JPH0715460U - Pretensioner for seat belt - Google Patents

Abstract

(57) [Abstract] [Purpose] For a good seat belt that can increase the sensitivity of the acceleration detection means by facilitating the reset after it has been operated once, and can exert its effect in a wider variety of operating situations. Provides a pretensioner. [Structure] The pullback prevention mechanism 24 includes a guide rail 24a fixed to the vehicle body, a slide base 24d slidably mounted along the guide rail 24a, and a cam portion 31 slidable on the guide rail 24a. The slide base 24d is rotatably held in contact with the cam piece 24b to which the transmission member 23 is fixed, and the buckle support member 20 fixed to the cam piece 24b. The cam portion 31
However, when the transmission member 23 pulls in the webbing tension direction, it allows the cam piece 24b to slide on the guide rail, and when the webbing pulls back the retracted portion, it meshes with the guide rail surface to prevent sliding. To do.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a seat belt pretensioner that removes seat belt play by retracting the buckle itself of the seat belt device or the webbing in the vicinity of the buckle in an emergency. It relates to the improvement of the mechanism.

[0002]

[Prior art]

 Conventionally, a seat belt device for safely holding an occupant such as a vehicle on a seat tends to reduce the retracting force of the webbing by the retractor in order to reduce the occupant's feeling of wearing the webbing. When a large amount of force is applied at the time of a collision, restraint is delayed due to such webbing play, and it may not be possible to restrain the occupant effectively and safely.

Therefore, in an emergency, in order to remove the seat belt play by pulling in the webbing and tensioning the webbing, the retractor take-up shaft is instantly rotated in the take-up direction, and a buckle for the seat belt. There is a seatbelt device in which a pretensioner for a seatbelt that is capable of instantaneously retracting the webbing itself or near the buckle in the tension direction of the webbing is incorporated.

As the latter type of seat belt pretensioner, there are pretensioners disclosed in, for example, Japanese Patent Laid-Open Nos. 1-164650, 3-38444 and 4-56658, and webbing. The supporting member of the buckle to which is connected is guided to the frame so as to be movable in the webbing tension direction from the normal protruding position, and the frame is provided with drive means for driving the webbing support member in the webbing tension direction in case of a vehicle emergency. In this way, the webbing that has been hung on the occupant is pulled in during an emergency. In addition, these pretensioners are equipped with a pullback prevention mechanism in order to prevent the webbing once pulled in an emergency from being pulled back by the load acting on the seat belt (for example, the inertial force of the occupant).

A so-called ratchet mechanism is generally used as the pull-back prevention mechanism. For example, a ratchet pawl member is swingably disposed on a buckle support member that is driven in the webbing tension direction by a driving unit. At the same time, ratchet locking teeth are provided on the frame fixed to the vehicle body to guide the buckle supporting member in the webbing tension direction, and the ratchet pawl member is meshed with the ratchet locking teeth of the frame to support the buckle. The member is movable only in the webbing tension direction to prevent the buckle support member from being pulled back by the load acting on the seat belt.

[0006]

[Problems to be solved by the device]

 By the way, as a driving means for the pretensioner as described above, there is a device using an explosive driving device, but the explosive driving device that has once been operated must be replaced together with the unit and cannot be reused. In addition, although a device using an urging force accumulating device such as a compression coil spring or a Zenmai spring as the driving means of the pretensioner as described above can be reused, in order to return the urging force accumulating device to the initial position. Must release the pullback prevention mechanism. However, in the case where the pull-back prevention mechanism is the ratchet mechanism as described above, after removing the cover member that covers the pretensioner, the ratchet pawl member is held in the disengaged state with the ratchet locking teeth, and the biasing force is accumulated. Difficult work such as returning the device to the initial position is required.

That is, once the conventional pretensioner operates once, it requires difficult work such as replacement of parts and adjustment of the mounting position by a maintenance worker who has expertise in order to reset the pretensioner to the usable state again. Therefore, the user will be inflicted with a large financial burden. On the other hand, the acceleration detecting means for activating the drive means of the pretensioner in case of an emergency of the vehicle receives various vibrations such as vibrations at the time of collision, vibrations at the time of door closing or hitting the body. If the sensitivity of the acceleration detecting means is increased, the possibility of malfunction will increase.

