JP2001260812A - Webbing take-up device and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a webbing take-up device capable of reducing a force- limiter load with a simple structure in a process to absorb energy by allowing withdrawal of a webbing, and a vehicle using it. SOLUTION: A spool 14 is linked to a lockable torsion bar 22 at its one end and is also linked to a pinion 32. A piston 38 provided with a rack 40 and a one-way clutch 50 is disposed in its vicinity. If the piston 38 is driven when a vehicle speed is suddenly reduced, the spool 14 is rotated through the pinion 32 and looseness of a webbing 26 is removed. If webbing pulling-force acts after that, the torsion load of the torsion bar 22 and the resistance load of the one-way clutch 50 act as a force-limiter load. If the spool 14 is further rotated, the pinion 32 is disengaged with the rack 40. Therefore, the force-limiter load can be reduced.

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 for tensioning a webbing in an occupant restraining direction when a vehicle is suddenly decelerated.
The present invention relates to a webbing retractor capable of absorbing energy by allowing webbing to be pulled out.

[0002] The present invention also relates to a vehicle provided with the webbing take-up device.

[0003]

2. Description of the Related Art In a webbing take-up device, rotation of a spool (winding shaft) in a webbing pull-out direction is locked at the time of rapid deceleration of a vehicle, so that webbing is not pulled out. As this lock mechanism,
Locking means is arranged near the device frame on one end side of the spool, and when the vehicle is suddenly decelerated, the locking means is actuated to prevent rotation of the spool in the webbing pull-out direction.

Further, in such a webbing take-up device, when the webbing is prevented from being pulled out, a predetermined amount of webbing is pulled out to absorb energy. As this energy absorbing mechanism, for example, there is a structure in which a spool and a torsion bar are arranged coaxially with the spool. Generally, the torsion bar is connected at one end to a spool and at the other end to a lock base connected to a lock means so as not to rotate relative to each other. Normally, the spool and the lock base rotate integrally via the torsion bar.However, when the lock base is prevented from rotating in the webbing pull-out direction during rapid deceleration of the vehicle, the spool is moved to the lock base by the webbing pulling force. On the other hand, it rotates in the webbing pull-out direction. At this time, the torsion bar is twisted to absorb energy, and the spool is allowed to rotate a predetermined amount.
Such absorbed energy is determined by the product of the load applied to the webbing (force limiter load) and the webbing withdrawal amount (spool rotation amount). In the webbing take-up device, the force limiter load and the allowable rotation amount of the spool are determined. (Torsion limit of the torsion bar).

However, in such a conventional webbing take-up device, the force limiter load at the time of energy absorption is governed by the material properties and dimensions of the torsion bar, and only a constant value from the start to the end of energy absorption. Could not give.

By the way, if the force limiter load can be reduced after the spool rotates a predetermined amount, a large force limiter load is applied in the initial stage of sudden deceleration of the vehicle to thereby absorb energy per spool rotation amount (webbing withdrawal amount). Is increased, the amount of webbing withdrawn (the amount of movement of the occupant) can be suppressed. On the other hand, after the predetermined energy absorption, the load (load) acting on the occupant can be reduced by reducing the force limiter load.

Particularly, in a vehicle equipped with an airbag device, the total load acting on the occupant can be reduced by reducing the force limiter load immediately before the contact between the airbag and the occupant, thereby further reducing occupant injury. can do.

In addition, if the force limiter load characteristic can be changed as described above by utilizing the pretensioner mechanism generally provided in the webbing take-up device, the whole webbing take-up device has a simple and compact configuration. Can be.

In consideration of the above facts, the present invention has a simple and compact structure, and when a webbing is allowed to be withdrawn to absorb energy, a large force limiter load is applied at an initial stage of energy absorption to provide a predetermined energy. A first object is to obtain a webbing take-up device to which a small force limiter load can be applied after absorption.

[0010] It is a second object of the present invention to provide a vehicle that includes the above-described webbing retractor and the airbag device and that can reduce the load acting on the occupant.

