JPH01219565A - Acceleration detector - Google Patents

Abstract

PURPOSE:To eliminate the need for a high-sensitivity amplifier by providing a weight which moves in response to acceleration, a fixed element which restrains the movement of the weight magnetically, and a detecting element which detects the weight moving exceeding the restraint force of the fixed element. CONSTITUTION:When acceleration which is smaller than a constant value operates as shown by an arrow A, a pendulum 3 which is magnetized and the fixed element 5 which couples magnetically with the pendulum rotate around a rotary shaft 4 as shown by an arrow B. The conductive material 5d of the pedestal 5a of the fixed element 5 contacts contact points 6a and 6b provided to the periphery of the hole 2b of a case 2 and the contact points 6a and 6b are turned on electrically, so that the fixed element 5 stops on the external surface 2c of the case 2. When the acceleration exceeds the constant value, the pendulum 3 further rotates against the restraint force by the magnetic force with the fixed element 5. Consequently, the magnetic force of the pendulum 3 operates on a reed switch 7, which turns on. Variation of the electric signal of the switch 7 is detected to know that the acceleration larger than the constant value operates. Thus, two stages of acceleration can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an acceleration detector mounted to detect acceleration in a moving object such as an automobile.

[Conventional technology] This type of acceleration detector will be explained 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 movable up and down, and when upward/downward acceleration is applied to the acceleration detector 41, the movable body 44
A force proportional to the acceleration is applied downward/upward to the leaf spring 4.
3 is bent, the strain gauge 45 fixed to the temporary spring 43 is also distorted. The strain signal generated by the strain gauge 45 at this time is input to the control unit 47 via the output cord 46, and when the voltage amplified by the amplifier 48 exceeds a predetermined threshold, it is output from the voltage comparison circuit 49. The acceleration detection signal is output to the section 50 as an acceleration detection signal.

[Problems to be Solved by the Invention] However, since the device using the strain gauge described above requires a highly sensitive amplifier 48, there is one problem that hinders the reduction in price.

This invention was made to eliminate the above-mentioned problems, and an object of the invention is to provide an acceleration detector that is inexpensive and easy to detect failures.

[Means for Solving the Problems] The present invention provides a weight that moves in response to applied acceleration;
a stator that moves slightly in conjunction with the movement of the weight and then magnetically restrains movement of the weight; a first detection element that detects movement of the weight or the stator; The present invention is characterized by comprising a second detection element that detects movement exceeding the restraining force of the stator.

[Operation] The weight and the stator, which are joined by magnetic force, move in response to acceleration, and the first detection element detects the movement of the stator. Based on the detection status of the first detection element, it can be determined whether the weight and the stator are malfunctioning due to sticking or the like. Note that since the amount of movement of the stator is limited, the amount of movement of the weight connected to the stator is also limited. When a stronger acceleration is applied, the weight shakes off the magnetic force that binds it to the stator and moves. The second detection element detects movement of the weight moving away from the stator.

First Embodiment In FIG. 1 showing an embodiment of the present invention, inside a case 2 of an acceleration detector l, an inner surface 2a of the case 2 and a side surface 3a of a pendulum 3 face each other, and Close-up rectangular pendulum 3
is suspended by a rotating shaft 4 passing through one end of the pendulum 3. Further, the pendulum 3 is magnetized, for example, one end of the pendulum 3 is an S pole and the other end is an N pole. A hole 2b passing through the inner and outer surfaces of the case 2 is provided on the inner surface 2a of the case 2, which faces the lower end of the suspended pendulum 3. This hole 2b
A stator 5 is provided which is slidable through the hole 2b and has a T-shaped cross section. Furthermore, the end portion 5b of the stator 5 is made of a magnetic material. The stator 5 has a base 5a of the stator 5 protruding from the outer surface 2c of the case 2 at an appropriate distance,
This is a state in which the end portion 5b of the stator 5 is joined to the side surface 3a of the pendulum 3 by the magnetic force of the pendulum 3. Note that the pedestal 5a has a size that does not allow it to pass through the hole 2b, and a conductive member 5d is provided on the side surface 5c of the pedestal 5a. In addition, the stator 5 and the conductive member 5
It is electrically insulated from d. Further, a pedestal 5 of the stator 5 is provided around the outer surface 2c of the case 2 where the hole 2b is provided.
The contact point 6 is connected so as to be able to contact the conductive member 5d provided at the
a and 6b are provided. A lead wire 6c is connected to the contacts 6a and 6b. For example, the contact 6a is a positive pole, and the contact 6 is a positive pole.
b is connected to the negative pole.