Therefore, in the conventional pretensioner, the operating condition is limited to, for example, a collision during high-speed traveling, which has a high degree of risk, to make the operation sensitivity of the acceleration detection means dull so that the pretensioner does not operate carelessly. It is set to operate by a major collision. As a result, there is a problem that the effect of the pretensioner cannot be obtained, for example, when traveling on a rough road, during sudden braking, or during a slight collision during traveling at low speed.

Therefore, an object of the present invention is to solve the above-mentioned problems, and it is possible to increase the sensitivity of the acceleration detecting means by facilitating the resetting after the operation once, and it is effective in a variety of operating situations. It is intended to provide a good seat belt pretensioner capable of exhibiting the above.

[0010]

[Means for Solving the Problems]

 The above object of the present invention is to provide a driving means for pulling a seat belt fitting or a webbing near the fitting in the webbing tension direction in a vehicle emergency, and the operation of the driving means to the fitting itself or the webbing near the fitting. A seat belt for removing play of the seat belt, which includes a transmission member for transmitting and a pull-back prevention mechanism for preventing the pulled-back portion from being pulled back by the load acting on the webbing after the pulling-in operation by the driving means is completed. In the pretensioner, the pullback preventing mechanism includes a guide rail fixed to the vehicle body, a slide base slidably mounted along the guide rail, and a slide so that a cam portion slides on the guide rail. A cam piece rotatably held by the base and having the transmission member fixed thereto; And a buckle support member fixed to the web piece to which the webbing is connected, and when the cam portion of the cam piece is pulled in the webbing tension direction by the transmission member, when the cam piece rotates, the cam piece slides on the guide rail. The seat belt lid is characterized by allowing the movement of the cam piece and engaging with the guide rail surface to prevent the cam piece from sliding on the guide rail when the cam piece suddenly rotates when the retracted portion is pulled back by the webbing. Achieved by the tractor.

Further, the above-mentioned object of the present invention is such that the pullback preventing mechanism includes a cylinder in which a viscous fluid is sealed, a piston reciprocally slidable in the cylinder, and a pressure adjusting means provided in the piston. The rod has one end connected to the buckle support member and the other end connected to the transmission member and fixed to the piston, and the pressure adjusting means allows movement of the piston in the webbing tension direction. It can also be achieved by a seat belt retractor characterized by preventing rapid movement in the webbing pullback direction.

Further, the above-mentioned object of the present invention is that the pullback preventing mechanism includes a cylinder in which a viscous fluid is sealed, a piston capable of reciprocatingly sliding in the cylinder, and a piston having one end connected to the transmission member. It is equipped with a rod fixed to the cylinder and a pump capable of supplying viscous fluid into the cylinder in order to move the piston in the webbing tension direction. The pressure of the viscous fluid supplied by the pump causes the piston to move in the webbing tension direction. It can also be achieved by a seat belt retractor characterized by allowing movement and preventing rapid movement in the webbing pullback direction.

[0013]

[Action]

 According to the above configuration of the present invention, the force for pulling back the retracted portion by the load acting on the webbing to the cam piece after being pulled in the webbing tension direction in the emergency of the vehicle in response to the pulling drive of the drive means. When is acted, the cam piece is rapidly rotated in the direction in which the cam portion meshes with the guide rail surface. Therefore, the cam piece, which is prevented from sliding on the guide rail, is prevented from being pulled back by the drive means.

In order to cancel the state in which the cam portion of the cam piece meshes with the guide rail surface to prevent the cam piece from sliding on the guide rail, the direction in which the cam portion meshes with the guide rail surface is set. A slight rotating force in the opposite rotating direction may be applied to the cam piece. Further, since the cam portion meshes with the guide rail surface by the abrupt rotation of the cam piece, if the cam piece is moved to the initial position so as not to rotate abruptly in the direction in which the cam portion meshes with the guide rail surface, The cam piece is not prevented from sliding on the guide rail.

Therefore, the pullback preventing mechanism can be easily released, and the buckle supporting member can be easily returned to the initial position. Also, even if the pretensioner operates once, it can be easily reset to the initial state without the need for difficult work such as parts replacement and adjustment of the mounting position, reducing the financial burden on the user due to parts replacement, etc. Be touched.

