JPH04218780A - Impact sensor - Google Patents

Abstract

PURPOSE:To enable execution of reliable detection by a construction wherein a distance between the central axes of two coil springs is made shorter than the outside diameters of the coils so that the coils may not come into contact with each other in a non- impact state, and the contact of the coil springs is ensured not only at one point, but on the whole periphery, when an impact of prescribed strength or more is impressed. CONSTITUTION:Diameters of wires, outside diameters, wind pitches, etc., of coil springs l and 2 having conductivity are made to be of the same specification and a distance between the central axes 8A and 8B of the springs l and 2 is provided to be shorter than the outside diameters of the coils. In a state of no impact being impressed, accordingly, terminals 3 and 4 are put in noncontinuity with each other. When an impact in the direction 9 of impression of the impact is applied, an impact detecting body 5 compresses the springs l and 2. When the impact of prescribed strength or more is impressed, the springs l and 2 come into contact with each other. Then the terminals 3 and 4 are put in a state of continuity and the impact of prescribed strength or more is detected. At this time, the contact of the springs l and 2 is ensured not only at one point, but on the whole peripheries of the coils, and a stable state of continuity of the terminals 3 and 4 can be ensured.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact sensor, and more particularly to an impact sensor used in devices operated by impact, such as automobile seat belts and airbags.

0002

[Prior Art] Conventionally, this type of impact sensor has
It consists of a magnet that cannot be moved due to impact, and a reed switch that is closed by this magnet.

FIG. 3 is a perspective view of an impact sensor showing an example of such a conventional impact sensor. As shown in FIG. 3, in the conventional reed switch type impact sensor, a ring-shaped magnet 13 is supported by a spring 14 around a reed switch 11 having a terminal 12 fixed to a support base 10. This magnet 13 is set by a stopper 16 at a position where the reed switch 11 is in the OFF state, and a spring 14
is fixed to a fixed plate 17. For example, when an impact in the impact direction 9 is applied above a certain level, the magnet 13 moves into the hole 18.
The reed switch 11 is turned on. When the impact disappears, the magnet 13 returns to its home position on the stopper 16 due to the elasticity of the spring 14.

0004

[Problems to be Solved by the Invention] The above-mentioned conventional impact sensor has a built-in impact sensor that outputs an output indicating the presence or absence of an impact that exceeds a certain level.
This is done by Therefore, if a contact failure occurs in the reed switch itself, there is a drawback that the reed switch loses its function as an impact sensor.

[0005] An object of the present invention is to provide an impact sensor that can eliminate contact failure caused by such an impact sensor, reliably extract a detection signal, and reduce failure rate.

[0006]

[Means for Solving the Problems] The impact sensor of the present invention includes an impact sensing body that receives force due to an impact, a movable stage that supports the impact sensing body, one end of which is connected to a signal terminal, and the other end of which is connected to the movable stage. It has two conductive coil springs fixed to a stand, and a case containing the shock detector, the movable stand, and the two coil springs, and the two coil springs are mutually connected to each other in a non-impact state. The distance between the central axes is shorter than the outer diameter of the coil to prevent contact.

[0007]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an impact sensor according to a first embodiment of the present invention, in a non-impact state and in an impact state. Figure 1 (
As shown in a), in this embodiment, the central axes 8 are aligned and one end is connected to the external lead-out terminals 3 and 4, and the first and second coil springs 1 and 2 do not contact each other when no impact is applied. , a shock detector 5, a movable base 6 that supports the detector 5 and has the other end of the coil spring 2 fixed thereto, and a case 7 to which the terminals 3 and 4 are fixed. These coil springs 1 and 2 have the same wire diameter, outer diameter, winding pitch, etc., are electrically conductive, and have coil central axes 8 aligned with each other. That is, the terminals 3 and 4 are arranged so as to be non-conductive when no impact is applied. Next, as shown in FIG. 1(b), when receiving an impact in the impact direction 9, the impact sensing body 5 compresses the coil springs 1 and 2. This compressive force is proportional to the magnitude of the impact, and when a certain impact or more is applied, the coil springs 1 and 2 come into contact. Therefore, the terminals 3 and 4 become conductive, and it is detected that an impact of a certain level or higher is applied. At this time, the contact between the two coil springs 1 and 2 is ensured not only at one point but over the entire circumference of the coil. Therefore, even if there is poor contact at several points due to foreign objects, terminal 3,
4 can ensure a stable conduction state.

FIG. 2 is a sectional view of an impact sensor showing a second embodiment of the present invention. As shown in FIG. 2, this embodiment has central axes 8A and 8B of two coil springs 1 and 2.
This is the case when the Similar to the first embodiment described above, this embodiment also allows the impact detection body 5 to detect an impact in the impact direction 9, and when manufactured, the central axes 8A and 8B of the coil springs 1 and 2 are aligned. Since the coil springs 1 and 2 are offset from each other, there is an advantage that the coil springs 1 and 2 can be easily assembled.

0010

Effects of the Invention As explained above, the impact sensor of the present invention has two coil springs arranged under the movable table that supports the impact detection body, so that it can function as a contact point and a conduction path, and Since the number of contact points during detection increases, detection signals can be reliably extracted and the failure rate can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an impact sensor according to a first embodiment of the present invention when there is no impact and when there is an impact.

FIG. 2 is a sectional view of an impact sensor showing a second embodiment of the present invention.

FIG. 3 is a perspective view of a conventional impact sensor.

[Explanation of symbols]

1, 2 Coil spring 3,4 Terminal 5 Shock detection body 6　　　　Moving platform 7 Case 8 Central axis 9 Shock application direction

Claims (3)

[Claims] [Claim 1] An impact detection body that receives force from an impact;
a movable base that supports the impact detector; two conductive coil springs each having one end connected to a signal terminal and the other end fixed to the movable base; the impact detector, the movable base, and the second conductive coil spring; and a case containing two coil springs, wherein the distance between the center axes of the two coil springs is shorter than the outer diameter of the coil so that the two coil springs do not come into contact with each other in a non-impact state. 2. The impact sensor according to claim 1, wherein the central axes of the two coil springs coincide. 3. The impact sensor according to claim 1, wherein the two coil springs are in contact with each other around the entire circumference when an impact is detected.