VANOS is a

variable valve timing In internal combustion engines, variable valve timing (VVT) is the process of altering the timing of a valve lift event, and is often used to improve performance, fuel economy or emissions. It is increasingly being used in combination with varia ...

system used by BMW on various automotive

petrol engine A petrol engine (gasoline engine in American English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends (such as ''E ...

s since 1992. The name is an abbreviation of the German words for ''variable camshaft timing'' (german: variable Nockenwellensteuerung). The initial version (retrospectively renamed "single VANOS") was solely used on the intake camshaft, while the later "double VANOS" systems are used on intake and exhaust camshafts. Since 2001, VANOS is often used in conjunction with the

valvetronic The Valvetronic system is a BMW variable valve lift system which, in combination with VANOS, allows infinite adjustment of the intake valve timing and duration. The system claims to improve fuel economy and emissions, and negates the need for ...

variable valve lift system.

Operation

VANOS is a

variator A variator is a device that can change its parameters, or can change parameters of other devices. Often a variator is a mechanical power transmission device that can change its gear ratio continuously (rather than in steps). Examples * Beier v ...

system that varies the timing of the

valves A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fitting ...

by moving the position of the

camshaft A camshaft is a shaft that contains a row of pointed cams, in order to convert rotational motion to reciprocating motion. Camshafts are used in piston engines (to operate the intake and exhaust valves), mechanically controlled ignition systems ...

s in relation to the drive gear. The relative timing between inlet and exhaust valves is changed. At lower engine speeds, the position of the camshaft is moved so the valves are opened later, as this improves idling quality and smooth power development. As the engine speed increases, the valves are opened earlier: this enhances torque, reduces fuel consumption and lowers emissions. At high engine speeds, the valves are opened later again, because this allows full power delivery.

Single VANOS

The first-generation ''single VANOS'' system adjusts the timing of the intake camshaft to one of two positions — e.g. the camshaft is advanced at certain engine speeds. VANOS was first introduced in 1992 on the

BMW M50 The BMW M50 is a straight-6 DOHC petrol engine which was produced from 1990 to 1996. It was released in the E34 520i and 525i, to replace the M20 engine. In September 1992, the M50 was upgraded to the M50TU ("technical update"), which was BMW ...

engine used in 3 and 5 Series. In 1998 single infinitely variable VANOS was introduced on the

BMW M62 BMW M62 is a naturally aspirated V8 petrol engine which was produced from 1995 to 2005. A successor to the BMW M60, the M62 features an aluminium engine block and a single row timing chain. In 1998, a Technical Update included VANOS (variable va ...

V8 engine.

Double VANOS

The second-generation ''double VANOS'' system adjusts the timing of the intake and exhaust camshafts with continuously variable adjustment, based on engine speed and throttle opening. The first double VANOS system appeared on the S50B32 engine in 1996.

References

{{BMW Variable valve timing BMW

Operation

Single VANOS

Double VANOS

See also

References