1. Valve core structure and motion control
The pressure regulation in the hydraulic valve body depends largely on the structure of the valve core and its motion control. The valve core is a key component in the valve body. Its movement in the valve body can change the size and connection mode of the fluid flow channel. For example, in a common overflow valve, one end of the valve core is subject to the spring force, and the other end is subject to the pressure of the hydraulic oil. When the system pressure is lower than the set pressure, the spring force keeps the valve core in the position of closing the oil overflow channel. As the system pressure increases, when the pressure of the hydraulic oil on the valve core overcomes the spring force, the valve core begins to move, opening the overflow channel, allowing part of the hydraulic oil to flow back to the tank, thereby reducing the system pressure. By adjusting the preload of the spring, different pressure adjustment values can be set. The greater the spring force, the higher the pressure the system needs to reach to move the valve core, achieve overflow pressure reduction, and thus achieve pressure regulation.
2. Application of throttling principle
Throttling also plays an important role in the pressure regulation of the hydraulic valve body. In some pressure regulating valve bodies, the flow rate and flow of hydraulic oil are controlled by setting a throttle in the flow channel, thereby affecting the pressure. When the hydraulic oil passes through the throttle, the flow rate of the oil increases due to the smaller flow area. According to the Bernoulli equation, the increase in flow rate will lead to a decrease in pressure. By changing the size of the throttle, such as using an adjustable valve core structure to move the valve core to change the opening of the throttle, the pressure of the hydraulic oil can be controlled. For example, in a speed regulating valve, the throttle works in conjunction with the pressure compensation device, which automatically adjusts the pressure difference before and after the throttle according to the change in load pressure, thereby maintaining a stable flow output under different loads, which indirectly realizes the regulation of pressure, because flow and pressure are interrelated in the hydraulic system.
3. Pilot control
Pilot hydraulic valve body is another common way to achieve pressure regulation. The pilot valve body includes a main valve and a pilot valve. The pilot valve first controls the pressure of the hydraulic oil with a smaller flow. When the pressure controlled by the pilot valve reaches a certain value, the action of the main valve spool is controlled by the transmission of hydraulic pressure. The precision of the pilot valve is usually higher, and it can respond more sensitively to pressure changes. For example, in a pilot-operated relief valve, the pilot valve controls the overflow of a small portion of the oil. When the overflow pressure of the pilot valve reaches the set value, the main valve spool opens to achieve a large amount of hydraulic oil overflow, thereby regulating the pressure of the entire hydraulic system. This pilot control method can achieve more accurate pressure regulation and more effective pressure control in a large flow hydraulic system.
