JP2001310706A - Seat belt device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat belt device capable of certainly operating an energy absorbing mechanism and adequately absorbing energy. SOLUTION: This seat belt device comprises a substantially cylindrical bobbin 34 for winding a webbing for constraining a passenger to a seat, a plurality of torsion members 35 and 36 that are arranged inside the bobbin coaxially with and radially of the bobbin, and are joined with the bobbin, and an engaging part for selectively preventing rotation of the torsion members in response to a supplied operation command signal. The plurality of torsion members are arranged through a clearance (a) for preventing interference between the members by their twists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat belt device, and more particularly to an improvement in a seat belt device provided with an energy absorbing mechanism for reducing compression of webbing due to inertial movement of an occupant in a collision.

[0002]

2. Description of the Related Art In the event of a vehicle collision or the like, a seat belt device restrains an occupant to a seat by webbing to prevent forward movement, thereby ensuring safety from a secondary collision. For this reason, the retractor of the seat belt device is provided with a lock mechanism that prevents the webbing from being pulled out in the event of a collision.

[0003] However, when the vehicle suddenly decelerates due to a collision or the like, inertia acts on the occupant, and the occupant tries to move to the front of the seat. At this time, the locked webbing may compress the occupant's chest. In order to reduce this, when a webbing withdrawing force exceeding the reference value acts on the retractor, an energy absorbing mechanism built in the retractor allows the webbing to be withdrawn to reduce the compression of the chest.

For example, Japanese Unexamined Patent Publication (Kokai) No. 11-129865 discloses that the stop position of a torsion bar and a torsion sleep blocking member provided on a common blocking member is changed by moving a stopper pressing bar according to the weight of an individual. It is determined. It can be engaged individually or together with the torsion bar and torsion sleeve, allowing for two levels of energy absorbing loading.

[0005] Japanese Patent Application Laid-Open No. 11-286259 discloses that when the weight of an occupant is small, the torsional force of only the torsion bar is used. When the weight of the occupant is more than the above, the pin is moved by an actuator and the pin is moved by a torsion pipe or a lock bar. And changes the torsional load. When the pin is engaged with the lock lever, the delivery of the seat belt is stopped.

[0006] In the international application WO97 / 49583, one end of a torsion bar is connected to a block blocking member of a belt winding device via a profile head. Things.

[0007] In addition, as a known example of an energy absorbing mechanism using a torsion shaft and a torsion pipe, there is German Patent Publication DE19653510.

[0008]

SUMMARY OF THE INVENTION As described above,
-129865, JP-A-11-286259, WO97 / 49583, and DE19653551
The known technology described in each publication of No. 0 includes a plurality of torsion members such as a torsion shaft and a torsion pipe as an energy absorbing mechanism, and a torsion plastic deformation force of a torsion shaft and a torsion member such as a torsion pipe as an energy absorbing means. Is used to absorb energy.

However, in a structure in which energy is absorbed by using the torsional plastic deformation force of the torsion pipe, when a torsional load is applied to the torsion pipe, the inner diameter of the torsion pipe shrinks (decreases), and in addition, the torsion pipe has a smaller diameter. The dimension in the axial extension direction is also reduced (shorter).
For this reason, the torsion pipe comes into contact with another adjacent torsion member due to the reduction of the inner diameter due to the torsion,
Operation will be affected. Due to this influence, reliable operation of the energy absorbing mechanism and appropriate energy absorption cannot be obtained. Also, when the axial extension direction dimension is reduced due to the torsion pipe torsion, if there is no fixed torsion pipe shrinkage direction space (gap) or the length of the rotation transmitting engagement portion, the members of the torsion pipe will be twisted. May cause interference, or the engagement required for transmitting the rotational force may be insufficient.

Accordingly, an object of the present invention is to provide a seat belt device in which an energy absorbing mechanism operates reliably and an appropriate energy is absorbed.

[0011]

In order to achieve the above object, a seat belt device according to the present invention comprises a substantially cylindrical bobbin for winding webbing for restraining an occupant to a seat, and a coaxial inner bobbin inside the bobbin. A plurality of torsion members which are arranged in a radial direction so as to form a shape arrangement and are coupled to the bobbin; and a member which selectively prevents rotation of the plurality of torsion members in response to a supplied operation command signal. And a torsion member, wherein the plurality of torsion members are arranged via a gap for preventing interference between the members due to twisting of the members.

With this configuration, it is possible to ensure the operation of the energy absorbing mechanism and obtain an appropriate energy absorbing load.

[0013] Preferably, the engagement portion of the torsion member is set to a length in which an extra dimension of the dimension in the axial direction due to torsion of the member is added in advance.

[0014] Preferably, the gap is set in advance to a length at least exceeding a decrease in a radial dimension due to twisting of the member.

[0015] Preferably, the plurality of torsion members include a torsion shaft and one or more torsion pipes.

