Study On Key Technology Of High-pressure Internal Gear Pump

Internal gear pump is widely used in injection molding machinery,engineering machinery and marine equipment because of its compact structure,high volume efficiency,low noise,good anti pollution ability and self-priming performance.With the increasing demand for internal gear pump in various industries,higher requirements are put forward for its comprehensive performance,which makes the internal gear pump develop towards high pressure,large displacement and lower flow pulsation and noise.In this paper,the output flow characteristics of internal gear pump,the optimization of radial clearance compensation structure and the radial force balance of internal gear ring are studied.In order to explore and optimize the output flow characteristics of the internal gear pump,based on the relationship between the engagement point and the angle and the influence of the coincidence degree,this paper proposes a theoretical method for the accurate calculation of the displacement of the internal gear pump,and uses three different types of internal gear pump parameters to verify the displacement,the maximum error is about 3%.The flow pulsation coefficient is deduced to analyze the flow quality of the pump.The flow pulsation characteristics of the pump under different meshing modes are compared and analyzed from the three aspects of the flow pulsation coefficient,the instantaneous flow curve and the pump outlet flow curve based on pumplinx.Finally,the influence of gear parameters on the output flow characteristics of the pump is explored,and the selection principle of gear pair parameters is proposed,which aims to maximize the pump displacement and minimize the flow pulsation without significantly increasing the geometric size.In order to explore and optimize the stress state of the radial clearance compensation structure of the internal gear pump,this paper analyzes the dynamic hydraulic pressure of the oil in the transition area of the meniscus fitting surface by theoretical calculation and simulation analysis,and analyzes the supporting force characteristics of the plate spring and nylon rod to the meniscus,based on the radial clearance compensation principle of the split type meniscus assembly.Taking the weak lower crescent as the research object,the analytical expressions of its compression coefficient and resultant moment with the rotation angle of the gear are deduced through the stress analysis,and the stress state of the small crescent is measured.Finally,the influence of the position of high and low pressure sealing nylon bar and the spring force on the stress state of the small crescent plate is explored with an example.The reasonable matching of the position of nylon bar and the specification of the plate spring can make the small crescent plate adhere to the inner ring gear reliably and wear more evenly.In order to explore and optimize the radial force state of the inner ring gear,based on the kinematic relationship between the meshing point and the rotation angle,the corresponding dynamic analysis of the radial force on the ring gear is carried out,and the relationship between the hydraulic pressure on the inner ring gear and the meshing force between the gear pairs and the rotation angle is deduced respectively.Combined with the structure and running state of the ring gear and the shell,the supporting characteristics of the oil film cavity to the ring gear are analyzed,that is,the static supporting force provided by the hydrostatic oil film,and the dynamic supporting force provided by the dynamic pressure and extrusion effect of the oil film cavity.Finally,in order to balance the radial force of the inner ring gear,the position and angle parameters of the hydrostatic bearing are designed and calculated.