JP2550133B2 - Acceleration detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration detector mounted to detect acceleration in a moving body such as an automobile.

[Prior Art] This type of acceleration detector will be described below.

FIG. 4 shows an acceleration detector 41 using a strain gauge. A movable body 44 supported by a leaf spring 43 is provided in the case 42 so as to be vertically movable. When an upward / downward acceleration is applied to the acceleration detector 41, the movable body 44 is proportional to the acceleration. Since force is applied in the downward / upward direction to bend the leaf spring 43, the strain gauge 45 fixed to the leaf spring 43 is also distorted. The strain signal generated in the strain gauge 45 at this time is input to the control unit 47 via the output code 46, and output from the voltage comparison circuit 49 when the voltage amplified by the amplifier 48 exceeds a predetermined threshold value. An acceleration detection signal is output to the unit 50.

[Problems to be Solved by the Invention] However, the one using the strain gauge as described above requires the high-sensitivity amplifier 48, and thus has a problem of hindering cost reduction.

The present invention has been made in order to eliminate the above-mentioned problems, and an object thereof is to provide an acceleration detector which is inexpensive and whose failure detection is easy.

[Means for Solving the Problem] According to the present invention, a weight that moves in response to an applied acceleration and a slight movement in conjunction with the movement of the weight, and thereafter, magnetically restrains the movement of the weight. A stator, a first detection element that detects the movement of the weight or the stator, and a second detection element that detects that the weight moves beyond the restraining force of the stator. Is characterized by.

[Operation] The weight and the stator joined by magnetic force move in response to the acceleration, and the first detection element detects the movement of the stator.
It can be determined from the detection status of the first detection element whether the weight and the stator are malfunctioning due to sticking or the like. still,
Since the moving amount of the stator is limited, the moving amount of the weight joined to the stator is also limited. When a stronger acceleration acts, the weight moves away from the restraining force with the stator due to the magnetic force. The second detection element detects the movement of the weight moving away from the stator.

Example 1 First Example Referring to FIG. 1 showing an example of the present invention, inside case 2 of acceleration detector 1, inner surface 2a of case 2 and side surface 3a of pendulum 3 face each other, and A strip-shaped pendulum 3 is approached and is suspended by a rotary shaft 4 that penetrates one end of the pendulum 3. The pendulum 3 is magnetized, and for example, the pendulum 3
Has an S pole at one end and an N pole at the other end. A hole 2b penetrating the inner and outer surfaces of the case 2 is provided on the inner surface 2a of the case 2 that faces the lower end of the suspended pendulum 3. A stator 5 having a T-shaped cross section is provided in the hole 2b so as to be slidable in the hole 2b. The end 5b of the stator 5 is made of a magnetic material. In the state where the pedestal 5a of the stator 5 is projected from the outer surface 2c of the case 2 with an appropriate gap and the end 5b of the stator 5 is joined to the side surface 3a of the pendulum 3 by the magnetic force of the pendulum 3, is there. The pedestal 5a has a size that cannot pass through the hole 2b, and the side surface 5c of the pedestal 5a is provided with a conductive member 5d.
The stator 5 and the conductive member 5d are electrically insulated. Further, contacts 6a and 6b are provided on the outer surface 2c of the case 2 around the hole 2b so as to be in contact with the conductive member 5d provided on the pedestal 5a of the stator 5. A lead wire 6c is connected to the contacts 6a and 6b, for example, the contact 6a is connected to a positive pole and the contact 6b is connected to a negative pole.

Further, a reed switch 7 for turning the switch on and off by the magnetic force of the pendulum 3 is installed at a portion of the inner lower surface 2d of the case 2 facing the trajectory of the pendulum 3 rotating. The lead wire 8 is connected to the reed switch 7, and the lead wire 8 is guided to the outside of the case 2.

