Valvetronic
Encyclopedia
The Valvetronic system is a variable valve timing
system to offer continuous and precisely variable intake valve lift, from ~0 to 10 mm, and duration. It typically works in conjunction with the independent Double VANOS system that continuously varies the timing (on both intake and exhaust camshaft
s). Valvetronic-equipped engines rely on the amount of valve lift for load control, rather than a butterfly valve
in the intake tract. In other words, in normal driving, the "gas pedal" controls the Valvetronic hardware rather than the throttle plate.
Cylinder heads with Valvetronic use an extra set of rocker arm
s, called intermediate arms (lift scaler), positioned between the valve
stem and the camshaft. These intermediate arms are able to pivot on a central point, by means of an extra, electronically actuated camshaft. This movement alone, without any movement of the intake camshaft, can vary the intake valves' lift from fully open, or maximum power, to almost closed, or idle.
Because the intake valves lift now have the ability to move from almost closed to fully open positions, and everywhere in between, the primary means of controlling engine output is transferred from the throttle plate to the intake valvetrain
. By shortening the duration of the intake instead of throttling, pumping losses are reduced and fuel economy is improved. By reducing the valve lift, asymmetrically on 4-valve engines, swirl is generated in the cylinder, leading to a better air/fuel mixture.
By avoiding a large air reservoir between the throttle and the engine responsiveness can be improved, though it depends on the speed of the electric motor actuating the second camshaft.
However, the throttle plate is not removed, but rather defaults to a fully open position once the engine is running. The throttle will partially close when the engine is first started, to create the initial vacuum needed for certain engine functions, such as emissions control. Once the engine reaches operating speed, a vacuum pump run off the passenger side exhaust camshaft (on the N62 V8, exhaust cam on the N52/K) provides a vacuum source, much as a diesel engine would, and the throttle plate once again goes to the fully open position.
The throttle plate also doubles as an emergency backup, should the Valvetronic system fail. In this case, the engine would enter a "limp home" program, and engine speed would once again be controlled by the throttle plate.
, to further enhance both power and efficiency across the engine speed range. Valvetronic was not coupled to early BMW's N53
, "High Precision Injection" (gasoline direct injection
) technology engines due to lack of room in the cylinder head. New generation 'compact' Valvetronic allows for direct injection to utilized in the N55B30
turbo engine, as seen in the 2010 BMW 5-series Gran Turismo.
Valvetronic was initially used on BMW's mass-market engines, mostly of the naturally aspirated variety such as the BMW N42
i4 engine, N62
V8
, N73
V12
, and N52
straight-6
. However, turbocharged engines introduced in 2009 such as the single-turbo N55
straight-6 and the twin-turbo N74
V12 also make use of Valvetronic.
As of 2010, no high-performance M-series
vehicle uses Valvetronic, instead continuing to utilise multiple throttle-bodied designs. The new F10 M5, however, uses valvetronic technology in lieu of the individual throttles its V10 predecessor once had.
MultiAir
Variable valve timing
In internal combustion engines, variable valve timing , also known as Variable valve actuation , is a generalized term used to describe any mechanism or method that can alter the shape or timing of a valve lift event within an internal combustion engine...
system to offer continuous and precisely variable intake valve lift, from ~0 to 10 mm, and duration. It typically works in conjunction with the independent Double VANOS system that continuously varies the timing (on both intake and exhaust camshaft
Camshaft
A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part.-History:An early cam was built into Hellenistic water-driven automata from the 3rd century BC. The camshaft was later described in Iraq by Al-Jazari in 1206. He employed it as part of his automata,...
s). Valvetronic-equipped engines rely on the amount of valve lift for load control, rather than a butterfly valve
Butterfly valve
A butterfly valve is a valve which can be used for isolating or regulating flow. The closing mechanism takes the form of a disk. Operation is similar to that of a ball valve, which allows for quick shut off. Butterfly valves are generally favored because they are lower in cost to other valve...
in the intake tract. In other words, in normal driving, the "gas pedal" controls the Valvetronic hardware rather than the throttle plate.
Cylinder heads with Valvetronic use an extra set of rocker arm
Rocker arm
Generally referred to within the internal combustion engine of automotive, marine, motorcycle and reciprocating aviation engines, the rocker arm is a reciprocating lever that conveys radial movement from the cam lobe into linear movement at the poppet valve to open it...
s, called intermediate arms (lift scaler), positioned between the valve
Poppet valve
A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide...
stem and the camshaft. These intermediate arms are able to pivot on a central point, by means of an extra, electronically actuated camshaft. This movement alone, without any movement of the intake camshaft, can vary the intake valves' lift from fully open, or maximum power, to almost closed, or idle.
Because the intake valves lift now have the ability to move from almost closed to fully open positions, and everywhere in between, the primary means of controlling engine output is transferred from the throttle plate to the intake valvetrain
Valvetrain
Valvetrain is an all-encompassing term used to describe the mechanisms and parts which control the operation of the valves. A traditional reciprocating internal combustion engine uses valves to control air and fuel flow into and out of the cylinders, facilitating combustion.-Layout:Valvetrain: The...
. By shortening the duration of the intake instead of throttling, pumping losses are reduced and fuel economy is improved. By reducing the valve lift, asymmetrically on 4-valve engines, swirl is generated in the cylinder, leading to a better air/fuel mixture.
