JP2003212087A - Seat belt winding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seat belt winding device with a pretensioner capable of securely restraining the tip of a pipe and smoothly operating an EA mechanism. <P>SOLUTION: A ball 15 pushed with gas pressure from a gas generator is collided with and guided to a first guide surface 31 first, and next, passes over a second guide surface 32. The force applied to a guide block 30 by the ball 15 when the ball 15 passes becomes larger as the ball 15 progresses on the first guide surface 31 and smaller on the second guide surface 32. Since a part under the first guide surface 31 is solid and its rigidity is high, the possibility of breaking the guide block 30 is small even if a large force is applied to the guide block 30 by the ball 15. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention moves a ball arranged in a pipe by a pressure of a gas generated from a gas generator provided at one end of the pipe and installs it at another end of the pipe. The present invention relates to a seat belt winding device that rotates a pre-tension mechanism by the propulsive force of a ball discharged from a ball exit. In particular, the present invention relates to a seat belt retractor having a pretensioner that has sufficient strength and that allows an energy absorption (EA) mechanism to operate smoothly.

[0002]

BACKGROUND ART As a facility for protecting an occupant when a vehicle is suddenly accelerated or decelerated, most vehicles are equipped with a seat belt. Furthermore, some recent seat belts are equipped with a pretensioner that further tightens the seat belt tightening force in the event of a vehicle collision to initially restrain the occupant to the seat. Further, in the case where the restraint force of the seat belt is likely to be excessive, there is also one having an EA mechanism that gradually unwinds the belt to limit the restraint force and absorb the kinetic energy of the human body.

[0003]

FIG. 6 is an exploded perspective view showing an example of a seat belt retractor having a pretensioner and an EA mechanism. The pretensioner shown in this figure is currently under development and is not publicly known. Further, among components, those which are considered unnecessary for the description of the present invention are omitted.

A spool 2 is housed in the base frame 1, and a seat belt (not shown) is wound around the spool 2. As the spool 2 rotates, the seat belt is wound and unwound. A torsion bar 3 is arranged at the axial center of the spool 2, and one end of the torsion bar 3 is supported by a retainer 6 via lock mechanism parts 4 and 5. Torsion bar 3 is E
This is a main component of the A mechanism, and when the belt tension exceeds a predetermined value, it undergoes plastic torsional deformation, and accordingly, the spool 2 gradually rotates in the belt payout direction.

A gear 7 is provided at one end (the left end in the figure) of the spool 2. The gear 7 is engaged with a gear in the return spring cover 8 shown at the lower left end of the figure. The return spring in the return spring cover 8 urges the spool 2 in the direction in which the seat belt is wound.

A pretensioner is provided in the seat belt retractor having such a basic structure. The configuration of the pretensioner will be described below. Pretensioner cover 9 shown on the right of the return spring cover 8
And a pretensioner plate 10 shown at the right end of the lower part of the figure, a pipe 11 is provided. This pipe 1
A gas generator 12 is attached to one end of 1. And inside the pipe 11, the spring 1
3, a piston 14, and a plurality of balls 15 are arranged. A side of the pipe 11 near the other end is notched, and a guide block 30 is fitted into the other end.

The pretensioner cover 9 has two pins 1
7 is provided, and a ring gear 18 is fitted and held therein. Then, the most advanced ball 15 is sandwiched and constrained between the outer teeth of the ring gear 18 and the not-cut inner wall of the pipe 11.

On the other hand, the gear 19 at the left end of the spool 2 in the figure
A pinion 20 is fitted in the pinion. In a normal state, the ring gear 18 and the pinion 20 are not engaged, but as will be described later in detail, the gas generator 12
If gas is generated from the ball 1
5 is pushed, the pin 17 is broken by the force, and the ring gear 1
8 becomes free and engages with the pinion 20. And
In that state, the ring gear 18 is rotated by being pushed by the ball 15, and the spool 2 is rotated via the pinion 20. In this way, the seat belt is pretensioned.

