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Hybrid electric-hydraulic actuator promises the best of both

04 January, 2012

At the recent SPS/IPC/Drives show in Germany, Moog demonstrated a prototype electrohydrostatic actuator (EHA) that combines hydraulic and electric technologies and avoids the mechanical screws and gearing usually needed for purely electric actuators. Unlike conventional hydraulic actuators, the EHA needs no hydraulic piping, thus cutting costs and improving reliability.

The actuator (shown above) taps Moog’s electrical and hydraulics expertise that it has been applying to aircraft flight controls for more than 18 years. The company now hopes to transfer this expertise to industrial applications that need high forces and redundant or failsafe operation, while also delivering energy, cost and environmental benefits.

Moog says that the EHA technology will offer machine-builders high efficiency and reliability, space savings, reduced wear, and weight savings of up to 40%. It also avoids the need for long hydraulic lines and rotary couplings, while the integrated design improves reliability because fewer components are needed. Redundancy and failsafe functions are built in.

The actuator is aimed, in particular, at low duty-cycle or actuation-on-demand applications that need the high force density typical of hydraulic systems. By operating the electric system only when needed, energy consumption is reduced.

The self-contained actuator integrates hydraulic and electric components including a servomotor, hydraulic pump and valves, a manifold, an accumulator, a controller and software. It uses fluid to transmit power from the motor to the actuator. The motor rotates only when movement is needed, saving energy and reducing wear. The hydraulic components and fluid are contained within the assembly, eliminating the danger of leaks and environmental contamination.

“The motion control industry is seeking new technologies that address the need for better energy efficiency and reliability at lower weight and size,” says Dr Sherif El Henaoui, Moog Industrial’s European marketing manager. “Smart systems like EHA hybrid technology offer a new and innovative solution suited to a range of industrial applications.”

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