JPH078110U - Seat belt retractor with pretensioner - Google Patents

Abstract

(57) [Summary] [Purpose] The versatility is high and the winding resistance can be efficiently and smoothly rotated in the webbing winding direction by reducing the starting resistance at the time of starting the pretensioner and the time delay until the start of webbing winding. A good one-way torque transmission mechanism is provided. [Structure] The clutch ring 14 disposed on the take-up shaft 4 and a rotary piston 31 rotatably supported relative to the clutch ring 14 form a substantially wedge-shaped space between the rotary piston 31 and the outer peripheral surface of the clutch ring 14. , A roller pin 15 disposed in the wedge-shaped space and movable in the clutch ring engaging direction, and disposed so as to be rotatable relative to the rotary piston 31 by a predetermined angle, and in the clutch ring engaging direction of the roller pin 15. And a holder 9 locked to the casing 6 to prevent the movement of the. When the vehicle collides, the rotary piston 31 is driven to rotate by a predetermined angle, and the roller pin is attached to the clutch ring 14 and the cam surface 32a.
After engaging 15 with each other, the locked state of the holder 9 with respect to the casing 6 is released.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a seat belt retractor having a pretensioner for removing looseness of a seat belt by winding a webbing around a retractor take-up shaft in an emergency.

[0002]

[Prior art]

 Conventionally, a seat belt device for safely holding an occupant of 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. However, the addition of the slack inevitably increases the play of the webbing, and such play of the webbing delays the restraint, so that the occupant cannot be restrained effectively and safely.

Therefore, in an emergency, there is a seat belt device in which a pretensioner that instantly rotates the winding shaft of the retractor in the winding direction is removed in order to remove the play of the webbing by pulling the webbing in and tensioning the webbing. . When such a pretensioner is installed in a retractor, the driving force transmission member for transmitting the driving force of the driving means to the take-up shaft to drive the rotation does not interfere with the rotation of the take-up shaft during normal use. As described above, when the pretensioner is not operating, the driving force transmitting member is disengaged from the winding shaft, and when the pretensioner is operating, the driving force transmitting member is connected to the winding shaft to transmit the rotational torque to the winding shaft. One torque transmission mechanism of various configurations is provided between the driving force transmission member and the winding shaft.

For example, a pretensioner disclosed in Japanese Patent Application Laid-Open No. 2-256549 discloses that a plurality of shoes facing an extension portion of a winding shaft are axially supported so as to mesh with and engage with the extension portion and a biasing means. The drive means is connected to one end of the cable wound around these shoes by urging the cable in a direction not to engage with the extension. That is, during normal use, the shoe, which is the driving force transmitting member, is biased by the biasing means in the direction in which it does not engage with the extension portion, and therefore does not interfere with the rotation of the winding shaft. Then, when the drive means is activated and the cable is pulled in an emergency such as a vehicle collision, the shoe is rotated in the direction of engagement with the extension portion by the winding tightening force of the cable to engage with the extension portion of the winding shaft. Therefore, the webbing is tightened by rotating the winding shaft.

Further, for example, a pretensioner disclosed in Japanese Patent Publication No. 2-10743 and the like has a clutch member that is attached to a casing by a shearing member in a state of not engaging with a winding shaft. The driving means is connected to a pulling member roller for forcibly controlling and shearing the shearing member and pressing the clutch member against the clutch extension of the winding shaft to engage the clutch member when it is rotationally driven in an emergency such as a collision.

That is, during normal use, the clutch member, which is a driving force transmitting member, is attached by the shearing member in a state of not engaging with the winding shaft, so that it does not interfere with the rotation of the winding shaft. . When the driving means is activated and the pulling member roller is driven to rotate in an emergency such as a vehicle collision, the pulling member roller shears the shearing member and engages the clutch member with the clutch extension portion of the winding shaft. The webbing is tightened because the winding shaft is integrally wound and rotated.

