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Technical Paper

A Systems Modeling Methodology for Evaluation of Vehicle Aggressivity in the Automotive Accident Environment

2001-03-05
2001-01-1172
A systems modeling approach is presented for assessment of harm in the automotive accident environment. The methodology is presented in general form and then applied to evaluate vehicle aggressivity in frontal crashes. The methodology consists of parametric simulation of several controlled accident variables, with case results weighted by the relative frequency of each specific event. A hierarchy of models is proposed, consisting of a statistical model to define the accident environment and assign weighting factors for each crash situation case, and vehicle and occupant models for kinematic simulation of crash events. Head and chest injury results obtained from simulation are converted to harm vectors, in terms of probabilistic Abbreviated Injury Scale (AIS) distributions based on previously defined risk analyses. These harm vectors are weighted by each case’s probability as defined by the statistical model, and summed to obtain a total estimate of harm for the accident environment.
Technical Paper

A Compact Cooling System (CCS™): The Key to Meet Future Demands in Heavy Truck Cooling

2001-05-14
2001-01-1709
To meet future needs for heavy truck cooling, a novel high performance radial compact cooling system (CCS) was developed. Measurements with a prototype system were conducted in a component wind tunnel and with truck-installed systems in a climatic vehicular wind tunnel. The CSS is compared to conventional axial and side-by-side systems. In comparison with a conventional axial system, the performance per unit volume of the CCS is 42% higher, the noise level is about 6 dB lower and the power consumption of the radial fan is 70% of the axial fan leading to significant savings in fuel consumption.
Technical Paper

Parking Cooling Systems for Truck Cabins

2001-05-14
2001-01-1728
Engine independent AC-systems, or parking cooling systems for non-idling air conditioning are getting more and more important, because extremely uncomfortable conditions during breaks or a disproportionate amount of fuel consumption for engine idling during breaks are not longer accepted. For cost, weight and package reasons today only thermal storage systems are ready for series production of in series production. The benefits (comfort and fuel savings) and test results of such a system are shown. Future developments of fuel cells or new alternator/battery-systems will probably change this evaluation.
Technical Paper

Model Development, Simulation and Validation, of Power Train Cooling System for a Truck Application

2001-05-14
2001-01-1731
Power train cooling control is becoming a topic of increasing interest as evidenced by the recent surge of activities that suppliers of automotive power train cooling and HVAC systems are reporting in literature. The goals of these activities are to achieve better fuel economy, lower emissions and increased passenger comfort by controlling coolant flow through the different system components. In order to study any of the ideas in this area, a simulation model must be developed to sift through them for the most practical and effective method to avoid the high cost of hardware builds and long testing hours. This work uses the EASY5 simulation package (a product of the Boeing Company) to model such systems. A model is developed for a pick up truck application and is validated against test results. At this stage, the model has only the basic components namely the radiator, the water pump, a surge (return) tank, hoses and pipes, and the engine thermal load.
Technical Paper

Factors Affecting Truck Driver's Perceived Comfort

2001-04-30
2001-01-1571
Truck driver's perception of ride quality/comfort is influenced by many factors relating to the driver, the vehicle and road surface roughness. A subjective rating survey was undertaken to identify the range of roughness wavelengths in the longitudinal road surface profile that affect the perceived ride of heavy articulated vehicles. They were found to range between 4.8 and 19.5 meters. Accordingly, a new roughness index called Profile Index (PI) was established. During the survey, data was collected on factors such as driver's age, years of driving experience, weight, vehicle's age, loading condition, cab location, type of driving axle suspension, weather condition and time of the rating. The effects of these factors were studied at different PI levels to test the viability of the PI as a measure of the perceived heavy vehicle ride and to establish if any of the above factors influenced the drivers' judgments during the survey.
Technical Paper

The Effect of Temperature on Pass-By Noise

2001-04-30
2001-01-1568
Repetitive J-366 pass-by tests were run on a number of trucks to determine the effect of atmospheric conditions on the measured pass-by noise level. Of the atmospheric conditions observed (temperature, wind, humidity, air density & sunshine), only ambient temperature had a significant effect on measured pass-by noise. Measured pass-by noise level increased approximately 1 dB(A) for each 13 °C drop in temperature. Data indicates that applying a generic correction factor based on engine type is more accurate than ignoring the effect of temperature.
Technical Paper

Gear Whine Improvements for an Automatic Transmission through Design Retargeting and Manufacturing Variability Reduction

2001-04-30
2001-01-1505
Gear whine in 1st gear for an automatic transmission that has been in production for nearly thirty years was identified as an NVH issue. Due to advances in vehicle level refinement, and reduction of other masking noises, the automatic transmission gear whine became an issue with the customer. Since the transmission was already in production, the improvements had to be within the boundaries of manufacturing feasibility with existing equipment to avoid costly and time consuming investment in new machines. The approach used was one of identifying optimum values of existing gear parameters to provide a reduction in passenger compartment noise. The problem was in a light truck application. Objective noise measurements were recorded for 10 transmissions from more than 50 driven in vehicles. The transmissions were disassembled and the gears inspected.
Technical Paper

