JPH03274464A - Collision detector - Google Patents

Abstract

PURPOSE:To enhance assembling properties by a simple structure and to achieve the reduction of cost and the enhancement of reliability by moving a wt. body forwardly at the time of collision to bring a movable contact and a fixed contact to a contact state to obtain a continuity state. CONSTITUTION:A mass 2 moves toward a leading end (the left direction of a drawing) against the energizing force of a main spring 8 by the impact force generated when a vehicle collides while slides with the inner peripheral surface of a case main body 3a. The movement of this mass 2 is determined by the equation of motion due to the parameters given by the wt. of the mass 2, the spring constant of the main spring 8 and that of a contact spring 9, a contact gap S and the coefficient of friction between the mass 2 and the inner peripheral surface of the main body 3a. When the movement quantity of the mass becomes the gap S or more, the spring load of the spring 9 becomes the contact load of contacts and a movable contact 6 comes into contact with the contact parts 4a, 5a of fixed contacts 4, 5 to bring external connection terminal parts 4b, 5b to a continuity state and, therefore, a current is supplied to the ignition device of an air bag from a battery to operate the air bag.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a collision detection device for detecting a collision of a vehicle or the like.

[Prior Art] Conventionally, there has been a collision detection device that detects a vehicle collision and outputs an electric signal for activating an air bag (see Japanese Patent Laid-Open No. 4-5578).

This collision detection device consists of a mass that is displaced against the urging force of a main spring in the event of a collision, a fixed contact held in a case that houses this mass, and a fixed contact that comes into contact with the mass as it is displaced. It consists of movable contacts, etc.

In addition, the case that forms the outer shell of the device includes a cylinder that slidably holds the mass, a cylindrical bulkhead that is integrally formed with a stopper that prevents the mass from jumping out when biased by the main spring, and the cylinder and cylinder. It consists of a metal cylindrical body that covers the outer periphery of the partition wall, and an end plate that is coupled to the open end of the cylindrical body and holds a lead wire connected to a fixed contact.

[Problem to be solved by the invention] However, in the conventional collision detection device described above, the case is
Because it consists of four parts: a cylinder, a cylindrical bulkhead, a cylinder, and an end plate, and because the fixed contact and the lead wire drawn out to the outside of the end plate are separate parts, the number of parts is large and the structure is complicated. It gets complicated.

As a result, the assembly becomes difficult and is susceptible to deterioration of parts over a long period of time, resulting in a decrease in reliability.

The present invention has been made based on the above circumstances, and its purpose is to reduce the number of parts and simplify the structure.
The objective is to provide a collision detection device that is easy to assemble and has high reliability.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a weight body biased to one side by a main spring, and a weight body fixed to a case accommodating the weight body and attached to the main spring. a stopper that restricts the amount of movement of the biased weight body to one side;
A predetermined gap is formed between a pair of fixed contacts held in the case and the fixed contacts in a state in which the contacts are urged toward the other side by a contact spring having a spring force weaker than the main spring and are in contact with the weight body. and a movable contact that comes into contact with the fixed contact as the weight body moves during a collision, wherein the case is an insulating case that houses the weight body and the main tin ring. and an insulating contact case that holds the fixed contact, houses the movable contact and the contact spring, and is coupled to the open end of the case body, and the fixed contact is The technical means is that the contact portion with the movable contact and the external connection terminal portion drawn out to the outside of the contact case are integrally formed.

[Operations and Effects of the Invention] In the collision detection device of the present invention having the above configuration, the case is composed of two parts, the case body and the contact case, and the contact part with the movable contact and the contact part that is drawn out from the contact case. The fixed contact is integrated with the external connection terminal.

As a result, the number of parts is reduced and the structure is simplified compared to the conventional device, so it is possible to improve ease of assembly and reduce costs. Furthermore, with the reduction in the number of parts and the simplification of the structure, the effects of component deterioration over a long period of time are reduced, so high reliability can be maintained.

[Embodiment] Next, a collision detection device of the present invention will be explained based on an embodiment shown in the drawings.

FIG. 1 is a sectional view of the collision detection device.

The collision detection device 1 of this embodiment includes a mass 2 having a predetermined weight M (heavy body of the present invention), a pair of fixed contacts 4.5 fixed to a case 3 accommodating this mass 2, and The movable contact 6 is housed in the case 3 with a contact gap S between it and the contact 4.5, and when the vehicle collides, the movable contact 6 moves to the fixed contact 4.5 as the mass 2 moves. When it comes into contact with it, it outputs an electrical signal that activates an airbag (not shown) installed in the vehicle.

The mass 2 has a cylindrical shape with a convex portion 2a formed in the center on the rear end side (right side in FIG. 1), and is disposed to be slidable inside the case 3.

