JP2022185189A - Pretensioner, retractor, and seat belt device - Google Patents

Abstract

To provide a pretensioner, a retractor, and a seat belt device, which can relax constraint conditions for designing the pretensioner while suppressing discharge of operation gas.SOLUTION: A power transmission device 32 of a pretensioner 3 includes: a piston 32d which is arranged between a gas generator 32c and a power transmission member 32a; and a restraining section 32g which restrains the piston 32d formed in a guide member 32b. The piston 32d has through holes (first through hole 32r and second through hole 32s) communicating front and back spaces with each other and guide flow passages (first groove 321c and second groove 321d) for guiding operation gas to the through holes. The guide flow passages have at least a bent section (first bent section 321e and second bent section 321f).SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a pretensioner, a retractor, and a seatbelt device, and more particularly to a pretensioner, a retractor, and a seatbelt device suitable for a configuration in which a power transmission member is moved by a gas generator.

2. Description of the Related Art A vehicle such as an automobile is generally provided with a seat belt device for restraining an occupant in a seat having a seat on which the occupant sits and a backrest portion positioned on the back of the occupant. Such a seatbelt device includes a webbing that restrains the occupant, a retractor that winds up the webbing, a buckle arranged on the side of the seat, and a tongue arranged on the webbing, and the tongue is fitted to the buckle. The webbing restrains the occupant to the seat. Moreover, the retractor generally has a pretensioner that removes slack in the webbing in an emergency such as a vehicle collision.

Such a pretensioner includes a power transmission member that rotates a spool that winds up webbing, an elongated cylindrical pipe (guide member) that guides the power transmission member, and a working gas supplied to the pipe to generate power. and a gas generator that applies a driving force to the transmission member (see, for example, Patent Document 1).

As described in Patent Document 1, when the power transmission member is completely discharged from the pipe when the pretensioner is actuated, the working gas may be released to the outside, generating noise and smoke. Therefore, Japanese Patent Laid-Open No. 2002-200002 proposes various means for closing the final section of the pipe with a power transmission member (mass or drive cylinder) so that the working gas is not discharged to the outside of the pipe.

By the way, in recent years, research and development have been made on using an elongated rod-shaped part made of resin as a power transmission member of a pretensioner. For example, Patent Document 2 discloses a configuration in which a piston provided with a reduction element and a sealing element contacts a stopper formed inside a pipe, and the piston is stopped within the pipe by plastically deforming the stopper with the reduction element. disclosed.

Japanese Patent No. 4654204 Japanese Patent Publication No. 2016-523198

The inventions described in Patent Document 1 and Patent Document 2 are both configured to completely seal a pipe by a moving body (mass body, piston, etc.) that moves along the pipe. Since the pretensioner needs to wind up the webbing instantaneously (for example, within one second), the kinetic energy of the moving body tends to increase inevitably.

Therefore, in order to stop the moving body completely within the pipe, it is necessary to design a structure capable of resisting the kinetic energy of the moving body when it collides with the stopper. There is a problem of severity.

SUMMARY OF THE INVENTION The present invention has been devised in view of such problems, and aims to provide a pretensioner, a retractor, and a seatbelt device that can reduce the restrictions on the design of the pretensioner while suppressing the release of working gas. aim.

According to the present invention, in a pretensioner including a ring gear connected to a spool for winding webbing that restrains an occupant, and a power transmission device that transmits power to the ring gear in an emergency, the power transmission device a power transmission member for transmitting power to the ring gear; a cylindrical guide member for guiding the power transmission member to the ring gear; a gas generator for supplying working gas to the interior of the guide member; a piston disposed between the gas generator and the power transmission member; a seal member that seals a gap between the piston and the guide member; and a restraining portion that is formed in the guide member and restrains the piston. wherein the piston includes a through hole that communicates the front and rear spaces, and a guide channel that guides the working gas to the through hole, the guide channel having at least one bend. There is provided a pretensioner characterized by:

The guide channel may be formed by a plug attached to the piston.

The guide channel may be formed by a gap between a groove formed in the outer surface of the plug and the inner surface of the piston.

The guide channel may be formed by a pore formed in the axial direction of the plug.

The plug may include a protruding portion formed to be insertable into the through hole with a predetermined gap.

The piston may include a head portion having the through hole, and a cylindrical trunk portion formed behind the head portion.

The through-hole may be configured to be sealed by a member positioned in front of the piston until it reaches the restraining portion.

The through-hole may be configured in multiple stages with a plurality of holes having different diameters.

