JPS63201519A - Sensor - Google Patents

Abstract

PURPOSE:To improve detection accuracy by putting a permanent magnet formed of a columnar magnetic rigid body in the columnar space in a casing movably through lubricating oil and detecting displacement from a reference position. CONSTITUTION:The columnar magnetic rigid body 4 is put movably in the columnar case 2 made of a nonmagnetic body. A couple of ring-shaped permanent magnets 5a and 5b are fitted between small-diameter parts 42 formed at both end parts of the magnetic rigid body 4 and the case 2 while gaps 4 are left. The magnetic fluid 7 is charged as a lubricating material in the gaps. A transformer 9 and a permanent magnet 10 are provided to the outside center art of the case 2 and the primary coil 9a of the transformer 9 is connected to an AC constant voltage source. When the case 2 is horizontal, the rigid body 4 stays in the center of the magnetic rigid body 4 because of the magnet 10, but when the case slants, the rigid body 4 moves down until the gravitational force balance with the component of the magnetic force and the inclination is found from the difference voltage generated by a secondary coil 9b. Consequently, the detection accuracy is improved and the detection range is expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a sensor for detecting acceleration, inclination, etc.

(Prior Art) As a sensor for detecting acceleration, inclination, etc., the one disclosed in Japanese Utility Model Application Publication No. 61-38565, for example, has been developed by the present applicant.

This sensor has the following structure. A cylindrical storage space is formed inside the casing, and a hollow cylindrical magnetic rigid body is slidably accommodated in this storage space. Further, on the outside of the casing, there is a permanent magnet (magnetic field generating member) for attracting the magnetic rigid body to a predetermined reference position (the center in the longitudinal direction of the storage space), and a permanent magnet for detecting the displacement of the magnetic rigid body from the reference position. A differential transformer (detection member) for this purpose is arranged.

The principle when the above sensor is installed on the object to be measured and used as, for example, an inclination sensor is as follows.
When the object to be measured is tilted, the magnetic rigid body moves downward along the tilt direction from the reference position due to gravity against the magnetic force of the permanent magnet. By detecting the displacement of this magnetic rigid body as the output of the differential transformer, the degree of inclination of the object to be measured is detected.

(Problem to be solved by the invention) However, in the above sensor, the magnetic rigid body is hollow cylindrical and the absolute amount of magnetic material is small, so the number of generated magnetic flux is small and only a small differential output can be obtained. . As a result, detection accuracy was poor.

Furthermore, since the absolute amount of magnetic material is small, the attraction force of the permanent magnet is small, and the detection range is narrowed.

(Means for Solving the Problems) This invention has been made to solve the above problems, and its gist consists of a casing, a cylindrical storage space formed inside the casing, and a cylindrical storage space formed inside the casing. A magnetic body movably housed in a space, a magnetic field generating member for attracting the magnetic body to a reference position, and detecting the amount of electrical or magnetic change accompanying the displacement of the magnetic body from the reference position. In the sensor, the magnetic body is formed of a substantially cylindrical magnetic rigid body, and a lubricating liquid is provided in a radial gap between the inner surface of the casing that forms the outline of the storage space and the magnetic rigid body. The sensor is characterized in that:

(Function) Since the magnetic body is a substantially cylindrical magnetic rigid body, the absolute amount of magnetic material contained increases, and a large detection output can be obtained. As a result, detection accuracy is improved. Furthermore, as the absolute amount of magnetic material contained increases, the force of attraction by the magnetic field generating member also increases, and therefore the detection range also expands.

In addition, by placing the lubricant between the inner surface of the casing and the magnetic rigid body, the frictional resistance is reduced compared to when the casing and the magnetic rigid body are in direct contact, and the magnetic rigid body can move more easily, improving responsiveness. do. Furthermore, since each part of the storage space divided into two by the magnetic rigid body is substantially isolated from each other by the lubricating liquid, the Gumper effect works. Therefore, even when vibrations are applied to the object to be measured, there is no relative movement between the magnetic rigid body and the casing, and detection errors due to vibrations are eliminated.

(Example) Hereinafter, an example of the present invention will be described based on the drawing of FIG.

In the drawings, reference numeral 1 indicates a sensor, which is used as a tilt sensor in this embodiment.

