Hyundai Santa Cruz: Exhaust Emission Control System / CVVT (Continuously Variable Valve Timing) System

- Description Electric Continuous Variable Valve Timing system (E-CVVT) Electric E-CVVT system is electric continuous variable valve timing system. It is located on the intake camshaft of the engine and uses motor rotation to control the rotation angle of camshaft relative to the rotation of crankshaft regardless of engine pressure.E- CVVT controls the DC motor current (duty signal) to more closely control the system compared to the previous pressure type, by increasing reaction speed of cam, improving startability, and reducing the emission of exhaust gas. Also, operation range of intake valve (valve opening angle) is expanded. So, the output and fuel efficiency are improved. - Operation Principle Electric Continuous Variable Valve Timing system (E-CVVT)

[Center OCV Type CVVT] 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.

   

• 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.

[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	Middle	* Valve Under-lap * Improvement of combustion stability
(2) Part Load	Retard	* Reduction of HC	Retard	* Reduction of pumping loss
(3) Low Speed /High Load	Completely Advance	* Reduction of pumping loss	Advance	* Prevention of intake back flow (Improvement of volumetric efficiency)
(4) High Speed/High Load	Completely Advance	* Reduction of pumping loss	Advance	* Prevention of intake back flow (Improvement of volumetric efficiency)