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Hong Yeh-Sun,Lee Sang-Yul,Kim Sung-Hun,Lim Hyun-Sik The Korean Society of Mechanical Engineers 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.3
The hydraulic pump of an Electro-hydrostatic Actuator 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 through low-speed operation so that the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and wear rate of valve plate in the low-speed range with mixed lubrication. The results showed that the friction torque of the valve plate mated with a TiN coated cylinder barrel could be reduced to 22% of that with an uncoated original one when load pressure was 300 bar and rotational speed 100 rpm. It means that the torque efficiency of the test pump was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to $40\sim50%$.
Analysis on the Friction Losses of a Bent-Axis Type Hydraulic Piston Pump
Yeh-Sun Hong,Yoon-Ho Doh 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.9
he design of an axial piston pump for electro-hydrostatic transmission systems requires accurate information where and how much the internal friction and flow losses are produced. This study is particularly focused on the friction losses of a bent-axis type hydraulic piston pump, aiming at finding out which design factors influence its torque efficiency most signiTo this end, the friction coefficients of the pump parts such as piston heads, spherical joints, shaft bearings, and valve plate were experimentally identified by a specially constructed tribometer. Applying the experimental data to the equations of motion for pistons as well as to the theoretical friction models for the pump parts, the friction torques produced by them were computed. The accuracy of the computed results was confirmed by the comparison with the practical input torque of the pump. In this paper, it is shown that the viscous friction forces on the valve plate and input shaft bearing are the primary source of the friction losses of the bent-axis type pump, while the friction forces and moments on the piston are of little significance.
Hybrid Constant Pressure Control of a Swash Plate Type Axial Piston Pump
Yeh-Sun Hong,Jong-Hyeok Kim 유공압건설기계학회 2015 유공압건설기계학회 학술대회논문집 Vol.2015 No.10
In this paper both the volumetric displacement and the shaft speed of a variable displacement swashplate type piston pump were varied in order to minimize power consumption in supplying constant-pressure oil to a valve-controlled hydraulic cylinder, particularly during idle modes. At operating modes which were triggered by position command inputs, the pump speed was varied by a pressure control algorithm to maintain a constant system pressure, with the swash plate angle fixed at the maximum. At idle, with no position controller input signal and the system pressure greater than or equal to the reference value, the swash plate angle and pump speed were lowered to their minimum limits. Computer simulation and experimental results showed that the idling power could be reduced by up to 83% by reducing the pump speed from 1800 rpm to 300 rpm and the swash plate angle to 3°, compared to a conventional system consisting of a pressure-compensated variable displacement type pump driven at a constant speed of 1800 rpm.
Design of a Two-Dimensional Proportional Solenoid for Miniature Directional Control Pneumatic Valves
Yeh-Sun Hong,Dong-Hyun Ha,Myung-Ki Yeom 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.7
In this paper, a new proportional solenoid invented for pneumatic directional control valves is introduced. The new proportional solenoid has two-dimensional structure and a pivoting armature on which the friction force is inherently negligible. Another advantageous feature of this solenoid is that its mechanical parts can be easily manufactured and assembled. The working principle and design example of the now proportional solenoid. its application to the activation of a 4/3-way directional control valve, and the evaluation of its control performance in a position control loop are reported.
Electromagnetic Analysis of a Flat-Type Proportional Solenoid by the Reluctance Method
Yeh-Sun Hong,Yong-Cheol Kwon 한국정밀공학회 2006 International Journal of Precision Engineering and Vol.7 No.2
In this study, the electromagnetic characteristic of a flat-type two-dimensional proportional solenoid were analyzed by the magnetic reluctance method. The magnetic equivalent circuit equation for the solenoid was derived by modeling the reluctance of air gaps and magnetic structural components such as pole core, armature and yoke. It was solved iteratively because of the nonlinear magnetization properties of iron parts. The solutions showed good agreement with experimental data. Based on the magnetic equivalent circuit equation, the influence of design parameters on force-to-armature displacement curves was mathematically derived and experimentally verified. In this way, dominant design parameters could be analytically determined.
Design of a Two-Dimensional Proportional Solenoid for Miniature Directional Control Pneumatic Valves
Hong, Yeh-Sun,Ha, Dong-Hyun,Yeom, Myung-Ki The Korean Society of Mechanical Engineers 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.7
In this paper, a new proportional solenoid invented for pneumatic directional control valves is introduced. The new proportional solenoid has two-dimensional structure and a pivoting armature on which the friction force is inherently negligible. Another advantageous feature of this solenoid is that its mechanical parts can be easily manufactured and assembled. The working principle and design example of the now proportional solenoid, its application to the activation of a 4/3-way directional control valve, and the evaluation of its control performance in a position control loop are reported.
Electromagnetic Analysis of a Flat-Type Proportional Solenoid by the Reluctance Method
Hong, Yeh-Sun,Kwon, Yong-Cheol Korean Society for Precision Engineering 2006 International Journal of Precision Engineering and Vol.7 No.2
In this study, the electromagnetic characteristic of a flat-type two-dimensional proportional solenoid were analyzed by the magnetic reluctance method. The magnetic equivalent circuit equation for the solenoid was derived by modeling the reluctance of air gaps and magnetic structural components such as pole core, armature and yoke. It was solved iteratively because of the nonlinear magnetization properties of iron parts. The solutions showed good agreement with experimental data. Based on the magnetic equivalent circuit equation, the influence of design parameters on force-to-armature displacement curves was mathematically derived and experimentally verified. In this way, dominant design parameters could be analytically determined.
Yeh-Sun Hong,Sang-Yul Lee,Sung-Hun Kim,Hyun-Sik Lim 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.3
The hydraulic pump of an Electro-hydrostatic Actuator 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 through low-speed operation so that the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and were rate of valve plate in the low-speed range with mixed lubrication. The results showed that the friction torque of the valve plate mated with a TiN-coated cylinder barrel could reduced to 22% of that with an uncoated original one when load pressure was 300 var and rotational speed 100 rpm. It means that the torque efficiency of the test pump was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to 40~50%.
Analysis on the Friction Losses of a Bent-Axis Type Hydraulic Piston Pump
Hong, Yeh-Sun,Doh, Yoon-Ho The Korean Society of Mechanical Engineers 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.9
The design of an axial piston pump for electro-hydrostatic transmission systems requires accurate information where and how much the internal friction and flow losses are produced. This study is particularly focused on the friction losses of a bent-axis type hydraulic piston pump, aiming at finding out which design factors influence its torque efficiency most significantly. To this end, the friction coefficients of the pump parts such as piston heads, spherical joints, shaft bearings, and valve plate were experimentally identified by a specially constructed tribometer. Applying the experimental data to the equations of motion for pistons as well as to the theoretical friction models for the pump parts, the friction torques produced by them were computed. The accuracy of the computed results was confirmed by the comparison with the practical input torque of the pump. In this paper, it is shown that the viscous friction forces on the valve plate and input shaft bearing are the primary source of the friction losses of the bent-axis type pump, while the friction forces and moments on the piston are of little significance.