Integral Helmholtz resonator for improving diesel engine performance, comprises calculator controlled valves on exhaust feed back heat exchanger and air intake pipe dimensioning to produce Helmholtz effect

摘要

The internal combustion engine (10) has an exhaust gas re-circulating pipe (50) which includes a heat exchanger (54) with valves (58,62) at either end. The valves are controlled by an engine calculator (60) and the lengths (L1,L2) of the air pipework are chosen to produce two Helmholtz frequencies. At low speeds both valves are closed, at higher speeds both are opened and at top speed one is opened to give a Helmholtz resonance.