MANN+HUMMEL already offers broadband silencers for the low-pressure side which are equipped with filter material for effective acoustics. Now a material has been successfully developed which is also effective under the hard operating conditions present on the high pressure side.

A hissing roar when starting, a deep growl as the accelerator pedal is pressed and vibrant purring while idling – it's the right sound which makes a car perfect. One undesired disruptive influence here is the high frequency sound of the turbocharger. The development of an innovative broadband silencer by MANN+HUMMEL now helps to avoid disruptive sound on the high-pressure side of the air intake manifold. The new acoustic filter is able to handle the demanding thermal and chemical requirements and can be integrated directly in the charge-air duct.

Broadband silencers with damping chambers work on the resonance principle. The use of a filter material with effective acoustic characteristics is then referred to as the absorption principle. These acoustic filters are characterized by excellent damping over a wider range of higher frequencies and at the same time by a very compact design.

 

The right coating

MANN+HUMMEL already offers compact acoustic filters for the low-pressure side. The filter material with its effective acoustic characteristics which fills out the damping volume of the broadband silencer serves to absorb undesired noise. However, the non-woven fabrics and foams used here are only suitable for low temperatures. The broadband silencers used up to now on the high-pressure side only work according to the resonance principle. Now the experts at MANN+HUMMEL have managed to develop a thermally resistant material using an oleophobic coating which is also resistant to the chemical influence of blow-by gases and oil. The noise-reducing performance of the material is not influenced by the coating. In addition, the acoustic filter does not require more space than the broadband silencers used up to now and convinces with its improved performance to fix the high frequencies issues. Moreover, the acoustic filter offers gain in terms of costs and design flexibility in comparison to current insulation systems.

Simulation cuts costs

In terms of the dampening performance, the developers set a high target. This was a reduction of 20 decibels in the frequency range between three and ten kilohertz. This is a frequency range where conventional broadband silencers function no longer. In order to test the reaction of the new material under environmental conditions in the high-pressure area, the experts first of all designed a simulation tool which in future will ensure an easy and quick layout already in the development stage. This enables a precise technical concept early on to reduce costs and improve competitiveness.