| 摘要 |
The combustion chamber structure(3) having a combustion chamber(2) almost at the center of the piston (31) is installed in a cavity(8) formed in the piston body(1) with a heat insulating layer(12, 15) interposed therebetween. The combustion chamber structure(3) and the piston body(1) are joined by a joining member. The combustion chamber structure(3) is formed with a nozzle insertion hole(9) and communication holes(10). The joining member is made of a material with a thermal expansion coefficient intermediate between those of piston body(1) and the combustion chamber structure(3), or of almost the same kind of material as the piston body(1). Alternatively, the combustion chamber strucure(3) forms a piston head portion(5A) and the piston body(1) forms a piston skirt portion(4). The lower surface(45) of the piston head portion(5A) is formed as a tapered surface that is inclined toward the periphery. The upper surface(46) of the piston skirt portion(4) is also formed as a tapered surface that extends along the opposing tapered surface of the piston head portion(5A). The lower surface(56) of the outer periphery of the piston head portion(5A) and the upper surface(57) of the outer periphery of the piston skirt portion(4) are in firm contact with each other. The combustion chamber structure of this invention is so constructed that a rich air-fuel mixture is generated in the upper part(A) of the combustion chamber(2) and that the mixture is quickly ejected into the cylinder chamber(20) to reduce the combustion period. <IMAGE> |
