JPH05264582A - Acceleration sensor - Google Patents

Abstract

PURPOSE:To obtain an acceleration sensor hardly causing malfunction due to tilted arrangement. CONSTITUTION:The system has a non-magnetic case 1, a magnet 2, a magnet responding switch 3 and a support device 5. The magnet 2 is arranged in the non-magnetic case 1, supported with magnetic fluid 4 and floats on the inner surface of the bottom 101. The magnet responding switch 3 is arranged at lower outside of the bottom 101 of the case 1 so that it responds to the position of the moving magnetic body 3. The support device 5 supports the non-magnetic case 1 so as to keep the horizontal position before the inclination even in case of inclination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor for detecting acceleration associated with vibration or the like.

[0002]

2. Description of the Related Art As prior art similar to this type of acceleration sensor, Japanese Patent Laid-Open No. 63-21884 and Japanese Patent Laid-Open No. 6-19884 are known.
JP-A-3-317712, JP-A-63-26520, JP-A-63-141415 and JP-A-63-7.
There is a tilt sensor known from Japanese Patent No. 0017, etc. FIG. 9 is a plan view showing its basic structure, and FIG. 10 is a partial sectional view of the same. In the figure, 1 is a non-magnetic case made of a non-magnetic material, 2 is a magnet, and 3 is a magnetically responsive switch. The non-magnetic case 1 has a bottom portion 101 and a side wall surface 102 continuously standing up the entire circumference thereof. The magnet 2 is arranged inside the non-magnetic case 1, and the magnetic fluid 4
And is floated on the inner surface of the bottom portion 101. The magnetic response switch 3 is arranged outside the bottom portion 101 and responds to the position of the magnet 2.

As shown in FIG. 10, when an acceleration due to vibration or the like is received, the magnet 2 moves while being supported by the magnetic fluid 4, and the relative position with respect to the magnetic responsive switch 3 changes. The magnetic responsive switch 3 has a sensitive area S1 and a dead area S2 with respect to the position of the magnet 2. The sensitive area S1 is an area in which the magnetically responsive switch 3 performs a switch operation under the action of the magnetic field generated by the magnet 2, and the insensitive area S2 is an area in which the magnetically responsive switch 3 is not substantially affected by the magnetic field of the magnet 2. Is. When the magnetic response switch 3 is turned on in the sensitive area S1, it is turned off in the insensitive area S2. As a result, the magnetically responsive switch 3 responds to the magnetic field of the magnet 2 to turn on or off, and the acceleration is detected.

[0004]

However, the object on which the acceleration sensor is mounted is tilted due to some reason such as ground subsidence, or the mounting state of the acceleration sensor on the object is changed, and the acceleration sensor is tilted. In that case, the magnet 2 will move in the tilt direction as shown in FIG. Therefore, in the tilt direction, the magnet 2 enters the dead region S2 with a small acceleration, and the acceleration response characteristic in the tilt direction becomes sensitive. On the contrary,
In the direction opposite to the tilt direction, the distance to the dead area S2 becomes large, and a large acceleration is required for the magnet 2 to enter the dead area S2, so the detection operation becomes insensitive. Therefore, a malfunction is likely to occur.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems and provide an acceleration sensor which does not cause a malfunction due to an inclined arrangement.

[0006]

In order to solve the above problems, the present invention is an acceleration sensor having a non-magnetic case, a magnet, a magnetically responsive switch, and a supporting device, wherein the magnet is the non-magnetic case. The magnetic responsive switch is disposed in a magnetic case, is supported by a magnetic fluid, and floats on the inner surface of the bottom of the non-magnetic case. And the supporting device keeps the non-magnetic case in a horizontal position before tilting when it is tilted,
It is characterized by supporting the non-magnetic case.

[0007]

[Function] The magnet is arranged in the non-magnetic case, is supported by the magnetic fluid, and floats on the inner surface of the bottom.
The magnetic response switch is located outside the bottom of the non-magnetic case so that it responds to the position of the magnet. As it moves on the inner surface of the bottom, the relative position to the magnetically actuated switch changes. As a result, the magnetic response switch is turned on or off in response to the magnetic field of the magnet, and the acceleration is detected.

Since the supporting device supports the non-magnetic case so that the non-magnetic case maintains the horizontal position before the tilt when the device is tilted, the object on which the acceleration sensor is attached does not cause a ground subsidence or the like. Even if the support device tilts due to tilting due to some reason or the mounting state of the acceleration sensor on the object changing, the position of the magnet located inside the non-magnetic case does not change and is affected by the tilting. Acceleration can be detected without

[0009]

1 is a plan view of an acceleration sensor according to the present invention,
FIG. 2 is a partial sectional view of the same. In the figure, 1 is a non-magnetic case, 2 is a magnet, 3 is a magnetically responsive switch, 4 is a magnetic fluid, 5 is a supporting device, and g is the direction of gravity.

