JPH0424510A - Displacement detector - Google Patents

Abstract

PURPOSE:To change the number of magnetic fluxes passing yokes linearly with respect to the displacement of a magnetism cutting member by distributing the magnetic fluxes at equal intervals in the longitudinal direction of the yokes, and changing the size of the range wherein the magnetic fluxes can be distributed based on the displacement of the magnetism shielding member. CONSTITUTION:When an exciting current is supplied into an exciting coil 5, from a power supply 6 the coil 5 generates alternating magnetic fluxes which are imparted to yokes 1 and 2. In the yoke 1, the magnetic fluxes cannot pass through a magnetic-flux cutting member 7. Therefore, the magnetic fluxes from a magnetic-flux supplying means 3 are distributed at equal intervals in the longitudinal direction of the yokes between the yokes 1 and 2 as shown by the symbol PHI. When the magnetic-flux cutting member 7 is displaced in the longitudinal direction of the yoke 1 together with a moving body through a linking means 8, the size of the range wherein the magnetic fluxes are distributed at the equal intervals is changed. Since the power supply 6 is a constant current power supply, the number of the magnetic fluxes generated from the coil 5 is proportional to the distance between the coil 5 and the magnetic-flux shielding member 7. Therefore, the number of the magnetic fluxes which are interlinked with a detecting coil 9 is changed in proportion to the displacement of the magnetic-flux shielding member 7. The output signal is linearly changed with respect to the displacement of the magnetic-flux shielding member 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a displacement detector used to detect the position of a displacing member.

[Conventional technology]

A differential transformer is an example of this type of displacement detector. In a differential transformer, due to the displacement of the moving object to be detected,
When the core connected to it moves back and forth, the distribution of magnetic flux changes. As a result, the number of magnetic fluxes that intersect with the detection coil changes, and the voltage obtained at the detection coil changes. In this way, a signal corresponding to the displacement of the moving body can be obtained from the detection coil.

[Problem to be solved by the invention]

In this conventional displacement detector, the distribution of magnetic flux changes with the displacement of the core as described above, so the change in the number of magnetic flux declinations with respect to the displacement of the core becomes non-linear, and the above-mentioned signal with respect to displacement becomes non-linear. There was a problem. Such a signal has the problem of complicating the control circuit, such as requiring a conversion circuit in the control circuit, when attempting to control the movement of the mobile object using the signal.

The present invention was made in order to solve the problems (technical problems) of the prior art described above, and it makes it possible to distribute the magnetic flux at equal intervals in the longitudinal direction of the yoke, and also to increase the size of the range where the magnetic flux can be distributed. By changing the magnetic flux according to the displacement of the magnetic shielding member, the number of magnetic fluxes passing through the yoke can be changed linearly with respect to the displacement of the magnetic shielding member, thereby detecting a signal with extremely good linearity with respect to displacement. The object of the present invention is to provide a displacement detector that can be obtained from a coil.

[Means to solve problems]

In order to achieve the above object, the present invention takes the measures as described in the claims above, and its effects are as follows.

[Effect]

Between the pair of yokes, magnetic flux is distributed at equal intervals in the longitudinal direction of the yokes only between the magnetic flux supply means and the magnetic flux blocking member. - The force detection coil outputs a signal corresponding to the number of magnetic fluxes passing through the yoke. As the magnetic flux blocking member is displaced in the longitudinal direction of the yoke, the size of the range in which the magnetic flux can be distributed at equal intervals changes. Therefore, the number of magnetic fluxes passing through the yoke varies linearly with the displacement of the magnetic flux blocking member. As a result, the signal changes linearly with the displacement of the magnetic flux blocking member.

〔Example〕

The drawings showing the embodiments of the present application will be described below.