[0016]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1 to 4 show a seat belt pretensioner according to a first embodiment of the present invention. FIG. 1 is a front view of a main portion of the seat belt pretensioner, and FIG. 2 is a seat shown in FIG. FIG. 3 is an exploded perspective view of the main part of the belt pretensioner, FIG. 3 is a rear view of the main part of the seatbelt pretensioner shown in FIG. 1, and FIG. 4 is a bottom view of the seatbelt pretensioner.

The seat belt pretensioner 21 of the first embodiment removes the seat belt play by pulling the buckle 10 fixed to the lower fitting of the seat belt in the webbing tension direction in case of a vehicle emergency. As shown in FIG. 4, drive means 22 for retracting the buckle support member 20 by a predetermined amount in the webbing tension direction in an emergency and a transmission member for transmitting the operation of the drive means 22 to the buckle support member 20. 23, and a pullback prevention mechanism 24 that functions as the lower attachment and at the same time prevents the pullback portion from being pulled back by the load acting on the webbing after the pulling operation by the driving means 22 is completed. It is said that.

The drive means 22 is, for example, an application of a drive device for an automatic seat belt system disclosed in Japanese Patent Application Laid-Open No. 62-143747 and is applied to the buckle support member 20 via the pullback prevention mechanism 24. A rotary drum 22a for winding up and pushing out a flexible cord body (for example, a wire) having one end connected, a motor 22b for rotationally driving the rotary drum 22a, and an operation of the motor 22b. It is composed of a pretensioner control means (not shown) for controlling the.

The pretensioner control means monitors a vehicle acceleration or the like by an acceleration sensor to detect a vehicle collision, and rotationally drives the rotary drum 22a in a direction in which the cord 22 is wound by the motor 22b. Further, the pretensioner control means rotationally drives the rotary drum 22a in the direction of pushing out the cord in order to reset the pretensioner.

As shown in FIG. 2, the transmission member 23 has a flexible cord body 23a that is wound or extruded by the rotary drum 22a and a slidable coating of the cord body 23a. The cord guide 23b and a pair of connecting fittings 23c for connecting and fixing the tip end of the cord body 23a to the fixture side are provided. The pair of connecting fittings 23c are provided with a pipe portion 23d through which the cord 23a is inserted, and a projecting piece 23e protruding from the outer periphery of the pipe 23d, and the pipe 23d is provided with the cord 23a. After being inserted, the pipe portion 23d is fixed to the cord 23a by caulking a part of the pipe portion 23d.

As shown in FIG. 2, the pull-back prevention mechanism 24 includes a long guide rail 24a fixed to the vehicle body at the side of the seat and the like, and a bottom surface portion of the guide rail 24a. Slide base 24d slidably attached to the guide rail 24a, and the cam base 31 is rotatably held by the slide base 24d so that the cam portion 31 is in sliding contact with the bottom surface of the guide rail 24a. And a buckle support member 20 fixed to the cam piece 24b.

The guide rail 24a is formed by bending a metal plate to form a groove 25 in which the cam piece 24b is slidably guided, and the pullback is provided on the lower surface on the front end side of the guide rail 24a. A limit switch 22c for detecting that the prevention mechanism 24 is set to the initial state is attached. The slide base 24d is formed by bending a U-shaped metal plate so as to face the bottom and both sides of the guide rail 24a. Bearing holes 24c are formed in both side wall portions of the slide base 24d so as to rotatably support the cam piece 24b through the inserted pins 26.

The slide base 24d is fitted onto the guide rail 24a from the bottom side of the guide rail 24a, and the cam piece 24b is fitted into the groove 25 of the guide rail 24a with the slide base 24d fitted on the guide rail 24a. Then, by inserting the pin 26 into the bearing hole 24c and the through hole 27, the cam piece 24b and the slide base 24d are integrally slidably mounted on the guide rail 24a. A retaining ring 34 is fitted at the tip of the pin 26 inserted through the bearing hole 24c and the through hole 27 to prevent the pin from coming off.

The cam piece 24b has a through hole 27 for inserting a pin 26 serving as a rotation center axis into a metal block, and a transmission member connection for inserting the cord 23a and the connection fitting 23c of the transmission member 23. The hole 28, the buckle fixing screw 30 for rotatably connecting the base end of the buckle supporting member 20 via the bolt 29, and the buckle fixing screw part 30 for preventing the webbing from being pulled back after the pulling operation. And a cam portion 31 that engages with the bottom surface of the guide rail 24a.

