• Title/Summary/Keyword: CVT

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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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Study on Engine-CVT Consolidated Control(I) -Development of Consolidated Control Algorithm (엔진-CVT 통합제어에 관한 연구(I) -통합제어 알고리즘 개발)

  • 김달철;김현수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.5
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    • pp.86-96
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    • 1997
  • In this paper, engine-CVT consolidated control algorithm was developed. Engine -CVT control strategy suggested uses throttle control based on power difference and CVT ratio control based in CVT ratio map. Simulation results showed that the larger the rate of CVT ratio, the better the engine performance in the optimal operation line. Also, it was found that the engine performance where the magnitude of the acceleration changes abruptly depends on the magnitude of the rate of CVT ratio. Comparing the results of CVT control only without engine control, the engine-CVT control algorithm suggested in this work showed better performance demonstrating that the consolidated control algorithm should be required for the engine optimal operation.

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Engine-CVT Integrated Control Algorithm Considering Power train Loss and CVT Response Lag (동력전달계 동력손실계 CVT 응답지연을 고려한 엔진-CVT 통합제어 알고리즘)

  • 김달철;김현수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.1
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    • pp.112-121
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    • 2001
  • In this paper, an engine-CVT integrated control algorithm is suggested by considering the powertrain loss, inertia torque and the CVT ratio response lag. The integrated control algorithm consists of (1) the optimal engine power calculation and (2) determining of the optimal throttle valve opening and the optimal CVT ratio. The optimal engine power is obtained by compensating the inertia torque due to the CVT ratio change and the powertrain loss that is calculated iteration procedure. In addition, an algorithm to compensate the effect of the CVT ratio response lag on the drive torque is suggested by the engine speed compensation causing the increased optimal CVT ratio. Simulation results show that the engine-CVT integrated control algorithm developed in this study makes it possible to obtain better engine operation on the optimal operating line, which results in the improved fuel economy while satisfying the driver's demand.

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Development and Optimal Operation of an Electro-Hydraulic Controlled Rig Type CVT (전자유압제어식 리그형 CVT 개발과 최적운전)

  • Kim, K.W.;Kwon, H.B.;Kim, H.S.;Eun, T.;Park, C.I.
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.9
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    • pp.2181-2190
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    • 1993
  • An electro-hydraulic controlled rig type CVT(Continuously Variable Transmission) system was developed and its performance tests were carried out for the optimal operation. A CVT map was suggested based on the speed ration-axial force-torque relationship which was derived from the metal belt CVT mechanics. Also, a real time control and operation software was developed for the electro-hydraulic CVT system. By using the software and the CVT map, the control system was designed for the CVT speed ratio control with various drive modes. The electro-hydraulic CVT system developed in this study showed that the optimal operation algorithm could be obtained for the best fuel economy or the maximum power mode.

HARDWARE IN THE LOOP SIMULATION OF HYBRID VEHICLE FOR OPTIMAL ENGINE OPERATION BY CVT RATIO CONTROL

  • Yeo, H.;Song, C.H.;Kim, C.S.;Kim, H.S.
    • International Journal of Automotive Technology
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    • v.5 no.3
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    • pp.201-208
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    • 2004
  • Response characteristics of the CVT system for a parallel hybrid electric vehicle (HEV) are investigated. From the experiment, CVT ratio control algorithm for the optimal engine operation is obtained. To investigate the effect of the CVT system dynamic characteristics on the HEV performance, a hardware in the loop simulation (HILS) is performed. In the HILS, hardwares of the CVT belt-pulley and hydraulic control valves are used. It is found that the engine performance by the open loop CVT ratio control shows some deviation from the OOL in spite of the RCVs open loop control ability. To improve the engine performance, a closed loop control of the CVT ratio is proposed with variable control gains depending on the shift direction and the CVT speed ratio range by considering the nonlinear characteristics of the RCV and CVT belt-pulley dynamics. The HILS results show that the engine performance is improved by the closed loop control showing the operation trajectory close to the OOL.

