JP2002022489A - Mechanism for detecting origin location of absolute sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a compact and inexpensive mechanism for detecting the origin location of an absolute sensor. SOLUTION: In the mechanism 1 for detecting the origin location of the magnetic-type absolute sensor, both an annular membrane pattern 6 with magnetic shielding characteristics and a membrane dot pattern 8 also with magnetic shielding characteristics located outside in the radial direction of a separating part 7 formed in the pattern 6 are formed in the surface of a rotating disk 2 made of a magnetic transmitting material. When each of the membrane dot pattern 8 and the separating part 7 pass between an opposingly arranged exciting coil 3 and first and second detecting coils 4 and 5, pulsating detection output is obtained from each of the detecting coils 4 and 5. On the basis of the detection output, it is possible to detect the origin location of the rotating disk 2 every one rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absolute sensor capable of detecting the rotational position of a rotary member as an absolute position, and more particularly to a mechanism for detecting the origin of the rotary member suitable for realizing a small and high-resolution absolute sensor. It is about.

[0002]

2. Description of the Related Art As an absolute sensor capable of detecting a rotational position of a member as absolute information, a magnetic sensor is also known. This magnetic absolute sensor mainly includes a magnetic pattern type sensor and a resolver type sensor.

The magnetic pattern type absolute sensor has a configuration in which a magnetic pattern is formed on the outer peripheral surface of a magnetic drum, and the magnetic pattern is read using a magnetic detecting element such as an MR element. Generally, a large number of magnetic patterns are formed in the axial direction on the outer peripheral surface of the magnetic drum.

On the other hand, in a resolver type absolute sensor, when a pair of primary coils are excited in two phases,
Using the fact that an excitation signal whose phase has changed by the rotation angle is induced in the secondary coil, the phase of the excitation signal of the primary coil and the phase of the induced voltage signal of the secondary coil are compared, and the rotation angle is determined. It is to detect. Here, if the windings are arranged such that the phase changes by one cycle per rotation, the rotational position can be detected as an absolute position.

[0005]

Here, in the case of an absolute sensor of the magnetic pattern type or the resolver type, when the resolution is increased, the detection signal has a multi-period for each rotation or the phase of the detection signal has a multi-period for one rotation. Change. For this reason, the same detection signal or the same phase difference appears in one rotation. In order to detect the absolute rotation position, it is necessary to add an origin position detection mechanism for detecting the origin position for each rotation of the rotating member. is there.

An object of the present invention is to propose an origin position detecting mechanism of an absolute sensor capable of generating an origin position signal generated for each rotation of a rotating body necessary for detecting an absolute rotational position by a simple configuration.

[0007]

Referring to FIG. 1, an origin position detecting mechanism 1 of an absolute sensor according to the present invention includes a rotating disk 2 and an exciting coil disposed on one side of the rotating disk 2. 3 and first and second detection coils 4 and 5 arranged on the other side of the rotating disk 2. The rotating disk 2 is formed of a material having a magnetic transmission characteristic, and has a surface 2a on its surface 2a, for example, a ring-shaped thin film pattern 6 having a magnetic shielding characteristic separated at one location in the circumferential direction.
In addition, a thin film dot pattern 8 having a magnetic shielding property located outside or inside (outside in the illustrated example) in the radial direction with respect to the separation portion 7 of the ring-shaped thin film pattern 6 is formed. These patterns are formed from, for example, copper foil.

[0008] Thin film dot pattern 8 on rotating disk 2
Between the excitation coil 3 and the first detection coil 4
Are arranged facing each other. Further, the excitation coil 3 and the second detection coil 5 are arranged opposite to each other with the passing position of the separation portion 7 on the rotating disk 2 interposed therebetween.

