JP2000203384A - Pretensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretensioner cheap in manufacturing cost and realizing a compact structure. SOLUTION: A winding shaft 3 fixed on a reel is penetrated into the inside of a pretensioner 1. A sleeve 25 is attached on the winding shaft 3. The inner end part 36a of a strip 36 is inserted and fixed to a groove 25a of the sleeve 25. The closer part to the inner end part of the strip 36 is wound several times around the outer circumference of the sleeve 25. An egg-shaped piston 23 is mounted on the outer end part of the strip 36. On the other hand, a gas generator 15 is provided in a pressure vessel 13. The pressure vessel 13 is communicated with a steel hollow pipe 17. The pipe 17 is curved in U shape and its inside serves as a passage for moving of the piston 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretensioner incorporated in a seat belt device for restraining an occupant to a seat of a vehicle or the like and urgently rotating a winding shaft of the seat belt in a winding direction. In particular, it relates to a pretensioner that can be manufactured at a low cost and realize a compact structure.

[0002]

2. Description of the Related Art In recent years, seat belt devices equipped on vehicles such as automobiles have been increasingly equipped with a pretensioner. The pretensioner urgently rotates a reel (winding shaft) around which a seat belt is wound in a winding direction at the time of a collision of a vehicle to remove the slack of the belt and apply tension to the belt. A device for driving the pretensioner generally ignites explosives based on a detection signal transmitted at the time of a vehicle collision, and drives the reel rotating mechanism by the gas pressure generated thereby.

[0003] Such a pretensioner is disclosed in, for example, Japanese Patent Publication No. 2-10743 and Japanese Patent Application Laid-Open No. 10-8679.
No. 1 is known.

[0004] The pretensioner disclosed in Japanese Patent Publication No. Hei 2-10743 is equipped with an animal power device (drive device) such as an air cylinder that operates when a vehicle collides. This animal powerer is connected to a bobbin-shaped roller through a pulling member such as a flexible rope. This roller is connected to a belt shaft that winds the belt via a clutch. In particular, the pulling member and the roller are connected as follows. That is, the roller has a hole along the tangential direction and a screw hole perpendicular to the hole. A screw pin is screwed into the screw hole. The pulling member is compressed and deformed by the screw pin and fixed to the roller with the end inserted into the hole.

[0005] In this pretensioner, when the raising device operates at the time of a vehicle collision, the raising device pulls the pulling member.
As a result, the roller rotates, the clutch engages, and the roller and the belt shaft are connected. Further, when the pulling force of the animal power device acts on the pulling member and the roller rotates, the rotation of the roller is transmitted to the belt shaft. Thereby, the belt is wound in the winding direction.

On the other hand, the pretensioner disclosed in Japanese Patent Application Laid-Open No. 10-86791 has a driven shaft protruding from a reel around which a belt is wound. A rotating ring is coaxially arranged on the driven shaft via a clutch mechanism. A steel tape is attached around the rotating ring. The tape is stored in a storage chamber, and gas is supplied to the storage chamber by a gas generator.

When the gas generator is ignited at the time of a vehicle collision, gas pressure is supplied into the accommodation chamber, and the pressing force of the gas acts to press the tape. Then, the rotating ring rotates via the tape, the clutch engages, and the rotating ring and the driven shaft are connected. When the pressing force of the gas acts on the tape and the rotating ring rotates, the rotation of the ring is transmitted to the driven shaft, and the belt is wound in the winding direction.

[0008]

However, the pretensioners disclosed in the above publications have the following problems. The pretensioner disclosed in Japanese Patent Publication No. 2-10743 uses a rope or a wire as a pulling member. These ropes and wires are expensive parts, and need to be replaced with other parts in order to reduce costs.
Further, the connecting portion for connecting the rope or the wire to the roller has a complicated mounting structure as described above. There is a demand for a simpler and more compact structure of this joint. On the other hand, in the pretensioner disclosed in Japanese Patent Application Laid-Open No. 10-86791, gas pressure is supplied to almost the entire area of the inside of the pretensioner (tape storage chamber), and the internal structure is complicated. The complexity of this structure has led to high costs.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a pretensioner capable of realizing a compact structure with a low manufacturing cost.

[0010]

In order to solve the above-mentioned problems, a pretensioner according to a first aspect of the present invention provides a pretensioner that applies a pretension to a belt by rotating a winding shaft of a seat belt in a winding direction in an emergency. A tensioner;
A sleeve connected to the winding shaft via a clutch, a strip having one end locked to the sleeve,
A piston fixed to the other end of the strip, a passage through which the piston travels, and an accelerator for moving the piston in the passage, wherein one end of the strip is wound on the sleeve. Features. Strips have a lower material cost than ropes and wires that are joined together. In addition, since there is no thickness, the entire device can be downsized. Furthermore, since one end side of the strip is wrapped around the sleeve to hold the strip end locked on the sleeve by the strip itself, the end is firmly fixed. Therefore, the locking structure at the end of the strip is simple.

