JP2005181252A - Magnetic rotary position sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce linear error of detection magnetic flux density of a magnetoelectric conversion element. <P>SOLUTION: First and second semi-cylindrical magnets 32a and 32b are oppositely arranged on the inner face of a cylindrical yoke 31 comprising a soft magnetic material. Each of the magnets 32a and 32b is magnetized so that N and S poles are opposed in an inner circumferential face. Magnetic sensors 33a and 33b are arranged in a space formed by the magnets 32a and 32b. When the magnetic sensors 33a and 33b are assumed as a circle taking as a center the center of the yoke 31, they are arranged at an interval of 180° on a circumference. A square magnetic piece 34 is arranged at the center part of a circumferential length of the magnets 32a and 32b, and magnetic permeability of the center part of the circumferential length of the magnets 32a and 32b is enlarged. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic rotary position sensor that detects an absolute position of a rotation angle as an electrical output in a non-contact manner by using a magnetoelectric conversion element that converts a change in magnetic flux into a voltage.

  Japanese Patent Application No. 2003-285194, which is a prior application, is a magnetic rotary position sensor that detects an absolute position of a rotation angle as an electrical output in a non-contact manner using a magnetoelectric transducer that converts a change in magnetic flux into a voltage. There is a magnetic rotary position sensor described in a document.

  FIG. 5 is a diagram showing the basic configuration of the magnetic rotary position sensor described in the specification of the above-mentioned prior application. As shown in the figure, semi-cylindrical first and second magnets 2a and 2b having an arc angle α (α ≦ 180 °) are arranged to face each other on the inner surface of a cylindrical yoke 1 made of a soft magnetic material. Each of the magnets 2a and 2b is magnetized so that the N and S poles face the inner peripheral surface. Further, when the magnetic sensor 3 is arranged in a space formed by the magnets 2a and 2b, and the magnetic sensor 3 considers a circle having a center at the center O of the yoke 1 and a radius r, the tangential direction of the circumference of the circle The radius r is at least 1/2 of the outer dimension width w of the magnetic sensor 3. The yoke 1 rotates with respect to the magnetic sensor 3 with the center O as the center of rotation.

  In this magnetic rotary position sensor, in the state shown in FIG. 5, there is no magnetic flux component intersecting at right angles to the magnetic sensing surface of the magnetic sensor 3, and the yoke 1 is rotated ± 90 ° from the state shown in FIG. Sometimes, the magnetic flux component intersecting at right angles to the magnetic sensitive surface of the magnetic sensor 3 becomes the largest. In other words, if the fact that the magnetic field in the cylinder does not become a parallel magnetic field and becomes slightly curved as it goes away from the center is actively used, the radius r and the arc angle α can be appropriately selected to detect the magnetic sensor 3. The magnetic flux density can be linearly approximated.

  In such a magnetic rotary position sensor, there is no magnetic material in the space formed by the magnets 2a and 2b, and only air, so no hysteresis phenomenon occurs. Further, when considering a circle centered on the center O of the yoke 1 and having a radius r of a value of 1/2 or more of the outer dimension width w of the magnetic sensor 3, the magnetic field component in the tangential direction of the circumference of the circle is detected. Since the magnetic sensor 3 is disposed at the position where the magnetic sensor 3 is positioned, the detection error is reduced over a wide range of the rotation angle θ of the yoke 1 relative to the magnetic sensor 3.

  FIG. 6 is a diagram for explaining the operation of the magnetic rotary position sensor shown in FIG. 5. FIG. 6A is a graph showing the relationship between the rotation angle θ and the detected magnetic flux density in the magnetic rotary position sensor shown in FIG. a represents the change in the absolute value of the amount of magnetic flux passing through the detection unit of the magnetic sensor 3, and the curve b represents the change in the actual detected magnetic flux density of the magnetic sensor 3 (note that both the rotation angle θ and the detected magnetic flux density are positive). The curves a and b overlap in the region where FIGS. 5B to 5D are views showing the positional relationship between the magnets 2a and 2b of the magnetic rotary position sensor shown in FIG. 5 and the magnetic sensor 3, and FIG. The state of the angle θmin is shown, (c) shows the state where the rotational angle θ is 0, and (d) shows the state where the rotational angle θ is the maximum detected rotational angle θmax. As shown in FIG. 6A, the curve a indicating the change in the absolute value of the amount of magnetic flux passing through the detection unit of the magnetic sensor 3 is symmetric with respect to the vertical axis. Since 1 rotates, the polarity of the detection part of the magnetic sensor 3 is reversed when the rotation angle θ is 0, and the change in the actual detected magnetic flux density of the magnetic sensor 3 is as shown by the curve b. Therefore, an inflection point appears at the position where the rotation angle θ is 0, and an error of the actual detected magnetic flux density of the magnetic sensor 3 with respect to the ideal detected magnetic flux density of the magnetic sensor 3 indicated by the approximate line c, that is, a linear error occurs. .

