Continuously Variable Valve Duration (CVVD) Device

Hyundai Motor Group

New engine technology to debut in Smartstream G1.6 T-GDi engine

The operation of the intake CVVD device

FIG. 5A illustrates a neutral state in which the rotational center of the camshaft 30 and the cam unit 70 coincide with each other. 

The roller wheel 60 includes: a wheel body 62 slidably inserted into the camshaft 30 and a wheel head 64 rotatably inserted into the first sliding hole 86. A cam shaft hole 34 is formed in the camshaft 30 and a wheel body 62 of the roller wheel 60 is movably inserted into the camshaft hole 34.

When the vehicle is maintaining a constant speed and requires low engine output, CVVD opens the intake valve from the middle to end of the compression stroke. This helps to improve fuel efficiency by reducing the resistance caused by compression. On the other hand, when engine output is high, such as when the car is driving at a high speed, the intake valve is closed at the beginning of the compression stroke to maximize the amount of air used for the explosion, enhancing torque to improve acceleration.