[0016] Preferably, the gap between the adjacent torsion members is 0.5 mm or more.

Preferably, the clearance is subjected to a treatment for reducing sliding resistance, for example, Teflon processing, grease (oil) addition, mirror finishing, plating, etc., on the surface of the torsion member.

Preferably, an extra dimension is added to the axially extending length of the engaging portion of the torsion member.
５5 mm.

Preferably, the engaging portion of the torsion member has a length of at least 1 mm in the axial direction in consideration of the decrease in the axial direction due to the torsion of the torsion member so that the engaging portion can be securely engaged. It is said to be.

The retractor of the seat belt device according to the present invention has a substantially cylindrical bobbin for winding webbing for restraining an occupant to a seat, and a radial direction inside the bobbin so as to be coaxial with the bobbin. A plurality of torsion members arranged and coupled to the bobbin, and an engagement portion for selectively blocking rotation of the plurality of torsion members in response to a supplied operation command signal; The torsion member is arranged via a gap for preventing interference between members due to twisting of the member.

According to this structure, a certain gap exists between the torsion members, the engagement portion of the torsion member can surely transmit the rotation, and the engagement portion of the torsion member extends in the axial extending direction. In this case, since it is possible to move a predetermined distance and to achieve sufficient engagement, it is possible to make the occupant have an appropriate energy absorbing ability.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Overall Configuration) Embodiments of the present invention will be described below with reference to the drawings. FIG. 19 shows the configuration of the seat belt device. One end of the webbing 4 for restraining the occupant to the seat 2 is retracted and stored by the retractor 3, and the other end is attached to the vehicle body 6 via an anchor plate 5 with bolts. Webbing 4
Is the turnbuckle 8 attached to the upper part of the center pillar
Will be folded back. The webbing 4 is provided with a tongue plate 7 through which the webbing 4 is inserted. By engaging the tongue plate 7 with a buckle 11 supported by a support member 10 on the waist side of the seat 2, the seat belt is fastened. Done. The retractor 3 includes, for example, a take-up storage unit 3a that winds the webbing around a bobbin, a lock unit 3b that includes a lock mechanism that locks the rotating shaft of the bobbin to prevent rotation in the webbing pull-out direction in the event of a collision, The pretensioner 3c forcibly rotates the bobbin in the winding direction of the webbing in order to remove the slack of the webbing, and the urging force for removing the slack of the webbing and the winding when the webbing is released is removed. It is constituted by a spiral spring portion 3d for giving a given tension. As described later, the winding storage section 3a
Is provided with an energy absorbing (shock absorbing) mechanism using a plurality of torsion members (twisted members) such as a torsion shaft (twisted shaft) and a torsion pipe (twisted pipe). An airbag device 24 is provided on a steering wheel or a dashboard (not shown) of the vehicle.

As shown in FIG. 20, the vehicle is provided with a control device 23 for controlling the operation of the above-described seat belt device. A weight sensor 21 for detecting the weight of the occupant is provided at the bottom of the seat 2, and the output of the weight sensor 21 is supplied to the control unit 23. The output of the collision sensor 22 that is attached to the vehicle and detects a collision is supplied to the control unit 23.

The control unit 23 is a vehicle-mounted computer.
The weight and deceleration of the occupant are determined based on the outputs of the weight sensor 21 and the collision sensor 22, and the webbing withdrawal load acting on the occupant is calculated. The operation of the later-described first and second actuators 31 and 32 is controlled in accordance with the pull-out load. Thereby, an energy absorbing operation in an energy absorbing mechanism using a plurality of torsion members such as a torsion shaft and a torsion pipe at the time of a collision is selected. That is, an energy absorbing operation according to the pull-out load acting on the webbing 4 due to the occupant's inertial movement due to the collision can be performed. Further, the control unit 23 activates the pretensioner 25 in the event of a collision, forcibly winds up the webbing to remove slack, and restrains the occupant to the seat. Control unit 23
When the impact of the collision is equal to or higher than a predetermined level, the airbag device 24 is also operated.

An outline of the operation of the seat belt device will be described. When the vehicle collides with an obstacle, the collision sensor 22 detects the collision, and the control unit 23 operates the pretensioner 3c, rotates the bobbin in the winding direction of the webbing, removes the slack of the webbing 4, and removes the occupant from the seat. Restrict to 2.
In addition, the locking mechanism 3b operates by deceleration or sudden withdrawal of the webbing 4, locks one end of the rotating shaft of the bobbin, and prevents rotation in the webbing withdrawal direction. In addition,
It is possible to rotate the webbing 4 in the winding direction. Furthermore,
When the impact of the collision exceeds a predetermined value, the airbag device 24 operates to deploy the bag. The occupant moves forward due to inertia, and a pull-out force acts on the webbing. When it is determined that the withdrawal force exceeds the operation value of the energy absorbing mechanism set based on the occupant weight and / or the degree of impact, as will be described in detail later, the torsion member formed on the rotary shaft portion of the bobbin (A torsion shaft, a plurality of torsion pipes, a combination thereof, etc.) are selected, a torsional load is set, and the webbing 4 can be pulled out. Thereby, the chest load received by the occupant by the webbing is reduced. A secondary collision with the steering wheel or the like due to the occupant moving forward is prevented by the airbag. In this way, occupant safety in the event of a vehicle collision is achieved.

