JPH07117620A - Mechanical ignition sensor - Google Patents

Abstract

PURPOSE:To generate surely force capable of releasing a trigger and attempt the miniaturization of an outer diameter size. CONSTITUTION:A first ball 44 and a second ball 45 for detecting acceleration in vehicular rapid speed reduction time by inertia movement are arranged in a cylinder 46. The second ball 45 is formed smaller by a prescribed dimension than the first ball 44 and can move the cylinder 46 with a resistance smaller than that of the first 44. The vicinity of one end of a drive shaft for blocking the movement of an ignition pin is in contact with the first ball 44 positioned on the inertia movement side. In a vehicular rapid speed reduction time, the inertia force of both balls 44, 45 is transmitted to the driven shaft surely. As the ball which was one in the past was divided to two, the diameter of the cylinder 46 may be smaller and the outer diameter of a mechanical ignition sensor become smaller than before.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical ignition sensor, and more particularly to a mechanical ignition sensor mounted on a vehicle for inflating a bag for protecting an occupant.

[0002]

2. Description of the Related Art An air bag is equipped with a mechanical ignition sensor. For example, in an air bag of a type mounted on a steering wheel, the steering wheel is inflated by the mechanical ignition sensor when the vehicle suddenly decelerates. This is to be interposed between the passenger and the passenger.

As shown in FIG. 5, a conventional mechanical ignition sensor 100 of this type has an ignition pin biased toward a cylinder 104 accommodating a spherical ball 102 and a detonator 106 (in the direction of arrow B). And 108.

The drive shaft 1 is attached to the ball 102.
One end of 10 is in contact with the drive shaft 110.
A trigger member 112 is fixed to the other end of the.

Normally, the drive shaft 110 is pressed in the direction of arrow B by a bias pin 116 having a bias spring 114, whereby the drive shaft 110 pushes the ball 102 into the cylinder 104.
The trigger member 112 is engaged with the ignition pin 108 to prevent the ignition pin 108 from moving toward the detonator 106.

When the vehicle 102 suddenly decelerates, the ball 102 inertially moves in the direction of arrow C against the biasing force of the bias spring 114 and rotates the drive shaft 110 counterclockwise, whereby the trigger member 112 and the ignition pin 108 are separated. The disengagement causes the ignition pin 108 to collide with the detonator 106, the detonator 106 is ignited to burn a gas generating substance (not shown), and the generated gas causes a bag (not shown) to expand. ing.

[0007]

As shown in FIG. 5, in the mechanical ignition sensor 100 of this type, the outer diameter size d of the cylinder 104 occupies a large portion of the sensor outer diameter size D.

Further, in order to generate a force capable of releasing the trigger at the time of sudden deceleration of the vehicle, a certain weight or more of the ball is required, and it is difficult to significantly reduce the ball diameter. Therefore, the outer diameter size D of the mechanical ignition sensor cannot be significantly reduced, and the outer diameter size d of the cylinder 104 is an obstacle to downsizing the mechanical ignition sensor.

The present invention has been made in view of the above circumstances, and an object thereof is a mechanical type which can surely generate a force capable of releasing a trigger and can reduce the outer diameter size. It is to provide an ignition sensor.

[0010]

A mechanical ignition sensor according to the present invention is disposed in a cylinder, and a first ball movably disposed in the cylinder for detecting sudden vehicle deceleration by inertial movement. The outer diameter of the first ball is smaller than that of the first ball by a predetermined dimension, and the outer diameter of the first ball is opposite to the inertial movement direction of the first ball. Is engaged with the end of the first ball on the side of inertial movement in the inertial movement direction to hold the first ball and the second ball at predetermined positions, and when the vehicle rapidly decelerates. One ball and a drive shaft rotated by the second inertial movement, an ignition pin that acts on the detonator to inflate the airbag and is always biased in the collision direction by the detonator, and engages with the ignition pin for ignition. Pi And a trigger member that rotates together with the drive shaft to release movement inhibition of the ignition pin when the vehicle rapidly decelerates, and a direction in which the trigger member releases movement inhibition of the ignition pin when the vehicle suddenly decelerates. A pressing member for pressing the drive shaft in a direction,
It is characterized by having.

