Pretensioner, retractor and seatbelt device

Abstract

To provide a pretensioner, a retractor, and a seatbelt device capable of improving power transmission efficiency of a pressing member even when a resin rod-shaped guide member is bent.SOLUTION: A pretensioner 3 includes: a ring gear 31 connected to a spool 2; and a power transmission device 32 that transmits power to the ring gear 31 in an emergency. The power transmission device 32 includes: a resin rod-shaped power transmission member 32a; a bent cylindrical guide member 32b that guides the power transmission member 32a to the ring gear 31; a piston 32d provided between a gas generator 32c and the power transmission member 32a; and a spacer 32e provided between the piston 32d and the power transmission member 32a, a contacting part β between the power transmission member 32a and the spacer 32e forming a ball joint.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pretensioner, a retractor, and a seat belt device, and more particularly to a pretensioner, a retractor, and a seat belt device that are suitable for a configuration including a power transmission member that is an elongated rod-shaped member made of resin. [Background technology]

[0002] In vehicles such as automobiles, a seat belt device for restraining an occupant is generally provided on a seat having a seat portion on which the occupant sits and a backrest portion located behind the occupant. Such a seat belt device includes a webbing for restraining the occupant, a retractor for winding up the webbing, a buckle located on the side of the seat, and a tongue located on the webbing, and the occupant is restrained to the seat by the webbing by fitting the tongue into the buckle. In addition, it is becoming common for the retractor to have a pretensioner for removing slack in the webbing in an emergency such as a vehicle collision.

[0003] Such pretensioners often include a power transmission device that includes a power transmission member that rotates a spool that winds up the webbing, a long, thin, cylindrical pipe (guide member) that guides the power transmission member, and a gas generator that imparts a propulsive force to the power transmission member by supplying a working gas into the pipe.

[0004] In recent years, research and development has been conducted on the use of a thin, rod-shaped resin part (hereinafter referred to as a "resin rod") as a power transmission member of a pretensioner. For example, Patent Document 1 discloses a configuration including a thrust means constituting a resin rod and a piston including a deceleration element and a sealing element. Patent Document 2 discloses a configuration including a pretensioner rod constituting a resin rod, a stopper fixed to the rear end of the pretensioner rod, and a sealing member disposed behind the stopper. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2016-523198 [Patent Document 2] JP 2019-127261 A Summary of the Invention [Problem to be solved by the invention]

[0006] For example, as described in Patent Document 2, the pipe that guides the resin rod is often bent three-dimensionally. Therefore, when the contact portion between the resin rod and a pressing member (for example, the deceleration element in Patent Document 1, the stopper in Patent Document 2, etc.) that pushes the resin rod is in planar contact, a gap is generated between the resin rod and the pressing member at the bent portion of the pipe, resulting in a problem of reduced power transmission efficiency.

[0007] Furthermore, when the contact portion between the pressing member and the resin rod is a combination of a flat surface and a spherical surface, there is a problem in that the power transmission efficiency decreases due to reasons such as a small contact area and misalignment at the bent portion.

[0008] The present invention has been devised in consideration of such problems, and has an object to provide a pretensioner, a retractor, and a seat belt device that can improve the power transmission efficiency of the pressing member even when the guide member of the resin rod is bent. [Means for solving the problem]

[0009] According to the present invention, in a pretensioner including a ring gear connected to a spool that winds up a webbing for restraining 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 having a rod shape made of resin, and a bending processed guide member that guides the power transmission member to the ring gear. Including bendsThe power transmission device includes a cylindrical guide member, a gas generator that supplies a working gas to the inside of the guide member, a piston that is disposed between the gas generator and the power transmission member, and a spacer that is disposed between the piston and the power transmission member, and a contact portion between the power transmission member and the spacer constitutes a ball joint. The spacer is made of a resin having a hardness that is harder than the piston and equal to or less than that of the power transmission member. A pretensioner is provided that is characterized by the above.

[0010] The ball joint may have a convex spherical shape on the power transmission member side and a concave spherical shape on the spacer side.

[0011] The ball joint may have a concave spherical shape on the power transmission member side and a convex spherical shape on the spacer side.

[0013] The spacer is a Made from the same resin as It may be configured as follows.

[0014] The piston and the spacer may be configured to be capable of plane contact or spherical contact or engagement with each other.

[0015] The spacer may have a throttle portion at an axially intermediate portion.

