• Title, Summary, Keyword: Hydrodynamic Bearing(동압유체베어링)

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Analysis of a Hydrodynamic Bearing of a HDD Spindle Motor Due to Elevated Temperature (온도변화에 의한 HDD 유체 동압 베어링의 특성 해석)

  • 김학운;김관수;장건희;이행수;김철순
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.556-563
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    • 2003
  • This paper presents a method to investigate the characteristics of a hydrodynamic bearing of a HDD spindle motor due to elevated temperature considering the variation of the clearance as well as the lubricant viscosity. Iterative finite element analysis of the heat conduction and the thermal deformation is performed to determine the viscosity and clearance of a hydrodynamic bearing due to elevated temperature until the temperature of the bearing area converges. Proposed method is verified by comparing the calculated temperature with the measured one in elevated surrounding temperature as well as in room temperature. This research shows that elevated temperature changes the clearance as well as the lubricant viscosity of the hydrodynamic bearing of a HDD spindle motor. Once the viscosity and clearance of a hydrodynamic bearing of a HDD spindle motor are determined, finite element analysis of the Reynolds equation is performed to investigate the static and dynamic characteristics of a hydrodynamic bearing of a HDD spindle motor due to elevated temperature. It also shows that the variation of clearance due to elevated temperature is another important design consideration to affect the static and dynamic characteristics of a hydrodynamic bearing of a HDD spindle motor.

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Analysis of a Bydrodynamic Bearing of a BDD Spindle Motor Due to Elevated Temperature (온도변화에 의한 HDD 유체 동압 베어링의 특성 해석)

  • Kim Kwan Soo;Kim Hak Woon;Lee Haeng Soo;Kim Chul Soon;Jang Gun Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.5
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    • pp.762-769
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    • 2005
  • This paper presents a method to investigate the characteristics of a hydrodynamic bearing of a HDD spindle motor due to elevated temperature considering the variation of the clearance as well as the lubricant viscosity. Iterative finite element analysis of the heat conduction and the thermal deformation is performed to determine the viscosity and clearance of a hydrodynamic bearing due to elevated temperature until the temperature of the bearing area converges. Proposed method is verified by comparing the calculated temperature with the measured one in elevated surrounding temperature as well as in room temperature. This research shows that elevated temperature changes the clearance as well as the lubricant viscosity of the hydrodynamic bearing of a HDD spindle motor. Once the viscosity and the clearance of a hydrodynamic bearing of a HDD spindle motor are determined, finite element analysis of the Reynolds equation is performed to investigate the static and dynamic characteristics of a hydrodynamic bearing of a HDB spindle motor due to elevated temperature. It also shows that the variation of clearance due to elevated temperature is another important design consideration to affect the static and dynamic characteristics of a hydrodynamic bearing of a HDD spindle motor

A Study for the Improvement of Performance of the Water-meter applying the Hydrodynamic Journal Bearing Theory (동압 유체 베어링 이론을 적용한 수도미터의 성능향상에 관한 연구)

  • Yoon, Joon-Yong;Sung, Nak-Won;Kim, Byung-Ho
    • The KSFM Journal of Fluid Machinery
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    • v.3 no.1
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    • pp.5-9
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    • 2000
  • A study to minimize the error in water-meter is considered in this work. It is presumed that the large amount of error at large flowrate is occurred due to the vibration of the impeller shalt. After a newly designed bushing applying hydrodynamic journal bearing theory is adopted, the error at large flow rate is decreased remarkably comparing with the classical water-meter. It is concluded that the effect of a bushing in water-meter stabilizes the rotator of the impeller shaft.

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Characteristics of Herringbone-Grooved Hydrodynamic Bearing and Scanner Motor for Laser Beam Printer (레이저 프린터에 사용되는 빗살무늬 유체동압 베어링과 스캐너 모터의 특성)

  • Jeong, Seong-Hun;Lee, Yeong-Je;Jeong, Dae-Hyeon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.1
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    • pp.269-274
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    • 2000
  • Frictions and electrical contact voltages of the herringbone-grooved hydrodynamic bearing(HHB) were 9, measured to use in a laser scanner motor. This bearing with varying loads, speeds, oil viscosity, and radial clearances successfully operated up to 28,000rpm and 0.5N. Experimental results under various environments confirmed that this bearing had excellent performance with low friction force, and operated without contact between shaft and sleeve.

Analysis of a Journal and Thrust FDB and a Conical FDB in the Spindle Motor of a Computer Hard Disk Drive (HDD 스핀들 모터용 저널-스러스트 유체동압 베어링과 코니컬 유체동압 베어링의 특성해석비교)

  • Kim, Bum-Cho;Jang, Gun-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.478-483
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    • 2005
  • This paper presents the comparison analysis of a Journal and thrust FDB (fluid dynamic bearing) and a conical FDB in a HDD spindle motor. The Reynolds equation is appropriately transformed to describe journal, thrust and conical bearing. Finite element method is applied to analyze the FDB by satisfying the continuity of mass and pressure at the interface between the hearings. The pressure field of the bearings is numerically approximated by applying the Reynolds boundary condition. The load and friction torque are obtained by integrating the pressure and the velocity gradient along the fluid film. The flying height of the spindle motor is measured to verify the proposed analytical result. This research shows that the conical bearing generates bigger load capacity and less friction torque than the journal and thrust bearing in a HDD spindle motor.

