COMBUSTION CHAMBER STRUCTURE FOR ENGINES

A structure of a combustion chamber for an engine includes a crown surface of a piston, a combustion chamber ceiling surface, an injector and an ignition plug provided on the combustion chamber ceiling surface, and an intake opening and an exhaust opening opened in the combustion chamber ceiling surface. A side where the intake opening is opened is defined as an intake port side, and a side where the exhaust opening is opened is defined as an exhaust port side, with respect to a center portion of the combustion chamber as a reference, in a plan view from one side in a cylinder axis direction. An ignition portion of the ignition plug is disposed on the intake port side. The ignition plug is ignited at a timing after the piston passes a compression top dead center. The injector is disposed on the center portion, and is configured to inject fuel toward the exhaust port side. A cavity, which is recessed in the cylinder axis direction in a region on the exhaust port side with respect to a position below the ignition portion, is provided on the crown surface of the piston. A reverse squish flow generation portion, which draws an air-fuel mixture toward the intake port side as the piston moves in an expansion stroke, is provided in the combustion chamber.