Multi way directional valve is called multi-way valve for short. It is a combined valve with more than two directional valves as the main body. According to the requirements of different systems, the overflow valve (safety valve), one-way valve, overload valve, oil makeup valve and other valves that play the role of safety protection are often combined together.
In order to prevent overloading of the hydraulic system, the main safety valve is set in the oil inlet chamber of the multi-channel valve as the main safety valve of the whole hydraulic system.
According to the structure of the valve body, a one-way valve is installed in each valve body. Its function is to avoid the backflow of pressure oil when the valve is reversed, so as to overcome the "nodding" phenomenon in the working process.
Function of overload valve
The structure of multi-channel valve is divided into two types: split and integral. The multi-channel valve of Yuchai excavator is divided into two types and is assembled by multi-channel (block) directional valve with bolts.
Multi way valves are classified into series, parallel, series parallel and composite oil circuits according to the oil circuit connection mode 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 main oil return port of the multi-channel valve. The directional valves can be operated independently.
(b) For series parallel connection, the oil inlet chamber of each reversing valve is connected with the intermediate oil circuit of the previous reversing valve. Operate the former reversing valve, and the latter reversing valve cannot work, which ensures that the former reversing valve has priority in oil supply.
If the oil circuit of the multi-channel valve is composed of the above basic oil circuit, it is called the composite oil circuit.
3.5.3 the unloading methods of hydraulic pump include middle unloading and unloading with unloading valve.
Intermediate unloading means that the pressure oil at the inlet of the multi-channel valve is directly returned to the oil tank for unloading through the intermediate oil circuit of each combined directional valve.
When the multi-channel valve of yc13 and yc35 excavators is in the middle position, the middle return oil circuit is used to unload the pump.
Unloading of the unloading valve means that the pressure oil at the inlet of the multi-channel valve is unloaded through the unloading valve. When the multi-channel valve of yc65 and yc85 excavators is in the middle position, the flow control valve (which can act as the unloading valve) is used to unload the pump.
3.5.4 the operation of multi-channel directional valve includes manual operation and pilot (hydraulic) operation.
