JPH0473721B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] This is a device for detecting a position by detecting a change in leakage magnetic flux depending on the position in a closed magnetic circuit device, and the device detects a position by detecting a change in leakage magnetic flux depending on the position in a closed magnetic circuit device. The structure is such that leakage magnetic flux exists between the moving center axis, and the magnetic detector is not only linearly movable but also rotatable, so that even if the magnetic detector moves with rotation, Enables highly accurate position detection.

[Industrial Field of Application] The present invention relates to a position detection device, and particularly to an improvement of a position detection device comprising a closed magnetic circuit device and a magnetic detector.

[Conventional technology]

The applicant filed a patent application (patent application 1986-1989) for the invention titled "Potensiometer" on September 13, 1985.
No. 202832). This potentiometer is the first
As shown in FIG. 2, a magnetic detector 2 is provided inside a closed magnetic circuit device 1 so as to be movable linearly as shown by an arrow. The closed magnetic circuit device 1 is
It consists of elongated magnetic metal plates 3 and 4 arranged in parallel, and permanent magnets 5 and 6 arranged at the left and right ends. A leakage magnetic flux 7 that weakens as it moves away from the permanent magnets 5 and 6 flows inside the closed magnetic circuit device 1. The magnetic detector 2 has a structure in which a magnetic sensing element that utilizes the magnetic resistance of, for example, a ferromagnetic metal is housed in a case, and is guided by a non-magnetic guide 8 according to the displacement of the object to be measured. It also moves linearly while detecting the leakage magnetic flux 7. The magnetic detector 2 outputs a voltage according to the direction and amount of the detected leakage magnetic flux. Based on this output voltage, the position of the magnetic detector 2 (object to be measured) in the longitudinal direction of the closed magnetic circuit device 1 is detected.

[Problem that the invention seeks to solve]

The leakage magnetic fluxes 7 described above flow parallel to each other as shown in FIG. 13, and have no symmetry in the circumferential direction with the guide 8 as the center. Therefore, when the magnetic detector 2 rotates about the guide 8 as shown by the two-dot chain line, the magnetic detector 2 is rotated by the leakage magnetic flux 7.
The angle formed by the magnetic sensor changes, and the output voltage from the magnetic detector 2 changes by an amount corresponding to the above-mentioned angle change. Therefore, in the potentiometer configured as described above, rotation of the magnetic detector 2 about the guide 8 must be strictly avoided, and the object to be measured is limited to linearly displaced objects, such as shock absorbers. It cannot be applied to detecting the position of something that moves in a linear manner while rotating, such as a shaft, and its range of application is limited.

Also, the rotation of the magnetic detector 2 is restricted,
Since there is always a slight gap between this hole and the guide 8, even if the object to be measured does not rotate but moves linearly. The magnetic detector 2 may rotate slightly during movement. In this case as well, there was a problem in that the output voltage of the magnetic detector 2 fluctuated, resulting in an error in the detection position and reducing the resolution of the potentiometer.

[Means for solving problems]

The present invention provides a substantially cylindrical cylindrical member made of a magnetic material, a permanent magnet provided at at least one end of the cylindrical member, annular in shape and radially magnetized, and the permanent magnet A center penetrating member made of a magnetic material is fixed to a center hole of the cylindrical member and is arranged to pass through the center of the cylindrical member, and magnetic flux leaks between the inner surface of the cylindrical member and the center penetrating member. a closed magnetic circuit device forming a closed magnetic path; a closed magnetic circuit device disposed inside the closed magnetic circuit device so as to be movable in the longitudinal direction of the closed magnetic circuit device and rotatable in the circumferential direction of the cylindrical member; It is characterized by a magnetic detector that detects

[Effect]

The closed magnetic circuit device forms leakage magnetic flux such that the output voltage from the magnetic detector does not change at all even if the magnetic detector rotates. Therefore, no matter what rotational position the magnetic detector is in, the position of the magnetic detector to be detected in the longitudinal direction of the closed magnetic circuit device can be accurately detected.

〔Example〕

FIG. 1 is a partially cutaway perspective view schematically showing a position detection device according to a first embodiment of the present invention, and FIG.
The longitudinal cross-sectional view of the closed magnetic circuit device shown in the figure, and FIGS. 3 and 4 are enlarged cross-sectional views taken along lines - and - in FIG. 1, respectively.

In FIGS. 1 to 4, 10 is a closed magnetic circuit device;
Reference numeral 11 denotes a magnetic detector housing a magnetic sensing element that utilizes the magnetic resistance of ferromagnetic metal, for example.

The closed magnetic circuit device 10 includes a cylindrical member 12 made of a magnetic material, annular permanent magnets 13 and 14 fitted into openings at both ends of the cylindrical member 12, and an end portion connected to the center of the permanent magnets 13 and 14. It consists of a center penetrating member 15 fixed in the hole and provided at the center of the cylindrical member 12 so as to penetrate through the cylindrical member 12. Permanent magnet 1
3 and 14 are magnetized in the radial direction, with an S pole (N pole) on the inner circumferential side and an N pole (S pole) on the outer circumferential side. The center penetrating member 15 is made of a magnetic material and has an elongated cylindrical shape.

As shown in FIG. 2, a magnetic flux 16 passes through the cylindrical member 12 from the north pole of the permanent magnet 13 to the south pole of the permanent magnet 14. A magnetic flux 17 from the north pole of the permanent magnet 14 to the south pole of the permanent magnet 13 passes through the center penetrating member 15 . In the space inside the cylindrical member 12,
Leakage magnetic fluxes 18 and 19 flow which weaken as they move away from the permanent magnets 13 and 14. Closed magnetic circuit device 10
As shown in FIG. 3, the leakage magnetic flux 18 in the left half of the magnetic flux leaks from the inner surface of the cylindrical member 12, flows toward the center penetrating member 15, and is distributed so as to converge on the center penetrating member 15. . As shown in FIG. 4, the leakage magnetic flux 19 in the right half of the closed magnetic circuit device 10 leaks from the circumferential surface of the center penetrating member 15 and flows toward the inner surface of the cylindrical member 12. They are distributed radially around the penetrating member 15.

In FIGS. 1 to 3, 20 is a non-magnetic ring, which is fitted into the center penetrating member 15 so as to be slidable and rotatable. The magnetic detector 11 is connected to the ring 2
It is fixed on the outer periphery of the cylindrical member 12 so as to face the inner surface of the cylindrical member 12.

When the magnetic detector 11 is guided by the central penetrating member 15 and moves linearly between positions P ₁ and P 2 with the position P ₀ as the center as shown by arrow A in FIGS. 1 and ₂ , The direction and amount of leakage magnetic flux 18 or 19 are detected and a voltage is output. Line I in FIG. 5 shows the characteristics of the position detector. Based on this characteristic, the position of the magnetic detector 11 in the longitudinal direction of the closed magnetic circuit device 10 is detected.

A case in which the magnetic detector 11 rotates around the penetrating member 15 as shown by arrow B in FIG. 1 will now be described.

First, as shown in Figure 3, the magnetic detector 1
1, even when rotated, the distance m from the inner surface of the cylindrical member 12 is maintained at the same distance. Further, as already mentioned, the leakage magnetic fluxes 18 and 19 are distributed so as to converge on the central penetrating member 15 and radiate from the central penetrating member 15, as shown in FIGS. 3 and 4, respectively. There is. Therefore, as can be seen from FIG. 3, when the magnetic detector 11 rotates at any position within the left half of the closed magnetic circuit device 10, the relationship between the magnetic detector 11 and the leakage magnetic flux 18 acting on it is The angle is always maintained at 90 degrees and remains unchanged regardless of the rotation angle of the magnetic detector 11, and therefore the output voltage also remains unchanged. Magnetic detector 1
1 rotates at any position within the right half of the closed magnetic circuit device 10, as can be seen from FIG.
9 is always maintained at 90 degrees and remains unchanged regardless of the rotation angle of the magnetic detector 11, and therefore the output voltage also remains unchanged.

