• Title/Summary/Keyword: 시동 모터

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A Study on the Start-up Control for HDD Spindle Motors (HDD 스핀들 모터의 초기 구동 제어에 관한 연구)

  • Jeong, Jun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.10
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    • pp.1065-1072
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    • 2008
  • A HDD adopts a sensorless brushless DC (BLDC) motor as a spindle motor. Because there is no direct sensor measuring rotor position. open loop commutations with inductive sensing are used to increase the rotor speed up to a certain speed where the zero crossings of the back electromotive force (EMF) voltage are measurable. Therefore, successful open loop commutations are necessary for the stable start-up control of the spindle motors. In this paper, the time scale and the number of the open loop commutations are employed for design parameters to guarantee robustness to torque constant variation and initial rotor position. The design results are verified by experiments on a very low current start-up of the spindle motor with various environment. The experimental results show that the design results can decrease the start-up failure rate considerably.

A Study on the Forging Process Development of the Commutator of an Automotive Starting Motor (자동차용 시동 모터 정류자의 단조공정 개발에 관한 연구)

  • 서명규;배원병;정호승;조종래
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.905-909
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    • 2002
  • Commutators of a starting motor for automobiles has been produced through various processes such as forging, segmenting, and assembling. And the conventional method producing an automotive motor commutator is not appropriate for saving material and cost, because it makes each segment separated one by one. Therefore a new process design is required in oder to avoid the assembling process. In this study, a new process design of the commutator of an automotive starting motor has been carried out to save material and manufacturing time by FE analysis. In the FE analysis, three forging processes are proposed for producing the copper(ASTM Cl1000) commutators of a starting motor. And forging experiments are performed to make an unsegmented commutator in order to verify the theoretically proposed process. And then, in order to get the final product, the forged commutator is passed through various postprocessing such as resin terming, and machining. From the experimental result, the forging process proposed from the FE analysis is verified to be an economical method for producing the commutator of an automotive starting motor.

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Numerical Analysis on Flow Characteristics of Air Starting Motor for Marine Medium-Speed Diesel Engine (선박용 중형디젤엔진 공기시동모터의 유동특성에 관한 수치해석)

  • Yang, Su-Young;Kim, Tae-Hun;Lee, Yeon-Won;Doh, Deog-Hee
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.4
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    • pp.545-552
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    • 2009
  • The marine medium-speed diesel engines are operated by two methods; one is the electric motors, and the other air starting motors. Even though air starting motor is dependent of the engine types and sizes, it has been widely used in this area due to its simplicity, convenience and reliability. However most of them are currently imported from overseas due to the lack of the cutting-edge technology in terms of design and manufacturing. Therefore, from the point of this view, the air starting motor needs to be produced by our own techniques. The purpose of this paper is to give the designing parameters in order to make a proper "Air Starting Motor" using CFD. The aerodynamic approaches were given to understand the internal flow characteristics of the air starting motor. In addition, we have carried out the effects of tip clearance. In the calculations the tip clearance of air starting motor has been varied between 0% and 5.7% of blade span.

Review of the Solid Propulsion Trend in the Launch Vehicle(1) (발사체 고체 추진기관 동향 리뷰(1))

  • Lee, Tae-Ho
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2012.05a
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    • pp.201-212
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    • 2012
  • In general solid propulsion offers cost effective, large thrust capabilities comparing to the liquid propulsion which offers high specific impulse and restart capabilities. Therefore solid propulsion is well fitted for the first stage and boosters. BBL approach has been studied for the launch vehicle because of cost effectiveness, limited development time and low risk. Using of the carbon fiber epoxy resin in the solid rocket motor case is expanded, and specially high strength fibers are more attracted since its inert mass reduction.

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The study on the characteristics of transient recovery voltage of electromagnetic contactor (전자기 접촉기의 과도회복전압 특성에 대한 연구)

  • Kim, Geun-Yong;Ryu, Jae-Nam
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.834-835
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    • 2008
  • 전자기 접촉기(electromagnetic contactor)는 교류 또는 직류 저압의 전로(電路)에 사용되는 부하개폐기의 한 종류로 전자석 코일(electromagnet coil)의 여자(勵磁)에 의하여 주 접촉자를 개폐시키는 기기이다. 일반적으로 전자기 접촉기는 단락전류를 차단하도록 설계되어 있지는 않다. 그러므로 설치 시 적절한 단락 보호가 이루어져야 하며, 반드시 접촉기의 일부분일 필요는 없다. 차단기와 퓨즈 등을 단락보호장치(SCPD, Short-Circuit Protective Device)로 많이 사용한다. 전자기 접촉기는 특히 고빈도 개폐를 목적으로 사용되는 개폐기로, 농형모터(squirrel-cage motors)의 시동, 운전 중의 정지, 플러깅(plugging, 모터가 운전하고 있는 중에 모터의 1차측 접속을 역으로 바꿔서 모터를 급격히 정지시키거나 역 회전시키는 것) 및 인칭(inching, 모터를 짧은 기간 동안 1회 또는 반복 여자해서 피동기구를 조금 이동시키는 것)에 많이 쓰인다. 이러한 기기의 개폐특성을 평가하기 위한 부하는 과도회복 전압의 진동 주파수(oscillatory frequency)와 진폭율 ${\gamma}$를 얻을 수 있도록 조정되어야 한다. 본 논문에서는 고빈도 개폐능력을 갖고 있는 전자기 접촉기의 과도회복 전압 특성과 그 특성을 얻기 위한 부하 회로의 조정방법에 대해 고찰하였다.

