Validation of Clicking-type Noise and Vibration in Automotive HVAC System

Abstract

In this study, the characteristics of clicking-type noise and vibration occurring in the automotive heating, ventilation and air conditional (HVAC) systems are investigated. A lab-scale model of HVAC system is developed, and validation is carried out with a vehicle system. A fixed blower speed of 1 (at an airflow of 2.53 m/s) with alternated air conditional (AC) was implied in this study. Three different sensors namely as tachometer, accelerometer, and microphone were used to measure and prove the existing noise in the HVAC system. The study inferred that the compressor contributed significantly to the total vibration and noise in the HVAC system. Other components such as AC pipe, evaporator, and thermal expansion valve (TXV) also contributed to a slight extent. The clicking noise was observed in the operating frequency range of 200 ~ 300 Hz. This noise and vibration issues are partly influenced by the running conditions of the AC and the effect was significant when the AC was turned on. The validation of the findings in the model shows a good agreement with the results obtained in the vehicle system, whereby the clicking noise and vibration can be observed at a similar frequency range.

Archives of Acoustics

“…From the figures, it can be observed that both AC pipe and compressor have the significant peaks of natural frequencies between 50-250 Hz, whereby the highest peak occurred at 148 Hz and 85 Hz for AC pipe and compressor, respectively. This frequency range is corresponded to the region of humming noise and vibration determined by (Satar et al, 2019;2021b). This subsequently will create a resonance to the AC pipe and neighbouring HVAC components while increasing the engine speed during the operation condition.…”

“…When the compressor is engaged, the HVAC is running smoothly and reduces the overall system vibration. This also supported by the flow of refrigerant fluids which results in an increment of the mass and stiffness of the affected HVAC components (Satar et al, 2021b).…”

Archives of Acoustics

“…The method has been applied in complex air conditional (AC) assemblies. In the experimental approach, it is common to use a microphone to record the sound from vibrating component and compare it with the noise of the models (Wiart et (Satar et al, 2018) were used to correlate the data from the microphone. However, studies involved sound diagnosis are still limited in the literature.…”

“…Another noise that originated from the HVAC system is a knocking noise. It is generated when the mounting bolts of any HVAC components system were loosened (Satar et al, 2018). Based on the study by Sharma et al (2012), knocking can lead to noise accompanied by a thermostat malfunction and this also related to the humming noise characteristics in the study that has been conducted on the vehicle system by Satar et al (2018).…”

“…It is generated when the mounting bolts of any HVAC components system were loosened (Satar et al, 2018). Based on the study by Sharma et al (2012), knocking can lead to noise accompanied by a thermostat malfunction and this also related to the humming noise characteristics in the study that has been conducted on the vehicle system by Satar et al (2018). They have successfully characterised the noise at different operating conditions such as different blower speeds and AC settings.…”