• Title/Summary/Keyword: Mechanical transmission

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Development of Self-compensated Technique for Evaluation of Surface-breaking Crack by Using Laser Based Ultrasound

  • Choi, Sang-Woo;Lee, Joon-Hyun;Cho, Youn-Ho
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.3
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    • pp.215-221
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    • 2005
  • It is required to evaluate nondestructively depth of surface-breaking cracks in structures. In this paper, the self-compensated technique by laser-based ultrasound is used to measure the depth of surface-breaking defect. Optical generation of ultrasound produces a well defined pulse with reliable frequency content. It is broad banded and suitable for measurement of attenuation and scattering over a wide frequency range. The self-calibrated signal transmission data of surface wave shows good sensitivity as a practical tool far assessment of surface-breaking defect depth. It is suggested that the relationship between the signal transmission and crack depth can be used to predict the surface-breaking crack depths in structures.

A study on the mechanical strength system and supporting method of insulator strings for KEPCO 765kV transmission lines (한전 765 kV 송전선로 애자장치 강도계열 및 지지방식에 관한 검토)

  • Han, Yup;Park, K.H.;Yoon, S.H.;Seo, C.S.
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1920-1922
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    • 1996
  • After determining the type and string condition of conductor of 765kV transmission lines, we studied the mechanical strength system of insulator strings to support conductors and insulate conductors from towers. In this paper, for the insulator strings which will be used in 765kV transmission lines, we're going to optimally determine the mechanical strength system and supporting method in the consideration of the reliability, economics and the survey data of T/L routes, and also suggest the calculation method to stipulate for the application limits of suspension and strain insulator strings according to the loadspan and height difference of tower.

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Study on the Elliptical Elastohydrodynamic Lubrication in the Toroidal Continuously Variable Transmission (가변 동력전달 장치에서의 타원 형상 점접촉 탄성유체윤활 연구)

  • 장시열
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2001.11a
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    • pp.310-315
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    • 2001
  • The most general feature of contact zone among the mechanical components is elliptical circle. In particular, continuously variable transmission (CVT) of toroidal type has elliptical shape of contact zone under the elastohydrodynamic lubrication condition, where the power is transmitted by the shearing the efluid. Due to the traction of the shear behaviors of lubricant over the small elliptical contact zone, high power of torque is transmitted. During the power transmission, many kinds of mechanical movements occur such as squeezing, sliding, rolling and spinning. The spinning effect that is not common contact behavior in tribological components frequently makes significant abnormal wear damage. In this work, the analysis of elliptical contact of elastohydrodynamic lubrication with spin effect is performed, which will give very useful information to understand the traction behaviors in toroidal type of CVT system.

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Development of a Simulator of Vehicle Equipped with Mechanical Transmission and Hydraulic Accumulator Type-Braking Energy Regeneration System (유압 축압기식 제동에너지 희생시스템을 장착한 기계식 변속기 차량의 모의시험기 개발)

  • 이성래
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.5
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    • pp.180-186
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    • 2004
  • The simulator of a vehicle equipped with mechanical transmission and hydraulic accumulator type-braking energy regeneration system is developed using a PC. The simulator receives the shift lever position, the accelerator pedal angle and the brake pedal angle generated by the operator using the keyboard, updates the state variables of the energy regeneration system responding to the input signals, and draws the moving pictures of the accumulator piston and pump/motor plate angle every drawing time on the PC monitor. Also, the operator can observe the shift lever position, the accel pedal angle, brake pedal angle, pressures of accumulators, vehicle speed, hydraulic torque, engine torque and air brake torque representing the operation of braking energy regeneration system through the PC monitor every drawing time. The simulator can be a very useful tool to design and improve the braking energy regeneration system.

Shock-Absorbing Safety Mechanism Based on Transmission Angle of a 4-Bar Linkage (4절링크의 전달각에 기초한 충격흡수식 안전기구)

  • Park, Jung-Jun;Kim, Byeong-Sang;Song, Jae-Bok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.11 s.242
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    • pp.1534-1541
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    • 2005
  • Unlike industrial manipulators, the manipulators mounted on service robots are interacting with humans in various aspects. Therefore, safety has been one of the most important design issues. Many compliant robot arms have been introduced for safety. It is known that passive compliance method has faster response and higher reliability than active ones. In this paper, a new safety mechanism based on passive compliance is proposed. Passive mechanical elements, specifically transmission angle of the 4-bar linkage, springs and shock absorbing modules are incorporated into this safety mechanism. This mechanism works only when the robot arm exerts contact force much more than the human pain tolerance. Validity of this mechanism is verified by simulations and experiments. It is shown that the manipulator using this mechanism provides higher performance and safety than those using other passive compliance mechanisms or active methods.

