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Viewing 70801 to 70830 of 104148
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
1988-08-01
Technical Paper
881178
Charles D. Wood
Combustion of highly non-homogeneous fuel-air mixtures and the use of hydrodynamic lubrication of piston rings are identified as barriers to long-term progress in diesel engines. The characteristics of non-homogeneous mixtures are discussed and the effects of various injection system modifications are illustrated using a turbulent fuel jet model. The problems caused by the hydrodynamic oil film at the piston rings are identified, and the potential of boundary lubrication is discussed.
1988-08-01
Technical Paper
881175
Robert L French
Future on-board navigation and information systems for automobiles will automatically keep the driver informed of current location, deduce best routes to specified destinations taking into account current traffic and road conditions, and provide turn-by-turn route guidance according to where the automobile is along the route. Other road transport informatics functions will include location-keyed directory services and automatic vehicle identification for toll and parking billing. These systems will be integrated with systems for automatic headway control and collision avoidance and, eventually, automatic vehicle control. Advanced on-board information systems require integration of vehicular navigation technologies such as dead reckoning, proximity beacons, and radiolocation with various other technologies including digital cartography, data processing and storage, mobile data comunications, information display, voice synthesis, etc.
1988-08-01
Technical Paper
881176
Hiroyuki Okamoto
The Japan Traffic Management and Technology Association, by the suggestion of the National Police Agency, studies the Advanced Mobile Trafffic Information & Communication System (AMTICS) from the beginning of last year in cooperation with the Ministry of Posts and Telecommunications (MPT) and private 59 corporations.
1988-08-01
Technical Paper
881212
Keith Parmee
The Paper deals with the development of commercial vehicle transmissions since 1895 and highlights the author's personal views on the differences between the European and American markets. The Paper also explains current developments towards electronically enhanced transmissions.
1988-08-01
Technical Paper
881181
Tom Bitzer
This paper briefly discusses the different kinds of honeycomb; how the core is manufactured, the basic sandwich design parameters and reasons for its use. Current and future honeycomb transportation applications are also presented.
1988-08-01
Technical Paper
881184
David D. Shepard, David R. Day, Huan L. Lee
Implantable microdielectric sensors are routinely used to monitor the cure of thermosetting polymers. Until recently, the cure monitoring of Reaction Injection Molding (RIM) processes has been difficult due to the short reaction times of RIM materials in relation to the time required to make the dielectric measurements. New high-speed hardware and software (8.3 milliseconds per measurement) has been developed for the dielectric cure monitoring of RIM systems. Dielectric curing data collected with both the existing and new hardware and software are discussed.
1988-08-01
Technical Paper
881179
Hans Welters, Jürgen Helling, Rolf MeiBner
A microprocessor-based power control unit has been developed for an off-road utility vehicle (16 to., 240 kW). The control unit enables the internal combustion engine to be operated according to selected criteria, such as minimum fuel consumption or minimum noise emission. Implementation of the microelectronics, instrumentation and control peripherle and additional safety components in the test vehicle was followed by an extensive programme of developement and testing. There were evident advantages for the electronic control unit as compared to series models, for example in respect to consumption and to the operating and driving characteristics of the vehicle.
1988-08-01
Technical Paper
881180
Raju S. Dave', John L. Kandos, M. P. Dudukovic
The autoclave process is one of the often used production procedures for making structural composites in the aerospace industry. An autoclave is a pressure vessel that operates under control temperature and pressure. The fabrication of composites by the autoclave process is complex. It involves simultaneous heat, mass, and momentum transfer along with chemical reactions in a multiphase system with time-dependent material properties and boundary conditions. The critical problems that arise during the production of thick composites are the occurrence of severely detrimental voids, gradients in resin concentration, unequal cure at different points in the composite, and thermal stresses. In order to efficiently manufacture quality parts, on-line control and process optimization are necessary, which in turn require a realistic model of the entire process. In the past, chemoviscosity, heat transfer, resin flow, and void growth models have been developed for thermosetting resin system.
1988-08-01
Technical Paper
880987
Jerry R. Blevins, Merlyn L. Hutchins
1988-08-01
Technical Paper
880986
E. Göhring
Since 1982 Daimler-Benz is the first commercial vehicle and bus manufacturer to offer modern anti-lock systems (ABS). After several years of development, anti-lock systems have technically matured to be installed upon request in vehicles with air brakes. The installation rate of this safety item has been steadily increasing ever since. The fundamental design and control philosophy of 4- and 6-channel anti-lock systems will be described. Besides a global analysis regarding the failsafe quotas of digitized electronics in road vehicles, the ABS-specific components will be looked at. The gain of safety achieved by the installation of ABS in commercial vehicles and buses will be presented with the aid of computer simulation. A 40-t-truck/trailer combination, with ABS, without ABS and with a partially defect system, will serve as an example to demonstrate the dynamic behavior during “Braking in a Straight Line” and “Braking in a Turn”
1988-08-01
Technical Paper
881133
Lane R. Miller, Charles M. Nobles
This paper describes the fundamental concepts of semi-active control, and the development and testing of a semi-active suspension on an M551 tank. The single degree-of-freedom (SDOF) model of a vehicle suspension is used in explaining the basic concepts. Background information is presented on conventional, fully active, and optimal suspension systems. One goal of this paper is to give the reader an intuitive “feel” for semi-active control. Primary vehicle suspension systems are a natural application for semi-active control, but the concepts apply equally well to general vibration isolation problems.
1988-08-01
Technical Paper
881134
Theodore G. Duclos
Electrorheological fluids (ER fluids) are materials with the potential to radically change the way electromechanical devices are designed and operated. Working from constitutive equations of the basic ER fluid phenomena, equations for assessing the feasibility of using ER fluids in clutches, dampers, and mounts can be derived. Using these equations, the impracticality of using currently available ER fluids in primary suspension dampers and power train clutches can be clearly demonstrated. The practicality of using current ER fluids in engine mounts can also be demonstrated. Finally, the feasibility assessments of the clutch and dampers can be used to determine the improvements necessary in the performance of ER fluids which will make these applications feasible.