JPH02163615A - Position sensor - Google Patents

Abstract

PURPOSE:To simplify the constitution so that a small installation space is enough, and also, to simplify the manufacturing process by constituting the sensor of a magnetostrictive body, an exciting means, a magnetic field applying means and a detecting means. CONSTITUTION:A position sensor 1 detects a position of a moving body, etc., by using a linear magnetostrictive body 2 extended and provided in the direction as indicated with arrows A, B so that a magnetic elastic wave generated by applying an external magnetic field is propagated. A permanent magnet 9 being a magnetic field applying means is attached as one body, for instance, to a moving body, etc., provided so as to be movable in the longitudinal direction of the magneto strictive body 2, and can move along the magnetostrictive body 2 in a state being adjacent to the magnetostrictive body 2. An exciting coil 5 is connected to a driving circuit 7 for applying a pulse current, and constitutes an exciting means for generating a magnetic elastic wave together with the driving circuit 7. A detecting coil 6 is a detecting means for detecting the magnetic elastic wave which is reflected and returned, and connected to a signal processing circuit 8 for processing an induced detecting signal. According to this constitution, the number of parts can be decreased, and also, the manufacturing process can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to position sensing, and in particular to a position sensor configured to be able to measure any position of a moving snow object by detecting magnetoelastic waves propagating through a magnetostrictive body. Regarding tnza.

2. Prior Art As a conventional position sensor, for example,
There is one shown between Publication No. 884 and Publication J.

The position sensor 9 of this publication includes a flat magnetostrictive plate provided with excitation means for generating ultrasonic signals, a flat printed board disposed parallel to the magnetostrictive plate, and a position sensor 9 that can move on the printed board. It is roughly composed of a magnet. This position sensor 9 detects the position of the magnet, and when a pulse current is passed through the excitation coil, an ultrasonic signal is generated at one end of the magnetostrictive plate due to the magnetostrictive effect, and this is transmitted toward the other end. It will spread. When this ultrasonic signal passes through the magnet, the magnetic permeability of the magnetostrictive plate changes due to the Villery effect, and the magnetic flux given by the magnet changes. As a result, an induced voltage is generated in the zigzag conductor formed on the pudding mill plate. Since this induced voltage curve changes depending on the positional relationship between the zigzag-shaped conductor and the magnet, the position of the magnet is expanded based on the above-mentioned induced voltage.

Problems to be Solved by the Invention However, in the above-mentioned position sensor, not only a flat magnetostrictive plate but also a flat blind plate must be disposed parallel to the magnetostrictive plate, and the number of valve parts is large. There is a problem that a larger 5H space is required when installing at a predetermined installation location. In addition, in the first step of manufacturing, the length of the magnetostrictive plate and printed board must be adjusted according to the intended use or installation location, which adds up to an additional 40% of manufacturing time and effort. There are also challenges.

Therefore, an object of the present invention is to provide a position sensor that solves the above problems.

Means and Effects for Solving the Problems The present invention provides a magnetostrictive body which is extended to allow magnetic waves to propagate, an excitation means for generating magnetoelastic waves in the magnetostrictive body, and It consists of a magnetic field applying means provided so that it can be approached at any position, and a detecting means for detecting the arrival of a magnetoelastic wave that is inconsistent with the magnetic field application site by the magnetic field applying means, reducing the number of parts and installing it. It takes up less space and simplifies the time and effort required to make the culm.

Embodiment FIG. 1 shows a first embodiment of the position sensor 4) according to the present invention.

In Figure 1, the attached sensor 1 is the input external magnetic field Erl jl
left and right directions (
A linear magnetostrictive body 2 extending in the direction of arrows A and B)
is used to detect the position of the moving mackerel. This magnetostrictive body 2 can be fabricated using, for example, a rotating liquid spinning method (Japanese Unexamined Patent Publication No. 15-64).
This is a Fe-8i-B di-crystalline magnetic fI line produced in an extremely thin line by the manufacturing method called ``BJ method'' (see Japanese Patent Publication No. 91). This magnetostrictive body 2 has the characteristic that magnetic valve +71 waves propagate, and is formed into an extremely thin wire, so it requires a small installation space and can be arranged not only in a straight line but also in a curved or bent shape. You can also do that. In FIG. 1, the magnetostrictive body 2 is shown stretched in a straight line in order to facilitate understanding of the present invention.

