• International Journal of Automotive Technology
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• 제7권1호
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• pp.61-68
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• 2006

In design of the friction clutches of automobiles, knowledge on the thermo-elasticity a priori is very informative in the initial design stage. Especially, the precise prediction technique of maximum temperature and stress should be requested in design of mechanical clutches for their durability and compactness. In this study, an efficient and reliable analysis technique for the design of the mechanical clutches by using computer modeling and numerical method was developed. A commercial software STAR-$CD^{TM}$ was used to find the convective heat-transfer coefficients. MSC/$NASTRAN^{TM}$ software was followed to predict the temperature of clutch with utilization of estimated coefficients. Some experiments were also performed with a dynamometer to verify the procedure and calibrate the thermal load. As a conclusion, a design procedure, including numerical steps and experimental techniques for calibration, was proposed.

• Tribology and Lubricants
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• 제25권4호
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• pp.243-249
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• 2009

A magnetic clutch consists of pulley and disk. It delivers and isolates the power needed for the operation of the compressor used in automotive air conditioning system. To improve the performance, efficiency and durability of automotive air conditioning system, appropriate design of pulley, disk and system working parameters(the magnitude of magnetic force, and so on) is necessary. For that goal, it is required to understand the friction characteristics of magnetic clutch for the initial operating time. In this study, friction tests were carried out in order to investigate the effect of sliding velocity on the friction characteristics of magnetic clutch using pin-on-disk type friction and wear tester. For experiments, pulley and disk used in real automotive air conditioning system were considered. Friction experiments were conducted under various sliding velocities, and coefficients of kinetic friction were obtained. Under the experimental conditions considered in this study, the coefficients of kinetic friction increased with the increase of test number(sliding distance) and decreased with the increase of sliding velocity.

• Tribology and Lubricants
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• 제22권4호
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• pp.196-202
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• 2006

This paper presents a case study on the tribological failure analysis of a clutch system for a manual transmission car. The clutch systems are composed of clutch disk, clutch pressure plate, flywheel rubbing surface, coil and diaphragm springs, release bearing and lever, clutch spline and shaft. The purpose of a clutch system is to transmit and disconnect the driving power of engines by frictional farce from a rubbing surface of a flywheel to a clutch disk and clutch pressure plate with a minimum power loss. In this study, many tribological failure cases based on the wear phenomena and thermal distortions have been presented, which are collected from the car repair shop and maintenance center. The triboiogicai failures are mostly come from the driving conditions, overloading of a car, and especially driving style and personal habit of a car driver.

• Advances in Automotive Engineering
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• 제1권1호
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• pp.21-39
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• 2018

Clutch energy is the thermal energy dissipated on the clutch disc, and it reaches its highest level during drive-off as a result of the difference between the angular speeds of the flywheel and clutch disc, and the torque transmitted. The thermal energy dissipated effects the clutch life. This study presents a new drive-off and thermal model to calculate the clutch energy for a rear wheel driven heavy-duty vehicle and to analyze the effects of clutch energy on temperatures of clutch pressure plate, flywheel and clutch housing. Three different driver profiles are used, based on the release of the clutch pedal in modulation zone: i) the pedal travels with the same speed all the way, ii) the travel speed of the pedal increases, iii) the travel speed of the pedal decreases. Vehicle test is performed to check the accuracy of the model. When compared to a simpler model that is widely used in the literature to calculate the clutch energy, the model used in this study calculates the clutch energy and angular speed behaviors of flywheel and transmission input shaft in better agreement with experimental results. Clutch wear and total clutch life are also estimated using the mean specific friction power.

• 한국자동차공학회논문집
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• 제12권4호
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• pp.119-128
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• 2004

With the growing traffic density and increasing comfort requirements, the automation of the drive train will gain importance in vehicles. The automatic clutch actuation relieves the drivers especially in urban driving and stop-and-go traffic conditions. This paper describes the dynamic modeling of a clutch actuator and clutch spring. The dynamic model of the clutch system is developed using MATLAB/Simulink, and evaluated by experimental data using a test rig. This performance simulator is useful to develop the clutch-by-wire (CBW) system for an automated manual transmission (AMT). The electro-mechanical type CBW system is also implemented as an automatic clutch for AMT. The prototype of CBW system is designed and implemented systematically, which is composed of an electric motor, worm gear and slider-crank mechanism. The test rig is developed to perform the basic function test of the automatic clutch, and the developed prototype is validated by the experimental data on the test rig.

• 한국가스학회지
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• 제19권3호
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• pp.49-53
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• 2015

이 논문의 목적은 자동차 클러치, 수동변속기와 타이어 시스템의 마찰에 관련된 화재에 대한 고장사례를 분석하고 연구하는 것이다. 첫 번째 사례는 반복적으로 클러칭하면서 자동차의 클러치 디스크가 플라이 휠의 접촉면과 접촉하면서 열에 의해 과열되어 이 열이 수동변속기의 외부로 흘러 고착된 오일 찌꺼기에 옮겨 붙어 화재가 발생된 것으로 확인되었다. 두 번째, 사례로 변속 장치는 기어와 기어의 접촉에 의해 동력을 전달한다. 변속기 오일이 변속기 케이스의 균열로 인해 오일 부족 현상이 일어나 변속기 케이스 상단의 퇴적물에 의해 화재가 발생된 것을 확인하였다. 세번째 사례는 건조한 구덩이에서 빠져나오려고 반복적으로 가속페달을 작동시키면서 타이어와 도로의 마찰이 반복되면서 내부의 축적된 열에 의해서 화재가 발생된 것으로 확인되었다. 따라서, 운전자는 운전 중 마찰부에 화재가 발생하지 않도록 세심하게 관리하여야 한다.

• 소성∙가공
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• 제20권2호
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• pp.154-159
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• 2011

The roll die forming (RDF) process is a new manufacturing technique for producing gear parts such as clutch drum and clutch hub in automotive transmission. In the RDF process, the material is deformed by a roll installed on a die set. Excellent productivity, low forming load and improved dimensional accuracy have quantitatively been shown to be the benefits of the RDF. In this study, the RDF process is applied to manufacture a clutch hub with a gear shaped part. A finite element (FE) analysis was performed in order to investigate the material strain field and dimension of the final product. Based on the result of the FE analysis, a RDF experiment was performed and the dimensional accuracy of the final product was validated. This work demonstrates that RDF is a process capable of producing a sound clutch hub.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.1-7
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• 2013

This paper focuses on cooling fan control by using a magnetic clutch type for the improvement of fuel economy on a heavy city bus. In general, Heavy duty vehicles use viscous clutch type cooling fan which has some disadvantages, such as slow response, wide temperature variation of engine coolant water. But a magnetic clutch type cooling fan can be controlled electronically so the engine coolant temperature can be precisely controllable and this effects could be used to reduce fuel consumption. A control system for applying the magnetic clutch type cooling fan was developed in this study and applied to the real field test and chassis dynamometer test. The result showed well controlled coolant temperature and enhancement of fuel economy.

• Tribology and Lubricants
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• 제30권2호
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• pp.92-98
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• 2014

Transmission fluid film behaviors in the gap between the wet clutch pad and separator plate are analyzed using the CFD software ADINA. Three pattern groove designs are selected and are used to validate the fluid film behaviors based on the outlet flow in the gap when the wet clutch pad and separator plate are engaged. The main design goal for pattern grooves is faster engagement. In most cases, much of the outlet flow of transmission fluid in the gap occurs on the outer radius boundary due to the centrifugal force generated by the clutch pad circular motion. Groove patterns are created to ensure faster transmission fluid outlet flow in the direction of the inner radius boundary. Computational results of the selected groove patterns are compared.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.235-240
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• 2003

Auto transmission system is composed by torque converter. clutch, brake, planetary goat and valve body controlling oil pressure. In the automatic transmission, the most largest influence elements are torque converter and clutch for oil performance. In this piper I studied failure of tribology causing sealing poor of the acting parts, leakage of the oil pressure and poor of the lubrication.