Quantification of the Impacts of Vibration and Flow Fluctuation on Automotive Air Filter Performance, 08-R8058Printer Friendly Version
Inclusive Dates: 04/01/09 Current
Background - Diesel and gasoline internal combustion engines are the primary sources of motive power for automobiles and heavy-duty vehicles. In spite of efforts to find alternatives, these engines will likely retain this role well into the near future. Air induction is a primary process in the operation of an internal combustion engine. A key component of an air induction system is the air cleaner, and more specifically, the air filter element, which protects the engine from becoming dirty and therefore susceptible to wear. The burden placed on the air filter has significantly increased as engine designers have been forced to use more aggressive combustion control strategies and sophisticated after-treatments to meet increasingly stringent emission standards worldwide. Previously, the consequences of wear were mostly related to engine performance and longevity. Now, major concerns include the effects of wear-induced blow-by on downstream emission control components, such as exhaust catalysts and diesel engine particulate traps. It is well known that atmospheric dust particles, especially in highly dusty environments, can contribute significantly to ring and liner wear if the particles are not adequately removed from the incoming air. Furthermore, the build up of deposits on the mass air flow sensor can affect sensitivity and greatly distort performance, resulting in power loss and increased fuel consumption and exhaust emissions.
Modern air filters are expected to meet specific performance values given in industry and government specifications when tested to specific protocols, typically given in organizational standards, and developed and upgraded over time by a committee of interested members. All of these standardized tests evaluate air filter performance under static mechanical conditions that ignore vibration and vibration plus flow fluctuation. As such, despite technical advances in filter design and materials technology, laboratory-proven air cleaner systems and filter elements sometimes perform poorly in real-world environments. This not only demonstrates that there can be a significant difference between testing conditions and working conditions, but also that it is a mistake to assume that laboratory performance will automatically translate directly to performance in the field. To ensure that vehicle propulsion system components are adequately protected from airborne dust, realistic air filter testing must be performed. Vibration and specifically vibration combined with flow fluctuation are important parameters that should not be excluded from such tests as they are now.
Approach - The purpose of this project is to lay the groundwork for correcting this situation. The approach is to (1) conduct laboratory experiments, based on developed vibration data, to examine the extent to which filter performance is affected by vibration and vibration plus simultaneous flow fluctuation, and (2) increase SwRI's knowledge so it can provide enough scientific evidence, if the data corroborate SwRI's contentions, to show the automotive and air filter industries that a closer look at how air filters are specified and tested is warranted.
Accomplishments - Field testing using instrumented vehicles has been conducted to measure vibration spectra encountered by many air filter systems under real-world conditions. These spectra are being used to design the test matrices for combined dust and vibration testing of air filters for specific classes of vehicles (passenger cars, light-duty trucks, and on and off-road heavy duty trucks and construction equipment, for example). In addition, baseline laboratory testing continues on selected air filter systems without vibration and flow fluctuation.