Analysis And Research Of A New Type Synchronous Valve With Full Compensation Of Principle Error

With the rapid development of modern industry,machinery,aviation,shipping and many other industries have increased the demand for hydraulic.There are many ways to realize hydraulic synchronization,among which the synchronous valve has been widely used due to its advantages of low price and stable performance.However,in actual work,the synchronous valve often occurs two branch load pressure is not equal and the inlet flow deviates from the rated flow,resulting in synchronous error.These errors are theoretical and will not be reduced by the improvement of the machining accuracy of the synchronous valve.The inadaptability to wide range of off-load and flow fluctuation greatly limits the practical application range of synchronous valves.Although the development trend of hydraulic control technology is integration and digitalization,the traditional hydraulic valve is still the foundation of its development.The hydraulic synchronous valve is selected as the research object to improve the ability of the synchronous valve to resist bias load and flow change,so as to improve the synchronization accuracy of the synchronous valve from the perspective of resolving the principle error.Not only can broaden the application range of synchronous valve,but also can enrich the theory of hydraulic synchronous valve,with both theoretical and practical significance.Most of the variable orifice shapes of the existing synchronous valves are circular,but the orifice area is not linearly related to the pressure difference between the two branches and the total inlet flow.Therefore,the flow compensation of variable orifice is limited,and the synchronization error is not zero theoretically.Therefore,the design theory of synchronous valve needs further improvement and innovation.Based on that,this paper analyzes the mechanism of synchronous error caused by load differential pressure and flow change,and puts forward the design theory of full compensation of principle error.According to this theory,a new type of synchronous valve with three-stage structure is designed: the first stage is fixed orifice;the second stage is load differential pressure compensation stage,which compensates for the synchronous error caused by load differential pressure;the third stage is flow deviation compensation stage,which compensates for the synchronous error caused by flow change.Based on the flow characteristics of thin wall holes and the basic working principle of the synchronous valve,the last two stages are designed according to the variation law of synchronous error with load deviation and flow fluctuation.By using MATLAB to quantitatively analyze the influence of load differential pressure and inlet flow change on variable orifice area,the shape of orifice is innovated.This special orifice can compensate the nonlinear synchronization error through the linear displacement of the spool.Finally,the simulation software AMESim is used to build a model of the new synchronous valve to simulate its working state.It is found that the synchronous error is less than 0.4% when the inlet flow rate of the new type synchronous valve is 20L/min and the load pressure difference is within the range of 40% of the maximum load pressure.When the load differential pressure is 10 MPa and the inlet flow varies within 50% of the rated value,the synchronization error is less than 0.6%.The accuracy of the step valve is improved to less than 1% from the way of compensating the principle error.A large number of studies have confirmed that there is a nonlinear coupling relationship between flow and pressure in the synchronous valve control system.The pressure difference compensation method or feedback method is difficult to solve the problem of high precision flow control of synchronous valve when the load changes,especially when the load changes dramatically.Aiming at this scientific problem,this paper starts from the circulation characteristics of thin wall holes.Based on the principle of full compensation for the error caused by load offset and flow deviation,the control mode of synchronous valve and the form of variable throttle are designed completely.The new type of synchronous valve has the advantages of high precision,strong resistance to load bias and strong resistance to flow deviation.Through the research on the new type of synchronous valve,the paper explores the flow compensation method and key technologies of high-precision shunt and collector valve with wider flow adaptive range when the load changes greatly.It provides a feasible design theory and method for improving the performance of similar hydraulic valves.