Kia Niro: Cylinder Head Assembly / 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



Driving
Condition
Exhaust Valve
Intake Valve
Valve
Timing
Effect
Valve
Timing
Effect
(1) Low Speed
/Low Load
Completely
Advance
* Valve Under-lap
* Improvement of combustion stability
Completely
Retard
* Valve Under-lap
* Improvement of combustion stability
(2) Part Load
Retard
* Increase of expansion work
* Reduction of pumping loss
* Reduction of HC
Retard
* Reduction of pumping loss
(3) Low Speed
/High Load
Retard
* Increase of expansion work
Advance
* Prevention of intake back flow (Improvement of volumetric efficiency)
(4) High Speed
/High Load
Advance
* Reduction of pumping loss
Retard
* Improvement of volumetric efficiency

Cylinder Head Cover Repair procedures
Removal Engine removal is not required for this procedure.    • Use fender covers to avoid da ...

CVVT & Camshaft Repair procedures
Removal    • Use fender covers to avoid damaging painted surfaces. ...

Other information:

Kia Niro (DE HEV) Owners Manual: Warning message and warning light
When the sensor cover or the sensor lens is smudged with the foreign substances, such as snow or rain, the AEB operation may temporarily stop. In this case, the warning message appears to warn the driver. This is not a malfunction with the AEB. To operate the AEB again, remove the foreign s ...

Kia Niro 2017 (DE HEV) Service Manual: Tire Repair procedures
Tire Wear    • Using tires and wheel other than the recommended sizes could cause unusual handling characteristics and poor vehicle control, resulting in a serious accident. ...

© 2016-2019 www.kniro.net