When measuring, the microphone is placed 10mm away from the wall of the compression enclosure. The compressor height is divided into 6 layers on average, and 10 measuring points are distributed on each layer (that is, 7 and 3 are respectively distributed on the compressor casing and the reservoir cylinder). The arrangement of the measuring points is as shown in (a). The near sound field distribution of the layer near the middle of the lower cylinder of the liquid reservoir is as shown in (b) (the center of the compressor vent hole is the origin O, and the line connecting the center of the suction and exhaust holes is the X axis).

From the near-field noise distribution, it can be seen that the compression (a) near-field distribution point distribution (b) compressor noise near-field distribution has the largest noise on the reservoir side of the near-field tester, indicating that the accumulator is a major compressor. Sounding parts. Therefore, the optimal design of the accumulator structure can improve its muffling performance, reduce the overall noise of the compressor, and improve the structure of the accumulator. The distance between the suction pipe and the filter pad is adjusted. The basic structure is an expansion type muffler, which is a sudden expansion or contraction of the pipe section, so that the noise propagating along the pipe is reflected back to the sound source at the sudden change, thereby achieving the purpose of eliminating the sound. Single-cavity or double-cavity is commonly used in controlling intake and exhaust airflow noise, and the accumulator is a single-cavity inner cannula expansion muffler (as shown), so the noise reduction of the inner-tube single-chamber expansion muffler is introduced here. Calculation.

The muffler's muffling amount mainly depends on the expansion ratio m, but the muffling amount changes periodically with sin2kl1. When the length l1 of the expansion chamber increases, the maximum muffling frequency fn=(2n+1)c/4l1 of the muffler moves toward the low frequency. If the internal structure of the accumulator is not properly designed, not only can the noise of the corresponding frequency be reduced, but also secondary noise may be generated, thereby increasing the overall noise of the compressor. In the design, according to the muffler characteristics of the muffler and the frequency corresponding to the airflow noise in the accumulator, combined with the theoretical calculation, the length of the accumulator and the spacing between the internal elbow and the filter pad are preliminarily determined. After many experiments, the spacing of the corresponding parts is continuously adjusted, and the structural parameters of the optimal noise reduction effect are obtained, thereby effectively reducing the peak value of the frequency corresponding to the intake noise.

Increasing the thickness of the reservoir housing The reservoir also functions as a sound insulator in addition to separating the gas and liquid. The size of the structural sound insulation TL is related to the areal density and noise frequency of the material, so that the sound insulation effect can be improved by changing the mass per unit area of ​​the material. The higher the noise frequency, the larger the sound insulation TL, the empirical formula is TL=18lgP+12lgf-25 where: p structure unit area weight (kg/m2); f noise frequency (Hz).

In order to improve the sound insulation effect of the liquid reservoir and enhance its rigidity, the thickness of the reservoir body is increased from 1.5 mm to 2.0 mm. This not only reduces the transmission ability of the airflow noise, but also eliminates the regeneration noise. In addition, in order to avoid noise generated by the vibration of the bent pipe, the partition is fixed near the middle end of the bent pipe. At the same time, in order to reduce the vibration transmitted to the accumulator by the compressor casing, the compressor and the accumulator are fixedly coupled by an elastic pressure plate, and a rubber strip is added between the pressure plate and the accumulator to increase the elastic contact thereof. The rigid joint of the bracket directly spot welding on the reservoir is better.

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