The hydraulic valve body plays a key control role in the hydraulic system, and the valve core structure design is directly related to the flow regulation accuracy.
First of all, the shape and size of the valve core have a fundamental impact on the flow regulation accuracy. Common valve core shapes include cylindrical and conical. The cylindrical valve core has the characteristics of simple structure and convenient processing. Its axial movement in the valve body can change the flow cross-sectional area, thereby adjusting the flow. However, since its sealing line with the valve seat is circular, when adjusting a small flow, a small displacement change may cause a large flow change, and the accuracy is relatively low. The conical valve core is different. Its conical surface cooperates with the valve seat. When adjusting the flow, as the valve core moves, the change of the flow cross-sectional area is relatively linear, and more accurate regulation can be achieved within a wider flow range.
For example, in some precision hydraulic systems with extremely high requirements for flow control, such as the fuel supply system in the aerospace field, a conical valve core design is often used to ensure accurate flow output.
Secondly, the opening form of the valve core is also extremely critical. There are positive opening, zero opening and negative opening. The positive opening valve core has a certain flow area in the middle position. As the valve core moves, the flow rate changes relatively smoothly, but there is a certain leakage in the middle position; the flow area of the zero opening valve core is theoretically zero in the middle position, which can effectively reduce leakage, but the flow regulation characteristics are more sensitive near the middle position; the negative opening valve core is completely closed in the middle position, which can achieve zero leakage, but the flow rate changes greatly at the moment of opening, and the regulation accuracy is poor.
Therefore, according to the specific needs of the hydraulic system, such as the emphasis on leakage and flow regulation accuracy, it is very important to reasonably select the valve core opening form. For example, in general industrial hydraulic systems, if there are certain requirements for leakage and the flow regulation accuracy does not need to be extremely high, a positive opening valve core can be used.
Furthermore, the surface roughness and matching clearance of the valve core have an important influence on the flow regulation accuracy. If the surface of the valve core is rough, when it cooperates with the valve seat or valve body, it will generate additional friction resistance and local turbulence, affecting the stability and regulation accuracy of the flow.
The appropriate matching clearance can ensure that the valve core moves flexibly and seals well. If the gap is too large, leakage will increase and flow will be unstable; if the gap is too small, the valve core may be stuck due to thermal expansion and contraction or the influence of foreign particles, making the flow regulation ineffective. Through precision machining and grinding processes, the surface roughness of the valve core can be controlled within a very small range, and the matching clearance can be ensured to meet the design requirements, thereby improving the flow regulation accuracy.
Finally, with the continuous development of hydraulic technology, higher requirements are placed on the design of valve core structure. For example, the valve core of a hydraulic valve body using electro-hydraulic proportional or servo control technology needs to have fast response and high-precision positioning capabilities. This has prompted the valve core structure design to continue to innovate on the basis of tradition, introducing advanced sensing and feedback mechanisms, so that the valve core can accurately adjust the position according to the electrical signal, and realize dynamic and high-precision regulation of the flow, so as to meet the needs of modern complex hydraulic systems for precise flow control.
