JP2628515B2 - Collision sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collision sensor suitable for detecting a collision used in a trigger system of an air bag or the like as an occupant protection device for a vehicle, and more particularly to a collision sensor (bias force) generated by a magnet. The present invention relates to a moving ball mass that detects a collision.

[0002]

2. Description of the Related Art Conventionally, as this type of collision sensor, there is known a collision sensor disclosed in Japanese Utility Model Laid-Open Publication No. 3-92339. This collision sensor will be described with reference to FIGS. 5 is a sectional view of a conventional collision sensor, FIG. 6 is a sectional view taken along line AA of FIG. 5, and FIG. 7 is a sectional view taken along line BB of FIG.

In FIGS. 5 and 6, a collision sensor detects a ball mass 2 which moves upon sensing a collision.
And a cylinder 7 for holding the ball mass 2 and the cylinder 7 in a front space 3 around the cylinder 7.
0 and the body forming the rear space 31 (the main body 1 and the holding plate 5).
And a contact plate 6), a magnet 3 held by the body 1 of the body and attracting the ball mass 2 toward the rear space 31, and a pair of contacts 15 located in the front space 30 and forming the contact 4 together with the ball mass 2. , 15 '.

The ball mass 2 is made of, for example, a conductive material such as a steel ball whose surface is plated with gold. A cylindrical cylinder 7 is fitted into the body 1, and a predetermined gap is formed between the cylinder 7 and the ball mass 2 so as to impart a predetermined resistance to the movement of the ball mass 2 by an air flow. The seal 7a is for preventing a bypass airflow from occurring so that the airflow in the gap between the cylinder 7 and the ball mass 2 becomes a resistance. In a normal state, the ball mass 2 is located on the hemispherical end surface of the rear space 31 by the attraction of the magnetic body 3.

[0005] The holding plate 5 of the body is made of resin similarly to the main body 1, is fitted into the fitting portion 8 of the main body 1, and is integrated with the main body 1 by bending the tip 1 a of the main body 1. The seal 9 isolates essential parts of the sensor such as the ball mass 2 and the contact 4 from the outside air to ensure weather resistance. The spherical end surface 13 of the front space 30 is provided inside the holding plate 5.
And a spigot portion 25 for attaching the contact plate 6 described later.

The contact 4 is formed by arranging a pair of gold-plated cantilevered elastic contacts 15 and 15 ′ vertically and symmetrically with respect to the center E. The bottom 15a of the contact 15 is fitted into the small projection 5a of the holding plate 5, and the small projection 5a is fixed by pressing with a heat bar. Also, the take-out piece of the contact 15 protrudes outside from the holding plate 5 and is hardened with resin or the like.
2 is connected.

As shown in FIG. 7, the abutment plate 6 of the body has a hole 19 at its center and a parallel surface 20 at the top and bottom surfaces thereof. The inclined portions of the contacts 15 and 15 ′ abut on the corners of the parallel surface 20 to keep the inclination angle constant. Projections 21 and 21 ′ are provided on the outer peripheral portion of the contact plate 6 so as to be vertically symmetrical. It is decided. As shown in FIG. 6, fitting portions 14 are provided on the right and left sides of the outer peripheral portion of the contact plate 6.
The holding plate 5 is provided with a spigot portion 25.
Then, as shown in FIG.
And a slit 24 are provided, so that the fitting portion 14 having a slightly larger diameter than the spigot portion 25 can be fit into the spigot portion 25. Therefore, the attachment to the holding plate 5 is completed only by pushing the fitting portion 14 of the contact plate 6 into the spigot portion 25, and the position of the contact plate 6 with respect to the center E of the holding plate 5 is determined.

