Today, we will continue our look at hydraulic cartridge valve and focus on the components that make them up.
Hydraulic cartridge valves usually consist of four main parts: the insertion element, the pilot element, the control cover, and the cartridge block.
Insert element
The insertion element is the main stage or what is known as the power stage element of the hydraulic cartridge valve.
In terms of graphic symbols, although there are also many variants of two-plug valves, they basically consist of a spring, a spool that performs the opening and closing action, and a sleeve that encompasses both the spring and the spool.
We will insert the entire original assembly into a valve block. By opening and closing the valve spool, we will control the size of the opening to regulate the oil flow, pressure levels, and flow rate. This will allow us to control the direction of the actuator, as well as the pressure and speed of its movement.
Pilot element
We control the operating state of the insertion element using various pilot elements, which in this case belong to the control class. In addition to mounting on the control cover in the form of a plate connection or a stacked connection, we can also insert the pilot elements directly into the control cover or even into the valve body. For example, the figure below shows that we connect the two-position 4-way directional valve and the shuttle valve in a stacked connection.
It is also because the action of the hydraulic cartridge valve needs to rely on the external control pressure, and the source of the external control pressure can be various, then we can according to the source of the control fluid is different, the pilot section is divided into the following four control methods:
(1) Control fluid from port A
(2) Control fluid from port B
(3) Control fluid comes from outside
(4) Control fluid can come from either port A or port B, selected by the shuttle valve.
Control cover
People often overlook the control cover of hydraulic cartridge valves because they typically focus on the insertable part when thinking about cartridge valves. In fact, the control cover plate not only covers and fixes the inserted element but also acts as a bridge between the inserted element and the pilot element. More importantly, it comes equipped with various control functions of its own. As mentioned above, the control cover, together with the pilot element, forms the pilot part of the hydraulic cartridge valve and is a very important part of the control stage.
That is to say, on the control cover, we process the corresponding control flow channels and the mounting holes that facilitate connection, and we often install some pilot elements internally.
Cartridge valve body
We often refer to the cartridge valve body as the valve block, and more academically, we call it the hydraulic integrated block. We machine the cartridge valve body with mounting connection holes for insertion elements and control covers, as well as with various flow paths. Since we connect liquid cartridge valves mainly in an integrated way, we can install several insert elements in a valve body to achieve various system functions.
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