有源先导级控制的电液比例流量阀特性研究

针对现有技术采用压差补偿器或插装式流量传感器控制流量,会降低阀的通流能力,增加系统的功率损失和发热;大流量场合只能通过阀开口面积间接控制流量,受负载变化影响控制精度低;低工作压力范围可控性差、动态响应慢;大通径采用三级结构,构造复杂等问题,提出用小功率伺服电动机驱动小排量液压泵/马达(有源)、结合液压晶体管(Valvistor),构造新的低能耗、高可控的电液比例流量阀。该方法可扩大阀的流量控制范围,提高阀在低压时的动态响应。建立阀的静态数学模型,分析获得影响阀负载流量特性最主要的因素是反馈节流槽预开口量大小;进一步建立阀的动态数学模型,获得主阀芯稳定条件。根据阀的结构组成,建立阀的仿真模型,仿真分析主阀各参数对主阀性能的影响。结果表明,反馈节流槽预开口量越小,主阀负载流量特性越好;主阀口压降越大,主阀芯响应越快;但由动态数学模型可知主阀口压降太大且先导流量较小时,阀的稳定性也会降低。研究也表明,在保证主阀良好的动态特性前提下,可通过使先导泵/马达转速随负载压力变化,实现对阀的流量补偿,从而改善阀的负载流量特性。

Research on the Performance of Electro-hydraulic Proportional Flow Valve Controlled by Pilot Pump

Considering the problems that in existing technology, by using differential pressure compensator or cartridge type flow sensor to control flow will reduce the valve flow capacity and increase the system power loss and heating. The flow only can be indirectly controlled by changing valve opening area in large flow occasion and the control precision is low for the influence of load variation. The controllability is bad and dynamic response is slow when working pressure is low. The structure of three stage larger size valve is complex. So a low energy consumption, high controllable electro-hydraulic proportional valve which is structured by small displacement hydraulic pump/motor driven by servo motor and hydraulic transistor(Valvistor)is put forward. This method can enlarge the valve flow control range and improve the dynamic response of valve in low pressure condition. In research, the static mathematical model of the valve is developed firstly, and the most important factors which affect the characteristic of load flow is the size of feedback slot opening found out by theoretical analysis. Moreover the dynamic mathematical model is developed and the stability criterion of the valve is derived. According to the structure of the valve, the simulation model is established to simulate and analyze the influence of the parameters of valve on the performance of main valve. The simulation results show that reducing the size of feedback slot opening will improve the characteristic of the load flow of the valve. The main valve response speed increases along with the increasing of the pressure drop of the opening of main valve. But the stability of the valve will reduce when the pilot flow is small. The research also show that on the condition of keeping good dynamic performance, making the pilot pump/motor rotation speed change as load pressure varies so that can realize flow compensation of the valve improve the characteristic of the load flow.