GB1273793A - Electric fuel-injection control systems - Google Patents

Abstract

1,273,793. Fuel injection control systems. TOYOTA TIDOSHA KOGYO K. K. July 29, 1969 [Aug. 7, 1968, Sept. 10, 19681, No.38015/69. Heading G1N. In an I. C. engine fuel injection control system, the duration of opening pulses for the electromagnetically controlled injection valves, is controlled in dependence upon the back pressure in the inlet manifold and the engine speed, and are supplied to the electromagnetic valves 2-5 in a sequence according to a signal synchronous with the engine speed. As shown, the output pulses of a monostable multi-vibrator 9 have constant width and amplitude and a recurring frequency dependent upon the back pressure, this output being combined, in a sawtooth generator 10 including an integrating and switching circuit, Fig. 3 (not shown), with the output of a pulse generator 11 producing pulses of a frequency synchronous with the operation of the injection valves and thus the engine speed. The sawtooth output has a slope and frequency dependent upon back pressure and engine speed and is applied to one input of two differential amplifiers 13, 14, the other inputs of which are supplied with a reference voltage from a frequency/voltage converter of the output of generator 11. When the accelerator is depressed, the back pressure decreases, and the slope of the sawtooth wave decreases and its frequency increases. During the period when the sawtooth output is lower than the reference voltage, an opening pulse is supplied via distributors 15, 16 and driving units 17-20 to one of the electromagnetic valves 2-5. When the sawtooth output is the same as the reference voltage the pulse is ended. If now the accelerator is eased off, the back pressure increases, the slope of the sawtooth increases and its frequency decreases, and the reference voltage decreases and therefore the duration of the pulses supplied to the electromagnetic valves decreases. In an alternative, Fig. 7 (not shown) the output of the oscillator 8 having a frequency dependent upon the back pressure is converted into a D. C. signal which is then corrected by the signal from the generator 11 to produce a reference voltage. This reference voltage is applied to one input of four differential amplifiers, one for each electromagnetic valve, to the other inputs of which is applied the output of a respective sawtooth generator triggered by the signal from the generator 11.