Patent GB-992338-A (GB)
Title: Improvements in or relating to an engine analyser
IPC: F02P17/02
Filed: 1962-01-25
Abstract: 992,338. Engine analyses. T. NAKAGAWA. Jan. 25, 1962, No. 2771/62. Heading G1U. An engine analyser comprises an electrical or mechanical pickup device developing a synchronizing signal of period corresponding to one revolution of a distributer or fuel injector, generating means responsive to the synchronizing signal for successive control signals mutually phase displaced in quadrature which respectively control gate circuits energized from transducer circuits responsive to amplitudes of primary and secondary voltages and currents and the phases thereof in an ignition coil circuit, or cylinder pressure at TDC or explosion pressure, and inlet and exhaust manifold pressures, so as to excite a cathode ray oscillograph displaying the engine variables as stationary waveforms. In Fig. 1 a pickup device P electromagnetically coupled to a high tension plug lead from the distributer produces a synchronizing pulse train of rotational period corresponding to distributer rotation; which triggers a signal pulse generator 1 whose output is shaped at 2 and squared at 3 to energize in parallel a ¢ frequency divider 4, amplifier 5, and phase inverter 6 to produce distinct square wave signals C, A, and B respectively of equal amplitudes of which A, C are combined to control gates 11, 14 and B, C to control gates 12, 13. Gates 11, 12 operate on positive pulses and gates 13, 14 on negative pulses, so that they open in succession over time periods a, b, c, d, (Fig. 2) to pass signals V p , I p , V s , I s  to the Y plates of C.R. oscillograph 18 from the primary voltage and current and the secondary voltage and current of the ignition coil feeding the distributer and plugs (Fig. 6, not shown). The oscillograph X timebase from generator 16 is triggered from I p , so that the display traces appear stationary and in synchronism. In a modification (Fig. 3) two shaping circuits 2, 2<SP>1</SP> and square wave generators 3, 3<SP>1</SP> are energized in parallel from the pulse signal generator 1 to respectively energize amplifier 5 and ¢ frequency divider 4; and phase inverter 6 with ¢ frequency divider and inverter 4; to produce square wave outputs A, B, C, D which are combined so that gate 11 is controlled by AC, gate 12 by CB, gate 13 by AD and 14 by BD is respective combination (Fig. 4). Alternatively two inversely responsive gate circuits are alternatively switchable to the outputs of amplifiers responsive to V p , I p  and V s , I s  respectively, in combination with fundamental squarewave A, so that any two of the parameters can be displayed selectively on the oscillograph; the wave A being derived from a synchronizing pickup as in Fig. 1. The synchronizing signal may be obtained photo-electrically from the top dead centre mark of an engine flywheel or fuel injection pump, or from explosion pressure or fuel injection pressure in a specific cylinder through a suitable transducer, or mechanically from a rotating member of an injection pump. The apparatus may also display signals representing inlet and exhaust manifold pressures, derived from appropriate transducers.