A novel pump design for an efficient and compact Electro-Hydraulic Actuator IEEE aerospace conference

This paper presents an innovative design solution for a compact Electro-Hydraulic Actuator (EHA). Although the current trend in many mobile applications is towards Electro Mechanical Solutions (EMAS) instead of Hydraulic Actuation systems (HAS), the use of HEAs could represent the best technological compromise. In fact, EHA can combine the power to weight ratio advantage of hydraulic technology with the versatility and ease of control of electric technology. Compared to EMAS, which are often equipped with low efficiency load holding mechanisms, EHAs can also offer superior energy efficiency. The key element of the compact EHA system taken as reference in this study is a miniaturized bi-directional gear pump (from 0.13 cc/rev). The pump design is conceived to maximize performance in terms of efficiency, noise emissions and durability. In particular, a novel pressure compensation system was formulated to minimize power losses associated with the internal lubricating gaps in the whole field of operation. In the considered EHA system, the pump is used to control a differential cylinder in a layout that includes built-in valves to allow control of the actuator according to a power-on-demand strategy. Applications of the proposed EHA includes aircrafts, cargo and vehicle doors, hatches and landing gears. The paper describes the numerical approach used to formulate the new design for gear pump used in the reference EHA. In particular, an optimization procedure based on the use of a detailed simulation model for pressure compensated external gear unit was formulated. Based on the optimal design provided by the optimization procedure, a prototype was realized and tested. Experimental results confirmed the potentials of the proposed design procedure.