In the pretensioner according to the first aspect of the present invention, it is preferable that a groove is formed in the sleeve, and one end of the strip is inserted into the groove. Since it is an inexpensive and simple part / structure, the manufacturing cost is reduced. Also, assembly is easy. Alternatively, the end of the strip may be fixed to the sleeve with an adhesive or an adhesive tape.

Also, a pretensioner according to a second aspect of the present invention is a pretensioner which applies a pretension to a belt by rotating a winding shaft of a seat belt in a winding direction in an emergency; A strip fixed at one end to the sleeve, a piston fixed to the other end of the strip, a passage for the piston, and an accelerator for moving the piston in the passage. And wherein the passage is curved. Since the passage is curved, the size is reduced as compared with a straight one. Therefore, the device as a whole has a compact structure.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are diagrams showing one embodiment of the present invention. FIG. 1A is a front sectional view showing a state before operation of a pretensioner according to the present embodiment, and FIG. 1B is an enlarged detailed view of a joint portion between a sleeve and a strip. FIG.
FIG. 2 is a front sectional view showing a state after the operation of the pretensioner. FIG. 3 is an enlarged exploded view of the joint between the strip and the piston.

The pretensioner 1 shown in FIGS. 1 to 3 is incorporated in a seat belt retractor. The seat belt retractor includes a reel on which the belt is wound, a frame for rotatably supporting the reel, a return spring for urging the reel in a winding direction, and a reel for pulling the reel in a belt withdrawing direction when the vehicle is suddenly decelerated. An emergency lock mechanism for preventing rotation is provided. Although not shown, the components of the seat belt retractor are conventionally known.

A take-up shaft 3 fixed to the reel passes through the inside of the pretensioner 1. This winding shaft 3
Are provided along the axis of the reel, and rotate synchronously with the reel. At the upper part of the pretensioner 1, a pressure vessel (accelerator) 13 is attached. The pressure vessel 13 is made of a die-cast member made of aluminum and zinc. The pressure vessel 13 is screwed to a retractor base (not shown). A gas generator 15 is provided in the pressure vessel 13. The gas generator 15 ignites an explosive based on a detection signal transmitted at the time of a vehicle collision and supplies gas pressure to the inside of the pressure vessel 13.

The right end of the pressure vessel 13 in FIG. The pipe 17 is a hollow member made of iron. The pipe 17 is curved in a U-shape. The left end (the left end in FIG. 1A) communicates with the inside of the pressure vessel 13, and the right end (the right end in FIG. 1A).
The side is open. The inside of the pipe 17 is a passage 18 in which a piston described later moves. Since the pipe 17 (passage 18) is curved as described above, the size is reduced as compared with a straight pipe, and the entire apparatus has a compact structure. As the pipe 17, a pipe obtained by bending a steel pipe can be used.

On the other hand, a hollow cylindrical sleeve 25 having a clutch mechanism 30 is attached to the winding shaft 3. The clutch mechanism 30 transmits the rotational driving force of the sleeve 25 to the winding shaft 3 only when the pretensioner operates, and has a conventionally known structure (Japanese Patent Application Laid-Open No. 10-86791).
Or the structure disclosed in Japanese Patent Publication No. 2-10743 / 1995).

The sleeve 25 has a groove 25a carved from the surface toward the axis. This groove 25a
It extends parallel to the axis of the sleeve 25. This groove 25a
As shown in FIG. 1 (b), an inner end 36a of a stainless steel strip 36 is inserted and fixed in the nip. The portion near the inner end of the strip 36 is wound around the outer periphery of the sleeve 25 a plurality of times.
Since the strip end 36a locked on the sleeve 25 is pressed by the strip 36 itself, the end 36a is firmly fixed. Therefore, the locking structure of the strip end 36a is simple. The length of the strip 36 is determined in consideration of the length of the pipe 17 (the length of the passage 18) and the diameter of the sleeve 25.

On the other hand, the egg-shaped piston 23 is attached to the outer end of the strip 36. Same piston 23
Are the two symmetrical halves 21, 2 as shown in FIG.
2 is provided. The half portions 21 and 22 are formed with shallow grooves 21a and 22a respectively on opposing surfaces. The outer end of the strip 36 is held between the grooves 21a and 22a. The outer ends of the halves 21, 22 and the strip 36 have holes 21b, 22
b, 36b are formed. And these holes 21
By inserting the pin 27 into the b, 22b, and 36b, the half portions 21, 22 and the strip 36 are integrally connected and fixed. As described above, the mounting structure of the strip 36 and the piston 23 is simple, and the cost of parts is reduced.

