Diesel Engine Electronics

Copyright © 2014 Delmar, Cengage Learning

Diesel Engine Electronics

Instructor Name: (Your Name)

14CHAPTER


Learning Objectives

• Discuss the various types of electronically controlled diesel fuel systems

• Describe why the current flow through an inductor can not instantly change

• Explain the fundamentals of a closed loop control system

• Discuss how an in-range failure might not cause a DTC to be set


Learning Objectives (continued)

• Explain the difference between in-cylinder emission reduction and exhaust aftertreatment

• Discuss how a variable geometry turbocharger can be used to regulate EGR flow rate

• Explain how particulate matter and NOx

exhaust emissions are controlled• Describe the requirements for HD-OBD and

discuss some of the benefits of this regulation for technicians


Electronically Controlled Engine

• Particulate Matter (PM) – Exhaust smoke• Oxides of Nitrogen (NOx) – One of the

pollutants responsible for smog• Electronic Control Module (ECM) –

Computer that controls engine fuel system


Typical 2010 Engine Wiring Harness

Figure 14-1 Typical 2010 engine wiring harness.


The Basic Tasks of a Diesel Fuel System

• Provide injection metering• Atomize the fuel • Provide injection timing control• Control fuel delivery independent of

engine speed and cam shaft geometry• Perform multiple injection events per cycle


Bosch RE30 Electronically Controlled Rack Actuator

Figure 14-5 Bosch RE30 electronically controlled rack actuator.


Bosch Electronically Controlled VE Distributive Pump

Figure 14-6 Bosch electronically controlled VE distributor injection pump used on smaller diesel engines.


Electronic Unit Injector (EUI)

• NOP – Nozzle opening pressure• NCV – Needle control valve• SV – Spill valve• EUP – Electronic unit pump• Pilot Injection – Small amount of fuel

injected in combustion chamber prior to main injection


Single Actuator EUI

Figure 14-10 Single actuator EUI.


Important Fact

The current flow through an inductor cannot change instantly from level to another. However, the voltage measured across an inductor can instantly change from one level to another.


Figure 14-12 Instantaneous current rise ina resistor circuit.

Figure 14-13 Ramped current rise in inductor circuit

Current Rise


Delphi E3 Dual Actuator EUI

Figure 14-15 Delphi E3 dual actuator EUI.


Nozzle Can Open When NCV is Energized

Figure 14-16 Nozzle opens when NCV is energized.


Electronic Unit Pump (EUP)

Figure 14-17 Electronic unit pump.


Main Components of a HEUI System

• High pressure oil pump develops the high pressure engine oil called injection control pressure (ICP)

• Injection pressure regulator (IPR)• ICP sensor• Electronic unit injectors (EUI)• High pressure oil manifold


Navistar HEUI Pressure Control System Components

Figure 14-18 Navistar HEUI injection pressure control system components.


Closed Loop Circuit

• ECM knows the desired injection control pressure

• ECM knows the measured or actual injection control pressure

• Measured injection control pressure can be changed by increasing or decreasing the duty cycle of the injection pressure regulator


Navistar Single Coil Unit Injector

Figure 14-24 Navistar single coil HEUI injector internal components.


CAUTION

Follow the OEM’s specific safety recommendations when troubleshooting any electronically controlled diesel fuel system to prevent fatal electric shock.


Navistar Second Generation Two-Coil HEUI Injector

Figure 14-25 Navistar second-generation two-coil HEUI injector.


WARNING

Never crack common rail fuel lines open with the engine running for any reason, including checking for a misfiring cylinder. Doing so could cause fuel under extreme pressure to penetrate your skin resulting in death or serious injury. Follow OEM instruction for rail pressure bleed down before loosening any components in the high-pressure fuel system. Never install a standard pressure gauge in a common rail system. The extreme pressure will cause the gauge to explode.


Caterpillar Common Rail Fuel System

Figure 14-27 Caterpillar common rail fuel system.


Common Rail High Pressure Pump with Control Solenoids

Figure 14-28 Common rail high-pressure pump with control solenoids.


Solenoid Controlled Common Rail Injector Nozzle

Figure 14-29 Solenoid-controlled common rail injector nozzle.