(Embodiment 1) Next, an energy absorbing mechanism according to a first embodiment will be described with reference to FIGS.

FIG. 1 is a cross-sectional view mainly showing the front of the retractor 3 centering on the take-up storage section 3a and the lock mechanism section 3b. For convenience of explanation, the pretensioner 3c and the spiral spring section 3d are detached. Have been. FIG.
It is sectional drawing in the AA 'direction of FIG. FIG. 3 is a left side view showing the left side of the slide lever portion of the retractor 3 shown in FIG. FIG. 4 is an explanatory diagram illustrating the operation of the latch plate and the pawl of the lock mechanism 3b. FIG.
FIG. 3 is an explanatory diagram illustrating an energy absorbing mechanism in a state where an actuator 31 is operated. FIG. 6 is a cross-sectional view taken along line BB ′ of FIG.
3 is a cross-sectional view showing a cross section of FIG. FIG. 7 is a cross-sectional view of FIG.
It is sectional drawing which shows the cross section in C '. FIG. 8 is a sectional view showing a section taken along line DD ′ of FIG. FIG. 9 is an explanatory diagram illustrating the energy absorbing mechanism in a state where the actuator 32 operates. FIG. 10 is a sectional view showing a section taken along line EE ′ of FIG. FIG. 11 is a cross-sectional view of FIG.
It is sectional drawing which shows the cross section in F '.

The first embodiment is an example in which the energy absorbing ability can be controlled in three stages. As a plurality of torsion members, one torsion shaft and one torsion member arranged radially coaxially with the shaft. And two torsion pipes. Then, the torsional drag of only the torsion shaft, the combined torsional drag of the torsion shaft and the torsion pipe, and the torsional drag of only the torsion pipe can be selected. Thereby, three stages of energy absorption are possible.

As shown in FIG. 1, the retractor base 33 has a substantially U-shape having a pair of opposed side walls, and the openings provided on both side walls serve as bearings. To rotatably hold the bobbin 34. The bobbin 34 has a substantially cylindrical shape around which webbing (not shown) is wound. The bobbin 34 is hollow, and a torsion shaft 35 disposed coaxially with the bobbin 34 inside the hollow.
And a torsion pipe 36. The lock mechanism 3b described above is attached to the right end side of the torsion shaft 35 and the torsion pipe 36 by a screw that is screwed to the center of the shaft at the end of the shaft 35. The operation of the energy absorbing mechanism is provided on the left end side of the torsion shaft 35 and the torsion pipe 36 by an engagement portion that selectively prevents the rotation of the torsion shaft 35 and the torsion pipe 36 in response to the supplied operation command signal. Is selected.

The torsion shaft 35 and the torsion pipe 36 are arranged via a gap a for preventing mutual interference. The gap a between the torsion members is such that when a torsional load is applied, the torsion pipe 3
In consideration of the reduction of the inner diameter due to the twist of No. 6, the length is set in advance to at least exceed the reduction in the radial dimension of the torsion pipe 36. Thereby, the torsion shaft 35
And the torsion pipe 36 can be prevented from interfering with each other, and proper energy absorption can be obtained without affecting the operation related to energy absorption.

The torsion shaft 35 and the torsion pipe 3
The gap a between the six (radial distance between the outer circumference of the torsion shaft 35 and the inner circumference of the torsion pipe 36) is usually 0.5 mm or more, though it depends on the crushing rigidity of the torsion pipe 36 and the like. It is preferable (see the experimental example described later). By setting the gap a to 0.5 mm or more, when a torsional load is applied to the torsion pipe 36, it is possible to avoid contact with the torsion shaft 35 due to reduction of the inner diameter due to the torsion. It is possible to prevent the torsion member from contacting the torsion member 35 and preventing proper operation of each of these torsion members. Therefore, proper energy absorption can be performed,
A function as an energy absorbing mechanism is exhibited.

The upper limit of the gap a is determined by the torsion shaft 3
5 and the shape of the torsion pipe 36 can be set freely within an allowable range. However, due to the shrinkage allowance of the torsion pipe 36 described later, the gap a is set to 4 m.
m or less. That is, the gap a is 0.5
４4 mm, especially 0.5０．５3 mm
More preferably, it is in the range of mm.

