JP2015125039A - Rotation angle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive rotation angle detector that does not require the incorporation of a circuit for keeping the exciting current and exciting voltage constant.SOLUTION: A part of a circumference facing a teeth 2-1 of a stator 2 on which an excitation coil 3 is wound is formed in a circular arc shape having a constant curvature. When a rotor 1 is rotated in a range of the circumference having the circular arc shape having the constant curvature, the gap between the teeth 2-1 of the stator 2 on which the excitation coil 3 is wound and the circumference of the rotor 1 is kept constant. Thus, without performing a design for keeping the exciting current and exciting voltage constant, the rotation angle of a detection object corresponding to the variation of the gap caused by the rotation of the rotor 1 can be detected.

Description

  The present invention relates to a rotation angle detector that detects a rotation angle of an object to be detected in accordance with a change in a gap with a stator caused by rotation of a rotor.

  Conventionally, for example, a potentiometer has been used to detect the rotation angle of an electric valve actuator. The structure of a general potentiometer consists of resistors, shafts, electrodes and cases and covers that wrap them, and is simple and inexpensive, and has no electronic circuit inside, so it is resistant to noise. There are features. However, the potentiometer has a defect that the resistor and the electrode are always in contact with each other and sliding, and whisker-like noise is generated due to deterioration over time.

  On the other hand, there exists a rotation angle detector called a resolver (see, for example, Patent Document 1). In the resolver shown in Patent Document 1, as shown in FIG. 10, teeth (convex portions) 11 are formed on the inner periphery of an annular stator 10 and arranged in the circumferential direction. A perfectly circular rotor 20 is located, and the rotor 20 rotates about the rotation center O. Four teeth 11 are formed at intervals of 90 °, and an excitation winding and a detection winding (not shown) are wound around these teeth 11.

  The stator 10 and the rotor 20 are made of a magnetic material, and the rotor 20 has a structure having no winding. Then, the shape of the rotor 20 is configured such that the gap permeance between the stator 10 and the rotor 20 changes in a sine wave shape with the rotation of the rotor 20, so that an arbitrary rotation angle within 360 ° of the rotor 20 can be set. Detectable.

JP 2008-164435 A Japanese Patent Laid-Open No. 10-111145

  In the resolver described above, in order to change the output signal in a sine wave form within a range of 360 °, the shape of the rotor is formed by a special curve over the entire circumference, and the stator wound around the exciting winding is wound. The distance between the teeth and the rotor cannot be kept constant. For this reason, the excitation amplifier incorporates a circuit for keeping the excitation current and the excitation voltage constant as shown in Patent Document 2, which is expensive.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide an inexpensive rotation angle detector that does not need to incorporate a circuit for keeping the excitation current and excitation voltage constant. It is in.

  In order to achieve such an object, the present invention includes a rotor made of a magnetic material that rotates in accordance with a change in the angle of a detection target, and a stator made of a magnetic material provided so as to surround the rotor, and the rotation of the rotor In the rotation angle detector that detects the rotation angle of the object to be detected in accordance with the change in the gap between the stator and the stator, the stator has an annular portion that surrounds the rotor, and the inner periphery of the annular portion is at the center of the rotor. Three or more convex portions are provided, and an exciting winding is wound around one of the convex portions, and the rotor has a peripheral edge facing the convex portion of the stator on which the exciting winding is wound. A part is formed in a circular arc shape having the same curvature around the center point of the rotor.

  In the present invention, since a part of the peripheral edge of the rotor facing the convex portion of the stator around which the exciting winding is wound is formed in an arc shape having the same curvature, the range of the arc-shaped peripheral edge having the same curvature When the rotor is rotated, the gap between the convex portion of the stator around which the excitation winding is wound and the peripheral edge of the rotor is kept constant. As a result, in the present invention, it is possible to detect the rotation angle of the detection target in accordance with the change in the gap caused by the rotation of the rotor without making any effort to keep the excitation current and the excitation voltage constant.

  According to the present invention, since a part of the peripheral edge of the rotor facing the convex portion of the stator around which the excitation winding is wound is formed in an arc shape having the same curvature, the circuit for keeping the excitation current and the excitation voltage constant. Therefore, it is possible to reduce the cost.

