JPH09178768A - Shock sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor where parts such as a coil spring need not be selected even if a starting time is short, the starting time can be easily adjusted again, and at the same accurate starting time can be obtained. SOLUTION: A sensor 10 is constituted of a magnetic lead switch 13 which is arranged along a direction for detecting shock, a traveling member 14 with a magnet which is supported so that it can move along the longitudinal direction of the magnetic lead switch 13 and is energized toward one side by a coil spring 15. In this case, the traveling member 14 contacts a stopper 12a via a spacer 16 at the terminal part of one side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects an impact applied to a vehicle body in the event of an accident such as an automobile,
The present invention relates to an impact sensor using a magnetic reed switch for activating an airbag or seat belt system.

[0002]

2. Description of the Related Art Conventionally, as such an impact sensor,
For example, an impact sensor using a magnetic reed switch is often used, and is configured as shown in FIG. 4, for example. In FIG. 4, the impact sensor 1 is provided with a case 2 that can be attached to a vehicle body of an automobile, and in the case 2 so as to extend along the direction in which an impact should be detected, for example, the front-back direction of the automobile. A hollow cylindrical switch case 3, a magnetic reed switch 4 inserted in the switch case 3, and a hollow member constituting a moving member slidably fitted along the longitudinal direction of the switch case 3. It is composed of a cylindrical magnet 5 and a coil spring 6 that biases the magnet 5 to the left in the drawing.

The lead frames 4a and 4b attached to the two connection terminals of the magnetic reed switch 4 are connected to a detection circuit having an appropriate structure via lead wires (not shown). Further, in the illustrated case, the magnet 5 is provided with a small diameter portion 5a provided on the outer peripheral surface at the right end, and the small diameter portion 5a has a step portion 5b in the axial direction. As a result, the coil spring 6 urges the magnet 5 to the left in the drawing by engaging the left end of the coil spring 6 with the step portion 5b.

According to the shock sensor 1 configured as described above, when the automobile or the like to which the shock sensor 1 is attached is stopped or running normally, the shock sensor 1 Does not have too high acceleration,
The magnet 5 is in contact with a stopper 3 a provided at the left end of the switch case 3 by the tension of the coil spring 6. Therefore, the magnet 5 is relatively separated from the magnetic reed switch 4 inserted in the switch case 3. Therefore, the magnetic reed switch 4 is in the off state because its contact portion is not affected by the magnetic force of the magnet 5.

From this state, for example, while the automobile is running,
When a shock is applied, such as when the shock sensor 1 suddenly stops due to an accident or the like, the shock sensor 1 is suddenly stopped from the state of moving rightward as indicated by an arrow A in the drawing. The magnet 5 receives a relatively large negative acceleration. Therefore, the magnet 5 receives an inertial force relatively oriented in the arrow A direction with respect to the switch case 3 based on its inertial mass.

Thus, the magnet 5 moves to the right along the switch case 3 against the tension of the coil spring 6, and the magnet 5 acting on the contact portion of the magnetic reed switch 4 is moved.
The magnetic reed switch 4 is turned on by the magnetic force of the magnet 5 when the magnetic force of the magnetic reed switch becomes larger than a predetermined value.

After that, when the acceleration of the magnet 5 falls below a predetermined value when the automobile or the like is stopped, the magnet 5 is rotated by the coil spring 6
The tension of the coil spring 6 cannot be resisted, and the coil case 6 moves to the left of the switch case 3 based on the tension of the coil spring 6 to be returned to the initial position again. At this time, when the magnetic force of the magnet 5 acting on the contact portion of the magnetic reed switch 4 becomes equal to or smaller than a predetermined value, the magnetic reed switch 4
The contact part is turned off.

In this way, the magnetic reed switch 4 continues to be in the on state only during the above-mentioned on-switching and off-switching, and this on-state is detected by the connected detection circuit, and the airbag and The seat belt system is activated to ensure the safety of the occupants of the vehicle.

Here, the adjustment of the on-point of the impact sensor 1 described above is performed as follows. That is, at the time of assembly, first, the coil spring 6 and the tubular magnet 5 are fitted to the switch case 3 from the left side in FIG.
Attach a to the left end of the switch case 3. FIG.
As shown in, the reed switch assembly 7 in which the lead frames 4a and 4b are attached to the reed switch 4,
Insert into switch case 3. In this state, the reed switch assembly 7 is moved to the left and right in the switch case 3 for adjustment to turn on the reed switch 4. Based on this ON position, the reed switch 4
The reed switch 4 is moved and adjusted to the proper position by determining the proper position in the switch case 3. After that, the lead frames 4a and 4b are spot-welded to the terminal frame of the switch case 3 to adjust the on-point of the impact sensor 1.

