valvetronic engine technology - IFET College of Engineering

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;