It is a top view which shows the principal part of one Embodiment of the rotation angle detector which concerns on this invention. It is the top view and sectional drawing of a rotor used for this rotation angle detector. It is a figure explaining the curvature of the external shape (periphery) of this rotor. It is a figure which illustrates the relationship between the rotation angle of a rotor, and output voltage V1 and V2. FIG. 5 is a perspective view showing an example in which an excitation winding and a detection winding are inserted into teeth as an air-core coil. It is a figure which shows the example which made the annular part of the stator into "U" shape. It is a figure which shows the example which used the annular part of the stator as the ring. It is a figure which shows the example which made small the angle of the periphery of the rotor which makes a curvature equal. It is a figure which shows the example which made the cyclic | annular part of the stator into the square ring with which the perimeter was connected. It is a figure which shows the principal part of the resolver shown by patent document 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view showing a main part of an embodiment of a rotation angle detector according to the present invention.

  In FIG. 1, reference numeral 1 denotes a rotor (sensor disk) made of a magnetic material that rotates according to a change in the angle of a detection target, and 2 denotes a stator (pickup) made of a magnetic material provided so as to surround the rotor 1.

  The rotor 1 is provided with a fitting hole 1a that fits a rotation shaft (not shown) to be detected at the center thereof, and rotates according to a change in the angle of the detection object around the point O1. 2A is a plan view of the rotor 1, and FIG. 2B is a cross-sectional view taken along the line II in FIG. 2A.

  Further, the curvature of the circumferential surface of the rotor 1 changes every 120 °. FIG. 3 is a view for explaining the curvature of the circumferential surface of the rotor 1. As shown in FIG. 3, when the x-axis and y-axis with the point O1 as the origin are defined with respect to the rotor 1, and the angle from the x-axis to the counterclockwise direction is θ, −90 ° ≦ θ ≦ 30 ° In the range T1 up to 120 °, the peripheral surface of the rotor 1 (hereinafter referred to as the peripheral edge T1) is a curve 1 having a radius r1 = (1140−2θ) / 120, and 120 ° up to 30 ° ≦ θ ≦ 150 °. In the range T2, the peripheral surface of the rotor 1 (hereinafter referred to as the peripheral edge T2) is a curve 2 having a radius r2 = 9, and in the range T3 up to 150 ° ≦ θ ≦ 270 °, the peripheral surface of the rotor 1 (hereinafter referred to as the peripheral edge T3). Is a curve 3 having a radius r3 = (780 + 2θ) / 120. The units of the radii r1, r2, and r3 are mm, and 1 / r1, 1 / r2, and 1 / r3 are the curvatures of the peripheral edges T1, T2, and T3.

  On the other hand, the stator 2 has an arcuate annular portion 2-0 that surrounds the rotor 1 by providing a defect in a part thereof. That is, when the annular portion 2-0 of the stator 2 is an annular ring, one peripheral end portion 2a and the other peripheral end portion 2b of the annular portion 2-0 are connected, but this connection is not present and is missing. . In the present embodiment, the angle (center angle) of the circular arc around the point O1 of the annular portion 2-0 is 240 °, and the central angle is set to 120 ° between the peripheral end portion 2a and the peripheral end portion 2b. An arc-shaped defect having a degree is provided.

  Further, a first convex portion toward the center O <b> 1 of the rotor 1 is formed at the center of the inner peripheral portion between the one peripheral end 2 a and the other peripheral end 2 b of the annular portion 2-0 of the stator 2. 2-1. Further, on the inner peripheral portion of one peripheral end portion 2a of the stator 2 and the other peripheral edge portion 2b, the second convex portion and the third convex portion toward the center O1 of the rotor 1 are teeth 2-2 and 2-3. It is provided as. The excitation winding 3 is wound around the first tooth 2-1, and the detection windings 4-1 and 4-2 are wound around the second tooth 2-2 and the third tooth 2-3. Has been.

  In this rotational angle detector 100, the rotor 1 is wound around the excitation winding 3 of the stator 2 at the peripheral edge T2 (the peripheral edge T2 having the curvature 1 / r2) which is the curve 2 having the radius r2 at the rotational angle of 0 °. A tooth 2-2 around which a detection winding 4-1 is wound around a peripheral edge T1 (a peripheral edge T1 having a curvature of 1 / r1) which is opposed to the tooth 2-1 being rotated and is a curve 1 having a radius r1. And a peripheral edge T3 (a peripheral edge T3 having a curvature of 1 / r3) which is a curve 3 having a radius r3 is opposed to a tooth 2-3 around which a detection winding 4-2 is wound.

