VANOS is a

variable valve timing Variable valve timing (VVT) is the process of altering the timing of a Poppet valve, valve lift event in an internal combustion engine, and is often used to improve performance, fuel economy or emissions. It is increasingly being used in combina ...

system used by

BMW Bayerische Motoren Werke AG, trading as BMW Group (commonly abbreviated to BMW (), sometimes anglicised as Bavarian Motor Works), is a German multinational manufacturer of vehicles and motorcycles headquartered in Munich, Bavaria, Germany. Th ...

on various automotive

petrol engine A petrol engine (gasoline engine in American and Canadian 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 ...

s since 1992. The name is an abbreviation of the German words for ''variable camshaft timing'' (). 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 variable valve lift system.

Operation

VANOS is a variator system that varies the timing of the valves by moving the position and 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 syst ...

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 BMW 5 Series (E34), E34 520i and 525i, to replace the BMW M20, M20 engine. In September 1992, the M50 was upgraded to the M50TÜ (''Techni ...

engine used in 3 and 5 Series. In 1998 single infinitely variable VANOS was introduced on the BMW M62 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