• 한국산학기술학회논문지
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• 제20권10호
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• pp.117-124
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• 2019

국군이 운용중인 대부분의 군 전용차량은 개발이 완료된지 15년이 넘었으며, 개발 당시의 기술력과 정비성을 고려하여 수동변속기를 채택하고 있다. 수동변속기는 엔진과 변속기 사이에 동력을 조절/차단하는 클러치를 포함한다. 본 연구의 대상이 되는 2.5톤 군용차량은 수동변속기와 클러치 시스템을 적용하고, 클러치 커버와 릴리스 베어링 간극을 수동으로 조절해야 했다. 이러한 특성으로 인하여 클러치 디스크 조기마모, 클러치 커버 파손 등의 품질문제가 발생하였다. 본 연구는 발생된 품질문제를 해결하기 위하여, 클러치 커버와 릴리스 베어링의 간극을 자동으로 설정하도록 하고 클러치 디스크 자체의 성능도 향상시키는 과정을 거쳤다. 개선된 시스템을 평가하기 위해서, 단시간에 기어변속을 하는 가속내구시험을 수행하였으며 추가적으로 군인이 직접 운전을 하여 차량에 적용하였을 때 이상이 없음을 증명하였다. 본 연구활동을 통해, 클러치 간극을 조정할 필요가 없도록 하여 차량 정비 인력의 정비시간을 단축하였다. 또한, 클러치 간극을 조정해 주지 못함으로써 발생되는 품질문제를 해소하여, 근본적인 개선책을 제시하였다고 볼 수 있다.

• 한국자동차공학회논문집
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• 제12권4호
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• pp.146-153
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• 2004

This paper presents a discrete analysis approach to investigate the performance of dual mass flywheel (DMF). In the discrete analysis, arcspring installed between the flywheels is modeled as N- discrete elements. Each element consists of mass, spring and nonlinear friction element. LuGre friction model is used to describe nonlinear friction characteristic. Based on the dynamic models of the DMF, clutch, engine, manual transmission and vehicle, a DMF performance simulator is developed using MATLAB Simulink. Simulation results of the engine speed, driveshaft torque and vehicle velocity are compared with test results. It is found that the discrete DMF model describes the vehicle behavior closely, especially during the clutch actuation period.

• 소음진동
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• 제9권5호
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• pp.936-942
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• 1999

Unstable torsional vibration on the marine ship's propulsion shafting system with diesel engine occurred due to a slippage of multi-friction clutch which was installed between increasing gear and shaft generator. In this paper, the mechanism of this vibration was verified via torsional, whirling, axial and structural vibration measurements of shafting system and noise measurement of gear box. And it was also identified by the theoretical analysis method.

• 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.

• Journal of Biosystems Engineering
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• 제21권2호
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• pp.134-145
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• 1996

Since the skid-steer loader is able to work for excavating, lifting and transporting load even at the narrow space, they are widely used in the regular farm and the livestock farm. The skid-steer loader normally adopts the hydrostatic transmission because the power to move the machine backward and forward should be delivered independently on both sides of wheels. Contrast to the mechanical system such as chain and belt transmissions, however, the hydrostatic transmission is less efficient in the use of energy and more difficult in the maintenance. This study was intended to investigate the feasibility of using triangular-type belt clutch and V-belt transmission for the newly developed skid-steer loader in order to overcome the problems stated in the hydrostatic transmission. In the developed triangular-type belt clutch, the centers of driving, driven and idler sheaves are arranged in the triangular shape in a plane, and V-belts were loaded loosely on three sheaves. The power is transmitted by pressing the idler connected to a lever on the loosened V-belt. Contrast to the normal belt clutch using two sheaves, the newly developed belt clutch has the characteristics of small contact-angle of the driving sheave at no bucket load and increasing contact-angle at the time of power transmission. The results of research can be summarized as follows: 1) The developed triangular-type belt clutch adopted a spring-loaded slackside idler which could transmit more power than a fixed idler could by sacrificing the belt life. The life of V-belt used in the power transmission reached at 500 hours(6 months) when the engine power of 11.8 ㎾ was transmitted. Also, it was feasible to develop the large industrial skid-loader with the V-belt transmission by using the proper set of sheaves. 2) The developed skid-steer loader changed the rotating radius and speed with bucket loads as the conventional skid steer loader did. The rotating speed was 47 deg/s at the maximum bucket load of 2.74 kN when the minimum rotating radius was 1.5m. 3) The power required in turning at the bucket load of 2.74 kN was 4 ㎾ and the slippage of V-belt was less than 1%.

