JP7612459B2 - Pretensioner, retractor and seatbelt device - Google Patents

Description

The present invention relates to a pretensioner, a retractor, and a seat belt device, and in particular to a pretensioner, a retractor, and a seat belt device that are suitable for a configuration that includes a power transmission member that is an elongated rod-shaped resin member.

Vehicles such as automobiles are generally provided with a seat belt device that restrains an occupant on a seat that has a seating portion on which the occupant sits and a backrest portion located behind the occupant. Such a seat belt device includes webbing that restrains the occupant, a retractor that winds 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. It is also becoming common for the retractor to have a pretensioner that removes slack in the webbing in an emergency such as a vehicle collision.

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 applies a propulsive force to the power transmission member by supplying a working gas into the pipe.

In recent years, research and development has been conducted into the use of a thin, rod-shaped resin part (hereinafter referred to as a "resin rod") as a power transmission member for a pretensioner. For example, Patent Document 1 discloses a configuration that includes a thrust means that constitutes a resin rod, and a piston that includes a deceleration element and a sealing element. Patent Document 2 discloses a configuration that includes a pretensioner rod that constitutes a resin rod, a stopper fixed to the rear end of the pretensioner rod, and a sealing member disposed behind the stopper.

Special Publication No. 2016-523198 JP 2019-127261 A

For example, as described in Patent Document 2, the pipe that guides the resin rod is often bent three-dimensionally. Therefore, if the contact area between the pressing member that pushes the resin rod (e.g., the deceleration element in Patent Document 1, the stopper in Patent Document 2, etc.) and the resin rod is flat, a gap will be created between the resin rod and the pressing member at the bent part of the pipe, resulting in a decrease in power transmission efficiency.

In addition, when the contact area between the pressing member and the resin rod is a combination of a flat surface and a spherical surface, there is a problem that the power transmission efficiency decreases due to reasons such as a small contact area and misalignment at the bent part.

The present invention was devised in consideration of these problems, and aims 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.

According to the present invention, there is provided 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, wherein the power transmission device includes a rod-shaped power transmission member made of resin, a cylindrical guide member including a bent portion that has been bent to guide the power transmission member to the ring gear, 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, and a spacer disposed between the piston and the power transmission member, wherein a contact portion between the power transmission member and the spacer constitutes a ball joint , and the spacer is made of a resin that is harder than the piston and has a hardness equal to or less than that of the power transmission member .

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

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

The spacer may be made of the same resin as the power transmission member.

The piston and the spacer may be configured to be in planar contact or spherical contact or to be engageable.

The spacer may have a constriction at the axial middle.

The present invention also provides a retractor that is characterized by having a pretensioner having the above-mentioned configuration.

The present invention also provides a seat belt device that has a retractor equipped with a pretensioner having the above-mentioned configuration.

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. This makes it possible to maintain the contact area between the power transmission member and the spacer regardless of how the guide member is bent, thereby improving the power transmission efficiency.

FIG. 2 is a component exploded view showing the retractor according to the first embodiment of the present invention. 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. 5A and 5B are explanatory views of when a power transmission member passes through a bent portion, in which FIG. 5A shows a first embodiment and FIG. 5B shows a comparative example. 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. 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. 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. 1 is an overall configuration diagram showing a seat belt device according to an embodiment of the present invention;

Embodiments of the present invention will be described below with reference to Figs. 1 to 7. Here, Fig. 1 is an exploded view showing a retractor according to a first embodiment of the present invention. Fig. 2 is an explanatory diagram showing the relationship between the power transmission member and the spacer, with (A) showing the first embodiment and (B) showing the second embodiment.

As shown in FIG. 1, the retractor 1 according to the first embodiment of the present invention includes a spool 2 that winds up the webbing that restrains the occupant, and 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. Note that the webbing is omitted from FIG. 1.

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 guide member 32b having a bent cylindrical shape 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.

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 also have 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.

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

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

A vehicle sensor 6 that detects 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.

The spool 2 may have a cavity in the center, through which a torsion bar 21 that forms the axis is inserted. The torsion bar 21 has a first end 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 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 the direction of winding up the webbing by a spiral spring stored in the spring unit 4.

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.

The locking base 52 is equipped with a pawl (not shown) that is arranged so that it can be extended and retracted from its side surface. When the locking mechanism 5 is activated, the pawl is caused to protrude from the side surface of the locking base 52, 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 pull-out direction.

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 relative to the torsion bar 2, and the webbing is pulled out.

The lock mechanism 5 also includes a lock gear 53 that is disposed adjacent to the locking base 52. The lock gear 53 includes a flywheel (not shown) that is arranged to be able to swing, and when the webbing is pulled out faster than the normal speed, the flywheel swings and engages 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 of the lock gear 53.

In this way, 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 this relative rotation causes the pawl to protrude from the side of the locking base 52.

The locking mechanism 5 is not limited to the configuration shown in the figure, and various conventional configurations can be selected and used. In addition, the spool 2 may be equipped with a shock absorbing mechanism consisting of a combination of a shaft and a wire-like or plate-like plastic deformation member, instead of the torsion bar 21.

The pretensioner 3 includes, for example, a ring gear 31 with engaging 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 the 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.

The ring gear 31 is disposed so as to be located in the 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 also 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.

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

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 made 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.

Before being inserted into the guide member 32b, the power transmission member 32a is formed in a rod shape having a straight shape, and is housed inside the guide member 32b in a state that conforms to the shape of the guide member 32b, for example, by being pressed 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.