Both pant portions of the magnetostrictive body 2 are held by holders 3 and 4. Holder 3.4G;L The magnetoelastic wave propagating through the magnetostrictive body 2 is reflected, and holds the magnetostrictive body 2 as shown in 1.

In addition, as a holding method using such a holder 3.4,
It is known that magneto-elastic waves can be reflected and maintained by applying a suitable liquid via a rubber-like substance.

An excitation coil 5 is wound near the end of the magnetostrictive body 2, and the excitation coil 5 has a dimension e. A detection coil 6 is wound at a spaced apart position. The excitation coil 5 is connected to a drive circuit 7 for applying a pulse current, and together with this drive circuit 7 constitutes an excitation means for generating a magnetic valve wave.

Further, the detection coil 6 is a detection means for detecting the magnetoelastic waves reflected and returned, and is connected to a signal processing circuit 8 for processing the detection signal induced in the detection coil 6. Excitation coil5. The detection coil 6 is largely fixed to the magnetostrictive body 2.

9 is a permanent magnet as a magnetic field applying means, for example, magnetostrictive body 2
1, which is integrally attached to a movable ring that is movably provided in the longitudinal direction of the magnetostrictive body 2 and can move along the magnetostrictive body 2 while remaining close to the magnetostrictive body 2. The head sensor 1 that detects the displacement position includes a magnetostrictive body 2, an excitation coil 5, a detection coil 6, a drive circuit 7, a signal processing circuit 8.
It is roughly composed of permanent magnets 9 and the like. Therefore, unlike the conventional position sensor, the sensor 1 does not require the printer 1 to the plate, so the number of parts is reduced and the configuration is simplified.

Therefore, since the position sensor 1 requires a small installation space, it can be easily installed regardless of the installation location.It can also be easily manufactured in an artificial culm.

The principle of position detection of the position sensor 1 is as follows.

That is, the generation and detection of magnetic valve fl waves in the magnetic material of the magnetostrictive body 2 is based on the mechanism described below.

When a magnetic field is applied to a part of a magnetic material using a coil, etc.,
Along with this change, the magnetization changes according to the magnetization curve. This change in magnetization causes magnetostriction, and this strain propagates through the magnetic material as an elastic wave, which is called magnetoelasticity. It's a wave. 1 Conversely, when magnetoelastic waves exist in a magnetic material, they cause a change in magnetization due to the distortion (Villeri effect) associated with the magnetoelastic waves, and this change in magnetization changes the surrounding magnetic field.
Magnetoelastic waves can be detected by detecting changes in this magnetic field using a coil or the like.

Magnetic materials such as C wire and ribbon 1. If you use a long and narrow root shape, the propagation path will be one-dimensional, so you can know the distance from the propagation time. It is also known that when a magnetic field is applied to a part of a magnetic material, part of the magnetoelastic waves are reflected at that part. , the phenomenon GJ in which magnetoelastic waves are reflected at the second magnetic field application site has already been confirmed through experiments.

Therefore, in the present invention, the magnetoelastic wave is provided so as to be close to the magnetostrictive body 2, and the position of the permanent magnet 9 is detected by measuring the time it takes for the magnetoelastic wave to be reflected by the magnetic field application part 17 of the IS permanent magnet 9 and returned. Specifically, in FIG. 1, a pulse current]o is applied to the excitation coil 5 by the operation of the drive circuit 7 as shown in FIG. 2(a). Then, a magnetoelastic wave is generated from the part of the magnetostrictive body 20 around which the excitation coil 5 is wound, and propagates toward both ends of the magnetic f body 2 4 and toward the boulder 4 side (left side in FIG. 1). When the propagated magnetoelastic wave reaches the winding position of the detection coil 6, the detection coil 6
As shown in FIG. 2(b), a detection pulse P+ is induced.

Furthermore, the magnetoelastic wave propagates toward the boulder 4 side, and the permanent magnet 9
Reach a position opposite to. Since this portion is magnetized by the magnetic field from the permanent magnet 9, a portion of the magnetoelastic wave is reflected as described above. The magnetoelastic waves thus reflected propagate to the left in FIG. 1 and return to the winding position of the detection coil 6. When the reflected magnetoelastic wave reaches the detection coil 6, it generates a detection pulse P2 as shown in FIG. 2(b).

