Electro-Hydrulic Proportional Control Systems

This thesis is concerned with studying the performance of two-relief valves, namely an ordinary pilot relief valve and proportional pilot relief valve.The proportional pilot relief valve is a new type of relief valve, which is characterized by controlling the pressure and reducing the pressure peaks. Thus, the proportional pilot relief valve protects the hydraulic components from pressure transient and can allow the use of higher operating pressure without causing fatigue failure to these components.Two mathematical models are developed to study the dynamic and static behaviors of the two valves under consideration. Using these models, the behaviors of the two valves are simulated using the SIMULINK software package.Finally, a mathematical models is developed to study the dynamic behaviors of the simple hydraulic press circuit using proportional pilot relief valve, this system is simulated using the SIMULINK software package.And it was concluded that the static characteristics for the proportional relief valve is better than it in ordinary ones and dynamic characteristics for the ordinary relief valve is better than it in proportional ones and it can be improved by changing the dimensions of the used valve for the proportional to fit the required dynamic performance