GB1364554A - Fuel injection systems for internal combustion engines - Google Patents

Abstract

1364554 Intermittent fuel injection systems for I C engines ROBERT BOSCH GmbH 6 Oct 1971 [6 Oct 1970] 46378/71 Heading G1N In an I.C. engine intermittent fuel injection system, the duration t i of the injection valve energizing pulses S is made proportional to the product of the mean value of the air intake quantity rate and the time duration T p required for a pre-set angle of rotation of the engine crank-shaft, the pulses S being provided by circuitry controlled by the amount J r by which the heating current through a temperature dependent resistor 30 arranged in the intake manifold 25, must be raised, above the heating current required at zero engine speed, to maintain the temperature of the resistor constant, the duration of these pulses S being proportional to the product of T p and the square value of J r . As shown, the resistor 30 is arranged in a bridge circuit and a voltage U s proportional to the heating current is supplied to an integrator 40 which is arranged to integrate a voltage proportional to J r for the period T p by way of pulses of duration T p provided by a bistable circuit 41 and trigger 18. During the ported T p a capacitor in the integrator 40 is charged in dependence upon J r to a voltage U 1 , see Fig. 3. The capacitor is then linearly discharged over a period t c which is therefore proportional to the product of J r and T p . During the interval t c , a differentiator 42 provides a square pulse of duration t c , this pulse controlling a second integrator 43 to charge a second capacitor to a value U 2 in dependence upon J r via the voltage U s . This second capacitor is then discharged linearly for a period t i which is proportional to the product of J r and t c i.e. to the product of J r <SP>2</SP> and T p . During the interval t i a second differentiator 44 provides the pulse S of duration t i . The integrators 40, 43 preferably include an operational amplifier having the capacitor in its feedback circuit, Fig.5 (not shown), the differentiators 42, 44 also including an operational amplifier, Fig. 6 (not shown). In an alternative, a capacitor is charged, during the rotational time T p , with a charging current J a in a stepwise manner with a number of pulses f during a time t a , the capacitor storage voltage U s = f.t a .J a .T p attained being reduced with constant discharge current to provide the pulse time t i . Two of the factors f, t a , J a , T p are made proportional to the regulating current J r .