JP7324149B2 - Pretensioner and seat belt device - Google Patents

Description

The present disclosure relates to pretensioners and seatbelt devices.

In a vehicle seatbelt device, a configuration has been proposed in which a pretensioner is provided that operates in an emergency such as a vehicle collision and pulls in members to be retracted, such as webbing and buckles, thereby increasing the restraining force of the webbing on the occupant of the vehicle. there is

In the conventional pretensioner, when gas is injected into the gas chamber from the gas generator, the piston is pushed by the high pressure gas and moves inside the cylinder. As a result, the wire connected to the member to be retracted is pulled, and the member to be retracted is retracted, thereby increasing the restraining force of the webbing on the occupant of the vehicle (for example, Patent Document 1).

JP-A-2000-326823

A situation may occur in which the piston becomes difficult to move in the cylinder or becomes fixed in the cylinder, for example, a state in which excessive force is applied to the member to be retracted and the piston cannot fully pull the wire. In this state, if gas is injected from the gas generator to activate the pretensioner, there is a risk that the pressure in the gas chamber will rise above normal.

An object of the present disclosure is to provide a pretensioner and a seatbelt device that can suppress the internal pressure of a gas chamber from rising above normal.

A pretensioner according to an aspect of an embodiment of the present invention is a pretensioner that is actuated in an emergency to draw in a member to be retracted to increase restraining force of a webbing on a vehicle occupant. A wire to which one end is connected, a piston connected to the other end of the wire, a cylinder slidably housing the piston, and a gas for operating the piston in the direction in which the wire is drawn. a gas generator for supplying gas to the gas chamber in the cylinder; a pressure receiving member arranged facing the gas chamber; and, when the internal pressure of the gas chamber exceeds a predetermined value larger than the pressure at which the piston can normally move, the regulating member cancels the regulation of the pressure receiving member to reduce the volume of the gas chamber. The pressure receiving member is movable in the increasing direction.

ADVANTAGE OF THE INVENTION According to this indication, the pretensioner and seatbelt apparatus which can suppress that the internal pressure of a gas chamber rises more than usual can be provided.

It is a lineblock diagram of a seat belt device concerning an embodiment. 1 is a perspective view of a pretensioner according to a first embodiment; FIG. It is an exploded perspective view of a pretensioner. It is a longitudinal cross-sectional view of a pretensioner. It is an assembly perspective view around a piston. It is a figure which shows the 1st procedure of an internal pressure rise suppression process. It is a figure which shows the 2nd procedure of an internal pressure rise suppression process. It is a figure which shows the 3rd procedure of an internal pressure rise suppression process. It is a figure which shows the 4th procedure of internal pressure rise suppression processing. It is an assembly perspective view of the piston periphery which concerns on the 1st modification of 1st Embodiment. It is a longitudinal cross-sectional view around a piston according to a second modification of the first embodiment. It is a longitudinal cross-sectional view around a piston according to a third modification of the first embodiment. It is a perspective view of the pretensioner which concerns on 2nd Embodiment. It is a longitudinal cross-sectional view of a pretensioner. 4 is an exploded perspective view of elements housed inside the cylinder of the pretensioner; FIG. It is a figure which shows the 1st procedure of the internal pressure rise suppression process of 2nd Embodiment. It is a figure which shows the 2nd procedure of the internal pressure rise suppression process of 2nd Embodiment. It is a figure which shows the 3rd procedure of the internal pressure rise suppression process of 2nd Embodiment. FIG. 11 is a diagram showing a fourth procedure of internal pressure increase suppression processing according to the second embodiment;

Embodiments will be described below with reference to the accompanying drawings. In order to facilitate understanding of the description, the same constituent elements in each drawing are denoted by the same reference numerals as much as possible, and overlapping descriptions are omitted.

In the following description, x-direction, y-direction, and z-direction are directions perpendicular to each other. Typically the x and y directions are horizontal and the z direction is vertical. The x direction is the sliding direction of the piston 3, and the direction in which the member to be retracted is pulled in is the positive x direction. The x direction is the longitudinal direction of the vehicle when the pretensioner 1 is installed in the vehicle. The y direction is the vehicle width direction when the pretensioner 1 is installed in the vehicle.

[First embodiment]
A first embodiment will be described with reference to FIGS. 1 to 12. FIG. FIG. 1 is a configuration diagram of a seatbelt device 100 according to an embodiment. FIG. 1 shows an example of a state in which a seatbelt device 100 is mounted on a vehicle. A seatbelt device 100 includes a webbing 101 , a retractor 102 , a tongue 105 , a buckle 107 and a pretensioner 1 .

Webbing 101 is a band-like member for restraining an occupant sitting on seat 108 . One end 103 of the webbing 101 is connected to the retractor 102 and the other end 106 of the webbing 101 is connected to the pretensioner 1 .

The retractor 102 is a winding device that allows the webbing 101 to be wound or pulled out, and the webbing 101 is pulled out from the main body of the retractor 102 when an acceleration exceeding a predetermined value is detected, such as at the time of a vehicle collision. It restricts The retractor 102 is fixed to a vehicle body portion (for example, a portion below the pillar to which the shoulder anchor 104 is fixed) on the side of the backrest portion 109 of the seat 108 .

