• Title/Summary/Keyword: Rotor Unbalance

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Rotordynamic Analysis of a Turbo-Chiller with Varying Gear Loadings Part I ; A Driving Motor-Bull Gear Rotor-Bearing System (터보 냉동기의 변동 기어하중을 고려한 로터다이나믹 해석 Part I : 구동 모터-불기어 로터-베어링 시스템)

  • 이안성;정진희
    • Journal of KSNVE
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    • v.9 no.3
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    • pp.593-599
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    • 1999
  • A rotordynamic analysis is performed with a motor-bull gear rotor system supported on two partial bearings, which is intended to drive a high-speed turbo-chiller compressor impeller shaft through its built-in pinion gear. The motor-bull gear rotor system has a rated speed of 3,600 rpm, and is modeled utilizing the finite element method for analysis. As loadings on the bearings due to the gear action are significant in the system considered, each resultant bearing load is calculated statically by considering the generalized forces of the gear action as well as the rotor itself. The two support partial bearings are designed to take their varying loads along with their varying load angles, and they are also analyzed to give their rotordynamic coefficients. Then, a complex rotordynamic analysis of the motor-bull gear rotor-bearing system is carried out to evaluate its whirl natural frequencies and mode shapes and unbalance responses under various loading conditions. Results show that the bearings and entire rotor system are well designed regradless of operating conditions, i.e., loads and operating speeds.

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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.

Development of a hard bearing type balancing machine (강성 베어링형 밸런실 장치의 개발)

  • 권이석;이동환;박중윤;홍성욱
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.773-777
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    • 1994
  • This paper is devoted to the development and performance evaluation of a hard bearing type balancing machine for rigid rotors. The pedestals of the balancing machine are designed to be rigid to be rigid enough to enable the balancing to operate far below the fundamental critical speed. The force measuring method is implemented to the balancing machine. The forces due to unbalance are measured through load cell that are attached to the pedestals. A helical coupling is used for transmitting the driving force from an AC servo motor to the rotor to be balanced. The experimental results show that the current hard bearing type balancing machine can indicate the presence of unbalance beyond 1 .mu. m in specific unbalance unit. The limitation of the current balancing machine is due to the coupling that is likely to make inconsistent offset errors everytime the rotor is connected to the machine.

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Analysis on the characteristics the induction motor under mechanical unbalance of a rotor (유도형 모터 회전자의 기계적 불형형 특성해석)

  • Jang, S.M.;Lee, S.L.;Seo, J.H.;Jeong, S.S.;Kim, K.J.;Park, Y.S.
    • Proceedings of the KIEE Conference
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    • 1998.07a
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    • pp.296-298
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    • 1998
  • The mechanical unbalance of the rotor in motors generate vibrations and make its shortened their life, therefore, it is important that search for a cause of the vibration in the point of economics. In this paper, to reduce the vibration we will analyse the unbalance magnetic pull in induction motor. Namely, the electromagnetically generated forces, the airgap flux density distribution in a single phase induction motor is calculated by analytical and numerical method.

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Element Design of Balancing Shaft for Reducing the Vibration in Engine Module (엔진진동 저감을 위한 밸런싱샤프트의 요소설계 기법 연구)

  • Lee, Bong-Hyun;Kim, Dong-Chul;Jung, In-Oh;Kim, Chan-Jung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.11 s.104
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    • pp.1268-1275
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    • 2005
  • Vibration in Engine module could be reduced by introducing a balance shaft module which has one or more unbalanced rotors. Since the unbalanced rotor is installed in an opposite direction of the free force or unbalance moment by engine component, the unexpected vibration could be decreased kinematically. The essential equation of the unbalanced rotor was Presented for two cases, 3 in-line and 4 in-line cylinder engine type, And the efficiency of the balance shaft is investigated by the vehicle testing that is focused on measuring the reduced vibration level when adapting a balancing module. With the signal processing of measured signals, some important issues on design the balancing shaft could be derived and the overall design process is explained in the final part including the peripheral component, i.e. housing and bush.

ISO/TC/108/SCl 1940-1(Mechanical vibration - Balance quality requirements of rigid rotors- Determination of permissible residual unbalance) (강성회전체의 평형특성 요구조건 - 허용 잔류불평형량의 결정 (ISO 1940-1))

  • 최상규;전오성
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.889-898
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    • 2002
  • This part of ISO 1940 gives recommendations for determining unbalance and for specifying related quality requirements of rigid rotors; it specifies a) a representation of unbalance in one or two planes; b) methods for determining permissible residual unbalance; c) methods for allocating it to the correction planes; d) methods for identifying he residual unbalance state of a rotor by measurement; e) a summary of errors associated with the residual unbalance identification. This part of ISO 1940 is also intended to facilitate the relations between manufacturer and user of machines. Detailed consideration of errors associated with the determination of residual unbalance is covered in the 2nd part of ISO 1940 (ISO 1940-2 will deal with these errors).

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Dynamic analysis of spin speed dependent parameter rotor-bearing systems (회전속도 의존 매개변수를 가진 회전체-베어링계의 동적 해석)

  • 홍성욱;이종원
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.5
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    • pp.976-983
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    • 1988
  • An efficient unbalance response analysis method for rotor-bearing systems with spin speed dependent parameters is developed by utilizing a generalized modal analysis scheme. The spin speed dependent eigenvalue problem of the original system is transformed into the spin speed independent eigenvalue problem by introducing a lambda matrix, assuming the bearing dynamic coefficients are well approximated by polynomial functions of spin speed. This method features that it requires far less computational effort in unbalance response calculations and that the influence coefficients are readily available. In addition, the critical speeds and the corresponding logarithmic decrements can be readily identified from the resulting eigenvalues.

Dynamic Behavior Analysis of Rotor-Bearing System for Rotary Compressor (로터리 압축기 회전체-베어링계의 동적 거동해석)

  • 김태학
    • 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.

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