[0011]

According to the above construction, when the vehicle is suddenly decelerated, the first ball and the second ball inertially move and the drive shaft pivots largely. Therefore, the engagement state between the trigger member of the drive shaft and the ignition pin is released, and the biased ignition pin collides with the detonator to inflate the airbag. As a result, the occupant is protected from the impact when the vehicle suddenly decelerates. On the other hand, during normal traveling (normal time), the trigger member provided on the drive shaft engages with the ignition pin, and the movement of the ignition pin is blocked.

Since the outer diameter of the second ball is smaller than the outer diameter of the first ball, the second ball moves more easily than the first ball during inertial movement, and the first ball The drive shaft can be pressed with the second ball always in contact with the second ball, and the inertia force of the first ball and the second ball
The inertial force that is the sum of the inertial force of the ball and the inertial force of the ball reliably acts on the drive shaft.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 4 is a partial cross-sectional view showing a state where the airbag device 10 to which an example of the mechanical ignition sensor according to the present invention is applied is attached to the steering wheel 18.

The airbag device main body 12 of the airbag device 10 is a base plate with bolts 32 or the like to the support plate 16 fixed to the hub 18A of the steering wheel 18.
By fixing the toe 14, the steering wheel 1
It is designed to be attached to 8.

The release pin 3 is provided at a position corresponding to a mechanical ignition sensor, which will be described later, at a substantially central portion of the support plate 16.
4 is projected. The release pin 34 is for releasing the operation of the fixing device described later.

An air bag body 20, an air bag cover 22, and an inflator 24 are attached to the base plate 14, respectively.

The airbag bag body 20 includes the base plate 1
4 is arranged in a folded state toward the passenger side (arrow B side in FIG. 4). The edge of the airbag 20 on the opening side is attached to a substantially central portion of the base plate 14 via a ring plate 26. The ring plate 26 is tightened to the base plate 14 with a bolt (not shown), and the edge on the opening side is pressed to the base plate 14.

The airbag cover 22 is a base plate 1
4 is disposed on the occupant side (arrow B side in FIG. 4) and stores the airbag bag 20 between itself and the base plate 14. A frame-shaped core metal (not shown) is embedded around the airbag cover 22 and is attached to the base plate 14 by rivets or the like via the core metal.
Further, a thin portion 22A is formed in a portion of the airbag cover 22 facing the inflator 24.
It is easily broken at 2A.

The inflator 24 has a substantially columnar shape and penetrates a circular hole in the central portion of the base plate 14, and
It is arranged in a state in which a part thereof is inserted into the airbag body 20. The inflator 24 has a flange 2 on the surface of the base plate 14 on the side opposite to the occupant (the side of arrow C in FIG. 4).
It is attached by fixing 4A.

The inflator 24 is filled with a gas generating substance 30 whose combustion is started by a mechanical ignition sensor 28 described later. The gas generating substance 30 is decomposed by combustion to release a large amount of gas, and the gas having passed through a filter (not shown) inflates the airbag bag body 20. As the gas generating substance 30,
For example, some contain sodium azide.

A mechanical ignition sensor 28 is arranged at the axial center of the inflator 24. A detonator 36 (see FIG. 1) is provided between the gas generating substance 30 and the mechanical ignition sensor 28.
Also, an explosive agent (not shown) is arranged coaxially with the mechanical ignition sensor 28, and when the detonator 36 ignites, a spark is guided to the explosive agent and converted into thermal energy, and this heat causes the explosion The agent is designed to generate a large amount of gas.

The mechanical ignition sensor 28 will be described in detail below. The mechanical ignition sensor 28 has a cylindrical shape, and as shown in FIG. 1, has a lower case 40 and an upper case 38 which are divided by a plane orthogonal to the axis at the center of the axis. The side case 40 and the upper case 38 are inserted and fixed in the outer case 39.