By the way, as the driving means for the pretensioner as described above, a so-called cylinder type driving means for pulling and driving one end of the cable by a driving force acting on a piston slidably received in the cylinder, There is a so-called cylinderless type drive means in which a rotary drive member (rotary piston) that is rotationally driven by a driving force such as gas expansion pressure or spring force pulls in and drives the winding shaft in the webbing winding direction in an emergency. The cylinder-less type driving means is advantageous in storing the vehicle because the winding shaft can be pulled in and driven in the webbing winding direction by the compact rotary driving member without requiring a long cylinder.

[0008]

However, in the structure of the one-side torque transmission mechanism such as the pretensioner disclosed in the above-mentioned Japanese Patent Laid-Open No. 2-256549 and the like, the engagement of the shoe with the extension portion due to the winding tightening force of the cable. The pretensioner drive means is not limited to the cylinder type drive means because it is rotated in the mating direction and engages with the extension of the winding shaft. A compact cylinderless type drive means is used. I can't.

On the other hand, in the configuration of the one-torque transmission mechanism such as the pretensioner disclosed in Japanese Patent Publication No. 2-10743, etc., the shearing member supporting the clutch member is deformed / sheared when the pretensioner is started. However, it requires a large driving force to deform / shear the shearing member with a stationary pulling member roller. Also, the strength of the shearing member must be sufficiently higher than the peak load that occurs during normal use, and as a result, the pretensioner causes a large loss at the time of starting, and the webbing winding performance and the time until the winding starts. It causes a delay.

Therefore, an object of the present invention is to solve the above-mentioned problems, and it is highly versatile, and the starting resistance at the time of starting the pretensioner and the time delay until the start of webbing entrainment are reduced to make the winding shaft smooth and efficient. Another object of the present invention is to provide a seat belt retractor with a pretensioner equipped with a good one-way torque transmission mechanism that can be rotated in the webbing winding direction.

[0011]

[Means for Solving the Problems]

 The above object of the present invention is to rotate the winding shaft in the direction in which the slack of the seat belt is removed by rotationally driving the rotation driving member capable of transmitting the rotation torque to the winding shaft of the retractor in the event of a vehicle collision. A seatbelt retractor having a pretensioner, in which a clutch ring disposed on a winding shaft and a rotation driving member supported so as to be relatively rotatable around an axis are provided between the clutch ring outer peripheral surface. A cam surface that forms a substantially wedge-shaped space, a driving force transmission member that is disposed in the wedge-shaped space and is movable in the clutch ring engaging direction, and is arranged so as to be rotatable relative to the rotation driving member by a predetermined angle. And a holding means locked to the casing so as to prevent the driving force transmitting member from moving in the clutch ring engaging direction. It is driven after engaging the driving force transmitting member to the clutch ring and the cam surface is achieved by the retractor for a seat belt with pretensioner to release the locked state with respect to the casing of the retaining means.

[0012]

[Action]

 According to the above configuration of the present invention, since the holding means locked to the casing prevents the driving force transmitting member from moving in the clutch ring engaging direction during normal use, the driving force transmitting member is prevented. The member does not interfere with the rotation of the winding shaft. When the rotary drive member is rotationally driven at the time of a vehicle collision, the drive force transmission member is moved in the clutch ring engagement direction, and the cam surface formed on the inner peripheral surface of the rotary drive member and the outer peripheral surface of the clutch ring. It is bitten by and. At the time of starting the pretensioner, the holding means remains locked to the casing and can move relative to the rotary drive member immediately after being rotationally driven, so that the rotary drive member immediately after being rotationally driven. Does not act on the load for releasing the locking state of the holding means to the casing, and the starting resistance of the rotary drive member at the time of starting the pretensioner becomes small.

Further, when the rotation driving member is driven to rotate by a predetermined angle and a load for releasing the locked state of the holding means acts on the rotation driving member, the rotation driving member is accelerated to generate kinetic energy. Since it is increasing, the holding state of the holding means can be released with a small loss, and the holding means can be quickly moved integrally with the rotation driving member, and the time from the start of the pretensioner to the start of webbing entrainment can be increased. The delay can be reduced.

