Fast-acting electrohydraulic digital transducer. Poppet-type on-off valve by making use of a multilayered piezoelectric device.

Abstract

Intelligent control of an electrohydraulic servo system can be realized comparatively easily by introducing microcomputer. To realize intelligent control systems, it is important to obtain a digital control valve with high transducer-actuator switching speed performance. In the case of a small valve opening, a poppet-type valve has some advantages compared to a spool-type one. The aims of this study are to propose a high-speed displacement control method for the valve poppet and to develop a high-speed digital valve whose switching time is within 100μs. By introducing feed-forward control and providing some improvements, a poppet-type on-off valvd with a high-speed switching response within 70 μs is developed. In application, a two-stage digital servo valve, whose second stage of the spool valve is driven by the high-speed poppet-type on-off valves, is devised.