The following method is also available as another adjustment method.
That is, at the time of assembly, first the reed switch assembly 7
Is inserted in the switch case 3, and the lead frame 4a,
4b is spot-welded to the terminal frame of the switch case 3. Next, the coil spring 6 and the magnet 5 are fitted onto the switch case 3 from the left side in FIG. In this state, the reed switch 4 is turned on by moving the magnet 5. An appropriate initial position of the magnet 5 is obtained based on this ON position. After that, the stopper 3a whose thickness is selected so that the magnet 5 is in the proper initial position is attached and fixed.

[0011]

However, due to the demand for improving the performance of airbags and the like, there has been a demand for a more accurate impact sensor, that is, a variation in the on-time is reduced. Further, when the impact sensor is used for the side airbag, a rise time from the impact being applied until the reed switch is turned on is required to be shorter. Therefore, in the above-described conventional impact sensor 1, since the standard of the coil spring 6 needs to be more rigorous, the re-sorting operation of the coil spring 6 is required and the yield of the coil spring 6 is reduced. There was a problem that the cost would be high.

Further, there is a case where the rise time is inspected by actually applying an impact to the impact sensor assembly which is adjusted by the above-mentioned ON adjustment method and before being incorporated in the case 2. Then, based on this result, the reed switch 4 or the magnet 5
When re-adjusting the position of, the spot welding part of the reed switch 4 is removed, the set position of the reed switch 4 is adjusted, and then spot welding is performed again, or the stopper 3a is removed and a new stopper whose thickness is re-selected It is necessary to attach and fix 3a. Therefore, it takes a lot of time and effort to inspect the impact sensor. Further, the rising time largely depends on the moving distance of the magnet 5, and when the rising time is short, it strongly depends on the moving distance of the magnet 5.

In view of the above points, the present invention facilitates readjustment of the rise time without selecting parts such as coil springs even when the rise time is short, and also provides a highly accurate rise time. It is an object to provide an impact sensor that is time consuming.

[0014]

In order to achieve the above object, in the present invention, a magnetic reed switch arranged along a direction in which an impact should be detected, and a longitudinal direction of the magnetic reed switch. And a moving member provided with a magnet urged toward one side by spring means, the moving member having a spacer at one end thereof. It is configured to abut the stopper.

The shock sensor according to the invention is preferably
The spacer has an appropriate dimension in the longitudinal direction.

The shock sensor according to the invention is preferably
The spacer is a C-type metal wire having a spring property or a C-type washer.

The shock sensor according to the invention is preferably
The spacer is made of a magnetic material and is attracted to one end of the moving member by a magnet.

According to the above construction, for example, when the present impact sensor is mounted on the body of an automobile or the like, when the automobile suddenly stops, the moving member is moved by the inertial mass against the tension of the coil spring. After that, when the acceleration acting on this moving member becomes equal to or less than a predetermined value, it is returned to the original position based on the tension of the spring.

Here, the one end of the moving member is normally in contact with the stopper via the spacer by the tension of the spring. Therefore, the position of the moving member with respect to the reed switch can be adjusted by appropriately adjusting the dimension of the spacer in the longitudinal direction. As a result, the moving distance of the moving member to the on position of the reed switch when an impact is received can be adjusted appropriately, and the on point can be easily changed by replacing the spacer with an appropriate length dimension. Adjustment is possible. Thus, it is possible to easily adjust the rising time with high accuracy even if the rising time is short, by adjusting the moving distance of the moving member by exchanging and adjusting the spacers appropriately without the need to strictly select each member. Can be set to.

When the spacer is a metal wire having a C-type spring property or a C-type washer, the spacer itself can be easily formed at low cost.

When the spacer is made of a magnetic material and is attracted to one end of the moving member by the magnet, the spacer moves together with the moving member, so that the moving member receives an impact. When receiving and moving, the spacer does not hinder the smooth movement of the moving member.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on an example shown in the drawings. FIG. 1 shows an embodiment of a shock sensor according to the present invention. Impact sensor 10
Is a case 11 attached to the body of an automobile, etc.
And a hollow cylindrical switch case 12 arranged so as to extend along the direction in which the impact should be detected (for example, the front-back direction of the automobile), and the right side inside the switch case 12. The magnetic reed switch 13 inserted in the area, the cylindrical magnet 14 constituting the moving member slidably inserted along the longitudinal direction of the switch case 12, and the magnet 14 are shown on the left side in the drawing. It is composed of a spring member for urging the coil spring, for example, a coil spring 15.