In the upper case 38, the inertial body of the mechanical ignition type air bag sensor, that is, the first ball 45 and the second ball 45 for detecting the acceleration during sudden deceleration of the vehicle by inertial movement.
Are arranged. In this embodiment, the first ball 44 and the second ball 45 are inserted into a cylindrical cylinder 46, and the cylinder 46 has an axis line in the upper case 38 that is parallel to the axis line of the upper case 38. And is fixed in place.

The outer diameter d1 of the first ball 44 is slightly smaller than the inner diameter d2 of the cylinder 46, and the first ball 44 is movable in the cylinder 46. on the other hand,
The outer diameter d3 of the second ball 45 is smaller than the outer diameter d1 of the first ball 44 by a predetermined dimension, and the cylinder 46 can be moved with a resistance smaller than that of the first ball 44.

In this embodiment, the first balls 44 are arranged on the lower case 40 side (arrow C direction side), and the second balls 4 are arranged.
5 is arranged on the side opposite to the lower case 40 side (arrow B direction side).

With the above structure, when a sudden acceleration in the direction of arrow C acts on the first ball 44 and the second ball 45, the first ball 44 and the second ball 45 move downward in the cylinder 46. Move toward the case 40.

A housing portion 42 is formed on the end surfaces of the upper case 38 and the lower case 40 that face each other. At the end of the first ball 44 on the lower case 40 side, one end of the drive shaft 48 disposed in the accommodating portion 42 along the boundary between the lower case 40 and the upper case 38 is disposed (see FIG. 3). (See) is abutted.

As shown in FIG. 2, the drive shaft 48
A locking piece 52, which is a rod-shaped member having a substantially semicircular cross-section, is attached to the other end of the drive shaft 48 so as to be orthogonal to the axial direction of the drive shaft 48.
The drive shaft 48 is pivotally supported by the upper case 38 and the lower case 40 via a pair of rotating shafts 52A and 52B provided at both ends of the drive shaft 48. As a result, the drive shaft 48 can turn up and down about the rotary shafts 52A and 52B.

As shown in FIG. 1, the lower case 40 includes
A hole 53 is formed in the end portion on the upper case 38 side. The hole 53 is formed along the axis of the lower case 40, and the bias pin 54 that constitutes the pressing member is movably inserted therein. The bias pin 54 has a small-diameter portion 54A on the bottom side of the hole 53 (arrow C side in FIG. 1), and the small-diameter portion 54A is wound with the bias spring 50 that constitutes another part of the pressing member. It is equipped. The bias spring 50 is in contact with the bottom of the hole 53 formed in the lower case 40, and biases the bias pin 54 toward the upper case 38 side (arrow B side in FIG. 1).

As a result, the end portion of the bias pin 54 on the upper case 38 side presses the intermediate portion in the longitudinal direction of the drive shaft 48, and as a result, the bias spring 50 is attached near one end portion of the drive shaft 48. The first ball 44 is pressed by the force.

An ignition pin 56 is accommodated in the accommodating portion 42, and the ignition pin 56 is used for the upper case 3 during sudden deceleration of the vehicle.
8 and the lower case 40 can be moved from the lower case 40 side to the upper case 38 side along guide paths 66 and 68 formed in the respective axial center directions.

As shown in FIG. 1, the ignition pin 56 is provided with a shaft portion 56A and a stepped collar portion 58 provided at an intermediate portion in the longitudinal direction of the shaft portion 56A. A compression coil spring 72 is wound around the shaft portion 56A at a portion of the stepped collar portion 58 on the arrow C side in FIG. One side of the compression coil spring 72 abuts on the stepped collar portion 58, and the other side abuts on the bottom portion of the annular hole 73 formed in the lower case 40 to move the ignition pin 56 toward the detonator 36 (arrow B).
Direction). In addition, the detonator 3 of the shaft portion 56A
The end on the 6 side is formed in a conical shape.

The stepped collar portion 58 is formed by the first disc-shaped portion 6
2 and a second disc-shaped portion 64 which is coaxially formed on the tip side of the first disc-shaped portion 62 and has a somewhat smaller diameter, and the first disc-shaped portion 62 and the first disc-shaped portion 62. A step portion 60 is formed at a boundary between the second disc-shaped portion 64 and the disc-shaped portion 64.

