GB1089783A - Improvements relating to the continuous measurement of relative speed between two rotating members - Google Patents

Abstract

1,089,783. Speed difference determination. COURTAULDS Ltd. July 17, 1964 [July 17, 1963], No. 28250/63. Heading G1A. To determine the difference in speed (or a function thereof) between two members each is connected to a device producing pulses at a rate proportional to its speed, the pulse trains so produced are applied to trigger a bi-stable circuit in opposite directions and the time the circuit is in one of its stable states determined. As described the arrangement is used to measure the amount that yarn stretches during sizing. The yarn is fed from a supply drum 1 over feed roller 2 to the sizing and drying plant 4 from which it is drawn out over take-up roller 5 on to winding up beam 6. The stretch of the yarn is related to the difference in speed with which it passes over the rollers 2 and 5. Slotted discs 8 and 9 are shown directly coupled for rotation with these rollers and each disc is positioned between a light source and a photo-transistor. The output pulses from the detectors are amplified and fed to trigger a bi-stable circuit in apposite directions. Resultant pulse output signals may be derived from either side of the bi-stable circuit and in the circuit described Fig. 2 (not shown), the output from one side is applied to a circuit giving a meter indication of a mean potential representing the on-off time ratio of waveform whilst that from the other side is applied to a similar circuit feeding a recorder. An inter-connection between the circuits compensates for the switching time of the bi-stable circuits. To avoid troubles due to low beat frequencies between the two pulse trains it is preferred to make one pulse train have a slightly higher repetition rate than the other for the same speed of the two members. The resulting error in the indicator can be removed by applying a steady bias potential. Instead of the discs 8 and 9 being directly mounted on the shafts of rollers 2 and 5 they may be mounted on spindles carrying friction wheels which can be brought into contact with the rollers.