The power transmission device may include an elastic body arranged between the piston and the power transmission member and configured to be able to pass through the restraint portion.

The power transmission device may include a resin protection member disposed between the elastic body and the power transmission member to protect the elastic body.

The power transmission member may have a resin rod shape.

The power transmission member may have a spherical rear end.

The restricting portion may be a constricted portion formed in a part of the guide member.

Further, according to the present invention, there is provided a retractor comprising the pretensioner having the above configuration.

Further, according to the present invention, there is provided a seatbelt device having a retractor having the pretensioner having the configuration described above.

According to the pretensioner, retractor, and seatbelt device according to the present invention described above, the through hole and the guide channel are formed in the piston. The working gas can be released from, and the kinetic energy of the piston can be reduced.

In addition, by forming the curved portion in the guide channel, it is possible to inhibit the straightness of the working gas when it is discharged, and it is possible to lower the temperature of the working gas. Therefore, according to the present invention, restrictions on the design of the pretensioner can be relaxed while minimizing the release of working gas.

1 is an exploded view of parts showing a retractor according to an embodiment of the present invention; FIG. FIG. 2 is an enlarged view of the plug shown in FIG. 1, where (A) is a perspective view, (B) is a cross-sectional view including the groove when attached, and (C) is a cross-sectional view not including the groove when attached. . It is a perspective view which shows the modification of a plug, (A) has shown the 1st modification, (B) has shown the 2nd modification. It is sectional drawing which shows the modification of a piston, (A) has shown the 1st modification, (B) has shown the 2nd modification, (C) has shown the 3rd modification. It is sectional drawing which shows the modification of a plug, (A) has shown the 3rd modification, (B) has shown the 4th modification, (C) has shown the 5th modification. FIG. 2 is a conceptual diagram illustrating the action of the piston shown in FIG. 1, where (A) is the state before the gas generator is activated, (B) is the state after the gas generator is activated, and (C) is the piston (D) shows the state in which the working gas has been released from the piston. FIG. 2 is a cross-sectional view showing the operation of the pretensioner shown in FIG. 1, where (A) is the state before operation, (B) is the state in which the piston has reached the restraint portion, and (C) is the state in which the working gas is released from the piston. , is shown. FIG. 2 is a conceptual diagram showing a modification of the power transmission device shown in FIG. 1, where (A) is the state before the gas generator is activated, (B) is the state where the elastic body has reached the restraining portion, and (C) is the (D) shows a state in which the elastic body has passed through the restraining portion, and a state in which the working gas has been released from the piston. 1 is an overall configuration diagram showing a seatbelt device according to an embodiment of the present invention; FIG.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 9. FIG. Here, FIG. 1 is an exploded view of parts showing a retractor according to one embodiment of the present invention. 2 is an enlarged view of the plug shown in FIG. 1, (A) is a perspective view, (B) is a cross-sectional view including the groove when attached, (C) is a cross-sectional view not including the groove when attached, is shown.

A retractor 1 according to an embodiment of the present invention includes, as shown in FIG. 1, a spool 2 that winds up a webbing that restrains an occupant, a pretensioner 3 that winds up the webbing to remove slack in an emergency, The pretensioner 3 includes a ring gear 31 connected to the spool 2 and a power transmission device 32 that transmits power to the ring gear 31 in an emergency. In addition, in FIG. 1, the illustration of the webbing is omitted.

The power transmission device 32 includes, for example, a resin rod-shaped power transmission member 32a that transmits power to the ring gear 31, a cylindrical guide member 32b that guides the power transmission member 32a to the ring gear 31, and a guide member A gas generator 32c that supplies working gas to the inside of 32b, a piston 32d that is arranged between the gas generator 32c and the power transmission member 32a, and a seal member 32e that seals the gap between the piston 32d and the guide member. , a spacer 32f for filling a gap between the gas generator 32c and the piston 32d, a restraining portion 32g formed in the guide member 32b for restraining the piston 32d, and a power transmission member 32a when the power transmission member 32a and the ring gear 31 start meshing. and a guide member 32h that supports the

The spool 2 is a winding drum for winding webbing, and is rotatably housed in a base frame 11 that forms the framework of the retractor 1 . The base frame 11 has, for example, a first end surface 111 and a second end surface 112 facing each other, and a side surface 113 connecting these end surfaces. The base frame 11 may include a tie plate 114 facing the side surfaces 113 and connected to the first end surface 111 and the second end surface 112 . Also, a bracket 115 for fixing the base frame 11 may be fixed to the side surface 113 .

