JPH09292204A - Rotation angle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized simply worked rotation angle detector by detecting discharge current flowing between a discharge electrode and a flat- plane-like electrode by means of a detecting circuit. SOLUTION: When higher voltage than that of an electric power source 8 for discharge is impressed between a needle-like dischatge electrode 3 and a flat-plane-like electrode 6, corona discharge is generated between the electrode 3 and the electrode 6, and discharge current is detected by a detecting circuit 7. When a rotor 1 is rotated and the electrode 3 together with a supporting member 2 are rotated, the distance between the electrode 6 and the electrode 3 is changed according to the rotation angle of the rotor 1, and the discharge current value is changed according to change of the distance. When relation of the discharge current value and the distance between the electrode 6 and the electrode 3 is known, because relation of the distance between the electrode 6 and the electrode 3 to the rotation angle of the rotor 1 is fixed, the rotation angle can be obtained from the discharge current value through a signal generating means generating a rotation angle signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detector for detecting the rotation angle of a rotating body by using corona discharge.

[0002]

2. Description of the Related Art Conventionally, for detecting the rotation angle of a rotating body by using corona discharge, for example, as shown in FIG.
A device in which the discharge pulse is counted to detect the rotation angle is disclosed (for example, Japanese Patent Laid-Open No. 54-2864).
No. 8). In the figure, 10 is a rotating body to be measured, such as a motor shaft, 20 is an insulating disk fixed to the rotating body 10, and 30 are formed on concentric circles near the outer circumference of the insulating disk 20 at equal intervals and with the same width. A plurality of slits, 40 is a plate-like conductor provided on one side of the insulating disc 20 so as to sandwich the slit 30, and 50 is a needle provided opposite to the plate-like conductor 40 with the slit 30 in between. -Shaped discharge electrode, 60 is a discharge power source composed of a DC power source, 70 is a load resistance, and 80 is an amplifier circuit for amplifying the output voltage. With such a configuration, when a high voltage is applied to the needle-shaped discharge electrode 50 from the power source 60 for discharge to cause corona discharge, the discharge current flows through the slit 30 formed in the insulating disk 20 to the plate-shaped conductor 40. Is detected. Since the insulating disk 20 rotates integrally with the rotating body 1, a pulse-like output characteristic in which the interval becomes narrower as the rotation speed increases is obtained, and the rotation angle or the number of rotations is detected from the output characteristic.

[0003]

However, in the above prior art, since it is necessary to provide the insulating disk with slits having a large number of fine widths at equal intervals in the circumferential direction, the diameter of the insulating disk becomes large. In addition, there are problems that the processing cost is high, such as the slit processing is performed by using a photolithography technique, and that miniaturization is difficult. It is an object of the present invention to provide a rotation angle detector that is small and easy to process.

[0004]

In order to solve the above-mentioned problems, the present invention is based on a discharge amount detecting means for detecting a discharge amount varying according to a rotation angle of a rotating body, and an output of the discharge amount detecting means. In a rotation angle detector provided with a signal generating means for generating a rotation angle signal of the rotating body, the discharge amount detecting means is supported by a supporting member having a sharp tip and capable of rotating integrally with the rotating body. A discharge electrode, a flat electrode inclined with respect to the rotation axis and facing the discharge electrode through a gap, a discharge power supply for supplying a discharge current to the discharge electrode and the flat electrode, A detection circuit for detecting a discharge current flowing between the discharge electrode and the planar electrode is provided. Further, the planar electrode has a fan shape in which the surface of the swash plate is divided into at least two parts with a diameter passing through the axis of the rotating body. The discharge amount detecting means includes a swash plate that is inclined and fixed with respect to the rotator, a ring-shaped planar electrode provided on the surface of the swash plate, and a circumference around the rotator. And three or more discharge electrodes arranged at equal intervals in the direction, and a support arranged so that the tip of the discharge electrode faces the plane electrode and is on a plane perpendicular to the rotation axis of the rotating body. A member, a discharge power supply for supplying a discharge current to the discharge electrode and the planar electrode, and a detection circuit for detecting a discharge current flowing between the discharge electrode and the planar electrode. .