By avoiding a large air reservoir between the throttle and the engine responsiveness can be improved, though it depends on the speed of the electric motor actuating the second camshaft.
However, the throttle plate is not removed, but rather defaults to a fully open position once the engine is running. The throttle will partially close when the engine is first started, to create the initial vacuum needed for certain engine functions, such as emissions control. Once the engine reaches operating speed, a vacuum pump run off the passenger side exhaust camshaft (on the N62 V8, exhaust cam on the N52/K) provides a vacuum source, much as a diesel engine would, and the throttle plate once again goes to the fully open position.
The throttle plate also doubles as an emergency backup, should the Valvetronic system fail. In this case, the engine would enter a "limp home" program, and engine speed would once again be controlled by the throttle plate.
History
First introduced by BMW on the 316ti compact in 2001, Valvetronic has since been added to many of BMW's engines. The Valvetronic system is coupled with BMW's proven double-VANOSVANOS
VANOS is an automobile variable valve timing technology developed by BMW in close collaboration with Continental Teves. VANOS varies the timing of the valves by moving the position of the camshafts in relation to the drive gear...
, to further enhance both power and efficiency across the engine speed range. Valvetronic was not coupled to early BMW's N53
BMW N53
The BMW N53 is BMW's 14th generation production straight 6 engine, released in 2007 in the facelifted BMW 5 Series and the BMW 3 Series . It is an improvement on the N52 Naturally Aspirated engine mainly since it has gasoline direct injection technology and can burn stratified...
, "High Precision Injection" (gasoline direct injection
Gasoline direct injection
In internal combustion engines, gasoline direct injection , also known as petrol direct injection or direct petrol injection, is a variant of fuel injection employed in modern two-stroke and four-stroke gasoline engines...
) technology engines due to lack of room in the cylinder head. New generation 'compact' Valvetronic allows for direct injection to utilized in the N55B30
BMW N55
The N55 is a turbocharged straight-6 automobile engine from BMW. It was launched in early 2009 in the new BMW 5-Series Gran Turismo in the BMW 535i GT model...
turbo engine, as seen in the 2010 BMW 5-series Gran Turismo.
Valvetronic was initially used on BMW's mass-market engines, mostly of the naturally aspirated variety such as the BMW N42
BMW N42
The N42 is a series of I4 automobile piston engines from BMW designed in conjunction with MG Rover engineers with the intention of replacing the larger capacities of K series engines used in Rover products. However, this plan was dropped following the sell off in 2000. The series debuted with the...
i4 engine, N62
BMW N62
The N62 is a V8 from BMW, built in Munich, Germany. It has an Alusil aluminum engine block and aluminum DOHC cylinder heads.It uses SFI fuel injection, has 4 valves per cylinder with BMW's double-VANOS and Valvetronic technologies and features fracture-split forged powdered metal connecting...
V8
V8 engine
A V8 engine is a V engine with eight cylinders mounted on the crankcase in two banks of four cylinders, in most cases set at a right angle to each other but sometimes at a narrower angle, with all eight pistons driving a common crankshaft....
, N73
BMW N73
The N73 was a V12 engine from BMW, built in Munich, Germany.The N73 was among the first BMW engines to receive the revolutionary Valvetronic technology, which surprisingly gives it more economical fuel consumption than older non-Valvetronic V8 BMW engines...
V12
V12 engine
A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft....
, and N52
BMW N52
The BMW N52 is a straight-6 engine made by BMW, which debuted in 2004 on the BMW E63 630Ci. The N52 is BMW's 12th generation production straight-6 engine.Its crankcase is made entirely of magnesium and aluminum, a first in the world of engine construction...
straight-6
Straight-6
The straight-six engine or inline-six engine is a six-cylinder internal combustion engine with all six cylinders mounted in a straight line along the crankcase...
. However, turbocharged engines introduced in 2009 such as the single-turbo N55
BMW N55
The N55 is a turbocharged straight-6 automobile engine from BMW. It was launched in early 2009 in the new BMW 5-Series Gran Turismo in the BMW 535i GT model...
straight-6 and the twin-turbo N74
BMW N74
The N74 a V12 engine built by BMW in Munich, Germany. As of 2009 it is the company's flagship engine in the 7-Series, only being offered in the Li long wheelbase variant....
V12 also make use of Valvetronic.
As of 2010, no high-performance M-series
BMW M
BMW M GmbH is a subsidiary of German car manufacturer BMW AG.BMW M, also known as M-Technik or just "M" was initially created to facilitate BMW’s racing program, which was very successful in the 1960s and 1970s...
vehicle uses Valvetronic, instead continuing to utilise multiple throttle-bodied designs. The new F10 M5, however, uses valvetronic technology in lieu of the individual throttles its V10 predecessor once had.
Similar technology
Nissan VVEL, Toyota Valvematic, FiatFiat
FIAT, an acronym for Fabbrica Italiana Automobili Torino , is an Italian automobile manufacturer, engine manufacturer, financial, and industrial group based in Turin in the Italian region of Piedmont. Fiat was founded in 1899 by a group of investors including Giovanni Agnelli...
MultiAir
Multiair
Multiair is an electro-hydraulic variable valve actuation technology controlling air intake in petrol or diesel engines . It is compatible with both naturally aspirated and forced-induction engines....