JPH09164912A - Retractor for seat belt with pretensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve the shock of the windingly tightening drive force of a drive means at the start time of a pretensioner and turn a take up shaft in a webbing take up direction efficiently and smoothly. SOLUTION: A clutch ring 14 arranged on a take up shaft 4 and a clutch outer wheel 12 supported relatively and rotatably around an axial center are provided with a cam surface 12b for constituting a nearly wedge shape space between a clutch ring outer periphery surface and it and roller pins 10 arranged in the wedge shape space, which is movable in a clutch ring engaging direction. A planet gear device for the speed up rotation of the clutch outer wheel 12 by the rotation of the rotary disc is arranged between a rotary disc and the clutch outer wheel 12. A holder for obstructing the movement of the roller pins 10 is engagingly locked with the rotary disc through a fine connection part. When the clutch outer wheel 12 is speed up rotated for the rotary disc at the collision time of a vehicle, the fine connection part of a holder is broken, after the roller pins 10 are bitten into a clutch ring 14 and the cam surface 12b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 winding shaft in an emergency.

[0002]

2. Description of the Related Art Conventionally, a seat belt device for safely holding an occupant of a vehicle on a seat tends to reduce the winding force of the webbing by a retractor in order to reduce the occupant's feeling of wearing the webbing. However, when a large force is applied at the time of a collision, the play of the webbing is inevitably increased, and the restraint is delayed due to such a play of the webbing, and there is a possibility that the occupant cannot be effectively and safely restrained.

Therefore, in an emergency, in order to remove the slack of the webbing by pulling in the webbing and tensioning the webbing,
There is a seat belt device in which a pretensioner that instantly rotates the retractor winding shaft in the winding direction is incorporated. When such a pretensioner is incorporated in the retractor, the rotation driving member for transmitting the driving force of the driving means to the winding shaft to drive the rotation does not interfere with the rotation of the winding shaft during normal use. , When the pretensioner is not operating, the rotary drive member is disengaged from the take-up shaft, and when the pretensioner is operating, the rotary drive member is connected to the take-up shaft to transmit the rotational torque to the take-up shaft. A clutch mechanism having various configurations is provided between the winding shaft and the winding shaft.

For example, a pretensioner disclosed in Japanese Patent Laid-Open No. 57-128169 is a pulling member attached to a casing by a mooring device (clutch mechanism) so as not to engage with a belt shaft (winding shaft). When the accumulator (driving means) has a roller (rotational driving member) and operates in an emergency such as a vehicle collision, the pulling member roller overcomes the mooring force of the mooring device and is connected to the belt shaft. The shaft is tightened and rotated.

That is, during normal use, the rotation driving member is mounted by the clutch mechanism in a state of not engaging with the winding shaft, so that it does not interfere with the rotation of the winding shaft. Then, when the drive means is activated and the rotation driving member is driven to rotate in an emergency such as a vehicle collision, the rotation driving member is connected to the winding shaft via the clutch mechanism, and the winding shaft is integrally wound. Since the take-up and rotation are performed, the webbing is wound and tightened to remove the looseness.

[0006]

However, in the structure of the clutch mechanism such as the pretensioner disclosed in Japanese Patent Laid-Open No. 57-128169, the shearing force that supports the rotary drive member when the pretensioner is started. It is necessary to deform and shear the shearing member such as the pin,
The starting resistance is large, and a large driving force is required to deform and shear the shearing member with the pulling member roller in a stationary state.

Therefore, when the rotary driving member is rotationally driven by the driving means having a large driving force, the shearing member is sheared in a moment, but since the shearing member is sheared before the clutch mechanism is connected, The engagement of the clutch mechanism may not be constant due to rebound due to impact or fluctuation of belt tension. When the driving means is driven by the pressure of combustion gas such as explosive, the rotation driving member moves at high speed, so that the clutch mechanism is instantly connected. Because of this,
When rotating the take-up shaft that has a large inertial weight in a nearly stationary state, an excessive impact load is applied to each mechanism part, so the strength of each part must be sufficiently large, which increases the manufacturing cost. easy.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, and to mitigate the impact of the driving force for tightening the winding of the driving means at the time of starting the pretensioner, and efficiently and smoothly move the winding shaft in the webbing winding direction. It is an object of the present invention to provide a seat belt retractor with a pretensioner that has a good clutch mechanism that can be rotated.

