JP2017150861A - Rotation angle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation angle detector which exhibits a high accuracy of rotation angle measurement and can be driven with a small current, and with which it is possible to measure the revolving speed of a rotor rotating at high speed.SOLUTION: A rotation angle detector includes a rotary member 100 having portions differing in the distance from the center of rotation in a plurality of places and a magnetic flux detection unit 20, the magnetic flux detection unit 20 comprising a first oscillation circuit, a second oscillation circuit, measurement means for measuring the oscillation frequency of each of the first oscillation circuit and the second oscillation circuit, calculation means for calculating a difference in oscillation frequencies measured by the measurement means, and conversion means for converting the difference calculated by the calculation means into magnetic permeability, characterized in that a change in the distance of the rotary member 100 and the magnetic flux detection unit 20 that changes due to the rotation of the rotary member 100 is detected as a change of magnetic permeability and the rotation angle of the rotary member 100 is detected.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of a rotating portion of a device having a rotating portion.

Various rotation angle sensors have been proposed for measuring the rotation angle and rotation speed of a mechanical facility such as a rotor of a rotating machine or a rotating part of an automobile.
For example, Patent Document 1 discloses a rotational speed detection device that measures the wheel speed of an automobile.
A rotation sensor having an output coil arranged in the vicinity of a detected rotating body that constitutes the outer periphery of a plurality of parts arranged at a predetermined interval made of a conductor or a magnetic material detects an eddy current or a change in magnetic permeability of the magnetic material. ing.
Patent Document 1 does not specifically disclose the configuration or measurement method of the output coil.
Patent Document 2 discloses a rotation angle detection device having a disk having a magnetic permeability change pattern and a detection coil for detecting a change in magnetic permeability of the disk as an inductance change.
In the technique disclosed in Patent Document 2, it is necessary to excite the core, and a large amount of exciting current needs to flow, so that power consumption increases.
Moreover, since the eddy current loss of the core is included as a change in the magnetic permeability, the measurement error increases.

JP 2001-33467 A JP 2014-20792 A

  Therefore, an object of the present invention is to provide a rotation angle detection device that can measure the rotation speed of a rotating body that rotates at a high speed with high rotation angle measurement accuracy and can be driven with a small current.

A rotating member made of a magnetic material and having a plurality of portions having different radial distances from the rotation axis;
Having a magnetic flux detector for detecting the permeability of the rotating member;
The magnetic flux detector is
A first oscillation circuit that oscillates including a first coil that receives magnetism from the rotating member;
A second oscillation circuit that oscillates including a second coil that receives magnetism from the rotating member;
Measuring means for measuring an oscillation frequency in each of the first oscillation circuit and the second oscillation circuit;
Calculating means for calculating a difference between oscillation frequencies measured by the measuring means;
A conversion means for converting the difference calculated by the calculation means into magnetic permeability;
A rotation angle detection device that detects a rotation angle of a rotation member by detecting a change in the distance between the rotation member and the magnetic flux detection unit that changes due to rotation of the rotation member as a change in magnetic permeability.

  In the present invention, since the magnetic permeability is detected from the difference between the oscillation frequencies of the two oscillation circuits and the rotation angle is measured from the change in the magnetic permeability, the rotation angle can be measured accurately.

  The rotating member is a cylindrical body having irregularities on the outer peripheral surface.

  In the present invention, since the cylindrical member having the unevenness on the surface is used as the rotating member, the change in the rotation angle can be accurately measured.

  The rotating member is a column having an elliptical cross section.

  In the present invention, since the member having an elliptical cross section is used as the rotating member, the measurement accuracy of the rotation angle can be increased.

  The center of rotation of the cross-sectional ellipse is different from the axis center of the ellipse.

  In the present invention, since the rotation center is different from the axis center of the ellipse, the rotation angle can be accurately known.

  The rotation angle detection device of the present invention has high measurement accuracy of the rotation angle, can be driven with a small current, and can detect the rotation angle of a rotating body that rotates at high speed.

It is a perspective view which shows the magnetic flux detection part which is a component of this invention. It is sectional drawing which shows the magnetic flux detection part which is a component of this invention. It is an axial sectional view showing the composition of the rotation angle detection device of the present invention. It is a block diagram which shows the function structure of the magnetic flux detection part which is a structure part of this invention. It is a circuit diagram which shows one structural example of the magnetic flux detection part which is a structural part of this invention. It is a timing chart for demonstrating operation | movement of the magnetic flux detection part which is a component of the structure of this invention. It is sectional drawing which shows another embodiment of the rotation angle measuring apparatus of this invention. It is sectional drawing which shows another embodiment of the rotation angle measuring apparatus of this invention.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. 1 and 2 are a perspective view and a cross-sectional view showing the configuration of the magnetic flux detector of the present invention.

