• 한국유체기계학회 논문집
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• 제16권5호
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• pp.29-35
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• 2013

Butterfly valve seated rubber has been widely used in water works and industrial fields because it has advantages which are small installation area and low weight. The size and material of butterfly valve have been selected by service environments and purposes. But there are out of the ordinary to find papers for the life characteristics of the butterfly valve. So, this study carries out the accelerated life test, which has an acceleration factor with pressure, using performance and life test equipment. Accelerated model is adopted with 3 stress level and the inverse power law model to estimate the life of the test samples. After the analysis of the test result, accelerated index has 7.0 and the acceleration factor has 208 which is applied with field condition with the pressure 6.3 bar.

• 한국분말재료학회지
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• 제10권2호
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• pp.89-96
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• 2003

The recent trend of miniaturization and high performance of vehicle engines has put an urgent necessity for the development of valve seats which can operate under more severe conditions. In order to develope valve seat material that has the most excellent wear resistance at operating temperature of engine through improvement of the progress of work. the effects of mixing ratio of the milled powder on sintered and Cu-infiltrated properties of sintered valve seats have been studied. The resultant radial crushing strength and hardness of sintered specimens were gradually increased with increasement of volume of milled powders. It is because increasement of sintering density by increasing of surface diffusion. The hardness of Cu-infiltrated specimens became lower than that of the commercial powders as the increasement of volume of milled powders. It was due to the decrease of the amount of the martensite. By results of this research, It has been found that martensite is formed around of the Cu-infiltrated site and the decrease of the amount of the martensite is due to decrease of the amount of the Cu-infiltrated site by the decrease of gas channel.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.42-50
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• 2001

In this paper, the effects of scale formation in engine water jacket upon the thermal durability of engine itself and its component parts were studied. To understand the effect of quality of water, a full load engine endurance test for 50 hours was carried out with not-treated underground water. The followings were found through the tested engine inspection after the endurance test; 1-2 mm thick scale formation in the engine water jacket, valve seat wear, piston top land scuffing, piston pin stick, and cylinder bore scuffing in siamese area. In order to understand the causes of above test results, the heat rejection rate to coolant, the metal surface temperature of combustion chamber, and the oil and exhaust gas temperatures were measured and analyzed. The scale formed in the engine water jacket played a role as thermal insulator. The scale formed in the engine reduced the heat rejection rate to coolant and it caused to increase the metal surface temperature. The reduced heat rejection rate to coolant increased the heat rejection rate to oil and exhaust gas and increased the oil and exhaust gas temperature. Also, the reasons of valve seat wear, piston top land scuffing and cylinder bore scuffing, and piston pin stick quantitatively analyzed in this paper.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.921-927
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• 2001

Steady flow bench test is a practical, powerful and widely used test in most engine manufacturers to give a design concept of a new engine. In order to use steady data as a performance index, it is necessary to build some database, which can correlate the port characteristics with engine data. However, it is very hard to investigate all port and valve shapes with experimental tools. The steady flow scheme is relatively simple and its results are bulk ones such as flow rate and momentum of flow. Therefore a CFD code can be easily applied to the port evaluation. In this study, the steady flow test was simulated through two and three-dimensional analysis on intake port design for comparing with experimental data and confirming the feasibility of applying analytic method. For this purpose, the effect of valve curvature on flow rate was estimated by a CFD code. There results were compared with those of real steady flow tests. As a result, the 2-D analysis described the phenomena qualitatively well, and also the results of 3-D analysis were almost consistent with experimental data.