In the ignition pin movement prevention state shown in FIG. 1, one end of the locking piece 52 (on the side of arrow C in the figure) is locked to the step portion 60 of the ignition pin 56.

The outer peripheral surface of the second disk-shaped portion 64 is shown in FIG.
As shown in FIG. 2 to FIG. 2, a taper is formed. Therefore, in the ignition pin movement preventing state shown in FIG. 1, between the tip of the locking piece 52 and the second disk-shaped portion 64, An escape portion 70 (see FIG. 3) is formed to avoid the contact of the tip end portion of the locking piece 52.

The locking piece 52 of the drive shaft 48
An arcuate chamfered portion (not shown) is actually formed at the tip end portion on the side of arrow C of FIG.
The ball 44 and the second ball 45 are finished with an accuracy such that they can be smoothly rotated at a predetermined timing when a predetermined inertial force is applied to them.

Further, as shown in FIG. 2, the surface of the engaging piece 52 on the side facing the ignition pin 56 is moved when the ignition pin 56 is moved, which will be described later in the description of the operation.
The recessed portion 52C is formed so as not to hit the locking piece 52.

In the accommodating portion 42 on the lower case 40 side,
The fixing device 74 is arranged on the ball movement direction side of the drive shaft 48 (the arrow C direction side in FIG. 1). This fixing device 74 is for preventing the ignition pin 56 from moving when it is not needed by restricting the up-and-down rotation of the drive shaft 48, and in practice, it is a torsion coil spring (not shown). One extension portion of the torsion coil spring is configured with a lock pin (not shown) that can be fitted. In the operating state of the fixing device 74, the drive shaft 48 cannot be turned up and down.

Next, the operation and the like of this embodiment will be described. With the airbag device body 12 attached to the vehicle body,
The release pin 34 releases the fixing device 74.

During normal deceleration while the vehicle is traveling, the first
The ball 44 and the second ball 45 move in the direction of arrow C in FIG. 1 according to the degree of deceleration. As a result, the drive shaft 48 slightly rotates counterclockwise in FIG. 1 about the rotation shafts 52A and 52B, but in the normal deceleration state, the biasing force of the bias spring 50 applied to the bias pin 54 is smaller. First ball 44 and second
Since it is larger than the inertial force applied to the ball 45, the locking piece 52 of the drive shaft 48 does not come off from the stepped collar portion 58 of the ignition pin 56.

Next, when the vehicle is suddenly decelerated, the inertial force applied to the first ball 44 and the second ball 45 is applied to the first ball 44 and the second ball 45 during the normal deceleration. It is much larger than the added inertial force. Therefore, the first ball 44 and the second ball 45 are shown in FIG.
The inertial movement largely moves in the direction of arrow C.

Since the outer diameter d1 of the first ball 44 is only slightly smaller than the inner diameter d2 of the cylinder 46,
The first ball 44 has the same structure as the first ball 44 during inertial movement.
Since the direction of movement of (the arrow C direction) but the braking force F _D in the opposite direction acts, the second ball 45 is the outer diameter d3 is further predetermined size smaller than the outer diameter d1 of the first ball 44, the inertial When moving, almost no braking force is applied. That is, during inertial movement, the second ball 45 is easier to move than the first ball 44, so that the first ball 44 and the second ball 45 are always in contact with each other and inertial movement is performed in the direction of arrow C. The inertial force m ₁ G of the first ball 44 (where m _{1 is} the mass of the first ball 44, G is the acceleration during deceleration of the vehicle) and the inertial force m ₂ of the second ball 45 can be achieved. G (where
m _2: mass of the second ball 45, G: braking force F from the vehicle during deceleration of the acceleration) and total inertial force _{(m 1 G + m 2 G} )
_The force F obtained by subtracting _D acts on the drive shaft 48 without fail.

When the first ball 44 and the second ball 45 inertially move in the direction of arrow C, the drive shaft 48 pivots more counterclockwise in FIG. 1 about the rotary shafts 52A and 52B. As a result, the locking piece 52 of the drive shaft 48 is locked by the stepped collar portion 5 of the ignition pin 56.
Depart from 8. As a result, the ignition pin 56 is moved in the direction of the detonator 36 by the biasing force of the compression coil spring 72 along the guide paths 66 and 68 from the lower case 40 side to the upper case 38 side.

