force applied to the webbing does not exceed a predetermined value.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a webbing retractor according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a cross-sectional view showing a state where the webbing is pulled out from the state shown in FIG. 2;

FIG. 4 is a perspective view of a drum of the webbing take-up device according to the embodiment of the present invention.

FIG. 5A is a side view of a main part of a webbing take-up device according to one embodiment of the present invention, and FIG. 5B is a side view of a cylinder of the webbing take-up device according to one embodiment of the present invention. It is sectional drawing.

FIG. 6A is a side view of a main part in a state where the drum has bitten into a pretensioning shaft part from FIG. 5A, and FIG. 6B is a sectional view of a cylinder at this time.

7 (A) is a side view of a main part in a state where the drive plate has been rotated in the webbing winding direction from FIG. 6 (A), and FIG. 7 (B) is a sectional view of the cylinder at this time.

8A is a side view of a main part in a state where the drive plate has been rotated in the webbing winding direction from FIG. 7A, and FIG. 8B is a cross-sectional view of the cylinder at this time.

9A is a side view of a main part in a state where the drive plate has been rotated in the webbing pull-out direction from FIG. 8A, and FIG. 9B is a cross-sectional view of the cylinder at this time.

10A is a side view of a main part in a state where the drive plate has been rotated in the webbing withdrawing direction from FIG. 9A and the broken part of the engagement piece has been broken, and FIG. It is sectional drawing of the cylinder of FIG.

FIG. 11A is a side view of a main part in a state where the holding portion of the drum and the pretensioning shaft portion have been rotated in the webbing withdrawing direction from FIG. (B) is a sectional view of the cylinder at this time.

FIG. 12 is an exploded perspective view of a conventional webbing winding device.

[Explanation of symbols]

 Reference Signs List 10 webbing take-up device 18 spool 22 torsion part 24 torsion bar (energy absorbing member) 26 pretension shaft part 40 locking shaft part 64 drum 76A breaking part (release part) 80 drive plate (pretensioner) 86 cylinder (pretensioner) ) 88 piston (pretensioner) 94 wire (pretensioner)

Claims (2)

[Claims] 1. A spool on which webbing is wound, an energy absorbing member which is deformed by the spool to prevent an increase in webbing tension when a rotational force in the webbing pull-out direction acts on the spool during rapid deceleration of a vehicle, and a predetermined value or more. A pretensioner that is connected to the spool when the deceleration is applied and rotates in the webbing take-up direction; and receives a rotational force in the webbing take-out direction when the energy absorbing member is deformed by the rotational force in the webbing take-out direction. A release unit for releasing the rotation of the pretensioner from rotating in the webbing withdrawing direction. 2. The webbing retractor according to claim 1, wherein the release portion is a break portion that separates the spool and the pretensioner by breaking.