Research On Low Speed Characteristics Of Friction Pair Of Piston Pump

With the continuous advancement of industrial technology,the global environmental pollution problem has become increasingly serious,and how to effectively promote environmental governance towards sustainable development has become a problem that all countries and industries are concerned about.Electrification of construction machinery is a new development concept of the current construction machinery industry,because electrification has the advantages of energy saving,low noise and low emissions,it has become an important way for the construction machinery industry to achieve green and lowcarbon transformation,reduce costs and reduce pollution.The variable speed volume speed regulation system adopts the structure of servo motor directly driving the quantitative pump,which has good energy saving and noise reduction effect,and is one of the important ways to realize the electrification of construction machinery.However,due to the shortcomings of poor stability at low speed,its application under high voltage and high power conditions has been severely limited.Among them,the piston pump friction pair cannot give full play to its efficiency at low speed,which is one of the important factors leading to the poor stability of the system at low speed.In this paper,a theoretical model is established for the friction pair of swash plate axial piston pump,the influence of low speed on the oil film characteristics of friction pair is analyzed and discussed,optimization measures are proposed,and a torque test platform of piston pump is built to verify the simulation results.The main research contents and conclusion are as follows:(1)Theoretical modeling of friction pairs for axial piston pumps.Firstly,the working principle of swash plate axial piston pump is described in detail,and the key parameters such as theoretical displacement,theoretical flow rate and theoretical torque are derived,which provides a theoretical basis for the simulation model of friction pair resistance torque and the construction of torque test platform.Secondly,considering the lateral force of the piston pair,the static and dynamic pressure effects and extrusion effects of the slipper pair and the port plate pair,the kinematics and dynamics of the three friction pairs were analyzed,and a mathematical model of force and moment balance was established.Finally,the three-point circumferential uniform distribution description method and the inclination angle were used to establish the mathematical model of oil film thickness of the slipper pair and the port plate pair.(2)Simulation analysis of low-speed characteristics of friction pair of axial piston pump.Firstly,based on the established mathematical theoretical model,with the help of Matlab and Amesim simulation programs,combined with Stribeck curve,the oil film thickness model and friction pair resistance moment model were constructed.Secondly,the simulation results of the low-speed characteristics of friction pairs of swash plate axial piston pumps are analyzed.The results show that with the decrease of speed,the static pressure of the oil film remains unchanged,and the dynamic pressure gradually decreases,especially when the speed is too low,the dynamic pressure effect of the oil film cannot be formed,and the dynamic pressure of the oil film is zero.With the decrease of speed,the dynamic pressure support force of the oil film decreases,and the hybrid friction force and extrusion support force increase,among which the change amplitude of the dynamic pressure support force is the most obvious.The thickness of the oil film decreases with the decrease of the speed;With the decrease of speed,the friction pair resistance torque and the actual torque of the piston pump gradually increase,resulting in a gradual decrease in the efficiency of the piston pump,especially at low speeds.Finally,taking the port plate pair of A10VSO45 test pump as the research object,the structure of the port plate is optimized,the area of the outer sealing belt is increased,and the simulation analysis is carried out.The results show that with the increase of the sealing belt area outside the port plate,the dynamic pressure effect can be formed at a lower speed,and the dynamic pressure effect is more significant than before the improvement.In addition,after the area of the sealing belt outside the port plate is increased,the thickness of the oil film is also significantly higher than the previous oil film thickness.(3)Axial piston pump torque test analysis.Firstly,the schematic diagram of the torque test system of the plunger pump was designed,the test components and data acquisition cards were selected,and the torque test platform was built according to the schematic.Secondly,the torque test plan was formulated,and the test process of the test bench was introduced in detail.Finally,the actual torque of the A10VSO45 test pump at low speed was measured,and the test data and simulation results were compared and analyzed according to the torque test principle.The experimental results show that the theoretical model can accurately reflect the torque change trend of the swash plate axial piston pump at low speed.