GB1364546A - Apparatus for regulating the duration of a square-wave signal in an electronic injection control installation for diesel engines - Google Patents

Abstract

1364546 Electronic fuel injection systems for Diesel engines SOFREDI 9 Aug 1971 [14 Aug 1970] 37393/71 Heading G1N In a Diesel engine fuel injection control system, the duration of injection control pulses is determined in dependence upon the value of a regulating voltage, which is triggered in synchronism with engine rotation, at the instant of the beginning of each injection control pulse. As shown, an engine driven pulse generator I triggers, with each pulse, Fig.4a, a number of monostable multi-vibrators and associated current generators MM1 + GI1 &c., a reference signal control device CSR, a switch CO3 and an injection control device CDI, the multi-vibrators being arranged to be triggered to their unstable state at different intervals to cause their associated current generators to supply differing currents to a capacitor VR to thereby form a voltage on the capacitor which has the form shown in Fig.4c. The device CSR, in the form of a monostable multi-vibrator, provides a pulse T o , Fig. 4b, to a current generator GC, such that a capacitor in a memory device can be charged at the end of each pulse T o via a switch CO1 which is coupled to a switch CO2 so that when the voltage across the memory capacitor reaches the level of the reference voltage on the capacitor VR, the voltage on the memory capacitor can follow this reference voltage, Fig.4d. When the next engine triggered pulse occurs and thus pulse T o occurs, the voltage on the memory capacitor is maintained, and the injection control pulse T i initiated by this pulse has its duration controlled by this capacitor voltage. The injection control device CDI also includes a monostable multi-vibrator. The injection control pulse T i is amplified at 4 and applied to a distributor, the end of each injection control pulse causing a device CO4 to discharge the memory capacitor. Fig.3 (not shown) gives details of these circuit elements. Thus, since the point at which the memory capacitor voltage is maintained is variable with engine speed, the duration of the injection control pulses is also variable. The monostable multivibrator and pulse generator MM3 + GI3 provides a voltage (see dotted line of Fig. 4c) which has an amplitude suitable for lengthening the injection control pulses for starting purposes. A relay may be inserted between the pulse generator I and this multi-vibrator to operate only with the starting switch.