Design of pilot-assisted load control valve for proportional flow control and fast opening performance based on dynamics modeling

• A flow control performance design method of pilot-assisted CBV is presented.
• A static model based on hydraulic half bridge is built to help designing orifices.
• A dynamic model is provided to determine compensation orifice diameter.
• Test results of an actual valve on test rig and crane validate the design method.

This paper presents a flow control performance design method of pilot-assisted load control valve (LCV) based on dynamics modeling. Good flow control performance has both static and dynamic aspects for an LCV. In static aspect, proportional flow control is required, which means the static flow through the valve can be proportionally controlled by pilot pressure. In dynamic aspect, fast opening performance is required, which means the desired flow can be fast provided but without overshoot when given a step pilot pressure. Good flow control performance of an LCV is the key to improve the system performance and to reduce the system complexity. In the method proposed by this paper, a static model of the static flow control performance based on hydraulic half bridge analysis was built to determine the area-displacement features of two key orifices to achieve proportional flow control. In addition, a dynamic model of the spool motions was provided to study the compensation orifice effect on the opening performance of the valve and further to determine the optimized orifice size. An actual LCV was developed according to above method. Tests were carried out both on a mobile crane and a test rig to validate its static and dynamic flow control performance, respectively. The good flow control performance of the valve in the tests indicates that the proposed method can provide theoretical guidance for pilot-assisted LCV design.