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2016-09-18
Technical Paper
2016-01-1920
Deaglan O'Meachair, Stamatis Angelinas, Matthew Crumpton, Antonio Rubio Flores, Juan Garcia, Pablo Barles
Abstract Bentley Motors Ltd. has developed a Carbon Silicon Carbide (CSiC) brake system for its Mulsanne product, introduced at 17MY. The CSiC brake system is conceived as a performance brake system, and as such offers notable improvements in brake performance. In developing the brake system, particular focus was placed on meeting the refinement levels required for a premium product, and indeed as the flagship model for Bentley Motors, NVH refinement of the brake system was of particular concern. This paper intends to discuss the technical performance of the brake system and review the NVH performance of the brakes. Particular attention is given to the methodology employed by Bentley Motors Ltd. and IDIADA Automotive Technology S.A. in identifying NVH concerns, and proposing and validating solutions in the field, through extensive NVH endurance runs. The performance of the system is benchmarked against similar systems offered by Bentley Motors.
2016-09-18
Technical Paper
2016-01-1935
Binyu Mei, Xuexun Guo, Gangfeng Tan, Ming Chen, Bo Huang, Longjie Xiao
Abstract With the continuous increasing requirements of commercial vehicle weight and speed on highway transportation, conventional friction brake is difficult to meet the braking performance. To ensure the driving safety of the vehicle in the hilly region, the eddy current retarder (ECR) has been widely used due to its fast response, lower prices and convenient installation. ECR brakes the vehicle through the electromagnetic force generated by the current, and converted vehicle mechanical energy into heat through magnetic field. Air cooling structure is often used in the traditional ECR and cooling performance is limited, which causes low braking torque, thermal recession, and low reliability and so on. The water jacket has been equipped outside the eddy current region in this study, and the electric ECR is cooled through the water circulating in the circuit, which prolongs its working time.
2016-09-18
Technical Paper
2016-01-1934
Arun Kumar Prasad, Baskar Anthonysamy, V.A. Gopalakrishn, Gurdeep Singh Pahwa
Abstract Fierce competition in India’s automotive industry has led to constant production innovation among manufactures. This has resulted in the reduction of the life cycle of the design philosophies and design tools. One of the performance factors that have continues to challenge automotive designer is to design and fine tune the braking performance with low cost and short life cycle. Braking performance of automotive vehicle is facilitated by the adhesion between the tyre and the ground. Braking force generated at the wheels of a vehicle have to appropriately match to the adhesion. Antilock braking system (ABS) is used for this purpose. ABS is a modern braking system which could significantly improve directional stability and reduce stopping distance of a vehicle. However this system still too complicated and expensive to use in low end compact car and pickup truck.
2016-09-18
Technical Paper
2016-01-1933
Mingzhuo Li, Dejian Meng, Lijun Zhang
Abstract Brake judder severely affects the riding comfort and safety of vehicle. For the brake corner system, a rigid-flexible coupling model is established based on ADAMS. In the model, brake pads, caliper, anchor and knuckle are flexible bodies, and the contacts between pads and disc and the contacts between pads and caliper are defined in detail. Meanwhile, the vibration acceleration of the brake corner components and the contact forces between disc and pads are used as evaluation index and the evaluation system of brake judder are improved. The analysis results show that the novel model and evaluation system can be used to predict brake judder effectively.
2016-09-18
Technical Paper
2016-01-1932
Niclas Strömberg
Abstract During several years a toolbox for performing virtual rig tests of disc brake systems has been developed by the author. A thermo-flexible multi-body model of a test rig is derived and implemented by coupling two types of models: a finite element model and a multi-body model. The finite element model is a thermo-mechanical model of the pad-disc system that is formulated including thermo-elasticity, frictional contact and wear. The energy balance of the contact interface is governed by contact conductance that depends linearly on the contact pressure and the frictional heat depends on a temperature dependent coefficient of friction. Instead of adopting a standard Lagrangian approach, the disc is formulated in an Eulerian frame like a fluid. This is then coupled to the pad most accurately by using Signorini’s contact conditions, Coulomb’s law of friction and Archard’s law of wear.
