| 摘要 |
PURPOSE:To reduce the shearing force caused by the frictional force without increasing the contact area of a piston ring, by applying a coating layer of a soft material having a thickness smaller than 1/2 of the thickness of the piston ring over the surface of a cylinder in a cylinder block made of a head material. CONSTITUTION:A cylinder block 1 is made of a hard material 9 such as cast iron, steel or ceramics, and a soft material 10 such as high-silicon aluminum is cast on the inner surface of the hard material 9 in the manner of forming a multi-layer structure. Here, the thickness of the soft material 10 is selected to be smaller than 1/2 of the thickness of a top ring 4, although the layer of the soft material 10 is required to be sufficiently thick for enabling casting of the same. Thus, since the hard material 9 is disposed at the region where a high stress is acted, deformation of the soft material 10 can be prevented, so that the shearing force caused by the frictional force can be reduced without increasing the contact area A of the top ring 4. |