The tongue 105 is a plate-like member slidably attached to the webbing 101 between the pretensioner 1 and the shoulder anchor 104 .

Buckle 107 is a member to which tongue 105 is attached and detached. The buckle 107 is fixed to a seat portion on the side opposite to the retractor 102 across the seat portion 110 of the seat 108 .

By connecting the tongue 105 to the buckle 107, the chest of the occupant on the seat 108 is restrained by the shoulder belt portion 101b of the webbing 101, and the waist of the occupant is restrained by the lap belt portion 101a of the webbing 101. The shoulder belt portion 101 b is the portion of the webbing 101 between the shoulder anchor 104 and the tongue 105 , and the lap belt portion 101 a is the portion of the webbing 101 between the tongue 105 and the pretensioner 1 .

The pretensioner 1 instantly pulls in the lap belt portion 101a of the webbing 101 to take up the slack between the occupant's waist and the lap belt portion 101a when an acceleration greater than or equal to a predetermined value is detected at the time of a vehicle collision or the like. It is a wrap pretensioner that reduces The pretensioner 1 is usually fixed to a vehicle body portion near the door with respect to the vehicle outer side portion of the seat portion 110 .

FIG. 2 is a perspective view of the pretensioner 1 according to the first embodiment. FIG. 3 is an exploded perspective view of the pretensioner 1. FIG. FIG. 4 is a longitudinal sectional view of the pretensioner 1. FIG. FIG. 5 is an assembled perspective view of the piston 3 and its surroundings.

The pretensioner 1 is a device for increasing the restraining force of the vehicle occupant by the webbing 101 by operating in an emergency and retracting the member to be retracted. As shown in FIGS. 2 to 4, the pretensioner 1 includes a wire 2 connected to a webbing 101 that restrains an occupant, a piston 3 arranged on the wire 2, and a cylinder 4 that slidably accommodates the piston 3. , a gas generator 5 that applies a driving force to the piston 3 , a housing 6 that integrally connects the cylinder 4 and the gas generator 5 , and a bracket 7 that is connected to the housing 6 and positions the wire 2 .

The housing 6 includes an insertion hole 61 for guiding the wire 2, a communication portion 62 communicating with the cylinder 4 and the insertion hole 61, and a gas supply port 63 for supplying the gas generated by the gas generator 5 to the communication portion 62. Prepare. A wire guide 8 is arranged at a boundary portion 66 between the insertion hole 61 and the communicating portion 62 .

The pretensioner 1 functions as a belt anchor, and is attached to the vehicle body by inserting a bolt 9 (see FIG. 1) through a fixing hole 7a formed in the bracket 7 and a fixing hole 6a formed in the housing 6. Fixed. The bracket 7 has a guide portion 7b, and the wire 2 is inserted along the guide portion 7b when the bracket 7 is integrally attached to the housing 6, thereby holding the bending angle of the wire 2. As shown in FIG.

A ferrule 22 is connected to one end of the wire 2 via a holder or the like (not shown). The ferrule 22 is connected to the end of the lap belt 101a of the webbing 101, as shown in FIG.

The other end of the wire 2 is passed through the housing 6 via the bracket 7 and connected to the wire end 23 inside the cylinder 4 . A piston 3 is slidably disposed within the cylinder 4 , and the wire 2 is inserted through the piston 3 and then connected to a wire end 23 .

The gas generator 5 is arranged in an opening (gas generator mounting portion 64) formed in the housing 6 and fixed to the housing 6, as shown in FIGS. A gas supply port 63 is formed by a passage that communicates between the gas generator attachment portion 64 and the communication portion 62 .

The gas generator 5 is also connected to, for example, an acceleration sensor (not shown) that detects a vehicle collision, and is activated to eject high-pressure gas into the housing 6 when the vehicle collides. The gas generator 5 generates gas by, for example, an internal explosive. The high-pressure gas jetted into the housing 6 presses the piston 3 to move the piston 3 in the direction away from the housing 6 (positive x direction). As the piston 3 moves, the wire 2 is pulled into the housing 6 and the cylinder 4 to tighten the webbing 101 (lap belt 101a).

The housing 6 is made of, for example, a material having a lower specific gravity than iron (eg, aluminum, aluminum alloy, etc.). Specifically, the housing 6 may be manufactured by aluminum die casting. By adopting a material having a lower specific gravity than iron, the weight of the housing 6 can be reduced.

Further, the housing 6 has an insertion hole 61 for guiding the wire 2 from the bracket 7 to the cylinder 4 on one end side (x negative direction side), and a connecting portion for connecting the cylinder 4 on the other end side (x positive direction side). 65. The wire 2 is inserted into the insertion hole 61 , and the threaded portion of the cylinder 4 is screwed into the connecting portion 65 . A communication portion 62 is formed between the insertion hole 61 and the connection portion 65 to communicate with them.

The inner diameter of the connecting portion 65 is larger than that of the communicating portion 62 , so that a step is formed between the connecting portion 65 and the communicating portion 62 . Also, the inner diameter of the cylinder 4 is formed to be larger than that of the communicating portion 62 . Therefore, when the piston 3 is arranged at the end portion of the cylinder 4 on the negative x direction side, the end face 37 on the negative x direction side of the piston 3 (or the negative x direction end face 43 of the movable portion 40 described later) is positioned at this position. The piston 3 hits a step, thereby restricting further movement of the piston 3 in the negative x direction.

