Pre-combustion chamber-type engine

摘要

The present invention provides a pre-combustion chamber-type engine, which optimizes the relation between the heat capacity of the pre-combustion chamber structure that forms the pre-combustion chamber and the displacement per cylinder and thereby improves the net average effective pressure and fuel efficiency. In this pre-combustion chamber-type engine, which has the pre-combustion chamber structure 15 installed in the cylinder head 3 so that it is surrounded by a heat insulating layer, the ratio of the heat capacity of the pre-combustion chamber structure to the displacement per cylinder is set to 0.35 cal/ DEG C.xcm3 or less. Alternatively, the ratio of the heat capacity of the pre-combustion chamber structure to the inner surface area of the pre-combustion chamber is set to 0.55 cal/ DEG C.xcm2 or lower.