| As the powerful component of pneumatic system,air compressor has a broad application prospect in various industries of national economy,among which the piston miniature medium pressure air compressor in the military,civilian and other advanced equipment field has an indispensable position.In order to reduce the volume of air compressors and improve the cleanliness of gas,miniaturization and oil-free have become the development trends of air compressors.In addition,the reliability of pistons and piston rings,key components of air compressors,under the harsh conditions of high temperature and pressure is also increasing attention.Therefore,this paper focuses on the miniaturization and oil-free design of air compressor and thermal coupling simulation analysis and structural optimization of key components to provide reference for the optimized design of miniature medium pressure air compressor.The main research work of this paper is as follows.Firstly,according to the analysis of the requirements of the miniature medium pressure air compressor,the overall structure scheme of the miniature medium pressure air compressor is given,and the structural form,the number of stages,the lubrication method and the drive method were determined through the study.The overall structure adopts single-cylinder two-stage compressor to meet the requirements of small volume design.The piston ring material is PTFE,which has great self-lubricating performance and meets the requirements of clean air discharge design.In addition,the main parameters were determined based on thermodynamic and dynamic calculations.Secondly,thermal coupling study of piston and piston ring.The compression working condition is used as the mechanical load boundary condition and thermal load boundary condition of the piston and piston ring.Based on ANSYS Workbench simulation software,the steady-state temperature field simulation analysis of piston and piston ring was carried out,and the results of piston and piston ring temperature distribution were obtained.The thermal coupling simulation of the piston and piston ring using the sequential coupling method is also used to derive the stress and deformation distribution of the key components,to determine their danger zones,which can provide the basis for structural optimization of the piston ring.Thirdly,the piston ring structure optimization based on response surface method.Based on the piston ring simulation analysis,the sensitivity analysis of its radius clearance,opening clearance,opening clearance angle,axial height,inner diameter and radial thickness,it was concluded that the opening clearance angle and inner diameter have a greater influence on the piston ring stress and deformation.The DOE experimental design based on the best space-filling design method was used to establish the kriging response surface model of piston ring opening clearance angle,internal diameter versus stress and deformation.By evaluating the response surface,the results show that the response surface model is reliable.The multi-objective genetic algorithm(MOGA)in ANSYS Workbench was used to solve the response surface model with the maximum stress and maximum deformation of the piston ring as the optimization objectives to obtain the best combination of design parameters for the piston ring.The optimized piston ring was re-modeled and simulated,and it was found that the stress of the optimized piston ring was reduced by 17.8%,and the deformation was also reduced by 4.6%.Finally,engineering tests of the miniature medium pressure air compressor.By using the PTFE piston rings,the compressor can be lubricated without oil,thereby satisfying the design requirements for a clean air discharge.The air displacement and motor power of the miniature medium pressure air compressor are tested by using tank filling method,and the final air compressor exhaust temperature was tested by upgraded test equipment.In addition,the air compressor was tested for 500 hours of trouble-free operation,and the test data all met the design requirements. |
