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Continuous Variable Valve Timing: Description

The CVVT (Continuously Variable Valve Timing) which is installed on the exhaust camshaft controls intake valve open and close timing in order to improve engine performance.

The intake valve timing is optimized by CVVT system depending on engine RPM.

This CVVT system improves fuel efficiency and reduces NOx emissions at all levels of engine speed, vehicle speed, and engine load by EGR effect because of valve over-lap optimization.

The CVVT changes the phase of the intake camshaft via oil pressure.

It changes the intake valve timing continuously.

Fig 1: Intake Valve Timing Graph
G04810111Courtesy of HYUNDAI MOTOR CO.
INTAKE VALVE TIMING SPECIFICATION

Driving Condition Intake Valve Timing Effect
Light load (1) Retard Stable combustion
Part load (2) Advance Enhanced fuel economy and exhaust emissions
High load & Low RPM (3) Advance Enhanced torque
High load & High RPM (4) Retard Enhanced Power