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Viewing 70801 to 70830 of 107228
1990-02-01
Technical Paper
900788
William E. Mercer
Mechanical testing and prototyping of several developmental magnesium die cast alloys have shown that certain magnesium alloys can be exposed to temperatures in excess of 232°C (450°F) and still have adequate strength. For example, one of the alloys tested at 260°C (500°F) had a tensile yield strength greater than 87 HPa (12.7 ksi). Further testing also revealed that some of these alloys possess better creep strength at 316°C (600°F) than AZ91D has at 177°C (350°F) with at least as good castability as AS41A.
1990-02-01
Technical Paper
900785
Michael J. Narusch
Information is provided on a new, innovative coating process which is now available in the U.S. and Canada through Metal Coatings International Inc. Data on this patented technology includes the details of the base coating process which applies a zinc-iron alloy. This coating results from “impact blasting” the metal substrate, particularly steel, with special zinc-iron alloy media in equipment similar to shot blasters. The zinc-iron alloy coated surface can then be passivated with a special chromate coating and/or with special top-coat paints. These coatings synergistically result in outstanding corrosion resistance for a wide variety of stamped, fabricated, forged or cast metal parts. Many other advantages are also presented, such as the absence of any significant process heat, demonstrating that the impact plating technology offers metal finishers, as well as parts manufacturers, new, definitive solutions to many of their coating and application problems.
1990-02-01
Technical Paper
900786
Susan E. Housh, John S. Waltrip
Safe handling of magnesium alloys in the high volume die cast production plant is an integral part of the overall manufacturing process. There are inherent problems involved with handling molten metals and handling molten magnesium alloys is no different. The risks must be identified and managed through proper procedure and employee training. Proper handling practices as related to employee and equipment safety will be discussed along with procedures for handling emergency situations.
1990-02-01
Technical Paper
900781
Takahiro Manabe, Mikio Nozu, Osada Yasuhito, Yasuhiro Shiraishi, Ikuo Katsumata
Abstract As the car-mount electronic control devices are increasing in number and variety, power train control devices for controlling actuators such as motors and solenoids are intensively developed at great speed. The electronic circuits used in these devices contain microcomputers, LSIs and ICs that have arithmetic processing functions, and power transistors that drive the actuators, and therefore they are always accompanied by the problem of temperature rise of electronic circuit elements due to heat generation of power transistors caused by operation of the devices, which made it difficult to reduce the size of the device while guaranteeing the reliability.
1990-02-01
Technical Paper
900779
Myrna Cotran Sultan, Dah-Lain Tang, Man-Feng Chang
An engine and starting system computer simulation is described. The simulation consists of physically-based models of the engine, battery and starter motor during engine starting. The interaction between the engine dynamics and the starter motor dynamics is shown for two types of starter motors: a series wound-field starter motor and a permanent magnet gear reduction starter motor. The engine dynamics are determined by engine combustion, friction and engine inertia, while the starter motor dynamics are determined by the motor's torque versus speed characteristic, and its effective inertia as seen by the engine.
1990-02-01
Technical Paper
900780
Shoji Matsubara, Takashi Kuwahara, F. Bruce Gerhard
Abstract The ongoing advances being made in electronics technology has made it possible to expand the range of microcomputer applications in automotive engine control systems. Progress in this field of application has given rise to very sophisticated control systems called total engine control systems, which are designed to provide interacting control with other subsystems (e.g., antiskid braking system, traction control system, transmission control system), instead of just controlling the engine itself. Improved engine control system performance and more versatile functions have made the application software controlling the system larger, with more complex control processing. Until now, control processing in engine control systems could be implemented by the microcomputer's interrupt processing program alone.
1990-02-01
Technical Paper
900795
D. Nardini, I. J. McGregor, A. D. Seeds
The paper describes problems and suggested solutions in use of adhesive bonding for joining aluminum structures. Different ways to model and analyse a bonded joint are presented along with discussion on various advantages and drawbacks. As an example, the modelling and experimental results of a design exercise on a vehicle front cross-member are presented. The use of detailed joint modelling in determining the influence of local joint geometry on both adhesive and metal stresses is also demonstrated.
1990-02-01
Technical Paper
900794
Chris Suman
The effects of low temperature thermal processing on diecast magnesium alloys AZ91D and AM60B were studied to determine the impact of manufacturing processes such as the baking of coatings on mechanical properties and corrosion resistance. For times less than 36 hours at temperatures up to 232°C little effect was observed on mechanical strength. Exposure to temperatures above 230°C was found to decrease salt spray corrosion resistance, particularly in alloy having higher residual element content. It was concluded that processing temperatures for diecast components in alloys AZ91D and AM60B be further limited to temperatures below 150° C whenever possible to insure maximum toughness and to offer a margin of safety.
