JPS61110021A - Torque detector - Google Patents

Abstract

PURPOSE:To achieve a higher torque detection performance, by providing a rotatable adjusting means arranged to be magnetically eccentric roughly at the center of a flat plate of a ferrite magnetic core. CONSTITUTION:A torque detector 1 is equipped with a table-shaped ferrite magnetic core 3 in which columnal legs 5a-5d at four apexes of one main surface of a roughly square flat plate 4 respectively, exciting coils 6a and 6b mounted on a set of legs 5a and 5b existing on the diagonal line of the core 3 while connected in series to each other and detecting coils 6c and 6d mounted on other legs 5c and 5d as connected in series. An adjusting coil 7 arranged to be magnetically eccentric is mounted roughly at the center of the flat plate 4 of the core 3 in such a manner as to be rotatable. The torque detector 1 is so arranged that the legs 5a and 5b as exciting pole are positioned within a plane containing the axis line 2a of a rotating shaft 2 while the legs 5c and 5d as detecting pole positioned with a plane vertical to the axis line 2a while the tips of these legs face one another on the circumferential surface of the rotating shaft 2 through a fine clearance. Thus, a higher torque detection performance can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a torque detection device that detects torque applied to a rotating shaft or the like for power transmission.

(Prior Art) Devices that utilize magnetostriction phenomena have been known as devices that non-contactly detect torque applied to a rotating shaft for power transmission or the like. This type of torque detection device uses multiple sensors near the rotating shaft surface because when torque is applied to the rotating shaft made of a magnetic material, the rotating shaft surface becomes magnetically anisotropic and the magnetic permeability varies depending on the direction. The magnetic poles are arranged opposite each other, some of the magnetic poles are used as excitation poles, and the other magnetic poles are used as detection poles.The detection poles detect changes in the magnetic flux that is excited by the excitation poles and returns from the magnetic poles to the magnetic poles via the rotating shaft surface. It detects torque. The number of magnetic poles is 5 poles and 4 poles.

Three poles have been proposed.

By the way, when no torque is applied to the rotating shaft, etc., its surface is magnetically uniform, and therefore the voltage extracted from the coil of the detection pole (herein referred to as offset voltage) is a constant voltage, for example, O voltage. However, in reality, it is not necessarily constant due to variations in the core, and this requires a complicated adjustment circuit, which poses the problem of being extremely expensive.

(Objective of the Invention) The present invention provides a torque detection device that has four poles in structure and can easily adjust an offset voltage.

(Structure of the Invention) In order to achieve the above object, a table-shaped ferrite magnetic body with legs erected at the four corners of a substantially square shape of one main surface of a flat plate is used as a core.

A magnetically eccentric adjustment core is rotatably provided approximately at the center of the flat plate of the ferrite magnetic core.

Among the four legs, one set of legs facing each other is equipped with excitation coils connected in series, and the other set of legs is equipped with a detection coil.

The tips of the four legs are arranged close to the outer peripheral surface of the rotating shaft and facing each other. When the rotating shaft is not receiving torque, the offset voltage is generated by the rotation of the adjustment core.

Can be easily adjusted.

Embodiments will be described in detail below with reference to the drawings.

(Explanation of Examples) FIG. 1 shows an embodiment of the present invention.

1 is a torque detector, and 2 is a rotating shaft for power transmission. The torque detector 1 has columnar legs 5a, 5b, and 5c at four apex corners of one principal surface of a substantially square flat plate 4, respectively.

A table-shaped ferrite magnetic core 3 with 5d erected therein, and an excitation coil 6a attached to a pair of legs 5a and 5b on the diagonal of this core and connected to each other in series.
, 6b, and detection coils 6c, 6d attached to the other legs 5c, 5d and connected in series. Approximately in the center of the flat core plate 4 is rotatably mounted an adjustment core 7, which is made of, for example, a semi-cylindrical magnetic material, molded with resin to form a columnar shape, and is magnetically eccentric.

In the torque detector 1 configured in this way, the legs 5a and 5b as excitation poles are located in a plane that includes the axis 2a of the rotating shaft 2, and the legs 5c and 5d as detection poles are located in a plane perpendicular to the axis 2a. The tips of these legs are arranged so as to face the outer circumferential surface of the rotating shaft 2 with a small gap therebetween.