The inner peripheral surface of the communication portion 62 on the side of the insertion hole 61 forms a conical surface whose diameter decreases as it approaches the insertion hole 61 , forming a boundary portion 66 between the insertion hole 61 and the communication portion 62 . . A wire guide 8 made of resin is inserted into the boundary portion 66 . The wire guide 8 has a substantially truncated cone shape and has a hole through which the wire 2 can be inserted in the center. The wire guide 8 has the function of guiding the wire 2 to the communicating portion 62 and sealing the boundary portion 66 . An opening communicating with the gas supply port 63 is formed in a part of the inner peripheral surface of the communicating portion 62 .

A tapered surface 35 is provided at an intermediate portion in the x direction of the piston 3 . The tapered surface 35 is formed such that its outer diameter increases from one end side (negative x direction side) where the end portion 36 of the piston 3 is located toward the other end side (positive x direction side). A ball 32 and a ball ring 33 are arranged on the tapered surface 35 to suppress the backward movement of the piston 3 in the negative x direction. The ball ring 33 is arranged at the end of the tapered surface 35 in the negative x direction, that is, at the portion of the tapered surface 35 where the outer diameter is the smallest. The ball 32 is normally urged from the negative x direction side by the ball ring 33 . The ball 32 is formed with a diameter that does not interfere with the sliding of the piston 3 due to friction caused by contact with the inner peripheral surface of the cylinder 4 when the ball ring 33 is installed.

In particular, in this embodiment, the end 36 of the piston 3 on the negative x direction side has an outer diameter smaller than the inner diameter of the cylinder 4, and is circular enough to form a gap between its outer peripheral surface and the inner peripheral surface of the cylinder 4. It is formed in a columnar shape. A groove 34 is provided in the outer peripheral surface of the end portion 36 in the circumferential direction. An O-ring 31 is fitted in the groove 34 to improve airtightness (see FIG. 6).

Further, an annular movable portion 40 (pressure receiving member) is arranged on the outer peripheral side of the end portion 36 of the piston 3 . The movable portion 40 is fitted into the gap between the outer peripheral surface of the end portion 36 of the piston 3 and the inner peripheral surface of the cylinder 4 . In other words, the O-ring 31 described above improves the airtightness of the gap between the end portion 36 of the piston 3 and the inner peripheral surface of the movable portion 40 . A groove 41 is also provided in the outer peripheral surface of the movable portion 40 along the circumferential direction. An O-ring 42 is fitted in the groove 41 to improve the airtightness of the gap between the outer peripheral surface of the movable portion 40 and the inner peripheral surface of the cylinder 4 .

The movable portion 40 is arranged such that the end face 43 on the negative x direction side is flush with the end face 37 of the piston 3 . A protrusion 38 is formed on the outer peripheral surface of the end portion 36 of the piston 3 so as to protrude radially outward and extend along the circumferential direction of the outer peripheral surface at a position on the positive x direction side of the movable portion 40 . When the end surface 44 of the movable portion 40 on the positive x direction side abuts against the projection 38, the movable portion 40 is restricted from moving relative to the piston 3 in the positive x direction. 43 is kept flush with the end surface 37 of the piston 3 .

That is, as shown in FIG. 5, when the pretensioner 1 normally operates, the movable portion 40 is connected to the end portion 36 of the piston 3 on the negative x direction side at a position where the end surface 43 is flush with the end surface 37. , and is configured to be movable integrally with the piston 3 .

A connecting portion 39 having an outer diameter smaller than that of the end portion 36 is provided between the end portion 36 of the piston 3 on the negative x direction side and the tapered surface 35 .

The procedure of internal pressure increase suppression processing of the pretensioner 1 according to the first embodiment will be described with reference to FIGS. 6 to 9. FIG.

FIG. 6 is a diagram showing the first procedure of the internal pressure increase suppression process. As shown in FIG. 6, before the pretensioner 1 is activated, the space inside the housing 6 formed by the communicating portion 62 of the housing 6 and the gas supply port 63 can be filled with the high-pressure gas from the gas generator 5. It can also be expressed as a gas chamber C. When an opportunity to activate the pretensioner 1 occurs, such as during a vehicle collision, the gas generator 5 ejects high pressure gas into the housing 6 . The high-pressure gas ejected into the housing 6 presses the end face 37 of the piston 3 (and the end face 43 of the movable portion 40).

During normal operation of the piston 3, the high-pressure gas jetted into the housing 6 pushes the piston 3 and moves the piston 3 away from the housing 6 (positive x direction) from the position shown in FIG. As a result, the volume of the gas chamber C is expanded, so the increase in pressure of the gas in the gas chamber C is suppressed. At this time, since the projection 38 receives the end surface 44 of the movable portion 40 in the positive x direction, the movable portion 40 is restricted from moving relative to the piston 3 in the piston moving direction (positive x direction). , the movable portion 40 moves integrally with the piston 3 .

