| Hydraulic direction control valve,as a control component to change the direction of oil flow in the hydraulic drive system,is an indispensable basic component of the hydraulic transmission system.In the hydraulic transmission system,the use of directional valve is huge and the control is complex,which makes the transmission system bloated.Experts and researchers have done a lot of research to improve and solve this problem.In order to simplify the use of directional valve and enhance the function of single directional valve,this paper proposes a principle of six-position six-way electro-hydraulic directional valve with multiple directional control based on sliding and rotating of single valve spool.The key technologies are studied by theoretical analysis,simulation and experiment.Firstly,according to the reversing requirements of multi-pump and multi-motor system,the working principle of the directional valve was determined.The main valve spool adopts the movement mode of combination of sliding and rotation to realize the reversing function of multi-position and multi-way;the driving device and its distribution scheme were determined,and the structural characteristics of key components were revealed.The comparison showed that the directional valve studied in this paper has better adaptability for multi-pump and multi-motor system.Secondly,the infinitesimal method was used to analyze the mechanism of clearance leakage,and a new variable factor was found.The flow formulas of axial and circumferential leakage under 4 kinds of shape and position relationship between main valve spool and valve bush hole were deduced theoretically.The mathematical models of axial leakage and circumferential leakage flow were obtained,the angle variables affecting the leakage were determined and analyzed,the leakage mechanism was revealed,and the influence of angle variables on the axial,circumferential leakage and unilateral combined leakage was obtained.Thirdly,according to the three-dimensional flow state of oil in the directional valve,the mathematical expressions of 3 kinds of steady flow force are analyzed and obtained.The influences of 3 kinds of steady flow force on the main valve spool and valve port were obtained.According to the special distribution of the leakage clearance and the shape and position of valve spool and valve bush,the infinitesimal method was used to analyze the two kinds of hydraulic clamping forces caused by the axial circumferential leakage.The mathematical models of the hydraulic clamping force were established,which conforms to the actual situation.Furthermore,the influence of the angle variable on the hydraulic clamping force was found,and the relationship between angle variable and hydraulic clamping force was analyzed and obtained.After that,aiming at the method of reducing the hydraulic clamping force,this paper puts forward a structure form of the groove which combines the circumferential groove with the axial groove.By using SolidWorks to establish the clearance model,and based on ANSYS and FLUENT software,the finite element analysis and flow field simulation were carried out to reduce the hydraulic clamping force according to the number and width of grooves.Through comparative analysis,the influence law of the groove on the hydraulic clamping force without considering the leakage was obtained.Combined with the influence of different types of groove on the internal leakage,the structure of groove suitable for the directional valve in this paper was obtained by comprehensive analysis.Finally,the geometric relationships between the structures were analyzed,and the parameter formula between the key structure size and the diameter of the directional valve was established,and the design size and relevant parameters of the main structure of the reversing valve were determined.According to this,the prototype was processed and the test system was built.The experimental results showed that the oil function of the valve in 6 working positions was realized,the numerical relationship between the pressure loss of the valve in each working position and the change law of the pressure loss between the oil ports were obtained;when the oil supply pressure is fixed,the variation rule of the internal leakage amount and pressure was obtained for the main valve spool at each working position.The main reasons for the error between the test results and the theoretical values were analyzed.This paper not only enriches the type of hydraulic directional valve,but also provides a theoretical reference for the study of similar directional valve.At the same time,it also proposes a solution to reduce the number of directional valve used in the hydraulic system and simplify the hydraulic system,which has a good application prospect and practical engineering significance. |
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