Torque Converter

(c) Oil Flow Patterns
(1) To assist us in understanding hydraulic torque multiplication, let us consider three terms. First, Kinetic Energy : Energy opposed by oil in motion. Second, Rotary Flow: The Flow of oil around the outer circumference in the converter. Third, Vortex Flow: The Flow of oil across the converter. Third, Vortex Flow : The flow of oil across the converter.
(2) Kinetic energy
The multiplication of input torque results from the kinetic energy imparted to the oil by the pump (impeller) plus the kinetic energy entering the pump from the stator. The more the turbine resists turning, the greater the velocity of the vortex flow of oil circulating in the converter, and the greater the torque multiplication. The less the turbine resists turning, the less the velocity of the vortex flow of oil in the converter and the less the torque multiplication.
(3) Rotary and vortex flow
The instant the torque converter impeller, which is driven by the engine flywheel, starts rotating, the oil spins around with it. This movement of oil is rotary flow (Figure 11). The converter turbine, connected to the load, resists turning as the oil strikes its blades. Because of this resistance, and because of the shape of the blades within the converter elements, the oil takes a second path of travel cross-wise. This second path is called vortex flow (Figure 12). The greater the load resistance transmitted by the turbine, the greater will be the vortex flow.
(d) Principle of Operation
The torque converter provides varying drive ratios between the driving member (impeller) and the driven member (turbine). This is accomplished by using curved vanes in both the driving and driven member, and by using one or more extra members. The extra members act to reduce the splashing effect mentioned before in paragraph 2b (4). Figure 13 shows the curvature of the vane in the torque converter members.
(e) Power Flow
The impeller (Figure 13 (1) is driven by the engine. The turbine (Figure 13 (3) is attached to the converter output shaft. The stator (Figure 13 (2) is supported between the impeller and turbine and can either be held from rotating by being mounted rigidly on a fixed support, or mounted in a one way clutch which permits it to turn free when the driving and driven members are both turning at about the same speed. The impeller is driven by the engine; the turbine, connected to the output shaft rotating free (no mechanical connection to the impeller or stator); the stator is positioned between the turbine and impeller and directs the flow of oil between the two units.