| 摘要 |
PROBLEM TO BE SOLVED: To realize a prescribed EGR in all the operating areas of an engine by introducing EGR gas into a gas trunk provided below a cylinder, compressing the EGR gas during the inlet stroke of a piston and supplying the EGR gas to a combustion chamber from an EGR gas supply passage by lowering the piston. SOLUTION: When an inlet valve 10 is opened in an intake stroke, air supplied (fresh air) from a supercharger 30 is supplied to a combustion chamber 13 simultaneously with the lowering of a piston 12. When the piston 12 is lowered and its lower edge closes a gas supply port 8a, EGR gas supplied to an EGR gas trunk 5 in an exhaust stroke is compressed in the rear side of the piston 12. When gas pressure reaches pressure higher than the pressure set by an EGR gas pressure regulating valve 6, the valve 6 is opened and a part of the EGR gas is discharged to an exhaust pipe 17 side. Further, when the piston 12 is lowered to open the gas supply port 8a, the EGR gas in the EGR gas trunk 5 enters the combustion chamber 13 from an EGR gas supply pipe 8 and is mixed with the fresh air (charging) so as to be used for combustion. |
