GB1252510A - - Google Patents

Abstract

1,252,510. Measuring torque photoelectrically. SUD-AVIATION SOC. NATIONALE DECONSTRUCTIONS AERONAUTIQUES. Dec. 2, 1969 [Dec.9, 1968; Nov. 21, 1969], No. 58787/69. Headings G1A and G1W. A torque measuring arrangement comprises a disc with apertures attached to one shaft which is rigidly attached to a second coaxial shaft, the second shaft being provided with a radial projection which extends across the aperture so that a light beam extending from a fixed source to a fixed opto-electronic detector is separated into two portions. As the shafts rotate the two signals obtained are compared to measure the relative offset between the shafts and thus the transmitted torque. As shown in Fig. 1, a tubular shaft 1 connects driving and driven shafts M, R respectively and is provided with a disc 4 rigidly attached to shaft 1 and provided with apertures 5. A second shaft 7 is secured to one end to shaft 1 by cone coupling 8 and is supported coaxially within shaft 1 by bearing 9. A disc 6 is rigidly attached to shaft 7 and is provided around its periphery with a plurality of radial teeth 12 which are arranged to correspond with apertures 5. The disc 4 is cranked so that the apertures and teeth are in the same plane. A flat radial light beam is provided from a fixed source so that each aperture X, Y is scanned as the shafts rotate and photo-transistor 28 is energized accordingly. As the torque changes the size of apertures X, Y will change so that the duration of signals x, y will be proportional to their widths. For any given scan that speed can be considered constant and thus the torque is proportional to the difference between signals x, y. The circuit shown in Fig. 5 produces a signal at 59 which is a measure of the transmitted torque. Signals from photo-transistor 28 are amplified at 29 and passed to a remote amplifier 34 whose output is partly fed back through pulse clipping Zener diodes 101, 102 and integrator 75 to base 103 of photo-transistor 28 so that the pulses leaving amplifier 34 are correctly shaped and spaced. The pulses leaving amplifier 34 pass through gates 35, 40 to trigger circuits 21, 22 (monostable and bi-stable respectively) which reset the system after the passage of each pair of pulses. The pulse are separated by gate circuit 23 so that line m is positive for signal y and line n is positive for signal x and these signals are integrated by capacitors 47, 49 in unit 27. Further processing by amplifiers 51, 52 which together with voltage divides 53, 54, 55, 56 provides a differential amplifier giving the sum and difference of the integrated signals. The difference value is displayed on an indicator calibrated as torque. To compensate for temperature variation a temperature probe including a thermistor may be inserted in the feedback circuit of the amplifier and the probe disposed near shaft 1.