JPH09257603A - Magnetostrictive torque sensor - Google Patents

Abstract

(57) An object of the present invention is to provide a magnetostrictive torque sensor which eliminates the non-uniformity of the magnetic resistance in the circumferential direction of the yoke, has no fluctuation of the zero point, and has stable characteristics. SOLUTION: A rotating shaft 1 provided with a magnetic anisotropy portion 2 on at least a surface thereof, and a single-layer exciting / detecting coil or multiple-layer exciting coil 3 wound concentrically in the vicinity of the rotating shaft 1 and detecting. The coil 4, the lead wire 6 drawn from the exciting coil 3 and the detecting coil 4, the exciting coil 3 and the detecting coil 4, and the outer peripheral plate surface portion 51 and side plate surface portions 52 provided on both side surfaces thereof. And a donut-shaped yoke 5. The yoke 5 is provided with a slit 54 having a constant width in the outer peripheral plate surface portion 51 or the side plate surface portion 52 that makes one round in the circumferential direction, and the lead wire 6 is externally provided from the slit 54. It has been pulled out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type torque sensor utilizing a reverse magnetostriction effect of a magnetic material, and more particularly to a torque sensor for detecting a torque of a rotary shaft of a rotary drive system of, for example, a robot or a machine tool. About.

[0002]

2. Description of the Related Art Conventionally, a non-contact and small torque sensor has been required for controlling a robot, a manipulator, and a machine tool having a rotary drive system. There are various types of such torque sensors, and there is a magnetostrictive torque sensor as a non-contact and advantageous method for downsizing. In this method, torque is detected by utilizing the inverse magnetostriction effect that the magnetic permeability of the magnetic material changes when a force is applied to the magnetic material. For example, as shown in FIG. 3, a magnetic anisotropic portion 2 is formed on the surface of a rotary shaft 1 made of a magnetostrictive alloy material at an angle to the direction of the rotary shaft length, and the magnetic anisotropic portion 2 is concentrically fixed. Excitation coil 3 and detection coil 4 wound with a gap of
And an exciting circuit (not shown) for supplying an exciting current to the exciting coil, the change of the magnetic permeability of the magnetic anisotropic portion 2 caused by the torque applied to the rotating shaft 1 is regarded as the change of the impedance of the detection coil 4. To detect. A yoke 5 made of a donut-shaped box made of a magnetic material is provided outside the detection coil 4 to prevent external electromagnetic noise and reduce the power consumption of the exciting current. As shown in FIG. 4, the yoke 5 includes an outer peripheral plate surface portion 51 and donut-shaped side plate surface portions 52 provided on both side surfaces of the outer peripheral plate surface portion 51.
Also, the excitation coil 3 and the detection coil 4 are housed in a donut-shaped space surrounded by both side plate surface portions 52, and the lead wire 6 connected to the excitation coil 3 and the detection coil 4 has a side plate surface portion 52 on one side of the yoke 5. It is pulled out from the pull-out hole 53 provided in (for example, Japanese Patent Laid-Open No. 3-218427).

[0003]

However, in the former prior art described above, since the yoke 5 is provided with the extraction hole 53, the magnetic resistance of the yoke 5 becomes unbalanced only in the extraction hole 53 of the coil, and the yoke 5 is formed. There was magnetic disturbance in the circumferential direction. When torque is applied without rotating the rotating shaft 1, a signal with good reproducibility is output, but when the rotating shaft 1 is rotated, this magnetic disturbance causes a circumferential direction of the magnetic anisotropic portion of the rotating shaft. However, there is a problem that the zero point fluctuates due to the non-uniformity of the magnetic field or the combination with the eccentricity of the rotating shaft with respect to the yoke. SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetostrictive torque sensor that eliminates the non-uniformity of the magnetic resistance in the circumferential direction of the yoke, has no fluctuation of the zero point, and has stable characteristics.

[0004]

In order to solve the above-mentioned problems, the present invention provides a rotating shaft having at least a magnetic anisotropic portion on its surface, and a single layer wound concentrically in the vicinity of the rotating shaft. Alternatively, it is composed of a multi-layered excitation / detection coil, a lead wire drawn from the excitation / detection coil, the excitation / detection coil, and an outer peripheral plate surface portion and side plate surface portions provided on both side surfaces thereof. In a magnetostrictive torque sensor having a doughnut-shaped yoke, the yoke is provided with a slit having a constant width in the circumferential direction on the outer peripheral plate surface portion or the side plate surface portion, and the lead wire extends from the slit. It has been pulled out to the outside.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention, a part of which is cut away. In the figure, reference numeral 1 denotes a rotary shaft made of maraging steel, and the surface of the rotary shaft 1 has a magnetic anisotropy that forms an angle of 45 ° with the direction of the rotary shaft length, as shown in FIG. 2 (a). Directional part 2 in the circumferential direction 1
It is provided so as to go around. 3 is an exciting coil wound around the rotary shaft 12 so as to be opposed to each other with a gap therebetween, 4 is a detection coil wound outside the exciting coil 3, and 5 is so as to surround the exciting coil 3 and the detecting coil 4. The provided doughnut-shaped yoke is made of a magnetic material composed of 3% Si—Fe and is composed of an outer peripheral plate surface portion 51 and side plate surface portions 52 provided on both side surfaces thereof. A slit 54 having a constant width is formed in the central portion of the outer peripheral plate surface portion 51 so as to make one round in the circumferential direction, and the lead wire 6 of the exciting coil 3 and the detection coil 4 is provided from the slit 54.
And the inside of the slit other than the lead-out portion of the lead wire 6 is filled with resin.

The following Table 1 shows the ripple caused by the rotation of the rotary shaft 1 in the case where the side plate surface portion 52 of the related art is provided with a drawing hole and when the slit 54 is provided in the central portion of the outer peripheral plate surface portion 51 of the present invention. It is the result of obtaining the relationship between the value (Vpp) and the rated torque output (V) when the rotating shaft 1 is stationary.

[0007]

[Table 1]

From these results, it can be seen that the configuration of the present invention eliminates the non-uniformity of the magnetic resistance in the circumferential direction of the yoke 5 as compared with the configuration of the related art, so that the output fluctuation due to the rotation of the rotary shaft is reduced. . In the above embodiment, 1 in the circumferential direction.
The example in which the slit 54 having a constant width is provided in the central portion of the outer peripheral plate surface portion 51 has been described, but as shown in FIG. 2B, the slit 54 having a constant width that makes one turn in the circumferential direction. May be provided on any one of the side plate surface portions 52, and the lead wire 6 may be pulled out. In the above embodiment,
The example in which the shape anisotropy is directly given to the surface of the rotating shaft as the magnetic anisotropic portion has been described, but it is also effective when the magnetostrictive film is formed on the surface of the rotating shaft. Also, an example in which a multi-layer coil of an excitation coil and a detection coil is mounted inside the yoke has been described, but when a single-layer coil is used, for example, the excitation voltage and the phase angle deviation of the current of the excited coil are shifted. This is effective even when the impedance change is detected by.

[0009]

As described above, according to the present invention, the lead wires of the exciting coil and the detecting coil housed inside the yoke are pulled out from the slit provided in the central portion of the outer peripheral plate surface portion of the yoke. As a result, magnetic disturbance in the circumferential direction of the yoke is eliminated, zero-point fluctuation associated with rotation of the rotary shaft can be eliminated, and a magnetostrictive torque sensor having stable characteristics can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a side sectional view showing an embodiment of the present invention.

FIG. 3 is a side sectional view showing a conventional example.

FIG. 4 is a perspective view showing a conventional example.

[Explanation of symbols]

1: rotation axis, 2: magnetic anisotropic part, 3: excitation coil, 4:
Detection coil, 5: Yoke, 51: Peripheral plate surface part, 52: Side plate surface part, 53: Drawing hole, 54: Slit, 6: Lead wire

Claims (1)

[Claims] 1. A rotating shaft having a magnetic anisotropy portion on at least a surface thereof, a single-layer or multiple-layer exciting / detecting coil wound concentrically in the vicinity of the rotating shaft, and the exciting / detecting coil. In a magnetostrictive torque sensor including a lead wire drawn from and an excitation / detection coil, and a donut-shaped yoke formed of an outer peripheral plate surface part and side plate surface parts provided on both side surfaces thereof, The yoke is provided with a slit having a constant width that makes one turn in the circumferential direction on the outer peripheral plate surface portion or the side plate surface portion, and the lead wire is drawn out from the slit to the outside. .