• Title/Summary/Keyword: friction brake

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Characteristics of Aggression and Brake Judder by Different ZrSiO4 Particle Size (지르콘 입도 크기에 따른 디스크 공격성과 브레이크 져드 특성)

  • Lee, GirHyoung;Kang, KukHyoun;Lee, DongKyu
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.7
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    • pp.144-151
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    • 2014
  • Recently, according to the advances of vehicle manufacturing technology and the fuel-efficient vehicles, the weight of the vehicle body has been reduced and quietness of the vehicle has been increased. So that, as the emotional qualities of cars, such as NVH, are emphasized in recent years. Also required to be established of the effective measure for brake Judder. The Judder was caused by the increase in DTV by the uneven thermo metamorphosis of brake disc and the partial abrasion of disc. In this study, the disc aggression by friction materials was confirmed and the improving methods of friction materials in connection with the abrasive characteristics reviewed of $ZrSiO_4$ each particle size(under $3{\mu}m$, $5{\sim}10{\mu}m$ and over $15{\mu}m$). In addition, the study is institute make use of limit for $ZrSiO_4$ raw-material particle size and vol% in friction materials. At the result, the optimum size of $ZrSiO_4$ particles was confirmed about 5 to $10{\mu}m$.

Tribological Characteristics for High Perfomance Metallic Friction Materials (고성능 금속마찰재의 트라이볼로지적 특성)

  • 김석삼;김재호;안효준
    • Tribology and Lubricants
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    • v.14 no.1
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    • pp.45-53
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    • 1998
  • Friction and wear test for two kinds of Cu-based sintered metallic friction material against cast iron disk was carried out by plate-on-disk type friction and wear tester to investigate the friction and wear characteristics of brake system in severe condition. In this experimental study, the counter specimen was cast iron which is being used generally in brakes of heavy duty equipments. Test friction materials were A type which was manufactured by foreign company and B type by domestic company. Friction coefficient and wear volume were measured and compared with each other. The experiment was performed under room temperature. The worn surface of cast iron disk and friction material were observed by scanning electron microscope. The temperature of surface of disk was measured continuously by the non-contacting thermometer. It was found that A type friction material had stable friction coefficient over the wide range of sliding condition, but B type friction material had unstable friction coefficient and lower value of 0.2 under the severe sliding condition.

Study of Friction Charactedstics of Non-asbestos Organic (NAO) and Semi-metallic Brake Pads During Automotive Braking (자동차 제동시 나타나는 마찰재의 마찰 특성에 관한 연구 (II. 비석면계 유기질 (Non-asbestos Organic) 마찰재와 반금속 (Semi-metallic) 마찰재의 마찰 특성 비교))

  • Kim, Seong-Jin;Jang, Ho
    • Tribology and Lubricants
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    • v.13 no.3
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    • pp.10-19
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    • 1997
  • Frictional characteristics of two different types of automotive friction materials were studied. They were non-asbestos organic and semi-metallic friction materials. The two friction materials were tested using an inertial brake dynamometer to investigate friction stability, rooster tailing phenomena, temperature change during drags and stops. Results show that the level of the friction force is strong functions of time, temperature, and speed regardless of the type of friction materials. In particular, rooster tailing effects are pronounced in the case of semi-metallic friction materials compared to non-asbestos organic friction materials. The phenomena appear strongly dependent on raw materials contained in the friction materials.

Design for Yaw Brake System in Wind Turbine (풍력발전기 요 브레이크 시스템의 설계)

  • Park, Jin-Hwan;Park, Sang-Shin;Yoon, Yong-Ik;Yoo, Chang-Hee;Hwang, Jung-Gyu
    • Tribology and Lubricants
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    • v.27 no.4
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    • pp.204-208
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    • 2011
  • Yaw brakes are used in wind turbines to control the orientation of blades to be perpendicular to the wind. These devices are very important machine elements because they are closely related to the overall efficiency of wind turbines. One unit of yaw brakes is composed of a friction pad and a caliper. In this study, a tangential force between the friction pad and the disk is calculated when the brake is acting in 750 kW wind turbine. Then, stress distribution and the deformation of the caliper are calculated using a finite element analysis. An experimental equipment is also developed to verify the exactness of calculated results. The analytical and experimental results are presented and discussed.

