Tài liệu đào tạo động cơ V TDI trên ô tô Audi

Brief description and special features Synergy with the 3.0l V6 TDI Gen2 evo • Concept of the timing gear • Concept of the cylinder heads • Concept of the thermal management system • Con

Audi 4.0l V8 TDI engine

of EA898 series

Self Study Programme 652

For internal use only

Audi Service Training

As a source of superior driving power in the premium segment, the

V8 TDI engine offers high traction and ample power reserves in any

driving situation The new V8 TDI continues to follow this course

An electric powered compressor (EPC) contributes to good

drive-away performance

The derivatives of the new engine generation will be available with

the following features:

• Power spread from 310 kW to 320 kW

• Maximum torque of up to 900 Nm

• Certification to EU6 (ZG) emission standard

• Certification to EU5 and ULEV125 emission standards for

export markets

In addition to the main development targets, a key aim was to create a standard engine for all markets The different emission standards are differentiated by the vehicle exhaust system.The state-of-the-art technologies described in this self study programme have been implemented with the following aims:

• High engine power output and high torque for sporty ing in an S model

position-• Low fuel consumption for high efficiency in the ance segment

high-perform-• Low and sustainable emissions certified to EU6, EU5 and ULEV125 exhaust emission standards for world-wide use

• Spontaneous power delivery and optimal drive-away ance as well as a high level of comfort

perform-Learning objectives of this self study programme:

This self study programme describes the design and function of

the 4.0l V8 TDI engine of the EA908 engine series

After you have completed this self study programme you will be

able to answer the following questions:

• What is the structure of the components located in the inner V?

• How is the coolant pump driven and how can it be switched off?

• What is the voltage applied to the electric powered sor (EPC)?

compres-• How does the charge pressure control system work?

652_002

Introduction

Brief description and special features 4Specifications 6Engine concept with "inner hot side" _ 7

Engine mechanicals

Engine block _ 8Timing gear _10Cylinder head _12Audi valvelift system (AVS) 13Crankcase ventilation system _14

Oil supply

System overview _16Oil circuit 18Oil filter _18Oil pump 19Oil cooling 19

Exhaust gas recirculation

Overview 20EGR cooler 21

Cooling system

System overview _22Coolant module 24

Air supply and turbocharging

Combined design cover with integrated air filter _27Intake system 28Intake manifold header _29Electric powered compressor (EPC) 3048-volt electrical subsystem 33Charging group _34Charge-air pressure control _35

Fuel system

System overview _38High-pressure fuel system 40SCR system _41

Exhaust system

Overview 42Exhaust gas treatment module _42Ammonia slip catalyst (version for NAR) 43

The self study programme teaches a basic understanding of the design and mode of operation of new models,

new automotive components or new technologies

It is not a repair manual! Figures are given for explanatory purposes only and refer to the data valid at the

time of preparation of the SSP

This content is not updated.

For further information about maintenance and repair work, always refer to the current technical literature

Contents

Brief description and special features

Synergy with the 3.0l V6 TDI Gen2 evo

• Concept of the timing gear

• Concept of the cylinder heads

• Concept of the thermal management system

• Concept of the single-scroll

high-pressure exhaust gas recirculation system

• Innovative Thermal Management (ITM) 2

• Concept of a fully variable oil pump

• Friction reduction through the use of coated piston rings and reduced preload

• Friction reduction in the exhaust turbocharger rotor

• Use of engine oil 0W-20

Integrated oil filter

• Installed in the oil pan behind a cover

Active engine mountings

• Engine oscillation reduction

Audi valvelift system (AVS)

• Located at the intake and exhaust ends

Oil pump

• Combined oil/vacuum pump integrated in the oil pan

• Fully variable oil pump flow rate control

High-pressure fuel system

• Common rail injection system which delivers injection pressures of up to

2500 bar

Turbocharging

• Combination of active and passive turbochargers

• Inner hot side

• Switching of passive turbocharger via AVS on exhaust valve side

Electric powered compressor (EPC)

• Complementary to conventional exhaust turbochargers

• Powered by 48-volt electrical subsystem

Specifications

Torque-power curve of 4.0l V8 FDI engine EA898

(engine code CZAC)

