• 한국자동차공학회논문집
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• 제12권2호
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• pp.175-181
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• 2004

Analysis of brake characteristics has progressed rapidly in recent years, as computer techniques have developed. However, there are many problems in predicting braking characteristics, due to the numerous design variables of the brake system. Therefore, a synthetic braking performance analysis is required for all brake system parts such as master cylinder, booster, control valve and split system. In this paper, a program which can analyze braking performance such as force distribution, braking efficiency, pedal force and pedal travel, is presented. The preprocessor of the program helps users prepare input files through a dialog box. An additional postprocessor makes the graph presentation of solved results. Also, a simple example problem is applied to show the usefulness of the presented program.

• 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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• 제14권4호
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• pp.32-38
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• 2006

A clutch hydraulic system for automotive manual transmissions transfers hydraulic pressure generated by driver's pedal manipulation to the clutch mechanism. The foot effort when the clutch pedal is pushed is different than that when the clutch is returned. The effort or load difference, called hysteresis, is caused by the friction produced between rubber seal and inner wall inside the hydraulic cylinder. This clutch pedal travel foot effort hysteresis is essential for a clutch hydraulic system design and analysis. The dynamic model for a clutch hydraulic system is developed and a simulation analysis is performed to estimate the fiction coefficient as a function of the cylinder pressure. The simulation result is then compared to the measurements obtained from a clutch hydraulic system tester to ensure the reliability of the dynamic model and the coefficients estimated. Also the estimated friction coefficients at various pressure values are compared to those reported by an independent study.

• 대한교통학회지
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• 제24권1호
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• pp.53-58
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• 2006

본 연구에서는 오토차량 운전자의 피로를 덜어주기 위해 개발된 보조 발판(heel rest)에 대한 안전성 테스트를 실시하였다 기존에 개발된 자동차 모의 운전장치를 이용하여 30대, 40대, 50대 운전자 남녀 각 10명씩 60명의 실험참가자를 대상으로 보조 발판을 장착했을 때와 그렇지 않을 때 주행 상황 하에서의 주행 중 급제동 능력(반응시간)을 측정하였다. 30초간의 자율적인 초기 적응 과정과 실험 환경에 적응하기 위한 훈련을 진행하고, 반응 시간 측정을 실시하였다. 반응 시간 측정 실험에서는 실험참가자로 하여금 가상 주행 운전 상황에서 임의의 시간에 주어진 갑작스런 신호(붉은색 신호등 표시)에 대하여 반응을 하도록 하였다. 실험 결과, 보조발판은 사용하지 않았을 때와 비교하여 급제동시 반응 시간에 영향을 미치지 않는 것으로 나타났다. 이러한 결과는 운전자의 하지 관절과 근육피로를 감소시키기 위한 보조 발판이 급제동과 같은 위급한 상항에도 일반 페달과 유사한 반응시간을 보인다는 것을 확인해 주었다.

• 자동차안전학회지
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• 제12권2호
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• pp.7-13
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• 2020

Recently, there is a big issue of downsizing on brake system according to fuel efficiency and regenerative braking cooperation control. Especially, small cars have improved in a variety ways such as electric vehicle and smart car compared to previous small cars. So, small brake system is strongly required in the car industry. A new small brake system for light compact vehicles was proposed in this paper. For this system, the solid type disc and caliper were newly developed. And the important design factors were considered to reduce brake size. First, we calculated the temperature rise of disc through heat capacity formula and CAE analysis. Second, we analyzed the housing and carrier stiffness of caliper to select the reasonable condition. Finally, the superiorities of the developed brake system were verified by heat capacity, consumption liquid level, braking feeling, judder, wear test and regenerative braking cooperation control analysis. A developed brake system is expected to be useful for brake system of light compact platform.

• 소음진동
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• 제11권3호
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• pp.461-470
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• 2001

A friction-type clutch system sometimes generates spick-slip vibration during engagement, which disturbs smooth start of a car and makes a passenger uncomfortable. In this study, the spick-slip vibration in four types of friction couples was investigated at two different engagement conditions respectively of which the amount of slip time and clutch travel was varied. Results are found as follows. First, the vibration increased at the condition of small engine torque and large torque fluctuations due to higher harmonics of engine speed. Second, the friction couple without a pre-damper has advantages of reducing the vibration. This study also suggested an evaluation method of vehicle vibration in the view point of human perception by using the frequency weighting of ISO2631-1.

• 자동차안전학회지
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• 제14권3호
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• pp.17-22
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• 2022

In this paper, we propose the improved EDR (Event Data Recorder) storage data, which can identify the cause of unintended acceleration of eco-friendly vehicles. The proposed EDR storage data includes the brake pressure sensor value and a brake pedal travel sensor value. To verify the proposed EDR storage data, we observe the control algorithm and internal structure of the vehicle dynamic control system and a regenerative braking system in an eco-friendly vehicle.