On the other hand, there are cases where the piston 3 becomes difficult to move within the cylinder 4 or is fixed within the cylinder 4, such as a state in which the piston cannot completely pull the wire due to excessive force being applied to the member to be retracted. . In this state, when high-pressure gas is injected from the gas generator 5 to operate the pretensioner 1, in the conventional pretensioner, the piston 3 does not move from the position shown in FIG. Since the movement to the gas chamber C is slow, the increase in the volume of the gas chamber C cannot catch up with the increase in the pressure inside the gas chamber C, and the pressure inside the gas chamber C rises more than usual, which may cause a problem with the pretensioner.

FIG. 7 is a diagram showing the second procedure of the internal pressure increase suppression process. As shown in FIG. 7, in this embodiment, when the pressure in the gas chamber C rises above normal, the projection 38 of the piston 3 is sheared by the end surface 44 of the movable portion 40 . With such a share structure, the restriction on the movable portion 40 is released, and the movable portion 40 can move relative to the piston 3 in the positive x direction. That is, in the first embodiment, the movable portion 40 functions as "a pressure receiving member that is arranged facing the gas chamber C and receives the pressure of the high pressure gas from the gas generator 5". In addition, the projection 38 "regulates the movement of the pressure receiving member (movable part 40) in the direction of increasing the volume of the gas chamber C, and the internal pressure of the gas chamber C is higher than the pressure at which the piston 3 can normally move. It functions as a regulating member that releases the regulation of the pressure receiving member when the predetermined value is exceeded and allows the pressure receiving member to move in the direction of increasing the volume of the gas chamber C.

FIG. 8 is a diagram showing the third procedure of the internal pressure increase suppression process. As shown in FIG. 8, when the protrusion 38 is sheared, the movable portion 40 is pressed by the high-pressure gas at its negative x-direction end surface 43, and moves relative to the piston 3 in the positive x direction. As a result, the volume of the gas chamber C increases by the movement of the movable part 40, as indicated by the dotted line in FIG. can be reduced from a higher than normal state.

FIG. 9 is a diagram showing a fourth procedure of the internal pressure increase suppression process. As shown in FIG. 9, the movable part 40 finally moves to the position of the connecting part 39 between the end 36 of the piston 3 and the tapered surface 35 . Since the outer diameter of the connecting portion 39 is smaller than the end portion 36 , it is smaller than the inner diameter of the inner peripheral surface of the movable portion 40 . Therefore, a gap is formed between the inner peripheral surface of the movable portion 40 and the outer peripheral surface of the connecting portion 39 of the piston 3 . This gap communicates the gas chamber C with the internal space of the cylinder 4, so that the high-pressure gas in the gas chamber C is discharged into the cylinder 4 through this gap. As a result, the pressure in the gas chamber C can be further reduced, and the internal pressure in the gas chamber C can be reliably reduced from a state higher than normal.

As described above, the pretensioner 1 of the first embodiment is provided on the radially outer edge of the pressure receiving surface 37 of the piston 3 as a pressure receiving member arranged to face the gas chamber C, and moves relative to the piston 3. A movable part 40 is provided. In addition, as a restricting member that restricts the movement of the movable portion 40 as a pressure receiving member in the direction of increasing the volume of the gas chamber C (positive x direction), it protrudes radially outward from the outer peripheral surface of the piston 3, A protrusion 38 is provided extending along the circumferential direction. The projection 38 as a regulating member regulates the movement of the movable portion 40 in the movement direction of the piston 3, and is movable when the internal pressure of the gas chamber C exceeds a predetermined value higher than the pressure at which the piston 3 can normally move. The regulation of the portion 40 is released, and the movable portion 40 is allowed to move relative to the piston in the moving direction of the piston 3 .

Due to this configuration, as shown in FIGS. 7 to 9, a situation occurs in which the piston 3 is difficult to move within the cylinder 4 or is fixed within the cylinder 4, and the pressure within the gas chamber C rises above normal. In this case, the movable portion 40, which is normally arranged to be flush with the pressure receiving surface (end surface 37) of the piston 3, moves relative to the piston 3 in the positive x direction, thereby increasing the volume of the gas chamber C. increases. As a result, the pressure in the gas chamber C can be reduced, so that the internal pressure of the gas chamber C can be prevented from rising above normal. In addition, it is possible to suppress the occurrence of troubles in the pretensioner 1 due to an increase in internal pressure.

In addition, in the pretensioner 1 of the first embodiment, the protrusion 38 as the regulating member is sheared by the movable portion 40 when the internal pressure of the gas chamber C exceeds a predetermined value, thereby releasing the regulation of the movable portion 40. do.

Since the protrusion 38 is provided to extend in the circumferential direction of the outer peripheral surface of the piston 3 , it can normally receive the end surface 44 of the movable portion 40 on the positive x direction side over the entire circumferential direction. Since the contact area with is relatively large, the movement of the movable portion 40 in the positive x direction can be restricted more reliably. Further, when the internal pressure of the gas chamber C rises above normal, the protrusion 38 is sheared off from the outer peripheral surface of the end portion 36 of the piston 3 and removed, so that the movable portion 40 can move smoothly in the positive x direction. , the increase in the internal pressure of the gas chamber C can be suppressed more quickly.

