JPH08244556A - Acceleration sensor - Google Patents

Abstract

PURPOSE: To reduce the influence by a reverse acceleration. CONSTITUTION: Between a ball 58, and the wall 50A of a sensor body 50 at the opposite side in the detecting direction of the ball 58, a coil spring 72 is inserted. The coil spring 72 is provided to position the center of gravity M of the ball 58 on the extension line of the center line of the coil spring 72, and the coil spring 72 is to be compression deformed pressed by the ball 58, when the ball 58 is moved in the direction opposite to its detecting direction (in the -G direction in the figure). The spring constant and the stroke of the coil spring 72 are set at the values to minimize the influence by the reverse acceleration, by considering the load operated to the ball 58.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor,
In particular, the present invention relates to an acceleration sensor having a mass that inertially moves in a detection direction when the vehicle suddenly decelerates.

[0002]

2. Description of the Related Art Conventionally, as one of occupant protection devices mounted on a vehicle, there is an airbag device for inflating a bag toward the occupant when the vehicle is suddenly decelerated. There are various types of air bag devices, for example, driver seats, passenger seats, etc. when categorized from the viewpoint of installation site, and mechanical ignition type and electric ignition type when categorized from the viewpoint of ignition system. Hereinafter, a mechanical ignition type airbag device and an electric ignition type airbag device will be briefly described in comparison, taking an example of an airbag device for a driver's seat.

As elements common to both, an inflator having a gas generating agent or the like inside, a base plate to which the inflator is attached, a bag body attached to the base plate in a folded state, and the bag body to be stored between the base plate and There are pads that break and develop when the vehicle suddenly decelerates. On the other hand, both have different ignition systems as described above, but in the case of the mechanical ignition system, the acceleration sensor itself is arranged at the axial center of the inflator, and the mass moves inertially in the detection direction during sudden vehicle deceleration. The firing pin pierces the detonator with a biasing force via the trigger member, whereby the gas generating agent burns. On the other hand, in the case of the electric ignition type, the acceleration sensor itself is arranged on both sides and the center of the front part of the vehicle body, and when one of the acceleration sensors senses the rapid deceleration state of the vehicle, the acceleration sensor is connected to the shaft core of the inflator through the determination circuit. The igniter arranged is energized, which causes the gas generant to burn.

Further, in the case of an acceleration sensor of a mechanical ignition type air bag device, for example, when a vehicle runs on a bad road, as shown in FIG. 4, a detection direction (arrow in FIG. 4) is detected on a mass 80 of the acceleration sensor. In addition to the acceleration in the G direction), the reverse acceleration-G also acts in the direction opposite to the detection direction (arrow G direction in FIG. 4). Therefore, the acceleration acting on the mass 80 tends to alternate between positive and negative with time, as shown by the solid line in FIG.

However, in the conventional acceleration sensor,
As shown in FIG. 4, when the inverse acceleration −G acts on the mass 80 in the direction opposite to the detection direction (arrow −G direction in FIG. 4), the mass 80 may contact the wall portion 82, In this case, the movement of the mass 80 is blocked by the wall portion 82.
Therefore, when the acceleration G acts on the mass 80 subsequent to the reverse acceleration −G, the acceleration G in the detection direction acting on the mass 80 is affected by the reverse acceleration −G and is shown by an imaginary line in FIG. 3. It will grow big. As a result, the acceleration sensor is easily turned on, making it difficult to adjust the sensitivity of the acceleration sensor.

[0006]

SUMMARY OF THE INVENTION In consideration of the above facts, an object of the present invention is to obtain an acceleration sensor capable of reducing the influence of reverse acceleration.

[0007]

An acceleration sensor according to the present invention as set forth in claim 1 is a mass that inertially moves in a detection direction when the vehicle decelerates rapidly, and an ignition provided outside the sensor by moving from a predetermined position. The material ignites and engages the ignition member that activates the occupant protection device equipped on the vehicle, the mass and the ignition member, and holds the ignition member in the predetermined position when the mass is not inertially moved, and the mass inertia A trigger member that allows movement of an ignition member by moving, and an acceleration sensor, wherein the mass of the mass is on an extension line of a center line between the mass and a wall portion opposite to a detection direction of the mass. It is characterized in that a coil spring is provided so that the center of gravity is located and is compressed and deformed by the mass when the mass moves in a direction opposite to the detection direction.

