tire type BMW 745i 2004 E65 N62B44 Engine Workshop Manual

Downloaded from www.Manualslib.com manuals search engine Valvetronic
Over the entire speed and load range, the gasoline engine needs a combustible fuel-air
mixture within the ideal ratio (Lambda = 1). The mixture quantity must be altered to vary the
speed and output. This variation is effected by the throttle valve. The mixture, which falls
within the narrow range of Lambda = 1, is formed outside the combustion chamber using
the fuel injection system (external mixture formation).
The mixture control is influenced by the throttle valve and is not optimal in all the different
load ranges. This is particularly true in the idle to part-load ranges, since the throttle valve
is only opened slightly in these ranges. The consequences are less than optimal cylinder
filling, torque and increased fuel consumption.
Technical measures were previously introduced; such as the optimization of air/fuel mixing,
improved valve overlap, introduction of DISA and the steady improvement of mixture con-
trol all depend on the throttle valve. This is where the new completely unique Valvetronic
design comes in.
The Valvetronic system simultaneously varies the valve opening time and the valve opening
lift between 0.3 mm and 9.85 mm, according to engine speed and load. This means that
the air/fuel mixture volume is controlled according to engine requirements. This type of mix-
ture and volume control makes the typical throttle valve control unnecessary.
23
N62 Engine