Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

A Comprehensive Review of Pedestrian Impact Reconstruction

1987-02-01
2014-01-2828
This paper presents a review on pedestrian impact reconstruction methodology and offers a comprehensive review of the literature. Several types of analyses are discussed which can be used to reconstruct the accident scenario using the facts collected from the scene. Inclusive in this review is the utilization of skid mark analysis, debris analysis, injury/damage match-up, trajectory analysis, nighttime visibility, and alcohol effects. The pedestrian impact reconstruction methodology is illustrated with a real world case example to point out different observations which can provide insight into the pedestrian/vehicle collision reconstruction approach. The literature review provides a broad foundation of information on pedestrian impact reconstruction and can be used to supplement the techniques presented in this paper in areas related to pedestrian impact. Research advances in the area of pedestrian impact reconstruction are also discussed in this paper.
Journal Article

Properties of Partial-Flow and Coarse Pore Deep Bed Filters Proposed to Reduce Particle Emission of Vehicle Engines

2009-04-20
2009-01-1087
Four of these Particulate Reduction Systems (PMS) were tested on a passenger car and one of them on a HDV. Expectation of the research team was that they would reach at least a PM-reduction of 30% under all realistic operating conditions. The standard German filter test procedure for PMS was performed but moreover, the response to various operating conditions was tested including worst case situations. Besides the legislated CO, NOx and PM exhaust-gas emissions, also the particle count and NO2 were measured. The best filtration efficiency with one PMS was indeed 63%. However, under critical but realistic conditions filtration of 3 of 4 PMS was measured substantially lower than the expected 30 %, depending on operating conditions and prior history, and could even completely fail. Scatter between repeated cycles was very large and results were not reproducible. Even worse, with all 4 PMS deposited soot, stored in these systems during light load operation was intermittently blown-off.
Journal Article

Gasoline Fuelled Partially Premixed Compression Ignition in a Light Duty Multi Cylinder Engine: A Study of Low Load and Low Speed Operation

2009-06-15
2009-01-1791
The objective of this study was to examine the operating characteristics of a light duty multi cylinder compression ignition engine with regular gasoline fuel at low engine speed and load. The effects of fuel stratification by means of multiple injections as well as the sensitivity of auto-ignition and burn rate to intake pressure and temperature are presented. The measurements used in this study included gaseous emissions, filter smoke opacity and in-cylinder indicated information. It was found that stable, low emission operation was possible with raised intake manifold pressure and temperature, and that fuel stratification can lead to an increase in stability and a reduced reliance on increased temperature and pressure. It was also found that the auto-ignition delay sensitivity of gasoline to intake temperature and pressure was low within the operating window considered in this study.
Journal Article

Online Implementation of an Optimal Supervisory Control for a Parallel Hybrid Powertrain

2009-06-15
2009-01-1868
The authors present the supervisory control of a parallel hybrid powertrain, focusing on several issues related to the real-time implementation of optimal control based techniques, such as the Equivalent Consumption Minimization Strategies (ECMS). Real-time implementation is introduced as an intermediate step of a complete chain of tools aimed at investigating the supervisory control problem. These tools comprise an offline optimizer based on Pontryagin Minimum Principle (PMP), a two-layer real-time control structure, and a modular engine-in-the-loop test bench. Control results are presented for a regulatory drive cycle with the aim of illustrating the benefits of optimal control in terms of fuel economy, the role of the optimization constraints dictated by drivability requirements, and the effectiveness of the feedback rule proposed for the adaptation of the equivalence factor (Lagrange multiplier).
Journal Article

Application of a Tunable-Diode-Laser Absorption Diagnostic for CO Measurements in an Automotive HCCI Engine

2010-10-25
2010-01-2254
An infrared laser absorption technique has been developed to measure in-cylinder concentrations of CO in an optical, automotive HCCI engine. The diagnostic employs a distributed-feedback, tunable diode laser selected to emit light at the R15 line of the first overtone of CO near 2.3 μm. The collimated laser beam makes multiple passes through the cylinder to increase its path length and its sampling volume. High-frequency modulation of the laser output (wavelength modulation spectroscopy) further enhances the signal-to-noise ratio and detection limits of CO. The diagnostic has been tested in the motored and fired engine, exhibiting better than 200-ppm sensitivity for 50-cycle ensemble-average values of CO concentration with 1-ms time resolution. Fired results demonstrate the ability of the diagnostic to quantify CO production during negative valve overlap (NVO) for a range of fueling conditions.
Journal Article

