JP3153326B2 - 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 for use in an airbag system for ensuring the safety of a driver and a passenger from the impact of an automobile collision, and more particularly to a collision sensor for safing with a main collision sensor. About.

[0002]

2. Description of the Related Art As this kind of airbag system,
There is one shown in the circuit diagram of FIG. In FIG. 3, reference numeral 1 denotes a power supply mounted on a vehicle, 2 denotes an ignition switch, 3 denotes an operating device, and 4 denotes an airbag module, and these constitute an airbag system. The airbag module 4 includes an airbag 5, a gas generator 6 for inflating the airbag 5, and a squib 7 such as a heating coil for starting the gas generator 6. It is installed in the console box of etc. The operating device 3 has a series connection circuit of a main collision sensor 8 and a safing collision sensor 9. The main collision sensor 8 may be, for example, one that mechanically closes an electric contact at the time of a collision, or one that is constituted by a piezoelectric element or a semiconductor element, and can take out an electric signal proportional to the magnitude of acceleration. In some cases. The mechanical sensor is installed in an engine room or the like, and the electric sensor is installed in a room or the like suitable for each collision detection characteristic. The safing collision sensor 9 is for preventing malfunction of the airbag system and improving the reliability of the system. The safing collision sensor 9 is placed in a room different from a place where the mechanical main collision sensor 8 is installed. The electric main collision sensor 8 is collectively installed at the same place. And the mechanical main collision sensor 8
In relation to, accidentally when checking the engine room, etc.,
Even if the main collision sensor 8 is turned on by giving an impact, the safing collision sensor 9 is kept off and the airbag system is not started. In relation to the electric main collision sensor 8, even if the main collision sensor 8 is turned on due to electromagnetic interference or the like, the safing collision sensor 9 remains off, and the airbag system does not start. ing.

The main collision sensor 8 corresponds to various types of collisions, and is turned on when a specific acceleration waveform is detected. Regardless of the type of collision, the safing collision sensor 9 must be set to O within the collision detection time of the main collision sensor 8.
N, and a long collision detection time is required. That is, the requirements for the safing collision sensor 9 include operating at a low acceleration, a long collision detection time (contact closing time), a simple structure, and high reliability.

As a conventional safing collision sensor 9 which satisfies such requirements to some extent, there is a collision sensor using a reed switch shown in FIG.

The detailed structure and operation of the safing collision sensor 9 will be described with reference to FIG. Reed switch 16
A cylindrical body 12 having the reed switch 16 provided therein, a perforated magnet 13 which is loosely fitted to the outside of the cylindrical body 12 and moves upon sensing a collision to actuate the reed switch 16; The structure comprises a spring 14 for urging in the anti-collision direction and a housing 11 to which the cylindrical body 12 is fixed. A spring 14 is fitted outside the cylindrical body 12. Further, a stopper 15 is provided in the moving direction of the magnet to regulate the moving range.

Next, the operation of the collision sensor having such a structure will be described below. Normally, a reed switch 16 fixed in the cylinder 12 is a magnetic tongue 16 forming a contact.
a, 16b, which are open as shown
Is located on the right side of the drawing by the urging force of the spring 14. Due to the acceleration change accompanying the collision, the magnet 13 overcomes the urging force of the spring 14 and moves to the left in the drawing. When the magnet 13 approaches the reed switch 16 to some extent, the magnetic lines of force of the magnet 13 cause the magnetic tongue pieces 16a, 16b forming the contact points.
, The magnetic tongue pieces 16a and 16b are magnetized and closed.

In the above collision sensor, the magnet 13
Moves in response to the change in acceleration, and reaches the position e, the reed switch 16 closes. When the magnet reaches the position f, the angle formed by the line of magnetic force and the magnetic segment 16b changes and becomes nearly parallel, so that the reed switch 16 is opened. That is, the contacts are closed only during the time when the magnet 13 is located in the section L from the position e to the position f.

