Investigation On Oil Film Shape Algorithm And Temperature Characteristics Of Port Pair Of Axial Piston Pump

The port pair is one of the key friction sub of axial piston pump.In the process of working,due to the force and torque,the cylinder body deflection,the coaxiality of the cylinder body and the main shaft and other factors,the shape of the oil film is wedge-shaped and changes with the rotation of the cylinder body,and its change law is relatively complex.Since the axial piston pump has the characteristics of high pressure,high speed and high work to weight ratio,the oil film gap of the distribution sub is small,and its temperature characteristics have great influence on lubrication,friction and wear,so it is very meaningful to study the change law of the oil film shape of the port pair and its temperature characteristics for the design and optimization of the axial piston ump.This paper establishes the axial force balance equation and oil film thickness model for the axial piston pump with wedge-shaped oil film,and establishes the wedge-shaped oil film shape solution algorithm based on the test data of the three-point film thickness of the port pair,and obtains the oil film shape variation law.The main work is as follows:(1)Based on the film thickness test data of the port pair,the solution algorithm of the oil film shape of the port pair is established.Considering the pressure of the plunger chamber on the plunger cylinder,the static and dynamic pressure support force of the oil film,and the mixed frictional contact support force of the port pair,the axial force balance equation of the plunger cylinder is established;considering the influencing factors of the constant and fluctuating values of the film thickness,the formula of the average thickness of the oil film and the formula of the fluctuating thickness are established,and the oil film thickness model of the port pair is further established.A test bench was built to test the film thickness of the distribution sub oil film,and the film thickness test data were obtained.The algorithm for solving the oil film shape of the port pair oil film was established,and the time-varying curves of the minimum film thickness,wedge angle and azimuth angle of the oil film under multiple working conditions were solved by MATLAB,and the influence of the working pressure and swashplate inclination angle on the oil film shape was analyzed.(2)The oil film temperature model of the port pair is established.According to the solved oil film shape,considering the influence of the mixed friction area on the viscous friction loss of the port pair,the throttling loss model caused by the leakage of the port pair,the viscous friction loss model,the heat conduction model of the port pair,combined with the hydraulic oil viscosity-temperature characteristic equation,the heat-flow coupling model of the port pair is established,and the temperature of the port pair under different working conditions is solved by MATLAB.(3)The influence law of working pressure,cylinder speed and swashplate tilt angle on the temperature characteristics of the oil film of the flow distribution sub is analyzed.The results show that the larger the working pressure and cylinder speed,the larger the overall temperature and maximum temperature of the oil film,the highest temperature point is located at the average value of the azimuth,and the temperature rise rate of the highest temperature point is the largest.The larger the inclination angle of the swashplate,the smaller the maximum temperature,the overall temperature increases in the circumferential [-80°,-40°]range and decreases in the circumferential [-30°,80°] range.This is because the greater the inclination of the swashplate,the greater the wedge angle and the lower the temperature,but an increase in the inclination of the swashplate leads to a decrease in the azimuth angle,i.e.,the minimum oil film thickness point is shifted counterclockwise,resulting in a shift in the maximum temperature point,which affects the temperature distribution.