Therefore, the position detecting device has the magnetic detector 11
Even if the closed magnetic circuit device 10 moves in the longitudinal direction with the above-mentioned rotation, the result in FIG. 5 obtained when it moves without rotation, regardless of the degree of rotation, is It exhibits exactly the same characteristics as Line I. Therefore, in this embodiment, the position detector is used not only when the object to be measured moves linearly without rotation, but also when the object to be measured moves linearly while rotating, such as the shaft of the shock absorber mentioned above. It can also be applied to position detection without any problems.

FIG. 6, FIG. 7, and FIG. 8 each show a position detection device according to a second embodiment of the present invention. In each figure, the first
Components that are substantially the same as those shown in FIGS. 4 to 4 are designated by the same reference numerals, and their explanations will be omitted.

The position detection device of this embodiment has a closed magnetic circuit device 3.
0 is replaced with a cylindrical member 3 in which the right permanent magnet 14 constituting the closed magnetic circuit device 10 described above is removed, and the right opening is closed with a lid portion 31a instead of the cylindrical member 12.
This is a configuration using 1. That is, the closed magnetic circuit device 30 has the permanent magnet 1 in the left opening of the cylindrical member 31.
3 is fitted, and the center penetrating member 15 is connected and fixed at its left end to the center hole of the permanent magnet 13 and at its right end to the lid portion 31a. A magnetic flux 32 passes through the cylindrical member 31 and the central penetrating member 15 from the S pole to the N pole of the permanent magnet 13 . The leakage magnetic flux 33 inside the closed magnetic circuit device 30 leaks from the inner surface of the cylindrical member 21 and flows toward the center penetrating member 15, and is distributed as shown in FIG. 8 in the circumferential direction.

The magnetic detector 11 is attached to a ring 20 fitted to the penetrating member 15, and is movable linearly in the direction of arrow A and rotatable in the direction of arrow B, as described above.

In the position detector of this embodiment, similarly to the above, the output voltage does not change due to the rotation of the magnetic detector 11, and when the magnetic detector 11 moves in the direction of the arrow A, the output voltage accompanies the rotation. In this case, the position of the magnetic detector 11 in the longitudinal direction of the closed magnetic circuit device 30 is detected with high accuracy based on the output voltage.

FIG. 9, FIG. 10, and FIG. 11 each show a position detection device according to a third embodiment of the present invention. In each figure,
Components that are substantially the same as those shown in FIGS. 1 to 4 are designated by the same reference numerals, and their explanations will be omitted.

The position detection device of this embodiment includes a closed magnetic circuit device 1
This is a configuration in which a shielding cylindrical member 40 made of a magnetic material is provided so as to surround 0. This cylindrical shielding member 40 includes a protruding portion 15a of the central penetrating member 15 that protrudes outward from the permanent magnets 13 and 14,
15b. 42 is a magnetic flux passing through the shielding cylindrical member 40, and 43 is a magnetic flux leaking from the cylindrical member 12 and flowing into the shielding cylindrical member 4.
This is the leakage magnetic flux toward 0.

Since leakage magnetic fluxes 18 and 19 similar to those shown in FIGS. 2 and 3 flow inside the closed magnetic circuit device 10, the magnetic detector 11 moves with rotation as in the previous case. Even in this case, the position of the magnetic detector 11 in the longitudinal direction of the closed magnetic circuit device 10 can be detected with high accuracy.

Note that in this embodiment, the shielding cylindrical member 12
As a result, unnecessary magnetic fields from the outside are removed from the closed magnetic circuit device 1.
The effect on 0 is effectively reduced. Therefore, the position detection device of this embodiment can be installed without any problem even in a place where a magnetic field is generated. Note that this shielding cylindrical member 12 is also effective when applied to the conventional position detection device shown in FIG.