Power output in kW

Torque in Nm

Engine speed [rpm] 652_007

Type 8-cylinder engine with 90° V angle

Fuel type Diesel to EN 590

Turbocharging VTG, active and passive turbochargers, e-actuator,

electric powered compressor (EPC)Engine management Bosch CRS 3.25

Maximum injection pressure in bar 2500 bar

Exhaust gas treatment NOC (NOx oxidation catalyst), SCR-coated diesel particulate filter

with integrated ammonia slip catalystEmission standard EU 6 (ZG)

CO2 emissions in g/km 189 – 1981)

The engraved engine code is located at the front left below the

cylinder head on the protruding edge of the engine block as seen in

the direction of travel

652_050

1) Depending on tyre size

Engine concept with "inner hot side"

Components in the inner V

652_044

The exhaust turbocharger and the exhaust gas recirculation system

are integrated in the inner V of the engine This compact layout

follows a strict multi-level architecture which, thanks to a

twin-scroll exhaust manifold system, allows short gas flow paths and

close-coupling of the exhaust gas aftertreatment system This

concept, with a "hot side" in the inner V, provides the basis for

Charging group Exhaust manifold

Exhaust gas recirculation

meeting fuel economy and emission targets The exhaust gas recirculation system is located on the lowest level of the inner V The EGR cooler with U-shaped throughflow, pneumatic EGR bypass valve and electric controlled EGR valve (exhaust gas recirculation valve GX5) has been optimised for minimal pressure loss

Passive turbocharger

Active turbocharger

Engine block

Pistons

Engine block GJV450 is a completely redesigned sand-core package

casting The positioning of the "hot side" in the inner V and the

separate head-block cooling system have to a large extent defined

the geometry of the engine block

The engine block has been designed with a systematic focus on

reducing wall thickness The complex part of the media supply

system to the oil/coolant heat exchangers is now separate from

the engine block and integrated in a lightweight aluminium

trans-fer plate

The split head block cooling configuration allows the coolant to

stand inside the engine block at cold start, which results in ever

faster warming up thanks to the low volume of the water jacket

The cylinder liners are plate-honed to attain an optimal cylinder

shape during engine operation This process is a basic requirement

for reliable functioning of the piston rings with a low preload and

is a key factor contributing to an optimal friction balance

For reasons of friction and strength, the aluminium pistons with

salt-core cooling port are designed as sleeve pistons with a DLC1)

-coated gudgeon pin After casting and premachining, the highly

stressed bowl rim is re-melted by means of laser energy to produce

the finest and strongest possible aluminium microstructure

The piston ring assembly was designed with a special emphasis on

reduced friction For example, lower piston ring preloads and

piston ring heights are used A combined system of PVD (physical

vapour deposition) and DLC1) layers provides the required wear

resistance of the first ring (control ring)

652_026

Pin bore bushing

Salt-core cooling duct

DLC 1) coated gudgeon pin

Re-melted bowl rim

1) DLC stands for Diamond like Carbon, an amorphous carbon

These strata exhibit very high hardness and are noted for having

very low dry coefficients of friction They can be identified by

their glossy, black-gray surface

Oil filter integrated

in the oil pan

Engine mechanicals

Transfer plate

652_025

The area to the oil/coolant heat exchangers has been separated

from the engine block and integrated into a lightweight aluminium

Transfer plate Oil/vacuum pump

Oil/coolant heat exchanger 2

Oil/coolant

heat exchanger 1

Timing gear

The layout for the new V8 TDI engine has been taken from the V6

TDI engine family The timing drive is, therefore, located on the

flywheel side To meet the high dynamic requirements of the

high-pressure pump during use of the 2500 bar injection system,

the chain drive for the high-pressure fuel pump is configured as a

torsionally rigid twin-shaft drive which eliminates resonance and

high chain forces across the entire rev band

In this engine the oil/vacuum tandem pump flange-mounted to the oil pan is driven directly from the front end of the crankshaft via a separate chain track

Drive shaft Coolant pump Timing gear

Camshaft drive

An intermediate gear mounted in the cylinder head provides a 2:1

ratio without the need for large camshaft sprockets Taking this

intermediate gear as the starting point, camshaft drive is provided

by a downstream double gear-wheel stage with each gear wheel

having backlash compensation for acoustic reasons To minimise

Needle bearing

Fixed gear

Fixed gear Idler

Recess in the fixed gear

Snap ring

friction in these additional bearing points, the intermediate gear mounting takes the form of a needle bearing To provide greater robustness in terms of oil quality and different oil viscosities, the Audi V configuration diesel engines exclusively use bush chains with chrome-plated pins

Backlash compensation

Backlash is compensated by the omega spring, which engages the

recess in the fixed gear and is preloaded by a spring guide in the

idler

When the camshaft gear is installed, it is relieved of stress by an

excentric bolt and engages the drive wheel with a degree of play

On completion of assembly, the excentric bolt is removed The

spring force rotates the two gears towards each other, and the

gear runs without backlash in the drive sprocket

Cylinder head

Cooling jacket

Vent duct

The high demands imposed on the cylinder head in terms of power

output and maximum cylinder pressure have been met by means of

an axle-parallel, symmetrical valve star and a two-part water

jacket

In order to eliminate micro-notching effects in high-stress zones,

the coolant jacket and the intake ducts have been optimised with

respect to their parting burr characteristics The objective was to

eliminate mould parting burrs from highly stressed areas and to allow these areas to be deburred reliably and automatically.The structural design of the cylinder head has been adapted to the engine concept with the "hot side" of the cylinder head located in the inner V In conjunction with other structural improvements, this makes both cylinder heads about 7.0 kg lighter than in the predecessor engine

Thanks to very fast flow rates, the lower water jacket ensures

intensive cooling of the combustion chamber plate and the highly

stressed valve webs Despite the gain in performance, web

tem-peratures have been reduced by as much as 30° C compared to the

predecessor engine with a single-part water jacket

In the upper water jacket requiring less cooling, slow flow rates

prevail in order to minimise the water-side pressure losses

If leaks occur in the area of the injector ring seal, a vent duct

allows the combustion pressure to escape This duct is integrated

in the cylinder head above the intake module

It prevents excess pressure from the combustion chamber

escap-ing via the crankcase ventilation system to the compressor side of

the turbocharger and causing the turbocharger to malfunction, or

damaging the ring seals or blowing them out of the crankcase

Upper coolant jacket

Lower coolant jacket

Glow plug

Intake cam adjuster

Exhaust duct to passive turbocharger

Exhaust duct to active turbocharger Fuel injector

652_065

Vent duct

Audi valvelift system (AVS)

The Audi valvelift system (AVS) is the core element of the

multi-stage turbocharging system The system had been used previously

in the petrol engines of the VW Group and has been improved to

meet the general operating requirements of the diesel engine

Due to the position of the injectors and the alignment of the valves

perpendicular to the combustion chamber plate, the basic shaft of

the AVS is mounted between the individual cylinders The basic

shaft has a spline which accommodates the individual, axially

displaceable cam elements The pins of the electromagnetic

actuator (cam adjuster) engage the gate of the cam element and

move it axially between the two cam shift positions Two different

cam contours are used on the intake side to vary event duration

652_032 652_075

Intake cam adjuster

Cam element

Exhaust end Intake end

Injector

with the aim of maximising drive-way performance while ing the required power output by means of long valve opening times, short valve timings for drive-away performance (opening angle of 160 crank angle degrees) and long valve timings for power (opening angle of 185 crank angle degrees)

generat-Thanks to variable intake valve timing, it has been possible to achieve an optimised intake valve lift curve which provides good response at low engine speeds and volumetric efficiency at high engine speeds This combination, together with leakage-free switch-over between the two exhaust turbochargers and variable exhaust valve timing, results in significantly better spontaneity

163 crank

185 crank

Crankcase ventilation system

Overview

The 4.0l V8 TDI engine is equipped with an efficient crankcase

ventilation system consisting of a crankcase breather module and

blow-by gas ducts leading into the cylinder head covers

The blow-by gases rising up out of the crankcase are collected at

the centre of the cylinder head covers and ducted through the

coarse oil separator This separator consists of multiple ascending

steps (settling chambers) which are responsible for initial

separa-tion of the oil and air in the blow-by gases The blow-by gases

subsequently reach the fine oil separators, of which there is one in

the left cylinder head cover and two in the crankcase breather module The blow-by gases are ducted through a labyrinth into the two fine oil separators with swirls, which are installed horizontally and vertically in an enclosed housing The remaining oil residues are thereby separated

The separated oil flows along several discharge ducts and into the oil pan above the oil level The oil-free blow-by gases flow through the pressure control valve to the intake end of the active turbo-charger and are admitted into the combustion chamber