[0016] According to the present invention, there is also provided a retractor comprising a pretensioner having the above-mentioned configuration.

[0017] According to the present invention, there is also provided a seat belt device comprising a retractor equipped with a pretensioner having the above-mentioned configuration. Effect of the Invention

[0018] According to the pretensioner, retractor, and seat belt device of the present invention described above, the pressing member is formed by a spacer disposed between the piston and the power transmission member, and the contact portion between the power transmission member and the spacer is formed by a ball joint. Therefore, no matter how the guide member is bent, the contact area between the power transmission member and the spacer can be maintained, and power transmission efficiency can be improved. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is a component exploded view showing the retractor according to the first embodiment of the present invention. [Diagram 2] 5A and 5B are explanatory views showing the relationship between a power transmission member and a spacer, in which FIG. 5A shows a first embodiment and FIG. 5B shows a second embodiment. [Diagram 3] 5A and 5B are explanatory views of when a power transmission member passes through a bent portion, in which (A) shows a first embodiment and (B) shows a comparative example. [Figure 4] 5A and 5B are explanatory diagrams showing an initial state of a pretensioner, in which FIG. 5A shows a first embodiment and FIG. 5B shows a comparative example. [Diagram 5] 5A to 5C are cross-sectional views showing modified examples of the pretensioner, in which (A) shows a first modified example, (B) shows a second modified example, and (C) shows a third modified example. [Figure 6] 5A to 5C are cross-sectional views showing modified examples of the pretensioner, in which (A) shows a fourth modified example, (B) shows a fifth modified example, and (C) shows a sixth modified example. [Figure 7] 1 is an overall configuration diagram showing a seat belt device according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to Fig. 1 to Fig. 7. Fig. 1 is a component exploded view showing a retractor according to a first embodiment of the present invention. Fig. 2 is an explanatory diagram showing the relationship between a power transmission member and a spacer, where (A) shows the first embodiment and (B) shows the second embodiment.

[0021] 1, a retractor 1 according to a first embodiment of the present invention includes a spool 2 that winds up a webbing for restraining an occupant, and a pretensioner 3 that winds up the webbing to remove slack in an emergency, and 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. Note that the webbing is omitted from FIG. 1.

[0022] The power transmission device 32 includes, for example, a power transmission member 32a (resin rod) having a rod shape made of resin that transmits power to the ring gear 31, a bent cylindrical guide member 32b that guides the power transmission member 32a to the ring gear 31, a gas generator 32c that supplies working gas to the inside of the guide member 32b, a piston 32d arranged between the gas generator 32c and the power transmission member 32a, a spacer 32e arranged between the piston 32d and the power transmission member 32a, and a coil spring 32f arranged between the gas generator 32c and the piston 32d.

[0023] The spool 2 is a winding drum that winds up the webbing, and is rotatably housed within a base frame 11 that forms the framework of the retractor 1. The base frame 11 has, for example, a first end face 111 and a second end face 112 that face each other, and a side face 113 that connects these end faces. The base frame 11 may include a tie plate 114 that faces the side face 113 and is connected to the first end face 111 and the second end face 112.

[0024] Also, for example, the spring unit 4 is disposed on the first end face 111 side, and the pretensioner 3 and the locking mechanism 5 are disposed on the second end face 112 side. Note that the arrangement of the spring unit 4, the pretensioner 3, the locking mechanism 5, etc. is not limited to the configuration shown in the figure.

[0025] An opening 111a through which the shaft portion of the spool 2 is inserted is formed in a first end surface 111 of the base frame 11, and an opening 112a having internal teeth engageable with a pawl (not shown) of the locking mechanism 5 is formed in a second end surface 112 of the base frame 11. A part of the pretensioner 3 (e.g., ring gear 31) is disposed inside the second end surface 112 of the base frame 11. The locking mechanism 5 is disposed outside the second end surface 112 of the base frame 11, and the locking mechanism 5 is housed in a retainer cover 51.

[0026] A vehicle sensor 6 for detecting sudden deceleration or tilt of the vehicle body may be disposed 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 the movement of the mass body. The vehicle sensor 6 may be fitted and fixed in an opening 112b formed in the second end surface 112 of the base frame 11.

