Display:

Results

Viewing 61 to 90 of 10713
2016-09-18
Journal Article
2016-01-1944
Seongjoo Lee, JeSung Jeon, ShinWook Kim, ShinWan Kim, Seong Rhee, Wan Gyu Lee, Young Sun Cho, Jeongkyu Kim
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.
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
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
Journal Article
2016-01-1939
Toshikazu Okamura
Abstract Brake judder is one of the most serious problems in automotive-brake systems. It is basically a forced vibration caused by the friction-surface geometry of a brake disc, and therefore, disc rotors play a significant role in judder. There are two types of judder: cold and hot. Hot judder is caused by the thermo-mechanical deformation of a brake disc due to high-speed braking. There are several shapes of deformation, e.g., coning and circumferential waviness. Circumferential waviness is caused by thermo-mechanical buckling and typically found as a butterfly shape in a 2nd rotational-order and hot-spotting. In a previous paper, two groups of disc castings with different material homogeneity were machined intentionally to have two kinds of dimensional variations.
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
2016-01-1953
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
2016-01-1947
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
Journal Article
2016-01-1948
Axel Freiwald, Gunn Hwang
Abstract 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 vehicle The availability of the vehicle for the passengers The security aspect includes the necessity to protect the vehicle and the manufacturers IP from unwanted attacks.
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
Journal Article
2016-01-1949
John David Fieldhouse, Joe Gelb
Abstract The design of a braking system involves a delicate balance between the friction pair, the disc and pad, where the pad is a complex blend of constituents to provide predictable characteristics, typically, a known and consistent friction level. In its base form the brake has to absorb the vehicle kinetic energy by converting it into heat. This heat absorption by the friction pair can result in chemical and physical interactions with the release of debris about which we know little. Other than environmental concerns, brake dust causes unnecessary problems with wear, thermal gradients (hot banding) and NVH. This paper is concerned with the removal and collection of brake debris from the friction interface - the debris being regarded as solids and airborne particles, the latter less than 10μm in size. The test procedure consisted of a Burnish program followed by 8 different drive cycles. The overall effects of debris removal is then reported for each test.
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
2016-01-1957
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
Journal Article
2016-01-1959
Laura Sguotti, Davide Olivieri, Domenico Bosco
Abstract Bearing friction is a direct contribution to vehicle CO2 emissions. The friction is defined as the total resistance to rotation, resulting from the combination of rolling and sliding friction in the contact areas. First, friction reduction was approached from a theoretical standpoint by employing modeling and simulation techniques. Improvements identified in simulation were then used to: create a new set of design rules for the internal geometry of the bearing, introduce a new grease, develop new seals, also with the integration of labyrinth functions and an optimization of the preload range variation. In order to provide a reliable confirmation of the expected achievements, a new friction measurement methodology was also introduced.
2016-09-18
Journal Article
2016-01-1958
Seungpyo Lee, Nahyon Lee, Jongkeun Lim, Jungyang Park
Abstract Through transmitting power and carrying vehicle weight, automotive wheel bearings play an important role. Counterbalancing the bearing responsibilities, they also are designed to last the life of a vehicle without servicing. When mounted to the vehicle steering knuckle by bolts, distortion occurs to the outer ring. Performance is affected when distortion takes place at the seal mounting location and raceways. Finite element analysis using commercial software was performed to analyze the outer ring distortion. Elasto-plastic and contact analyses were carried out to compute the clamping behavior of the outer ring, bolts and the knuckle under various conditions. To verify the reliability of this study, the distortion of the outer ring was measured. The experimental results proved to be comparative with the analysis results.
2016-09-16
Journal Article
2016-01-9018
Judhajit Roy, E. Harry Law
Abstract It is well known that the ride quality of trucks is much harsher than that of automobiles. Additionally, truck drivers typically drive trucks for much longer duration than automobile drivers. These two factors contribute to the fatigue that a truck driver typically experiences during long haul deliveries. Fatigue reduces driver alertness and increases reaction times, increasing the possibility of an accident. One may conclude that better ride quality contributes to safer operation. The secondary suspensions of a tractor have been an area of particular interest because of the considerable ride comfort improvements they provide. A gap exists in the current engineering domain of an easily configurable high fidelity low computational cost simulation tool to analyze the ride of a tractor semi-trailer. For a preliminary design study, a 15 d.o.f. model of the tractor semi-trailer was developed to simulate in the Matlab/Simulink environment.
