Camshaft Control (CVVT)

Courtesy of VOLVO CARS CORPORATION

Both camshafts can be adjusted by the Engine Control Module (ECM) individually using their separate camshaft reset valve.

The induction camshaft is located in the engine's leading edge (in the travel direction) and the exhaust camshaft in the trailing edge (towards the passenger compartment).

The camshafts are driven by the crankshaft via a timing belt at the front edge of the engine.

When each camshaft is adjusted in the factory, its position is aligned with the crankshaft's position. The camshaft's position at alignment against the crankshaft is called the camshaft's 0-position (basic setting).

At camshaft control (CVVT), the camshaft's 0-position is displaced so that the camshaft's angle position is changed. Thus, opening and closing of the exhaust and inlet valves changes relative to the crankshaft.

By controlling the camshaft's angle position, the engine's performance can be increased, idle quality can be improved, and emissions can be reduced.

The Engine Control Module (ECM) detects the position of the camshafts by comparing the signals from the engine speed (rpm) sensor (crankshaft position) and the camshaft position sensors (camshaft positions). The Engine Control Module (ECM) then controls the angle of the camshaft by controlling the oil flow to the CVVT unit using the reset valve camshaft.