Directional valves are widely used due to their advantages of simple operation, wide application, stability and reliability, but in addition to these advantages, directional valves also have some disadvantages.
1. The structure of the reversing valve is relatively simple, although it is convenient to operate, but there are also limitations, the valve core can only move between the two limit positions, can not be continuously adjusted.
2. The directional valve needs to interact with various forces during operation, and the performance of the internal fluid medium will have a certain impact on these forces, which requires that the medium must have good cleanliness and meet certain viscosity requirements.
3. In order to improve the stability of the system and reduce the impact of load changes on the speed, the hydraulic system is designed to either sacrifice some of the functions we want to achieve, or add additional hydraulic components, such as speed control valves, pressure control valves, etc., to improve the stability of the system by increasing resistance and improving the speed rigidity of the system. However, the addition of such components will reduce efficiency, waste energy, and reduce the possibility and cost of the entire system.
4. Due to the particularity of the commutation structure, the user must purchase the corresponding hydraulic components when realizing a certain function, and the construction machinery manufacturer will design the corresponding function according to different user requirements, which will cause the manufacturer to purchase the same type, multi-specification hydraulic control components to meet the needs of different functional requirements, which is not conducive to product generalization and product management, and will greatly increase product costs.
5. Since the inlet and outlet hydraulic oil of the actuator is controlled by a valve core, it is impossible to control the pressure on both sides of the actuator separately. Therefore, the back pressure of the oil outlet side acts on the opposite direction of the movement of the actuator, and as the back pressure of the oil outlet side increases, the pressure on the oil inlet side must be increased in order to ensure the movement of the actuator. This will increase the function consumed by the hydraulic system, reduce efficiency, and increase heat.
6. The price of the directional valve is relatively high, and the maintenance cost is relatively high, which is not suitable for some occasions with limited economic conditions.
There are still some limitations in the use of directional valves, and in order to ensure the reliability of directional valve operation, we need to continuously improve technology to overcome these birth defects.
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