Injection pulse time determination - by comparing exhaust signal with reference using circuit to compensate for rich or lean mixt.

摘要

The arrangement to determine the duration of fuel injection pulses comprises an exhaust oxygen sensor (1) whose output signal is compared with a threshold voltage (9) in a comparator circuit (7), producing an output indicating rich or lean mixture, the fuel being supplied synchronously with engine rotation as a function of engine speed and intake air flow, preferably by solenoid-operated injection valves. A circuit (12) is provided which receives the variable lower voltage limit of the sensor and acts on a threshold adjusting circuit (Ti) such that the threshold voltage, which opposes the sensor output, remains above the lower sensor voltage limit at all times.