Further, for example, the spring unit 4 is arranged on the first end surface 111 side, and the pretensioner 3 and the lock mechanism 5 are arranged on the second end surface 112 side. The arrangement of the spring unit 4, pretensioner 3, lock mechanism 5, etc. is not limited to the illustrated configuration.

The first end face 111 of the base frame 11 is formed with an opening 111a through which the shaft of the spool 2 is inserted, and the second end face 112 of the base frame 11 is provided with a pawl (not shown) of the lock mechanism 5. ) are formed with internal teeth engagable therewith. A part of the pretensioner 3 (for example, the ring gear 31 ) is arranged inside the second end surface 112 of the base frame 11 . Further, the lock mechanism 5 is arranged outside the second end surface 112 of the base frame 11 and is accommodated in the retainer cover 51 .

A vehicle sensor 6 for detecting sudden deceleration or inclination of the vehicle body may be arranged on the retainer cover 51 . The vehicle sensor 6 has, for example, a spherical mass body (not shown) and a sensor lever 61 that is swung by movement of the mass body. The vehicle sensor 6 may be fixed by being fitted into an opening 112b formed in the second end face 112 of the base frame 11 .

The spool 2 may have a cavity in the center and a torsion bar 21 forming an axis may be inserted therethrough. The torsion bar 21 has a first end connected to a locking base 52 of the locking mechanism 5 connected to the end of the spool 2 and a second end fixed to the spool 2 and a spring core of the spring unit 4 . It is connected to the. Therefore, the spool 2 is connected to the spring unit 4 via the locking base 52 and the torsion bar 21, and is urged in the webbing winding direction by the spiral spring housed in the spring unit 4. As shown in FIG.

The means for applying the winding force to the spool 2 is not limited to the spring unit 4, and other means using an electric motor or the like may be used.

The locking base 52 has a pawl (not shown) arranged so as to be retractable from its side surface. When the locking mechanism 5 is actuated, the pawl protrudes from the side surface of the locking base 52 and is engaged with the internal teeth formed in the opening 112a of the base frame 11, thereby restraining the rotation of the locking base 52 in the webbing pull-out direction. do.

Therefore, even if a load is applied in the webbing pull-out direction while the lock mechanism 5 is actuated, the spool 2 can be held in a non-rotating state until a load equal to or greater than the threshold is applied to the torsion bar 21. can. When a load equal to or greater than a threshold is applied to the torsion bar 21, the torsion bar 21 is twisted, causing the spool 2 to relatively rotate and the webbing to be pulled out.

The lock mechanism 5 also includes a lock gear 53 arranged adjacent to the locking base 52 . The lock gear 53 has a flywheel (not shown) which is arranged to be able to swing. engages the internal teeth. Also, when the vehicle sensor 6 is actuated, the sensor lever 61 engages with external teeth formed on the side surface of the lock gear 53 .

Thus, the rotation of the lock gear 53 is restricted by the operation of the flywheel or vehicle sensor 6 . When the rotation of the lock gear 53 is restricted, relative rotation occurs between the locking base 52 and the lock gear 53 , and the pawl protrudes from the side surface of the locking base 52 with this relative rotation.

It should be noted that the lock mechanism 5 is not limited to the configuration shown in the drawings, and can be used by arbitrarily selecting from various conventional configurations. Further, instead of the torsion bar 21, the spool 2 may be provided with an impact absorbing mechanism constituted by a combination of a shaft and a wire-like or plate-like plastic deformation member.

The pretensioner 3 includes, for example, a ring gear 31 having engagement teeth on its outer periphery, a power transmission device 32, a pretensioner cover 33 that stores the ring gear 31, and a pin 34 that restricts movement of the power transmission member 32a. , is equipped with Although not shown, the pretensioner 3 may include a guide spacer inside the pretensioner cover 33 to form a movement space for the power transmission member 32a.

The ring gear 31 is arranged so as to be located in a space formed between the pretensioner cover 33 and the base frame 11 (second end face 112). Note that the ring gear 31 may also be referred to as a driving wheel or rotating member.

The pretensioner cover 33 is arranged, for example, inside the second end surface 112 of the base frame 11 . Also, the pretensioner cover 33 is fixed to the base frame 11 (second end surface 112) together with the guide member 32b or directly by means of fasteners 35, for example.

In the power transmission device 32, for example, a gas generator 32c, a spacer 32f, a seal member 32e, a piston 32d, and a power transmission member 32a are arranged in this order from the rear end to the front end of a guide member 32b formed of a cylindrical pipe. It is The power transmission member 32a, the seal member 32e, and the piston 32d are accommodated within the guide member 32b, and are moved within the guide member 32b by working gas generated from a gas generator 32c arranged at the rear end of the guide member 32b. .

