Patent GB-748049-A (GB)
Title: Vibration analyser
IPC: G01H1/00
Filed: 1953-11-30
Abstract: 748,049. Electric correspondence control systems. WITHERS, J. S. (Lion Manufacturing, Inc.). Nov. 30, 1953, No. 33165/53. Class 40(1) [Also in Group XIX] Apparatus for analysing the vibrations of a rotating machine having parts moving at different rotary speeds comprises an inductive pick-up for measuring the vibrations, and stroboscopic means actuated by the vibration signal component having the maximum amplitudes for indicating the part producing the greatest vibrations, since that part will appear to be stationary in the light of the stroboscopic lamp, and includes means for determining the rotary speed of that part and the amplitude of the vibrations. The apparatus also includes an adjustable oscillator which may alternatively be fed to the stroboscope so that the speed of each of the different parts may be determined. As shown (Figs. 1, 2), an inductive pickup 10 feeds vibration signals into a preamplifier 11 comprising two RC coupled valves 22, 23, followed by an amplitude indicator 13 wherein the signals are integrated at 156, amplified at RC coupled valves 164, 165, and rectified by diodes 191 192, the resulting current being indicated by a meter 203 whose sensitivity is selected by switch 210 and is proportional to the amplitude of the vibration signals. The amplified signals from 11 are also fed via a change-over switch 18 to a unit 12, where they are further amplified at valve 52, followed by a frequency indicator unit 15, where they are first limited by diodes 221, 222, and amplified at valve 232 for feeding to a square wave generator valve. 257, wherein each signal changes the anode current from zero to maximum. The resulting square waves are integrated by resistor 261 and condenser 268 or 269, as chosen by ganged switch 264, for rectification by diodes 265, 266, and the resulting current, which is proportional to the frequency of the vibration signals, is indicated by meter 275 whose sensitivity is selected by ganged switch 278. The amplified signal in unit 12 is also differentiated by an an RC network 60, 66 and the resulting positive pulse triggers a valve 62 with a preadjusted bias obtained from power supply unit 16 to actuate, a stroboscope 14. Unit 12 also contains two sections 71, 72 each comprising two valves 73, 74 and 75, 76, each dividing the pulse frequencies by two and feeding into a further trigger valve 111, the appropriate output frequency being chosen by a ganged switch 69. 70, 110, 264, 276, 278. Unit 14 contains a stroboscopic valve 127 which, in the first three positions of the ganged switches is fired by valve 62, and in the other two switch positions is fired by valve 111, in the fourth position the frequency being divided by two, and in the fifth position the frequency being divided by four. The frequency range to be indicated by stroboscopic valve 127 may be extended by the addition of further dividing sections to unit 12. The apparatus also includes a Weinbridge oscillator 17 for independent strobatron study, connected to the stroboscope 14 by operation of switch 18. The frequency of the oscillator is adjusted by a double potentiometer 289 to synchronize with the RPM of a moving part and is indicated on meter 275.