The stiffness of the torsion pipe 36 is not particularly limited as long as the gap a is set so as to prevent interference between the torsion members as described above. In addition, the collapse rigidity of the torsion pipe 36 is mainly caused by the inner diameter and the thickness of the torsion pipe 36 in many cases. Accordingly, by setting the inner diameter and the thickness of the torsion pipe 36 in appropriate ranges according to the diameter of the torsion shaft, it is possible to further prevent the torsion members from interfering with each other. Further, the collapse rigidity of the torsion pipe 36 is also caused by the material of the torsion pipe 36, but the preferable range of the gap a described above is an example in which a torsion pipe made of low carbon steel is used.

The right end of the torsion shaft 35 is fixed to the latch plate 37 so as to always rotate integrally with the latch plate 37 by providing a polygon or serration. At the left end of the torsion shaft 35, a shaft diameter portion (or a circumferential groove that loops around the shaft outer periphery) 35 a (see FIG. 11) that can slide and rotate with respect to the inner diameter of the lock plate 38, and the lock plate 3
The shaft diameter portion (circumferential groove) 35 is slidable in the longitudinal direction of the shaft.
One or a plurality of grooves (axial grooves) 35b (see FIG. 8) which are continuous with the lock plate 38 and engage with the lock plate 38 are formed.

The torsion pipe 36 has a coaxial arrangement in which the torsion shaft 35 and the bobbin 34 have a common central position. As described above, a predetermined gap is provided between the torsion pipe 36 and the torsion shaft 35, and a gap is also provided between the torsion pipe 36 and the bobbin 34. The bobbin 34 and the torsion shaft 35 affect the rotation of the torsion pipe 36. It is made not to give. At the right end of the torsion pipe 36, a polygon or serration is provided, and the latch plate 37 is formed with a shape that engages with it. The torsion pipe 36 is movable in the axial direction by sliding at the engagement portion 36a with the latch plate 37. By the movement of the torsion pipe 36, a state in which the torsion pipe 36 and the latch plate 37 are engaged (see FIG. 2) and a state in which the torsion pipe 36 is not engaged (see FIG. 7) can be selected.

The torsion pipe 36 has an engaging portion 36a.
In the gap between the torsion shaft 35 and the torsion pipe 36, for example, processing such as Teflon processing, addition of grease (oil), mirror finishing, plating, etc., to reduce the sliding resistance is performed. Is preferably applied to prevent galling and twisting between the engaging member and the non-engaging member and to obtain a predetermined energy absorbing force.

The engaging portion 36a of the torsion pipe 36 is movable in the axial extension direction as described above, and in particular, is movable by 1 mm or more due to a contraction margin of the pipe and an energy absorption stroke described later. It is preferred that

The engaging part 3 in the torsion pipe 36
6a is set to a length in which an extra dimension of the dimension in the axial direction due to the twist is added in advance for the following reason. That is, when the torsion pipe 36 is twisted by applying a torsional load, the circular shape of the cross section is crushed and deformed into a worm gear shape (a state where a towel is squeezed), so that the total length of the torsion pipe 36 is shortened. In order to forcibly prevent the entire length of the torsion pipe 36 from being shortened in this way, for example, it is conceivable to provide a highly rigid retractor base or a mounting portion. However, if the length of the torsion pipe 36 is forcibly prevented, an extra stress is applied to the torsion pipe 36, and the torsion pipe 36 is torsioned by a load less than a specified value. For this reason, the torsion pipe 36
Rather than shortening the entire length of the torsion pipe 3, for example, by increasing the length of the gap b (see FIG. 9) between both cut portions of the torsion pipe 36 and the bobbin 34.
6 to prevent interference with other parts, or the engagement part 3 between the latch plate 37 and the torsion pipe 36.
In view of the fact that the length c (see FIG. 1) in the axial extension direction at 6a becomes short, measures such as increasing the total length of the torsion pipe 36 in advance may be taken. For this reason, the engagement portion 36a of the torsion pipe 36 is set to have a length in which an extra dimension in the axial extension direction due to the torsion is added in advance.

Before the torsion pipe 36 is twisted, the state where the two steps of the torsion pipe 36 and the bobbin 34 are closest (the state where the energy absorbing load of the energy absorbing mechanism described later is “medium” (the state shown in FIG. 9) In (2), when a load is applied in this state, only the torsion pipe 36 is twisted, so that the step portions of the torsion pipe 36 and the bobbin 34 are further closer to each other, and the gap b is further reduced. Therefore,
The gap b needs to be longer than a certain value.

The torsion shaft 35 and the torsion pipe 3
When both 6 are twisted, the total length of the torsion pipe 36 is reduced, so that the length c of the engaging portion 36a in the axial extending direction is reduced. Therefore, it is necessary to secure the engagement (width) and strength of the engagement portion 36a by increasing the total length of the torsion pipe 36 in advance. For example, in view of securing necessary strength, it is preferable that the length c of the engaging portion 36a of the torsion pipe 36 in the axial extending direction is 5 mm or more.

