JP2001180439A - Seat belt pretensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat belt pretensioner particularly ensuring high rigidity of a gear member in addition to miniaturizing a case and simplifying structure, and realizing structure for the purpose by the effective use of a clutch case. SOLUTION: This seat belt pretensioner 5 is provided with a gas generating device 20; a case 21 with a roller storing passage 24 and a gear storage part 25; five roller members 40; a gear member 50 and a clutch 60. A plurality of roller members 40 in the roller storing passage 24 are moved onto the gear storage part 25 side with gas led into the roller storing passage 24 from the gas generating device 20, and roller bodies 41 of the roller members 40 are successively meshed with a gear body 51 between a flange 42 and a gear base 52 constituting a clutch case of the gear member 50, to rotate the gear member 50 in a winding direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seatbelt pretensioner attached to a seatbelt retractor, and more particularly, in a vehicle emergency, a plurality of roller members are sequentially meshed with a gear member, and a winding shaft is wound together with the gear member in a winding direction. And a seat belt pretensioner for winding the webbing by forcibly rotating the webbing.

[0002]

2. Description of the Related Art Conventionally, a seat belt pretensioner has a winding shaft for winding a webbing for restraining an occupant, a housing for rotatably supporting the winding shaft, and an elastically urging spring for the winding shaft in the winding direction. In a vehicle emergency such as a vehicle collision, the winding shaft is forcibly rotated in the winding direction to wind up the webbing, thereby removing slack in the webbing. Usually, the seat belt retractor is provided with an emergency lock mechanism for locking the rotation of the winding shaft in the pull-out direction in the event of a vehicle emergency, in addition to the winding shaft, the housing, and the urging member. By removing the slack of the webbing by the tensioner, the emergency lock mechanism functions effectively, and the function of restraining the occupant by the webbing can be enhanced. In the normal state where the seat belt pretensioner does not operate,
The webbing can be pulled out and taken up freely.

[0003] As a conventional seat belt pretensioner, a gas generator for generating gas in the event of a vehicle emergency is provided, and one or more driving members are driven by the gas pressure to rotate the winding shaft in the winding direction. Various types that are operated have been put to practical use.

The seatbelt pretensioner disclosed in US Pat. No. 5,697,571 communicates with an elongated accommodating passage having one end connected to a gas generator, a gear accommodating portion communicating with the other end of the accommodating passage, and the gear accommodating portion. And a chain member housed in the housing passage, a gear member rotatably housed in the gear housing part, and coaxially coupled to the winding shaft. In the event of a vehicle emergency, the gas introduced from the gas generator into the storage passage causes the chain member to pass through the gear storage portion from the storage passage, move to the recovery portion, and be recovered. When the chain member passes through the gear housing portion, it meshes with the gear member, and the gear member rotates integrally with the winding shaft in the winding direction. Even if the chain member is maximally collected by the collection section, the chain member is in a state of meshing with the gear member.

The seatbelt pretensioner disclosed in Japanese Patent Application Laid-Open No. 11-208415 discloses a housing passage having one end connected to a gas generator, a sleeve housing portion communicating with the other end of the housing passage, and a recovery device communicating with the sleeve housing portion. A case having a passage, a large number of cylindrical rollers housed in a row in the housing passage, a sleeve rotatably housed in the sleeve housing portion and coaxially coupled to the winding shaft, and the like. In the event of a vehicle emergency, the gas introduced from the gas generator into the storage passage
A large number of cylindrical rollers move toward the sleeve housing portion along the housing passage. At this time, a large number of cylindrical rollers move while being sequentially press-fitted between the sleeve and the side wall of the sleeve accommodating portion facing the sleeve, and the frictional force causes the sleeve to rotate integrally with the winding shaft in the winding direction. . The large number of cylindrical rollers that have passed between the sleeve and the side wall move to the collection passage and are collected.

The seatbelt pretensioner shown in FIG. 7 of International Publication No. WO95 / 27638 has a ball accommodating passage connected at one end to a gas generator and a pinion accommodating portion communicating with the other end of the ball accommodating passage. A plurality of balls housed in a row in a ball housing passage, a pinion rotatably housed in a pinion housing portion, and coaxially coupled to a winding shaft. In the event of a vehicle emergency, gas introduced from the gas generator into the ball accommodating passage moves a large number of balls in the ball accommodating passage toward the gear accommodating portion, and these balls are sequentially meshed with the pinion and wound integrally with the pinion. The take-up shaft rotates in the take-up direction.

[0007]

Problems to be Solved by the Invention US Patent No. 5,697
The No. 571 seat belt pretensioner has the following problem. Since a collecting section for collecting the chain member must be provided in addition to the accommodating passage for accommodating the chain member, the case becomes large and the structure becomes complicated. In a normal state, the gear member rotates together with the winding shaft to change the phase, so that there is a possibility that the gear member and the chain member may not smoothly mesh with each other in an emergency of the vehicle. Since the frictional force acting between the chain member and the wall of the housing passage is large, the efficiency of transmitting the driving force by the gas generated by the gas generator to the gear member via the chain member is reduced. Therefore, it is necessary to use a high-power gas generator. Even if the chain member is maximally collected by the collection section, the chain member is engaged with the gear member, so that the gear member and the take-up shaft are rotated in the pull-out direction to release the restraint by the webbing. Becomes difficult. Due to the size of the case, the use of a chain member, the use of a high-power gas generator, and the like, the production cost becomes high.

The seat belt pretensioner disclosed in Japanese Patent Application Laid-Open No. 11-208415 has the following problems. Since a collecting passage for collecting a large number of cylindrical rollers must be provided in addition to the accommodating passage for accommodating a large number of cylindrical rollers, the case becomes large and has a complicated structure. High processing accuracy is required to improve the efficiency of transmitting the driving force of the gas generated by the gas generator to the sleeve via the cylindrical roller pressed into between the sleeve and the side wall of the gear housing. Since a large number of cylindrical rollers are provided, the number of parts is large, and the work of assembling these cylindrical rollers becomes difficult. When the cylindrical roller moves in the passage, there is a high possibility that the roller moves in the moving direction, the frictional force acting between the cylindrical roller and the wall of the passage increases, and the efficiency of transmitting the driving force to the gear member decreases. Therefore, it is necessary to use a high-power gas generator. Due to the size of the case, the increase in the number of parts and the assembling work load, the demand for high processing accuracy, the use of a high-output gas generator, etc., the production cost becomes high.

