JPH0647869U - Shock sensor - Google Patents

Abstract

(57) [Summary] [Object] To provide an impact sensor having a simple structure and capable of surely detecting an impact even when an excessive impact is applied. A magnetic reed switch 13 arranged along a direction in which an impact should be detected, and a magnet movably supported along the longitudinal direction of the magnetic reed switch and biased toward one side by an elastic member 15. A moving member having 14;
The impact sensor 10 is configured by integrally attaching a weight member 16 made of a material having a specific gravity higher than that of the magnet material to the moving member.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an impact sensor using a magnetic reed switch for detecting an impact applied to a vehicle body and activating an airbag or seat belt system in the event of an accident such as an automobile.

[0002]

[Prior art]

 Conventionally, as such an impact sensor, for example, an impact sensor using a magnetic reed switch has been widely used, and is configured as shown in FIG. 2, for example. Immediately, the impact sensor 1 has a case 2 that can be attached to the vehicle body of an automobile, and extends in the case 2 along the direction in which an impact should be detected (for example, the front-back direction of the automobile). The hollow cylindrical tube part 3 provided, the magnetic reed switch 4 inserted in the left region of the tube part 3, and the slidable insertion along the longitudinal direction of the tube part 3. And an annular magnet 5 and a spring 6 for urging the magnet 5 to the right in the drawing. 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).

According to the impact sensor 1 configured as described above, when the automobile or the like to which the impact sensor 1 is attached is stopped or is traveling normally, the impact sensor 1 is Since a very high acceleration does not act, the magnet 5 is in contact with the right end of the tube portion 3 by the tension of the spring. Therefore, the magnet 5 is relatively distant from the magnetic reed switch 4 inserted in the left region of the tube portion 3. Therefore, the magnetic reed switch 4 is in the off state because its contact portion is not affected by the magnetic force.

From this state, when a shock is applied, for example, when the car suddenly stops due to an accident while the car is running, the shock sensor 1 moves to the left as shown by the arrow in the drawing. The magnet 5 receives a relatively large negative acceleration because it is abruptly stopped from the state of moving toward. Therefore, the magnet 5 receives an inertial force that is relatively leftward with respect to the tube portion 3 based on its inertial mass.

Thus, the magnet 5 moves the tube portion 3 to the left against the tension of the spring 6 so that the magnetic force of the magnet 5 acting on the contact portion of the magnetic lead switch 4 becomes a predetermined value or more. Then, the contact portion of the magnetic reed switch 4 is turned on by the magnetic force of the magnet 5. Especially when the impact is large, the magnet 5 continues to move and stops when the spring 6 reaches the fully compressed position. The kinetic energy stored in the magnet 5 by this time is once converted into deformation and vibration energy of the spring 6 and the case 2 at this point, and then converted into kinetic energy of the magnet 5 whose direction is reversed.

After that, when the acceleration of the magnet 5 becomes a predetermined value or less due to the stop of the automobile or the like, it becomes impossible to resist the tension of the spring 6, and based on the tension of the spring 6, It moves to the right of the pipe portion 3 and is 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 less than a predetermined value, the contact portion of the magnetic reed switch 4 is turned off.

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

[0008]

[Problems to be solved by the device]

 However, in the impact sensor 1 having such a configuration, when the applied impact is excessively large, the moving speed of the magnet 5 to the left region of the tube portion 3 is high, and moreover, the tube portion 3 of the magnet 5 is moved. Since the return to the right is also quick, the duration of the on-state of the magnetic reed switch 4 becomes extremely short. For this reason, the detection signal from the detection circuit is very short, and in some cases, the control device of the airbag and seat belt system cannot recognize this detection signal, and the airbag and seat belt cannot be activated. There was an occasion.

In view of the above points, the present invention has an object to provide an impact sensor having a simple structure and capable of surely detecting an impact even in the case of an excessive impact or the like.

[0010]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, in the present invention, a magnetic reed switch is arranged along a direction in which an impact should be detected, and one side is supported by an elastic member so as to be movable along the longitudinal direction of the magnetic reed switch. In a shock sensor having a moving member having a magnet biased toward, a weight member made of a material having a higher specific gravity than the material of the magnet is integrally attached to the moving member. It is said that.

In the shock sensor according to the present invention, preferably, the magnet is made of a plastic magnet, and the weight member is made of a material having a higher specific gravity than the plastic magnet.

[0012]

[Action]

 According to the above configuration, for example, when the impact sensor is mounted on the vehicle body of an automobile, when the impact sensor is suddenly stopped, the moving member causes the moving mass of the spring due to the inertial mass of the magnet and the weight member. When the spring 6 is moved against the tension and the direction of the spring 6 is reversed at the position where the spring 6 is completely compressed, and then the acceleration acting on this moving member falls below a predetermined position, the spring 6 is restored to its original position based on the tension of the spring. Returned to position.

At that time, since the weight member is integrally attached to the magnet to increase the inertial mass of the moving member, the motion energy of the spring at the time of full compression is large. This kinetic energy is once converted into deformation and vibration energy of the spring and case, and then converted into kinetic energy of the moving member again. The duration of the on state of the switch depends on the time required for reversing the speed of the moving member and the speed after reversing the direction. This depends on the time required to deliver the energy and its efficiency. If the kinetic energy at the time of full compression of the spring increases, the deformation and vibration of the material increase, and the on-time of the switch increases. If the on-time becomes long, the detection signal can be surely recognized by the control device of the airbag and seat belt system. Further, the above structure is a simple structure in which a weight member is added to the magnet of the conventional impact sensor, so that it can be manufactured at a relatively low cost.

