• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1999.06a
• /
• pp.232-239
• /
• 1999

Generally quantity of supply oil for piston ring lubrication in an internal combustion engine may be insufficient to fill the entire volume formed in the clearance between piston ring and cylinder liner. Thus oil starvation condition should be considered for the analysis of piston ring lubrication. In order to reasonably estimate amount of oil left on the cylinder liner, adequate boundary condition should be adapted for the analysis of ring pack lubrication. In this analysis of ring pack lubrication of an internal combustion engine, oil starvation and open-end boundary conditions are considered at inlet and outlet of piston rings. It is revealed that piston rings are operated under oil starvation in most operating cycle and the result with these conditions are quite different from that with fully-flooded assumption.

• Journal of KSNVE
• /
• v.10 no.3
• /
• pp.474-479
• /
• 2000

Piston slap is not only one of the major sources of noise and vibration in internal combustion engines but also a cause of the deterioration of engine performance. The basic mechanism associated with the piston slap seems to be quite simple but the phenomenon is in fact complicated with regard to many mechanical elements associated, First of all the impact force of piston slap must be identified to estimate engine block surface vibration, In this paper model of collision point is proposed to calculate the impact force when slap surface vibration. In this paper model of collision point is proposed to calculate the impact force when slap occurs. The parameters of the model are estimated by employing the concept of point mobility, . The predicted and experimentally observed vibration results confirm that the proposed method is practically useful.

• Tribology and Lubricants
• /
• v.15 no.3
• /
• pp.233-239
• /
• 1999

Generally quantity of supply oil for piston ring lubrication in an internal combustion engine may be insufficient to fill the entire volume formed in the clearance between piston ring and cylinder liner. Thus oil starvation condition should be considered for the analysis of piston ring lubrication. In order to reasonably estimate amount of oil left on the cylinder liner, adequate boundary condition should be adapted for the analysis of ring pack lubrication. In this analysis of ring pack lubrication of an internal combustion engine, oil starvation and open-end boundary conditions are considered at inlet and outlet of piston rings. It is revealed that piston rings are operated under oil starvation in most operating cycle and the result with these conditions are quite different from that with fully-flooded assumption.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1988.06a
• /
• pp.28-30
• /
• 1988

윤활시스템에서 마모는 상대적인 운동을 하는 두 물체사이에서 표면상태, 접촉조건 및 분위기등의 제요소들에 의해 발생되며, 형태학적으로 scuffing, scoring, pitting 및 fretting 등으로 분류된다. 윤활조건의 특성에 따라 미끄럼 접촉에서는 mild wear, severe wear로 구분되며, 이들의 마모 생성기구의 차이는 접촉상대속도, 하중 및 표면조도등의 정도에 기인된다. mild wear에서 severe wear 영역으로 전이될 때의 가혹한 조건에서 생성되는 마모현상을 scuffing wear라 하며, 이는 접촉면에서의 표면돌기의 직접접촉에 의한 cold welding 현상, 즉 local welds의 특성을 지닌 마멸형태로 정의한다. 이의 생성은 접점간의 하중 및 미끄럼 속도가 증가됨에 따라 온도상승에 기인되어 순간적으로 발생된 마찰열이 그 원인이 있으며, 기어, cam 및 tappet, 피스톤링 및 실린더 라이너 등의 마멸현상이 대표적인 예이다.

