Patent GB-979013-A (GB)
Title: Apparatus for testing the unbalance of a rotating part of a machine
IPC: G01M1/22
Filed: 1961-06-22
Abstract: 979, 013. Electric selective signalling systems. SOC. NOUVELLE D'ELECTRONIQUE ET DE LA RADIO-INDUSTRIE. June 22, 1961 [June 22,1960], No. 22715/61. Heading G4H. The unbalance of a rotating member, e.g. the crankshaft 1, Fig. 1, of an internal combustion engine, is sensed by two pick-up leads 8, 9 in which are induced alternating voltages whose amplitude and phase represent in polar co-ordinates the respective unbalance vectors V 1 <SP>1</SP>, V 2 <SP>1</SP> in the sensing planes. The system described converts these voltages to D.C. voltages representing the component vectors V 1 <SP>1</SP>x, V 1 <SP>1</SP>y, V 2 <SP>1</SP>x, V 2 <SP>1</SP>y in Cartesian co-ordinate, digitizes these D.C. voltages and calculates the component correction vectors V 1 x, V 1 y, V 2 X V 2 y which represent the amount of metal which must be removed on the x and y axes of the correction planes 4, 5 to balance the crankshaft. If a correction vector e.g. for plane 4, is found to be negative, metal is removed from planes 5, 6, this operation having the same effect as adding metal in plane 4. Metal is removed in planes 4, 5, 6 by a pair of machinery heads arranged on the x and y axes defined by the angular positions of the crankshaft at which the angular displacements 0 degrees and 90 degrees of a reference voltage occur, this voltage being produced by alternator 120 or a photo-electric generator. The component correction vectors are given by: - Operation: Heads 8, 9 each supply a pair of amplifiers 113,114, Fig. 2, the amplifiers having gains of (e + d)/2d and (e - d)/2d so that their outputs on leads 15a, 15b and 16a, 16b represent V 1 <SP>1</SP> and V 2 <SP>1</SP> multiplied by these factors. Reference voltages with phases 0 degrees and 90 degrees derived from alternator 120 are utilized in units 230, 260 to produce clock pulses on leads 21-1 to 21-4, 22A,22B,25,27,28a,28b as shown in Fig. 3. Pulses on lead 25 mark the instants at which the 0 degrees reference voltage passes through zero in cycle A (lead 22A energized), and leads 21-1 to 21-4 are energized in turn over successive cycles of this reference voltage. Gates 311-314, Fig. 7, each produce an output pulse at times corresponding to angular positions 0, # during successive revolutions of the crankshaft. Gates 315-318 are only opened by the outputs of gates 311-314 if the respective sinusoidally varying input on leads 15a, 15b, 16a, 16b, is positive, and the voltages thus sampled, representing the right hand sides of equations (3), (4), are supplied in succession to an analogue store 319. The stored samples are fed in turn to a digitizer 331 (block 330) which produces a train of pulses representing in number the analogue input. Unit 210 produces a train of pulses on lead 26 which alternately mark the positive half cycles of the two sensed voltages on leads 15a, 16a. The pulses on leads 28a, 28b respectively mark the instants at which the positive and negative half-cycles of the 0 degrees reference voltage commence, and thus the signs of vectors V<SP>1</SP> 1 y and V 2 <SP>1</SP>y are determined by gates 333, 334 which control gates 338, 339 so that the output of converter 331 is supplied to the add or subtract lead of counter 340. When the first two pulse trains have entered counter 340 (R.H.S. of equation (3)), pulse generator 343 is started and feeds pulses on lead 38 to return counter 340 to zero. The sign of the contents of counter 340 appears as a marking on lead 39a or 39b and determines which of gates 338, 339 is opened during the resetting period. When the counter again reaches zero, matrix 334 delivers a pulse to stop generator 343. The pulses on lead 38 are applied to an appropriate counter for V 1 y in a store 460 through a gating circuit 410 which is controlled by the sign bit on leads 39a, 39b and the clock pulses on leads 21-1 to 21-4 and 22A, 22B. The next two numbers (R.H.S. of equation (4)) are then entered in counter 340 and the sum is transferred to the appropriate counter for V 2 y in store 460. The process is repeated with lead 22B energized and a differently phased set of clock pulses (right hand side of Fig. 3) in order to determine the components V 1 x and V 2 x. If a component of a correction vector e.g. V 1 x is negative, lead 39b is energized when the transfer to store 460 takes place and the pulses on lead 38 are gated in circuit 410 to the store counters for V 2 x and V 0 x (V 0 x being the x component of a correction vector in plane 6). The stored components may be used to control the necessary machining operations either directly or after transferring the data to a punched card or tape.