What Is Valvetronic?
The Valvetronic
engine is the world's first engine without a throttle butterfly. Valvetronic allows
the engine to run without a throttle butterfly, the cylinder charge being determined
under part load as a function of the valve-opening period. The intake and outlet
camshafts are driven by variable cam adjustment, BMW’s Vanos technology. A further
advantage of this concept is that it allows worldwide use of the proven three-way
catalyst for emissions management, thus meeting even the strictest emissions standards
in the US.
Innovative technology
was essential in order
to reach the
demanding objectives and functional requirements
desired. However, at the same time, this concept demanded the utmost of the electronic
control and management systems in the engine.
Concept Taking nature
as the role model: human beings also apply the Valvetronic principle.
A comparison
with the human being clearly explains how Valvetronic works: Whenever we are required
to make a great effort, we human beings breathe in a deep and long process of ventilation.
Whenever we need less air, we do not throttle the supply of air by, say, closing
our nose or our mouth, but simply breathe in a shorter, flatter process of ventilation.
In a conventional
combustion engine the throttle butterfly is basically comparable to
a human being keeping his nose or mouth at least partially closed. With its large
valve lift (= deep, long ventilation) and short valve lift (= flat, short process
of ventilation), Valvetronic, on the other hand, is able to breathe in the same
way as nature – always in line with current requirements, without any kind of
throttling effect and therefore with maximum efficiency.
Valvetronic
Technology
Accordingly,
the Valvetronic engine no longer requires a throttle butterfly, which has quite
literally restricted the free ventilation of the internal combustion engine ever
since its invention. Now Valvetronic replaces this conventional function by infinitely
variable intake valve lift, offering a quantum leap in technology quite comparable
to the changeover from the carburetor to fuel injection.
Its most important
feature is that it is able to save at least 10 per cent fuel throughout the entire
operating range relevant to the customer, with a corresponding reduction in exhaust
emissions, regardless of fuel quality. And a further important point is that the
efficient operation of Valvetronic does not require any unusual types and grades
of oil possibly difficult to obtain.
As a result
of these particular features the 85 kW/115bhp BMW 316ti compact with its top speed
of 210 km/h or 125 mph consumes a mere 6.9 liters of premium fuel on 100 kilometers
in the European test cycle, equivalent to 40.9 mpg Imp. This is a significant 0.7
liters less than the former 77 kW/105 bhp compact and well over a liter less
than all competitors in this class.
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