JPH0257931A - Torque detecting apparatus - Google Patents

Abstract

PURPOSE:To detect torque highly accurately by providing a sensitivity correcting means for correcting the sensitivity of a signal in order to define the changing rate of the detected torque signal at a specified changing rate. CONSTITUTION:Exciting windings 141 and 142 which are wound around detecting magnetic cores 131 and 132 are connected in a cumulative pattern. Detecting windings 151 and 152 are connected in a differential pattern. A constant AC is applied to the windings 141 and 142 from a driving circuit 21, and the annular magnetic cores are excited in the circumferential direction of a torque transmitting shaft. Then voltages are generated in the windings 151 and 152. When torque T is applied to the torque transmitting shaft, a voltage which is the difference between the voltages at both ends of the windings 151 and 152 is generated. When the torque T in the reverse direction is applied to the torque transmitting shaft, the operation in the reverse direction is generated. The magnitude of said torque T and the signals from the windings 151 and 152 undergo phase detection in a phase detector 23. The results are made to be DCs in an integrator 24. The relationship between the magnitude of the torque T and said DC voltage V is as follows: the relationship between the direction of the torque application and the voltage is changed nonlinearly with an original point as a boundary. Then, the signals are made to be the DC signals with the integrator 24, and thereafter an amplifier 26 is used. Thus the relationship between the torque T and the voltage V can be made linear.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a torque detection device that detects torque applied to a rotating shaft or the like in a non-contact manner.

(Prior Art) Torque is one of the basic quantities to be detected when controlling a rotational drive system, for example. Conventionally, mechanical devices using coil springs or leaf springs are known as torque detection devices, but non-contact devices are used for applications such as rotation control systems that require precise torque detection. A type torque sensing device is required.

Therefore, in recent years, a torque detection device that utilizes the magnetostriction effect produced in a thin ribbon of an amorphous magnetic alloy has been proposed as a torque detection device that satisfies such requirements (IEE of Japan Magnetics Study Group Material MAG-81-72).

The principle of this torque detection device will be explained with reference to FIG. In FIG. 5, an annular magnetic core 2 made of an amorphous magnetic alloy ribbon is wound around and fixed to a rotating shaft on which torque is to be detected, that is, a torque transmission shaft 1. This annular magnetic core 2 has an induced magnetic anisotropy M whose axis of easy magnetization is in a direction at an angle θ with respect to the circumferential direction. has been granted. Further, a detection coil (not shown) is arranged close to the annular magnetic core 2, and this detection coil is connected to a detection circuit (not shown).

Using the torque detection device having such a configuration, torque can be detected in the following manner. Here, to simplify the explanation, it is assumed that θ>45° and the saturation magnetostriction constant λ3>0. Now, when the torque T shown by the broken line arrow is applied to the torque transmission shaft 1, the strain stress σ generated in the torque transmission shaft 1 is transmitted to the annular magnetic core 2, and the tension σ is applied to the annular magnetic core 2 in the +45'' direction. Compressive stress −σ is generated in the direction of °.

Along with this, the annular magnetic core 2 has a +4
An induced magnetic anisotropy (=3λ5σ) is induced in the direction of 5°. As a result, the magnetic anisotropy of the annular magnetic core 2 changes to M2 because the magnetic flux and the magnetic flux are combined. In this case, if the direction of the magnetic flux passing through the annular magnetic core 2 is constant, the magnetic permeability in the magnetic flux penetration direction in the annular magnetic core 2 changes as the direction of the induced magnetic anisotropy changes. Therefore, this change in magnetic permeability can be measured as a change in voltage using, for example, a detection coil and a detection circuit connected thereto, and the torque T applied to the torque transmission shaft 1 can be determined from that value.

In the above description of the torque detection device, a case has been described in which an amorphous magnetic alloy is used as the magnetic material constituting the annular magnetic core 2. Other magnetic materials such as Fe-AQ-Si alloy), Sendust (Fe-AQ-Si alloy), and Fe-Si alloy can be used.

As described above, torque can be detected by installing a detection coil or a detection head close to the periphery of an annular magnetic core made of a magnetic thin ribbon of metal. However, according to experiments conducted by the present inventors, the detection sensitivity of the torque detection signal differs from the origin as shown in Fig. 6, and the detection sensitivity differs with respect to the direction of torque application as shown in Fig. 7. It was confirmed that there was a difference in

This is due to differences in mechanical accuracy such as the angular accuracy of the detection head with respect to the circumferential direction of the torque transmission shaft 1, the difference in the gap between the magnetic alloy and the detection head, or even if the above mechanical accuracy is Even if it is managed with high precision, this is caused by the non-uniformity of the induced magnetic anisotropy of the annular magnetic core 2 fixed to the torque transmission shaft 1, which is unique to this torque sensor, that is, a soft magnetic material such as an amorphous magnetic alloy. considered to be a thing.

