A multi-way valve is a directional control valve with an integrated structure composed of a directional valve and several auxiliary devices, and performs multi-directional switching control of oil flow. It has the advantages of compact structure, simple pipeline and convenient operation.
As a directional control device, it is mainly used in hydraulic systems such as construction machinery, mining metallurgical machinery, lifting transportation machinery and light industry machinery. Auxiliary devices mainly include main relief valves, overload relief valves, charge valves and other valve components. Most of these valves use plug-in components with smaller structural sizes. They are selected according to the requirements of the host, which has a great influence on the performance of the multi-way valve.
The current multi-way valve has many structures and models, which can be summarized into two types: integral type and combined type.
1) Integral multi-way valve The spool valve and various valve components of the integral multi-way valve are installed in the same valve body. It has a compact structure, light weight, and relatively small pressure loss, but the valve body casting process is complex and versatile, and it is integrated when mass production and fewer connections
2) Combined multi-way valveThe combined multi-way valve is composed of the front cover of the oil inlet, the back cover of the oil return, and the assembly of the valve bodies of various circuits. The early development of the multi-way valve, which is prone to oil leakage and large volume, was a manual six-way multi-way valve. This valve is: After the throttling of the bypass, the full flow of the oil source enters the system through the main valve port of the multi-way valve. It has certain proportional control performance, but the proportional control range decreases as the system pressure increases.
In view of the shortcomings of the six-way multi-way valve that is easily affected by the pressure difference and the unstable operation of the load change, the researchers developed a four-way multi-way valve with a pressure compensator based on the principle of the two-way speed control valve.
In the 1980s, the maturity and wide application of electro-hydraulic proportional technology promoted the application of electro-hydraulic proportional multi-way valves.The two-way pressure compensator was used in each joint for nearly 30 years to achieve load pressure compensation, and fixed differential overflow Valves or load-sensitive pumps realize load-sensitive control.When the flow rate of the pump is saturated, that is, the actuator demand flow exceeds the maximum flow rate of the pump, the pump's output pressure drops to reduce the flow into the highest pressure joint load, and the speed decreases, while entering other loads Of traffic remains unchanged. This can not meet the requirements of simultaneous operation of multiple cylinders in engineering.
21st century hydraulic technology is increasingly used in construction machinery. As an important component of the hydraulic system of construction machinery, the multi-way valve is not only continuously improved on the basis of the existing structure, but more importantly is to transplant the technical achievements in other fields, such as electronic technology, computer technology, information technology, automatic control technology, friction and wear technology and New materials, new processes, etc., to further develop construction machinery 名媛直播 in the direction of energy saving, high efficiency, high reliability and environmental protection, while China is still in its infancy. For the electro-hydraulic load sensitive load port, the system structure design, shunt control method, and decoupling control method for the mutual interference between the actuators to independently control the electro-hydraulic proportional multi-way valve to maximize the system energy saving and realize the system Stability and rapidity have become the focus of research.