  1 and 2, reference numeral 10 denotes a flat rectangular substrate. A first coil 1 is formed on one surface (lower surface) of one end of the substrate 10 (see FIG. 2). A second coil 2 is formed on the other surface (upper surface) of one end of the substrate 10 so as to be coaxial with the first coil 1. The first coil 1 and the second coil 2 are formed, for example, by printing a copper foil pattern on the substrate 10.

  A connector 3 is mounted on the upper surface of the other end portion of the substrate 10 with a part protruding from the other end. On the upper surface of the central portion of the substrate 10, an electronic chip 4 composed of a microcomputer for performing various processes described later is mounted. Further, a circuit component 5 is mounted in the vicinity of the electronic chip 4. The circuit component 5 includes a capacitor for forming an oscillation circuit with the first coil 1 or the second coil 2. The magnetic flux detection unit 20 of the present invention has the above configuration.

FIG. 3 is a cross-sectional view showing an example of the rotation angle detection device of the present invention.
The rotating member 100 made of a magnetic material has a cylindrical shape or a disk shape, and rotates around the rotating shaft 110. The outer peripheral part of the rotating member has rectangular convex parts 120 arranged at equal intervals in the circumferential direction. A concave portion 130 is formed between the convex portions 120.
In other words, uneven portions are formed at equal intervals on the outer peripheral portion of the rotating member.
The distance in the radial direction from the axial center (rotary axis) of the concave portion of the outer peripheral portion of the rotating member is different from the distance in the radial direction from the rotational axis of the convex portion, and there are a plurality of portions having different distances.
The magnetic flux detection unit 20 is arranged while maintaining a certain distance in the radial direction from the center (rotating shaft 110) of the rotating member.
In FIG. 3, the magnetic flux detection unit 20 has the first coil 1 on the lower side, the front side of the paper is one end of the substrate 10 (the first coil 1 and second coil 2 forming side), and the back of the paper is the other end of the substrate 10. (Connector 3 mounting side)
In other words, in FIG. 3, the portion viewed from the left side of FIG.
The rotating member is connected to, for example, a rotating part of a device (not shown) by a shaft or the like.
With this configuration, the shortest distance between the rotating member 100 and the magnetic flux detection unit 20 changes as the rotating member rotates.
When the convex portion 120 of the rotating member 100 is below the magnetic flux detecting unit 20, the distance between the rotating member 100 and the magnetic flux detecting unit 20 is closest, and when the concave portion 130 of the rotating member 100 is below the magnetic flux detecting unit 20. The distance between the rotating member 100 and the magnetic flux detector 20 is the longest.
Since the rotating member 100 is a magnetic body, the inductance of the coil changes as the distance to the magnetic flux detection unit 20 (coil portion) changes.
The change in permeability can be known from the change in inductance.
The rotation angle of the rotating member can be known from the change in the magnetic permeability when the rotating member rotates.
In addition, the rotation speed and the rotation speed can be obtained from the detected rotation angle by calculation.
The cross-sectional shape of the rotating member 100 only needs to have at least two or more parts having different distances from the rotation axis center to the rotating member surface. In other words, even if the cross section is circular, if the rotation axis is deviated from the center of gravity of the circle (if it is decentered), the rotation member 100 rotates to change the distance between the rotation member 100 and the magnetic flux detection unit 20. The function as a member is demonstrated.
FIG. 3 schematically illustrates a configuration in which the rotating member is disposed in, for example, a cylindrical casing 160 and the magnetic flux detection unit is disposed in the casing.
Any configuration may be used as long as the interval between the rotating member and the magnetic flux detection unit is kept constant, and the configuration is not limited to that shown in FIG.

  The magnetic flux detector 20 is arranged so that the lower surface side of the substrate 10 shown in FIGS. 1 and 2 is on the rotating member side. Therefore, the first coil 1 is disposed closer to the rotating member than the second coil 2 by the thickness of the substrate.

A method for detecting the magnetic permeability that is a parameter for detecting the rotation angle will be described below.
As a method for knowing the rotation angle from the obtained magnetic permeability and a method for knowing the rotation speed and the rotation speed from the rotation angle, a known method may be used.

