JP2658855B2 - Shock sensing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle collision detection switch, and more particularly to a shock detection device which acts as a trigger for inflating an airbag in the event of a vehicle collision.

[0002]

2. Description of the Related Art As a conventional impact sensing device, as shown in FIG. 6, a steel ball 1 is held by an attraction force of a permanent magnet 2, and when an impact force F is applied, the steel ball is ejected so as to be interposed. Some are configured to operate the switch 4 via the object 3.

[0003]

However, in such a conventional impact sensing device, the impact direction is effective only in one direction, and when the magnitude of the impact force to be sensed is set. Since the attraction force of the permanent magnet 2, the rolling friction of the steel ball 1, the accuracy of the intermediate inclusion 3, the contact reliability of the switch 4, and the like must be taken into consideration, the magnitude of the impact force to be sensed is set with high accuracy. There is a problem that it is difficult.

It is an object of the present invention to provide an impact sensing device which eliminates the above-mentioned disadvantages.

[0005]

In order to achieve the above object, the present invention provides an impact sensing device comprising: a fixed member provided with an MR element; a movable member opposed to the MR element and provided with a permanent magnet; And an elastic member having a permanent magnet at an end and a plurality of MR-E elements, and one end of the fixed member and one end of the movable member are rotatable. The fixed member and the movable member are provided with a coil spring, and the other end of the movable member is connected with the elastic member. A pulse signal of the MR-E element and a pulse signal of the MR element in a shock sensing device in which a plurality of the MR-E elements are arranged radially around the permanent magnet and opposed to a permanent magnet mounted at an end of the MR element. Combination with resistance value More, and a control circuit for generating a sensing pulse signal.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. 1 (a) and 1 (b) are a plan view and a side view showing one embodiment of the present invention. In the figure, the MR element 11
Is a magnetoresistive element whose resistance changes when it receives magnetism, and is represented as shown in FIG. Resistance of MR element 11
The magnetic field strength characteristics are shown in FIG. The MR element 11 is incorporated in a fixed member 12. A permanent magnet 13 is incorporated in the movable member 14 so as to face the MR element 11. The fixed member 12 and the movable member 14 are connected by a pin 15 so that the movable member 14 is rotatable about the pin 15. The coil spring 16 is coupled to the fixed member 12 and the movable member 14, and has a permanent magnet 18 at the other end. The MR-E elements 19a ₁ , a ₂ , b ₁ , and c have a built-in magneto-resistive element whose resistance changes when it receives magnetism therein, and a waveform shaping circuit. The sensor detects magnetism and generates a pulse output. The MR-E elements 19 a ₁ , a ₂ , b ₁ , and c are arranged radially around the permanent magnet 18 near the permanent magnet 18.

FIG. 5 is a block diagram showing a control circuit.
A constantly monitors the resistance value of the MR element 11, and B
Is an MR-E element. The pulse output from 19a _1, a _2, C also D pulse output from 19b _1, b ₂ is monitoring the pulse output from 19c. R-H characteristics of the MR element 11 resistance when the magnetic field H ₁ is applied as shown in FIG. 3 is a R _1. Similarly, when H ₂ , R ₂ , and when H ₃ , R ₂
The R ₄ when _3, H _4. Control circuit, the resistance value of A is receiving a pulse output when the R ₂ B, and generates a pulse output from the Out terminal. The resistance value of A to generate a pulse output from the receiving Out terminals B and C either pulse output when R _3. Furthermore, the resistance value of A to generate a pulse output from the time B, C, Out terminal receives either pulse output D of R _4. Now, when an impact force is applied from the F ₁ direction (e.g. a car in front), the elastic member 17 moves in the direction of impact, since the permanent magnet 18 approaches the MR-E element 19c, MR-
The E element 19c operates to generate a pulse output. At this time, at the same time, the movable member 14 moves away from the fixed member 12 and the gap between the MR element 11 and the permanent magnet 13 is widened.
Resistance value of the element ^{11 is} R ^{_4. F} 2
^{When an impact force is applied from the direction, the MR-E element 19b} 2
^{But it operates,} the resistance value of the MR element 11 is R _3, and the the impact force from the F ₃ direction Ruru applied, and operation MR-E element 19a _2, the resistance value of the MR element 11 is R _2.

[0008]

As described above, according to the present invention, not only the impact force in one direction but also the switch contact reliability can be obtained by providing the control circuit in the impact sensing device composed of the MR element and the MR-E element. Therefore, an inexpensive and reliable impact sensing device can be realized.

[Brief description of the drawings]

1 (a) and 1 (b) are a plan view and a front view showing an embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of an MR element.

FIG. 3 is a resistance-magnetic field strength characteristic diagram of an MR element.

FIG. 4 is a circuit diagram of an MR-E element.

FIG. 5 is a block diagram of a control circuit.

FIG. 6 is a configuration diagram showing a conventional impact sensing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel ball 2 Permanent magnet 3 Intermediate inclusion 4 Switch 11 MR element 12 Fixed member 13, 18 Permanent magnet 14 Movable member 15 Pin 16 Coil spring 17 Elastic member 19 MR-E element

Claims (1)

(57) [Claims] 1. A fixed member having a magnetoresistive effect element (hereinafter, referred to as an MR element) having a resistance value changed by magnetism, a movable member having a permanent magnet opposed to the MR element, and a sensor for detecting a shock. Element (hereinafter referred to as MR) having a built-in elastic member movable in the direction of impact and having a permanent magnet at an end thereof, and a waveform shaping circuit for outputting a pulse when subjected to magnetism.
-E element. ), One end of the fixed member and one end of the movable member are rotatably connected by a pin, and a coil spring is provided between the fixed member and the movable member. The elastic member is coupled to the other end of the movable member, and the MR-E element faces the permanent magnet attached to the end of the elastic member, and radially around the permanent magnet. A plurality of shock sensing devices, comprising: a control circuit for generating a sensing pulse signal by a combination of a pulse signal of the MR-E element and a resistance value of the MR element. .