The acceleration detector 1 configured as described above is installed, for example, at an appropriate location of the automobile with the lower surface 2d of the case 2 horizontal. When acceleration is not acting on the acceleration detector 1, the pendulum 3 is vertically oriented due to gravity, and
Conductive member of the pedestal 5a of the stator 5 which is joined by magnetic force with
5d and the contacts 6a and 6b are not in contact with each other. Therefore, contact 6a
6b is electrically off. When a first acceleration of a certain value or less in the direction of arrow A acts, the pendulum 3 and the stator 5 joined to the pendulum 3 by magnetic force rotate in the direction of arrow B about the rotation shaft 4. Therefore, the conductive member 5d of the pedestal 5a of the stator 5 and the contact 6a provided around the hole 2b and
By contacting 6b, the contacts 6a and 6b are short-circuited via the conductive member 5d, so that the contacts 6a and 6b are electrically turned on. Moreover, since the pedestal 5a of the stator 5 cannot pass through the hole 2b of the case 2, the movement of the stator 5 is suppressed and the rotation of the pendulum 3 joined to the stator 5 by magnetic force is also suppressed. Therefore, at the first acceleration, the reed switch 7 is off. When the applied acceleration decreases, the pendulum 3 rotates in the vertical direction due to gravity, and the stator 5 joined to the pendulum 3
Also returns to the original position. Therefore, the conductive member of the pedestal 5a of the stator 5
Since 5d and the contacts 6a and 6b are not in contact with each other, the contacts 6a and 6b are electrically turned off.

Next, when the second acceleration of a certain level or more acts in the direction of the arrow A, the contacts 6a and 6b are electrically turned on and the movement of the stator 5 is suppressed as described above.
The pendulum 3 is further rotated by shaking off the restraining force due to the magnetic force with the stator 5. As a result, the magnetic force of the pendulum 3 acts on the reed switch 7, and the reed switch 7 changes from the off state to the on state. By detecting the change in the electric signal of the reed switch 7 in this manner, it can be seen that the second acceleration above a certain level has acted on the acceleration detector. When the acceleration decreases, the pendulum 3 tends to return in the vertical direction due to gravity, so the magnetic force of the pendulum 3 acting on the reed switch 7 weakens, and the reed switch 7 returns from the on state to the off state. When the pendulum 3 further returns in the vertical direction, the pendulum 3 and the stator 5 are joined together by magnetic force and the pedestal 5a of the stator 5 is attached.
The conductive member 5d and the contacts 6a and 6b return to the non-contact state,
The contacts 6a and 6b return from the on state to the off state.

As described above, the acceleration detector 1 can detect acceleration in two stages. Further, by detecting the on / off state of the contacts 6a and 6b, it is possible to determine whether or not the pendulum 3 is fixed and cannot be rotated.

Further, as compared with the case where the stator 5 is fixed to the case 2, when an acceleration is applied to the acceleration detector 1 by providing a region in which the stator 5 can move freely as in this embodiment. The force due to the acceleration and the inertial force of the pendulum 3 generated while the stator 5 moves in the movable area are applied to the pendulum 3. Therefore, by adjusting the movable region length of the stator 5, the acceleration required for the pendulum 3 to move away from the stator 5 can be adjusted.

Although the reed switch is used as the element for detecting the second acceleration in this embodiment, a Hall IC, a coil or the like may be used to detect the magnetic force of the pendulum 3.

Second Embodiment FIG. 2 shows another embodiment of the present invention. Since the basic structure is the same as that of the first embodiment, only different points will be described below. The same members as those shown in the first embodiment are designated by the same reference numerals.

Although the pendulum 3 was magnetized in the first embodiment, the pendulum 3 is made of a magnetic material in this embodiment. On the other hand, pendulum 3
The end portion 5b of the stator 5 that is joined to is magnetized. Such a stator 5 is provided so that the end 5b of the stator 5 penetrates the spring 10 and the hole 2b of the case 2 so that the pedestal 5a of the stator 5 is located outside the case 2. In addition, when the pendulum 3 is suspended vertically, the end 5b of the stator 5 is
The side surface 3a of the pendulum 3 is magnetically bonded. Also in this state, the lower surface 2d of the case 2 has a lower surface of the pendulum 3.
A Hall IC 11 that is turned on and off by sensing magnetism is provided at a position facing 3b. Case 2
When the pendulum 3 rotates in the direction of arrow B, the pendulum 3
A micro switch 12 is provided at a position where it contacts with. The lead wire 8 is connected to the microswitch 12, and the lead wire 8 is guided to the outside of the case 2.