1990-02-01
Technical Paper
900793
Thomas J. Ruden
Abstract Magnesium die casting alloys have the mechanical properties of metals, yet are lightweight like plastics and offer the designer a wide variety of applications. Plastics have previously been considered the most cost effective material for components that have limited mechanical requirements. Also, plastics' past history of being lightweight and easy to manufacture has made them attractive. However, in many instances, using magnesium instead of plastics offers a less expensive part that is much stronger, stiffer, just as lightweight and often easier to manufacture.
1990-02-01
Technical Paper
900792
T. Kr. Aune, D. L. Albright, Hakon Westengen
Abstract Test specimens of magnesium alloys with two, five, six and nine weight percent aluminum were produced by high pressure die casting. The results of room temperature mechanical tests were combined with data from prior investigations to provide property trends as a function of aluminum content. The strength and ductility properties of these alloys generally show opposite dependencies with a change in the aluminum content. Design engineers must therefore make material selection decisions based upon the best balance of properties available for the intended application.
1990-02-01
Technical Paper
900789
John S. Waltrip
The effective management of magnesium casting scrap involves a choice among several viable alternatives and techniques. Today's climate of diverse economic and environmental concerns preclude just a single “best approach” for all applications and locations. The various alternatives and options will be detailed along with their advantages and disadvantages. The best choice will depend on a caster's overall volume (or throughput), geographic location, existing facilities available, magnesium experience level, and several significant criteria.
1990-02-01
Technical Paper
900693
Jan A. Gatowski
Abstract A single-cylinder direct-injection diesel engine with a displacement typical of passenger car practice was built to incorporate low-heat-rejection (LHR) components. These included a silicon-nitride piston cap, an Inconel firedeck, and stainless steel portliners, all backed by air gaps. In addition, a water-cooled engine with the same geometry was tested to provide a baseline. The LHR engine was tested with three different injector spray-tip geometries to assess the sensitivity of the results to the injection system. The LHR engine was worse than the baseline engine in most respects: it demonstrated higher fuel consumption and higher NO and HC emissions, and it rejected more heat at a given operating condition. The exhaust smoke emissions from both engines were similar, with the LHR engine having a small advantage at 2000 r/min. Destructive failure of the piston cap occurred after roughly 60 hours of operation.
1990-02-01
Technical Paper
900694
Cornelius Peter
Abstract A new physical layer for automobile class B communication networks is based on simple galvanic connections. Only ten passive external components per node are needed to perform reliable data transmission inside the hostile car environment. Every single fault related to the bus will be detected and diagnosed by every node, where a software controlled logic assures continuous data flow.
1990-02-01
Technical Paper
900695
Sanjay Gupta
Abstract Controller Area Network (CAN) is a serial communications protocol that is optimized for real-time control. This paper addresses how the CAN protocol handles different functional in-vehicle communications requirements such as broadcasting of messages, handling generic- or device-specific request and response, and handling generic- or device-specific command and acknowledge. The functional requirements are elaborated by using the SAE J1922 as an example of a control and communications network and the 82526 as an example of a CAN implementation that is optimized for J1922 type of networks. The concept of a General CAN implementation is introduced; the concept can be used for other control and communications networks.
1990-02-01
Technical Paper
900696
Uwe Kiencke
Abstract The formulation of software tasks as parallel processes allows their implementation within distributed microcontrollers. The requirements for Automotive Networks to support these applications are discussed. By introduction of a locality measure, a classification of networks can be made either into interactive distributed realtime processing or into classical communication. Given a sufficiantly small locality, the physical network extension does not have an impact on the implementation. A concept i presented how to integrate process dispachting and synchronization. Based upon this concept, functions may be formulated independant of their location in a specific microcontroller.
1990-02-01
Technical Paper
900697
Rolf Isernhagen, Wolfhard E. Lawrenz
Abstract Multiplexing within motorcars, that means using invehicle- controller-networks, is a new trend to push car developement to more economics, to less pollution, to more security and to more convenience. More and more functions will be integrated into the networks which will grow larger and larger. That leads to so called structured or hierarchical networks. One main difference of controller-nets in comparison with other local area networks is, that they have to meet realtime requirements. Messages, crossing the communication lines, have to do that within a certain time to fullfill certain control functions. To support all phases of network developement, beginning with planning and ending with test and maintenance, an according toolset family - comprising Simulator, Emulator and Analyzer - has been introduced by I + ME-Company [0], [1], [14], 19]. This paper results from a joint venture between Fachhochschule and I + ME-Company in Wolfenbüttel, Germany (FRG).