Next, the operation of the collision sensor having such a structure will be described with reference to FIG. Normally ball mass 2 is magnet 3
And is located on the hemispherical end surface of the rear space 31.
When an impact occurs in the direction of the arrow, the ball mass 2 overcomes the attractive force of the magnet 3 and moves forward in the cylinder 7 while receiving the damping effect of the airflow flowing through the gap with the cylinder 7.
It contacts the contacts 15, 15 '. As shown in FIG. 6, a voltage is applied to the contacts 15 and 15 'by a battery 16 or the like, and the ball mass 2 and the contact 1
The contact 4 closes the contact 4 due to the contact between 5, 5 ', and the electric current flows to activate the electric detonator 17 or the like of the airbag device. The sensitivity of the collision sensor 1 having such a structure to a collision is determined by the magnetic force of the magnet 2, the gap between the ball mass 3 and the cylinder 4, and the distance between the ball mass 2 and the contact 6.

The current supply time for obtaining the necessary electric energy for operating the airbag apparatus is determined by the ball mass 2 that has moved upon sensing the collision and the contact 1.
5 and 15 ', the contact 4 is closed, the contact 5 is bent and the contact 5 is advanced to some extent in the direction of extension of the center axis of the cylinder 7 in the front space 30, and then returned to the cylinder 7 again by the attractive force of the magnet 3, Ball mass 2 is contact 1
5, 15 'and the time until the contact 4 opens.

[0010]

When a particularly strong impact acts on the collision sensor having the above-described structure, the ball mass 2 hits the spherical end face 13 of the front space 30 in the direction in which the center axis of the cylinder 7 extends. Since it contacts and rebounds and returns to the cylinder 7 instantaneously, there is a problem in that the contact closing time is shortened, and it may not be possible to obtain electric energy required for operating the airbag device. Therefore, in order to extend the contact closing time, several projections are provided on the circumferential side surface 7a of the cylinder 7 of the front space 30 so that the ball mass 2 is brought into contact with the projection, and By providing the kinetic component, the kinetic energy component of the ball mass 2 in the direction of the central axis of the cylinder 7 is reduced, and the ball mass 2
The time from contact with 15 'to separation is the ball mass 2
There has been proposed a collision sensor in which the movement speed in the direction of the center axis is increased by reducing the movement speed (see Japanese Patent Application Laid-Open No. 57-813). However, if a strong impact is applied,
There is a limit to the movement speed that can be reduced by the protrusion on the circumferential side surface of the cylinder 7 of the front space 30, and there is a problem that such an effect of extending the contact closing time cannot be expected.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to operate an airbag apparatus particularly when a strong impact is applied. An object of the present invention is to provide a collision sensor that can reliably secure a contact closing time required for obtaining electric energy.

[0012]

In order to solve the above-mentioned object, a collision sensor according to the present invention comprises a ball mass which moves upon sensing a collision, a cylinder which restricts the movement of the ball mass in one direction, A collision sensor comprising a body forming a front space and a rear space in the front, a magnet held by the body to attract the ball mass toward the rear space, and a pair of contacts located in the front space and forming a contact with the ball mass. Wherein the front space has a space which is larger than the cylinder inner diameter and accommodates at least half of the ball mass, and rebounds after the ball mass, which has moved upon sensing a collision, comes into contact with an end surface of the front space located on the extension of the cylinder center axis. A projection for making the direction different from the cylinder center axis direction is provided on the end face of the front space.

[0013]

When the front space has a space which is larger than the cylinder inner diameter and accommodates more than half of the ball mass, the ball mass has a space to move freely in the front space,
If a projection is provided on the end face on the extension of the center axis of the cylinder in the front space, the ball mass that has moved particularly by sensing a strong impact rebounds in a direction different from the center axis direction of the cylinder after contacting the end face, It is not possible to return to the cylinder instantly, and the contact between the inner surface of the front space and the end of the cylinder on the front space side is repeated many times in the front space with the contacts closed, so that the time required for the ball mass to return to the cylinder is delayed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the collision sensor of the present invention, and FIG. 2 is a sectional view taken along line XX of FIG. FIGS. 1 and 2 are different from FIGS. 5 and 6 described in the related art in the shapes of the contact plate 33 and the holding plate 3 constituting the body, and are otherwise the same as FIGS. 5 and 6. It is.