2016-09-18
Technical Paper
2016-01-1941
Tie Wang, Gangfeng Tan, Xuexun Guo, Shengguang Xiong, Zhiwei Zhang, Xin Gao
Abstract Vehicle hydraulic retarders are applied in heavy-duty trucks and buses as an auxiliary braking device. In traditional cooling systems of hydraulic retarders, the working fluid is introduced into the heat exchanger to transfer heat to the cooling liquid in circulation, whose heat is then dissipated by the engine cooling system. This prevents the waste heat of the working fluid from being used effectively. In hydraulic retarder cooling system based on the Organic Rankine Cycle, the organic working fluid first transfers heat with the hydraulic retarder working fluid in Rankine cycle, and then outputs power through expansion machine. It can both reduce heat load of the engine cooling system, and enhance thermal stability of the hydraulic retarder while recovering and utilizing braking energy. First of all, according to the target vehicle model, hydraulic retarder cooling system model based on Rankine cycle is established.
2016-09-18
Technical Paper
2016-01-1942
Sarah Chen, Steve Hoxie
Abstract Developing a brake system with high overall customer satisfaction rating is a constant challenge for OEMs as well as their brake suppliers. Brake system performance is directly linked to the engagement between the rotors and pads. The materials for the rotors and pads play a key role in the nature of the engagement. Therefore, to meet the performance targets, it is critical to have a good understanding of the brake rotor materials and their impacts. Gray iron is the most widely used brake rotor material in the industry owing to its superior thermal handling capacity, damping characteristics, and wear and cost advantages. G30 per ASTM A48 is generally specified for most brake rotors with minimum tensile strength of 200 MPa and Brinell hardness of 187∼241. G20 is also widely used for brake rotors, especially for brake smoothness and optimal lining life.
2016-09-18
Technical Paper
2016-01-1938
Xin Gao, Gangfeng Tan, Binyu Mei, Mengzuo Han, Tie Wang
Abstract The hydraulic retarder is an auxiliary braking device used for commercial vehicle in a long slope brake, and its transmission oil generates a lot of heat in its working process. If the heat of transmission doesn’t go through a reasonable management, it will seriously affect the braking performance of hydraulic retarder. To cool down the transmission oil, it will aggravates the load of the engine cooling system, and the long cooling path sometimes causes heat exchange not timely. When the Rankine cycle is used for cooling the hydraulic retarder transmission oil in virtue of its good heat transfer performance in phase change process, it can make the transmission oil temperature controlled more stable. In this new system, the setting parameters of the Evaporate-condensate system will affect the stability of the transmission oil temperature in the hydraulic retarder inlet and the energy recovery efficiency of the system.
2016-09-18
Technical Paper
2016-01-1953
Michael Herbert Putz, Harald Seifert, Maximilian Zach, Jure Peternel
Abstract Since more than eight years Vienna Engineering (VE) is working on an electro-mechanical brake (EMB) actuated by eccentrics and a highly non-linear actuation mechanism. The principle allows full braking in approx. 70 milliseconds (including air gap) and only approx. 3 A RMS actuator current at 12 V for classical ABS with oscillations. This EMB reached an elaborated state. Versions for passenger cars, elevators, railway and commercial vehicles (CVs) were derived. Now, as the EMB is going to road tests, it is necessary to fulfill safety requirements closely. What are these safety requirements and how can they be fulfilled? The properties of the overall system, of the mechanics and electronics of the single brake are discussed in this paper. The overall brake system for EMBs needs a truly redundant power supply, a safe control bus and a safe brake pedal. The mechanics of a single brake can be required to release when power is off and it must not get mechanically stuck.
