| 摘要 |
PURPOSE:To obtain excellent combustion of an engine, by keeping the piston- ring sliding range at a low temperature by constituting at least the head portion of a piston and the upper half of a cylinder liner by a ceramics material having a low coefficient of heat conduction. CONSTITUTION:In a piston 17 fitted into a cylinder block 1 with a cylinder liner 6, at least the upper half of which is made of a ceramics material such as silicon nitride having a low coefficient of heat conduction, a piston head 17A formed with a recess at its top is made of the same ceramics material as the upper half of the cylinder liner 6. Further, a ring portion 17B and a skirt portion 17C of the piston 17 are made of a unitary metal material, and they are bonded firmly to the head portion 17A at a bonding portion 19 by way of soldering or diffusion bonding. In such an arrangement, the length L of a top land 17E from the top surface of the head portion 17A to the first piston-ring groove 17F is so seleced that it is equal to or greater than 1/4 of the diameter of the head portion 17A. |