The size of the piston 23 is slightly smaller than the inside of the pipe 17 (that is, the passage 18). The egg-shaped piston 23 makes it easier to follow the curve in the passage 18. Therefore, piston 2
3 can move smoothly in the passage 18. Note that the main body (half portions 21 and 22) of the piston 23 is made of aluminum or resin.

On the inner side of the U-shape of the pipe 17, guide members 31, 33 are arranged above and below (up and down in FIG. 1A) with the sleeve 25 interposed therebetween. Guide members 31, 33
Is made of a die-cast member such as aluminum. There is a gap between the sleeve 25 and the guide members 31, 33. Further, between the guide member 31 and the pressure vessel 13,
There is a slight gap of the order of the thickness of the strip 36.

In FIG. 1A, the upper guide member 31
Is a part of the outer peripheral surface (the left end surface in FIG.
7 and screwed to a retractor base (not shown). Guide member 3
1 has a strip 3 extending from the sleeve 25.
6 is the surface to be guided. Therefore,
When the piston 23 moves in the direction of the arrow X in the passage 18 in the pipe 17, the strip 36 is pulled out from around the sleeve 25 while being guided by the outer peripheral surface of the guide member 31.

On the other hand, in the lower guide member 33 in FIG. 1A, the entire outer peripheral surface is fixed to the inner periphery of the pipe 17. The guide member 33 is also screwed to a retractor base (not shown).

Next, the operation of the pretensioner 1 having the above configuration will be described. When the collision state of the vehicle is detected, a detection signal is transmitted to the gas generator 15.
By this detection signal, the gas generator 15 is ignited,
A gas pressure is supplied into the pressure vessel 13. The piston 23 is pushed by this gas pressure, and the piston 23 moves in the passage 18 of the pipe 17 in the direction of the arrow X.

Then, as shown in FIG.
The strip 36 is pulled out with the movement of. At this time, the middle of the strip 36 is pulled out while being guided by the outer peripheral surface of the guide member 31. When the strip 36 is pulled out, the sleeve 25 to which the inner end of the strip 36 is fixed rotates in the arrow Y direction. This sleeve 25
, The clutch mechanism 30 is engaged, the rotation of the sleeve 25 is transmitted to the winding shaft 3, and the rotation of the belt in the winding direction is started. The piston 23 finally advances to near the end point of the passage 18 shown in FIG. 2, and the winding shaft 3 rotates approximately 540 °.

[0026]

As apparent from the above description, the present invention has the following effects. (1) Since the strip is a belt-like body, the material cost is lower than that of the ropes and wires that are brought together. (2) When one end of the strip is wound on the sleeve, the strip itself is pressed by the strip itself, so that the end is firmly fixed. Therefore, the locking structure and assembly of the strip end are also simple. (3) When the passage of the piston is curved, the size is reduced, and the entire device has a compact structure.

[Brief description of the drawings]

FIG. 1A is a front sectional view showing a state before an operation of a pretensioner described in the present embodiment.
(B) is an enlarged detailed view of the joint between the sleeve and the strip.

FIG. 2 is a front sectional view showing a state after an operation of the pretensioner of FIG. 1;

FIG. 3 is an enlarged exploded view of a joint portion between a strip and a piston.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pretensioner 3 Take-up shaft 13 Pressure vessel 15 Gas generator 17 Pipe 18 Passage 21, 22 Half part of piston 23 Piston 25 Sleeve 27 Pin 30 Clutch mechanism 36 Strip

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroki Takehara 1-4-30 Roppongi, Minato-ku, Tokyo Inside Takata Corporation (72) Inventor Hiromasa Tanji 1-4-30 Roppongi, Minato-ku, Tokyo Takata Corporation F-term (reference) 3D018 MA02

Claims (3)

[Claims] 1. A pretensioner for rotating a winding shaft of a seat belt in a winding direction in an emergency to apply pretension to a belt; a sleeve connected to the winding shaft via a clutch; , A piston fixed to the other end of the strip, a passage through which the piston travels, and an accelerator for moving the piston in the passage. A pretensioner wound on the sleeve. 2. The pretensioner according to claim 1, wherein a groove is formed in the sleeve, and one end of the strip is inserted into the groove. 3. A pretensioner for applying a pretension to a belt by rotating a winding shaft of a seat belt in a winding direction in an emergency; a sleeve connected to the winding shaft via a clutch; And a piston fixed to the other end of the strip, a passage through which the piston travels, and an accelerator for moving the piston in the passage, wherein the passage is curved. A pretensioner characterized in that: