JPH0777166B2 - Non-contact type potentiometer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a non-contact potentiometer that detects a rotation angle of a rotor by the interaction of magnetic forces, and particularly, a ferromagnetic magnet whose resistance value is reduced by the magnetic force. The present invention relates to a non-contact type potentiometer using a resistance element.

[Prior Art] The magnetic circuit of a non-contact potentiometer has conventionally been configured as a closed magnetic circuit together with a bottomed cylindrical core, a rotating magnetic body, and a permanent magnet, and a magnetic resistance element is provided in a gap formed at the tip of the rotating magnetic body. An InSn is arranged to generate an output according to the rotation of the rotating magnetic body, and in other words, by changing the size of the gap formed at the tip of the rotating magnetic body, in other words, the rotating magnetic body is changed. A predetermined function output is obtained from the InSb magnetoresistive element as described above by processing the tip of the above with a predetermined function.

[Problems to be Solved by the Invention] In this case, the permanent magnet corresponds to approximately half of the magnetoresistive element, but the magnetic resistance of the portion where the magnetic flux force from both ends of the permanent magnet does not correspond to the permanent magnet. Inevitably, the relationship between the rotation angle and the output will be inaccurate, and the reliability of the operation of various devices such as the speedometer to which the potentiometer is applied and the throttle position sensor will be poor. .

This invention was made to eliminate this problem.
By locally preventing magnetic leakage from both ends of the magnetic field generation means, the magnetic flux force at both ends of the magnetic field generation means does not reach the magnetoresistive element in a portion that does not correspond to the magnetic field generation means.
It is an object of the present invention to provide a non-contact potentiometer having an excellent effect that an accurate relationship between a rotation angle and an output is maintained, and thus high reliability in operation of various devices is obtained.

[Means for Solving the Problems] According to the present invention, a housing, a rotor rotatably provided in the housing, and a rotor that is concentric with the rotor and is spaced apart from the rotor by a predetermined distance are provided. An insulating substrate having a ferromagnetic magnetoresistive element having a predetermined shape, and a rotor concentric with a radial surface of the rotor mounted on the rotor side in proximity to a part of the ferromagnetic magnetoresistive element. And a magnetic field generating means for applying a magnetic field in the radial direction of the rotor to the part, the magnetic field of the magnetic field generating means being attached to the radial surface, Is provided with a magnetic leakage prevention member made of a magnetic material that prevents leakage from the radial surface.

[Operation] According to the present invention configured as described above, the magnetic flux from both ends of the magnetic field generation means is absorbed by the magnetic leakage prevention members made of a magnetic material, and the magnetic force lines emitted from both ends of the magnetic field generation means. So that the inner magnetic field generating means of the ferromagnetic magnetoresistive element does not extend to a portion other than the adjacent portion, the accurate relationship between the rotation angle and the output is maintained, and thus high reliability in the operation of various devices can be obtained. become.

[Advantages of the Invention] According to the present invention configured as described above, the magnetic flux from both ends of the magnetic field generation means is converged by the magnetic leakage prevention members made of a magnetic material, and the magnetic field lines of the magnetic field generation means are strong. The internal magnetic field generating means of the magnetic magnetoresistive element does not extend beyond a portion close to the magnetic magnetoresistive element, the accurate relationship between the rotation angle and the output is maintained, the variation in output characteristics between products is reduced, and eventually various devices are used. It is possible to provide a non-contact potentiometer having an excellent effect that high reliability can be obtained in the operation of.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. First
An embodiment of the present invention is shown in the figure, a top view thereof is shown in the same figure (a), and a cross-sectional view taken along line AA in the same figure is shown in the same figure (b). The configuration shown in the figure is a circular or polygonal shape with an opening on an insulating substrate 1 as a circuit board, and is made of Ni-F.
Ferromagnetic magnetoresistive elements 2a, 2b made of thin films of e, Ni-Co, etc.
Is formed, one end 3 of the opening is connected to the power supply voltage Vcc, and the other terminal 4 is grounded (GND). In addition, the output terminal 5 is Vout from within the ferromagnetic magnetoresistive elements 2a and 2b.
Connected to take out as. Then, a semi-circular arc-shaped permanent magnet 6 is attached to the ferromagnetic magnetoresistive elements 2a, 2b of the insulating substrate 1 at a predetermined distance from the ferromagnetic magnetoresistive elements 2a, 2b.

This state or mode will be described in more detail with reference to FIG. 2 as well. A disk-shaped rotor 8 is provided in a cylindrical housing 7 with a closed upper end, and a rotary shaft 9 of the rotor 8 is It is oriented in the vertical direction, penetrates the upper surface of the housing 7, and is supported by bearings 10. A case 11 is provided in a closed state at the lower end opening of the housing 7, and an insulating substrate 1 is mounted on the upper surface of the case 11. The permanent magnet 6 as a magnetic field generating means has a semicircular arc shape, which is attached to the outer peripheral surface of the rotor 8 and is arranged so as to be concentric with the ferromagnetic magnetoresistive element 2a so as to face it vertically. At this time,
A pair of magnetic leakage prevention members 12 made of a magnetic material such as iron pieces are attached to both ends of the permanent magnet 6 with an adhesive or the like having a trademark name of Aron Alpha. The permanent magnet 6 and the ferromagnetic magnetoresistive elements 2a and 2b form a closed magnetic path as indicated by the symbol i in FIG. 1 (b).

Further, the permanent magnet 6 rotates in the circumferential direction of the ferromagnetic magnetoresistive elements 2a and 2b with the centers of the ferromagnetic magnetoresistive elements 2a and 2b as the centers of rotation axes. In the embodiment, the absolute value of the strength of the magnetic field generated toward 2a and 2b is set to be equal to or higher than the saturation magnetic field strength of the ferromagnetic magnetoresistive elements 2a and 2b. The magnetic field is applied in the direction perpendicular to the circumferential direction of the ferromagnetic magnetoresistive elements 2a and 2b, that is, in the radial direction.

Next, the operation of the potentiometer configured as described above will be described.

When the permanent magnet 6 receives a magnetic field from the direction perpendicular to the current direction, the resistance values of the ferromagnetic magnetoresistive elements 2a and 2b decrease. And the permanent magnet 6 is the ferromagnetic magnetoresistive element 2a, 2b.
By rotating in the circumferential direction of the ferromagnetic magnetoresistive element 2a,
The portion where the resistance value decreases in 2b also rotates continuously. Therefore, the resistance value between the ground terminal and the output terminal Vout and the output terminal
The value of the output Vout as the divided value of the power supply voltage Vcc determined by the ratio of the resistance value of the Vout to the resistance value of the power supply voltage Vcc terminal has a linearity as shown in FIG.

The rotation angle 0 deg in FIG. 3 means that the straight side 6c of the permanent magnet 6 in FIG. 1 is perpendicular to the line AA in the figure, and the permanent magnet 6 is arranged on the left side in the figure. is there. Further, although FIG. 3 shows the characteristic of right rotation from that position in FIG. 1, either direction of rotation may be used.

The ferromagnetic magnetoresistive elements 2a and 2b show a constant decrease in their resistance values when subjected to a magnetic field strength (absolute value) equal to or higher than the saturation magnetic field (dashed line) as shown by the characteristic (solid line) in the graph of FIG. Since (the resistance value becomes substantially constant), the value of the output Vout does not depend on the mounting error of the permanent magnet 6 and the slight fluctuation of the magnetizing strength in the actual embodiment. It should be noted that the characteristic of InSb is shown by a dotted line in FIG. 4, but it can be seen that the resistance value of InSb increases as the magnetic field strength increases.

As described above, in the above structure, since the magnetic leakage prevention portions 12 are provided at both ends of the permanent magnet 6, the magnetic force from both ends of the permanent magnet 6 is absorbed by the magnetic leakage prevention portion 12 made of a magnetic material. Therefore, the magnetic force at both ends of the permanent magnet 6 becomes
Since it does not reach the ferromagnetic magnetoresistive element 2b which does not correspond to, the relationship between the rotation angle and the output can be maintained exactly as specified, and high reliability can be obtained in the measurement of various kinds of devices.

In this way, magnetic leakage from both ends of the permanent magnet 6 is prevented, and as shown by the solid line in FIG. 3, the peak value becomes larger and the linear portion increases as compared with the broken line, so that the potentiometer is used. Output processing, that is, amplification circuit processing and the like are facilitated.

Next, FIGS. 5 (a) and 5 (b) show a second embodiment of the present invention. The difference between the second embodiment and the first embodiment is as follows. That is, in the first embodiment, the permanent magnet 6 is positioned so as to correspond vertically to the ferromagnetic magnetoresistive elements 2a and 2b, but in the second embodiment, the permanent magnet 6 is arranged.
The radius of is slightly larger than the radius of the ferromagnetic magnetoresistive element 2a,
The permanent magnet 6 is positioned so as to exist around the outer periphery of the ferromagnetic magnetoresistive element 2a.