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Starting Characteristics of Supersonic Exhaust Diffuser for Altitude Simulation Testing (고공환경 모사를 위한 초음속 디퓨저의 시동 특성 분석)

  • Kim, Yong-Wook;Lee, Jung-Ho;Kim, Sang-Heon;Oh, Seung-Hyub
    • Aerospace Engineering and Technology
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    • v.11 no.2
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    • pp.117-121
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    • 2012
  • Upper stage propulsion system designed for operation in the upper atmosphere should be tested under nozzle full flow conditions to verify its performance on the ground. KARI has carried out high altitude simulation test of KSLV-I kick motor using cylindrical supersonic exhaust diffuser. Also cold and hot flow test for the sub-scaled diffuser have been conducted to verify the design of real scale diffuser and to study its operating characteristics. This paper deals with the results obtained from these high altitude simulation tests.

Research on fault analysis and reliability improvement of APU start motor for Korea Utility Helicopter (한국형 기동헬기 APU 시동모터 결함원인 분석 및 신뢰성 개선)

  • Kang, Tae-Woo;Yeom, Hyo-Won;Lee, Hee-Rang;Ahn, Jong-Moo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.6
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    • pp.703-709
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    • 2017
  • Korea Utility Helicopter(KUH) is a project to replace the aging helicopter presently being operated by the military with a domestic helicopter. The auxiliary power unit is a device that supplies emergency power to the system by an alternator installed when the main generator fails and the start motor converts the electrical energy of the battery into mechanical rotational energy to rotate the auxiliary power unit engine. With continuing power and operation, defects of the starting motor were found and improvements were carried out to solve it. In the failure mode analysis, the causes of possible defects were classified into 5 categories. Analysis of the 5 factors revealed that the main cause of defects is mechanical wear, which was found to be related to spring pressure. 250 tests were conducted through the theoretically determined pressure and regression analysis was performed with 4 sampling.The results showed that pressure was related to wear rate. In conclusion, early wear and breakage due to wear can be controlled through spring force and test showed the prediction of wear and the validity of the result were confirmed.

Study on Wear of Journal Bearings during Start-up and Coast-down Cycles of a Motoring Engine - II. Analysis Results (모터링 엔진의 시동 사이클 및 시동 정지 사이클에서 저어널베어링의 마모 연구 - II. 해석 결과)

  • Chun, Sang Myung
    • Tribology and Lubricants
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    • v.31 no.3
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    • pp.125-140
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    • 2015
  • In this paper, we present the results of the wear analysis of journal bearings on a stripped-down single-cylinder engine during start-up and coast-down by motoring. We calculate journal bearing wear by using a modified specific wear rate considering the fractional film defect coefficient and load-sharing ratio for the asperity portion of a mixed elastohydrodynamic lubrication (EHL) regime coupled with previously presented graphical data of experimental lifetime linear wear in radial journal bearings. Based on the calculated wear depth, we obtain a new oil film thickness for every crank angle. By examination of the oil film thickness, we determine whether the oil film thickness at the wear scar region is in a mixed lubrication regime by comparing dimensionless oil film thickness, h/σ, to 3.0 at every crank angle. We present the lift-off speed and the crank angles involved with the wear calculation for bearings #1 and #2. The dimensionless oil film thickness, h/σ, illustrates whether the lubrication region between the two surfaces is still within the bounds of the mixed lubrication regime after scarring of the surface by wear. In addition, we present in tables the asperity contact pressure, the real minimum film thickness at the wear scar region, the modified specific wear rate, and the wear angle, α, for bearings #1 & #2. To show the real shape of the oil film at wear scar region, we depict the actual oil film thickness in graphs. We also tabulated the ranges of bearing angles related with wear scar. We present the wear volume for bearings #1 and #2 after one turn-on and turn-off of the engine ignition switch for five kinds of equivalent surface roughness. We show that the accumulated wear volume after a single turn-on and turn-off of an ignition switch normally increases with increasing surface roughness, with a few exceptions.

Study on Wear of Journal Bearings during Start-up and Coast-down Cycles of a Motoring Engine - I. Theory and Analysis Procedure (모터링 엔진의 시동 사이클 및 시동 정지 사이클에서 저어널베어링의 마모 연구 − I. 이론 및 해석 절차)

  • Chun, Sang Myung
    • Tribology and Lubricants
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    • v.31 no.3
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    • pp.109-124
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    • 2015
  • This paper presents a wear analysis procedure for the journal bearings on a stripped-down single-cylinder engine during start-up and coast-down by motoring. A journal bearing is in the mixed elastohydrodynamic (EHL) lubrication region when the shaft speed is less than the corresponding lift-off speed. Below the lift-off speed, a wear scar can form on bearing surfaces. In part 1 of this paper, we develop the appropriate formulations and the calculation procedure for the analysis. Specifically, we formulate an equation for modified film thickness in a journal bearing considering the additional wear volume. In order to obtain the modified specific wear rate induced by the modified Archard’s wear coefficient, we utilized the extended non-dimensional diagram for the specific wear rate, k, the fractional film defect coefficient, Ψ and the asperity load sharing factor, γ2. This asperity load sharing factor is newly calculated by setting the Zhao-Maietta-Chang (ZMC) asperity contact pressure equation coupled with the central film thickness equation derived by using the ZMC asperity contact model equal to the modified central contact pressure derived by using the central (or maximum) contact pressure at the dry rough line-contact configuration. We can use the procedure introduced in this paper to determine the lifetime (or longterm) linear wear in radial journal bearings that is a result of repeated stop-start cycles.