The Research On Characteristics And Measurement Method Of Micro Muffler

The noise of refrigerator is one of the important indicators to measure the quality of refrigerators. The compressor is the main source of noise, which has a great impact on the noise level of whole refrigerator. Whether the performance of compressor muffler is good or bad is directly related to the noise level of the compressor, the sound transmission loss of muffler is an important parameter to evaluate the performance of the muffler. Therefore, a measurement system about sound transmission loss of Micro Muffle is designed in this paper for accurately determining the performance of micro muffler, which has great significance on micro muffler design and selection.This paper studies evaluation and measurement method of micro muffler, summarizes four measurement methods of muffler sound d transmission loss, analyzes its measuring principle and measuring steps, then summarizes the advantages and disadvantages of four measurement methods, and concludes the applicable conditions of each method. By contrast, this paper uses transfer matrix method.For hardware design, according to Chinese national standard, this paper designs an impedance tube for different frequency bands, determined the parameters of impedance tube such as wall thickness, microphone position, microphone spacing, specimen tube, bracket and speaker etc.For software design, according to transfer matrix method and LabVIEW software, design transmission loss measurement system of micro muffler. The system realizes writing program modules such as signal generation, microphone calibration, data acquisition and disposition. Therefore, accurately and quickly measuring the transmission loss of micro muffler is achieved.Under wide broadband sound source condition, the measurement results are compared with the numerical simulation, there is little difference among the results, and the sound transmission loss curve is consistent with the trend in the same frequency band, indicating that the system is accurate and effectiveFinally, the sound transmission loss measurement error is discussed. Under the conditions of different microphone spacing, by contrast, using the system, analyze and discuss influence of the microphone spacing on the measurement results, while discussing the effect of average mode, system frequency resolution and spectral analysis number on measurement error.