What is the difference between a directional valve and a proportional valve?

Directional valves and proportional valves play different roles in hydraulic systems, and the main differences between them are reflected in their functions and control characteristics.

Directional valves are mainly used to control the flow direction of fluids in hydraulic systems. They usually have two or more working oil ports, and the connection state of the oil ports is changed by the movement of the valve core, thereby controlling the movement direction of hydraulic actuators (such as hydraulic cylinders and hydraulic motors). The operation of directional valves can be manual, electric or hydraulic, depending on the needs of the system.

In contrast, a proportional valve is a valve that can continuously control the flow, pressure or direction of a hydraulic system. Its notable feature is that its output (such as flow or pressure) is proportional to the control input (such as an electrical signal). This proportional relationship enables the proportional valve to accurately respond to changes in the control signal, thereby achieving fine control of the hydraulic system. Proportional valves are usually equipped with electrical components such as electronic amplifiers or proportional solenoids to achieve precise control of the valve core position by electrical signals.

In summary, directional valves are mainly used to control the flow direction of fluid in hydraulic systems, while proportional valves can continuously and accurately control the flow, pressure or direction of hydraulic systems. These two types of valves each have their own unique application scenarios and advantages in hydraulic systems, and the choice of which valve depends on the specific needs and design requirements of the system.