[0014]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 are a side sectional view and a sectional view taken along the line AA of a principal portion of a seatbelt retractor 1 with a pretensioner according to a first embodiment of the present invention. The seatbelt retractor 1 with a pretensioner is equipped with a take-up reel 17 around which the webbing 20 can be taken up or pulled out freely. Like the conventional retractor, the take-up reel 17 is provided with the take-up reel 17. The webbing 20 is constantly urged in the winding direction by the winding spring device 5 connected to the winding shaft 4. Further, when the webbing 20 is to be pulled out at an acceleration of a predetermined magnitude or more, the emergency lock mechanism 12 prevents the winding shaft 4 from rotating, and the webbing 20 is prevented from being further pulled out.

Further, in the seatbelt retractor 1 with a pretensioner, the winding shaft 4 is removed from the slack of the seatbelt on one side wall 11a of the retractor base 11 formed in a substantially U shape. A pretensioner 3 provided with a cylinderless type driving device for rotating in a predetermined direction is provided. The pretensioner 3 includes a rotary piston 31 which is a rotary drive member rotatably arranged around a clutch ring 14 fitted to one end of a winding shaft 4 which penetrates the base side wall 11a, and a base. A casing 6 that is disposed outside the side wall 11a and that forms a substantially annular guide passage 22 for rotatably accommodating the rotary piston 31, and a drive gas for rotationally driving the rotary piston 31. A gas generator 16 for generating a gas and a control device (not shown) for operating the gas generator 16 in the event of a vehicle collision are provided.

The casing 6 is composed of a lower case 7 fixed to the base side wall 11 a and an upper case 8 fixed to the base side wall 11 a via the lower case 7. A gas generator 16 is built in a substantially L-shaped housing integrally formed below the upper case 8, and the gas generator 16 is defined by a partition wall 8b that closes a part of the guide passage 22. One end of the guide passage 22 and the gas ejection portion of the gas generator 16 communicate with each other through a gas conduit port 19. The gas generator 16 has a heater (not shown) incorporated in a case 25 that houses a gas generating agent 24 and is sealed to a frame. The heater is controlled by a controller (not shown) that detects a vehicle collision. Is ignited by the electric signal of.

The rotary piston 31 is provided with a cylindrical portion 32 that is supported so as to be rotatable relative to the clutch ring 14 about its axis, and a protruding portion radially outward from the cylindrical portion 32 to receive driving gas. The driving gas generated from the gas generator 16 acts on the blades 33 in the guide passage 22 to be rotationally driven. A cam surface 33b forming a wedge-shaped space is formed on the rotational movement direction side opposite to the pressure receiving surface 33a of the blade portion 33 that receives the expansion pressure of the driving gas, and the casing is formed in the wedge-shaped space. A cylindrical roller pin 13, which is a meshing element that restricts relative rotation of the rotary piston 31 in the webbing pull-out direction (clockwise direction in FIG. 1) with respect to the inner peripheral wall of the roller 6, is provided.

On the inner peripheral surface of the cylindrical portion 32, a plurality of cam surfaces 32 a forming a wedge-shaped space between the outer peripheral surface of the clutch ring 14 are formed at equal intervals along the circumferential direction. ing. Then, in each wedge-shaped space, a cylindrical roller pin 15 which is a driving force transmitting member movable in the clutch ring engaging direction so as to enable torque transmission between the rotary piston 31 and the clutch ring 14, A spring member 10 for urging the roller pin 15 in the clutch ring engaging direction and a holding portion 9a of a holder 9 for holding the roller pin 15 in the clutch ring engaging direction are provided. To be done.

