Vehicle engine fuel injection timing control - has blocking circuit to prevent fuel shut=off at low loads at high speed

摘要

An oxygen analyser is the engine exhaust feeds a comparator whose output is fed to an integrating amplifier. THe output of the amplifier controls the duration of the fuel injection pulse. A flip flop circuit has a timing input from a circuit triggered by the injection pulses. The flip flop feeds a comparator which compares the duration of the flip flop output with the duration of the injection pulses. These are fed into its second input. When the pulse duration drops below a preset value, the comparator energises a switching circuit which blocks the integrating amplifier. This prevents fuel being shut off completely when there is no power demand on the engine at high vehicle speeds.