• Title, Summary, Keyword: 금속벨트 CVT

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An Experimental Study on the Shift Characteristics of a Metal Belt Type Continuously Variable Transmission (CVT) (금속벨트식 무단변속기(CVT)의 변속특성에 관한 실험적 연구)

  • 이충섭
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.6
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    • pp.36-43
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    • 1997
  • To cope with quest to improve the fuel economy and vehicle performance, Continuously Variable Transmission with Changing the speed ratio between minimum and maximum ratio by infinite step, is more efficient than conventional multi-ratio transmission. In this paper, to investigate a specific CVT shift ratio diagram and CVT shift characteristics, CVT vehicle was tested on the proving ground and chassis dynamometer. The test results are as follows; CVT can obtain the excellent vehicle performance and fuel economy changing the shift ratio by infinite step, without rapid change of engine revolution and driving force. And CVT can set up a special shift range that obtains not only the engine brake effect but also the maximum speed driving.

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Shifting Ratio Control of CVT (CVT의 변속제어)

  • Kim, Hyun-Soo;Kim, Kwang-Won;Kim, Sung-Ho;Sung, Duk-Hwan;Eun, Tak;Park, Seong-Hyon;Yang, Jin-Seung;Kwon, Hyuk-Bin
    • Journal of the KSME
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    • v.33 no.10
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    • pp.892-901
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    • 1993
  • 환경오염과 차량 성능향상에 따라서 날로 강화되는 연비규제는 차량용 변속기로서 CVT 양상 보급에 대한 필요를 앞당기고 있다. CVT는 소형차를 중심으로 일부 자동차 에이커에 의해 이미 실용화되어 있으며 일본 및 구미 자동차 각 사는 CVT에 대한 자체기술을 보유하고 경쟁성 있 는 완성품 개발을 위하여 총력을 기울이고 있는 실정이다. CVT에 대한 연구개발의 추세는 동 력전달 구동요소의 특성에 따라 벨트식과 토로이달 (Torodial)식으로 구분할 수 있으며 대부분의 경우 현재 일부 실용화 개발된 벨트식 CVT가 기술완성도가 높은 반면 토로이달롤러의 각도를 연속적으로 변환시킴으로써 무단변속을 이루는 토로이달 방식은 2000년대 이후에 양산을 목표로 일본 및 영국 등에서 개발 진행주이나 새로운 재질과 제어기술개발 등의 숙제를 안고 있다. 벨 트식의 경우 금속벨트는 지난 십 수년이상 시행착오를 겪으며 CVT용으로 개발된 전문업체의 제품이 이미 특허화되어 있기 때문에 자동차 각사는 벨트와 같은 구동요소보다는 CVT 메카니즘 설계 및 제어시스템 개발에 기술력을 투입하고 있다. 따라서 국내 CVT 개발도 이와 같은 추세를 따를 것으로 기대되고 있으나 AT와 같은 완성품으로서의 상품가치를 갖기 위하여는 CVT에 대한 보다 많은 연구개발이 필요하다고 생각된다.

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Transfer Function Derivation and LQG/LTR Speed Ratio Control for a Metal Belt CVT (금속벨트 CVT의 전달함수 도출과 변속비 LQG/LTR 제어)

  • 김종준;송한림;김현수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.1
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    • pp.49-58
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    • 1997
  • In this paper, a transfer function was obtained for a PWM high speed solenoid valve controlled metal belt CVT system. The transfer function was defined as the ratio of speed ratio to PWM duty ratio and derived in time domain by linear regression analysis from the experimental results. The transfer function obtained showed different dynamic characteristics for the up and down shift. Also, LQG/LTR controller was designed for the CVT system using the transfer function. It is seen from the experimental results that LQG/LTR control showed good performance for the speed ratio tracking and disturbance rejection. The phase difference and relatively slow response are considered due to the inaccuracy os the transfer functions, which resulted from the inherent nonlinearities of the transmission characteristics of the metal belt CVT.

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Analysis of belt behavior for a metal V-belt CVT (금속 V-벨트 CVT의 벨트거동 해석)

  • 김현수;이재신
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.557-566
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    • 1991
  • The metal V-belt behavior of a continuously variable transmission was investigated analytically and experimentally. Numerical results showed that nondimensional belt radial displacement increased in the radial inward direction for the driven pulley, while that of the driver pulley increased for the first 90 degrees of the active are and decreased with the increasing torque load. Experimental results for the belt radial displacement were in good agreement with the theoretical results. However, the absolute magnitude of the belt radial displacement was so small that the change in the belt displacement could not be measured in the experimental range except for the inlet region of the driven pulley, where the radial inward displacement was observed due to the effect of bending moment. The speed ratio-axial force relationship derived from the belt behavior analysis also showed god agreement with the experiment.

Power Transmission Characteristics and Speed Ratio-Torque Load-Axial Force Relationship for a Metal V-Belt CVT (금속 V-벨트 CVT의 동력전달 특성과 변속비-부하토크-축력 관계)

  • 김광원;김현수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.2
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    • pp.349-357
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    • 1990
  • Power transmission characteristics and speed ratio-torque load-axial force relationship for a metal V-belt CVT were investigated theoretically and experimentally. In the metal V-belt CVT drive, it was found that the power was transmitted by thrust force and that band tension should be greater than compression force between the metal blocks. The experimental results for the speed ratio-torque load-axial force relationship showed good agreement with those predicted using equations developed from theoretical considerations.