The rotary piston 31 is sandwiched by the lower case 7 and the upper case 8 in the direction of the rotation axis, and is radially supported by the outer peripheral surface of the clutch ring 14, so that the rotary piston 31 of the clutch ring 14 is accommodated in the casing 6. It is arranged so that relative rotation is possible while sliding around the outer peripheral surface. Further, the rotary piston 31 has a concave portion formed on the outer peripheral surface thereof locked by a small projection 8a provided on the inner peripheral surface of the upper case 8 so as to be non-rotatably fixed to the casing 6. It is positioned so that it will not move due to vibration of the vehicle body. Of course, both members can be positioned by frictional engagement.

The holder 9 has an annular portion 9 b that is frictionally sandwiched between the outer surface of the upper case 8 and the bottom wall surface of the winding spring device 5 so as to be relatively rotatable, and is positioned in the casing 6, and the circular portion 9 b. A spring which is provided between the cam surface 32a and a plurality of holding portions 9a which are vertically installed on the annular portion 9b and whose tip portion is inserted into each wedge-shaped space of the rotary piston 31. The roller pin 15 biased in the clutch ring engaging direction by the member 10 is held in a state of not engaging with the outer peripheral surface of the clutch ring 14. Here, the frictional engagement force between the outer side surface of the upper case 8 and the bottom wall surface of the winding spring device 5 that prevents the holder 9 from moving in the clutch engagement direction opposes the biasing force of the spring member 10. It is large enough for

Further, the inner diameter of the cylindrical portion 32 is larger than the outer diameter of the clutch ring 14, and the roller sandwiched by the spring member 10, the cam surface 32 a of the rotary piston 31, and the holding portion 9 a of the holder 9 is provided. The pin 15 has a clearance with respect to the outer peripheral surface of the clutch ring 14. That is, the cam surface 32a of the rotary piston 31, the spring member 10, the holder 9, the roller pin 15 and the like constitute one torque transmission mechanism between the clutch ring 14 and the rotary piston 31. The pin 15 is in a state where torque cannot be transmitted by the holder 9 locked to the casing 6 by frictional sandwiching, the cam surface 32a of the rotary piston 31 non-rotatably locked to the small protrusion 8a, and the spring member 10. Held in. Therefore, during normal use, the rotary piston 31 does not interfere with the rotation of the clutch ring 14, and the webbing 20 can be freely pulled out and taken up from the retractor. On the other hand, when the rotational driving force in the webbing winding direction (the arrow X direction in FIG. 1) is generated in the rotary piston 31 by the drive gas generated by the gas generator 16, the roller pin 15 causes the cam of the rotary piston 31 to move. By biting between the surface 32a and the outer peripheral surface of the clutch ring 14, the clutch ring 14 and the rotary piston 31 are connected, and the rotary torque of the rotary piston 31 is transmitted to the winding shaft 4. ing.

Next, the operation of the seat belt retractor 1 with the pretensioner will be described. In the normal traveling state of the vehicle, as shown in FIG. 1, since the rotary piston 31 is not engaged with the clutch ring 14, the winding shaft 4 can freely rotate. Therefore, the webbing 20 can be wound by the biasing force of the winding spring device 5, and the webbing 20 can be pulled out against the spring force.

When a certain amount of deceleration such as sudden braking occurs in the vehicle, the occupant moves forward and tries to pull out the webbing 20 with some acceleration. At this time, the emergency lock mechanism 12 of the retractor operates to lock the rotation of the winding shaft 4. This prevents the webbing from extending, but the rotary piston 31 does not rotate because the control device (not shown) does not operate the gas generator 16.

On the other hand, when an extremely large predetermined deceleration occurs such as during a vehicle collision, a control device (not shown) detects this deceleration and ignites the gas generating agent 24 of the gas generator 16. The gas generator 16 to which the gas generating agent 24 is ignited ejects the driving gas into the gas conduit port 19. Then, the expansion pressure of the drive gas flowing into the guide passage 22 from the gas conduit port 19 acts on the pressure receiving surface 33a of the blade portion 33, and the rotary piston 31 moves in the webbing winding direction (the arrow X direction in FIG. 1). It is driven to rotate.