2016-09-18
Technical Paper
2016-01-1954
Zhe Xiong, Xiaofei Pei, Xuexun Guo, Chengcai Zhang
Abstract In this paper a new pressure control method of a modified accumulator-type Electro-hydraulic Braking System (EHB) is proposed. The system is composed of a hydraulic motor pump, an accumulator, an integrated master cylinder, a pedal feel simulator, valves and pipelines. Two pressurizing modes are switched between by-motor and by-accumulator to adapt different pressure boost demands. A differentiator filtering raw sensor signal and calculating pedal speed is designed. By using the pedal feel simulator, the relationship between wheel pressures and brake force is decoupled. The relationships among pedal displacement, pedal force and wheel pressure are calibrated by experiments. A model-based PI controller with predictor is designed to lower the influences caused by delay. Moreover, a self-tuning regulator is introduced to deal with the parameter’s time-varying caused by temperature, brake pads wearing and delay variation.
2016-09-18
Technical Paper
2016-01-1955
Liangyao Yu, Xiaohui Liu, Xiaoxue Liu
Abstract The traditional vacuum booster is gradually replaced by Brake-by-Wire system (BBW) in modern passenger car, especially Electric Vehicle (EV). Some mechanical and hydraulic components are replaced by electronic components in Brake-by-Wire system. Using BBW system in modern passenger vehicles can not only improve the automotive safety performance, reliability and stability, but also promote vehicle maneuverability, comfort, fuel economy and environmental protection. Although vehicle's braking performance is greatly improved by using BBW, the system will inevitably consume some energy of the vehicle power supply, thus introducing unexpected drawback in comparison with the traditional vacuum assist braking system, since it doesn't need any electric power. Therefore, the analysis of energy consumption on typical main cylinder booster based BBW system under typical driving cycles will contribute to advanced design of current advanced braking system.
2016-09-18
Technical Paper
2016-01-1957
Seonho Lee, Heejae Kang, Ohchul Kwon, Chirl Soo Shin
Abstract A trend in automotive parts development is the pursuit of long life, high quality and reliability. The increase in service life of automotive wheel bearings, by improving the rolling contact fatigue (RCF) life of bearing steels, was investigated. Conventional studies of bearing steels and heat treatments have dealt with quenching and tempering (Q/T) in 52100 steel. This study is a new trial to increase the strength of bearing steels by special austempering in phases after general Q/T heat treatments.
2016-09-18
Technical Paper
2016-01-1936
Ashesh Anil Shah, Kshitiz Raj
Abstract Brake system for any vehicle plays an important role, as safety comes at highest level, also domestic and international safety norms for commercial vehicles are getting stringent. In current scenario of highly competitive commercial market, Payload advantage comes at peak level in customer demand list, also maintainability plays an important role to make sure least vehicle downtime, linked to customer profitability. Finally, if product has less complexity (reducing no. of parts), then it will provide add on benefit to any organization. Considering these customer oriented perspectives, mainly payload & maintenance, along with regulation compliance. We have proposed new Disc brake system for heavy duty commercial vehicle providing maximum payload benefit, along with enhancement in maintainability. It has also enhanced performance and meeting all legislative criteria at vehicle level.
2016-09-18
Technical Paper
2016-01-1921
Yusuke Sunagawa, Tsuyoshi Kondo
Abstract Brake squeal noise is generally classified into two vibration modes of disc. One is called “out-of plane mode” which vibrates in disc’s out-of-plane direction. The other is “In-plane mode” which vibrates in disc’s in-plane direction, it means the disc is contracted partially or is extended. There are few “In-plane noise” analysis reports from Disc pad standpoint, so it has been unclear how disc pad contributes to “In-plane mode” until now. This paper confirms that we successfully analyzed direct pad vibration mode by laser scanning under in-plane mode condition. Based on these results, we assume that pad stiffness affected in-plane mode and carried out validation tests.
2016-09-18
Technical Paper
2016-01-1913
Alessandro Sanguineti, Federico Tosi, Andrea Bonfanti, Flavio Rampinelli
Abstract Organic brake pads for automotive can be defined as brake linings with bonding matrix constituted of high-temperature thermosetting resins. Bonded together inside the polymeric binder are a mix of components (e.g. abrasives, lubricants, reinforcements, fillers, modifiers…), each playing a distinctive role in determining the tribology and friction activity of the final friction material. The herein reported work presents inorganic “alkali-activated”-based materials suitable for the production of alternative brake linings (i.e. brake pads), by means of an unconventional low-temperature wet process. Exploiting the hydraulic activity of specific components when exposed to an alkaline environment, such peculiar inorganic materials are capable of coming to a complete hardening without the need of traditional high-temperature energivorous procedures.