The acceleration detector 1 configured as described above can detect acceleration in two stages, like the acceleration detector shown in the first embodiment.

When no acceleration is applied to the acceleration detector 1, the pendulum 3 and the stator 5 are magnetically joined to each other, and the pedestal of the stator 5 is further attached.
Since the spring 10 is provided in the gap between the outer surface 2c of the case 2 and the case 5a, the pendulum 3 does not rotate freely as in the first embodiment, and the pendulum 3 is moved to a predetermined position by the compression force of the spring 10. It is fixed to.

When a certain first acceleration or less in the direction of arrow A acts, the pendulum 3 starts to rotate in the direction of arrow B. Along with this, the stator 5 joined to the pendulum 3 by magnetic force also moves together with the pendulum 3 against the compressive force of the spring 10.
As the stator 5 moves, the magnetic action of the end portion 5b of the stator on the Hall IC 11 becomes stronger, and the Hall IC 11 moves toward the end portion 5b.
An output signal can be generated by the magnetic force of and the first acceleration can be detected.

Further, when acceleration acts in the direction of arrow A, the pedestal 5a of the stator 5 comes into contact with the side surface 2c of the case 2 via the spring 10, so that the stator 5 cannot move but the pendulum 3
Shakes off the magnetic force of the stator 5 and further rotates in the direction of arrow B. Therefore, the pendulum 3 pushes the switch installed in the micro switch 12, and the micro switch 12 is switched from the off state to the on state. Therefore, turning on the micro switch 12,
The second acceleration can be detected by detecting the off state.

If the acceleration decreases and stops working, the pendulum 3
Will return vertically due to gravity, so microswitch 12
The switch installed in the switch returns to its original state, the micro switch 12 changes from on to off, the magnetic force of the stator 5 acting on the Hall IC 11 also weakens, the output of the Hall IC becomes zero, and the acceleration detector 1 becomes Return to the original state.

Also in this embodiment, the stator 5 is used as in the first embodiment.
By adjusting the movable length of, the inertial force applied to the pendulum 3 is adjusted, and the detection level of the second acceleration can be adjusted.

Third Embodiment FIG. 3 shows still another embodiment of the present invention.
The acceleration detector 1 is also capable of detecting acceleration in two stages as in the first and second embodiments.

Inside the case 15, a magnetic ball 16 made of a magnetic material and a cavity 17 in which the magnetic ball 16 can move are provided. Further, a hole 19 penetrating the wall surface 18 is formed in the center of the wall surface 18 of the cavity 17.
And a stator 20 that slides in the hole 19 is provided in the hole 19. The stator 20 has a shaft 20a passing through the hole 19.
And the pedestals 20b and 20c attached to both ends of the shaft 20a and sandwiching the wall surface 18 of the cavity 17, and the stator 20 has an H-shaped cross section. Shaft 20a of stator 20
The length in the vertical direction is the thickness of the wall surface 18 plus the gap 21, so that the stator 20 can slide in the hole 19 by the size of the gap 21. Also, the two pedestals 20 of the stator 20
b and 20c are magnetized.

A light emitting element 22 and a light receiving element 23 are installed on the outer surface of the case 15 so as to face each other. It should be noted that holes 22a and 23a are opened in the outer surface of the case 15 in which the light emitting element 22 and the light receiving element 23 are installed and the cavity 17, and the light emitted from the light emitting element 22 passes through the cavity 17 and the light receiving element 23. Is received at. Light emitting element 22 and light receiving element 23
Is installed on the base 20b of the stator 20 located inside the cavity 17.
Contact the wall surface 18 and magnetic force is applied to the pedestal 20b by magnetic force.
The light emitted from the light emitting element 22 is not blocked when the two are joined, and when the stator 20 moves into the cavity 17 by the size of the gap 21, the light emitted from the light emitting element 22 becomes a magnetic ball. It is a position where it is shut off at 16. Further, in a direction opposite to the wall surface 18 from the position where the light emitting element 22 and the light receiving element 23 are installed, the light emitting element 22 and the light receiving element 25 have an appropriate interval, and the light emitting element 24 and the light receiving element 25 are in the case 15. Also installed on the surface.