The signal processing circuit 8 receives the detection pulse P+.

P is manually input from the detection coil 6, and the signal processing circuit 8 calculates the time t2 between the detection pulses P1 and P2.
Furthermore, the distance t between the detection coil 6 and the permanent magnet 9 is calculated based on the relationship between the I18 interval t2 and the previously measured propagation speed of the magnetoelastic wave. In addition, as another calculation method exclusively for this distance mp-, there is also the following method.

That is, the distance Hp-o between the excitation coil 5 and the detection coil 6
Measure in advance. The time t1 between the detection pulses Po and Pl is 111ft. Corresponding to this, the time t2 between the detection pulses PI and P2 is equal to the distance Mp-, that is, 2
Corresponds to 48. Therefore, t = (1/2) XL
The distance of 5° between o x (t2/l:+) and 4 is the propagation time of the magnetoelastic wave. ．． 3. When this discharge method is executed in the signal processing circuit 8, the distance history can be calculated based on the times t+ and t2. The distance t can be determined without being affected by temperature changes in the magnetoelastic wave propagation speed in the magnetoelastic wave, and changes in the magnetoelastic wave propagation speed due to temperature changes are compensated for.

In addition, as described in 1-, the magnetostrictive body 2 through which the magnetoelastic waves propagate is 1
The material is not limited to the one obtained by processing the A crystalline magnetic material into a linear shape, but any material may be used as long as it has a large magnetostriction, easily generates magnetoelastic waves, and is easy to detect Fa magnetoelastic waves.

Further, the magnetostrictive body 2 is not limited to a wire, but may be a ribbon or a plate.

Further, in the first description, it is assumed that a pulse current is applied to the excitation coil 5, but the present invention is not limited to this, and of course, for example, a pulse current may be applied to the excitation coil 5. Further, as another means for emitting magnetoelastic waves in a magnetostrictive body, for example, a piezoelectric material may be used. Further, in the first embodiment, a permanent magnet 169 is used as the magnetic field applying means, but the present invention is not limited to this, and the same effect can be obtained even if an electromagnet is used, for example.

FIG. 3 shows a second embodiment of the invention. In FIG. 3, the position sensor 4J11 includes a magnetostrictive body 12, a coil 13 wound around the magnetostrictive body 12, and a drive/signal processing circuit 14 to which the coil 13 is connected. The drive/signal processing circuit 14 has both the functions of the drive circuit and the signal processing circuit shown in FIG. 1. Zemotsu.

Further, a holder 151J that holds the end portion 12b8 of the magnetostrictive body 12
, has a different configuration from the holder 3.4, and holds the magnetostrictive body 12 from which magnetoelastic waves can be reflected. UIJ! When an h-force force is applied to a magnetostrictive body through a material made of material, magnetoelastic waves are reflected at that part. Further, even if no special holding is performed, reflections occur at the ends of the magnetostrictive body.

Here, with reference to FIGS. 3 and 4, the position sensor 1
The first position detection operation will be explained.

As shown in FIG. 4(a), a pulse current P is applied to the coil 13 by the operation of the drive/signal detection circuit 14. is supplied,
A magnetic field 13J and 13J is applied to the magnetostrictive body 12.

In this way, a part of the magnetoelastic wave propagating through the magnetostrictive body 12 in the direction of arrow B is reflected at the magnetic field application section from the permanent magnet 9, and the magnetoelastic wave also reaches the holder 15, where it is reflected. Return to the 13th turn section. Since the coil 13 also functions as a detection coil, the permanent magnet 9 as shown in the fourth (J<b)
A detection pulse P+ of the magnetoelastic wave reflected at the position of and a detection pulse P2 of the magnetoelastic wave reflected at the position of the holder 15 are output.

