• Title/Summary/Keyword: Composite piston

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A Study on the Gas Leakage and Friction of the Self-lubricating Piston Seal Rings (자체 윤활 피스톤 씨일 링의 가스 누출과 마찰에 대한 연구)

  • 심현해;권오관;이규한;김병환;임윤철
    • Tribology and Lubricants
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    • v.12 no.4
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    • pp.7-12
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    • 1996
  • Present study was undertaken to investigate the leakage and friction of self-lubricating piston seal rings. A crank-piston type gas leakage test set-up was constructed. The piston rings were made of PTFE-polyimide composite. The free gap configurations of the seal rings were butt and step types. Eccentric tension rings were used to give the seal rings prepressure between the seal rings and cylinder wall. Two sizes of the tension rings were installed to investigate their effect on the gas leakage and friction of the seal rings. The results showed that step type seal rings are superior than the butt types. High tension spring rings resulted in low leakage and high friction loss. In order to reduce the gas leakage and friction loss of the piston seal rings, there should be compromise between the number of ring stages and prepressure of the tension rings.

Durability Design of Composite Piston in Marine Diesel Engines (박용 디젤엔진용 분리형 피스톤의 내구설계)

  • Son, Jung-Ho;Ha, Man-Yeong;Ahn, Sung-Chan;Choi, Seong-Wook
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.5
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    • pp.651-657
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    • 2010
  • A composite piston with a crown made of steel and a skirt made of NCI is used in a marine diesel engine, which has a maximum firing pressure of over 180 bar and a high thermal load. In the fatigue design of the composite piston, the fatigue is influenced by factors such as the load type, surface roughness, and temperature; further, the distribution ratio of the firing force from the crown to the skirt is important for optimizing the design of the crown and skirt. In this study, the stress gradient method was used to consider the effect of the load type. The temperature field on the piston was predicted by cocktail-shaking cooling analysis, and influence of high temperature on fatigue strength was investigated. The load transfer ratio and contact pressure were optimized by design of the surface shape and accurate tolerance analysis. Finally, the cooling performance and durability design of the composite piston were verified by performing a long-term prototype test.

피스톤 형상과 틸팅에 따른 피스톤 펌프의 윤활특성

  • 박태조;전병수
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1997.04a
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    • pp.142-150
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    • 1997
  • A numerical analysis is carried out to study the effect of piston shape on the lubricaton characteristics between the cylinder and piston in hydraulic piston pump. The shapes of piston affect significantly the pressure distributions, the lateral force and leakage flowrate. Composite shaped piston is more effective than other shapes which not only reduces the possibility of hydraulic locking but improves the volumetric efficiency of the piston pump.

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Effect of Piston Shape on the Lubrication Characteristics of Hydraulic Piston Pump and Motor (피스톤 형상이 유압피스톤 펌프$cdot$모터의 윤활특성에 미치는 영향)

  • 이정오;박태조
    • Tribology and Lubricants
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    • v.10 no.3
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    • pp.47-53
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    • 1994
  • Thin film flow in the clearance between cylinder bore and axially moving compositeshape piston is analyzed to study the effect of piston shape on the lubrication characteristics of hydraulic piston pump and motor. It is shown that the piston shape significantly affect the distribution of fluid film pressure, lateral force acting on the piston and leakage flow rate in the clearance. And it is also shown that the composite-shape piston is more effective than the cylindrical piston under tilted condition to reduce the possibility of hydraulic locking. Therefore, the results of present study can be used usefully in the design-and manufacturing of hydraulic piston pump and motor.

Theoretical Analysis of Sealless Piston for Hydraulic Cylinders (시일이 없는 유압 실린더용 피스톤의 이론해석)

  • Park, T.J.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.3 no.3
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    • pp.1-7
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    • 2006
  • In this paper, a theoretical analysis is carried out to study the lubrication characteristics of sealless piston for hydraulic cylinders. The analytical pressure distributions are obtained solving one-dimensional Reynolds equation with partially tapered moving piston. Nearly analytical expressions for lateral forces acting on the piston and leakage flow rate through the clearance are also presented. Using the analytical expressions, the influence of design parameters on lubrication characteristics can be easily evaluated without numerical analysis. Composite-shaped piston which minimizes the leakage flow rate is the optimum in sealless piston for hydraulic cylinder.