In addition, in the pretensioner 1 of the first embodiment, the outer peripheral surface of the piston 3 is movable at a position where the movable portion 40 faces the movable portion 40 when the regulation by the protrusion 38 as a regulation member is released and the movable portion 40 moves relatively. It is formed so that a gap is formed between it and the portion 40 . Specifically, as shown in FIG. 9 and the like, a connecting portion 39 between the end portion 36 of the piston 3 and the tapered surface 35 has an outer diameter smaller than that of the end portion 36 .

With this configuration, as shown in FIG. 9, when the movable portion 40 moves relative to the piston 3 in the positive x direction due to an increase in the internal pressure of the gas chamber C, the movable portion 40 and the piston 3 is formed, and the gas chamber C and the internal space of the cylinder 4 communicate with each other through this gap. As a result, the high-pressure gas in the gas chamber C can be discharged into the cylinder 4, the pressure in the gas chamber C can be further reduced, and the internal pressure in the gas chamber C can be reliably reduced from a state higher than normal. can.

The connecting portion 39 may have any structure as long as a gap is formed between the movable portion 40 and the movable portion 40 when the movable portion 40 moves to the position of the connecting portion 39, and a structure other than the small diameter shown in FIG. good. For example, the outer peripheral surface may be tapered or stepped so that the outer diameter becomes smaller toward the positive x direction. Alternatively, the outer diameter of the connection portion 39 may be the same as that of the end portion 36 and a groove may be provided on the outer peripheral surface of the connection portion 39 . In this case, the groove communicates the gas chamber C with the internal space of the cylinder 4 .

A modification of the first embodiment will be described with reference to FIGS. In this embodiment, the protrusion 38 projecting radially outward from the outer peripheral surface of the piston 3 and extending in the circumferential direction functions as a restricting member. good.

FIG. 10 is an assembled perspective view around the piston 3 according to the first modified example of the first embodiment. As shown in FIG. 10, a plurality of plate members 45 projecting radially outward from the outer peripheral surface of the end portion 36 of the piston 3 and arranged along the circumferential direction of the outer peripheral surface may be provided as the restricting member. In this configuration, the plate member 45 receives the end surface 44 of the movable portion 40 in the positive x direction, thereby restricting the movable portion 40 from moving relative to the piston 3 in the piston moving direction (positive x direction). In addition, when the internal pressure of the gas chamber C exceeds a predetermined value, the plate member 45 is bent by the movable portion 40, thereby releasing the regulation of the movable portion 40. FIG.

FIG. 11 is a longitudinal sectional view around the piston 3 according to the second modification of the first embodiment. As shown in FIG. 11, a configuration may be adopted in which a biasing member 46 such as a spring that biases the movable portion 40 in the direction opposite to the moving direction of the piston 3 (x negative direction side) is provided as the restricting member. In this configuration, an abutting portion 47 projecting radially outward is provided on the negative x direction side of the movable portion 40 at the end portion 36 of the piston 3 . The biasing member 46 applies a biasing force to the movable part 40 in the negative x direction and abuts it against the abutting part 47, whereby the movable part 40 moves relative to the piston 3 in the piston moving direction (positive x direction). regulate what you do. Further, by setting the parameters such as the spring constant of the biasing member 46 so that the biasing force of the biasing member 46 is approximately equal to the pressure with which the piston 3 can normally move, the gas chamber C When the internal pressure exceeds a predetermined value, the movable portion 40 is allowed to move in the moving direction of the piston 3 in the positive x direction against the biasing force of the biasing member 46, thereby releasing the regulation of the movable portion 40. .

FIG. 12 is a longitudinal sectional view around the piston 3 according to the third modification of the first embodiment. As shown in FIG. 12, the restricting member may be configured to use a projection 48 that protrudes radially inward from the inner peripheral surface of the movable portion 40 and extends along the circumferential direction of the inner peripheral surface. In this configuration, the projection 48 hits the end surface 37 (pressure receiving surface) of the end portion 36 of the piston 3 on the negative x direction side, whereby the movable portion 40 moves relative to the piston 3 in the piston moving direction (positive x direction). restrict movement. Further, when the internal pressure of the gas chamber C exceeds a predetermined value, the protrusion 48 is sheared by the end portion 36 of the piston 3, thereby releasing the regulation of the movable portion 40. As shown in FIG.

In the first embodiment, the member to be retracted of the pretensioner 1 is the webbing 101 (lap belt 101a), but the member to be retracted may be the buckle 107 .

[Second embodiment]
A second embodiment will be described with reference to FIGS. 13 to 19. FIG. FIG. 13 is a perspective view of a pretensioner 1A according to the second embodiment. FIG. 14 is a longitudinal sectional view of the pretensioner 1A. FIG. 15 is an exploded perspective view of elements accommodated inside the cylinder 4 of the pretensioner 1B according to the second embodiment.

As shown in FIG. 13, in the second embodiment, a buckle pretensioner in which the member to be retracted is a buckle 107 is exemplified as a pretensioner 1A. Further, as shown in FIG. 14, in the pretensioner 1A of the second embodiment, unlike the first embodiment in which the gas generator 5 is installed on the cylinder 4 side (fixed side), the gas generator 5 is installed on the piston 3 side. (movable side).

