• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.2
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• pp.241-248
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• 2013

In this study, bearings were developed for a high-power propulsion motor operating in inclined operation conditions through a simulation and similitude-experimental methods using commercial rotating machinery dynamics analysis software. The developed journal bearing is electrically insulated and has low thermal conductivity because each part is connected with 2-4 -mm-thick epoxy plates. To realize an appropriate oil thickness, an oil lift system is adopted, and a half separated structure is applied to ensure the feasibility of maintaining very heavy components. This study discusses some of the key design aspects of sleeve bearing design for high-torque and low-speed propulsion motor applications. Furthermore, the conditions of variable slope tests are examined to prevent oil leakage from the bearing lip seal on the test rig.

• 열병합발전
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• s.51
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• pp.18-23
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• 2006

• Journal of the KSME
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• v.29 no.3
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• pp.261-269
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• 1989

볼 베어링의 성능에 중요한 영향을 미치는 볼 베어링 특유의 기하학적 형상, 탄성론에 근거한 볼과 궤도륜 사이의 접촉역학 및 구름접촉을 위한 탄성 유체윤활이론을 소개한 후, 축방향 하 중하에서 고속으로 회전하고 있는 볼 베어링의 해석방법을 기술하였다. 소개된 해석 방법이 완박한 것은 아니며, 보다 엄밀한 해석을 위하여 마찰열에 의한 온도상승의 영향을 고려하여야 할 것이다. 또한 해석 결과를 얻기 위하여 효율적인 수치 계산법을 적용한 볼 베어링 해석을 위한 결과를 얻기 위하여 효율적인 수치 계산법을 적용한 볼 베어링 해석을 위한 전용 소프트 웨어를 개발하여야 한다. 외국에서는 이와 같은 컴퓨터 프로그램이 사용되고 있으나, 우리도 독자적으로 전용 소프트웨어를 개발함으로써, 외국의 소프트웨어를 도입하였을 때의 한계를 피 하고, 다양한 응용예마다 가장 효율적인 해석을 할 수 있는 유연성을 가질 필요가 있다고 생각 한다. 구조물 최적설계를 위하여 유한요소 해석 프로그램을 이용하듯이, 이와 같은 전용 해석 소프트웨어를 사용하여 볼 베어링의 최적설계를 할 수 있을 것이다.

• Journal of the KSME
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• v.30 no.5
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• pp.454-459
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• 1990

마그네틱 베어링으로써 일반베어링의 사용할 때에 있었던 수많은 문제점들이 모두 해결되는 것 처럼 보인다. 여러 가지 특징 및 장점을 갖고 있으므로 가까운 장래에 회전기계 분야에 중요 하게 사용될 것으로 판단된다. 그러나 받아들여질 수 없는 몇 가지 요인들과 산업체에서 완전히 수용하기 이전에 좀 더 기술되어야 할 사항들은 다음과 같다. (가) 신뢰성 : 좀 더 연구할 필 요가 있다. (나) 안정성 : 동적 안정성의 측면에서 연구되어야 한다. (다) 축방향 베어링 : 앞 에서 설명한 바와 같이 원주속도의 한계치가 21,000m/min이고 따라서 그보다 직경이 작은 반경 방향 베어링의 한계 원주속도는 12,000m/min가 된다. (라) 전기적 장애 : 고정자와 절연된 회 전자 사이에는 방전이 일어나게 되고 이에 따라 포텐셜의 장애가 나타나게 된다. (마) 가격 : 크기가 작을 경우에는 일반 베어링에 비해 약 1.5배가량 비싸며 크기가 클 경우에는 약 80%가 된다. 그리고 운전비용은 일반 베어링에 비해 저렴하다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2680-2687
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• 2000

The Reynolds equation, incorporating Elrods cavitation algorithm, is discretized on a rectangular grid in computational space through coordinate mapping in order to accurately analyze a herringbone grooved journal bearing of a spindle motor in a computer hard disk drive. The pressure distribution and cavitation area are determined by using the finite volume method. Predicted results are compared to experimental data of previous researchers. It was found that positive pressure is developed within the converging section of the bearing and that a cavity occurs in the diverging section. Cavitation has been neglected in the previous analysis of the herringbone grooved bearing. Load capacity and bearing torque are increased due to the increased of eccentricity and L/D and the decrease of the grooved width ratio. The maximum load capacity was found to occur at a groove angle of 30 degrees while bearing torque remains constant due to the variation of the groove angle. The cavitation region is significantly decreased with the inclusion of herringbone grooves. However, the region increases with the increase of the eccentricity, L/D, groove angle and the rotational speed and the decrease of the grooved width ratio.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1058-1064
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• 2003

Noise estimating procedures of oil lubricated journal bearings are presented. Nonlinear analysis of rotor-bearing system including unbalance mass of the rotor is performed in order to obtain acoustical properties of the bearing. Acoustical properties of the bearing are investigated through frequency analysis of the pressure fluctuation of the fluid film calculated from the nonlinear analysis. Noise estimating procedures presented in this paper could aid in the evaluation and understanding of acoustical properties of oil lubricated journal bearings.

• Tribology and Lubricants
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• v.27 no.2
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• pp.71-76
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• 2011

In this study, the nondimensional load capacity of water hydrodynamic journal bearings is calculated. A generalized coordinate formulation is applied to handle the complexity of bearing geometry. A window-based analysis program is developed to analysis the cylindrical hydrostatic bearings. Load capacities are calculated according to some design parameters such as clearance, diameter of orifice, size of recesses and temperature. The results are presented and discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.2
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• pp.244-251
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• 1999

Large dynamic loads act on the rotor in rotary compressors. There are unbalance forces due to eccentric rotation parts and gas forces induced by the pressure difference between compression and suction gases. Rotor-journal bearing system is nonlinear since the stiffness and damping coef-ficients of the lubrication oil film are not constant in the bearings. in this paper the program for predicting the behaviors of rotor-journal bearing system of rotary compressor is developed. Finite element modeling is used to analyze the flexible rotor. The numerical results are compared with experimental results.

• JOURNAL OF ELECTRICAL WORLD
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• no.6 s.174
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• pp.1-4
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• 1991

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.7 s.112
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• pp.746-753
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• 2006

This paper proposes a method to calculate the stiffness and the damping coefficients of the coupled journal and thrust bearings. The Reynolds equations and their perturbation equations are transformed to the finite element equations by considering the continuity of pressure and flow at the interface between bearings. The Reynolds boundary condition is used in the numerical analysis to simulate the cavitation phenomena. The dynamic coefficients of the proposed method are compared with those of the numerical differentiation of the loads with respect to finite displacements and velocities of bearing center. It shows that the proposed method is more accurate and efficient than the differentiation method.