1 and 2, an inner diameter D of the contact plate 33 is shown.
1 is larger than the inner diameter D2 and the outer diameter D3 of the cylinder 7, and the upper and lower parallel surfaces 3 of the contact plate 33 for preventing the cylinder 7 from coming off.
4 are smaller than the outer diameter D3 of the cylinder 7. Thereby, most of the end face 7a of the cylinder 7 is exposed. Further, the inner diameter D1 of the contact plate 33 is
If it is larger than 2 and close to the outer diameter D3 but smaller than the outer diameter D3, a substantial portion of the end face 7a is exposed. Thus, the end surface 7a of the cylinder 7 is exposed, and a front space 34 defined by the parallel surface 35, the peripheral surface 36, and the end surface 38 of the holding plate 37 described below is formed. Further, the width W of the contact plate 33 is a width that accommodates at least half of the ball mass 2,
Preferably, the width W is such that the entire ball mass 2 can be accommodated as shown. Therefore, as shown by the two-dot chain line, the ball mass 2 that has come out of the cylinder 7 has a space that can freely move up, down, left, right, front and back in the front space 34.

The end face 38 of the holding plate 37 is flat,
As shown in FIG. 2, the hemispherical surface is eccentric by a distance M from the center E of the end face 38 on the central axis extension of the cylinder 7 and further rotated clockwise with respect to the vertical axis of the parallel surface 34. The projection 39 is provided integrally with the holding plate 37.
Since the holding plate 37 is a resin molded product, such a protrusion 39 can be easily added by slightly changing the mold.

Next, the operation of the collision sensor 21 having the above configuration will be described with reference to FIG. The problem occurs when the ball mass 2 receives a particularly strong impact and rebounds by abutting against the end face 38 on the extension of the center axis of the cylinder 7. This case will be described. When a particularly strong shock occurs, FIG.
As shown in (a), the ball mass 2 overcomes the attractive force of the magnet, enters the front space 34 from the cylinder 7, contacts the contact, closes the contact, and advances substantially linearly to hit the projection 37. Touch At this time, since the position of the projection 39 is eccentric from the center E of the end face 38, the direction in which the ball mass 2 rebounds is the a direction inclined with respect to the center axis direction of the cylinder 7. The inclination at this time is the protrusion 39 and the ball mass 2
When the inclination angle formed by the tangent line contacting with the end surface 38 of the front space 34 is α, the ball mass 2 has an angle 2 with respect to the straight traveling direction.
It becomes the direction inclined by α. Further, it rebounds in the direction b connecting the projection 39 and the center E of the end face 38, that is, in the parallel plane 35.

Then, as shown in FIG. 3B, the ball mass 2 rebounds in the direction c toward the end face 7a of the cylinder 7 and in the direction d toward the peripheral surface 36. Then, as shown in FIG. 3C, the ball mass 2 rebounds from the end face 7a of the cylinder 7 in the e direction returning to the front space and in the f direction toward the parallel plane 35. Then, as shown in FIG. 3D, the ball mass 2 rebounds in the g direction toward the front space end surface 38 and in the h direction toward the peripheral surface 36. As described above, the ball mass 2 makes complicated movements in the axial plane and the radial plane of the front space 34, and its trajectory becomes longer and kinetic energy is attenuated. When the kinetic energy of the ball mass 2 finally falls below a certain level, the cylinder 7 is pulled by the attraction force of the magnet.
Pulled back in. As a result, the movement trajectory of the ball mass 2 becomes longer, so that the return time of the ball mass 2 becomes longer,
The contact time with the contact becomes longer.

In the above-described embodiment, the case where the contact plate 33 has the parallel surface 35 has been described. However, even if the contact plate 33 has only the circumferential surface having no parallel portion, the impact force in an actual collision can be reduced. The motion component of the ball mass 2 is affected not only in the central axis direction of the cylinder 7 but also in a direction perpendicular to the central axis direction of the cylinder 7, that is, in the circumferential direction, because the motion component is affected not only in the traveling direction of the car but also in the oblique direction. There is. Therefore, the movement of the volumous mass 2 necessarily causes the ball mass 2 to move complicatedly in the axial plane and the radial plane of the front space 34. Although the projection 39 is a hemispherical projection, various other shapes such as a cone, a triangular pyramid, a truncated cone, and a truncated pyramid can be employed. In addition, any protrusion that makes the rebound direction of the ball mass different from the direction of the center axis of the cylinder may be used.
A tapered projection located at the center E of the end face 38 as shown in FIG. 4 may be used.