Then, as shown in FIG. 3, the small protrusion 8a, which has locked the rotary piston 31 non-rotatably, is released, and the rotary piston 31 rotates in the webbing winding direction. At this time, the holder 9 is frictionally sandwiched between the outer surface of the upper case 8 and the bottom wall surface of the winding spring device 5 and positioned in the casing 6, and each wedge-shaped space of the rotary piston 31. Has a circumferential length sufficient for the holding portion 9a of the holder 9 to move in the clutch ring engaging direction, the holder 9 rotates relative to the rotary piston 31 that rotates in the webbing winding direction. To do.

Therefore, the roller pin 15 biased in the clutch ring engagement direction by the biasing force of the spring member 10 becomes movable in the clutch ring engagement direction, and the cam surface 32 a of the rotary piston 31 and the clutch ring 14 are moved. Since the roller pin 15 bites into the outer peripheral surface, the roller pin 15 connects the clutch ring 14 and the rotary piston 31, and the rotational torque of the rotary piston 31 is transmitted to the winding shaft 4. Even if the roller pin 15 is not biased by the spring member 10 in the clutch ring engaging direction, the rotary piston 31 is rapidly rotated, so that the inertia force causes the roller pin 15 to move in the clutch ring engaging direction. It is movable and the spring member 10 can be omitted.

That is, the rotary piston 31 immediately after being rotationally driven has the holder 9 locked to the casing 6 by the frictional force between the outer surface of the upper case 8 and the bottom wall surface of the winding spring device 5. The load for releasing the locked state does not act, and the starting resistance of the rotary drive member at the time of starting the pretensioner becomes small. Then, when the rotational driving force is transmitted to the clutch ring 14 via the roller pin 15 and the rotary piston 31 is further rotated by a predetermined angle in the webbing winding direction, the holding portion 9a of the holder 9 is moved as shown in FIG. The rotary piston 31 comes into contact with the inner wall of the wedge-shaped space, and the rotational torque of the rotary piston 31 is transmitted to the holder 9. At this time, the load for releasing the locked state of the holder 9 locked to the casing 6 is rotated by the frictional force between the outer surface of the upper case 8 and the bottom wall surface of the winding spring device 5. Although acting on the piston 31, the rotary piston 31 is accelerated to increase the motion energy. Therefore, the rotary piston 31 can release the locked state of the holder 9 with a small loss, and the holder 9 can be swiftly and integrally rotated. Therefore, from the start of the pretensioner to the start of the webbing entrainment. The time delay can be reduced.

Further, when the rotary piston 31 is rotationally driven in the webbing winding direction by the expansion pressure of the driving gas, the rotary piston 31 forces the holder 9 to rotate via the roller pin 15 as shown in FIG. The clutch ring 14 is driven to rotate, and the winding shaft 4 is smoothly rotated in the winding direction of the webbing 20, so that the webbing 20 is tightened and the play is removed.

Then, when the rotation of the rotary piston 31 due to the expansion pressure of the driving gas stops in the webbing winding direction, the tension of the webbing 20 causes the winding shaft 4 to move in the webbing withdrawing direction (the arrow Y direction in FIG. 6). It rotates and the rotary piston 31 also starts reverse rotation. Then, as shown in FIG. 6, the blade portion 33 of the rotary piston 31 rotates relative to the inner peripheral wall of the casing 6 in the webbing pull-out direction, and the roller pin 13 causes the inner peripheral wall of the casing 6 and the cam surface of the blade portion 33. The rotary piston 31 is prevented from rotating in the reverse direction because it bites into the gap 33b. However, such reverse rotation of the winding shaft 4 in the webbing pull-out direction can be prevented also by the lock mechanism of the emergency lock mechanism 12, so which reverse rotation prevention method is to be used is appropriately selected according to various conditions. Just do it.