[0008]

According to the acceleration sensor of the present invention as set forth in claim 1, when a reverse acceleration acts on the mass in the direction opposite to the detection direction, the mass presses the coil spring and compresses and deforms the mass in the direction opposite to the detection direction. Move to. At this time, the trout is
Since it engages with the ring-shaped end of the coil spring and moves along the center line of the coil spring, the biasing force of the coil spring reliably acts on the center of gravity of the ball in the detection direction. Subsequently, when acceleration in the detection direction acts on the mass, the mass moves in the detection direction from the position moved in the opposite direction.

[0009]

FIG. 1 shows an acceleration sensor according to an embodiment of the present invention.
~ It demonstrates according to FIG.

FIG. 2 shows a state in which an airbag device 10 for a driver's seat as an occupant protection device is attached to a hub 12A of a steering wheel 12. Less than,
The schematic configuration of the airbag device 10 will be described with reference to this drawing.

An inflator 18 consisting of an upper case 14 and a lower case 16 is arranged in the center of the inside of the airbag device 10. A bulging portion 16A bulging toward the occupant side is formed at an axial center portion of the lower case 16, and a mechanical ignition type acceleration sensor as a passenger protection device that senses a sudden vehicle deceleration state is formed in the bulging portion 16A. 20 are stored. A detonator 22 as an ignition material is arranged directly above the acceleration sensor 20, and an enhancer (transfer agent) 24 is arranged directly above the detonator 22. A gas generating agent 26 is enclosed around the enhancer 24. Further, the coolant 2 is provided around the gas generating agent 26.
8 and a filter 30 are provided. Further, a plurality of gas holes 32 are formed on the peripheral surface of the upper case 14 at predetermined intervals.

The above-described inflator 18 is fixed to the central portion of the base plate 34, which is a strength member, with the upper case 14 side being penetrated. A folded bag body 36 is provided on the side of the occupant of the base plate 34 so as to cover the upper case 14 side of the inflator 18. A ring plate 38 is arranged on the inner peripheral edge of the opening of the bag body 36.
Is fixed to the base plate 34 so that the bag 3
The peripheral edge of the opening 6 is pressed against the side surface of the occupant of the base plate 34.

The folded bag body 36 is covered with an air bag pad 40 attached to the base plate 34 via an insert plate 39 which is formed into a predetermined shape by foaming urethane and insert-molded inside. There is. A substantially H-shaped thin portion 48 is formed on the side surface of the occupant of the airbag pad 40, and the thin portion 48 is broken at the time of sudden deceleration of the vehicle. As a result, the airbag pad 40 is deployed and the bag body 36 is inflated toward the occupant seated in the driver's seat.

The above is the schematic configuration of the airbag device 10. The acceleration sensor 20 for detecting the above-described rapid deceleration of the vehicle will be described below.

As shown in FIG. 1, the acceleration sensor 20
Includes a resin and cylindrical sensor body 50 (in FIG. 1, the same hatching is added, but to be exact, it has a two-part structure of an upper body and a lower body). The sensor body 50 is covered with a can cover 52 and a support plate 54.

A cylinder 56 is arranged in the sensor body 50, and a cylinder 56 is provided in the cylinder 56 as a mass that inertially moves to the front side (anti-occupant side; left side in FIG. 1) during rapid vehicle deceleration. A ball 58 is housed. One end of a drive shaft 60 as a trigger member is in contact with the moving direction side of the ball 58 in the detection direction. A block-shaped locking portion 60A is integrally formed at an axially intermediate portion of the drive shaft 60.
It is rotatably supported at both longitudinal ends of 0A.
The engaging portion 60A has a firing spring 62.
The brim portion 64A of the firing pin 64 as an ignition member that is pressed and urged by is locked. The detonator 22 described above is arranged on the movement trajectory of the firing spring 62.

On the other hand, at the other end of the drive shaft 60, the hook 6 provided at the tip of the bias pin 66.
8 is loosely fitted. The bias pin 66 is pressed and biased by a bias spring 70 as a biasing means. Specifically, one end of the bias spring 70 is locked (coupled) to the rear end of the bias pin 66 in a loosely fitted state, and the other end of the bias spring 70 contacts and locks with the sensor body 50 or the can cover 52. (Consolidated). Alternatively, one end of the bias spring 70 may be bent in a hook shape and the other end of the drive shaft 60 may be directly loosely fitted.

