Multi-way directional valve is abbreviated as multi-way valve, it is a combination valve composed of more than two directional valves. According to the requirements of different systems, it is common to combine relief valves (safety valves), check valves, overload valves, charge valves and other valves that play a role in safety protection.
In order to prevent the hydraulic system from being overloaded, a main safety valve is set in the oil inlet of the multi-way valve as the general safety valve of the entire hydraulic system.
According to the structure of the valve body, a check valve is installed in each valve body. Its function is to avoid the backflow of pressure oil when the valve changes direction, thereby overcoming the "nod" phenomenon in the working process.
The role of overload valve
The structure of the multi-way valve is divided into slice type and integral type. The multi-way valve of Yuchai excavator is divided into pieces, which are assembled by bolts of multi-piece (block) reversing valve.
Multi-way valves are classified into series, parallel, series-parallel and composite oil circuits according to the oil circuit connection between each block (joint) valve.
(a) For parallel connection, the pressure oil from the oil inlet can directly enter the oil inlet chamber of each directional valve, and the oil return chamber of the multi-directional valve is directly collected to the total oil return port of the multi-way valve. . The directional valve can be operated independently.
(B) For series and parallel connection, the oil inlet chamber of each directional valve is connected to the neutral oil circuit of the previous directional valve. Operate the previous directional valve, the latter directional valve cannot work, it Ensure that the previous directional valve is supplied with priority oil.
If the oil of the multi-way valve is composed of the above basic oil circuit, it is called a compound oil circuit.
3.5.3 The unloading methods of hydraulic pumps include neutral unloading and unloading using unloading valves.
Neutral unloading means that the pressure oil at the inlet of the multi-way valve is directly returned to the tank for unloading through the neutral oil passage of each directional valve.
When the multi-way valve of some excavators is in the neutral position, the neutral return path is used to unload the pump.
Unloading valve unloading means that the pressure oil at the inlet of the multi-way valve is unloaded through the unloading valve. Some excavators use flow control valves (which can act as unloading valves) to unload the pump when the multi-way valve is in the neutral position.
3.5.4 The operation of the multi-way directional valve is divided into manual and pilot (hydraulic) operation.
