System to regenerate an exhaust particle filter in a diesel engine

A calculator (18) receives data from a differential pressure sensor (20) at a catalyser and particle filter, temperature sensors also at the catalyser and filter (21,22,23) and an exhaust gas oxygen content sensor (24). The data is used to control the supply of an additive (16) which lowers the combustion temperature of the exhaust particles to the fuel and also to trigger multiple fuel injection during firing strokes to optimise catalyser operation