652_009

Crankcase breather module

with 2 fine oil separators

Cylinder head cover with integrated fine oil separator

Vent tube with fixed connection Oil return

Fine oil separator Treated blow-by gases to the intake end

of the active turbocharger

Crankcase breather module

Fine oil separator

The crankcase breather module is located at the back of the

engine In it are integrated the two fine oil separators for the

right-In terms of their working principle, the fine oil separators are

centrifugal separators - or what are known as axial swirls

(PolyswirlTM) Each of these separators consists of 8 permanently

open swirls and 2 packs of 8 swirls which are activated and

deacti-vated depending on volumetric flow The two packs are actideacti-vated

hand cylinder bank, the pressure control valve and the oil return line from the fine oil separator of the left-hand cylinder bank

and deactivated by action springs with different spring tics The fine oil separator is opened by the blow-by gas flow in dependence on engine speed The spring force of the action springs is used for closing

characteris-652_014

652_016

Non-return check valve

Cleaned blow-by gas

Separated oil

Swirl

Blow-by gas inlet (raw gas) Action springs

Permanently open swirls

Permanently open swirls

Treated blow-by gases to

the intake end of the

active turbocharger

Fine oil separator for the left cylinder bank

Oil return from the left cylinder bank

Blow-by gases from the right cylinder bank Fine oil separator for

the right cylinder bank Oil return to oil pan

Non-return check valve

A non-return check valve, installed in the oil return line from the crankcase breather module, ensures that oil cannot be drawn into the intake area from the oil pan in situations such as icing-up of the crankcase breather

4 Oil/coolant heat exchanger 1

5 Oil/coolant heat exchanger 2

6 Oil filter module

7 Chain tensioner pinion A:

8 Chain tensioner pinion D:

9 Piston cooling nozzle

10 Non-return valve

11 Oil pressure control valve N428

12 Controlled oil pump

13 Vacuum pump

High pressure circuit

Low pressure circuit

System overview

Oil supply

7 8

Oil circuit

Oil filter

Due to the constraints on space, the oil filter has been installed

inside the oil pan The oil filter is accessible through a sevice cover

on the oil pan

652_047

652_010

Piston cooling jets

Oilways for supplying the

camshafts and the support

elements

Active turbocharger Passive turbocharger

Oil/coolant heat exchanger 2 Chain tensioner

Oil/vacuum pump

Oil/coolant heat exchanger 1

Oil pressure switch

F22

Main oil gallery

Oil pressure control valve

N428

Oil filter module

(in oil pan)

Service cover on the oil pan with seal

Service cover on the oil filter with seal

Oil filter cartridge

Oil pump

The oil circuit uses the fully variable oil pump of the V6 TDI engine,

which has been adapted to the oil demand of the V8 TDI engine

The vane pump, continuously controlled by way of an eccentric

ring, permits optimum adaptation of the pressure/volume flow

To allow the oil to heat up oil quickly after a cold start, volumetric

flow to the oil/coolant heat exchangers takes place on the coolant

side There is no coolant flow through the oil/coolant heat

exchangers during the cold start phase and at low engine loads It

depending on engine load and speed Additionally, the throughput

of the piston jets can be influenced, or shut off, by way of the pressure map in order to optimise friction

Rotor with vane cells

Adjustment ring with control spring

Oil pump cover

Design

is not until a certain, evelated oil temperature is reached that coolant flow through the oil/coolant heat exchangers is enabled by switching the oil cooler valve

Overview

EGR cooler

652_062

In a combustion process involving surplus air, unwanted nitrogen

oxides form at high combustion chamber temperatures in any

internal combustion engine The formation of nitrogen oxides can,

to a large extent, be avoided by recirculating the exhaust gases

The exhaust gas recirculation system directs a portion of the

exhaust gases back into the combustion chambers This reduces the amount of fresh, oxygen-rich air in the exhaust gases thereby inhibiting the chemical reactions within the combustion chamber The resultant reduction in combustion temperatures in turn means significantly lower NOx emissions

