KIA Niro: CVVT & Camshaft Description and operation

Description

Continuous Variable Valve Timing (CVVT) system advances or retards the valve timing of the intake and exhaust valve in accordance with the ECM control signal which is calculated by the engine speed and load.

By controlling CVVT, the valve over-lap or under-lap occurs, which makes better fuel economy, reduces exhaust gases (NOx, HC) and improves engine performance through reduction of pumping loss, internal EGR effect, improvement of combustion stability, improvement of volumetric efficiency, and increased expansion work.

This system consists of

• the CVVT Oil Control Valve (OCV) which supplies the engine oil to the cam phaser or runs out the engine oil from the cam phaser in accordance with the ECM
  PWM (Pulse With Modulation) control signal,
• the CVVT Oil Temperature Sensor (OTS) which measures the engine oil temperature,
• and the Cam Phaser which varies the cam phase by using the hydraulic force of the engine oil.

The engine oil released from the CVVT oil control valve varies the cam phase in the direction (Intake Advance/Exhaust Retard) or opposite direction (Intake Retard/
Exhaust Advance) of the engine rotation by rotating the rotor connected with the camshaft inside the cam phaser.

Operation Principle

The CVVT has the mechanism of rotating the rotor vane with hydraulic force generated by the engine oil supplied to the advance or retard chamber in accordance with
the CVVT oil control valve control.

1. Intake CVVT
2. Exhaust CVVT

CVVT System Mode

1. Low Speed / Low Load
2. Partial Load
3. Low Speed / High Load
4. High Speed / High Load

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