Lead frames 13a and 13b attached to the two connection terminals of the magnetic reed switch 13 described above.
Is connected to a detection circuit having an appropriate configuration via a lead wire (not shown). Further, in the illustrated case, the magnet 14 includes a small diameter portion 14a provided on the outer peripheral surface at the right end, and the small diameter portion 14a has a step portion 14b in the axial direction. As a result, the left end of the coil spring 15 is engaged with the stepped portion 14b to urge the magnet 14 to the left in the drawing.

The above construction is similar to that of the conventional impact sensor 1 shown in FIG. 4, but in the embodiment of the present invention, one end (left end in the drawing) of the magnet 14 has the spacer 16 at its one end. It is adapted to come into contact with the stopper 12a via.

Here, the spacer 16 is constructed so as to have an appropriate dimension, that is, a thickness, in the longitudinal direction, and is made of, for example, phosphor bronze having a C-shaped spring property as shown in FIG. 2 or stainless steel. Although it is formed of a metal wire or a C-type metal washer as shown in FIG. 3, it may be a non-magnetic material such as a resin washer. In the case of the C-type metal wire, the spacer 16 can be easily obtained at a low cost by using a commercially available metal wire having various wire diameters. Further, in the case of the C-type washer, the spacer 16 can be easily and inexpensively formed from a commercially available plate having various thicknesses, for example, by punching.

Further, when the spacer 16 is made of a magnetic material, the spacer 16 is attracted by the magnet 14 so that the spacer 16 is attracted and held by the magnet 14 (that is, the moving member) and moves integrally. Therefore, when the magnet 14 moves, the spacer 16 moves freely and
There is no obstacle to the smooth movement of. The outer diameter of the spacer 16 is smaller than the outer diameter of the magnet 14,
Further, its inner diameter is selected to be larger than the outer diameter of the switch case 12.

The impact sensor 10 according to the present invention is configured as described above, and is used when the automobile or the like equipped with the impact sensor 10 is stationary or is traveling normally. Since a very high acceleration does not act, the magnet 14 is in contact with the stopper 12a provided at the left end of the switch case 12 via the spacer 16 by the tension of the coil spring 15.
Therefore, the magnet 14 is relatively distant from the magnetic reed switch 13 in the switch case 12. For this reason,
The magnetic reed switch 13 is in the off state because its contact portion is not affected by the magnetic force.

From this state, for example, while the automobile is running,
When a car suddenly stops due to an accident, etc.,
When an impact is applied, the impact sensor 10 is abruptly stopped from the state where the entire impact sensor 10 is moving to the right as shown by the arrow A in the drawing, so that the magnet 14 is comparatively moved. It receives a large negative acceleration. Therefore, the magnet 14 receives an inertial force relatively to the right with respect to the switch case 12 based on the inertial mass of the magnet 14.

As a result, the magnet 14 moves the switch case 12 to the right against the tension of the coil spring 15 and acts on the contact portion of the magnetic reed switch 13.
When the magnetic force of No. 4 exceeds a predetermined value, the contact portion of the magnetic reed switch 13 is turned on by the magnetic force of the magnet 14.

After that, when the automobile etc. stops,
When the acceleration of the magnet 14 becomes less than a predetermined value, the tension of the coil spring 15 cannot be resisted, and the tension of the coil spring 15 causes the switch case 12 to move to the left side, and then again. Returned to the position.
At this time, when the magnetic force of the magnet 14 acting on the contact portion of the magnetic reed switch 13 becomes equal to or less than a predetermined value, the contact portion of the magnetic reed switch 13 is turned off.

In this way, the magnetic reed switch 13 continues to be in the on state only during the above-mentioned on-switching and off-switching, and this on-state is detected by the connected detection circuit, and the airbag and Although the seat belt system is activated to ensure the safety of the occupant of the vehicle, in the present embodiment, the spacer 16 is provided between the one end of the magnet 14 and the stopper 12a. Therefore, when the magnet 14, that is, the moving member is moved, the moving distance to the position where the reed switch 13 is turned on by the magnet 14 can be appropriately adjusted by the spacer 16. As a result, other components such as the coil spring 1
The desired on-point position can be adjusted without performing the re-sorting of No. 5, and a highly accurate rise time is set even if the rise time is relatively short.

