To provide an engine and an engine ignition method which can ignite a fuel accurately and securely at a desired ingnition time, in a simple structure without adding a new device to an existing engine.
While a recess 2b is formed to the upper part of a piston 3 and one side of a cylinder head 2a, a projection 3b is formed to the other side of the piston 3, and an auxiliary combustion chamber 6 having a compressive ratio larger than a main combustion chamber 4 is formed by the recess 2b and the projection 3b. As a result, the fuel is ignited earler in the auxiliary combustion chamber 6 having the compressive ratio larger than the main combustion chamber 4, and the fuel in the mixing gas in the main combustion chamber 4 is ignited accurately and securely at a desired ingnition timing, by the ignited mixing gas flowing out to the main combustion chamber 4.
WAKAMOTO KOTARO
MUROTANI TAISUKE