[0027] The spool 2 may have a cavity in the center, through which a torsion bar 21 that forms an axis is inserted. A first end of the torsion bar 21 is connected to a locking base 52 of the locking mechanism 5 that is connected to an end of the spool 2, and a second end is fixed to the spool 2 and connected to a spring core of the spring unit 4. Therefore, the spool 2 is connected to the spring unit 4 via the torsion bar 21, and is biased in a direction to wind up the webbing by a spiral spring stored in the spring unit 4.

[0028] The means for applying a winding force to the spool 2 is not limited to the spring unit 4, but may be other means such as an electric motor.

[0029] The locking base 52 is provided with a pawl (not shown) arranged so as to be able to protrude from and retract into a side surface of the locking base 52. When the locking mechanism 5 is activated, the pawl is caused to protrude from the side surface of the locking base 52, thereby engaging with internal teeth formed in the opening 112a of the base frame 11, thereby restricting the rotation of the locking base 52 in the webbing-pulling out direction.

[0030] Therefore, even if a load is applied in the webbing-pulling direction with the locking mechanism 5 activated, the spool 2 can be held in a non-rotating state until a load equal to or greater than a threshold value is applied to the torsion bar 21. When a load equal to or greater than a threshold value is applied to the torsion bar 21, the torsion bar 21 twists, causing the spool 2 to rotate relatively, and the webbing is pulled out.

[0031] The lock mechanism 5 also includes a lock gear 53 disposed adjacent to the locking base 52. The lock gear 53 includes a flywheel (not shown) disposed so as to be able to swing, and when the webbing is pulled out faster than a normal speed, the flywheel swings to engage with internal teeth formed on the retainer cover 51. When the vehicle sensor 6 is activated, the sensor lever 61 engages with external teeth formed on the side surface of the lock gear 53.

[0032] In this way, the rotation of the lock gear 53 is restricted by the operation of the flywheel or the vehicle sensor 6. When the rotation of the lock gear 53 is restricted, a 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 in accordance with this relative rotation.

[0033] The lock mechanism 5 is not limited to the configuration shown in the figure, and various conventional configurations can be selected and used as desired. Also, the spool 2 may be provided with a shock absorbing mechanism formed by combining a shaft and a wire-like or plate-like plastic deformation member, instead of the torsion bar 21.

[0034] The pretensioner 3 includes, for example, a ring gear 31 having engaging teeth on its outer periphery, a power transmission device 32, a pretensioner cover 33 that houses the ring gear 31, and a pin 34 that restricts movement of the power transmission member 32a. Although not shown, the pretensioner 3 may also include a guide spacer that forms a movement space for the power transmission member 32a within the pretensioner cover 33.

[0035] The ring gear 31 is disposed so as to be located in a space formed between the pretensioner cover 33 and the base frame 11 (second end surface 112). The ring gear 31 may also be referred to as a drive wheel or a rotating member. A shaft guide 35 may be disposed on the inner surface of the second end surface 112 along the outer periphery of the ring gear 31 to guide the rotation while controlling the load from the power transmission member 32a.

[0036] The pretensioner cover 33 is disposed, for example, on the inside of the second end surface 112 of the base frame 11. In addition, the pretensioner cover 33 is fixed to the base frame 11 (the second end surface 112) together with the guide member 32b or directly by, for example, a fastener 36 or the like.

[0037] The power transmission device 32 is, for example, arranged in the following order from the rear end to the front end of a guide member 32b formed of a cylindrical pipe: a gas generator 32c, a coil spring 32f, a piston 32d, a spacer 32e, and a power transmission member 32a. The power transmission member 32a, the spacer 32e, the piston 32d, and the coil spring 32f are housed in the guide member 32b, and move within the guide member 32b by the working gas generated by the gas generator 32c arranged at the rear end of the guide member 32b.

[0038] The power transmission member 32a is formed in a rod shape having a linear shape before being inserted into the guide member 32b, and is housed inside the guide member 32b in a state following the shape of the guide member 32b, for example, by being press-fitted into the guide member 32b from the tip side of the guide member 32b, as shown in Fig. 1. In addition, the rear end portion 321 of the power transmission member 32a has a convex spherical shape.

[0039] 1, the guide member 32b has a shape that is three-dimensionally bent so as to pass through an upper portion of the first end face 111, an upper portion of the tie plate 114, an upper portion of the second end face 112, and extend downward from an upper portion of the inside of a corner portion formed by the second end face 112 and the side face 113. The guide member 32b shown in FIG. 1 has, for example, three bent portions α from the upstream side to the downstream side. Note that the bending of the guide member 32b is not limited to the shape shown in the figure.