Here, the adjustment of the ON point position in the impact sensor 10 is performed as follows. That is, first, with respect to the switch case 12, the coil spring 15 and the magnet 1
4 is fitted to fix the stopper 12a, and the lead frames 13a, 13
The reed switch assembly attached with b is inserted into the switch case 12 and spot-welded to the terminal frame of the switch case 12. In this state, a shock is externally applied as a test. Based on the result, the proper moving distance of the magnet 14 from the initial position of the magnet 14 to the position where the reed switch 13 is turned on is obtained, and the thickness of the spacer 16 is selected so as to finely adjust the predetermined moving distance. To be done. Then, the spacer 16 having this thickness is inserted between the magnet 14 and the stopper 12a, so that the ON point is adjusted.

Thus, even when the rise time is short, the spacers 16 having an appropriate thickness are inserted between the magnet 14 and the stopper 12a without re-sorting each component, for example, the coil spring 15. Since the on-point adjustment can be performed by appropriately adjusting the moving distance of the magnet 14 to the on-point position, a highly accurate rise time can be set and readjustment work becomes easy.

Incidentally, in the case of adjusting the on-point for shortening the moving distance of the magnet 14 which is the moving member, the on-point can be adjusted by inserting the spacer 16 having an appropriate thickness. In the case of adjusting the ON point for increasing the distance, a spacer 16 having a predetermined thickness is temporarily inserted in advance, and an impact test is performed. Then, the spacer 16 having a proper thickness is used. By exchanging or removing it, accurate on-point adjustment can be performed. Further, when the spacer 16 is a C-type washer, it is possible to make it have an appropriate thickness by inserting a plurality of spacers.

In the above embodiment, the magnet 14 is constructed so as to also serve as a moving member, but it is a separate ring-shaped moving member which is slidably inserted along the longitudinal direction of the switch case 12. It may be attached to the member.

[0036]

As described above, according to the present invention,
A spacer is interposed between the moving member and the stopper, and the position of the moving member with respect to the reed switch can be adjusted by appropriately adjusting the longitudinal dimension of the spacer or the number of spacers. This allows
The moving distance of the moving member to the ON position of the reed switch when an impact is received can be adjusted appropriately, and the ON point can be easily adjusted by replacing it with a spacer having an appropriate length dimension. Becomes Therefore, the moving distance of the moving member can be adjusted simply by exchanging the spacers without having to select each member, and even if the rising time is short, the highly accurate rising time can be easily set. In addition, readjustment work becomes easy.

Thus, according to the present invention, there is provided an extremely excellent impact sensor capable of obtaining a highly accurate rise time without having to select parts such as coil springs even when the rise time is short. Provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of an impact sensor according to the present invention.

2 is a schematic front view showing a first example of forming a spacer used in the impact sensor of FIG. 1. FIG.

3 is a schematic front view showing a second example of forming a spacer used in the impact sensor of FIG. 1. FIG.

FIG. 4 is a schematic cross-sectional view showing an example of a conventional impact sensor.

5 is a schematic side view of a reed switch assembly in the shock sensor of FIG.

[Explanation of symbols]

 10 Impact Sensor 11 Case 12 Switch Case 12a Stopper 13 Magnetic Reed Switch 13a, 13b Lead Frame 14 Magnet 15 Coil Spring 16 Spacer

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yuji Tsuda 1-25-252 Komaoka, Tsurumi-ku, Yokohama-shi, Kanagawa Japan Aleph Co., Ltd. (72) Inventor Hirohiro Iwaki 1-28, Komaoka, Tsurumi-ku, Yokohama-shi, Kanagawa No. 52 within Nippon Aleph Co., Ltd.

Claims (5)

[Claims] 1. A magnetic reed switch arranged along a direction in which an impact should be detected, and a magnetic reed switch movably supported along the longitudinal direction of the magnetic reed switch and biased toward one side by a spring. A shock sensor including a moving member having a magnet, wherein the moving member comes into contact with a stopper via a spacer at one end thereof. 2. The shock sensor according to claim 1, wherein the spacer has an appropriate dimension in a longitudinal direction. 3. The impact sensor according to claim 1, wherein the spacer is a C-shaped metal wire having a spring property. 4. The impact sensor according to claim 1, wherein the spacer is a C-type washer. 5. The shock sensor according to claim 1, wherein the spacer is made of a magnetic material and is attracted to one end of the moving member by a magnet.