JPH09251829A - Shock sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a shock sensor using a lead switch which maintains close operation while detection and checking shock with a plurality of sensors and which has its sufficient contact capacity for driving an actuated body. SOLUTION: This shock sensor is provided with a plurality lead of switches 2 provided on a wall face opposite to a casing 1, a magnet 3 for switching the lead switch adjacent to the lead switches 2 swingably, and a spring 4 whose one end is fixed to the casing 1 and whose other end is fixed to a surface of the magnet 3 to pull back the magnet 3 and is constituted so that at least on of the lead switches 2 includes a second lead switch 2a having its contact capacity capable of directly switching the driving power supply of the actuated body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock sensor, and more particularly to a shock sensor having a prolonged reed switch closing operation and improved withstand current.

Among the impact sensors, an impact sensor using a reed switch is one in which the reed switch is closed (ON) at a certain impact G or more, and the vibration applied to a fixed body or a moving body or the acceleration of the impact is electrically measured. It is a measuring instrument that converts into a signal.
In the case of fixed objects such as buildings and structures fixed on the ground, prevent the destruction of facilities such as computers that form the center of information and dangerous facilities such as chemical plants from earthquakes. However, a shock sensor is used to prevent a secondary disaster caused by it.

Further, in the case of a moving body such as a vehicle or an aircraft, it is essential to improve the riding comfort, but recently, for example, when an automobile crashes, an airbag is instantly used. It is also attracting attention as a sensor that detects a shock to inflate.

By the way, since the acceleration itself due to the shock occurs instantly, in the case of a car collision accident, the sensor operates the circuit to detect the shock and perform some control, or the gas generating agent is detonated. In order to do so, it is required that the duration of sensing be long and that it withstand a large current.

[0005]

2. Description of the Related Art FIG. 5 is an explanatory view of an example of a shock sensor using a reed switch. FIG. 5 (A) is a partially cutaway perspective view of the shock sensor, and FIG. 5 (B) shows a shock force G and an output. FIG. 6 is a block diagram of an example of a control circuit for an air bag of an automobile. In the figure, 1 is a housing, 2 is a reed switch,
3 is a magnet, 4 is a spring, 6 is a main sensor, 6a is a first sub-sensor, 6b is a second sub-sensor, 6c is a third sub-sensor, 8 is explosive, and 10 is an impact sensor.

In FIG. 5A, an impact sensor 10 includes a housing 1, a reed switch 2 integrally fixed to the housing 1, and an annular magnet 3 swingable on the reed switch 2. It is a type of mechanical sensor that is arranged so as to be fitted on the outside.

The magnet 3 is made of, for example, a sintered body of ferrite. Then, it is pressed by the coiled spring 4 and is constantly urged in the direction in which the impact force G is applied. Now, when the impact force G is applied in the direction of the arrow, the reed switch 2 rapidly moves in the direction of the impact force G together with the housing 1, but the magnet 3 has inertia so that the spring 4 is not pushed. Then, it relatively moves in the direction opposite to the direction in which the impact force G is applied. The position where the reed switch 2 is closed by the movement of the magnet 3 is limited. Therefore, for example, a hard synthetic resin stop member 9 is struck against the stop member 9 so as not to go over. Meanwhile, when the magnet 3 moves to the sensitive position of the reed switch 2, the reed switch 2 is closed and put into an operating state.

The output obtained by closing the reed switch 2 to which the power source is connected is closed about 10 msec after the impact force G is applied as shown in FIG. 5 (B). However, since the magnet 3 hits the stop member 9 and bounces back and is returned to the original state by the pressing of the spring 4, the closing duration of the reed switch 2 is about 15 msec.

FIG. 6 is a block diagram of an example of a control circuit for an automobile airbag. The main sensor 6 is installed in a dashboard or the like, detects an impact force G due to a collision or the like, and also serves as an ignition switch for igniting explosive powder for inflating an airbag. For this reason, it is necessary to cause a large current of several amperes to flow through the filament of the ignition source of the explosive to burn it.

