Brakes

The climate-acoustic chamber with its flexible conditioning from cold to heat climate offers ideal boundary conditions to realistically load the heating/air conditioning system of a vehicle. With the control of the temperature from -20°C to +50°, the humidity, the sun simulation by means of infrared lamps as well as the vehicle inflow with up to 32 km/h driving wind, a variety of climate zones can be simulated as vehicle environment. In addition to the thermodynamic usability, the design as an acoustic semi-free-field room together with the hydrophobic attenuation of all conditioning components allows the authentic evaluation and measurement of acoustic phenomena. Typical applications include the testing and subjective evaluation of in-vehicle air conditioning compressors, HVAC noise (evaporator hiss) and general transfer path analysis of the refrigeration circuit.

As is well known, multi-channel microphone measurements allow the evaluation of sound propagation at different positions. This allows conclusions to be drawn about different assemblies and their acoustic radiation behavior. However, the spatial resolution when using conventional microphones is limited and the exact assignment of where a sound is actually emitted is often very inaccurate. Here, the use of the acoustic camera offers a practical and fast possibility for the identification of dominant partial sound sources. Using a ring-shaped arrangement of 48 individual microphones (microphone array) and a video camera in the center of the ring, the sound radiation is initially recorded synchronously with the video image data. The analysis of the different propagation times of the sound radiation of individual partial sources allows the directional assignment of their radiation points.

The acoustic development of automotive components benefits significantly from the interaction of testing and simulation. While general experience and analyses of measurements form the basis for new developments, simulation allows the evaluation of components and concepts in advance, independently of time- consuming and cost-intensive hardware. Thus, it is possible to select from several designs, weak points can be identified and avoided at an early stage. Thus, the parallel management of simulation and testing allows a constant mutual optimization - the quality of each hardware construction stage benefits from the previous simulation; likewise, the accuracy of the simulation models can be optimized by comparison with the subsequently available measurement data.