Analysis of Out-of-plane Motion of a Disc Brake System Considering Contact Stiffness (접촉 강성을 고려한 디스크브레이크의 면외진동 해석)

  • Joe, Yong-Goo;Oh, Jae-Eung;Shin, Ki-Hong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.597-600
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    • 2004
  • A two-degree-of-freedom out-of-plane model with contact stiffness is presented to describe dynamical interaction between the pad and disc of a disc brake system. It is assumed that the out-of-plane motion of the system depends on the friction force acting along the in-plane direction. Dynamic friction coefficient is modelled as a function of both in-plane relative velocity and out-of-plane normal force. When the friction coefficient depends only on the relative velocity, the contact stiffness has the role of negative stiffness. The results of stability analysis show that the stiffness of both pad and disc are equally important. Complex eigenvalue analysis is conducted for the case that the friction coefficient is also dependent on the normal force. The results further verify the importance of the stiffness. It has also been found that increasing the gradient of friction coefficient with respect to the normal force makes the system more unstable. Nonlinear analysis is also performed to demonstrate various responses. Comparing the responses with experimental data has shown that the proposed model may qualitatively well represent a certain type of brake noise.

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Friction Coefficient of Emergency Braking on ABS and Non-ABS Car (ABS와 Non-ABS 승용차량의 급제동시 마찰계수 변화)

  • Kim, Kee-Nam;Lee, Ji-Hoon;Ok, Jin-Kyu;Yoo, Wan-Suk;Park, Ji-Yeong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.3
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    • pp.52-59
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    • 2008
  • Most accident reconstruction or analysis depend on the coefficient of friction to estimate the vehicle speeds. Skid mark and coefficient of friction are usually utilized to calculate the velocity and behavior of vehicles. For a critical case such as traffic accident reconstruction, however, the initial velocity of the car should be calculated precisely. In this paper, emergency brake tests on ABS and Non-ABS brake system are conducted on the dry pavement asphalt road on speed 40, 60, 80 and 100 km/h respectively. The SWIFT sensor was established in the front wheel and rear wheel at driver side to measure the forces, moments and speeds of revolution of the tires. These tests results can be available to brake tests and accident reconstruction.

Rear Drum Brake Grunt(stick-slip) Noise Improvement on Braking During Nose-dive & Return Condition (제동시 발생하는 리어 드럼브레이크 Grunt(stick-slip) Noise 개선)

  • Hong, Ilmin;Jang, Myunghoon;Kim, Sunho;Choi, Hongseok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.9
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    • pp.781-788
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    • 2013
  • 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 1 kHz 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.

A study on the improvement of frictional performance of friction material for automobile brake by spray treatment (용사처리에 의한 자동차 브레이크용 마찰재료의 마찰성능개선에 관한 연구)