Development of a Toroidal CVT Controller for Agricultural Tractor (II) - PID controller - (트랙터용 토로이달 무단변속기 제어시스템 개발(II) - PID 콘트롤러 개발 -)

  • Kim H. J.;Ryu K. H.
    • Journal of Biosystems Engineering
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    • v.29 no.5 s.106
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    • pp.407-418
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    • 2004
  • There are several different types of continuously variable transmission(CVT) such as toroidal drive, belt drive, hydrostatic drive, hydro-mechanical drive. The toroidal CVT is an alternative to the manual transmission, HST, power-shift gear trans-missions or other CVTs. The driver of the CVT tractor doesn't have to operate a shia lever since the CVT controller automatically controls the speed of tractor. Thus, it is much easier to operate the CVT tractor. The fuel efficiency of CVT tractor can be increased since the controller responds quickly to the change in external load on the wheel during field operation. This study was conducted to develop the hardwares and softwares for the toroidal CVT controller which control the variator and the range clutches. The hardware consisted of a measurement system, hydraulic system and computer. And the PID controller was developed using the simulation model of the CVT control system. Through the simulation, the control coefficients for the PID controller were selected. Finally, the performance of the CVT control system was evaluated by step response test and torque response test. The settling time of the CVT control system appeared to be fast enough for field operations.

Performance Analysis of the Rubber Belt type CVT System (고무 벨트식 무단변속기 시스템의 성능분석)

  • Kim, Sung-Mo;Zheng, Chun-Hua;Lim, Won-Sik;Cha, Suk-Won
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.4
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    • pp.376-381
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    • 2011
  • CVT(Continuously Variable Transmission) is one of the most promising candidates for the future automobile transmission because of its continuously variable gear ratio and reduced shift shock. It is also possible to operate the power source at its high efficiency region with CVT. The CVT system consists of thrust plate, driving pulley, belt, driven pulley, and preload spring of output shaft. In this paper, the dynamic modeling of a CVT system is completed to obtain the static performances of CVT system. A simulator is implemented on Matlab(Simulink), which can analyse the static performances of a CVT system. The methods for improving the total efficiency of a motorcycle system are also proposed based on the simulation results. In this study we increase the capacity factor of CVT up to the three times of default specification.

ADAPTIVE CVT-BASED REDUCED-ORDER MODELING OF BURGERS EQUATION

  • Piao, Guang-Ri;Du, Qiang;Lee, Hyung-Chun
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.13 no.2
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    • pp.141-159
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    • 2009
  • In this article, we consider a weighted CVT-based reduced-order modelling for Burgers equation. Brief review of the CVT (centroidal Voronoi tessellation) approaches to reduced-order bases are provided. In CVT-reduced order modelling, we start with a snapshot set just as is done in a POD (Proper Orthogonal Decomposition)-based setting. So far, the CVT was researched with uniform density ($\rho$(y) = 1) to determine the basis elements for the approximatin subspaces. Here, we shall investigate the technique of CVT with nonuniform density as a procedure to determine the basis elements for the approximating subspaces. Some numerical experiments including comparison of two CVT (CVT-uniform and CVT-nonuniform)-based algorithm with numerical results obtained from FEM(finite element method) and POD-based algorithm are reported.

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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 Algorithm and Response Characteristics of CVT (CVT의 변속 알고리듬과 응답특성)

  • Sung, D.H.;Kim, H.S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.6
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    • pp.9-17
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    • 1994
  • In this study, a shifting algorithm of CVT was suggested for the two(2) driving modes : (1) power mode and (2) economy mode. Shifting algorithm must be obtained to make the engine run on the optimum operating line for the desired performance of the vehicle. Optimum operating lines of the engine were obtained by connecting the shortest way of the iso-power lines for the power mode and by connecting the shortest way of the BSFC curves for the economy mode. Also dynamic model of CVT vehicle was derived considering the throttle and the brake operation. By using the shifting algorithm and the CVT vehicle model, numerical simulations were performed to estimate the performance of CVT. Simulation results showed that comparing the performance of the conventional 4-speed automatic transmission, acceleration performance of the CVT vehicle was almost same with the AT vehicle for the power mode and the fuel economy of CVT was 14% superior than that of AT for the economy mode.

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