A Study of Two-Stroke Engine Braking for HD Diesel Engines

Different compression release two-stroke braking concepts are presented and one is thoroughly studied by simulation and test. The two-stroke braking concept studied here is achieved by eliminating the normal exhaust event and opening an exhaust valve near both compression TDC (first braking event) and exhaust TDC (second braking event). A second “intake” is achieved by keeping the exhaust valve open during the normal expansion stroke after the first braking event, allowing exhaust gases to be reintroduced to the cylinder for the second braking event. Excellent correlations are obtained between simulation results and test data. More than a 40% braking power increase has been achieved by using two-stroke braking compared with the conventional single event braking four-stroke cycle.