Pass-By Noise Prediction for Trucks Based on Powertrain Test-Cell Measurements

2001-04-30
2001-01-1564
The paper outlines and discusses the possibilities of a new instrumentation tool for the analysis of engine and gearbox noise radiation and the prediction of pass-by noise from powertrain test cell measurements. Based on a 32 channel data acquisition board, the system is intended to be quick and easy to apply in order to support engineers during their daily work in the test cell. The pass-by prediction is a purely experimental approach with test cell recordings being weighted by measured transfer functions (from the powertrain compartment to the pass-by point).
Technical Paper

Dynamic Interactions Between Loaded and Unloaded Gear Pairs Under Rattle Conditions

2001-04-30
2001-01-1553
In many manual transmissions, conditions for the onset of vibro-impacts from an unloaded gear pair are more likely than from an engaged set. Although some of the general characteristics of neutral gear rattle are known, no specific analytical models are available in the literature that can explain interactions between unloaded and loaded gear pairs in the drive rattle mode. For the sake of illustration, a particular problem for a light duty truck is studied in this paper and dynamic interactions are investigated. Some experimental measurements are first presented to define the unloaded gear rattle problem. Linear and non-linear mathematical models of the driveline are developed to understand, quantify and control the rattle problem. Trends predicted by simulations are compared with those observed in experiments. The effects of various gear run-ups and vibratory drag torques are investigated.
Technical Paper

Feasibility of Using Acoustic Room Models and Measured Sound Power to Estimate Vehicle Interior Noise

2001-04-30
2001-01-1533
In this paper, interior noise of a heavy commercial truck was modeled with the room equation. This approach assumed that large truck cabins may be adequately modeled as a practical room as is done in architectural acoustics, where ray theory and statistical concepts are suitable, and where application of complicated wave theory may not be necessary. This simplifies computational requirements, making a semi-empirical scheme useful for timely product development. This study employed sound power measurements at thirty-four surface patches encompassing the interior cabin boundary. Each surface-patch constituted an individual interior noise source. Predicted and measured results correlated well, demonstrating the capability to estimate driver-position noise level from predicted periphery sound intensity changes.
Technical Paper

Development of EGR Coolers for Truck and Passenger Car Application

2001-05-14
2001-01-1748
The new European legislation (EURO III) for emission reduction was mainly reached by combustion optimization. This lead to a higher fuel consumption, which can be compensated by cooled EGR. One of the described coolers is the first known EGR cooler for series truck application in Europe and is in production since mid of year 2000. Also for the next legislation step (EURO IV) cooled EGR is one of the most promising solutions. The design criteria and production issues of a tube and shell type EGR cooler for truck application and a tube plate design for a high volume production cooler for passenger car will be described.
Technical Paper

Total networked truck driver information and multiplexing vehicle area networks

2000-06-12
2000-05-0372
The truck market is more and more demand driven and complexity has grown substantially. Especially in combination with sophisticated bodies and trailers flexible electronic solutions are required to cope with this complexity. A new approach to meet these demands is to use standardized PLC functionality for vehicle multiplexing and visualization electronics. The VDO KIBES Mk II system is such a solution especially designed for the commercial vehicle market. With software-controlled modules replacing hardwired control centers the vehicles can be easily differentiated at the latest possible time. For the traffic information terminals the first devices are modern radios. Besides classical traffic news the RDS/TMC system delivers continuous digital information for the chosen area. Alternatively telematic service providers can transmit trip-individual traffic and weather information, e.g., through GSM mobile phones.
Technical Paper

Computational design of commercial vehicle for reconciling aerodynamics and engine cooling performance

2000-06-12
2000-05-0344
As the global environmental protection becomes the world consensus recently, the regulations of the fuel consumption and the exhaust gas have large effects on the performance and the fundamental structure of commercial vehicles. Especially the technology concerning "fluid" and "heat" has a close relationship with those issues. Owing to above circumstances, commercial vehicles such as large trucks and buses are forced to be designed near the limit of allowance. Furthermore, a rapid design is another requirement. However, though significant number of variations, i.e., cab configuration, wheel base, rear body configuration, engine specification, etc., are prepared, it is impossible to improve the performance of all those combinations by experiments which cost a lot. Accordingly, the quantitative prediction using computer will become indispensable at the beginning term of new car development.
Technical Paper

Truck recycling: Environmental-friendly guidelines

2000-06-12
2000-05-0357
Transport is a fundamental aspect of community prosperity and it is closely connected to its development. Transport plays an essential role among the production cycles of a nation, and the commercial vehicle (trucks or buses) makes it possible to become true. From the days when commercial vehicles first appeared, to the early ''80s, main research themes were those intended to increase "productivity" and "profitability." In the ''80s a new and common ecological awareness had induced the industrial sector, and specially motor vehicle manufacturers to try reducing atmosphere and water pollution effects as much as possible. Starting with the ''80s, new needs have appeared in addition to the "usual" ones, entailing entirely new research trends for commercial vehicles.
Technical Paper

