INTERNAL COMBUSTION ENGINE AND COMBUSTION CONTROL METHOD THEREFOR

PROBLEM TO BE SOLVED: To reliably control a rate of compression self-ignition combustion in a combustion system wherein spark-ignition combustion and compression self-ignition combustion are combined so as to suppress unburned HC discharge, and to improve heat efficiency. SOLUTION: The internal combustion engine includes: a pair of exhaust valves 8, and a pair of intake valves 7; an ignition plug 9 installed in about the center position of a combustion chamber 1; and a tumble control valve variably controlling the strength of tumble flow. In the region of low to medium load, ignition is turned on at a specified ignition timing, and the flame propagation 21 after the spark ignition is distorted by harnessing a pair of vortexes T1, T2 caused in the tumble flow, and an end gas areas 22 are allowed to remain on the intake valve 7 side in the combustion chamber 1. The end gas area 22 is compressed to self-ignition before flame propagation by increase in the cylinder pressure due to spark ignition combustion, and the combustion is completed at an early stage. The size of the end gas area 22 self-ignited by compression is controlled by the strength of the tumble flow. COPYRIGHT: (C)2010,JPO&INPIT