[0011]

According to a first aspect of the present invention, there is provided a webbing take-up device comprising: a tubular spool from which webbing is wound and drawn; and one end of the spool. A lock base provided coaxially with the spool and rotatably relative to the spool; and a webbing of the lock base provided to be connected to the lock base and engaged with a frame when a predetermined acceleration is detected. Locking means for preventing rotation in the pull-out direction, and provided in the spool coaxially with the spool, one end of which is connected to the spool and the other end of which is connected to the lock base. And the lock base is prevented from rotating in the webbing pull-out direction rotation direction by the lock means while being twisted by the webbing pulling force. A torsion bar for rotating the spool relative to the lock base in a webbing pull-out direction, a piston provided to be engageable with the spool, a cylinder fixed to the frame and having the piston inserted therein, and communicating with the cylinder; Gas supply means capable of supplying gas into the cylinder, and when the vehicle suddenly decelerates, the gas supply device is operated, and the piston slides in the cylinder to forcibly rotate the spool. And a pretensioner mechanism for tensioning the webbing in the occupant restraint direction.The webbing retractor is provided in the cylinder, and after the pretensioner mechanism is actuated, the spool rotates in the webbing pullout direction. The resistance force associated with the relative movement between the piston and the cylinder It is characterized by having a resistance means to the time difference.

In the webbing take-up device according to the first aspect, the spool and the lock base are connected via a torsion bar, and these usually rotate integrally. Further, in the pretensioner mechanism, the piston and the spool are normally in a disengaged state, and the piston does not hinder the rotation of the spool. For this reason, normally, the webbing can be freely taken up and pulled out.

When the vehicle suddenly decelerates, the gas supply device of the pretensioner mechanism is operated to supply gas into the cylinder. Due to the pressure of the gas, the piston slides while engaging with the spool, whereby the spool is forcibly rotated in the webbing take-up direction, the slack of the webbing is removed, and the webbing is tightly mounted on the occupant (pre-tensioner mechanism). Operation is terminated).

At this time, since the predetermined acceleration (deceleration) at the time of rapid deceleration of the vehicle has already been detected, the locking means is actuated and engaged with the frame, and the rotation of the lock base in the webbing withdrawing direction is prevented. .

After the pretensioner mechanism is actuated, when a webbing pulling force accompanying the inertial movement of the occupant acts, the webbing pulling force acts on the torsion bar via the spool as a rotational force in the webbing pull-out direction, and also via the spool. This also acts as a moving force of the piston in the initial position return direction. For this reason, the torsion bar is twisted, and the piston moves while resisting the resistance caused by the relative movement with the cylinder, and the load acting on the webbing (occupant) is kept constant (the torsion load of the torsion bar and the resistance means). The spool is rotated in the webbing withdrawal direction with respect to the lock base while the resistance load of the first acting as a constant force limiter load, and the webbing is withdrawn.
The next energy absorption is achieved.

When the spool is further rotated and the piston is moved to the initial position, the engagement between the spool and the piston is released, so that the webbing pulling force acts only as the rotating force of the torsion bar. Thus, the force limiter load is reduced by the resistance load. At this time, the secondary energy absorption is achieved while the torsional load of the torsion bar acts as a constant force limiter load.

As described above, the webbing take-up device according to the first aspect has a simple and compact structure. When the webbing is allowed to be pulled out and energy is absorbed, a large force limiter load is initially applied to the energy absorption. After the predetermined energy absorption, a small force limiter load can be added.

According to a second aspect of the present invention, in the webbing retractor according to the first aspect, the resistance means is provided on at least one of an outer periphery of the piston or an inner periphery of the cylinder. The pre-tensioner mechanism is arranged between the piston and the cylinder inner wall when the pre-tensioner mechanism is operated. After the tensioner mechanism is actuated, the spool is held between the piston and the inner wall of the cylinder when the spool is rotated in the webbing withdrawing direction, and the ball generates a resistance force associated with the movement of the piston. It is characterized by a one-way clutch.

