valvetronic engine technology - IFET College of Engineering

stiff and robust, minimizing anyvibration of other vehicle componentsthe driver would otherwise feel on thesteering wheel, gearshift lever andpedals, and also perceive as a kind ofconsistent humming noise.All ancillaries are bolted directlyto the crankcase without the ratherelaborate supports and attachmentsotherwise required – again an importantcontribution to running smoothness withvibrations reduced to a minimum. Throttle plate is not removedIt is important to note however,that the throttle plate is not removed, butrather defaults to a fully open positiononce the engine is running. The throttlewill partially close when the engine isfirst started, to create the initial vacuumneeded for certain engine functions, suchas emissions control. Once the enginereaches operating speed, a vacuum pumprun off the passenger side exhaustcamshaft (on the N62 V8 only) providesa vacuum source, much as a dieselengine would, and the throttle plate onceagain goes to the fully open position.The throttle plate also doubles as anemergency backup, should theValvetronic system fail. In this case, theengine would enter a "limp home"program, and engine speed would onceagain be controlled by the throttle plate.ADVANTAGES ANDBENEFITS Fuel economy increasedValvetronic offers the customerdirect, immediate benefits, with fuelconsumption and exhaust emissionsdecreasing, but dynamic performanceand the spontaneous response of theengine improving accordingly. Added tothis there is the even higher standard ofrunning smoothness, since the valvesmove only slightly in a preciselycontrolled process.The improvement in fueleconomy ensured by this concept ofthrottle-free engine load management isapproximately 10 per cent in the EUcycle and at least 10 per cent under thetypical driving conditions encounteredby a customer. The basic rule is that fueleconomy versus other concepts increaseswith the driver running the vehicle at