In addition to the main sensor 6, the collision detection of an automobile is, for example, a first sub-sensor 6a which is installed at the head of the vehicle and operates at 100G, and a first auxiliary sensor 6a which is installed on the left side of the engine room and operates at 50G. As with the second sub-sensor 6b, a third sub-sensor 6c mounted on the right side is also used. A shock sensor made of, for example, a semiconductor is used as the sub-sensors 6a, 6b, 6c, and a shock sensor using a reed switch 2 driven by a magnet 3 is used as the main sensor 6.

That is, the control circuit composed of the sensors 6, 6a, 6b, 6c and the like first takes the logical sum D of the second sub-sensor 6b and the third sub-sensor 6c when a collision occurs. , The logical sum D and the first sub-sensor 6a take the logical product C ₁ , and finally the logical product C ₁ and the main sensor 6 take the logical product C ₂ . When it is determined that a collision occurs, for example, the explosive 8 that generates a large amount of nitrogen gas when decomposed, such as atrium azide, is ignited.

As described above, when detecting a collision accident of an automobile, a logical sum or a logical product of a plurality of sensors arranged at various positions of the vehicle body is taken so as to prevent malfunction during traveling. There is.

By the way, for example, a plurality of sub-sensors 6a,
Since 6b and 6c are combined to detect the impact, the closing time during which the main sensor 6 is operating continues while the sub-sensors 6a, 6b and 6c are appropriately activated to recognize the collision. There is a need.

Therefore, the present inventors have used at least one of the magnet 3 and the stop member 9 as an elastic material to absorb kinetic energy and suppress the moving speed of the magnet 3 (Japanese Patent Laid-Open No. Hei 5-
288764), to increase the closing operation time of the reed switch 2, that is, to increase the closing operation time of the reed switch 2 by arranging multiple reed switches in parallel to give different operation timings (Publication No. 95-02929). Propose to lengthen.

[0015]

By the way, the impact sensor not only constitutes a control circuit as illustrated in FIG. 6, but also, for example, detonates a gas generating agent in order to inflate an airbag of an automobile. In this case, as shown by a thick line passing through the logical sum C ₁ from the main sensor 6, a large current of 10 A, for example, is used to open and close the power source for driving or activating the actuated body. .

However, in the conventional shock sensor, the power source is opened and closed by the switch driven through the control circuit, and it is considered that the reed switch incorporated in the sensor is used to directly open and close the power source. It wasn't.

Therefore, an object of the present invention is to provide an impact sensor in which the power source can be directly opened and closed by at least one of a plurality of reed switches configured to extend the operation time of the impact sensor.

[0018]

According to a first aspect of the present invention, there are provided a plurality of reed switches installed on opposite wall surfaces of a housing, and the reed switches provided swingably close to the reed switches. A reed switch, a spring for opening and closing the reed switch, and a spring having one end fixed to the housing and the other end fixed to one surface of the magnet to pull back the magnet. One is solved by an impact sensor configured to include a second reed switch having a contact capacity capable of directly opening and closing a driving power source of an actuated body.

Further, in the second reed switch, the closing operation timing is at least the second or later in the second aspect, and the reed piece is the cobalt-type in the third aspect.
This is solved by an impact sensor configured to consist of ferromagnet.

That is, in claim 1, at least one of the plurality of reed switches arranged in parallel for the purpose of extending the closing operation time is a second reed switch, and the drive power source for the operated body is directly connected. It can be opened and closed. Then, this second reed switch confirms that the control circuit has undergone a shocking change such as a collision or a drop, and performs a closing operation at least until the actuated body is driven. I'm trying to continue. Then, the logical operation is performed by the fact that the second reed switch is in the closing operation and the control circuit confirms the abnormality, and the power supply for directly driving the actuated body is opened from the second reed switch. I am trying.