In FIG. 1, I is a yoke of W, 1, which is formed into a cylindrical cane. 2 is a second yoke, which is formed into a cylindrical shape. These yokes 1 and 2 are made of a material with low magnetic resistance, such as permalloy, and are coaxially arranged so that their longitudinal directions are parallel to each other. Reference numeral 3 denotes magnetic flux supply means, which supplies magnetic flux to each end of the yoke 12 in the longitudinal direction on the same side. It is composed of an excitation coil 5 provided therein. 6 is an AC power source for exciting the coil 5, and for example, a constant current power source is used. 7
is a magnetic flux blocking member, which is formed in an annular shape and is connected to the first yoke 1.
The yoke is inserted through the yoke and is movable in the longitudinal direction of the yoke, and is connected to a moving body whose displacement is to be detected using a connecting means 8 made of a non-magnetic or non-metallic material. The magnetic flux blocking member 7 is made of a low electrical resistance material such as copper or silver. It is more preferable to use a superconducting material. Also, it is better to form it thicker so as to increase the cross-sectional area. Reference numeral 9 denotes a detection coil, which is disposed around the end of the yoke 1 where the magnetic flux supply means is attached, as shown, so that it can output a signal corresponding to the number of magnetic fluxes passing through the end. Reference numeral 9a denotes an output terminal, which is connected to a well-known circuit or device (not shown) that handles displacement corresponding signals.

In the above configuration, when an excitation current (for example, a high frequency current of several KHz) is supplied from the power supply 6 to the excitation coil 5, the coil 5 emits an alternating magnetic flux, which causes the yoke 1.
given to 2. In the yoke 1, when the magnetic flux tries to pass through the magnetic flux blocking member 7, the magnetic flux blocking member 7
The magnetic flux causes a short-circuit current of a magnitude corresponding to the number of magnetic fluxes to flow, and the short-circuit current generates magnetic flux of the same number and in the opposite direction as the magnetic flux that is passing through. Therefore, the magnetic flux cannot substantially pass through the magnetic flux blocking member 7. Therefore, the magnetic flux from the magnetic flux supplying means 3 is directed between the yokes 1 and 2 in the longitudinal direction of the yoke, as indicated by the symbol Φ in the range between the magnetic flux supplying means 3 and the magnetic flux blocking member 7. Distributed at equal intervals. In this state, the detection coil 9 has a number of magnetic fluxes penetrating the portion of the yoke 1 to which the detection coil 9 is attached (this number of magnetic fluxes is distributed in the space between the yokes 1 and 2 within the above range). (equal to the number of magnetic fluxes) are interlinked.

As a result, a voltage corresponding to the number of intersecting magnetic fluxes is induced in the detection coil 9, which is output as an output signal at the terminal 9a.
is output from.

When the magnetic flux blocking member 7 is displaced in the longitudinal direction of the yoke 1 together with the moving body via the connecting means 8, the size of the range in which the magnetic flux can be distributed at equal intervals changes. Since the power source 6 is a constant current power source, the number of magnetic fluxes emitted from the coil 5 is proportional to the distance between the coil 5 and the magnetic flux blocking member 7. That is, even if the size of the range in which the magnetic flux can be distributed changes, the intervals of the magnetic flux distribution remain constant. Therefore, the number of magnetic fluxes intersecting with the detection coil 9 changes in proportion to the displacement of the magnetic flux blocking member 7, and the output signal changes linearly with respect to the displacement of the magnetic flux blocking member 7. In the case of the above operation, the magnetic flux passing through the first yoke 1 mainly passes through the periphery of the yoke 1 due to the skin effect, so the yoke 1 may be formed hollow.

Next, FIG. 2 shows the characteristics of the displacement detector configured as described above (the relationship between the displacement of the magnetic flux blocking member 7 and the output signal obtained from the detection coil 9).
．． Except for the portion corresponding to the end portion of 2, it is possible to obtain an output that changes linearly with respect to the displacement of the magnetic flux blocking member 7.

Next, FIG. 3 showing a different embodiment of the present application will be described. This example shows an example in which the excitation coil 5d also serves as a detection coil. In this example, output terminal 9ad
By connecting the resistor 10 in series to the excitation voltage 156d, the coil 5d
Get the output signal from.

The above output signal can be expressed as follows. If E is the output signal, ω is the angular frequency of the excitation power source, ▪ is the constant current amplitude, and L is the inductance of the coil 5d, then E=ωLl. The inductance L is the coil 5d and the magnetic flux blocking member 7d.
Therefore, the output signal E is proportional to the displacement of the magnetic flux blocking member 7d.

