JP2596841B2 - Inductance displacement sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inductance type displacement sensor for detecting a displacement of a cylindrical or cylindrical object such as a rotating body.

(Prior art)

Here, for convenience of explanation, an inductance type displacement sensor for detecting a displacement of a cylindrical object to be detected will be described. Fig. 5 shows a conventional inductance type displacement sensor.
FIG. 6 shows a block diagram of the sensor circuit. In FIG. 5, reference numeral 120 denotes a columnar object to be detected. E-shaped sensor cores 111, 112, 113, 114 are arranged around the object to be detected 120 with a gap therebetween.
Sensor coils 101, 102, 103, and 104 are provided in each of 13, 114.

In the inductance type displacement sensor having the above configuration, for example, when the detected object 120 is displaced in the Y direction from a predetermined position, the inductance of the sensor coils 101 and 103 changes,
When displaced in the X direction, the inductance of the sensor coils 102 and 104 changes. By detecting the change in the inductance, the displacement of the detected object 120 is detected.

[Problems to be solved by the invention]

However, in the conventional inductance type displacement sensor shown in FIG. 5, when a pair of sensor coils is used in a measurement direction (for example, sensor coils 101 and 103).
Meanwhile, when an external magnetic flux 107 is applied, an electromotive force is generated in the sensor coil 101 by mutual induction. This electromotive force is generated in the sensor coil 101 like the electromotive force 118 as shown in FIG.
There is a problem that this is superimposed on a change in potential due to a change in inductance of No. 3 and this becomes noise with respect to the displacement signal of the displacement sensor. In FIGS. 5 and 6, reference numeral 106 denotes an arrow indicating the direction of magnetic flux generated at a certain moment by the carrier wave of the sensor itself, 115 denotes a carrier generation circuit, and 116 denotes a detection circuit.

The present invention has been made in view of the above points, and eliminates the above-described problems, cancels out an electromotive force generated in a sensor coil by mutual induction of external magnetic flux, and increases the number of sensor coils when the number of sensor coils is increased. An object of the present invention is to provide an inductance type displacement sensor which can prevent interference between coils.

[Means for solving the problem]

In order to solve the above-mentioned problem, the invention described in claim (1) arranges a pair of sensors including a core made of a magnetic material and a coil wound on the core so as to face each other. An inductance-type displacement sensor for measuring displacement of a measurement object, which is made of a magnetic material, in a direction opposite to the sensor and disposed between the pair of sensors based on a change in inductance of a coil, the sensor core having two magnetic poles, One coil is provided for each of the two magnetic poles, and the two coils are wired in series, and the magnetic flux generated from each coil is arranged in the opposite direction. The magnetic flux to be generated is formed so as to pass through the same magnetic path, and two magnetic poles of the sensor core are arranged so as to face the object to be measured.

The invention described in claim (2) provides a sensor including a core made of a magnetic material and a coil wound on the core in two orthogonal directions having different measurement directions. In an inductance type displacement sensor, which is disposed so as to face each other on the axis of the sensor, and measures the displacement in the facing direction of the measured object made of a magnetic material disposed between the facing sensors by changing the inductance of the coil, the sensor core is 2
Having two magnetic poles, one coil for each of the two magnetic poles, the two coils are wired in series, and the magnetic fluxes generated from each other are arranged in opposite directions, The magnetic flux generated from the two coils is formed so as to pass through the same magnetic path, and the two magnetic poles of the sensor core are arranged to face the object to be measured and are arranged on the two different axes. And coils adjacent to each other are arranged such that magnetic fluxes generated from the coils repel each other.

[Action]

According to the invention described in claim (1), by adopting the above-described configuration, the coils provided on each of the two magnetic poles of the sensor core are wired in series, and the magnetic flux generated from the coils is mutually different. Since the magnetic fluxes generated from the two coils are arranged so as to be in opposite directions and pass through the same magnetic path, the electromotive forces generated in the respective coils by the external magnetic fluxes are opposite to each other and are canceled out. Sensor noise due to external magnetic flux can be reduced, and more accurate displacement can be measured.