As shown in FIGS. 14 and 15 , the gas generator 5 is arranged inside the cylinder 4 on the positive x direction side of the piston 3 , that is, on the moving direction side of the piston 3 .

Unlike the first embodiment, the piston 3 has a shape that does not have an end portion 36 on the x-negative direction side or a connection portion 39 . The outer peripheral surface of the piston 3 is provided with a tapered surface 35 as in the first embodiment, and balls 32 and ball rings 33 are arranged thereon.

The wire end 51 connected to the end of the wire 2 on the cylinder 4 side is longer than the wire end 21 of the first embodiment, and approximately half of the wire end on the negative x direction side is inserted into the communication hole of the piston 3 to extend the negative x direction. A side end protrudes radially outward and is connected to the piston 3 . A cylindrical piston body 52 is arranged on the positive x direction side of the piston 3 . The piston body 52 accommodates the wire end 51 inside and is connected to the piston 3 and the wire 2 via the wire end 51 .

The piston body 52 has an opening on the positive x direction side, through which the gas generator 5 is accommodated in the piston body 52, and a cylindrical lid member 53 is connected to the piston body 52 from the positive x direction side. The gas generator 5 is installed inside the piston body 52 by . Moreover, the outer diameter of the lid member 53 is substantially the same as the inner diameter of the cylinder 4 , and the lid member 53 is formed to be slidable inside the cylinder 4 . An O-ring 54 is fitted to the outer peripheral surface of the lid member 53 to improve airtightness.

The gas generator 5 is installed so as to inject gas from the tip on the negative x direction side. Further, the piston body 52 is provided with one or a plurality of (two in the example of FIG. 14) communicating holes 52a and 52b for communicating the outer peripheral surface and the inner peripheral surface. The gas injected into the piston body 52 from the gas generator 5 is injected into the cylinder 4 through the communication holes 52a and 52b of the piston body 52, thereby moving the piston 3 and the piston body 52 in the positive x direction. do.

The configuration for installing the gas generator 5 on the side of the piston 3 (movable side) may be other than the configuration including the piston body 52, the wire end 51, the lid member 53, etc. illustrated in FIGS.

In addition, in the second embodiment, a communication hole 59 that communicates the inside and the outside of the cylinder 4 is provided at a position on the negative x direction side of the piston 3 of the cylinder 4 . One or a plurality of communication holes 59 are provided along the circumferential direction of the cylinder 4 at predetermined positions in the x direction, for example. A cylindrical sealing member 55 for sealing the communication hole 59 is arranged inside the cylinder 4 at a position where the communication hole 59 opens. The outer diameter of the sealing member 55 is substantially the same as the inner diameter of the cylinder 4 , and the outer peripheral surface of the sealing member 55 contacts the inner peripheral surface of the cylinder 4 including the communication hole 59 to block the communication hole 59 . can be done. The sealing member 55 has a circular end surface 55a on the positive x direction side, and a hole 55b through which the wire 2 is passed is provided in the center of the end surface in the radial direction.

A wire guide 57 is arranged on the positive x direction side of the sealing member 55 . The wire guide 57 also has an outer diameter substantially equal to the inner diameter of the cylinder 4, and is provided with a hole 57a through which the wire 2 is passed in the center in the radial direction. The end face of the wire guide 57 on the x negative direction side is in contact with the end face 55 a of the sealing member 55 .

A spacer 58 is arranged between the wire guide 57 and the piston 3 . Before the pretensioner 1</b>A is activated, the end face of the piston 3 on the negative x direction side is in contact with the spacer 58 . Also, the spacer 58 is fitted to the wire guide 57 .

A ring member 56 is arranged on the x-negative direction side of the sealing member 55 . The ring member 56 has an outer diameter substantially equal to the inner diameter of the cylinder 4, and has one or a plurality of (three in the example of FIG. 15) protrusions 56a protruding radially outward. The cylinder 4 is provided with a concave portion 60 recessed from the inner peripheral surface of the cylinder 4 on the negative x direction side of the communication hole 59 . The recess 60 is provided at a position on the inner peripheral surface of the cylinder corresponding to the position in the circumferential direction of the projection 56 a of the ring member 56 . The ring member 56 is installed with the protrusion 56a fitted into the recess 60 on the inner peripheral surface of the cylinder 4, thereby fixing the position in the cylinder 4 in the x direction. Note that the recess 60 may be a hole that communicates with the outside.

The wire 2 enters the cylinder 4 from the housing 6 , passes through the ring member 56 , the sealing member 55 , the wire guide 57 and the spacer 58 , passes through the piston 3 and is fixed to the wire end 51 .

Thus, in the second embodiment, the ring member 56, the sealing member 55, the wire guide 57, and the spacer 58 are arranged on the opposite side of the moving direction of the piston 3, are slidable with respect to the cylinder 4, It functions as a guide member 70'' that guides the piston 3 through the wire 2. This guide member 70 functions as "a pressure receiving member arranged facing the gas chamber C and receiving the pressure of the high pressure gas from the gas generator 5".

Note that the guide member 70 may have a configuration other than the ring member 56, the sealing member 55, the wire guide 57, and the spacer 58 of the present embodiment. For example, ring member 56, sealing member 55, wire guide 57, and spacer 58 may be formed together as a single piece, or a portion of ring member 56, sealing member 55, wire guide 57, and spacer 58 may be formed together. It's okay.

