The combined digital electro-hydraulic valve used in the belt conveyer hydraulic pressure soft-start system

In order to improve the start condition of the long-distance, large-capacity belt conveyor, soft-start device based on a oil-film Clutch controlled by the hydraulic system which is used to regulate the film thickness of the oil-film clutch is widely used. In the paper a kind of combination digital valve was designed for improving the control precision and unfailing performance of the soft-start device. Based on pulse code modulation principle, the combination digital valve which is made of many on-off valves has a lot of advantage such as being simple in structure, good in anti-pollution and cheap, so it is suitable for application in electro-hydraulic servo system control by the computer of some large-scale mining machinery equipment like the long-distance belt conveyer.