In-cylinder direct injection diesel engine

摘要

PURPOSE:To reduce the soot, unburnt HC and the like in exhaust gas by injecting the compressed air inside a squish area into a combustion chamber through a compressed air injection passage, causing turbulent flow of air inside the combustion chamber and accelerating the mixture of air and injected fuel. CONSTITUTION:When a piston 2 moves upward, an annular wall 6 is fitted to a cavity 5, and also the opening 11a on the combustion chamber side of an air communication passage 11 inside the piston is closed by the outside surface 6b of the annular wall 6, and at the same time the opening 12b on the squish area side of an air communication passage 12 inside the annular wall is closed by the inside surface 5a of the cavity, so that the squish area 10 is isolated from the combustion chamber 9. When both the air communication passages 11, 12 are mutually communicated, a compressed air jetting passage for communicating the squish area 10 with the combustion chamber 9 is formed. As a result, the air compressed by the rise of the piston 2 inside the squish area 10 is jetted through the compressed air jetting passage at high speed, so that the mixture of the fuel injected from a fuel injection valve 4 and air can be accelerated.