2016-09-16
WIP Standard
J2806
Subject document is specifically intended for service brakes and service brakes when used for parking and/or emergency brakes (only) that are commonly used for automotive-type, ground wheeled vehicles exceeding 4536 kg (10 000 US lb) Gross Vehicle Weight Rating (GVWR). Subject specification provides the off-vehicle procedures, methods, and processes used to objectively determine suitability of tactical and combat ground wheeled vehicle brake systems and selected secondary-item brake components (a.k.a. aftermarket or spare parts), including brake “block” for commercial applications only, specifically identified within subject document. Subject specification is primarily based on known industry and military test standards utilizing brake inertia dynamometers. Targeted vehicles and components include, but may not be limited to the following: a.
2016-09-16
Standard
J1981_201609
The test is designed to evaluate the frontal impact resistance of wheel and tire assemblies used with passenger cars, light trucks and multi-purpose vehicles. The test is specifically related to vehicle pothole tests that are undertaken by most vehicle manufacturers. The scope has been expanded to allow the use of a striker that can be angled to preferentially impact the inboard and outboard wheel flange. For side impact of the outboard rim flange only, please refer to SAE J175. This SAE Recommended Practice provides a procedure to test a wheel or a tire and the test failure critiera. The specific test for a vehicle requires input from a pothole test on that vehicle to establish the drop height of the striker used in this test.
2016-09-14
WIP Standard
J257
The minimum performance values in this SAE Recommended Practice are applicable to vehicles with brake systems having typical service pressure ranges 0 to 16.6 MPa (0 to 2400 psi) hydraulic or 0 to 945 kPa (0 to 135 psi) air only. SAE J880 not only provides for determining maximum brake rating power capability, but also permits verification of any desired or arbitrary level such as the requirement established herein. The determining criteria for deciding brake rating power capability are: a. Cold brake stopping ability. b. Fade as a result of brake power absorption. c. Hot brake stopping ability following brake power absorption. d. Brake system stability following brake power absorption. e. Functional and structural integrity of brake system following test.
2016-09-14
Technical Paper
2016-01-1871
Renxie Zhang
Abstract Path following controller of a six-wheel skid-steering vehicle is designed. The vehicle speed is controlled through engine speed control and the lateral vehicle steering is controlled through hydraulic braking on each side. Contrary to the common approaches considering non-holonomic constraints, vehicle dynamic characteristics and nonlinear characteristics of tire are considered. A hierarchical control structure is applied in this vehicle control system. The kinematic controller works out the reference yaw rate and reference vehicle speed. And a robust dynamic controller tracks the reference signal. In addition, the dynamic controller takes actuator ability into account.
2016-09-14
Technical Paper
2016-01-1872
Bin Wu, Xichan Zhu, Lin li
Abstract Based on the emergency lane change cases extracted from the China naturalistic driving data, the driving steering behavior divides into three phases: collision avoidance, lateral movement and steering stabilization. Using the steering primitive fitting by Gaussian function, the distribution of the duration time, the relationship between steering wheel rate and deflection were analyzed in three phases. It is shown that the steering behavior essentially is composed of steering primitives during the emergency lane-change. However, the combination of the steering primitives is different according to the specific steering constraints in three phases. In the collision avoidance phase, a single steering primitive with high peak is used for the fast steering; in the lateral movement and stabilization phase, a combination of two or even more steering primitives is built to a more accurate steering.
2016-09-14
Technical Paper
2016-01-1886
Zhuoping Yu, Yi Zhang, Lu Xiong, Songyun Xu
Abstract With development of vehicle advanced driver assistant system and intelligent techniques, safer and more intelligent Integrated-Electro-Hydraulic Braking System is required to realize brake-by-wire. Thus, more and more companies and universities developed Integrated-Electro-Hydraulic Braking System to fulfill these requirements. In this paper, an Integrated-Electro-Hydraulic Braking System is introduced, which consists of active source power, pedal feel emulator and electro control unit. As a composite system of mechanic, electron and hydraulic pressure, the Integrated-Electro-Hydraulic Braking System has complex system characteristics. Integrated-Electro-Hydraulic Braking System and active power source have very different dynamic characteristics. So algorithms of hydraulic pressure control and motor control should be apart, but algorithm of them should be united in hardware to meet integration demand.