The case 1 has a bottom portion 101 and a side wall surface 102 continuously standing up the entire circumference thereof.
The planar shape of 1 is substantially circular. In the illustration,
Although the inner surface of the bottom portion 101 is concave, it may be flat. The case 1 is made of a non-magnetic material such as aluminum or plastic as in the conventional case.
The magnet 2 is disposed inside the case 1, is supported by the magnetic fluid 4, and floats above the inner surface 111 of the bottom portion 101. The magnet 2 is vertically or radially magnetized. The magnetic fluid 4 is a liquid having relatively low viscosity such as fine magnetic particles of cobalt, iron, nickel, etc., such as kerosene,
It is dispersed in water or the like, and generally, a surfactant is adsorbed on the fine particles and stably dispersed.

The magnetically-actuated switch 3 is arranged so as to have a fixed relationship with the case 1. Although it is installed vertically in the figure, it may be installed horizontally. Further, the number is not limited to one and may be plural. The magnetic response switch 3 has a sensitive area S1 and a dead area S2 with respect to the position of the magnet 51. The sensitive area S1 is an area in which the magnetically responsive switch 3 operates under the action of the magnetic field of the magnet 51, and the dead area S2 is an area in which the magnetically responsive switch 3 is not substantially affected by the magnetic field of the magnet 51. .. The magnetic response switch 3 is turned on in the sensitive area S1 and turned off in the insensitive area S2.

The support device 5 supports the non-magnetic case so that the non-magnetic case 1 maintains the horizontal position before the tilt when it is tilted. The illustrated supporting device 5 has a supporting case 51 and a bearing. The support case 51 has a volume capable of ensuring a necessary space between the support case 51 and the non-magnetic case 1, and contains the non-magnetic case 1. The bearing has a magnetic fluid 52,
The magnet 53 is attached to the bottom surface of the support case 51, and the magnetic fluid 52 includes the magnet 53.
3 and supports the non-magnetic case 1. Magnetic fluid 5
The number of bearings configured by 2 and the magnet 53 is preferably set to the number required for stable support of the non-magnetic case 1, for example, 3 to 4 sets.

As described above, the magnet 2 is disposed inside the non-magnetic case 1, is supported by the magnetic fluid 4, and floats on the inner surface of the bottom portion 101, and the magnetically responsive switch 3 responds to the position of the magnet 2. As described above, since the magnet 2 is disposed outside the bottom portion 101 of the non-magnetic case 1, when the magnet 2 receives an acceleration in the direction of arrow a or b, the magnet 2 is supported by the magnetic fluid 4 by its own inertia, It moves on the inner surface of the bottom portion 101 of the case 1 in the same direction a or b, and the relative position to the magnetically actuated switch 3 changes. When the magnet 2 moves from the sensitive area S1 to the insensitive area S2, the magnetic response switch 3 responds to the magnetic field of the magnet 2 to turn on or off, and the acceleration is detected.

Further, as shown in FIG. 2, the supporting device 5 is mounted because the object on which the acceleration sensor is mounted is inclined due to some cause such as ground subsidence or the mounting state of the acceleration sensor on the object is changed. When the support case 51 of FIG. 2 is inclined by the angle θ with respect to the horizontal direction, the support case 51 is subjected to the lubrication bearing action of the magnetic fluid 52 and the magnet 53, and the non-magnetic case 1 is kept at the same position as before the inclination. To slide. Therefore, the predetermined acceleration detection characteristic can be maintained without being affected by the inclination of the support device 5.

FIG. 3 is a diagram showing another embodiment of the acceleration sensor according to the present invention. In the figure, the same reference numerals as those in FIGS. 1 and 2 denote the same components. The support device 5 includes a support case 51 serving as a support and a suspension thread 54. The support case 51 contains the non-magnetic case 1, and the suspension thread 54 includes the lid 103 of the non-magnetic case 1 and the support case 51. It is connected to the lid. The hanging thread 54 can be composed of a metal wire or a non-metal wire.

Also in the case of this embodiment, the same basic acceleration detecting operation as that of the above-mentioned embodiment can be obtained. Further, as shown in FIG. 4, when the support case 51 of the support device 5 is tilted, the non-magnetic case 1 is hung by the hanging thread 54 and maintains the same horizontal position as before the tilt, so that the support device 5 is tilted. Acceleration can be detected without being affected.

