A Study of Oil Flow and Temperature in Journal Bearings

With the recent trend toward increased unit load in engine bearings, problems due to lack of lubrication frequently arise, especially in crankpin bearings. We have previously investigated the influence of shaft and bearing design on the oil flow using the connecting rod in actual use under alternating loads.

In this paper, we investigate the critical value of oil flow at which the Fbearing temperature rises rapidly and the influence of connecting rod rigidity on the oil flow. As a result of these tests, it was discovered that the increase in bearing temperature (ΔT_j) is in inverse proportion to oil flow (Q_j),tests resulting in a single curve expressed by ΔT_j = E₁/Q_j + E₂, that the critical oil flow (Q_c) varies according to Q_c = Const. • E₁, and that connecting rod rigidity greatly influences the oil flow (specifically, the greater the rigidity, the less oil).