Patent ID: 7720590
Filing Date: 2010-05-18
Classification: F02B,F02D,Y02T

Abstract:
1. A homogeneous charge compression ignition (HCCI) engine, wherein the HCCI engine allows a combustion mode to be switched between an HCCI combustion and a spark ignition combustion, the HCCI engine comprising: a combustion chamber; an intake valve; an exhaust valve; an intake variable valve mechanism for changing an intake lift amount, which is a lift amount of the intake valve, wherein the intake lift amount is set to a first intake lift amount in the HCCI combustion, and the intake lift amount is set to a second intake lift amount in the spark ignition combustion; an exhaust variable valve mechanism for changing an exhaust lift amount, which is a lift amount of the exhaust valve, wherein the exhaust lift amount is set to a first exhaust lift amount in the HCCI combustion, and the exhaust lift amount is set to a second exhaust lift amount in the spark ignition combustion; and a controller for controlling the intake variable valve mechanism and the exhaust variable valve mechanism, wherein the controller sets an internal EGR amount, which includes the amount of burned gas that remains in the combustion chamber at the time of the HCCI combustion, by setting a negative valve overlap period, during which both of the intake valve and the exhaust valve are closed, such that not all the burned gas is discharged from the combustion chamber, and wherein, when switching the combustion mode from the HCCI combustion to the spark ignition combustion, the controller executes following operations a) and b) before switching the intake lift amount from the first intake lift amount to the second intake lift amount, a): switching the exhaust lift amount from the first exhaust lift amount to the second exhaust lift amount while ensuring the internal EGR amount, and b): delaying a closing timing of the exhaust valve so as to reduce the internal EGR amount after switching the exhaust lift amount from the first exhaust lift amount to the second exhaust lift amount.