Torque Converter, Function
Due to the effect of centrifugal force, the blades of the impeller (P) pump the oil outwards to the turbine wheel (T), causing it to rotate. The turbine wheel blades direct the oil onto the blades of the stator, which in turn push the oil back to the impeller (P) (arrow). This diversion at the stator (L), which is supported against the transmission housing via the freewheel, produces an increase in torque. At the maximum speed difference between the impeller (P) and the turbine wheel (T), the torque conversion achieves its maximum value at a factor of 1.8 to 2.0, dropping to a torque ratio of 1:1 as the speeds converge. From this operating state onwards, also referred to as the coupling point, the stator (L) rotates with the impeller (P) and the turbine wheel (T). Efficiencies of up to approximately 98% are achieved in the coupling range. See Fig 1.
The oil in the torque converter is constantly being replaced so that the heat produced in the operating phase can be dissipated via the transmission oil cooler.