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to embodiments shown in the drawings. 1 is a perspective view showing a first embodiment of the present invention, and FIG. 2 is a block diagram. In the figure, 1 is a rotating body to be measured such as a motor shaft, 2 is a support member made of a disk-shaped insulator fixed to the rotating body 1, and 3 is a needle-shaped discharge fixed to the support member 2. The electrodes are extended downward in parallel with the axial direction of the rotating body 1, and the tips are sharply pointed.
Reference numeral 4 denotes a slip ring fixed to the rotating body 1 so as to supply current while rotating to the discharge electrode 3. Reference numeral 5 denotes a swash plate made of an insulating material, which is inclined with respect to the axial direction of the rotating body 1, and therefore is also inclined and opposed to the support member 2 and fixed to a fixed portion such as a frame. Reference numeral 6 denotes a planar electrode made of a conductive material provided on a surface of the swash plate 5 facing the support member 2. The surface of the swash plate 5 is divided into two by a diameter passing through the axis of the rotating body 1 and is a semicircular electrode 6a. It consists of 6b. Reference numeral 7 (7a, 7b) is a detection circuit for detecting a discharge current discharged between the discharge electrode 3 and the planar electrode 6, which is connected to each of the semicircular electrodes 6a, 6b to generate a known rotation angle signal (not shown). The angle signals a and b are output via the signal generating means. Reference numeral 8 denotes a discharge power source composed of a DC power source, the negative side of which is connected to the discharge electrode 3 via the slip ring 4 and the positive side of which is connected to the detection circuit 7.
The flat electrode 6 may be a metal plate attached to the swash plate 5,
You may form with the metal film by plating etc.

With such a configuration, the needle-shaped discharge electrode 3
5 to 10 kV from the discharge power source 8 between the flat electrode 6 and the flat electrode 6.
When a high voltage is applied, a corona discharge is generated between the discharge electrode 3 and the planar electrode 6, and the discharge current is detected by the detection circuit 7 (7a, 7b). When the rotating body 1 rotates and the discharge electrode 3 rotates together with the support member 2, the planar electrode 6 provided on the swash plate 5 is inclined with respect to the support member 2 parallel to the rotation surface of the discharge electrode 3, As shown in FIG. 3, the distance between the planar electrode 6 and the discharge electrode 3 changes according to the rotation angle of the rotating body 1, and further, the distance between the planar electrode 6 and the discharge electrode 3 changes. The discharge current value changes accordingly. If the relationship between the discharge current value and the distance between the planar electrode 6 and the discharge electrode 3 is known, the relationship between the distance between the planar electrode 6 and the discharge electrode 3 and the rotation angle of the rotating body 1 is constant. Therefore, through a signal generating means for generating a known rotation angle signal (not shown),
The rotation angle can be obtained from the discharge current value. Also,
The planar electrode 6 is divided into two in the circumferential direction and is divided into semicircular electrodes 6a, 6
Since b is formed, the direction of rotation can be known by detecting the increasing or decreasing tendency of the discharge current of the semicircular electrodes 6a, 6b by the detection circuits 6a, 6b. In addition, the planar electrode 6 is not limited to being divided into two,
It may be a fan-shaped electrode divided into a plurality of parts each having a diameter passing through the axis of the rotating body 1.

