Patent ID: 7818112
Filing Date: 2010-10-19
Classification: F02B,F02D,F02M,Y02T

Abstract:
1. A homogeneous charge compression ignition engine operated in combustion modes switchable between homogenous charge compression ignition combustion and spark ignition combustion, the engine comprising: a combustion chamber; an intake passage through which flows fresh air that is drawn into the combustion chamber; an exhaust passage through which flow exhaust gas that is discharged from the combustion chamber; an external exhaust gas recirculation apparatus which performs external exhaust gas recirculation by supplying the intake passage with some of the exhaust gas discharged to the exhaust passage and mixing the exhaust gas supplied to the intake passage with fresh air; a driving state detection unit which detects a driving state of the engine; and a control unit which executes combustion control by specifying either one of a homogeneous charge compression ignition combustion range and a spark ignition combustion range based on the driving state of the engine detected by the driving state detection unit and a combustion range map for specifying the combustion range that is in accordance with the driving state; wherein the combustion range map includes the homogenous charge compression ignition combustion range, the spark ignition combustion range, and a switch preparation combustion range that is included in the spark ignition combustion range and extended along a boundary between the spark ignition range and the homogeneous charge compression ignition combustion range; the control unit lowers the temperature in the combustion chamber when the switch preparation combustion range is specified by executing a control for reducing the amount of internal exhaust gas recirculation or having the external exhaust gas recirculation apparatus perform the external exhaust gas recirculation; reducing the amount of the internal exhaust gas recirculation or performing external exhaust gas recirculation is continuously performed when the switch preparation combustion range is specified; and the homogeneous charge compression ignition combustion is continuously performed until the spark ignition combustion range except for the switch preparation combustion range is specified once the homogeneous charge compression ignition is performed.