Study on Engine-CVT Consolidated Control(II)-Experimental Study (엔진-CVT 통합제어에 관한 연구(II)-실험적 연구)

  • 김달철;김현수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.6
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    • pp.111-119
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    • 1997
  • In this paper, engine-CVT consolidated control performance were investigated experimentally. Engine-CVT consolidated control was composed of engine throttle control based on power difference and CVT ratio control based on CVT ratio map. Experimental results showed that engine optimal operation was obtained while satisfying the driver's desire, i. e., following the given drive mode by engine-CVT consolidated control. Also, it was found that engine performance is subjected to inertia of the powertrain where the magnitude of acceleration changes abruptyly. Comparing with the results of CVT only control, the results of engine-CVT consolidated control showed better performance. Therefore, in order to meet the driver's desire as well as keeping the engine optimal operation, the engine-CVT consolidated control could be suggested as an integral solution.

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Electronic Ratio Control of Metal Belt CVT (금속벨트 CVT 변속비 전자제어화)

  • 김달철;김현수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.4
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    • pp.100-109
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    • 2000
  • In this paper a stepping motor drive electronic ratio control system for a metal belt CVT is suggested. The electronic ratio control system developed in this study is designed to control flow rate which is required to obtain the shift speed and to control the primary actuator pressure to maintain the desired ratio. Considering these control characterstics a fuzzy logic is used for the CVT ratio control. Using the fuzzy logic dynamic models of the ratio control system is investigated and compared with the experimental results. The experimental and simulation results show that the electronic ratio control system developed in this study can be used in CVT system for the active control of the speed ratio.

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Analysis of Primary and Secondary Thrust of a Metal Belt CVT Part I : New Formula for Speed Rtio-Torque-Thrust Relationship Considering Band Tension and Block Compression (금속벨트 CVT 의 구동 및 종동 드러스트 해석 Part I : 밴드 장력과 블록 압축력을 고려한 새로운 변속비-토크-트러스트 관계식)

  • 이희라;김현수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.8
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    • pp.132-142
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    • 1999
  • In this paper, a new formula for primary and secondary thrust of metal belt CVT is proposed considering variation of band tension, block compression and active arc for each of the primary and secondary pulleys. For the secondary thrust, effective friction coefficient is introduced considering the effect of flange deflection. Nondimensional primary and secondary thrust of the metal belt CVT by the new formula agree well with the experimental results except for low torque range, $0\;<\;{\lambda}\;<\;0.2$ at speed ration i = 1.0. The new formula can be used in design of the primary and secondary thrusts control system for the metal belt CVT.

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A study on the belt-pulley system of continuously variable transmission (무단변속기(CVT) 벨트-풀리 시스템에 관한 고찰)

  • 이충섭;조희복
    • Journal of the korean Society of Automotive Engineers
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    • v.18 no.3
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    • pp.8-16
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    • 1996
  • 차량의 주행저항에 대응하여 최소-최대변속비 사이를 연속적으로 무한대의 단계로 변속시킴으로써 우수한 동력성능과 연비를 얻을 수 있다는 장점을 지닌 무단변속기의 벨트-풀리 시스템에 대하여, 현재 개발에 성공한 벨트-풀리 시스템의 특징을 분석하고, 벨트 효율 및 적용한계를 조사분석한 결과, 내구성 및 소음측면에서 볼 때 금속푸시벨트가 가장 유리하며, 벨트의 동력손실을 최소화하기 위하여 금속푸시벨트의 구성부품인 블록과 링을 최적화하고, 풀리에 작용하는 축력을 최적으로 제어함으로서 전달효율이 향상된 벨트-풀리 시스템을 제공할 수 있다. 날로 엄격해지는 배기가스 규제와 전자 및 제어분야의 발달로 성능이 더욱 향상된 무단변속기의 개발 및 장착이 환산될 것으로 예상되며, 또한 효율, 소음측면 뿐만 아니라, 제작단가가 저렴한 CVT용 벨트의 개발이 잇따를 것으로 전망된다.

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Analysis of Ratio Changing Characteristics of a Metal V-Belt CVT Adopting Primary Pressure Regulation (압력제어 방식 금속 벨트 CVT 변속특성 해석)

  • 최득환;김현수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.5
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    • pp.179-187
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    • 2001
  • In this paper, a primary pressure regulating type ratio control system is developed for a metal belt CVT, and the CVT ratio changing characteristics are investigated by simulation and experiment. The hydraulic part of the ratio control system has a simple structure with one 3-way spool valve as a main ratio control valve and one bleed type variable force solenoid as a pilot valve. The mathematical modelling of the CVT hydraulic system is derived by considering the CVT shift dynamics. Simulation results of CVT speed ratio and the primary pressure agree with the experimental results demonstrating the validity of the dynamic models. It is found from the simulation and experimental results that the response time of speed ratio and primary pressure can be shortened by increasing the ratio control valve port area, and the size of feedback orifice of ratio control valve gives a damping effect on the primary pressure oscillation.

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