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Dynamic Characteristics of a Coupled Journal and Thrust Hydrodynamic Bearing in a HDD Spindle System Due to Groove Location (HDD 스핀들 시스템에 사용되는 저널과 트러스트가 결합된 유체 동압 베어링의 홈 위치에 따른 동특성 해석)

  • 윤진욱;장건희
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.304-311
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    • 2001
  • This research numerically analyzes the dynamic characteristics of a coupled journal and thrust hydrodynamic bearing due to its groove location which has the static load due to the weight of a rotor in the axial direction and the dynamic load due to its mass unbalance in the radial direction. The Reynolds equation is transformed to solve a plain member rotating type of journal bearing(PMRJ), a grooved member rotating type of journal bearing (GMRJ), a plain member rotating type of thrust bearing (PMRT) and a grooved member rotating type of thrust bearing (GMRT). FEM is used to solve the Reynolds equations in order to calculate the pressure distribution in a fluid film. Reaction forces and friction torque are obtained by integrating the pressure and shear stress along the fluid film, respectively. Dynamic behaviors, such as whirl radius or floating height of a rotor, are determined by solving its nonlinear equations of motion with the Runge-Kutta method. This research shows that the groove location affects the pressure distribution in the fluid film and consequently the dynamic performance of a HDD spindle system.

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Finite Element Analysis of a Coupled Hydrodynamic Journal and Thrust Bearing in a Computer Hard Disk Drive (컴퓨터 하드디스크 드라이브에 사용되는 저널과 스러스트가 연성된 유체 동압 베어링의 유한 요소 해석)

  • Kim, Hak-Woon;Lee, Sang-Hoon;Jang, Gun-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.846-852
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    • 2004
  • This paper proposes a method to calculate the characteristics of a coupled hydrodynamic journal and thrust bearing of a HDD spindle motor. The governing equations for the journal and thrust bearings are the two dimensional Reynolds equations in ${\theta}z$ and $r\theta$ planes, respectively. Finite element method is appropriately applied to analyze the coupled journal and thrust bearing by satisfying the continuity of mass and pressure at the interface between the journal and thrust bearings. The pressure in a coupled bearing is calculated by applying the Reynolds boundary condition and compared with that by using the Half-Sommerfeld boundary condition. The static characteristics are obtained by integrating the pressure along the fluid film. The flying height of spindle motor is measured to verify the proposed analytical result. This research shows that the proposed method can describe HDB in a HDD system more accurately and realistically than the separate analysis of a journal or thrust bearing.

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Finite Element Analysis of a Coupled Hydrodynamic Journal and Thrust Bearing in a Computer Hard Disk Drive (컴퓨터 하드디스크 드라이브에 사용되는 저널과 스러스트가 연성된 유체 동압 베어링의 유한 요소 해석)

  • Kim, Hakwoon;Lee, Sanghoon;Jang, Gunhee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.1
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    • pp.87-95
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    • 2005
  • This paper proposes a method to calculate the characteristics of a coupled hydrodynamic journal and thrust bearing of a HDD spindle motor. The governing equations for the journal and thrust bearings are the two dimensional Reynolds equations in $\theta z$ and $ r\theta$ planes, respectively. Finite element method is appropriately applied to analyze the coupled journal and thrust bearing by satisfying the continuity of mass and pressure at the interface between the journal and thrust bearings. The pressure in a coupled bearing is calculated by applying the Reynolds boundary condition and compared with that by using the Half-Sommerfeld boundary condition. The static characteristics are obtained by integrating the pressure along the fluid film. The flying height of spindle motor is measured to verify the proposed analytical result. This research shows that the proposed method can describe HDB in a HDD system more accurately and realistically than the separate analysis of a journal or thrust bearing.

Analysis of a Hydrodynamic Herringbone-Grooved Journal Bearing in a Small Precision Motor Considering Cavitation (공동현상을 고려한 소형 정밀 모터용 빗살무늬 저널베어링의 해석)

  • 창동일;장건희
    • 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.

A Study on Dynamic Characteristics of a Rotor-Bearing System Supported by Actively Controlled Fluid Film Journal Bearing (능동 제어 유체 윤활 베어링으로 지지된 축-베어링 시스템의 동특성에 관한 연구)

  • No, Byeong-Hu;Kim, Gyeong-Ung
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.8
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    • pp.116-121
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    • 2001
  • The paper presents the dynamic characteristics of a rotor-bearing system supported by an actively controlled hydrodynamic journal bearing. The proportional. derivative and integral controls are adopted for the control algorithm to control the hydrodynamic journal bearing with an axial groove. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than conventional analysis, which uses the Reynolds condition. The speed at onset of instability of a rotor-bearing system is increased by both proportional and derivative control of the bearing. The proportional control increases the stability threshold without affecting the whirl ratio. However, for the derivative control of the bearing, increase of stability threshold speed is accompanied by a parallel reduction of the whirl ratio. The integral control has no effect on stability characteristics of hydrodynamic journal bearing. The PD-control is more effective than proportional or derivative control. Results 7how the active control of bearing can be adopted for the stability improvement of a rotor-bearing system.

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