The power transmission member 32a is formed in a rod shape having a linear shape before it is inserted into the guide member 32b. As shown, it conforms to the shape of guide member 32b and is received within guide member 32b. The power transmission member 32a has, for example, a spherical rear end (the end on the side of the piston 32d). Note that the rear end of the power transmission member 32a may be planar.

The guide member 32b, for example, as shown in FIG. It has a curved shape extending downward from the upper part inside the part.

A guide member 32h is arranged at the tip of the guide member 32b. An opening 32i is formed at the tip of the guide member 32b to release the power transmission member 32a guided by the guide member 32h from the guide member 32b into the space formed by the pretensioner cover 33. As shown in FIG. The guide member 32b also has a notch 32j communicating from the tip of the guide member 32b to the opening 32i, and an insertion hole 32k through which the fastener 35 formed below the opening 32i is inserted.

The opening 32i is formed at a position adjacent to the guide member 32h of the guide member 32b, and constitutes the outlet of the power transmission member 32a. The notch 32j has a function of positioning the guide member 32h in the circumferential direction, and the projection of the guide member 32h is inserted into the notch 32j.

The guide member 32h has, for example, a substantially cylindrical shape that can be inserted into the distal end of the guide member 32b, and a sliding surface 32m that guides the power transmission member 32a to the opening 32i is obliquely formed at the end on the insertion side. It is The sliding surface 32m may have a curved groove shape along the outer shape of the power transmission member 32a.

A notch portion 32n through which the fastener 35 is inserted is formed in the lower portion of the sliding surface 32m. A bolt hole 32o (see FIG. 7) for screwing a bolt (not shown) for fixing the guide member 32h and the guide member 32b to the base frame 11 (side surface 113) is formed on the rear side of the sliding surface 32m. It is

The restraining portion 32g is a portion that allows the power transmission member 32a to pass through and stops the piston 32d within the guide member 32b. The restricting portion 32g is, for example, a constricted portion formed in a part of the guide member 32b, and forms a convex portion that protrudes inside the guide member 32b. 32 g of restraint parts are formed by pressing a part of outer periphery of the guide member 32b, for example. Note that the restraining portion 32g may be formed by fixing another component such as a pin to the guide member 32b.

The spacer 32f is also a component that fills the gap between the gas generator 32c and the piston 32d that is created when the pretensioner 3 is assembled. By arranging the spacer 32f, it is possible to reduce noise generated by the movement of the piston 32d during normal operation. The spacer 32f is composed of, for example, a metallic coil spring.

The piston 32d, for example, as shown in FIGS. 1 and 2B, has a substantially spherical head portion 32p and a substantially cylindrical body portion 32q formed behind (flat side) the head portion 32p. And, it is a metal part configured by.

The head 32p has an outer diameter larger than the inner diameter of the restraining portion 32g. A first through-hole 32r and a second through-hole 32s are formed in the center of the head 32p to communicate with the space in front of and behind the piston 32d. The first through hole 32r is formed to have a smaller diameter than the second through hole 32s. In this manner, the through-hole may be configured in multiple stages with a plurality of holes having different diameters.

The first through hole 32r is configured to be sealed by the rear end of a member (for example, the power transmission member 32a) located in front of the piston 32d until the piston 32d reaches the restraint portion 32g. Also, the amount of the working gas released can be controlled by the size of the diameter of the first through hole 32r. Further, by increasing the diameter of the second through hole 32s, the weight of the piston 32d can be reduced.

A seal member 32e is arranged on the outer periphery of the trunk portion 32q. The seal member 32e is, for example, a substantially cylindrical elastomer component. The outer diameter of the seal member 32e is, for example, slightly larger than the inner diameter of the guide member 32b, and is press-fitted into the guide member 32b. Therefore, the seal member 32e moves while maintaining contact with the inner surface of the guide member 32b by the pressure of the working gas supplied from the gas generator 32c.

Moreover, the inner diameter of the trunk|drum 32q is formed more largely than the diameter of 32 s of 2nd through-holes, for example. For example, the plug 321 shown in FIG. 2(A) is press-fitted into the trunk portion 32q. In addition, the trunk|drum 32q is not limited to cylindrical shape, A rectangular cylindrical shape may be sufficient.

