Marcus Hofmann

Acoustical simulation and evaluation of load-dependent hydraulic engine mounts using two-port description

Hydraulic engine mounts, consisting of an elastomeric part and an additional hydraulic damping mechanism, became generally accepted in the automotive industry within the last decades. For a target sound design of the interior noise of a passenger car, the transfer paths from the engine via the engine mounts into the passenger compartment play an important role. To influence these vibroacoustic paths, the transfer behavior of an engine mount needs to be designed in detail in frequency range and preferably as a function of the load state of the engine. In this paper, several purposeful acoustic lay-out designs of hydraulic engine mounts with load-dependent transmission characteristic are presented. The complex acoustical transfer function of a hydraulic mount has been linearized for several operating points and implemented in a one-dimensional analytical calculation model using 2-port descriptions. The parameters of the model were measured on the components of a modular engine mount. The calculation tool has been used to evaluate different concepts of mounts with load-dependent transmission characteristics. Parameter studies showed high potential of three different concepts which have been build up as prototypes and verified on a test rig.

Investigation of tyre road noise

A pleasant sound based on a low interior noise level is one of the main requirements for passenger cars. Because of the reduction of many single noise sources, tyre road noise is now becoming increasingly important. Manufacturers of luxury cars in particular are asked to accept this challenge. Daimler has developed a systematic method for the investigation of tyre road noise. The target is to identify the main principles of noise transmission in an efficient process.

Untersuchung von Reifenabrollgeräuschen

Ein angenehmer Klang basierend auf einem niedrigen Gerauschniveau ist eine der zentralen Anforderungen an die Eigenschaften eines Pkw. Das Absenken vieler einzelner Gerauschquellen hat dazu gefuhrt, dass Reifenabrollgerausche im Fahrzeuginnenraum an Bedeutung gewinnen. Daimler stellt eine Methode zur systematischen Untersuchung von Reifenabrollgerauschen vor. Ziel ist die Identifikation der Mechanismen der Gerauschubertragung unter Berucksichtigung eines effizienten Vorgehens.