FIG. 4 is a perspective view showing the second embodiment, and FIG. 5 is a block diagram. In this case, the swash plate 5 is fixed to the rotating body 1 by inclining it by a predetermined angle, and a ring-shaped planar electrode 6 is provided on the surface thereof. The discharge electrode 3 is composed of three discharge electrodes 3a, 3b, 3c arranged at a position divided into three equal parts around the rotating body 1, that is, at a pitch of 120 °. The discharge electrodes 3a, 3b, 3c are supported, and the tips of the discharge electrodes 3a, 3b, 3c are arranged so as to be on a plane perpendicular to the axial direction of the rotating body 1, and are opposed to the planar electrode 6 with a gap. . In addition, each discharge electrode 3
The a, 3b, and 3c are connected to one side terminal of the discharge power source 8 via the detection circuits 7a, 7b, and 7c, respectively, and the planar electrode 6 is connected to the other side terminal of the discharge power source 8. With such a configuration, when a high frequency high voltage is applied between the discharge electrodes 3a, 3b, 3c and the planar electrode 6, a discharge is generated between the discharge electrodes 3a, 3b, 3c and the planar electrode 6, Each of the detection circuits 7a, 7b, 7c has a discharge electrode 3
The discharge currents flowing in a, 3b and 3c are detected. When the rotator 1 rotates, the flat electrode 6 is provided on the surface of the swash plate 5, so that the distance between the discharge electrodes 3a, 3b, 3c and the flat electrode 6 changes, and the change in the distance changes. The discharge current value also changes accordingly. The rotation angle and the rotation direction can be known by comparing the phases of changes in the discharge current value. In the above embodiment, an example in which three discharge electrodes are provided has been described, but a plurality of discharge electrodes of three or more may be provided.

[0008]

As described above, according to the present invention, the discharge current value changes depending on the rotation angle of the rotating body simply by providing the planar electrode inclined with respect to the plane including the tip of the discharge electrode. Therefore, it is possible to obtain the rotation angle and the rotation direction from the change in the discharge current without requiring a lot of trouble such as machining fine slits in the support member at equal intervals, and the size is small. This has the effect of providing a rotation angle detector that is extremely easy to process.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a first exemplary embodiment of the present invention.

FIG. 3 is a block diagram showing a relationship between a discharge current and a rotation angle according to an embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration of a second exemplary embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a conventional example.

[Explanation of symbols]

1: Rotating body, 2: Support member, 3, 3a, 3b, 3c: Discharge electrode, 4: Slip ring, 5: Swash plate, 6: Planar electrode, 6a, 6b: Semicircular electrode, 7, 7a, 7b , 7c: Detection circuit, 8: Power supply for discharge

Claims (3)

[Claims] 1. A discharge amount detecting means for detecting a discharge amount that changes corresponding to a rotation angle of a rotating body, and a signal generating means for generating a rotation angle signal of the rotating body from an output of the discharge amount detecting means. In the rotation angle detector provided, the discharge amount detecting means has a sharp tip, and a discharge electrode supported by a supporting member that can rotate integrally with the rotating body, and is inclined with respect to the rotating shaft, And a planar electrode facing the discharge electrode via a gap, a discharge power supply for supplying a discharge current to the discharge electrode and the planar electrode, and a discharge current flowing between the discharge electrode and the planar electrode. And a detection circuit for detecting the rotation angle. 2. The rotation angle detector according to claim 1, wherein the planar electrode has a fan shape in which the surface of the swash plate is divided into at least two parts by a diameter passing through the axis of the rotating body. 3. A discharge amount detecting means for detecting a discharge amount that changes corresponding to a rotation angle of the rotating body, and a signal generating means for generating a rotation angle signal of the rotating body from an output of the discharge amount detecting means. In the rotation angle detector provided, the discharge amount detecting means includes a swash plate fixed at a predetermined angle with respect to the rotating body, a ring-shaped planar electrode provided on a surface of the swash plate, and the rotation. Three or more discharge electrodes arranged at equal intervals in the circumferential direction around the body, and a tip of the discharge electrodes on a plane facing the planar electrode and perpendicular to the rotation axis of the rotating body. A supporting member arranged so as to form a discharge, a discharge power supply for supplying a discharge current to the discharge electrode and the planar electrode, and a detection circuit for detecting a discharge current flowing between each discharge electrode and the planar electrode. A rotation angle detector comprising: