VVT-i 1

(Variable Valve Timing intelligent)

VVT-i

VVT-i 2

1. HERE’S WHAT I LOOK FOR IN AN ENGINE !

3. PROCESS OF DRAWING AIR-FUEL MIXTURE INTO CYLINDER

4. ENGINE RPM AND VALVE TIMNG

5. VVT-i CONTROL

6. VVT-i ADVANTAGE

INTRODUCTION

2. BASIC OPERATION OF THE FOUR-STROKE ENGINE

7. VALVE TIMING

VVT-i 3

“I wish it had bettergas mileage”

“I wish it had morepower”

“I don’t needto refuel yet”

“I wish engine performed smoothly even in heavy traffic”

“Even exhaustfumes are clean”

“I want engine that isenvironmentally

friendly”

“I wish they wouldn’t demand

so much”

1. HERE’S WHAT I LOOK FOR IN AN ENGINE

Wouldn't it be wonderful if your engine addressed all of your needs? Such as one that has plenty of power yet uses very little fuel and is friendly to the environment?

VVT-i 4

VVT-i

The VVT-i is an all-comprehensive engine control system that has achieved high levels of the seemingly opposing performance of "higher power output", "lower fuel consumption", and "cleaner exhaust gases".

VVT-i 5

2. BASIC OPERATION OF THE FOUR-STROKE ENGINE

Before we learn how the VVT-i system operates, let us first review the basic operation of the four stroke engine.

Compression stroke

Combustion stroke

Exhaust stroke

Intake stroke

VVT-i 6

It takes me awhileto get moving.

Top-dead-center

Intake lag (1)

3. PROCESS OF DRAWING AIR-FUEL MIXTURE INTO CYLINDER

As the piston begins its descent from its top-dead-center, a vacuum is created in the cylinder, causing the pressure in the cylinder to become lower than that of the intake port. The air-fuel mixture that was standing by in the intake port does not move immediately when the vacuum that is created in the cylinder is ready to draw the air-fuel mixture into the cylinder.

The drawing of the air-fuel mixture into the cylinder is slightly delayed in relation to the descent of the piston, a phenomenon know as "intake lag".

VVT-i 7

There’s 　plenty of room for us

But they’re pushing harder!

Bottom-dead-center

Intake lag (2) Due to the "intake lag", even after the piston turns around at its bottom-dead-center and begins its descent, the pressure in the cylinder for sometime remains lower than that of the intake port.

Until this difference in pressure is eliminated by the further ascension of the piston, the air-fuel mixture continues to be drawn into the cylinder.

Engines are normally designed with these factors in mind.

Consequently, in order to draw in as much air-fuel mixture as possible during the intake stroke, it is important to take the "intake lag" into consideration when determining the timing of the opening and closing of the intake valve.

VVT-i 8

It’s not pulling me in very fast

I caught up with you

I’m coming down slowly

During low engine rpm (1)

4. ENGINE RPM AND VALVE TIMING

Because the piston descends at a slow speed and the air-fuel mixture also flows at a slow speed, only a slight resistance is created against the drawing of the air-fuel mixture into the cylinder. Therefore, the air-fuel mixture in the intake port is drawn into the cylinder without lagging too far behind the movement of the piston.

The intake lag varies in accordance with the engine rpm because the piston's descent speed is proportionate to the engine rpm.

VVT-i 9

I’m fullNow.

Bottom-dead-center

During low engine rpm (2) Because the "intake lag" is short, the difference in pressure that is created in the cylinder and in the intake port at the piston's bottom-dead-center is only slight. Therefore, the pressure in the cylinder becomes higher than the pressure in the intake port as soon as the piston starts to ascend. Therefore, a larger amount of air-fuel mixture can be drawn in if the intake valve is opened near the piston's top-dead-center and closed near the bottom-dead-center.

VVT-i 10

It’s all the way down there already.

There’s noway to catch up.

During high engine rpm (1) Because the piston descends at a fast speed and the air-fuel mixture also flows at a fast speed, a considerable amount of resistance is created against the drawing of the air-fuel mixture into the cylinder. Therefore, the air-fuel mixture in the intake port is drawn into the cylinder lagging considerably behind, without being able to catch up with the movement of the piston.

VVT-i 11

There’splenty moreroom for me.

Bottom-dead-center

During high engine rpm (2) When the "intake lag" becomes long, even after the piston turns around at its bottom-dead-center and begins its ascent, the pressure in the cylinder for some time remains lower than that of the intake port. Thus, the air-fuel mixture continues to be drawn into the cylinder for quite some time after the piston has begun its ascent.

Therefore, during high rpm operation, a larger amount of air-fuel mixture can be drawn into the cylinder when the intake valve is opened earlier than the top-dead-canter, and closed later than the bottom-dead-center.

VVT-i 12

5. VVT-i CONTROL

The VVT-i improves the engine's overall performance based on the engine rpm and the extent to which the throttle valve is opened. When greater power is needed, it changes the timing to that which enhances torque, and when less power is needed, it changes the timing to that which enhances fuel economy and cleaner exhaust gases.

Let us confirm how the VVT-i achieves "high power output", "low fuel consumption", and "clean exhaust gases" by using the various driving condition as the VVT-i control example.

VVT-i 13

It’s hard to get through.

Vacuum

Exhaustgas

I’m gettingpulled in!

Idling (1)Because the intake lag that occurs during idle minimal, it is not necessary to open the intake valve early. However, on a conventional engine in which the valve timing is fixed, the valves open early because they are designed with the intake lag in mind, which takes place during high-rpm operation.

When the air-fuel mixture is contaminated in this manner, it does not produce reliable combustion and results in an unstable engine rpm. For these reasons, in conventional engines that avoid valve overlap, it becomes necessary to raise the rpm at idle to a certain extent.

VVT-i 14

The exhaustgases are not coming in.

Idling (2)

During idle, the VVT-i delays the timing at which the intake valve opens to eliminate the valve overlap, thus preventing the exhaust gases from flowing back into the intake port.

VVT-i 15

Light & medium load driving (1)

During normal driving, the VVT-i advances the valve timing to achieve a large valve overlap. During normal driving, when the throttle valve is not opened too widely, a vacuum is created in the intake port. Similar to when the engine is idling, when the valve overlap is large, this vacuum causes the exhaust gases to flow back into the intake side.

Why does the VVT-i increase the valve overlap, which could the state of the air-fuel mixture to worsen?

VVT-i 16

Now I can move moresmoothly!

Light & medium load driving (2)

As the exhaust gases are drawn in, the vacuum in the intake port becomes lower and reduces the resistance (the force that tries to pull the piston upward) during the descent of the piston during the intake stroke.

The engine's power loss is reduced and fuel economy is increased.

VVT-i 17

There’s less NOx because it doesn’t get too hot.

I’m clean!

Light & medium load driving (3)

The unburned fuel that is contained in the exhaust gases is re-introduced into combustion, resulting in a decreased amount of HC emissions and cleaner exhaust gases.

The mixing of the inactive gases into the air-fuel mixture lowers the combustion temperature, resulting in a decreased amount of NOx emissions and cleaner exhaust gases.

VVT-i 18

ClickI’m full now

Heavy-load with low & medium rpm (1)

Bottom-dead-center

When the driver is about to depress the accelerator pedal all the way to start accelerating, the engine rpm is low and the piston is operating at a low speed, so the intake lag of the air-fuel mixture is short.

Under such conditions, when the piston turns around at its bottom-dead-center, the pressure in the cylinder and the pressure in the intake port soon reach their equilibrium. Therefore, unless the intake valve is closed before the piston ascends, the air-fuel mixture gets pushed back. by advancing the timing of closing the intake valve, and enable the valve to close when the piston is near the bottom-dead-center, a sufficient amount of air-fuel mixture can be drawn in.

VVT-i 19

Overlap : Large

Heavy-load with low & medium rpm (2)

However, closing the intake valve early also means that the intake valve opens early, causing the valve overlap to increase. during idle, if the valve overlap is large, the exhaust gases flows back due to the vacuum that is present in the intake port. However, during sudden acceleration, in the intake port is low, and there is practically no back flow of the exhaust gases.

VVT-i 20

I’m going to delay it a little.

I can’t catch upwith the piston.

It’s getting graduallyearlier.

Heavy-load with high rpm

When the accelerator pedal continues to be depresses, the engine rpm increases, resulting in a longer intake lag.

Using sensors to monitor the engine rpm, the VVT-i gradually delays the timing to close the valve so that the maximum amount of air-fuel mixture can be drawn in according to the increase in the engine rpm.

VVT-i 21

(1)Stable combustion can be obtained even at a low rpm. Thus, with the lower idle rpm, the engine achieves better

fuel economy.

6. VVT-i ADVANTAGE

(2)The engine's power loss is reduced and fuel economy is increased.

The exhaust gases are cleaner.

(3)To maximize the potential of the engine.

VVT-i 22

TDCTDC

BDCBDC

ININ

EXEX

Eliminated overlap

Amount of exhaust gas blowing-back to intake

port is contained

Stabilized combustion

Improved fuel economy

During Idling

7. VALVE TIMING

VVT-i 23

Increased overlap

Internal EGR rate is

increased

Reduced pumping loss

Reduced NOxemission and

re-burning of HCImproved

fuel economy

During light & medium-load

VVT-i 24

Closing timing of intake valve is advanced

Amount of mixture blowing-back to intake

port is contained

Improved volumetric efficiency

Improved out put

During heavy-load, low & medium rpm

VVT-i 25

Closing timing of intake valve is retarded

according to engine speed.

Timing matched with inertia force of intake air

is set.

Improved volumetric efficiency

Improved output

During heavy-load, high rpm

VVT-i 26

Range Operation State

Valve timing

1Idling

2Light Load

3MediumLoad

4Medium rpm &Heavy Load

5High rpm& Heavy Load

TDC BDC

EX

IN

EX

IN

EX

IN

EX

IN

EX

IN

Load

Engine rpm

Wide Open Throttle

Range 4 Range 5

Range 3

Range 1

Range 2

Summary

VVT-i 27

1. RELATED COMPONENTS

2. OPERATION

3. VVT-i CONTROL

D16D VVT-i SYSTEM

VVT-i 28

Cam angle sensor

Crankangle sensor

OCV

VVT-icontroller

1. RELATED COMPONENTS(1) VVT-i controller(2) OCV (Oil Control Valve)(3) Cam angle sensor(4) Engine revolution sensor

K3-VE

VVT-i 29

(Fixed on intake camshaft)

(Fixed on housing)

Lock pin

Hydraulicpressure Spring

force

During engine running When engine is In stopped state

RetardAdvance

(1) VVT-i controller (K3-VE)

VVT-i 30

Camshaft drive gear( Fixed on camshaft drive gear )

Rotor ( Fixed on exhaust camshaft )Vane

Housing

Lock pin

Hydraulicpressure Spring

force

During engine running When engine is In stopped state

(1) VVT-i controller (EJ-VE)

VVT-i 31

Drain DrainPump Spool valve

Advancechamber

Retardchamber

Operating direction of spool valve

Duty ratio

SmallLarge

(2) OCV (Oil Control Valve)

VVT-i 32

EJ-VE

Timing pin

Cam angle sensor

Two turns of engine

Cam angle sensor output

K3-VE

(3) Cam angle sensor

VVT-i 33

(4) Engine revolution sensor

EJ-VE

K3-VE

VVT-i 34

2. OPERATION(1) Advance operation(2) Retard operation(3) Retention operation

VVT-i 35

VVT-icontroller

Oil pressure

Rotatingdirection

Advance SignalDuty ratio : Large

EngineECU

Drain

Operating direction of spool valve

(1) Advance operation (K3-VE)

VVT-i 36

Intake 　camshaft

Exhaust camshaft

Engine ECU

DrainOil

pressure

OCV

Advance SignalDuty ratio : Large

(1) Advance operation (EJ-VE)

VVT-i 37

Rotatingdirection

Oil pressure

Engine ECU

VVT-i controller

Operating directionof spool valve

Retard signalDuty ratio: Small

Drain

(2) Retard operation (K3-VE)

VVT-i 38

EngineECU

DrainOil pressure

Exhaust 　camshaft

Intakecamshaft

OCV

Retard signalDuty ratio: Small

(2) Retard operation (EJ-VE)

VVT-i 39

Engine ECU

Oil pressure

Retention signalDuty ratio ： Middle

(3) Retention operation (K3-VE)

VVT-i 40

Exhaust camshaft

Intake camshaft

OCV

Oil pressure

Engine ECU

Retention signalDuty ratio ：Middle

(3) Retention operation (EJ-VE)

VVT-i 41

3. VVT-i CONTROL(1) Outline(2) Control(3) Valve timing

VVT-i 42

Each sensor

OCV

Oil pump

ECU

Cam angle sensor

VVT-i controller

Intake cam shaft

Exhaust cam shaft

Engine revolution sensor

Retard

Advance

(1) Outline (K3-VE)

VVT-i 43

Cam angle sensor

Signal rotor

Intake cam shaft

Exhaust cam shaft

Signal rotor

Engine revolution sensor

Each sensor

OCVOil pump

VVT-i controller

(1) Outline (EJ-VE)

VVT-i 44

OCV

Engine ECU

Compensation

Actual valve timing

Throttle sensor

Engine revolution sensor

Water temp. sensor

Pressure sensor

Cam angle sensor

Feedbackcontrol

Target valve timing

(2) Control

VVT-i 45

BDC

TDC

2°EX close

12°30°

52°

10° 30°EX openIN close

IN open

Enginerotatingdirection

Valve 　TimingIntake 　：　

Open 　：　 BTDC 　 30° ～　 -12°

Close ：　 ABDC 　 10° ～ 52°

Exhaust 　：Open 　： BBDC 30°

Close 　：　 ATDC 2°

　　　

(3) Valve timing (K3-VE)

VVT-i 46

TDC

BDC

2°

6°

EX 　 close

EX open44°

40

62°

20°

IN 　open

IN close

Valve 　TimingIntake 　：　

Open 　：　 BTDC 　 40° ～　 - 2°

Close ：　 ABDC 　 20° ～ 62°

Exhaust 　：Open 　： BBDC 44°

Close 　：　 ATDC 6°

　　　

(3) Valve timing (EJ-VE)