Abstract
The interaction of pressure and flow in a hydraulic system with multiple working conditions, multiple actuators, and large flow limits action adjustment and control. Through a pilot pressure control circuit, hydraulically operated valves can adjust pressure or direction more effectively. A recent study proposed a two-stage pressure control method based on multistage orifices and solenoid valves. The requirements of the number and diameter ratio of short orifices in the series to realize the two-stage pressure control were theoretically analyzed. Scheme design and experiment were carried out. The influence of structures of complex flow channel and solenoid valve on the higher or lower pilot control pressure was considered in the experiment. The method was experimentally verified and successfully applied in a turbine electrohydraulic control system with lower maintenance costs, making the system more reliable in the case of electrical failure. Research results provide insight into pilot pressure control in fluid systems using multistage orifices to achieve either higher or lower pressure. In addition, it has important guiding significance for the design of valves or engineering systems based on pilot hydraulic pressure.
Highlights
Multiactuator systems are widely used in engineering, e.g., in bionic robots, engineering machinery, and turbine electrohydraulic control systems
This paper proposes a two-stage pressure control method based on multistage orifices
The paper discussed a novel two-stage pilot control pressure method based on multistage orifices and solenoid valves
Summary
Multiactuator systems are widely used in engineering, e.g., in bionic robots, engineering machinery, and turbine electrohydraulic control systems. When a single oil source serves the hydraulic control system with multiple actuators, the actions of each actuator are restrained due to the mutual influence of pressure and flow in the circuit; independent and stable pilot control pressure is often needed in the system to meet the specific operating requirements of the actuators. Taking the electrohydraulic control system of steam turbines in power plants as an example, the opening and closing actions of multiple hydraulic motors in the steam turbine system are controlled by pilot pressure. When the turbine functions abnormally, lower pilot pressure is provided to make the main control actuator close quickly and realize an emergency shutdown. The second method is to directly take system pressure oil as the pilot oil source This has pilot oil pressure closely related to the working pressure of the actuator, which can cause the system with a single pump source and multiple actuators to run incorrectly. It is difficult for this method to provide low pressure for emergency stops under normal conditions
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