2016-09-14
Technical Paper
2016-01-1902
Xiaoyu Wang, Yun Zhao, Yufeng Lian, Yantao Tian
Abstract A new lateral stability control method, which is based on vehicle sideslip angle and tire cornering stiffness estimation, is proposed to improve the lateral stability of the four-in-wheel-motor-driven electric vehicle (FIWMD-EV) in this paper. Through the lateral tire force information, vehicle sideslip angle can be estimated by the extended kalman filter (EKF). Using the estimated vehicle sideslip angle, tire cornering stiffness can be also estimated by forgetting factor recursive least squares (FFRLS). Furthermore, combining with the vehicle dynamics model, an adaptive control target model is proposed with the information on vehicle sideslip angle and tire cornering stiffness. The new lateral stability control system uses the direct yaw moment control (DYC) based on dynamic sliding mode is proposed. The performance and effectiveness of the proposed vehicle state estimation and lateral stability control system are verified by CarSim and Simulink cosimulation.
2016-09-14
Technical Paper
2016-01-1905
Gaoming Fang, Hui Chen
Abstract Electric Power Steering (EPS) is the actuator of several lateral-dynamic-related Advanced Driver Assistance Systems (ADAS). A driving simulator with EPS will be much helpful for the ADAS development. However, if a real EPS is used in the driving simulator, it is quite difficult to realize the road reaction force accurately and responsively. To overcome this weakness, a virtual EPS platform is established. The virtual EPS platform contains two parts: one is the vehicle and EPS model, the other is the force feedback actuator (FFA) of the Steer-by-Wire (SBW) system. The FFA is an interface between the driver and the EPS/vehicle model. The reactive torque of the FFA is obtained based on the models. Meanwhile, the input of the EPS model is the steering angle of the FFA. Comparing to a real EPS, the virtual EPS platform has a problem of instability because of the actuator lag of the FFA. Therefore, a damping control method is applied to make the system stable.
2016-09-14
Standard
AS1145C
This specification covers minimum requirements for brake temperature monitoring equipment whenever used on any type and model of civil aircraft. It shall be the responsibility of the purchaser to determine the compatibility of these requirements with the application aircraft and to specify requirements in excess of these minimums as necessary.
2016-09-14
WIP Standard
J75
Motor vehicle brake fluid must conform to the requirements of SAE J1703 or J1704, not only when manufactured, but also after extended storage in any commercial packaging container. The purpose of this SAE Information Report is to generate an awareness of the major problems involved in the storage of brake fluids and, to some extent, provide means of circumventing them. It is also the purpose of this document to relate to experience and to test data accumulated and to list certain conclusions which should aid in the proper selection of containers for brake fluid.
2016-09-13
Standard
J1707_201609
This SAE Recommended Practice provides basic recommendations for dispensing and handling of SAE J1703 and SAE J1704 Brake Fluids by Service Maintenance Personnel to assure their safe and effective performance when installed in or added to motor vehicle hydraulic brake actuating systems. This document is concerned only with brake fluid and those system parts in contact with it. It describes general maintenance procedures that constitute good practice and that should be employed to help assure a properly functioning brake system. Recommendations that promote safety are emphasized. Specific step-by-step service instructions for brake maintenance on individual makes or models are neither intended nor implied. For these, one should consult the vehicle manufacturer’s service brake maintenance procedures for the particular vehicle. Vehicle manufacturer’s recommendations should always be followed.
2016-09-10
Article
The G-Vectoring Control name is a bit of a misnomer. It is not a torque-vectoring system aimed at dramatically improving race-circuit lap times. Rather, the purpose of the system is to endow the vehicle with refined and natural smoothness in normal day-to-day driving environments.
2016-09-09
WIP Standard
J2690
This SAE Recommended Practice establishes uniform test procedures for friction based parking brake components used in conjunction with hydraulic service braked vehicles with a gross vehicle weight rating greater than 4500 kg (10 000 lb). The components covered in this document are the primary actuation and the foundation park brake. Various peripheral devices such as application dashboard switches or indicators are not included. These test procedures include the following: a. Brake Related Tests 1. Brake Functional Performance 2. Brake Dynamic Torque Performance 3. Brake Corrosion Resistance 4. Brake Endurance with Torque 5. Brake Endurance without Torque 6. Vibration Resistance 7. Brake Ultimate Static Load 8. Brake Lining Wear Adjuster Function b. Actuation Related Tests 1. Mechanical Actuator Functional Performance 2. Mechanical Actuator Endurance 3. Mechanical Actuator Quick Release 4. Mechanical Actuator Ultimate Load 5. Spring Apply Actuator Functional Performance 6.
Viewing 61 to 90 of 10713

Filter