Driving device for fuel injection solenoid valves

Claim 1

A driving system for fuel injection solenoid valves in an electrical fuel injection system for an internal combustion engine having time operated air intake valves, comprising: driving and holding coils independently provided to each of said fuel injection solenoid valves, a pulse source for producing timing pulses in synchronism with the timing with which said air intake valves in said engine are operated, first means for determining the time intervals during which each one of said injection solenoid valves is opened depending upon the operating condition of said engine, second means for produCing valve holding pulses in synchronism with said timing pulses and each having a voltage level only sufficient to hold one of said solenoid valves open when applied to the holding coil of said one and having a pulse width determined by said time interval determined by said first means, third means for producing valve driving pulses in synchronism with said timing pulses and each having a voltage level and a pulse width only sufficient to open one of said solenoid valves instantly when applied to the driving coil of said one valve, and means for applying said driving and holding pulses respectively to said driving and holding coils of the corre-sponding one of said solenoid valves.