  Further, a magnetic rotary position sensor described in the specification of Japanese Patent Application No. 2003-321534, which is a prior application, has been considered.

  FIG. 7 is a diagram showing a basic configuration of the magnetic rotary position sensor described in the specification of the above-mentioned prior application. As shown in the figure, semi-cylindrical first and second magnets 12a and 12b are arranged opposite to the inner surface of a cylindrical yoke 11 made of a soft magnetic material, and each of the magnets 12a and 12b has an inner peripheral surface. Are magnetized so that the N and S poles face each other. Further, when the magnetic sensors 13a and 13b are arranged in the space formed by the magnets 12a and 12b, and the magnetic sensors 13a and 13b are considered to be a circle centered on the center of the yoke 11, the tangential direction of the circumference of the circle The center line of the magnetic sensor 13 a coincides with the center line of the magnetic sensor 13 b, and the center lines of the magnetic sensors 13 a and 13 b pass through the center of the yoke 11. The yoke 1 rotates with respect to the magnetic sensors 13a and 13b with the center of the yoke 11 as the center of rotation. Moreover, the square protrusion part 14 which protruded inside is provided in the center part of the circumferential length of magnet 12a, 12b, and the magnetomotive force of the center part of the circumferential length of magnet 12a, 12b is large.

  In this magnetic rotary position sensor, the protrusion 14 is provided at the center of the circumference of the magnets 12a and 12b, and the magnetomotive force at the center of the circumference of the magnets 12a and 12b is increased. It is possible to compensate for an insufficient amount of magnetic flux when the rotation angle θ is high and the magnetic flux does not easily pass around 0 °. For this reason, the linear error at the center of the detection angle range of the detected magnetic flux density of the magnetic sensors 13a and 13b can be reduced.

  FIG. 8 is a diagram showing a basic configuration of another magnetic rotary position sensor described in the specification of the above-mentioned prior application, wherein (a) is a diagram showing the basic configuration itself, and (b) is a magnet 21b (21a). (B) A-C position corresponds to (A) A-C position. As shown in the figure, semi-cylindrical first and second magnets 21a and 21b are arranged to face the inner surface of a cylindrical yoke 11, and each of the magnets 21a and 21b has N and S poles on the inner peripheral surface. Are magnetized so as to face each other. Magnetic sensors 13a and 13b are arranged in a space formed by the magnets 21a and 21b. In addition, the magnetizing amount at the central portion of the circumferential length of the magnets 21a and 21b is large, and the magnetomotive force at the central portion of the circumferential length of the magnets 21a and 21b is large.

  Also in this magnetic rotary position sensor, the amount of magnetization at the center of the circumference of the magnets 21a and 21b is large, and the magnetomotive force at the center of the circumference of the magnets 21a and 21b is large. The linear error at the center of the detection angle range of the detected magnetic flux density of the magnetic sensors 13a and 13b can be reduced.

  Patent Documents 1 and 2 can be cited as documents describing this type of prior art.

US Pat. No. 5544000 US Pat. No. 5,789,917

  However, in the magnetic rotary position sensor shown in FIG. 5, the linear error at the center of the detection angle range of the detected magnetic flux density of the magnetic sensor 3 cannot be reduced. Further, in the magnetic rotary position sensor shown in FIGS. 7 and 8, since the shape of the magnets 12a and 12b and the magnetization distribution of the magnets 21a and 21b are special, the magnet orientation, the magnetizing yoke, and the magnetizing method Therefore, it is necessary to manufacture a dedicated mold, a magnetized yoke, etc., which requires a lot of manufacturing time and increases the manufacturing cost.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a magnetic rotary position sensor with a small linear error in the detected magnetic flux density of the magnetoelectric transducer.

  In order to achieve this object, in the present invention, the first and second magnets, which are semi-cylindrical on the inner surface of the cylindrical yoke and magnetized so that the N and S poles face each other, face each other. Arranged in a magnetic field generated by the first and second magnets, the magnetoelectric conversion element rotating with respect to the first and second magnets, the center of the yoke and the magnetoelectric conversion element The magnetoelectric transducer is arranged at a position where a magnetic field component in the tangential direction of the circumference of the circle is detected when considering a circle having a radius of ½ or more of the outer dimension width of the first, second, 2. Increase the magnetic permeability at the center of the circumferential length of the magnet.

