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Viewing 70801 to 70830 of 104161
1988-09-01
Technical Paper
881263
Nabi Dedeoglu, Timothy Kajina
The scavenging process is an incompressible process, which infers that it is a volumetric process. As such, its success depends on the volume of scavenging air. For a given port configuration, the higher the scavenging air volume the higher, the trapped fresh air volume in the cylinder. But this method leads to a less trapped fresh air mass in cylinder because of its lower density. The aim of two-stage scavenging is to increase the amount of the trapped fresh air mass. For this purpose the scavenging air is divided into two portions, namely warmed and unwarmed. During the first stage the cylinder is scavenged with the warmed portion resulting in a higher volumetric purity factor due to the higher scavenging air volume. The unwarmed air portion having a higher density is in the second stage to fill the already well-scavenged cylinder. The maximum fresh air mass in the cylinder is obtained if the two portions are divided almost equally.
1988-09-01
Technical Paper
881225
K. Nishiwaki
Deposit surface temperature was measured by an infrared technique in a motored engine at the wall temperature level nearly as high as in fired engines. This condition made the infrared measurements free from flame radiation noise. Deposit thermal diffusivity was obtained by measuring the response of a dirty surface thermocouple to a photo-flash. For computational analyses, the deposit was modeled as a solid having the measured thermal diffusivity. The computations used the experimental deposit surface temperature measurements as boundary conditions and established heat conductivity and heat capacity of the deposit. Thermal effects of porous structure of deposits were discussed by solving the fin model which allowed heat exchange between a solid material and a gas inside deposits. In the fin model computation the deposit behaves as if it had larger heat capacity as a single material solid.
1988-09-01
Technical Paper
881224
Noboru Miyamoto, Zhixin Hou, Hideyuki Ogawa
The oxidations of Crapped diesel soots containing catalytic metals such as Ca, Ba, Fe, or Ni were characterized through thermogravimetric analysis with a thermobalance. Soot particles were generated by a single cylinder IDI diesel engine with metallic fuel additives. A two-stage oxidation process was observed with the metalcontalning soots. It was found that the first stage of oxidation is catalytically promoted by metal additives resulting in an enhanced reaction rate and a reduced activation energy. Soot reduction in the rapid first stage increases with increases in metal content. Soots containing Ba and Ca are oxidized most rapidly due to the larger reduction during the first stage. The second stage of oxidation is also slightly promoted by metal addition. The ignition temperature of the collected soot is substantially reduced by the metal additives.
1988-09-01
Technical Paper
885007
E. Herb, H. Krusche, E. Schwartz, H. Wallentowitz
Abstract In the past there was a development of stability control systems for front- and rear-wheel driven cars. These systems will come to the market under the names ASR, ETC or ASC. Completely independent of these systems, four-wheel driven cars were developed. They have, specially with locked differentials, maximum traction. In this paper we are combining four-wheel driven cars with the systems for stability control. We made some research, in what way the independent systems add to each other, optimize the driving behaviour of the vehicle. These works were done with comprehensive computer-simulation and with experiments on real cars. It will be shown, that the combination of the systems will be possible, if we will get a reference for the wheel velocities. Possibilities for solving this problem are additional sensors or the use of the vehicle dynamics theory in the real cars. As a result, control systems are developed, which will help the drivers in critical driving situations.
1988-09-01
Technical Paper
885005
D. S. Fine
1988-09-01
Technical Paper
885006
H. Stumpf, G. Arendt, F. Lux
High speed tires were measured on the road and in the lab, both on a rear wheel drive and a front wheel drive vehicle. The tests described refer to standard methods used in the tire industry. They include various tire patterns as well as direction-oriented patterns. Depending upon vehicle type and driven axle, the subjective test result in varying sequences in the main groups of tested parameters - slalom, curve behaviour, handling characteristics and steering response. Static, quasi-static and dynamic measurements on tires were performed in the Semperit lab. The data obtained in the lab did not result in distinct sequences. In case we have to decide which tire is best suited for the intended purpose, the basis for decisions in neither precise nor clear, and conventional engineering mathematics will not suffice. Therefore, “Fuzziness” has to be introduced. The basis of the Fuzzy-Set-Theory is a maximum/minimum principle.
1988-09-01
Technical Paper
885003
John G. Cherng
Engineering education is at a transition stage in its move from conventioal teaching methods to computer aided teaching methods. Engineering colleges should take prompt action so this transition will be smooth. The objective of this paper is to present some feasible suggestions that can be implemented by engineering colleges. First, a status analysis summarizes the result of a literature search on the development and activities of Computer-Aided-Design (CAD) and Computer-Aided-Manufacturing (CAM) among colleges, universities, and technical institutions. Then a number of areas including new course structure, new courses, new texbook, information coordination, software interface and laboratory upgrading are discussed in detail to demonstrate how CAD/CAM can be integrated into a comprehensive engineering curriculum. Finally, the experience of the School of Engineering of the University of Michigan-Dearborn is included as an example.
