• Title/Summary/Keyword: crankshaft-journal bearing system

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Load Characteristics of Engine Main Bearing : Comparison Between Theory and Experiment

  • Cho, Myung-Rae;Oh, Dae-Yoon;Ryu, Seung-Hyuk;Han, Dong-Chul
    • Journal of Mechanical Science and Technology
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    • v.16 no.8
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    • pp.1095-1101
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    • 2002
  • The load characteristics of engine main bearing are very important in the design of crankshaft and engine block. The stiffness of crankshaft and block, or the optimal dimension of the bearing can be determined according to the load level. This paper presents the load characteristics of engine main bearing. Two components of the main bearing load are measured during engine firing and motoring. The vertical and horizontal load components are measured by using the dynamic load cell mounted in each main bearing cap bolt. The measured main bearing loads are compared with calculated results by using the statically determinate method. The theoretical results, provided in this study, agreed well with the experimental results. The presented results are very useful for achieving optimal design of engine.

The Effect of Oil Pressure Fluctuation on the Engine Lubrication System (엔진 윤활 시스템에서 오일 압력 변동의 영향)

  • 윤정의;전문수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.3
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    • pp.44-50
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    • 2002
  • The connecting rod big-end bearing is one of the most heavily loaded components of the lubrication system of high-speed combustion engines. The supply oil flow has to pass to the main bearing and the rotating crankshaft before entering the connecting rod bearing. It is common knowledge that the centrifugal forces due to the crankshaft rotation influence the oil flow to connecting rod bearing through the oil supply bore, especially, when the oil supply system to the connecting rod bearing has a 180$^{\circ}$circumferential groove via a single drilling in the crankshaft. In this case, it should be confirmed that the groove oil pressure in the main bearing is sufficient to overcome these centrifugal forces. For the purpose, the dynamic oil pressure before entering oil supply bore to the connecting rod bearing was measured instead of averaged oil pressure in main gallery. Experimental test results show that the dynamic oil pressure in the oil groove was more useful than that of main gallery. And it was also found that the oil pressure fluctuation in the groove was sensitively affected by the reduction of the main bearing clearance.

Dynamic Behavior Analysis of a Crankshaft-Bearing System in Variable Speed Reciprocating Compressor (가변속 왕복동형 압축기 크랭크축-베어링계의 동적 거동 해석)

  • 김태종
    • Tribology and Lubricants
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    • v.17 no.6
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    • pp.426-434
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    • 2001
  • The hermetic reciprocating compressor driven by the BLDC motor rotating with variable speeds, is modelled and analyzed for dynamic characteristics. The governing equations of piston, connecting rod and crank-shaft of the reciprocating compression mechanism and characteristics of driving torque of the motor are obtained. Dynamic behavior of the crankshaft supported on 2 journal bearings is analyzed considering compression load and eccentric unbalance for the 4 rotating speeds of crankshaft. And. reaction forces generated from oil film in the journal bearings are analyzed under transient condition using Reynolds' equation. To take into account the dynamic characteristics depending on the variable rotating speeds, comparison on the dynamic behavior of crank-shaft is made for the 4 operating modes of the compressor. Results show that the magnitude of crankshaft locioperating on the lower rotating speeds is more larger than the higher ones due to reduction of inertia force of the reciprocating piston.

A Study on Oil Path Design in the Journal Bearing of a Reciprocating Compressor (왕복동식 압축기의 저널 베어링 오일 패스 설계를 위한 연구)

  • Cho, Ihn Sung;Jung, Jae Youn
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.8
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    • pp.839-846
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    • 2013
  • Because the performance of a reciprocating compressor in refrigeration and air-conditioning systems is influenced by the lubrication characteristics of sliding components, the lubrication characteristics between the crankshaft and journal bearing have to be researched for the design and the performance improvement of reciprocating compressors. Thus, the proper supply of lubricant for a lubrication between the crankshaft and journal bearing is essential, and an oil path for lubricant supply is installed in the shaft or bearing. However, in order to guarantee the lubrication performance of the journal bearing, it is necessary to design the position of the oil path. Therefore, it is studied to find the optimum position of the oil path by the analysis of the pressure distribution in the journal bearing. The results show that the position of the oil path is significantly influenced by the pressure distribution of the oil film in the journal bearing.

Crankshaft Bearing Design Adapting Discontinuous Oil Supply System (불연속 오일공급 형태의 크랭크샤프트 베어링 설계)

  • Yun, Jeong-Eui
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.6
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    • pp.90-95
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    • 2004
  • In this study, for the crankshaft bearing design adapting discontinuous oil supply system, analyses were conducted to determine the lubrication characteristics such as oil flow rate and increase of oil temperature at main bearing and connecting rod bearing. Additionally, supplied oil pressure and temperature effects on the bearings were simulated to figure out lubrication characteristics on the bearings. Finally the effects of increasing the bearing width and clearance were introduced on the lubrication characteristics.