In the above-described collision sensor shown in FIG. 4, by extending the time during which the magnet 13 is present in the section L,
A long contact closing time can be obtained. Therefore, a collision sensor 20 as shown in FIG.
9) has been proposed. The collision sensor 20 includes a reed switch 16 and a cylinder 1 in which the reed switch 16 is provided.
2, a magnet 13 that is loosely fitted to the outside of the cylinder 12 and operates the reed switch 16, a first spring 14 that urges the magnet 13 in the anti-collision direction, and a magnet 12 A carriage 21 slidable at both ends of the cylindrical body 12, a non-magnetic mass 23 which is loosely fitted to the outside of the carriage 21 and moves upon sensing a collision, and a non-collision with the non-magnetic mass 23. Second spring 22 biasing in the direction
And a housing 11 to which the cylindrical body 12 is fixed.

The operation of the collision sensor having such a structure is as follows. Due to the acceleration change accompanying the collision, the magnet 13 overcomes the urging force of the first spring 14 and moves to the left in the drawing. When the magnet 13 comes to a position where the reed switch 16 is operated, the carriage 21 is in contact with the end of the housing 11 and thus tries to move in the anti-collision direction. At that time, the non-magnetic mass 23 is attached to the second spring 22. Since it moves to the end of the carriage 21 on the left side of the drawing overcoming the force, the carriage 21 and the magnet 13 are moved during the entire moving time of the nonmagnetic mass 23 by the inertial force of the nonmagnetic mass 23 transmitted to the end of the carriage 21. The reed switch is maintained in a position to operate.

[0010]

However, in such a collision sensor operated as described above, the inertial force of the non-magnetic mass 23 for maintaining the magnet 13 at the position where the reed switch 16 is operated depends on the acceleration change accompanying the collision. Therefore, there is a problem that it is difficult to obtain a specific long contact closing time corresponding to various collision modes such as a frontal collision and an oblique collision. In addition, the non-magnetic mass 23 is
Since the movement of the non-magnetic mass 23 completely depends on the movement of the carriage 21 due to the structure of riding on the top, the inertial force of the non-magnetic mass 23 can be sufficiently increased when necessary depending on the manner of movement of the carriage 21. There was a problem that it could not be used.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a collision sensor using a reed switch,
The contact closing time can be freely adjusted.

[0012]

In order to solve the above-mentioned object, a collision sensor according to the present invention comprises a reed switch, a first cylindrical body in which the reed switch is provided, and a reed switch outside the first cylindrical body. A first magnet that is fitted and moves upon sensing a collision to actuate the reed switch, a first spring that urges the first magnet in an anti-collision direction, a first magnet that is concentric with the first cylinder, and the like; And a second magnet or magnetic mass that is loosely fitted to the outside of the second cylindrical body and moves upon sensing a collision to actuate the reed switch, and the second magnet or magnetic mass. A second spring biasing in the anti-collision direction, wherein a movement speed at the time of collision between the system of the first magnet and the first spring and a movement speed at the time of collision of the system of the second magnet or the magnetic mass and the second spring. There is a difference between them. The present invention eliminates obstacles due to the subordination of the motion system by completely making the structure of the first cylinder system for operating the reed switch and the structure of the second cylinder system for extending the contact closing time completely mechanically independent. 1
The inertia force acting on the first cylinder system can be adjusted by adjusting the strength of the magnetic force of the magnet forming the cooperative movement between the cylinder system and the second cylinder system.

[0013]

When there is a difference between the movement speed of the system of the first magnet and the first spring at the time of collision and the movement speed of the system of the second magnet or the magnetic mass and the system of the second spring at the time of collision, the difference between these magnets or The magnetic mass moves to the position to activate the reed switch,
The staggered approach results in the magnet being long in the position to actuate the reed switch, resulting in a long contact closure time.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a collision sensor of the present invention, and FIG. 2 is a diagram showing an operation of the collision sensor of the present invention. FIG. 1 differs from FIG. 4 in that two magnets which are independently urged in the anti-collision direction by two springs and actuate a reed switch are provided.

