JP2005207748A - Magnetic induction type rotational position sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic induction type rotational position sensor capable of obtaining a sine wave output by simple constitution. <P>SOLUTION: This sensor has a stator 101 arranged concentrically with a plurality of magnetic pole pins 2, a rotor 105 arranged opposedly under a coaxial condition to the stator 101, a primary side excitation coil 104 arranged in the stator 101, and a secondary side induction coil 103 arranged in the each magnetic pole pin 2. A cross-sectional shape of the each magnetic pole pin 2 is formed into a sector shape around the rotation center 105a of the rotor 105 as the center to change sine-wave-likely an overlap area S of a magnetic substance 106 in the rotor 105 and the each magnetic pole pin 2, in response to a rotation angle position of the rotor 105, and a sine-wave-like irregular patterns are formed in an inner circumferential edge of the magnetic substance in the rotor 105. The sine-wave-like output is obtained from the secondary side induction coil 103, because the overlap area S is changed sine-wave-likely. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic induction type rotational position sensor capable of accurately detecting the rotational position of a rotating body, and more particularly to an improvement of a magnetic pole pin around which a secondary induction coil is wound.

  A rotational position sensor that detects the rotational position of a rotating body using magnetic induction is known as disclosed in Patent Documents 1, 2, and 3 below. In such a magnetic induction type rotational position sensor, an AC signal generated by the primary side excitation coil is received by the secondary side induction coil via the magnetic path, and the magnetic path permeability changes in accordance with the rotational position of the rotor. The contour pattern is set. In general, a sinusoidal shape is adopted for the contour pattern of the rotor, and a magnetic pin having a circular cross section is used for the core of the secondary induction coil.

  FIG. 1A is an explanatory diagram showing a configuration example of the magnetic induction type rotational position sensor having this configuration, and FIG. 1B is an explanatory diagram showing an overlapping area of the rotor and the magnetic pin. In the magnetic induction type rotational position sensor 100, a plurality of circular magnetic pole pins 102 are concentrically mounted on the surface of a disk-shaped stator 101, and a secondary induction coil 103 is wound around each magnetic pole pin 102. ing. For example, four magnetic pole pins 102 are arranged at intervals of 90 degrees, and a pair of secondary-side induction coils 103 facing each other in the diametrical direction are connected in series with each other in the winding direction reversed. Similarly, the remaining set of secondary side induction coils 103 are also connected in series with each other in the reverse winding direction.

  On the stator 101 side, a primary side excitation coil 104 is annularly arranged so as to surround each magnetic pole pin 102. In addition, a disk-shaped rotor 105 is disposed on the surface of the stator 101 so as to face each other in a coaxial state. On the stator side surface of the rotor 105, a ring-shaped magnetic plate 106 made of a magnetic material is fixed in a state facing the magnetic pole pins 102. A rotating shaft (not shown) is fixed to the rotor 105 in a coaxial state. The inner peripheral edge 107 of the magnetic plate 106 of the rotor 105 has a contour shape in which a sinusoidal uneven pattern is repeated along a concentric circle 108 on which the magnetic pole pins 102 are arranged.

When the rotor 105 rotates, the overlapping area (the area of the hatched portion in FIG. 1B) between the magnetic plate 106 of the rotor 105 and each magnetic pole pin 102 changes with the rotation. The amount of magnetic flux generated in the secondary induction coil 103 is approximately proportional to the overlapping area. When the overlapping area changes in a sine wave shape, when a sin ωt excitation voltage is applied to the primary side excitation coil 104, the set of secondary side induction coils 105 generates sin θ · sin ωt according to the rotation angle θ of the rotor 105. From the remaining set of secondary induction coils 105, a voltage of cos θ · sin ωt is obtained. Therefore, a signal representing the rotational position of the rotor 102 can be generated by a signal processing circuit (not shown) based on these two sets of induced voltages. That is, a signal indicating the rotational position of the rotating body to which the rotor 105 is attached can be obtained.
JP-A-9-53909 JP 2000-352501 A JP 2003-42805 A

  However, since the magnetic pole pin having a circular cross section is conventionally used, the change in the overlapping area of the rotor 105 and the magnetic pin due to the rotation of the rotor deviates from the sinusoidal change. Therefore, the change in the amount of magnetic flux passing through the coil generated as the rotor rotates also deviates from the sine wave-like change. This may cause measurement errors.

  It is an object of the present invention to provide a high resolution and high accuracy capable of accurately changing the overlapping area between a magnetic pole pin wound with a secondary induction coil and a rotor having a sinusoidal uneven pattern into a sinusoidal shape. In some cases, a magnetic induction type rotational position sensor is proposed which is advantageous for the realization.

In order to solve the above problems, a magnetic induction type rotational position sensor according to the present invention includes:
A stator,
A rotor disposed coaxially with the stator; and
A plurality of magnetic pole pins arranged concentrically about the rotation center of the rotor on the surface of the stator facing the rotor;
A primary excitation coil disposed on the stator or each magnetic pin;
A secondary induction coil arranged on each magnetic pole projection,
The cross-sectional shape of each magnetic pin is a sector shape with a predetermined angle around the rotation center, or a rectangular shape with both sides parallel to a diameter line passing through the rotation center,
The rotor has a contour shape in which a concavo-convex pattern is repeated in a sinusoidal shape along a concentric circle in which the magnetic pin is arranged,
The rotational position of the rotor is detected based on a change in the magnetic coupling state between the primary side excitation coil and the secondary side induction coil caused by a change in the overlapping area of the rotor and each magnetic pin. Yes.

