heui(curso completo)

Service TrainingMeeting Guide 672 SESV1672-01

April 1997

TECHNICAL PRESENTATION

3408E/3412E ENGINE CONTROLS

HYDRAULIC ELECTRONIC UNIT INJECTION (HEUI)

PUMPCONTROL

VALVE

OILFILTER

OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR

HYDRAULICTEMPERATURE

SENSORCOLD START

OILRESERVOIR OIL PRESSURE

SENSOR

ECM

HYDRAULICSUPPLY

PUMPGROUP

COOL DOWNCIRCUIT

FUEL TANK

FUELTEMPERATURE

SENSOR

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTER

FUELTRANSFER

PUMP

PRIMARYFUEL FILTER

WATERSEPARATOR

LUBE OILPUMP

TO LUBESYSTEM

3408E/3412E HEUI FUEL SYSTEM

FLUID MANIFOLDHYDRAULIC PASSAGE


3408E/3412E ENGINE CONTROLSHYDRAULIC ELECTRONIC UNIT INJECTION (HEUI)MEETING GUIDE 672 SLIDES AND SCRIPT

AUDIENCE

Level II - Service personnel who understand the principles of engine systems operation, diagnosticequipment, and procedures for testing and adjusting.

CONTENT

This presentation is designed to prepare a service technician to identify the components, explain theirfunction, and service the 3408E/3412E Hydraulic Electronic Unit Injection (HEUI) engines in allcurrent machine and industrial applications.

OBJECTIVES

After learning the information in this presentation, the serviceman will be able to:

1. locate and identify the major components in the 3400 HEUI system;

2. explain the functions of the major components in the 3400 HEUI system;

3. trace the flow of oil through the engine hydraulic system;

4. trace the flow of fuel through the fuel system; and

5. trace the flow of current through the engine electrical system.

PREREQUISITES

Interactive Video Course "Fundamentals of Mobile Hydraulics" TEVR9001Interactive Video Course "Fundamentals of Electrical Systems" TEVR9002Programmed Instruction Course "Basic Electricity" SEBV0534STMG 546 "Graphic Fluid Power Symbols" SESV1546

Prior training in systems operation and testing and adjusting procedures for the 3408C/3412C enginesshould be completed before participating in this training session. Additionally, the participants shouldhave PC skills and have completed introductory training in Windows software.

Estimated Time: 8 HoursVisuals: 138 (2 X 2) SlidesServiceman Handouts: 8 Drawings/Data SheetForm: SESV1672-01Date: 4/97

1997 Caterpillar Inc.

SUPPLEMENTARY TRAINING MATERIAL

Video Tape "3408E/3412E HEUI Service Introduction" SEVN3550Brochure "Caterpillar 3408E and 3412E Engines" LEDH6055ESTMG "Introduction to Electronic Technician" LEPV5155Brochure "Caterpillar Electronic Technician" NEHP5614Wall Chart "HEUI Fuel System" (small) LEWH6116Wall Chart "HEUI Fuel System" (large) LEWH6266Wall Chart "HEUI Engine" LEWH6740

Training Book "Easy Windows, 3.1 Edition" by Shelly O'HaraAvailable from:Prentice Hall Computer Publishing0-88022-985-3Attn: Order Dept.201 W. 103rd St.Indianapolis, IN 46290

Reference Book "Field Guide to Microsoft Windows 95" by Stephen L. NelsonAvailable from:Microsoft Press International at Fax No. (206) 936-7329Also available from bookstores

Training Book "Windows 95 for Dummies"Published by IDG BooksIDG Books World Wide Website: http://www.idgbooks.comAvailable from bookstores

RECOMMENDED HEUI TOOLING

Caterpillar Electronic Technician Single Use License JERD2124Caterpillar Electronic Technician Annual Data Subscription (All Engines and Machines)JERD2129

Communication Adaptor 7X1700PC to Communication Adaptor Cable 7X1425Communication Adaptor to Machine Cable 139-4166(combined ATA and CDL Data Link cable; replaces 7X1570 and 7X1412)Digital Multimeter (Fluke 87) 9U7330Cable Probes 7X1710

Hydraulic Unit Injector Puller 131-3921Hydraulic Unit Injector Sleeve Removal Wrench 111-5051

STMG 672 - 3-4/97

STMG 672 - 4-4/97

REFERENCES

Troubleshooting Manual "3408E Engine--631E - 637E Wheel Tractor-Scrapers"SENR1037Troubleshooting Manual "3412E Engine--24H Motor Grader" SENR1038Troubleshooting Manual "3408E Engine--834B/836 Wheel Tractors" SENR1052Troubleshooting Manual "3408E/3412E Engines--D9R/D10R Track-type Tractors"SENR1054Troubleshooting Manual "3408E/3412E Engines--988F/990 Wheel Loaders"SENR1060Troubleshooting Manual "3408E/3412E Engines--769D - 775D Off-highway Trucks"SENR1062Troubleshooting Manual "3408E/3412E Engines--Industrial Applications" SENR1065Troubleshooting Manual "3408E/3412E Engines--651E - 657E Wheel Tractor-Scrapers"SENR1076

Disassembly and Assembly Manual "3408E/3412E Captive Engines" SENR1013Disassembly and Assembly Manual "3408E/3412E Industrial and Marine Engines"SENR1063

Testing and Adjusting Manual "3408E/3412E Engines--Captive Engines" SENR1018Testing and Adjusting Manual "3408E/3412E Engines--Industrial Engines"SENR1033

Electrical Schematic "3408E/3412E Captive Engines" SENR1026Electrical Schematic "3408E/3412E Industrial Engines" SENR1064

Special Instruction "Using the ECAP" SEHS8742Special Instruction "Installing the 7X1180 ECAP Expansion Board" SEHS8833

Tool Operating Manual "Using the Communication Adapter" SEHS9264Tool Operating Manual "Using the Machine Functions Service Program Module"SEHS9343

Parts Manual "3408E Industrial Engine" SEBP2509

STMG 672 - 5-4/97

TABLA DE CONTENIDOS

INTRODUCCION..................................................................................................................7Vista Genreal ..........................................................................................................................8Compoentes Principales ...........................................................................................................9

SISTEMA DE CONTROL ELECTRONICO .......... ............................................................26Fuel Injection .................................................................................................................29Fuel Injection Control System .......................................................................................31

FUEL INJECTION SYSTEM .............................................................................................49System Components .......................................................................................................51System Operation ...........................................................................................................53Hydraulic Unit Injector Operation .................................................................................56Injector Operation Characteristics..................................................................................61Injector Components ......................................................................................................64Injector Removal and Installation ..................................................................................68Injection Sequence .........................................................................................................71

HYDRAULIC SYSTEM......................................................................................................82Hydraulic Supply Pump Group ......................................................................................83System Operation ...........................................................................................................93

SYSTEM POWER SUPPLIES ..........................................................................................105ECM Power Supply .....................................................................................................106Speed/Timing Sensor Power Supply ............................................................................108Injector Power Supplies ..............................................................................................109Analog Sensor Power Supply ......................................................................................110Digital Sensor Power Supply .......................................................................................111Pump Control Valve Power Supply .............................................................................112

ELECTRONIC SENSORS AND SYSTEMS ....................................................................114Speed/Timing Sensors ..................................................................................................115Analog Sensors and Circuits ........................................................................................117Digital Sensors and Circuits .........................................................................................131Engine Shutdown Systems ...........................................................................................135Demand Fan Controls ..................................................................................................137Ether Injection System .................................................................................................138CAT Data Link .............................................................................................................139Logged Events..............................................................................................................141

MACHINE APPLICATIONS ............................................................................................144D9R/D10R Track-type Tractors ...................................................................................145988F/990 Series II Wheel Loaders ..............................................................................149769C/771C/773B/775B Off-highway Trucks ..............................................................1523408E/3412E HEUI Industrial Engines .......................................................................155

SLIDE LIST .......................................................................................................................158

SERVICEMAN'S HANDOUTS ........................................................................................160

INSTRUCTOR NOTES

STMG 672 - 6-4/97

STMG 672 - 7-4/97

1

3408E/3412E ENGINE CONTROLS

HYDRAULIC ELECTRONIC UNIT INJECTION(HEUI)

1997 Caterpillar Inc.

INTRODUCTION

This presentation discusses the 3408E/3412E Hydraulic Electronic UnitInjection (HEUI) Engine Controls in all applications.

The topics are sequenced as follows:

- Introduction and Major Components

- Electronic Control System

- Fuel Injection System

- Hydraulic System

- System Power Supplies

- Electronic Sensors and Systems

- Machine Applications

INSTRUCTOR NOTE: This presentation refers to and describesElectronic Technician (ET) as the programming tool for the3408E/3412E engines. As new and more sophisticated electronicengine controls are now in use, the Electronic Control AnalyzerProgrammer (ECAP) is no longer adequate for all tasks (such as flashprogramming). The ET software, installed on a PC, is now theprinciple tool used in programming.

Major topics

STMG 672 - 8-4/97

HEUI applications

System features

2

Overview

The 3408E/3412E engines equipped with the HEUI fuel system areavailable in construction equipment and industrial applications.

Industrial engines are available in both 3408C/3412C (pump and line fuelsystem) and 3408E/3412E HEUI versions.

Caterpillar machines powered by the 3408E/3412Eengines which featureHEUI include:

- 769D/771D/773D Off-highway Trucks

- 988F/990 Series II Wheel Loaders

- D9R/D10R Track-type Tractors

- 631E/637E/651E/657E Wheel Tractor-Scrapers

- 24H Motor Grader

The HEUI engines have many features and benefits not possible withmechanical fuel systems. These features include a very clean exhaust,improved fuel consumption and cold starting, simplified maintenancewith fewer moving parts, and reduced operating costs.

The system has additional advantages which will be covered later in thispresentation.