1988-09-01
Technical Paper
885001
Alberto Morelli
The automotive technologies as education disciplines were introduced in the Turin Technical University in the far-off 1931-32 academic year, mainly for military purposes. The evolution of education that has taken place so far is shown and put in connection with the development of both the industrial and scientific progress in the automotive techniques and the subsequent reforms of education programmes in the Faculty of Engineering of Italian Universities. The role of cooperation mainly between University and Industry, is examined. The present state of the programme of studies is also reported, together with the development trend. The methods adopted in order to obtain a satisfactory profit of the students and to keep the teaching staff up-dated with the technical progress is finally reported upon and discussed.
1988-09-01
Technical Paper
885004
Ali Seireg
The education of the engineer should reflect the importance of technical management by incorporating specially designed courses in the curriculum. The paper discusses the author's views on the educational needs in this area and the initiatives underway in the ASME towards the development of a body of knowledge for training and the continuing education of the mechanical engineers.
1988-09-01
Technical Paper
885002
F. E. Plonka, R. J. Piccirilli, R. L Stewart
Increased global competitiveness in the automotive industry has demanded major improvements in manufacturing performance. One method for improving manufacturing performance is the development of computer-based systems to support the manufacturing process. This paper outlines a number of computer systems developed within Chrysler Motors to improve manufacturing performance. The paper also reviews the training required and the performance benefits gained by each system. At Chrysler Motors we are continually striving to train our employees in the use of effective manufacturing computer systems to support the building of an internationally competitive vehicle.
1988-09-01
Technical Paper
885016
Antonio Ficarella, Domenico Laforgia
A simulation model of an injection system for reciprocating engines has been developed to study the influence of the geometrical and mechanical configuration of the injection apparatus on the injection flow characteristics. The suggested model simulates pressure wave propagation in the pipelines, particularly in presence of cavitation, and injector behaviour. The model used for nozzle simulation evaluates fluid-dynamic phenomena in the nozzle sections and chambers. This allows prediction of injector geometry influence on the flow parameters and simulation of general behaviour of the apparatus and the spray using different nozzles (with sac, without sac, with reduced sac). Lastly, a model of the structure by a finite elements method allows the study of dynamics of the moving elements. The mathematical model has been verified through a series of experimental measurements. The comparison between numerical and experimental results has been satisfactory.
1988-09-01
Technical Paper
885017
Sarim Jawad AL-Zubaidy
The present paper applies a previously published semi-empirical method for calculating laminar and turbulent boundary layer for the purpose of analysis and design of rectangular, straight-wall diffusers (with arbitrary free stream pressure gradient) to estimate performances of diffusing channels with alternative wall geometries. The method has been used on diffusers with concave and convex wall contouring (in addition to straight profile) having the same air inlet speed. The calculation for concave-wall diffusers agreed reasonably well with available detailed experimental results over wide range of area ratio variation (1.2-2) for constant inlet blockage. However, when the prediction method was used to calculate likely performance of diffusers with convex wall contouring, it could only give poor estimates for low value area ratio diffusers (equal or less than 1.2), the method could not predict performance of higher area ratio diffusers.
1988-09-01
Technical Paper
885014
Klaus Egger, Maximilian Kronberger
The development of future passenger car diesel engines has to be pointed in many directions. Present diesel techniques already set high standards on fuel economy, as the gasoline engines with catalytic converters did in passenger car application on performance, exhaust emissions, noise and vibrational emissions. Unit Injectors for airborne mixing direct injection diesel combustion offer the flexibility necessary to form injection rate patterns and associated injection pressures for the sake of combustion tuning. The development steps of a small pilot injection of high cyclical precision which is load independend at lower speeds and which disappears into a high-rated injection at the upper speed range are discussed. Recent test results of a prototype engine indicate the high potential of HSDI engines with such Unit Injectors to meet standards on fuel economy in combination with performance and emissions far beyond today's serial diesel engines for passenger cars.
1988-09-01
Technical Paper
885015
H. P. Lenz, G. K. Fraidl, H. Friedl
The performance of SI engines is substantially influenced by the degree of fuel atomization that occurs within the mixture preparation system. With a measuring device, based on laser Sight diffraction, it is possible to determine droplet size spectra with high temporal and spatial resolution, even if the droplets are moving with high velocity. However, with such a measuring device, the influence of density gradients within the measuring volume, as that created by fuel vapor or temperature differences, can be critical and must be taken into consideration to provide satisfactory results. The degree of atomization depends on the engine operating conditions, namely engine speed and load.