A Study on the Strength Analysis of Crankshaft for 4 Stroke Marine Diesel Engine (선박용 4행정 디젤엔진의 크랭크축 강도해석에 관한 연구)

  • Lee, D.C.;Kang, D.S.
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.3
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    • pp.359-368
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    • 2006
  • The trend on marine diesel engine productions and refinements has led to a higher mean effective pressure and thermal efficiency. These resulted in increased maximum combustion pressure within the cylinder and vibratory torque in crankshaft. In view of this. the crankshaft should be able to withstand the dynamic stresses caused by load variations. Different factors including size, material and stress concentration factors should also be considered to ensure the reliability of the shafting system. As such, crankshaft must be designed and compacted within its fatigue strength. In this paper, the strength analysis of crankshaft Is carried out by: simplified method recommended by IACS(International Association Classification Societies) M53 and a detailed method with the crankshaft assumed as a continuous beam and bearing supported in its flexibility. The results of these two methods are then compared.

Analysis of the Dynamic Behavior and Lubrication Characteristics of a Small Reciprocating Compressor (소형 왕복동 압축기의 동적 거동 및 윤활특성 해석)

  • Kim, Tae-Jong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.7
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    • pp.1138-1145
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    • 2003
  • In this paper, a study on the dynamic behavior and lubrication characteristics of a reciprocating compression mechanism used in small refrigeration compressor is performed. In the problem formulation of the compressor dynamics, the viscous frictional force between piston and cylinder wall is considered in order to determine the coupled dynamic behaviors of piston and crankshaft. The solutions of the equations of motion of the reciprocating mechanism along with the time dependent Reynolds equations for the lubricating film between piston and cylinder wall and oil films of the journal bearings are obtained simultaneously. The hydrodynamic forces of journal bearings are calculated using finite bearing model and Gumbel boundary condition. And, a Newton-Raphson procedure was employed in solving the nonlinear equations of piston and crankshaft. The results explored the effects of design parameters on the stability and lubrication characteristics of the compression mechanism.

Analysis of the Dynamic Behavior and Characteristics of the CNG Compressor Considering Bearing Characteristics (베어링 특성을 고려한 CNG 압축기의 동적 거동 및 동특성 해석)

  • Kim, Tae-Jong
    • Tribology and Lubricants
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    • v.22 no.6
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    • pp.342-349
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    • 2006
  • In this study, a dynamic behavior of rotor-bearing system used in CNG compressor has been investigated using the combined methodologies of finite elements and transfer matrices. The finite element is formulated including the field element for a shaft section and the point element for roller bearings. The Houbolt method is used to consider the time march for the integration of the system equations. The transient whirl response of rotating shaft supported on roller bearings is obtained, considering compression forces and unbalance forces at eccentric crank-pin part. And, the steady state displacements of the rotor are compared with a variation in stiffness coefficient of roller bearings. Results show that the loci of crankshaft considering unbalance forces and external compression forces are more severe in whirl motion than with only unbalance forces.

Dynamic Analysis of a Reciprocating Compression Mechanism Considering Hydrodynamic Forces

  • Kim, Tae-Jong
    • Journal of Mechanical Science and Technology
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    • v.17 no.6
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    • pp.844-853
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    • 2003
  • In this paper, a dynamic analysis of the reciprocating compression mechanism of a small refrigeration compressor is performed. In the problem formulation of the mechanism dynamics, the viscous frictional force between the piston and the cylinder wall is considered in order to determine the coupled dynamic behaviors of the piston and the crankshaft. Simultaneous solutions are obtained for the equations of motion of the reciprocating mechanism and the time-dependent Reynolds equations for the lubricating film between the piston and the cylinder wall and for the oil films on the journal bearings. The hydrodynamic forces of the journal bearings are calculated by using a finite bearing model along with the Gumbel boundary condition. A Newton-Raphson procedure is employed in solving the nonlinear equations for the piston and crankshaft. The developed computer program can be used to calculate the complete trajectories of the piston and the crankshaft as functions of the crank angle under compressor-running conditions. The results explored the effects of the radial clearance of the piston, oil viscosity, and mass and mass moment of inertia of the piston and connecting rod on the stability of the compression mechanism.

Dynamic Behaviour of a Radial Compliant Crank Mechanism Used in Scroll Compressor (스크롤 압축기에 적용된 가변반경 크랭크 기구의 동적 거동에 관한 연구)

  • 김태종;한동철
    • Tribology and Lubricants
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    • v.12 no.2
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    • pp.8-19
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    • 1996
  • Scroll compressor using a slide bushing type radial compliant crank mechanism is modelled, and it's dynamic behaviour characteristics are analyzed. Sealing forces generated in the flank surfaces of the orbiting scroll depending on the distance, e, from slide bushing center to crank pin center are calculated. From the stable condition of orbiting scroll for the moment equilibrium in tangential direction, the range of e is determined as 0$r_o$. Transient response of a crankshaft supported by two journal bearings is investigated, considering applied load, moment, and unbalance force by eccentric mass. As a result, conical whirl mode with circular orbits are obtained. The characteristics of journal orbits and frictional losses are calculated with a variation of viscosity and bearing clearance.