In such a pretensioner, it is necessary to fix the pipe 11 between the pretensioner cover 9 and the pretensioner plate 10. During operation of the pretensioner, a large force for moving the ball is applied by the gas pressure, and therefore the restraining force of the pipe 11 needs to be considerably high. The upper surface of the pipe 11 can be held on the upper surface of the pretensioner cover 9, but the tip of the pipe 11 on the side where the balls are discharged must also be strongly held.

On the other hand, when the EA mechanism is operating, the spool 2 and the ring gear 18 rotate in a direction opposite to the direction in which the pretensioner is operating, and an operation for pushing the ball 15 back into the pipe 11 occurs. At this time, the balls 15 may be clogged (stuck), and countermeasures against them may be necessary.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a seat belt retractor having a pretensioner capable of reliably restraining the tip end portion of a pipe and smoothly operating an EA mechanism. To aim.

[0012]

In order to solve the above problems, a seat belt retractor of the present invention comprises a pretensioner for rotating a seat belt spool in the retracting direction to give pretension to the belt in an emergency, and , When the seat belt is tensioned with a predetermined value or more,
A seat belt retractor having an energy absorbing mechanism for gradually rotating the spool in a belt withdrawing direction, wherein the pretensioner includes a gas generator and a series of a plurality of gas generators accelerated by gas generated by the gas generator. A ball; a pipe for guiding the ball; and a rotary member having a plurality of driving points which are hit by the ball ejected from the end of the pipe to give a rotary driving force, and which is connected to the spool. A guide block for guiding the ejection of the ball is attached to an end of the pipe, and the guide block is connected to a first guide surface connected to the end of the pipe and a tip of the first guide surface. A second guide surface,
The first guide surface has an arc shape substantially concentric with the rotating member, the ball collides with the pretensioner during operation, and the second guide surface is formed so as to gradually move away from the rotating member. A portion below the first guide surface of the guide block is solid, while a portion below the second guide surface is hollow, and when the energy absorbing mechanism operates after the pretensioner operates. In addition, a notch is formed in the guide block as a starting point at which a member of the guide block forming the surface is broken when the ball is pushed back to the second guide surface and a strong pressing force is applied to the surface. It is characterized by

In the guide block where the balls collide when the pretensioner operates, the portion of the first guide surface is solid, so it has sufficient resistance to the collision force of the balls. For example, slack on a seat belt
When the pretensioner is actuated, the rotating member (ring gear) that is rotationally driven by the ball first swiftly rotates, and the ball hits the first guide surface of the guide block while the ball speed is high, and Although the force of strength may be applied over a fairly wide range, even in such a case, damage to the first guide surface of the guide block can be avoided.

On the other hand, since the second guide surface of the guide block where the balls may be pushed back and stuck when the EA mechanism is activated is hollow and has the notch, the second guide surface is severe. When a pressing force is applied, the guide block is broken from the notch as a starting point, the ball that is about to be stacked is released, and a smooth operation of the EA mechanism can be ensured.

[0015]

DETAILED DESCRIPTION OF THE INVENTION A description will be given below with reference to the drawings. First, the overall configuration and operation of a pretensioner according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a front sectional view showing a state before operation of a pretensioner according to an embodiment of the present invention. FIG. 2 is a front sectional view showing a state of the pretensioner immediately after ignition of the gas generator.

The pretensioner 10 shown in these figures is
It is incorporated in the seat belt retractor shown in FIG. The pretensioner 10 is attached to the left end side of the base frame 1 (see FIG. 6) of the seat belt retractor. The pipe 11 of the pretensioner 10 is a bent steel pipe (one example). The pipe 11 is curved from the lower base end 11a in FIGS. 1 and 2 to the upper right by about 90 ° and is connected to the straight line portion 11b, and is further connected to the semicircular portion 11c at the upper portion of the drawings. A straight portion 11d directed downward in the figure is connected to the tip of the semicircular portion 11c. This last straight part 11
A notched portion 11e is formed inside the d so that the ring gear 18 can intervene therein. Notch 11e
The outer teeth 18a of the ring gear 18 are inserted inside.

