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Technical Paper

Heavy Duty Truck Cooling System Design Using Co-Simulation

2001-05-14
2001-01-1707
In order to meet the legislated emissions levels, future diesel engines will likely utilize cooled exhaust gas re-circulation (EGR) to reduce emissions. The addition of the EGR cooler to the conventional vehicle coolant system creates several challenges. Firstly, the engine cooling system flow and heat rejection requirements both increase as it is likely that some EGR will be required at the rated power condition. This adversely affects packaging and fuel economy. The system design is further complicated by the fact that the peak duty of the EGR cooler occurs at part load, low speed conditions, whereas the cooling system is traditionally designed to handle maximum heat duties at the rated power condition of the engine. To address the system design challenges, Ricardo have undertaken an analytical study to evaluate the performance of different cooling system strategies which incorporate EGR coolers.
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

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

Powertrain Mounting Development Based on Computational Simulation and Experimental Verification Method

2001-04-30
2001-01-1509
This paper presents a method applied in the development of an optimized transmission rubber mount of a midsize Diesel pickup. The focus of this optimization were to improve the vibration insulation and consequently improve the NVH (Noise and Vibration Harshness) quality of the vehicle. The paper describes the basic mounting design and manufacturing constrains, the simulation modeling basis, inputs required to perform the computational simulation, the experimental method used to extract the center of gravity and rotational inertia of the powertrain and a general mounting tuning strategy. The mounting dynamic simulation results for the optimized version is also presented compared to the original one. In order to quantify the noise and vibration improvements, the internal noise and vibration transmissibility levels were measured and compared in percentile reduction basis to current vehicle levels
Technical Paper

Effect of Seating Foam on the Acoustic Behavior of an Earth-Moving Cab

2001-04-30
2001-01-1560
The designs of vehicle seats have significant impact on interior acoustic modes as well as sound pressure level inside the vehicles. Seats trimmed with elastic porous materials are especially critical to the acoustic behavior of the vehicles due to the sound absorption of the materials. This paper demonstrates how seating materials affect the acoustic performance of an earh-moving cab. To accurarely simulate the sound absorption of the seat, the seat was modeled as a bulk reactive absorber instead of a local reactive absorber.
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

CFD Optimization of an EGR Cooler for Heavy-Duty Diesel Engines

2001-05-14
2001-01-1755
The gas flow and heat transfer in an EGR cooler has been studied using Computational Fluid Dynamics method (CFD). The shell-and-tube cooler is intended for heavy-duty diesel engines EGR cooling applications. The influence of the diffuser shape has been studied with regards to pressure drop, flow distribution across the tube bundle, and heat transfer. Inlet temperature is 250 °C, and flows varies from 100 up to 200 g/s. These results were compared to experimental measurements. The influence of the bundle size and design has also been investigated for two designs. A single tube cooler test bench has also been developed to validate the CFD flow and heat transfer models. In flow temperature measurements are provided. The bigger tube bundle has advantages both in terms of pressure drop and even flow distribution. The mean outlet gas temperature is also decreased by 6% in this case. The design of the diffuser has important consequences on flow distribution and pressure drop.
Technical Paper

Vehicle Exhaust Emissions Benefit from a Regulatory Cap in Gasoline Distillation Index

2001-05-07
2001-01-1963
The Distillation Index (DI) is a measure of the volatility of gasoline, especially its tendency to vaporize in an engine at initial start-up and during warm up. On January 27, 1999 the U.S. domestic and import automotive manufacturers petitioned the US EPA to limit the DI of all U.S. gasoline to 1200 degrees Fahrenheit as a means of reducing in-use emissions and ensuring consistent cold start and warm-up driveability.[1] Air Improvement Resource, Inc. (AIR) completed a 1999 study that evaluated the benefits of a DI cap. Overall, the 1999 AIR study estimated that the DI cap would produce a 16 and 15 percent reduction in hydrocarbon (HC) and carbon monoxide (CO) exhaust, respectively, from gasoline vehicles nationally in 2020. [2] In 2000, the Alliance of Automobile Manufacturers sponsored a more compreshensive examination of the emission consequences of the DI cap on which this paper is based.
Technical Paper

Analysis of Combustion Instability Phenomena in a CNG Fueled Heavy-Duty Turbocharged Engine

2001-05-07
2001-01-1907
The use of Compressed Natural Gas as an alternative fuel in urban transportation is nearly established and represents an efficient short and medium term solution to face with urban air pollution. However, in order to completely exploit its potential, the engine needs to be specifically designed to operate with this fuel. In the latest years, the authors have investigated the performances of a Heavy Duty Turbocharged CNG fuelled engine both experimentally and by using some analytical tools specifically developed by them which have been used for the engine optimisation. In the present paper the simulation approach has been enlarged by means of a co-operative use of a CFD code and experimental analysis on the actual engine. The numerical simulation of combustion process has, in fact, been used, to interpret series of pressure cycles, aiming to analyse how cyclic fluctuations influence engine behaviour in terms of combustion efficiency and temperature and pollutant distribution.
Technical Paper

The Influence of Body Layout on Vehicle Pitching Behavior in ATV (part 1)

2001-12-01
2001-01-1873
This paper intends to verify the following in order to clarify the influence of the body layout on ATV pitching behavior, and for the purpose of helping develop a more pleasing product, it reports the research results based on the theory and experiment concerning the effect of body geometry on vehicle dynamics, with particular emphasis on vehicle behaviors under acceleration and deceleration. A discussion of vehicles employing the chain drive or swing arm system involves a number of factors that contribute to pitching motion. Such factors can be roughly divided into two effects. One effect arises from a load transfer in every vehicle due to the inertial force acting on sprung mass, and the other is the force that is activated by a chain drive and a swing arm system and thus demands geometrical consideration.
Technical Paper