Next, in claim 2, since it takes time to confirm that a shocking abnormality has occurred by the plurality of sub-sensors, it takes time. Therefore, the second reed switch should be adjusted to meet the delay of the time. The closing operation timing of is set to at least the second timing. That is, when two reed switches are used in parallel, the closing operation timing is second.

Further, an iron-nickel magnetic material (52 alloy) is used for the lead piece of the ordinary reed switch, but the lead piece of the second reed switch is made of cobalt-iron having excellent withstanding current resistance. A magnetic material (trademark: Nibucoloy) is used. Further, the power source for driving the operated body can be opened and closed directly.

That is, when performing control by the impact sensor, among the plurality of reed switches, the switch that initially performs the closing operation may flow a low current for the control circuit.
It is convenient to use a lead piece made of a cobalt-iron magnetic material when a large driving current is passed by a switch that is closed in the latter half.

[0024]

1 is a perspective view of an embodiment of the present invention, FIG. 2 is a plan view schematically showing an embodiment of the present invention,
FIG. 3 is a shock G-output characteristic of one embodiment of the present invention, and FIG. 4 is a block diagram of an example of a control circuit of one embodiment of the present invention. In the figure, 1 is a housing, 2 is a reed switch, 2a is a second reed switch, 3 is a magnet, 4 is a spring, 5 is an output terminal, 6
Is a main sensor, 6a is a first sub-sensor, 6b is a second sub-sensor, 6c is a third sub-sensor, 7 is a control circuit, 8 is explosive, and 10 is an impact sensor.

In FIGS. 1 and 2, the basic components of the shock sensor 10 are a plurality of reed switches 2 and a magnet 3 supported in a housing 1. In this case, one of the two is a reed switch, for example, a reed switch 2 using a Fe-Ni-based 52 alloy, and the other one is a Co-F on the reed.
It is a second reed switch 2a using an e-based alloy (trademark: Nibcoloy) and capable of passing a large current. In this way, the reed switches 2 and 2a are selectively used, for example, in the 52 alloy, the current capacity is about 1 A at the most. Therefore, it is used for explosive explosives in airbags 10
When the current of A is passed, it is fused by one use, and it is required to endure about 30 uses for the test. Therefore, in this case, a reed switch 2 is provided with a Co—Fe based reed piece 2a and a current capacity of 10 A
It is designed to withstand repeated use.

The housing 1 is made of, for example, a plastic mold, and two reed switches 2 and 2a are fixed on the opposite wall surfaces. The magnet 3 can swing in the housing 1 while being close to each other along the longitudinal direction of the reed switches 2 and 2a. One end of a spring 4 is fixed to one surface of the magnet 3, and the other end of the spring 4 is fixed to the housing 1. Spring 4
Is a tension spring such as a coil spring,
The magnet 3 is always urged to be attracted by the spring 4.

Here, the two reed switches 2, 2a are
Since the second reed switch 2a capable of passing a large current has a longer glass tube for sealing than the reed switch 2, when the one end is aligned and fixed to the housing 1, the reed switch 2,
The closing motion area of 2a is shifted. Therefore,
When the housing 1 moves with the reed switches 2 and 2a due to an impact G or the like, the magnet 3 tries to stay due to inertia, so that the magnet 3 resists the bias of the spring 4 and the spring 4 relatively.
Move in the direction indicated by the hatched arrow to extend.
Then, the reed switch 2 enters the closing operation first,
It opens when the magnet 3 passes by. On the other hand, the position of the second reed switch 2a is adjusted so that the reed switch 2 overlaps before the opening operation and enters the closing operation. Also, 2
The output terminals 5 from the reed switches 2 and 2a of the book have a parallel connection configuration in which one is commonly connected and the other is individually led out from the housing 1.

In FIG. 3, when the magnet 3 receives a rapid acceleration due to the shock G, the reed switch 2 first enters the closing operation by the movement of the magnet 3, and the second reed switch continues before the magnet 3 passes by. The switch 2a enters the closing operation. The second reed switch 2a compensates for the closing operation while the impact G is stopped and the magnet 3 is pulled back by the bias of the spring 4 and the reed switch 2 is again closed.

