Engine system

An engine system, comprising:

• an engine having a water jacket formed around a combustion chamber;
• a circulation system that is attached to the engine and circulates coolant through the water jacket;
• and
• a controller configured to control the circulation system according to an operating state of the engine,
• wherein the circulation system includes:
• a radiator passage including a heat exchanger;
• a bypass passage bypassing the heat exchanger;
• a coolant control valve that adjusts a flow rate of coolant flowing through the water jacket by adjusting a flow rate of coolant flowing through each of the radiator passage and the bypass passage;
• and
• a thermally-actuated valve that is connected to the radiator passage and opens to allow the coolant to pass through the heat exchanger,
• wherein the engine has a spark plug that forcibly ignites an air-fuel mixture,
• wherein the engine switches between a first combustion in which the air-fuel mixture combusts without the forcible ignition of the spark plug, and a second combustion in which the air-fuel mixture combusts by the forcible ignition of the spark plug,
• wherein the controller is electrically connected to the coolant control valve, and
• wherein when the engine performs the first combustion, the controller controls the coolant control valve to adjust the flow rate of the coolant flowing through the water jacket according to a load of the engine, by closing the radiator passage and adjusting the flow rate of the coolant flowing through the bypass passage.