In the seat belt pretensioner of International Publication No. WO95 / 27638, it is not necessary to separately provide a collecting section for collecting a large number of balls in addition to a ball accommodating passage for accommodating a large number of balls in the case. And its structure can be simplified. However, in a normal state, the pinion rotates together with the winding shaft to change the phase, so that the pinion may not smoothly mesh with the ball in the event of a vehicle emergency.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the size of a case and simplify the structure of a seat belt pretensioner, to reliably rotate a winding shaft in a winding direction in a vehicle emergency, and to generate a gas generating device. Efficiently transmitting the driving force of the gas to the gear member, reducing the manufacturing cost, securing high rigidity of the gear member, and realizing the structure therefor by effectively utilizing the clutch case,
And so on.

[0011]

According to a first aspect of the present invention, there is provided a seat belt pretensioner configured to wind a webbing for restraining an occupant, a housing rotatably supporting the webbing shaft, and a winding shaft in a winding direction. A seatbelt pretensioner attached to a seatbelt retractor having a biasing member for biasing and rotating to wind the webbing by forcibly rotating a winding shaft in a winding direction in a vehicle emergency. A case fixed to a housing, having a roller storage passage having one end connected to the gas generation device, a gear storage portion communicating with the other end of the roller storage passage, and A plurality of roller members housed in a row in the roller housing passage and movable along the roller housing passage into the gear housing portion; and a roller member rotatably housed in the gear housing portion. A gear member meshable when moving from the roller accommodating passage to the gear accommodating portion, and a clutch that interlocks and connects the gear member and the take-up shaft by rotation of the gear member, wherein the roller member has a roller body and And a flange provided concentrically at one end of the roller body and having a diameter larger than that of the roller body, wherein the gear member is integrally provided on a gear body and an end face of the gear body opposite to the flange. A plurality of roller members in the roller accommodating passage are moved to the gear accommodating portion side by gas introduced from the gas generator into the roller accommodating passage, and a roller main body of these roller members is flanged. And the gear base of the gear member is sequentially meshed with the gear body to rotate the gear member in the winding direction.

In a normal state where the vehicle does not collide (before a vehicle emergency), the plurality of roller members are held in a state of being housed in the roller housing passage, and the gear member is held stationary with respect to the case. Also, in the normal state, the clutch is not functioning, so that the gear member and the winding shaft are not interlocked, and the winding shaft can rotate without being affected by the clutch. You can take it freely.

In the event of a vehicle emergency such as a vehicle collision, gas is generated from the gas generator, and the gas is introduced into the roller accommodating passage from one end. By the gas (gas pressure) introduced into the roller accommodating passage, the plurality of roller members in the roller accommodating passage are pushed toward the gear accommodating portion and move as a whole. When the plurality of roller members move from the roller accommodating passage to the gear accommodating portion, the roller bodies of these roller members sequentially mesh with the gear body between the flange and the gear base of the gear member, and the gear member moves in the winding direction. Rotate. The clutch functions as a result of the rotation of the gear member, whereby the gear member and the winding shaft are interlocked and connected. Thereafter, the winding shaft rotates integrally with the gear member in the winding direction. Since the rotation angle of the gear member required for the functioning of the clutch can be made small, the winding shaft rotates in the winding direction at an angle close to the rotation angle of the gear member. In this way, in a vehicle emergency, the webbing can be wound by forcibly rotating the winding shaft in the winding direction.

In this seat belt pretensioner,
Since the gear member rotates while holding the meshed state with the roller member, and there is no need to separately provide a collecting portion for collecting the plurality of roller members in the case, the case can be downsized and the structure can be simplified. In the normal state, the gear member is stationary irrespective of the rotation of the take-up shaft. By maintaining the stationary phase of the gear member at an appropriate phase, the first roller member is moved to the gear member in the event of a vehicle emergency. Mesh smoothly without causing strange collision,
Thereafter, the plurality of roller members can smoothly and sequentially mesh with the gear member, and the gear member can be rotated in the winding direction.

Since the frictional force acting between the roller member and the wall of the roller accommodating passage can be reduced, the driving force of the gas generated by the gas generator can be efficiently transmitted to the gear member via the plurality of roller members. Can be. Therefore, the size of the gas generator can be reduced. After the pretensioner is activated, the gear member can be freely rotated integrally with the take-up shaft, so that the gear member and the take-up shaft are rotated in the pull-out direction to release the restraint by the webbing. Becomes possible. In order to ensure proper operation of the seat belt pretensioner, high processing accuracy for forming the roller housing passage, the roller member, and the gear member is not required. The manufacturing cost can be reduced by downsizing the case, downsizing the gas generator, and eliminating the need for high processing accuracy.

The driving force caused by the gas pressure introduced into the roller accommodating passage first acts on the roller member at the most end of the roller accommodating passage, and the roller member passes through the flange of the adjacent roller member to most of the roller accommodating passage. The power is transmitted to all the roller members reaching the roller member on the other end side, the roller members are entirely moved to the gear housing portion side, and the driving force is transmitted to the gear member of the gear member via the roller main body of these roller members. It is transmitted to the main body.

The end surface of the flange having a larger diameter than the roller body of the roller member is guided by, for example, a wall or the like, so that the plurality of roller members can be prevented from tilting in the moving direction when moving while transmitting driving force to each other. . Therefore, the frictional force acting between the roller member and the wall of the roller accommodating passage can be reduced, so that the efficiency of transmitting the driving force to the gear member can be increased. Since the gear base is integrally provided on the end face of the gear body opposite to the flange, the rigidity of the gear member can be increased, and the roller body reliably meshes with the gear body without damaging the gear body.

According to a second aspect of the present invention, in the seat belt pretensioner according to the first aspect of the present invention, the gear member is accommodated in a gear accommodating portion coaxially with a winding shaft, and a gear base of the gear member corresponds to a clutch case of the clutch. It is characterized by comprising. In the event of a vehicle emergency, the clutch functions by the rotation of the gear member, and the gear member and the winding shaft are connected and interlocked. The high rigidity of the gear member can be ensured, and a structure therefor can be realized by effectively utilizing the clutch case.