In FIG. 1, a collision sensor 30 has a reed switch 36, a first cylindrical body 32 in which the reed switch 36 is provided, and is loosely fitted to the outside of the first cylindrical body 32 to move upon sensing a collision. A perforated first magnet 33 for actuating the reed switch, a first spring 34 for urging the first magnet 33 in the anti-collision direction, and movement of the magnet to limit the amount of movement of the first magnet 33. Stopper 35 provided in the direction
A second cylindrical body 37 for accommodating the first cylindrical body 32, and a perforated second magnet 38 which is loosely fitted to the outside of the second cylindrical body 37, moves upon sensing a collision, and operates the reed switch. When,
A second spring 39 for urging the second magnet in the anti-collision direction
A stopper 40 provided in a moving direction of the magnet to limit a moving amount of the second magnet 38;
This is a structure including a housing 31 to which the cylindrical body is fixed. A spring 3 is provided outside the cylindrical bodies 32 and 37.
4 and 39 are fitted respectively. Here, in order to provide a speed difference between the two magnets so that the first magnet 33 moves faster than the second magnet 38, the first spring 34,
The spring constants k1 and k2 of the second spring 39 are adjusted to k1 <k2, and the masses m1 and m2 of the first magnet 33 and the second magnet 38 are adjusted to m1 ≧ m2. In addition, the magnetic force is adjusted so that these magnets are long at a position where the reed switch is operated by each other,
The polarities of both magnets may be in different directions or in the same direction. FIG. 2 is shown in a different direction.

Next, the operation of the above-structured collision sensor 30 will be described with reference to FIG. Normally, as shown in FIG. 2A, the magnetic tongue pieces 36a and 36b constituting the contacts of the reed switch 36 fixed in the first cylindrical body 32 are open, and the two magnets 33 and 38 Each of them is located on the right side in the drawing by the urging force of the first spring 34 and the second spring 39.

When a collision occurs, the two magnets 33 and 38 are respectively driven by the first spring 3 due to a change in acceleration accompanying the collision.
4. Overcome the biasing force of the second spring 39 and move to the left in the drawing. Here, the spring constants k1 and k2 of the first spring 34 and the second spring 39 are k1 <k
2, the respective masses m1 and m2 of the first magnet 33 and the second magnet 38 are adjusted so that m1 ≧ m2, so that the first magnet 33 moves faster than the second magnet 38. As shown in FIG. 2B, the first magnet 33 first enters the section L in which the reed switch 36 is operated, and the contact of the reed switch 36 is closed. Subsequently, the second magnet 3
8 attempts to enter section L where the reed switch 36 is activated. At that time, if the respective magnets are in different directions, they repel each other because they have the same polarity as shown, and the second magnet 38 is slowed down and enters the section L. When the respective magnets are in the same direction, the speed at which the first magnet 33 is attracted by the second magnet 38 and leaves the section L in which the reed switch 36 is operated is reduced.

When further moved, as shown in FIG. 2C, the second magnet 38 is provided at the end of the second cylindrical body 37, changes its direction to the stopper 40, and tries to move in the anti-collision direction. On the other hand, the first magnet 33 is about to go out of the section L. At this time, when the respective magnets are in different directions, the first magnet 33 has a repulsive force outside the section L because the polarity is the same as shown in the drawing. Receive. However, with the second magnet 38, the contact of the reed switch 36 remains closed. When the polarities of the respective magnets are in the same direction, the speed at which the first magnet 33 is attracted by the second magnet 38 and exits from the section L where the reed switch 36 is operated is reduced. During this time, since the magnet is present in the section L, the contact of the reed switch 36 is kept closed.