Exhaust gas recirculation valve GX5

Active turbocharger

Exhaust gas inlet

in the charge air pipe

Exhaust gas extraction point

on active turbocharger

Exhaust gas

recirculation pressure sensor

G691

Charge air pipe

Exhaust gas recirculation

Bypass mode

A key feature of the external exhaust cooling system is that the

exhaust gases on the exhaust side of the engine are extracted from

the exhaust manifold and returned to the combustion process

When the engine is cold, the hot exhaust gases are channelled

directly into the charge air system via the bypass duct This ensures

rapid heating of the oxidising catalytic converter and of the engine

Cooling mode

To reduce nitrogen oxide emissions still further, the exhaust gases are additionally cooled via the liquid-controlled exhaust gas recir-culation cooler The EGR bypass valve, activated by the EGR cooling bypass valve N386, opens the inlet to the EGR cooler The exhaust gases are now channelled through the cooled pipes and dissipate their heat to the coolant This allows the combustion chamber temperature to be reduced thereby ensuring lower NOx levels in the exhaust gases

Exhaust gas inlet

Coolant outlet EGR cooler

Cooler bypass valve open

To

EGR inlet on

charge air pipe

Pneumatic

EGR bypass valve

Exhaust gas inlet

Exhaust gas inlet

Pneumatic EGR bypass valve

652_066

Coolant flow

Due to the gas flow configuration in the EGR cooler, double the

distance of the EGR cooler is utilised The exhaust gases from the

exhaust manifolds flow in a U shape from the bottom to the top

section of the exhaust gas recirculation cooler The gases flow

through the coolant tubes and dissipate their heat to the coolant

To enlarge the cooling surface area, the gas-carrying pipes are

embossed The cooled coolant flows into the EGR cooler at the hot

exhaust gas inlet This results in so-called "continuous flow

cooling" at the bottom end of the EGR cooler and "counterflow

cooling" at the top end of the EGR cooler

EGR cooler

Exhaust gas recirculation valve GX5

Exhaust gas recirculation valve GX5

Exhaust gas recirculation valve GX5

Coolant inlet Exhaust gas outlet

System overview

652_004

Cooling system

Cooled coolantWarm coolant

F265 Thermostat for mapped engine cooling G8 Oil temperature sensor

G62 Coolant temperature sensor G83 Coolant temperature sensor at radiator outlet G812 Coolant temperature sensor 3

J293 Radiator fan control unit J671 Radiator fan control unit 2 N474 Reducing agent injector N509 Gearbox oil cooling valve V488 Heating assistance pump V645 Electric compressor coolant pump

Key to figure on page 22:

1 Front heater heat exchanger

2 Rear heater heat exchanger

3 ATF cooler

4 Exhaust turbocharger 1

5 Coolant expansion tank

6 Cylinder head, bank 1

7 Cylinder head, bank 1

8 Cylinder head, bank 2

9 Cylinder head, bank 2

10 EGR cooler

11 Exhaust turbocharger 2

12 Oil/coolant heat exchanger 1

13 Oil/coolant heat exchanger 2

14 Coolant pump

15 Non-return valve

16 Rotary slide valve with electrically heated

wax expansion element

17 Oil cooling circuit control valve

18 Electric powered compressor (EPC)

19 Head block cooling circuit control valve

Coolant module

The innovative thermal management concept permits autonomous

supply to the interior and gearbox oil heating, the EGR cooler and

the exhaust turbocharger via the cylinder head circuit, regardless

of the coolant standing in the engine block

Coolant flows through the engine block and cylinder heads in two

parallel cooling circuits The coolant flow for both circuits runs

from the hot inner V intake across the engine block or cylinder

head to the cold outer side

The water pump located in the inner V now has a covered impeller

with three-dimensionally curved blades, and continuously supplies

the two sub-circuits The coolant pump is driven by a drive shaft

integrated in the timing gear via a sprocket

The coolant module, in which key functional components of the

coolant circuit are integrated, is installed at the front end of the

engine The volute casing of the coolant pump forms the coolant

module The map-controlled thermostat with rotary slide valve and

electrically heated wax expansion element for switching the large

cooling circuit is flange-mounted to the coolant module on the

supply side Also integrated in the coolant module are the head

block control valve, activated by the pressure reducing valve N155,

and the oil cooler bypass valve, activated by the EGR cooling

bypass valve 2 N387 in a pulse width modulated fashion using

Coolant pump Oil cooling circuit

control valve

Head block cooling circuit control valve

Intake to radiator Return from engine

Thermostat for mapped engine cooling F265

Return from radiator

652_060

Design

Coolant module with coolant pump