Determining the Noise Reduction Technology of Inverter Variable Frequency Scroll Compressor

Determination of Excitation Force Inverter Scroll Compressor Noise Reduction Technology Analysis By using modal analysis and acoustic analysis methods, it is found that the pressure and vibration frequency generated by the scroll parts should be avoided as much as possible with the natural frequency of the shaft, which is very effective for noise reduction. of. Based on the analysis and experimental results, this paper finds an improved method to optimize the natural frequency of the shaft to optimize the natural frequency of the entire compressor, including bearings, racks, etc. A variable frequency controlled scroll compressor that reduces the vibration structure of the shaft has been developed.

It is important to reduce the noise in the band and determine the excitation force that exists in this frequency band. It is well known that the vibration of a part associated with a rotating component, the radial magnetic pulling force of the motor, the exhaust pressure vibration, and the like are all considered to be exciting forces for generating compressor vibration. Now we find that the noise in the band is related to the change in working pressure. As shown, the noise is closely related to the high-pressure refrigerant gas discharged from the vortex, so a dynamic pressure time signal is installed as shown. Thus, the wavelet component of one of the time domain frequency analysis methods is used to study the frequency component of the instantaneous dynamic pressure, and it is found that the refrigerant gas at the outlet end of the vortex has a pressure vibration in the wavelength band. Based on the model of the inside of the crankshaft and the space below the motor, a digital acoustic analysis is completed. The results are shown in the figure. There is an acoustic resonance mode inside the band crankshaft. The pressure vibration of the refrigerant gas discharged from the vortex in the band component is amplified by the acoustic resonance mode inside the crankshaft. Since the acoustic resonance frequency is very close to the natural frequency of the first deformation mode of the crankshaft, exhaust pressure vibration is generated under the vibration of the crankshaft vibration, and as a result, the excitation force causes the compressor to vibrate in the rigid body mode.

Optimization of Crankshaft Support Structure First, we used finite element analysis to complete the study of increasing the natural frequency of the first deformation of the crankshaft to reduce its vibration. First use a simplified model to study the extent to which design changes affect natural frequencies. In the simplified model, the crankshaft, including the rotor and balance weight, is considered a single-mass free beam, and the bearing is considered a resilient element to simplify the model. The elastic constant represents the rigidity of the bearing support, and the modal analysis result shown in the figure can be consistent with the analysis result of the simplified model of the first deformation natural frequency of the crankshaft. The design change includes the distance between the main bearing and the lower bearing, the bending stiffness of the crankshaft representing the Young's modulus, the secondary moment representing the section, and the like.