When a torsional load is applied to the torsion pipe 36, the shrinkage of the torsion pipe 36 is
There is a certain relationship between the torsion shaft 35 and the gap a between the torsion pipes 36. That is, if the gap a is large, the amount of crushing of the torsion pipe 36 also increases, and the amount of shrinkage increases accordingly (see graph 3 in FIG. 18 of an experimental example described later). In addition, a graph 3 described later is a graph showing a relationship between a gap between the shaft and the pipe and a shrinkage allowance per rotation of the pipe. This shrinkage allowance is required for torsion pipe 3
6 corresponds to the movable amount in the extending direction. In consideration of the energy absorption stroke, it is necessary to secure the movable amount for 3 to 4 rotations of the pipe. For this reason,
In order to secure an amount of 3 to 4 rotations, the movable amount in the extending direction of the torsion pipe 36 must be at least one.
mm.

As described above, the upper limit of the gap a is inevitably determined from the shrinkage allowance. For example, the gap a is 4 mm
Then, shrinkage allowance 4mm x (3-4) rotation = 12-14mm
Becomes However, it is difficult to secure such dimensions in each of the gap b and the engaging portion length c with a realistic physical size of the retractor.

At the left end of the torsion pipe 36, a slide lever 40 is arranged. Slide lever 40
Is connected to the actuator 31 provided on the retractor base 33, and the torsion pipe 36 is moved in the axial direction (rightward in the example in the figure) in accordance with the operation of the actuator 31.
Go to The actuator 31 includes a system that generates combustion gas in a cylinder, an electromagnetic system, and the like. The torsion pipe 36 does not move with a force lower than the operating force of the actuator 31. When the actuator 31 operates and the slide lever 40 moves the torsion pipe 36 to the right, the engagement between the torsion pipe 36 and the latch plate 37 is released. The rotation of the torsion pipe 36 is free.

One or more grooves 34a extending in the direction of the central axis are formed on the inner periphery of the left end of the bobbin 34. One or more through-holes 36b extending in the axial direction are formed in the torsion pipe 36 at positions facing these elongated grooves 34a. Also, these through holes 36 of the torsion pipe 36
One or a plurality of grooves 35b extending in the axial direction are formed at the position of the torsion shaft 35 facing b. These grooves 35
b is continuous with a groove 35a around the torsion shaft 35 at its end. These include a groove 34a, a through hole 36b,
The lock plate 38 is arranged in a region surrounded by the groove 35b. The lock plate 38 has a shape that penetrates the through hole 36 b, the outer protrusion thereof contacts the groove 34 a on the inner periphery of the bobbin 34, and the inner protrusion contacts the groove 35 b of the torsion shaft 35. The lock plate 38 is axially movable with respect to the bobbin 34, the torsion pipe 36, and the torsion shaft 35, and always rotates integrally with the bobbin 34. The lock plate 38 is connected to the actuator 32 provided on the retractor base 33 via a slide lever 39. Like the actuator 31, the actuator 32 can use a gas expansion (explosive) type, an electromagnetic type, or the like. The lock plate 38 is connected to the actuator 32.
When the actuator 32 operates, it does not move with a driving force equal to or less than the driving force, and can move in the axial direction (to the right in the example of the drawing). When the lock plate 38 moves in the axial direction and the inward projection reaches the groove 35a of the torsion shaft 35, the engagement between the lock plate 38 and the torsion shaft 35 is released,
A free state is provided between the torsion shaft 35 and the bobbin.

Therefore, when the actuators 31 and 32 are not operated, the bobbin 34 and the latch plate 37 are connected to each other by the torsion shaft 35 and the torsion pipe 36. When only the actuator 31 is operated, the bobbin 34 and the latch plate 37 are connected to each other by the torsion shaft 35. When only the actuator 32 operates,
The bobbin 34 and the latch plate 37 are connected by a torsion bar 36. Therefore, three levels of energy absorption are obtained.

Next, the operation of the seat belt device to detect the deceleration (or acceleration) of the vehicle body and the speed of withdrawing the webbing to prevent the bobbin from rotating, and the energy absorbing mechanism
The operation of changing the type of load will be described.

In the normal state, the control unit 23 does not operate the actuators 31 and 32. By the non-operation of the actuator 31, as shown in FIGS. 1 and 2,
The torsion shaft 35 and the latch plate 37 are engaged with an engagement portion 37a.
Is engaged. Further, the torsion pipe 36 and the latch plate 37 are engaged at an engaging portion 36a. The torsion shaft 35, the torsion pipe 3
6 and the latch plate 37 rotate integrally.

