Control Charateristic Research On Axial Variable Displacement Piston Pump With Displacement-Force-Feedback Principle

The research object in this paper is the variable-displacement device of A4VSG750-HD series hydraulic swashplate axial piston pump, which is produced by REXROTH. Mathematical model of variable-displacement device is developed by analyzing the internal structures and the operating principles of the servo valve and the variable-displacement cylinder. A simulation model for the variable-displacement device is established based on AMESim, and the relationship between the control performance and the key parameters as spring rate and pre-compression stroke. The correctness of the simulation model is tested by experiment through the test device. The specific work in the following order:First, a three-dimensional model of the A4VSG750-HD series swashplate axial piston pump is established. Mathematical model of variable-displacement device within A4VSG-HD series hydraulic axial piston pump is established by analyzing the internal structures and the operating principles of the servo valve and the variable-displacement cylinder, and the determining factor influencing the control characteristic is found out. The swashplate axial piston pump assembly model is established in the UG three-dimensional design software. Hydraulic system simulation software AMESim and multi-system dynamic analysis and simulation software ADAMS are combined together. The co-simulation model of axial piston pump is established through the interface between the two softwares.Second, simulations are performed for the variable-displacement device within A4VSG750-HD series hydraulic axial piston pump in AMESim, analyzing the influences of the control characteristics and dynamic characteristics from the components of the variable-displacement device. At the same time, test the Mathematical model by four group of central return-springs in valve plug.Finally, test the variable-displacement device within A4VSG750-HD series hydraulic axial piston pump by experiment through the test device, then get the following conclusions:The control hydraulic pressure is connected to output volume when the variable-displacement device of hydraulic axial piston pump operates. The output volume of the pump is proportional to the control hydraulic pressure. The parameters of central return-spring in servo valve and the area of the head face at servo value are the determining factors. They determine the control range of the variable-displacement device. The dynamic characteristic is remarkably affected by load pressure of the system, the parameters of the left and right sides return-springs of the servo value and The control hydraulic pressure. In this paper, the simulation results are basically in accordance with the experimental results. It means that the simulation model of the variable-displacement device is correct. The conclusions drawn by this paper are universal. It helps to the design and the optimization of the variable-displacement device.