Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 03, 2017 - September 06, 2017
The effects of fuel injection timing and coolant temperature on soot and particulate emissions at stoichiometric mixture condition under heating mode were examined in a single cylinder spark ignition direct injection gasoline engine. Single injection was employed and the start of fuel injection timing was adjusted in the intake stroke. The gross indicated mean effective pressure and the 50% heat release angle were set to 0.7 MPa and 9 deg.ATDC respectively by adjusting the intake air pressure, injected fuel mass and ignition timing. Regardless of coolant temperatures, with advancing the injection timing close to the top dead center, the exhausted soot mass concentration and particulate number are increased, mainly due to more liquid fuel impinging the combustion chamber walls and resulting in wider and more rich fuel-air mixture around the walls. Regardless of fuel injection timings, with decreasing coolant temperature, the exhausted soot mass concentration and particulate number are increased. To maintain the same load and combustion phasing, more amount of liquid fuel should be injected, due to the lower in-cylinder temperature and wall temperture with lower coolant temperature, resulting in more unevaperated fuel and wider zone for rich fuel-air mixture near the combustion chamber walls. Compared to coolant temperature, the injection timing should be well designed to decrease the particulate matter emission.
