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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.

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.