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Thermo mechanical analysis of a ceramic coated piston used in a diesel engine

  • Buyukkaya, Ekrem;Cerit, Muhammet;Coban, Mehmet
    • Steel and Composite Structures
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    • v.21 no.2
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    • pp.429-442
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    • 2016
  • The aim of this paper is to determine temperature and stress distributions in a ceramic based on Partially Stabilized Zirconia coated steel piston crown by using plasma spraying for improving performance of a marine diesel engine. Effects of coating constituent and thickness on temperature and stress distributions were investigated including comparisons with results from an uncoated piston by means of finite element method namely ANSYS. Temperature developed at the coated surface is significantly higher than that of the uncoated piston. The maximum stress components occur between bond coat and adjacent ceramic layer. Provided that coating thickness is constant as 0.5 mm, when numbers of layers increase, magnitude of the normal stress decrease about 34.1% on the base metal surface according to uncoated piston, but the base metal surface temperature of the steel piston increase about 13.1%.

Wear Resistance Characteristics of Thermal Sprayed AlSiMg/SiC Composite Coatings on Aluminum Engine Cylinder Bores (Aluminum Engine Cylinder Bore 적용 AlSiMg/SiC 복합 용사피막의 내마모 특성)

  • 양병모;변응선;박경채
    • Journal of Welding and Joining
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    • v.17 no.6
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    • pp.62-69
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    • 1999
  • The advantages of Thermal sprayed coatings as a replacement for cast iron liners are reduced weight, better heat transfer and reduced cost. One of the most important performance attributes of a cylinder bore coating is its wear resistance, since it must survive the abrasive sliding of both the piston rings and the piston skirt. In this study, composite powders were prepared by ball milling of Al-13Si-3Mg(wt%) alloy with SiC particles. The concentrations of SiC were 40 and 60wt%. The composite powders were sprayed using Metco-9MB plasma torch. Plasma sprayed coatings were heat-treated at 500℃ for 3 hours. The wear resistances of the plasma sprayed coatings were found to improve with heat treatment and superior to the commercially available G.C.I.(gray cast iron). AlSiMg-40SiC heat-treated coatings showed the best wear resistance in this study.

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A Study on the Friction and Wear Property of Composite Piston Ring for Oil Free Air Compressor (무급유 공기압축기용 복합재료 피스턴링의 마찰마모 특성에 관한 연구)

  • Kim, Y.Z.;Jung, H.D.;Kim, Y.H.
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.766-771
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    • 2000
  • This study is mainly concerned with friction and wear properties for the piston ring of non-lubricating air compressor which made of PTFE-polyimide composites. At the PTFE and polyimide alone mixture specimens, PTFE80%-polyimide20%, which shows the lowest men friction coefficient and specific wear rate at 0.94m/s sliding speed. At each of carbon, copper and oxide lopper mixed with PTFE80%-polyimide20%. In case of copper10%, at 0.94m/s sliding speed, the mean friction coefficient shows 0.087, which is the lowest value in all specimens. In case of the specific wear rate, copper30% specimen shows the lowest value of $2.537E-5(mm^3/Nm)$ in all specimens.

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Practical Calculation of Iron Loss for Cylindrical Linear Machine

  • Jeong, Sung-In
    • Journal of Electrical Engineering and Technology
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    • v.13 no.5
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    • pp.1901-1907
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    • 2018
  • This paper is a study for accurate iron loss calculation of a cylindrical linear machine for free piston engine. This study presents that it is possible to accurately predict power loss in ferromagnetic laminations under magnetic flux by specially considering the dependence of hysteresis, classical, and excess loss components on the magnetic induction derivative. Significant iron loss in the armature core will not only compromise the machine efficiency, but may also result in excessive heating, which could lead to irreversible deterioration in the machine performance. Thus, correct prediction of power losses under a distorted flux waveform is therefore an important prerequisite to machine design, particularly when dealing with large apparatus where stringent efficiency standards are required. Finally, it will be discussed about the iron loss in various materials of cylindrical linear electric machine by geometric and electrical parameters. It will give elaborate information about the perfect design and design rules of cylindrical linear machine and in parallel tools for the calculation, simulation and design will be available.

Manufacture and Mechanical Properties of $ABO_w/AC4CH$ Composite Material ($ABO_w/AC4CH$복합재료의 제조 및 기계적 특성)

  • 허선철;박원조;허정원
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.5
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    • pp.188-194
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    • 2001
  • Metal matrix composites with whisker reinforcements have significant potential for demanding mechanical applications including defense, aerospace, and automotive industries. Especially, metal matrix composites, which are reinforced with aluminum borate whisker, have been used for the part of piston head in automobile because of good specific strength and wear resistance. Aluminum alloy-based metal matrix composites with whisker reinforcements have been produced using squeeze casting method, which is kind of an infiltration method. In this study, AC4CH-based metal matrix composites with $Al_{18}B$_4$O_{33}$ reinforcement have been produced using squeeze casting method, after T6 heat treatment, we evaluated mechanical properties of matrix and MMC composite were evaluated.

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