The through hole 27 and the buckle fixing screw portion 30 are formed so as to penetrate along the width direction of the groove portion 25 of the guide rail 24 a, and the transmission member connecting hole 28 is formed in the longitudinal direction of the groove portion 25. It is formed so as to penetrate along (that is, the sliding direction of the cam piece 24b). Further, in the transmission member connecting hole 28, a step portion 28a that engages with the projecting piece 23e of the connecting fitting 23c is projectingly provided, and a pair of connecting members provided at the tip of the cord 23a. The tip end of the cord 23a is connected to the cam piece 24b by the projecting pieces 23e of the metal fitting 23c sandwiching the step portion 28a. That is, with this connecting structure, when the cord 23a is pushed out by the driving means 22, the force in the pushing direction (the direction of arrow A in FIG. 1) can act on the cam piece 24b, and When the body 23a is pulled in the webbing tension direction by the drive means 22, the force in the pulling direction can act on the cam piece 24b.

The cam portion 31 is given a desired cam shape by two cam surfaces 31 a and 31 b having different radii of rotation around the pin 26. The cam surface 31a rotates the cam piece 24b that rotates around the pin 26 when the cam piece 24b connected to the transmission member 23 by the driving means 22 is pulled in the webbing tension direction (in FIG. 1, the counterclockwise direction is shown). (Rotation) faces the bottom surface of the guide rail 24a. This cam surface 31a has a smaller distance to the pin 26 which is the central axis of rotation than the cam surface 31b, and when the cam piece 24b is pulled in the webbing tension direction of the cam piece 24b by the driving means 22, the cam piece 24b moves clockwise in FIG. When it is rotated, the cam surface 31a engages with the bottom surface of the guide rail 24a, but the cam surface 31a does not bite into the bottom surface of the guide rail 24a. Allow movement.

On the other hand, the cam surface 31b rotates the cam piece 24b that rotates around the pin 26 when the buckle support member 20 is pulled forward of the vehicle (in the direction of arrow A in FIG. 1) by the load acting on the webbing or the like. (Counterclockwise rotation in FIG. 1) faces the bottom surface of the guide rail 24a. This cam surface 31b has a larger distance to the pin 26 which is the rotation center axis than the cam surface 31a, and when the cam piece 24b rotates counterclockwise in FIG. 1, it meshes with the bottom surface of the guide rail 24a. The cam piece 24b is prevented from sliding along the longitudinal direction of the guide rail 24a.

Stopper portions 35, 36 are formed on both side wall portions of the guide rail 24a to limit the moving range of the cam piece 24b and the slide base 24d assembled to the guide rail 24a. These stopper portions 35, 36 form an arcuate outer contour with which the pin 26 abuts, and the stopper portion 35 provided on the front end side of the guide rail 24a is a cam piece to which the buckle support member 20 is connected. 24b is to be set to the initial position, and when the seat belt is normally worn, the pin 26 is in contact with the stopper portion 35. When the cam piece 24b and the slide base 24d are located at this initial position, the slide base 24d closes the limit switch 22c mounted on the lower surface on the front end side of the guide rail 24a, so that the pretensioner control not shown is performed. The means can detect that the buckle support member 20 is in the initial position.

On the other hand, the stopper portion 36 provided on the rear end side of the guide rail 24a sets the maximum amount of pulling in when the cam piece 24b is pulled in the webbing tension direction in an emergency of the vehicle. The maximum value of the retracted amount by is set to be slightly smaller than the stroke determined by the stopper portions 35 and 36.

Next, the operation of the pretensioner 21 of the first embodiment as described above will be described. In the pretensioner 21, the seat belt is worn by the occupant while the cam piece 24b is moved to the initial position where the pin 26 contacts the stopper portion 35. Then, when the vehicle is in an emergency, the drive means 22 is actuated, and the cam member 24b is pulled through the transmission member 23 in the webbing tension direction.

