GB1502094A - Apparatus for simulating an internal combustion engine ignition distributor - Google Patents

Abstract

1502094 Ignition systems; timing ignition LUCAS ELECTRICAL Ltd 14 Jan 1975 [5 Dec 1973] 56359/73 Heading F1B Apparatus for simulating an internal combustion engine distributer comprises an encoder 10 for producing a pulse train of frequency proportional to the engine crank-shaft speed, means for producing a synchronizing pulse (at an output terminal 10a) at a specific position of the engine crank-shaft, a dividing circuit 15 for producing an output pulse each time a given number of pulses of the pulse train are received thereby, means for varying the given number of pulses in accordance with the number of sparks required in each revolution and means 13, 14 for setting a variable delay between production of the synchronizing pulse and setting of the dividing circuit such delay being dependent on engine operating parameters. The time at which a spark occurs is determined by the instant at which the particular coil current ceases to flow. This occurs when the distributer 17 energizes an output line and the counter 19 starts to count and inhibits an output gate 18 and will depend upon the angular time between the synchronizing pulse from the encoder 10 and the carry pulse from the counter 14 which in turn depends upon the input voltage to the ADC 13. The optical couplers 21 are used to feed switching transistors 22 controlling the current to the ignition coils 23. One function generator 25 produces an output under the influence of a D.C. voltage proportional to engine speed developed by a frequency to voltage converter 24. A second function generator 29 produces a varying output voltage under the influence of two pressure transducers 26, 27 connected to the inlet manifold or throttle of the engine. A variable frequency test pulse generator 47 can be switched into the circuit to simulate the synchronizing and “ degree pulses normally obtained from the encoder 10.