When the actuator 32 is not operated, the position of the lock plate 38 is at the position shown in FIG. 1 and FIG.
4. The torsion pipe 6 and the torsion shaft 35 are mutually engaged. As a result, the bobbin 34 and the latch plate 37
Is in a state of being integrally rotated.

FIG. 4 shows that the acceleration sensor (not shown) provided in the vicinity of the lock mechanism 3b detects a deceleration exceeding a predetermined value due to a vehicle collision or the like, or that the webbing withdrawal acceleration exceeds a predetermined value. Thus, the pole 42 provided in the lock mechanism 3b rotates clockwise. The pawl 42 engages with the latch plate 37,
The rotation of the bobbin 34 is locked, and the webbing is prevented from being pulled out. Note that a configuration may be employed in which the control unit 23 that detects the collision causes the pawl 42 to engage. As a result, the webbing is not extended from the bobbin, and the occupant can be restrained.

The control section 23 comprehensively determines the webbing withdrawal force due to the forward movement of the occupant at the time of a collision based on the control data such as the weight by the weight sensor 21 and the degree of collision by the collision sensor 22 described above. Control the absorption mechanism. For example, the set load of the energy absorbing mechanism is set to “small”, “medium”, and “large”.

For example, when the weight of the occupant is light (for example, less than 50 kg), the degree of collision is light, or when the weight of the occupant is heavy but the degree of collision is very light, the control unit 23 can reduce the webbing withdrawal force. Sets the set load of the energy absorbing mechanism to “small”.

For example, when the weight of the occupant is moderate (for example, 50 kg or more and less than 100 kg), the degree of collision is moderate, and the weight of the occupant is heavy but the degree of collision is light, the webbing withdrawal force is controlled. If the value is medium, the set load of the energy absorbing mechanism is set to “medium”.

For example, when the weight of the occupant is heavy (for example, 100 kg or more), the degree of collision is severe, the weight of the occupant is medium, but the degree of collision is large in the table. If the webbing withdrawal force due to the movement of the occupant is large, the set load of the energy absorbing mechanism is set to “large”.

When the control unit 23 determines that the set load of the energy absorbing mechanism is “small”, the actuator 31 is operated. When the actuator 31 operates, the torsion pipe 36 moves in the axial direction (rightward), and moves from the position shown in FIG. 1 to the position shown in FIG. In this state, the engaging portion 36a at the right end of the torsion pipe 35 is
7 and the bobbin 34 and the latch plate 3
7 are connected only by the torsion shaft 35.
Therefore, the webbing pull-out force (draw-out load of the energy absorbing mechanism) due to the movement of the occupant in the collision becomes a torsional load of the torsion shaft 35.

When the control unit 23 determines that the set load of the energy absorbing mechanism is “medium”, the actuator 32 is operated. When the actuator 32 operates, the lock plate 38 moves rightward in the axial groove 35b of the torsion shaft 35 and moves to the circumferential groove 35a. Thereby, the engagement between the lock plate 38 and the torsion shaft 35 is released, and the torsion pipe 36 is provided between the bobbin 34 and the lock plate 37.
They are linked only by. Therefore, the webbing pull-out force (draw-out load of the energy absorbing mechanism) due to the movement of the occupant in the collision becomes a torsional load of the torsion pipe 36.

When the control unit 23 determines that the set load of the energy absorbing mechanism is "large", the actuators 31 and 32 are not operated. If both actuators do not work,
As shown in FIG. 7, the bobbin 34 and the lock plate 37 are connected by a torsion shaft 35 and a torsion pipe 36. Therefore, the webbing pull-out force (draw-out load of the energy absorbing mechanism) due to the movement of the occupant in the collision becomes a torsional load of the torsion shaft 35 and the torsion pipe 36.

As described above, according to the first embodiment, the state in which the bobbin 34 and the torsion shaft 35, and the state in which the torsion pipe 36 and the latch plate 37 are engaged with each other is changed according to the webbing pull-out load. Not released (drawer load “large”), disengagement of the left end of bobbin 34 and torsion shaft 35 (drawer load “medium”), disengagement of torsion pipe 36 and right end of latch plate (drawer load “small”) )), Select.

In particular, when the control unit 23 selects the "middle" withdrawal load, the torsion shaft 35 is not twisted and the torsion pulp 36 is twisted. Then, when the torsion pulp 36 is twisted, its cylindrical cross section is crushed and deforms like a worm gear. The deformed torsion pulp 36 tends to tighten the torsion shaft 35 coaxially arranged when the gap a does not have a predetermined interval. In such a state, the deformed torsion pulp 36 and the torsion shaft 35 are integrated through a contact portion. Thereby, the torsion shaft 35 which is originally free and cannot be twisted is also twisted together with the torsion pulp 36. As a result, the control unit 23 sets the set load of the energy absorbing mechanism to “medium”.
Despite the determination, the load setting for twisting both the torsion shaft 35 and the torsion pulp 36 becomes “large” (both twist).

