• 제목/요약/키워드: Air Journal Bearing

검색결과 375건 처리시간 0.032초

공 회전시 자동변속기 차량의 실내소음 음질 개선에 관한 연구 (A Study on the Improvement of the Sound Quality of the Interior Noise of A/T Vehicle in Idle State)

  • 이상권;최병욱;여승동
    • 한국자동차공학회논문집
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    • 제1권1호
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    • pp.110-119
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    • 1993
  • 본 논문은 자동변속기를 탑재한 차량에서 에어콘(air condition)을 작동시키고, 공 회전시 기어의 변속을 "D"단에 두었을 때 실내에서 발생하는 이상음의 원인규명 및 해결 방 법에 관한 연구 결과를 논하고자 한다. 이 이상한 소음의 원인을 규명하기 위하여 실린더 내부의 연소압력, 메인 베어링캡(main bearing cap)의 진동, 엔진 마운팅 보스의 진동 및 차 량의 실내소음을 동시에 측정하여 분석하였으며 이 결과에 의하면 이상음의 원인은 크랭크 샤프트(crank shaft)의 굽힘진동이 파워플랜트(power plant)를 가진하여 진동을 증가시키고, 이 진동이 마운팅 보스를 통하여 차량의 차체에 전달되며, 차체의 진동에 의해서 발생하는 고체 전달음(structure-borne noise)이었다. 또한 이상음의 주기는 주파수 성분은 200-400Hz 이었다. 이 이상음은 크랭크 샤프트의 댐퍼 풀리의 질량을 저감하여 크랭크 샤프트의 동특 성을 개선함으로서 해결가능하고, 혹은 점화시기를 지연하여 연소 압력을 낮춤으로서 해결 가능하다.

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4자유도 비접촉 자기 서스펜션 기구의 설계 및 제어 (The Design and Control of Contact-free Magnetic Suspension System with Four Degrees of Freedom)

  • 이상헌;백윤수
    • 대한기계학회논문집A
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    • 제27권6호
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    • pp.871-878
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    • 2003
  • With the development of micro -technology, the demand for micro actual ing device is increasing. But, it is difficult to achieve high resolution and wide bandwidth with the conventional contact systems. So, the contact-free systems which are suspended or levitated by magnetic force or air bearing were proposed. These systems can be applied to high precision stages and alignment apparatuses. This paper describes a magnetically suspended system with four degrees of freedom which are composed of three rotations (roll, pitch, yaw), and one translation ( z). The operating principle and the structure of the system are similar to variable reluctance type electric machines. In this study, the force analysis is executed using magnetic circuit and virtual work principle, and the equations that describe the dynamics of the system are presented. The multivariable PID controller is adapted to the system and the experiment is executed.

회전자 편심을 고려한 농형 유도전동기의 특성해석 (Characteristics Analysis on the Effects of Rotor Eccentricity in Squirrel-cage Induction Motor)

  • 김미정;김병국;황돈하;강동식;조윤현
    • 전기학회논문지
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    • 제56권2호
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    • pp.289-294
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    • 2007
  • This paper describes the effects of rotor eccentricity in squirrel cage induction machines. Asymmetric electro-magnetic force caused by the frictional worn bearing, rotor misalignment and unbalanced rotor etc. generates an asymmetrical operation, vibration and electro-magnetic noise. The need for detection of these rotor eccentricities has pushed the development of monitoring methods with increasing sensitivity and noise immunity. In this paper, we focus on investigating the asymmetrical operation considering of unbalanced magnetic pull in squirrel-cage induction motor with 380 [V], 7.5 [kW], 4P, 1,768 [rpm]. The effects of the non-symmetric rotor and magnetic force are simulated by finite element method (FEM) and tested using search coils for measuring the actual air-gap flux.

최적화 기법을 이용한 HDD용 헤드 슬라이더의 부상상태 해석 (A Flying State Analysis of HDD Head Slider by Using An Optimization Technique)

  • 윤상준;김존관;최동훈;이재헌;김광식
    • Tribology and Lubricants
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    • 제8권2호
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    • pp.26-34
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    • 1992
  • This paper suggests a method to predict the flying state of the head slider in a hard disk drive (HDD) by using an optimization technique. The modified Reynolds equation for the hydrodynamic lubrication theory under the slip flow condition is used to describe the air-bearing system and a Finite Volume Method (FVM) is applied to solve the equation. Especially, Augmented Lagrange Multiplier (ALM) method is employed to find the minimum flying height, the pitch angle and the roll angle of the slider, which is shown to be faster and more general than the conventional update schemes. By using the proposed method, the variations of the flying state are analyzed as a function of the slider position in the direction of the disk radius for various disk velocities and skew angles.

초소형 스프링 정밀 측정을 위한 디지털 영상 처리 시스템 개발 (Development of System based on Digital Image Processing for Precision Measurement of Micro Spring)

  • 표창률;강성훈;전병희
    • 소성∙가공
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    • 제11권7호
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    • pp.620-627
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    • 2002
  • The purpose of this paper is the development of an automated measurement system for micro spring based on the digital image processing technique. This micro spring can be used in various engineering applications such as filament, load bearing springs, hard disk suspension and many others. Main functionality of the micro spring inspection system is to measure the representative pitch of the micro spring. The derivative operators are used for edge detection in gray level image. Measurement system developed in this paper consisted of new auto feeding mechanism to take advantage of air pressure. In the process of development of the micro spring inspection system based on the image processing and analysis, strong background technology and know-how have been accumulated to measure micro mechanical parts.