  In the rotation angle detector 100, when the rotor 1 rotates within a range of ± 60 °, the curvature of the peripheral edge T2 of the rotor 1 is all equal to 1 / r2, and therefore the teeth 2-1 of the stator 2 and the rotor 1 The gap between the teeth 2-2 of the stator 2 and the periphery T1 of the rotor 1 and the teeth 2-3 of the stator 2 and the periphery T3 of the rotor 1 are maintained in a state in which the gap between the periphery T2 of the stator 2 is kept constant. The gap between them changes.

  In the rotation angle detector 100, an excitation current is supplied to the excitation winding 3, and output voltages V1 and V2 are obtained from the detection windings 4-1 and 4-2. FIG. 4 illustrates the relationship between the rotation angle of the rotor 1 and the output voltages V1 and V2 obtained from the detection windings 4-1 and 4-2.

  The state shown in FIG. 1 is a case where the rotation angle of the rotor 1 is 0 °, and the output voltages V1 and V2 obtained from the detection windings 4-1 and 4-2 are equal. When the rotor 1 is rotated clockwise, that is, when the rotor 1 is rotated in the direction of + 60 °, the output voltage V1 obtained from the detection winding 4-1 rises and the output voltage obtained from the detection winding 4-2. V2 falls. On the other hand, when the rotor 1 is rotated counterclockwise, that is, when the rotor 1 is rotated in the direction of −60 °, the output voltage V1 obtained from the detection winding 4-1 decreases, and the detection winding 4-2. The output voltage V2 obtained from the above increases.

  In this way, the output voltages V1 and V2 obtained from the detection windings 4-1 and 4-2 are symmetrical with respect to the rotation center (0 °) of the rotor 1, and therefore the difference between the output voltages V1 and V2 Is obtained as ΔV = V1−V2, a linear difference voltage ΔV corresponding to the rotation angle of the detection target can be obtained in the rotation angle range of ± 60 °. In this case, the gap between the teeth 2-1 of the stator 2 and the peripheral edge T2 of the rotor 1 is kept constant in the rotation angle range of ± 60 °. There is no need to do it.

  In an electric valve actuator that controls the flow rate of fluid passing through the ball valve by rotating the valve body of the ball valve, the angle detection range required as an actual opening sensor for detecting the actual opening of the ball valve is 0 ° to 90 °. It is a degree exceeding 0 ° (for example, 105 °, 120 °).

  The rotation angle detector 100 according to the present embodiment specializes in the required angle detection range of such an electric valve actuator, so that one peripheral end 2a of the annular portion 2-0 of the stator 2 and the other peripheral portion are detected. By providing a deficit with the end 2b, that is, because a part of the outer periphery of the stator 2 is not necessary as a magnetic circuit, the annular part 2-0 is not circular but has a deficit in part. The outer shape of the stator 2 is reduced, the size is reduced, and the structure is simplified. Further, by making the curvature of the peripheral edge T2 of the rotor 1 equal, a circuit for keeping the excitation current and the excitation voltage constant is unnecessary, and the cost of the rotation angle detector 100 is reduced. Further, by downsizing the rotation angle detector 100, it is possible to reduce the size of the electric valve actuator itself that mounts the rotation angle detector 100 as an actual opening degree sensor.

  In the present embodiment, the excitation winding 3 and the detection windings 4-1 and 4-2 are independent, and are linearly connected to the teeth 2-1, 2-2, and 2-3 of the stator 2. Since it is arranged, an air-core coil made in advance outside may be inserted without directly winding around the teeth 2-1 and 2-2, 2-3.

  FIG. 5 shows an example in which the excitation winding 3 and the detection windings 4-1 and 4-2 are inserted into the teeth 2-1, 2-2 and 2-3 as air core coils. Even when it is inserted as an air-core coil, the excitation winding 3 and the detection windings 4-1, 4-2 are still wound around the teeth 2-1, 2-2, 2-3.

