Patent ID: 9267421
Filing Date: 2016-02-23
CPC Classification: F02B,F02F,Y02T

Claim Text:
1. A combustion chamber structure for an engine that comprises: a cylinder block having one or more cylinders; a cylinder head that covers the cylinder from one side in a cylinder axis direction; a piston reciprocatingly inserted into the cylinder; intake valves provided at a ratio of two valves per cylinder at one side thereof from among two regions separated by a crankshaft axis; and exhaust valves provided at a ratio of two valves per cylinder at an opposite side thereof from among the two regions separated by the crankshaft axis, and that is adopted to the engine in which compressed self-ignition is performed in at least a low-load range, wherein a geometric compression ratio of the cylinder is set to 15 or higher; a cavity is formed in a central portion of a crown surface of the piston; a part of a valve head of each intake valve overlaps the cavity, as viewed in the cylinder axis direction; valve recesses for preventing interference between the piston and the valve heads of the intake valves are formed in the piston crown surface so as to be connected to the cavity; an axial line of the intake valve is inclined to recede from a cylinder axis with increasing distance from the valve head, as viewed in the cylinder axis direction, and a gap between the piston crown surface and a region which is a part of a lower surface of the valve head, at least on a side that is closer to the crankshaft axis, expands in accordance with an approach of the crankshaft axis; and a relationship of G