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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.

In recent years, engines equipped with idle reduction system for fuel saving have been increased in Europe and Japan. Because of the start-stop frequency increase, correspondingly crankshaft and engine bearing contacts also increase. The friction between shaft and bearing is significant to reduce fuel consumption, and besides it, engine bearing wear tends to increase. Therefore, lower friction with small wear engine bearings are expected. In this paper, new developed engine bearing with solid lubricant overlay and its frictional and wear properties are reported (1). As experimental result, a bearing with MoS2 solid lubricant contained polyamide-imide resin coated overlay proved 40% less coefficient of friction, 25% less starting torque and 65% less bearing wear against conventional aluminum alloy bimetal bearing without overlay under close to the start-stop lubrication conditions by testers. Also diesel engine bench test proved less FMEP.