The sensor 1 has a casing 2 consisting of a cylindrical portion 20 and closed end portions 21a and 21b, and a cylindrical storage space 3 is formed inside the casing 2 along the axial direction.

In the storage space 3, a cylindrical magnetic rigid body 4 is movably stored. The magnetic rigid body 4 has a large diameter portion 41 at the center, and small diameter portions 42 at both ends of the large diameter portion 41 in the axial direction. A pair of ring-shaped permanent magnets 5a, 5b is fitted into each small diameter portion 42 with a slight gap 6 in the axial direction. The permanent magnets 5 a and 5 b have a magnetic field gradient in the radial direction, and the permanent magnet 5 a has an N pole on the inside and an S pole on the outside, and the permanent magnet 5 b has an S pole on the inside and a N pole on the outside. It has become. Furthermore, each of the above permanent magnets 5 a, 5
A magnetic fluid 7 serving as a lubricant is magnetically attached to the radially outer side of b and the gap 6 by permanent magnets 5 a and S b.

The second magnetic fluid 7 has a ring shape and is in contact with the inner surface 2a of the casing 2 forming the outline of the storage space 3.

The magnetic fluid 7 is a colloidal liquid in which fine ferromagnetic particles are dispersed in a solvent, and the fine ferromagnetic particles do not precipitate or agglomerate even when a magnetic field is applied, and the appearance is that of the main liquid. It behaves as if it were magnetic.

Two transformers 9°9 (detection members) wound around a cylindrical bobbin 8 are fixed to the outside of the cylindrical portion 20 of the casing 2. The boundary between these transformers 9.9 is located at the axial center (reference position) of the storage space 3. Each transformer 9 includes an outer primary coil 9a and an inner secondary coil 9b.

A cylindrical permanent magnet 10 (magnetic field generating member) is arranged outside the transformer 9. The center of the permanent magnet 10 is located at the boundary between the two transformers 9, 9.

The casing 2, transformer 9, and permanent magnet 10 are housed and fixed in a housing (not shown).

Further, the transformer 9 is electrically connected to a mount roll unit (not shown) that includes an AC constant voltage generation circuit, a signal processing circuit, and the like.

The primary coil 9a of each transformer 9 is connected to the AC constant voltage generation circuit of the control unit, and the differential output of both secondary coils 9b is detected by the signal processing circuit, and the control unit) Connected display (
(not shown) is digitally displayed as the degree of inclination.

The casing 2 and bobbin 8 are made of non-magnetic material, and the housing is made of soft magnetic material.

A case will be described in which the sensor 1 having the above-mentioned configuration is attached to an object to be measured and the degree of inclination of the object to be measured is detected.

When the object to be measured maintains a horizontal posture, the magnetic rigid body 4 is attracted by the magnetic force of the permanent magnet 10 and comes to rest at a reference position, which is the boundary between the transformers 9 . Therefore, the differential output of the secondary coils 9b of both transformers 9 becomes zero, and the signal processing circuit of the Huntroll unit converts the differential output into a digital signal and sends it to the display, which displays the zero value. Display digitally.

When the object to be measured is tilted to either the left or right in FIG. 1, the magnetic rigid body 4 moves downward along the slope due to gravity and comes to rest at a position where gravity and magnetic force are balanced. That is, the axial component of the storage space 3 of the force due to gravity acting on the magnetic rigid body 4 and the axial component of the storage space 3 of the magnetic force acting between the magnetic rigid body 4 and the permanent magnet 10 are balanced. The magnetic rigid body 4 stands still at this position.

When the magnetic rigid body 4 moves, the magnetic fluid 7 is always magnetically attracted to the permanent magnets 5 a and 5 b and is always interposed between the magnetic rigid body 4 and the inner surface 2 a of the casing 2. The magnetic fluid 7 functions as a lubricant without directly contacting the inner surface 2a of the casing 2. Therefore, the magnetic rigid body 4 can move smoothly with small frictional resistance.

Further, since the magnetic fluid 7 is interposed in the radial gap between the magnetic rigid body 4 and the inner surface 2a of the casing 2, the storage space 3 is substantially divided by the magnetic rigid body 4 and the magnetic fluid 7 and isolated from each other. Ru. As a result, a damper acts on the magnetic rigid body 4, and even if vibration is applied to the object to be measured, the magnetic rigid body 4
There is no relative movement between the casing 2 and the casing 2, and detection errors due to vibrations do not occur.

