valvetronic engine technology - IFET College of Engineering
valvetronic engine technology - IFET College of Engineering
valvetronic engine technology - IFET College of Engineering
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eccentric shaft, an electric motor andseveral intermediate rocker arms, whichin turn activates the opening and closing<strong>of</strong> valves. If the rocker arms pushdeeper, the intake valves will have ahigher lift, and vice-versa. Thus,Valvetronic has the ability to get deep,long ventilation (large valve lift) andflat, short ventilation (short valve lift),depending on the demands placed on the<strong>engine</strong>. intake valve with <strong>valvetronic</strong>. the fuel/air mixture is controlled by avariable valve lift, without a throttle plate.Cylinder heads with Valvetronic use anextra set <strong>of</strong> rocker arms, calledintermediate arms (lift scaler),positioned between the valve stem andthe camshaft. These intermediate armsare able to pivot on a central point, bymeans <strong>of</strong> an extra, electronicly actuatedcamshaft. This movement alone, withoutany movement <strong>of</strong> the intake camshaft,can open or close the intake valves.The Valvetronic system is basedon BMW's established double VANOSsystem, which steplessly varies thetiming <strong>of</strong> both the inlet and exhaustcams. However, the Valvetronic systemadds variable valve lift to the inlet cam,achieved by the use <strong>of</strong> a lever positionedbetween the camshaft and the inletvalves. Valvetronic varies the timing andthe lift <strong>of</strong> the intake valves. TheValvetronic system has a conventionalintake cam, but it also uses a secondaryeccentric shaft with a series <strong>of</strong> levers androller followers, activated by a steppermotor. Based on signals formerly takenmechanically from the accelerator pedal,the stepper motor changes the phase <strong>of</strong>the eccentric cam, modifying the action<strong>of</strong> the intake valves. An additionaleccentric shaft alters the lever's distancefrom the camshaft, with the eccentric'sposition determined by a worm drivefrom an electric motor. The position <strong>of</strong>the lever converts the cam action into asmaller or larger valve lift, as requestedby the <strong>engine</strong> management system.