Method for predicting knock, method for suppressing knock, and engine system

An engine system, comprising:

• a combustion chamber including a cylinder;
• a fuel supply including an injector that supplies fuel including gasoline into the combustion chamber;
• a spark plug;
• and
• circuitry configured to:
• inject, using the injector, fuel into the combustion chamber;
• ignite the spark plug which begins an initial stage of the combustion of an air-fuel mixture which includes the fuel in the combustion chamber, the initial stage of the combustion being from immediately after a start of the combustion of the air-fuel mixture by the spark plug to a subsequent occurrence of a knock, the igniting of the spark plug causing spark controlled compression ignition within the combustion chamber, an engine including the combustion chamber having a compression ratio of greater than 14;
• obtain, in the initial stage of combustion of an air-fuel mixture in the combustion chamber, a pressure in the combustion chamber;
• compare the pressure in the initial stage of combustion with a reference value and determine whether the pressure exceeds the reference value;
• predict the knock will occur before an end of the combustion when the pressure exceeds the reference value;
• and
• injecting, using the injector, a fluid into the combustion chamber before an end of the combustion in order to suppress the knock, when the knock is predicted to occur when the pressure exceeds the reference value.

A non-transitory computer readable medium including instructions which, when executed by a processor, perform control of an engine system by executing the steps of:

• injecting, using an injector, fuel into a combustion chamber;
• igniting a spark plug which begins an initial stage of combustion of an air-fuel mixture which includes the fuel in the combustion chamber, the initial stage of the combustion being from immediately after a start of the combustion of the air-fuel mixture by the spark plug to a subsequent occurrence of a knock, the igniting of the spark plug causing spark controlled compression ignition within the combustion chamber, an engine including the combustion chamber having a compression ratio of greater than 14;
• obtaining, in the initial stage of combustion of the air-fuel mixture in the combustion chamber, a pressure in the combustion chamber, wherein the initial stage of the combustion is during the process of the combustion from immediately after a start of the combustion of the air-fuel mixture to the subsequent occurrence of a knock;
• comparing the pressure in the initial stage with a preset reference value and determining whether the pressure exceeds the reference value;
• predicting the knock will occur before an end of the combustion when the pressure exceeds the reference value;
• and
• injecting, using the injector, a fluid into the combustion chamber before an end of the combustion in order to suppress the knock, when the knock is predicted to occur when the pressure exceeds the reference value.