[0009]

The object of the present invention is to eliminate the slack of the seat belt from the winding shaft by the driving means capable of transmitting the rotational torque to the winding shaft of the retractor via the rotating member. A retractor for a seat belt having a pretensioner that rotates in a direction, wherein a rotation driving member that is supported so as to be rotatable relative to a clutch ring disposed on the winding shaft is an outer periphery of the clutch ring. A cam surface that forms a substantially wedge-shaped space between itself and a surface; and a meshing element that is disposed in the wedge-shaped space and is movable in the clutch ring engagement direction. Is provided with a speed-increasing gear transmission for increasing speed by rotation of the rotating member, and is retained by the rotating member to prevent movement of the meshing element in the clutch ring engaging direction. The means engages the meshing element with the clutch ring outer peripheral surface and the cam surface in accordance with the difference in rotation angle between the rotary member and the rotary drive member that are rotationally driven in the event of a vehicle collision, and then releases the locked state with respect to the rotary member. It is achieved by a seat belt retractor with a pretensioner, which is characterized by being configured as follows.

As the speed increasing gear transmission, a sun gear formed by forming external teeth on the outer periphery of the rotary drive member,
A planetary gear device comprising an internal gear fixed to the retractor base and a carrier member serving as the rotating member and supporting the planetary gear arranged between the sun gear and the internal gear is preferable.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a front view of a seat belt retractor 1 with a pretensioner according to a first embodiment of the present invention, and FIGS. 2 to 4 are main parts of the seat belt retractor 1 with a pretensioner shown in FIG. FIG. 5 is an exploded perspective view, and FIGS. 5 and 6 are A of the seat belt retractor 1 with a pretensioner shown in FIG. 1.
FIG. 7 is a sectional view taken along the line A-A and a sectional view taken along the line B-B, and FIG. 7 is a sectional view taken along the line C-C of the pretensioner shown in FIG. 5.

The seat belt retractor 1 with a pretensioner has a take-up reel 7 around which a webbing 20 can be taken up or drawn out freely. Like the conventional retractor, the take-up reel 7 has its own take-up reel 7. By the winding spring device 5 connected to the winding shaft 4, the webbing 2
It is always urged in the direction of winding 0. Further, when the webbing 20 is to be pulled out at an acceleration of a predetermined magnitude or more, the emergency lock mechanism 2 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 driving means for rotating in the direction is arranged. The pretensioner 3 includes a clutch outer ring 12 which is a rotary drive member rotatably arranged around a clutch ring 14 fitted to one end of a winding shaft 4 which penetrates a base side wall 11a, and a gas generating member. A drive means 6 for rotationally driving the clutch outer ring 12 by a pinion gear 21 that is constantly meshed with a rack 25 that is pressed and driven by the gas pressure generated by a container 29, and the clutch outer ring 12 is accelerated by the rotation of the pinion gear 21. Therefore, it is provided with a planetary gear device 35 which is a speed increasing gear transmission device arranged between the pinion gear 21 and the clutch outer ring 12, and a control device (not shown) which operates the gas generator 29 in the event of a vehicle collision.

The clutch outer ring 12 is a cylindrical member which is rotationally driven by the drive means 6 via a planetary gear device 35, which will be described later, and a sun gear which meshes with the planetary gear 15 of the planetary gear device 35 is formed on the outer peripheral surface. External tooth 12a for
And four cam surfaces 12b forming a wedge-shaped space between the outer peripheral surface of the clutch ring 14 and the outer peripheral surface of the clutch ring 14 are formed at equal intervals along the circumferential direction. There is. Then, in each wedge-shaped space, a cylindrical roller pin 10 which is a meshing element movable in the clutch ring engaging direction so as to enable torque transmission between the clutch outer ring 12 and the clutch ring 14, and the roller. Roller pin holding pieces 9a of a holder 8 which is a holding means locked to a rotating disk 17 as a rotating member which rotates integrally with the pinion gear 21 in order to prevent the pin 10 from moving in the clutch ring engaging direction, 9b are provided respectively.

