Torquemeter circuit

Abstract

A circuit for generating a potential indicative of torque. The circuit responds to the phase angle between the AC signals generated by two generating coils or magnetoelectric pickups, each excited by a toothed wheel. The two toothed wheels are connected to different points along a shaft transmitting power between an engine and its load. The windup or torsion of the shaft is proportional to torque; therefore, the relative phase angle of the signals from the two pickups is also proportional to torque. Each generating coil is connected to a high-gain input amplifier which generates a square-wave signal in phase with the signal from the coil. Each input amplifier triggers a pulse generator which generates a pulse the leading edge of which is in fixed phase relation to the pickup signal. The two pulse generator outputs are connected to a flip-flop circuit to generate a zero output signal during the interval between the two inputs to the flip-flop. The duty cycle of this signal is indicative of torque. The flip-flop output signal is transmitted through two driver circuits to an averaging circuit including two integrating circuits in series which provides an output potential proportional to torque. Each integrating circuit includes means for calibrating the circuit in response to a simulated predetermined torque signal. One calibration establishes a zero or datum point and the other establishes the gain of the circuit. The circuit is particularly insensitive to variations in speed of the torque shaft and ambient temperature.