Research On A New Type Of High Pressure Three Screw Pump And Its Characteristics

Hydraulic pump is a kind of energy conversion device that converts mechanical energy into hydraulic energy.It is widely used in industrial production and daily life as a kind of basic product in mechanical industry.It provides fluid with a certain pressure for the hydraulic system.Therefore,the performance of the hydraulic pump has direct influence on the reliability and stability of the hydraulic system.Three screw pumps belong to positive displacement pumps and have the merits of the compact structure,strong self-suction capacity,small hydraulic pulsation and long service life.Three screw pumps have been widely used in Chemical Industry,Metallurgical Industry and Ship Industry.At the same time,three screw pumps get more and more attention at home and abroad.General three screw pumps are used to provide lube with low pressure load.However,with the expansion of three screw pump applications,more and more occasions need high pressure load.For the lack of theoretical analysis,factories usually simply increase the length of screws to achieve multi-stage series pressurization,which makes the volume too large.And the length increase of screws will add the processing difficulty and reduce the structural strength.Especially,the wear between driven screws and bush will cause destruction of the seal,resulting in leakage.These problems limit the application and development of three screw pumps.In view of the above facts,this paper presents a new type of high pressure three screw pumps with 20 MP load,small volume,high structure strength and high volume efficiency.At the same time,the new design is based on the current production processes and material properties and does not significantly increase the cost and volume.The main contents of this paper are as follows:Firstly,according to <135> three screw pump cycloidal meshing principle and size characteristics,the size of the core parameters has been determined,such as pitch circle diameter,tooth center angle,seal length and so on.Then a high pressure three screw pump model has been established.Secondly,the axial force and radial force distribution have been analyzed in detail.For each section with different stress state,mathematical equations have been established.Then the causes of wear and the calculation of wear position have been done.Thirdly,according to differences of meshing form,the total leakage has been divided into three different parts.For each part,an independent mathematical model has been established and the relationship between leakage and clearance,gesture and revolution speed has been clear.Then,the model of the screw and the flow path in the engagement area has been built using ANSYS and Fluent software.The simulation results have verified the accuracy of the force and leakage calculations.At last,based on actual machining accuracy and material properties,a new type of high pressure three screw pump design has been finished with rational strength and efficiency.The total length is 310 mm,the pump body diameter is 200 mm and the weight is 26.28 kg without oil.The final results show that the proposed new type of high pressure three screw pumps can achieve the desired goals.And compared to traditioanal high pressure structure,the new design has greatly reduced the size.