Analysis On The Variable Displacement Characteristics Of Three Oil Mouth Axial Piston Pump

The electro-hydraulic control technology as the development of the hydraulic transmission and control technology is divided into two types of valve control and pump control technology.The valve control system has the advantages of simple structure,convenient operation,fast response speed and large output power,which plays an important role in the field of military and automation engineering machinery.The main disadvantage of the system is that there is a great of throttle loss,resulting in a large amount of heating to system,increasing the failure probability of the system and reducing the energy efficiency.The pump control technology has no loss of throttle,reducing system installed power and system noise,overcoming the problem of environmental pollution which from clean up a lot of waste oil,has high energy utilization rate and the small system calorific value.The pump controlled hydraulic cylinder system have been achieved satisfactory results.However,there is a problem that the single rod hydraulic cylinder system have bad control effect and can not be compensated by using the hydraulic pump alone,which is necessary to add hydraulic pump,valve,accumulator and other components to achieve single rod hydraulic cylinder compensation,resulting in the complex of system control loop and control strategy,low energy efficiency,restricting the green development of electro-hydraulic control technology.So our professor Quan Long based on anew assignment principle design the three oil mouth axial piston pump is a good solution to the asymmetric flow problem.This degree on the basis of the previous studies,analysis on the variable displacement mechanism and characteristics of the three oil mouth axial piston pump.This paper take the development of electro-hydraulic control technology as the background,mainly from the point of view of control theory and algorithm,contrasting analysis of the pump controlled hydraulic cylinder system circuit characteristics.According to the working principle of electro-hydraulic proportional displacement adjust,a inclined plate pendulum angular displacement feedback control scheme is proposed,comparing the control and job characteristics of the system circuit between simulation and experiment research.The specific research contents of this paper include the following aspects:First of all,based on the electro-hydraulic proportional displacement adjusting principle,considering the influence of elastic stiffness and load disturbance,the variable displacement control system model of three oil mouth axial piston pump is established by MATLAB/Simulink.Simulation analysis of different piston diameter,load stiffness and angle of swash plate,the load pressure of the pump outlet flow dynamic characteristics.The results show that the decrease of the hydraulic cylinder piston diameter,increasing load stiffness can accelerate response speed;increaseing the load pressure can improve the stability of the response.Then the three oil mouth pump variable displacement control strategy is optimized and the pump control performance is improved.Secondly,according to the swash plate variable resistance moment as load disturbance,influencing the pump variable displacement control characteristics.Through the detailed mapping of three oil mouth piston pump and built piston pump 3D model in Proe/E,establishing a complete three oil port axial piston pump multi body dynamic model.The paper analyzes the size and the change tendency of the variable resistance torque of the swash plate of the three oilmouth pump under the different swash plate angle,loading pressure,motor speed,and piston rod diameter.The results showed that with increasing the swash plate angle,the pump outlet pressure,the motor speed,the swash plate variable resistance torque increases;with the increase of swash plate angle,the control pressure of Swash plate rotation driven by double rod hydraulic cylinder increases,driven swash plate rotating double rod hydraulic cylinder to control pressure increases;with the increase of double rod hydraulic cylinder piston rod diameter,the swash plate has the same variable resistance moment but reduces the control pressure of the swash plate.Through the simulation X established the whole hydraulic system model of the three oil mouth piston pump,and the output flow of the plunger is input into the ADAMS.So as to improve the multi-body dynamic model of the whole pump.At the same time,the operating characteristics of the piston pump,such as the movement and load characteristics,the outlet flow and pressure characteristics are simulated and analyzed under different operating conditions,such as the swash plate angle,the motor speed and the load pressure.The simulation results show that with the swash plate angle and motor speed increases,the axial velocity and acceleration increased;with the loading pressure decreases,the plunger load force and the cavity bottom pressure decreases,the plunger load and cavity bottom pressure decreased,loading pressure is too low to produce greater pressure impact;with the swash plate angle increases,the pump outlet pressure keep constant amplitude and decrease the rise time but increase the flow pulsation amplitude;with the loading pressure increases,the oil outlet flow rise time increases and pulsation amplitude becomes larger.At last,a test bench with three oil mouth axial piston pump is built.The test results show that the displacement performance of the three oil mouth axial piston pump is stable and reliable.At the same time,the working characteristics of the piston pump such as the pump flow and pressure characteristics arestudied.The correctness of the simulation results is verified by experiments.The study demonstrates that:a inclined plate pendulum angular displacement feedback control scheme is proposed,the good control performance can be obtained under the condition of external load disturbance and the dynamic performance indicators meet the performance requirements of the control system.The system has the characteristics of simplifying the system loop,optimizing the structure parameters and the control strategy,which can meet the application of the three oil mouth piston pump in the practical engineering field.