  In the above-described embodiment, the annular portion 2-0 of the stator 2 has an arc shape, but may have a “U” shape as shown in FIG. Even in the annular portion 2-0 having a “U” shape, a defect is provided between one peripheral end 2a and the other peripheral end 2b, and the outer shape of the starter 2 is reduced by the amount of the defect, Miniaturization is achieved. Further, by making the curvature of the peripheral edge T2 of the rotor 1 equal, the gap between the tooth 2-1 of the stator 2 and the peripheral edge T2 of the rotor 1 is kept constant in a rotation angle range of ± 60 °.

  In the above-described embodiment, the annular portion 2-0 of the stator 2 has an arc shape. However, as shown in FIG. 7, the annular portion 2-0 'may be an annular shape. In this case, the outer shape of the stator 2 is increased, but the curvature of the peripheral edge T2 of the rotor 1 is made equal, so that the teeth 2-1 of the stator 2 and the peripheral edge T2 of the rotor 1 are within a rotation angle range of ± 60 °. The gap between them is kept constant. Therefore, the original purpose of reducing the cost of the rotation angle detector 100 without using a circuit for keeping the excitation current and the excitation voltage constant is achieved.

  In the example shown in FIG. 7, the number of teeth of the stator 2 is not limited to three, and the angle of the peripheral edge T2 of the rotor 1 that makes the curvature equal is not limited to 120 °. For example, when the measurement range is small, as shown in FIG. 8, the angle of the peripheral edge T2 of the rotor 1 is made small, and the positions of the teeth 2-2 and 2-3 are made closer to the teeth 2-1. Also good. Further, as shown as an annular portion 2-0 ″ in FIG. 9, it may be a quadrangular ring with the entire circumference connected instead of a circular ring.

  Moreover, the capacitance type angle sensor according to the present invention is not limited to the electric valve actuator, and can be widely used in an apparatus having a relatively wide application temperature range and no space. In addition, since the structure of the angle detection unit is simple and the gap is guaranteed with the accuracy of a general mold, individual differences can be reduced.

[Extension of the embodiment]
The present invention has been described above with reference to the embodiment. However, the present invention is not limited to the above embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the technical idea of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Rotor (sensor disk), 1a ... Fitting hole, 2 ... Stator (pickup), 2-0, 2-0 ', 2-0 "... Annular part, 2a ... One peripheral edge part, 2b ... The other Peripheral ends, 2-1, 2-2, 2-3 ... teeth (convex parts), 3 ... exciting windings, 4-1, 4-2 ... detecting windings.

Claims (5)

A rotor made of a magnetic body that rotates in response to a change in the angle of the detection target, and a stator made of a magnetic body that is provided so as to surround the rotor. In response to the rotation angle detector for detecting the rotation angle of the detection target,
The stator is
An annular portion surrounding the rotor;
Three or more convex portions toward the center of the rotor are provided on the inner peripheral portion of the annular portion,
An exciting winding is wound around one of the convex portions,
The rotor is
A rotation angle characterized in that a part of a peripheral edge facing the convex portion of the stator around which the exciting winding is wound is formed in an arc shape having an equal curvature centering on the center point of the rotor. Detector. The rotation angle detector according to claim 1, wherein
The circular arc having the same curvature is
The rotation angle detector, wherein the central angle is the maximum measurement angle of the rotation angle detector. The rotation angle detector according to claim 2, wherein
The rotation angle detector is characterized in that the maximum measurement angle of the rotation angle detector is 120 ° or less. In the rotation angle detector as described in any one of Claims 1-3,
The stator is
An annular portion surrounding the entire circumference of the rotor;
A first convex portion directed toward the center of the rotor is provided on an inner peripheral portion of the annular portion;
Second and third convex portions toward the center of the rotor are provided on one and the other side of the first convex portion of the annular inner peripheral portion,
An exciting winding is wound around the first convex portion,
A rotation angle detector, wherein a detection winding is wound on each of the second and third convex portions. In the rotation angle detector as described in any one of Claims 1-3,
The stator is
Having an annular portion surrounding the rotor with a defect in a part thereof,
A first convex portion directed toward the center of the rotor is provided on an inner peripheral portion between one peripheral end portion of the annular portion and the other peripheral end portion;
Second and third convex portions directed to the center of the rotor are provided on the inner peripheral portion of one peripheral end portion and the other peripheral end portion of the annular portion,
An exciting winding is wound around the first convex portion,
A rotation angle detector, wherein a detection winding is wound on each of the second and third convex portions.

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