Chain Drive

Chain Drive

Timing drive mechanism with trioval sprockets

Torque must be applied to open the valves on a cylinder. On a V6 engine, the valve on each cylinder bank and camshaft opens three times during every working cycle. As a result, higher forces act on the chain drive every time the valve opens. These forces may cause vibrations in the timing drive mechanism that can be felt at higher speeds in particular.







Technical characteristics of the trioval chain drive

Trioval sprockets are used to drive the camshafts on the Cayenne S Hybrid engine.







Function:

The trioval sprockets are raised in three places and are therefore not perfectly circular. The elevations increase the outer diameter of the sprocket as well as the effect of the lever arm that acts on the valves. When a cam needs to open the valve, the elevations (larger arm) act at exactly the right moment. The extension of the lever arm leads to a reduction in the chain forces and dampens disruptive vibrations.

Advantages:

The lower chain forces reduce friction and also fuel consumption. Furthermore, more cost-effective chains and chain tensioners with identical performance characteristics can be used. A further advantage is the reduction in vibrations, which allows the chains to run more smoothly.







Auxiliary system drive

The engine is fitted with two separate belt drives that power the auxiliary units. Because various auxiliary systems on the Cayenne S Hybrid are powered electrically (air-conditioning compressor, power steering, etc.) and the generator has been replaced with the E-machine, the tensioning force on the two drive belts can be reduced. Belt drive A powers the drive belt for the supercharger via the crankshaft drive sprocket and belt drive B powers the coolant pump.