1988-09-01
Technical Paper
885012
Dietmar Hermann
NEW SEALING ELEMENTS MADE OF ELASTOMERIC MATERIALS TO MEET THE HIGH DEMANDS OF THE AUTOMOTIVE INDUSTRY Use of automated manufacturing as well as the call for more comfort and less fuel consumption are just some of the key requirements facing today's designers of new vehicles. The elastomer industry has risen to this challenge and, through the implementation of innovative technologies, can now offer the vehicle designer a wide range of alternatives. Developments in process engineering have made it possible not only to optimize the frictional resistance and anti-wear properties of the elastomer's surface, but also to vary the extrusion's section during actual production. In addition the industry supplies pneumatically controllable elastomeric extrusions with two stable phases, which are used, for example, on vehicle doors and radiator grilles.
1988-09-01
Technical Paper
885013
G. Frankl, B. G. Barker, C. T. Timms
In comparison with current production diesel engines the next generation will need to have better fuel consumption, lower noise and reduced emissions both gaseous and visible. Research over the last ten years has shown that higher rates of injection, coupled with a sharp end of injection and precise timing control will give considerable benefits. The Lucas CAV response to this requirement is the development of an electronically controlled unit injector system which provides these characteristics. This paper describes the operating principles and looks at the main performance parameters, including design considerations for continuous operation at pressures up to 1500 Bar. As the unit injector is a new concept to many engine manufacturers, Lucas CAV has developed a suite of computer programmes to assist in the design and engine application process in terms of a complete hydraulic simulation, unit injector drive train analysis and cam design.
1988-09-01
Technical Paper
885009
P. Ratti
The mathematical simulation of road vehicle dynamics under extreme or coupled conditions depends on an accurate tire modelling. The goal of this study was to develop a simple model taking into account the non linearities and the interactions between longitudinal, transverse and vertical forces in all conditions of road surface and velocity. The basic concepts are Coulomb's friction law, and the shear stresses between the road and the tire tread rubber, the tread being reduced to its equatorial line linked to the wheel rim by an elastic carcass. The behavior of the friction and elasticity coefficients is derived from experimental and simplified local models. A vehicle handling simulation program based on this tire model was developed by RENAULT. Some examples of calculations show the importance of the model for a realistic theoretical study of road vehicle handling.
1988-09-01
Technical Paper
885018
C. C. Colyer, K. E. Davis, M. E. Desing, S. E. Jaynes, W. G. Copan
Laboratory engine tests have beets used to evaluate the performance properties of engine oils for more than four decades and have been progressively modified to meet the lubrication challenges from new engine designs, operating conditions, fuels and emission controls. Engine sequence or bench laboratory tests are an important first step in the development of passenger car crankcase oils. These tests are correlated with reference oils of conventional additive chemistry with known field performance. When using conventional additive chemistry, sequence tests usually provide an excellent correlation with field performance. However, when new or novel chemistry is employed, laboratory testing may not be an adequate indicator of field performance. In these situations, actual field tests must be conducted. There are also other reversals or unexpected results which further require field tests as the final proof of performance.
1988-09-01
Technical Paper
885134
Mounir M. Kamal
A series of studies at the General Motors Research Laboratories have demonstrated the practical benefits of constructing automotive structures as three dimensional space frames with attached panels. Importantly, a metallic space frame with a plastic skin has been shown to be a highly weight-efficient passenger car structure.
1988-09-01
Technical Paper
881280
Frederick A. Lloyd, John N. Anderson, Laurie S. Bowles
The performance of friction material in an oil-cooled environment is greatly influenced by conditions of use. Power, speed, oil flow, and inertia are some of the factors whose effects on material performance have been documented in the literature. These factors interact in a complex manner which makes it difficult to predict material performance. The effects of several major factors-power, speed, inertia, oil flow, and reaction plate thickness-were investigated using an inertia dynamometer. The program was designed to assess the relative significance of each factor in determining material performance and to examine how effects of each factor are modified by interaction with other factors. Three materials were tested. Groove pattern was investigated as a means of modifying the effects of other factors.
