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As its unique compact, flexible, multi-function, high efficiency and low price, easy maintenance, mall entire rotation crawler excavator is becoming more and more small earthwork construction units’favorite. Hydraulic system works as an important part of hydraulic excavator, How to make full use of engine power, reduce energy loss of hydraulic excavator is an important issue to be resolved, so doing research of simulation of the hydraulic system, not only can predict the performance of the machine, shorten product design cycle, but can also evaluate the performance of the entire system.In this paper, I use AMESIM hydraulic simulation software to simulate the system. By analyzing the condition of their working performance, we can optimize the hydraulic system’s configuration, improve the overall perfonnance and achieve maximum energy efficiency.This paper analyzes the structure and components of the hydraulic system and basic principle of circuits, calculating and designing the excavator’s hydraulic system. Under the overall performance requirements, on basis of the original depth analysis of the hydraulic system, the following proposed and the innovative technical improvements are as follows:(1) In order to reduce the hydraulic shock, I the increased security without impact valves in designing the motor running, and analyzed the characteristics of the improved hydraulic components; (2) the machine applies full power control system, analyzes Fujio full power control features and characteristics of hydraulic system analysis, calculates and verifies the power matching of the excavator’s hydraulic pump in order to meet the full power control purposes; (3) calculated working devices’parameters of the cycle time, blocking force, etc. in various conditions; checking the cylinders’strength and stability:(4) According to the completed schematic diagram of hydraulic system, established mini excavator’s cylinder valve, load sensing pump, rotary system, travel system as well as simulation model of the machine hydraulic system.Before designing the system, I optimized the overall system according to the technical requirements of the overall system. In order to achieve full power control purposes and realize the action switches in a variety of conditions. I increased the switching function in main pump; for the purpose of easy installation. I reduced the length of the main pump and made it 7～11mm shorter, increased by 6ml/r in pump maximum discharge, to guarantee performance’s the stability. In order to reduce the size of the rotary motor running, I set the hydraulic motors, hydraulic valves and gear as integration, improved the material strength of gear so as to enhance the affordability of the hydraulic motor. For the purpose of putting the rotary motor mounted under the cab, I changed the assembly of parts, reducing the height to 20%.Through the improved hydraulic system AMESIM simulation, available walking speed of the motor output shaft is more stable, import and export in the event of transient pressure curve after the peak, remained stable, you can ensure the linearity of excavator; the simulation to see The shortcomings of the traditional rotation system and the advantages of rotary system Fujio, that improves the efficiency of the latter, import and export of motor pressure stable. In the hydraulic system, research shows that the hydraulic system of the engine power curve and power curve are consistent, to the maximum extent to meet the full power control. To verify the system using software to create AMESIM correctness, rationality and parameter settings are correct.
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