• Journal of Biosystems Engineering
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• v.36 no.2
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• pp.89-95
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• 2011

Tractor implements are mainly utilized for the tillage operation. The proposed hydraulic system control was implemented to experimental apparatus. An implement control system for tractor using proportional valve was fabricated to improve the working efficiency. Hydraulic circuit included the proportional solenoid valve and on/off solenoid valve and so on. This paper shows results of a specification and design of an implement control system for tractor using proportional valve for automation. It was conducted to evaluate response characteristics of the designed implement control system under experimental conditions of various input flow rates. The results of experiments showd that the response characteristics was sufficient to be used as the implement control system.

• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.3
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• pp.1-5
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• 2005

There are two types of solenoid actuator for force and position control of the fluid power system. One is an on-off solenoid actuator and the other is an electro-magnetic proportional actuator. They have some different characteristics for attraction force according to solenoid shape. Attraction force of the on-off solenoid actuator only depends on flux density. And the stroke-force characteristics of the proportional solenoid actuator are determined by the shape of the control cone. In this paper, steady state characteristics of the solenoid actuator for electro-hydraulic proportional valve determined by the shape of control cone are analyzed using finite element method and it is confirmed that the proportional solenoid actuator has a constant attractive force in the control region independently on the stroke position. And the shape of control cone is optimized using 1+1 evolution strategy to get a constant force. In the optimization algorithm, control cone length, thickness and taper length are used as a design parameter.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.99-104
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• 2001

In this study, selecting methods of the hydraulic valve and evaluation item for development of reliability testing standard are c]early defined. And, we developed reliability testing standard of the hydraulic valves which are as follows, - Hydraulic directional control valve, - Hydraulic on-off solenoid valve - Hydraulic PWM valve, - Hydraulic check valve, - Hydraulic relief valve, - Hydraulic reducing valve, - Hydraulic flow control valve

• Journal of the korean Society of Automotive Engineers
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• v.14 no.4
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• pp.50-60
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• 1992

Flame characteristics of periodic fuel jets were studied experimentally by supplying the fuel periodically using solenoid valve. Flame was observed using a high speed camera, a 35 mm camera and a cathetometer. Hot-wire ananometer was used to meature the speed of fuel flow at the nozzle exit to analyze the flow characteristics. Various types of flame characteristics such as the flame lift-off and extinction were observed for different ranges of period, duty, and flow rate, but the flame shape was not affected much by the variation in the flow rate. Decreasing duty of the pulses applied to the solenoid valve promotes lift-off and enhances premixed flame characteristics.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.200-203
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• 1997

This paper describes an study electric injection system for diesel engines. It is needed effective fuel injection which controls the solenoid valve of fuel pump. To solve this, this paper proposes DCC-PWM method which can realize fast reply and low holding current for solenoid valve on/off. For the proposed design method, simulation tools of ACSL are used to analyze the system. And the single-chip microcomputer is used to reduce the size of controller and to improve flexibility. And the system's validity can be verified through the experimental results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1469-1478
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• 1995

PWM control is a kind of nonlinear control. The merits of PWM control of hydraulic equipment are the robustness of the high speed on-off valve and its low price. And it is easily implemented to hydraulic equipments with microcomputer. The high speed on-off valve is directly digitally controlled without any D/A converter. The objectives of this study is to analyze the limit cycle which regularly appear in the position control system using high speed on-off valve, and to give a criterion for the stability of this system. To do this, the nonlinear characteristics of PWM and cylinder friction of this system are described by harmonic linearization and the effects of parameter variations to the system stability are examined theoretically and experimentally. Consequently, the availability of the proposed method is confirmed well.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.3
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• pp.38-44
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• 2003

The solenoid valve in ABS hydraulic modulator is a two directional on-off valve and is controlled by around 100Hz high speed pulse width modulation. When the valve is switched from open state to closed state, noise and vibration due to pressure surge phenomena in the hydraulic line and wheel cylinder are made. In this study, we identify Pressure surge phenomenon in the braking process of a ABS, and investigate the way to reduce the phenomenon. For the purpose of theoretical analysis on the pressure surge in the closed state hydraulic line, characteristic curve method based on wave equation was utilized. To reduce the surge, high frequency control of 20kHz was attempted. The result showed that the surge pressure of 50% was reduced compared to one observed in the low frequency control. Duty variation of high frequency can control current of solenoid valve and prevent sudden change of displacement.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.364-369
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• 1987

It has recently shown that a solenoid valve can be utilized in a hydraulic position-control system by discontinuous control methods. The objective of this study is to investigate the effects of solenoid valves on the response characteristics of a hydraulic position-control system by applying two kinds of discontinued control methods i.e., Simple On-Off (SOF) and Pusating On-Off(POF) controls. Three types of solenoid valves i.e. low-frequency, closed-center type (LF/C), high-frequency, closed-center type (HF/C), low-frequency, tandem-center type(LF/T) were used in this study. Effects of loading conditions and control parameters on the response characteristics were experimentally examined and compared each other. Pressure transients within the actuator were also studied.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.85-91
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• 1998

This paper describes an study electric injection system for diesel engines. It is needed effective fuel injection which controls the solenoid valve of fuel pump. To solve this, this paper proposes DCC-PWM method which can realize fast reply and low holding current for solenoid valve on/off. For the proposed design method, simulation tools of ACSL are used to analyze the system. And the single-chip microcomputer is used to reduce the size of controller and to improve flexibility. And the systems validity can be verified through the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.285-290
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• 2005

Micro On-Off valves are currently recognized as the core technology in the fields of the micro fluid chip fur medical applications and production lines of semi-conduct chip. Micro valves that operate by compressed air need the high-speed responsibility, repeatability, the absorbability and the uniform pressure by the poppet. In this study, Micro On-Off valves that posses the high-speed responsibility and the high rate of flow have designed and analyzed through the law of equivalent magnetic circuit and Finite Element Method (FEM) respectively. In case of poppet, Flow field characteristic was analyzed by the variation of poppet and it was able to display flow field by changing the location of the poppet. Also, we verified possibility of the design through the static and dynamic pressure and the 3D distribution curve of the force by working the front poppet.