Kia Optima: 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 camsh ...
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 co ...
See also:
Cylinder Head Repair procedures
Removal
•
Use fender covers to avoid damaging painted surfaces.
•
To avoid damaging the cylinder head, wait until the engine
coolant temperature ...
Sunvisors
To use a sunvisor, pull it downward.
To use a sunvisor for a side window (if equipped), pull it downward, unsnap it
from the bracket and swing it to the side.
There is a pocket on the driver’s v ...
Seat Belt Pretensioner (BPT) Description and Operation
Description
The Seat Belt Pretensioners (BPT) are installed inside Center
Pillar (LH & RH). When a vehicle crashes with a certain degree of
frontal impact, the pretensioner seat belt helps ...
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