According to the invention described in claim (2), the coils of the sensors which are arranged on different axes and which are adjacent to each other are arranged such that magnetic fluxes generated from the coils repel each other. With the arrangement, interference between the coils can be prevented, noise can be reduced, and more accurate displacement of the measured object can be measured. That is, when the sensors are arranged so that magnetic fluxes generated from coils adjacent to each other on different axes are attracted to each other (different polarities), part of the magnetic flux generated from one coil becomes magnetic flux generated from the other coil. In order to make the magnetic path common to a part of the measurement, the change of one magnetic flux due to the displacement of the measured object affects the other, that is, interferes with each other,
Although the displacement of the object to be measured cannot be measured accurately, in the present invention, if the coils are arranged so as to repel each other (having the same polarity), interference between the coils is prevented, so that a change in one magnetic flux due to the displacement of the object to be measured affects the other. And the displacement of the measured object can be accurately measured.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an inductance type displacement sensor according to the present invention. In FIG. 1, reference numeral 20 denotes a columnar object to be detected. A gap is provided between the object 20 and the U-shaped sensor cores 11, 12, 13, and 14 are fixed to an annular support member 21. Are located. The sensor core 11 is provided with a pair of sensor coils 1 and 2 at respective poles, the sensor core 12 is provided with a pair of sensor coils 3 and 4, the sensor core 13 is provided with a pair of sensor coils 5 and 6, and the sensor core 14 is provided with a sensor coil. A pair of sensor coils 7 and 8 are provided. If the detected object 20 is displaced in the Y direction, the inductance of the sensor coils 1, 2 and the sensor coils 5, 6 changes, and if the detected object 20 is displaced in the X direction, the inductance of the sensor coils 3, 4 and the sensor coils 7, 8 changes. .
The displacement of the detection target object 20 is detected using the change in the inductance. The sensor cores 11, 12, 13, 14 and the detection target 20 are made of a ferromagnetic material.

FIG. 2 is a diagram for explaining the operation of the inductance type displacement sensor having the above configuration, and FIG. 3 is a block diagram of a sensor circuit. By mounting the sensor coils 1 and 2 in series so that the directions of the magnetic fluxes generated by the respective coils are opposite to each other, the magnetic flux generated by the carrier wave of the sensor itself is indicated by an arrow 9 at a certain moment. Become like When the magnetic flux 10 enters from the outside, as shown in FIG. 3, the electromotive force 31 and the electromotive force 32 are generated in the sensor coil 1 and the sensor coil 2 in opposite directions, and cancel each other. The same applies to the sensor coils 5, 6 (omitted in FIG. 2) on the opposite side of the detected object 20. The sensor coils 3 and 4, the sensor coils 5 and 6, and the sensor coils 7 and 8 are also wired in series with each other, and are installed so that the directions of the generated magnetic fluxes are opposite to each other.

As shown in FIG. 2, the directions of the magnetic fluxes 9 and 15 of the sensor coils 1 and 8 adjacent to each other and having different measurement directions are set as follows.
By arranging the surfaces facing the detected object 20 to have the same polarity, the magnetic fluxes 9 and 15 generated in each of the sensor coils 8 and 1 repel each other and do not pass through each sensor coil. There is no interference. Also,
Similarly, the sensor coils 2 and 3, the sensor coils 4 and 5, and the sensor coils 6 and 7 are also arranged so that the polarities of the surfaces facing the detected object 20 are the same.

The above is described in detail with reference to the drawings. When the sensor coils 1 and 8, the sensor coils 2 and 3, the sensor coils 4 and 5, and the sensor coils 6 and 7 are adjacent to each other and have different measurement directions, By making the polarities of the surfaces to be the same, the magnetic fluxes 9, 15, 16, and 17 generated from the adjacent sensor coils repel each other as shown in FIG. Therefore, the displacement of the object 20 can be accurately detected without the change of the magnetic flux of one sensor coil by the object 20 affecting the other. On the other hand, the sensor coils 1 and 8, the sensor coils 2 and 3, the sensor coils 4 and 5, and the sensor coils 6 and 7 are arranged so that the polarities of the surfaces facing the detection object 20 are different from each other, so that they are adjacent to each other. The magnetic fluxes 9, 15, 16, 17 generated from the sensor coil are the eighth.
As shown in the figure, the magnetic poles attract each other, and a magnetic flux (magnetic flux having a common magnetic path) 18 around the adjacent magnetic poles is generated and interferes with each other. Therefore, a change in the magnetic flux of one sensor coil due to the detection target 20 affects the other, and the displacement of the detection target 20 cannot be accurately detected.

FIG. 4 is a diagram showing a configuration of another inductance type displacement sensor according to the present invention. As shown in the figure, the detected object
An annular sensor core 60 made of a ferromagnetic material is arranged around 20 and the magnetic poles 41, 42, 43, 44, 45, 4 are provided inside the annular sensor core 60.
6,47,48 are integrally formed. Here, the magnetic poles 41 and 42 correspond to the sensor core 11 shown in FIG.
2, magnetic poles 45 and 46 are sensor core 13, magnetic poles 47 and 48 are sensor core 1.
Equivalent to 4. That is, if the detected object 20 is displaced in the Y direction, the inductance of the sensor coils 51 and 52 and the sensor coils 55 and 56 is changed, and if the detected object 20 is displaced in the X direction, the sensor coils 53 and 54 are displaced.
Then, the inductance of the sensor coils 57 and 58 changes. The displacement of the detection target object 20 is detected using the change in the inductance.