[0040] A guide block 32g is disposed at the tip of the guide member 32b. An opening 32h is formed at the tip of the guide member 32b to release the power transmission member 32a guided by the guide block 32g from the guide member 32b into a space formed by the pretensioner cover 33. The guide member 32b also includes a notch 32i that communicates from the tip of the guide member 32b to the opening 32h, and an insertion hole 32k that is formed below the opening 32h and through which a fastener 36 is inserted.

[0041] The opening 32h is formed in the guide member 32b at a position adjacent to the guide block 32g, and constitutes an outlet portion of the power transmission member 32a. The notch 32i has a function of positioning the guide block 32g in the circumferential direction, and a protrusion of the guide block 32g is inserted into the notch 32i.

[0042] The guide block 32g has, for example, a generally cylindrical shape that can be inserted into the tip of the guide member 32b, and a sliding surface 32m that guides the power transmission member 32a to the opening 32h is formed at an angle at the end of the insertion side. The sliding surface 32m may have a groove shape that curves along the outer shape of the power transmission member 32a. In addition, a notch 32n through which the fastener 36 is inserted is formed at the lower part of the sliding surface 32m.

[0043] The piston 32d is, for example, a sealing member made of elastomer having a substantially cylindrical shape. The piston 32d moves while being kept in contact with the inner surface of the guide member 32b by the pressure of the working gas supplied from the gas generator 32c. The coil spring 32f is a component that fills a gap that occurs between the gas generator 32c and the piston 32d in the initial state to position the piston 32d.

[0044] The spacer 32e is a pressing member that transmits the power of the piston 32d to the power transmission member 32a. For example, as shown in Fig. 2(A), the spacer 32e has a substantially cylindrical outer shape, and a tip portion 322 has a concave spherical shape. The rear end portion 321 of the power transmission member 32a and the tip portion 322 of the spacer 32e have substantially the same radius of curvature, and a contact portion β between the power transmission member 32a and the spacer 32e constitutes a ball joint.

[0045] The spacer 32e is made of a material harder than the piston 32d because it is necessary to transmit the power of the piston 32d to the power transmission member 32a. The spacer 32e is made of a material having a hardness equal to or less than that of the power transmission member 32a. For example, the spacer 32e is made of the same resin as the power transmission member 32a.

[0046] 2A, the piston 32d and the spacer 32e are configured to be in flat contact with each other. The spacer 32e may be made of a material (e.g., metal) harder than the power transmission member 32a.

[0047] 2(B), the ball joint (contact portion β) may be configured by a concave spherical shape formed on rear end portion 321 of power transmission member 32a and a convex spherical shape formed on tip portion 322 of spacer 32e. With this configuration, the ball joint according to the second embodiment has the same effects as the first embodiment.

[0048] 3A and 3B are explanatory diagrams of the power transmission member passing through a bent portion, where (A) shows the first embodiment and (B) shows a comparative example. For example, as shown in Fig. 3B, when the power transmission member 32a' passes through the bent portion α of the guide member 32b, the axis of the power transmission member 32a' deviates from the axis of the guide member 32b, and the rear end portion 321' is biased in one direction on the inner surface of the guide member 32b.

[0049] Therefore, as shown in the comparative example of Figure 3(B), in the case where the power transmission member 32a' and the spacer 32e' are in planar contact with each other, a gap γ is formed between the power transmission member 32a' and the spacer 32e', reducing the contact area between the power transmission member 32a' and the spacer 32e', and thus reducing the power transmission efficiency.

[0050] In contrast, when the contact portion β between the power transmission member 32a and the spacer 32e is formed by a ball joint as in the first embodiment shown in FIG. 3(A), even if the rear end portion 321 is biased in one direction on the inner surface of the guide member 32b when the power transmission member 32a passes through the bent portion α of the guide member 32b, the gap formed between the power transmission member 32a and the spacer 32e can be reduced and the contact area between the power transmission member 32a and the spacer 32e can be maintained, thereby improving the power transmission efficiency.

[0051] Furthermore, when the guide member 32b is three-dimensionally bent, the direction in which the rear end 321 of the power transmission member 32a is biased changes each time it passes through the bend α. However, even in such a case, the contact area between the power transmission member 32a and the spacer 32e can be maintained, thereby improving the power transmission efficiency.