In this embodiment, as a driving means for driving the rotary driving member to rotate in the webbing winding direction, a cylinderless type driving means for directly applying the expanding pressure of gas to the blade of the rotary piston to drive the rotary piston. However, the elastic force of the torsion coil spring is used, or the so-called cylinder type driving means for pulling and driving one end of the cable by the expansion pressure of the gas acting on the piston slidably received in the cylinder is used. You can also do it.

A retractor 41 for a seat belt with a pretensioner according to a second embodiment of the present invention shown in FIG. 7 is wound around a base side wall 46a of one of the retractor bases 46 formed in a substantially U shape. A pretensioner 42 having a cylinder type driving device for rotating the shaft 4 in a direction in which the slack of the seat belt is removed is provided. The same members as those of the seat belt retractor 1 with a pretensioner of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The pretensioner 42 is a rotor 43, which is a rotary drive member that is rotatably arranged around the clutch ring 14 that is fitted to one end of the winding shaft 4 that penetrates the base side wall 46 a. A cable 49 wound around the rotor 43 and having one end connected to the connecting portion 45 of the rotor 43 via a wire end 50 and a piston 48 connected to the other end of the cable 49 are connected to a gas generator (not shown). The driving means is driven in the cylinder 47 by the driving gas, and the one-torque transmission mechanism similar to that of the first embodiment is formed between the clutch ring 14 and the rotor 43. .

Therefore, when an extremely large predetermined deceleration such as at the time of a vehicle collision occurs, a control device (not shown) detects this deceleration and operates the gas generator, so that the drive flowing into the cylinder 47 is driven. The piston 48 is rapidly moved upward (direction of arrow Z) by the pressure of the gas. The drive force of the piston 48 causes the cable 49 to be pulled rapidly in the arrow Z direction.

When the cable 49 is pulled, the pulling force drives the rotor 43 to rotate in the webbing winding direction (arrow W direction in FIG. 7). Then, the small projection (not shown) that has locked the rotor 43 non-rotatably is released, and the rotor 43 rotates in the webbing winding direction. Therefore, similarly to the seat belt retractor 1 with a pretensioner of the first embodiment, the pretensioner 42 reduces the starting resistance at the time of starting the pretensioner and the time delay until the start of the webbing entrainment to improve the efficiency of the winding shaft. The webbing can be rotated smoothly and smoothly.

That is, the configuration of the one-side torque transmission mechanism such as the pretensioner in the present invention can be applied to either the cylinder type drive means or the compact cylinderless type drive means as the drive means of the pretensioner. The versatility is high because the driving means can be appropriately selected according to various conditions such as the retractor mounting position while sharing the basic constituent members.

In each of the above-mentioned embodiments, the method of holding the holder 9 as the holding means by friction between the holder 9 and the casing 6 is used, but the present invention is not limited to this. For example, the holding means for preventing the movement of the roller pin 15 in the clutch ring engaging direction is constituted by a locking projection protruding from the inner wall of the casing 6, and the rotary piston 31 is wound by the webbing. After being rotated in a predetermined direction by a predetermined angle, the locking protrusion may be brought into contact with the inner wall of the wedge-shaped space of the rotary piston 31 and sheared to release the locked state.

Also in this case, the load for shearing the locking projection does not act on the rotary piston 31 immediately after being rotationally driven, and the starting resistance of the rotary piston 31 at the time of starting the pretensioner can be reduced. Further, when the rotary piston 31 is rotationally driven by a predetermined angle and a load for shearing the locking projection acts on the rotary piston 31, the rotary piston 31 is accelerated and the kinetic energy is increased. The locking projection can be sheared by the loss, and the time delay from the start of the pretensioner to the start of the webbing entrainment can be reduced.

Further, the configuration of the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various forms can be adopted based on the gist of the present invention. For example, a rotary drive member, a clutch ring, The shape and configuration of the driving force transmitting member, the cam surface, the holding means, the method of locking the holding means, and the like can be appropriately changed.