FIG. 4 is a block diagram showing a functional configuration of the magnetic flux detection unit 20 of the rotation angle detection device of the present invention. In FIG. 4, the same or similar parts as those in FIGS. 1 and 2 are denoted by the same reference numerals.
The first coil 1 and a part of the circuit component 5 constitute a first oscillation circuit 6, and the second coil 2 and a part of the circuit component 5 constitute a second oscillation circuit 7. In the magnetic flux detection unit 20 of the present invention, the first and second oscillation circuits 6 and 7 share the same components other than the first coil 1 and the second coil 2. Therefore, the oscillation frequency measured by each of the first oscillation circuit 6 and the second oscillation circuit 7 is not affected by the characteristic variation due to different constituent members, and an accurate value is measured. Therefore, the magnetic permeability detection accuracy is high.

  The electronic chip 4 includes a measurement unit 41 that measures the oscillation frequency in each of the first oscillation circuit 6 and the second oscillation circuit 7, a calculation unit 42 that calculates a difference between the oscillation frequencies measured by the measurement unit 41, and a calculation unit. It has functionally the conversion part 43 which converts the difference calculated in 42 into magnetic permeability.

  FIG. 5 is a circuit diagram showing a configuration example of the magnetic flux detection unit 20 of the present invention. In FIG. 5, the coil L1 and the coil L2 correspond to the first coil 1 and the second coil 2 described above, respectively. The microcomputer U1 corresponds to the electronic chip 4 described above.

  One end of the coil L1 is connected to the sixth terminal of the microcomputer U1, and one end of the coil L2 is connected to the third terminal of the microcomputer U1. The other end of the coil L1 and the other end of the coil L2 are connected to the base of the transistor Q1 via the capacitor C1. A resistor R2 is provided between the base and collector of the transistor Q1, and a capacitor C2 is provided between the base and emitter of the transistor Q1. The collector of the transistor Q1 is connected to the second terminal of the microcomputer U1 and is grounded through the resistor R3.

  The first terminal of the microcomputer U1 is connected to the input terminal for the power supply voltage Vdd. The input terminal of the power supply voltage Vdd is connected to the emitter of the transistor Q1 through the resistor R1. One end of a capacitor C3 is connected between the resistor R1 and the emitter of the transistor Q1, and the other end of the capacitor C3 is grounded. One end of a capacitor C6 is connected between the input terminal of the power supply voltage Vdd and the first terminal, and the other end of the capacitor C6 is grounded. A grounding terminal is connected to the eighth terminal of the microcomputer U1.

  An output terminal that outputs a detection voltage Vout corresponding to the magnetic permeability is connected to the seventh terminal of the microcomputer U1 via a resistor R4. One end of a capacitor C7 is connected between the output terminal and the resistor R4, and the other end of the capacitor C7 is grounded. An input terminal for inputting a control voltage Vcont for performing offset control is connected to the fifth terminal of the microcomputer U1 via a resistor R6. One end of a capacitor C4 is connected between the fifth terminal of the microcomputer U1 and the resistor R6, and the other end of the capacitor C4 is grounded.

  The coil L1, the two capacitors C2 and C3, and the transistor Q1 constitute the first oscillation circuit 6 (Colpitts oscillation circuit). The coil L2, the two capacitors C2 and C3, and the transistor Q1 described above. A second oscillation circuit 7 (Colpitts oscillation circuit) is configured. Then, by the switching operation of the microcomputer U1 (the switching operation is performed at the third terminal and the sixth terminal of the microcomputer U1), the first oscillation circuit 6 and the second oscillation circuit 7 oscillate alternately at predetermined time intervals. It is like that.

  Next, operation | movement of the magnetic flux detection part 20 of this invention is demonstrated. FIG. 6 is a timing chart for explaining the operation of the magnetic flux detector 20 of the present invention.

  The first oscillating circuit 6 and the second oscillating circuit 7 are alternately oscillated for a predetermined time, and the oscillation frequency in each oscillation is measured by the measuring unit 41. The predetermined time is 2 ms, for example. At this time, as shown in FIG. 6, in the period in which the first oscillation circuit 6 is oscillated and the oscillation frequency is measured, the second oscillation circuit 7 is not oscillated, and the second oscillation circuit 7 is oscillated and the oscillation is performed. The first oscillation circuit 6 is not oscillated during the frequency measurement period. Therefore, since the oscillation frequency is measured without being influenced by oscillation, the measured value is highly accurate.