(Problems to be Solved by the Invention) As described above, in the conventional torque detection device, the detection sensitivity changes due to various causes, and highly accurate torque detection cannot be performed.

The present invention has been made in view of the above circumstances, and its purpose is to provide a torque detection device that eliminates the difference in detection sensitivity and is capable of highly accurate torque detection.

[Structure of the invention]

(Means for Solving the Problems) In the present invention, a magnetic metal ribbon having magnetostriction is attached to a torque transmission shaft, and the magnetic properties of the magnetic metal ribbon change in response to rotational torque applied to the torque transmission shaft. The torque detection device non-contactly detects torque as a torque detection signal using a detection head, and is characterized by being provided with sensitivity correction means for correcting signal sensitivity in order to adjust the rate of change of the torque detection signal to a predetermined rate of change.

Further, the rate of change of the torque detection signal is made to be a constant rate of change.

(Function) With this configuration, non-uniformity in detection sensitivity due to reasons that are difficult to overcome, such as non-uniformity in induced magnetic anisotropy of the magnetic metal ribbon used in this torque detection device, can also be corrected. By doing this, uniformity can be achieved at all times. Therefore, highly accurate torque detection can be performed.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a torque detection device according to an embodiment of the present invention. In FIG. 1, a pair of magnetic metal thin strips 12 are attached to a part of the outer periphery of a torque transmission shaft 11 made of a ferromagnetic material that is rotated by a drive source such as a motor (not shown).
, 12. are fixed magnetic metal thin strips 12□,
12. are made of an amorphous magnetic alloy, and are provided with induced magnetic anisotropy in the directions of angle θ and angle −0 with respect to the circumferential direction, respectively.

Magnetic metal thin strips 12□, 12□ are provided on the outer periphery of the torque transmission shaft 11.
A pair of detection heads are arranged so as to be close to each other with a predetermined gap therebetween. These detection heads consist of a magnetic metal thin strip 12. ．． Excitation windings 14 . . . 12 . are arranged in U-shaped detection magnetic cores 13 . , 142
and a detection winding 151.15□.

FIG. 2 is a circuit diagram showing the electrical configuration of the first embodiment of the torque detection device of the present invention. Detection magnetic core 131.1
Excitation winding 14 applied to 32. ．． Drive circuit 21 in 14□
is connected and a constant current is applied. A voltage change caused by a change in impedance of the detection windings 15□, 15□ in response to a torque change due to mutual induction is inputted to the amplifier 22 as a torque detection signal.

A phase shifter 25 is connected to the drive circuit 21, and a phase detector 23 is connected to the drive circuit 21.
It is used as a reference signal. The torque detection signal from the amplifier 22 and the reference signal from the phase shifter 25 are input to the phase detector 23, and after phase detection, are converted to DC through the integrator 24. A resistor 27 is connected to the output of this integrator 24.
．． 28.29, diode 30.31 and operational amplifier 32
An amplifier 26 according to the above is connected.

Next, the operation of the torque detection device according to the first embodiment configured as described above will be explained.

Excitation windings 141.14 applied to detection magnetic cores 13□ and 13□
2 is a summation coupling, and L5.2 between the detection windings. , 15□ are differentially coupled, and the AC constant current obtained from the drive circuit 21 is applied to the excitation windings 141, 14 . In addition, when the annular magnetic cores 12□, 12□ are excited in the circumferential direction of the torque transmission shaft 11, a voltage is generated in the detection winding 11151.15□ due to mutual induction. This voltage is.