2016-09-18
Technical Paper
2016-01-1960
Yukihisa Takayama
Recently, vehicle production volumes have been increasing, particularly in newly developing countries that often lack adequate infrastructure. These regions utilize many unimproved roads and frequently experience heavy rainfall, requiring robust product features. In contrast, developed countries, with well-maintained infrastructure, have emphasized protection of the environment, requiring automobile manufacturers to target reductions in carbon dioxide emissions. Hub unit bearings, which enable smooth wheel rotation, are mounted at the wheel center. The hub bearing is a critical part which supports the automotive body and requires high reliability. To make environmental progress, hub unit bearings have increasing requirements for low friction. NSK has developed effective grease technologies to meet the diverse requirements of hub unit bearings, such as high reliability and low friction under severe environmental conditions.
2016-09-18
Technical Paper
2016-01-1926
Matthew Robere
Abstract Brake pad to rotor adhesion following exposure to corrosive environments, commonly referred to as “stiction”, continues to present braking engineers with challenges in predicting issues in early phases of development and in resolution once the condition has been identified. The goal of this study took on two parts - first to explore trends in field stiction data and how testing methods can be adapted to better replicate the vehicle issue at the component level, and second to explore the impacts of various brake pad physical properties variation on stiction propensity via a controlled design of experiments. Part one will involve comparison of various production hardware configurations on component level stiction tests with different levels of prior braking experience to evaluate conditioning effects on stiction breakaway force.
2016-09-18
Technical Paper
2016-01-1951
Björn Dingwerth
Abstract Caused by a number of beneficial properties inherently from the zinc-nickel material, this electrodeposited alloy is used more and more for cathodically protecting layers on ferrous components like cast iron brake calipers. Direct plating from acidic solutions is the state-of-the-art solution for zinc-nickel surface finishing of these components. To contribute to the continuous improvement of the final component and reduce the finishing cost, areas for improvement have been scrutinized in a current finishing system. Areas for improvement have been identified in the uniformity of the nickel distribution within different current densities and in the handling and economy of the metallic zinc anodes used for zinc metal replenishment. While today’s acidic zinc-nickel electrolytes suit and usually exceed the requirements for an alloy containing 10-15% nickel, nickel incorporation may drop just below 12% incorporation rate in areas which are plated at high current densities.
2016-09-18
Technical Paper
2016-01-1912
Bo Hu, Sydney Luk, Peter Filip
Abstract Copper and copper alloys are widely used in friction materials such as brake pad formulations as one of key ingredients by providing good thermal conductivity and high temperature friction stability to achieve desired friction performance, fade and wear resistance. However, the use of copper or copper containing material is being restricted in brake pads due to environment and health concerns. Extensive works have been made to explore the copper substitutes but most of these efforts became ineffective and failed with issues either thermal fade or excessive pad/rotor wear. In this paper, friction and wear responses were examined when a metallic composite material was used as the copper substitute in NAO and Low-met brake formulations where the copper and copper alloys were added 8% and 22% respectively.
2016-09-18
Technical Paper
2016-01-1916
Raffaele Gilardi, Davide Sarocchi, Loredana Bounous
Abstract A wide range of different carbon powders is available and currently used in friction materials like coke, graphite and carbon black. The effect of the type of carbon on braking performance has been extensively investigated in the past and it has been demonstrated that graphite can play an important role in copper-free brake pads. However, there are no studies about the influence of carbon powders on the processability of brake pads. Brake pads need to be painted in order to avoid corrosion. Typically electrostatic painting is used on an industrial scale, which requires the brake pads to be conductive. NAO brake pads (and especially Cu-free NAO brake pads) are rather insulating, and therefore difficult to paint. In this presentation we’ll show how special carbon powders can increase the electrical conductivity and therefore allow easy painting of brake pads. Based on these investigations, a new copper-free NAO formulation has been developed.
