Fluid Drive And Control Application System Oriented Study Of Fault-tolerant Principle And Error Correction Method

Fluid power transmission and control system plays an important role in varioustypes of machinery and equipment; fault tolerance and fault rectification technologiesare effective approaches for enhancing reliability and safety of fluid power transmissionand control system. Fault tolerance and fault rectification technologies of hydrauliccontrol valves are taken as the main clue. Structure of directional-control valve withfault tolerance function and structure of counterbalance valve with fault rectificationfunction are designed, static characteristics and dynamic characteristics for above twohydraulic control valves are studied deeply and systematically in this thesis.The three-position, four-way, directional-control valve is an important hydrauliccomponent, either a sliding-spool type or a rotary spool type is adopted in the structureof traditional directional-control valve, it can’t change directions when failure occurs. Inthis thesis, the sliding-spool and rotary-spool are integrated into a valve body, takingabove idea as foundation, structure principle and structure design of the directionalcontrol valve are described in detail. Furthermore, the sliding function, rotary function,and switch principle when failure occurs, are analyzed. According to the mathematicalmodel of the directional-control valve under linear motion and rotary motion workmode, static characteristics analysis and dynamic characteristics analysis are conducted,and results show that the directional-control valve not only possesses good static anddynamic characteristics, but also possesses fault tolerance function. The new directionalcontrol valve can further improve safety and reliability of hydraulic system.Hydraulic counterbalance valve plays an important role in hydraulic system aslimiting speed and guaranteeing safety, it is an important hydraulic component, and iswidely used in the modern engineering machinery. There are some deficiencies in speedcontrol and security features with traditional counterbalance valve. An innovativestructure of counterbalance valve is proposed in this thesis. On one hand the ideas offault rectification are applied to the design of counterbalance valve, on the other hand adirect feedback of control piston structure is proposed first. Structure principle andstructure design of the counterbalance valve are presented in detail. The normal lifting function, remain stationary function, decline function, and fault rectification function incase of emergency are described in detail. Furthermore, the rationality of the design isverified. According to the mathematical model of the counterbalance valve, staticcharacteristics analysis and dynamic characteristics analysis are conducted. Thecounterbalance valve not only possesses good speed control function, but also possessesfault rectification function in case of emergency. It will improve the safety of hydraulicsystem significantly.Research on innovative structures design of hydraulic control valves and its faulttolerance and fault rectification technologies will provide some effective theories,methodologies and techniques for the fault tolerance and fault rectification of hydraulicsystem.