Abstract: An engine system includes a combustion chamber and an air supplier. The combustion chamber is formed in a cylinder. The air supplier is configured to supply air to a circumferential area of the combustion chamber. The circumferential area is near an inner circumferential surface of the cylinder. The air supplier is configured to supply air to the circumferential area before ignition to gather a rich air-fuel mixture that is present in the combustion chamber to a central area of the combustion chamber such that a stratified body consisting of a layer of the air-fuel mixture in the central area and a layer of the air in the circumferential area is formed.

Abstract: An engine system includes a combustion chamber and an air supplier. The combustion chamber is formed in a cylinder. The air supplier is configured to supply air to a circumferential area of the combustion chamber. The circumferential area is near an inner circumferential surface of the cylinder. The air supplier is configured to supply air to the circumferential area before ignition to gather a rich air-fuel mixture that is present in the combustion chamber to a central area of the combustion chamber such that a stratified body consisting of a layer of the air-fuel mixture in the central area and a layer of the air in the circumferential area is formed.

Abstract: A relay drive unit drives a relay by supplying a power source voltage from a battery. The relay drive unit includes a power source voltage detector, a drive signal generator, and a relay drive circuit. The power source voltage detector detects the power source voltage. The drive signal generator generates a PWM signal as a drive signal for maintaining the relay in an ON state. The PWM signal has a preset duty ratio according to a magnitude of the power source voltage detected by the power source voltage detector. The relay drive circuit turns a supply of the power source voltage from the battery on/off based on a duty ratio of the drive signal generated by the drive signal generator.