According to a third aspect of the present invention, in the seat belt pretensioner according to the first aspect, an interlocking gear portion is formed on the gear base, and the interlocking gear portion meshes with the interlocking gear portion; A second gear member having a case and being accommodated in the gear accommodation portion coaxially with the winding shaft. In the event of a vehicle emergency,
The rotation of the gear member causes the second gear member to rotate via the interlocking gear portion, and the rotation of the second gear member functions as a clutch, so that the second gear member and the winding shaft are connected. The gear member and the winding shaft are interlocked and connected. By setting the gear ratio between the gear member and the second gear member, in a vehicle emergency, the rotation amount of the winding shaft (second gear member) with respect to the rotation amount of the gear member is increased to force the webbing to the winding shaft. It is possible to increase the amount of winding to be performed.

According to a fourth aspect of the present invention, there is provided the seat belt pretensioner according to any one of the first to third aspects, wherein the plurality of roller members and the plurality of roller bodies are arranged in a state where the plurality of roller members are in contact with each other by bringing the flanges into contact with each other. A plurality of teeth of the main body have substantially the same pitch. Therefore,
After the first roller member is engaged with the gear member, a plurality of roller members can be successively and smoothly engaged with the gear member.

According to a fifth aspect of the present invention, there is provided the seat belt pretensioner according to any one of the first to fourth aspects, wherein the roller receives the gas pressure of the gas generated by the gas generator at one end of the roller accommodating passage. A movable pressure receiving member for transmitting the pressure to the member is provided. The movable pressure receiving member receives the gas pressure of the gas generated by the gas generator, and the driving force is transmitted to the plurality of roller members via the movable pressure receiving member, and the plurality of roller members are moved together with the movable pressure receiving member toward the gear housing. Moving. By providing the movable pressure receiving member, the efficiency of transmitting the driving force by the gas pressure to the gear member can be increased.

According to a sixth aspect of the present invention, in the seat belt pretensioner according to the fifth aspect of the present invention, the bottom of the roller accommodating passage facing the end of the roller member opposite to the flange is formed to have a width smaller than the diameter of the flange. A pair of side walls of the roller accommodating passage are formed with a tapered portion having a width narrower from the vicinity of the flange toward the bottom.
In other words, the plurality of roller members can be assembled in the roller accommodating passage only in a fixed posture, and on the contrary, the assembling work can be made simple and reliable. In addition, since the contact area between the roller member and the side wall of the roller accommodating passage can be reduced and the frictional resistance acting between them can be reduced, the efficiency of transmitting the driving force to the gear member is further improved.

According to a seventh aspect of the present invention, in the seat belt pretensioner according to any one of the first to sixth aspects, the length of the roller accommodating passage is substantially equal to the length of a state where a plurality of roller members are all adjacent to each other. It is the same. That is, since the length of the roller accommodating passage can be minimized, the case can be made as small as possible.

An eighth aspect of the present invention is the seat belt pretensioner according to any one of the first to seventh aspects, wherein the seat belt pretensioner is mounted near a boundary between the roller accommodating passage and the gear accommodating portion. A leaf spring is provided to hold the gear member so as not to move to the gear housing portion and to allow the roller member to move to the gear housing portion through elastic deformation in a vehicle emergency. That is, in the normal state, the plurality of roller members can be fixedly held by the leaf spring so as not to move to the gear housing portion, and the roller members can be brought into contact with each other and maintained in a row to stand by. Also, in the event of a vehicle emergency, the movement of the roller member to the gear housing portion by the leaf spring is permitted through elastic deformation,
The roller member can be meshed with the gear member. That is, the reliability of the pretensioner can be improved.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. This embodiment is attached to a seat belt retractor having a winding shaft, a housing, and a biasing member, and in a vehicle emergency such as a vehicle collision, forcibly rotates the winding shaft in the winding direction to wind up the webbing. It is an example when the present invention is applied to a seat belt pretensioner. The description will be made with reference to the front and the left in FIG.

As shown in FIG. 1, a seat belt retractor 1 has a winding shaft 2 for winding up a webbing W for restraining an occupant.
And a winding drum 3 through which the winding shaft 2 is inserted and around which the webbing W is wound, a housing 4 rotatably supporting the winding shaft 2 and fixed to a vehicle body, the winding shaft 2 and the winding drum 3 A spiral spring (not shown) corresponding to an urging member for elastically urging in the winding direction indicated by an arrow, an emergency sensing mechanism (not shown) that operates in the event of a vehicle emergency, the winding shaft 2 and the winding in the event of a vehicle emergency It is constituted by a seat belt pretensioner 5 (hereinafter, referred to as a pretensioner 5) unique to the present invention for winding the webbing W by forcibly rotating the drum 3 in the winding direction.

The housing 4 has a left side wall 10, a right side wall 11, and a rear wall 12 integrally formed. The left and right ends of the winding shaft 2 are rotatably supported by the left side wall 10 and the right side wall 11. The rear wall 12 is fixed to the vehicle body with bolts (not shown) or the like. The take-up drum 3 is accommodated between the left side wall 10 and the right side wall 11, and the front upper ends of the left side wall 10 and the right side wall 11 are connected by a bar member 13 oriented in the left and right direction.

The winding shaft 2 is provided on the left side wall 1 of the housing 4.
A short knurled shaft 15 located immediately to the left of 0,
The knurled shaft 15 has a small-diameter shaft 16 extending leftward from the knurled shaft 15 and having a smaller diameter than the knurled shaft 15. The emergency sensing mechanism operates when the vehicle body suddenly decelerates and when the webbing W is suddenly pulled out. However, various emergency sensing mechanisms can be applied, and description thereof will be omitted.

The pretensioner 5 will be described in detail. As shown in FIGS. 1 and 2, the pretensioner 5
Is a gas generator 20 for generating gas in the event of a vehicle emergency.
A roller accommodating passage 24 having one end (front and lower end) connected to the gas generator 20 and a gear accommodating portion 25 communicating with the other end (rear and lower end) of the roller accommodating passage 24 and fixed to the housing 4. Case 21, five roller members 40 which are accommodated in a row in the roller accommodating passage 24 and are movable along the roller accommodating passage 24 into the gear accommodating portion 25, and are rotatably wound around the gear accommodating portion 25. The roller member 40 is accommodated coaxially with the shaft 2, and is moved from the roller accommodation passage 24 to the gear accommodation portion 2.
5, a gear member 50 that can mesh with the gear member 50, a clutch 60 that interlocks the gear member 50 and the winding shaft 2 by rotating the gear member 50, and the like.

