Advances in Filtration in Automatic Lube Oil Filters

In 2006 an automatic lube oil filtration system with an automatic backflushing filter and a centrifuge for diesel locomotives was presented at the ASME Spring Technical Conference [1]. The filter cleans itself continuously and the system can be used instead of conventional disposable paper filters to reduce servicing requirements, improve oil cleanliness and reduce the oil system’s exposure to contaminants. In 2015 at the ASME Fall Technical Conference, a development of the system was presented that introduced an electric pump to boost both centrifuge and automatic filter performance at lower engine speeds, as seen during locomotive idling or coasting. The next development addresses the automatic filter mesh, something that has not improved substantially over the last 20 years. The main challenge with improving the mesh for a backflushing filter has been balancing the filtration grade with self-cleaning performance. By going to a finer mesh that catches ever smaller particles, the filter element tends to become more difficult to backflush. For a given wire diameter the free flow area also decreases when the openings become smaller, reducing the maximum mesh loading. Reducing the diameter of the wire used increases the free flow area, but makes the mesh more fragile and difficult to weld. A recent advancement in the mesh design now allows the automatic filter to filter the oil to a much finer degree than was previously possible while maintaining high self-cleaning performance. The filtration performance was evaluated by using the multi-pass method according to ISO 16889, while the backflushing performance was evaluated on our in-house test stand. Currently these elements are being field tested. Being able to filter and separate much smaller particles is expected to reduce long term engine wear and, in certain cases, improve oil life.