1990-02-01
Technical Paper
900698
Wolfhard E. Lawrenz
Abstract Cars networked electronics represent very complex systems. Ruling this complexity is a great challenge to future cars system designers. As there are no analytic solutions to the problem only good modelling in conjunction with trial and error methods will be apropriate to attack the problem. In order to produce results in a timely and cost effective manner a new generation of System Design Tools is needed to support the system design process. In the following paper a new method for assessing the system design problems is proposed: VLSA - Virtual Leveled System Architecture. A set of Network Development Tools - Simulator, Emulator, Analyzer, etc. - is discussed as the basis for efficient system design support.
1990-02-01
Technical Paper
900684
E. H. James
An existing “phenomenological” computer model of the spark ignition engine combustion process has been used to reveal further information on flame development in such engines. A detailed flame map and pressure-time diagram ( from Ref ( 6 ) ) has been analysed to determine more precisely the 3-dimensional nature of the flame development across the CFR engine cylindrical disc combustion chamber. The conventional spherical flame assumption (centred at the spark plug) is found to be inaccurate with the extent of the deviation from sphericity varying with flame radius and compression ratio in both the vertical and horizontal (plan view) planes. The flame map provides input data in the form of enflamed volumes, heat transfer surface areas etc for the subsequent evaluation of turbulent burning velocities, mass burn rates, pressure-time diagrams etc.
1990-02-01
Technical Paper
900685
T. Chomiak, T. J. Rychter, A. Teodorczyk
A universal method to determine the geometry of burned-gas zone in SI piston engine is presented. Although the background of the method has been previously used by other authors the applicational details have not been exposed, therefore the mathematical details of the method are introduced. The short description of the computer code is given. The computer code has been divided into two files. First file, run as independent program, calculates proper set of data being later used as an input to the second file. The second file, the quick-response one, can be used as a subroutine in a quasi-dimensional SI engine cycle model and to be called at each consecutive step of calculations.
1990-02-01
Technical Paper
900686
James L. Lauer, Scott R. Dwyer
For lubrication and reduced wear of friction couples at high temperatures, such as those required by the “adiabatic” or low heat rejection engine, solid lubricants are the materials of choice. Their replenishment under operating conditions is, however, more difficult than that of liquid lubricants. Two principal approaches have been suggested: (i) reaction of the boundary surfaces with vaporized liquid lubricants [1]∗ and (ii) dissociation of a gas, stable at high temperature, at the boundary surfaces to produce a lubricating carbon [2]. Continuing work by the latter approach has demonstrated its feasibility at temperatures between 400 and 650°C with both a metallic (NiAℓ) and a ceramic surface (Si3N4 · Aℓ2O3) in a pin-on-disc tribometer for ethylene gas. Friction coefficients dropped to < 0.02.
1990-02-01
Technical Paper
900688
Zissimos P. Mourelatos
The side-load capacity of an unlubricated ringless piston assembly was calculated for a four-stroke I.C. engine for possible application to a Low-Heat-Rejection engine. A compressible flow analysis for an ideal gas was used to calculate the flow at the piston-cylinder interface. The analysis accounts for the gas inertia effect and possible choked flow. The piston side-load capacity is compared with the actual side thrust on the piston, generated through the combination of piston inertia, cylinder pressure, and connecting rod angularity. It was found that a carefully designed ringless piston can support the side load of a slider-crank mechanism during the power stroke of a four-stroke engine. However, during the remaining strokes, the load can be supported only partially.
1990-02-01
Technical Paper
900690
Jialin Yang, Jay K. Martin
Consideration of the heat transfer effects in low-heat-rejection engines has prompted further study into engine heat transfer phenomena. In a previous study, an approximate solution of the one-dimensional energy equation was acquired for transient, compressible, low-Mach number, turbulent boundary layers typical of those found in engines. The current study shows that an approximate solution of the one-dimensional energy equation with arbitrarily-distributed heat release can also be obtained. Using this model, the effects of high temperature walls, combustion, and autoignition on heat transfer can be studied. In the case of high temperature walls, the model predicts the expected behavior unless the quench distance gets very small. For combustion, the reaction must occur close to the wall for a direct effect on the heat transfer to be observed. With autoignition, instantaneous values of heat flux reach levels as high as 6 MW/m2, and oscillate in phase with the pressure wave.