• Tribology and Lubricants
• /
• v.9 no.1
• /
• pp.9-15
• /
• 1993

Tribology는 미끄럼 혹은 구름베어링, 피스톤링, 기어, 공구, 그밖의 상대적 움직임하에 있는 부품의 설계 및 제조와 관련된 학문이다. 또한 tribology는 서로 접촉하는 재료의 적절한 사용, 윤활유와의 상호작용 이해 및 적절한 선택을 통해 마모와 마찰의 감소 혹은 최적의 마찰(브레이크, 벨트 등의 경우)을 위해 연구되는 분야이다. 부품의 내마모성을 향상시키고 적절한 마찰계수를 얻기 위해서는 기계 설계, 윤활유 선택 및 개발, 재료의 선택 및 개발 등 여러 분야의 기여가 모두 필요하다. 지금까지는 전통적으로 사용되어 오던 재료, 특히 금속재료를 중심으로 하여 기계 및 윤활제 개발 등에 치중하여 왔다. 그러나 산업이 발전되고 복잡화됨에 따라 극한 분위기 즉 고온, 고진공하에서의 장시간 사용과 고효율 등을 요구하여 최근의 tribology 분야에 사용되는 부품들의 신소재로의 대체를 요구하고 있다. 한 예로 지금의 엔진보다 더 고온에서 작동되는 고효율의 경량의 첨단 열엔진의 개발을 들 수 있다. 이러한 열 엔진의 사용목적을 달성하기 위해서는 기존의 금속재료로는 고온에서 작동괴기에는 너무 약하고 무겁기 때문에 구조용 세라믹스가 고려되고 있는 것이다. 신소재 분야중 세라믹스는 고기능성 부품과 이미 산업화된 분야의 부품의 대체 재료로 주목을 받고 있다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.3
• /
• pp.349-356
• /
• 2003

The aim of this paper is to investigate the friction characteristics of piston assembly. The friction of piston assembly is composed of ring pack and skirt friction. In this paper, the theoretical models of piston ring pack and piston skirt were presented. The mixed lubrication theory was considered to calculate friction force of piston ring and skirt. from the results, most of friction in piston assembly occurred at the piston ring park. The piston assembly usually showed hydrodynamic lubrication characteristics. but the top and bottom dead centers showed mixed lubrication characteristics. The piston skirt was much affected by radial clearance and load, but ring was significantly influenced by ring tension.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.9 no.3
• /
• pp.123-129
• /
• 2000

To make high accuracy cutting of long materials and a piston for the engines it must be necessary to keep the thermal stability of spindle and tail stock in CNC lathe. If a object is clamped at the ends the thermal expansion and cutting process generate the deflection of cutting objects. Especially in the case of a piston ring piston ovality and piston profile the influences of deflection are very serious. In order to solve the problems most of piston cutting are worked under simply support. However the prob-lems exist yet. Therefore this paper proposes the new structure of tail stock which can compensates the deflection.

• Journal of KSNVE
• /
• v.9 no.3
• /
• pp.587-592
• /
• 1999

Piston slap is one of the sources producing engine block surface vibration and mechanical noise. To analyze piston slap-induced vibration, a realistic but simple model is proposed and verified experimentally. A piston is modeled by 3 degree of freedom system and an impact point between piston skirt and cylinder wall by 2 degree of freedom system. Numerical simulation estimates impact forces of piston in cylinder, and the engine block surface vibration response is predicted by the convoluton of the impact forces with measured impulse responses. Experimental verification on the predicted response has been also performed by using a commercial 4-cylinder diesel engine. the predicted and experimental vibration responses confirm that the suggested model is practically useful.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.04a
• /
• pp.361-366
• /
• 2000

To make high precision cutting of long materials or a piston for the engines, it must be necessary to keep the stability of spindle and tail stock in CNC lathe. If a object is clamped at the ends, the thermal expansion and cutting generated in cutting process appear as the deflection of in cuttings objects. Especially, of a piston ring, piston ovality and piston profile, the influences are very serious. In order to solve the problems most of piston cutting are worked in simply support. However, the problems exist, yet.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.5
• /
• pp.81-88
• /
• 1999

In order to understand the relationship between the phase angle of piston ring and oil consumption was measured by analyzing $CO_2$concentration in exhaust gas. The use of hydrogen fuel not gasoline makes this possible because all of the carbon component in exhaust gas can be assumed to be produced from oil. As a result of experiment, it is known that the oil consumption varies periodically and a specific location of ring end gap was found at each peak of oil consumption. Therefore, it was found that the oil consumption was not constant even at the same operating conditions and this is because the relative locations of top and 2'nd ring end gap change arbitrarily.