Engine system

An engine system, comprising:

• a combustion chamber to which an intake flow passage and an exhaust flow passage are connected;
• an exhaust gas purification catalyst provided to the exhaust flow passage;
• a turbocharger including:
• a turbine arranged on the exhaust flow passage;
• and
• a compressor arranged on the intake flow passage;
• a bypass flow passage for connecting an upstream side and a downstream side of the turbine on the exhaust flow passage;
• a bypass valve configured to open and close the bypass flow passage;
• a detector configured to detect a temperature of the exhaust gas purification catalyst, and
• a controller configured to control the bypass valve and a compression ratio of the combustion chamber,
• wherein, when the temperature of the exhaust gas purification catalyst is smaller than a first threshold value, the controller controls the bypass valve to an open state and controls the compression ratio to a high compression ratio larger than a minimum compression ratio, and
• when the temperature of the exhaust gas purification catalyst is equal to or larger than the first threshold value, the controller controls the bypass valve to a closed state and maintains the high compression ratio.