[0039]

[Effect of device]

 According to the seat belt retractor with a pretensioner of the present invention, when the rotary drive member is rotationally driven at the time of a vehicle collision, the drive force transmitting member is moved in the clutch ring engaging direction, and the inner peripheral surface of the rotary drive member is moved. It is made to bite between the cam surface formed on the surface and the outer peripheral surface of the clutch ring, but at this time, the holding means is still locked to the casing, and the rotation drive member immediately after the rotation drive is performed. Since the relative movement is possible, a load for releasing the locking state of the holding means with respect to the casing is not applied to the rotary drive member immediately after being rotationally driven, and the start of the rotary drive member at the time of starting the pretensioner is started. The resistance becomes smaller.

Further, when the rotary drive member is rotationally driven by a predetermined angle and a load for releasing the locking state of the holding means acts on the rotary drive member, the rotary drive member is accelerated to generate kinetic energy. Since it is increasing, the holding state of the holding means can be released with a small loss, and the holding means can be quickly moved integrally with the rotation driving member, and the time from the start of the pretensioner to the start of webbing entrainment can be increased. The delay can be reduced.

Further, since the configuration of the one-side torque transmission mechanism in the present invention is not limited by the drive means of the rotary drive member, the basic component members are made common and driven by various conditions such as the retractor mounting position. The means can be appropriately selected. Therefore, the versatility is high, and the winding resistance can be efficiently and smoothly rotated in the webbing winding direction by reducing the starting resistance at the time of starting the pretensioner and the time delay until the start of webbing winding. It is possible to provide a seat belt retractor with a pretensioner having a torque transmission mechanism.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view of essential parts of a seat belt retractor with a pretensioner according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of the seat belt retractor with a pretensioner shown in FIG.

FIG. 3 is a partially enlarged cross-sectional view for explaining an operation start state of the rotary piston shown in FIG.

FIG. 4 is a partial enlarged cross-sectional view for explaining an operation start state of the rotary piston shown in FIG.

5 is a partially enlarged cross-sectional view for explaining an operating state of the rotary piston shown in FIG.

FIG. 6 is a partial enlarged cross-sectional view for explaining an operation completed state of the rotary piston shown in FIG.

FIG. 7 is a cross-sectional side view of essential parts of a seat belt retractor with a pretensioner according to a second embodiment of the present invention.

[Explanation of symbols]

1 Seat belt retractor with pretensioner 3 Pretensioner 4 Winding shaft 5 Winding spring device 6 Casing 7 Lower case 8 Upper case 9 Holder 9a Locking part 10 Spring member 11 Retractor base 12 Emergency locking mechanism 13 Roller pin 14 Clutch Ring 15 Roller pin 16 Gas generator 17 Take-up reel 19 Gas conduit port 20 Webbing 22 Guide passage 31 Rotating piston 32 Cylindrical part 32a Cam surface 33 Blade part

Claims (1)

[Scope of utility model registration request] 1. A pretensioner for rotating a winding shaft in a direction in which slack of a seat belt is removed by rotationally driving a rotation driving member capable of transmitting a rotation torque to a winding shaft of a retractor in the event of a vehicle collision. A seat belt retractor provided with a clutch ring disposed on a winding shaft and a rotation drive member supported so as to be relatively rotatable about an axis, between the clutch ring and the outer peripheral surface of the clutch ring. A cam surface that forms a space, a driving force transmitting member that is disposed in the wedge-shaped space and is movable in the clutch ring engaging direction, and a driving force transmitting member that is rotatable relative to the rotation driving member by a predetermined angle and is driven. Holding means locked to the casing to prevent the force transmitting member from moving in the clutch ring engaging direction, and the rotation driving member is rotated by a predetermined angle in the event of a vehicle collision. After engaging the driving force transmitting member to the latch ring and the cam surface, the holding means of the retractor for a seat belt with pretensioner for releasing the locked state relative to the casing.