ST M G 672 - 9 -4/97

3

E lec tronic ally s imilarto E UI s ys tem

Hydraulic pump rais espres s ure

Hydraulic pres s urec ontrolled by E C M

Injec torselec tronic allys ignalled

V A L V UL A DE C ONT R OLDE L A B OMB A

F IL T R O DE

A C E IT E

E NF R IA DORDE A C E IT E

HE UI

HE UI

S UMIDE R ODE A C E IT E

S E NS OR DEP R E S IONHIDR A UL IC A

S E NS OR DET E MP E R A T UR AHIDR A UL IC A

DE P OS IT OP A R A

A R R A NQUE S E NS OR DEP R E S ION DE A C E IT E

E C M

B OMB A DEA C E IT EDE A L T A

P R E S ION

C IR C UIT O DEE NF R IA MIE NT O

T A NQUE DE C OMB US T IB L E

S E NS OR DET E MP E R A T UR AC OMB US T IB L E

V A L V UL AR E G UL A DOR A

DE P R E S ION

F IL T R OS E C UNDA R IODE C OMB US T IB L E

B OMB A DET R A NS F E R E NC IA

C OMB US T IB L E

F IL T R O P R IMA R IODE C OMB US T IB L E

Y S E P A R A DORDE A G UA

B OMB A DEL UB R IC A C ION

A S IS T E MADE L UB R IC A C ION

3408E /3412E H E UI

MUL T IP L E DE A C E IT EA A L T A P R E S ION

MUL T IP L E DE A C E IT EA A L T A P R E S ION

M ajor C omponents

T his schematic shows the various components in the HE UI fuel system.A detailed explanation of the system and the various components followslater in this presentation.

T he electronic components in the HE UI fuel system are very similar tothose used in other E UI systems. However, in the HE UI system, theinjectors are not actuated by a camshaft.

A high pressure hydraulic pump, which draws oil from the pressure sideof the lubrication pump, raises the pressure to a maximum of 22800 kPa(3300 psi). T he pressure is controlled by the E lectronic Control Module(E CM). T he hydraulic flow is directed to hydraulic actuators in eachinjector.

T he injectors are electronically signalled (as in the E UI system) to permitoil under high pressure to move a piston which then moves the fuelplunger.

SI ST E M A DE C OM B UST I B L E

E N F R IO

STMG 672 - 10-4/97

Siete t ipos de componentes principales

1. Hydraulic supplypump group

2. ECM

3. Throttle control

4. Speed/timingsensor

5. Injector

6. Temperaturesensor

7. Pressure sensor

CAT Data Link andcoolant flow switch(not shown)

4

2

3

456

7

1

This slide shows seven of the major types of components in the HEUIfuel system.

Hydraulic Supply Pump Group (1) containing:

- High pressure hydraulic pump

- Pump control valve

- Transfer pump

ECM (2)

Throttle Control (3)

Speed/Timing Sensor (4)

Injector (5)

Temperature Sensor (6)

Pressure Sensor (7)

The CAT Data Link (not shown) provides a two-way communication pathbetween the HEUI system and the remaining electronic circuits orsystems on the machine. The CAT Data Link also allows the service toolto communicate with the engine electronic system.

NOTE: Only one example of each sensor (pressure, temperature andspeed/timing) is shown on the slide.

STMG 672 - 11-4/97

3400 HEUI engine topview

1. ECM--the "heart"of the system

Personality moduleaccess panel locatedbelow ECM


Wiring harness

5

1

2222

The principal component in the HEUI system, the Electronic ControlModule (1), is mounted on top of the right front valve cover.

The ECM is the "heart" of the engine. The ECM performs enginegoverning, timing and fuel limiting. It also reads sensors andcommunicates to the instrument display system through the CATDataLink.

The Personality Moduleis used to program the ECM with all the ratinginformation for a particular application. The Personality Module can bechanged by direct replacement or can be flash programmed(reprogrammed) using a PC. The Personality Module Access Panel islocated below the ECM.

The Hydraulic Supply Pump Group(2) is mounted in the vee of theengine in the same position as the original fuel pump and governor for the3408C/3412C engines. Flow from this pump supplies the actuatingpressure for the injectors. Mounted on the rear of the pump is the fueltransfer pump.

Among the visible components are the Wiring Harnessand 40 PinConnectorsto the ECM.

INSTRUCTOR NOTE: The slides which follow show machine andindustrial engines. The physical appearance and function of theHEUI machine and industrial engine components are very similar.

STMG 672 - 12-4/97

Engine upper left sideview

1. Fuel temperaturesensor

2. Atmosphericpressure sensor

3. Lubrication oilpressure sensor

4. Hydraulictemperature sensor

5. Machine interfaceconnector

6. Ground bolt

6

12 4

53

6

This view from the upper left side of the engine shows the FuelTemperature Sensor (1). The Atmospheric Pressure Sensor (2) ismounted on the Hydraulic Supply Pump Group mounting adapter.

Mounted on the Hydraulic Supply Pump Group is the Lubrication OilPressure Sensor (3). The sensor is used by the ECM to generate a lowoil pressure warning for the operator.

Also mounted on the Hydraulic Supply Pump Group is thelUBRICATIONTemperature Sensor (4). This sensor is used by the ECM for viscositycompensation to maintain consistent fuel delivery and injector timingregardless of viscosity changes caused by varying hydraulic temperatures.Both sensors are threaded into the supply pump case.

The 40 Pin Machine Interface Connector (5) is mounted behind theHydraulic Supply Pump Group. This component makes the connectionbetween the engine and machine wiring harnesses.

A vital part of the wiring assembly is the Ground Bolt (6) mounted onthe machine interface connector bracket.

NOTE: Oil flow from the Hydraulic Supply Pump Group will bereferred to as "hydraulic" to avoid confusion with the lubricationsystem.

STMG 672 - 13-4/97

1. Timing calibrationconnector

2. Hydraulic pressuresensor

3. Injector connector

7

2

13

The Timing Calibration Connector(1) is located adjacent to the ECM.

The Hydraulic (Injection Actuation) Pressure Sensor(2) is locatedbetween the valve cover bases in the right Fluid Supply Manifold.

The Injector Connector(3) is one of four connectors on a 3408E. (Each connector supplies current to two injector solenoids.)

STMG 672 - 14-4/97

Coolant temperaturesensor (arrow)

8

The engine Coolant Temperature Sensor(arrow) is located in the frontof the right cylinder head. This sensor is used with the ECM to controlvarious functions. The following systems or circuits use the TemperatureSensor output to the ECM:

The Vital Information Management System (VIMS) or CaterpillarMonitoring System Coolant Temperature Gauge over the CATDataLink.

The High Coolant Temperature Warning Alert Indicator LED andGauge on the VIMS or Caterpillar Monitoring System panel. (Theinformation is transmitted over the CATData Link.)

The Engine Demand Fan Control, if installed, uses the sensor signalreference to provide the appropriate fan speed.

The Cat Electronic Technician (ET) status screen coolant temperatureindication.

The Coolant Flow Switch(not visible in this view) is mounted below thecoolant temperature sensor at the inlet to the oil cooler.

Coolant flow switch(not visible)

STMG 672 - 15-4/97

Secondaryspeed/timing sensor(arrow)

9

This view shows one of the Speed/Timing Sensors(arrow). A sensor ismounted on each side of the timing gear housing. This slide shows thesecondary Speed/Timing Sensor. The primary Speed/Timing Sensor islocated closest to the ECM.

These sensors are used to calculate engine speed and crankshaft positionfor timing purposes.

The sensors are self-adjusting, but special precautions are necessaryduring installation to prevent damage. (The precautions are describedlater in the presentation.)

NOTE: The sensors maintain a zero clearance with the timing wheel.

STMG 672 - 16-4/97

Rueda de Sincronizacion

Marca de sincronizacion

10

Esta es la rueda de sincronizacion, fuera del motor

Notice the wide 50/50 size slot and equal size tooth (arrow) cut in thewheel. Las otras 23 ranuras son de tamao 80/20

La ranura y diente 50/50 es usada po elECM como punto de referencia paradeterminar la posocion del motor para la sincronizacion del combustible (se explica completamente mas adelante). El sensor de Speed/Timing puedeidentificar este diente porque crea una seal diferente que los otros dientes

Una marca de sincronizacion "H," al reverso de larueda de sincronizacion es usada parasincronizar la rueda en relacion a los otros engran. de sincroniz. y el TDC del cigueal.

Ranura y diente 50/50(fecha)

STMG 672 - 17-4/97

Turbo inlet pressuresensor (arrow)

11

The Turbo Inlet Pressure Sensor(arrow) is mounted between the airfilter and the turbocharger. Not all machines have this sensor installed.

This sensor (if installed) is used in conjunction with the atmosphericpressure sensor to measure air filter restriction for engine protectionpurposes. The difference between the two pressure measurements is usedas the filter differential pressure.

The engine ECM uses this calculation to determine whether derating isnecessary to protect the engine.

STMG 672 - 18-4/97

Turbo outlet pressuresensor (arrow)

12

At the front of the engine in the right cylinder head is the Turbo Outlet(Boost) Pressure Sensor (arrow). This sensor is used with the ECM tocontrol the air/fuel ratio electronically. This feature allows very precisesmoke control, which was not possible with mechanically governedengines.

The sensor also allows boost pressure to be read using the service tools.

STMG 672 - 19-4/97

Identify components:

1. Atmosphericpressure sensor

2. Fuel temperaturesensor

3. Primaryspeed/timingsensor

4. Secondaryspeed/timingsensor

13

1

2

43

The Atmospheric Pressure Sensor(1) is installed on the HydraulicSupply Pump Group adapter and is vented to the atmosphere. This sensorhas various functions which are fully described later in the presentation.A foam block below the sensor helps prevent the entry of dirt into thesensor.

Briefly, the sensor performs the following functions:

- Ambient pressure measurementfor automatic altitudecompensation and automatic air filter compensation.

- Absolute pressure measurementfor the fuel ratio control, ET,Caterpillar Monitoring System panel (gauge) pressurecalculations.