Further, a reed switch 7 that is turned on and off by the magnetic force of the pendulum 3 is installed in a portion of the inner lower surface 2d of the case 2 that faces the locus of rotation of the pendulum 3. A lead wire 8 is connected to the reed switch 7 and led to the outside of the case 2.

Acceleration detector configured as above! is installed, for example, at a suitable location in a car with the lower surface 2d of the case 2 being horizontal. When no acceleration is acting on the acceleration detector l, the pendulum 3 is oriented vertically due to gravity, and the pendulum 3
The conductive member 5d of the pedestal 5a of the stator 5, which is magnetically connected to the conductive member 5d, and the contacts 6a and 6b are not in contact with each other. Therefore, contacts 6a and 6b are electrically off. When a first acceleration of a certain level or higher is applied in the direction of arrow A, the pendulum 3 and the stator 5 connected to the pendulum 3 by magnetic force,
It rotates in the direction of arrow B around the rotating shaft 4. Therefore, when the conductive member 5d of the pedestal 5a of the stator 5 comes into contact with the contacts 6a and 6b provided around the hole 2b, the contacts 6a and 6b are short-circuited via the conductive member 5d. It is electrically turned on. In addition, stator 5
Since the pedestal 5a 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, which is magnetically joined to the stator 5, is also suppressed. Therefore, at this first acceleration, the reed switch 7 is in an off state.

Note that when the applied acceleration decreases, the pendulum 3 rotates in the vertical direction due to gravity, and the stator 5 connected to the pendulum 3 also returns to its original position. Therefore, the conductive member 5 of the pedestal 5a of the stator 5
d and contacts 6a and 6b are not in contact, so contacts 6a and 6
b is electrically turned off.

Next, when a second acceleration of a certain level or more acts in the direction of arrow A, the contacts 6a and 6b are electrically turned on as described above, and the movement of the stator 5 is suppressed, but the pendulum 3 shakes off the magnetic restraining force with the stator 5 and rotates further. 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 electrical signal of the reed switch 7 in this manner, it can be determined that the second acceleration of a certain level or more has acted on the acceleration detector. Note that when the acceleration decreases, the pendulum 3 tries to return to 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 to the vertical direction, the pendulum 3 and the stator 5 are joined by magnetic force, and the conductive member 5d of the pedestal 5a of the stator 5 and the contacts 6a and 6b return to a non-contact state, and the contacts 6a and 6b returns from the on state to the off state.

As described above, this acceleration detector 1 is capable of detecting two levels of acceleration. Furthermore, by detecting the on/off states of the contacts 6a and 6b, it is possible to determine whether the pendulum 3 is fixed and cannot rotate.

In this embodiment, a reed switch was used as the element for detecting the second acceleration, but instead of a Hall IC.

The magnetic force of the pendulum 3 may be detected using a coil or the like.

Measure 2 (7) Kyodan Figure 2 shows another embodiment of the present invention, and since the basic structure is the same as that of the first embodiment, only the different parts will be described below. Note that the same reference numerals are given to the same members as those shown in the first embodiment.

In the first embodiment, the pendulum 3 was magnetized, but in this embodiment, the pendulum 3 is made of a magnetic material.

