Hyundai Palisade (LX2): Exhaust Emission Control System / CVVT (Continuous Variable Valve Timing) System

Hyundai Palisade (LX2) 2020-2026 Service Manual / Emission Control System / Exhaust Emission Control System / CVVT (Continuous 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 consists of the CVVT Oil Control Valve (OCV) which supplies the engine oil to the cam phaser or takes 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 changes the cam phase by using the hydraulic force of the engine oil.
The engine oil which is supplied from the CVVT oil control valve changes 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.

Hyundai Palisade. Description and operation

[Intermediate Lock CVVT]
It increases the retarded amount compared to the default state to expand the operating range of the variable valve timing system.
The cam phase is fixed mechanically so that it is locked at the middle position.

Hyundai Palisade. Description and operation

 â–·Effect
Improves fuel efficiency by approx. 1.7%.

Expands the intake CVVT operating range.
(Increases the retarded amount by up to 30° compared to the default state.)
∇
LIVC (Late Intake Valve Close)
∇
1. Improves fuel efficiency by reducing pumping loss.
2. Improves knocking characteristics by reducing compression ratio.

Hyundai Palisade. Description and operation
Default position : Middle
CVVT operates in advanced / retarded directions.

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.
Hyundai Palisade. Description and operation   
•
The variable force solenoid (VFS) changes its force depending on the PWM duty to control the stroke of the OCV.
•
It also controls the lock, unlock, advanced, retarded, and holding functions.
1.
Intake CVVT

Hyundai Palisade. Description and operation
2.
Exhaust CVVT

Hyundai Palisade. Description and operation
[CVVT System Mode]

Hyundai Palisade. Description and operation

(1) Low Speed / Low Load
(2) Part Load

Hyundai Palisade. Description and operation

Hyundai Palisade. Description and operation
(3) Low Speed / High Load
(4) High Speed / High Load

Hyundai Palisade. Description and operation

Hyundai Palisade. Description and operation

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

Schematic diagrams

Circuit Diagram
Variable Force Solenoind (VFS)

Hyundai Palisade. Schematic diagrams

Harness Connector

Hyundai Palisade. Schematic diagrams

CVVT Oil Control Valve (OCV)

Hyundai Palisade. Schematic diagrams

Harness Connector

Hyundai Palisade. Schematic diagrams

Repair procedures

Inspection
Variable Force Solenoind (VFS)
Refer to Engine Control / Fuel System - "E-CVVT Motor"
CVVT Oil Control Valve (OCV)
Refer to Engine Control / Fuel System - "CVVT Oil Control Valve (OCV)"
Removal
Variable Force Solenoind (VFS)
Refer to Engine Control / Fuel System - "E-CVVT Motor"
CVVT Oil Control Valve (OCV)
Refer to Engine Control / Fuel System - "CVVT Oil Control Valve (OCV)"
Installation
Variable Force Solenoind (VFS)
Refer to Engine Control / Fuel System - "E-CVVT Motor"
CVVT Oil Control Valve (OCV)
Refer to Engine Control / Fuel System - "CVVT Oil Control Valve (OCV)"

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