Oil mist separator with switched impactor

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Stuttgart, Germany, September 2007—The switched impactor from MAHLE used as an oil mist separator can let off quite a bit of steam—and does so without harm to the environment. Because a non-woven insert in the bypass filters out the oil mist. The system has a 20 percent higher efficiency than conventional products.

The new oil mist separator operates without an external drive and is highly efficient. It is a combination of inertial separator and filter media. No maintenance is required because the component is designed to last the service life of the engine.

With the bypass design, the developers at MAHLE achieve optimum efficiency: maximum filtration at minimum pressure loss. Since the flat seat valve of the separator operates as a function of the excess pressure, the flow speed in the impactor nozzle always remains within the defined range. The non-woven insert developed by MAHLE is the only one available on the market that additionally filters gases passing through the bypass.

The filtration efficiency of the oil mist separator from MAHLE is 20 percent higher than comparable competitive products. The impactor is best-in-class in the range of passive systems. Unlike cyclones, it allows a highly variable design. The system can be adapted to arbitrary blow-by volumes due to the number and size of its nozzles.

The extremely high filtration efficiency of the MAHLE oil mist separator is of crucial importance, especially for the steadily rising number of engines with exhaust gas turbochargers, since turbochargers are particularly sensitive to oil residue in the exhaust gas. This makes the new oil mist separator an important milestone to support automobile manufacturers in their efforts to comply with the strict EURO 5 standard.


The MAHLE Group is one of the 30 largest automotive suppliers worldwide. As the leading manufacturer of components and systems for the internal combustion engine and its peripherals, MAHLE is among the top 3 systems suppliers for piston systems, cylinder components, valve train systems, air management systems, and liquid management systems. With more than 40,000 employees in 110 production plants and seven research and development centers, MAHLE generated sales in excess of EUR 4.3 billion (USD 5.8 billion) in 2006.