| Scroll compressor is a new type of high-efficiency positive displacement compressor.Compared with other types of compressors,it has small size,compact structure and high reliability.It is widely used in refrigeration,air conditioning,refrigeration and other fields.As an important part of scroll compressor,the rotor system is very important for the safe and stable operation of scroll compressor.The dynamic characteristics of the components of the scroll compressor rotor system are analyzed to provide theoretical and technical support for the optimization of the scroll compressor.In this paper,theoretical analysis and numerical simulation are used to optimize the dynamic balance of the prototype rotor system.The influence of the force,vibration characteristics,natural frequency and bearing stiffness on the critical speed before and after the optimization of the rotor system is compared and analyzed.Firstly,based on the working principle of the scroll compressor,the finite element model of the working area of the balance iron of the prototype is established.The working area of the balance iron is simulated by FLUENT sliding mesh technology,and the resistance moment of the balance iron of the prototype is studied.By analyzing the pressure distribution of the balance iron wall and the velocity cloud diagram and streamline diagram of the auxiliary surface,the balance iron with rounded front and rear ends is proposed.The results show that reducing the differential resistance moment is the key to reduce the total resistance moment,and it is found that the maximum pres sure of the balance iron wall mainly occurs at the left end near the fan-shaped outer edge,and the minimum pressure mainly occurs at the right end near the ring.Reducing the pressure at the fan-shaped outer edge is the key to reducing the differential resistance moment.Compared with the balance iron of the prototype,the total resistance torque of the balance iron with rounded front and rear ends is reduced by 30%～50%.Secondly,based on the dynamic balance theory of rotor system,the physical model and finite element model of rotor system before and after optimization are established,and the stress deformation analysis of rotor system before and after optimization is carried out.The results show that the maximum deformation of the rotor system is at the crank pin of the spindle,and the deformation is also large near the installed balance iron.The maximum stress before and after the optimization of the rotor system is at the position from the root of the main shaft crank pin to the installation of the main bearing.The influence of the optimized balance iron on the stress and deformation of the main shaft of the rotor system is reduced.Finally,based on the mathematical model established by stress deformation analysis,the vibration characteristics of the rotor system before and after optimization are studied,and the first six natural frequencies,modal shapes and critical speeds of the rotor system are extracted.The results show that the first six natural frequencies and critical speed values of the optimized rotor system are improved.When the rotor system speed is increased to 9000 rpm,the rotor system before optimization will resonate,and the optimized rotor system will avoid the resonance region.In order to improve the safety margin of the optimized rotor system at 9000 rpm or higher speed,the influence of bearing stiffness on the critical speed is further studied.The Design Explorer is used to optimize the bearing stiffness in the range of 1.0×10~7N/m～1.0×10~8N/m,and the optimal critical bearing stiffness value to avoid resonance is obtained by response surface optimization. |
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