JP2005091013A - Magnetic type rotary position sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce linear error of detected magnetic flux density of magneto-electro conversion element. <P>SOLUTION: In the center of a cylindrical yoke 11 consisting of a soft magnetic material, a first, a second half-cylindrical magnets 12a, 12b are arranged face to face. Each magnet 12a, 12b is magnetized so that N and S poles are face to face on the inner circumferential surface. Magnetic sensors 13a, 13b are arranged in a space formed with the magnets 12a, 12b. The magnetic sensors 13a, 13b are arranged on the positions for detecting magnetic component in the tangential direction of the circumference of the circle supposing around the yoke 11 in the center, and the magnetic sensors 13a, 13b are arranged with an interval of 180 degrees on the circumference. A rectangular projection 14 is provided in the center of the circumferential length of the magnets 12a, 12b to enlarge the magnetomotive force of center of the circumferential length of the magnets 12a, 12b. <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. 7 is a view showing a basic configuration of the magnetic rotary position sensor of the above-mentioned prior application. As shown in the figure, semi-cylindrical first and second magnets 2a and 2b having a circular arc angle α (α ≦ 180 °) are arranged to face each other in 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. 7, 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.

  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

  FIG. 8 is a diagram for explaining the operation of the magnetic rotary position sensor shown in FIG. 7. FIG. 8A 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 a region where FIGS. 7B to 7D are views showing the positional relationship between the magnets 2a and 2b of the magnetic rotary position sensor shown in FIG. 7 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. 8A, the curve a indicating the change in the absolute value of the 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. .

  9 and 10 are graphs showing the relationship between the rotation angle θ of the magnetic rotary position sensor shown in FIG. 7 and the detected magnetic flux density. FIG. 9 shows the arc angle α as 143 °, and the detection angle range is ± FIG. 10 shows the relationship between the rotation angle θ and the detected magnetic flux density at 60 °, and FIG. 10 shows the relationship between the rotation angle θ and the detected magnetic flux density when the arc angle α is 166 ° and the detection angle range is ± 75 °. FIGS. 9 and 10 (b) show an enlarged view of a part of (a) (rotation angle θ is 0 to 45 degrees and detected magnetic flux density is 0 to 50 mT). An approximate straight line a is shown together with a curve b indicating a change in detected magnetic flux density. FIG. 11 is a graph showing the relationship between the rotation angle θ and the linear error of the magnetic rotary position sensor shown in FIG. 7, and the curves a1 and b1 show the cases where the arc angle α is 143 ° and 166 °, respectively. . 9 to 11, the linear error when the rotation angle θ of the detected magnetic flux density of the magnetic sensor 3 is around ± 30 degrees, that is, the linear error at the center of the detection angle range becomes large, and the center of the detection angle range. The straight line error of the portion becomes larger when the arc angle α is increased and the detection angle range is increased.

  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, The magnetomotive force at the center of the circumferential length of the magnet 2 is increased.

  In this case, a protrusion may be provided at the center of the circumferential length of the first and second magnets.

  Moreover, you may enlarge the magnetization amount of the center part of the circumferential length of the said 1st, 2nd magnet.

  In the magnetic rotary position sensor according to the present invention, since the magnetomotive force at the central portion of the circumferential length of the first and second magnets is large, the linear error of the detected magnetic flux density of the magnetoelectric transducer can be reduced.

  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 12a and 12b are arranged oppositely in 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. That is, two magnetic sensors 13a and 13b are arranged at intervals of 180 degrees on the circumference. Further, the radius of the circle is ½ or more of the outer dimension width of the magnetic sensors 13a and 13b. 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 14 which protruded inside is provided in the center part of the circumferential length of magnet 12a, 12b, and the magnetomotive force (magnetic flux amount) of the circumferential center part 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 absolute value of the amount of magnetic flux passing through the detection unit of the magnetic sensor 3 shown by the curve a in FIG. 8 can be increased when the rotation angle θ is around 0 °. Since the curve indicating the change in the absolute value of the magnetic flux amount can be approximated to a straight line when the rotation angle θ is near 0 °, 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. it can. Further, since the two magnetic sensors 13a and 13b are arranged at intervals of 180 degrees on the circumference, it is monitored that the sum of the outputs of the magnetic sensors 13a and 13b is constant, and the magnetic sensors 13a and 13b It can be confirmed that it is functioning normally.