Piezo Actuated Common Rail Injector

Figure 14-30 Piezo-actuated common rail injector.


In Cylinder Exhaust Emission Reduction

• EGR – Exhaust gas recirculation• VGT – Variable geometry turbocharger• Smart Actuator – An actuator that contains a

microprocessor and communication interface• Virtual Sensor – Estimated value obtained

from mechanical models of the system• Learn Cycle – Actuator is driven from

minimum to maximum span at start up


Typical Cooled EGR System With VGT Turbocharger

Figure 14-31 Typical cooled EGR system with VGT.


Electrohydraulic VGT Actuator

Figure 14-32 Electrohydraulic VGT actuator.


Diesel After Treatment

• Aftertreatment – Modification of exhaust gasses after they leave the combustion chamber

• DPF – Diesel particulate filter• DOC – Diesel oxidization catalyst• SCR – Selective catalyst reduction• DEF – Diesel exhaust fluid


DOC/DPF System

Figure 14-35 DOC/DPF system.


Bosch Departronic® Fuel Dosing System

Figure 14-36 Bosch Departronic® fuel dosing system.


Caterpillar CRS System

Figure 14-37 Caterpillar CRS system. Compressed air is used to purge the injector and to aid in combustion.


Caterpillar CRS Injector and Spark Plug Assembly

Figure 14-38 Caterpillar CRS injector and spark plug details. Engine coolant is used to cool the injector.


SCR System Components

Figure 14-39 SCR system components.


Bosch Denoxtronic® System

Figure 14-40 Bosch Denoxtronic® system.


Heavy Duty On-Board Diagnostics

• HD-OBD – Heavy duty on board diagnostics• MIL – Malfunction indicator lamp• Started coming into effect in 2010• Pending DTC – ECM first detects an

emissions related malfunction; MIL will not illuminate

• Detected DTC – The pending DTC is detected on second drive cycle; MIL will illuminate


Pro Link 9000 EST

Figure 14-42 Pro-Link 9000 scan tool.


PC Based EST

Figure 14-43 PC-based electronic service tool.


Injector Cut Out Test Result

Figure 14-44 Injector cutout test results indicate a problem with #2 cylinder.


Two Channel Oscilloscope Displays Two Different Signals

Figure 14-46 Two-channel oscilloscope displays two different signals.


Typical J1939 Voltage Levels

Figure 14-47 Typical J1939 voltage levels using two-channel oscilloscope referenced to ground.


Summary• Vehicles with diesel engines sold in the U.S.

are subject to EPA exhaust emissions regulations. These regulations have resulted in substantial decreases of particulate matter and oxides of nitrogen emissions. To attain these requirements , electronic engine controls were necessary.

• Electronic unit injector (EUI) systems with single actuators control the spill valve opening and closing. Dual-actuator EUIs control both the spill valve and the nozzle opening.


Summary (continued)• Self-inductance prevents the current flow

through an inductor from changing quickly.• Hydraulically actuated electronic unit injectors

amplify engine lubrication oil under pressure to generate injection pressures.

• A closed loop control system compares a desired output to the measured output referred to as the error. A controller drives the output such that the error becomes zero, indicating the desired output and the measured output are the same. Closed loop systems are used in a variety of trucks.


Summary (continued)

• An in-range failure is a condition where the input voltage at an electronic control module is within the normal operating voltage range, but does not correctly represent what is being measured.

• Exhaust emissions can be controlled by a combination of in-cylinder techniques and by exhaust aftertreatment systems.

• A variable geometry turbocharger (VGT) can be used to regulate EGR flow.


Summary (continued)

• An H-bridge is an electronic circuit that causes the polarity of two wires to reverse to permit directional control of a electric motor.

• Soot is captured in a DPF. A periodic regeneration of the filter to oxidize the soot is sometimes necessary. Heat for the regeneration is produced either by diesel fuel being injected over a DOC or by igniting the fuel in a burner in the exhaust.


Summary (continued)

• SCR uses ammonia to reduce NOx. The ammonia is produced when an urea water solution called DEF is injected into the exhaust stream.

• HD-OBD describes the ability of a diesel engine to determine that its emissions have exceeded a threshold and to illuminate a MIL to alert the driver.

Diesel Engine Electronics

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