| Multi-way valve is one of most critical components of hydraulic system of hydraulicexcavator. The performances of the multi-way valve determine the level of the whole machine.The multi-way valve of hydraulic excavator is studied relatively late in our country. Thetechnology of domestic multi-way valve of hydraulic excavator is weak and behind that ofabroad. Currently, there is no domestic multi-way valve with high performance to meet thehydraulic excavator’s demand. The excavator host manufacturers have no choice but todepend on import completely. Multi-way valve has become the shackles for hostmanufacturers. In order to get out of this predicament as soon as possible, we can only go onthe way that a set of design theory is formed and localization is promoted by absorbing theadvanced technology of foreign multi-way valve.Taking a certain multi-way valve of hydraulic excavator as research object, the workprinciple, the orifice area variation pattern, the valve flow field characteristics, the stable flowforce is analyzed by theoretical and flow field simulation methods. The works lay afoundation for the localization of multi-way valve.The main research works and conclusions of this thesis are as follows:(1) Based on the operating characteristics of the hydraulic excavator and therequirements of the hydraulic system, the structure and characteristics of the multi-way valveare introduced. The principle of valve Arm1, Arm2and Lock are analyzed. The oil flow ofhydraulic system, the work principle and the characteristics of arm circuit under five differentconditions such as usual regeneration, forced regeneration, regeneration cutting, neutral andarm release are analyzed in detail.(2) The calculation method and principle on orifice area of multi-way valve of thehydraulic excavator are introduced. The relative formulas are derived, and the calculations areprogrammed. The orifice area curve of bucket valve, swing valve and arm valve are obtained,and all the curves are analyzed based on the movement characteristics of relative actuators.(3) The flow field dynamics simulation models with different spool displacement ofvalve are created by software UG and GAMBIT, and the characteristics of different flow fieldare analyzed by software FLUENT. The distribution of velocity, pressure and turbulence energy of the flow field in the valve Arm2are compared by the visualize diagrams. The lawthat the characteristics of flow field are influenced by the displacement of valve spool isobtained.(4) The stable flow force under different work conditions is compared by the flow fieldsimulation, the variation laws of the steady flow force with the displacement of spool isobtained. |
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