JPH02245668A - Acceleration sensor - Google Patents

Abstract

PURPOSE:To detect acceleration at a high sensitivity by arranging a bias magnet wrapping a spherical magnet for movement with a magnetic fluid. CONSTITUTION:A magnetic fluid 3 is attached wrapping a spherical permanent magnet 2, housed in a chamber 5 which is made of non-magnetic material with a smooth concave curved surface as bottom surface thereof and a permanent magnet 6 for biasing is arranged on a symmetrical axis of the chamber 5 to build an acceleration sensor 1. Here, while no acceleration is applied to the sensor 1, the magnet 2 is positioned at on the bottom of the chamber 5 and a magnetic field generated with the magnet 2 passes through a reed switch 9 to activate. Then, when an acceleration alpha is applied to the sensor 1, the magnet 2 moves and a magnetic fluid 3 keep a liquid lubrication between the magnet 2 and the bottom surface of the chamber 5. At this point, the magnet 2 is turned under the influence of the magnet 6 so that the magnetic field of the magnet 2 separates from the switch 9 to deactivate. Thus, acceleration can be detected by checking a change in the magnetic field of the magnet 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an acceleration sensor that detects acceleration caused by movement of an object.

Conventional technology Conventionally, as an acceleration sensor, Japanese Patent Application Laid-Open No. 63-18615
The one shown in Publication No. 0 was known. In this system, a magnetic ball placed in a magnetic fluid (or damper liquid) is attracted to the center of the storage space by a magnetic field generating member, and the movement of the magnetic rigid body due to changes in the acceleration of the moving object is suppressed by placing the magnetic sphere in such a way as to sandwich the magnetic rigid body. It was detected as a change in capacitance between ti and blank plates.

Problems to be Solved by the Invention However, in the above configuration, solid contact friction occurs in the magnetic sphere, which poses a problem in detection sensitivity.

Means for Solving the Problems In the present invention, a spherical moving magnet to which a magnetic fluid is attached is enclosed in a non-magnetic container, and a bias magnet for applying a magnetic field from outside the container is disposed. An acceleration sensor is provided with a magnetic detection element for detecting changes in the magnetic field of the moving magnet.

Effect With the above-described configuration, the moving magnet is arranged in a state of fluid lubrication with the container via the magnetic fluid, and when acceleration is applied to this acceleration sensor, the moving magnet is transferred under the influence of the bias magnet, and this A magnetic sensing element detects changes in the magnetic field to detect acceleration. Sensitivity adjustment at this time is obtained by the magnetic force exerted by the bias magnet on the moving magnet.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2.

In FIG. 1, 1 is an acceleration sensor. 2 is a spherical permanent magnet, with one hemisphere magnetized as a north pole and the other hemisphere as a south pole. 3 is a magnetic fluid attached to the birch tree that holds this magnet. This magnet 2 has a main body 4 made of non-magnetic material.
It is arranged in a chamber 5 having an axially symmetrical smooth concave curved surface as a bottom surface. Reference numeral 6 denotes a bias permanent magnet arranged on the symmetry axis of the chamber 5. The magnet 6 and the magnet 2 have a birch polar arrangement that attracts each other. The magnet 6 is pressed downward by a spring 7, and its position can be adjusted by a screw 8.

9 is a reed switch placed above the magnet 2;
It is arranged close to the magnet 2 and detects changes in its magnetic field. 10.11 is a lead wire of the reed switch 9.

Next, we will discuss the operation.

FIG. 1 shows a state in which no acceleration is applied to the acceleration sensor 1, and a magnet 2 is surrounded by a magnetic fluid 3 in a chamber 5.
It is located at the bottom of the concave curved surface. At this time, the magnetic field generated by the magnet 3 crosses the reed switch 9, so the reed switch 9 is working.

Next, FIG. 2 shows a state in which acceleration is applied to the acceleration sensor 1. At this time, the magnet 2 moves in the opposite direction with acceleration α. Since the magnetic fluid 3 is attached around the magnet 2, the magnet 2 and the bottom surface of the chamber 5 maintain a state of fluid lubrication, and the magnet 2 is moved sensitively to applied acceleration. At this time, magnet 2 becomes NF due to the influence of magnet 6.
The transfer is made in such a state that i is close to the S pole of the magnet 6. As a result, the magnetic field of the magnet 2 moves away from the reed switch 9, so the reed switch 9 stops working.

The magnet 6 gives a magnetic bias effect to the magnet 2, and by adjusting the screw 8, when the magnet 2 is brought closer to the magnet 6, the effect of dulling the sensitivity occurs, and when it is moved away, the effect of sharpening the sensitivity is generated. Occur.

Next, a second embodiment will be explained with reference to FIGS. 3 and 4.

Of the 7 items in Figure 3, those with the same numbers as in Figure 1 have the same structure and structure.
It has the ability of a. The difference is that the bias permanent magnet 6 in FIG. 1 is replaced by an electromagnet 12. The electromagnet 12 has a core 13. It consists of magnets 114 and 15 and a coil 16. 17.18 is coil 16
This is the lead wire. In this case, when the coil 16 is energized, a ladder configuration is formed in which the magnet 1114 becomes the south pole and the magnetic pole 15 becomes the north pole.

In Fig. 4, 19 is a DC power supply, 20 is a switch, 2
1 is a variable resistance.

Next, the operation will be described.

When switch 20 is turned on, voltage is applied to coil 16. At this time, in the electromagnet 12, the magnetic pole 14 becomes the S pole and the magnetic pole 15 becomes the N pole, so the effect on the magnet 2 is similar to that of the magnet 6 in the first embodiment. As a result, acceleration sensor 1
The operation when acceleration is applied to is the same as in the first embodiment.

In this case, the strength of the magnetic field applied to the magnet 2 is adjusted by controlling the amount of current applied to the coil 16 by operating the variable resistor 21.

Effect of the invention According to the present invention, the keyaki described above has the following effects.

(1) By forming the moving magnet into a spherical shape, surrounding it with magnetic fluid, and arranging a bias magnet, the direction of the magnetic field of the moving magnet can be easily directed away from the reed switch, and the direction of the magnetic field of the moving magnet can be easily moved away from the reed switch. Since the contact with the surface can be set to a state of fluid lubrication, it is possible to detect acceleration with high sensitivity.

(2) Detection sensitivity can be adjusted by configuring the bias magnet to be movable.

(3) By making the bias magnet an electromagnetic structure,
Since the detection sensitivity can be adjusted without using any moving parts, finer and more reliable acceleration detection is possible.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of an acceleration sensor according to an embodiment of the present invention, FIG. 2 is a diagram showing a different operating state from FIG. 1, and FIG. 3 is a vertical sectional view of another embodiment of the present invention. FIG. 4 is a circuit diagram for controlling the electromagnet shown in FIG. 3. 1... Acceleration sensor, 2... Moving magnet, 3... Magnetic fluid, 5... Chamber, 6...
...Bias magnet, 9...Reed switch (magnetic detection element), 12...Electromagnet. Name of agent: Patent attorney Shigetaka Awano and 1 other person! ...Large 1: It/l Zemp 6-...Mouse

Claims (3)

[Claims] (1) A spherical moving magnet to which a magnetic fluid is attached is enclosed in a chamber having a concave curved surface, and a bias magnet that applies a magnetic field is placed in the chamber, and the magnetic field of the moving magnet is An acceleration sensor equipped with a magnetic sensing element that detects changes. (2) The acceleration sensor according to claim (1), wherein the bias magnet is a permanent magnet. (3) The acceleration sensor according to claim (1), wherein the bias magnet is an electromagnet.