GB1478157A - Method and apparatus for measuring and displaying the unbalance in a rotor - Google Patents

Abstract

1478157 Measuring rotor unbalance AVERY-DENISON Ltd 21 Oct 1974 [7 Feb 1974] 45421/74 Heading G1N Apparatus for measuring rotor unbalance comprises: an electro-mechanical transducer, and means for combining the transducer signal with a reference signal whose frequency corresponds to the rotor speed; an A-D converter; digital display means for displaying the combined signal in magnitude and sign, and operable in a number of different modes according to the co-ordinate system, units and decimal point position; and means for adjusting the combined signal and for placing the display means in an appropriate mode. Analogue voltage UMI - UMS represent rotor unbalance components in each of two planes as X and Y co-ordinates, and the rotor speed; alternatively the unbalance components may be expressed as polar co-ordinates, according to the setting of a selector switch 27. Each signal in turn, e.g. U M1 , selected at 21, is integrated at 22 for a fixed time determined by a control member 23 connected to a clockpulse generator 26; then the integral is reduced to zero by subtracting from it the integral of a fixed voltage UK, whereupon a comparator 25 signals the control member 23 to transfer a pulse count, accumulated at 24, to a store e.g. 30a as a digital measure of the magnitude of U M1 : a driver 31a feeds a coded magnitude signal, with a further signal representing the sign of U M1 , to a display 32a. The display 32a also receives, from a device 33, calibration information related to machine characteristics, the type of co-ordinate system, and the position of the decimal point. The five signals U M1 - U M5 , processed in time-division multiplex, are displayed on respective displays 32a-32e. Means, Fig. 2 (not shown) sensing when the magnitude of any analogue U M1 - UMS exceeds a predetermined magnitude appropriate to the full range of the display, provides a signal which may warn the operator to switch the range; preferably however the range is switched, and the input signal attenuated as necessary, by automatic means. Further means make appropriate changes when the input signal is insufficient to use one tenth of the selected range. Other means may be provided for cancelling a display if the measured quantity is insignificant on the most sensitive range.