Operation

OPERATION

The torque converter transmits engine torque to the transmission. When it is not locked up, it transmits the torque by means of oil. When it is locked up, it transmits the torque by means of the lockup piston.


The lockup damper is designed to soften the impact as the torque converter locks up.


The torque converter is a 3-element, single-stage, 2-phase type.

The term single-stage indicates that there is 1 turbine runner (output element). The term 2-phase indicates that the mechanism works as a torque converter when the turbine runner is turning slowly relative to the pump impeller and as a fluid coupling when the turbine runner is turning quickly relative to the pump impeller.






TORQUE CONVERTER NOT LOCKED UP






The torque converter activation pressure is not supplied between the converter front cover and lockup piston via passage (3). The lockup clutch (1) and the plate (2) are therefore disengaged and the lockup function is inactive.


TORQUE CONVERTER LOCKED UP






The torque converter activation pressure is supplied between the converter front cover and lockup piston via passage (3). The lockup clutch (1) and the plate (2) are therefore engaged and the lockup function is active.


TURBINE


As the fluid that was put into motion by the impeller blades strikes the blades of the turbine, some of the energy and rotational force is transferred into the turbine and the input shaft. This causes both of them (turbine and input shaft) to rotate in a clockwise direction following the impeller. As the fluid is leaving the trailing edges of the turbine's blades it continues in a "hindering" direction back toward the impeller. If the fluid is not redirected before it strikes the impeller, it will strike the impeller in such a direction that it would tend to slow it down.


STATOR


Torque multiplication is achieved by locking the stator's one-way clutch to its shaft. Under stall conditions (the turbine is stationary), the oil leaving the turbine blades strikes the face of the stator blades and tries to rotate them in a counterclockwise direction. When this happens the one-way clutch of the stator locks and holds the stator from rotating. With the stator locked, the oil strikes the stator blades and is redirected into a "helping" direction before it enters the impeller. This circulation of oil from impeller to turbine, turbine to stator, and stator to impeller, can produce a maximum torque multiplication of about 2.4:1. As the turbine begins to match the speed of the impeller, the fluid that was hitting the stator in such as way as to cause it to lock-up is no longer doing so. In this condition of operation, the stator begins to free wheel and the converter acts as a fluid coupling.





Stator Operation








TORQUE CONVERTER CLUTCH (TCC)


In a standard torque converter, the impeller and turbine are rotating at about the same speed and the stator is freewheeling, providing no torque multiplication. By applying the turbine's piston and friction material to the front cover, a total converter engagement can be obtained. The result of this engagement is a direct 1:1 mechanical link between the engine and the transmission.


The clutch can be engaged in second, third, fourth, fifth and, sixth gear ranges.