Hyundai Elantra: 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 and 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 increase of expansion work.
This system consist 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,
-
and the Cam Phaser which varies the cam phase by using the hydraulic force of the engine oil.
The engine oil getting out of 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 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.
   
A separate solenoid valve is installed on the chain cover in the intake side for closing and releasing a separate lock pin.

[CVVT System Mode]

(1) Low Speed / Low Load
(2) Part 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
* Reduction of HC
Retard
* Delays the closing time of intake valve to reduce pumping loss
* Increases expansion work
(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

CVVT & Camshaft Components and Components Location
Components 1. Camshaft bearing cap2. Camshaft front bearing cap3. Exhaust camshaft4. Intake camshaft5. Exhaust CVVT assembly6. Intake CVVT assembly ...

CVVT & Camshaft Repair procedures
Removal     • Use fender covers to avoid damaging painted surfaces. • To avoid damage, unplug the wiring connectors carefully while holding the connector portion. ...

Other information:

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Hyundai Elantra AD (2016-2020) Owners Manual: Turn Signal, High Beam, Light ON Indicator Lights
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