valvetronic engine technology - IFET College of Engineering

More documents

Recommendations

Info

VALVETRONIC ENGINE TECHNOLOGYINTRODUCTIONThe automobile has beenproviding individual mobility for morethan 100 years. This mobility is madepossible first and foremost bycombustion engines drawing their powerfrom fossil energy carriers, which, eventoday, provide the foundation ingenerating mechanical drive power inthe automobile. The primary objectivesin developing drive systems are to curbfuel consumption and reduce CO2emissions. In an effort to meet thischallenge, the automotive industry isdeveloping suitable new engines. Thevoluntary commitment assumed by theEuropean Automobile ManufacturersAssociation (ACEA) is to reduce thefleet emission average of all newlyintroduced cars to 140g of CO2 perkilometer by 2008 .The first objective is to minimiseemission components such ashydrocarbon, CO2 and nitrogen oxides(NOx) subject to specific limits. At thesame time, manufacturers are seeking tominimise fuel consumption and,accordingly, CO2 emissions. All of thisshould be achieved with a maximumstandard of comfort and safety on theroad. In the homologation of motorvehicles, Europe, Japan and the USapply different driving cycles todetermine emissions and fuelconsumption. However, it is theindividual customer who ultimatelydecides on his/her particular style ofmotoring and up to 30% of a car’s fuelconsumption depends on how it is drivenand the style of motoring that ispreferred by the driver. Clearly, thedevelopment engineer is unable toinfluence these external parameters – allthat he/she can do is change the basicfunctions and control factors in the carand its drivetrain. The amount of energyrequired for driving a vehicle also dropswith decreasing driving resistanceprovided by, for example, a reduction inroll and air resistance. To make moreefficient use of the energy in fuel, the
actual process of using energy mustreach a higher standard of efficiency.Despite modern engine technology, theprocess of on-going development has notyet come to an end. Looking at theoverall concept of a vehicle, thedevelopment engineer must thereforeoptimize the efficiency chain formed byall of the car’s individual components.For example, a car with a state-of-the-artspark-ignition engine uses only about20% of the energy consumed to actuallygenerate driving power and mobility inthe EU test cycle. This alonedemonstrates the remaining potentialEvolution of Valvetronic• the charge cycle;• friction; and• thermal losses through the walls.Optimisation in these areas indriving cycles with low loads and enginespeeds provides the greatestimprovements in fuel economy. Quitegenerally, steps taken to reduce thethrottle effect have a greater potential forsaving fuel than the reduction of frictionin the drivetrain (see Figure 2.1).Precisely with this in mind, BMW haseveloped a fully variable valve drivereferred to as Valvetronic, a systemoffering improvement in fuelconsumption comparable in virtually alldriving cycles to the latest spark-ignitionengines with direct fuel injection (DFI)and leanburn operation.The losses that are capable ofbeing influenced are composed primarilyof the following:• a combustion process not yet ideal;A number of other importantitems were also included in the list ofobjectives: • achieving dynamicperformance, fuel economy, noisemanagement and quality typical ofBMW;• having a flexible concept capable offulfilling future emissions standards;• creating a benchmark product in termsof its package, weight and cost ofownership;
Page 1: IFET COLLEGE OF ENGINEERINGDEPARTME
Page 5 and 6: as nature - always in line with cur
Page 7 and 8: eccentric shaft, an electric motor
Page 9 and 10: stiff and robust, minimizing anyvib
Page 11 and 12: the most advanced direct-injection
Page 13 and 14: Compact. In turn, the first represe

valvetronic engine technology - IFET College of Engineering

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?