As a result, the output terminal 5 is closed by the reed switch 2 and subsequently the second reed switch.
2a performs the closing operation, and further, the closing operation continues for a long time until the reed switch 2 performs the closing operation again.

FIG. 4 shows an example in which the impact sensor of the present invention is applied to a control circuit for an automobile air bag. Although the basic structure for detecting a collision of an automobile is the same as the conventional one, the impact sensor 10 according to the present invention is used as the main sensor 6, and the main sensor 6 has a reed switch 2 and a second sensor capable of supplying a large current. Are arranged in parallel with the reed switch 2a. Besides, for example,
The first sub-sensor installed at the top of the car and operating at 100G
6a, a second sub-sensor 6b which is mounted on the left side of the engine room and operates at 50G, and a third sub-sensor 6c which is also mounted on the right side are also used. These sub-sensors 6a, 6b,
A shock sensor made of, for example, a semiconductor is used for 6c.

When a collision occurs, the main sensor 6 and the sub-sensors 6a, 6b, 6c first take the logical sum D of the second sub-sensor 6b and the third sub-sensor 6c, and obtain the logical sum D thereof. The logical product C ₁ is calculated with the second sub sensor 6b. In addition, the control circuit 7
Is the logical sum D, the output of the second sub-sensor 6b and the main sensor 6
When the output of the reed switch 2 is input and the collision is judged by the logical product C _{2 of} the logical sum C ₁ and the output of the control circuit 7 and the output of the second reed switch 2a of the main sensor 6, for example, The explosive 8 which generates a large amount of nitrogen gas such as sodium chloride is ignited. The large current for igniting the explosive 8 at this time is supplied by the second reed switch 2a of the main sensor 6.

In this example, two reed switches having different lengths are illustrated. However, even if the reed switches have the same length, they are arranged so that the operation timing is deviated with respect to the shock G, and the current capacity of the slower-acting switch can be increased. However, various modifications are possible. Regarding the relationship between the magnet and the spring,
The tension spring always urges the magnet in a direction to draw it, and the impact G acts to stretch the spring. However, the push spring urges the magnet in a direction to keep it away from the impact G in a direction to compress the spring. , And various modifications are possible.

[0033]

According to the impact sensor using a plurality of reed switches according to the present invention, it is possible to simultaneously detect the impact G and drive the object to be actuated with the timing delayed from the detection.

As a result, the present invention greatly contributes to the expansion of demand for impact sensors, for example, to meet the demand as an impact sensor for controlling an air bag that inflates in the event of an automobile collision.

[Brief description of drawings]

FIG. 1 is a perspective view of one embodiment of the present invention.

FIG. 2 is a plan view schematically showing an embodiment of the present invention.

FIG. 3 is a shock G-output characteristic of an example of the present invention.

FIG. 4 is a block diagram of an example of a control circuit according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of an example of an impact sensor using a reed switch.

FIG. 6 is a block diagram of an example of a control circuit for an airbag of a vehicle.

[Explanation of symbols]

1 housing 2 reed switch 2a second reed switch 3 magnet 4 spring 5 output terminal 6 main sensor 6a first sub sensor 6b second sub sensor 6c
Third sub-sensor 7 Control circuit 8 Explosive 10 Impact sensor

Claims (3)

[Claims] 1. A plurality of reed switches installed on opposite wall surfaces of a housing, a magnet swingably close to the reed switches to open and close the reed switch, and one end of which is fixed to the housing, The other end has a spring fixed to one surface of the magnet to pull back the magnet, and at least one of the reed switches has a contact capacity capable of directly opening and closing the drive power source of the actuated body. An impact sensor including a second reed switch. 2. The shock sensor according to claim 1, wherein the second reed switch has a closing operation timing of at least the second closing timing. 3. The shock sensor according to claim 1, wherein a lead piece of the second reed switch is made of a cobalt-iron magnetic material.