Noise and vibration of passenger car thermal systems are some of the major contributing factors to customer satisfaction. The optimization of these characteristics requires an integrated approach involving detailed analysis, simulation and testing. This paper describes selected noise, vibration and harshness (NVH) issues, discusses solutions and provides examples of its successful applications for thermal systems in passenger cars.
The major components of a thermal system include condenser, radiator and fan module, main HVAC module, auxiliary HVAC module as well as air conditioning (AC) additional components such as lines, seals, hoses and vibration isolators. All components can contribute individually or as a system to the noise problem.
Significant sound level reductions and improvements in sound quality have been achieved applying detailed analysis, Computer Aided Engineering (CAE) tools, and advanced testing methods. Examples presented in this paper include an auxiliary HVAC module of half the size and equivalent overall sound level compared to past designs, considerable reductions in objectionable noises such as aspirator and defrost bleed noises, and improvements in vibration through optimized placement of stiffening members.