The plug 321 includes, for example, a shaft portion 321a inserted into the trunk portion 32q, and a flange portion 321b arranged on the rear end side of the trunk portion 32q. A first groove 321c is formed along the axial direction on the outer surface of the shaft portion 321a. A second groove 321d communicating with the first groove 321c is formed on the surface of the flange portion 321b on the side of the piston 32d.

When the plug 321 is attached, as shown in FIG. 2(C), the portion that seals the inner surface of the barrel portion 32q of the piston 32d and as shown in FIG. A portion forming a space communicating with the second through hole 32s is formed on the inner surface. Therefore, the first groove 321c and the second groove 321d form a guide flow path that guides the working gas to the through hole.

As shown in FIG. 2B, the guide flow path is formed between a stepped portion formed between the inner surface of the body portion 32q and the second through hole 32s and the tip portion of the shaft portion 321a. A first bent portion 321e and a second bent portion 321f formed between the first groove 321c and the second groove 321d are provided.

By attaching the plug 321 to the piston 32d in this way, it is possible to form a bent guide passage and prevent the working gas from passing straight through the piston 32d. By forming such a guide flow path, the resistance of the working gas when it passes through the piston 32d is increased, and the time during which the working gas contacts the piston 32d is lengthened. It can be lowered by action.

The route of the guide flow path is not limited to the illustrated configuration, and for example, the plug 321 may be configured integrally with the piston 32d, or the plug 321 and the piston 32d may be separated at another portion. The first groove 321c and the second groove 321d may be twisted in the circumferential direction.

Further, in the present embodiment, a pair of guide channels (the first groove 321c and the second groove 321d) are arranged at opposing positions, but the number of guide channels may be one, or three or more. There may be. When forming a plurality of guide channels, it is preferable to arrange them at equal intervals in the circumferential direction.

Here, FIG. 3 is a perspective view showing a modification of the plug, where (A) shows the first modification and (B) shows the second modification. A plug 321 shown in FIG. 3(A) is configured by omitting the flange portion 321b of the plug 321 shown in FIG. 2(A) and having only a shaft portion 321a. With such a configuration as well, at least one bent portion (first bent portion 321e) can be formed by the first groove 321c.

The plug 321 shown in FIG. 3B has a plurality of C-shaped projections 321g arranged in the circumferential direction of the shaft portion 321a. The open portions of adjacent convex portions 321g are arranged so as not to be adjacent to each other. When the plug 321 is attached, the convex portion 321g constitutes a groove (guiding channel) formed along the axial direction and the circumferential direction between itself and the inner surface of the body portion 32q.

The shape of the convex portion 321g is not limited to the C shape, and may be an arc shape forming a plurality of openings in the circumferential direction, or a spiral shape extending to both ends of the plug 321. may Further, a flange portion 321b may be formed on the plug 321 shown in FIG. 3(B).

Here, FIG. 4 is a cross-sectional view showing modifications of the piston, where (A) shows the first modification, (B) shows the second modification, and (C) shows the third modification. A piston 32d shown in FIG. 4A has a through hole formed by one through hole 32t. A single through-hole may be provided in this manner, or a plurality of through-holes may be provided as in the above-described embodiment.

A piston 32d shown in FIG. 4B has a recess 32u formed at the tip of a head 32p. With such a configuration, it is possible to easily match the spherical shape of the power transmission member 32a. A piston 32d shown in FIG. 4C has a hollow portion 32v formed in the second through hole 32s. With such a configuration, the weight of the piston 32d can be reduced.

Here, FIG. 5 is a sectional view showing modifications of the plug, where (A) shows the third modification, (B) shows the fourth modification, and (C) shows the fifth modification. A plug 321 shown in FIG. 5(A) has a protrusion 321h formed at the tip of the shaft portion 321a of the plug 321 shown in FIG. 2(B). The protruding portion 321h is a substantially cylindrical portion formed so as to be insertable into the second through hole 32s of the piston 32d with a predetermined gap therebetween.

With such a configuration, a part of the guide channel can be formed by the gap between the projecting portion 321h and the second through hole 32s. Further, the stepped portion formed between the first through hole 32r and the second through hole 32s of the piston 32d can form the third bent portion 321i. Therefore, by adopting the plug 321 of the third modified example, the temperature of the working gas can be further lowered.

A plug 321 shown in FIG. 5(B) has a shaft portion 321a in the axial direction instead of the first groove 321c and the second groove 321d formed in the plug 321 of the third modification shown in FIG. 5(A). A guide flow path is formed by the narrow hole 321j extending inward. The hole 321j is formed to pass through the stepped portion between the shaft portion 321a and the projecting portion 321h.

