The oil control valve, which consists of a solenoid valve that operates under duty cycle control, is mounted to the cylinder head and used in hydraulic pressure control for switching the cams.

When the coil of the oil control valve is not energized (duty cycle ratio: 0%), port B closes, ports A and C open to each other, causing the oil that was acting on the cam switching control piston to be discharged from port C via port A. When the coil is energized (duty cycle ratio: 100%), the spool valve moves, port A closes, and ports B and C are open to each other. The oil that is pumped by the oil pump flows via ports B and C and acts on the cam switching control piston.