[0052] 4A and 4B are explanatory diagrams showing the initial state of the pretensioner, where (A) shows the first embodiment and (B) shows a comparative example. Note that in each diagram, the coil spring 32f is omitted for ease of explanation.

[0053] 4(B), when the spacer 32e' is located at the bent portion α of the guide member 32b in the initial state of the pretensioner 3, a gap γ is also formed between the power transmission member 32a' and the spacer 32e'. Therefore, the power transmission efficiency and response performance when the pretensioner 3 is activated are reduced.

[0054] In contrast, when the contact portion β between the power transmission member 32a and the spacer 32e is configured by a ball joint as in the first embodiment shown in FIG. 4(A), even when the spacer 32e is located at the bent portion α of the guide member 32b in the initial state of the pretensioner 3, the gap formed between the power transmission member 32a and the spacer 32e can be reduced and the contact area between the power transmission member 32a and the spacer 32e can be maintained, thereby enabling improvements in power transmission efficiency and response performance to be achieved.

[0055] Next, modified examples of the pretensioner 3 described above will be described with reference to Fig. 5(A) to Fig. 6(C). Fig. 5 is a cross-sectional view showing modified examples of the pretensioner, with (A) showing a first modified example, (B) showing a second modified example, and (C) showing a third modified example. Fig. 6 is a cross-sectional view showing modified examples of the pretensioner, with (A) showing a fourth modified example, (B) showing a fifth modified example, and (C) showing a sixth modified example.

[0056] In the first modification shown in Fig. 5(A), the tip of the piston 32d shown in Fig. 2(A) is changed to a convex spherical shape. This configuration makes it easier to fill the gap between the spacer 32e and the piston 32d in the initial state. Although not shown, the piston 32d may be spherical.

[0057] In the second modified example shown in Fig. 5(B), the rear end of the spacer 32e shown in Fig. 5(A) is changed to a concave spherical shape. With this configuration, a ball joint can be formed between the piston 32d and the spacer 32e, and power transmission efficiency can be improved.

[0058] In the third modified example shown in Fig. 5(C), the tip end of the piston 32d shown in Fig. 2(A) is changed to a concave spherical shape, and the rear end of the spacer 32e is changed to a convex spherical shape. With this configuration, a ball joint can be formed between the piston 32d and the spacer 32e, and power transmission efficiency can be improved.

[0059] In the fourth modified example shown in Fig. 6(A), a generally cylindrical or generally truncated cone-shaped engagement hole 32p is formed at the tip of the piston 32d shown in Fig. 2(A), and a protrusion 32q that engages with the engagement hole 32p is formed at the rear end of the spacer 32e. With this configuration, the piston 32d and the spacer 32e can be integrated before being inserted into the guide member 32b, improving the assembly performance. In addition, the contact area between the piston 32d and the spacer 32e can be increased, improving the power transmission efficiency.

[0060] In the fifth modified example shown in Fig. 6(B), a substantially cylindrical or truncated cone-shaped engagement hole 32r is formed at the rear end of the spacer 32e shown in Fig. 2(A), and a protrusion 32s that engages with the engagement hole 32r is formed at the tip of the piston 32d. With this configuration, the piston 32d and the spacer 32e can be integrated before being inserted into the guide member 32b, improving the assembly performance. In addition, the contact area between the piston 32d and the spacer 32e can be increased, improving the power transmission efficiency.

[0061] In the sixth modified example shown in Fig. 6(C), a throttle portion 32t is formed in the axially intermediate portion of the spacer 32e shown in Fig. 2(A). The throttle portion 32t is formed by reducing the diameter of the axially intermediate portion of the spacer 32e. By forming such a throttle portion 32t, it is possible to reduce the weight of the spacer 32e and improve its flexibility. Note that the throttle portion 32t is not limited to the shape shown in the figure.

[0062] The first to sixth modified examples described above are applied to the power transmission device 32 of the pretensioner 3 according to the first embodiment shown in FIG. 2(A), but can also be applied to the second embodiment shown in FIG. 2(B).

[0063] Next, a seat belt device according to one embodiment of the present invention will be described with reference to Fig. 7. Here, Fig. 7 is an overall configuration diagram showing a seat belt device according to one embodiment of the present invention. In Fig. 7, for convenience of explanation, components other than the seat belt device are illustrated by dashed lines.