Even with this structure, the same effect as that of the first embodiment can be obtained.

In the second embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and only different parts are described.

6 (a) and 6 (b) show a third embodiment of the present invention.
In particular, FIG. 6 (a) shows a sectional view taken along line VI-VI of FIG. 6 (b). In the third embodiment, the width dimension of the permanent magnet 6 in the first embodiment is set to be large.

With this configuration, the magnetic leakage prevention effect on the permanent magnet 6 is enhanced. In this case, the ferromagnetic magnetoresistive element 2a is set to be slightly larger in diameter than the other ferromagnetic magnetoresistive element 2b.

7 (a) and 7 (b) show a fourth embodiment of the present invention.
In the fourth embodiment, the diameter of the permanent magnet 6 in the third embodiment is set to be slightly larger so that the permanent magnet 6 is located on the outer periphery of the ferromagnetic magnetoresistive elements 2a and 2b.

Next, FIGS. 8 (a) and 8 (b) show a fifth embodiment of the present invention. In the fifth embodiment, a recess is formed in the magnetic leakage prevention unit 12 of the fourth embodiment, and the recess of the magnetic leakage prevention unit 12 is fitted to both ends of the permanent magnet 6. Even with this structure, the same effect as that of each of the above-described embodiments can be obtained.

Although the ferromagnetic magnetoresistive elements 2a and 2b have a circular or polygonal shape in the above embodiment, the shape is not limited to this and may be, for example, a strip shape.

Further, although the iron-based material is used as the material of the magnetic leakage prevention unit 12 in the above-mentioned embodiment, the material is not limited to this material, and the point is that a magnetic material such as ferrite may be used. Further, the field generating means may be linearly formed together with the ferromagnetic magnetoresistive element so as to take out the linear displacement. Further, the rotor may be configured to have a negative effect on rotation and linear movement, and may be configured to take out rotation and linear movement. Alternatively, in this case, the rotational displacement and the linear displacement of the rotor may be simultaneously extracted.

[Brief description of drawings]

FIG. 1 shows an embodiment of the potentiometer of the present invention. FIG. 1 (a) is a top view thereof and FIG. 1 (b) is a sectional view taken along line AA. 2 is a longitudinal sectional view, FIG. 3 is a graph showing output characteristics of the embodiment shown in FIG. 1, FIG. 4 is a graph showing characteristics of a ferromagnetic magnetoresistive element, and FIGS. 5 (a) and 5 (b).
Shows a top view and a sectional view showing a second embodiment of the present invention, FIGS. 6 (a) and 6 (b) show a top view and a sectional view showing a third embodiment of the present invention, FIG. 7 (a), b) is a top view and a sectional view showing a fourth embodiment of the present invention, FIG. 8 (a),
(B) is a top view and a sectional view showing a fifth embodiment of the present invention. In the figure, 1 ... Insulating substrate (circuit board), 2a, 2b ... Ferromagnetic magnetoresistive element, 6 ... Permanent magnet (magnetic field generating means), 7 ...
… Housing, 8 …… Rotor, 9 …… Rotary shaft, 10 …… Bearing, 12 …… Magnetic leakage prevention section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Ao 1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd. (72) Inventor Toshikazu Arasa 1-1-chome, Showa town, Kariya city, Aichi prefecture Sozo Co., Ltd.

Claims (3)

[Claims] 1. A housing, a rotor rotatably provided in the housing, and a pair of concentric rotors arranged at a predetermined distance from the rotor and having a generally annular shape. An insulating substrate having a ferromagnetic magnetoresistive element, mounted on the rotor side in proximity to a part of the ferromagnetic magnetoresistive element to rotate together with the rotor, and to have both end portions on a radial surface of a concentric circle of the rotor. A magnetic field generating means that is partitioned and formed in an arc shape concentric with the rotor and applies a magnetic field in the radial direction of the rotor to the part, and a magnetic field of the magnetic field generating means that is attached to the radial surface is in the radial direction. A non-contact potentiometer equipped with a magnetic leakage prevention member made of a magnetic material that prevents leakage from the surface of the. 2. The non-contact potentiometer according to claim 1, wherein the magnetic leakage prevention member is provided in such a manner that the outer peripheral portions of both end portions of the magnetic field generating means are fitted to each other. . 3. The non-contact potentiometer according to claim 1 or 2, wherein the magnetic leakage prevention member is made of an iron-based metal material.