The NVH (noise, vibration, harshness) requirements for automotive HVAC technology (Heating, Ventilation and Air-Conditioning) refer to the low background noise of modern cars. In order to avoid acoustic peculiarities all components of the HVAC system have to be developed and tested under extreme climate conditions. The number of operation parameters to be monitored for a good repeatability generate a high complexity of measurement signals for general vehicle Operation, thermodynamics and acoustics. This paper shows a comprehensive approach for efficient development methods combining real summer and winter testing with test bench measurements. In the beginning the standard climate compressor is introduced with its typical construction as a belt driven axial piston engine with variable stroke. In the thermodynamic context of pressure, temperature and specific enthalpy, the Operation criteria of the circuit are explained, including the critical points concerning NVH. Subsequently two typical scenarios for comfort climate and hot climate are characterized by thermodynamic conditions and NVH phenomena of automotive HVAC components. As the concordant monitoring and controlling at test bench and on-road test is one of the key interests in development process, the relevant parameters, sensors and measurement technologies are listed in an overview combining both scenarios. Based on this, for test bench use three special examples are proposed aiming accurate and efficient handling of test operation. The items concern high pressure controlling of climate system, ODS application with full stroke climate compressor tested at a very early state combustion engine prototype and a cabling setup offering good shielding and well-defined wave impedance for CAN-Bus signals. Afterwards for on-road test under extreme climate conditions, the option for acoustic data storage is proposed in the context of various parameters, which enables identification of acoustic phenomena, directly when detected first-time in order to support early accurate analyses. In this way time limits for prototype definition can benefit from early existing measurement results. Regarding the quality of NVH measurements the supervision by audio studio methods is a well-established way to ensure the up to date status of development. In addition to the high accurate reproduction in a room with decoupled building foundations an option for audio studio implementation inside the car is proposed.
Contributions for efficient development in automotive climate acoustics
2011
20 Seiten, 30 Bilder, 2 Tabellen, 5 Quellen
Aufsatz (Konferenz)
Englisch
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