JPH0656771U - Shock sensor - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide an impact sensor having a simple structure, capable of reliably detecting an impact even when an excessive impact is applied, and preventing variations in the on-time. 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 a coil spring 15. A moving member provided with a coil spring, and a coil spring is fitted into a small diameter portion 14a provided on an outer surface of the moving member, and an end surface 14b of the small diameter portion.
The impact sensor 10 is configured so as to urge the moving member by abutting against.

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 pipe portion 3 arranged, the magnetic reed switch 4 inserted in the left region of the pipe portion 3 in the drawing, and slidable along the longitudinal direction of the pipe portion 3. It is composed of a ring-shaped magnet 5 fitted and inserted, and a coil panel 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). The coil spring 6 is fitted on the outer periphery of the tube portion 3 and is in contact with the end surface 5a of the magnet 5 to bias the magnet 5 to the right.

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 stopper 3a provided at the right end of the tube portion 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 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 is suddenly stopped due to an accident while the car is traveling, the car moves to the left as shown by the arrow in the drawing. The magnet 5 receives a relatively large negative acceleration because it is suddenly stopped. Therefore, the magnet 5 receives an inertial force relatively leftward with respect to the tube portion 3 based on its inertial mass.

In this way, the magnet 5 moves the tube portion 3 to the left against the tension of the coil spring 6 so that the magnetic force of the magnet 5 acting on the contact portion of the magnetic reed switch 4 becomes a predetermined value or more. When this happens, the magnetic reed switch 4 has its contact portion 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 coil spring 6 reaches the fully compressed position. At this point, the kinetic energy stored in the magnet 5 is once converted into deformation energy or vibration energy of the coil spring 6 and the case 2, and then converted into kinetic energy of the magnet 5 whose direction is reversed. Become.

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, the tension of the coil spring 6 cannot be resisted, and the tension of the coil spring 6 is used as a basis. , Is moved to the right of the pipe portion 3 and 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 contact portion of the magnetic reed switch 4 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. As a result, the airbag and seat belt system can be activated to ensure the safety of the vehicle occupants.

[0009]

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, Moreover, since the magnet 5 returns to the right of the tube portion 3 to the right, 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.

Further, when the coil spring 6 is in a completely compressed state, when it is further compressed, it tends to deform in the radial direction. However, the coil spring 6 has a play against the side surfaces of the tube portion 3 and the magnet 5. Since it is comparatively small and deformation in the radial direction is suppressed, deformation in the radial direction occurs only when the compression is fairly strong, and variations in the on-time occur.

In view of the above points, the present invention provides an impact sensor that has a simple structure, can detect an impact reliably even when an excessive impact is applied, and prevents the on-time from varying. It is intended to be provided.

[0012]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, in the present invention, 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 supported by a coil spring on one side In a shock sensor including a moving member having a magnet urged toward, the coil spring is fitted to a small diameter portion provided on the outer side surface of the moving member and abutted on the end surface of the small diameter portion. It is characterized in that the moving member is biased by the.

[0013]

[Action]

 According to the above configuration, for example, when the impact sensor is mounted on the body of an automobile, when the impact sensor is suddenly stopped, the moving member resists the tension of the coil spring by the inertial mass of the magnet. When the coil spring is moved and the direction is reversed at the position where the coil spring is completely compressed, and then the acceleration acting on this moving member becomes a predetermined value or less, it is returned to the original position based on the tension of the coil spring.

Here, the duration of the ON state of the switch depends on the time required for the direction reversal of the speed of the moving member and the speed after the direction reversal. This depends on the time and efficiency required to deliver the energy. According to the present invention, since the coil spring is engaged with the small diameter portion provided on the outer peripheral surface of the magnet, the radial play of the coil spring becomes relatively large, and thus the coil spring is completely compressed. After that, it can be easily deformed in the radial direction.

By thus setting the radial play of the coil spring to be large, the deformation and vibration of the material can be increased, and the ON time of the switch can be lengthened. If the on-time becomes long, the detection signal can be surely recognized by the control device of the airbag and seat belt system. Furthermore, since the above-mentioned configuration is a simple configuration in which the shape of the magnet or the moving member is changed with respect to the conventional impact sensor, it can be manufactured at a relatively low cost.

[0016]

【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 in the longitudinal direction 12 and a coil spring 15 for urging 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-mentioned configuration is similar to the conventional impact sensor 1 shown in FIG. 2, but in the impact sensor 10 according to the present invention, the magnet 14 is provided on the outer peripheral surface at the left end thereof. It has a small diameter portion 14a. The coil spring 15 is fitted in the small diameter portion 14a, and one end of the coil spring 15 is in contact with the end surface 14b of the small diameter portion 14a. As a result, the magnet 14 can be biased to the right.