In the present embodiment, the protrusion 56a of the ring member 56 is "a protrusion protruding radially outward from the guide member 70 in the cylinder 4" and "a pressure-receiving member (a guide member 70), and when the internal pressure of the gas chamber C exceeds a predetermined value larger than the pressure at which the piston 3 can normally move, the regulation of the pressure receiving member is released to increase the volume of the gas chamber C. function as a regulating member that allows the pressure receiving member to move in an increasing direction. The protrusions 56a are fitted into recesses 60 provided on the inner peripheral surface of the cylinder 4 to restrict the movement of the guide member 70 (the ring member 56, the sealing member 55, the wire guide 57, and the spacer 58), and to prevent the gas chamber from moving. When the internal pressure of C exceeds a predetermined value, the guide member 70 is released from the restraint by being sheared by the concave portion 60 .

16 to 19, the procedure of internal pressure increase suppression processing of the pretensioner 1A according to the second embodiment will be described.

FIG. 16 is a diagram showing a first procedure of internal pressure increase suppression processing according to the second embodiment. As shown in FIG. 16, before the pretensioner 1A is activated, the space between the piston 3 and the wire guide 57 and the space between the piston main body 52 and the outer peripheral surfaces of the piston 3 and the inner peripheral surface of the cylinder 4 are formed. , can also be expressed as a gas chamber C that can be filled with high-pressure gas from the gas generator 5 . When there is an opportunity to activate the pretensioner 1, such as during a vehicle collision, the gas generator 5 ejects high pressure gas into the gas chamber C through the communication holes 52a and 52b. The high-pressure gas ejected into the gas chamber C presses the wire guide 57 and the spacer 58 in the negative x direction.

During normal operation of the piston 3, the high-pressure gas jetted into the gas chamber C presses the wire guide 57 and moves the piston 3 and the piston body 52 away from the housing 6 (positive x direction) from the position shown in FIG. Let As a result, the distance between the wire guide 57 and the piston 3 is increased and the volume of the gas chamber C is expanded, so that the increase in gas pressure in the gas chamber C is suppressed. At this time, since the protrusion 56a of the ring member 56 is fitted into the recess 60 of the cylinder 4, the guide member 70 (the ring member 56, the sealing member 55, the wire guide 57, and the spacer 58) is positioned inside the cylinder 4 in the x direction. movement is restricted.

On the other hand, it becomes difficult for the piston 3 and the piston body 52 to move within the cylinder 4, for example, when the piston 3 and the piston body 52 cannot fully pull the wire 2 due to an excessive force being applied to the member to be retracted. A situation that is fixed in the In this state, when high-pressure gas is injected from the gas generator 5 to operate the pretensioner 1A, in the conventional pretensioner, the piston 3 and the piston body 52 do not move from the positions shown in FIG. Also, the movement of the piston body 52 in the positive x direction is slow, and the increase in the volume of the gas chamber C cannot catch up with the pressure increase in the gas chamber C, and the pressure in the gas chamber C rises more than usual, causing a problem with the pretensioner. There is fear.

FIG. 17 is a diagram showing a second procedure of internal pressure increase suppression processing according to the second embodiment. As shown in FIG. 17, in the present embodiment, when the pressure in the gas chamber C rises above normal, the pressing force with which the high-pressure gas in the gas chamber C presses the wire guide 57 in the negative x direction is , is transmitted to the ring member 56 via the sealing member 55 . Then, the projection 56a of the ring member 56 is sheared by the recess 60 and the inner peripheral surface of the cylinder 4 which are fitted. With such a share structure, the regulation of the guide member 70 is released, and the ring member 56 is no longer fixed to the cylinder 4 . This allows the guide member 70 to move relative to the piston 3 in the negative x direction.

FIG. 18 is a diagram showing the third procedure of the internal pressure increase suppression process of the second embodiment. As shown in FIG. 18, when the protrusion 56a is sheared, the guide member 70 is pushed in the negative x direction by the high pressure gas in the gas chamber C, and moves relative to the piston 3 in the negative x direction. . As a result, as shown in FIG. 18, the volume of the gas chamber C increases by the movement of the guide member 70, so that the pressure in the gas chamber C decreases by the increase in volume, and the internal pressure of the gas chamber C returns to normal. can be reduced from an elevated state.

FIG. 19 is a diagram showing the fourth procedure of the internal pressure increase suppression process of the second embodiment. As shown in FIG. 19, the ring member 56 finally moves to the end position of the cylinder 4 on the negative x direction side. At this time, since the sealing member 55 and the wire guide 57 are also moved in the negative x direction from the position of the communicating hole 59, the communicating hole 59 of the cylinder 4 is exposed in the gas chamber C. The high pressure gas in the gas chamber C is discharged to the outside of the cylinder 4 through this communication hole 59 . As a result, the pressure in the gas chamber C can be further reduced, and the internal pressure in the gas chamber C can be reliably reduced from a state higher than normal.

In the second embodiment, the buckle pretensioner in which the member to be retracted of the pretensioner 1A is the buckle 107 was illustrated, but the member to be retracted may be the webbing 101 (the lap belt 101a). In this case the pretensioner also functions as a belt anchor.

