JPH0610873U - Acceleration sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] The output of the acceleration sensor causes chattering, or the ON time is longer than the ON time determined by the predetermined acceleration.
Prevent the time from becoming short. [Structure] By using a rubber magnet 17 as a magnetic body as a weight, the impact of a collision between the weight and the casing 8'is attenuated and the rebound is reduced, so that chattering of the output of the sensor due to the impact or ON due to the rebound.
Prevent time reduction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an acceleration sensor which is attached to a vehicle or the like and detects an acceleration applied to the vehicle.

[0002]

[Prior art]

 Conventionally, an acceleration sensor 1 mounted on a vehicle or the like detects acceleration applied to the vehicle, that is, a shock, and when the acceleration becomes larger than a preset value, an acceleration sensor 1 that activates a safety device such as an airbag is shown in FIG. 3, a base 3 having a mounting hole 2, a tubular case 4 attached to the base 3, a reed switch 5 incorporated in the tubular case 4, and a tubular type movable in an arrow direction X. A weight 6 formed in a donut shape by a magnetic body attached to the case 4, a coil spring 7 also attached to the cylindrical case 4 for urging the weight 6 in a direction against acceleration, a weight 6 and a coil spring. A casing 8 having a cover and a lower end attached to the base 3 and a casing 8 ′ attached to the casing 8 are provided.

Further, the terminals 9 and 9 ′ output from the reed switch 5 are pulled out from the bottom surface of the base 3, the terminal 9 is connected to the power supply section 11 by the wiring 10, and the terminal 9 ′ is connected via the wiring 10 ′. Is connected to the air bag, and is connected to the switch 13 via the wiring 12. The switch 14 is operated by the microcomputer 14, which is connected to the semiconductor acceleration sensor 15 via the A / D converter 16 and forms a circuit as shown in FIG. 4 as a whole.

In such an acceleration sensor 1, when an acceleration of a predetermined value or more is applied in the arrow direction Y, the inertial force becomes equal to or greater than the urging force of the coil spring 7, the weight 6 moves to 6 ', and the weight 6 moves. A contact point of the reed switch 5 comes into contact with the generated magnetic field to electrically connect the power source and the air bag, and to prevent explosion of the air bag due to malfunction of the microcomputer 14, the semiconductor acceleration sensor 15, and the A / D converter 16. Has become.

[0005]

[Problems to be solved by the device]

 By the way, in such a conventional acceleration sensor 1, when acceleration is applied to the sensor and the weight 6 urged by the spring 4 collides with the casing 8 ′, a high G as shown in FIG. 5A is applied. When a collision occurs, the acceleration sensor 1 causes chattering as shown in FIG. 5B due to the impact of the collision, and the ON state is not maintained. If the acceleration sensor 1 chatters while the vehicle collision determination signal is being output by the microcomputer shown in FIG. 5C, the airbag may fail to fire. When the weight 6 collides with the casing 8 ′ due to the addition of a long G having a long period as shown in FIG. 6D, the weight 6 bounces, and the ON time of the acceleration sensor 1 becomes a predetermined value as shown in FIG. 6E. The time becomes shorter than the ON time determined by the acceleration, and there is a problem that the airbag does not fire because it passes the vehicle collision determination signal by the microcomputer as shown in FIG. 6 (f).

Therefore, an object of the present invention is to provide an acceleration sensor having a simple structure, which is less likely to cause chattering even when an impact is applied.

[0007]

[Means for Solving the Problems]

 Therefore, in order to achieve the above-mentioned object, the present invention provides elasticity or flexibility to a magnet that moves when an impact is applied, and uses a rubber magnet as a magnet. The surface of is covered with a member having elasticity or flexibility.

[0008]

【Example】

 Next, an embodiment of the present invention will be described with reference to the drawings.

The same parts as those of the conventional structure are designated by the same reference numerals, and detailed description thereof will be omitted. 1 shows an example in which a rubber magnet is used for the weight 17, and FIG. 2 shows an example in which a magnetic body covered with rubber or resin is used for the weight 18.

The difference from the conventional example of the present invention lies in the construction of the magnet, and the embodiment shown in FIG. 1 is constructed by a rubber magnet 17 as a magnet. Since this rubber magnet 17 has elasticity or flexibility, chattering can be reduced due to its elasticity even when it hits the casing against the elasticity of the spring 7 when an impact is applied.

FIG. 2 shows another embodiment of the present invention, in which the surface of the magnet 6 is covered with a resin 18 having elasticity or flexibility.

[0012]

[Effect of device]

 As described above, according to the present invention, since elasticity or flexibility is imparted to the magnet, it is possible to reduce the impact due to the collision between the weight (magnet) and the casing and to reduce the rebound. For this reason, chattering as shown in FIG. 5 (b) and operation in which the ON time is shortened as shown in FIG. 6 (e) are prevented, and in the airbag system as shown in FIG. The effect is that the misfire of the back can be surely eliminated.

[Brief description of drawings]

FIG. 1 is a right half sectional view showing an embodiment of the present invention.

FIG. 2 is a right half sectional view showing another embodiment of the present invention.

FIG. 3 is a right half sectional view of a conventional acceleration sensor.

FIG. 4 is a circuit diagram of an airbag system using an acceleration sensor.

FIG. 5 (a) is an acceleration generated by a vehicle collision,

FIG. 5B is the output of the acceleration sensor.

FIG. 5 (c) is a collision determination signal by the microcomputer.

FIG. 6 (d) is an acceleration generated by a vehicle collision.

FIG. 6 (e) is the output of the acceleration sensor.

FIG. 6 (f) is a collision determination signal by the microcomputer.

[Explanation of symbols]

 1 Reed switch 6 Weight (magnet) 7 Spring 8 Casing 17 Magnet 18 Covering material

Claims (3)

[Scope of utility model registration request] 1. A magnet having elasticity or flexibility that moves when an acceleration is applied, a spring that urges the magnet in one direction, and a reed switch that is arranged in parallel with the moving direction of the magnet. An acceleration sensor characterized by being. 2. The acceleration sensor according to claim 1, wherein the magnet is a rubber magnet. 3. The acceleration sensor according to claim 1, wherein the magnet is covered with a member having elasticity or flexibility.