The shock sensor 10 according to the present invention is configured as described above, and in use, the shock sensor 10 is attached to the vehicle body of an automobile in advance. Then, when the automobile or the like is at a standstill or is traveling normally, a very high acceleration does not act on the impact sensor 10, so that the magnet 14 is caused by the tension of the coil spring 15 to cause the tube portion 12 to move. Is in contact with a stopper 12a provided at the right end of the. 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 is suddenly stopped 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. In this way, the magnet 14 moves the tube portion 12 leftward against the tension of the coil spring 15, reaches a position where the coil spring 15 is completely compressed in the moving direction, and further the coil spring 15 is radially deformed. By doing so, it can be compressed in the tilt direction and stops. In this case, since the play of the coil spring 15 with respect to the tube portion 12 and the magnet 14 is relatively large, the coil spring 15 can be easily deformed in the radial direction.

At this time, when the magnetic force of the magnet 14 acting on the contact portion of the magnetic reed switch 13 reaches a predetermined value or more, the magnetic reed switch 13 is turned on by the magnetic force of the magnet 14 at the contact portion. It can be changed. After that, when the acceleration of the magnet 14 becomes less than or equal to a predetermined value due to the stop of the automobile or the like, the tension of the coil spring 15 cannot be resisted, and the tension of the coil spring 15 causes the tube portion 12 to move. It moves to the right and returns 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 coil spring 15 has a relatively large play with respect to the tube portion 12 and the magnet, the kinetic energy of the magnet 14 can be converted into longitudinal compression, radial deformation, and vibration of the coil spring 15. Therefore, the time required at the time of reversing the speed and the on-duration time of the switch affected by the speed after reversing will become longer in comparison. In this way, the magnetic reed switch 13 continues to be in the on state only during the above-described on-switching and off-switching. This on-state is detected by the connected detection circuit, and the airbag or seat is detected. The 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 becomes longer than that of the conventional impact sensor 1 shown in FIG. Therefore, since the duration of the detection signal from the detection circuit is relatively long, the detection signal can be reliably recognized by the control device of the airbag and seat belt system.

The length L1 in the longitudinal direction of the small-diameter portion 14a of the magnet 14 is preferably selected to be shorter than the completely compressed length L2 of the coil panel 15. As a result, when the magnet 14 moves to the left while receiving a shock and compressing the coil spring 15, even if the coil spring 15 is in a completely compressed state, the left end of the magnet 14 is located on the side wall of the case 11. The impact is not received by the coil spring 15, and all the shock is received by the coil spring 15. Therefore, all the kinetic energy of the magnet described above is converted into compression, radial deformation and vibration of the coil spring 15, and can be used as energy for reversing the magnet 14.

[0025]

[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, when the automobile suddenly stops, the moving member resists the tension of the coil spring due to the inertial amount of the magnet. Then, the coil spring is reversed in direction at the position where the coil spring is completely compressed, and when the acceleration acting on this moving member becomes less than a predetermined value, the coil spring is returned to its original position based on the tension of the coil spring. At that time, since the coil spring is engaged with the small-diameter portion provided on the outer peripheral surface of the magnet, the radial play of the coil spring is relatively large, and therefore, the coil spring is compressed after being completely compressed. It can be easily deformed in the direction. The kinetic energy of the coil spring at the time of complete compression is once converted into deformation energy and vibration energy of the coil spring and the case, and then converted into kinetic energy of the moving member again. Here, 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 and efficiency required to deliver the energy. According to the present invention, the deformation and vibration of the material at the time of the complete compression of the coil spring becomes large, and the on-time of the switch becomes long. In this way, by prolonging the on-time, the detection signal can be reliably recognized by the control device of the system of the airbag and seat belt. Further, since the above-mentioned configuration is a simple configuration in which the shape of the magnet or the moving member is changed with respect to the conventional impact sensor, it can be manufactured at a relatively low cost. Thus, according to the present invention, there is provided an extremely excellent impact sensor having a simple structure, capable of accurately detecting an impact even in the case of excessive impact, and preventing variation in the on-time. It

[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 Section 12a Stopper 13 Magnetic Reed Switch 14 Magnet 14a Small Diameter Section 14b End Face 15 Coil Spring

Claims (1)

[Scope of utility model registration request] 1. A magnetic reed switch disposed 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 coil spring. An impact sensor including a moving member provided with a magnet, the coil spring is fitted to a small diameter portion provided on an outer surface of the moving member, and is brought into contact with an end surface of the small diameter portion to move the moving member. A shock sensor characterized by being urged.