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제동시 발생하는 리어 드럼브레이크 grunt (stick-slip) noise 개선
홍일민(Ilmin Hong),장명훈(Myunghoon Jang),김선호(Sunho Kim),최홍석(Hongseok Choi) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.10
Grunt (Stick-slip) noise happens between rear lining and drum on braking condition while vehicle is returning to steady position after nose-dive. The study presents a new testing and analysis methods for improving brake grunt noise on vehicle. Grunt noise is called a kind of stick slip noise with below 1kHz frequency that is caused by the surfaces alternating between sticking to each other and sliding over each other with a corresponding change in friction force. This noise is typically come from that the static friction coefficient of surfaces is much higher than the kinetic friction coefficient. For the identification of the excitation mechanism and improvement of grunt noise, it is necessary to study variable parameters of rear drum brake systems on vehicle and to implement CAE analysis with stick slip model of drum brake. The aim of this study has been to find solution parameters throughout test result on vehicle and dynamo test. As a result of this study, it is generated from stick slip between rear lining and rear drum and it can be solved to reduce contact angle of lining with asymmetric and is effected not only brake drum strength but also rear brake size and brake factor.
실차 상태에서의 제동시 이상떨림 현상에 관한 실험적 연구
홍일민(Hong, Il-Min),이원섭(Lee, Won-Sub),이종수(Lee, Jong-Soo) 한국소음진동공학회 2002 한국소음진동공학회 논문집 Vol.12 No.5
The study presents a new testing and analysis method for brake judder on vehicle. For the identification of the excitation mechanism of a brake judder, it is necessary to measure the dynamic brake disc geometry during braking on vehicle. The non-contact sensor system was used to monitor the brake disc geometry. Brake torque variation (BTV) caused by disc thickness variation (DTV) is the primary excitation for brake judder. The mechanical effects generating BTV are linked not only to initial manufacturing tolerances but also to uneven wear. Therefore, the brake disc geometry should be strictly managed to initial condition. The aim of this study has been to measure the dynamic DTV and runout on vehicle and analyze the influence of test parameters on brake judder and compare the disc component with vehicle matching about the DTV Profile. As a result of this study, The amplitude of brake judder is proportional to vehicle speed and fluid pressure fluctuation on braking. The major sources of brake judder are directly related to disc thickness variation and side runout variation of corner assembly (disc, hub. bearing).
신준호,원유진,홍일민,Shin, Junho,Won, Eugene,Hong, Ilmin 한국자동차안전학회 2014 자동차안전학회지 Vol.6 No.2
Based on the analysis of the actual passenger vehicle fire cases for recent four years (2010~2013), the passenger vehicle fire is increasing annually. Main root cause was analyzed as an electric problem as a 39%. Vehicle fire case by electric problem was mainly caused by use of Non-genuine part. Vehicle fire case by mechanical problem was mainly caused by various oil system maintenance. Vehicle fire case by smoking material was mainly caused by cigarette and disposal lighter. And external fire transition issue and towing mistake fire cases was also confirmed.
브레이크 디스크의 FNC 코팅 두께에 따른 마찰계수 및 내식성 영향도 평가
김용탁(Yongtak Kim),홍일민(Ilmin Hong) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.5
Brake disc anti-corrosion performance has been improved in various ways for customer emotional satisfaction. Ferritic nitrocarburizing(FNC) is one of the methods used for anti-rust surface treatment, and it is currently in the spotlight as a brake disc rust prevention method. However, there are different kinds of performance requirements for brake corner system to satisfy customers, and every so often, several test results are found to be inconsistent. The brake friction value setting compromising with the other performance is the first priority in brake system development in order to have a sufficient fundamental “braking” function. In this paper, we studied the effect of the brake friction value by FNC compound layer thickness with scaled dynamometer testing, and we determined how the anti-corrosion performance shows for each respective case via complex environment salt spray testing.
Experimental Study of brake pipe oil leak by sealing performance impro vement
Jeehyung Lee(이지형),Ilmin Hong(홍일민),Sunho Kim(김선호) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
The study presents how the characteristic of brake tube nut surface treatment can be affected brake oil leak at pipe connection area. Brake oil leak issue is one of the most chronic problems in Automobile manufacturing and as the issue is normally approached by torque increase for containment or improving part quality and assembly quality, the problem is fluctuated due to the quality control. According to vehicle corrosion requirement is gradually severe and workers require easier finger-start for brake pipe installation, brake tube nut surface treatment is selecting ZnNi rather than Zn. If we control the same coefficient of friction spec for both, there is no difference for sealing performance in theoretical. Even though Zn surface treatment is regarded better sealing performance than ZnNi empirically by sealing mark test result, there was no objective evidence of relationship between sealing mark and brake oil leak and it is very difficult to define with CAE analysis So, we approached this issue as below - Comparison brake pipe flare and tube nut - Comparison leak test with brake pipe and tube nut each supplier - Comparison leak test with different machining method to increase thread length - Comparison leak test with pipe misalignment condition - Comparison seal mark test according to tube nut friction of surface treatment - Comparison seal mark test for tube nut surface treatment (ZnNi vs Zn) From the experimental study, we verified what dominant factor is for brake pipe sealing. We checked the ZnNi surface treatment has lighter seal mark than Zn cause by increasing friction and found the friction increase because ZnNi layer of tube nut at thread area can easily be damaged at aluminum port without anodized surface. As a result of the experimental study, tube nut surface treatment shouldn’t be selected ZnNi because most of modulator material are aluminum without anodized surface. If ZnNi should be applied for corrosion improvement and easier finger-start, it should be considered the torque increasing.