The sensor coils 51 and 52 are wired in series and installed so that the directions of the generated magnetic fluxes are opposite to each other. The sensor coils 53 and 54, the sensor coils 55 and 56, and the sensor coils 57 and 58 are also wired in series, and are installed so that the directions of the generated magnetic fluxes are opposite to each other.

The directions of the magnetic fluxes of the sensor coils 51 and 58 which are adjacent to each other and have different measurement directions are arranged so that the polarities of the surfaces facing the detection target object 20 are the same. As a result, the magnetic fluxes generated in the sensor coils 51 and 58 repel each other and do not pass through the sensor coils, so that they do not interfere with each other. Similarly, the sensor coils 52 and 53, the sensor coils 54 and 55, and the sensor coils 56 and 57 are also arranged so that the directions of the magnetic flux are the same on the surfaces facing the detection target 20.

〔The invention's effect〕

As described above, according to the invention described in claim (1), the coils provided on each of the two magnetic poles of the sensor core are arranged in series, and the magnetic fluxes generated from the coils are opposite to each other. Since the magnetic fluxes generated from the two coils are formed so as to pass through the same magnetic path, the external magnetic flux cancels out the electromotive force generated in each coil, thereby reducing noise. An excellent effect that more accurate displacement can be measured is obtained.

In addition, the invention described in claim (2) is:
Further, the coils of the sensors which are arranged on two different axes and which are adjacent to each other are arranged so that the magnetic flux generated from the coils repel each other, so that interference between the coils can be prevented. Therefore, noise can be reduced, and more accurate displacement of the measured object can be measured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the configuration of an inductance type displacement sensor according to the present invention, FIG. 2 is a diagram for explaining the operation of the inductance type displacement sensor having the above configuration, and FIG. FIG. 4 is a block diagram of a circuit, FIG. 4 is a diagram showing a configuration of another inductance type displacement sensor according to the present invention, FIG. 5 is a diagram showing a configuration of a conventional inductance type displacement sensor, and FIG. 6 is a block diagram of the sensor circuit. 7 and 8 are views showing the state of magnetic flux generated from the sensor coil. In the figure, 1 to 8: sensor coil, 11 to 14: sensor core, 20: detected object, 21: carrier wave generation circuit, 22:
Detection circuit, 41-48 ... pole, 51-58 ... sensor coil, 60
…… Circular sensor core.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Minoru Takizawa 885-6 Taninocho, Hachioji-shi, Tokyo 51-8 Mitsudai 51-8 (72) Inventor Riki Murakami 1444-8 Izumicho, Hachioji-shi, Tokyo (72) Inventor Yoichi Kanemitsu 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture, EBARA Research Institute, Inc. (72) Inventor Yuji 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture, EBARA Research Institute, Inc. (56) References JP JP-A-57-50601 (JP, A) JP-A-58-41304 (JP, A)

Claims (2)

(57) [Claims] A sensor comprising a core made of a magnetic material and a coil wound on the core is disposed so as to face each other, and a sensor made of a magnetic material is disposed between the pair of sensors. In an inductance type displacement sensor for measuring the displacement of the measuring object in the facing direction by a change in inductance of the coil, a core of the sensor has two magnetic poles, and one coil is provided for each of the two magnetic poles. , The two coils are arranged in series, the magnetic fluxes generated from the coils are arranged in opposite directions, and the magnetic fluxes generated from the two coils are formed to pass through the same magnetic path. An inductance type displacement sensor, wherein two magnetic poles of a core of the sensor are arranged so as to face the object to be measured. 2. A sensor comprising a core made of a magnetic material and a coil wound on the core is disposed so as to face each other on two orthogonal axes different from each other in a measurement direction. An inductance-type displacement sensor that measures displacement of the object to be measured, which is a magnetic body disposed between opposed sensors, in the opposite direction based on a change in inductance of the coil, wherein a core of the sensor has two magnetic poles, One coil is provided for each of the two magnetic poles, and the two coils are wired in series, and the magnetic flux generated from each coil is arranged in the opposite direction. The generated magnetic flux is formed so as to pass through the same path. The two magnetic poles of the sensor core are arranged opposite to the object to be measured, and the sensor coils are arranged on the two different axes. Coil that are next to each other I can,
An inductance type displacement sensor, wherein magnetic fluxes generated from the coil are arranged to repel each other.