The magnetic flux in each transformer 9 changes due to the displacement of the magnetic rigid body 4. In this case, since the magnetic rigid body 4 has a solid cylindrical shape and contains a large absolute amount of magnetic material, the amount of change in magnetic flux is extremely large.

This change in magnetic flux causes a large change in the inductance of the transformer 9, producing a large differential output between the secondary coils 9b, 9b. This differential output is digitally displayed as a slope as a positive or negative value on a display.

In this way, a large differential output is obtained, so sensor 1
Detection accuracy is improved.

In addition, the magnetic rigid body 4 has a large absolute amount of magnetic material, and because it is cylindrical and the magnetic path formed between it and the permanent magnet 1O is short, the force of attracting the magnetic rigid body 4 by the permanent magnet 1O is increased. increases, so the detection range of the sensor 1 can be expanded.

Furthermore, since the cross section of the magnetic rigid body 4 perpendicular to the axial direction has a circular shape with almost the same diameter over its entire length, the correlation between the displacement of the magnetic rigid body 4 and the differential output can be expressed as a straight line. It can be brought closer.

This simplifies the signal processing for displaying the differential output on the display.

The sensor 1 can be used not only for detecting inclination but also for detecting acceleration. In this case, the magnetic rigid body 4 is moved in the direction opposite to the acceleration direction by receiving an inertial force.

Figures 2 and 3 show other embodiments, and the differences from the first embodiment described above will be explained below, and the same reference numerals will be given to the same parts as in the first embodiment, and the explanation will be omitted. do. The casing 2' of the sensor 1' in this embodiment is made of an insulating material. On the outside of this casing 2', in place of the transformers 9, 9, capacitors 9', 9' each formed by a pair of semi-cylindrical electrode plates 91, 92 facing each other with the casing 2' in between are arranged. There is. These capacitors 9' and 9' are arranged side by side with a slight gap in the axial direction, and the center of this gap is at the reference position (casing 2
’ (center in the axial direction).

In the case of the sensor 1', the dielectric constant changes due to the movement of the magnetic rigid body 4, and as a result, the capacitance of the capacitors 9' and 9' changes. The degree of inclination of the object to be measured is detected based on this change in capacitance.

This invention is not limited to the above-mentioned embodiments, and various embodiments are possible.

For example, the outer peripheral surface of the magnetic rigid body may be provided with slight irregularities, and the magnetic rigid body may be provided with an orifice extending in the axial direction in order to adjust the vibration absorption characteristics due to the damper effect.

In addition, a variable electromagnetic coil is used as the magnetic field generating member, and an output signal based on a change in inductance or a change in capacitance is fed back to the electromagnetic coil, so that the electromagnetic filter is adjusted so that the magnetic rigid body is always located at the reference position. The inclination and acceleration may be detected by controlling the supply voltage and detecting this supply voltage.

(Effects of the Invention) As explained above, according to the present invention, the detection accuracy is improved by making the magnetic body into a substantially cylindrical magnetic rigid body.
Detection range is expanded.

Further, by disposing the lubricating liquid in the radial gap between the magnetic rigid body and the inner surface of the casing, the magnetic rigid body can move easily, and detection errors due to vibrations are eliminated.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view of a sensor according to one embodiment of the present invention, FIG. 2 shows a cross-sectional view of a sensor according to another embodiment, and FIG.
The figure is a sectional view taken along line 2 in Figure 2. 1...Sensor, 2...Casing, 2a...
Inner surface of casing, 3... Storage space, 4... Magnetic rigid body, 7... Lubricating fluid (magnetic fluid), 9.9'...
- Detection member, 10... Magnetic field generation member.

Claims (2)

[Claims] (1) a casing, a cylindrical storage space formed inside the casing, a magnetic material movably stored in the storage space, and a magnetic field generating member for attracting the magnetic material to a reference position; and a detection member that detects an amount of electrical or magnetic change accompanying displacement of the magnetic body from the reference position, wherein the magnetic body is formed of a substantially cylindrical magnetic rigid body, and the magnetic body is formed of a substantially cylindrical magnetic rigid body; A sensor characterized in that a lubricating liquid is disposed in a radial gap between the inner surface of the casing forming the outline of the space and the magnetic rigid body. (2) The sensor according to claim 1, wherein the lubricant is a magnetic fluid.