Mathematical Model And Performance Research O F Variable Cross Section Scroll Combined By IHV Profile

Compared with traditional compressors,scroll compressor has many advantages such as simple structure,high efficiency,low energy consumption and environmental protection,high reliability.Currently,scroll compressor has been used in automotive air conditioning,transportation,medicine industry,refrigeration and other fields.Improving the compression ratio and working efficiency of scroll comp ressors is not only the key to occupying and expanding its market,but also a s an important research topic facing researchers.Although increasing the number of scroll of the constant cross-section profile can improve the compression ratio,but it also increases the length of the leakage line and affects the efficiency of the compressor.The variable cross-section scroll profile can obtain a higher compression ratio without increasing the number of turns of the scroll and the leakage line length,so it has become a research focus of scroll profile.Based on the involute scroll profile meshing theory,this paper establishes a new type of IHV(circular involute-high-order curve-reducing base circle involute)combined variable cross-section profile mathematical model,and analyzes its comprehensive performance.It provides a theoretical basis for the design of the variable cross-section scroll compressor profile.The research work of the thesis mainly includes the following aspects:Firstly,the geometric model of the IHV scroll profile is built.Based on the involute geometry theory,secondly,establish the generatrix equation of the Involute-High order curve-Variable radii involute(IHV)combined profile.The inner and outer wall profile equations of IHV combined line is established by using the theory of normal equidistant line.The two-dimensional and three-dimensional models of scroll teeth are established in Auto CAD and Solid Works by using computer-aided design methods.Secondly,the volume characteristic analysis and mechanical model establishment of the IHV scroll profile working volume.In view of the geometric model of the IHV combined profile,the theory of the volume of each working volume of the new combined profile is systematically studied.The calculation expression of the working volume and the calculation of the pressure in the working chamber are deduced.With the help of MATLAB analysis,the change rule of volume value and pressure value with the crank angle of the crankshaft is obtained.which is the geometric performance of the scroll compressor of the IHV combined profile.This work laid the foundation for the geomet ric performance analysis and dynamic analysis of the IHV combined profile scroll compressor.The mechanical model was further constructed.With the help of MATLAB software,the gas force change trend is analyzed.Thirdly,the establishment of the equivalent wall thickness model and the comparative study of geometric performance of the IHV scroll profile.According to the theory of the IHV combined profile,the equivalent wall thickness calculation model of the IHV combined line is established.According to the calculation model,the influence of different geometric parameters on the equivalent wall thickness is quantitatively studied.Based on the combined profile of IHV,the influence of variable radius coefficient K on performance is quantitatively analyzed.Under the condition that the base circle radius,the final wrap angle and the tooth height of scroll are set to a certain value.The results show that the length of the radial leakage line of the IHV combined profile is 223 mm shorter than that of the involute of circle,which is reduced by 26.80%,the displacement volume is increased by 5.82%,and the compression ratio is increased by 6.95%.Therefore,the IHV combined profile can effectively shorten the scroll profile,reduce the number of scroll turns,a nd improve the volumetric efficiency of the compressor.Finally,finite element simulation of IHV combined profile scroll tooth and CNC machining.Computer simulation analysis is an effective,feasible and low-cost way.A solid model of the IHV combined profile scroll with different reduction coefficients is established,and its deformation under the gas pressure load and the location of the maximum stress are studied.The results show that the IHV combined profile scroll tooth,when K takes a negative value,the maximum deformation position occurs at t he top of the scroll tooth tip,and the maximum deformation position is at the top of the tooth head when K takes a positive value.The maximum equivalent stress of the IHV combined profile scroll tooth is distributed at the root of the tooth,and the equivalent stress will increase with the increase of the variable radius coefficient K.In the end,the numerical control machining method of the scroll is briefly introduced.