Abstract: The present invention provides a mechanism and method of launching a vehicle using a conventional automatic shifting power transmission. By slipping a first gear reaction clutch during a launch, an efficient hydrodynamic fluid drive with a low stall speed may be used with negligible impact on launch performance. The reduced stall speed characteristic of the hydrodynamic drive may provide improved efficiency in other vehicle operating regions.

Abstract: A torque converter assembly is provided, which includes an impeller, a turbine, and a stator. The impeller and the turbine each have a plurality of passages for directing fluid. The inlet and outlet of each passage are larger in cross-sectional area than the middle portion of the passage, located between the inlet and outlet. This structure reduces energy losses, which typically occur near the midpoint of the passage due to flow separation. Additionally, reducing the flow area of the torus of the impeller and turbine permits an overall thinner torque converter, which is preferred for engine packaging purposes. The stator includes a core, a shell, and a plurality of stator blades. One end of each stator blade is fixed to the core, while the opposite end is fixed to the shell. Each stator blade has a mean camber line and an associated mean camber line length. The maximum thickness of each stator blade is approximately 20% of the mean camber line length.