2016-09-18
Technical Paper
2016-01-1947
Albert Boretti, Sarim Al-Zubaidy
Abstract The operation of a conventional passenger car is characterised by increasing or maintaining the kinetic energy, when accelerating or cruising the vehicle, and reducing the kinetic energy by using the brakes. While the energy taken by the friction brakes to slow the vehicle is dissipated into heat, the introduction of Kinetic Energy Recovery Systems (KERS) has permitted the recovery of part of the braking energy. This reduces the amount of energy needed from the internal combustion engine (ICE). The contribution reviews the latest developments in electric KERS (E-KERS), with emphasis to round trip efficiency wheels to wheels and electrification of the powertrain. The contribution considers the opportunity to connect the E-KERS traction battery to other electric machines, such as an electrically assisted turbocharger (E-TC) connected to a motor/generator unit, or an electric water pump (EWP), to further optimise the vehicle operation.
2016-09-18
Technical Paper
2016-01-1950
Guirong Zhuo, Subin Zhang, Kun Xiong
Abstract As is known to all, the structure of the chassis has been greatly simplified as the application of in-wheel motor in electric vehicle (EV) and distributed control is allowed. The micro EV can alleviate traffic jams, reduce the demand for motor and battery capacity due to its small size and light weight and accordingly solve the problem that in-wheel motor is limited by inner space of the wheel hub. As a result, this type of micro EV is easier to be recognized by the market. In the micro EV above, two seats are side by side and the battery is placed in the middle of the chassis. Besides, in-wheel motors are mounted on the rear axle and only front axle retains traditional hydraulic braking system. Based on this driving/braking system, distribution of braking torque, system reliability and braking intensity is analyzed in this paper.
2016-09-18
Technical Paper
2016-01-1928
ByeongUk Jeong, Sang Do Kwak, Cheol Ki Kim
Abstract Recently, upon customer’s needs for noise-free brake, carmakers are increasingly widely installing damping kits in their braking systems. However, an installation of the damping kits may excessively increase softness in the brake system, by loosening stroke feeling of a brake pedal and increasing compressibility after durability. To find a solution to alleviate this problem, we first conducted experiments to measure compressibility of shims by varying parameters such as adhesive shims (e.g., bonding spec., steel and rubber thickness), piston’s shapes (e.g., different contact areas to the shims), and the numbers of durability. Next, we installed a brake feeling measurement system extended from a brake pedal to caliper. We then compared experimental parameters with brake feeling in a vehicle. Finally, we obtained an optimized level of brake feeling by utilizing the Design for Six Sigma (DFSS).
2016-09-18
Technical Paper
2016-01-1937
Taylor Erva, Adam Loukus, Luke Luskin
Abstract Aluminum metal matrix composite brake rotors with a selective ceramic function reinforcement gradient (FRG) have been developed for automotive applications. This paper will highlight the design, manufacturing, and testing of the rotors. Weight saving of an aluminum composite rotor in comparison to an industry standard cast iron rotor is 50-60%. With this material change comes design considerations to manage rotor temperature, rotor surface integrity, and friction. Manufacturing methods to meet these design constraints were needed to develop a viable high performance aluminum composite rotor. High pressure squeeze casting with soluble coring techniques were developed to incorporate the selective FRG MMC rotors. Dynamometer testing was performed, concentrating on brake friction and temperature to evaluate the macro and micro interfaces in the rotors.
2016-09-18
Journal Article
2016-01-1927
Christian Riese, Frank Gauterin
Abstract New technologies like alternative power trains and driver assistance systems have a big impact on brake system development. Most of the development work aims at the improvement of the actuation and modulation components of the brake system. The basic hydraulic network remained nearly the same over decades and still has to meet these new requirements. Previous papers have focused mainly on studying the behavior of single components, like for example the brake hose fluid consumption in detail. Other papers studied the complete system but simplified it extremely, so that some relevant effects are neglected. In this work, one focus is to study the influence of single relevant components, like the hydraulic unit and the hoses on the overall system performance. For this measurements with a complete hydraulic brake system, including a state of the art electromechanical brake booster and single component measurements for identification, are conducted.