• 대한기계학회논문집A
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• 제22권4호
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• pp.762-767
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• 1998

The main torsional vibration source of the powertrain is the fluctuation of engine torque. The gear rattle is impact generating in the backlash of the free gear due to this torsional vibration. Optimization of the clutch torsional characteristic is one of the effective method to reduce the idle gear rattle. Many researches have been reported on this problem but only few of them give sufficient consideration to the detailed clutch modeling and the experiment. This paper pays attention to the optimization of clutch design parameters and the experiment to reduce the idle gear rattle vibration and noise.

• 한국소음진동공학회논문집
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• 제26권4호
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• pp.436-442
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• 2016

This paper presents the torsional vibration isolation performance evaluation of a centrifugal pendulum absorbers (CPAs) that has a continuously varying resonance frequencies proportional to engine firing (excitation) order. CPAs are commonly used to suppress torsional vibrations in rotating machinery and internal combustion engines. In this study, they are employed on the current spring type torsional damper inside a torque converter of automotive vehicle. To evaluate the effectiveness of designed resonance tuning order, the torsional vibration transmissibility based on torque measurements with respect to different engine firing orders is experimentally measured with a lower-inertia dynamometer. The torsional vibration transmissibility with respect to different frequencies with engine order of 2 is also evaluated. It has been demonstrated that the significant vibration reduction over operational frequency range of interest can be achieved by attaching simple pendulums. Future research direction includes the study on theoretical analysis, improved design of pendulum etc.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.105-114
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• 2001

In this study, a shift control algorithm far improving the shift quality of a parallel hybrid drivetrain with an automated manual transmission (AM) is proposed. The general AMT requires the sophisticated control of clutch in the clutch engagement to improve its shift characteristics, and that is generally known to be difficult. But in this hybrid drivetrain, we can control the speeds of clutch plates by engine and motor control, and it provides the easier clutch control in shift process than general AMT. Additionally, it permits the much-reduced shift shock. The motor control during the shift period is also to achieve reduced velocity drop of the vehicle in comparison with that of a general AMT. Furthermore various dynamometer-based experiments are carried out to prove the validity of the proposed shift control algorithm.

• Journal of Biosystems Engineering
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• 제40권2호
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• pp.95-101
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• 2015

Purpose: During the start-up period, the response time of a hydraulic system increases in the winter because of the increased oil viscosity caused by the cold weather. The problems of delayed tractor starting and excessive wear of the clutch disk occur for these reasons. Therefore, this study develops an analysis model using the commercial hydraulic analysis program AMESim to examine the characteristics of delays in power shuttle starting at different oil temperatures. Methods: In the experiment, a tractor was stationary on a flat surface with the engine running at a constant speed of 1,080 rpm. The forward lever was then pressed to activate the power shuttle at three different oil temperatures, and the pressure changes were measured. The pressure on the forward clutch control valve was measured by a pressure gauge installed on the hydraulic line supplied to the transmission from the main valve. An analysis model was also developed and verified with actual tests. Results: The trend of the simulated pressures of the power shuttle is similar to that of the measured pressures, and a constant modulation period was observed in both the simulation and test results. However, the difference found between the simulation and test results was the initial pressure required to overcome the initial force of the clutch spring. Conclusions: This study also examines the characteristics of the delayed startup of the power shuttle at different oil temperatures through simulations.

• Tribology and Lubricants
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• 제33권2호
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• pp.71-78
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• 2017

The drag torque in the wet clutch system of a dual clutch transmission system is investigated because it is relatively high, up to 10 of the total output torque of the engine, even when the clutch is in the disengagement state with zero torque transfer. Drag torque results from the shear resistance of the DCTF between the friction pad and separator plate. To reduce the drag torque for ensuring fuel economy, the groove pattern of the wet clutch friction pad is designed to have a high flow rate through the pattern groove. In this study, four types of groove patterns on the friction pad are designed. The volume fraction of the DCTF (VOF) and hydrodynamic pressure developments in the gap between the friction pad and separator plate are computed to correlate with the computation of the drag torque. From the computational results, it is found that a high VOF and hydrodynamics increase the drag torque resulting from the shear resistance of the DCTF. Therefore, a patterned groove design should be used for increasing the flow rate to have more air parts in the gap to reduce the drag torque. In this study, ANSYS FLUENT is used to solve the flow analysis.