[0064] The seat belt device 100 according to this embodiment shown in FIG. 7 includes a webbing W for restraining an occupant, a retractor 1 for winding up the webbing W, a guide anchor 101 provided on the vehicle body side for guiding the webbing W, a belt anchor 102 for fixing the webbing W to the vehicle body side, a buckle 103 arranged on the side of the seat S, and a tongue 104 arranged on the webbing W, and the retractor 1 has, for example, the configuration shown in FIG. 1.

[0065] Below, components other than the retractor 1 will be briefly described. The seat S includes, for example, a seating portion S1 on which an occupant sits, a backrest portion S2 located behind the occupant, and a headrest portion S3 that supports the occupant's head. The retractor 1 is built into, for example, a B-pillar R of a vehicle body. In general, the buckle 103 is often disposed on the side of the seating portion S1, and the belt anchor 102 is often disposed on the underside of the seating portion S1. The guide anchor 101 is often disposed on the B-pillar R. One end of the webbing W is connected to the belt anchor 102, and the other end is connected to the retractor 1 via the guide anchor 101.

[0066] Therefore, when the tongue 104 is fitted into 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 an occupant fastens the seat belt or releases the seat belt when getting off the vehicle, the spring unit 4 of the retractor 1 acts to retract the webbing W until a certain load is applied.

[0067] The above-mentioned seat belt device 100 is a normal seat belt device for the front seat to which the retractor 1 according to the above-mentioned embodiment is applied. Therefore, according to the seat belt device 100 according to this embodiment, no matter how the guide member 32b is bent, the contact area between the power transmission member 32a and the spacer 32e can be maintained, and power transmission efficiency can be improved.

[0068] The seat belt device 100 according to the present embodiment is not limited to application to a front seat, and can be easily applied to a rear seat, for example, by omitting the guide anchor 101. The seat belt device 100 according to the present embodiment can also be used in vehicles other than automobiles.

[0069] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0070] 1 Retractor 2 Spools 3 Pretensioner 4 Spring unit 5 Locking mechanism 6 Vehicle Sensors 11 Base frame 21 Torsion bar 31 Ring Gear 32 Power transmission device 32a Power transmission members 32b Guide member 32c Gas Generator 32d Piston 32e Spacer 32f coil spring 32g guide block 32h opening 32i Notch 32k insertion hole 32m sliding surface 32n Notch 32p,32r engagement hole 32q,32s protrusion 32t squeeze section 33 Pretensioner cover 34 pin 35 Shaft guide 36 Fasteners 51 Retainer cover 52 Rocking Base 53 Lock Gear 61 Sensor lever 100 Seat belt device 101 Guide Anchor 102 Belt anchor 103 Buckle 104 Tongs 111 First end face 111a opening 112 Second end face 112a,112b opening 113 Side 114 Thai Plate 321 Rear end (power transmission member) 322 Tip (spacer)

Claims

1. A pretensioner including a ring gear connected to a spool that winds up a webbing for restraining 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 having a rod shape made of resin; a cylindrical guide member including a bent portion formed by bending and guiding the power transmission member to the ring gear; a gas generator that supplies a working gas to an inside of the guide member; a piston that is disposed between the gas generator and the power transmission member; and a spacer that is disposed between the piston and the power transmission member; a contact portion between the power transmission member and the spacer constitutes a ball joint; The spacer is made of a resin having a hardness that is harder than the piston and equal to or less than the hardness of the power transmission member. A pretensioner characterized by the above.

2. 2. The pretensioner according to claim 1, wherein the ball joint has a convex spherical shape on the power transmission member side and a concave spherical shape on the spacer side.

3. 2. The pretensioner according to claim 1, wherein the ball joint has a concave spherical shape on the power transmission member side and a convex spherical shape on the spacer side.

4. The pretensioner according to claim 1 , wherein the spacer is made of the same resin as the power transmission member.

5. The pretensioner according to claim 1 , wherein the piston and the spacer are configured to be capable of making flat surface contact or spherical contact or to be engageable with each other.

6. The pretensioner according to claim 1 , wherein the spacer has a throttle portion at an axially intermediate portion.

7. A retractor comprising the pretensioner according to any one of claims 1 to 6.

8. A seat belt device comprising a retractor equipped with a pretensioner according to any one of claims 1 to 6.

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