As shown in FIGS. 3 and 8, the holder 8 made of a synthetic resin material such as polyacetal and nylon or a metal material such as aluminum and zinc is paired with a circular hole through which the winding shaft 4 is inserted. Substrate portion 8a having a substantially disc shape having fixing portions 8b, 8b, and four pairs of roller pin holding pieces 9a, 9 vertically provided along the axial direction of the substrate portion 8a.
b, and is fixed to the inner surface of the rotating disc 17 by rivets 8f inserted into the mounting holes 8e of each fixing portion 8b and the locking holes 17b of the rotating disc 17. The fixing of the holder 8 to the rotary disc 17 is not limited to the fixing by the rivet 8f, but other fixing methods such as a patching stop dowel may be used.

Therefore, the roller pin holding pieces 9a, 9 are
The tip end of b is inserted into each wedge-shaped space of the clutch outer ring 12 arranged inside the holder 8 to hold the roller pin 10 in a non-engaged state with the outer peripheral surface of the clutch ring 14. Further, the roller pin holding pieces 9a, 9
A slit 8c is formed along the circumferential direction between the base plate portion 8a on which b is vertically installed and each fixing portion 8b provided with the mounting hole 8e, and a break is formed at an end portion of the slit 8c. A thin connecting portion 8d, which is a possible connecting means, is configured. Therefore, the base plate portion 8a on the inner side of the slit 8c on which the roller pin holding pieces 9a and 9b are vertically provided is released from the engagement state with respect to the rotating disc 17 by breaking the thin connecting portion 8d, and the clutch outer ring is released. It becomes possible to rotate integrally with 12. Then, the rotating disk 17 of the substrate portion 8a
The side surface serves as a sliding surface when the clutch outer ring 12 rotates.

That is, the roller pin holding pieces 9a, 9b
Is locked to the rotary disc 17 via a thin connecting portion 8d having a breakage portion at a portion other than the surface of the base plate 8a on the side of the rotary disc 17 which is a sliding surface when the clutch outer ring 12 rotates. Has been done. Further, the inner diameter of the clutch outer ring 12 is larger than the outer diameter of the clutch ring 14, and the roller pin 10 sandwiched by the roller pin holding pieces 9a and 9b of the holder 8 has a clearance with respect to the outer peripheral surface of the clutch ring 14. have. That is, the cam surface 12b of the clutch outer ring 12, the holder 8 and the roller pin 10
As described above, a clutch mechanism is formed between the clutch ring 14 and the clutch outer ring 12, and the roller pin 10 is securely held by the holder 8 in a state in which torque cannot be transmitted.

The pair of roller pin holding pieces 9a, 9b sandwich the roller pin 10 so as to face each other along the circumferential direction of the base plate portion 8a, and the roller pin 10 holds the clutch ring 14 and the clutch ring 14. Clutch outer ring 1
Its radial portion facing 2 is open. Therefore, a rotational driving force acts on the rotary disc 17 and the planetary gear device 35 accelerates and rotates the clutch outer ring 12 in the webbing winding direction, so that a difference in rotation angle occurs between the rotary disc 17 and the clutch outer ring 12. In this case, the roller pin 10 can be reliably fixed to the rotating disc 17. Therefore, the roller pin holding pieces 9a and 9b can regulate the movement of the roller pin 10 in the circumferential direction with respect to the rotating disc 17 until the roller pin 10 is securely bitten.

Moreover, when the clutch outer ring 12 rotates by a predetermined angle and the roller pin 10 is urged by the cam surface 12b toward the center of the winding shaft, the movement of the roller pin 10 in the biting direction may be hindered. The roller pin holding pieces 9a and 9b can be easily deformed so as not to exist. Further, the clutch outer ring 12 that has been rotated at an increased speed is rapidly driven to rotate in the webbing winding direction, but the moving speed of the roller pin 10 in the biting direction depends on the rotational speed difference between the rotating disk 17 and the clutch outer ring 12. Therefore, it is possible to gently engage the roller pin 10 and reduce the impact of the clutch connection.