That is, the pore 321j is a through hole having a diameter smaller than the radial width of the stepped portion between the shaft portion 321a and the projecting portion 321h. According to the configuration of the fourth modification, it is possible to form the first bent portion 321e and the third bent portion 321i in the guide channel. The pore 321j may be one or more. In addition, the hole 321j is formed at a position where the working gas can be discharged toward the first bent portion 321e.

A plug 321 shown in FIG. 5(C) is obtained by attaching a plug 321 having a shaft portion 321a, a flange portion 321b, and a hole 321j to the piston 32d of the first modified example shown in FIG. 4(A). With such a configuration, it is also possible to form at least one first bent portion 321e in the guide channel. In addition, the hole 321j is formed at a position where the working gas can be discharged toward the first bent portion 321e.

Next, the action of the piston 32d will be described with reference to FIGS. 6(A) to 6(D). 6A and 6B are conceptual diagrams for explaining the action of the piston shown in FIG. , (C) shows the state in which the piston reaches the restraint portion, and (D) shows the state in which the working gas is released from the piston.

As shown in FIG. 6A, before the gas generator 32c is activated, the piston 32d is inserted into the guide member 32b while being pressed against the rear end of the power transmission member 32a by the spacer 32f. .

When the gas generator 32c is actuated to supply working gas into the guide member 32b, the pressure of the working gas moves the piston 32d to the rear end of the power transmission member 32a as shown in FIG. 6(B). The power transmission member 32a is moved forward while maintaining contact.

After that, as shown in FIG. 6C, when the piston 32d reaches the restraining portion 32g, as shown in FIG. 6D, the piston 32d collides with the restraining portion 32g and stops. 32a moves forward due to the inertial force and the pressure of the working gas applied from the first through hole 32r. The working gas released from the first through hole 32r is finally released outside the guide member 32b through the gap between the power transmission member 32a and the guide member 32b.

Therefore, according to the present embodiment, after the piston 32d is restrained by the restraining portion 32g, the working gas can be released from the first through-hole 32r through the guide channel (the first groove 321c and the second groove 321d). , the kinetic energy of the piston 32d can be reduced, and constraints on the design of the pretensioner can be relaxed while minimizing the release of working gas.

Further, according to the present embodiment, by forming the curved portions (the first curved portion 321e and the second curved portion 321f) in the guide passage, it is possible to inhibit the straightness of the working gas when it is released, and the The temperature of the gas can also be lowered, further easing constraints on the design of the pretensioner.

Here, the operation of the pretensioner 3 will be described with reference to FIGS. 7(A) to 7(C). 7A and 7B are cross-sectional views showing the operation of the pretensioner shown in FIG. 1, in which (A) is the state before operation, (B) is the state where the piston has reached the restraining portion, and (C) is the working gas from the piston. is released.

As shown in FIG. 7A, before the pretensioner 3 is activated, the power transmission member 32a is housed inside the guide member 32b. At this time, the tip of the power transmission member 32a is inserted to a position facing the guide member 32h.

In the event of an emergency such as a vehicle collision, the pretensioner 3 is activated, working gas is supplied from the gas generator 32c into the guide member 32b, and the power transmission member 32a is pushed out via the piston 32d to move along the guide member 32b. do. At this time, the tip of the power transmission member 32a collides with the sliding surface 32m of the guide member 32h, is deflected toward the opening 32i, moves along the sliding surface 32m, and is formed on the outer circumference of the ring gear 31. released toward the engaged tooth.

The power transmission member 32a released from the guide member 32b collides with the engaging teeth of the ring gear 31 and causes the ring gear 31 to rotate. After that, the power transmission member 32 a moves along the path formed by the pretensioner cover 33 while being plastically deformed by the engaging teeth of the ring gear 31 .

As shown in FIG. 7B, when the piston 32d moves while the movement of the power transmission member 32a is restricted by the pin 34, the piston 32d collides with and reaches the restriction portion 32g. Then, as shown in FIG. 7C, the piston 32d collides with the restraining portion 32g and stops, the power transmission member 32a is compressed by the inertial force and the pressure of the working gas, and the rear end of the power transmission member 32a Detach from the piston 32d.

Therefore, when the piston 32d is restrained, the working gas can be discharged outside from the first through hole 32r of the piston 32d without being confined in the guide member 32b, and the kinetic energy of the piston 32d can be reduced. . In addition, in the present embodiment, the formation of the guide channel can also reduce the temperature of the working gas discharged from the first through hole 32r.