A coil spring 72 is inserted between the ball 58 and the wall portion 50A of the sensor body 50 on the side opposite to the detection direction of the ball 58. The coil spring 72 is arranged so that the center of gravity M of the ball 58 is located on the extension line 72A of the center line thereof.
The coil spring 72 is adapted to be pressed and deformed by the ball 58 when the ball 58 moves in the direction opposite to the detection direction (arrow-G direction in FIG. 1).

The spring constant and stroke of the coil spring 72 (the distance between the ball 58 and the wall 50A)
Is set to a value that minimizes the influence of the reverse acceleration in consideration of the load acting on the ball 58.

Next, the operation of this embodiment will be described. According to the acceleration sensor 20 of the present embodiment, when the vehicle 58 travels on a bad road or the like and the reverse acceleration (arrow G in FIG. 1) in the direction opposite to the detection direction acts on the ball 58, the ball 58
Moves in the direction opposite to the detection direction (arrow-G direction in FIG. 1) while compressing and deforming the coil spring 72. At this time, the ball 58 engages with the ring-shaped end of the coil spring 72 and moves along the center line of the coil spring 72, so that the biasing force of the coil spring 72 causes the ball 5 to move.
The center of gravity of 8 reliably acts in the detection direction (direction of arrow G in FIG. 1).

Subsequently, when acceleration in the detection direction (arrow G in FIG. 1) acts on the ball 58, this acceleration causes the ball 58 to move in the opposite direction (the position indicated by the imaginary line in FIG. 1). Move in the detection direction.

Therefore, as shown by the solid line in FIG. 3, the ball 58 of the acceleration sensor 20 of this embodiment moves in the direction opposite to the detection direction from the point P1 when the reverse acceleration acts against the biasing force of the coil spring 72. Therefore, as compared with the case where the ball 80 moves in the detection direction from the point P2 when the acceleration in the detection direction acts, like the acceleration sensor of the conventional example (see FIG. 4) shown by the imaginary line in FIG. Can be reduced.

Further, in this embodiment, the coil spring 7 is used.
Since the adjustment is made so that the influence of the reverse acceleration is reduced by the spring constant and the stroke of No. 2, the adjustment can be performed easily and with high accuracy.

In the present embodiment, the example of the acceleration sensor of the airbag apparatus for the driver's seat has been described, but the acceleration sensor of the present invention is not limited to the acceleration sensor of the airbag apparatus for the driver's seat, and others. It is also applicable to the acceleration sensor.

[0025]

The acceleration sensor according to the present invention is arranged such that the center of gravity of the mass is located on the extension line of the center line between the mass and the wall portion on the side opposite to the detection direction of the mass. Since the coil spring is provided so as to be compressed and deformed by the mass when the mass moves in the direction opposite to the detection direction, it has an excellent effect that the influence of the reverse acceleration can be reduced. Further, since the adjustment is made so that the influence of the reverse acceleration is reduced by the spring constant and stroke of the coil spring, it has an excellent effect that the adjustment is easy and the adjustment can be performed with high accuracy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an acceleration sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an airbag device for a driver's seat including an acceleration sensor according to an embodiment of the present invention.

FIG. 3 is a graph showing a relationship between acceleration acting on a mass of the acceleration sensor and time.

FIG. 4 is a sectional view showing an acceleration sensor according to a conventional example.

[Explanation of symbols]

 10 Airbag Device (Passenger Protection Device) 20 Accelerometer 22 Detonator (Ignition Material) 58 Ball (Mass) 60 Drive Shaft (Trigger Member) 64 Firing Pin (Ignition Member) 72 Coil Spring

Claims (1)

[Claims] 1. An ignition system for activating an occupant protection device mounted on a vehicle by igniting a mass that inertially moves in a detection direction when the vehicle rapidly decelerates, and an ignition material disposed outside the sensor by moving from a predetermined position. A trigger member that engages with the mass and the ignition member, holds the ignition member at a predetermined position in the non-inertial movement state of the mass, and allows the movement of the ignition member by the inertial movement of the mass in the detection direction. An acceleration sensor, wherein the mass is arranged in a direction opposite to the detection direction such that the center of gravity of the mass is located on an extension line of the center line between the mass and a wall portion opposite to the detection direction of the mass. An acceleration sensor, comprising: a coil spring that is compressed and deformed by the mass when moved to.