OILPAS - Online Imaging of Liquid-Particle-Suspensions - How to Prevent a Sudden Engine Breakdown

2010-05-05
2010-01-1528
Amount and size distribution of wear particles in engine lubricating oil are indicators of the current machine condition. A change in size distribution, especially a rise in the amount of larger particles, often indicates a starting wear of some machine parts. Monitoring wear particles contained in lubricating oil during normal machine operation can help to identify the need for maintenance and more important to prevent sudden failure of the machine. An optical method is used to image a thin layer of oil to count and classify contained particles. Therefore, a continuous flow of undiluted oil from the oil circuit of the machine is pumped through the measurement instrument. Inside the instrument, the oil flow is directed through a thin transparent flow cell. Images are taken using a bright LED flashlight source, a magnification lens, and a digital camera. Algorithms have been developed to process and analyze the images.
Journal Article

A Study of Drying-Up Friction and Noise of Automotive Accessory Belt

2013-04-08
2013-01-1701
Multiple-ribbed V belts have been widely used in automotive accessory drive systems to transmit power from crankshaft to power steering pump, alternator, and air conditioning (A/C) compressor. Overload under severe environmental conditions can lead to excessive slippage in the belt pulley interface in poorly designed accessory drive systems. This can lead to undesirable noise that increases warranty cost substantially. The mechanisms of this tribology phenomenon, noise features and system response are of utmost interest to the accessory drive system engineers. As accessory belt systems are usually used in ambient condition, the presence of water or moisture on belt is unavoidable under rainy or highly humid conditions. It has been found that the wet friction with negative coefficient of friction (cof)-velocity slope can lead to self-excited vibrations and squeal noise.
Journal Article

Blade Tip Clearance Sensors for Use in Engine Health Monitoring Applications

2013-09-17
2013-01-2145
Blade tip clearance is a key design parameter for gas turbine designers. This parameter is often measured during engine testing and development phases as part of design validation but has yet to be utilized during normal engine fleet operation. Although blade tip clearance measurements are often mentioned for fleet operation in the context of active clearance control, the use of blade tip clearance measurements can provide an additional benefit for engine health monitoring. This paper explores the use of blade tip clearance sensors for engine condition monitoring of hot section blades. Blade tip clearance, especially in the first stage turbine, has an impact on exhaust gas temperature. The use of tip clearance measurements can provide supplementary information to traditional EGT measurements by providing a direct measurement of wear on the blade tips.
Technical Paper

In-Depth Considerations for Electric Vehicle Braking Systems Operation with Steep Elevation Changes and Trailering

2021-10-11
2021-01-1263
As the automotive industry prepares to roll out an unprecedented range of fully electric propulsion vehicle models over the next few years - it really brings to a head for folks responsible for brakes what used to be the subject of hypothetical musings and are now pivotal questions for system design. How do we really go about designing brakes for electric vehicles, in particular, for the well-known limit condition of descending a steep grade? What is really an “optimal’ design for brakes considering the imperatives for the entire vehicle? What are the real “limit conditions” for usage that drive the fundamental design? Are there really electric charging stations planned for or even already existing in high elevations that can affect regenerative brake capacity on the way down? What should be communicated to drivers (if anything) about driving habits for electric vehicles in routes with significant elevation change?
Technical Paper

Empowering the Brake Systems

2021-10-11
2021-01-1261
Some research shows that the transport system is one of the main responsible for the emission of pollutants in the atmosphere. The growing demand for automobiles contrasts directly with the scarcity of inputs, planet temperature increasing and air quality degradation in large cities. This counterpoint is explored and discussed a lot, demanding that studies would be conducted to find out sustainable solutions in the production to end-customers. Instead of use fossil resources, one of the options to reduce gas emissions is the use of vehicles powered by electricity. When converting part of the vehicle's kinetic energy into electrical one its reduces emissions in the production electricity - power plants - as well burning gases in transport. Technological advances allow us to use Electronic Stability Control to generate environmental and safety results in mobility for next years.
Technical Paper

