Hyundai Sonata: CVVT (Continuously Variable Valve Timing) System Description and Operation - Exhaust Emission Control System - Emission Control SystemHyundai Sonata: CVVT (Continuously Variable Valve Timing) System 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 rgulates engine oil to and 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.

[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
* 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

    Catalytic Converter Repair procedures
    Removal 1. Remove the exhaust manifold. (Refer to Engine Mechanical System - "Exhaust Manifold") Installation 1. Install in the reverse order of removal. ...

    See also:

    Repair procedures
    Service Adjustment Procedure Transmission Oil Inspection And Replacement 1. Park the vehicle on a level ground and stop the engine. 2. ...

    AVN Remote Controller Repair procedures
    Inspection 1. Check for resistance between terminals in each switch position (LH). [LH : Audio + Hands free] SwitchConnectorTerminalResistance(В±5%)SEEK Up2-5430 ?SEEK Down1.11 k?MODE2.11 k?MUTE ...

    Ignition switch position
    LOCK Without the immobilizer The steering wheel locks to protect against theft. The ignition key can be removed only in the LOCK position. When turning the ignition switch to the LOCK position ...