JPS63153473A - Acceleration detector - Google Patents

Abstract

PURPOSE:To eliminate mechanical wear, etc., by composing coil assemblies of detection coils which detect the displacement of a magnetic spherical body and ferromagnetic fluid and exciting coils which apply constant magnetic fields to the detection coils, and holding the spherical body in the center of a container by holding coils. CONSTITUTION:Coil assemblies 4 and the inverse of 4, and 4A and the inverse of 4A are composed of couples of detection coils which detect variation in magnetic resistance due to the position shift of the magnetic spherical body 3 and exciting coils which apply constant magnetic fields to the detection coils. The holding coils 5 and the inverse of 5, and 5A and the inverse of 5A are arranged distantly from the coil assemblies respectively and hold the magnetic spherical body 3 by excitation. A G sensor supplies the constant magnetic fields to the detection coils during operation by the exciting coils and detect the variation in the magnetic reluctance of a magnetic circuit due to the displace ment of the magnetic spherical body and magnetic fluid caused on the center axis in the presence of parallel acceleration differentially by the detection coils to detect the direction and magnitude of the acceleration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an acceleration detection device (hereinafter referred to as a G sensor) that is mounted on various types of machines, such as vehicles and robots.

[Conventional technology]

In conventional G sensors, a pendulum hole or ball type is used. Acceleration is detected using this pendulum or pole as an effector of total acceleration.

[Problem that the invention seeks to solve]

Since the conventional G sensor is constructed as described above, the effecting body is quite heavy, large and large, and there is a mechanically worn part, so the wear of this part becomes more noticeable as the weight of the effecting body increases. As a result, the service life is significantly shortened, and furthermore, the structure requires multiple servings, making it difficult to reduce the size and weight, and making it expensive.

This invention was made to solve the above-mentioned problems, and aims to provide a G sensor that has a simple structure and can detect acceleration in a non-contact manner.

[Means for solving problems]

The G sensor according to the present invention has a magnetic sphere suspended in a ferromagnetic fluid, and has a detection coil and an excitation coil assembled on both sides of a closed container enclosing the ferromagnetic fluid on the central axis of the container. 4 coil assemblies and 4 holding coils are arranged.

[For production]

The G sensor according to the present invention differentially detects a change in magnetic resistance of a magnetic circuit caused by a displacement caused by an excitation coil (using a detection coil), and detects the direction and magnitude of the acceleration.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1~! FIG. 3 is a front view showing an embodiment of the present invention. In the figure, 1 is a closed container made of non-magnetic material, 2
is a ferromagnetic fluid sealed in this closed container 1, and 3 is a magnetic sphere placed in a floating state in this ferromagnetic fluid 2.

4, 4, 4A, 4A are arranged on two sides of the closed container 1, for example, on the two orthogonal left and right and upper and lower central axes X- and Y-Y of the closed container 1, and A set of four coils each consisting of four detection coils that detect changes in magnetic resistance due to position changes and four excitation coils that are connected to a power source (not shown) and provide a constant magnetic field to the detection coils. It is the body. 5.5.5A.

Similarly, the magnetic sphere 3 is arranged separately from the coil assemblies 4, 4, 4A, and τi on the central axes X-X and Y-Y, and is connected to a power source (not shown) for excitation. There are four holding coils to hold the

It is assumed that the G sensor having the above configuration is mounted on a vehicle, for example.

Next, the operation will be explained. Normally, when there is no acceleration when no acceleration G is acting, the magnetic force of the four holding coils 5.5° 5A, 5A generated by energization and the buoyant force received from the ferromagnetic fluid 2 are applied as shown in Figure 1. The magnetic sphere 3 is held at the center of the closed container 1. For this reason,
Coil assembly on x-x, y-Y axis 4.4, 4A, 4
The magnetic circuit of the detection coil A is completely symmetrical, sb, and its magnetic resistance is equal, so the differential output of the detection coils of the coil assemblies 4, 4, 4A, and 4A on the X-X and Y-Y axes is as follows. It becomes zero.

Next, when a force of G acts parallel to the central axis X, for example in the right direction, the magnetic sphere 3 is displaced in a direction opposite to the direction of G, as shown in FIG. As a result, on the left side of the figure, the density of the ferromagnetic fluid 2 decreases, so the magnetic resistance in the magnetic circuit on the detection coil side of the left coil assembly 7 increases, and the magnetic resistance in the magnetic circuit on the detection coil side of the right coil assembly 4 increases. Resistance F
it-i hardly ever changes. Therefore, both coil assemblies 4
．． Since a magnetic field is applied to each of the above-mentioned magnetic circuits due to the excitation of the excitation coil 7.4, a differential output voltage due to the induced voltage difference is generated in the detection coil of the above two coil assembly 7.4 due to electromagnetic induction. arise. Since this differential output voltage is proportional to the amount of displacement of the ferromagnetic fluid 2 due to the amount of displacement of the magnetic sphere 3, the magnitude of G in the left/right direction depends on this differential output voltage. can be detected, and the direction of G can also be detected from its polarity.

