| Because of its advantages of safety,energy saving and high efficiency,the electric scroll compressor is widely used in air conditioning system of new energy vehicles.The noise of the electric scroll compressor plays an important role in the noise contribution of new energy vehicles.However,the vibration reduction and noise reduction of the electric scroll compressor is difficult because of its unique structure and special working mode.The noise of the electric scroll compressor is divided into three categories: mechanical noise,electromagnetic noise and pneumatic noise.The development of modern mechanical vibration dynamic balance technology reduces the mechanical noise,which makes the electromagnetic noise of the motor more prominent.At present,there is no qualitative and quantitative research on the aerodynamic noise of the electric scroll compressor.Therefore,this paper mainly analyzes the noise reduction of electromagnetic noise and pneumatic noise.Firstly,the research of electromagnetic noise,according to the existing products,analyzes the winding mode,and then establishes the 3D solid model of stator and rotor by rmxprt.Then the model is introduced into Maxwell to calculate the radial electromagnetic force located in the stator tooth.According to the different ways of its generation,the radial electromagnetic force is divided into three categories.Then the data are coupled to the stator teeth.The multi speed parametric scanning analysis is carried out to obtain the equivalent sound power radiation waterfall diagram and far-field noise diagram,Finally,the vibration data of prototype and original product are compared by experiments,and it is found that increasing air gap is better for improving noise reduction of V-type radial rotor motor.Secondly,in terms of aerodynamic noise,the scroll disk profile is drawn by using the involute of the circle according to the existing products,and the tooth head profile is modified by using the perfect meshing profile(PMP)profile,and the 3D model is established to extract the fluid field.Combined with the three laws of fluid motion,the paper uses CFD software FLUENT to write the motion function equation program of the boundary of the moving scroll plate by user defined functions(UDF),and makes scale adaptive simulation of the working process of the electric scroll compressor,and finally obtains the specific flow field information of the compressed gas body in the working cavity.Based on the accurate solution of the flow information of the flow field in the vortex compressor,combined with the acoustic analogy method based on the FW-H equation,the sound propagation is mainly due to the compressibility of the fluid,so that the density fluctuation is regarded as the acoustic quantity,The noise curve of the air flow pulsation at the exhaust port of the electric compressor is drawn by using the fast Fourier transform.Based on the calculation of aerodynamic noise,the principle of expansion muffler is used to increase the critical expansion ratio of the muffler by increasing the length of the expansion cavity.The noise vibration test is carried out for the two kinds of muffler before and after the improvement by using the semi anechoic chamber.The measured sound level of A-weighted sound is reduced from 58.03 DB to56.27 d B,which shows that the numerical method is accurate and reliable. |
