Compression ignition gasoline engine

A compression ignition gasoline engine comprising:

• a cylinder for accommodating a piston to be reciprocally movable;
• a fuel injection valve for injecting fuel containing gasoline as a main component into the cylinder;
• an EGR device operative to perform high-temperature EGR of introducing burnt gas generated in the cylinder into the cylinder at a high temperature;
• and
• a combustion control unit for controlling the fuel injection valve and the EGR device in such a way that HCCI combustion in which fuel injected from the fuel injection valve self-ignites within the cylinder occurs, wherein
• the combustion control unit controls the EGR device in such a way that, in at least a partial load operating range in which HCCI combustion is performed, an EGR rate increases, as compared with a low load condition, in a high load condition in which G/F being a ratio between a total amount of gas and a fuel amount within the cylinder decreases, and
• a geometric compression ratio of the cylinder is set to be not smaller than 18 but not larger than 22.

A compression ignition gasoline engine comprising:

• a cylinder for accommodating a piston to be reciprocally movable;
• a fuel injection valve for injecting fuel containing gasoline as a main component into the cylinder;
• an EGR device operative to perform high-temperature EGR of introducing burnt gas generated in the cylinder into the cylinder at a high temperature;
• and
• a combustion control unit for controlling the fuel injection valve and the EGR device in such a way that HCCI combustion in which fuel injected from the fuel injection valve self-ignites within the cylinder occurs, wherein
• the combustion control unit controls the EGR device in such a way that, in at least a partial load operating range in which HCCI combustion is performed, an EGR rate increases, as compared with a low load condition, in a high load condition in which G/F being a ratio between a total amount of gas and a fuel amount within the cylinder decreases, and
• the EGR device is a valve variable mechanism operative to perform internal EGR of letting burnt gas generated in the cylinder remain in the cylinder, as the high-temperature EGR.