A parallel surface 35 is provided as an object for imparting a motion component in the circumferential direction of the cylinder to the motion of the ball mass after coming into contact with the end surface of the front space in the front space and extending on the center axis of the cylinder. Although it is used, in order to more positively impart the circumferential motion component of the cylinder to the movement of the ball mass, the shape of the front space should be not a cylinder but a front space with an asymmetric cross section Can also.

[0021]

According to the collision sensor of the present invention, the front space is made larger than the inner diameter of the cylinder to accommodate at least half of the ball mass, so that the ball mass has a sufficient space to move freely in the front space. By providing a projection on the end surface of the front space on the extension of the center axis of the cylinder, the ball mass, which has moved upon sensing a strong impact, rebounds in a direction different from the center axis direction of the cylinder after contacting the end surface. To prevent the ball mass from returning to the cylinder instantaneously, while keeping the contacts closed, repeated contact with the inner surface of the front space and the end surface of the cylinder to lengthen the movement trajectory and delay the time for the ball mass to return to the cylinder. Therefore, in the case of a particularly strong impact, it is possible to reliably secure the contact closing time required for obtaining electric energy for operating the airbag device.

[Brief description of the drawings]

FIG. 1 is a sectional view of a collision sensor according to the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is an operation diagram of the collision sensor of the present invention.

FIG. 4 is a sectional view of another collision sensor of the present invention.

FIG. 5 is a sectional view of a conventional collision sensor.

6 is a sectional view taken along line AA of FIG.

FIG. 7 is a sectional view taken along line BB of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body (Body) 2 Ball mass 3 Magnet 7 Cylinder 15, 15 'Contact 34 Front space 36 Contact plate (Body) 37 Holding plate (Body) 38 End face 39 Projection

Continued on the front page (72) Inventor Atsushi Taniguchi 1764-1 Munihara, Kamiinagi, Chiyoda-mura, Niigata-gun, Ibaraki Prefecture Inside Sensor Technology Co., Ltd. -1 Sensor Technology Co., Ltd. (72) Inventor Hiroshi Moriyama 1764-1 Murahara, Kamiinagi, Chiyoda-mura, Niigata-gun, Ibaraki Prefecture Sensor Technology Co., Ltd. Inayoshi character Mukohara 1764-1 Sensor Technology Co., Ltd. (72) Inventor Koji Minekubo Chiyoda-mura, Ibaraki Pref. JP-A-228342 (JP, A) JP-A-62-198765 (JP, A) JP-A-62-198764 (JP, A) JP-A-62-198763 (JP, A) JP-A-62-198762 (JP, A) JP-A-4-218226 (JP, A JP-A-57-813 (JP, A) JP-A-53-23083 (JP, A) JP-A-3-92339 (JP, U) JP-A-4-126170 (JP, U) JP-A-5-213 40880 (JP, U) Japanese Utility Model 5-45568 (JP, U) Japanese Utility Model 5-92935 (JP, U)

Claims (1)

(57) [Claims] A ball mass that moves upon sensing a collision;
A cylinder that restricts the movement of the ball mass in one direction, a body that forms a front space and a rear space before and after the cylinder, a magnet that is held by the body and that attracts the ball mass to the rear space, and that is located in the front space. In a collision sensor comprising a pair of contacts forming a contact point together with a ball mass, the front space has a space larger than the cylinder inner diameter and accommodating at least half of the ball mass, and the ball mass which has moved upon sensing a collision is a cylinder. A collision sensor characterized in that a projection is provided on the front space end surface for making the rebound direction after contacting the front space end surface on the extension of the central axis different from the cylinder center axis direction.