Helical gear multi-contact tooth mesh load analysis with flexible bearings and shafts

  • Li, Chengwu;He, Yulin;Ning, Xianxiong
    • Structural Engineering and Mechanics
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    • v.55 no.4
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    • pp.839-856
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    • 2015
  • A multi-contact tooth meshing model for helical gear pairs considering bearing and shaft deformations is proposed. First, to easily incorporate into the system model, the complicated Harris' bearing force-displacement relationship is simplified applying a linear least square curve fit. Then, effects of shaft and bearing flexibilities on the helical gear meshing behavior are implemented through transformation matrices which contain the helical gear orientation and spatial displacement under loads. Finally, true contact lines between conjugated teeth are approximated applying a modified meshing equation that includes the influence of tooth flank displacement on the tooth contact induced by shaft and bearing displacements. Based on the model, the bearing's force-displacement relation is examined, and the effects of shaft deformation and external load on the multi-contact tooth mesh load distribution are also analyzed. The advantage of this work is, unlike previous works to search true contact lines through time-consuming iterative strategy, to determine true contact lines between conjugated teeth directly with presentation of deformations of bearings and shafts.

A Study of Effects of the Helical Angle Directions of Planetary Gear Sets on the Axial Forces on Thrust Bearings in an Automatic Transmission (자동변속기 적용 유성기어의 헬릭스 각 방향에 의한 쓰러스트 베어링 작용 축 하중 연구)

  • Kwon, Hyun Sik
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.3
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    • pp.92-99
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    • 2021
  • An automatic transmission, which consists of several decks of planetary gear sets, provides multiple speed and torque ratios by actuating brakes and clutches (mechanical friction components) for connecting central members of the planetary gear sets. The gear set consists of the sun gear, the ring gear, and the carrier supporting multiple planet gears with pin shafts. In designing a new automatic transmission, there are many steps to design and analyze: gears, brakes and clutches, shafts, and other mechanical components. Among them, selecting thrust bearings that not only allow the relative rotation of the central members and other mechanical components but also support axial forces coming from them is important; doing so yields superior driving performance and better fuel efficiency. In selecting thrust bearings, the magnitude of axial forces on them is a critical factor that affects their bearing size and performance; its results are systematically related to the direction of the helical angle of each planetary gear set (a geometric design profile). This research presents the effects of the helical angle direction on the axial forces acting on thrust bearings in an automatic transmission consisting of planetary gear sets. A model transmission was built by analyzing kinematics and power flows and by designing planetary gear sets. The results of the axial forces on thrust bearings were analyzed for all combinations of helix angle directions of the planetary gear sets.

Mechanical Strength Calculation of HVDC Valve Hall (HVDC시스템 밸브홀의 기계적 강도 계산)

  • Kim, Chan-Ki;Lee, Seong-Do;Kang, Ji-Won;Yoon, Yong-Beum
    • The Transactions of the Korean Institute of Power Electronics
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    • v.21 no.5
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    • pp.442-448
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    • 2016
  • This paper presents electromagnetic force effect of the conductor and insulator in the HVDC valve hall. This paper is based on IEC 60865, which is applicable to the mechanical and thermal effects of short-circuit currents. The paper contains procedures for the calculation of the electromagnetic effect on HVDC conductors and flexible conductors, as well as the thermal effect on HVDC conductors. The results are applied to the Godeok -Dangjin HVDC system.

The Propagation Characteristics of the Pressure in the Volume Loaded Fluid Transmission Line (체적부하를 갖는 유체 전달관로의 압력전파 특성)

  • 윤선주;손병진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.11
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    • pp.3075-3083
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    • 1994
  • The applications of the electrical transmission line theory to the pressure propagation characteristics in the volume loaded fluid transmission line with step and impulse input wave is demonstrated in this paper. The method is based on the premise that the time response is the inverse Fourier transform of frequency spectrum of the wave which spectrum is a product of frequency spectrum of input pressure wave and system transfer function. The frequency response and transient response of step and impulse input wave in the volume loaded fluid transmission line is analysed by the Laplace transform and inverse Laplace transform with FFT numerical algorithm. The numerical solution of the distributed friction model is compared with the average friction model and the infinite product model. And the result is showed that FFT method may have major advantages for the simulation of fluid circuitary.

Transmission Error Analysis of the Helical Gears for the Elevator (엘리베이터용 헬리컬기어의 전달오차 해석)

  • Park, Chan-Il;Kim, Dae-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.12
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    • pp.2695-2702
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    • 2002
  • The elevator gear box with the helical gears needs to be developed instead of the one with the worm gears to improve the efficiency. In order to develop the gear box, the analytical tool to predict the helical gear noise is necessary to meet customer's noise requirement. Gear noise is related to the loaded transmission error. Therefore, the simulation program fer the loaded transmission error analysis of the helical gears is developed in this study. Using the developed program, the effects of tooth modification such as tip relief and the extent of tip relief are investigated. Finally, the procedures to determine the tip relief and the extent of tip relief are proposed.