In the origin position detecting mechanism 1 of the absolute sensor according to the present invention, the rotating disk 2 is rotated, and the separation portion 7 and the thin film dot pattern 8 of the ring-shaped thin film pattern 6 are separated from the exciting coil 3 and the second thin film pattern 8, respectively. When passing between the detection coils 5 and between the excitation coil 3 and the first detection coil 4, a magnetic coupling state different from that at other rotational positions is formed. That is, when the thin film dot pattern 8 passes, the magnetic circuit between the exciting coil 3 and the second detection coil 5 is temporarily shut off by the thin film dot pattern 8. Conversely, when the separating portion 7 passes, a magnetic circuit shielded by the ring-shaped thin film pattern 6 is formed temporarily.

As a result, as shown in FIG. 2, pulse-shaped waveforms 4S1 and 5S1 having opposite phases appear at the outputs 4S and 5S of the first and second detection coils 4 and 5, respectively. Therefore, based on these outputs, the origin position for each rotation of the rotating disk 2 can be detected. Therefore, the absolute rotational position of the rotating disk 2 can be detected with high resolution based on the origin position.

The rotational position of the rotary disk 2 can be detected by the above-described magnetic pattern type absolute sensor. Further, an optical sensor may be provided with an origin position detecting mechanism according to the present invention for detecting the origin position.

Here, the rotating disk 2 may be formed from a non-magnetic material, and a magnetic material may be attached to the surface of the rotating disk 2. Alternatively, the rotating disk 2 may be formed of a material having a magnetic shielding property such as a copper plate, and a through hole or the like having a magnetic transmission property may be formed therein.

Next, the present invention relates to an origin position detecting mechanism of a magnetic induction type absolute sensor. FIG.
The magnetic induction type absolute sensor 10 includes a stator 11, a rotor 12, a primary excitation coil 13 and a secondary induction coil 14 arranged on the stator 11, and the rotor 12 The magnetic coupling between the primary excitation coil 13 and the secondary induction coil 14 of the stator 11 is changed according to the rotational position.

The origin position detecting mechanism 100 according to the present invention attached to the absolute sensor 10 is configured as follows. The rotor 12 is formed of a material having a magnetic shielding property such as a copper plate or a magnetic material, and a portion having a magnetic transmission characteristic, for example, a through hole or a non-magnetic material (a circular through hole in the figure) ) Are formed. An origin position detecting coil 16 is arranged so as to face the passing position of the magnetic flux line transmitting hole 15.

In the illustrated example, the stator 11 has
A plurality of, in the illustrated example, four secondary-side induction coils 14 are arranged at equal angular intervals on a concentric circle, and a magnetic metal is disposed on the surface 12a of the rotor 12 facing each of the secondary-side induction coils 14. A magnetic pattern 17 formed by attaching a plate or the like is formed. A ring-shaped primary induction coil 13 is arranged so as to surround them.

As shown in FIG. 4, the primary side induction coil 13
When an alternating current is passed through the AC, an AC magnetic flux is generated there. This magnetic flux forms a magnetic circuit passing through the magnetic ring 21 on the outer periphery, the magnetic pattern 17 formed on the rotor surface, and the magnetic pole pin 22 located at the center of the secondary induction coil 14, and as a result, the secondary induction A voltage signal is induced in the coil 14. By appropriately forming the magnetic pattern 17, the signal obtained from the secondary side induction coil 14 becomes a multi-cycle sine wave or cosine wave signal per rotation of the rotor.

Here, since the origin position detecting coil 16 usually faces the rotor 12 made of copper, an eddy current is generated in the copper plate by the magnetic flux of the primary side induction coil 13, the magnetic path is cut off, and the detecting coil 16 is turned off. , No voltage is induced. However, when the rotor 112 rotates and the magnetic flux transmitting hole 17 faces the detection coil 16, a magnetic circuit is formed through the relevant portion, and a voltage is induced in the origin position detection coil 16. Therefore, one detection pulse is obtained from the origin position detection coil 16 per one rotation of the rotor.
Based on the origin signal and the rotational position information obtained from the secondary induction coil 14, the absolute rotational position of the rotor 12 can be detected.