Although not shown, the power transmission member 32a stops when the slack in the webbing is completely taken up. Therefore, when the amount of slack in the webbing is small, the power transmission member 32a is stopped before the piston 32d reaches the restraining portion 32g. 32a may stop moving.

Next, modifications of the power transmission device 32 will be described with reference to FIGS. 8(A) to 8(D). Here, FIG. 8 is a conceptual diagram showing a modification of the power transmission device shown in FIG. (C) shows the state in which the elastic body has passed through the restraining portion, and (D) shows the state in which the working gas is released from the piston.

The power transmission device 32 shown in FIGS. 8(A) to 8(D) includes an elastic body 322 disposed between a piston 32d and a power transmission member 32a and configured to be able to pass through a restraining portion 32g, and an elastic body 322 and a resin protection member 323 that protects the elastic body 322 and is disposed between the power transmission member 32a.

The elastic body 322 is, for example, an elastomer component formed in a substantially cylindrical shape. The elastic body 322 has an outer diameter smaller than the inner diameter of the guide member 32b in an unloaded state, and is configured to contact the inner surface of the guide member 32b when compressed. In addition, the elastic body 322 has an elastic force capable of being deformed into a shape that can pass through the restraining portion 32g when compressed. Also, the elastic body 322 may have a retaining hole for locking the protective member 323 .

The protection member 323 is made of, for example, the same material as the power transmission member 32a. The protection member 323 has, for example, a substantially T-shaped cross section, and is configured to come into surface contact with the rear end of the power transmission member 32a. Also, the protection member 323 may have a projection that can be locked to the elastic body 322 .

By integrating the elastic body 322 and the protective member 323, handling can be facilitated when the pretensioner 3 is assembled. Note that the protective member 323 is not necessarily a part that must be connected to the elastic body 322, and the shape of the protrusion and retaining hole may be changed or the protrusion and retaining hole may be omitted as necessary.

The configuration of the elastic body 322 and the protection member 323 is not limited to the illustrated configuration. For example, the connection structure may be changed, or the protection member 323 may be omitted as necessary. good.

As shown in FIG. 8A, the elastic body 322 and the protection member 323 are inserted between the power transmission member 32a and the piston 32d before the gas generator 32c is activated. After that, when the gas generator 32c is actuated to supply working gas into the guide member 32b, as shown in FIG. and is compressed and deformed so as to contact the inner surface of the guide member 32b, and moves forward together with the piston 32d.

When the elastic body 322 and the protection member 323 reach the restraining portion 32g, they pass through the restraining portion 32g while elastically deforming along the restraining portion 32g, as shown in FIG. 8(C). Then, as shown in FIG. 8D, when the piston 32d reaches the restraining portion 32g, the piston 32d collides with the restraining portion 32g and stops, and the elastic body 322 and the protective member 323 completely move the restraining portion 32g. pass.

Therefore, the first through hole 32r of the piston 32d is opened and the working gas is discharged. The working gas released from the first through hole 32r is released outside the guide member 32b through the gap between the power transmission member 32a, the elastic body 322, the protection member 323 and the guide member 32b.

Next, a seatbelt device according to one embodiment of the present invention will be described with reference to FIG. Here, FIG. 9 is an overall configuration diagram showing a seat belt device according to one embodiment of the present invention. In addition, in FIG. 9, for convenience of explanation, components other than the seatbelt device are shown by dashed lines.

A seat belt device 100 according to the present embodiment shown in FIG. 9 includes a webbing W that restrains an occupant, a retractor 1 that winds up the webbing W, a guide anchor 101 that is provided on the vehicle body side and guides the webbing W, Equipped with a belt anchor 102 for fixing the webbing W to the vehicle body, a buckle 103 arranged on the side surface of the seat S, and a tongue 104 arranged on the webbing W, the retractor 1 has, for example, the configuration shown in FIG. have.

Components other than the retractor 1 will be briefly described below. The seat S includes, for example, a seat portion S1 on which an occupant sits, a backrest portion S2 positioned behind the occupant, and a headrest portion S3 that supports the occupant's head. The retractor 1 is built in the B-pillar R of the vehicle body, for example. Further, generally, the buckle 103 is often arranged on the side surface of the seat S1, and the belt anchor 102 is often arranged on the lower surface of the seat S1. Further, the guide anchor 101 is often arranged on the B-pillar R. The webbing W has one end connected to the belt anchor 102 and the other end connected to the retractor 1 via the guide anchor 101 .

