V50 L5-2.4L VIN 39 B5244S7 (2005)
Camshaft: Description and Operation
Function
Camshafts, valve system
The camshafts and valves let in the fuel/air mixture for the ignition stage. The camshafts and valves then release the fuel/air mixture after ignition.
Conical valve springs allow smaller shims to be used and reduce the total moving mass. The valve springs operate progressively. This means that there
is little force at the beginning and the end of the closing phase, but considerable force during maximum valve lift.
The camshaft is rotated by the timing belt which is turned by the crankshaft. When the cam lobes on the camshaft press in the valve lifter, the valve is
also pressed in and lets the fuel/air mixture out. A VVT unit on the camshaft can vary the valve timing steplessly using the oil pressure. The function
of the VVT unit is to determine when to open or close the valves (within specific tolerances).