In the present invention, the detection pattern composed of the magnetic flux transmitting portion and the blocking portion can be defined by the presence or absence of holes formed in a plate made of copper or another conductive material. Instead of forming the holes, a small piece of magnetic material may be attached to the surface of the non-magnetic plate. Further, a configuration in which a magnetic body is attached to the surface of the insulating plate can be adopted.

[0019]

As described above, since the origin position detecting mechanism of the absolute sensor according to the present invention can detect the origin position of the rotating member with a simple configuration, a high-resolution absolute sensor can be formed small, compact and inexpensive. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an origin position detecting mechanism of an absolute sensor to which the present invention is applied.

FIG. 2 is a signal waveform diagram showing outputs of first and second origin detection coils in FIG. 1;

FIG. 3 is an explanatory view showing a magnetic induction type absolute sensor to which the present invention is applied.

FIG. 4 is an explanatory diagram showing an origin position detecting operation in the absolute sensor of FIG. 4;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 origin sensor detecting mechanism of absolute sensor 2 rotating disk 2 a surface 3 excitation coil 4, 5 detection coil 4 S, 5 S output signal 6 ring-shaped magnetic thin film pattern 7 separation part 8 magnetic thin film dot pattern 10 magnetic induction type absolute sensor 11 Stator 12 Rotor 13 Primary excitation coil 14 Secondary induction coil 100 Origin position detection mechanism 15 Magnetic flux transmission hole 16 Origin position detection coil 17 Magnetic pattern

Claims (5)

[Claims] A rotating disk; an exciting coil disposed on one side of the rotating disk; and first and second detection coils disposed on the other side of the rotating disk. The disk is formed of a material having magnetic permeability characteristics, and on the surface thereof, a ring-shaped thin film pattern having magnetic shielding characteristics separated at one point in the circumferential direction, and a radius with respect to the separated portion of the ring-shaped thin film pattern And a thin film dot pattern having a magnetic shielding property located outside or inside the direction is formed, and the exciting coil and the first detection coil are arranged to face each other with a position where the thin film dot pattern passes on the rotating disk interposed therebetween. And the excitation coil and the second detection coil are arranged to face each other with a position through which the separation portion passes on the rotating disk, and outputs of the first and second detection coils are provided. An origin position detecting mechanism for an absolute sensor, wherein the absolute position of the rotating disk is detected based on the following. 2. The absolute sensor according to claim 1, wherein the rotating disk is formed of a magnetically shielding material, and the ring-shaped thin film pattern and the thin film dot pattern are formed of a magnetically permeable material. Home position detection mechanism. 3. The mechanism for detecting the origin position of an absolute sensor according to claim 2, wherein a through hole formed in said rotating disk is used instead of said thin film dot pattern. 4. The method according to claim 1, wherein the ring-shaped thin film pattern and the thin film dot pattern are formed by attaching a magnetic piece to a surface of the rotating disk. A mechanism for detecting the origin position of an absolute sensor. 5. A stator according to claim 1, further comprising a stator, a rotor, and a primary excitation coil and a secondary induction coil disposed on the stator, wherein the rotor has a primary excitation coil of the stator in accordance with a rotational position. And an origin position detecting mechanism in a magnetic induction type absolute sensor configured to change magnetic coupling between the secondary induction coils, wherein a magnetic flux transmitting hole is formed at one position in a circumferential direction of the rotor. An origin position detecting coil is disposed so as to face the passing position of the magnetic flux line transmitting hole, and when the magnetic flux transmitting hole faces the origin position detecting coil, the magnetic flux transmitting hole is removed from the primary side exciting coil. A magnetic circuit is formed to reach the origin position detection coil via the sensor, and the absolute position of the rotor is detected based on the output of the origin position detection coil. A mechanism for detecting the origin position of an absolute sensor.