| The working efficiency of a hydraulic excavator is depend on its working device, which is the main actuator in the working process. When design and match hydraulic components for a new excavator, it is necessary to debug and optimize them repeatedly, especially the main spools of multi-way valve, so that they can meet the performance requirements of working device. Numerical simulation is an important method to guide the structural optimization design for hydraulic components. But in fact, for the medium hydraulic excavators which use throttle governing system, the results of simulation are often different from the actual conditions, because the performance of hydraulic system of excavators can be easily affected by load and it is impossible to simulate the ever-changing load accurately just with numerical simulation method.To make up the shortage mentioned above, a semi-physical simulation platform for hydraulic system of working device of excavator was designed and established, which combined with the technology of numerical simulation and virtual instrument. And it’s used to study the hydraulic system of working device. The main contents of this paper are as follows:Firstly, the basic composition and working principle of hydraulic system of working device of excavator were introduced. The principle and characteristics of the negative flow control, total power control and rotate speed sensing control for the main pump were studied. The basic circuits of hydraulic system of working device were analyzed.Secondly, the mathematical model of main pump and the structure of main reversing valves of multi-way valve were analyzed. And then the numerical simulation model of main pump and main reversing valves were built based on AMESim. After studying the characteristics of valve orifices of main reversing valves, a new calculation method of equivalent flow area for valve orifices of non-circular opening spool valve was proposed. The numerical simulation model of hydraulic system of working device was established. And the model parameters were set accurately with the help of measured data.Thirdly, after studying the testing method for load force, the general scheme of real-time testing system for excavator based on NI CompactRIO was established. The hardware system of testing system was built, and a new data acquisition method of SSI signal was proposed. The FPGA VIs, RT VIs and HOST VIs of the software system of testing system were designed.Finally, the data communication interface between the numerical simulation model and the HOST VIs of testing system was studied. The semi-physical simulation platform for hydraulic system of working device of medium hydraulic excavator was built based on the testing system and the numerical simulation model. The movement of each hydraulic cylinder for boom, arm and bucket was simulated, and the simulation results were analyzed with experimental data.The main contribution of this paper is to design and establish a semi-physical simulation platform for hydraulic system of working device of excavator, which combined with the technology of numerical simulation and virtual instrument. The platform can be used to study the hydraulic system of excavator. It provides a new method to design, analyze, and study the hydraulic system of excavator, and is valuable for engineering application. |
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