1. Introduction of the CVVT System 2. CVVT System Components, Function 3. CVVT System Diagnosis 4. CVVT DTC 5. Oil specification for Beta CVVT engine 6. Waveform 7. Models with CVVT system
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CVVT(Continuously Variable Valve Timing) System The CVVT, which is installed on the exhaust camshaft controls intake valve open and close timing in order to improve engine performance. The intake valve timing is optimized by CVVT system depending on engine rpm.
Advantages of CVVT ■ Reduced Fuel Consumption : - Reduce Reduce Pumping Pumping loss because because of increasing increasing valve valve overlap overlap
■ Reduced emission : - Reduce Reduce NOx NOx by EGR effec effectt because because of valv valve e overlap overlap optim optimiza ization tion
■ Improved performance and increased torque at low speed : - Improved Improved volumetric volumetric and thermodyn thermodynamic amic efficiency efficiency by variable variable valve timing timing
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Exhaus Ex haustt Camsh C amshaft aft
Rotation Direction
CVVT
Timing C hain hain Intake Camshaft Timing Belt
Crankshaft
① Rota Ro tati tion on forc f orc e of c rankshaft rankshaft is transmi transmitt tted ed to exhaust c amshaft amshaft by timing timing belt. belt. ② Rota Ro tati tion on force fo rce of exhaust c amshaft is transmi transmitt tted ed to to intak intake e c amshaft by timing timing c hain.
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CVVT, OCV(Oil Control Valve)
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OCV FILTER
-
Oil Temperature Sensor
MAP Sensor
Air Flow Sensor (HOT Film Type)
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CVVT Parts Location
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Valve timing variation EXHAUST
INTAKE
40CA
OVERLAP
- 240
- 120
0
120
240
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Intake Valve Timing
Beta Engine
Beta Engine with CVVT
Exhaust Valve Timing
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CVVT Oil Passage
R etard
D R A IN
A d v an c e
D R A IN Secti ction A- A
From Cylinder Block
Secti ction BB- B
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Rotating Direction of Engine
Retard
Advance
Driving condition
Intake V/Timing
Efficiency
At low load
Retard
Stable combustion
At high load, high speed
Retard
Improved performance
At high load, low speed
Advance
Improved Torque
At middle condition
Advance
Reduced fuel consumption
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Hold
Retard
Advance
12
Retard
Return
13
Advance
Return
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HOUSING VANE ROTOR VANE
Retard Chamber
Advance Chamber
※ The Oil O il is suppli supplied ed to to the the ret retar ard d chamber c hamber and advanc advanc e chamber by O C V control. control.
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1. Rotor vane vane is installe installed d on exhaust-cam exhaust-camshaft shaft by bolt bolt 2. Camshaft-intake and housing of CVVT is connected by chain ( Sprocket is attached on housing. So, phase difference occurs between Housing and Rotor Vane of CVVT). 3. Rotor vane is fixed on housing by stopper pin at the position of the maximum retard retard 4. If the oil is supplied to advance chamber, Housing will be advanced and stopper pin is unlocked. 5. Timing of intake-camshaft is advanced. 6. Engine off condition. The oil is drained from the advance chamber, the housing returned to retard position and fixed by pin due to lock of position