The Fuel Temperature Sensor(2) is used for automatic fuel temperaturecompensation.

The Primary(3) and Secondary (4) Speed/Timing Sensors(discussedearlier) are located on the rear of the timing gear housing.

STMG 672 - 20-4/97

1. Aceite de suministro

2. Valvula Compensadora

3. Valvula de control bomba

4. Bomba trasnferencia

14

4

3

2

1

A number of components are mounted on the Hydraulic Supply PumpGroup. The Oil Supply Line(1) from the oil gallery is a large diameterline for maximum delivery during cold operation. The hydraulic pumpdepends on the lubrication pump for the first stage of pressure increase.

The Compensation Valve(2) is mounted at the rear of the pump. Belowthe compensation valve is the Pump Control Valve(3). This valve mayalso be referred to as the "injection actuation pressure control valve."This valve controls the angle of the swashplate, which varies the output ofthe pump.

The Fuel Transfer Pump(4) is mounted at the rear of the HydraulicSupply Pump and is driven by the main drive shaft which extends throughthe supply pump.

Also visible in this slide are the transfer pump inlet and outlet fuel linesand the pressure and temperature sensors (discussed earlier).

STMG 672 - 21-4/97

Lubrication oil pump

Supplies oil tolubrication andhydraulic injectionactuation systems

15

Mounted internally in the oil pan is the Bomba de aceite de lubricacion. Thispump supplies oil at approximately 400 kPa (65 psi) to the oil gallery forengine lubrication.

Oil is also supplied to the hydraulic pump for injection actuationpurposes. For this reason, the HEUI engine lubrication oil pump is largerthan the pump in the previous engine to accommodate the increased needsof the lubrication and the hydraulic injection actuation systems.

STMG 672 - 22-4/97

Timing calibrationsensor (arrow)

16

The Timing Calibration Sensor(arrow) is installed when required in theflywheel housing.

This sensor (magnetic pickup) is installed in the hole normally reservedfor the timing pin. (The pin is used to position the crankshaft with theNo. 1 piston at top dead center.)

NOTE: On some applications (i.e. some track-type tractors) whereaccessibility is limited, this sensor is permanently installed.

STMG 672 - 23-4/97

1. Water separatorand primary filter

2. Two micronsecondary filter

Water separatorservice intervals

17

1

2

The Water Separator (1), which also functions as a Primary Fuel Filter,is an important part of the fuel system.

As with any high pressure fuel system with operating pressures atapproximately 150000 kPa (22000 psi), fuel quality is important. Waterin the fuel can cause corrosion of the plungers and barrels. Dirt can causeearly hour wear on the same components. The water separator contains a30 micron filter. The Priming Pump is mounted on the filter base.

For the same reason, the correct two micron Secondary Filter (2) mustbe used in the system. The clearance between the plunger and barrel isapproximately 5 microns. Typically, the 3 to 8 micron abrasive materialprematurely wears out the fuel system components.

The Water Separator is serviced daily by draining the water. The WaterSeparator filter is serviced with a new element every 500 hours.

INSTRUCTOR NOTE: The high fuel pressures mentioned in thistext are mandated by the need to meet environmental regulations forsmoke and emissions. Also, to maintain good fuel consumption, highpressures are required. The HEUI system meets and surpasses thoserequirements.

ST M G 672 - 24 -4/97

18

E ngine c omponentidentific ation

A DE M IIMODUL O DE

C ONT R OLE L E C T R ONIC O

(E C M) P E R NO DET IE R R A

DIS Y UNT OR15 A

R E L E P R INC IP A LDE P OT E NC IA

INT E R R UPDE L L A V E

S E NS OR DE P R E S ION DE S A L IDA

S E NS OR P R IMA R IO DEV E L OC IDA D/S INC R ONIZA C ION

S E NS OR DE P R E S ION DEA C T IV A C ION DE INY E C C ION

24 V

C ONE C T OR DEINT E R F A Z DEL A MA QUINA

MA ZO DE C A B L E SDE L MOT OR

V A L V UL A DE C ONT R OL DE P R E S ION

S E NS OR DE T E MP E R A T UR A

S E NS OR DE P R E S ION A T MOS F E R IC A

S E NS OR DE P R E S ION DE

S E NS OR DE T E MP E R A T UR A DE

S E NS OR DE T E MP E R A T UR A

INT E R R UP T OR DE F L UJ O

8 O 12INY E C T OR E S

A C C E S O A L AS ONDA DE S E R V IC IO

T A B L E R O DEINS T R UME NT OS

C ONT R OL DE L R E T A R DA DOR A UT OMA T IC O

C ONT R OL DE L A T R A NS MIS ION E P T C II

HE R R A MIE NT A E L E C T R ONIC A DE S E R V IC IO

E NL A C E DE DA T OS C A T

V E NT IL A DOR

S E NS OR DE V E L OC IDA D

V A L V UL A P R OP OR C IONA L DE C ONT R OL

T UR B O INL E T P R E S S UR E S E NS OR

INT E R R UP T OR E S DE R E S E R V A DE L A C E L E R A DOR , DE A C T IV A C ION DE

B A J A E N V A C IO E L E V A DA Y DE A P A G A DO DE S DE E L S UE L O

S E NS OR DE LA C E L E R A DOR P E DA L DE L

A C E L E R A DOR

INT E R R UP T OR G E NE R A L

S IS T E MA 3408E /3412E HE UIDIA G R A MA DE C OMP ONE NT E S

C A B L E S DEL A MA QUINA

T his schematic identifies the external HE UI engine components (shownon the engine harness side of this schematic). T he components shown onthe left side of the diagram are mounted on the engine and those on theright are machine mounted. Notice that the turbo inlet pressure sensor ismounted on the machine.

I NST R UC T OR NOT E : A t this time, it is r ecommended that eachcomponent be located on the machine and the function of eachr eviewed with the students. A list of the components follows on thenext page.

Some additional (used/defective) components available forexamination on a table will be helpful. A n E C M with the Per sonalityM odule and var ious sensor s can be examined at this time and usedfor tr oubleshooting exer cises later .

DE L V E NT IL A DOR

DE L V E NT IL A DOR

MA ZO DE

DE A C T IV A C ION DE L A INY E C C ION

S E NS OR DE R E S E R V A DEV E L OC IDA D/S INC R ONIZA C ION

DE L R E F R IG E R A NT E

DE L T UR B OC OMP R E S OR

A C E IT E DE L MOT OR

A C E IT E DE L MOT OR

DE L C OMB US T IB L E

DE R E F R IG E R A NT E

DE C E NT R OS UP E R IOR (T DC )

STMG 672 - 25-4/97

Electrical Components

Conector del ECM 40 Pins

Modulo de Personalidad

Timing Calibration Connector and Installation Location

Sensor de presion hhidraulica

Sensor de Temperatura Hidraulica

Primary Speed Timing Sensor

Secondary Speed Timing Sensor

Sensor de Temperatura de Refrigerante

Sensor de Presion Atmosferica

Sensor de presion de entrada del turbo

Sensor de presion de salida del turbo

Sensor de presion de aceite

Sensor de Temperatura de combustible

Switch de flujo de refrigerante

Conector de interfase a la maquina

Pernos de tierra de motor y de maquina

Conector al Data Link

Sensor de posicion de acelerador

Switches de apagado

Componentes Mecanicos

Grupo de bomba de suministro de aceite

Valvula de control de la bomba

Valvula de Compensacion

Reservorio para arranque en frio

Valvulas check

Manifold de fluido

Filtro Primario / Separador de agua

Filtro secundario

Bomba de transferencia

Valvula Reguladora de presion

Inyector

Tubo Jumper

Adaptador de aceite para inyector

STMG 672 - 26-4/97

19

SISTEMA DE CONTROL DE ELECTRONICO

ELECTRONIC CONTROL SYSTEM

This section of the presentation explains the Electronic Control Systemincluding the following components:

ECM

Personality Module

Hydraulic Electronic Unit Injector Solenoids

Timing Wheel

Also covered are the following subsystems and related procedures:

Timing control

Fuel quantity control

Speed control

Cold modes

Timing calibration

STMG 672 - 27-4/97

ECM:

- Governor

- Fuel systemcomputer

- Injection pressurecontroller

- Injection timingcontroller

Same ECM used in allapplications

20

The Electronic Control Module (ECM) functions as the governor and fuelsystem computer. The ECM receives all the signals from the sensors andenergizes the injector solenoids to control timing and engine speed.

The ECM is sealed except for access to the software which is contained inthe Personality Module (next slide). This ECM is the second generationof Advanced Diesel Engine Management Systems and may be frequentlyreferred to as "ADEM II."

This ECM is used in all applications of the 3408E and 3412E engines.The ECM can also be moved from one application to another; however, apassword is required to activate the ECM when new software is installed.

NOTE: The ECM has an excellent record of reliability. Therefore,any problems in the system are most likely to be in the connectorsand wiring harness. In other words, the ECM should typically be thelast item in troubleshooting.

STMG 672 - 28-4/97

Personality modulecontains software

Two methods toupgrade software

ECM is sealed exceptfor personality module

21

The Personality Module (shown removed from the ECM) contains thesoftware with all the fuel setting information (such as horsepower, torquerise and air/fuel ratio rates) which determines how the engine willperform. The Personality Module is installed on the lower face of theECM, behind the access panel.

At this time, two methods can be used to update the software:

1. Flash Programming: Electronic reprogramming of the PersonalityModule software. (This method is preferred when updating thesoftware.)

2. Remove and replace the Personality Module. (This method maybe used if Flash Programming is not possible.)

Upgrading the software is not a routine task, but might be performed forreasons of a product update, a performance improvement or a productproblem repair.

NOTE: The ECM is sealed and needs no routine adjustment ormaintenance. The Personality Module is mounted within the ECM.Installation of the Personality Module is the only reason to enter theECM. This operation would normally be performed during an ECMinstallation or a software update.

