| 摘要 |
PURPOSE:To provide stable combustion state for improving the performance of an engine by surrounding a hot plug by use of a thin and cylindrical liner having low heat conductivity and then mounting such hot plug in a cylinder head. CONSTITUTION:A hot plug 10 is surrounded by a thin and cylindrical liner 11 which has an inner diameter longer than the external diameter of the hot plug, and then mounted inside a cylinder head. The cylindrical liner 11 has upper and lower annular beads 12 and 13 formed on the inner face threof so as to hold the hot plug 10 with a clearance between the cylindrical liner. A heat-insulating air layer 17 is therefore defined by the liner 11, the hot plug 10 and the beads 12 and 13 so that heat conductivity from the hot plug 10 to the cylinder head 2 may be reduced and the insulating characteristics of the hot plug be improved. Stable combustion state will then be obtained and the performance of an engine be improved. |