For this reason, it is necessary to set the collapse rigidity of the torsion pulp 36 and the gap a between the torsion shaft 35 and the torsion pulp 36 in a well-balanced manner. The crushing rigidity is determined by the wall thickness if the inner diameter is constant. The crushing rigidity changes with the power of the wall thickness in consideration of the section modulus. Therefore, if the thickness of the torsion pulp 36 is large, the crushing rigidity is increased, and the required amount of the gap a is also reduced.

In this embodiment, an example in which a torsion shaft and a torsion pipe are used as described above is described, but the present invention is not limited to this example as long as a plurality of torsion members are used. For example, a plurality of torsion members including one torsion shaft and a plurality of torsion pipes arranged coaxially with the shaft in a radial direction (for example, an energy absorbing mechanism shown in FIG. 12). Is also good. In this case, the torsional force of only the torsion shaft, the combined torsional force of the torsion shaft and the first torsion pipe, the combined torsional force of the torsion shaft and the second torsion pipe,..., The combination of the torsion shaft and the nth torsion pipe A torsional drag, a combined torsional resistance of the torsion shaft and the first and second torsion pipes, and a combined torsional drag of the combination of the torsion shaft and the first to nth torsion pipes can be selected. Thereby, multi-stage energy absorption is possible. Furthermore, a device comprising a plurality of torsion pipes without a torsion shaft (for example,
An energy absorption mechanism shown in FIG. 13) may be used, and in this case, energy absorption in three or more stages is possible similarly to the above case. Here, FIGS. 12 and 13
The energy absorbing mechanism shown in FIG. 7 differs from that of the first embodiment in terms of a lock mechanism and the like, but merely shows an example of a plurality of torsion members different from the first embodiment.

(Experimental example) [Relationship between pipe wall thickness and shaft-pipe gap] Wall thickness of pipe (torsion pipe) and shaft (torsion shaft) -pipe gap [between outer circumference of shaft and inner circumference of pipe] The following experiment was conducted to examine the relationship between In this experiment, unlike the retractors shown in FIGS. 1, 5, and 9,
A shaft and a pipe were respectively selected on the bobbin side and fixed to a retractor base. The retractor used here is exactly the same as the retractor shown in FIGS. 1, 5 and 9 with respect to selectively twisting the shaft and / or pulp and transmitting the torsional load to the bobbin. . Therefore, it can be said that the retractor used in this experiment has substantially the same structure as the retractor shown in FIGS.

The inner diameter φ is 10.1 mm and the thickness t is 1.0 m
In a combination of an m or 1.5 mm pipe (low carbon steel) and a solid shaft (low carbon steel), one end (right end) of each of the pipe and the shaft is fixed to a bobbin as shown in FIG. The bobbin, the pipe, and the shaft are allowed to rotate the same. The other end of the shaft is free without being fixed.
The other end (left end) of the pipe is fixed to the retractor base so as not to rotate. Next, the webbing is wound around the bobbin. Thereafter, as shown in FIG. 15, with the webbing wound around the bobbin, the webbing is pulled out of the retractor and pulled to rotate the bobbin. On this occasion,
Set the amount of webbing pulled (crosshead movement amount) to 0.
The webbing tension (load) (kN) when sequentially increasing from (mm) is measured and plotted to make a graph. The graph in FIG. 16 is a graph showing the relationship between the crosshead movement amount and the load at this time. In the graph, the gap between the shaft and the pipe is changed by changing the shaft diameter.

Point A in the graph shown in FIG. 16 is a point where the shaft undergoes torsional deformation (bending point). The mechanism by which this shaft generates torsional deformation is as follows. In other words, if the gap between the shaft and the pipe is small, the neck formed by twisting the pipe in a state of squeezing a towel bites into the shaft. As a result, the shaft that originally rotates with the bobbin is fixed to the pipe by biting by the constricted portion of the pipe, so that torsional deformation occurs.

A pipe having a thickness t of 1.5 mm without a central axis (Graph 1-G), a gap of 1.55 mm and 1.
The point A is substantially the same in the case of 05 mm (graphs 1-A and 1-B). On the other hand, a pipe having the same thickness and a gap of 0.
In the case of 8 mm (graph 1-C), the crosshead movement amount indicating the point A is shorter than that of the above-mentioned one, and after the point A is exceeded, the torsion torque of the solid shaft is added. Also,
A pipe with a thickness t of 1.0 mm, a gap of 2.05 mm,
The results shown in graphs 1-D, 1-E, and 1-F were obtained for the samples with 1.05 mm and 0.80 mm, respectively.

