CVVT Oil Control Valve (OCV) Description and Operation

Description

The Continuously Variable Valve Timing (CVVT) system advances or retards the intake and exhaust valve timing according to the ECM control signal, which is calculated from engine speed and load. Under CVVT control, valve overlap or underlap is achieved, which improves fuel economy and reduces exhaust emissions (NOx, HC) and improves engine performance by reducing pumping losses, internal exhaust gas recirculation effect, improving combustion stability, improving volumetric efficiency and increasing expansion work. This system consists of the CVVT Oil Control Valve (OCV), which supplies engine oil to or shuts off engine oil from the cam phaser according to the ECM PWM (Pulse Width Modulation) control signal; the CVVT Oil Temperature Sensor (OTS), which measures engine oil temperature; and the Cam Phaser, which changes the camshaft phase using hydraulic pressure from the engine oil. Engine oil flowing from the CVVT oil control valve changes the camshaft phase in the advance direction (intake advance/exhaust retard) or the opposite direction (intake retard/exhaust advance) relative to engine rotation, by rotating the rotor connected to the camshaft inside the cam phaser.