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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 (ΔTj) is in inverse proportion to oil flow (Qj),tests resulting in a single curve expressed by ΔTj = E1/Qj + E2, that the critical oil flow (Qc) varies according to Qc = Const. • E1, and that connecting rod rigidity greatly influences the oil flow (specifically, the greater the rigidity, the less oil).

In a common rail type fuel injection system installed in recent diesel engines, a supply pump is needed to accumulate high pressure fuel. In this supply pump, a bushing is used for the outer cam system. The bushing is lubricated by diesel fuel with relatively low viscosity and unit load of the bushing is higher. Therefore, lubricating film thickness of the bushing is extremely thin. In order to ensure the bushing function under such severe sliding conditions, the bushing is required higher seizure resistance and higher fatigue resistance. Conventionally, lead bronze alloys are applied for the bushing material. We developed a new high performance copper alloy material without lead, which is one of substances of environmental concern. The newly developed bushing contains bismuth instead of lead for tribological component.

This paper presents the development of the new conceptual copper alloy bearings in diesel engines for achieving longer life under higher load. The new concept utilizes a copper based lining as the main sliding part, which has a higher seizure resistance than conventional lead bronze, and makes the overlay as thin as 5m in order to ease the initial running-inFor this development, we selected two additives for the copper to get a higher seizure resistance, one being silver, and the other is tin. These additives will lead to a higher bearing performance.

To meet the requirement for higher performance engine bearings, the microgrooved bearings, that is the plain bearings with shallow circumferential grooves, have been developed. Recently, the performance of microgrooved bearings obtained experimentally have reported1)2). The authors calculated the bearing performance of the microgrooved bearings by elastohydrodynamic lubrication theory. In this paper, the authors described thecalculation method and the performance of the microgrooved bearings obtained theoretically.