The base end 11a of the pipe 11 is slightly thicker than the pipe 11 and has a gas generator 12 inside.
Is stored. The gas generator 12 ignites explosives on the basis of a detection signal transmitted from a collision detection means (not shown) at the time of a vehicle collision, and supplies gas pressure into the pipe 11 (see FIG. 2). The gas generator 12 is caulked and fixed to the base end 11 a of the pipe 11.

As shown in FIG.
Five balls 15 are loaded in series. The leading ball 15-1 hits the outer teeth 18a of the ring gear 18 and stops. After the rearmost ball 15-15 of the fifteen balls 15, a piston 14 having substantially the same shape as each ball is mounted. A spring 13 is provided between the piston 14 and the gas generator 12. The piston 14 is biased by the spring 13,
The ball 15 is pressed to the front side. Each ball 15 is made of steel or aluminum, and the piston 14 is made of silicone rubber. The piston 14 deforms after the gas is injected and comes into close contact with the inner surface of the pipe 11, and plays a role of a seal that does not leak the gas to the front side.

At the tip of the straight portion 11d of the pipe 11,
A guide block 30, which is a characteristic component of the pretensioner of the present invention, is fitted. The guide block 30 is a cast component (an example) made of aluminum or the like. Guide block 30
Are fixed to the support plate 21 of the pretensioner plate 10 (see FIG. 6) with screws 22. Details of this guide block 30 will be described later. Screw 22 is pipe 1
It also plays the role of fixing 1 to the support plate 21. Instead of the screw 22, for example, a rod-shaped member such as a rivet or a press-fit pin may be inserted and fixed by an adhesive so as not to fall off. 1 and 2, reference numerals 23 and 24 are cross sections of the pretensioner cover 9 (see FIG. 6). The cross section 23 restrains the pipe 11 and the cross section 24 forms a ball receiving portion 25.

The overall operation of the pretensioner 10 is as follows. In the state before operation shown in FIG. 1, the ring gear 18 is supported by the pin 17. The internal teeth 20b of the pinion 20 are fitted in the gear 19 of the spool 2 (see FIG. 6). In this state before the operation of the pretensioner, the internal teeth 18b of the ring gear 18 and the pinion 20 are
The outer teeth 20a of the above are not meshed. Therefore, the pretensioner 10 does not affect the rotation of the spool 2.

When a gas signal is generated from the gas generator 12 due to the operation signal of the pretensioner, the piston 14 is pushed by the pressure of the gas as shown in FIG. Then, the force is transmitted to the ball 15, and the most advanced ball 1
5-1 pushes the outer teeth 18a of the ring gear 18. Ball 1
When 5-1 pushes the outer teeth 18a of the ring gear 18, the pin 17 of FIG. 1 is broken and the ring gear 18 becomes free, and the push force of the ball 15 moves to the lower right side of the figure. With this, the inner teeth 18b of the ring gear 18 and the pinion 2
The outer teeth 20a of 0 mesh with each other.

As shown in FIG. 2, when the ring gear 18 and the pinion 20 mesh with each other, the ring gear 18 moves to the right in the figure, and the adjacent outer teeth 18a (bottom root) of the ring gear 18 and the pipe 11 move. A gap through which the ball 15 passes is formed between the inner surface and the inner surface. And the ball 15 pressed by gas pressure
-1 is discharged to the ball receiving portion 25 while rotating the ring gear 18 through the gap. Then, the second ball 15-2 pushes the outer teeth 18a of the ring gear 18,
The ball receiving portion 2 while further rotating the ring gear 18
It is discharged to 5. In this way, a plurality of balls 1
5 is pushed out, the ring gear 18 rotates accordingly, and the spool 2 rotates via the pinion 20, whereby pretension is applied to the seat belt.

Next, the structure and operation of the guide block 30, which is a main component of the present invention, will be described in detail. Figure 3
FIG. 3 is a detailed view of a guide block of the pretensioner according to the present invention. (A) is a side sectional view, (B) is a front view, (C) is a rear view, (D) is a bottom view, and (E) is a perspective view. FIG. 4 is a diagram showing a state where the ball collides with the guide surface of the guide block. Figure 5
(A) is an enlarged view for explaining a ball stack state during EA operation of the pretensioner of FIGS. 1 and 2.
FIG. 5B is an enlarged view for explaining the deformed state of the guide block during ball stacking.

The guide block 30 shown in FIG. 3 has a columnar shape with its tip cut obliquely, and its slope is the guide surface. This guide surface is shown in FIGS. 3 (B) and (E).
The first guide surface 31 and the second guide surface 31
And the guide surface 32. The first guide surface 31 is formed in an arc shape substantially concentric with the ring gear 18 at the upper end portion of the guide block 30, and the ball 15 ejected from the pipe 11 collides with the pretensioner during operation (see FIG. 5). ). On the other hand, the second guide surface 32 is connected to the tip of the first guide surface 31 and is a surface that gradually moves away from the ring gear 18.

A notch 33 is formed at the boundary between the first guide surface 31 and the second guide surface 32, as shown in FIGS. 3 (A), 3 (B) and 3 (E). When the EA mechanism operates after the pretensioner is operated, the notch 33 pushes the ball 15 back to the second guide surface 32,
When a strong pressing force is applied to the second guide surface 32 (at the time of ball stacking), the guide block 30 becomes a starting point of breaking (see FIG. 4B). The detailed operation of the notch 33 will be described later.

A through hole 36 is formed in the guide block 30 so as to penetrate along the width direction of the guide surface. As shown in FIG. 3A, the through hole 36 is formed by being hollowed out substantially on the lower side of the second guide surface 32. The upper end 36 a of the through hole 36 is located substantially below the notch 33. The portion of the guide block 30 below the first guide surface 31 is solid and has high rigidity. On the other hand, the portion below the second guide surface 32 is hollow due to the presence of the through hole 36 and has low rigidity.

Further, on the front surface side of the guide block 30 (right end side in FIG. 3A), the upper and lower inner surfaces 2 of the through holes 36 are formed.
Inner notches 36b and 36c are formed at the locations.
On the other hand, on the back surface side of the guide block 30 (the left end side in FIG. 3A), the inner notch 36 is formed on the lower inner surface of the through hole 36.
d is formed. These inner notches 36b, 36c, and 36d serve as the starting points at which the guide block 30 breaks during ball stacking, like the notch 33 described above. The detailed operation of these inner notches 36b, 36c and 36d will also be described later.

As shown in FIGS. 3A and 3C, a screw hole 37 is formed between the rear surface of the guide block 30 and the through hole 36. The screw hole 37 is inserted into the screw hole 37.
Goes in. Bottom surface 3 of the guide block 30 shown in FIG.
A recess 38 a is formed in the plate 8.

Next, the detailed operation of the guide block 30 will be described mainly with reference to FIGS. 4 and 5. As described above, when gas is generated from the gas generator 12 and the piston 14 and the ball 15 are pushed by this gas pressure, the ball 15 is ejected from the pipe 11 and the guide block 30 is pushed while rotating the ring gear 18 by pushing it down.
Leading to. At this time, as shown in FIG. 2, the ball 15 first collides with and is guided on the first guide surface 31, then passes through the second guide surface 32, and is discharged to the ball receiving portion 25.

When the ball 15 passes, the force applied from the ball 15 to the guide block 30 is the first guide surface 3
It becomes larger as it goes through 1, and becomes smaller at the second guide surface 32. That is, as shown in FIG. 4, the force applied from the ball 15 to the guide block 30 is the arrow α.
Gradually increases, the position B has the largest value, and the arrow β decreases the value. On the other hand, in the guide block 30 according to the present invention, the portion under the first guide surface 31 (the portion corresponding to the arrow α and the position B) is solid and has high rigidity, so that a large force is applied from the ball 15. Even if it does, the possibility that the guide block 30 will be damaged is low.

Further, for example, when the seat belt has a slack (slack), the ring gear 18, which is rotationally driven by the ball 15 at the time of actuation of the pretensioner, first turns vigorously and the speed of the ball 15 remains high. The ball 15 is the first guide surface 3 of the guide block 30.
In the case of 1, a force of considerable strength may be applied over a wide range. Even in such a case, in the guide block 30 according to the present invention, since the lower portion of the first guide surface 31 is solid and the rigidity is high, it is possible to avoid damage to the first guide surface 31 of the guide block 30. .

Next, the operation during EA will be described. E
At the time of A, the ring gear 18 rotates clockwise (clockwise in FIGS. 1 and 2) as the spool rotates. At this time, as shown in FIG. 5 (A), the ball 15 near the outlet of the pipe 11 tries to be drawn into the pipe 11 (direction of arrow X in FIG. 5 (A)). When such a ball stack occurs, the ball 15 is sandwiched between the guide block 30 and the outer teeth 18a of the ring gear 18.

At this time, the second guide surface 32 of the guide block 30 is sandwiched between the ball 15 and the ring gear 1.
It is pushed by the outer teeth 18a of No. At this time, a strong pressing force is applied to the second guide surface 32 of the guide block 30. When such a strong pressing force is applied,
As shown in (B), the notch 33 and the inner notch 36b,
The guide block 30 is broken starting from the portions (all or some of them) of 36c and 36d. Therefore, the ball 15 that is about to be stacked is not attached to the ring gear 18
And the block 30 (see the chain double-dashed line in FIG. 5B), and the rotation of the gear 18 is not hindered, so that a smooth operation of the EA mechanism can be ensured.

[0034]

As described above, according to the present invention,
It is possible to provide a seat belt retractor having a pretensioner capable of reliably restraining the tip portion of the pipe and smoothly operating the EA mechanism.

[Brief description of drawings]

FIG. 1 is a front cross-sectional view showing a state before an operation of a pretensioner according to an embodiment of the present invention.

FIG. 2 is a front sectional view showing a state of the pretensioner immediately after ignition of a gas generator.

FIG. 3 is a detailed view of a guide block of the pretensioner according to the present invention. (A) is a side sectional view, (B) is a front view, (C) is a rear view, (D) is a bottom view, and (E) is a perspective view.

FIG. 4 is a diagram showing a state where a ball collides with a guide surface of a guide block.

5 (A) is an enlarged view for explaining a ball stack state during EA operation of the pretensioner of FIGS. 1 and 2, and FIG. 5 (B) is a guide block during ball stacking. It is an enlarged view for explaining the deformation state of.

FIG. 6 is an exploded perspective view showing an example of a seat belt retractor having a pretensioner and an EA mechanism.

[Explanation of symbols]

10 Pretensioner 11 Pipe 12 Gas Generator 13 Spring 14 Piston 15 Ball 18 Ring Gear 20 Pinion 22 Screw 30 Guide Block 31 First Guide Surface 32 Second
Guide surface 33 Notch 36 Through hole 36a
Upper end parts 36b, 36c, 36d (through holes) Inner notch 37 Screw hole 38 Bottom surface 38a Recess

Claims (2)

[Claims] 1. A pretensioner for pretensioning a belt by rotating the spool of a seatbelt in a winding direction in an emergency, and gradually rotating the spool when tension of a predetermined value or more is applied to the seatbelt. A seat belt retractor having an energy absorbing mechanism for rotating the belt in the belt withdrawing direction, wherein the pretensioner includes a gas generator, a series of balls accelerated by gas generated by the gas generator, and the ball. A pipe that guides the pipe, and a rotating member that has a plurality of driving points that the balls ejected from the end of the pipe hit and that applies a rotational driving force, and that is connected to the spool. A guide block for guiding the ejection of the ball is attached to the section, and the guide block is A first guide surface connected to the end of the pipe, and a second guide surface connected to the tip of the first guide surface, wherein the first guide surface has an arc shape substantially concentric with the rotating member. The ball collides with the pretensioner during operation, the second guide surface is formed so as to gradually move away from the rotating member, and a portion of the guide block below the first guide surface is solid. On the other hand, the portion below the second guide surface is hollow, and when the energy absorbing mechanism is operated after the pretensioner is operated, the ball is pushed back to the second guide surface and a strong pressing force is applied. The seat belt retractor is characterized in that a notch is formed in the guide block as a starting point at which a member of the guide block forming the surface breaks when the sheet is applied to the guide block. 2. The seat belt retractor according to claim 1, wherein the notch is formed at a boundary portion between the first guide surface and the second guide surface.