Next, the operation of this embodiment will be explained. Now, when current i is passed through the excitation coils 6a and 6b in the direction of the arrow, since the excitation coils 6a and 6b are connected in series and with opposite polarity, the leg 5a - the rotation axis 2 - the leg 5b - Flux φ in the magnetic path consisting of the flat plate 4. flows, and accordingly, flux φ1 is applied to the magnetic path consisting of leg 5a, rotating shaft 2, leg 5C, and flat plate 4, and flux φ2 is applied to the magnetic path consisting of leg 5a, rotating shaft 2, leg 5d, and flat plate 4.

In addition, the flux φ is applied to the magnetic path consisting of the leg 5b, the flat plate 4, the leg 5C, and the rotating shaft 2, and the flux φ is applied to the magnetic path consisting of the leg 5b, the flat plate 4, the leg 5d, and the rotating shaft 2 in the direction of the arrow. Fluxes φ and φ flow in the opposite directions in the leg 5C, and fluxes φ2 and φ flow in the opposite directions in the leg 5d, so a voltage is induced in the detection coils 6c and 6d by the flux corresponding to the difference. , is output.

Here, if the values of the fluxes φ, φ, and φ2 and φ when no torque is applied to the rotating shaft 2 are equal, then
The offset voltage becomes O. However, due to variations in the characteristics of the core, variations in the coil, variations in the assembly of the detector, etc., the voltage is not necessarily 0. Therefore, the offset voltage can be easily adjusted by rotating the magnetically eccentric adjustment core 7. When a torque is applied to the rotating shaft 2, which can be adjusted to 0, in the direction of arrow A, for example, the surface of the rotating shaft 2 has a flux φ1. A compressive force is applied in the direction parallel to φ, and a flux φ2. φ.

It receives a tensile force in the direction parallel to . As a result, the flux φ0. φ, the permeability decreases in the direction, and the other flux φ
2. The magnetic permeability increases in the φ direction. Therefore legs 5c and 5
d fluxes φ1 and φ3. The balance between φ2 and φ is lost, and a voltage corresponding to the torque is output to the detection coils 6c and 6d.

As shown in FIG. 1, the adjusting core 7 may be an eccentric core molded with resin and rotatably inserted into a hole formed in the flat plate 4, but as shown in FIG. An adjusting tool 11 with the core assembled in a rotatable manner in advance is prepared, and is attached to the square hole 13 formed in the center of the flat plate of the ferrite magnetic core 12, so that the adjusting tool 11 protrudes in the direction of the legs. You can do it like this.

(Effects of the Invention) As explained above, according to the present invention, there is no need for a complicated and expensive sI rectifier circuit as in the past, and deviations in offset voltage due to variations in cores and coils can be extremely easily corrected! i1m, which improves torque detection performance and reduces costs.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of the present invention, and FIG. 2 is a configuration diagram of main parts of another embodiment of the present invention. 1... Torque detector, 2... Rotating shaft, 3゜12... Ferrite magnetic core, 4... Flat plate, 5a, 5b, 5c, 5d - Legs, 6a, 6b - Excitation coil , 6c, 6d...detection coil, 7.
...adjustment core, 11...adjustment tool, 13...square hole.

Claims (2)

[Claims] (1) For excitation, a pair of legs on the diagonal lines of a table-shaped ferrite magnetic core with columnar legs erected at each of the four corners of a substantially square main surface of a flat plate such as a square plate or a disc is used for excitation. Attach the coil and the detection coil to the other pair of legs, respectively.
In a torque detection device in which the tip of each leg is placed opposite to the outer circumferential surface of a power transmission rotating shaft made of a magnetic material through a minute gap to detect the torque applied to the rotating shaft, the flat plate of the ferrite magnetic core is A torque detection device characterized in that a magnetically eccentric and rotatable adjusting means is provided substantially in the center. (2) The adjustment means is characterized in that an adjustment tool having a magnetically eccentric adjustment core rotatably attached is attached to a round or square hole formed in the center of the flat plate. A torque detection device according to claim (1).