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SAE 2016 Brake Colloquium & Exhibition - 34th Annual
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Research on Matching for the Rankine Cycle Evaporate-condensate System of Hydraulic Retarder

Wuhan University of Technology-Xin Gao, Gangfeng Tan, Binyu Mei, Mengzuo Han, Tie Wang
Published 2016-09-18 by SAE International in United States
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.First of all, the outlet temperature of hydraulic retarder is set according to the stable condition in this paper. Next, it is the heat transfer calculation of evaporator and condenser under…
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Fine-Tuning of Rotor Gray Iron Material for Optimal Brake Performance

BWI Group-Sarah Chen, Steve Hoxie
Published 2016-09-18 by SAE International in United States
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.This study has found that variations in gray iron material can considerably affect brake fiction coupling behaviors and hence the overall brake performance. Rotors that meet both physical property and chemical composition requirements in general can…
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Disc Brake Pad Corrosion Adhesion: Test-to-Field Issue Correlation, and Exploration of Friction Physical Properties Influence to Adhesion Break-Away Force

General Motors Corporation-Matthew Robere
Published 2016-09-18 by SAE International in United States
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. Part two will involve modifying a production friction material formulation with known stiction in the field to force differences in porosity, density, and pH, and thus attempt to correlate stiction propensity with these physical properties. A prior study [1] has explored this potential with non-commercial friction materials of very…
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A Study of Low-Frequency and High-Frequency Disc Brake Squeal

SAE International Journal of Passenger Cars - Mechanical Systems

HMC-Jeongkyu Kim
Hyundai Mobis-Wan Gyu Lee, Young Sun Cho
  • Journal Article
  • 2016-01-1944
Published 2016-09-18 by SAE International in United States
When two identical brakes are simultaneously tested on a vehicle chassis dynamometer, very often the left hand brake is found to squeal more or less than the right hand brake, all at different frequencies. This study was performed to develop some understanding of this puzzling phenomenon. It is found that as the wear rate difference between the inner pad and the outer pad increases, low frequency (caliper and knuckle) squeals occur more and more, and as the differential wear becomes larger and larger, high frequency (disc) squeals occur less and less, finally disappearing all together. Discs and calipers are found to affect the differential pad wear, in turn affecting brake squeal generation.
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Optimization for Brake Feeling in Vehicle without Brake Noise

Hyundai Motor Company-ByeongUk Jeong, Sang Do Kwak, Cheol Ki Kim
Published 2016-09-18 by SAE International in United States
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). Our results may provide practitioners with a better guideline by helping them design a brake feeling system without brake noise such as squeal.
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Design and Research of Micro EV Driven by In-Wheel Motors on Rear Axle

Tongji University-Guirong Zhuo, Subin Zhang, Kun Xiong
Published 2016-09-18 by SAE International in United States
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. In order to coordinate with traditional hydraulic ABS control to ensure the braking stability of the vehicle, model following control (MFC) is adopted to fully utilize the fast and accurate torque response…
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Safe and Secure Software Updates Over The Air for Electronic Brake Control Systems

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Infineon Technologies AG Germany-Axel Freiwald
Infineon Technologies Korea Co., Ltd.-Gunn Hwang
  • Journal Article
  • 2016-01-1948
Published 2016-09-18 by SAE International in United States
Vehicle manufacturers are suffering from increasing expenses for fixing software issues. This fact is mainly driving their desire to use mobile communication channels for doing Software Updates Over The Air (SOTA).Software updates today are typically done at vehicle service stations by connecting the vehicles’ electronic network via the On Board Diagnostic (OBD) interface to a service computer. These operations are done under the control of trained technicians.SOTA means that the update process must get handled by the driver.Two critical aspects need to get considered when doing SOTA at Electronic Brake Control (EBC) systems. Both will determine the acceptance of SOTA by legal authorities and by the passengers:The safety and security of the vehicleThe availability of the vehicle for the passengersThe security aspect includes the necessity to protect the vehicle and the manufacturers IP from unwanted attacks.Existing safety measures ensure safe operation of a vehicle at all times. In general and especially for EBC systems the existing safety measures need extensions for updating software in remote locations. It must be absolutely ensured, that the vehicle will…
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Model-Based Pressure Control for an Electro Hydraulic Brake System on RCP Test Environment

Wuhan University of Technology-Zhe Xiong, Xiaofei Pei, Xuexun Guo, Chengcai Zhang
Published 2016-09-18 by SAE International in United States
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. To verify the controller validity, a Rapid Control Prototype (RCP) test environment based on dSPACE is built. Self-designed HCU and pedal feel simulator are installed in test bench. The close loop test results of pressure tracking are plotted and analyzed by contrasting…
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Wheel Bearing Lubrication Development for Low Friction and Water Resistance

NSK, Ltd.-Yukihisa Takayama
Published 2016-09-18 by SAE International in United States
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. Under wet operating conditions, the developed grease extended bearing life by using a unique composition of synthetic base oil with additives for water resistance which can separate water drops and form a thicker oxide film on the bearing raceways. At low speeds and heavy load conditions, the developed grease decreased friction torque…
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Bio-Soluble Chemical Composition for Complementary Mineral Fibres: An Enhanced Tribologic Effect and Its Influence on Disc Wear

SAE International Journal of Materials and Manufacturing

Lapinus Fibres-Diego Adolfo Santamaria Razo, Fernao Persoon
  • Journal Article
  • 2016-01-1909
Published 2016-09-18 by SAE International in United States
Environmental and financial factors are leading developments in the automotive industry and friction materials are no exception. Different organizations around the globe are increasing their attention on fine dust emissions. End users are more and more focused on comfort and cost due to global economic conditions.Two of these factors are directly related to each other: comfort and fine dust. They are the result of tribologic mechanisms resulting from pad and disc wear. These mechanisms linked to friction performance are the consequence of the interaction between friction material surface and disc surface. This interaction forms the third body layer and extensive studies have been carried out on this.This paper describes a detailed characterization of a new group of developed fibres. This new family of fibres has been specially engineered to offer an enhanced friction material surface reinforcement due to the specially designed aspect ratio. It has also been designed to maintain the most stable third body layer development to keep boosting friction level. Disc wear can be reduced thanks to its special chemical composition. The paper…
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