When the magnet is made of a plastic magnet and the weight member is made of a material having a heavier specific gravity than the plastic magnet, a weight member made of a heavier material than a magnet having a relatively small inertial mass is used. By adding the, the lightness of the plastic magnet is covered, and the impact can be reliably detected.

[0015]

【Example】

 Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings. FIG. 1 shows an embodiment of an impact sensor according to the present invention. The impact sensor 10 is a case 11 that can be attached to a vehicle body of an automobile, and an impact should be detected in the case 11. Direction, for example, the longitudinal direction of the automobile, a hollow cylindrical tube portion 12 arranged so as to extend, a magnetic reed switch 13 inserted in a left region of the tube portion 12, and the tube portion. It is composed of an annular magnet 14 slidably fitted along the longitudinal direction of 12 and a spring 15 for biasing the magnet 14 to the right in the drawing.

Although the magnet 14 is configured so as to also serve as a moving member in the case of the drawing, it is a separate ring-shaped moving member that is slidably inserted along the longitudinal direction of the tube portion 12. It may be attached to the member. The two connection terminals of the magnetic reed switch 13 are connected to a detection circuit having an appropriate configuration via lead wires (not shown). The above configuration is similar to the conventional impact sensor 1 shown in FIG. 2, but in the impact sensor 10 according to the present invention, a material having a higher specific gravity than the material of the magnet 14 is used for the magnet 14. A weight member 16 composed of is integrally attached to form a moving member. In this case, the weight member 16 has an annular shape formed so as to surround the magnet 14 and is integrally attached by being fitted to the magnet 14.

The impact sensor 10 according to the present invention is configured as described above, and in use, the impact sensor 10 is attached to the body of an automobile in advance. When the automobile or the like is at a standstill or is traveling normally, the impact sensor 10 is not subjected to a very high acceleration, so that the magnet 14 together with the weight member 16 is installed in the belt 15. It is in contact with the right end of the tube portion 12 by the tension. Therefore, the magnet 14 is relatively distant from the magnetic reed switch 13 inserted in the left region of the tube portion 12. Therefore, the magnetic reed switch 13 is in the off state because its contact portion is not affected by the magnetic force.

From this state, when a shock is applied, for example, when the car suddenly stops due to an accident while the car is running, the shock sensor 10 is indicated by an arrow in the drawing. Since the magnet 14 is suddenly stopped from the state of moving to the left, the magnet 14 receives a relatively large negative acceleration. Therefore, the magnet 14 receives an inertial force relatively leftward with respect to the tube portion 12 based on the inertial mass of the magnet 14 and the weight member 16. Thus, the magnet 14 moves the tube 12 to the left against the tension of the spring 15 and stops when the spring 15 reaches the fully compressed position. At this time, when the magnetic force of the magnet 14 acting on the contact portion of the magnetic reed switch 13 becomes larger than a predetermined value, the magnetic reed switch 13 causes the contact portion to be turned on by the magnetic force of the magnet 14. To be

After that, when the acceleration of the magnet 14 becomes less than a predetermined value due to the stop of the automobile or the like, the tension of the spring 15 cannot be resisted, and the tension of the spring 15 is used as a basis. It moves to the right of the tube portion 12 and is returned to the initial position again. At this time, when the magnetic force of the magnet 14 acting on the contact portion of the magnetic reed switch 13 reaches a value equal to or less than a predetermined value, the contact portion of the magnetic reed switch 13 is turned off.

By the way, since the weight member 16 is added to the magnet 14, the kinetic energy of the moving member is increased, so that the time required for reversing the speed and the speed after the reversal are affected. The on-duration time of the receiving switch is longer than that when the weight member 16 is not added.

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. This on-state is detected by the connected detection circuit, The bag and seat belt system can be activated to ensure the safety of the vehicle occupants.

At this time, the duration of the ON state of the magnetic reed switch 13 is longer than that when the weight member 16 is not provided. Therefore, since the duration of the detection signal from the detection circuit is relatively long, the detection signal can be surely recognized by the control device of the airbag and seat belt system.

[0023]

[Effect of device]

 As described above, according to the present invention, for example, when the impact sensor is mounted on the vehicle body of an automobile, the detection signal can be reliably recognized by the control device of the airbag and seat belt system. (EN) An extremely excellent impact sensor which is simple in structure and capable of surely detecting an impact even in the case of an excessive impact. Further, the above-described structure is a simple structure in which a weight member is added to the magnet of the conventional impact sensor, so that it can be manufactured at a relatively low cost. If the magnet is made of a plastic magnet and the weight member is made of a material having a heavier specific gravity than the plastic magnet, a weight member made of a heavier material is added to the magnet having a relatively small inertial mass. By doing so, the lightness of the plastic magnet is covered, and the impact can be detected more reliably.

[Brief description of drawings]

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

FIG. 2 is a schematic sectional view showing an example of a conventional impact sensor.

[Explanation of symbols]

 10 Impact Sensor 11 Case 12 Tube 13 Magnetic Reed Switch 14 Magnet 15 Spring 16 Weight Member

Claims (2)

[Scope of utility model registration request] 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 urged toward one side by an elastic member. An impact sensor including a moving member having a magnet, wherein a weight member made of a material having a specific gravity heavier than that of the magnet is integrally attached to the moving member. , Shock sensor. 2. The magnet comprises a plastic magnet,
The impact sensor according to claim 1, wherein the weight member is made of a material having a higher specific gravity than the plastic magnet.