The acceleration detector 26 as described above is installed, for example, with the cavity 17 horizontal at an appropriate position of the automobile. Acceleration detector 26
When no acceleration is applied to the pedestal 20, the pedestal 20b of the stator 20 and the wall surface 18 are in contact with each other, and the magnetic ball 16 is joined to the pedestal 20b, so that the light emitted from the light emitting elements 22 and 24 is received. Light is received by the elements 23 and 25, and the light receiving elements 23 and 25 are in the ON state. Next, when acceleration acts in the direction of arrow A, the stator 20 moves into the cavity 17 by the size of the gap 21 and stops. Further, the magnetic sphere 16 bonded to the stator 20 also moves together with the stator 20 and blocks the optical axis emitted from the light emitting element 22. Therefore, the light receiving element 23 does not receive light and changes to the off state. However, since the optical axis emitted from the light emitting element 24 is not blocked, the light receiving element 25 maintains the ON state.

Further, when the acceleration acts in the direction of arrow A, the magnetic balls 16 move in the direction of arrow B to shake off the magnetic force bonded to the stator 20. Therefore, the light emitted from the light emitting elements 22 and 24 is blocked by the magnetic ball 16 and the light receiving elements 23 and 25 are turned off. In this way, the acceleration detector 26 can also detect two levels of acceleration. If the applied acceleration decreases or stops working, the magnetic ball 16 becomes the stator.
The pedestal 20b of 20 joins the stator 20 by magnetism and returns to the original state. Therefore, the light receiving elements 23 and 25 are returned to the ON state again.
Although the moving body that moves the cavity 17 is spherical in the above description,
It may be cylindrical.

As shown in the above-described first to third embodiments, the present acceleration detector has the first acceleration and the second acceleration larger than the first acceleration.
It is possible to detect the acceleration of two stages of the acceleration. Further, by detecting the first acceleration, it is possible to confirm whether or not the acceleration detector is operating normally.

[Effects of the Invention] As described in detail above, according to the present invention, the stator that slightly moves due to the acting acceleration, the first detection element that detects the movement of the stator, and the magnetic force applied to the stator. The main acceleration is detected by providing a weight that separates from the stator and a second detection element that detects the movement of the weight that is separated from the stator only when an acceleration exceeding the restraining force due to this magnetic force is applied. The detector is capable of detecting two stages of acceleration and the electrical signals output from the first and second detection elements do not require a sensitive amplifier. Therefore, the cost of the acceleration detector can be reduced. Further, it is possible to judge an abnormality such as a malfunction of the moving part corresponding to the acceleration, based on the operating condition of the first detecting element.

[Brief description of drawings]

1 is a vertical sectional view of an acceleration detector showing a first embodiment of the present invention, FIG. 2 is a vertical sectional view of an acceleration detector showing a second embodiment of the present invention, and FIG. FIG. 4 is a vertical sectional view of an acceleration detector showing a third embodiment of the present invention, and FIG. 4 is a vertical sectional view of a conventional acceleration detector and an outline of a device connected to the acceleration detector. . 3 ... Pendulum, 5 ... Stator, 6a, 6b ... Contact, 7 ... Reed switch, 11 ... Hall IC, 12 ... Micro switch, 16 ... Magnetic ball, 20 ... Stator, 22 , 24 …… Light emitting element, 23, 25 …… Light receiving element.

Claims (4)

(57) [Claims] 1. A weight that moves in response to an applied acceleration, a stator that moves slightly in conjunction with the movement of the weight, and then magnetically restrains the movement of the weight, and the weight or the weight. An acceleration detector comprising: a first detection element that detects a movement of a stator; and a second detection element that detects that the weight moves beyond a restraining force of the stator. 2. The first detection element comprises an electrical contact,
The acceleration detector according to claim 1, wherein the stator having a conductive portion is configured to come into contact with the first detection element so that the electrical contact becomes conductive. 3. The acceleration detector according to claim 1 or 2, wherein a part of a case constituting the acceleration detector has a hole through which the stator can move. 4. The acceleration detector according to claim 3, further comprising a spring member which is compressed between the case and the stator protruding from the case by a force weaker than a restraining force of the weight and the stator.