Innovative Flexline solution

The filtration surface area and the inflow area are enhanced thanks to perfect exploitation of the installation space.

When the application is complex, it‘s time for Flexline. The air filter solution from MANN+HUMMEL even fits into very tight installation spaces. Mercedes-Benz is now the first vehicle manufacturer to use the innovative solution in a series application.

The requirements for cars are increasing, also demanding comfort functions for small and compact cars, low emission values, and maximum performance. And as a result the number of components competing for space under the hood is going up. Consequently, installation space is valuable and MANN+HUMMEL with Flexline now exploits the available installation space more efficiently. In contrast to conventional air filter elements, which mostly either have a trapezium shape, are rectangular or have a polygon shape and usually have straight sides, the rounded edges of Flexline filter elements allow excellent design flexibility. This enables completely new shapes. It is therefore possible to efficiently match the filters to the interference contours in the engine compartment and perfectly exploit the available installation space, even when this is very complex.

Increase performance, reduce noise

The innovative air filter system from MANN+HUMMEL is now going into series production for Mercedes-Benz. The vehicle manufacturer is using Flexline for its MFA2 platform (modular front architecture). The air filter system celebrates its premiere in the new A-Class and scores points on several fronts. The filtration surface area and the inflow area are enhanced thanks to perfect exploitation of the installation space. The result is a service life which is increased by approximately 20 percent and also an improved filtration performance. Apart from that, the increase in volume is also advantageous for the acoustics. The damping is improved by roughly 20 percent.

Sophisticated production technology

The air filter system for Mercedes-Benz consists of the air filter and the dirty and clean air ducts. For the acoustic damping the engineers used an over-molded fleece material for the dirty air duct. The porous structure enables the equalization of local pressure peaks to prevent undesired resonance in the line. A lot of development expertise also went into the clean air duct of the diesel application. The clean air duct uses an injection molded bellow from high temperature-resistant plastics instead of a bellow manufactured in a blow molding process. This new innovative feature is a challenge in terms of production engineering, but one which has decisive advantages. Up to now the thinner wall thicknesses which were necessary for the flexibility of the bellows were not compatible with the required collapse robustness at negative pressure. Apart from that, the noise emissions increased with the reduction in the wall thickness. The injection molded bellow, however, is able to manage the balancing act between the required flexibility and stability and is able to reconcile the opposing requirements with regard to decoupling, acoustics and collapse robustness under high temperatures. MANN+HUMMEL has produced injection molded bellows with a thermoplastic elastomer (TPE) in series for a number of years. The special feature of the new bellow for Mercedes-Benz is the use of high temperature resistant polyamide. This pushes the maximum possible application temperatures considerably upwards.

Overmolded inserts for higher quality

MANN+HUMMEL also presented a special solution to Mercedes- Benz for the clean air duct of the gasoline application. In order to reduce the number of welded parts, the engineers designed a bracket in the form of an overmolded insert part. The challenge here was the connection of the hard material of the bracket to the soft base material of the blow molded part. The engineers solved this problem by improving the wall thickness at the corresponding positions and created new geometries which enable a better connection between the components. The removal of the need for a welding process means that customers benefit from two advantages: higher quality and lower costs.