It is uniquely determined by the magnetic characteristics of the magnetic circuit composed of the detection magnetic core 131, 132 around which each winding is wound, the magnetic metal thin strip 121, 12□ facing these, and the air gap between the two. Now, assume that the torque detection signal is adjusted to be zero in a state where no torque is applied to the torque transmission shaft 11. In this state, when a torque T is applied to the torque transmission shaft 11 in the direction shown by the dotted arrow in the figure, a tension σ is applied to the magnetic metal ribbons 12□, 12□ in the +45° direction with respect to the circumferential direction. , also the same 4
A compressive stress -σ is generated in the direction of 5°. As a result, the induced magnetic anisotropy of the magnetic metal ribbon 121 is strengthened, while the induced magnetic anisotropy of the magnetic metal ribbon I2□ is weakened. When the magnetic properties of the magnetic metal ribbon 121.12□ change in this way, a voltage difference between the voltage across the detection winding 15□ and the voltage across the detection winding 15□ is generated. Further, when a torque in the opposite direction of the torque transmission shaft 11 is applied, these operations will be in the opposite direction to that described above. The magnitude of the torque T applied to such torque transmission #111 and the detection winding 15□.

The relationship between the phase detection of the signal from 15□ and the voltage V converted into DC by the integrator 24 is as shown in FIG. 6 or 7, as described in the prior art.

In the case shown in FIG. 6, the relationship between the direction of torque application and the voltage changes nonlinearly with respect to the origin.

Therefore, by using the amplifier 26 after converting the current to direct current using the integrator 24, the torque T and voltage v can be changed as shown in FIG.
The relationship between Q can be linearized. amplifier 26
is composed of resistors 27, 28, 29, diodes 30, 31, and an operational amplifier 32, and is the output V of the amplifier 26 when the input voltage V is ■〉O. is the resistance 27.28.29 R,,R
2, R, then vo= −(R, /R,) x v −(
1). Also, the output V of the amplifier 26 when V is 0. is V, = −(R, /R,) X V
-■, and if the output voltage changes non-linearly from the origin with respect to the direction of the torque T, then from equation (1) 20, the resistance 28.29, that is, R,, R, is changed to a variable resistor. By adjusting the gain, it is possible to make it linear as shown in Figure.

As described above, according to the first embodiment, when the relationship between the direction of torque application and the voltage is non-linear with respect to the origin, that is, when the detection sensitivity differs with respect to the direction of torque application, a circuit for performing sensitivity correction is used. Since the torque signal is obtained by inputting the torque, the obtained signal can have linearity.

Next, a second embodiment of the present invention will be described using the circuit diagram shown in FIG. In the previous embodiment, since the gain is adjusted using a variable resistor, it is difficult to perform sensitivity correction of the characteristics shown in FIG. Therefore, in FIG. 3, the operation of the amplifier 26 in the first embodiment is corrected by software using an arithmetic processing circuit 33 including a microcomputer, so that the relationship between the direction of torque application and the voltage is made linear. In the case of reproducible characteristics such as the characteristics shown in Figure 7, by storing the relationship between torque and voltage in a memory etc. in advance so that it becomes a linear characteristic, any characteristic can be easily reproduced. Sensitivity can be corrected. Further, as shown in FIG. 6, nonlinear characteristics with respect to the origin can be corrected by determining and storing the sensitivity correction gain in advance.

As described above, the present invention can be implemented with various modifications without departing from the spirit thereof.

〔Effect of the invention〕

As detailed above, according to the torque detection device of the present invention,
By correcting the detection sensitivity of the torque detection signal from the detection head, the relationship between the direction of torque application and voltage can be made linear, providing highly accurate and stable torque detection.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a torque detection device according to an embodiment of the present invention, FIGS. 2 and 3 are circuit diagrams of a first embodiment and a second embodiment of the torque detection device, and FIG. 4 is a diagram showing the relationship between the output voltage and torque of the device, FIG. 5 is a schematic configuration diagram of a conventional torque detection device, and FIGS. 6 and 7 are diagrams showing the relationship between the output voltage and torque of the conventional device. It is. 1.11...Torque transmission shaft 2, 12. , 12. ...Magnetic metal ribbon 131.13
□...Detection magnetic core 14. ．． 14□・・・Excitation winding 1
51, 15□...Detection winding 21...Drive circuit 2
2, 26...Amplifier 23...Phase detector 2
4... Integrator 25... Phaser 27.2
8, 29...Resistor 30.31...Diode 32...Operation amplifier 2S

Claims (1)

[Claims] A detection head in which a magnetic metal ribbon having magnetostriction is attached to a torque transmission shaft, and changes in the magnetic properties of the magnetic metal ribbon in response to rotational torque applied to the torque transmission shaft are used as a torque detection signal. What is claimed is: 1. A torque detection device for non-contact detection, comprising: a sensitivity correction means for correcting signal sensitivity in order to adjust the rate of change of the torque detection signal to a predetermined rate of change.