In the webbing take-up device according to the second aspect,
When the pretensioner mechanism is operated, the ball constituting the one-way clutch is not restrained between the piston and the inner wall of the cylinder, so that there is no resistance generated by the movement of the piston. Therefore, the piston is smoothly slid while engaging with the spool, and the spool is forcibly rotated in the webbing winding direction, so that the slack of the webbing is removed and the piston is tightly mounted on the occupant.

On the other hand, at the time of energy absorption after the operation of the pretensioner mechanism, when the webbing pulling force acts as a moving force of the piston via the spool, the ball constituting the one-way clutch is pinched between the piston and the inner wall of the cylinder. Therefore, the piston returns to the initial position (webbing pull-out direction) while the ball and the cylinder inner wall are in contact with each other, or while the cylinder or the ball is plastically deformed.
Move to. For this reason, the piston is moved to the initial position while a kinetic friction force or a resistance force due to plastic deformation is generated between the ball and the inner wall of the cylinder. As a result, in addition to the torsional load of the torsion bar, the kinetic friction load accompanying the movement of the piston or the resistance load accompanying the plastic deformation acts as a force limiter load, and after the piston is moved to the initial position, the torsion of the torsion bar is reduced. Only the load acts as a force limiter load.

As described above, in the webbing take-up device according to the second aspect, when the webbing is allowed to be pulled out and energy is absorbed by a simpler and more compact structure, a large force limiter is initially used for energy absorption. A load can be reliably applied, and a small force limiter load can be applied after a predetermined energy absorption.

Further, in the webbing take-up device according to the third aspect of the present invention, in the webbing take-up device according to the first aspect, the resistance means is formed in a shape of a hollow truncated cone whose outer diameter increases toward one end. And a cap connected to the piston such that the outer peripheral portion of the one end contacts the inner wall of the cylinder.

In the webbing take-up device according to the third aspect,
When the pretensioner mechanism is activated, the piston moves while deforming the conical portion of the cap so as to be constricted inward, so that the resistance force accompanying the movement of the piston is small. Therefore, the piston is smoothly slid while engaging with the spool, and the spool is forcibly rotated in the webbing winding direction, so that the slack of the webbing is removed and the piston is tightly mounted on the occupant.

On the other hand, when energy is absorbed after the pretensioner mechanism is actuated, when the webbing pulling force acts as a moving force of the piston via the spool, the piston is deformed so as to expand the conical portion of the cap to the outside, and the piston moves in the webbing withdrawing direction. Go to For this reason, the lower end of the cap gnaws the inner wall of the cylinder, and the piston is moved to the initial position while a galling resistance is generated between the cap and the inner wall of the cylinder. As a result, in addition to the torsional load of the torsion bar, the galling load caused by the movement of the piston acts as a force limiter load, and after the piston is moved to the initial position, only the torsional load of the torsion bar is used as the force limiter load. Works.

As described above, the webbing take-up device according to the third aspect has a simpler and more compact structure, and when the webbing is allowed to be pulled out and energy is absorbed, a large force limiter is initially used for energy absorption. A load can be reliably applied, and a small force limiter load can be applied after a predetermined energy absorption.

According to a fourth aspect of the present invention, there is provided the webbing retractor according to any one of the first to third aspects, wherein the gas in the cylinder is exhausted. It is characterized by having provided.

In the webbing take-up device according to the fourth aspect,
At the time of energy absorption after the operation of the pretensioner mechanism,
When the webbing pulling force acts as a moving force of the piston via the spool, the piston is moved to the initial position while reliably discharging gas remaining in the cylinder from the small holes. Thus, a stable force limiter load can be obtained while the piston is moved to the initial position, without being affected by the load associated with the compression of the gas that exhibits unstable behavior.

As described above, the webbing take-up device according to the fourth aspect has a simpler and more compact structure, and when the webbing is allowed to be pulled out and energy is absorbed, a large force limiter is initially used for energy absorption. The load can be more reliably applied, and a small force limiter load can be applied after the predetermined energy absorption.

According to a fifth aspect of the present invention, there is provided a vehicle according to any one of the first to fourth aspects.
A vehicle provided with the webbing take-up device according to claim and further including an airbag device, wherein the engagement state between the spool and the piston is released immediately before contact between the airbag and an occupant. .

