Development of high dust capacity, high efficiency engine air filter with nanofibres

Although dust-holding capacity is the primary feature of engine air filters operating in dusty environments, efficiency becomes a major factor when selecting an engine air filter. Inertial separators and high porosity or fibrous prefilters are commonly used to decrease the dust load to the main filter while high efficiency is achieved by utilizing submicron or nanofiber fibers in the main filter. The patented multi-stage filter was designed to achieve ultra-high particle removal efficiency and dust holding capacity, and long life in dusty and on highway environments. The main (final) filter is located downstream of the prefilter. The main filter is made of pleated filter media containing nanofibers with a diameter in the range of 40 – 800 nanometers. The upstream in-line precleaner utilizing flow-through mini cyclones has separation efficiency of 95%. A high dust capacity, high efficiency prefilter can be used instead of the precleaner. The prefilter is made of vertically lapped nonwoven filter media made from synthetic fibers of different materials to fully utilize the tribological effect. The volume of the prefilter is determined by the performance required and space allotted. This paper discusses the filter performance of high dust holding capacity engine air filters. Filter specifications, design and performance are discussed in detail. Performance characteristics of the media and full size filters were determined using on-line particle counters and the gravimetric test method. Initial and final efficiency, and dust loading performance characteristics, are provided.