基于高速开关阀先导流量调节的比例方向流量控制理论与方法

In recent years, high-speed on-off valve is a hot research topic in the field of digital hydraulic. At present, the high-speed on-off valve has defects of small flux and discontinuous output flow. Two stage digital flow control valve, in which, the high-speed on-off valve is used as pilot stage and controls the movement of main valve. Although it can solve the defects, but has the problem of poor stability of output flow. This problem seriously restrict the application and dissemination of high-speed on-off valve. To solve this problem, a proportion direction flow control method based on pilot flow controlled by high-speed on-off valve is put forward, and new structures of pilot valve, main valve and differential pressure compensator is proposed. Based on the new methods and new structure, performance characteristic of pilot valve, main valve and differential pressure compensator is studied. The mapping relationship of pilot valve flow and structure motion parameters is revealed, and the coupling relationship between digital discrete fluid in pilot stage and continuous fluid in main stage is uncovered. The structural parameters optimization design method is obtained. By optimizing the on-off frequency, the pilot flow pulsation is reduced. By optimizing the pressure compensation characteristics of differential pressure compensator, the influence of load pressure changes on the output flow is eliminated. By the matching design of main valve structure parameters, the vibration of main valve core caused by pilot flow pulsation is restrained. The results is expected to significantly increase the output flow stability of the two-stage digital flow control valve, and meet the urgent demand for output flow stability of high-speed on-off valve, with the rapid development of digital hydraulic control technology.

近年来，高速开关阀是数字液压领域的研究热点。目前，高速开关阀存在通流量小、输出流量不连续等缺陷。两级数字流量控制阀，将高速开关阀作为先导级控制主阀运动，虽然可解决这一缺陷，但存在输出流量不稳定问题，严重制约了高速开关阀的推广应用。为此，本项目提出基于高速开关阀先导流量调节的比例方向流量控制方法，以及先导阀、主阀和压差补偿器的新结构，在此基础上，研究先导阀、主阀和压差补偿器的工作特性，揭示先导阀流量与结构和运动参数的映射关系、主级连续流体与先导级数字离散流体的耦合关系，得到结构参数的优化设计方法，优化先导阀开关频率，减小先导流量脉动；优化压差补偿器的压力补偿特性，消除负载压力变化对输出流量的影响；通过主阀结构参数的匹配设计，抑制先导流量脉动引起的主阀芯振动。预期成果将显著提高此类两级数字流量控制阀输出流量的稳定性，满足高速发展的数字液压控制技术对高速开关阀输出连续稳定流量的迫切需求。

高速开关阀存在通流量小、输出流量不连续等缺陷。两级数字流量控制阀，将高速开关阀作为先导级控制主阀运动，虽然可解决这一缺陷，但存在输出流量不稳定问题，严重制约了高速开关阀的推广应用。针对这一问题，本项目：（1）提出了阀芯旋转式高速开关阀新结构，通过阀芯旋转实现开关功能，并对其静、动态特性进行研究，研究结果表明：阀芯旋转式高速开关阀可以突破阀芯往复运动结构的限制，实现更高的开关频率，提高开关频率可以有效降低高速开关阀输出流量脉动。（2）建立阀芯旋转式高速开关阀内部流场模型，研究了结构和运动参数对阀口气穴的影响，提出了阀口气穴抑制方法，研究结果表明：气穴现象易发生靠近阀套窗口壁面位置，通过增大阀套窗口与阀芯沟槽之间的倾斜角，可以有效抑制气穴现象的发生。（3）建立阀芯旋转式高速开关阀液动力矩的数学模型，研究了结构参数对液动力矩的影响，提出了液动力矩的补偿方法，研究结果表明：液动力矩是阀芯转速的非线性干扰因素，降低沟槽的高度可以有效补偿液动力矩。（4）提出了高速开关阀先导流量调节的位移—流量反馈比例阀，主阀线性放大先导阀的流量，研究了主阀结构参数对动态响应特性的影响，研究结果表明：减小主阀节流槽面积梯度和控制腔容积可以有效提高响应速度，减小先导阀流量脉动对主阀流量的影响。（5）建立位移—流量反馈比例阀流量控制的数学模型，提出了基于神经网络的压力补偿方法，采用神经网络基于主阀芯位移和阀口压差进行流量预测，快速实时得到输出流量值，对输出流量进行闭环控制，研究结果表明：提出的压力补偿方法可以快速有效消除负载压力变化对输出流量的影响。（6）研制位移—流量反馈比例阀实验台，分别开展静动态特性和压力补偿研究，对理论研究结果进行了验证。研究成果显著提高此类两级数字流量控制阀输出流量的稳定性，满足数字液压控制技术对高速开关阀输出连续稳定流量的迫切需求，具有重要理论意义和工程应用价值。