Designing redundant metering valves for hydraulic actuators under mixability and low cost-constraints

Abstract

This article deals with the design of redundant metering valves for mechanically signalled hydraulic actuators. The final aim of the work is to manufacture a new low-cost valve in replacement of the existing expensive valve with an additional leakage requirement in case of seizure. The new valve must ensure the same closed-loop behaviour of the actuator. The article presents the design of the valve according to the actuator specifications and to a criterion of mixability (capacity to replace the existing valve by a new one). The valve pre-design is based on the common sharp edges and rectangular orifice slots combined with a serial restrictor inserted on the supply line. After partial experimental validation, the proposed design process points out the interest of using a trapezoidal slot in order to get the required speed gain over the whole valve opening range. The proposal is validated through the experimental measurement of the actuator no-load speed as a function of the valve opening.