It should be noted that parts that are functionally the same or equivalent to those in the previous figure are given the same reference numerals as in the previous figure, followed by the letter ``d'', and redundant explanations are omitted.

(Also, in the next and subsequent versions, e, f, g, h, i, and j of Alpha Bento will be added in order based on the same idea, and redundant explanations will be omitted.) Next, Fig. 4 shows a further different explanation of the present application. This shows an embodiment, and magnetic flux supply means IL are provided at one end and the other end of the yokes le and 2e, respectively.
12 is shown. In this example, the excitation coils 5e5e of each magnetic flux supply means 11.12 are connected to the power source 6e so that the magnetic fluxes emitted from each have polarities that collide with each other as shown. Note that 13 indicates a slit formed in a part of the second yoke 2e in the longitudinal direction thereof, and the connecting means 8e is made to pass through the slit 13.

In the configuration as described above, the voltages obtained in the detection coils on both sides (excitation coils 5e, 5e in each magnetic flux supply means 11.12) change, and the difference between these voltages is used as an output signal. The relationship between the output signal and the displacement of the magnetic flux blocking member 7e obtained at the output terminal 9ae is as shown by the solid line in FIG. Becomes a characteristic. By passing this output signal through a phase detector, a linear output as shown by the broken line can be obtained.

Next, FIG. 6 shows a further different embodiment of the present application, and shows a different example of the structure for displacing the magnetic flux blocking member 7f in the longitudinal direction of the yoke. In the figure, a through hole 15 is formed in the side plate 4f of the magnetic flux supply means, and
A first yoke 1f formed in an elongated length is provided so as to be freely advanced and retracted in the longitudinal direction through the through hole 15, and the yoke 1f
A magnetic flux blocking member 7f is attached to.

In such a configuration, the first yoke 1f is connected to the movable body.

Next, Fig. 7.8 shows a further different embodiment of the present application, in which the first yoke 1g is formed hollow, and a part of the yoke 1g has a narrow slit in the longitudinal direction. 18 are formed. A reciprocating rod 19 made of a non-magnetic material shown as an example of a connecting means is inserted into the hollow portion so as to be freely retractable. It's attached.

With such a configuration, the magnetic flux blocking member 7g can be displaced in the longitudinal direction of the yoke by moving the advancing/retracting rod 19 back and forth.

Next, FIG. 9.10 shows a further different embodiment of the present application, in which the first and second yokes 1h2h are both formed into a rod shape (plate shape), and a magnetic flux blocking member 7h is attached to each yoke.
, 7h are provided so as to be freely displaceable in the longitudinal direction of the yoke. The magnetic flux blocking member 7h, 7
h are formed integrally with each other so that they can move together in the longitudinal direction of the yoke.

When the pair of yokes lh and 2h are formed in this way and the detection coil is provided independently from the excitation coil, the detection coil is connected to each magnetic flux supply means 11h.
, 12h, it can be provided at any one of the locations or locations indicated by reference numerals 9h'' and 9h', respectively.

Next, FIG. 11 shows a further different embodiment of the present application,
This shows an example in which the yokes li and 2i are both formed in an arc shape centered on a single center point 22, and the magnetic flux blocking member 71 is provided so as to be movable along the yokes li and 2i.

With such a configuration, it is possible to obtain an output signal corresponding to the displacement of the rotational force direction of the magnetic flux blocking member 7j about the center point 22.

Next, FIG. 12 shows a further preferred embodiment of the present application.
1 shows an example of a displacement detector configured for a wet type proportional solenoid for a solenoid valve. In the figure, a pressure tube 24 is made of a non-magnetic material and communicates with the plunger chamber of the solenoid. Due to this communication, oil from the oil passage of the valve device flows into the pressure tube through the plunger chamber. The yoke 1j is housed in the pressure tube 24 so as to be able to move forward and backward, and is connected to the plunger in the plunger chamber by a connecting piece 25.

In the above configuration, the magnetic flux blocking member 7J is displaced by the yoke 1j moving forward and backward together with the plunger,
A signal corresponding to the displacement of the plunger can be obtained.