The drive/signal processing circuit 14 measures the time t+, t2 from when the pulse current Po is generated until the detection pulses P+, P2 are (q), and from this time t1 and the magnetic propagation speed, the permanent magnet 9 , that is, the distance from the first coil 13 to the permanent magnet 9.Also, the distance history can be obtained by other methods.
4. The distance 111L between the circular portion and the end portion 12b is measured in advance. Then, V8 f1itj21. between the pulse current Po and the detection pulse P2. Corresponding to J distance #1-2-8,
The time t1 between the pulse current P and the detection pulse P+ corresponds to twice the distance fltp-. Therefore, the distance 11tt between the coil 3 and the permanent magnet 9 is t=:LX(t+/1
2) Find F.

In this case, since the distance Mp- can be calculated from the times t+ and t2, temperature changes in the propagation speed of the magnetoelastic wave can be compensated for even in an environment with temperature changes. Therefore, position sensor 4
j11 i The position of the permanent magnet 9 can be accurately measured regardless of temperature changes 9° Also, when determining the position of the permanent magnet 9, use the winding portion of the coil 13 as a reference and the end portion 12b as a reference. You can also do it. In that case, the drive/signal processing circuit 14 uses the detection pulses P1 and P1.
2. Calculate the position of the permanent magnet 9 based on the time t3.

A third embodiment of the present invention is shown in FIGS. 5 and 6.

FIG. 5 shows a liquid level sensor 21 that detects the level position of the liquid stored in the tank. This liquid level sensor 2
1 is a modification of the position sensor υ invented by Moeki. Further, the liquid level sensor 21 can detect the liquid level even when the liquid level fluctuates or tilts, and is suitable for use as the remaining portion 4 of a fuel tank of an automobile, for example.

The liquid level sensor 21 is a protection tube 22 in which a linear magnetostrictive body is housed.
and a first float 23. which is inserted into the protective tube 22 and is slidably provided in the manual force direction. The 1° protection tube 22, which is roughly composed of a second float 24 and a case 25 provided at the end of the protection tube 21, is bent into a U shape, and has a first vertical portion 22a and a vertical portion of the WS2. part 22b, and a first part 22b. Second
and a horizontal portion 22G connecting the vertical portions 22a and 22b. 1st. The annular) D-totes 23 and 24 are individually inserted into the second vertical portions 22a and 22b, respectively.
A permanent magnet (not shown) is installed inside the float 23.24.
move up and down independently depending on the height of the liquid level.

Further, a case 25 provided at the end of the vertical portion 22a houses a magnetostrictive coil and a drive/signal processing circuit (both not shown).

In the liquid level sensor 21 having the above configuration, a pulse current P is applied to the coil in the case 25 as shown in FIG. 6<a). is applied to generate magnetoelastic waves. The magnetoelastic wave propagates through the magnetostrictive body inside the protection@22 and reaches the other end 22d.
3. In this way, a part of the magnetoelastic waves that propagated through the magnetostrictive body in the protection tube 22 are transferred to the float 23. Flow 1-
24, that is, the magnetic field application part, and finally the end 2
2d and returns to the case 25. As shown in FIG. 6(b), the magnetoelastic waves reflected as described above arrive at the drive/signal detection circuit housed in the case 25, and the detection pulses P+ and P2 are detected via the coil.

P3 is manually operated.

Therefore, the drive/signal processing circuit can determine the position of the float 23 along the protection tube 22 from the time tl from the application of the pulse current Po until the detection pulse P1 is detected. Further, the drive/signal processing circuit can determine the position of the float 24 from the time t2 from the time when the pulse current Po is applied until the detection pulse P2 is detected, in the same manner as described above. Moreover, the distance along the protection tube 22 between the grooves 1 to 23 and 24 can be determined from the time difference Δt between the detection pulses P1 and P2. Also, Ho;'! By determining the time t3 until the detection pulse P3 of the magneto-elastic wave reflected from the end 22d of the tube 22, the float 23 is determined as in the second embodiment.
．． 24 position at time tl.

t:2. It can also be calculated from t3, in which case temperature changes in the propagation velocity are compensated for.

Note that the liquid level sensor 21 has a pair of 7[1-1 to 23.
Since the liquid level is measured from position 24, for example, in the case of a car fuel tank, even if the car is parked on an inclined surface, the position of the inclined liquid level can be measured by a pair of floats 23.2/l. 51, and based on the detection pulse, the actual remaining amount in the f fuel tank can be determined regardless of the inclination of the liquid level.Furthermore, in the embodiment 1, the pair of flows 1-23.24
] However, the present invention is not limited to this, and the number of vertical parts of the protection tube 22 may be increased to increase the number of flow 1- to two or more, and each 7-day
It is also possible to detect the 1-place d or float interval.

