| 摘要 |
PURPOSE:To improve resistance to heat and durability, by a method wherein composite reinforcement is made on the head part of a titled piston by the use of reinforcing fiber having a thermal expansion rate lower than that of a light metal, and as a portion is increased in temperature, the volume rate of reinforcing fiber is increased. CONSTITUTION:A piston 1 for a direct injection type diesel engine is formed by an aluminium alloy, and a combustion chamber dent 3, having a conical projection 5 protruded along an axis 4, is formed in the central part of a head part 2. In which case, composite reinforcement is made on the top surface of the head part 2 by the use of alumina tow having a mean fiber size of 3.2mu, a mean fiber length of 2mm., and composition of 95wt% Al2O3 and 5wt% SiO2. In which case, the volume rate of the alumina tow in first - third region, which are set, in order, around the opening end of the combustion chamber dent 3, is set to, for example, 8%, 3%, and 1%, and as a portion is increased in temperature, a thermal expansion preventing effect is increased. |