The case 3 is made up of a cylindrical resin case body 3a having a bottom on the distal end side, and a resin contact case 3b coupled to the open end of the case body 3a, and the inside thereof is kept airtight.

The case body 3a has a thin wall portion 3c formed at the open end for heat caulking the contact case 3b, and a hollow disk-shaped stopper 7 is formed in front of the thin wall portion 3C (on the tip side) by heat caulking or the like. Fixed. The mass 2 is housed inside the case body 3a and is biased toward the rear end side by a main tin ring 8 having a predetermined spring constant of 1, and is pushed out from the case body 3a by coming into contact with the stopper 7 described above. is prevented from popping out. Further, when the mass 2 is in contact with the stopper 7 (the state shown in FIG. 1), the convex portion 2a of the mass 2 passes through the hollow portion of the stopper 7 and projects toward the rear end side of the stopper 7.

The fixed contact 4.5 has contact parts 4a, 5a, and the movable contact 6.
Terminal portions 4b and 5b for external connection drawn out to the outside of contact case 3b through a through hole (not shown) formed in contact case 3b are integrally formed, and terminal portions 4b and 5b for external connection are integrally formed. It is held in the contact case 3b by being press-fitted into the through hole.

This contact case 3b accommodates therein the movable contact 6 and the contact spring 9 that biases the movable contact 6, and the outer circumferential portion of the contact case 3b is heat caulked to the thin wall portion 3C of the case body 3a and is coupled to the case body 3a. has been done.

The movable contact 6 has a cylindrical cag shape in which a recess 6a that fits into the protrusion 2a of the mass 2 is formed in the center thereof, and is biased toward the mass 2 by a contact spring 9 having a predetermined spring constant of 2. There is.

The spring constant of the contact spring 9 is set to 2, and the spring constant of the main spring 8 is set to 1/3 to 1/8. Therefore, the movable contact 6 urged by the contact spring 9 is
In a state where the concave portion 6a of the movable contact 6 is fitted into the convex portion 2a of the mass 2, displacement toward the tip side is regulated, and at this position there is a contact gap S between the movable contact 6 and the fixed contact 4.5.

The collision detection device 1 having the above configuration includes a case body 3a (see FIG. 2) that houses the main spring 8 and the mass 2 and fixes the stopper 7, a contact spring 9 and a movable contact 6.
and the contact case 3b (see Fig. 3) in which the fixed contact 4.5 is assembled, and the outer periphery of the contact case 3b is heat caulked with the thin wall portion 3C of the case body 3a. be exposed.

Next, the operation of this embodiment will be explained.

Now, when a vehicle collides, the mass 2 resists the biasing force of the main spring 8 and moves toward the tip side (left side in FIG. 1) while slidingly contacting the inner circumferential surface of the case body 3a. The movement of the mass 2 is caused by the weight M of the mass 2, the spring constant of the main spring 8 of 1, the spring constant of the contact spring 9 of 2, the contact gap S, and the distance between the mass 2 and the inner peripheral surface of the case body 3a. It is determined by the equation of motion with parameters given by the resulting friction coefficient μ.

When the amount of movement of the mass 2 exceeds the contact gear 118, the spring load of the contact spring 9 that biases the movable contact 6 becomes a contact contact load, and the movable contact 6 moves to the contact portion 4a of the fixed contact 4.5.
, 5a and enter the closed state.

As a result, the external connection terminal portion 4b of the fixed contact 4.5,
5b becomes electrically conductive, electricity is supplied from the battery (not shown) to the airbag ignition device (not shown) through the device 1, thereby activating the airbag.

Note that, normally, the mass 2 is pressed against the stopper 7 by the spring load of the main spring 8, so the small impact force that occurs when the airbag does not need to be activated or when passing over an uneven road, etc. For square 2
movement can be suppressed. In addition, even if the mass 2 moves due to a light collision or a small impact force, by setting the contact cap S appropriately, the moving amount of the mass 2 is prevented from exceeding the contact gap S, and the movable contact 6 is fixed. Contact with the contacts 4.5 can be prevented.

As described above, in this embodiment, the case 3 is composed of two parts: the cylindrical case body 3a and the contact case 3b coupled to the open end of the case body 3a. Also, the contact portion 4 that the movable contact 6 comes into contact with in the event of a collision
a, 5a, and external connection terminal portions 4b, 5b drawn out to the outside of the contact case 3b are integrally formed.
．． 5 was adopted.

As a result, the number of parts is reduced and the structure is simplified compared to the conventional device, making it easier to assemble and reducing costs. Furthermore, since the influence of component deterioration over a long period of time is reduced, high reliability can be obtained.

Next, a second embodiment of the present invention will be described.

FIG. 4 is a sectional view of the collision detection device 1 of this embodiment.

In this embodiment, the outer diameter of the mass 2 is reduced to reduce the weight M so that the contact point does not close due to a small impact force.