When the measurement of the oscillation frequency for each predetermined time (for example, 2 ms) is finished, the oscillation frequency measured in the first oscillation circuit 6 (derived from the first coil 1) and the oscillation frequency in the second oscillation circuit 7 (in the second coil 2) The difference from the measured oscillation frequency is calculated by the calculation unit 42. And the conversion part 43 converts the calculated difference into a magnetic permeability, and calculates | requires the variation | change_quantity of a magnetic permeability. The magnetic flux detection unit 20 detects a change in distance from the magnetic body as a change in magnetic permeability.
The predetermined time can be further shortened according to the rotational speed of the object to be measured.
It is also possible to set the shape and size of the rotating member as appropriate according to the number of rotations.
Since measurement is performed by switching between the first oscillation circuit and the second oscillation circuit in a short time, measurement is possible even when rotating at high speed.

  Further, in the period in which the first oscillation circuit 6 is oscillated and the oscillation frequency is measured, the difference between the previous measurement values (for example, A ′ and B ′) of the first oscillation circuit 6 and the second oscillation circuit 7 is calculated as follows: The calculation unit 42 calculates the difference, and the conversion unit 43 converts the calculated difference into the magnetic permeability to obtain the change amount of the magnetic permeability. Therefore, the change amount of the magnetic permeability is measured at the timing of starting the measurement of the oscillation frequency of each oscillation circuit. Updates are made sequentially.

  The present invention has the following advantages. The range in which the permeability changes may vary depending on the type and shape of the magnetic material of the rotating member used. In this case, for example, by using an unused terminal of the microcomputer U1 and controlling the voltage level of the unused terminal from the outside, an offset function for adjustment can be provided.

  Note that although FIG. 5 shows a microcomputer having eight terminals as an example, it is not limited to this configuration. If necessary, it is possible to use a microcomputer with a different number of terminals and transmit information such as permeability change to the upper control side by means of serial communication etc. and receive control signals from the upper side. is there.

Hereinafter, the principle by which the magnetic permeability can be detected by the procedure as described above will be described.
When the magnetic permeability of the object to be detected increases (when a part of the rotating member approaches the coil), the inductance of the coil disposed in the vicinity of the object to be detected increases in accordance with the change in the magnetic permeability. As a result, the oscillation frequency of the oscillation circuit including the coil decreases. Here, when two coils are arranged at different distances from the object to be detected, the inductance of each coil increases, and the oscillation frequency of any oscillation circuit decreases. However, the coil closer to the object to be detected is more affected by the change in the magnetic permeability than the coil farther away. Become. Therefore, a difference corresponding to the degree of change in the magnetic permeability occurs in the oscillation frequency in the two oscillation circuits including the two coils. Thus, since there is a correlation between the difference between both oscillation frequencies and the magnetic permeability, in the present invention, the magnetic permeability of the object to be detected can be detected based on the difference between the oscillation frequencies of both oscillation circuits. Is possible.

  In the embodiment described above, the change in inductance of the two coils (the first coil 1 and the second coil 2) coaxially arranged on the substrate 10 is measured with the accuracy of the oscillator built in the microcomputer (electronic chip 4). Is detected as a difference in oscillation frequency between two oscillation circuits (first oscillation circuit 6 and second oscillation circuit 7) driven by a simple clock signal, and the difference (amount of change in oscillation frequency) is processed by a microcomputer. The change in permeability is detected. Here, the two coils are alternately connected to the oscillation circuit, the oscillation frequency is measured alternately by a microcomputer for a predetermined time, and the difference is calculated to detect the change in the magnetic permeability.

  In the present embodiment, since the first coil 1 and the second coil 2 are coaxially arranged on the upper and lower surfaces of the substrate 10, the area necessary for the arrangement of the coils can be reduced, and the narrowing in the horizontal direction can be achieved. . Further, since the coil is formed by printing the conductor pattern on the substrate 10, the height in the height direction can be reduced. Furthermore, since various processes are performed using a microcomputer, the number of components can be reduced and the area for mounting circuit components can be reduced. From the above, the magnetic flux detector can be significantly downsized.

  In the present embodiment, the coil does not have a core, and the core is not excited during measurement, so that power consumption can be suppressed.

  Since the measurement of the oscillation frequency in the two oscillation circuits is alternately performed, the measurement of the oscillation circuit including one coil is not affected by the magnetic flux generated in the other coil (inductance change in the other coil). Therefore, an accurate oscillation frequency can be measured, and as a result, the magnetic permeability can be detected with high accuracy.

  In this embodiment, since the transistors and capacitors constituting the two oscillation circuits are shared, and the coils are arranged in the oscillation circuits, the number of parts can be reduced and the cost can be reduced. In addition, since the number of parts is small, variations in part characteristics can be reduced, and further accurate measurement is possible without being affected by disturbances such as temperature changes and noise.

