JPS61191930A - Magnetostrictive type torque detector - Google Patents

Abstract

PURPOSE:To eliminate non-contacting of the output voltage by providing a DC excitation means, by inversely magnetizing a shaft to be measured to a saturation area until dependence of the output voltage on the angle of rotation is gotten rid of while an output voltage integration circuit is provided. CONSTITUTION:A shaft 1 to be measured is wound with an excitation core 2 to be excited by an AC power source 7 and also an excitation coil 9 to be excited by a DC power source 8. An integrator 18 is provided at the rear stage of a sample holding circuit 19 of a torque detector output voltage processing circuit. Then, when the values of the DC excitation and AC excitation are set as specified, the shaft 1 being measured can be inversely magnetized easily to the saturation area with a small excitation current. The output 16 of the sample holding circuit 19 is integrated with an integrator 18 to eliminate non- continuity in the output 17 after the integration. Thus, a torque detector having a stable output voltage can obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to torque measurement of a power transmission shaft, and particularly to a torque measurement device suitable for non-contact detection of static and rotational torque.

[Background of the invention]

The conventional device is 4! As described in Japanese Patent Application Publication No. 57-72033, the axis to be measured is reversely magnetized to the saturation region. However, no consideration was given to the means for magnetizing to the saturation region and the circuit for processing the output.

[Purpose of the invention]

The purpose of the present invention is to provide a DC excitation means to easily reverse magnetize the shaft to be measured to the saturation region, eliminate the rotation angle dependence of the output voltage, and provide an output voltage integration circuit to achieve discontinuity in the output voltage. An object of the present invention is to provide a magnetostrictive torque sensor without a point.

[Summary of the invention]

The present invention has a problem in that when the shaft to be measured is reversely magnetized in the unsaturated region, the output voltage of the torque detector fluctuates due to the rotation of the shaft to be measured because the magnetic characteristics on the circumference of the shaft to be measured are non-uniform. . Therefore, we focused on the fact that the saturation magnetic flux density of the measured axis is constant at any point on the circumference, and in order to reverse magnetize the measured axis to the saturation region with limited power supply voltage and current,
From the technical standpoint that it is easy to use AC excitation and DC excitation together, and from the technical standpoint that discontinuities in the output voltage waveform after sampling and holding can be eliminated by installing an integrator at the subsequent stage. This will be implemented.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows a torque detector according to the present invention, in which an AC excitation coil 4
A DC excitation coil 9 is further wound around the excitation core 2 around which the coils a and 4b are wound. FIG. 2 shows the magnetization curve of the shaft 1 to be measured. Figure 3 shows the magnetization curve when DC excitation is applied to the measured shaft 1 in addition to the AC power supply 7, and (a)
In this case, there is no DC excitation, and the AC voltage is swung within a range that does not saturate the magnetic flux.

Under such conditions, the magnetic flux operating loop has no saturation region. In case (d), a large DC excitation is applied, and the measured axis l is saturated over almost the entire operating cycle. Therefore, if the values of DC excitation and AC excitation are appropriately selected to create an operation loop like (b) or (C), the measured axis can be
It has the effect of being able to magnetize up to the saturation region.

FIG. 6 shows an embodiment of the torque detector output voltage processing circuit according to the present invention, in which an amplifier 1O is connected to the detection coil 5, a sampling and holding circuit is connected to the rear stage of the amplifier, an integrator is further connected, and the sampling and holding circuit is connected to the detection coil 5. The circuit generates a pulse once per period by a sampling timing generator 11 connected to the AC power supply 7 to perform sampling in a phase in which the measured axis l of the excitation AC power supply 7 is saturated. This is the circuit that does this. Furthermore, it includes a DC power supply 8 for an excitation coil 9 for DC excitation of the shaft to be measured. FIG. 5 shows the waveforms of each part of the torque detector output processing circuit, and the output of the square wave generator has waveforms 20, 20,
The output 13 of the current amplifier is waveform 21, the output 14 of the bypass filter is waveform 22, and the output 15 of the Wereshot Multi
is a waveform 23, the output 16 of the sampling and holding circuit is a waveform 24, and the output 17 after integration is a waveform 25. Providing the integrator 18 after the sampling and holding circuit 19 has the effect of eliminating discontinuities in the output voltage.

〔Effect of the invention〕

According to the present invention, if AC excitation and DC excitation are used together to alternately magnetize the axis to be measured up to the saturation region, the excitation current can be reduced, and by providing an integrator after the sampling and holding circuit, the output This has the effect of eliminating voltage discontinuities.

[Brief explanation of drawings]

Fig. 1 is a torque detector according to the present invention, Fig. 2 is a magnetization curve diagram of the shaft to be measured, Fig. 3 is a magnetization curve diagram of the shaft to be measured when DC excitation is applied, and Fig. 1 is a diagram of the magnetization curve of the shaft to be measured. Torque detector output voltage processing circuit. FIG. 5 shows waveforms of various parts of the output voltage processing circuit. DESCRIPTION OF SYMBOLS 1... Axis to be measured, 2... Excitation core, 3'... Detection core, 7... AC excitation power supply, 8... DC excitation power supply, 9... DC excitation coil, 18 ...integrator, 19
...Sample ¥, '2-prisoner

Claims (1)

[Scope of Claims] 1. Magnetostrictive torque detection characterized in that an AC power source and a magnetostrictive torque sensor driven by the AC power source are provided with DC excitation means for saturating a measured shaft having high magnetostriction sensitivity. Device. 2. A magnetostrictive torque detection device according to claim 1, further comprising an output processing circuit that performs sampling and holding at and around the timing when the magnetic flux of the shaft to be measured is saturated. 3. A magnetostrictive torque detection device in the output processing circuit according to claim 2, characterized in that an integrating circuit is provided after the sampling and holding circuit.