GB1431772A - Control systems for engines - Google Patents

Abstract

1431772 Engine control systems LUCAS ELECTRICAL CO Ltd 2 July 1973 [15 July 1972] 33235/72 Heading G3N [Also in Division F 1] A control system for an engine operating parameter, e.g. fuel injection quantity or ignition timing angle, comprises at least two transducers 7, 8 producing outputs dependent upon the values of engine parameters, e.g. speed, throttle angle, manifold depression, a memory unit to which the outputs are fed, the memory unit providing a binary output dependent upon the transducer outputs, and control means 23 operable in accordance with the binary output for controlling the operating parameter, at least one of the transducers, e.g. 7, producing an output which can have p different values, the memory unit being capable of receiving less than p different inputs, but the system further including a converter 9 for converting the range p to a smaller range q that can be handled by the memory unit. As shown, the transducer 7 is responsive to throttle angle and has a 4-bit binary output which is converted in the converter 9 to a 3-bit binary output which is applied to a unit 12 which energizes one of eight lines 14a - 14h depending on the throttle angle. The lines 14a - 14h are connected to respective switches 15a - 15h, a line closing its corresponding switch when energized. The transducer 8 is responsive to engine speed and produces a 3-bit binary output which is applied to a unit 11 which energizes one of 8 lines 13a - 13h depending on the engine speed. The lines 13a - 13h cross each line of 8 sets of lines 16a - 16h, diodes being positioned at selected crossover points. Depending upon which of the switches 15a - 15h is closed, and which of the lines 13a - 13h is energized, the appropriate 5-bit binary output is applied via lines 21 to a decoder 22 whose output is applied to the control deivce 23, e.g. a fuel injection pump. A converter which converts a 5-bit binary input to a 4-bit binary output is described with reference to Fig. 4 (not shown). However, it is not necessary to change the number of bits in the converter. It is merely necessary to change the range from an original number e.g. 32 to, say, 20 numbers.