As shown in FIG. 1, for example, the guide member 32b has a three-dimensionally bent shape that passes through the upper part of the first end face 111, the upper part of the tie plate 114, and the upper part of the second end face 112, and extends downward from the upper part of the inside of the corner 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 parts 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.

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, which releases the power transmission member 32a guided by the guide block 32g from the guide member 32b into the space formed by the pretensioner cover 33. The guide member 32b also includes a notch 32i that connects from the tip of the guide member 32b to the opening 32h, and an insertion hole 32k that inserts a fastener 36 formed below the opening 32h.

The opening 32h is formed at a position adjacent to the guide block 32g of the guide member 32b, and constitutes the outlet of the power transmission member 32a. The notch 32i also serves to position the guide block 32g in the circumferential direction, and the protrusion of the guide block 32g is inserted into the notch 32i.

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 on 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 bottom of the sliding surface 32m.

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

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 the tip 322 has a concave spherical shape. The rear end 321 of the power transmission member 32a and the tip 322 of the spacer 32e have substantially the same radius of curvature, and the contact portion β between the power transmission member 32a and the spacer 32e forms a ball joint.

Since the spacer 32e needs to transmit the power of the piston 32d to the power transmission member 32a, it is made of a material that is at least harder than the piston 32d. In addition, the spacer 32e is made of a material that is equal to or less hard than the power transmission member 32a. For example, the spacer 32e is made of the same resin as the power transmission member 32a.

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

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

Here, FIG. 3 is an explanatory diagram of when the power transmission member passes through the bent portion, (A) showing the first embodiment, and (B) showing a comparative example. For example, as shown in FIG. 3(B), 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 toward the inner surface of the guide member 32b.

Therefore, as shown in the comparative example of FIG. 3(B), in the case where the power transmission member 32a' and the spacer 32e' are in planar contact, 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 the power transmission efficiency decreases.

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. 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.

In addition, if the guide member 32b is three-dimensionally bent, the direction in which the rear end 321 of the power transmission member 32a is biased will change each time it passes through the bend α. Even in such a case, however, the contact area between the power transmission member 32a and the spacer 32e can be maintained, improving the power transmission efficiency.

Here, FIG. 4 is an explanatory diagram showing the initial state of the pretensioner, (A) showing the first embodiment, and (B) showing a comparative example. Note that in each figure, the coil spring 32f has been omitted for ease of explanation.

For example, as shown in FIG. 4B, 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.

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 improving the power transmission efficiency and response performance.

Next, modified examples of the pretensioner 3 described above will be described with reference to Figs. 5(A) to 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.

The first modified example shown in FIG. 5(A) is one in which 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 also be spherical.

The second modification shown in FIG. 5(B) is one in which 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, improving the power transmission efficiency.

The third modified example shown in FIG. 5(C) is one in which the tip 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, improving the power transmission efficiency.

The fourth modified example shown in FIG. 6(A) has a generally cylindrical or generally truncated cone-shaped engagement hole 32p formed at the tip of the piston 32d shown in FIG. 2(A), and a protrusion 32q that engages with the engagement hole 32p 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 assembly performance. In addition, the contact area between the piston 32d and the spacer 32e can be increased, improving power transmission efficiency.

The fifth modified example shown in FIG. 6(B) has a generally cylindrical or generally truncated cone-shaped engagement hole 32r 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 assembly performance. In addition, the contact area between the piston 32d and the spacer 32e can be increased, improving power transmission efficiency.

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

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).

Next, a seat belt device according to one embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is an overall configuration diagram showing a seat belt device according to one embodiment of the present invention. Note that in FIG. 7, for ease of explanation, components other than the seat belt device are shown with dashed lines.

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. The retractor 1 has, for example, the configuration shown in FIG. 1.

The components other than the retractor 1 will be briefly described below. 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, for example, built into a B-pillar R of the vehicle body. In general, the buckle 103 is often located on the side of the seating portion S1, and the belt anchor 102 is often located on the underside of the seating portion S1. The guide anchor 101 is often located 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.

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. Also, 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.

The above-described seat belt device 100 is a normal seat belt device for the front seats to which the retractor 1 according to the above-described embodiment is applied. Therefore, according to the seat belt device 100 according to this embodiment, the contact area between the power transmission member 32a and the spacer 32e can be maintained regardless of how the guide member 32b is bent, and power transmission efficiency can be improved.

The seat belt device 100 according to this embodiment is not limited to application to front seats, but can be easily applied to rear seats, for example, by omitting the guide anchor 101. The seat belt device 100 according to this embodiment can also be used in vehicles other than automobiles.

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.

REFERENCE SIGNS LIST 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 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 throttle portion 33 pretensioner cover 34 pin 35 shaft guide 36 fastener 51 retainer cover 52 locking base 53 lock gear 61 sensor lever 100 seat belt 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 321 Rear end portion (power transmission member)
322 Tip (spacer)

Claims (8)

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. 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. 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. The pretensioner according to claim 1 , wherein the spacer is made of the same resin as the power transmission member. The pretensioner according to claim 1, wherein the piston and the spacer are configured to be capable of planar contact, spherical contact, or engagement. The pretensioner according to claim 1, wherein the spacer has a constricted portion at an axially intermediate portion. A retractor comprising the pretensioner according to any one of claims 1 to 6 . A seat belt device comprising a retractor equipped with a pretensioner according to any one of claims 1 to 6 .