Ivvt-T

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NEW FEATURES – 1GR-FE ENGINE

8. VVT-i (Variable Valve Timing-intelligent) System
General
D The VVT-i system is designed to control the intake camshaft within a range of 50_ (of CrankshaftAngle)
to provide valve timing that is optimally suited to the engine condition. This improves torque in all the
speed ranges as well as increasing fuel economy, and reducing exhaust emissions.VVT Sensor (Right Bank)
Throttle
Position
Sensor

Camshaft Timing Oil Control Valve
Engine Coolant Temp. Sensor

ECM

Camshaft Timing
Oil Control Valve

Mass Air
Flow Meter

VVT Sensor(Left Bank)
Crankshaft Position Sensor

238EG60

D Using the engine speed, intake air volume, throttle position and engine coolant temperature, the ECM
can calculate optimal valve timing foreach driving condition and controls the camshaft timing oil control
valve. In addition, the ECM uses signals from the camshaft position sensor and the crankshaft position
sensor to detect the actualvalve timing, thus providing feedback control to achieve the target valve
timing.

ECM
Crankshaft Position Sensor

Target Valve Timing
Duty-cycle
Control

Mass Air Flow Meter

CamshaftTiming Oil
Control
Valve

Feedback

Throttle Position Sensor
Engine Coolant Temp. Sensor

Correction

VVT Sensors

Actual Valve Timing

Vehicle Speed Signal
221EG16

NF

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NEWFEATURES – 1GR-FE ENGINE
Effectiveness of the VVT-i System
Operation State

Objective

Effect

TDC

Latest Timing

During Idling

EX

IN

BDC

Eliminating overlap to reduce
blow backto the intake side

D Stabilized idling rpm
D Better fuel economy

Decreasing overlap to eliminate
blow back to the intake side.

Ensured engine stability

Increasing overlap to increaseinternal EGR to reduce
pumping loss

D Better fuel economy
D Improved emission
control

Advancing the intake valve
close timing for volumetric
efficiency improvement

Improved torque in...