Euro 4 and Beyond Role of Diesel Fuel Injection Systems

1 Euro 4 and Beyond Role of Diesel fuel Injection SystemsDr. Gerhard ZieglerGeneral Manager (R&D and Application)Motor Industries 2004 SAE InternationalABSTRACTThe Euro 4 emission norms can be achieved by the well-known 2ndand 3rdgeneration Common Rail Systems ofBOSCH. The Beyond Euro 4 emission legislation is achallenging goal for Diesel engine emissions with highest engine performance,namely high specific power output, petrol like noiselevels,benchmarkinglowfuelconsumpti onandattractive costs are the targets for development activitiesof the future for the success will besophisticated fuel Injection system which supports all theabove mentioned.

2 BOSCH did launch very early a fundamentalproject defining the requirements for future injectionsystems with regard to mixture preparation, maximuminjection pressure, rate shaping capability and several versatile prototype injectionsystems a comprehensive engine investigation wasaccomplished to optimise the system configuration tomeet the above targets of Diesel engines. Applying thecriteria of performance, manufacturing robustness,lifetime durability and costs, the variety has beenreduced to a hydraulically amplified Diesel injectionsystem.

3 Which works with hydraulically concept togetherwith a potentialevaluation for two different Euro 5 scenarios is given inthis high-speed direct Injection Diesel engine has gainedworld-wide is especially successful inWestern Europe where the market share of newregistered vehicles exceeds 52%. It is predicted that themarket share of Diesel passenger cars will double by2014 in the rest of the world. This is due to the well-known advantages such as fun to drive, excellent fueleconomy and good noise seen in specific torque increased by a factor of 3 and specificpower by a factor of more than 4 over the last 6decades.

4 In parallel the fuel efficiency improved by 50%and power increased from 33 kW to 171 :Change of Diesel engine characteristicsOn the other hand, the Diesel engine faces more andmore continuously burdening challenges which areovercome using latest Injection technology. While thepetrol engines set the benchmark for Noise VibrationHarshness (NHV), the complexity of the overall dieselsystem becomes higher and higher in spite of thetremendous efforts to lower the overall system the truck segment of the Diesel world the targetsnamely fun to drive, NHV are not the main driversascompared to the passenger car maindriver is the absolute low fuel consumption which plays avital role for commercial vehicle fleet owners.

5 As the fuelconsumption covers the major part of the noting the fact that a modern Diesel enginestill represents the most robust drive train for commercialvehicles, the still rising challenge on life expectancyrequirements of the Diesel system , the fuel injectionequipment, is the future emission legislation for the passengercar and truck Diesel applications of the world market is abig challenge. To meet this challenge an overall systemoptimisation like fuel Injection equipment, the engine, thecombustion process and the exhaust gas treatment the task to realise a cost optimalsolution fulfilling the future emission legislation, petrollike comfort, lowest fuel consumption and fun to drive ontop.

6 Sounds like an impossible car vehicles require a big effort inexhaust gas treatment to fulfil future emission legislationleading to an unattractive low score for Diesel drive trainsystems. Emissions out of the engine have to bereduced by an overall Diesel system optimisation. Apromising approach is the air system , innovativeboost pressure concepts in combination with the adaption of the combustion process, forinstance the optimisation of the piston bowl has shown ahuge but not least the advance fuel Injection equipmentplays a key role to achieve future Diesel goals.

7 The basicquestion to develop the future fuel Injection equipment isthe overall system requirements, which willbe discussedin chapter 3 of this paper. Next we will focus on thestatus of the Euro 4 compliant COMMON RAIL Systems FOR EURO 4In 1997 BOSCH introduced the first Common RailSystem for Diesel engines [1]. The start of production ofthe Common Rail system 2ndgeneration was in 2000 [2],where the maximum system pressure was increased to1600 bar. A high pressure pump with quantity control,improvedinjectorswithmultipleinj ectionswasintroduced.

8 An overview of the Common Rail system 2ndgeneration is given in Fig. 2. Via the tank and the filterfuel is supplied by the gear pump to the quantity-controlled high pressure pump CP3. The suction throttleat the high pressure pump divides the fuel flow into twoparts: one supplies the pump elements and the otherserves for cooling the pump and lubricating the high pressure pump compresses the fuel up to 1600bar into the common rail. The rail pressure sensorregisters the actual pressure.

9 The rail pressure iscontrolled via the metering unit integrated into the highpressure pump. The pressure limiter valve opens in caseof any overpressure in the system due to anymalfunction. The solenoid actuated injectors areenergised depending on the set point of the electroniccontrol unit. Start and duration of the Injection as well asthe number of injections can be chosen : system overview Common Rail system 2ndgenerationIn 2004 the 3rdgeneration Common Rail system isintroduced into the market.

10 The system overview is givenin Fig. 3. The major changes are new software functionslike quantity balance control, pressure wave correction,lambda control and the totally new in-line piezo integrating of the piezo actuator into the injector bodya technology jump was achieved. The innovative in-lineconcept allows high nozzle needle velocities up to The excellent performance of the piezo injectorresults in higher flexibility of the engine design. Thequantity controlled high pressure pump is a compacthigh performance unit.