The graph shown in FIG. 17 is a graph showing the relationship between the pipe wall thickness and the required gap. The necessary gap here is obtained by plotting the experimental result of the graph of FIG. If the pipe thickness is large, the pipe has high crushing rigidity. Therefore, even if the gap is small, a bending point such as point A in the graph of FIG. 16 does not occur. The graph of FIG. 17 changes with a power of the section modulus of the pipe cylinder. Considering a practical energy absorption load and a wall thickness in processing a part, the wall thickness t is
It is preferably about 1.0 to 2.0 mm. Therefore, the required gap when the thickness t is 2.0 is preferably 0.5 mm or more in consideration of variations.

From the above experimental results, considering the range of a practical energy absorbing load, the gap a is at least 0.5
It is understood that it is preferable to set it to mm (see the graph of FIG. 17).

[Relationship between the gap between the pipe and the shaft and the amount of shrinkage of the pipe] When the solid shaft is twisted, the diameter decreases, so that the shaft extends in the direction in which the shaft extends. On the other hand, if you twist the pipe,
The pipe collapses like a towel, like a worm gear. For this reason, the length of the pipe in the axial extension direction is reduced.

The graph shown in FIG. 18 is a graph showing the relationship between the pipe-shaft gap and the shrinkage allowance of the pipe. If the gap between the pipe and the shaft is small, the pipe will not be easily crushed,
Shrinkage is also reduced (see graph). In the graph, when the gap is about 1 mm, the shrinkage of the pipe is about 0.2 mm when twisted by one rotation. 400m
In order to secure an energy absorption stroke of about m
The required number of rotations is about three. Need for stroke (3 rotations when the webbing wound on the bobbin is 700 to 800 mm, 40 when the remaining webbing is less)
For an energy absorption stroke of 0 mm, the number increases to 3 to 4 rotations. ), 0.2 × 4 = 0.8
mm. Therefore, it is necessary to consider that the length of the pipe for absorbing energy is reduced by at least about 1 mm in the axial direction.

[0069]

As described above, according to the seat belt device of the present invention, the operation of the energy absorbing mechanism is ensured.
It is possible to provide a seat belt device capable of obtaining appropriate energy absorption.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a retractor illustrating an energy absorbing mechanism (normal state, large webbing pull-out load) of a first embodiment.

FIG. 2 is a sectional view taken along the line AA ′ of FIG. 1;

FIG. 3 is a left side view showing a left side surface of a slide lever portion of the retractor shown in FIG. 1;

FIG. 4 is an explanatory diagram illustrating operations of a latch plate and a pawl of a lock mechanism unit 3b.

FIG. 5 is an explanatory diagram illustrating an energy absorbing mechanism (small webbing pull-out load) in a state where an actuator 31 is operated.

FIG. 6 is a sectional view showing a section taken along line BB ′ of FIG. 5;

FIG. 7 is a sectional view showing a section taken along the line CC ′ of FIG. 5;

FIG. 8 is a sectional view showing a section taken along line DD ′ of FIG. 5;

FIG. 9 is an explanatory diagram illustrating an energy absorbing mechanism (during a webbing pull-out load) in a state where an actuator 32 is operated.

FIG. 10 is a sectional view showing a section taken along line EE ′ of FIG. 9;

FIG. 11 is a sectional view showing a section taken along line FF ′ of FIG. 9;

FIG. 12 is a sectional view of a retractor illustrating an energy absorbing mechanism of another embodiment.

FIG. 13 is a cross-sectional view of a retractor illustrating an energy absorbing mechanism according to another embodiment.

FIG. 14 is a schematic sectional view of a retractor having an energy absorbing mechanism used in an experimental example.

FIG. 15 is a schematic sectional view (right side view) showing a state where the webbing is pulled from the retractor of FIG.

FIG. 16 is a graph showing a relationship between a crosshead movement amount and a load.

FIG. 17 is a graph showing a relationship between a pipe wall thickness and a clearance required between the shaft and the pipe.

FIG. 18 is a graph showing a relationship between a gap between a shaft and a pipe and a shrinkage allowance of the pipe.

FIG. 19 is an explanatory diagram illustrating the configuration of the seat belt device.

FIG. 20 is a block diagram illustrating a control system of the seatbelt device.

[Explanation of symbols]

 Reference Signs List 3 retractor 21 weight sensor 22 collision sensor 23 control unit 31, 32 actuator 34 bobbin 35 torsion shaft 36 torsion pipe 37 latch plate 38 lock plate

Claims (1)

[Claims] A substantially cylindrical bobbin for winding webbing for restraining an occupant to a seat, and a plurality of bobbins arranged inside the bobbin in a radial direction so as to be coaxial with the bobbin and coupled to the bobbin. A plurality of torsion members, and an engagement portion for selectively preventing rotation of the plurality of torsion members in response to a supplied operation command signal, wherein the plurality of torsion members are formed by torsional deformation of the members. A seatbelt device, wherein the seatbelt device is disposed via a gap for preventing interference between members.