Improvement of the Performance on the Small-Scale PCCI Engine Fuelled by Natural Gas (2nd Report) - Effects of the internal EGR by pilot-opening of an intake valve in an exhaust stroke

摘要

To control the combustion timing of a natural-gas PCCI (premixed charge compression ignition) engine, the internal EGR by pilot-opening of an intake valve in an exhaust stroke was applied to a single cylinder test engine, and effects of EGR rate on the engine performance and exhaust emissions were investigated. The EGR rate was continuously changed by the variable valve actuation system, which can vary the pilot-opening duration. The experimental results show that the combustion timing with the same heat consumption is advanced by the increase in the EGR rate, and the higher combustion efficiency and larger indicated mean effective pressure can be obtained compared to the case without EGR.