  • 김윤해;배창원;손태관
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.1
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    • pp.67-76
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    • 1998
  • Friction materials for brake linings and clutches have severe performance requirements. The principal function of such frictional elements is to convert kinetic energy to heat, and then either to absorb or to dissipate heat. In order to achieve these objectives, the coefficient of friction must be as high as possible, independent of variations in operating conditions, and the necessary energy conversion must be accomplished with a minimum of wear on the contacting parts. In this study, Al powder, Al bronze powder and Mo powder used in general for automobile brake was sprayed on automobile brake disc to restrain rust and to maintain friction performance. Dynamo and corrosion tests have been carried out. It is concluded that the sprayed disc with Al bronze powder has the most improved frictional performance and anti-corrosive characteristics. The main results obtained can be summarized as follows; 1. From the corrosion current density test for gray cast iron and sprayed disc with powders of Al, Al bronze and Mo, it was cleared that the spray treatment with Al bronze powder showed the most superior anti-corrosive characteristics than other powders. 2. By anode polarization toward the noble direction from corrosion potential, corrosion current density with sprayed brake disc by Al-bronze powder was the lowest. 3. Mean frictional coefficients obtained from dynamo test are as follows : the sprayed disc with Al(99.99%) powder was 0.190 ; the sprayed disc with Al-bronze powder was 0.312 ; the sprayed disc with Mo powder was 0.257 ; the non-sprayed disc of gray cast iron was 0.331. In the case of the sprayed disc Al-bronze powder showed the most excellent frictional characteristics . 4. Amount of burnish quantity obtained from burnish test by dynamometer is as follows : the sprayed disc with Al-powder was 1.079 mm : the sprayed disc with Al-bronze powder was 0.155 mm : the sprayed disc with Mo powder was 0.253 mm : the non-sprayed disc of gray cast iron was 0.241 mm. Al-bronze powder also showed the most excellent burnish characteristics.

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Design of Wedge in the Electro-Mechanical Brakes for Commercial Vehicles to Boost Braking Friction Forces (브레이크 마찰력 증가를 위한 상용차용 전기-기계식 브레이크의 쐐기 설계)

  • Lee, Sang Min;Park, Jeonghun;Nam, Kanghyun;Yoo, Chang-Hee;Park, Sang-Shin
    • Tribology and Lubricants
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    • v.34 no.2
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    • pp.55-59
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    • 2018
  • This paper proposes a new type of electro-mechanical wedge brake for commercial vehicles. The brake operates on a novel mechanism for self-boosting braking friction forces using eccentric shafts, and involves wedges that are inserted between the rampbridge and traverse; this self-boosting mechanism is explained herein. A dynamic analysis using ADAMS was conducted, and the findings are reported. The constraint and contact conditions are explained to verify the precision of the dynamic analysis. The dynamic analysis shows that in the proposed mechanism, the self-boosting effect occurs as desired. However, it is also noted that the system has a limitation in terms of the production of unlimited braking forces that can jam the roller inside the wedges. After demonstrating the self-boosting effect, dynamic analyses are performed for several values of the wedge angles and friction coefficients between the brake pads and disks. Conventionally, a lower wedge angle has been suggested owing to its provision of a larger clamping force for given friction coefficients. However, it is noted that lower wedge angles can lead to a higher probability of occurrence of undesirable high braking forces, which can jam the roller into the wedge; thus, a larger wedge angle is preferable for avoiding the undesirable jamming phenomena. These analysis results are presented and discussed herein.

A Study on the Evaluation of Physical Properties of Polymer-based Composite Materials for the Brake of the Automobile (자동차 브레이크용 고분자복합재료의 물리적 특성평가에 관한 연구)

  • Son, Tae Gwan;Kim, Yun Hae;Kim, Bong Sik
    • Journal of Advanced Marine Engineering and Technology
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    • v.20 no.2
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    • pp.75-75
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    • 1996
  • The rapid expansion for the auto-industry and the worldwide trend toward non-asbestos friction materials for brake lining force our industry to transfer into non-asbestos ones from asbestos-based friction materials. Furthermore, it is imperative for the friction materials to have technological excellence and lower production cost to be competitive in the world market. There is no known theoretical procedures to formulate friction materials. It, rather, depends on the trial and error process. Thus, it is quite clear how important it is to accumulate the know-how on the formulation and manufacturing the friction material. This study concerns the practical ways of conceptualizing the formulation and optimizing the manufacturing process. This study focused on the development of formulation for non-asbestos friction material as well as deriving the physical properties of the trial product to prove its validity and applicability. Elaboration of the formula and optimizing scheme of the manufacturing process to get better quality are also sought. Physical properties were obtained by constant velocity test dynamotest, hardness test and strength test. Differential scanning calorimeter was also used to analyze the thermal reactions of organic constituents, microstructures, bond effects, and degree of mixture.