Hydraulic multi-way directional valve, referred to as multi-way valve for short, is a multi-functional integrated valve with two or more directional valves as the main body and integrating different functional valves such as safety valve, one-way valve, diverter valve, overload valve, brake valve and oil makeup valve. It can control multiple actuators. Because of its compact structure, simple pipeline connection, small pressure loss and convenient installation, it has been widely used in construction machinery 14.
Multi way valve has two functions of flow and direction control. It can be divided into different categories according to different classification methods.
Various forms of multi-way valves are introduced below:
(1) Multi way valve can be divided into integral type and split type according to the structure of valve body. In general, a group of multi-channel valves is composed of multiple directional valves, and each directional valve is a joint. The integral multi-way valve is to install each directional valve and some auxiliary valves on one valve body. The integral type has the advantages of compact structure, small pressure loss, light weight, less processing surface, large flow and high pressure; However, its universality is poor, the internal flow channel is formed by precision casting, which has high requirements for casting technology and high cost. It is more suitable for relatively stable and large-scale machinery. The split multi-way valve uses bolts to assemble the directional valve blocks together according to the use requirements. It has strong universality, but there are many processing surfaces and there are many possibilities of oil leakage.
(2) According to the oil circuit connection mode between the directional valves, it can be divided into parallel, series, series parallel and composite oil circuits, as shown in Figure 1.5. Figure 1.5A) is a parallel type. The pressure oil at the oil inlet of the parallel oil circuit multi-channel valve can directly enter the oil inlet chamber of each directional valve, and the oil return chamber of each directional valve directly leads to the main oil return port of the multi-channel valve. Each combined valve can act independently, but in case of compound action, the one with small load can act preferentially. Fig. 1.5b) is a series type. The oil inlet chamber of the rear reversing valve of the series oil circuit multi-way valve is connected with the oil return chamber of the previous one, which can realize the simultaneous action of the multi-way valve, but at this time, the pressure at the outlet of the hydraulic pump is the sum of the pressures of all actuators, so the operation resistance is large. Figure 1.5C) is a series parallel type. The oil inlet chamber of each combined valve of the series parallel oil circuit multi-channel valve is connected in series, and the oil return chamber is connected with the main oil return chamber in parallel. With this oil circuit connection mode, when operating the directional valve of the previous one, the next one cannot work, which can ensure the priority action of the previous one. The oil circuit of the composite oil circuit multi-channel valve is composed of the above two or three combinations.
