How audi valvelift system (AVS) operation of TFSI engines works

For more efficient use of the energy of the burned fuel and, accordingly, its economy (from 7 to 10%), the guys from Audi introduced a system for changing the degree of opening of the intake valves - Audi Valvelift System (AVS). The system was used on 2.8 and 3.2 V6-FSI engines in 2008. AVS uses cam segments mounted on the camshafts of the intake valves, having the possibility of axial displacement (approx. 7mm). Next to each other are two different cams: one for small and the other for large valve lift stroke. Which cam to use in the work of the system determines depending on the load and torque (<4000 rpm, PCX mode, engine shutdown - small cam). One cylinder has two intake valves that serve a single cam segment.

The cams are shifted by a metal pin, which is installed in the cylinder head perpendicular to the camshafts. The pin is extended by an electromagnet and enters the groove of the cam segment, which has a spiral shape, due to which displacement occurs. At the end of the movement, the electromagnet is de-energized, and the pin is pushed mechanically back, due to the profile of the base of the groove. Fixation of cam segments during shear is carried out using a spring-loaded ball installed in the camshaft.