Research On Clearance Volume Design And Performance Of CoMPact High-pressure Piston Air Compressor Based On Thermal-structure Coupling

The coMPact high-pressure piston air compressor has the advantages of small size,high pressure,high efficiency,sufficient air volume,high reliability,and long life,but it has higher requirements for design and manufacturing.Among them,the design of the clearance volume is related to the overall performance of the air compressor in the actual production process.This paper takes a co MPact high-pressure three-stage piston air compressor as the research object,carries out analysis of thermodynamics,kinematics and dynamics,thermal-structure coupling simulation analysis and first-stage compression clearance volume design,and analysis of fluid characteristics in one-stage compression process with the different clearance volumes and air compressor test research.The main research contents are as follows:(1)On the basis of the working principle of the piston air compressor,the theoretical cycle process and the actual cycle process of the co MPact high pressure piston air compressor are co MPared.According to the structure of the air compressor,the movement relationship between the displacement,velocity,acceleration and crankshaft angle of the first and third stage pistons is calculated.Through dynamic analysis,the gas force,inertial force and friction force of the crank connecting rod motion mechanism during the working cycle are obtained,and the force regular curves of the first and third stage pistons and the main and auxiliary connecting rods are obtained.(2)According to the heat and force conditions of the key components in the assembly dimension chain of the clearance volume under working conditions,the thermal-structure coupling simulation analysis of the crank connecting rod mechanism and the first-stage cylinder is carried out through ANSYS Workbench software.According to the simulation results,the related dimensional chain of the crank connecting rod mechanism,the first-stage cylinder and the first-stage compression clearance volume is analyzed and calculated.The relationship between the distance between the end face of the first stage piston and the end face of the cylinder head and the thickness of the clearance adjustment gasket when the first-stage piston is at the top dead center is derived.Finally,a 2mm clearance adjustment gasket is selected to make that the clearance volume is 2.51cm~3 and the end face distance is 0.092 mm～1.450mm.(3)Fluid simulation and characteristic analysis on the one-stage compression process of the co MPact high-pressure piston air compressor are done.Firstly a first-stage compressed gas model with different clearance volumes are established,and then the compression process is simulated through Fluent software,the changes in gas pressure,velocity and turbulent kinetic energy during the compression process are analyzed,and finally the conclusion is derived through numerical analysis:As the clearance volume in the first-stage compression process increases,the opening lag angle of the exhaust valve increases,the displacement decreases,and the volumetric efficiency decreases.(4)An air compressor performance assessment test platform for air compressor test is self-designed and built.Running-in test,noise test,temperature test and performance test on air compressors with different first-stage compression clearance volume are carried out.The running-in test verifies the feasibility of the clearance volume design based on thermal-structural coupling.The results of the noise test show that the noise is greater with the greater the spindle speed of the air compressor,and the clearance volume has less effect on the noise of the air compressor.The results of the temperature test show that the surface temperature of the air compressor is lower with the larger the clearance volume.The results of the performance test show that the compression efficiency of the whole machine is lower with the larger the clearance volume,which verifies that the different clearance volumes in the numerical analysis have an effect on the influence the displacement and volumetric efficiency of air compressor.