On the other hand, the end portion 5b of the stator 5 that is connected to the pendulum 3 is magnetized. Such a stator 5 is provided by passing the end portion 5b of the stator 5 through the spring lO and the hole 2b of the case 2 so that the base 5a of the stator 5 is located outside the case 2. In addition, with the pendulum 3 suspended in the vertical direction, the end portion 5b of the stator 5 is connected to the side surface 3a of the pendulum 3 by magnetic force. In addition, in this state, on the inner lower surface 2d of the case 2, there is a position facing the lower surface 3b of the pendulum 3.
Hall IC that turns on and off by sensing magnetism
I1 is provided. Furthermore, a microswitch 12 is provided inside the case 2 at a position where it comes into contact with the pendulum 3 when the pendulum 3 rotates in the direction of arrow B. A lead wire 8 is connected to the microswitch 12, and the lead wire 8 is connected to the case 2.
led to the outside of

The acceleration detector 1 configured as described above can detect two levels of acceleration similarly to the acceleration detector shown in the first embodiment.

If no acceleration is acting on the acceleration detector l, the pendulum 3
and the stator 5 are joined by magnetic force, and the pedestal 5 of the stator 5 is
Since a spring IO is provided between the outer surface 2c of the case 2 and the outer surface 2c of the case 2, the pendulum 3 cannot rotate freely as in the first embodiment, but the pendulum 3 is held at a predetermined position by the compressive force of the spring IO. Fixed.

When a first acceleration of a certain value or less is applied in the direction of arrow A, the pendulum 3 begins to rotate in the direction of arrow B. Accordingly, the stator 5, which is magnetically joined to the pendulum 3, also moves together with the pendulum 3 against the compressive force of the spring 10.

As the stator 5 moves, the magnetic effect of the stator end 5b on the Hall IC 1 becomes stronger (and the Hall IC
I1 generates an output signal by the magnetic force of the end 5b, and the first
acceleration can be detected.

Furthermore, when acceleration acts in the direction of arrow A, stator 5
Since the pedestal 5a contacts the side surface 2c of the case 2 via the spring IO, the stator 5 becomes immovable, 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 microswitch 12, and the microswitch 12 changes from the off state to the on state. Therefore, micro switch 1
By detecting the on/off state of the second acceleration, the second acceleration can be detected.

Note that when the acceleration decreases and stops acting, the pendulum 3 returns to the vertical direction due to gravity, so the microswitch 12
The switch installed in the switch returns to its original state, the micro switch 12 changes from on to off, and
The magnetic force of the stator 5 acting on l becomes weaker, and the Hall IC
The output of becomes zero and the acceleration detector l returns to its original state.

Third Embodiment FIG. 3 shows yet another embodiment of the present invention, in which the present acceleration detector is also capable of detecting two levels of acceleration as in the first and second embodiments. be.

Inside the case 15, a magnetic ball 16 made of a magnetic material and a cavity 17 in which the magnetic ball 16 is movable are provided. Further, a hole 19 passing through the wall surface 18 is provided 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 this hole 19. The stator 20 includes a shaft 20a that passes through the hole 19, and pedestals 20b and 2 that are attached to both ends of the shaft 20a and sandwich the wall surface t8 of the cavity [7].
0c, and the stator 20 has an H-shaped cross section. The length of the shaft 20a of the stator 20 in the vertical direction is the thickness of the wall surface 18 plus the gap 21, so the stator 20 can slide through the hole 19 by the size of the gap 21. . In addition, the two pedestals 2 of the stator 20
0b and 20c are magnetized.

A light emitting element 22 and a light receiving element 23 are provided on the outer surface of the case 15.
are installed facing each other. Incidentally, holes 22a and 23a are formed between the outer surface of the case I5 in which the light emitting element 22 and the light receiving element 23 are installed, and the cavity 17, so that the light emitted from the light emitting element 22 passes through the cavity 17 and reaches the light receiving element 23. The light is received at The installation position of the light emitting element 22 and the light receiving element 23 is the cavity 17.
When the pedestal 20b of the stator 20 located inside is in contact with the wall surface 18 and the magnetic sphere 16 is joined to the pedestal 20b by magnetic force, the light emitted by the light emitting element 22 is not blocked and the stator 20 When the light emitting element 22 moves into the cavity 17 by the distance of the gap 21, the magnetic sphere 16 blocks the light emitted from the light emitting element 22.