Next, as both magnets move, FIG.
As shown in (d), the first magnet 33 and the second magnet 38
Overlap. At this time, if the respective magnets are in different directions, the attracting force works because the polarity is different as shown in the figure, and the magnets are integrated,
Since the mass in which the masses m1 and m2 of the two magnets are combined moves, the moving speed is further reduced. When the magnets are in the same direction, if the magnets that were initially attracted approach each other so as to overlap each other, they repel each other and the moving speed of both magnets is further reduced. During this time, since the magnet exists in the section L, the contact of the reed switch 36 is kept closed.

As a result, the magnet is long at the position where the reed switch is operated, and a long contact closing time is obtained.

In the above embodiment, the difference between the velocities of the two magnets is set so that the second magnet moves faster than the first magnet. To k1 <k2, the first magnet 33 and the second
Although the respective masses m1 and m2 of the magnets 38 are adjusted to m1 ≧ m2, the respective spring constants k1 and k2 of the first spring 34 and the second spring 39 are set so that the first magnets move faster than the second magnets. To k1> k2 and the first magnet 3
3, the respective masses m1 and m2 of the second magnet 38 are set to m1 ≦
The same effect can be obtained by adjusting to m2. Further, a magnetic mass may be used in place of the second magnet of the above-described embodiment. However, in this case, the spring constant of the spring and the mass of the magnet are set so that the magnetic mass exists within a range magnetized by the magnetic force of the first magnet. And magnetic force, the amount of travel of the magnet, etc. are adjusted.

[0022]

According to the present invention, the collision sensor has a movement speed between the first magnet and the first spring system at the time of collision and the second magnet or magnetic mass and the second spring system at the time of collision. By providing the difference, these magnets or magnetic masses are continuously shifted to enter the position where the reed switch is operated, and as a result, the magnets are long at the position where the reed switch is operated. Therefore, a long contact closing time is obtained. Further, the difference between the movement speed of the first magnet and the first spring system at the time of collision and the movement speed of the second magnet or the magnetic mass and the second spring at the time of collision depends on the magnitude of the impact force due to the collision. , Because it is determined only by the spring constant of the spring, the mass and magnetic force of the magnet, the amount of travel of the magnet, etc., the contact closing time can be freely adjusted, and the safing has a sufficient closing time corresponding to various types of collisions. Optimum as a collision sensor for

[Brief description of the drawings]

FIG. 1 is a diagram showing a collision sensor of the present invention.

FIG. 2 is a diagram illustrating the operation of the collision sensor of the present invention.

FIG. 3 is a circuit diagram of an airbag system using a collision sensor.

FIG. 4 is a sectional view showing a conventional collision sensor.

FIG. 5 is a sectional view showing another conventional collision sensor.

[Explanation of symbols]

 Reference Signs 30 collision sensor 31 housing 32 first cylinder 33 first magnet 34 first spring 35, 40 stopper 36 reed switch 37 second cylinder 38 second magnet 39 second spring

Continuation of front page (72) Inventor Yasunori Otsuki 21-1, Taishido, Taishiro-ku, Sendai-shi, Miyagi Prefecture Tokin Co., Ltd. (56) References JP-A-59-86127 (JP, A) JP-A-3-48169 ( JP, A) JP-A-3-110731 (JP, A) JP-A-4-63071 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01P 15/135 H01H 35/14

Claims (1)

(57) [Claims] 1. A reed switch, a first cylindrical body in which the reed switch is provided, and a first cylinder which is loosely fitted to the outside of the first cylinder and moves upon sensing a collision to actuate the reed switch.
A magnet, a first spring for urging the first magnet in the anti-collision direction, a second cylinder for accommodating the first magnet and the like in a concentric circle with the first cylinder, and a play outside the second cylinder. A second magnet or magnetic mass that is fitted and moves upon sensing a collision to actuate the reed switch, and a second spring that biases the second magnet or the magnetic mass in the anti-collision direction, comprises a first magnet and First
A collision sensor wherein a difference is provided between a movement speed of the spring system at the time of collision and a movement speed of the second magnet or magnetic mass and the second spring system at the time of collision.