When the cam piece 24b is pulled in by the transmission member 23, the cam piece 24b is slightly rotated counterclockwise in FIG. 1 so that the cam surface 31a faces the bottom surface of the guide rail 24a (that is, the cam piece 24b). Although the portion 31 is in the state of being engaged with the bottom surface of the guide rail 24a), the cam surface 31a is not in the state of biting into the bottom surface of the guide rail 24a, so that the cam piece 24b is slidable on the guide rail 24a. The cam piece 24b moves to the rear end side of the guide rail 24a by the amount by which the cord 23a of the transmission member 23 is pulled in by the rotary drum 22a of No. 22, and the buckle support member 20 fixed to the cam piece 24b is used. Remove seat belt play.

After the completion of the pulling-in operation by the driving means 22, the force (in the direction of arrow A in FIG. 1) that pulls back the buckle support member 20 due to the load acting on the seat belt (for example, the inertial force of the occupant). When actuated, the cam piece 24b rotates counterclockwise in FIG. 1 due to the pulling back force acting on the buckle support member 20, and the cam surface 31b is pressed against the bottom surface of the guide rail 24a and meshes with it. As a result, the cam portion 31 and the bottom portion of the slide base 24d sandwich the bottom portion of the guide rail 24a, and the cam piece 24b is prevented from sliding on the guide rail 24a. Therefore, even if a load in the pullback direction acts on the buckle support member 20, the pullback is prevented.

In order to cancel the state where the cam portion 31 of the cam piece 24b meshes with the bottom surface of the guide rail 24a to prevent the cam piece 24b from sliding on the guide rail 24a, the cam portion 31 is released. Since it suffices to exert a slight rotational force on the cam piece 24b in the rotational direction opposite to the direction in which it engages with the bottom surface of the guide rail 24a (clockwise direction in FIG. 1), for example, an occupant may move the buckle support member 20. It can be locked by a simple operation such as a slight clockwise rotation in Fig. 1.

Further, the cam portion 31 meshes with the bottom surface of the guide rail 24a when the cam piece 24b is rapidly rotated counterclockwise in FIG. 1, so that the cam portion 31 moves counterclockwise in FIG. If the cam piece 24b is moved to the initial position without suddenly rotating, the cam piece 24b will not be prevented from sliding on the guide rail 24a. Therefore, after releasing the locked state, the cam piece 24b to which the buckle supporting member 20 is fixed can be easily returned to the initial state by the manual operation of the occupant or the pushing operation of the transmission member 23 by the driving means 22. it can.

That is, in the pullback prevention mechanism of the first embodiment, even if the seatbelt pretensioner 21 once operates, the initial state can be easily changed without requiring difficult work such as parts replacement and attachment position adjustment. It can be reset, which reduces the financial burden on the user due to replacement of parts. Therefore, the sensitivity of the acceleration detection means can be increased so that the pretensioner can be operated frequently, and the operating sensitivity of the pretensioner is increased by adding collisions at low speed as operating conditions of the pretensioner. It is possible to exert the effect with. In addition, since it is possible to easily reset without needing to replace parts, it is possible to actually check the operation when inspecting and servicing the vehicle.

Further, by increasing the sensitivity of the operation, it becomes possible to operate the pretensioner at a faster stage of the collision even in the case of a collision at the time of high-speed running, which allows the webbing retracting after the acceleration is detected. Since it is possible to omit the time required to judge the movement, more webbing can be wound around the winding shaft. Then, the amount of tightness of the webbing wound around the take-up shaft increases, and the time until the tension is generated in the webbing is substantially lengthened, so that the pretensioner may remove the seat belt play by shock. At the same time, the energy absorption at the time of collision can be improved.

In the first embodiment, the lower fitting of the seat belt, to which the buckle is fixed by the driving means in the emergency of the vehicle, is pulled in. However, for example, the upper fitting of the seat belt and the webbing itself near the fitting are retracted. May be drawn in through a predetermined metal fitting or the like. FIG. 5 is a schematic configuration diagram showing a pullback prevention mechanism 40 for a seat belt pretensioner according to a second embodiment of the present invention.

The pullback prevention mechanism 40 is configured to include a cylinder 42 in which the viscous fluid 41 is sealed, and a piston 43 capable of reciprocatingly sliding in the cylinder 42. A buckle support member 44 is attached to one end of the rod 43a of the piston 43, and a transmission member 45 is connected to the other end of the rod 43a. The transmission member 45 transmits the force for advancing and retracting the piston 43 in the cylinder 42 to the rod 43a, and like the transmission member 23 of the first embodiment, a tubular guide 45a, The guide 45a is provided with a cord 45b capable of advancing and retracting, and the cord 45b is connected to the same driving means (not shown) as in the first embodiment.