Basic Considerations for the Concepts of Wheeled off-Road Vehicles

2000-06-12
2000-05-0387
The demand for greater mobility on unprepared terrain in all seasons by agriculture, construction, and the military has stimulated interest in the study of off-road vehicles. Thus the use of automobiles for cross-country movements and the potential for building more efficient automobiles and vehicles with high off-road mobility has also increased significantly. The engineers and designers of off-road vehicles face a lack of generally recognized theories. Usually, the concept of terrain vehicles are developed very empirically and are based on principles of mechanics and land locomotion. The author presents a general overview on models and considerations for wheeled off-road vehicle concepts. First vehicle and soil are defined, then the interaction between these two elements is discussed. Based on these models, methods to predict and measure traction of off-road vehicles are evaluated. The relevant elements of off-road vehicles and their influence on mobility are presented.
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

A Theoretical Study on Front Steering Angle Compensation Control for Commercial Vehicles

2000-06-12
2000-05-0244
This study investigates a control strategy using the front steering angle control to improve the handling and stability of heavy-duty vehicles as a possible substitute for four-wheel steering (4WS) system. The effective steering input is regulated through the state feedback computed by the optimal control theory suggested in this research, to adapt the closed system to the changes of some factors depending on running situations, such as velocity and center of gravity. Direct moment control with a simple auto-tuning proportion controller is also integrated in the compensation system, wherein yaw moment and roll moment are applied to decrease side slip angle and roll angle respectively. A double-cost-function LQR methodology (DLQR) is developed to compute the value of the front steering angle compensation.
Technical Paper

Development of Application Technique of Aluminum Sandwich Sheets for Automotive Hood

2000-06-12
2000-05-0237
Objective of this study was to develop basic techniques in order to apply aluminum sandwich sheets for an automotive hood part. The aluminum sandwich sheet is the material fabricated by adhering two aluminum skins to one polypropylene core. When it has the same bending stiffness as a steel sheet, it is 65% lighter than the steel sheet and 30% lighter than an aluminum alloy sheet. Therefore, it is notified exclusively as good substitutive materials for a steel body to improve the fuel efficiency. Through aluminum sandwich sheet, however, it has relatively lower formability than that of the steel sheet for automotive application. In this study, we fabricated a prototype of the automotive hood panel to develop application techniques of the aluminum sandwich sheet.
Technical Paper

Dynamometer Testing of a Heavy Duty Diesel Engine Equipped with a Urea-SCR System

2001-03-05
2001-01-0516
As part of a California Selective Catalyst Reduction (SCR) system demonstration and evaluation project [13], the authors and their industrial partners have conducted engine dynamometer emissions tests of SCR systems. The transient Federal Test Procedure (FTP) cycle and 13 Mode European Stationary Cycle (ESC) were conducted using certification diesel fuel with 300-500 ppm of sulfur. This paper reviews the performance of the first system to meet the goal of attaining 1 g/bhp-hr NOx emissions in the transient FTP cycle on a 1999 DDC Series 60 engine that has an initial 4 g/bhp-hr level. This paper discusses key characteristics of a typical automotive SCR system and then presents the results and analysis of the engine dynamometer emission testing of a SCR system. The paper concludes with a discussion of the challenges involved in on-road operation of the system.
Technical Paper

SIMON: A New Vehicle Simulation Model for Vehicle Design and Safety Research

2001-03-05
2001-01-0503
SIMON is a new vehicle dynamic simulation model. Applications for SIMON include single- and multi-unit vehicle handling simulation in severe limit maneuvers (including rollovers) and 3-dimensional environments. Applications also include vehicle-to-vehicle and vehicle-to-barrier collisions. This paper provides the technical background for the SIMON engineering model. The 3-dimensional equations of motion used by the model are presented and explained in detail. The calculations for suspension, tire, collision, aerodynamic and inter-vehicle connection forces and moments are also developed. The integration of features available in the HVE Simulation Environment, such as DyMESH, the Driver Model, Brake Designer and Steer Degree of Freedom, is also explained. Finally, assumptions and limitations of the model are presented.
Technical Paper

Heavy-Duty Diesel Truck In-Use Emission Test Program for Model Years 1950 through 1975

2001-03-05
2001-01-1327
Criteria pollutants were measured from ten Class 7 and 8 (i.e., gross vehicle weights > 33,000 lb) heavy-duty diesel trucks with engine model years between 1953 and 1975. The data was used by EPA to estimate that period's particulate matter emission rates for these type engines and will be used to develop dose response relationships with existing epidemiological data. Particulate samples were analyzed for sulfate and volatile organic fraction. Carbon soot was estimated. The trucks had particulate emissions of 2 to 10 g/mi as compared to 1 to 6 g/mi for trucks with model year engines from 1975 through the mid-1980s, and less than 1 g/mi for post-1988 trucks.
Technical Paper

Comparative Assessment of DPFs of Different Materials: A Case Study on a Euro I Light Duty Truck

2001-03-05
2001-01-1287
A test protocol, allowing for the evaluation of diesel particulate filters of different materials and of different sizes, located at various distances from the engine was developed. A total of 13 filter configurations were tested on a Euro I naturally aspirated diesel light duty truck with a fully passive trap system, utilizing only cerium-based additive in the fuel. It was proved that regeneration under constant urban driving conditions was always possible, at an exhaust gas temperature at the trap inlet in the range of 250 - 350°C. On a gravimetric basis, the efficiency of the traps tested concerning PM was in the order of 45 - 80% over the NEDC, depending on trap material and location along the exhaust pipe and reflecting the specific composition of the PM generated by the vehicle. No major effect on gaseous emissions (HC, NOx and CO) was observed.
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