In the vehicle according to the fifth aspect, immediately before the contact between the airbag and the occupant, the engagement between the spool and the piston is released, and the force limiter load is reduced by the resistance load by the resistance means. Therefore, before contact between the airbag and the occupant, a large force limiter load is applied to increase the amount of energy absorption per spool rotation amount, so that the webbing withdrawal amount (occupant movement amount) can be suppressed. . On the other hand, since the force limiter load is reduced after the contact between the airbag and the occupant, the total load acting on the occupant is reduced, and the degree of occupant injury can be reduced.

As described above, the vehicle according to the fifth aspect includes the above-described webbing winding device and the airbag device, and can reduce the load acting on the occupant.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows the overall configuration of a webbing take-up device 10 according to the present embodiment.

The webbing take-up device 10 includes a frame 12
It has. The frame 12 includes a pair of opposing leg pieces 1.
2A, a leg piece 12B and a back piece 12C connecting the leg pieces are formed in a substantially U-shape. The back piece 12C extends downward, and its lower end is fixed to the vehicle body by bolts.

The opposite leg pieces 12A, 12 of the frame 12
B, a cylindrical spool 14 whose axial direction is the direction opposite to the leg pieces 12A and 12B is provided. One end of a webbing 26 is locked to the spool 14, and the webbing 26 can be taken up and pulled out of the spool 14 by rotation of the spool 14.

In the cylinder of the spool 14, a lock base 16 is disposed at an end on the leg piece 12A side. The lock base 16 is rotatably supported coaxially with the spool 14 at the opening of the leg 12A of the frame 12. The lock base 16 is connected to a lock plate 24 that constitutes a lock means. When an acceleration sensor (not shown) detects a predetermined acceleration (deceleration), the lock plate 24 bites into the frame 12 to rotate the lock base 16. Is prevented.

The lock base 16 has a spool 1
The hexagonal portion of the torsion bar 20 disposed in the in-cylinder axial portion of No. 4 is inserted, and the lock base 16 is configured to always rotate integrally with the one-side hexagonal portion of the torsion bar 20.

On the other hand, a sleeve 18 is disposed at the end of the leg 14B inside the spool 14 cylinder. Sleeve 18
The spline-shaped teeth 20 fit into the spool 1
4 and is supported coaxially and rotatably with the spool 14 at the opening of the leg piece 12B.
The tip of the sleeve 18 protrudes outward from the leg piece,
Furthermore, a spring (not shown) is provided at the end of the protruding portion. Thus, the sleeve 18 is constantly urged to rotate in the direction of winding the webbing 34.

Further, the sleeve 18 is connected to the lock base 16 by inserting the hexagonal portion of the other end of the torsion bar 20 described above. This allows
Normally, the spool 14, the sleeve 18, the torsion bar 20, and the lock base 16 are configured to rotate integrally.

Further, the webbing take-up device 10 includes a pretensioner mechanism 30, and the pretensioner mechanism 3
0 has a pinion 32. The pinion 32 is connected to the outer end of the spool 14 of the sleeve 18, and is always rotated integrally with the spool 14 via the sleeve 18. Therefore, the rotation of the pinion 18 causes the spool 14 to rotate, and the webbing 26
Can be wound or unwound.

Further, a cylinder 34 is fixed to the leg piece 12B. The cylinder 34 is formed in a cylindrical shape, and has an upper end opened near the pinion 32. A piston 38 is provided in the cylinder 34. The bottom of the piston 38 is formed in a disk shape and is slidable in the cylinder 34. Piston 38
A seal holding part 42 is connected to the bottom of the seal holding part 42, and an O-ring 44 for sealing between the seal holding part 42 and the inner wall of the cylinder 34 is fitted on the outer periphery of the seal holding part 42.

On the other hand, at the bottom of the cylinder 34, a concave portion 36 is provided.
Are integrally formed. The recess 36 has a smaller diameter than the inner diameter of the cylinder, and the cylinder 34 and the recess 36 are stepped. By engaging the O-ring 44 with this step, the piston 38 does not bottom out.
The position where the O-ring 44 engages with this step is the initial position of the piston 38.

