• Journal of Drive and Control
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• v.16 no.2
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• pp.15-21
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• 2019

In this study, the maximum system efficiency of the electro-hydrostatic actuators was experimentally investigated, where small size external gear pumps with volumetric displacement under 1.3 cc/rev were combined with a 400W servomotor as the prime mover. Since the efficiency data of the servomotor, gear pumps and hydraulic cylinder were not provided by the suppliers, experimental apparatuses for their efficiency measurement were extra built up. When a gear pump with a volumetric displacement of 1.27cc/rev was used on an electro-hydrostatic actuator system, the maximum system efficiency was not higher than 70%. This was because the most effective operation ranges of the motor and pump did not coincide each other. In order to match their operation ranges as one of the most crucial design factors, a speed reduction mechanism can be used, such as a timing belt. It was shown in the study that the maximum system efficiency could be increased from 70% to 76% in that way.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.6
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• pp.89-102
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• 2010

In this paper, a study on the future-oriented actuator introduces the future technology and future direction in aerospace and several industry fields. In particular, the mechanical linkage or hydraulic and pneumatic actuators which have the higher output-to-weight ratio have been used a lot in the past as the aircraft's flight control device. Most recently, Fly-By-Wire system has been used in aircraft and the flight control system has been changed in more electric and all electric systems. Electrohydraulic actuators and electric actuators have been developed continually, because they have better efficiency, safety and lower cost for the flight control system of aircraft. Also, to improve the weight condition, accuracy and response of actuator, new field actuators using new materials have been developed. In this paper we clearly proposed the actuator design and detailed technology development trend for next generation actuation system in aerospace and new field.

• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.3
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• pp.7-13
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• 2004

The hydraulic pump for a Electro-hydrostatic Actuator for aircrafts should be able to quickly feed large volume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil by low-speed operation so that the steady state position control error of the EHA can be accurately compensated. This paper is focused on the investigation how the plasma coating surface treatment of cylinder barrel with CrSiN can contribute to the reduction of low-speed friction torque of a bent-axis type piston pump. The results showed that the reduction of the friction torque was not remarkable, but that the anti-wear characteristics of the CrSiN-coated cylinder barrel were much better that those of the original one.