Further, in the direction opposite to the wall 0 surface 18 from the position where the light emitting element 22 and the light receiving element 23 are installed, the light emitting element 24 and the light receiving element 25 are placed in a case with an appropriate distance from the light emitting element 22 and the light receiving element 23. 15 in the same manner.

The acceleration detector 26 as described above is installed, for example, at an appropriate position in an automobile with the cavity 17 horizontal.

When no acceleration is acting on the acceleration detector 26, the pedestal 20b of the stator 20 and the wall surface 18 are in contact with each other, and the pedestal 20 is in contact with the wall surface 18.
Since the magnetic sphere 16 is connected to 0b, the light emitting element 22
The light emitted from and 24 is received by the light receiving elements 23 and 25, and the light receiving elements 23 and 25 are in an on state.

Next, when acceleration acts in the direction of the arrow, the stator 20
moves into the cavity 17 by the dimension of the gap 21 and stops.

Also, a magnetic ball connected to the stator 20! 6 also stator 2
0 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 an OFF state. However, since the optical axis emitted from the light emitting element 24 is not blocked, the light receiving element 25 maintains an on state.

Furthermore, when acceleration acts in the direction of arrow A, the magnetic ball 16 shakes off the magnetic force that is connected to the stator 20 and
move in the direction. Therefore, the light emitted from the light emitting elements 22 and 24 is blocked by the magnetic sphere 16, and the light emitted from the light receiving element 23
and 25 are turned off. In this way, acceleration detector 2
6 can also detect two levels of acceleration. Note that when the applied acceleration decreases or ceases to act, the magnetic sphere 16 is joined to the stator 20 by the magnetism of the pedestal 20b of the stator 20 and returns to its original state. Therefore, the light receiving elements 23 and 25 return to the on state again. In the above description, the movable body moving through the cavity 17 is spherical, but it may be cylindrical.

As shown in the first to third embodiments above, the present acceleration detector can detect two levels of acceleration: the first acceleration and the second acceleration larger than the first acceleration. Furthermore, by detecting the first acceleration, it is possible to confirm whether the acceleration detector is operating normally.

[Effects of the Invention] As detailed above, according to the present invention, there is provided a stator that moves slightly due to the applied acceleration, a first detection element that detects the movement of the stator, and a magnetic force applied to the stator. Joined at
This acceleration detector has two stages: a weight that separates from the stator only when an acceleration that exceeds the binding force due to the magnetic force is applied, and a second detection element that detects movement of the weight separated from the stator. Acceleration can be detected and the electrical signals output from the first and second sensing elements do not require a highly sensitive amplifier. Therefore, the price of the acceleration detector can be reduced. Furthermore, it is possible to determine an abnormality such as malfunction of a moving part that responds to acceleration based on the operating status of the first detection element.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an acceleration detector showing a first embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of an acceleration detector showing a second embodiment of the present invention, and FIG. FIG. 4 is a vertical cross-sectional view of a conventional acceleration detector and a diagram schematically showing 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. Patent applicant Sumitomo Electric Industries, Ltd.

Claims (9)

[Claims] (1) A weight that moves in response to the 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 stator. An acceleration detector comprising: a first detection element that detects movement of the weight; and a second detection element that detects movement of the weight exceeding the restraining force of the stator. (2) Claim 1, wherein the first detection element is constituted by an electric contact, and the electric contact becomes conductive when the stator having a conductive portion comes into contact with the first detection element.
Acceleration detector described. (3) The acceleration detector according to claim 1, wherein part or all of the stator is made of a magnetic material or a magnet, and the first detection element is made of a magnetically sensitive element. (4) The acceleration detector according to claim 1, wherein the first detection element is an optical detector. (5) The acceleration detector according to claim 1, wherein a part of the case constituting the acceleration detector has a hole through which the stator can move. (6) The acceleration detector according to claim 1, further comprising a spring material between the case and the stator protruding from the case, which is compressed with a force weaker than the restraining force of the weight and the stator. (7) The acceleration detector according to claim 1, wherein the weight is suspended and rotated in a pendulum shape. (8) The acceleration detector according to claim 1, wherein the weight is spherical. (9) The acceleration detector according to claim 1, wherein the weight is cylindrical.