| 摘要 |
PURPOSE:To obtain a good layer-forming combustion by varying the injection timing in accordance with the load so that, as the load is decreased, the number of injection flows impinging upon a shallow recessed portion may be smaller and the number of injection flows impinging upon a guide groove may be correspondingly larger. CONSTITUTION:A combustion chamber 4 is provided in the top surface of a piston 2 and has a deep recessed portion 4a at its bottom and a shallow recessed portion 4b at its top. A guide groove 4c for guiding a fuel is provided, in the vicinity of an ignition plug 7, at an upper part of the deep recessed portion 4a. When the engine is in a range of low load, the whole flow of the fuel injected from injection ports 6a, 6b is so arranged as to impinge upon only the shallow recessed portion 4b and guide groove 4c. Injection timing is varied, in accordance with the load, so that, as the load becomes lower, the number of injection flows impinging upon the shallow recessed portion 4b may be smaller and the number of injection flows impinging upon the guide groove 4c may be correspondingly larger. By this, a fuel-air mixture of fixed concentration having a good ignitability is formed near an ignition plug 7 independently of a necessary fuel injection quantity while a fuel-air mixture of a concentration corresponding to the fuel injection quantity is formed in the combustion chamber.
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