STMG 672 - 29-4/97

Unit injectors

Electrically signalled,hydraulically actuated

22

Fuel Injection

The 3400 HEUI unit injector is electrically similar to the 3500 electronicunit injector. The injector is controlled electrically by the ECM but isactuated hydraulically. The signal from the ECM controls the openingand closing of the solenoid valve. The solenoid valve controls the flow ofhigh pressure hydraulic oil to the injector. This system enables the ECMto control fuel volume, timing and injection actuation pressure (hydraulicsupply pump pressure).

The injector solenoids operate on 105 Volts direct current. Alwaysremain clear of the injector area when the engine is running orelectric shock may occur.

STMG 672 - 30-4/97

Injector testing

23

PRUEBA DE SOLENOIDES DE INYECTOR

CORTE DE CILINDROS

PRUEBA AUTOMATICA DE INYECTORES

METODOS DE PRUEBAS EN INYECTORES HEUI

Three tests can be used to determine which cylinder or injector ismalfunctioning:

INJECTOR SOLENOID TESTThis test is performed while the engine is stopped. The injector solenoidscan be tested automatically with the service tool using the InjectorSolenoid Test. This function individually tests each solenoid in sequenceand indicates if a short or an open circuit is present.

CYLINDER CUT-OUT (Manual test)This test is performed while the engine is running at any speed. The 105 Volt pulse can be individually cut out to aid in troubleshootingmisfire problems in the injector and the cylinder.

AUTOMATIC INJECTOR TESTThis test is performed with the service tool while the engine is running atany speed. The test makes a comparative evaluation of all injectors andnumerically shows the results. The test enables an on-engine evaluationof the injectors. (This test cannot be performed using the ECAP.)

A satisfactory test of all injector solenoids without any diagnosticmessages indicates that a mechanical problem in the cylinder probablyexists.

ST M G 672 - 31 -4/97

24

F uel timing c ontrol

Inputs to timingc ontrol

B enefits of a " s mart"timing c ontrol

L OG IC A DE C ONT R OL DE HE UI

V E L OC IDA D DE L

C A NT IDA D DE F UE LR P M

MODO F R IO

S E L E C TT IMING

C ONV E R TDE S IR E D

T IMINGT E MP E R A T U

C ONT R OL DE L A S INC R ONIZA C ION

DE G R E E S B T DC DE S IR E DT IMINGB T DC

T IMING

F UE L INJ E C T IONT IMING WA V E F OR M

F uel I njection C ontr ol System

T his diagram shows the timing control logic within the E CM.

E ngine speed, fuel quantity (which relates to load), and hydraulic oiltemperature input signals are received by the timing control. T hehydraulic temperature signal determines when the Cold Mode should beactivated. T hese combined input signals determine the start of fuelinjection.

T he timing control provides the optimum timing for all conditions. T hebenefits of a "smart" timing control are:

- R educed particulates and lower emissions

- Improved fuel consumption while still maintaining performance

- E xtended engine life

- Improved cold starting

MOT OR

C OMB US T IB L E

STMG 672 - 32-4/97

25

Fuel quantity control

Inputs to fuel quantitycontrol

Start of injectiondetermines timing

Injection duration andinjection actuationpressure determinefuel quantity

ELECTRONICGOVERNOR

TORQUEMAPS

FRCMAPS

TURBO OUTLET ANDATMOSPHERIC

PRESSURE SENSORS

ENGINECONTROL

LOGIC

THROTTLE

SHUTDOWNS

INJECTIONACTUATIONCONTROL

ENGINE RPM

TDC

87654321

FUELINJECTIONCONTROL

TO PUMPCONTROL VALVE

SIGNALSTO FUEL

INJECTORS

SPEED/TIMINGSIGNAL

ENGINE RPM

SPEED/TIMINGSENSORS

TIMINGWHEEL

ENGINE RPM

ECM

3408E/3412E ELECTRONIC GOVERNOR

HYDRAULIC OILTEMPERATURE ANDPRESSURE SENSORS

Four inputs control fuel quantity:

1. Engine speed

2. Injection actuation (hydraulic) pressure

3. Throttle position

4. Boost

These signals are received by the electronic governor portion of the ECM. The governor then sends the desired fuel signal to the fuel injection andinjection actuation controls. The fuel quantity control logic also receivessignals from the fuel ratio and torque controls.

Three variables determine fuel quantity and timing:

- The start of injection determines engine timing.

- The injection duration and injection actuation (hydraulic)pressure determine the quantity of fuel to be injected.

STMG 672 - 33-4/97

26

Speed/timing sensors

Three functions of thespeed/timing sensor

Sensor installation

ADEM IIELECTRONIC

CONTROLMODULE

(ECM) GROUNDBOLT

15 AMPBREAKER

MAINPOWER RELAY

KEYSWITCH

TURBO OUTLET PRESS. SENSOR

SECONDARYSPEED/TIMING SENSOR

PRIMARYSPEED/TIMING SENSOR

HYDRAULICPRESSURE SENSOR

24 V

MACHINEINTERFACE

CONNECTOR

ENGINEHARNESS

PUMP CONTROL VALVE

COOLANT TEMP. SENSOR

ATMOSPHERIC PRESS. SENSOR

OIL PRESSURE SENSOR

HYDRAULIC TEMP. SENSOR

FUEL TEMPERATURE SENSOR

COOLANT FLOW SWITCH

8 OR 12INJECTORS

TDC SERVICEPROBE ACCESS

INSTRUMENTPANEL

AUTO RETARDER CONTROL

EPTC II TRANSMISSION CONTROL

ELECTRONIC SERVICE TOOL

CAT DATA LINK

FANFAN SPEED SENSOR

PROPORTIONAL VALVE

TURBO INLET PRESSURE SENSOR

THROTTLE BACK-UP, ELEVATED LOW IDLE ENABLE,AND GROUND LEVEL SHUTDOWN (2) SWITCHES

THROTTLESENSOR

ACCELERATORPEDAL

DISCONNECT SWITCH

HEUI SYSTEMCOMPONENT DIAGRAM

MACHINEHARNESS

Two Speed/Timing Sensors are installed: a primary and a secondary. TheSpeed/Timing Sensors serve three functions in the system:

1. Engine speed measurement

2. Engine timing measurement

3. Cylinder and TDC location

The Speed/Timing Sensors, which are mounted on the front housingbelow the timing gear wheel, are self-adjusting during installation andhave zero clearance with the timing wheel.

The head is extended prior to installation. The action of screwing in thesensor pushes the head back into the body until the head contacts thetiming wheel. This contact is only momentary while the engine isstarting. After start-up, the head runs with zero clearance.

STMG 672 - 34-4/97

27

Primary sensor

Secondary sensor

Power supply

393229381812

732-PK996-GN998-BR999-WHF723-PKF724-PU

SECONDARY ENGINE SPEED+V TIMINGDIGITAL RETURNPRIMARY ENGINE SPEEDTIMING CAL +TIMING CAL -

ECM(3408E/3412 E)

P2 J2

ABC

ORBKWH

SECONDARYSPEED/TIMING

SENSOR

ABC

ORBKWH

PRIMARYSPEED/TIMING

SENSOR

TIMING CALIBRATIONCONNECTOR

12

SPEED/TIMING SENSORS

P44 J44

P20 J20

P26 P1 J1

The Primary Speed/Timing Sensor (right side of engine) measures enginespeed for governing, and crankshaft position for timing purposes andcylinder identification.

The Secondary Speed/Timing Sensor (left side of engine) allowscontinuous operation if the primary sensor fails. A failure of the primarysensor will cause the ECM to automatically switch to the secondarysensor. Also, the check engine lamp will come on.

The ECM supplies 12.5 1 Volts to the Primary and SecondarySpeed/Timing Sensors.

Connectors A and B transmit the common power supply to the sensors.The C connectors transmit separate signals from each sensor to the ECMfor back-up purposes.

NOTE: The Speed/Timing Sensors have a dedicated power supply.No other circuits should be spliced into this power supply.

STMG 672 - 35-4/97

Timing wheel

28

The Timing Wheel is an integral part of the drive gear for the pump.Timing marks are used to locate the wheel in the correct position relativeto the crankshaft. This Timing Wheel is common to all 3408E/3412Eengines.

As previously stated, the Timing Wheel has a total of 24 teeth. 23 teethare large with small spaces between them (80/20 relative size).

The other tooth and space have equal dimensions (50/50 relative size).This configuration is used by the ECM to locate TDC on the No. 1cylinder.

NOTICE

The head of the sensor MUST NOT be positioned in the timing wheel(wide) slot during installation. Incorrect positioning will causedamage to the sensor head.

STMG 672 - 36-4/97

29

Sensors generate aPWM signal fromtiming wheel teeth

Failure modes

4

3

6

5

7

2

1

8

REF

REF

REF

REF

REF

REF

REF

REF

TDC

TDC

TDC

TDCTDC

TDC

TDC

SINGLE50/50 TOOTH

TIMING WHEELROTATION

TDC CYLINDER No. 1

TIMINGCALIBRATIONRANGE 10

PRIMARYSPEED/TIMING

SENSOR


SENSOR

TIMING WHEEL

The Speed/Timing Sensors are positioned vertically over the teeth.

The teeth and sensors generate a Pulse Width Modulated (PWM) outputsignal for the purpose of timing and a frequency modulated output signalfor speed measurement.

The Secondary Speed/Timing Sensor functions the same as the primarysensor. The Secondary Speed/Timing Sensor is used when the signal fromthe primary sensor is lost or distorted. If the secondary sensor is selected,it will continue in use until the engine is shut down and cranked. Then,the primary sensor will be selected.

Unless the engine is cranking, the ECM will not switch from thesecondary to the primary sensor. This feature prevents constant switchingbetween sensors if an intermittent fault occurs.

INSTRUCTOR NOTE: A description of PWM signals is providedlater in this presentation (Sensors and Systems).