Therefore, when fitting the tongue 104 to the buckle 103 , the webbing W is pulled out from the retractor 1 while sliding through the insertion hole of the guide anchor 101 . When the occupant wears the seat belt or releases the seat belt when getting off the vehicle, the webbing W is wound up by the action of the spring unit 4 of the retractor 1 until a certain load is applied.

The above-described seatbelt device 100 is obtained by applying the retractor 1 according to the above-described embodiment to a normal seatbelt device for front seats. Therefore, according to the seatbelt device 100 according to the present embodiment, after the piston 32d is restrained by the restraining portion 32g, the working gas can be released from the through hole through the guide passage, and the kinetic energy of the piston 32d can be reduced. can be reduced and the temperature of the working gas can be lowered.

Note that the seat belt device 100 according to the present embodiment is not limited to application to the front seats, and can be easily applied to rear seats by omitting the guide anchors 101, for example. Moreover, the seatbelt device 100 according to the present embodiment can also be used in vehicles other than vehicles.

Further, in the above-described embodiment, the case where the power transmission member 32a has a rod shape made of resin has been described, but the power transmission member 32a may be made of metal in the shape of a sphere (ball), or may be in the form of a rack or a rack. It may be an and pinion driven rack.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the scope of the present invention.

1 retractor 2 spool 3 pretensioner 4 spring unit 5 lock mechanism 6 vehicle sensor 11 base frame 21 torsion bar 31 ring gear 32 power transmission device 32a power transmission member 32b guide member 32c gas generator 32d piston 32e sealing member 32f spacer 32g restraining portion 32h guide member 32i opening 32j notch 32k insertion hole 32m sliding surface 32n notch 32o bolt hole 32p head 32q body 32r first through hole 32s second through hole 32t through hole 32u recess 32v hollow portion 33 pretensioner cover 34 pin 35 fastener 51 retainer cover 52 locking base 61 sensor lever 100 seatbelt device 101 guide anchor 102 belt anchor 103 buckle 104 tongue 111 first end surface 111a opening 112 second end surfaces 112a, 112b opening 113 side surface 114 tie plate 115 Bracket 321 Plug 321a Shaft 321b Flange 321c First groove 321d Second groove 321e First bend 321f Second bend 321g Projection 321h Projection 321i Third bend 321j Pore 322 Elastic body 323 Protective member

Claims (15)

A pretensioner including a ring gear connected to a spool for winding webbing that restrains an occupant, and a power transmission device that transmits power to the ring gear in an emergency,
The power transmission device includes a power transmission member that transmits power to the ring gear, a cylindrical guide member that guides the power transmission member to the ring gear, and a gas generator that supplies working gas to the inside of the guide member. a piston disposed between the gas generator and the power transmission member; a seal member for sealing a gap between the piston and the guide member; and a restraint formed in the guide member for restraining the piston. including the part and
The piston includes a through hole that communicates the front and rear spaces, and a guide flow path that guides the working gas to the through hole,
the guide channel comprises at least one bend;
A pretensioner characterized by: 2. A pretensioner according to claim 1, wherein said guide channel is formed by a plug attached to said piston. 3. The pretensioner according to claim 2, wherein said guide channel is formed by a gap between a groove formed on an outer surface of said plug and an inner surface of said piston. 3. The pretensioner according to claim 2, wherein said guide channel is formed by a hole formed in the axial direction of said plug. 3. The pretensioner according to claim 2, wherein said plug has a protruding portion formed so as to be insertable into said through-hole with a predetermined gap. 3. The pretensioner according to claim 2, wherein the piston includes a head portion having the through hole, and a cylindrical trunk portion formed behind the head portion. 2. The pretensioner according to claim 1, wherein said through-hole is configured to be sealed by a member located in front of said piston until it reaches said restraint portion. 2. The pretensioner according to claim 1, wherein said through-hole is configured in multiple stages with a plurality of holes having different diameters. 2. The pretensioner according to claim 1, wherein said power transmission device includes an elastic body arranged between said piston and said power transmission member and configured to be able to pass through said restraint portion. 10. The pretensioner according to claim 9, wherein said power transmission device includes a resin protection member disposed between said elastic body and said power transmission member and protecting said elastic body. The pretensioner according to claim 1, wherein the power transmission member has a rod shape made of resin. The pretensioner according to claim 11, wherein the power transmission member has a spherical rear end. 2. The pretensioner according to claim 1, wherein said restricting portion is a constricted portion formed in a portion of said guide member. A retractor comprising the pretensioner according to any one of claims 1 to 13. A seatbelt device comprising a retractor having the pretensioner according to any one of claims 1 to 13.

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