Reaserch On Indeprndent Metering Control Valve Of Pilot Hydraulic Controal

Hydraulic transmission is widely used in engineering machinery with its advantages of high power-to-weight ratio and strong anti-interference ability.However,its low efficiency in exchange for outstanding advantages is also the application constraint of hydraulic technology.Therefore,it is a long-term and valuable hot issue to study the energy-saving benefits of hydraulic system.The hydraulic system uses load sensing,flow regeneration,energy recovery and other measures to improve system efficiency.However,the traditional valve control mode has redundant throttling effect at the outlet throttling edge while controlling the flow rate of the actuator inlet chamber,and has no active cavitation prevention function.The independent control technology of load port adopts double spool to control the inlet and outlet of actuator,which increases the degree of freedom of oil return throttling control,and has the functions of energy saving,active cavitation prevention and switching flow regeneration mode.In this paper,a new type of load port independent control valve group scheme is proposed.Its structure is to use two sets of pilot pressure reducing valves to control the displacement of two main spools by proportional pressure difference,and then control the output flow of the valve,in order to obtain high response linear controllable flow characteristics.For this scheme,the main research contents of this paper include :According to the valve group scheme and flow demand,two main spools with Ushaped and V-shaped orifices are designed respectively,and the structural design and selection of related parts are completed.The rationality of the design is verified by simulation method.Based on the idea of electro-hydraulic differential compensation and dynamic pressure feedback,the method of calculating the flow area of the pressure control valve based on the target speed and the ratio of the flow area of the two valves is adopted.Combined with the mode of predicting and logically switching the flow-pressure control cavity according to the direction of load force,AMESim simulation is used to analyze the feasibility and limitations of the control strategy.The relationship between speed and load and pump source pressure in flow regeneration mode is derived.Taking the impedance extension as an example,the condition of energy saving of the load port independent control technology is compared with the traditional valve control mode.The results show that the valve group scheme can achieve high-precision speed control and anti-cavitation function under the two control strategies adopted and the control cavity switching mode under a certain target speed and load law.The performance of U and V valves in small flow control is related to system parameters.The simulation shows the accuracy of the speed calculation formula of the derived flow regeneration mode.