STMG 672 - 37-4/97

30

Cranking

Timing wheel teethand spacing

A B C D E F G

TIMING WHEEL ROTATION

H

80/20 % 80/20 % 80/20 %80/20 % 50/50%80/20 % 80/20 %

TIMING GEAR TOOTH TABLE

TABLEENTRY

CYLINDERREFERENCE

ABCDEFGH

80 %80 %80 %80 %80 %80 %80 %50 %

CRANKING

NONE IDENTIFIED

PWM DUTYCYCLE

The Speed/Timing Sensor uses the timing wheel with the teeth arrangedas shown to determine:

- Top Dead Center No. 1 (When found, the cylinders can beidentified.)

- Engine speed

The sequence of signals shown in the second column (duty cycle) isanalyzed by the ECM. At this point, no fuel will be injected until certainconditions have been met.

Unlike EUI engines, this engine does not rely on tooth configuration toprevent reverse rotation. The lubrication and the hydraulic pumps will notdevelop pressure during reverse rotation, and will not move the injectorsto pump fuel. Therefore, the engine cannot run in reverse.

STMG 672 - 38-4/97

31

After patternrecognition

Initial firing sequence


CYL NO. 3REFERENCE

EDGE

CYL NO. 4TDC

CYL NO. 4REFERENCE

EDGE

CYL NO. 8REFERENCE

EDGE

CYL NO. 3TDC


CYLINDERREFERENCE

80 %80 %80 %80 %80 %80 %80 %50 %

AFTER PATTERN RECOGNITION

NOCYL NO. 3NONOCYL NO. 4NONOCYL NO. 8

TABLEENTRY

ABCDEFGH

PWM DUTYCYCLE

A B C D E F G H

During start-up, the sensor initially monitors the pulses created by thepassing teeth and identifies the sequence as shown. After a completerotation, the control can recognize the location of TDC from the pattern inthe above illustration.

During initial cranking, no fuel is injected until:

The timing wheel has completed a full revolution.

TDC for all cylinders is identified by the control.

After the sensor has provided the necessary signals, the ECM is ready tostart injection (if sufficient hydraulic pressure is available to the injectors).

NOTE: The reference points in the illustration are positions on thetiming wheel from which the control measures the point of injectionand TDC.

STMG 672 - 39-4/97

32

Normal operation

Signal patternidentifies TDC

Conditions forinjection


PWM DUTYCYCLE

CYLINDERREFERENCE

80 %80 %80 %80 %80 %80 %80 %50 %

NORMAL OPERATIONNOCYL NO. 3NONOCYL NO. 4NONOCYL NO. 8

CYL NO. 4(REFERENCE)

CYL NO. 4ACTUAL TDC

(CALIBRATED)

62 BTDC (EEPROM)

DES TIMING

NO. 4INJECTION

TABLEENTRY


ABCDEFGH

A B C D E F G H

CYL NO. 3(REFERENCE)

CYL NO. 3ACTUAL TDC

(CALIBRATED)

62 BTDC (EEPROM)

DES TIMING

DELAY NO. 3INJECTION

DELAY

ASSUMEDTDC

ASSUMEDTDC

During normal operation, the ECM can determine timing from thesequence reference point for each cylinder. The reference point is storedby the ECM after calibration is performed.

Injection timing is calibrated by connecting a TDC probe to the serviceaccess connector on the engine harness, and by activating the calibrationsequence with the Caterpillar ET service tool. The ECM raises the enginespeed to 800 rpm (to optimize measurement accuracy), compares theactual No. 1 TDC location to the assumed cylinder No. 1 TDC location,and saves the offset in the EEPROM (Electrically Erasable ProgrammableRead Only Memory).

NOTE: The calibration offset range is limited to 10 crankshaftdegrees. If the range is exceeded, the offset is set to zero (nocalibration) and a calibration diagnostic message is generated.

STMG 672 - 40-4/97

33

Timing calibrationsensor

393229381812

732-PK996-GN998-BR999-WHF723-PKF724-PU

SECONDARY ENGINE SPEED+V TIMINGDIGITAL RETURNPRIMARY ENGINE SPEEDTIMING CAL +TIMING CAL -

ECM(3408E/3412E)

P2 J2

ABC

ORBKWH


SENSOR

ABC

ORBKWH

PRIMARYSPEED/TIMING

SENSOR

TIMING CALIBRATIONCONNECTOR

P26

TIMING CALIBRATIONSENSOR

TIMING CALIBRATION SENSOR

P44 J44

P20 J20

P1 J1

12

The Timing Calibration Sensor(magnetic pickup) is installed in theflywheel housing during calibration. The connector is located above theECM. (On some machines, i.e. D9R/D10R, the sensor is permanentlyinstalled.)

Using the Caterpillar ET service tool, timing calibration is performedautomatically for both sensors when selected on the appropriate screen.

The desired engine speed is set to 800 rpm. This step is performed toavoid instability and ensures that no backlash is present in the timinggears during the calibration process.

STMG 672 - 41-4/97

34

Timing calibration

Nulls out smallcrankshaft to timinggear tolerances

REFERENCE EDGE TO TDC DISTANCE

REFERENCEEDGE ASSUMED

CYL. NO. 1 TDCACTUAL

CYL. NO. 1 TDC

TIMINGREFERENCE

OFFSET

MAXIMUM TIMING REFERENCE OFFSET 10 DEGREES

TIMING CALIBRATIONSENSOR SIGNAL

TIMINGWHEEL

TIMING CALIBRATION

+10

10

-10

As the Speed/Timing Sensors use the timing wheel for a timing reference,timing calibration improves fuel injection accuracy by correcting for anyslight tolerances between the crankshaft, timing gears and timing wheel.

During calibration, the offset is logged in the control module EEPROM(Electrically Erasable Programmable Read Only Memory). Thecalibration offset range is limited to 10 crankshaft degrees. If timing isout of range, calibration is aborted. The previous value will be retainedand a diagnostic message will be logged.

Timing calibration is normally performed after the following procedures:

1. ECM replacement

2. Speed/timing sensor replacement

3. Timing wheel replacement

STMG 672 - 42-4/97

35

Unit injector currentflow

INJECTION CURRENT WAVEFORM

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

PULL-IN PEAK CURRENT

HOLD-IN PEAK CURRENT

ONE CYCLE

5

This illustration shows how the current increases initially to pull in theinjection coil and close the poppet valve. Then, by rapidly chopping(pulsing) the 105 Volts on and off, current flow is maintained. The end ofinjection occurs when the current supply is cut off and hydraulic pressuredrops. Therefore, fuel pressure drops rapidly in the injector.

INSTRUCTOR NOTE: This waveform may be demonstrated with a9U7330 Digital Multimeter (or equivalent) and a current probe.

STMG 672 - 43-4/97

36

Poppet valvemovement

POPPET VALVE MOVEMENT

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

CURRENT

POPPETLIFT

5

This diagram shows that the poppet valve will open just after the ECMenergizes the solenoid. The poppet valve permits hydraulic oil to shift theinjector intensifier piston which then moves the injector plunger.

STMG 672 - 44-4/97

37

Timing relative to:

1. Injector currentflow

2. Poppet valvemovement

3. Injection rate

WAVEFORM AND RESPONSE CHARACTERISTICS

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

CURRENT

POPPETLIFT

INJECTIONRATE

START OFINJECTION

DURATION

5

END OFINJECTION

Here timing is graphically illustrated to show:

1. The ECM initiates the signal to the injector to start injection.

2. The injector solenoid opens the poppet valve.

3. The injection rate increases.

STMG 672 - 45-4/97

Fuel system limits

Variable horsepower

Economy Shift Mode

38

FUEL SYSTEM COLD MODES

Speed Control

Fuel Limiting Injection Timing Injection Actuation Pressure Ether Injection

Just as the MUI engine had mechanical limits to determine maximum fueldelivery during full load, full torque and acceleration, the HEUI systemalso has electronic limits to protect the engine. These limits are:

- Maximum Horsepower

- Torque Limit (Determines torque rise characteristics)

- Fuel Ratio Control (Limits fuel until sufficient boost is available)

- Cold Mode Limit (Limits fuel with cold engine to control whitesmoke)

- Cranking Limit (Limits fuel during cranking)

An acceleration delay during start-up holds the engine at low idle for twoseconds or until oil pressure reaches 140 kPa (20 psi).

Off-highway Trucks have a system which increases engine horsepower indirect drive only. This system protects the driveline from excessivetorque in the lower gears.

Off-highway Trucks also have a service tool programmable feature whichis designed to lower shift points and the fuel limit to improve fuelconsumption at the customer's request.

STMG 672 - 46-4/97

Cold modes

39

FUEL SYSTEM COLD MODES

Speed Control Fuel Limiting Injection Timing Injection Actuation Pressure Ether Injection

The HEUI fuel system is designed to modify the operationalcharacteristics of the engine during cold operation. This modification isdone to protect the environment, the engine and to improve theoperational characteristics of the engine.

INSTRUCTOR NOTE: The various Cold Modes are tabulated inServiceman's Handout No. 2. Discuss how these Cold Modevariations can change the engine characteristics, particularly duringdiagnostic operations. For example:

- Injection actuation pressure will vary with engine temperature.

- Engine speed may be raised in Cold Mode.

STMG 672 - 47-4/97

Fuel system derates

Power correction

40

FUEL SYSTEM DERATES

Automatic Altitude Compensation

Automatic Filter Compensation

Engine Warning Derate

As the system limits fuel for every condition, derates are also built intothe system for protection. These derates are individually covered later inthe presentation, but are summarized here:

- Automatic Altitude Compensation (Altitude derate)

- Automatic Filter Compensation (Derates for air filter restriction ifinstalled)

- Engine Warning Derate (Derates for low oil pressure and highcoolant temperature; not installed on all applications)

If a loss of boost sensor output occurs, the ECM assumes zero boostpressure. Although not strictly a derate, power is reduced byapproximately 50 to 60%.

