| In industrial automation products,the vacuum suction system is one of the important ways to realize the vacuum suction and transportation of objects,and the vacuum ejector is the common basic component of the vacuum suction system.The Coanda-effect vacuum ejector used as a vacuum generating element can reduce the number of vacuum suction system components,simplify the control of vacuum suction and vacuum release.It also has advantages in the direct suction of particulate materials,so it has received extensive attention in research,design,and application.However,the maximum vacuum of the Coanda-effect vacuum ejector currently under development is about 52 k Pa,which restricts the improvement of workpiece suction and particle material conveying capabilities.In response to this problem,this paper conducts an in-depth study on the Coanda-effect vacuum ejector.It is hoped that the maximum vacuum can be increased by changing the structure of the key parts,and the suction capacity of the workpiece and the conveying capacity of granular materials can be further improved.To this end,this article has carried out the following main research work.First,a new concept of a Coanda-effect vacuum ejector that deflects the jet angle is put forward for the first time in the research.Based on this new idea,a circular arc-shaped "clawhorn" annular air storage chamber and a matching wall surface adapted to the smooth flow of the incident primary airflow of the deflected jet(oblique shot)attached to the wall are designed.To improve the ease of measuring the width of the jet gap,the structure for the positioning of the end surface of the main cylinder body are conceived,and the overall structure of the oblique jet vacuum ejector is given.Secondly,the influence of different structural parameters on the maximum vacuum in the new oblique jet is obtained by establishing fluid dynamics simulation models under different structural parameters and working conditions and performing a large number of simulations.The simulation results show that changing the jet deflection angle θ can effectively increase the vacuum of the vacuum ejector,and the vacuum is maximum when θ=30°.In addition,the influence of key structural parameters such as jet gap width h,throat diameter d,diffuser tube length L,diffuser cone angle α,and wall surface radius R on the vacuum of the vacuum ejector is obtained through simulation.Then,according to the simulation results,the key structural parameters of the oblique-fired vacuum ejector were determined,and the detailed structure of the new oblique-fired Coanda-effect vacuum ejector was determined.Finally,a test platform was established to test the basic characteristics and comprehensive performance of the oblique jet vacuum ejector.The experiment shows that the influence law of key structural parameters on the vacuum of the vacuum ejector is in good agreement with the simulation results,which verifies the concept and preliminary research work of this subject.The test results also show that the better structural parameters θ=30°,h=0.16 mm,d=10mm,L=50mm,α=3°,R=20mm correspond to the new oblique jet vacuum ejector at a gas supply pressure of 0.5MPa,the maximum vacuum reaches 63.8k Pa,which is about 23% higher than the 52 k Pa maximum vacuum of the ortho-radiation type.After that,the maximum suction capacity of the oblique jet vacuum ejector and the comprehensive characteristics of the suction of particulate materials were tested.The results show that,under the same conditions,the vacuum suction capacity of the oblique-shooting Coanda-effect vacuum ejector can be increased by about 23%,and the suction capacity of particulate materials can be increased by about 2.5 times.These results show that the research of this subject has achieved the goal of increasing the maximum vacuum of the Coanda-effect vacuum ejector,and has application prospects. |
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