Research on Displacement and Flow Control Characteristics of the Proportional Directional Valve Based on a Flow Feedback Mechanism

The proportional directional valve is a key component in electro-hydraulic control systems; however, existing solutions face structural and functional challenges. The mechanical feedback valves serve open-loop systems and electronic feedback valves serve closed-loop systems, their different mechanical structures complicate manufacturing and selection. Moreover, current proportional directional valves require additional pressure compensation valves for flow control, increasing complexity and energy loss. To address these challenges, this article proposes a pilot-controlled electrohydraulic proportional directional valve based on a flow feedback mechanism, which enables displacement and flow amplification via a feedback slot in the movable valve sleeve. Additionally, the appropriate displacement and flow control strategies are designed, and its efficacy is validated by co-simulation and test. The results show that the valve exhibits 0.28% linearity and 0.13% hysteresis in displacement closed-loop control mode, and 2.68% linearity and 1.47% hysteresis in displacement open-loop control mode with the strategy of compensate for the effects of flow force and spring force. Both control modes have been successfully realized, providing redundant control capabilities. The valve demonstrates 4% equal flow control accuracy, and exhibits strong antiload disturbance under significant load variations, eliminating the need for a pressure compensation valve. This article provides a simplified and cost-effective solution for fluid transmission and control of industrial and engineering equipment.