Development of a Fast Seat Type Switching Valve for Big Flow Rates

Advancements of hydraulic systems are necessary to keep them competitive with other drive systems. Two major topics for further improvements in hydraulics are energy efficiency and increased performance. High accuracy and fast systems, for instance for fast and precise positioning tasks, mostly can only be realized by the use of big servo valves. Such valves are costly and, moreover, their working is based on the resistance principle, which causes considerable losses. A promising method to achieve the mentioned goals is the use of fast and big switching valves. Former investigations showed that switching valves with flow rates of about 100 l/min at 5 bar and switching times of 1 to 2 ms can meet these requirements. Commercial switching valves fail on achieving such demands. After the successful development of a spool type switching valve a seat type switching valve has been developed which fulfills the mentioned requirements on switching time and flow rate. The valve is actuated hydraulically by a pilot valve. The high flow rate was realized by a simple arrangement of several coaxial metering edges. The fastest switching time which depends on the pressure drop is about 1.5 ms. Its seat valve properties make it highly suitable for emergency applications and mobile hydraulic applications were absence of leakage is required.