- Fuel Temperature Compensation (Compensates up to 5% forpower loss caused by hot fuel)

STMG 672 - 48-4/97

INSTRUCTOR NOTE: This material will be reinforced if thefollowing ET tasks are demonstrated. Review the material withquestions following the tasks. The demonstration can be performedon an engine or machine with a laptop computer. The suggestedtopics are:

Basic ET review (if required)

Status screens with throttle switch status, desired engine speed,fuel position, injection actuation pressure, etc.

Active diagnostic codes

Logged diagnostic codes

Events screen

Configuration screen

Timing calibration

Injector solenoid test

Cylinder cutout

Automatic injector test

STMG 672 - 49-4/97

41

FUEL INJECTION SYSTEM

FUEL INJECTION SYSTEM

This portion of the presentation describes the principles of operation ofthe HEUI Fuel Injection System as is used on the 3408E and 3412Eengines.

INSTRUCTOR NOTE: The various color codes which will be usedin this section of the presentation to identify flow and pressures are:

Hydraulic and Lubrication Circuits

Red - High pressure oil

Red and White Stripes- Reduced pressure oil

Brown - Lube oil pressure

Green - Lube oil suction or return

Fuel Circuits

Red - High pressure fuel

Red and White Stripes- Fuel transfer pump pressure

Green - Fuel suction or return

STMG 672 - 50-4/97

42

PUMPCONTROL

VALVE

OILFILTER

OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSORCOLD START

OILRESERVOIR OIL PRESSURE

SENSOR

ECM

HYDRAULICSUPPLY

PUMPGROUP

COOL DOWNCIRCUIT

FUEL TANK

FUELTEMPERATURE

SENSOR

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTER

FUELTRANSFER

PUMP

PRIMARYFUEL FILTER

WATERSEPARATOR

LUBE OILPUMP

TO LUBESYSTEM




Actuation of the fuel injection system is accomplished using hydraulics,rather than the conventional camshaft actuation commonly found on otherdiesel fuel systems.

Hydraulic actuation offers several advantages compared to mechanicalactuation, including the ability to make injection pressure independent ofengine operating speed. This capability is especially advantageous inmany respects, including transient engine response, cold starting,emissions and noise control.

INSTRUCTOR NOTE: The following schematics may appearidentical in the black and white illustrations. However, the actualslides are colored differently.

STMG 672 - 51-4/97

HEUI principlecomponents:


2. ECM

3. Temperaturesensor

4. Pressure sensor

5. Injector

43

12

3

54

System Components

To review, the 3400 HEUI hydraulic and fuel supply circuits contain thefollowing major components:

Hydraulic Supply Pump Group (1) including:

- Hydraulic pump

- Fuel transfer pump

- Pump control valve

Electronic Control Module (ECM) (2)

Electronic Sensors (3 and 4)

- Hydraulic temperature

- Hydraulic pressure

Injectors (5)

STMG 672 - 52-4/97

Hydraulic supplypump group:

1. Hydraulic pump

2. Pump control valve

3. Transfer pump

44

1

2

3

The following components are integrated into a single unit called theHydraulic Supply Pump Group:

- Hydraulic pump (1)

- Pump control valve (2)

- Transfer pump (3)

This pump group is located in the vee of the engine and is in the sameposition as the fuel injection pump on earlier engines.

Three fluid circuits are included in the system: low pressure oil, highpressure oil (hydraulic), and low pressure fuel supply.

NOTE TO THE INSTRUCTOR: These components and circuits willbe covered in detail later in the presentation.

STMG 672 - 53-4/97

45

Low pressure oilsupply

Cold start reservoir

Pressure sensor

Temperature sensor

TO LUBESYSTEM

FUELTRANSFER

PUMP

PUMPCONTROL

VALVE

OILFILTER


OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSOR

OIL PRESSURESENSOR

ECM

COOL DOWNCIRCUIT

LOW PRESSURE OIL (HYDRAULIC) SUPPLY

FUEL TANK

FUELTEMPERATURE

SENSOR

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTERPRIMARY

FUEL FILTERWATER

SEPARATOR

LUBE OILPUMP

COLD STARTOIL

RESERVOIR

HYDRAULICSUPPLY

PUMPGROUP



System Operation

On a HEUI equipped engine, the lubrication pump has two functions:

1. Provides lubrication to the engine2. Provides low pressure charge oil to the HEUI hydraulic pump

The engine lubrication pump has been enlarged to provide the requiredincrease in flow.

The hydraulic pump has a Cold Start Oil Reservoir. This reservoirprevents the hydraulic pump from cavitating during initial enginecranking until the lubrication pump can supply adequate charge pressure.

An oil pressure sensor is located in the Cold Start Oil Reservoir, which isthe inlet to the hydraulic oil pump. The sensor monitors lubrication oilpressure. An oil temperature sensor is also installed in the reservoir. Thissensor will be referred to as the "hydraulic temperature sensor" as it isused for this purpose.

STMG 672 - 54-4/97

46

High pressureactuates hydraulics

TO LUBESYSTEM

FUELTRANSFER

PUMP

PUMPCONTROL

VALVE

OILFILTER


OILCOOLER

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSOR

OIL PRESSURESENSOR

HYDRAULICSUPPLY

PUMPGROUP

COOL DOWNCIRCUIT

HIGH PRESSURE HYDRAULICS

FUELTEMPERATURE

SENSOR

ECM

FUEL TANK

PRESSUREREGULATING

VALVE

SECONDARYFUEL

FILTERPRIMARY

FUEL FILTERWATER

SEPARATOR

LUBE OILPUMP

COLD STARTOIL

RESERVOIRFLUID MANIFOLD

HYDRAULIC PASSAGE


During normal operation conditions, oil is pressurized between5000 and 21500 kPa (725 and 3100 psi) by the high pressure hydraulicpump to actuate the injectors. The level of hydraulic pressure iscontrolled by the ECM, which signals the pump control valve to upstrokethe hydraulic pump.

When the engine is running, high pressure oil is available to all injectorsat all times.

Oil from the high pressure pump enters the two oil supply passages.

Reverse flow check valves are used to prevent pressure surges betweenthe oil passages on opposite banks. The oil supply passages are connectedhydraulically to the injectors by jumper tubes. Oil used by the injectors isreleased below the valve covers and drains back to the sump through thepushrod compartments.

STMG 672 - 55-4/97

47

Low pressure fuelsupply

Injector cooling

TO LUBESYSTEM

FUELTRANSFER

PUMP PRESSUREREGULATING

VALVE

PUMPCONTROL

VALVE

OILFILTER


OILCOOLER

LUBE OILPUMP

HEUI

HEUI

OILSUMP

HYDRAULICPRESSURE

SENSOR


SENSOR

OIL PRESSURESENSOR

ECM

COOL DOWNCIRCUIT

LOW PRESSURE FUEL SUPPLY

FUELTEMPERATURE

SENSOR

FUEL TANK

SECONDARYFUEL FILTER(2 MICRON)

PRIMARYFUEL FILTER

WATERSEPARATOR

COLD STARTOIL

RESERVOIR

HYDRAULICSUPPLY

PUMPGROUP



Fuel is drawn from the tank through the water separator and the handpriming pump by a gear-type transfer pump. The fuel is then directedthrough the Electronic Control Module (ECM) housing for coolingpurposes. The fuel then flows through the secondary fuel filter.

Next, the fuel enters the low pressure supply gallery located in the fluidsupply manifolds on top of the cylinder heads. Any excess fuel notinjected leaves the manifold. The flow is then combined into one line andpasses through the pressure regulating valve, which is set between310 and 415 kPa (45 and 60 psi). From the pressure regulating valve, theexcess flow returns to the tank. The ratio of fuel between combustion andfuel returned to the tank is about 1:3 (i.e. four times the volume requiredfor combustion is supplied to the system for combustion and injectorcooling purposes).

A fuel temperature sensor is installed in the fuel supply system tocompensate for power losses caused by varying fuel temperatures.

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48

Fuel and oil flow

LOW PRESSUREFUEL SUPPLY

CYLINDER HEADINJECTOR SLEEVE

FLUID SUPPLYMANIFOLD

INJECTOR

INJECTOR OILADAPTER

JUMPER TUBE

INJECTOR CLAMP

HIGH PRESSUREHYDRAULIC PASSAGE

CYLINDER HEAD

ROCKER ARM BASE

LUBE OIL PASSAGE

CYLINDER BLOCKCOOLANT

METAL WASHER

INJECTOR FLUID FLOW HIGH PRESSURE HYDRAULIC OIL

Hydraulic Unit Injector Operation

High pressure hydraulic oil is provided to each injector from the hydraulicsupply passages through individual jumper tubes.

Fuel is supplied to the injector by the low pressure supply passage locatedin the fluid manifolds (described on the next slide).

Special "Viton" o-rings are used in the hydraulic joints between theinjector and the fluid manifold.

NOTE: This slide and the following slide depart from the colorlegend by using orange for high pressure oil to avoid confusionbetween the two fluids.

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49

Low pressure fuelsupply to injector

FLUID SUPPLYMANIFOLD

INJECTOR

CYLINDERHEAD

LOWER INJECTORO-RING SEAL

UPPER INJECTORO-RING SEAL

INJECTOR FUEL SUPPLY

METAL-TO- METALCONTACT

LOW PRESSUREFUEL SUPPLY


UPPER SLEEVEO-RING SEAL

LOWER SLEEVEO-RING SEAL

Low pressure fuel is supplied to the inlet of the injector through a drilledpassage located in each Fluid Supply Manifold.

The fuel supply to each injector is sealed from the combustion chamberand the area below the valve cover by upper and lower o-ring sealsbetween the injector and the cylinder head injector sleeve.

Combustion chamber gases are prevented from entering the fuel supplypassage by a metal-to-metal contact between the cylinder head injectorsleeve and the injector.