  Since various processes are performed by software using a microcomputer, the number of circuit parts as hardware can be reduced and the influence of variations in characteristics of circuit parts is reduced. In addition, since it is processed by software, it is less affected by the environment (temperature, humidity, etc.). Therefore, the accuracy of the detected magnetic permeability can be increased.

  Further, even when the material of the rotating member 100 is changed, it can be dealt with simply by changing the contents of the software. Therefore, mass production of the magnetic flux detection unit 20 becomes easy, and cost reduction can be achieved.

FIG. 7 shows another embodiment of the present invention.
Instead of a rotating member having an uneven outer peripheral surface, a rotating member 150 having an elliptical cross section is used.
Only the shape of the rotating member is changed, and the configuration of the magnetic flux detector 20 is not changed.
Since the magnetic permeability changes with the rotation of the rotating member 150, the change in the magnetic permeability can be detected as the rotation of the rotating member, and the rotation angle, the rotation speed, or the rotation speed can be detected.
FIG. 8 shows still another embodiment of the present invention.
The center of rotation of the ellipse is deviated from the center of gravity of the ellipse.
By rotating the rotating member, the distance between the rotating member 140 and the magnetic flux detector 20 changes.
The magnetic flux detection unit can detect the rotation angle of the rotating member by detecting the change in the distance as the change in the magnetic permeability.
Although the distance in the radial direction from the rotation axis of the rotating member continuously changes, the magnetic permeability is measured every predetermined time, so the outer surface of the rotating member is formed by a plurality of parts having different distances in the radial direction from the rotating axis. Can be considered.

In the present invention, the distance between a part of the rotating member and the magnetic flux detection unit only needs to change with rotation, and is not limited to the embodiment.
For example, the outer peripheral surface of the rotating member may have a triangular convex portion or a semicircular convex portion. Further, the cross-sectional shape of the rotating member itself may be a polygon.
Moreover, even if the rotating member has a circular cross section and magnetic and nonmagnetic materials are alternately arranged on the outer peripheral surface at equal intervals, the rotating member functions as a rotating member.
The rotating member may be plate-shaped or columnar. The distance between the outer surface of the columnar member and the magnetic flux detection unit only needs to change with rotation.
In the present embodiment, a rotating member is provided, and when the rotation of the rotating member is detected but the device that needs to detect the rotation angle has a gear, the gear may be used as the rotating member.
Further, in the rotating member, the number of parts having different distances in the radial direction from the rotating shaft may be appropriately set depending on the measurement accuracy.

In the present invention, the first coil and the second coil are used to detect the magnetic permeability, but at this time, each of the first coil and the second coil may be formed of a plurality of coils.
By configuring with a plurality of coils, the inductance can be increased.
In the present invention, the coil portion and the circuit portion are arranged on a rectangular substrate. However, the coil portion and the circuit portion may be arranged on different substrates, and the coil portion and the circuit portion may be connected by wiring.
At this time, a coil formed on a flexible substrate may be used.
By forming on the flexible substrate, it is possible to realize the arrangement of the coil on the curved surface and the arrangement of only the coil in a place where the circuit portion cannot be arranged in a narrow place.

  The disclosed embodiments should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 1st coil 2 2nd coil 3 Connector 4 Electronic chip 5 Circuit component 6 1st oscillation circuit 7 2nd oscillation circuit 10 Board | substrate 20 Magnetic flux detection part 41 Detection part 42 Calculation part 43 Conversion part 100 140 150 150 Rotating member 110 Rotating shaft 120 Convex part 130 Concave part 160 Case

Claims (4)

A rotating member made of a magnetic material and having a plurality of parts with different radial distances from the rotation axis;
Having a magnetic flux detector for detecting the permeability of the rotating member;
The magnetic flux detector is
A first oscillation circuit that oscillates including a first coil that receives magnetism from the rotating member;
A second oscillation circuit that oscillates including a second coil that receives magnetism from the rotating member;
Measuring means for measuring the oscillation frequency in each of the first oscillation circuit and the second oscillation circuit,
Calculating means for calculating a difference between oscillation frequencies measured by the measuring means;
A conversion means for converting the difference calculated by the calculation means into magnetic permeability;
A rotation angle detection device that detects a change in the distance between a rotation member and a magnetic flux detection unit that changes due to rotation of the rotation member as a change in magnetic permeability, and detects a rotation angle of the rotation member.   The rotation angle detecting device according to claim 1, wherein the rotating member has a cylindrical shape having irregularities on an outer peripheral surface.   The rotation angle detection device according to claim 1, wherein the rotation member is a column having an elliptical cross section. The rotation angle detection device according to claim 3, wherein the rotation center of the rotation member is a position different from the center of gravity of the elliptical cross section.