Cylinder block,cylinder head, and engine main body

摘要

A cylinder block ( 10 ) is such that a main body cylinder block ( 4; 404 ) and an outer cylinder block ( 6; 406 ) are molded separately. As a result, the portion of the die which is used to mold a water jacket ( 50; 450 ) does not need to be made thin, thereby increasing the life of the die. Further, cylinders ( 12; 412 ) are of a simple shape and the pressure in the axial direction of the cylinder ( 12; 412 ) is able to be dispersed substantially evenly between the cylinders ( 12; 412 ) and the outer cylinder block ( 6; 406 ), thus enabling the cylinders ( 12; 412 ) to be thin. Accordingly, there is an increased degree of freedom in design of the portion which forms the water jacket ( 50; 450 ). The water jacket ( 50; 450 ) and the cylinders ( 12; 412 ) can therefore both be made sufficiently thin, thereby contributing to a decrease in both the size and weight of the engine.