Variable camshaft timing control, VANOS

The variable camshaft timing control has been optimized. This optimization now enables even faster adjustment speeds of the VANOS valve actuators. The optimization has also further reduced susceptibility to dirt contamination.

The camshaft sensor wheel is now 1 component and no longer made of 2 parts. This measure increases the accuracy of production and reduces costs.

The non-return valve with strainer has been integrated in the VANOS solenoid valves. This measure has also enabled a reduction in the number of oil ducts in the cylinder head. Furthermore, the non-return valves have been integrated in the VANOS solenoid valves. Strainers on the VANOS solenoid valve ensure fault-free function and reliably prevent the VANOS solenoid valves from be jammed by dirt particles.

The control of the intake and exhaust camshaft is variable within their maximum adjustment range. Once the correct camshaft position has been reached, the VANOS solenoid valves ensure that the oil volume in the positioning cylinders in both chambers remains constant. This keeps the camshafts in this position. To perform the adjustment, the variable camshaft timing control requires a feedback signal on the current position of the camshaft. Camshaft sensors on the intake and exhaust side record the position of the camshafts. On engine start, the intake camshaft is in the end position ("late"). When the engine is started, the exhaust camshaft is pretensioned by a spring and held in the "advanced" position.

Fig 1: Identifying Intake VANOS Unit Components

Courtesy of BMW OF NORTH AMERICA, INC.

Example N55