Research on Locked Wheel Protection Function of Aircraft Brake System

2021-10-11
2021-01-1269
Locked wheel protection is an important part of antiskid control for aircraft brake control system. Locked wheel protection compares the wheel speed of two or more wheels, if one of the wheels is too slow, locked wheel protection releases the brake pressure on the slow wheel. This work aims to study the control logic for locked wheel protection. Locked wheel protection control logic consists of 3 key factors: paired wheels, active threshold and inhibit velocity. Focus on comparison different options of these 3 factors, all aspects of control logic for locked wheel protection had been expounded in this study. Simulation and calculation analysis is applied for different locked wheel strategies to evaluate the effect. One conclusion is that the greatest wheel speed of the wheel under control shall be set as a reference speed for locked wheel protection. This study provide the basis to design a proper locked wheel protection function of aircraft brake control system.
Technical Paper

Systems of Automatic Brake Torque Reduction on the Wheels of One Axle of the Car

2021-10-11
2021-01-1266
Braking mechanisms have the most variation in performance of all of the elements of the braking system. Instability of braking torques on the wheels of one axle of the vehicle leads to the appearance of the braking forces unevenness, and then- to the vehicle skidding during braking. At one time, the appearance of open-type disc brakes made it possible to reduce the unevenness of the braking forces on the sides of the car due to their higher characteristics of energy intensity and stability. However, the lack of feedback between the left and right disc brakes mounted on the same axle of the vehicle does not allow reducing the unevenness of the braking forces to an acceptable minimum. The authors of the work studied and proposed several systems for automatic reduction of the braking torques unevenness for braking mechanisms mounted on the wheels of one axle.
Technical Paper

Research on Braking Energy Recovery Strategy of Pure Electric Vehicle

2021-10-11
2021-01-1264
With the increasingly serious global environmental and energy problems, as well as the increasing number of vehicles, pure electric vehicles with its advantages of environmental protection, low noise and renewable energy, become an effective way to alleviate environmental pollution and energy crisis. Due to the current pure electric vehicle power battery technology is not perfect, the range of pure electric vehicle has a great limit. Through the braking energy recovery, the energy can be reused, the energy utilization rate can be improved, and the battery life of pure electric vehicles can be improved. In this paper, a pure electric vehicle is taken as the analysis object, and the whole vehicle analysis model is built. Through the comparative analysis, based on the driver's braking intention and vehicle running state, the braking energy recovery control strategy of double fuzzy control is proposed.
Technical Paper

An Investigation of Property Changes of Copper-Free Brake Pads During Wear Testing: Pressure and Temperature Dependence of Pad Modulus, and the Correlation Between Modulus and Friction Coefficient

2021-10-11
2021-01-1276
Earlier publications have demonstrated that pad and disc properties change during storage and also during the SAE J2522 Brake Effectiveness Test Procedure. The current investigation was undertaken to find out how the properties change under milder braking conditions, using the SAE J2707 Wear Test Procedure. A copper-free formulation was selected for the investigation and tested on an inertia dynamometer using a front caliper designed for a passenger car. The pad dynamic modulus changed up or down throughout the test, depending on the test conditions. The pad dynamic modulus, the pad natural frequencies and the disc natural frequencies all decreased by the end of the test. Under high-speed, high-deceleration and high-temperature braking conditions, the pad surface region permanently expands, which results in reduced dynamic modulus and also leads to reduced pad thickness loss as compared with pad weight loss.
Technical Paper

Research on High-efficiency Test Method of Vehicle AEB based on High-precision Detection of Radar Turntable Encoder

2021-10-11
2021-01-1273
With the increasingly complex traffic environment, the vehicle AEB system needs to go through a large number of testing processes, in order to drive more safely on the road. For speeding up the development process of AEB and solve the problems of long cycle, high cost and low efficiency in AEB testing, in this paper, a millimeter wave radar turntable is built, and a high-precision detection algorithm of turntable encoder is designed, at the same time, a test method of vehicle AEB based on the detection data of radar turntable encoder is designed. The verification results show that methods described in this paper can be used to develop the vehicle AEB test algorithm efficiently.
Technical Paper

