• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1215-1216
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.486-489
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• 2003

To reduce lateral force of traditional plunger type piston in the swash plate type hydraulic piston pumps and motors, we have proposed rod type piston with ball joint on both ends. We have studied the theoretical reaction force on two types of piston moving in the cylinder block bore. and made an experiment for the resistance force measurement on a reciprocating motion of plunger and rod type piston, changing the test condition such as swash plate angel and supply oil pressure and so on. As a result. a rod type piston has more smaller resistance force, about 29%. than a plunger type one.

• Journal of Power System Engineering
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• v.15 no.2
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• pp.5-12
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• 2011

In this study, modeling and numerical simulations has been performed to investigate performance characteristics of constant power regulator system for swash plate type axial piston pump. The commercial numerical simulation software, AMESim was applied for analyzing the dynamic behavior of constant power regulator system of swash plate axial piston pump. The validity of simulation model of constant power regulator system is verified by comparing simulation results with experiments. Also, the behavior of main components of constant power regulator system such as spool, sleeve and counterbalance piston is investigated using the results of computer simulation.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.237-242
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• 2009

A steam Rankine cycle was considered to recover waste heat from the exhaust gas of an automobile. Conceptual design of a swash plate type expander was practiced to convert steam heat to shaft power. With the steam pressure and temperature of 35 bar and $300^{\circ}C$ at the expander inlet, respectively, the expander was estimated to produce the shaft power output of about 1.93 kW from the exhaust gas waste heat of 20 kW. The expander output increased linearly accordingly to the amount of exhaust gas waste heat in the range of from 10-40 kW, and the Rankine cycle efficiency was more or less constant at about 9.6% regardless of the waste heat amount.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.741-744
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• 2002

The closed circuit pump is applied to control rotating speed and direction of hydraulic motor in hydrostatic transmission. To development of this pump, first of all the servo control regulator has to be designed. Mechanical-hydraulic type servo control mechanism is excellent to be compared with electronic-hydraulic type servo control valve to reliability and economy. In this paper to development positive and negative variable displacement type servo regulator, the hydro-mechanical servo control mechanism is calculated and designed with force balance of pilot piston and position feedback of servo piston.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.5-9
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• 2011

The hydraulic piston using a hydrostatic bearing has been used widely due to its satisfying performance at very high pressurized circumstance and relative higher power density in comparison to conventional one. For high pressurization, enhanced efficiency and long durability of the hydraulic piston, the design of hydrostatic bearing is at issue, which is installed between piston shoe and swash plate. The performance of the hydrostatic bearing is influenced significantly by the assembly of the piston shoe consisting of circular land and recess. In this study, to estimate the performance of the hydrostatic bearing, the characteristics for lubrication of the assembly of the piston shoe were investigated by measuring a leakage rate of hydraulic fluid under an experimental condition, where a rotating velocity of the piston, hydraulic pressure and temperature of the hydraulic fluid were changed systematically. In addition, a film thickness of the hydraulic fluid on the piston shoe was measured and compared to theoretical one.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.2
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• pp.78-88
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• 1991

The existing axial piston pump/motors of swash plate type rapidly drop efficiency in high speed region in comparison with low speed. This is the reason why the pump/motors were designed only in a view point of power supply. But, in this paper, the motor which was optimally designed on power supply load capacitancy, flow loss volume, axial stiffness and tiliting stiffness keeps up high efficiency in high speed region and in high pressure resion too.

• Journal of Drive and Control
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• v.13 no.3
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• pp.86-90
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• 2016

• Journal of Drive and Control
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• v.1 no.3
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• pp.26-31
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• 2004

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.4
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• pp.291-298
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• 2013

In this paper a new hybrid-type control system is proposed which reduces the pump speed of an electro-hydraulic actuator consisting of a pressure-compensated variable displacement piston pump and a valve-controlled hydraulic cylinder, whenever the flow rate demand is low. In order to avoid interfering with the pressure regulator which also has an effect on swash plate angle, the pump speed is changed in proportion to the mean value of the speed component of position commands. Additionally a pressure switch is employed to prevent the system pressure from getting lower than a reference value. Based on computer simulation & experimental results, it is shown that the hybrid control can save the idling power up to 44% at a stand-by mode by reducing the pump speed from 1,800 rpm to 600 rpm without affecting the dynamic response of the electro-hydraulic actuator.