• Journal of Drive and Control
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• v.10 no.4
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• pp.7-13
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• 2013

A tractor is a farm vehicle that is designed to provide a high tractive effort at low speed. It is used for versatile agricultural tasks such as hauling a trailer, tillage, mowing and construction work. As the intensity of work increases, tractors equipped with automatic transmission become popular due to the work convenience. Though manual and power shuttle transmissions are produced by domestic corporations, development for full-automatic power shift transmissions has never been challenged, and so related technology level is quite low. This paper gives a survey of the automatic transmissions from advanced foreign company, which includes layout of gear train, the way hydraulics controls clutches and brakes, electronic control system. The results are expected to be utilized as a basis in the development of original power train design for tractor.

• 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.

• 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.

• Journal of the korean Society of Automotive Engineers
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• v.17 no.5
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• pp.28-35
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• 1995

본 해설에서는 클러치 제어용 유압계 특성에 대하여 간략히 서술하고 각 장치즐의 장단점을 비교 검토함과 동시에, 본 저자들이 개발한 클러치 조작용 유압계에 쓰이는 압력조절장치에 대하여 설명한다. 1. 변속장치내 클러치 조작용 유압계 특성. 1.1 클러치 조작용 유압계 제어의 필요성. 1.2 변속시 충격 토크의 저감법. 1.3 클러치 조작용 유압계의 제어방식.

• Journal of Drive and Control
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• v.13 no.1
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• pp.1-9
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• 2016

Nowadays automatic transmission equipped vehicles prevail in construction and agricultural equipment due to their convenience in driving and operation. Though domestic vehicle manufacturers install imported electronic controlled transmissions at present, overseas products will be replaced by domestic ones in the near future owing to development efforts over the past 10 years. For passenger cars, there are many kinds of shift control algorithms that enhance the shift quality such as feedback and learning control. However, since shift control technologies for heavy duty vehicles are not highly developed, it is possible to improve the shift quality with an organized control method. A feedback control algorithm for neutral-into-gear shift, which is enabled during the inertia phase for the master clutch slip speed to track the slip speed reference, is proposed based on the power transmission structure of TH100. The performance of the feedback shift control is verified by a vehicle test which is implemented with firmware embedded TCU. As the master clutch engages along the predetermined speed trajectory, it can be concluded that the shift quality can be managed by a shift time control parameter. By extending the proposed feedback algorithm for neutral-into-gear shift to gear change and shuttle shift, it is expected that the quality of the shift can be improved.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.59-64
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• 2024

In this study, we conducted research on a miniaturized transmission system suitable for ultra-compact electric vehicles, such as electric arts or small electric cars. While conventional electric vehicles eliminate multi-gear transmissions and control motor output or secure initial driving force through reducers, in vehicles like electric karts or compact electric cars, which have relatively small battery capacities, the driving range can be reduced or the motor can be stressed epending on the loading state. Therefore, in this study, we developed a low stage ratio 0.625 and high stage ratio 1.6 a two-stage transmission system that can change gears as needed, considering factors such as slope conditions and loading status, by applying the continuously variable transmission (CVT) mechanism. Based on the selected gear ratios, we designed the transmission and created a test rig to verify the power transmission efficiency of the developed transmission. Using the test rig, we varied the rotational speed and load of the transmission to confirm its power transmission characteristics and also examined the heat generation characteristics during shifting and operation. As a result, developed a two-stage transmission with a CVT structure.

• Journal of Drive and Control
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• v.20 no.4
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• pp.17-26
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• 2023

A forklift is an industrial vehicle that lifts or transports heavy objects using a hydraulically operated fork, and is equipped with an automatic transmission for the convenience of repetitive transportation, loading, and unloading work. The Transmission Control Unit (TCU) is a key component in charge of the shift control function of an automatic transmission. It consists of an electric circuit with an input/output signal interface function and firmware running on a microcontroller. To develop TCU firmware, the development process of shifting algorithm design, firmware programming, verification test, and performance improvement must be repeated. A simulator is a device that simulates a mechanical system having dynamic characteristics in real time and simulates various sensor signals installed in the system. The embedded transmission simulator is a simulator that is embedded in the TCU firmware. information related to the mechanical system that is necessary for TCU normal operation. In this study, an embedded transmission simulator applied to the originally developed forklift TCU firmware was designed and used to verify various forklift shift control algorithms.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.95-104
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• 1997

We consider controller design problem to enhance shift quality for automatic transmission. A dynamic modeling related to shifting (mainly 2-3 up-shift) is constructed and nonlinear robust controllers are designed to reduce output torque during shifting. Suggesting a new hydraulic circuit enabling the direct clutch drive, the control activity is extended and more implementable than the conventional design. The designed robust controllers overcome the unmodeled dynamics and the uncertainty embending in the system. Moreover, the dynamic effect between the clutch pressure and the PWM valve duty is considered via singular perturbation technique.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.1078-1082
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• 1996

기계적 구동장치와 연계된 메카트로닉스 시스템에 대한 개발 시험은 비용, 공간 및 시간 등의 측면에서 제약을 받는다. 이러한 제약은 에뮬레이터를 이용한 개발 과정을 통해서 개선의 효과를 얻을 수 있다. 본 연구에서 설계 제작된 에뮬레이터는 전자 제어식 변속기에 적용된 장치로서 기계적 메카니즘 없이 전자 제어 메카니즘을 완전하게 에뮬레이션 할 수 있는 가능성을 보여준 것이다. 이러한 에뮬레이터를 이용하여 전자 제어장치의 개발 기간을 단축시키고 문제점을 빠르게 찾아낼 수 있다. 에뮬레이터의 개발은 수학적 모델링에 의해서, 장치에 대한 검증은 실차 시험을 통해 얻을 결과와 비교하여 수행된다.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.296-297
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• 2010

본 연구는 자전거의 속도를 이용하여 자동으로 기어변속을 하는 시스템 개발에 관한 연구이다. 본 논문은 자전거의 기어변속 메커니즘을 활용하여 기어 변속기를 개선함으로써 진행속도에 맞추어 자동으로 기어 변속을 수행하는 시스템의 설계 및 개발에 관하여 서술하였다. 상세하게는 뒷바퀴에 속도 측정장치를 설치하여 회전수에 따라 자전거의 진행하는 속도를 감지하며, 기존 자전거의 변속기에 개발된 전자제어장치를 탑재하여 운행자의 진행속도에 맞추어 자동변속을 구현한다.