• International Journal of Fluid Machinery and Systems
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• v.9 no.1
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• pp.28-38
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• 2016

The flexible control system for hydraulic pile hammer using main control valve is present to the requirement of rapidly reversing with high frequency. To ensure the working reliability of hydraulic pile hammer, the reversing performance of the main control valve should commutate robustness to various interfere factors. Through simulation model built in Simulink/Stateflow and experiment, the effects of relative parameters to reverse performance of main control are analyzed and the main interfere factors for reversing performance are acquired. Treating reverse required time as design objects, some structure parameters as control factors, control pressure, input flow and gaps between spool and valve body as interfere factors, the robust design of the main control valve is done. The combination of factors with the strongest anti-jamming capability is acquired which ensured the reliability and anti-jamming capability of the main control valve. It also provides guidance on design and application of the main control valve used in large flow control with interferes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.1
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• pp.39-46
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• 2008

The loss coefficient of the butterfly valve which allows partial opening of the valve at closed position and is applicable to the small-sized pipe system with the diameter of 1 inch was measured for the variation of the valve disk blockage ratio. Two different types of the valve disk configuration to adjust the blockage ratio were considered. One was the solid type valve disk of which the diameter was changed into the smaller size rather than the pipe diameter, and the other was the perforate type valve disk on which some holes were perforated. The results from two types of valve disk were compared to identify their characteristics in the loss coefficient distributions. The loss coefficient and the controllable angle of the valve disk were decreased exponentially with the decrease of the blockage ratio. In addition, the perforate valve disk had the effect on the higher loss coefficient rather than the solid type valve disk.

• Journal of Drive and Control
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• v.10 no.3
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• pp.27-33
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• 2013

Solenoid valve has used in various industrial field extensively. A solenoid valve has different size, shape and method of operation accordantly to industrial field. Many researchers study on kinds of solenoid valve such as flow rate, dynamic, magnetic field, valve shape and operating method. But the flow rate characteristic and dynamic response time performance on the diaphragm valve are not studied. This paper describes the flow rate characteristic and dynamic response time performance on the diaphragm valve. At first, the diaphragm valve is simulated in AMESim simulation tool. AMESim model found that an effect of valve performance depends on parameter. The parameter is the diaphragm orifice area. And the performance test bench confirms the effect in this parameter. Finally, it finds out the flow rate characteristic and dynamic response time performance on the diaphragm valve.

• Journal of Mechanical Science and Technology
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• v.15 no.1
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• pp.66-80
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• 2001

In brake systems, a proportioning valve(P. V), which reduces the brake line pressure on each wheel cylinder for the anti-locking of rear wheels, is closely related to the safety of vehicles. However, it is impossible for current P. V. s to completely control brake line pressure because, mechanically, it is an open loop control system. In this paper we describe an electronic brake force distribution system using a direct adaptive fuzzy controller in order to completely control brake line pressure using a closed loop control system. The objective of the electronic brake force distribution system is to change the cut-in-pressure and the valve slop of the P. V in order to obtain better performance of the brake system than with mechanical systems.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.4
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• pp.5-12
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• 2003

This paper discusses about the thickness effects on the structural durability of a bileaflet mechanical heart valve (MHV). In the study on the design and the mechanical characteristics of a bileaflet mechanical heart valve, the fluid mechanics analysis on the blood flow passing through leaflets, the kinetodynamics analysis on the rigid body motion of the leaflet induced by the pulsatile blood flow, and the structural mechanics analysis for the deformed leaflet are required sequentially and simultaneously. Fluid forces computed in the fluid mechanics analysis on the blood flow are used in the kinetodynamics analysis for the leaflet motion. Thereafter, the structural mechanics analysis for the deformed leaflet follows to predict the structural strength variation of the leaflet as the leaflet thickness changes. Analysis results show that structural deformations and stresses increase as the fluid pressure increases and the leaflet thickness decreases. Analysis results also show that the leaflet becomes structurally weaker and weaker as the leaflet becomes thinner and thinner.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.3
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• pp.131-140
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• 2004

The purpose of this research is to derive the principal design parameters governing the dynamic characteristics of the high response flow control servo valve. For this purpose, a numerical modeling of the servo valve system and a parameter sensitivity analysis to a frequency response characteristics were performed. As a result of these analysis, a basis for improvement of a dynamic characteristics of servo valve was arranged.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.967-973
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• 2004

Electro-pneumatic servo valve is an electro-mechanical device which converts electric signals into a proper pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristics, no air leakage at a null point, and can be fabricated at a low-cost. The first objective of this research is to design and to fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In order to design the mechanism of the servo valve optimally, the flow inside the valve depending upon the position of spool was analyzed variously, and on the basis of such analysis results, the valve mechanism, which was formed by combination of the spool and the sleeve, was designed and manufactured. And a tester for conducting an overall performance test was designed and manufactured, and as a result of conducting the flow rate test, the pressure test and the frequency test on the developed pneumatic servo valve.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1083-1090
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• 1998

A kind of three-way check valve, so called hydraulic calve was proposed for the substitute of the density lock of passive reactor such as SPWR (System-Integrated Pressurized Water Reactor). The function of the valve are the separation of the borated water from main coolant loop for normal operation and the insurge of the water into the loop for shutdown and the removal of the decay power when the main coolant flow rate is not enough. To verify the operability and the characteristics of the valve, experimental works were executed with 1/3 scale model calve. Also a diffuser model was proposed for the theoretical analysis of the valve.

• Journal of Energy Engineering
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• v.21 no.4
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• pp.378-384
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• 2012

Higher compression ratio is required in diesel engine to ignite the fuel that leads to better efficiency. For complete combustion inside the cylinder it is important to ensure the clean air flow with free of debris and as cool as possible. In this manner, modification of intake valve arrangements is taken in to consideration importantly. In this paper, the intake valve arrangements are modified with newly designed valve mixer. It causes swirl flow of air through the intake port that mixing with the fuel followed by complete combustion. The use of valve mixer reduces the carbon sediment formation on valve fillet and its face area as the carbon particles gradually take place on it after certain running period. It therefore, helps to increase the valve lifetime. And at the same time it reduces the exhaust elements i.e. soot from the automobiles to a significant level.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.2
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• pp.166-174
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• 1999

The flow characteristics of 2-valve and 4-valve cylinder heads with various blocked-valve were experimentally investigated in a steady flow rig. Effects of the blocked-valve configurations on flow coefficient, swirl and tumble intensity are studied. Compared to the conventional valve, the blocked valve in both cylinder heads have the much lower flow coefficient and the much higher intensity of swirl and tumble. Under the same size of blockage, the value of flow coefficient and swirl(or tumble) intensity were varied according to the position of blockage. Throughout these steady flow test the optimized positions of blockage in both cylinder heads were determined.