BLDC 전동기의 전자기적 불평형력을 고려한 편심 회전자의 동적 거동 해석 (Dynamic Behavior Analysis of an Eccentric Rotor with Unbalanced Magnetic Forces in BLDC Motors)

  • 김태종;황상문;박노길
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제48권11호
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    • pp.604-610
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    • 1999
  • Vibration of a rotor-bearing system driven by an electric motor is a coupled phenomenon between mechanical characteristics and magnetic origins through the air-gap. With the advent of new high-energy magnets together with high precision motor applications, magnetic sources of vibration are becoming more serious. This paper investigates the transient whirl responses of a rotor system with purely mechanical origins and compares it with that of magnetically coupled origins. A perturbation method is applied to model the magnetic field associated with rotor eccentricity. Electromagnetic forces are obtained by the Maxwell stress method, which utilizes the analytical expression of radial flux density distribution. The FEM was applied to a rotor-motor system to illustrate magnetically coupled effects in rotor dynamics. Results show that magnetically coupled sources significantly affect the vibration of the rotor-motor system.

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고속.고정밀 금형가공센터 개발 III (Development of High Speed & Precision Mould/Die Machining Center III)

  • 최원선;이창호;박보선;김태형
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2002년도 추계학술대회 논문집
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    • pp.429-435
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    • 2002
  • In order to manufacture a precision mold/die by machining, users need high speed & precision mold/die machining center. So, for development of this machine, we intend to use linear motor that is instead of ball-screw, servo-motor and coupling, high-speed spindle of pressurized air journal bearing and composite materials. In this paper we research column moving type and table moving type. The former is mainly piling 3 axes on one moving body, the latter is consist of two independent carriages. Both types are available to high speed & precision machine, but we finally draw a conclusion column moving type due to an advantage of high-speed control of linear motor.

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마그네틱 헤드 슬라이더의 極小 空氣膜에 대한 定常狀態 解析 (Steady State Analysis of Magnetic Head Slider at Ultra Low Clearance)

  • 장인배;한동철
    • 대한기계학회논문집
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    • 제13권4호
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    • pp.764-770
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    • 1989
  • This paper analyze the steady state performance of a self-acting air lubricated slider bearing in hard disk/head system. Modified Reynolds' equation is derived from the steady state compressible Navier-Stokes equation, under slip-flow conditions. Finite difference technique and numerical procedure are described by using Newton-Raphson iteration method to slove the non-linear equations. These techniques are applied to conventional slider bearings and the effects of molecular mean free path(MMFP) for a recording surface of hard disk are shown. The calculation procedure developed here, wide applicabilities in practical head design procedures, and converges rapidly.

하드 디스크 드라이브용 패드 슬라이더의 트라이볼로지 특성에 관한 실험적 연구 (Experimental Analysis of Tribological Performances of Padder Slider in HDD)

  • 홍수열;좌성훈;고정석;이형재
    • Tribology and Lubricants
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    • 제17권4호
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    • pp.312-320
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    • 2001
  • In magnetic hard disk drives, higher areal recording density requires reduction of head-disk spacing. To overcome the increase of stiction associated with reduction of head-disk spacing, a padder slider, which adds pads to slider's air bearing surface, can be one of the practical solution for sub 20 nm flying height, and even for near contact recording. This study investigated the tribological characteristics of a padder slider. A padder slider took off slowly but showed less friction force than a normal slider. The hot/dry CSS test and drag test indicated that pad wear of a padder slider was negligible. The tribological performance of disk is an important factor to be considered. In particular, less carbon overcoat layer of the disk will result in higher stiction and wear in slider/disk interface. In conclusion, a padder slider shows encouraging tribological performances for practical use in HDD.

선박용 복합재 에어 스포일러의 체결부 설계 및 강도 평가 (Joint Design and Strength Evaluation of Composite Air Spoiler for Ship)

  • 피준우;전상배;이근호;조영대;최진호;권진회
    • Composites Research
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    • 제28권4호
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    • pp.219-225
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    • 2015
  • 선박 분야에서 이산화탄소($CO_2$) 배출을 줄이고 연료 효율을 높이기 위한 방법의 하나로 항해하는 선박의 공기 저항을 줄이기 위한 에어 스포일러를 장착하는 방안이 검토될 수 있다. 본 연구에서는 대형 선박에 적용될 수 있는 복합재 에어 스포일러의 체결부를 설계하고, 이에 대한 정적, 피로강도를 평가하였다. 하중은 선박의 운항 중 발생하는 청파(Green Water Pressure) 0.1 MPa이 에어 스포일러에 수직하게 가해지는 것으로 가정하였다. 에어 스포일러는 유리섬유 면재에 발사 코어를 갖는 샌드위치 형태로 제작하였고, 여러 개의 샌드위치 패널이 셀(Cell) 형태로 강(Steel) 프레임에 볼트로 체결되는 것으로 가정하였다. 에어 스포일러와 프레임의 체결부는 베어링 파손을 가지도록 설계하고, 정적(베어링) 시험과 피로(4점 굽힘) 시험을 수행하였다. 시험 결과 개발된 에어 스포일러는 정해진 외부하중을 견딜 수 있는 충분한 안전여유를 갖는 것을 확인하였다. 개발된 에어 스포일러는 조만간 대형 상업용 선박에 적용될 예정이다.