Engine system

An engine system provided to a vehicle having an accelerator pedal, comprising:

• a supercharger driven by a crankshaft of an engine;
• an electromagnetic clutch disconnectably connecting the crankshaft to the supercharger;
• and
• a processor configured to execute:
• a determining module to determine, based on a target engine torque and an engine speed, whether an operation range of the engine is either one of a first range where the electromagnetic clutch is disengaged and a second range where the electromagnetic clutch is engaged;
• and
• a controlling module to control the engagement and disengagement of the electromagnetic clutch based on the determination of the determining module, and an opening of the accelerator pedal,
• wherein when the determining module determines that the operation range of the engine shifts from the second range to the first range after the opening of the accelerator pedal increases at an increase rate below a given reference increase rate, the controlling module switches the electromagnetic clutch from the engaged state to the disengaged state after a given basic stand-by period passes from the shift to the first range, and
• wherein when the determining module determines that the operation range of the engine shifts from the second range to the first range after the opening of the accelerator pedal increases at an increase rate at or above the reference increase rate, the controlling module switches the electromagnetic clutch from the engaged state to the disengaged state after a given acceleration stand-by period passes from the shift to the first range, the acceleration stand-by period being longer than the basic stand-by period by a given added period.