1988-09-01
Technical Paper
881324
W. F. Olszewski, D. J. Taylor
The demands placed upon power train lubricants have become increasingly severe with advances in automotive equipment design. Higher operating temperatures, speeds and gear/bearing loads are stressing the capabilities of current mineral oil powertrain lubricants. Gear lubricants based on synthetic fluids provide outstanding service under these conditions and offer a number of performance advantages. This paper reviews the performance of fully synthetic gear lubricants in a variety of laboratory and vehicle tests and comparisons are made with premium mineral oil lubricants. Field testing under severe conditions and extended service periods is also discussed. EXTENSIVE RESEARCH HAS BEEN DEVOTED over the past 40 years to the development of powertrain lubricants of improved performance. Significant advances have been made in lubricant technology to keep pace with advances in powertrain design.
1988-09-01
Technical Paper
885138
Liu Rong Di
This paper intends to establish a mathematical model based on the relations between “road”, “vehicle”, and “driver” for predicting the braking status on downhill drivings. Surveys of different road conditions in the mountainous areas in the western as well as eastern districts in China were first carried out as the basis of investigations. Taking different mountainous roads as composed of combinations of various kinds of short segments of road path with known gradients (it is referred to “element road”), and the vehicle as a moving mass with known parameters, getting the control behavior of drivers through statistics, we establish first the mathematical model of a single segment of road path with known gradient. Using this model as a base, we can establish then a generalized model by calculating through segment by segment for various kinds of hill slopes with different vehicles and braking requirements.
1988-09-01
Technical Paper
881272
Thomas Gallant
Coolant hose for heavy duty engines are required to provide long service life under very demanding conditions. To develop a coolant hose/joint assembly to meet these requirements, a life cycle test rig has been developed that can closely simulate engine conditions in heavy duty applications. Hoses of various materials, reinforcement and construction were tested for up to 2000 hours and evaluated for retained burst strength, leakage, and serviceability. The test has correlated very well with field experience.
1988-09-01
Technical Paper
881331
Narayan Yoganandan, Frank Pintar, Anthony Sances, Dennis Maiman, Joel Myklebust, Gerald Harris, Gautam Ray
In vitro biomechanical studies were conducted on fresh human cadaveric thoracolumbar spines to establish the limits of tolerance, explain the mechanism of failure, and investigate the effects of improvement in strength and stability of the injured column using Harrington distraction rods, Luque rods and modified Weiss springs. Quasistatic axial tensile loading on ligaments, compressive loads on vertebra) bodies and intervertebral discs, and flexure and compression-flexion force vectors on ligamentous columns, intact torsos and injured spines were applied to delineate the biomechanical and functional patho-anatomic characteristics. Vertical drop tests were conducted with the Hybrid II manikin to predict the forces and accelerations on the vertebral column.
1988-09-01
Technical Paper
885008
Dennis T. Kunkel, Ronald L. Leffert
This paper summarizes the technology and methodology used at General Motors for the objective measurement of vehicle directional response characteristics. It serves to update previous publications regarding this subject and presents information on new test procedures. Trends noted from statistical analysis of production vehicle performance data are also discussed.
1988-09-01
Technical Paper
885082
J. C. Van Dest
1988-09-01
Technical Paper
881315
Jingde Yan, Gary L. Borman
In-cylinder flame temperature and particulate concentration were measured in a Cummins single cylinder NH diesel engine by means of an optical radiation probe using the two-color theory. The radiation probe consists of a specially designed trifurcated fiber optical bundle and a sapphire rod window. A self-cleaning window was designed, which stays clean under steady state full load conditions. The engine was operated at various conditions for both standard cooled and simulated mini-cooled configurations. The heat release rate data and exhaust emissions, NO, NOx and CO are presented along with the radiant emission data. Increasing the coolant temperature gave slightly more exhaust soot production as well as in-cylinder soot production, because more late burning occurred at the higher coolant temperature. It is believed that increased late burning was caused by the delayed end of injection and lower injection rate perhaps due to thermal expansion effects in the injector.
1988-09-01
Technical Paper
881233
R. Beaulieu, J. Klatka
Lasers are used in the metal working industry for a variety of operations including welding, drilling, cutting, heat treating and marking. This paper will focus on the laser as a marking tool and the resulting effects, both physical and metallurgical, on bearing steels.
1988-09-01
Technical Paper
881232
C. A. Moyer, H. P. Nixon, R. R. Bhatia
Significant advances in bearing material quality, resulting in measurably cleaner steels, have provided increased ratings and extended performance in The Timken Company standard product tapered roller bearings. Using a sizable database of test results collected over the past years, along with appropriate analysis methods, it has been possible to identify those advances needed to provide additional improved bearing performance. New advances in bearing design and manufacturing technology, as exemplified by enhanced internal bearing geometry and advanced finish processing, indicate improved bearing performance can be achieved in smaller bearing designs or increased reliability or extended life within existing bearing sizes. Such advances culminated in the new Performance 900™ bearings announced by The Timken Company in February 1988.