FIG. 5 is a diagram showing still another embodiment of the acceleration sensor according to the present invention. The supporting device 5 is a supporting case 5.
A liquid 55 that serves as a bearing is provided inside the nonmagnetic case 1, and the nonmagnetic case 1 is floated by the liquid 55. As the liquid 55, a magnetic fluid or the like can be used in addition to various liquids. Also in this embodiment, the same basic acceleration detecting operation as in the above-described embodiments can be obtained. Also, as shown in FIG.
When the support case 51 of the support device 5 tilts, the non-magnetic case 1 receives the lubricating bearing action of the liquid 55 and maintains the same position as before the tilt, so that the acceleration is detected without being affected by the tilt of the support device 5. can do.

FIG. 7 shows still another embodiment of the acceleration sensor according to the present invention. The support device 5 includes a support 56 and a hanging thread 57. Also in this embodiment, the same basic acceleration detection operation as in the above-described embodiments can be obtained. Also,
As shown in FIG. 8, when the support case 51 of the support device 5 is tilted, the non-magnetic case 1 is hung by the hanging thread 57 and keeps the same position as before the tilt, and thus is affected by the tilt of the support device 5. Acceleration can be detected without

The supporting device 5 may have a structure in which it is supported by a spring in addition to the illustrated embodiment. It is also effective to add a damper mechanism as means for suppressing the swing of the non-magnetic case 1.

[0020]

As described above, according to the present invention, the following effects can be obtained. (A) The magnet is arranged in a non-magnetic case, is supported by a magnetic fluid, and floats above the inner surface of the bottom portion, so that the magnetically responsive switch responds to the position of the magnet.
Since it is located below the bottom of the non-magnetic case,
It is possible to provide an acceleration sensor that detects acceleration by relative movement of a magnet with respect to a magnetic response switch. (B) Since the support device supports the non-magnetic case so that the non-magnetic case maintains the horizontal position before the tilt when it is tilted, the object to which the acceleration sensor is attached is subsided, etc. Provided is an acceleration sensor capable of maintaining a predetermined acceleration detection characteristic without being affected by the inclination even when the supporting device is inclined due to inclination or a change in the mounting state of the acceleration sensor with respect to an object. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an acceleration sensor according to the present invention.

FIG. 2 is a diagram for explaining the operation of the acceleration sensor according to the present invention shown in FIG.

FIG. 3 is a diagram showing another configuration example of the acceleration sensor according to the present invention.

FIG. 4 is a diagram for explaining the operation of the acceleration sensor shown in FIG.

FIG. 5 is a diagram showing another configuration example of the acceleration sensor according to the present invention.

FIG. 6 is a diagram for explaining the operation of the acceleration sensor shown in FIG.

FIG. 7 is a diagram showing another configuration example of the acceleration sensor according to the present invention.

FIG. 8 is a diagram for explaining the operation of the acceleration sensor shown in FIG.

FIG. 9 is a plan view of a conventional acceleration sensor.

FIG. 10 is a partial cross-sectional view of a conventional acceleration sensor.

FIG. 11 is a plan view illustrating the operation of the conventional acceleration sensor.

[Explanation of symbols]

 1 Case 101 Bottom 2 Magnet 3 Magnetic Response Switch 4 Magnetic Fluid 5 Support Device

Claims (5)

[Claims] 1. An acceleration sensor having a non-magnetic case, a magnet, a magnetic response switch, and a support device, wherein the magnet is disposed in the non-magnetic case and is supported by a magnetic fluid to support the non-magnetic case. Floating on the inner surface of the bottom of the case, the magnetically responsive switch is disposed outside the bottom of the bottom so as to respond to the position of the magnet, and the support device is configured to be An acceleration sensor, wherein the non-magnetic case is supported so that the magnetic case maintains a horizontal position before being tilted. 2. The supporting device has a supporting case and a bearing, and the supporting case incorporates the non-magnetic case,
The acceleration sensor according to claim 1, wherein the bearing supports the non-magnetic case. 3. The acceleration sensor according to claim 2, wherein the bearing is liquid. 4. The bearing includes a magnetic fluid and a magnet, the magnet is attached to a bottom surface of the support case, and the magnetic fluid adheres to the magnet to support the non-magnetic case. The acceleration sensor according to claim 2, which is characterized in that. 5. The supporting device includes a support and a suspending thread, one end of the suspending thread is fixed to the support, and the other end is fixed to the non-magnetic case. The acceleration sensor according to claim 1.