JP3018954B2 - Displacement converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type displacement conversion device constituted by magnetic means, and more particularly, to an improvement in sensitivity of output to displacement and reduction in current consumption. To a displacement conversion device.

[0002]

2. Description of the Related Art FIG. 4 is a configuration diagram showing a configuration of a conventional displacement conversion device. This displacement conversion device is disclosed in Japanese Utility Model Publication No. 60-333.
This is disclosed in No. 69, "Title of Invention: Displacement Conversion Device", and the outline will be described below.

[0003] 1 is a first coil, 2 is a second coil, 3 is an AC power supply, and 4 is a core. The first coil 1 is formed as a multi-turn coil by a conductive pattern on an insulating substrate. The second coil 2 is wound around one side of the U-shaped core 4 and is excited by the AC power supply 3.

The core 4 is made of a material having high magnetic permeability such as ferrite and has a U-shaped cross section. The core 4 is arranged so as to sandwich the first coil 1 between its parallel sides. In such a configuration, coils 1 and 2
Magnetically coupled via the core 4.

As a result, the core 4
An output voltage corresponding to the interlinkage area between the two is transmitted. Here, since the coil 1 is formed in a predetermined shape so that the interlinkage area with the core 4 changes linearly along the longitudinal direction, it corresponds to the relative displacement between the coil 1 and the core 4. Output voltage can be obtained.

FIG. 5 is a diagram for explaining the operation of the device constructed as described above, and the same parts as those in FIG. 4 are denoted by the same reference numerals. In FIG. 5, the core 4 is in the longitudinal direction (X
), An output voltage e corresponding to the displacement X is transmitted from the coil 1.

Here, assuming that the inclination angle of the pattern of the coil 1 is constant and the distribution of the magnetic flux density between the parallel sides of the core 4 sandwiching the coil 1 is uniform, the movement of the coil 1 The magnitude of the magnetic flux interlinking with the pattern also changes linearly, and the rate of change of the output voltage e becomes constant to obtain linearity. However, it is difficult to simply form such a core 4. Yes, a certain degree of non-uniform distribution of the magnetic flux density cannot be avoided.

For example, when the gap of the core 4 is made uniform, the magnetic flux density near the coil 2 is larger than the magnetic flux density far from the coil 2. This means that the relative magnetic permeability of the core 4 is a finite value of about 100, and the magnetic resistance of the core 4 is smaller in a portion close to the coil 2 by an amount corresponding to the length of the core 4 than in a portion far from the coil 2. It is due to.

As a result, even if the pattern of the coil 1 is formed linearly so that the inclination angle of the pattern is constant, the output voltage e is not uniform in the magnetic flux density distribution between the parallel sides of the core 4 sandwiching the coil 1. Will change in accordance with

That is, focusing on the rate of change of the output voltage in each portion of the coil 1, the rate of change of the output voltage in the inclined portion near the coil 2 wound around the core 4 is
Far from the coil 2 wound around (the tip of the triangle)
, The rate of change of the output voltage becomes larger, and a non-linear error as shown in FIG. 5 occurs.

Therefore, a coil 1 '(not shown) having the same shape as the coil 1 is formed in parallel on one surface of the insulating substrate so as to be symmetrical about the movable direction (X direction). Alternatively, a coil set is formed by arranging the oblique sides on both sides of the insulating substrate so as to intersect with each other, and connection is made so that the output voltages generated in these coil sets are added to avoid a non-linear error. Has been made.

FIG. 6 shows that an insulating substrate is formed in a disk shape, and a coil 5 similar to that shown in FIG. 4 is formed in an arc shape by a conductive pattern on the insulating substrate. It is configured as a rotary displacement conversion device that detects a rotational displacement by inserting the U-shaped core 4 across it.

[0013]

However, in the displacement converting apparatus as described above, in order to increase the output sensitivity per angle, it is necessary to increase the change in the interlinkage area per angle. This leads to an increase in the size of the device.
Therefore, this configuration has a problem that it becomes an obstacle in downsizing while improving the sensitivity.

[0014]

SUMMARY OF THE INVENTION The present invention is directed to a linkage with a magnetic flux.
So that the area has a certain function characteristic with respect to the direction of rotation
When multiple detection coil groups are formed by conductive patterns,
The edge substrate and the center of rotation with respect to the insulating substrate.
A plurality of movable parts arranged relative to the insulating substrate
U-shaped cores and these cores should be enclosed
1 formed on the insulating substrate to generate the magnetic flux
And a plurality of excitation coils.
Connected so that their electromotive forces are added to each other
Is a displacement conversion device.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an example of the embodiment of the present invention. FIG. 2 is a plan view showing the configuration when the embodiment shown in FIG. 1 is viewed from the direction of the rotation axis. FIG.
2 and FIG. 2 show a case where there are two detection coils as an example for simplicity.

Reference numeral 10 denotes a disc-shaped insulating substrate having a hole 11 formed at the center thereof, and the insulating substrate 10 is fixed to a case (not shown). On this insulating substrate 10,
A pair of detection coils 12, 13 are formed symmetrically with respect to an axis YY 'extending radially through the hole 11 with the same size by a conductive pattern.

The detection coils 12 and 13 are
Are formed in a predetermined shape so that the area of linkage with a magnetic flux emitted from a core described later linearly changes along the rotation direction around the center.