Further, when G is applied parallel to the central axis Y-Y, for example in an upward direction, the magnetic sphere 3 is displaced downward in the opposite direction to the G direction, as shown in FIG. As a result, the density of the ferromagnetic fluid 2 in the downward direction decreases, the magnetic resistance in the magnetic circuit on the detection coil side of the lower coil assembly 4A increases, and the magnetic resistance in the magnetic circuit on the detection coil side of the lower coil assembly 4A increases.
The magnetic resistance in the magnetic circuit on the detection coil side hardly changes. Therefore, since a magnetic field is applied to each magnetic circuit by the excitation of the excitation coils of both coil assemblies 4A, 4A, a differential output voltage is generated in the detection coils of both coil assemblies 4A, 4A due to the induced voltage difference. arise. G in the horizontal (up/down) direction can be detected depending on the magnitude of the differential output voltage between the
The direction of G can be detected depending on its polarity. Thus, in this example, the G
This is how the sensor is realized.

In the above embodiment, it is desirable that the magnetic permeability of the ferromagnetic fluid 2 is approximately 10 times or more greater than the magnetic permeability of the magnetic spheres 3.

4 to 6 are front views showing a second embodiment of the present invention. In the figure, the feature is that only the surface layer of the magnetic sphere 3 is made entirely of magnetic material in order to reduce the total weight of the magnetic sphere 3 and reduce the impact of the magnetic sphere 3 on the inner wall surface of the sealed container 1. 3a, and the inside thereof is made of a light material 3b such as a non-magnetic light metal (for example, aluminum) or plastic. Since the other configurations and operations are the same as those in the first embodiment, the explanation thereof will be omitted entirely.

7 to 9 are front views showing a third embodiment of the present invention. In the figure, the feature of this embodiment is that a cushion member 6, such as rubber, is provided on a part of the inner wall surface of the closed container 1 against which the magnetic sphere 3 collides. 100, 6A, and 6A are provided on all sides to improve the durability of the G sensor.

Other components and operations are the same as in the first embodiment.

〔Effect of the invention〕

As described above, according to the present invention, a magnetic field is applied to the detection coil by the excitation coil, the ferromagnetic fluid and the magnetic sphere therein are displaced under the action of acceleration, and the detected value by the detection coil is determined by the displacement. Since it is configured to produce an output difference between the two, it is structurally simple and can be made smaller and lighter, with fewer parts and lower costs.Since it is non-contact detection, it is highly reliable and prevents mechanical wear and deterioration. □There is an effect that a product with improved durability can be obtained without causing any damage.

[Brief explanation of the drawing]

1 to 3 are front views in each state showing a first embodiment of the invention, FIGS. 4 to 6 are front views in each state showing a second embodiment of the invention, and FIGS. FIG. 9 is a front view of the third embodiment of the present invention in various states. In the figure, l is a closed container, 2 is a ferromagnetic fluid, 3 is a magnetic sphere,
4, 4, 4A, TI is a coil assembly, 5°T, 5A, 5
is a holding coil. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (4)

[Claims] (1) An airtight container made of a non-magnetic material, a ferromagnetic fluid sealed in the airtight container, a magnetic sphere suspended in the ferromagnetic fluid, and orthogonal central axes of the airtight container. A detection coil arranged on two sides of the closed container on a line and configured to detect the displacement of the magnetic sphere or ferromagnetic fluid under the action of acceleration, and an excitation coil for applying a constant magnetic field to the detection coil. An acceleration detecting device comprising four coil aggregates having a magnetic sphere and four holding coils for holding the magnetic sphere at the center of the closed container by excitation during normal times. (2) The acceleration detection device according to claim 1, wherein the magnetic permeability of the ferromagnetic fluid is approximately 10 times or more greater than the magnetic permeability of the magnetic sphere. (3) The acceleration detection device according to claim 1, wherein only the surface layer of the magnetic sphere is made of a magnetic material. (4) Claim 1, wherein a part of the inner wall of the airtight container is made of a cushion member.
Acceleration detection device described in Section 2.