• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.868-876
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• 1995

This study deals with a position control of an electro-hydraulic servo system which consist of cylinder and high speed on-off valves operated by microcomputer. The merits of PWM control of hydraulic equipment are the robustness of the high spee on-off valve, its low price and the direct control without D/A converter. In the PWM control of high speed on-off valve, the time lag and switching time existing between the input and output signals of valve are considered as demerit points. To get analytical results, the effects of these demerits have to be clarified in detail. The object of this study is to propose a mathematical model for the behavior of high speed on-off valve and to get analytical results of this system. The dynamic characteristics of this system is examined by digital computer simulation analytically and compared with experimental results to varify the proposed mathematical model.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.190-195
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• 2004

An exhaust brake system is composed of a gate valve, a pneumatic cylinder and an on-off solenoid valve. An on-off solenoid valve which is a key component of the exhaust brake system ought to have characteristics such as high reliability and long life for reducing the foot brake and tires damage, and for driver's fatigue relief of middle/large size vehicles running a long distance. In this paper, an on-off solenoid valve which is used for vehicle brake system was studied. For the performance evaluation of the on-off solenoid, electromagnetic characteristics and dynamic characteristics are analyzed. On the basic study for the performance improvement of exhaust brake system, pneumatic circuit and pneumatic valve of on-off solenoid type were suggested and the performance of pneumatic valve through the test procedure was evaluated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1552-1564
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• 2002

Meter-in, meter-out and bleed-off circuits are widely utilized in order to adjust the speed of a hydraulic actuator by using a flow control valve and in order to regulate the pressure of a hydraulic volume by using a simple on-off valve. In these circuits, a relief valve serves either to maintain constant system pressure or to protect the system from over-pressure loading. The relief valve of a bleed-off circuit is the second case frequently undergoing on-off action during operation. It makes the analysis of the pressure control characteristics of the circuit highly difficult. In this paper, steady-state flow rate, pressure, heat loss and efficiency of the three circuits are reexamined and basic experiments far obtaining the characteristics of a pump and relief valve are conducted. Finally, simple empirical first-order dynamic models of decreasing and increasing pressure were separately proposed and verified by comparison with experiment. As the result, the basis for the theoretical analysis of the pressure control characteristics of a bleed-off circuit using a simple on-off valve is established.

• Journal of Power System Engineering
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• v.7 no.4
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• pp.19-24
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• 2003

Exhaust brake system for Diesel engines is composed of gate valve, pneumatic cylinder and exhaust brake valve with on-off solenoid. Exhaust brake valve which is core component of exhaust brake system should have characteristics such as high reliability and long life. In this paper. exhaust brake valve with on-off solenoid which is used for vehicle brake system was studied. For the performance evaluation of on-off solenoid, electromagnetic characteristics and dynamic characteristics are analyzed. As a basic study for the performance improvement of exhaust brake system, pneumatic circuit and pneumatic valve with on-off solenoid were suggested and the performance of the pneumatic valve was evaluated through tests.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.1
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• pp.69-78
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• 1999

In this study a new pattern of pressure control of hydraulic cylinder using high speed On-Off solenoid valve in the electro-hydraulic system has been suggested. The control valve is 3-way high speed On-Off solenoid valve which is operated by PWM(Pulse Width Modulation)control signal. The high speed On-Off solenoid valve has a tendency to induce severe pressure fluctuation in the hydraulic actuator so it has not been used for the purpose of closed loop control with direct pres-sure feedback. In this study closed loop control with direct pressure feedback is enabled by using a digital filter which has linear minimum mean square filter algorithm. Through some experiments it is confirmed that stable pressure control can be realized by the proposed control technique.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.225-230
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• 2002

Machine of textiles let off is equipment supplying constantly fabrics. Nowdays, as it is replaced band - brake type with hydraulic motor driven type, we looked into characteristic of hydraulic solenoid pilot direction valve(SPDV) for controlling acceleration performance of hydraulic motor. This study deals with controlling the initial speed of textiles let off machine. Finally, to control the initial speed of hydraulic motor, we controlled the adjustment screw of SPDV by a hand. Test which was carried out in the laboratory shows that initial speed of textiles let off could be improved by controlling adjustment screw of SPDV. Also, the results of experiment work were compared with dynamic characteristic of other on/off solenoid direction valve(SDV).

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.80-84
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• 2015

In this paper, the valves for a LPG gas cylinder have been investigated on the body height and weight by comparing design data between typical automatic shut-off vertical and newly developed horizontal valves. The height of an automatic shut-off horizontal valve is radically reduced by 41~42% compared with that of a typical automatic shut-off vertical valve. And, the body weight of a horizontal valve is also reduced by 29~40% compared with that of a vertical shut-off valve. This result is just achieved by a structural design modification from typical vertical valve to horizontal arrangement of various valve components.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.820-825
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• 1996

This paper is concerned with effective operating method of pneumatic on-off valves for improving position control accuracy, valve life-time and position settling time using modified pulse width modulation with dead-zone. The pneumatic system using on-off valves studied in this paper has advantage of simple construction and low cost compared with a system with servo-valves. The performance of proposed control system is investigated experimentally for the position control of a pneumatic cylinder using on-off valves. Experimental results show that the proposed algorithm for valve operation can be used to obtain fast and accurate position control and to prevent on-off valves from unnecessary switching.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.70-75
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• 2017

This paper presents the FEM analysis results on the deformation behavior safety of automatic cut-off horizontal and conventional vertical gas valves. Based on the FEM analysis, the primary maximum deformation of $4.4{\mu}m$ was formed on the right end side of a valve body when the internal gas pressure was supplied on the screw port and gas discharge port of an automatic cut-off horizontal gas valve. And the secondary maximum deformation of $2.9{\mu}m$ was formed on the end side of safety valve port. This small deformation of an automatic cut-off horizontal gas valve is strongly related to the balanced design of a horizontal gas valve main body, which is composed of a screw part, gas outlet port, port for a stem and spindle shaft assembly, and safety valve port. But, the primary maximum deformation of 0.076mm was formed on the upper part of a conventional automatic cut-off vertical gas valve when the internal gas pressure was supplied on the screw port and gas discharge port. And the secondary maximum deformation of 0.055mm was formed on the left end side of a gas outlet port. This may effect on the sealing clearance of o-ring that is inserted on the groove of an automatic cut-off unit. Thus, this paper recommends an automatic cut-off horizontal gas valve compared with that of a conventional gas valve for a gas leakage free mechanism of a LPG cylinder valve.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.413-418
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• 2001

Emergency shut-on valve was developed to shut off natural gas at the front of a gas meter in the house. The shut-off flow rate and differential pressure of this valve was controlled by adjusting the distance between the spool and magnet. Also the spool shape was an important factor in the performance of this valve. The experimental and computational results will be useful for the design having better performance.