The cylinder 34 has a gas supply device 46.
Are connected to the gas supply device 46, and control means 48
Is connected. Thus, at the time of rapid deceleration of the vehicle, the control means 48 operates the gas supply device 46, and the piston 38 is moved in the direction of the arrow A in FIG.

On the other hand, a rack 4
0 is provided integrally. The rack 40 corresponds to the above-described pinion 32 and is usually located with a predetermined gap from the pinion 32 (disengaged). Thus, when the rack 40 slides in the cylinder 34 in the direction of arrow A in FIG. 2A together with the piston 38, the rack 40 meshes with the pinion 32 and moves the pinion 32 in the webbing 26 winding direction (FIG. 2A). (In the direction of arrow B).

The amount of rotation of the spool 14 forcibly rotated by the pretensioner mechanism 30 is
2, the stroke length of the piston 38 and the rack 40,
The number of teeth of the pinion 32 is determined.

A one-way clutch 50 constituting a resistance means is provided between the piston 38 and the seal holding portion 42. A pair of disks 52 and 54 are provided between the rack 40 and the seal holding portion 42, and this disk 5
Between the disk 2 and the disk 54, there is provided a frustoconical tapered portion 56 whose cross-sectional area decreases downward. Further, a pair of cylinders 34 is provided between the disks 52 and 54.
One or a plurality of balls 58 are arranged between the inner wall and the tapered portion 56. The one-way clutch 50 is configured such that the ball 58 is always located between the two disks 52 and 54.

The ball 58 has a piston 38 as shown in FIG.
2A, the piston 38 is positioned between the inner wall of the cylinder 34 and the small-diameter portion of the tapered portion 56 without being restrained, and the piston 38 is moved in the direction of the arrow D in FIG. When it moves in the (return direction), it is configured to be sandwiched between the inner wall of the cylinder 34 and the large diameter portion of the tapered portion 56. As a result, the one-way clutch 50
Generates a resistance only when it moves in the direction of arrow D in FIG. 2 (B).

Instead of the one-way clutch 50, a one-way clutch in which a tapered portion having a large diameter at the upper portion is provided on the inner surface of the cylinder and a ball is arranged between the straight portion and the piston may be employed. good.

Next, the operation of the present embodiment will be described.

In the webbing take-up device 10 having the above configuration,
The spool 14 and the lock base 16 are connected to the torsion bar 2
Since they are connected by a zero, they usually rotate together. The rack 4 provided on the piston 38
0 is disengaged from the pinion 32, and the rack 40 does not hinder the rotation of the spool 14. For this reason,
Normally, the webbing 26 can be freely taken up and pulled out.

When the vehicle reaches a sudden deceleration state, first, the pretensioner mechanism 30 operates. That is, when the gas supply device 46 is operated, the pressure of the gas supplied into the cylinder 34 causes the piston 38 to move in the direction indicated by the arrow A in FIG.
The rack 40 is slid in the direction shown in FIG.
It is rotated in the direction of arrow B in (A). As a result, the spool 14 is forcibly rotated in the webbing winding direction, the slack of the webbing 26 is removed, and the spool 14 is tightly mounted on the occupant (the operation of the pretensioner mechanism 30 is completed).

At this time, in the one-way clutch 50, since the ball 58 is located between the inner wall of the cylinder 34 and the small diameter portion of the tapered portion 56 and does not generate any resistance, the piston 38 slides smoothly.

On the other hand, when the pretensioner mechanism 30 is operated,
Since the predetermined acceleration (deceleration) accompanying the sudden deceleration of the vehicle has already been detected, the lock plate 2 constituting the locking means
4 engages with the frame 12 to prevent the lock base 16 from rotating in the webbing pull-out direction.

Therefore, after the pretensioner mechanism 30 is actuated, when a webbing pulling force is applied due to the occupant's inertial movement, the webbing pulling force is applied to the torsion bar 20 via the spool 14 and the sleeve 18 by a rotational force in the webbing pull-out direction. , And also acts as a moving force of the piston 38 in the initial position return direction via the spool 14, the pinion 32, and the rack 40.