The cylinder head injector sleeve is threaded into the cylinder head. Ametal washer is used to seal the lower end of the adapter to preventleakage between the cooling system and the combustion chamber.

STMG 672 - 58-4/97

Fluid supply manifold

Supply passages:

1. Hydraulic

2. Lubrication

3. Fuel

50

21 3

The following passages are located in the Fluid Supply Manifold:

- Hydraulic supply passage (1)

- Lubrication supply passage (2)

- Fuel supply passage (3)

The fluid supply manifold is mounted on the cylinder head and carriesinjector actuation hydraulic oil under pressure through the jumper tubes tothe injectors.

Low pressure fuel and lubrication oil to the valve mechanism are alsodirected through the manifold. These passages are shown in the sectionalview on the next slide.

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51

Supply passages

Additional fuel forcooling

Fuel seals

LOW PRESSUREFUEL SUPPLY PASSAGE


HIGH PRESSUREHYDRAULIC PASSAGE

ROCKER ARMBASE

LUBRICATION OILPASSAGE

EXTRACTORSPLINES

FUEL SEALS

FLUID SUPPLY MANIFOLD

This sectional view shows the various passages in the Fluid SupplyManifold.

- High pressure hydraulic supply passages

- Low pressure fuel supply passages

- Lubrication oil supply passages

The fuel enters the front of the manifold and exits the rear. Cooling of theinjectors is achieved by circulating a larger volume of fuel past theinjectors than is required for combustion.

Initially, fuel circulates around the outside of the injector sleeve and iscontained between the sleeve and the fluid supply manifold by the upperand lower injector sleeve fuel seals.

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Jumper tube and oiladaptor

52

1

2

The Jumper Tube (1) and Injector Oil Adaptor (2) direct hydraulic oilfrom the fluid manifold high pressure passage to the injector.

A specific procedure to tighten the six bolts (for the Jumper Tube andAdaptor) must be followed when installing the jumper tube. Thisprocedure follows later in the presentation.

NOTICEFailure to follow the correct tightening procedure can result in lowpower complaints caused by internal hydraulic leaks. Also, internalstrains on the injector caused by an improper tightening procedurecan cause changes in internal injector clearances which can decreaseperformance and injector life.

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53

Injector currentwaveform

Two current levels

INJECTION CURRENT WAVEFORM

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

PULL-IN PEAK CURRENT

HOLD-IN PEAK CURRENT

ONE CYCLE

5

Injector Operation Characteristics

The quantity of fuel delivered is controlled by varying the time thesolenoid is energized. This period of time, called "duration," is calculatedby the ECM to ensure delivery of the correct amount of fuel. Other inputsaffect calculation of on-time, including (but not limited to) hydraulicsupply pressure, oil temperature and mapped injector performancecharacteristics. Two current levels are generated in the wave form:

1. Pull-in current is higher to create a stronger magnetic field toattract the armature and lift the injector poppet valve off its seatagainst spring force.

2. Hold-in current is used to hold the armature and poppet off itsseat. Lower current reduces heat in the solenoid and increasessolenoid life.

The injector performance map shows delivery as a function of on-time,pump pressure, and oil temperature, and is stored in the ECM memory.

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54

Waveform and injectorresponse

WAVEFORM AND RESPONSE CHARACTERISTICS

0 1 2 3 4

CU

RR

EN

T

FL

OW

TIME (MILLISECONDS)

CURRENT

POPPETLIFT

INJECTIONRATE

START OFINJECTION

DURATION

5END OF

INJECTION

This slide shows that, as the ECM energizes the solenoid, the poppet valvemovement follows. Then, the injector rate increases for the start ofinjection. The end of injection occurs as the rate drops toward zero.

Therefore:

Engine fuel timing is a function of the start of injection.

Fuel quantity is a function of:

- The duration of injection - Injection actuation (hydraulic) pressure

STMG 672 - 63-4/97

Pull-in current

Poppet lift - Blue line

Start of injection- Purple line

Injection rate - Purple line

End of injection

The ECM sends a higher current to the solenoid to create a strongmagnetic field. This strong field is needed to create maximum pull on thearmature, which is at its farthest distance from the solenoid.

The poppet is normally held on its inlet seat by the poppet spring. Thehigher pull-in current attracts the armature and lifts the poppet off its inletseat and toward the exhaust seat against the spring force. The ECMreduces the current level to hold-in current and the poppet is held on itsexhaust seat.

Injection starts after the exhaust seat closes and oil pressure pushes theintensifier piston and plunger down. The downward movement of theplunger pressurizes the fuel to approximately 31000 kPa (4500 psi) andthe check valve lifts, allowing fuel to enter the cylinder. The time atwhich fuel leaves the tip is called the "start of injection."

The rate at which fuel is injected is controlled by injection hydraulicpressure. Higher hydraulic pressure pushes the piston and plunger faster,causing a higher flow rate through the nozzle tip.

When the ECM ends injection, it terminates the hold-in current whichcauses the magnetic field in the solenoid to collapse. The poppet springthen moves the poppet back to the inlet seat. As the poppet travels backto the inlet seat, hydraulic oil is shut off, and the downward travel of thepiston and plunger reverses, filling the barrel for the next injectionsequence.

As pressure drops below the plunger and nozzle areas, the valve closingpressure, which is about 21000 kPa (3000 psi), causes this pressure to beretained in the nozzle for the next cycle.

INSTRUCTOR NOTE: If a disassembled or a cutaway injector isavailable, it is recommended that the preceding sequence be reviewedusing the actual components.

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Major components

Seals

55

Injector Components

The 3408E/3412E unit injector has been designed to represent the state ofthe art in the industry. This section of the presentation will describe allthe components and their functions.

This slide shows a cutaway injector and the injector sleeve. Note thefollowing major injector component groups:

- Valve body group with solenoid and poppet valve

- Barrel group with intensifier piston and plunger

- Nozzle group

The injector sleeve has four seal grooves. The two upper grooves havethe seals which contain the fuel within the fluid manifold (shown in moredetail later).

The two lower seals contain the coolant below the cylinder upper deck. Ametal washer seals the lower part of the sleeve and prevents coolant fromentering the combustion chamber.

STMG 672 - 65-4/97

56

Three main groups

HEUI UNIT INJECTOR

3 MAIN GROUPS

VALVE BODYGROUP

BARREL GROUP

NOZZLE GROUP

The injector consists of three basic groups which will be described indetail:

- Valve Body Group

- Barrel Group

- Nozzle Group

This view and those that follow show the exhaust port on the injectorventing the return oil downward. This condition is a modification fromthe previous design which vented the oil upward. These injectors areinterchangeable. However, the newer injector reduces the tendency of theengine to discharge oil mist from the breather.

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57

Injector components

STOPPINPLUNGER SPRING SEAL BARREL BALL

DOWEL

SEAL

INTENSIFIER PISTON

RETAINER RING

WASHER

STOPPLATE

CHECKPLATE

BALL

STOP

DOWEL

SPRING

LIFTSPACER

SLEEVE

DOWEL

CHECK

TIP CASE

POPPET SPRING SLEEVE SHIM SEAL

ADAPTER BOLT

SPACER

ARMATURE

SCREW

SOLENOIDASSEMBLY

SCREW

BODYVALVE BODY GROUP

BARREL GROUP

NOZZLE GROUP

3408E/3412E HEUI INJECTORCOMPONENTS

The HEUI injector was designed with a minimum of component parts.The injector contains 35 part numbers.

This exploded view shows all the components by assemblies as follows:

The Valve Body Group contains the solenoid, armature and the poppetvalve. This assembly directs the oil to the hydraulic intensifier pistonwhich moves the fuel plunger.

The Barrel Group contains the high pressure fuel plunger.

The Nozzle Group contains the case, tip, check valve and nozzle.

NOTE: Although the injector components are explained in thispresentation, it should be noted that no individual parts of theinjector are serviced. This injector is precision assembled by amachine, and replacing individual injector components would resultin unacceptable performance problems or injector failures.

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58

Injector componentparts

SHIMBARREL

PISTON

VALVE

FUEL INLETCHECK VALVE

PIN

SPACER

ADAPTER

SPACER

ARMATURE

SOLENOID

WASHER

PLUNGER

SLEEVE

SLEEVE

UNIT INJECTOR COMPONENTS

LOWER FUEL SEAL

VALVE BODY

UPPER FUEL SEAL

NOZZLE

CHECK

This slide shows the component parts in the three basic groups discussedpreviously.

The valve body has three parts (body, adaptor and spacer) which areassembled with great precision. Any damage sustained in the valve bodyarea during installation or removal will cause an injector failure.

NOTICEThe correct injector removal procedures and tooling specified in theservice manual must always be used. Any leverage applied below thevalve body can cause deformation of the poppet valve bore andpossible injector failure.

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59

HORIZONTALBOLTS

JUMPER TUBE

INJECTOR CLAMP

VERTICALBOLTS

INJECTOR INSTALLATIONALLEN

SCREWS

INJECTOR OILADAPTOR

Injector Removal and Installation

The correct procedures for injector removal and installation must befollowed to avoid strain on the injector and hydraulic leaks in the jumpertube area. The three mating surfaces of the jumper tube, oil adaptor andinjector must be aligned before final torque is applied.

INSTRUCTOR NOTE : At this time, it is recommended that theinjector removal and installation procedures be demonstrated.Emphasis should be placed on the use of the correct puller duringremoval (rather than a pry bar, which could result in injectordamage). Also, disassemble a used injector to identify the variouscomponents shown on this slide.

STMG 672 - 69-4/97

Injector assembly andinstallation

This portion of the assembly procedure ensures that all mating and sealingfaces are flush and in complete contact before tightening the bolts.

