Detecting and processing circuitry for magnetostriction type torque sensor
First Claim
1. A torque sensor processing circuitry of a magnetostriction type, comprising:
- a) at least one detection coil installed on an outer periphery of a magnetostrictive shaft of the torque sensor;
b) an oscillator which is so constructed as to generate and output a reference waveform;
c) an inverting circuit, connected to said oscillator via a resistor, and having a negative feedback circuit connected between an input end thereof and an output end thereof, said feedback circuit having the detection coil;
d) a phase shift circuit which is so constructed as to output a reference signal whose phase is shifted by a phase difference of 1/4 period with respect to the reference waveform derived from said oscillator;
e) a detector which demodulates an inverted signal Va derived from the inverting circuit on the basis of the reference signal derived from said phase shift circuit; and
f) an integrator which integrates an output signal of the detector, the integrated output signal of said integrator being related to a direction and a magnitude of a torque applied to the magnetostrictive shaft.
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Accused Products
Abstract
A detection and processing circuitry of a magnetostriction type torque sensor is disclosed. An alternating current voltage signal Vo is generated and output from an oscillator. A shift circuit shifts a phase of the AC voltage waveform of the oscillator by 1/4 period and outputs the phase shifted voltage to a detector. The detector modulates the inverted voltage signal Va on the basis of the phase shifted voltage signal and an integrator integrates the detector output voltage in a time range from (α-π/2) to (α-3π/2). Thus, the output voltage signal Vd from the integrator indicates a resistance value of an imaginary part, i.e., inductance of the impedance of the detection coil of a magnetostrictive shaft of the torque sensor which is not dependent on the change in a temperature.
48 Citations
8 Claims
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1. A torque sensor processing circuitry of a magnetostriction type, comprising:
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a) at least one detection coil installed on an outer periphery of a magnetostrictive shaft of the torque sensor; b) an oscillator which is so constructed as to generate and output a reference waveform; c) an inverting circuit, connected to said oscillator via a resistor, and having a negative feedback circuit connected between an input end thereof and an output end thereof, said feedback circuit having the detection coil; d) a phase shift circuit which is so constructed as to output a reference signal whose phase is shifted by a phase difference of 1/4 period with respect to the reference waveform derived from said oscillator; e) a detector which demodulates an inverted signal Va derived from the inverting circuit on the basis of the reference signal derived from said phase shift circuit; and f) an integrator which integrates an output signal of the detector, the integrated output signal of said integrator being related to a direction and a magnitude of a torque applied to the magnetostrictive shaft. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A signal processing circuit for a torque sensor, comprising:
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a) at least one detection coil fixed to an external rigid body, and installed around a magnetostrictive shaft, said magnetostrictive shaft being interposed between ends of a rotating shaft so that its permeability is varied according to a direction and magnitude of the torque applied to the magnetostrictive shaft via the rotating shaft and so that an inductance of said detection coil is accordingly varied; b) an oscillator which is so constructed as to generate and output a reference waveform having an alternating voltage; c) an inverting circuit, connected to said oscillator via a resistor and having a negative feedback circuit connected between an input end thereof and an output end thereof, said feedback circuit having the detection coil; d) a phase shift circuit which is so constructed as to output a reference signal having a phase shifted by a phase difference of 1/4 period with respect to the reference waveform derived from said oscillator; e) a detector to demodulate an inverted signal output from the inverting circuit on the basis of the reference signal derived from said phase shift circuit; f) an integrator to integrate an output signal of the detector to compensate for an iron loss generated in the detection coil so that an integrated output signal indicates a signal corresponding to the inductance of the detection coil without a presence of the iron loss generated in the detection coil.
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Specification