A large-diameter orifice 46 and a small-diameter orifice 47, which are pressure adjusting means, are formed through the piston 43 in an appropriate number in the piston moving direction. The large-diameter orifice 46 has a check valve 48 for blocking the flow of the viscous fluid 41 from one end side (that is, the buckle support member 44 side) of the piston 43 to the other end side (that is, the transmission member 45 side). Is installed.

In the pull-back prevention mechanism 40, the pulling force is transmitted to the piston 43 through the transmission member 45 when the driving means (not shown) performs the pulling operation in an emergency of the vehicle, and the piston 43 Moves in the cylinder 42 in the webbing tension direction. At this time, the check valve 48 opens, and the viscous fluid 41 can easily pass through the large-diameter orifice 46, so that the piston 43 smoothly moves in the cylinder 42 in the webbing tension direction. Therefore, the buckle support member 44 is driven in the webbing tension direction to eliminate the play of the seat belt.

After the retracting operation is completed, when a force in the retracting direction momentarily acts on the rod 43a via the buckle supporting member 44, the check valve 48 is closed to suddenly retract the piston 43. The movement of the buckle support member 44 is prevented, and the buckle support member 44 is prevented from being pulled back. However, when a force in the pullback direction is applied to the piston 43 slowly and continuously, the flow of the viscous fluid 41 can be ensured by the small diameter orifice 47, so that the piston 43 can be pulled back. That is, even if the pretensioner operates once due to the occurrence of a vehicle emergency, the piston 43 can be returned to the initial position by slowly and continuously exerting a force in the pulling-back direction on the rod 43a and the like. The initial state can be easily reset without the need for difficult work such as adjusting the mounting position.

Therefore, as in the case of the first embodiment, it is possible to utilize the pretensioner more effectively by aiming to increase the sensitivity of the operation including the collision at low speed as the operation condition of the pretensioner. It will be possible. In addition, by appropriately selecting the diameter of the small-diameter orifice 47 that allows the piston 43 to move in the pullback direction, the moving speed of the piston 43 in the pullback direction can be adjusted as desired, and the occupant can be provided when the vehicle is in an emergency. It is also possible to further enhance the energy absorbency that alleviates the impact that acts.

FIG. 6 is a schematic diagram showing a pullback prevention mechanism 50 for a seat belt pretensioner according to a third embodiment of the present invention. The pull-back prevention mechanism 50 of the second embodiment is that a piston 51 having a buckle support member (not shown) connected to a rod 51a is reciprocally slidable in a cylinder 53 containing a viscous fluid 52. Although commonly used, the cylinder 53 is provided with a fluid supply port 53a for supplying the viscous fluid 52 and a fluid discharge port 53b for returning the viscous fluid 52 to the fluid storage tank 54. A pump 55 for feeding the viscous fluid 52 from the fluid storage tank 54 and a check valve 56 for preventing reverse flow of the viscous fluid 52 from the fluid supply port 53a to the fluid storage tank 54 are provided in the fluid supply port 53a. It is arranged.

The fluid supply port 53a is for supplying the viscous fluid 52 to one end side of the piston 51 (the side to which the buckle support member is connected) to move the piston 51 in the webbing tension direction. It is provided at one end of the buckle support member 53. The fluid discharge port 53b is a viscous fluid existing on the other end side of the piston 51 (the side opposite to the side where the buckle support member is connected) when the viscous fluid 52 is supplied from the fluid supply port 53a. By returning the liquid amount corresponding to the supply amount from 52 to the fluid storage tank 54, it is possible to rapidly move the piston 51 in the webbing tension direction due to the supply pressure of the viscous fluid from the fluid supply port 53a. It is provided at the other end of the cylinder 53.

Further, a small diameter that allows the piston 51 to slide in the cylinder 53 by continuously exerting a force in the pullback direction (upward direction in FIG. 6) on the piston 51. The orifice 57 is provided. The orifice 57 is provided for manually returning the piston 51 to the initial position after the end of the vehicle emergency or for absorbing energy for absorbing the impact as described above, and is not equipped with a check valve.