After the roller pin 10 is securely engaged between the cam surface 12b of the clutch outer ring 12 and the outer peripheral surface of the clutch ring 14, the clutch outer ring 12 is further engaged.
Is driven to rotate in the webbing take-up direction, the thin connecting portion 8d of the holder 8 is broken and the fixing portion 8b moves to the substrate portion 8
Since a is separated, the roller pin 10 biting into the clutch ring 14 rotates integrally with the clutch outer ring 12 and the base plate portion 8a in the webbing winding direction. The clutch ring 14 includes the roller pin 10
It is a harder material, and its outer peripheral surface is subjected to knurling (knurled knurling) that facilitates biting, shot peening, spline processing, and the like.

That is, the webbing winding direction (indicated by an arrow X _{1 in} FIG. 2) around the clutch outer ring 12 by the driving means 6 described later
Direction), the roller pin 10
Is the cam surface 12b of the clutch outer ring 12 and the clutch ring 1
By engaging with the outer peripheral surface of the clutch 4, the clutch ring 14 and the clutch outer ring 12 are connected, and the rotational torque of the clutch outer ring 12 is transmitted to the winding shaft 4.

The planetary gear unit 35 has the internal teeth 1 of the planetary gear case 16 fixed to the outside of the base side wall 11a.
6a and the outer ring 12 of the clutch, and a planetary gear 15 and the rotating disk 17 as a rotating member that rotatably supports the planetary gears 15.
The rotating disk 17 is formed with a through hole 17a into which a pin 19 that rotatably supports the planetary gear 15 is press fitted, and a central hole 18 into which a pinion gear 21 is fitted. It is revolved by the rotating disk 17. Therefore, the clutch outer wheel 12 is rotated at an increased speed by the rotation of the pinion gear 21.

As shown in FIGS. 5 and 7, the drive means 6 includes a rack 25 having rack teeth 25a meshed with the pinion gear 21, and a cylinder 24 for movably receiving the rack 25. It has a gas generator case 28 that connects the tip end of the cylinder 24 and the gas ejection portion of the gas generator 29. The base end of the cylinder 24 is connected to a rack gear case 22 fixed to the outside of the planetary gear case 16. The rack gear case 22 is formed with a central opening 33 in which the pinion gear 21 is rotatably accommodated, and a guide concave portion 34 which partially communicates with the central opening 33 and slides and guides the rack 25. A plate 23 having an opening 23a through which the tip of the winding shaft 4 penetrates is arranged outside the rack gear case 22 so as to cover the pinion gear 21 and the rack 25.

At the end of the rack 25 on the gas generator case 28 side, a piston 27 that is slidable in the cylinder 24 together with a cushioning material 26 is provided.
The high-pressure gas generated by is transmitted to the piston 27 via the gas generator case 28. Back 25 of the rack 25
A cam surface 32 forming a wedge-shaped space is formed on the side wall portion of the guide recess 34 on the side facing b, and the guide recess 34 of the rack gear case 22 is formed in the wedge-shaped space.
The cylindrical roller pin 36 that restricts the relative movement of the rack 25 in the return direction (the direction of the arrow Y _{2 in} FIG. 5) with respect to the inner wall of the coil, and the coil spring 31 that biases the roller pin 36 in the rack engaging direction. The rack 25 is provided with a return preventing mechanism. Therefore, when the rack 25 moves in the webbing winding drive direction (the direction of the arrow Y _{1 in} FIG. 5), the roller pin 36 can move in the non-meshing direction against the urging force of the coil spring 31. It does not hinder the movement of the rack 25.

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. 6, since the clutch outer ring 12 and the roller pin 10 are 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 2 can be resisted against the spring force.
0 can be withdrawn freely.

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 retractor's emergency lock mechanism 2 operates and the winding shaft 4
Lock the rotation of. This prevents the webbing from extending, but the control device (not shown) causes the gas generator 2 to operate.
The rack 25 is not pushed because the 9 is not operated.

