Application of the Structural Dynamic Modification Method to Reduce the Vibration of the Vehicle HVAC System

Abstract

Heating, ventilating and air conditioning (HVAC) system is one of the major sources for the vehicle noise and vibration, which subsequently contribute to the bad acoustical environment. The components of the HVAC system can produce a significant level of vibration during the operation and contributed to an unwanted noise. As the vibration of HVAC components get worse, it will be transferred to other components and excites the natural frequencies of the HVAC system. Natural frequencies of the components are depending on the mass and stiffness of the HVAC components and the value can been modify using these two parameters. This study is focusing on the specific type of HVAC noise and vibration problem and the counter measure has been perform by implementing the structural dynamic modification (SDM) method to the air conditioning (AC) pipe. The lab-scale of the vehicle HVAC system is set up to represent the actual HVAC system with the real vehicle operation. Noise and vibration of the HVAC system in the system level are measured and compared. From this data, the Dynamic Vibration Absorber (DVA) is designed and applied at the AC pipe of the HVAC system. The result shows that, the natural frequency of the AC pipe can be shifted which resulting a wide effective frequency range of 100-500 Hz. The effect of DVA on the HVAC system is observed during operation whereby a significant vibration attenuation has been achieved for operating frequency range of 100-300 Hz.