The case 21 includes a case main body 22 in which the concave portions of the roller housing passage 24 and the gear housing portion 25 are formed from the left side.
And a case cover 23 that covers the case body 22 from the left side. The case cover 23 has a plurality of bolts 26 to
28, the left side wall 1 of the housing 4 is firmly fixed to the case body 22 by a plurality of through bolts 28.
0 together with the case body 22. Case 2
1, a roller accommodating passage 24 having a semicircular arc in a vertical section is formed, and a gear accommodating portion 25 having a substantially circular longitudinal section is formed below the roller accommodating passage 24. The rear upper end of the storage section 25 communicates.

Attachment part 26 at the lower front part of case body 22
A mounting hole 27 is formed from the lower side of the gas generating device 20, and the gas generating device 20 is mounted in the mounting hole 27 so as to be internally fitted.
A cap member 28 is screwed onto the lower part of the mounting portion 26 so as to be fitted into the mounting hole 27 so as to be fitted into the mounting hole 27. Case body 2
2, a gas passage 29 communicating the front lower end of the roller accommodating passage 24 with the mounting hole 27 is formed, and the front lower end of the roller accommodating passage 24 is connected to the gas generator 2 via the gas passage 29.
Connected to 0.

Although not shown, the gas generator 20 includes, for example, a high-pressure gas generating agent, an electrode, an ignition device, and the like. Upon receiving a signal from the sensor, the electrodes are energized to ignite or chemically react the high-pressure gas generating agent, thereby instantaneously generating a high-pressure gas.

A roller housing passage 24 is provided in the case body 22.
Is formed, and a spring mounting hole 32 is formed immediately above the gear housing 25. Seal groove 3
The case cover 23 is fixed to the case main body 22 in a state in which a seal member 34 having substantially the same shape is mounted on the case 1. Here, a leaf spring 35 is mounted near the boundary between the roller accommodating passage 24 and the gear accommodating portion 25, and a base end portion of the leaf spring 35 is attached to a spring attaching member 36 fitted in the spring attaching hole 32. It is mounted so as to be sandwiched between side walls forming the use holes 32.

The five roller members 40 are formed to have the same shape and the same size.
And a flange 42 which is provided concentrically at the left end of the roller body 41 and has a larger diameter than the roller body 41 (for example, about twice the diameter of the roller body 41).
Are integrally formed. For example, the roller body 41 and the flange 42 are formed to have substantially the same left and right lengths.
Are chamfered at the left and right outer peripheral edges.

As shown in FIG.
A bottom 24a facing the end of the roller member 40 opposite to the flange 42 (the right end of the roller body 41);
Has a pair of side walls 24b on both sides in the width direction. Bottom 24a
Is a flange 4 slightly longer than the diameter of the roller body 41.
2 is formed in a width smaller than the diameter. The pair of side walls 24b has a bottom 24 at the right half on the bottom 24a side.
The tapered portions 24c whose widths become narrower toward the a side are formed respectively.
The surface in the left half of the pair of side walls 24b opposite to the bottom 24a has a width slightly longer than the diameter of the flange 42 and is orthogonal to the plane parallel to the bottom 24a.

As shown in FIG. 2, five roller members 40
Are accommodated in the roller accommodating passage 24 in a state where the flanges 42 are in contact with each other and are adjacent to each other.
A movable pressure receiving member 45 made of hard rubber for receiving the gas pressure of the gas generated by the gas generator 20 and transmitting the gas pressure to the roller member 40 is accommodated in the front lower end portion. The movable pressure receiving member 45 is disposed in contact with the flange 42 of the roller member 40, and is in contact with the front lower end of the roller accommodating passage 24 in the normal state of FIG. 2 in which the pretensioner 5 does not operate.

The length of the roller accommodating passage 24 is substantially the same as the length in a state where all five roller members 40 including the movable pressure receiving member 45 are adjacent to each other. Now, in the normal state, the five roller members 40 are provided by the leaf spring 35 described above.
Is held so as not to be moved to the gear housing 25, and the roller member 40 is allowed to move to the gear housing 25 through elastic deformation in a vehicle emergency.

As shown in FIG. 4 to FIG.
Is a gear body 51 having five teeth, and the gear body 5
1, a clutch case (52) of the clutch 60, which is integrally provided on the end face (right end face) opposite to the flange 42.
And a through hole 53 through which the small-diameter shaft portion 16 of the winding shaft 2 is inserted is formed in the center of the gear base 52.

The gear body 51 is formed to have substantially the same left and right length as the roller body 41 of the roller member 40, and has a gear base 52.
Is formed to be approximately twice as long as the left and right sides of the gear body 51, the flange 42 of the roller member 40 and the gear base 5 of the gear member 50.
2, the roller body 41 and the gear body 51 are configured to mesh with each other. In a state where the five roller members 40 are adjacent to each other by bringing the flanges 42 into contact with each other,
Roller body 41 and gear body 51 of five roller members 40
Have substantially the same pitch.

As shown in FIGS.
Is a clutch case 5 composed of the gear base (52).
2, a synthetic resin retainer 61 accommodated in the clutch case 52, and a retainer 61 also accommodated in the clutch case 52 and formed at equal circumferential intervals on the retainer 61.
4 which are respectively held by two holding portions 62 so as to be movable in the radial direction.
The knurled shaft portion 15 of the winding shaft 2 is located inside the retainer 61 and the four roller pins 63 in the clutch case 52.

At the right ends of the four holding portions 62 of the retainer 61, engagement pieces 62a are integrally formed, respectively.
These engaging pieces 62a engage with four engaging holes on the right side wall that constitutes the gear accommodating portion 25 of the case 21, and the retainer 61
Has been fixed. On the inner surface of the clutch case 52, 4
Four cam surfaces 64 corresponding to the respective roller pins 63 are formed, and in a normal state, each roller pin 63 comes into contact with the most radially outer portion of the cam surface 64 and does not contact the knurled shaft portion 15. It is.

The gear member 50 is held at the initial phase shown in FIG. 2 by frictional resistance acting between the retainer 61 and the roller pins 63 and the like. In this initial phase, the phase in which the roller main body 41 of the first roller member 40 smoothly meshes with the gear main body 51 when the pretensioner 5 operates is set. It is assumed that the gear member 50 does not move in the axial direction even when the pretensioner 5 is operated, as well as when the retainer 61 is fixed to the case 21 due to the frictional resistance or the like.