Also in the case of the pullback prevention mechanism 50 of the third embodiment, the pretensioner can be easily reset as in the case of the first and second embodiments. Therefore, the operation condition of the pretensioner is set as follows. The pretensioner can be used more effectively by increasing the sensitivity of the operation including collision at low speed. Then, similarly to the pullback prevention mechanism 40 of the second embodiment, the moving speed of the piston 51 in the pullback direction can be adjusted by appropriately selecting the diameter of the small diameter orifice 57 that allows the movement of the piston 51 in the pullback direction. Etc. can be adjusted as desired, and the energy absorbency for alleviating the impact on the occupant during a vehicle emergency can be enhanced.

Further, in the case of the pullback prevention mechanism 50 of the third embodiment, if the vehicle equipped with the pretensioner is an automatic transmission vehicle using a torque converter, transmission oil is used as the viscous fluid 52 and the pump 55 is used. By adopting a configuration that also serves as a hydraulic pump equipped on the transmission side, the equipment can be simplified. Further, in the case of the pullback prevention mechanism 50, if the equipped vehicle is a large vehicle, it is possible to use the air brake air pressure as a drive source.

In each of the above embodiments, a motor or a pump is used as the driving means for retracting the seat belt attachment or the webbing near the attachment in an emergency, but other than magnetic force, spring members, etc. It is also possible to appropriately use the driving means.

[0049]

[Effect of device]

 According to the seat belt pretensioner of the present invention, the pullback preventing mechanism can be easily released, and the buckle supporting member can be easily returned to the initial position. Further, even if the pretensioner operates once, it can be easily reset to the initial state without the need for difficult work such as parts replacement and adjustment of the mounting position, and the economic burden on the user due to parts replacement etc. is reduced. .

That is, it is possible to increase the sensitivity of the acceleration detection means and frequently operate the pretensioner, and it is possible to increase the sensitivity of the operation including a collision at a low speed as a pretensioner operation condition. Therefore, it becomes possible to exert the effect under a wider variety of operational situations. Moreover, since the time required for determining the webbing retracting operation after the acceleration is detected can be omitted, more webbing can be wound around the winding shaft. Then, the amount of tightness of the webbing wound around the take-up shaft increases, and the time until the tension is generated in the webbing is substantially lengthened, so that the pretensioner shockfully removes the seat belt play. The energy absorption at the time of collision can be improved as well as when the energy is eliminated.

Therefore, by providing a good seatbelt pretensioner, the sensitivity of the acceleration detecting means can be increased by facilitating the resetting after the operation once, and the effect can be exerted in a wider variety of operating situations. it can.

[Brief description of drawings]

FIG. 1 is a front view of a main portion of a seat belt pretensioner according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of a main part of the seat belt pretensioner shown in FIG.

3 is a rear view of a main part of the seat belt pretensioner shown in FIG. 1. FIG.

FIG. 4 is a bottom view of the seat belt pretensioner according to the first embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a pullback preventing mechanism according to a second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a pullback prevention mechanism according to a third embodiment of the present invention.

[Explanation of symbols]

 10 buckle 20 buckle support member 21 seat belt pretensioner 22 drive means 23 transmission member 23a rope body 23b rope body guide 24 pullback prevention mechanism 24a guide rail 24b cam piece 24c bearing hole 24d slide base 26 pin 31 cam portion

Claims (1)

[Scope of utility model registration request] 1. A drive means for retracting a seat belt attachment or a webbing near the attachment in a webbing tension direction in a vehicle emergency, and a transmission for transmitting the operation of the drive to the attachment itself or the webbing near the attachment. In a seatbelt pretensioner for removing play of a seatbelt, the member and a pullback prevention mechanism for preventing a pullback portion from being pulled back by a load acting on the webbing after the pulling operation by the driving means is completed, The pullback prevention mechanism is rotatable on the guide rail fixed to the vehicle body, a slide base slidably mounted along the guide rail, and a slide base so that a cam portion slides on the guide rail. And a cam piece to which the transmission member is fixed and And a buckle support member to which the webbing is connected, wherein the cam portion of the cam piece allows the cam piece to slide on the guide rail when the cam piece rotates when being pulled in the webbing tension direction by the transmission member. In addition, the retractor for a seat belt is characterized in that when the cam piece suddenly rotates when the retracted portion is pulled back by the webbing, the cam piece meshes with the guide rail surface to prevent the cam piece from sliding on the guide rail.