The cylindrical members 12 and 31 may have inner peripheries that correspond to the cylindrical peripheral surface, and the outer peripheries do not necessarily have to be cylindrical.

〔Effect of the invention〕

As explained above, according to the present invention, the rotation and the rotation position of the magnetic detector have no influence on the detection of the longitudinal position of the closed magnetic circuit device that is originally to be detected. It can also be applied to detecting the position of objects to be measured that move linearly with rotation, such as the shaft of a shock absorber, and can be used to expand the range of applications. Since this has no effect on position detection, it has the effect of improving position detection accuracy.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view schematically showing a position detection device according to a first embodiment of the present invention, and FIG.
3 and 4 are cross-sectional views taken along lines - and - in Fig. 1, respectively, showing the distribution of leakage magnetic flux, and Fig. 5 is a sectional view along the longitudinal direction of the position detecting device. FIG. 6 is a partially cutaway perspective view schematically showing a position detecting device according to a second embodiment of the present invention, and FIG. 7 is a longitudinal view of the position detecting device shown in FIG. 8 is a cross-sectional view taken along the line - in FIG. 6 showing the distribution of leakage magnetic flux, and FIG. 9 is a schematic view of a position detection device according to a third embodiment of the present invention. A partially cutaway perspective view, FIG. 10 is a sectional view in the longitudinal direction of the position detection device in FIG. 9, and FIG. 11 is a cross-sectional view along the XI-XI line in FIG. 9 showing the distribution of leakage magnetic flux. , FIG. 12 is a perspective view of a conventional potentiometer, and FIG. 13 is a cross-sectional view taken along the line X--X in FIG. 12, showing the distribution of leakage magnetic flux. 1 to 4 and 6 to 11, 10 and 30 are closed magnetic circuit devices, 11 is a magnetic detector, 12 and 31 are cylindrical members, 13 and 14 are permanent magnets, and 15 is a center penetrating members, 15a, 15b are protruding parts, 16, 17, 32, 42 are magnetic fluxes, 18,
19, 33, 43 are leakage magnetic fluxes, 31a is a lid portion, 4
0 is a cylindrical member for shielding.

Claims (1)

[Claims] 1. Substantially cylindrical magnetic material cylinder members 12, 31
and permanent magnets 13 and 14 provided at at least one end of the cylindrical members 12 and 31 and having an annular shape and magnetized in the radial direction; A center penetrating member 15 made of a magnetic material is arranged to penetrate through the centers of the cylindrical members 12 and 31, and magnetic flux leaks between the inner surface of the cylindrical member and the center penetrating member to form a closed magnetic path. a closed magnetic circuit device 10, 30, which is disposed inside the closed magnetic circuit device 10, 30 so as to be movable in the longitudinal direction thereof and rotatable in the circumferential direction of the cylindrical members 12, 31; magnetic flux 1
1. A position detection device comprising a magnetic detector 11 that detects the direction and amount of magnets 8, 19, and 33. 2 The closed magnetic circuit device 10 includes the cylindrical member 12
is open at both ends, and the permanent magnets 13, 1
4 are arranged at both ends of the cylindrical member 12, and the center penetrating member 15 has both ends thereof fixed to the center holes of the permanent magnets 13 and 14. The position detection device described. 3 The closed magnetic circuit device 30 includes the cylindrical member 31
The permanent magnet 13 is disposed at the other end of the cylindrical member 31, and one end of the center penetrating member 15 is fixed to the center hole of the permanent magnet 13, and the other end is fixed to the center hole of the permanent magnet 13. The position detection device according to claim 1, characterized in that it is configured to be fixed to the lid portion 31a. 4. The position detection device according to claim 1, wherein the closed magnetic circuit device 10 is surrounded by a shielding cylindrical member 40.