A rotary shaft 14 made of a non-magnetic material penetrates the hole 11, and the U-shaped cores 15, 16 have their back portions 15 a, 16 a opposed to each other. Fixed. Both ends of the rotating shaft 14 are rotatably fixed to a case (not shown). The cores 15 and 16 are made of a material having a high magnetic permeability such as ferrite.

Arms 15b and 15c, and 16b and 16c extend from both ends of the back portions 15a and 16a of the cores 15 and 16 in the radial direction of the insulating substrate 10 so as to sandwich the insulating substrate 10, respectively.

Further, the core 1 fixed to the rotating shaft 14
The excitation coils 17 are collectively insulated with the rotating shaft 14 so as to surround the back portions 15a and 16a.
A magnetic flux is applied to the detection coils 12 and 13 through the arms 15b and 15c and the arms 16b and 16c.

Accordingly, the arms 15b and 15c and the arms 16b and 16c move with the rotation of the rotating shaft 14, and output voltages corresponding to the area of linkage with the magnetic flux are generated in the detection coils 12 and 13, respectively.

Since the output voltages generated in the detection coils 12 and 13 are connected so as to be added to each other, a voltage twice as large as the voltage generated in the detection coils 12 and 13 is obtained as a whole.

Next, the operation of the displacement conversion device configured as described above will be described in more detail with reference to FIG.
FIG. 3 illustrates the magnetic coupling between the excitation coil and the detection coil in an equivalent circuit.

[0024] By applying the excitation voltage V _f to the exciting coil 17, the exciting current I _f flows through the excitation coil 17.
In this case, for simplicity, the resistance _Rf of the exciting coil 17 is set to zero.

If the self-inductance of the exciting coil 17 is L _f and the angular frequency of the exciting voltage V _f is ω _f , then V _f = jω _f L _{f If} (1)

Next, paying attention to only one side coil, the output voltage generated in the detection coil 12 (or 13) is assumed to be _Vd , and the detection coil side is to be received at high impedance. The flowing detection current _Id becomes zero.

Therefore, the detection coil 12 (or 13)
And the mutual inductance between the exciting coil 17 and M
Assuming that (θ) [θ: rotation angle] and the self-inductance of the detection coil 12 is L _d , V _d = jω _f M (θ) _If (2) is obtained.

[0028] Here, when the coupling coefficient K (theta), an M (θ) = K (θ ) (L d L f) 1/2 (3), when S a (theta) and interlinkage area , K (θ) ∝S
Since there is a relationship of (θ), sensitivity = dV _d (θ) / dθ = (L _d / L _f ) ^1/2 V _f (dS (θ) / dθ) (4)

Further, the exciting current I _f to be consumed is given by _{/ I f = V f (jω} f L f) (5).

Here, the detection coil shown in FIG. 1 and FIG.
Since the range in the radial direction is the same as that of the detection coil shown in FIG. 6 and the rotation range in the angular direction is ２, the area change rate per angle per detection coil is doubled. As a whole, dS (θ) / dθ is quadrupled,
Therefore, the sensitivity is quadrupled.

Further, since there are two cores 15 and 16, the number of cores is twice as large as that of FIG. 6, the self-inductance is twice as large as L _d and L _f , and the exciting current _If is 1 / l.
As a result, the current consumption is reduced by half.

In the above description, the case where there are two cores and two detection coils has been described. However, the present invention is not limited to this, and the sensitivity is improved by using more cores and detection coils. be able to. Also, the detection coil may be provided not only on one surface of the insulating substrate but also on the other surface.

[0033]

As described above, according to the present invention,
One excitation coil and multiple detection coils are
Formed with conductive patterns on the board, reducing the number of parts
Can be eliminated, resulting in smaller equipment and lower cost.
Can be realized. Also, one excitation coil
Generates magnetic flux in multiple cores with multiple detection coils
Since the signal is taken out, the sensitivity of the displacement conversion device and
Excitation impedance increases, resulting in lower current consumption
Can be reduced. In addition, low current consumption is possible.
The limited transmission power from the load side with two transmission lines.
To supply all the circuit power with this current
It can be mounted on an operating two-wire transmitter.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention.

FIG. 2 is a front view of the embodiment shown in FIG. 1 as viewed from a direction of a rotation axis.

FIG. 3 is an equivalent circuit diagram for explaining the operation of the embodiment shown in FIG. 1;

FIG. 4 is a perspective view showing a configuration of a conventional displacement conversion device.

FIG. 5 is an operation explanatory diagram illustrating an operation of the displacement conversion device shown in FIG. 4;

FIG. 6 is a perspective view showing a configuration when the displacement conversion device shown in FIG. 4 is of a rotary type.

[Explanation of symbols]

 Reference Signs List 1 coil 2 coil 3 AC power supply 4 core 5 coil 10 insulating substrate 11 hole 12 detection coil 13 detection coil 14 rotation axis 15 core 16 core 17 excitation coil

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-223502 (JP, A) JP-A-57-14809 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 7/00-7/34 G01D 5/20

Claims (1)

(57) [Claims] 1. An insulating substrate in which a plurality of detection coil groups are formed by conductive patterns so that the area of linkage with a magnetic flux has a predetermined functional characteristic with respect to the direction of rotation. A plurality of U-shaped core groups arranged so as to be relatively movable with respect to the insulating substrate; and a plurality of core groups formed on the insulating substrate so as to surround these core groups collectively.
And one excitation coil for generating the magnetic flux,
A displacement converter, wherein the electromotive forces generated in the detection coil groups are connected so as to be added to each other.