Theoretical analysis of the fluid flow in a torque converter is not easy because it is a three-dimensional and very complicated problem.
A new flow visualization method applicable to oil flow, namely a liquid-resin film method, was developed to observe the fluid flow in a torque converter.
The existence of cross, swirl, reverse and separated flow in torque converters was made clear by this method, and it was clarified that the existence of these kinds of flow resulted in depressing torque converter efficiency.
Additionally, the flow pattern in a torque converter was predicted theoretically by estimating the pressure distribution in it.
An elliptical torque converter with high efficiency was developed by flow visualization and theoretical consideration.