1. Clean the faces of the injector and the injector sleeve and installnew o-rings.

2. Lubricate the o-rings with oil and insert the injector in the injectorsleeve.

3. Visually align the injector with the flat surface parallel to thecenterline of the engine.

4. Position the injector clamp on the injector and tighten the bolt to 47 9 Nm (35 7 lb. ft.).

5. Install new seals on the jumper tube and rocker arm base.

6. Place the injector oil adaptor and jumper tube in position.

7. Install the allen screws and hex head bolts finger tight. If theinjector oil adaptor was previously installed on the injector, loosenthe allen screws.

The objective at this point in the procedure is to bring all the mating facesinto complete contact and alignment before starting the final torqueprocedure.

Failure to align the components will put a strain on the injector which willthen distort the poppet valve and barrel bores. These components operatewith a clearance of 5 microns because of the high injection and hydraulicpressures. Therefore, even a small amount of distortion will cause aseizure.

Additionally, some misalignment could cause combustion gases to enterthe supply system.

STMG 672 - 70-4/97

Injector installationtorque sequence

After all the mating surfaces are aligned, the torquing procedure can beperformed:

1. Tighten the allen screws and hex head bolts finger tight or justsufficiently to bring the mating surfaces together and intoalignment.

2. Apply an initial torque to the vertical hex head bolts of 5 3 Nm(4 2 lb. ft.).

3. Apply an initial torque to the horizontal hex head bolts of 5 3 Nm (4 2 lb. ft.).

4. Apply an initial torque to the allen screws of 1 0.2 Nm (10 2 lb. in.).

5. Final torque the vertical hex head bolts to 47 9 Nm (35 7 lb. ft.).

6. Final torque the horizontal hex head bolts to 47 9 Nm (35 7 lb. ft.).

7. Final torque the allen screws to 12 3 Nm (9 2 lb. ft.).

8. Check the system for leaks (crank with injection disabled). Then,check the hydraulic pressure (compare with desired pressure).

A number of possibilities for leaks can exist. Oil under high pressure mayleak from the jumper tube joints or from the injector valve body exhaustport. Fuel could leak from the upper seal on the injector. Also,combustion gas can possibly leak from the base of the injector.

If air has entered the fuel supply system, multiple injectors on one bankmay malfunction. If the above procedure was not followed, air couldenter past the lower o-ring seal. If this condition occurs, remove theinjector and check for carbon below the lower o-ring seal. Replace theseal and perform the torque sequence.

Air in the system may be detected by lightly touching the flexible returnline and checking for extreme pulsations or pressure spikes felt throughthe line. As an alternative, install a sight glass in each return line, run theengine and check for air.

Combustion gas leakage will usually affect the injector with the leakfollowed by the injectors downstream (toward the rear) of the leak.

In conclusion, the system is reliable. However, failure to follow theseprocedures may cause malfunctions.

STMG 672 - 71-4/97

60

Solenoid de-energized

Solenoid energized

Oil flows to intensifierpiston

SOLENOID DE-ENERGIZED SOLENOID ENERGIZEDPOPPET VALVE CLOSED POPPET VALVE OPEN

ARMATURESCREWPOPPET

SPRINGINLET

VALVE SEAT

SOLENOID

POPPET VALVE

ARMATURE

EXHAUSTVALVE SEAT

VALVE BODY GROUP

Injection Sequence

When the solenoid is de-energized, the poppet valve is held on its inlet(left) seat by the poppet spring. The poppet valve is connected to thearmature by the armature screw. When the poppet is closed, the inlet seatprevents high pressure oil from entering the injector. The exhaust poppetseat is open, connecting the intensifier piston cavity to the atmosphere.

Based on input signals from the various electronic sensors, the ECMcalculates the quantity and timing of fuel to be delivered by the injector tothe combustion chamber. At the appropriate time, the ECM sends anelectrical current to the injector solenoid.

The solenoid develops a magnetic force which attracts the armature andshifts the poppet valve. The poppet valve moves against the spring force,opens the inlet seat and closes the exhaust (right) seat. Hydraulic pressureoil from the supply manifold is directed through the jumper tube to the topof the intensifier piston.

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61

Plunger moves down

Pressurizes fuel belowplunger

Pressureintensification


INTENSIFIERPISTON

PLUNGER

FUEL TONOZZLE

BARREL

BARREL GROUPFUEL PRESSURE INCREASE

REVERSE FLOWCHECK VALVE

FUEL FROMTRANSFER PUMP

SUPPLY OIL

Supply oil flow from the poppet valve causes the intensifier piston and thefuel plunger to move downward. The displacement of the plungerpressurizes the fuel trapped between the plunger face and the nozzle checkseat.

NOTE: The intensifier piston has almost seven times the area of thefuel plunger. When the hydraulic circuit is supplying a pressure of21000 kPa (3000 psi), approximately 145000 kPa (21000 psi) will begenerated below the fuel plunger.

STMG 672 - 73-4/97

62

Fuel atomization

VIEW OF STOP PLATE & REVERSE FLOW CHECK VALVE


FUEL ATOMIZATION

NOZZLE GROUP

CHECK VALVE

When the trapped pressure exceeds the nozzle valve opening pressure(VOP), typically 31000 kPa (4500 psi), the check valve lifts, and fuelflows through the holes in the nozzle into the combustion chamber. At theend of injection, the nozzle check valve closes at approximately21000 kPa (3000 psi).

The reverse flow check valve is used to prevent combustion induced gasflow from entering the nozzle area.

The nozzle of the injector is very similar to the EUI unit injector. Sixorifices, each with a diameter of 0.252 mm (.010 in.), are arranged at anangle of 140 degrees.

STMG 672 - 74-4/97

63

End of injection

Solenoid de-energized

Poppet valve closes

INLETVALVE SEAT

SOLENOID

POPPET VALVE

ARMATURE

EXHAUSTVALVE SEAT

SOLENOID DE-ENERGIZED

VALVE BODY GROUP

The end of injection is accomplished by shutting off the current from theECM to the injector solenoid. The resulting loss of magnetic force on thearmature allows the return spring force to shift the poppet valve off theexhaust seat.

The poppet returns to the inlet seat in the valve body, blocks the flow fromthe hydraulic oil supply, and simultaneously fully opens the exhaust valveseat. This action vents the injector internal hydraulic circuit below thevalve cover.

STMG 672 - 75-4/97

64

End of injection

Intensifier pistonmoves up

Nozzle check valvecloses

SHIM

BARREL

PISTON

VALVE

BALL

PIN

SPACER

ADAPTER

SPACER

ARMATURE

SOLENOID

WASHER

PLUNGER

SLEEVE

SLEEVE

NOZZLE

BODY

UNIT INJECTOREND OF INJECTION

CHECK

When vented, the intensifier piston and fuel plunger are pushed upwardby the plunger return spring force until the intensifier piston contacts thevalve body. This upward displacement of the intensifier piston ventsspent oil from the injector below the valve cover.

Retraction of the fuel plunger decreases the pressure in the fuel chamberbelow the plunger, which permits the nozzle check valve to close whenthe pressure in the nozzle drops below the valve closing pressure (VCP)of approximately 21000 kPa (3000 psi).

STMG 672 - 76-4/97

65

Barrel refilling

BARREL GROUPREFILLING THE BARREL

BARREL

PISTON


PIN

SPACER

WASHER

PLUNGER

SLEEVE

NOZZLE

NOZZLE CHECKVALVE

FUEL EDGEFILTER

As the plunger continues to retract, the pressure below the plungerdecreases below the fuel supply gallery pressure. The fuel inlet checkvalve then opens, allowing fuel to pass through the edge filter (next slide)to the supply gallery to refill the injector for the next injection sequence.

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66

Fuel edge filter


EDGE FILTER

EDGE FILTER


FUEL INLET FUEL INLET

Note the location of the fuel edge filter. The edge filter is formed by twoflat parallel surfaces that are approximately 130 microns apart. Thesesurfaces trap and break down particles which might be big enough to plugthe nozzle orifices.

STMG 672 - 78-4/97

67

Injection rate shaping

Low emission levels

PRIME

PRIME INJECTION RATE SHAPING

0 1 2 3 4TIME (MILLISECONDS)

5

PRIME = PRE-INJECTION METERING INJECTION RATE

DURATIONSTART OF INJECTION

Another feature used in the injector for 3408E/3412E applications is aninjection rate shaping device. Rate shaping refers to tailoring the way fuelis delivered to the engine to obtain a desirable result. In the 3408E/3412Eapplication, rate shaping reduces the quantity of fuel delivered to thecombustion chamber during the ignition delay period (i.e. the timebetween the start of injection and start of combustion) to levels whichproduce low engine combustion noise and low emissions.

The device used to create rate shaping is known as PRIME, anabbreviation for PRe-Injection MEtering. This device is basically acontrolled spill port which serves to limit the amount of fuel delivered tothe combustion chamber during the initial 25% displacement of the fuelplunger. This metering action produces the desired reduction of fueldelivery during the ignition delay period.

STMG 672 - 79-4/97

68

Injection rate shaping

1. Start of injection

2. Pressure drop

3. Final increase

Benefits

CROSS SECTIONOF PLUNGER

PRIME RATESHAPING PASSAGE

PLUNGER

BARREL

SPILLPORT

FUEL TONOZZLE GROUP

START OF INJECTION PRESSURE DROPFINAL

PRESSURE INCREASE

BARREL GROUPPRIME RATE SHAPINGOIL FLOW

This slide shows the three stages in PRIME rate shaping.

1. Injection pressure starts to increase and causes the initialmovement of the plunger.

2. When the prime rate shaping passage on the plunger is passing thespill port in the barrel, pressure decreases below VCP aspressurized fuel leaks through the passage in the plunger into thespill port. At this time, nozzle flow momentarily decreases.

3. As the plunger continues downward, the PRIME rate passagepasses the spill port and pressure will again increase, causinginjection to resume.

This feature reduces emissions, smoke and noise. It also provides asmoother combustion cycle and reduces wear on the cylinder components.

STMG 672 - 80-4/97

69

Internal leakage

Fluids are vented topump inlet

BARREL GROUPVENTING INTERN

heui(curso completo)

Documents

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heui system3

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