In each of the embodiments shown in FIGS. 5 to 12,
As in the example shown in FIG. 1, the magnetic flux supply means may be provided only at one end of the yoke.

[Effects of the Invention] As described above, in the present invention, when the magnetic flux blocking member 7 is displaced together with the moving body whose displacement is to be detected, the number of magnetic fluxes intersecting with the detection coil 9 changes, and the detection coil In the above case, in the present invention, the pair of yokes 1.2 are parallel, and between them the magnetic flux is directed in the longitudinal direction of the yokes. Moreover, the size of the range in which the magnetic flux can be distributed in the yokes 1 and 2 changes according to the displacement of the magnetic flux blocking member 7. The number of magnetic fluxes is determined by the magnetic flux blocking member 7.
It has the advantage of being able to change linearly with the displacement of . This means that the change in the number of magnetic fluxes interlinking with the detection coil 9 is linear with respect to the displacement of the magnetic flux blocking member 7, and has the effect of obtaining a signal with extremely good linearity with respect to displacement.

Such a linear signal for displacement has the advantage of simplifying the control circuit, for example, when the signal is used to control the movement of the moving body.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, and FIG. 1 is a schematic longitudinal cross-sectional view (hatching has been omitted for clarity), FIG. 2 is a characteristic diagram of the displacement detector shown in FIG. 1, and FIG. The figure is a schematic longitudinal section showing a different embodiment, FIG. 4 is a schematic longitudinal section showing a further different embodiment, FIG. 5 is a diagram showing the characteristics of the displacement detector of FIG. 4, and FIG. 7 is a sectional view showing an example of a displacement detector with a different structure for displacing the magnetic flux blocking member; FIG. 7 is a sectional view showing an example of a displacement detector with a further different structure for displacing the magnetic flux blocking member; 8 is a sectional view taken along the line ■-■ in FIG. 7, FIG. 9 is a sectional view showing a further different embodiment of the displacement detector, FIG. 10 is a perspective view of the example shown in FIG.
FIG. 2 is a sectional view showing further different embodiments of the displacement detector. 12... Yoke, 3.11.12... Magnetic flux supply means, 7... Magnetic flux blocking member, 9... Detection coil. Figures Figures Figures Figures Figures Figures Figures Figures Figures Doctors Figure 10 Figures Diagrams

Claims (1)

[Claims] 1. A pair of yokes are arranged so that their longitudinal directions are parallel to each other, and each end of the yokes on the same side in the longitudinal direction is provided with a A magnetic flux supplying means for applying alternating magnetic flux of opposite polarity is provided so that the magnetic flux can be distributed at equal intervals in the longitudinal direction of the yokes between the pair of yokes, and At least one of the yokes has a magnetic flux blocking member formed in an annular shape made of a low electrical resistance material so as to be able to block the passage of magnetic flux due to the generation of a short circuit current, with the yoke penetrating the magnetic flux blocking member. The yoke is provided so as to be movable in the longitudinal direction, and a detection coil is disposed around the end of at least one of the pair of yokes to which the magnetic flux supply means is attached, and the detection coil is disposed around the yoke. . A displacement detector, characterized in that a signal corresponding to a displacement position of the magnetic flux blocking member in the longitudinal direction of the yoke is obtained. 2. The displacement detector according to claim 1, wherein one yoke is formed into a columnar shape and the other yoke is formed into a cylindrical shape, and these are arranged coaxially. 3. The displacement detector according to claim 1, wherein magnetic flux supply means are attached to each one end and each other end of the pair of yokes. 4. The displacement detector according to claim 1, wherein one yoke is movable longitudinally relative to the other yoke, and a magnetic shielding member is attached to the movable yoke. 5. The columnar yoke is hollow and has a slit formed in its longitudinal direction, and a retractable rod is inserted into the hollow part of the yoke so that it can move forward and backward, and the retractable rod has a magnetic field. 3. The displacement detector according to claim 2, wherein the blocking member is attached through the slit. 6. The displacement detector according to claim 1, wherein the pair of yokes are formed in an arc shape. 7. The displacement detector according to claim 1, wherein the magnetic flux supply means includes an excitation coil, and the detection coil includes the excitation coil.