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This paper describes a simulation study of the internal fluid flow of a torque converter. The study was conducted by using the steady-interaction technique to connect the boundaries between neighboring elements. This technique averages the flow variables in the circumferential direction on the connecting boundary surfaces. A comparison of computational results with experimental data gives an estimate of the accuracy in predicting torque converter performance with this method.

The durability of an automatic transmission is greatly affected by its lubrication properties. However, it is difficult to estimate exactly the flow rate of lubricating oil at each part of the automatic transmission, because of its structural complexity under rotating conditions. This paper presents a simple model which can estimate the flow rate of lubricating oil in the automatic transmission. Using this method, we can obtain various information about the lubricating state at every part of the automatic transmission and can help our judgement of whether lubrication is sufficient. To test this model and its results, we tried some experiments and examined the lubricating state by measuring discharge rate of oil. The estimated data is in good agreement with the experimental data. This study should assist in the optimal design of the lubricating system in the automatic transmission.

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.