Transfer Film Composition and Characteristics in Copper-Free NAO Brake Pads

2021-10-11
2021-01-1278
Copper-free non-asbestos-organic (NAO) brake pads have been developed to satisfy the copper content regulations in North America. Copper-free NAO brake pads are required to have a stable friction coefficient owing to the electrification of the control systems, as well as to exhibit improved wear resistance to reduce brake dust emissions. Our previous study indicated that the transfer film formed on the rotor surface affects both the friction coefficient stability and amount of wear. In this study, we investigated how different types of inorganic fillers affect the transfer film formation and its composition in a wear test controlled by temperature. It was confirmed that the main component of the transfer film was iron oxide derived from the rotor. Furthermore, the contained components changed according to the appearance of the rotor surface after each wear test.
Technical Paper

System Approach to Forecasting Standards of Vehicles’ Braking Efficiency

2021-09-02
2021-01-5083
The article is devoted to the development of a method for predicting changes in regulatory requirements for the braking efficiency of vehicles. On the basis of the analysis of the requirements for the vehicle’s braking efficiency, at different times imposed on the average steady deceleration, the dependence of the standard meaning of this value on time has been established. The values of the coefficients, which depend on the vehicle category, have been determined when carrying out various types of tests. It was found that the meaning of the minimum permissible average steady deceleration, depending on time, changes according to an exponential dependence, the parameters of which are determined by the vehicle category and the type of tests. On the example of a vehicle of category M1, the calculation was performed, and the results of the forecast of changes in the regulatory requirements for the braking efficiency of the vehicle were presented.
Technical Paper

Parameter Matching of Planetary Gearset Characteristic Parameter of Power-Spilt Hybrid Vehicle

2021-09-16
2021-01-5088
To quickly and efficiently match the planetary gearset characteristic parameter of power-spilt hybrid vehicles so that their oil-saving potential can be maximized, this study proposes a parameter matching method that comprehensively considers energy management strategy and driving cycle based on an analysis of vehicle instantaneous efficiency. The method is used to match the planetary characteristic parameter of a power-split hybrid light truck. The relevant conclusions are compared with the influence of various planetary characteristic parameters on fuel consumption obtained through simulation under typical operating conditions. The simulation results show that the influence laws of the various planetary characteristic parameters on vehicle average efficiency are similar to those on fuel consumption. The proposed parameter-matching method based on vehicle efficiency analysis can effectively match the planetary characteristic parameter for power-split hybrid powertrains.
Technical Paper

Styling Parameter Optimization of the Type C Recreational Vehicle Air Drag

2021-09-30
2021-01-5094
Recreational vehicles have a lot of potential consumers in China, especially the type C recreational vehicle is popular among consumers due to its advantages, prompting an increase in the production and sales volumes. The type C vehicle usually has a higher air drag than the common commercial vehicles due to its unique appearance. It can be reduced by optimizing the structural parameters, thus the energy consumed by the vehicle can be decreased. The external flow field of a recreational vehicle is analyzed by establishing its computational fluid dynamic (CFD) model. The characteristic of the RV’s external flow field is identified based on the simulation result. The approximation models of the vehicle roof parameters and air drag and vehicle volume are established by the response surface method (RSM). The vehicle roof parameters are optimized by multi-objective particle swarm optimization (MO-PSO).
Technical Paper

Infrared Signature of Combat Aircraft Incorporating Weight Penalty due to the Divergent Section of the Convergent-Divergent Nozzle

2021-09-01
2021-01-6002
Performance penalties associated with infrared (IR)-signature suppression (IRSS), e.g., increased engine back pressure, weight, drag, cost, and complexity, can shift the engine operating point to higher combustion temperatures. Extra weight degrades aircraft flight performance in terms of reduced range, higher length needed for takeoff, reduced maneuverability, etc. Lift-induced drag penalty due to increased weight shifts the aircraft gas turbine engine operating point to a higher combustion temperature. But the divergent section of the convergent-divergent (C-D) nozzle gives the extra thrust up to optimal flow expansion, which more than compensates the increased lift-induced drag corresponding to its weight. Thus, for the same thrust, an engine with a C-D nozzle operates at a lower combustion temperature than with a convergent nozzle.
X