On the other hand, when a very large predetermined deceleration occurs such as during a vehicle collision, a control device (not shown) detects this deceleration and ignites the gas generator 29. The ignited gas generator 29 ejects the driving gas into the gas generator case 28. Then, the expansion pressure of the drive gas flowing into the cylinder 24 from the gas generator case 28 acts on the piston 27, and the piston 27 presses the rack 25 in the webbing winding drive direction via the buffer material 26.

When the rack 25 is pressed and driven in the arrow Y ₁ direction shown in FIG. 5, the pinion gear 21 meshed with the rack teeth 25a of the rack 25 moves in the webbing winding direction (the arrow X ₁ direction in FIG. 5). ) Is driven to rotate. Then, the rotary disc 1 that rotates integrally with the pinion gear 21.
7 also rotates in the direction of arrow X ₁ . The rotating disk 17 has an arrow X ₁
The planetary gear 15 that is revolved in the direction of the arrow X ₁ by rotating in the direction is the internal tooth 16a of the planetary gear case 16.
While engaging with, rotate the clutch outer ring 12 to the arrow X ₁
Rotate to speed up. Therefore, the rotation of the pinion gear 21 in the arrow X ₁ direction is transmitted by being accelerated by the planetary gear device 35.

The clutch outer ring 12 is rotated by the rotating disc 17
When the holder 8 fixed to the rotating disk 17 is rotated at an increased speed in the direction of the arrow X _{1 with} respect to the clutch outer ring 12
Rotate relative to. Therefore, the roller pin 1 held by the roller pin holding pieces 9a and 9b of the holder 8 is
0 moves in the clutch ring engaging direction by the cam surface 12b and surely bites between the outer peripheral surface of the clutch ring 14 and the cam surface 12b, so that the roller pin 10 connects the clutch outer ring 12 and the clutch ring 14 to each other. The rotational torque of the clutch outer ring 12 is transmitted to the winding shaft 4.

In the present embodiment, the number of roller pins 10 is four, and they are arranged to face each other in the radial direction. Therefore, the clutch ring 14 receives the force from the roller pins 10 without losing the balance. Therefore, roller pin 1
The force from 0 bites into the clutch ring 14 without being dispersed. As described above, it is preferable that the number of roller pins 10 is an even number (especially 4 to 6) and the rollers are arranged to face each other.

Immediately after being rotationally driven, the thin outer connecting portion 8d is broken on the clutch outer ring 12 in order to release the locked state of the roller pin holding pieces 9a and 9b of the holder 8 fixed to the rotating disc 17. The load for the pre-tensioner does not act, and the starting resistance of the rotary drive member at the time of starting the pretensioner becomes small. Further, the clutch outer ring 12 is further rotated by the rotating disc 17
When the roller pin 10 is rotated relative to the webbing winding direction and moves to a position where the roller pin 10 bites securely between the outer peripheral surface of the clutch ring 14 and the cam surface 12b, the clutch outer ring 12 of the clutch outer ring 12 passes through the roller pin 10. The rotational driving force is transmitted to the holder 8. At this time, the rotating disk 1
Roller pin holding piece 9 of holder 8 fixed to 7
The thin connecting portion 8 for releasing the locked state of a and 9b.
Although a load sufficient to break d acts on the clutch outer ring 12, the clutch outer ring 12 is accelerated and the kinetic energy is increased, and the roller pin 10 is surely bite to complete the connection of the clutch mechanism.

Therefore, as shown in FIG. 9, the clutch outer ring 12 can break the thin connecting portion 8d with a small loss to release the locked state of the roller pin holding pieces 9a and 9b from the rotating disc 17. In addition to this, the substrate portion 8a can be swiftly and integrally rotated. Further, the clutch outer ring 12 that has been rotated at an increased speed is rapidly driven to rotate in the webbing winding direction, but the moving speed of the roller pin 10 in the biting direction is the difference in rotational speed between the rotating disk 17 and the clutch outer ring 12. Therefore, it is possible to gently engage the roller pin 10 and reduce the impact of the clutch connection.

Therefore, the time delay from the start of the pretensioner to the start of the webbing entrainment can be reduced, and rebound due to the impact of the clutch connection and fluctuations in the belt tension will not cause the roller pin 10 to become caught. Further, when the clutch mechanism is connected, an excessive impact load is not applied to each mechanism part.