  In this case, you may arrange | position a magnetic material piece in the center part of the circumferential length of the said 1st, 2nd magnet.

  In the magnetic rotary position sensor according to the present invention, the magnetic permeability at the central portion of the circumferential length of the first and second magnets is large. Therefore, the linear error of the detected magnetic flux density at the central portion of the detection angle range of the magnetoelectric transducer is calculated. Can be small.

  FIG. 1 is a diagram showing a basic configuration of a magnetic rotary position sensor according to the present invention. As shown in the figure, semi-cylindrical first and second magnets 32a and 32b are arranged opposite to the inner surface of a cylindrical yoke 31 made of a soft magnetic material, and each of the magnets 32a and 32b has an inner peripheral surface. Are magnetized so that the N and S poles face each other. Further, magnetic sensors 33a and 33b are disposed in a space formed by the magnets 32a and 32b, and the magnetic sensors 33a and 33b are disposed in a magnetic field generated by the magnets 32a and 32b. Further, when considering a circle centered on the center of the yoke 31, the magnetic sensors 33a and 33b are arranged at positions where the magnetic field component in the tangential direction of the circumference of the circle is detected. The center line of the magnetic sensor 33 b coincides with the center line of the magnetic sensor 33 b, and the center line of the magnetic sensors 33 a and 33 b passes through the center of the yoke 31. That is, two magnetic sensors 33a and 33b are arranged at intervals of 180 degrees on the circumference. Further, the radius of the circle is 1/2 or more of the outer dimension width of the magnetic sensors 33a and 33b. The yoke 31 rotates with respect to the magnetic sensors 33a and 33b with the center of the yoke 31 as the rotation center. In addition, a rectangular magnetic material piece 34 is disposed on the inner side of the circumferential length of the magnets 32a and 32b, and the permeability of the circumferential length of the magnets 32a and 32b is increased.

  In this magnetic rotary position sensor, a magnetic material piece 34 is disposed at the center of the circumferential length of the magnets 32a and 32b, and the magnetic permeability at the center of the circumferential length of the magnets 32a and 32b is increased so that the magnetic resistance is increased. Therefore, the configuration shown in FIG. 5 can compensate for an insufficient amount of magnetic flux where the rotation angle θ is difficult to pass through in the vicinity of 0 °. For this reason, the absolute value of the amount of magnetic flux passing through the detectors of the magnetic sensors 33a and 33b can be increased when the rotation angle θ is around 0 °, so that the absolute value of the amount of magnetic flux passing through the detectors of the magnetic sensors 33a and 33b is increased. Since the curve indicating the change in value can be made closer to a straight line when the rotation angle θ is around 0 °, the linear error at the center of the detection angle range of the detected magnetic flux density of the magnetic sensors 33a and 33b can be reduced. Further, since it is not necessary to specialize the shape and magnetization distribution of the magnets 33a and 33b, there is no need to manufacture a dedicated mold, a magnetizing yoke, etc., for example, a sheet-molding type magnet can be used. , Manufacturing time is shortened and manufacturing cost is reduced. Further, since the linear error can be reduced by adjusting the magnetic permeability depending on the shape and arrangement of the magnetic material piece 34, the trimming performed by the contact type position sensor (the resistor of the contact type position sensor is connected to the output voltage). The magnetic material pieces 34 can be arranged while observing the linearity of the output voltage, and the shape processing of the magnetic material pieces 34 can be easily performed. Can be done. Further, since the two magnetic sensors 33a and 33b are arranged at intervals of 180 degrees on the circumference, it is monitored that the sum of the outputs of the magnetic sensors 33a and 33b is constant, and the magnetic sensors 33a and 33b It can be confirmed that it is functioning normally.

  2 shows that the outer diameters of the yokes 1, 11, and 21 are 20 mm, the inner diameter is 15 mm, the thicknesses of the magnets 2a, 2b, 12a, 12b, 32a, and 32b are 2 mm, the arc angle α is 166 °, and the magnetic sensors 3, 13a, The distance from the center of the yokes 1, 11, and 31 at the center of 13 b, 33 a, and 33 b is 2.72 mm, the width a of the protrusion 14 is 0.5 mm, the radial length b is 0.7 mm, and the magnetic material piece 34 5 is a graph showing the relationship between the rotation angle θ and the linear error when the width a is 0.7 mm and the radial length b is 0.68 mm, and the curve a is the magnetic rotary position of the prior application shown in FIG. The case of the sensor is shown, the curve b shows the case of the magnetic rotary position sensor of the prior application shown in FIG. 7, and the curve c shows the case of the magnetic rotary position sensor of the present invention shown in FIG. As apparent from FIG. 2, when the magnetic material piece 34 is arranged, the linear error at the center of the detection angle range of the detected magnetic flux density of the magnetic sensors 33a and 33b is compared with the case where the magnetic material piece 34 is not arranged. The linear error when the rotation angle θ of the magnetic flux density detected by the magnetic sensors 33a and 33b is around 0 ° (−20 to 20 °) is made smaller than when the protrusion 14 is provided. be able to.