2016-09-18
Journal Article
2016-01-1929
Nimrod Kapas, Ajith Jayasundera
Abstract There is an increasing interest in transient thermal simulations of automotive brake systems. This paper presents a high-fidelity CFD tool for modeling complete braking cycles including both the deceleration and acceleration phases. During braking, this model applies the frictional heat at the interface on the contacting rotor and pad surfaces. Based on the conductive heat fluxes within the surrounding parts, the solver divides the frictional heat into energy fluxes entering the solid volumes of the rotor and the pad. The convective heat transfer between the surfaces of solid parts and the cooling airflow is simulated through conjugate heat transfer, and the discrete ordinates model captures the radiative heat exchange between solid surfaces. It is found that modeling the rotor rotation using the sliding mesh approach provides more realistic results than those obtained with the Multiple Reference Frames method.
2016-09-18
Journal Article
2016-01-1930
Heewook Lee
Abstract Contamination protection of brake rotors has been a challenge for the auto industry for a long time. As contamination of a rotor causes corrosion, and that in turn causes many issues like pulsation and excessive wear of rotors and linings, a rotor splash protection shield became a common part for most vehicles. While the rotor splash shield provides contamination protection for the brake rotor, it makes brake cooling performance worse because it blocks air reaching the brake rotor. Therefore, balancing between contamination protection and enabling brake cooling has become a key critical factor when the splash shield is designed. Although the analysis capability of brake cooling performance has become quite reliable, due to lack of technology to predict contamination patterns, the design of the splash protection shield has relied on engineering judgment and/or vehicle tests. Optimization opportunities were restricted by cost and time associated with vehicle tests.
2016-09-18
Journal Article
2016-01-1931
Aaron Völpel, Georg Peter Ostermeyer
Abstract In today’s research and development of brake systems the model-based prediction of complex vibrations and NVH phenomena plays an important role. Despite the efforts, the high dimensional computational simulation models only provide a limited part of the results gained through experimental measurements. Several reasons are discussed by the industry and academic research. One potential source of these inadequacies is the very simple formulation of the friction forces in the simulation models. Due to a significant shorter computation time (by orders of magnitude), the complex eigenvalue analysis has been established, in comparison to the transient analysis, as the standard method in the case of industrial research, where systems with more than one million degrees of freedom are simulated.
2016-09-18
Journal Article
2016-01-1911
Philippe Dufrenoy, Vincent Magnier, Yassine WADDAD, Jean-Francois Brunel, Gery DE SAXCE
Abstract During friction it is well known that the real contact area is much lower to the theoretical one and that it evolves constantly during braking. It influences drastically the system’s performance. Conversely the system behavior modifies the loading conditions and consequently the contact surface area. This interaction between scales is well-known for the problematic of vibrations induced by friction but also for the thermomechanical behavior. Indeed, it is necessary to develop models combining a fine description of the contact interface and a model of the whole brake system. This is the aim of the present work. A multiscale strategy is propose to integrate the microscopic behavior of the interface in a macroscopic numerical model. Semi-analytical resolution is done on patches at the contact scale while FEM solution with contact parameters embedded the solution at the microscale is used. Asperities and plateaus are considered at the contact interface.
2016-09-18
Journal Article
2016-01-1919
Joo Sang Park, Min Gyu Han, Seon Yeol Oh
Abstract This paper introduces the experimental test results of an investigation to understand the relationship between the leading offset and squeal propensity. In addition Transient Analysis (TA) and Complex Eigenvalue Analysis (CEA) are used simultaneously as a means to compare the experimental approach to two different numerical tools, so evaluating the validity of each theoretical approach. To confirm the CAE results. An ODS was recorded of the brake using a 3D laser scanning vibrometer. Even though the CEA approach is very popular in the study of brake squeal noise, there are some limitations and difficulties in replicating the real phenomenon especially containing unstable behavior. The differences are due to weak pad contact stiffness and friction characteristics which are dependent on the relative interface velocity between pad and rotor. It is necessary to consider stick-slip vibration and time domain analysis in addition.
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