By reducing the outer diameter of mass 2, mass 2
A shaft 1o that guides the movement of the contact case 3b passes through the center of the mass 2 and extends from the center of the bottom of the case body 3a to the center of the bottom of the contact case 3b.

Therefore, the mass 2 is slidably assembled to the shaft 1o so that it can move along the outer circumference of the shaft 1o in the event of a collision.

In addition, in the center of the movable contact 6, there is a movable contact 6 in the event of a collision.
A hole slightly larger than the diameter of the shaft 10 is formed so that the shaft 10 can move along the outer periphery of the shaft 10.

In this collision detection device 1, by reducing the weight iM of the mass 2, the mass 2 does not move even with a small impact force, and the contacts maintain an open state. As a result, activation of the airbag in the event of a minor collision can be prevented.

Next, a third embodiment of the present invention will be described.

FIG. 5 is a sectional view of the collision detection device 1 of this embodiment.

In this embodiment, a cylindrical shell 11 that serves as a guide surface when the mass 2 moves is provided on the inner periphery of the case body 3a.

Since this shell 11 forms an airtight chamber inside the case body 3a in which the main spring 8 is disposed, the gap between the inner peripheral surface of the shell 11 and the outer peripheral surface of the mass 2 is 0.01 ml.
It is set to ~0.1 mm.

In this way, by forming an airtight chamber on the tip side of the mass 2, it is possible to reduce the impact force with a relatively short period (a few milliseconds or more, tens of thousands of When a shock waveform of G occurs), damping is applied to the movement of the mass 2 so that the device does not operate.

On the other hand, when receiving an impact force that generates an impact waveform of several tens of G over a period of around ten milliseconds to several tens of milliseconds (occurs during a vehicle collision), the damping applied to the movement of mass 2 becomes smaller. , the contacts can be closed as the mass 2 moves.

Note that a formula representing how damping is applied is shown below.

CoLP ・V/D' C, damping coefficient P: Viscosity coefficient of internal fluid (air here) ■: Moving speed of mass 2 D Gap size between Nigel 11 and mass 2 From the above formula,
It can be seen that the faster the moving speed (■) of square 2 is, the more damping is applied.

Next, a fourth embodiment of the present invention will be described.

FIG. 6 is a sectional view of the collision detection device 1 of this embodiment.

In this embodiment, a cushion 12 made of rubber, soft plastic, or tin ring is attached to the bottom of the case body 3a.

This cushion 12 absorbs the repulsive force acting on the mass 2 that hits the bottom of the case body 3a when receiving a large impact force.

In other words, when receiving a large impact force, the mass 2 that hits the bottom of the case body 3a returns to its original position vigorously due to the repulsive force and the biasing force of the main spring 8.
- Contacts that are once closed open before the impact force disappears, which may make it impossible to maintain the energization time required to ignite the airbag.

Therefore, by attaching the cushion 12 to the bottom of the case body 3a, the repulsive force acting on the mass 2 can be absorbed, and the time for the mass 2 to return to its original position is delayed.
The energization time can be increased.

In addition, a magnet is attached instead of the cushion 12, and the mass 2
A similar effect can be obtained even if it is made of a magnetic material.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a sectional view of a collision detection device, FIG. 2 is a sectional view of a case body in which a main spring, a mass, and a stopper are assembled;
FIG. 3 is a cross-sectional view of a contact case in which a contact spring, a movable contact, and a fixed contact are assembled, FIG. 4 is a cross-sectional view of a collision detection device showing a second embodiment of the present invention, and FIG. FIG. 6 is a cross-sectional view of a collision detection device showing a fourth embodiment of the present invention. In the diagram 1... Collision detection device 2... Mass (heavy body) 3.
...Case 3a...Case body 3b...Contact case 4.5...Fixed contacts 4a, 5a...Contact parts 4b, 5b...Terminal part for external connection 6...Movable contact 7.・Stopper 8・
...Main tin ring 9...Contact spring S...
Contact gap (gap)

Claims (1)

[Claims] 1) A weight body urged to one side by a main spring; and a weight body fixed to a case housing the weight body and urged by the main spring to one side. A stopper for regulating the amount of movement, a pair of fixed contacts held in the case, and a contact spring having a weaker spring force than the main spring are biased toward the other side, and the fixed contact is in contact with the weight body. A collision detection device comprising: a movable contact having a predetermined gap between the contact and the fixed contact as the heavy body moves during a collision; an insulating case body that houses the main spring; and an insulative contact case that holds the fixed contact, houses the movable contact and the contact spring, and is coupled to the open end of the case body. The collision detection device is characterized in that the fixed contact is integrally formed with a contact portion with the movable contact and an external connection terminal portion drawn out to the outside of the contact case.