In the first to third embodiments described above, the permanent magnet is provided to move along the magnetostrictive body, but the magnetic field applying means does not necessarily move along the magnetostrictive body. do not have. An example thereof is shown in FIG.

In FIG. 7, the magnetic field applying means 31 is formed in the shape of a pencil, and a magnet 31a is fixed to its tip, that is, the pen tip.

Therefore, by holding the magnetic field applying means 31 and bringing it close to or in contact with the magnetostrictive body 32 at an arbitrary position, it is also possible to detect an arbitrary position at the above-mentioned position.

In addition, in the first to third embodiments described above, linear magnetostrictive bodies were stretched in a straight line to perform one-dimensional position detection.
The present invention is not limited to this, and for example, as shown in FIG. 8, a linear magnetostrictive body 41 may be bent in a zigzag pattern to form a planar position sensor 42.

A coil 43 is wound around the end of the magnetostrictive body 41, and the coil 43 is connected to a drive/signal processing circuit 44.

In FIG. 8, when the magnet 31a is brought into contact with an arbitrary position of the position sensor 42 using, for example, the pencil-shaped magnetic field applying means 31 shown in FIG. The position is determined by 2 from the time until the
Can be detected dimensionally (flat). An example of such an application field is a digitizer used as a graphic input device for inputting positional information on graphics or image information into a computer.

Effects of the Invention As described above, the position sensor of the present invention can simplify the configuration by reducing the number of parts compared to conventionally proposed position sensors, and requires less space for installing the valve. , can be easily manufactured. Moreover, even if a plurality of magnetic field applying means are provided, by detecting the magnetoelastic waves reflected by each magnetic field applying section, it is possible to simultaneously detect the positions of multiple points or the intervals between each (75). By comparing the time it takes for the magnetoelastic wave to reflect and return at a reflecting section set at a different position, it is possible to compensate for fluctuations in the propagation speed of the magnetoelastic wave due to temperature changes. By using a magnetostrictive material, it is not limited to a linear position (distance); for example, the magnetostrictive material can be arranged in a curved shape, or bent into a () shape, or bent into a zigzag shape to be arranged in a flat shape. It can be used not only to measure the linear distance to the magnetic field application part, but also to detect the position on a curve or two-dimensionally depending on the object to be measured, making it suitable for all kinds of applications. It has features such as being able to be applied for position detection.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a first embodiment of the position sensor 4 according to the present invention, FIG. 2 is a waveform diagram showing signals output and detected by the position sensor shown in FIG. 1, and FIG. Figure 4 is a schematic configuration diagram of the second embodiment of the present invention, Figure 4 is a waveform diagram showing the signal generated (ii) and the detected signal at the position sensor 1 shown in Figure 3, Figures 5 and 6 are waveform diagrams showing the detected signal. 7 is a schematic composition diagram of a liquid level sensor as a modified example of the present invention, and a waveform diagram of a signal generated and detected by the liquid level sensor υ, FIG. 7 is a perspective view showing a modified example of the magnetic field applying means, and FIG. Fig. 8 is a plan view showing a modification of about 100 degrees in which the magnetostrictive body is bent into a zigzag shape to form a flat surface. 1...Position sensor, 2...-Magnetostrictive body, 3, 4... Boulder, 5... Excitation coil, 6... Detection coil, 7...
...Drive circuit, 8...Signal start J! ! Circuit, 9... Permanent magnet, 11... Position sensor, 12-... Magnetostrictive body, 1
3... Coil, 14... Drive/signal processing circuit, 15
... Holder, 21 ... Liquid level adjustment, 31 ... Magnetic field application means, 41 ... Magnetostrictive body, 42 ... Position sensor.

Claims (1)

[Claims] A magnetostrictive body extending so that magnetoelastic waves propagate therein; an excitation means for generating magnetoelastic waves in the magnetostrictive body; What is claimed is: 1. A position sensor comprising: a magnetic field applying means provided as shown in FIG.