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Most new passenger vehicles on the road today are equipped with a disposable OEM engine intake filter made of cellulose paper or synthetic non-woven media. Engine intake filters have an expected and recommended service life (by OEMs) of approximately 45K to 75K kilometers under normal driving conditions [ref. 2, 3, 4 & 5]. Majority of air filter element manufacturers do not recommend any type of cleaning to be performed on their OEM products. However, cleaning OEM and aftermarket air filters is common for end-customers in areas such as Asia, Middle East and South America. Vehicle owners in some regions would like to service and clean their own air filter elements in an effort to reduce vehicle operating costs. As a result, a number of OEMs selling passenger vehicles in these regions are requesting their suppliers explore solutions and the effects of whether cleaning air filter elements is appropriate for proper engine operation.

Engine air filtration technologies currently used in air induction systems typically utilize pleated paper or felt type air filters. These air filter designs have been used for many years in panels, cylindrical or round (pancake type) type air cleaners. Pleated air filters are specifically designed to be serviceable and hence their performance is inherently limited by vehicle under-hood packaging and manufacturing constraints. Due to these constraints, majority of air cleaner designs are not optimized for engine filtration and air flow management under the hood. Studies show that use of low performing serviceable aftermarket air filters significantly affect the performance and durability of engine air cleaners [9]. High mileage studies confirm that engine durability, service issues, warranty field returns and customer satisfaction was affected by use of aftermarket filter brands.

Filtration performance of EAC is generally measured and evaluated in the laboratory using standard test procedures. Filtration performance and service life expectations of EAC in real world conditions are important for robust designs. Lab measurements may or may not represent real world conditions. However they do provide stable, repeatable, and quick comparative analysis. Initial efficiency is one of the key performance measures of automotive EAC. Typical bench performance levels for three [1,2,5] major air filtration technologies are presented (i.e. initial/overall efficiency, face velocity and dust capacity). The air filter performance effectiveness is also calculated. Typical filtration performance levels are predicted for EAC using paper type air filter elements. These performances are predicted from empirical models developed for various EAC designs using paper media. Service life expectations are also discussed based on field evaluations.

Understanding service life requirements of ‘engine air cleaners’ (EAC) and ‘air induction filters’ (AIF) in real world conditions is important for robust designs. The performances of EAC and AIF are generally measured and evaluated in the lab using standard test procedures which may or may not represent real world conditions. This paper compares some design specifications for light, medium and heavy duty EAC. Various field evaluations are presented to better understand how EAC and AIF perform in real world conditions. Service life expectations are also discussed based on field evaluations. Service life of an EAC is related to its dust/contaminant holding capacity and its restriction rise over time. Evaluating performances of EAC in real world conditions provide meaningful data. Analysis in this paper has been presented mainly for light and medium duty vehicles (passenger cars & light trucks). Heavy duty engine filtration systems are briefly compared and discussed as well.

Automotive engine air intake filters are constantly being challenged to deliver higher filtration performances. The need to protect the engine from abrasive contaminants is ever increasing to achieve longer engine life and improved engine performance. This paper discusses some of the key issues affecting engine filter performance. Currently, the SAE J726 procedure is used to test and evaluate engine air induction filters (AIF). The advantages and limitations of this procedure are discussed. Based on this procedure current engine air filtration technologies are also compared. Engine protection requirements are also discussed relating to contaminant size and concentrations. To design robust engine air induction filters, the particle size and concentration ingested by the engine should be controlled. In addition to the overall mass (gravimetric) efficiency of the filters, the fractional size efficiency of these filters should also be measured.