Furthermore, the pinion gear 2 is driven by the driving force of the rack 25 which is pressed by the expansion pressure of the driving gas.
When 1 is rotationally driven in the webbing winding direction, the clutch outer ring 12 that has been rotated at an increased speed drives the clutch ring 14 to rotate integrally in the arrow X ₁ direction via the roller pin 10 to wind the webbing 20. Since the winding shaft 4 is rotated in the direction, the webbing 20 is tightened and the slack of the seat belt is removed.

Holder 8 fixed to rotating disk 17
The broken portion of the thin connecting portion 8d for releasing the locked state of the roller pin holding pieces 9a, 9b is a sliding surface when the clutch outer ring 12 rotates as shown in FIG. 9 (separated base plate portion 8a Surface of the rotating disk and inner surface of the rotating disk 17)
Since the fracture surface is located on the outer peripheral surface of the base plate portion 8a, which is a portion other than the above, and the trace of the fracture does not remain on the sliding surface of the clutch outer ring 12, sliding when the clutch outer ring 12 rotates. The smoothness of the surface can be secured. Therefore, high-speed and smooth rotation of the clutch outer ring 12 is guaranteed.

When the pressing drive of the rack 25 due to the expansion pressure of the driving gas is stopped, the tension of the webbing 20 causes the take-up shaft 4 to move in the webbing pull-out direction (arrow X in FIG. 9).
_The clutch outer ring 12 and the pinion gear 21 also start reverse rotation. Then, the rack 25 tries to move relative to the inner wall of the guide recess 34 in the return direction (direction of arrow Y _{2 in} FIG. 5), but the roller pin 36 causes the back surface 25b of the rack 25 and the cam surface of the guide recess 34. By biting into 32, relative movement of the rack 25 in the return direction is restricted, so that the pinion gear 21 is prevented from reverse rotation. Therefore, even immediately after the belt tightening operation by the pretensioner 3 is completed, the drive means 6 can suppress the belt extension.

In the embodiment of the present invention described above, as a drive means for rotating the rotary disc 17 as a rotary member in the webbing winding direction, a revolving disc 17 is fixed to the rotary disc 17 via a pinion gear. The drive means of the type in which the rack capable of transmitting the rotation torque is pressed by the gas pressure is used for the winding shaft of the tractor, but the drive means is not limited to this. For example, the structure of the clutch mechanism such as the pretensioner in the present invention is a cylinderless type driving means for directly applying the expansion pressure of gas to the blade portion of the rotating piston as the driving means of the pretensioner for driving the rotating member, and , Applicable to any of so-called cylinder type driving means that uses the elastic force of a torsion coil spring or pulls and drives one end of a cable by the expansion pressure of gas acting on a piston slidably received in a cylinder Therefore, the driving means can be appropriately selected according to various conditions such as the retractor mounting position while sharing the basic constituent members, so that the versatility is high.

Further, the structure of the retractor for the seat belt with the pretensioner according to the present invention is not limited to the above embodiment, and it goes without saying that various forms can be adopted based on the gist of the present invention. The shape and configuration of the rotary drive member, the clutch ring, the meshing element, the cam surface, the holding means, the method of locking the holding means, the breakable connecting means, and the like can be appropriately changed. For example, a breaking portion for releasing the locked state of the roller pin holding pieces 9a, 9b serving as holding means to the rotating disc 17 when the pretensioner is activated is provided at the base of the rivet 8f and the roller pin holding pieces 9a, 9b. Is also good.

[0039]

According to the retractor for a seat belt with a pretensioner of the present invention, when the rotating member is rotationally driven at the time of a vehicle collision, the rotational driving is accelerated by the rotating member via the speed increasing gear device. The cam surface formed on the inner peripheral surface of the member causes the meshing element to move in the clutch ring engaging direction to be bitten between the cam surface and the outer peripheral surface of the clutch ring. Remains locked to the rotary member and is movable relative to the rotary drive member immediately after being rotationally driven. Therefore, the rotary drive member immediately after being rotationally driven is locked to the rotary member of the holding means. The load for releasing the state does not act, and the starting resistance of the rotary drive member at the time of starting the pretensioner becomes small.

