Recent advances in engine air cleaners design and evaluation

The development of engine air cleaners is based on filter performance requirements, engine operational environment, available space, filter media properties, and filter element technology. The design process includes analyses of theoretical and empirical models describing precleaner and filter media separation/filtration performance and airflow in filter housings and through filter elements. Filter media are selected based upon these. models and simplified laboratory tests. Since many new motor vehicle designs offer extremely limited space for an engine air induction system, this paper concentrates on new reduced-volume filters, including direct-flow fluted and pleated compact engine air filters. The grawimetric method is still commonly used in engine air filtration technology for air cleaner, filter element, and filter media testing. However a new test method for fractional efficiency measurements is in the final development stage. The paper discusses this new method and provides data on filter grawimetric and fuctional efficiencies.