Active Vibration Control of Driveline Systems

2000-06-12
2000-05-0318
Concern about axle noise/vibration/harshness (NVH) has been increasing with the growing popularity of sport utility vehicles, pick-up trucks, hybrid-vehicles and vans. Consumers want these vehicles to be quieter, with performance more like passenger cars. Traditional controls such as absorber-dampers and isolated/reduced vibration sources can solve some of the noise and vibration problems. An additional approach to enhancing NVH performance, is an active vibration control technique, which deals with the energy at the source. This paper describes an approach which combines an active vibration control technique with signature analysis, operational modal analysis and transfer path analysis to improve NVH performance. A flow chart of this is shown in Figure 1. Using this approach, we can identify and verify noise and/or vibration issues, find the root causes, and determine main contribution paths throughout driveline systems.
Technical Paper

Ways to meet future emission standards for heavy Sports Utility Vehicles - SUV

2000-06-12
2000-05-0288
Diesel engines belong to the most efficient power sources for any kind of on-road vehicle, but especially in Europe increasingly for passenger cars. However, more stringent exhaust emission regulations, which will come into force world-wide in industrialised countries during the first decade of the next century will require NOx and particulate emissions to be reduced by up to 60% and more from today's levels. To meet these future emission standards particularly for heavier passenger vehicles, such as SUVs, Pickup Trucks and Light Commercial Vehicles, as well as for heavy luxury class passenger cars, the application of new technologies including advanced exhaust gas aftertreatment systems will be indispensable, especially in view of maintaining the thermal efficiency of diesel engines relative to gasoline engines.
Technical Paper

The Driver Side Air Bag Development for Light Truck

2000-06-12
2000-05-0273
This study presents a driver side airbag development procedure of a cab-over type light truck which weighs from 2000kg to 3500kg. For the airbag development, crash tests are performed according to FMVSS 208 regulation used for passenger car. Test results are used to develop an airbag ECU and get a vehicle pulse for computer simulation and sled test. This study proposes a modified airbag deployment criterion, T150mm−25ms, for cab-over type truck. A finite element computer model for occupant behavior analysis is developed and utilized to find optimal airbag parameter values. Then, sled test is performed to verify the computed airbag parameter values and tune them if necessary. Finally, crash test equipped with airbag is performed again to check the improvement of injury coefficients. This study suggests three things to overcome the difficulties in femur protection capability.
Technical Paper

Drag Reduction of Bluff-Based Body by Wake Control Vanes (Effective Utilization of Under Floor Flow)

2000-06-12
2000-05-0257
Heavy aerodynamic drag of ~70% among all drags is imposed on large bluff-based vehicles like buses and container trucks traveling at high speed. To reduce the drag, wake control experiments are performed with attention to effective utilization of under floor flow by using air guide vanes equipped at the based rear end corners. The aerodynamic drag is measured for a 1/16 bus model settled on the moving ground of a wind tunnel. The flow patterns controlled by the vanes are visualized by oil film and smoke tracer techniques. As a result, drag reduction of ~16% is successfully attained by optimizing the vane profile and position, in which the under floor flow is effectively induced by the under vane into the wake resulting in remarkable recovery of the negative pressure acting on the based end surface.
Technical Paper

Modeling and Validation of Traveling Resistance for Heavy Trucks

2001-03-05
2001-01-0555
Low fuel consumption is very important for a heavy truck. Doing measurements of fuel consumption in a real vehicle is though complicated and very time-consuming. The main problem is that measurements are not repeatable. By use of computer simulations an ideal but repeatable result of fuel consumption and emissions can be created and differences between vehicles can be studied. A computer program to simulate fuel consumption and emissions for heavy trucks in long haulage has been created, using the object-oriented software DYMOLA. It has a longitudinal vehicle model and an engine model based on steady-state measurements. In this paper the validation of external forces, like air resistance and rolling resistance, is presented. This has been achieved by equipping a heavy truck with strain gauges to measure the torque on the propeller shaft. Several tests have been run at various constant speeds on flat road.
Technical Paper

Forward Collision Warning: Preliminary Requirements for Crash Alert Timing

2001-03-05
2001-01-0462
Forward collision warning (FCW) systems are intended to provide drivers with crash alerts to help them avoid or mitigate rear-end crashes. To facilitate successful deployment of FCW systems, the Ford-GM Crash Avoidance Metrics Partnership (CAMP) developed preliminary minimum functional requirements for FCW systems implemented on light vehicles (passenger cars, light trucks, and vans). This paper summarizes one aspect of the CAMP results: minimum requirements and recommendations for when to present rear-end crash alerts to the driver. These requirements are valid over a set of kinematic conditions that are described, and assume successful tracking and identification of a legitimate crash threat. The results are based on extensive closed-course human factors testing that studied drivers' last-second braking preferences and capabilities. The paper reviews the human factors testing, modeling of results, and the computation of FCW crash alert timing requirements and recommendations.
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