• 한국해양공학회지
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• 제23권1호
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• pp.140-145
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• 2009

This paper deals with a stability evaluation of a butterfly valve using the body and disc of a valve seat. The experimental results of a strength evaluation are shown using STS316 stainless steel and spheroidal graphite cast iron (GCD450). The disc material was made from GCD450. The results of the strength analysis are as follows: Ultimate tensile strength 485MPa, Yield strength 370 MPa, Young's modulus $1.1{\times}10^5$, and Poisson's ratio v = 0.28. For the results of the disc analysis, the safety factor was about 4. This shows that a design was derived that satisfied the requirements of structural safety. However, some problems, such as the deflection and deformation of the disc, may occur when the sea water has back flow with a high pressure.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.1-8
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• 2004

In this paper we present the effects that valve train design parameters and operating conditions have on the valve rotation properties of a diesel engine. Rotation of intake and exhaust valves are very closely related to the long term durability of diesel engines. of the valves do not rotate even at a rated engine speed, it causes the uneven wear of the valve seat and valve head contact area, which eventually shortens the engine life. Because the rated speed of a diesel engine is relatively lower than that of a gasoline engine, the operating condition of a diesel engine produces tough environment for valve rotation. Therefore, the valve rotation is an important problem which should be solved in the early stage of engine development. In this study, we developed a new technique to measure the valve rotation and shaking motion simultaneously using three proximity sensors. Valve train rotating properties of a diesel engine were measured under various engine operating conditions.

• 한국정밀공학회지
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• 제21권3호
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• pp.100-108
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• 2004

Contamination of environment induces the shortage of drinkables. In this trend, the leakage of water that occurs by breakage or erosion of rubber valve seats is serious problem. Rubber is apt to cause breakage between two materials when they contact with each other. The possible way to avoid leakage of water by damage and breakdown of rubber is to replace that with metal. Because of this reason, nowadays, rubber is being substituted with metal as valve seat materials for water works. In tribology, a severe from of wear is characterized by local, macroscopic material transfer, removal, or formation of surface protrusions when two solid surfaces experience relative sliding under load. One of the major problems in sliding of metals is galling due to bad surface quality. Experimentally, there are various elements which influence on incipient galling, such as hardness, surface roughness, temperature, load, velocity and external environments. This paper is aimed at verifying the galling tendencies according to hardness, surface roughness, load and velocity and showing how much effect the factors have on the galling tendencies.

• 한국분말재료학회지
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• 제26권2호
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• pp.112-118
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• 2019

Infiltration is a popular technique used to produce valve seat rings and guides to create dense parts. In order to develop valve seat material with a good thermal conductivity and thermal expansion coefficient, Cu-infiltrated properties of sintered Fe-Co-M(M=Mo,Cr) alloy systems are studied. It is shown that the copper network that forms inside the steel alloy skeleton during infiltration enhances the thermal conductivity and thermal expansion coefficient of the steel alloy composite. The hard phase of the CoMoCr and the network precipitated FeCrC phase are distributed homogeneously as the infiltrated Cu phase increases. The increase in hardness of the alloy composite due to the increase of the Co, Ni, Cr, and Cu contents in Fe matrix by the infiltrated Cu amount increases. Using infiltration, the thermal conductivity and thermal expansion coefficient were increased to 29.5 W/mK and $15.9um/m^{\circ}C$, respectively, for tempered alloy composite.

• 한국가스학회지
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• 제17권3호
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• pp.14-19
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• 2013

본 연구에서는 특수가스용기용 밸브의 안전성에 관한 실험적 연구를 수행하였다. 시험용 밸브는 특수가스용기에 부착되었던 것을 무작위로 수거한 것으로 가스누출 및 작동 안전성에 대한 시험을 실시하였다. 실험결과에 의하면, 밸브의 몸체, 나사 체결부, 안전판, 방출구, 스템부, 핸들에서 가스누출 안전성에 영향을 미칠 정도의 크랙, 마모, 부식, 변형이 발생하지 않았다. 다만, 핸들의 페인트 일부가 벗겨지고, PT나사와 몸체에서 녹이 국부적으로 형성되어 있지만, 가스누출 안전성에 영향을 미칠 정도는 아니었다. 또한, 탈거한 밸브에서 가스누출은 발생되지 않았다. 다만, 밸브스템의 영구변형과 오링의 마찰표면 일부에서 손상이 관찰되었다. 따라서, 탈거된 밸브의 가스누출 안전성을 보장하기 위해서 밸브시트와 오링 교체하는 것이 바람직함을 알 수 있다. 또한, 핸들의 조임력을 주기적으로 점검하는 것이 필요함을 알 수 있었다.