  FIG. 2 shows the yokes 1 and 11 having an outer diameter of 20 mm, an inner diameter of 15 mm, magnets 2a, 2b, 12a and 12b having a thickness of 1.5 mm, an arc angle α of 143 °, and the central portions of the magnetic sensors 3, 13a and 13b. Shows the relationship between the rotation angle θ and the linear error when the distance from the center of the yokes 1 and 11 is 2.72 mm, the width a of the protrusion 14 is 0.7 mm, and the radial length b is 0.68 mm. In the graph, a curve a1 shows the case of the magnetic rotary position sensor shown in FIG. 7, and a curve a2 shows the case of the magnetic rotary position sensor shown in FIG. As is apparent from FIG. 2, when the protrusion 14 is provided, the linear error at the center of the detection angle range of the detected magnetic flux density of the magnetic sensors 13a and 13b is smaller than when the protrusion 14 is not provided. can do.

  FIG. 3 is a graph showing the relationship between the rotation angle θ and the linear error when the arc angle α is 166 ° and other dimensions are the same as in FIG. 2, and the curve b1 is the magnetic rotary shown in FIG. The case of the position sensor is shown, and the curve b2 shows the case of the magnetic rotary position sensor shown in FIG. As is apparent from FIG. 3, even when the arc angle α is increased and the detection angle range is increased, when the protrusion 14 is provided, the magnetic sensor 13a is compared with the case where the protrusion 14 is not provided. , 13b, the linear error at the center of the detection angle range of the detected magnetic flux density can be reduced.

  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 circular protrusion 15 projecting inward is provided at the center of the circumferential length of the magnets 12a and 12b, and the magnetomotive force at the center of the circumferential length of the magnets 12a and 12b is increased. Yes.

  FIG. 5 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 protrusion 16 projecting inward is provided at the center of the circumferential length of the magnets 12a and 12b, and the magnetomotive force at the center of the circumferential length of the magnets 12a and 12b is increased. Yes.

  Also in the magnetic rotary position sensor shown in FIGS. 4 and 5, the protrusions 15 and 16 are provided at the center of the circumference of the magnets 12a and 12b, and the center of the circumference of the magnets 12a and 12b is raised. Since the magnetic force is increased, 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.

  6A and 6B are diagrams showing the basic configuration of another magnetic rotary position sensor according to the present invention. FIG. 6A is a diagram showing the basic configuration itself, and FIG. 6B is the circumferential length position and magnetization of the magnet 21b (21a). In the graph showing the relationship with the quantity, the positions A to C in (b) correspond to the positions A to C in (a). As shown in the figure, semi-cylindrical first and second magnets 21a and 21b are arranged opposite to each other in a cylindrical yoke 11, and each of the magnets 21a and 21b has N and S poles on its 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.

  In the magnetic rotary position sensor shown in FIG. 6 as well, the magnetizing amount at the center part of the circumferential length of the magnets 21a and 21b is large, and the magnetomotive force at the center part of the circumferential length of the magnets 21a and 21b is large. Therefore, 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.

  As the magnetic sensors 13a and 13b, magnetoelectric conversion elements such as Hall effect sensors, magnetoresistive 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.

  Moreover, in the above-mentioned embodiment, although the square-shaped protrusion part 14, the round-shaped protrusion part 15, and the V-shaped protrusion part 16 were provided as a protrusion part, you may provide another protrusion part. In the above-described embodiment, the amount of magnetization is changed as shown in FIG. 6B, but the magnetomotive force at the center portion of the circumferential length of the first and second magnets may be increased.

It is a figure which shows the basic composition of the magnetic type rotary position sensor which concerns on this invention. It is a graph which shows the relationship between the rotation angle (theta) and linear error of the magnetic type rotary position sensor shown in FIG. 1, FIG. It is a graph which shows the relationship between the rotation angle (theta) and linear error of the magnetic type rotary position sensor shown in FIG. 1, FIG. 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 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. 8 is a graph showing the relationship between the rotation angle θ of the magnetic rotary position sensor shown in FIG. 7 and the detected magnetic flux density. 8 is a graph showing the relationship between the rotation angle θ of the magnetic rotary position sensor shown in FIG. 7 and the detected magnetic flux density. It is a graph which shows the relationship between rotation angle (theta) and the linear error of the magnetic rotary position sensor shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Yoke 12a ... 1st magnet 12b ... 2nd magnet 13a ... Magnetic sensor 13b ... Magnetic sensor 14 ... Projection part 15 ... Projection part 16 ... Projection part 21a ... 1st magnet 21b ... 2nd magnet

Claims (3)

  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 transducer 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 raised. Magnetic rotary position sensor with increased magnetic force.   2. The magnetic rotary position sensor according to claim 1, wherein a protrusion is provided at the center of the circumferential length of the first and second magnets.   2. The magnetic rotary position sensor according to claim 1, wherein the amount of magnetization at the central portion of the circumferential length of the first and second magnets is increased.

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