GB1281339A - Improvements in the measurements of twist in rotating shafts - Google Patents

Abstract

1281339 Measuring torque HAWKER SIDDELEY DYNAMICS Ltd 10 Sept 1969 [13 Sept 1968] 43760/68 Headings G1A and G1N [Also in Division G4] The torque of a rotating shaft is measured by generating a signal the phase of which relative to a reference signal represents the torque. In one embodiment two contacting discs (A, B), Fig. 3 (not shown) having a basic pattern of m and m+n opaque and transparent portions are fixed to the rotating shaft at different positions. (Preferably n-1). As torque is transmitted by the shaft the phase of the signal from a receiver 13, Fig. 4, receiving light through both the discs varies with respect to the phase of the signal from a detector sensing reference markers on one of the discs, pulses being accumulated in a counter 21 between zero crossings in predetermined direction of the signals. Preferably these pulses are derived from a reference pattern on one of the discs. The count is displayed. Horse power and horse-power-hours may be measured by accumulating the pulses between zero crossings of the signal for a predetermined length of time and by using the counter as a totalizer respectively. An analogue output signal may be obtained in time ration form. By comparing the amplitude of the signal from the detector 13 with the number of reference pulses an analogue indication of the torque within a revolution of the shaft may be obtained. In a modification two magnetic patterns are written on the shaft a fixed distance apart from which frequency signals proportion to m and m+1 are derived from pick-up heads sensing the patterns. These signals are amplified and added to give a difference frequency the phase of which relative to a reference signal from a third head receiving one pulse per revolution of the shaft represents the torque. The output from one of the heads may be used for counting. In further modifications (a) the reference markers may be on a third disc, (b) a cyclic disturbance may be put on the patter of either of the discs to generate the reference signal, (c) concentric cylinders or semicircular discs may be used and (d) reflective and non-reflective patterns may be used.