In the second embodiment, the gas generator 5 is installed on the piston 3 side (movable side). It may be configured to be installed.

The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples by those skilled in the art are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element included in each specific example described above and its arrangement, conditions, shape, etc. are not limited to those illustrated and can be changed as appropriate. As long as there is no technical contradiction, the combination of the elements included in the specific examples described above can be changed as appropriate.

Reference Signs List 1, 1A Pretensioner 2 Wire 3 Piston 4 Cylinder 5 Gas generator 38 Protrusion (regulating member)
40 movable part (pressure receiving member)
45 plate material (restriction member)
46 biasing member (regulating member)
48 projection (restriction member)
55 sealing member (induction member, pressure receiving member)
56 ring member (induction member, pressure receiving member)
56a projection (restriction member)
57 Wire guide (guide member, pressure receiving member)
58 spacer (induction member, pressure receiving member)
59 communication hole 100 seatbelt device 101 webbing C gas chamber

Claims (11)

A pretensioner that is actuated in an emergency and pulls in a member to be retracted to increase restraining force of the webbing on a vehicle occupant,
a wire having one end connected to the member to be drawn;
a piston connected to the other end of the wire;
a cylinder that slidably accommodates the piston;
a gas generator that supplies gas to the gas chamber in the cylinder for operating the piston in the direction in which the wire is drawn;
a pressure receiving member arranged facing the gas chamber;
a restricting member that restricts movement of the pressure receiving member in a direction to increase the volume of the gas chamber;
with
The regulating member releases the regulation of the pressure receiving member when the internal pressure of the gas chamber exceeds a predetermined value higher than the pressure at which the piston can normally move, and the pressure receiving member increases the volume of the gas chamber. the member is movable,
Pretensioner. As the pressure receiving member, a movable portion provided radially outside the pressure receiving surface of the piston and capable of relative movement with respect to the piston,
The regulating member regulates the movement of the movable portion in the moving direction of the piston, releases the regulation of the movable portion when the internal pressure of the gas chamber exceeds the predetermined value, and releases the regulating member in the moving direction of the piston. The movable part is relatively movable with respect to the piston,
The pretensioner according to claim 1. The regulating member is a protrusion that protrudes radially outward from the outer peripheral surface of the piston and extends along the circumferential direction of the outer peripheral surface,
The projection regulates the movement of the movable portion by receiving the end face of the movable portion,
When the internal pressure of the gas chamber exceeds the predetermined value, the movable portion is sheared by the movable portion to release the regulation of the movable portion.
The pretensioner according to claim 2. The regulating member is a plurality of plate members protruding radially outward from the outer peripheral surface of the piston and arranged along the circumferential direction of the outer peripheral surface,
The plate member restricts movement of the movable portion by receiving an end face of the movable portion,
When the internal pressure of the gas chamber exceeds the predetermined value, the movable portion is bent by the movable portion to release the regulation of the movable portion.
The pretensioner according to claim 2. the regulating member is a biasing member that biases the movable portion in a direction opposite to the moving direction of the piston;
The biasing member restricts movement of the movable part by applying a biasing force to the movable part,
When the internal pressure of the gas chamber exceeds the predetermined value, the movable portion is allowed to move in the moving direction of the piston against the biasing force of the biasing member, thereby releasing the restriction on the movable portion. ,
The pretensioner according to claim 2. the regulating member is a protrusion that protrudes radially inward from an inner peripheral surface of the movable portion and extends along the circumferential direction of the inner peripheral surface;
The projection abuts against the pressure receiving surface of the piston to restrict movement of the movable portion, and
The protrusion releases the restriction on the movable portion by being sheared by the piston when the internal pressure of the gas chamber exceeds the predetermined value.
The pretensioner according to claim 2. The outer peripheral surface of the piston is formed so that a gap is formed between the piston and the movable portion at a position where the movable portion faces the movable portion when the restriction by the restriction member is released and the movable portion moves relative to the piston.
The pretensioner according to any one of claims 2-6. As the pressure receiving member, a guide member arranged on the side opposite to the movement direction of the piston, slidable with respect to the cylinder, and guided to the piston through the wire,
the gas chamber is formed between the guide member and the piston;
The regulating member regulates movement of the guide member in a direction away from the piston, and releases the regulation of the guide member to move away from the piston when the internal pressure of the gas chamber exceeds the predetermined value. and the guide member is movable relative to the piston,
The pretensioner according to claim 1. The regulating member is a protrusion that protrudes radially outward from the guide member in the cylinder,
The projection restricts the movement of the guide member by fitting into a recess provided on the inner peripheral surface of the cylinder,
When the internal pressure of the gas chamber exceeds the predetermined value, the restriction of the guide member is released by being sheared by the recess.
A pretensioner according to claim 8 . A communication hole is provided to communicate the inside and the outside of the cylinder,
The communication hole is sealed so as not to be exposed in the gas chamber when the restriction member restricts the movement of the guide member, and when the restriction by the restriction member is released and the guide member moves relatively. exposing to the gas chamber and discharging high pressure gas in the gas chamber;
A pretensioner according to claim 9 . A seatbelt device comprising the pretensioner according to any one of claims 1 to 10.

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