  In the magnetic induction type rotational position sensor of the present invention, the magnetic pole pin around which the secondary induction coil is wound has a fan-shaped or rectangular cross-sectional shape. Therefore, the overlapping area of the magnetic pole pin and the rotor having a contour in which the sinusoidal uneven pattern is repeated changes substantially in a sinusoidal manner as the rotor rotates. Since the amount of magnetic flux induced to the magnetic pin is proportional to the overlapping area, a sinusoidal output signal can be obtained with high accuracy. Therefore, according to the present invention, a magnetic induction type rotational position sensor advantageous for high resolution and high accuracy can be realized with a simple configuration in which the cross-sectional shape of the magnetic pole pin is devised.

  An example of a magnetic induction type rotational position sensor to which the present invention is applied will be described below with reference to the drawings.

  The basic configuration of the magnetic induction type rotational position sensor of this example is the same as that of the conventional one shown in FIG. FIG. 2 shows a cross-sectional shape of the magnetic pole pin 2 of the magnetic induction type rotational position sensor 1 of this example. The magnetic pole pin 2 has a fan-shaped cross section with a predetermined angle centered on the rotation center 105 a of the rotor 105.

Here, the sinusoidal uneven pattern formed on the inner peripheral edge of the magnetic plate 106 of the rotor 105 is formed along a concentric circle 108 on which the magnetic pole pins 2 are arranged. Since the influence of the curvature of the concentric circle 108 on the overlapping area is small and can be ignored, it is assumed that the center line of the sinusoidal uneven pattern is a straight line, and the overlapping area of the magnetic pole pin 2 and the rotor 105 is two. It is assumed that it is proportional to the output of the secondary induction coil 103. In this case, since the shape of the magnetic pole pin 2 is a rectangle whose left and right sides are parallel to the diameter line L passing through the center 105a and the width is constant, the sinusoidal curve y representing the uneven pattern in the graph of FIG. As described above, if the point x1 to the point x2 are definitely integrated, the overlapping area S can be obtained (the width of the magnetic pin = x2−x1).

  Therefore, it can be seen that the overlapping area S becomes a perfect sine wave, and the output of the secondary induction coil 103 becomes a perfect sine wave. As described above, since the influence on the overlapping area S by neglecting the curvature is slight, if the magnetic pin 2 having a fan-shaped cross section or a rectangular cross section is used, a sine wave output can be accurately obtained from the secondary induction coil. Can do. Therefore, a magnetic induction type rotational position sensor advantageous for high resolution and high accuracy can be realized by a simple configuration using a magnetic pin having a sector cross section or a rectangular cross section.

  In the case of a conventional circular magnetic pole pin, generally, a cylindrical magnetic pole pin is processed and positioned in an assembly operation. The positioning accuracy is determined by the combination of the dimensions of the parts used for assembly, and the positioning accuracy may deteriorate. On the other hand, when using a magnetic pin with a fan-shaped cross section, if the magnetic pin is formed by milling after being processed into a ring shape, the position of the magnetic pin is determined by a single component, thus improving the positional accuracy. The effect of improving the error accuracy due to machining variations can be obtained. In addition, since a part of the magnetic path can be processed at the same time, an effect of reducing the number of parts can be obtained.

(A) is explanatory drawing which shows the structure of the conventional magnetic induction type rotational position sensor, (b) is explanatory drawing which shows the overlapping state of a rotor and a magnetic pole pin. It is explanatory drawing which shows the overlap state of the rotor and magnetic pole pin in the magnetic induction type rotational position sensor to which this invention is applied. It is a graph which shows the calculation method of the overlapping area of the rotor and magnetic pole pin in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic induction type rotation position sensor 2 Magnetic pole pin 101 Stator 103 Secondary side induction coil 104 Primary side excitation coil 105 Rotor 105a Rotation center 106 Magnetic body 107 Inner peripheral edge 108 of magnetic body S Concentric circle S The overlapping area of a magnetic pole pin and a rotor

Claims (1)

A stator,
A rotor disposed coaxially with the stator; and
A plurality of magnetic pole pins arranged concentrically about the rotation center of the rotor on the surface of the stator facing the rotor;
A primary excitation coil disposed on the stator or each magnetic pin;
A secondary induction coil arranged on each magnetic pole projection,
The cross-sectional shape of each magnetic pin is a sector shape with a predetermined angle around the rotation center, or a rectangular shape with both sides parallel to a diameter line passing through the rotation center,
The rotor has a contour shape in which a concavo-convex pattern is repeated in a sinusoidal shape along a concentric circle in which the magnetic pin is arranged,
Magnetic induction type rotation in which the rotational position of the rotor is detected based on a change in the magnetic coupling state between the primary side excitation coil and the secondary side induction coil caused by a change in the overlapping area of the rotor and each magnetic pin Position sensor.

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