The moving ignition pin 56 collides with the detonator 36 and ignites the detonator 36. This spark is grown by an explosive agent (not shown) and converted into heat energy to react the gas generating substance 30. A large amount of gas generated by the gas generating substance 30 is guided into the airbag bag body 20 after passing through a filter (not shown) and inflates the same.

The inflated air bag body 20 is interposed between the occupant and the steering wheel 18 and effectively protects the occupant from an impact when the vehicle suddenly decelerates.

By the way, in the conventional type mechanical ignition sensor, one ball presses one drive shaft, but in this embodiment, the first ball 44 and the first ball 44 arranged in series in the moving direction are arranged. Since the two balls 45 are used, the outer diameter of the cylinder 46 can be made smaller than that of the conventional type.

That is, the conventional one ball has the same mass as the first ball 44 and the second ball 45, and the conventional one ball has the same diameter as the first ball 44 and the second ball 45. In comparison, the diameter of the first ball 44 and the second ball 45 is about 79 times the diameter of one conventional ball.
%, The pressing force of the drive shaft 48 can be made equal to that of the conventional one, and the outer diameter of the mechanical ignition sensor 28 can be made smaller than that of the conventional one.

The outer diameter d3 of the second ball 45 is set to the first
If the outer diameter of the ball 44 is equal to or larger than the outer diameter d1, a larger braking force acts on the second ball 45 than on the first ball 44 during inertial movement, so that the first ball 44 and the second ball 45
Are separated from each other, and the force pressing the drive shaft 48 is reduced, and as a result, the locking piece 52 of the drive shaft 48 may not come off from the stepped collar portion 58 of the ignition pin 56. Therefore, the outer diameter d3 of the second ball 45 must be smaller than the outer diameter d1 of the first ball 44.

[0050]

As described above, according to the mechanical ignition sensor of the present invention, the two balls for pressing the drive shaft during the rapid deceleration of the vehicle are arranged in the cylinder, so that the cylinder diameter is small. This has the excellent effect that the outer diameter size can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a mechanical ignition sensor according to this embodiment.

FIG. 2 is an exploded perspective view of each component except the fixing device portion of FIG.

FIG. 3 is an enlarged view of a portion inside a circle A in FIG.

FIG. 4 is a schematic cross-sectional view showing a state in which the airbag device equipped with the mechanical ignition sensor of FIG. 1 is mounted on a steering wheel.

FIG. 5 is a schematic sectional view of a mechanical ignition sensor according to a conventional example.

[Explanation of symbols]

 20 Airbag Body (Airbag) 28 Mechanical Ignition Sensor 36 Detonator 44 First Ball 45 Second Ball 46 Cylinder 48 Drive Shaft 50 Bias Spring (Pressing Member) 52 Locking Piece (Trigger Member) 54 Bias Pin ( Pressing member) 56 Ignition pin

Claims (1)

[Claims] 1. A first ball movably disposed in a cylinder for detecting sudden vehicle deceleration by inertial movement, and an outer diameter dimension disposed in the cylinder smaller by a predetermined dimension than the first ball. A second ball having a first ball, the second ball being arranged in a pair with the first ball on the side opposite to the inertial movement direction of the first ball, and detecting a sudden vehicle deceleration by inertial movement; The first ball and the second ball are engaged with an end portion on the inertial movement direction side to hold the first ball and the second ball at predetermined positions and at the time of sudden deceleration of the vehicle.
Drive shaft rotated by the inertial movement of the detonator, an ignition pin that acts on the detonator to inflate the airbag and is always urged in the collision direction of the detonator, and engages with the ignition pin to prevent the ignition pin from moving. A trigger member that rotates together with the drive shaft when the vehicle suddenly decelerates to release the movement prevention of the ignition pin, and the drive shaft in a direction opposite to the direction in which the trigger member releases the movement inhibition of the ignition pin during the vehicle sudden deceleration. A mechanical ignition sensor, comprising: a pressing member for pressing.