Here, when a tensile force acts on the webbing 26 and the pinion 32 is rotated in the direction of arrow C in FIG. 2B through the spool 14, the ball 58 constituting the one-way clutch 50 is The piston 38 is located between the inner wall and the large-diameter portion of the tapered portion 56, and the piston 38 is returned to the initial position while the ball 58 and the inner wall of the cylinder 34 are in contact with each other, or while the cylinder 34 or the ball 58 is plastically deformed. 2 (B) in the direction of arrow D). Therefore, a dynamic frictional force or a resistance force due to plastic deformation is generated between the ball 58 and the inner wall of the cylinder 34 while the piston 3
8 is moved to the initial position. Thereby, the spool acting on the webbing 26 (occupant) is kept constant (while the torsional load of the torsion bar 22 and the kinetic friction load caused by the movement of the piston 38 act as the force limiter load of F2 shown in FIG. 3). 14 is a lock base 16
Is rotated in the webbing pull-out direction with respect to the webbing 2
6 is withdrawn and primary energy absorption is achieved.

The spool 14 is further rotated and the piston 3
When the pin 8 is moved to the initial position, the engagement between the pinion 32 and the rack 40 is released, so that the webbing pulling force acts only as a rotational force of the torsion bar 22. For this reason, the force limiter load decreases by the amount of the dynamic friction load accompanying the movement of the piston 38. Therefore, the secondary energy absorption is performed while the torsional load of the torsion bar 22 acts as the force limiter load of F1 shown in FIG.

At this time, the webbing tensile force and the spool 1
The rotation amount of No. 4 has a relationship shown in FIG. 3, and the force limiter load can be reduced after the spool 14 has rotated a predetermined amount. For this reason, a large force limiter load is applied in the initial stage of rapid deceleration of the vehicle to increase the amount of energy absorption per time to suppress the webbing withdrawal amount (movement amount of the occupant). The load on the occupant can be reduced by adding a limiter load to reduce the amount of energy absorbed per time. In particular, in a vehicle equipped with an airbag device, the load acting on the occupant can be reduced by reducing the force limiter load immediately before the contact between the airbag and the occupant, and the occupant injury can be further reduced. .

Since the webbing withdrawal amount allowed during energy absorption is generally larger than the webbing winding amount by the pretensioner mechanism 30, the above-described force limiter load characteristics can be obtained.

As described above, in the webbing take-up device 10 according to the present embodiment, the force limiter load can be reduced in the process of allowing the webbing to be pulled out and absorbing energy with a simple and compact structure. . (Modification of Resistance Means) The webbing take-up device 10 according to the above-described embodiment has a configuration including the pretensioner mechanism 30. However, the webbing take-up device 10 may include a pretensioner mechanism according to a modification described below. good. Components common to the above-described embodiment are denoted by the same reference numerals as in the above-described embodiment, and description thereof will be omitted.

The webbing take-up device 10 includes a pretensioner mechanism 6 shown in FIG.
0 may be provided.

The pretensioner mechanism 60 includes a cap 62 instead of the one-way clutch 50 constituting the resistance means. A cap 62 is provided at the bottom of the piston 38. The cap 62 has a shape of a hollow truncated cone with a lower end opening whose outer diameter increases toward the bottom surface of the cylinder 34 (see FIG. 4B), and is coaxial with the piston 38 and in contact with the inner wall surface of the cylinder 34. Stopper 6
4 is fixed to the bottom surface of the piston 38.
The position at which the lower end of the cap 62 engages with the step formed by the lower part of the cylinder 34 and the recess 36 is the piston 38.
Is the initial position.

In the webbing take-up device provided with the pretensioner mechanism 60, when the piston 38 is driven in the webbing take-up direction by the operation of the gas supply device 46 during rapid deceleration of the vehicle, the conical portion of the cap 62 is turned inward. Since the piston 38 moves while being deformed so as to be narrowed, the resistance force accompanying the movement of the piston 38 is small. Therefore, the piston 38 is driven smoothly, and the rack 40 and the pinion 32 are driven.
, The spool is forcibly rotated in the webbing winding direction, the slack of the webbing 26 is removed, and the spool is tightly mounted on the occupant.

On the other hand, at the time of energy absorption after the operation of the pretensioner mechanism 60, when the webbing 26 is subjected to a tensile force and the pinion 32 is rotated in the reverse direction via the spool 14, the conical portion of the cap 62 is expanded outward. The piston 38 moves in the webbing withdrawing direction while being deformed to the shape shown in FIG. For this reason, the lower end of the cap 62 galls on the inner wall of the cylinder 38, and the piston 38 is moved to the initial position while galling resistance is generated between the cap 62 and the inner wall of the cylinder 34. As a result, in addition to the torsional load of the torsion bar 22, the galling load accompanying the movement of the piston 38 reliably acts as a force limiter load. Spool 1
After the piston 4 is further rotated and the piston 38 is moved to the initial position, only the torsional load of the torsion bar acts as a force limiter load.

Therefore, in the webbing take-up device provided with the pretensioner mechanism 60, the force limiter load characteristic shown in FIG. 3 can be obtained similarly to the webbing take-up device according to the above-described embodiment.

Further, the webbing take-up device 10 is provided in FIG.
A configuration including a pretensioner mechanism 70 shown in FIG.

The pretensioner mechanism 70 includes a one-way clutch 72 instead of the one-way clutch 50 in the pretensioner mechanism 30. One-way clutch 72
Then, the small hole 7 communicating the inside and outside of the cylinder 34 with the disk 74
6 are provided.

Further, the webbing take-up device 10 has a structure shown in FIG.
A configuration including a pretensioner mechanism 90 shown in FIG.

The pretensioner mechanism 90 includes a cap 92 instead of the cap 62 in the pretensioner mechanism 60.
It is a configuration provided with. The cap 92 includes the cylinder 34
Is provided with a small hole 94 communicating the inside and outside.

In the webbing take-up device provided with the pretensioner mechanism 70 or the pretensioner mechanism 90, when energy is absorbed after the operation of the pretensioner mechanism, a tensile force acts on the webbing 26 and the pinion 32 is inverted via the spool 14. When rotated, the piston 38 moves to the initial position while reliably discharging gas remaining in the cylinder 34 from the small holes 76 or 94. This allows
During the movement of the piston 38 to the initial position, a stable force limiter load can be obtained without being affected by the load accompanying the compression of the gas that exhibits unstable behavior.

Therefore, in the webbing take-up device provided with the pretensioner mechanism 70 or the pretensioner mechanism 90, a certain force limiter load can be reliably applied during the primary energy absorption.

In the above embodiment, the one-way clutch 72 or the small hole 94 constitutes the resistance means.
Alternatively, a configuration in which the small holes are provided in the cylinder 34 may be employed.

The webbing take-up device 10 according to the above embodiment can be applied to a vehicle provided with an airbag device.

In this vehicle, the engagement between the pinion 32 and the rack 40 can be released immediately before the contact between the airbag and the occupant. Accordingly, when the occupant comes into contact with the airbag, the force limiter load is reduced by the resistance load by the one-way clutch 50 or 72 or the cap 62 or 92. Therefore, before the contact between the airbag and the occupant, a large force limiter load is applied to increase the amount of energy absorption per rotation amount of the spool 14, so that the webbing withdrawal amount (the occupant movement amount) can be suppressed. . On the other hand, since the force limiter load is reduced after the contact between the airbag and the occupant, the total load acting on the occupant is reduced, and the degree of occupant injury can be reduced.

In this case, the timing of contact between the airbag and the occupant can be set in advance by adjusting the magnitude of the load applied by the resistance means.

As described above, the vehicle provided with the airbag device using the webbing take-up device 10 according to the above embodiment can reduce the load acting on the occupant.

[0076]

As described above, the webbing take-up device according to the present invention has a simple and compact structure, and when a webbing is allowed to be drawn out to absorb energy, a large force limiter is initially used for energy absorption. After applying a load and absorbing a predetermined energy, a small force limiter load can be applied.

Further, the vehicle according to the present invention includes the above-described webbing winding device and the airbag device, and can reduce the load acting on the occupant.

[Brief description of the drawings]

FIG. 1A is a side view of a webbing take-up device according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view showing the entire configuration.

FIG. 2A is a cross-sectional view when a pretensioner mechanism constituting a webbing take-up device according to an embodiment of the present invention is operated, and FIG. 2B is a cross-sectional view when energy is absorbed.

FIG. 3 is a diagram showing a relationship between a webbing pulling force (force limiter load) of a webbing take-up device according to an embodiment of the present invention and a rotation amount of a spool in a webbing pull-out direction.

FIG. 4A is a cross-sectional view of a pretensioner mechanism constituting a webbing take-up device according to a modification of the embodiment of the present invention, and FIG. 4B is a perspective view of a cap constituting the pretensioner mechanism. .

FIG. 5 is a cross-sectional view of a pretensioner mechanism included in a webbing take-up device according to a modification of the embodiment of the present invention, where (A) is a cross-sectional view showing a case where a small hole is provided in a one-way clutch. (B) is a sectional view showing a case where a small hole is provided in the cap.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Webbing take-up device 12 Frame 14 Spool 16 Lock base 18 Sleeve 22 Torsion bar 24 Lock plate (Lock means) 26 Webbing 30 Pretensioner mechanism 32 Pinion 34 Cylinder 38 Piston 40 Rack 46 Gas supply device 50 One-way clutch (Resistance means) Reference Signs List 60 Pretensioner mechanism 62 Cap (resistance means) 70 Pretensioner mechanism 72 One-way clutch (resistance means) 76 Small hole 90 Pretensioner mechanism 92 Cap (resistance means) 94 Small hole

Claims (5)

[Claims] A cylindrical spool from which the webbing is taken up and drawn; a lock base provided at one end of the spool so as to be coaxial with and relatively rotatable with the spool; and a lock base connected to the lock base. Locking means for engaging the frame when a predetermined acceleration is detected to prevent rotation of the lock base in the webbing pull-out direction, and provided in the spool coaxially with the spool, one end of which is provided on the spool. The other end of the lock base is connected to the lock base, and the spool and the lock base are normally rotated integrally. A torsion bar for rotating the spool relative to the lock base in a webbing pull-out direction, A piston provided to be engageable with the spool, a cylinder fixed to the frame and into which the piston is inserted, and a gas supply unit that is in communication with the cylinder and can supply gas into the cylinder, A pretensioner mechanism for actuating the gas supply device during rapid deceleration of the vehicle, forcibly rotating the spool by sliding the piston in the cylinder, and tensioning the webbing in the occupant restraining direction. In the webbing take-up device, when the spool is rotated in the webbing withdrawing direction after the pretensioner mechanism is provided in the cylinder, a resistance force caused by a relative movement between the piston and the cylinder is provided. A webbing take-up device provided with a resistance means for causing a wobble. 2. The method according to claim 1, wherein the resisting means is disposed between at least one of an outer periphery of the piston and an inner periphery of the cylinder, between the piston and the inner wall of the cylinder at the tapered portion, When the tensioner mechanism is operated, the piston is not restrained between the piston and the inner wall of the cylinder, and after the pretensioner mechanism is operated, when the spool is rotated in the webbing pull-out direction, the piston and the piston are rotated. 2. A webbing take-up device according to claim 1, wherein the one-way clutch comprises a ball held between the inner wall of the cylinder and a ball which generates a resistance force due to the movement of the piston. 3. A cap formed in the shape of a truncated cone having an outer diameter increasing toward one end and connected to the piston such that an outer peripheral portion of the one end contacts the inner wall of the cylinder. The webbing take-up device according to claim 1, wherein: 4. The webbing take-up device according to claim 1, wherein a small hole capable of discharging gas in the cylinder is provided. 5. A vehicle comprising the webbing take-up device according to claim 1 and an airbag device, wherein the vehicle is provided with the spool immediately before contact between the airbag and an occupant. A vehicle wherein the engagement state with the piston is released.