Furthermore, when the rotation driving member is rotated at an increased speed with respect to the rotation member and a load necessary to break the breaking portion of the holding means acts on the rotation driving member, the rotation driving member is As the accelerating energy is increased and the kinetic energy is increased, the meshing element surely bites to complete the connection of the clutch mechanism. Therefore, the locked 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. Further, since the moving speed of the engaging element in the biting direction is the difference in rotational speed between the rotating member and the rotation driving member, the engaging element can be gently engaged and the impact of clutch engagement can be mitigated.

Therefore, it is possible to reduce the time delay from the start of the pretensioner to the start of the webbing entrainment, and the meshing element does not cause the meshing failure due to the rebound due to the impact of the clutch connection or the fluctuation of the belt tension. Further, when the clutch mechanism is connected, an excessive impact load is not applied to each mechanism portion, and the strength of each mechanism portion is increased more than necessary and the manufacturing cost is not increased.

In addition, since the structure of the clutch mechanism in the present invention is not limited by the driving means for the rotating member, the driving means can be appropriately selected according to various conditions such as the retractor mounting position while sharing the basic constituent members. You can choose. Therefore, the versatility is high, and the impact of the driving force for tightening the driving means at the time of starting the pretensioner is reduced,
It is possible to provide a seat belt retractor with a pretensioner equipped with a good clutch mechanism that can efficiently and smoothly rotate the winding shaft in the webbing winding direction.

[Brief description of the drawings]

FIG. 1 is a front view of a seat belt retractor with a pretensioner according to an embodiment of the present invention.

FIG. 2 is a part of an exploded arrow view of essential parts of the seat belt retractor with a pretensioner shown in FIG.

FIG. 3 is a remaining part of an exploded arrow view of a main part of the seat belt retractor with a pretensioner shown in FIG. 1.

FIG. 4 is the remaining part of the main part exploded arrow view of the seat belt retractor with pretensioner shown in FIG. 1.

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

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

7 is a cross-sectional view taken along the line CC of the pretensioner shown in FIG.

FIG. 8 is an enlarged perspective view of a main part showing a mounted state of the holder shown in FIG.

9 is a cross-sectional view of a main part for explaining an operating state of the clutch mechanism shown in FIG.

[Explanation of symbols]

1 Seat belt retractor with pretensioner 3 Pretensioner 4 Winding shaft 5 Winding spring device 6 Driving means 7 Winding reel 8 Holder 9a Roller pin holding piece 9b Roller pin holding piece 10 Roller pin 11 Retractor base 12 Clutch outer ring 14 Clutch Ring 15 Planetary Gear 16 Planetary Gear Case 17 Rotating Disk 19 Pin 21 Pinion Gear 22 Rack Gear Case 24 Cylinder 25 Rack 27 Piston 29 Gas Generator

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shu Ichikawa 12 Kirihara-cho, Fujisawa-shi, Kanagawa Japan Seiko Co., Ltd. (72) Inventor Kaharu Komatsu 12 Kirihara-cho, Fujisawa-shi, Kanagawa Japan Seiko Co., Ltd.

Claims (1)

[Claims] 1. A seat belt having a pretensioner for rotating a winding shaft in a direction in which a slack of a seat belt is removed by a driving means capable of transmitting a rotation torque to a winding shaft of a retractor via a rotating member. A rotary drive member supported by the clutch ring disposed on the take-up shaft and rotatable relative to the shaft center with a substantially wedge-shaped space between the clutch ring outer peripheral surface and the clutch ring. The cam surface and the meshing element that is disposed in the wedge-shaped space and is movable in the clutch ring engaging direction are provided, and the cam surface is increased in rotation between the rotary member and the rotary member by the rotation of the rotary member. Therefore, a speed-increasing gear transmission is provided, and the holding means that is locked to the rotating member and prevents the meshing element from moving in the clutch ring engaging direction is driven to rotate during a vehicle collision. The engagement state with respect to the rotary member is released after the meshing element is engaged with the outer peripheral surface of the clutch ring and the cam surface according to the rotation angle difference between the rotary member and the rotary drive member. Seat belt retractor with pretensioner.