  FIG. 3 is a diagram showing a basic configuration of another magnetic rotary position sensor according to the present invention. As shown in the drawing, a circular magnetic material piece 35 is disposed on the inner side of the circumferential length of the magnets 32a and 32b, and the permeability of the circumferential length of the magnets 32a and 32b is increased. .

  FIG. 4 is a diagram showing a basic configuration of another magnetic rotary position sensor according to the present invention. As shown in the figure, a V-shaped magnetic material piece 36 is disposed on the inner side of the circumferential length of the magnets 32a and 32b, and the magnetic permeability of the circumferential length of the magnets 32a and 32b is increased. .

  Also in the magnetic rotary position sensor shown in FIGS. 3 and 4, the magnetic material pieces 35 and 36 are arranged at the center of the circumference of the magnets 32a and 32b, and the center of the circumference of the magnets 32a and 32b is arranged. Since the magnetic permeability is increased, the linear error at the center of the detection angle range of the detected magnetic flux density of the magnetic sensors 33a and 33b can be reduced. In addition, since it is not necessary to manufacture a dedicated mold, a magnetized yoke, etc., the manufacturing time is shortened and the manufacturing cost is reduced.

  As the magnetic sensors 33a and 33b, magnetoelectric conversion elements such as Hall effect sensors, magnetoresistance effect sensors, and MI (Magneto-impedance) sensors can be used. A programmable Hall IC that uses a Hall element in the magnetic sensing section and has an integrated AD conversion, DSP, DA conversion circuit, etc. has been developed for such applications. Gain adjustment that determines the relationship between the magnetic field, the function of changing the polarity of the magnetic field and the polarity of the output voltage, or the temperature compensation function that cancels the change in the magnetic characteristics of the magnet due to temperature change, etc. are built-in, and they are programmable Therefore, it is the easiest to use at present, and gain setting and magnet temperature correction can be easily performed.

  Further, in the above-described embodiment, the square magnetic material piece 34, the round magnetic material piece 35, and the V-shaped magnetic material piece 36 are arranged as the magnetic material pieces, but other magnetic material pieces may be arranged. Good.

It is a figure which shows the basic composition of the magnetic type rotary position sensor which concerns on this invention. 8 is a graph showing a relationship between a rotation angle θ and a linear error of the magnetic rotary position sensor shown in FIGS. 1, 5, and 7. It is a figure which shows the basic composition of the other magnetic rotary position sensor which concerns on this invention. It is a figure which shows the basic composition of the other magnetic rotary position sensor which concerns on this invention. It is a figure which shows the basic composition of the magnetic rotary position sensor of a prior application. It is operation | movement explanatory drawing of the magnetic type rotary position sensor shown in FIG. It is a figure which shows the basic composition of the magnetic type rotary position sensor of other prior applications. It is a figure which shows the basic composition of the magnetic type rotary position sensor of other prior applications.

Explanation of symbols

31 ... Yoke 32a ... first magnet 32b ... second magnet 33a ... magnetic sensor 33b ... magnetic sensor 34 ... magnetic material piece 35 ... magnetic material piece 36 ... magnetic material piece

Claims (2)

  The first and second magnets are arranged so as to face each other in a semi-cylindrical manner on the inner surface of the cylindrical yoke and are magnetized so that the N and S poles face each other. The magnetoelectric conversion element that rotates relative to the first and second magnets is disposed in the magnetic field generated by the above, and has a value that is at least a half of the outer dimension width of the magnetoelectric conversion element centered on the center of the yoke. When considering a circle having a radius, the magnetoelectric conversion element is disposed at a position where a magnetic field component in the tangential direction of the circumference of the circle is detected, and the central portion of the circumferential length of the first and second magnets is transparent. Magnetic rotary position sensor with increased magnetic susceptibility.   2. The magnetic rotary position sensor according to claim 1, wherein a magnetic material piece is disposed at the center of the circumferential length of the first and second magnets.

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