In this clutch 60, as shown by the chain line in FIG. 5, when the gear member 50 rotates by a predetermined angle (for example, about 30 degrees) in the winding direction shown by the arrow, the gear member 50 moves with respect to the retainer 61. The relative rotation becomes impossible due to the interference between the predetermined portions, and the four roller pins 63 are pushed toward the respective axis sides by the four cam surfaces 64 and are strongly pressed by the knurled shaft portion 15 of the winding shaft 2, The gear member 50 and the take-up shaft 2 are connected and interlocked. Then, for example, the case 2 of the retainer 61 is
1 is released, and the winding shaft 2 rotates integrally with the gear member 50 including the retainer 61.

The small-diameter shaft portion 16 of the winding shaft 2 is
1 extends through the insertion hole 53 of the gear member 50 to the left side of the case 21. A spring case 70 accommodating the spiral spring is fixed to the left end side of the case 21 via two screws 72 via a low friction sheet 71, and the left end of the small diameter shaft portion 16 is connected to the spiral spring. (See FIG. 1). In the pretensioner 5, for example,
The movable pressure receiving member 45 and the retainer 61 of the clutch 60 are made of synthetic resin, and the other members are made of metal.
Part of the other members may be made of synthetic resin.

The operation and effect of the seat belt pretensioner 5 will be described. As shown in FIG. 2, in a normal state where the vehicle does not collide (before a vehicle emergency), the leaf spring 3
According to 5, the five roller members 40 are fixedly held in the roller accommodating passage 24 so as not to move to the gear accommodating portion 25, and the roller members 40 are kept in contact with each other in a line and stand by. Can be. In this normal state, since the clutch 60 is not functioning, the gear member 50 and the winding shaft 2 are not connected, and the winding shaft 2 can rotate without being affected by the clutch 60, and the webbing W Can be freely drawn and wound.

On the other hand, in the event of a vehicle emergency such as a vehicle collision, gas is generated from the gas generator 20 and the gas is supplied to the gas passage 2.
9 and is introduced into the roller accommodating passage 24 from its lower front end. Then, as shown in FIGS. 8 and 9, the movable pressure receiving member 45 receives the gas pressure of the gas generated by the gas generator 20, and the driving force is applied to the five roller members 40 via the movable pressure receiving member 45. Transmitted to the movable pressure receiving member 45 and 5
The roller members 40 move toward the gear housing 25 as a whole. The leaf spring 35 allows the movement of the roller member 40 from the roller accommodating passage 24 to the gear accommodating portion 25 through elastic deformation.

The five roller members 40 are connected to the roller accommodation passage 2.
The roller body 41 of the roller member 40 is moved from the flange 42 to the gear
The gear member 50 rotates in the winding direction by sequentially meshing with the gear body 51 between the gear bases 52. The rotation of the gear member 50 causes the clutch 60 to function and the gear member 50
The take-up shaft 2 is coupled to and interlocked with the take-up shaft 2. Thereafter, the take-up shaft 2 rotates in the take-up direction together with the gear member 50. Thereafter, as shown in FIG. 10, the flange 42 of the roller member 40 that first meshes with the gear member 50 abuts against the leaf spring 35 from the front side and is restricted in rotation, so that the rotation of the gear member 50 and the winding shaft 2 is controlled. Stops.

The rotation angle of the gear member 50 required for the functioning of the clutch 60 is reduced by a small angle (for example, about 30 degrees).
(Degree), the winding shaft 2 rotates in the winding direction at an angle close to the rotation angle of the gear member 50. In the normal state, the last roller member 40 meshes with the gear member 50, which has contributed to the rotation of the gear member 50, but the roller member 40 meshed with the gear member 50 first and the leaf spring 35 By the contact, the leaf spring 35 is elastically deformed and the last roller member 4
0 is in contact with the front end portion.

In this way, in the event of a vehicle emergency, the webbing W can be wound by forcibly rotating the winding shaft 2 nearly one turn in the winding direction instantaneously. That is, in the seat belt retractor 1, the pretensioner 5
In the event of a vehicle emergency, the slack in the webbing W can be removed immediately after that, so that the emergency lock mechanism functions effectively and the function of restraining the occupant with the webbing W can be enhanced.

After the pretensioner 5 is actuated, the guide member is held by the gear member 50 so that the leaf spring 35 does not move the roller member 40 meshed with the gear member 50 toward the roller accommodating passage 24. Therefore, the gear member 50 can be freely rotated integrally with the winding shaft 2. Therefore, it is possible to rotate the winding shaft 2 and the gear member 50 in the pull-out direction in order to release the restraint by the webbing W. As shown in FIG. 11, when the take-up shaft 2 and the gear member 50 are rotated in the pull-out direction immediately after the operation of the pretensioner 5, as shown in FIG. Only 40 is returned to the roller accommodating passage 24 by the leaf spring 35, but is held so as not to move to the gear accommodating portion 25 side, so that there is no problem in the above operation.

According to the pretensioner 5 described above, the gear member 50 rotates while maintaining the meshed state with the roller member 40, and the case 21 needs to separately provide a collecting portion for collecting the five roller members 40. Case 21
Can be reduced in size and the structure can be simplified. In the normal state, the gear member 50 is stationary irrespective of the rotation of the take-up shaft 2. By setting the initial phase of the gear member 50 to an appropriate phase, the first roller member 4 can be used in a vehicle emergency.
0 can be smoothly meshed with the gear member 50, and thereafter, the five roller members 40 can be smoothly meshed with the gear member 50 in order to rotate the gear member 50 in the winding direction.

Since the frictional force acting between the roller member 40 and the wall of the roller accommodating passage 24 can be reduced, the driving force of the gas generated by the gas generator 20 is reduced by the five roller members 40 through the gear member 50. Can be transmitted efficiently. Therefore, the size of the gas generator 20 can be reduced. After the operation of the pretensioner 5, the gear member 50 can be freely rotated integrally with the winding shaft 2, so that the winding shaft 2 and the gear member 50 are pulled out to release the restraint by the webbing W. In the direction. In order to ensure proper operation of the pretensioner 5, high processing accuracy for forming the roller accommodating passage 24, the roller member 40, and the gear member 50 is not required. The manufacturing cost can be reduced by downsizing the case 21, reducing the size of the gas generator 20, and eliminating the need for high processing accuracy.

The case cover 23 guides the end surface of the flange 42 having a larger diameter than the roller body 41 of the roller member 40, and the five roller members 40 move in the moving direction while transmitting the driving force to each other. It can be prevented from tilting. Therefore, since the frictional force acting between the roller member 40 and the wall of the roller accommodating passage 24 can be reduced, the efficiency of transmitting the driving force to the gear member 50 can be increased. A clutch case 52 is provided on an end surface of the gear body 51 opposite to the flange 42.
Is integrally provided, the rigidity of the gear member 50 can be increased, and the roller main body 41 reliably meshes with the gear main body 51 without damaging the gear main body 51. That is, the high rigidity of the gear member 50 can be ensured, and a structure therefor can be realized by effectively using the clutch case 52.

In a state where the five roller members 40 are adjacent to each other with the flanges 42 in contact with each other, the roller body 41 of the five roller members 40 and the five teeth of the gear body 51 have substantially the same pitch. After the first roller member 40 is engaged with the gear member 50, the plurality of roller members 40 can be successively and smoothly engaged with the gear member 50.

The roller member 4 receives the gas pressure of the gas generated by the gas generator 20 at one end of the roller accommodating passage 24 and receives the gas pressure.
Since the movable pressure receiving member 45 that transmits the driving force to zero is provided, the efficiency of transmitting the driving force due to the gas pressure to the gear member 50 can be increased. The length of the roller accommodating passage 24 is substantially the same as the length of a state in which all five roller members 40 including the movable pressure receiving member 45 are adjacent to each other.
, The case 21 can be made as small as possible.

The bottom 24a of the roller accommodating passage 24 facing the end opposite to the flange 42 of the roller member 40 is
2 and a tapered portion 24c whose width decreases from the vicinity of the flange 42 toward the bottom portion 24a on the pair of side walls 24b of the roller accommodating passage 24. The assembling work can be made simple and reliable, and the contact area between the roller member 40 and the side wall 24b of the roller accommodating passage 24 can be reduced to reduce the frictional resistance acting between them. Thus, the efficiency of transmitting the driving force to the gear member can be increased.

In the normal state, the five roller members 40 are fixedly held by the leaf spring 35 so as not to be moved to the gear accommodating portion 25, and the roller members 40 are maintained in a row to stand by for operation. In the event of a vehicle emergency, the movement of the roller member 40 to the gear accommodating portion 25 is allowed by the leaf spring 35 through elastic deformation, so that the roller member 40 can be meshed with the gear member 50. That is, the reliability of the pretensioner 5 can be improved.

Next, a modified example of the seat belt pretensioner 5 will be described. However, the same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted. 1] As shown in FIG.
The bottom 24 of the roller accommodating passage 24A facing the end opposite to 2
a is formed to have a width smaller than the diameter of the flange 42, and all of the pair of side walls of the roller accommodating passage 24a are tapered to become narrower toward the bottom 24a so that the outer peripheral edge of the right end of the flange 42 comes into contact. May be formed.

2) As shown in FIG.
Roller receiving passage 24 facing the end opposite to flange 42
The roller accommodating passage 24 </ b> B having a stepped recess whose cross-sectional shape is slightly larger than the roller member 40 may be formed so that the bottom 24 a of B has a width smaller than the diameter of the flange 42. 3) The number of teeth of the roller member 40 and the gear member 50 is not limited to five, but may be six or more. Also,
It is not impossible to reduce the number to four or less.

Next, a seat belt pretensioner 5A of another embodiment will be described with reference to FIG. still,
In this seatbelt pretensioner 5A, those basically the same as those in the above embodiment will be briefly described, and the structure of the seatbelt retractor other than the seatbelt pretensioner 5A will be basically the same as that in the above embodiment. Therefore, the same reference numerals are given and the description is omitted.

As shown in FIG. 15, the seat belt pretensioner 5A includes a gas generator 80, a roller housing passage 91 having one end (upper end) connected to the gas generator 80, and the other end of the roller housing passage 91 ( (A lower end) and a case 81 fixed to the left side wall 10 of the housing 4 and communicating with the gear housing 92 in a row in the roller housing passage 91 along the roller housing passage 91 in the gear housing 92. The roller members 82 rotatably housed in the gear housing portion 92 below the winding shaft 2 and can be engaged when the roller members 82 move from the roller housing passage 91 to the gear housing portion 92. Gear member 83, a second gear member 84 meshed with the gear member 83 and accommodated in the gear accommodating portion 92 coaxially with the winding shaft 2, and the gear member 83 is wound by the rotation of the gear member 83. And a clutch 85 like interlocking linking two.

The case 81 includes a case main body 90 in which the main parts of the roller housing passage 91 and the gear housing portion 92 are formed and has a gas supply pipe 93, and case covers 94 and 95 that cover the case main body 90 from both left and right sides. . The case cover 94 is fixed to the case body 9 by four bolts 96 and 97.
The case body 90 and the case cover 95 are fixed to the left side wall 10 of the housing 4 by two through bolts 97 among them. The roller accommodating passage 91 is formed linearly in the vertical direction, and a cap bolt 98 is screwed into the case main body 90 from above from the upper side so that the upper end side is airtight. By removing the cap bolt 98, the six roller members 82
And the like can be mounted in the roller accommodating passage 91.

A gas generator 80 is provided on the right side of the gas supply pipe 93.
Are mounted in an inner fitting manner, and the gas generator 80 is connected to the gas supply pipe 9.
A cap member 99 is screwed to the right end portion of the gas supply pipe 93 so as to be externally fitted in order to fix the gas supply pipe 93 to the gas supply pipe 93. Roller member 82
Has a roller body 100 and a flange 101 provided concentrically at the left end of the roller body 100 and having a larger diameter than the roller body 100. A movable pressure receiving member externally fitted with a hard rubber seal 102 for receiving the gas pressure of the gas generated by the gas generator 80 and transmitting the gas pressure to the roller member 82 at the upper end of the roller accommodating passage 91 above the roller member 82. 103 is accommodated, and a stopper 104 is accommodated between the movable pressure receiving member 103 and the cap bolt 98.

In the normal state, the stopper 104, the movable pressure receiving member 103, and the six roller members 82 are accommodated in the roller accommodating passage 91 in a state of being adjacent to each other. The length is substantially the same as the state in which all six roller members 82 including the member 103 are adjacent to each other. In this state, the stopper 104 is
3, a gas introduction space is formed on the upper side, and the gas passage and the roller accommodation passage 91 of the gas supply pipe 93 are introduced so that the gas generated by the gas generator 80 is introduced into the gas introduction space.
Is connected.

The gear member 83 is rotatably supported by a shaft 115 supported by the case 81. The gear member 83 has a gear main body 110 and a gear base 111 integrally provided on an end surface of the gear main body 110 opposite to the flange 101 of the roller member 82. 112 are formed. Gear body 110 is 6
And the roller members 82 are adjacent to each other with the flanges 101 contacting each other and having six teeth.
The six teeth of the roller body 100 and the gear body 110 have substantially the same pitch.

The second gear member 84 has an interlocking gear portion 120 that meshes with the interlocking gear portion 112 of the gear member 83, and a clutch case 121 of the clutch 85. Here, the gear ratio of the second gear member 84 to the gear member 83 is configured to be, for example, 1: 2. Clutch 85
Has a clutch case 121, a retainer 122, and four roller pins 123. And retainer 122 and roller pin
The gear member 83 is held at the initial phase together with the second gear member 84 by frictional resistance acting between the gears 123 and 123. This initial phase is set to a phase in which the roller body 100 of the first roller member 82 smoothly meshes with the gear body 110 when the pretensioner 5A operates.

The operation and effect of the seat belt pretensioner 5A will be described. In the event of a vehicle emergency, gas is generated from the gas generator 80, and the gas is introduced into the roller accommodating passage 91 through the gas pipe 93 from the upper end. Since the stopper 104 forms a gas introduction space above the movable pressure receiving member 103, the gas pressure of the gas can be reliably received by the movable pressure receiving member 103, and the driving force is transmitted through the movable pressure receiving member 103. The power is transmitted to the six roller members 82, and the six roller members 82 are moved downward toward the gear housing 92 as a whole together with the movable pressure receiving member 103.

The six roller members 82 are connected to the roller accommodation passage 9.
1 to the gear accommodating portion 92, the roller body 100 of these roller members 82
The gear member 83 rotates in the winding direction by sequentially meshing with the gear body 110 between the gear bases 111. The rotation of the gear member 83 causes the rotation of the second gear member 84 via the interlocking gear portions 112 and 120, and the rotation of the second gear member 84 causes the clutch 85 to function. The winding shaft 2 is connected, and the gear member 83 and the winding shaft 2 are linked and connected. Thereafter, the winding shaft 2 is linked with the rotation of the gear member 83.
Rotates in the winding direction.

According to the seat belt pretensioner 5A, by setting the gear ratio between the gear member 83 and the second gear member 84, the winding shaft 2 (the second By increasing the rotation amount of the gear member 84), the winding amount for forcibly winding the webbing W around the winding shaft 2 can be increased. Further, since the roller accommodating passage 91 is formed in a straight line, the gas generated by the gas generator can be prevented from leaking from the movable pressure receiving member 103 to the roller member 82 side as much as possible, and the driving force by the gas is reduced to six roller members The transmission can be efficiently performed to the gear member 83 via 82. Therefore, the size of the gas generator 80 can be reduced. Other operations and effects are substantially the same as those of the seatbelt pretensioner 5, and the description is omitted.

The seat belt pretensioner 5
5A, the roller member 8 is mounted near the boundary between the roller housing passage 91 and the gear housing portion 92, and has six roller members 8 in a normal state.
2 is held so as not to be moved to the gear housing portion 92, and in the event of a vehicle emergency, the gear housing portion 92 of the roller member 82 is held.
A spring may be provided to allow the movement of the spring through elastic deformation. Further, the shape of the roller accommodating passage and other structures can be implemented as in the case of the seat belt pretensioner 5 or a modification thereof.

It is to be noted that various modifications may be made to the above-described embodiment and other embodiments and their modifications without departing from the spirit of the present invention. The present invention can be applied to the seatbelt retractor described above.

[0072]

According to the seat belt pretensioner of the first aspect, as described above, the case can be reduced in size and the structure can be simplified, and the winding shaft can be reliably rotated in the winding direction in the event of a vehicle emergency. The driving force of the gas generated by the gas generator can be efficiently transmitted to the gear member, and the manufacturing cost can be reduced. In particular, the end surface of the flange having a larger diameter than the roller body of the roller member is guided by, for example, a wall or the like, so that the plurality of roller members can be prevented from tilting in the moving direction when moving while transmitting the driving force to each other. Therefore, since the frictional force acting between the roller member and the wall of the roller accommodating passage can be reduced, the driving force can be efficiently transmitted to the gear member via the plurality of roller members. Since the gear base is integrally provided on the end face of the gear body opposite to the flange, the rigidity of the gear member can be increased, and the roller body reliably meshes with the gear body without damaging the gear body.

According to the seat belt pretensioner of the second aspect, the gear member is accommodated in the gear accommodating portion coaxially with the winding shaft, and the gear base of the gear member constitutes the clutch case of the clutch. The clutch functions as a result of the rotation of the gear member, and the gear member and the winding shaft are connected and interlocked. The high rigidity of the gear member can be ensured, and a structure therefor can be realized by effectively utilizing the clutch case.

According to the seat belt pretensioner of the third aspect, an interlocking gear portion is formed on the gear base, the interlocking gear portion meshes with the interlocking gear portion, and the clutch case of the clutch. Since the second gear member accommodated in the gear accommodating portion is provided coaxially with the winding shaft, in the event of a vehicle emergency, the second gear member is rotated via the interlocking gear portion by the rotation of the gear member.
Is rotated, the clutch functions by the rotation of the second gear member, the second gear member and the winding shaft are connected, and the gear member and the winding shaft are interlocked and connected. By setting the gear ratio of the gear member and the second gear member, in a vehicle emergency,
By increasing the rotation amount of the winding shaft (second gear member) with respect to the rotation amount of the gear member, the winding amount for forcibly winding the webbing around the winding shaft can be increased.

According to the seat belt pretensioner of the present invention, the plurality of roller members and the plurality of teeth of the gear body have substantially the same pitch in a state where the plurality of roller members are adjacent to each other with the flanges in contact with each other. After the first roller member is engaged with the gear member, a plurality of roller members can be successively and smoothly engaged with the gear member.

According to the seat belt pretensioner of the fifth aspect, the movable pressure receiving member for receiving the gas pressure of the gas generated by the gas generator and transmitting the gas pressure to the roller member is provided at one end of the roller accommodating passage. The efficiency of transmitting the driving force due to the gas pressure to the gear member can be increased.

According to the seat belt pretensioner of the sixth aspect, the bottom of the roller accommodating passage facing the end of the roller member opposite to the flange is formed to have a width smaller than the diameter of the flange, and one pair of the roller accommodating passages is formed. The side wall has a tapered portion whose width becomes narrower from the vicinity of the flange toward the bottom side, so that the operation of assembling the plurality of roller members can be performed easily and reliably. Since the contact area can be reduced and the frictional resistance acting between them can be reduced, the efficiency of transmitting the driving force to the gear member is further improved.

According to the seat belt pretensioner of the seventh aspect, the length of the roller accommodating passage is substantially the same as the length of the state in which all of the plurality of roller members are adjacent to each other. Thus, the case can be made as small as possible.

According to the seat belt pretensioner of the present invention, in the normal state, the plurality of roller members are fixedly held by the leaf spring so as not to move to the gear accommodating portion, and these roller members are kept in contact with each other. You can wait. Further, in the event of a vehicle emergency, the movement of the roller member to the gear accommodating portion is allowed by the leaf spring through elastic deformation, so that the roller member can be meshed with the gear member. That is, the reliability of the pretensioner can be improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a seat belt retractor including a seat belt pretensioner according to an embodiment of the present invention.

FIG. 2 is a left side view of the seat belt pretensioner with a cover case removed.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a left side view of the gear member.

FIG. 5 is a right side view in which a gear member and a clutch are partially cut away.

FIG. 6 is a sectional view taken along line VI-VI of FIG. 5;

FIG. 7 is a left side view of a main part of the clutch.

FIG. 8 is a left side view of a main part of the seatbelt pretensioner (operation start).

FIG. 9 is a left side view of a main part of a seat belt pretensioner (a state in which a first roller member is meshed with a gear member).

FIG. 10: Seat belt pretensioner (operation completed)
It is a principal part left side view.

FIG. 11 is a left side view of a main part of the seatbelt pretensioner (a state in which the gear member is started to be rotated in the pull-out direction after the operation is completed).

FIG. 12 is a left side view of a main part of the seatbelt pretensioner (in a state where the gear member is further rotated in the pull-out direction after the operation is completed).

FIG. 13 is a longitudinal sectional view of a case near a roller accommodating passage according to a modification.

FIG. 14 is a longitudinal sectional view of a case near a roller accommodating passage of another modification.

FIG. 15 is an exploded perspective view of a part of a seat belt retractor including a seat belt pretensioner according to another embodiment.

[Explanation of symbols]

 W Webbing 1 Seat belt retractor 2 Winding shaft 4 Housing 5, 5A Seat belt pretensioner 20, 80 Gas generator 21, 81 Case 24, 24A, 24B, 91 Roller accommodation passage 24a Bottom portion 24b Side wall 24c, 24d Taper portion 25, 92 Gear housing portion 35 Leaf spring 40, 82 Roller member 41, 100 Roller body 42, 101 Flange 45, 103 Movable pressure receiving member 50, 83 Gear member 51, 110 Gear body 52, 111 Gear base 60, 85 Clutch 84 Second Gear member 112, 120 Gear section for interlocking

Claims (8)

[Claims] 1. A seat belt retractor comprising: a winding shaft for winding a webbing for restraining an occupant; a housing rotatably supporting the winding shaft; and a biasing member for biasing the winding shaft to rotate in a winding direction. A seat belt pretensioner for forcibly rotating a take-up shaft in a winding direction in a vehicle emergency to wind up a webbing; a gas generator for generating a gas in a vehicle emergency; one end of the gas generator; And a case fixed to the housing and having a gear housing communicating with the other end of the roller housing passage, and a case housed in a row in the roller housing passage. A plurality of roller members movable to the inside of the gear housing portion, and rotatably housed in the gear housing portion, the roller members being meshable when moving from the roller housing passage to the gear housing portion. A roller, and a clutch for interlockingly connecting the gear member and the winding shaft by rotating the gear member, wherein the roller member is provided concentrically at one end of the roller body and at one end of the roller body. The gear member has a gear body, and a gear base integrally provided on an end surface of the gear body opposite to the flange, and accommodates a roller from the gas generator. By the gas introduced into the passage, the plurality of roller members in the roller accommodating passage are moved toward the gear accommodating portion, and the roller bodies of these roller members are sequentially meshed with the gear body between the flange and the gear base of the gear member. A seat belt pretensioner configured to rotate the gear member in a winding direction. 2. The clutch according to claim 1, wherein the gear member is accommodated in a gear accommodating portion coaxially with a winding shaft, and a gear base of the gear member constitutes a clutch case of the clutch.
A seatbelt pretensioner according to item 1. 3. An interlocking gear section is formed on the gear base, the interlocking gear section meshes with the interlocking gear section, and a clutch case of the clutch, and the gear is accommodated coaxially with a winding shaft. The seat belt pretensioner according to claim 1, further comprising a second gear member housed in the portion. 4. The method according to claim 1, wherein the plurality of roller members and the plurality of teeth of the gear body have substantially the same pitch in a state where the plurality of roller members are adjacent to each other with the flanges in contact with each other. The seatbelt pretensioner according to claim 1. 5. A movable pressure receiving member for receiving a gas pressure of a gas generated by a gas generator and transmitting the gas pressure to a roller member is provided at one end of the roller accommodating passage.
The seat belt pretensioner according to any one of claims 1 to 4, wherein 6. A bottom portion of the roller accommodating passage facing the end of the roller member opposite to the flange is formed to have a width smaller than a diameter of the flange, and a pair of side walls of the roller accommodating passage are formed from the vicinity of the flange to the bottom side. The seat belt pretensioner according to claim 5, wherein a tapered portion having a reduced width is formed. 7. The sheet according to claim 1, wherein a length of the roller accommodating passage is substantially equal to a length of a state in which all of the plurality of roller members are adjacent to each other. Belt pretensioner. 8. A roller unit is mounted near a boundary between the roller housing passage and the gear housing unit, holds the plurality of roller members so as not to move to the gear housing unit in a normal state, and transfers the plurality of roller members to the gear housing unit of the roller member in a vehicle emergency. The seatbelt pretensioner according to any one of claims 1 to 7, further comprising a leaf spring that allows the movement of the seatbelt through elastic deformation.