Kia Optima Hybrid: 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,
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 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

CVVT & Camshaft Components and Components Location

Components 1. Camshaft bearing cap2. Camshaft front bearing cap3. Exhaust camshaft4. Intake camshaft5. Exhaust CVVT assembly6. Intake CVVT assembly7. Exhaust camshaft upper bearing8. Intake camshaft lower ...

CVVT & Camshaft Repair procedures

Removal 1. Remove the cylinder head cover. 2. Set No.1 cylinder to TDC/compression. a. Turn the crankshaft pulley and align its groove with the timing mark "T" of the lower timing chain cover. b. Check ...

Other information:

Kia Optima Hybrid (TF HEV) 2016-2020 Service Manual: Compressor Oil Repair procedures


Oil Specification 1. The HFC-134a system requires synthetic (POE) compressor oil whereas the R-12 system requires mineral compressor oil. The two oils must never be mixed. 2. Compressor (POE) oil varies according to compressor model. Be sure to use oil specified for the model of compressor. • Since ...

Kia Optima Hybrid (TF HEV) 2016-2020 Service Manual: General Safety Information and Caution


Safety Precaution     Since hybrid vehicles contain a high voltage battery, if the high voltage system or vehicles are handled incorrectly, this might lead to a serious accidents like electric shock and electric leakage.     • Be sure to shut off the high voltage by removing the ...

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