1990-02-01
Technical Paper
900689
T. A. Marolewski, R. J. Slone, A. K. Jung
Significant progress has been made in the development of high temperature liquid lubricant candidates for low-heat-rejection diesel engines. Program objectives were the reduction of lubricant-derived deposits and the optimization of lubricant thermal/oxidation stability. Lubricants with established performance in high temperature multi-cylinder LHR engines were used to develop and calibrate bench tests for optimizing lubricant deposition characteristics and stability. Base stocks with optimum combinations of low deposits and high stability were selected with these bench tests. These base stocks were used in the additive selection phase of the program. Existing LHR Engine test data exemplify the need for ashless lubricants to avoid metal related deposits in the upper cylinder area. Candidates with 60% less sulfated ash than typical commercial lubricants have been formulated for single-cylinder engine tests.
1990-02-01
Technical Paper
900691
Dennis N. Assanis, Francis A. Friedmann, Kevin L. Wiese, Matthew J. Zaluzec, J. M. Rigsbee
A prototype chromel-alumel overlapping thin-film thermocouple (TFTC) has been developed for transient heat transfer measurements in ceramic-coated combustion chambers. The TFTC has been evaluated using various metallurgical techniques such as scanning electron microscopy, energy dispersive x-ray detection, and Auger electron spectroscopy. The sensor was calibrated against a standard thermocouple in ice, boiling water, and a furnace at 1000°C. The microstructural and chemical analysis of the thin-films showed the alumel film composition was very similar to the bulk material, while the chromel film varied slightly. An initial set of ceramic plug surface temperatures was taken while motoring and firing the engine at 1900 rpm to verify thermocouple operation. The data shows a 613 K mean temperature and a 55 K swing for the ceramic surface compared with a 493 K mean temperature and a 20 K swing for the metal surface at the same location.
1990-02-01
Technical Paper
900679
Thomas Morel, Michael F. Flemming, Leon a. LaPointe
A combined experimental/analytical study was made of a 2.2ℓ production engine. The objective was to characterize the performance of the engine and the pressure wave dynamics in its manifolds, and to compare the data/predictions obtained using an engine simulation program. Description of the computer program is given, providing an overview of its capabilities and of the models it contains. The data was obtained at wide open throttle, at four engine speeds from 1600 rpm to 4800 rpm. The comparisons showed the ability of the simulation to predict the major features of the wave dynamics, including the amplitude, frequency and phasing of the waves, and their tuning and de-tuning at the various engine speeds.
1990-02-01
Technical Paper
900678
M. Endo, J. Iwamoto
A numerical scheme known as the Random-Choice Method was applied to analyze the pulsating flow in a pipe with and without a nozzle. Good quantative agreement between shock locations obtained experimentally and numerically was found. Furthermore, the pressure histories of flow upstream of the nozzle show good quantitative agreement.
1990-02-01
Technical Paper
900681
Frank A. McGinnity, Roy Douglas, Gordon P. Blair
Abstract This paper outlines some developments in engine modelling techniques and details the results of an extensive validation exercise. This validation was conducted in two distinct parts: firstly, on a specially constructed rig, and, secondly, using engine test results. The test rig described was constructed in such a way as to rigourously test the theories employed. Comparisons were made between measured and predicted pressure traces and air mass flow. The predicted results are shown to be in good agreement with all measurements recorded. The performance of a complete engine simulation is also described and compared with actual dynamometer test results. The accuracy of this model is clearly demonstrated for all engine performance parameters.
1990-02-01
Technical Paper
900680
Renee T. Jameson, Patrick A. Hodgins
Manifolding for a 600cc four-stroke engine to be used to power a vehicle entered in the 1989 student Formula SAE® competition was tuned to maximize mid-range torque. Although powerful computer programs exist to analyze manifold wave dynamics, these programs are unavailable to the public; lacking access to these types of programs, Helmholtz tuning theory was chosen for use in this work due to its straightforward computational methods. Although the assumptions of Helmholtz tuning theory may not rigorously apply at high engine speeds, it was successfully used to provide design guidelines for the selection of manifolding physical parameters, and was applied successfully to increase engine output. Intake tuning of the engine with the required restrictor and single carburetor yielded torque levels of as much as 12% higher than the unrestricted stock engine with four carburetor set-up.
1990-02-01
Technical Paper
900683
Thomas Morel, Rifat Keribar
The warmup characteristics of an engine have an important impact on a variety of design issues such as performance, emissions and durability. A computer simulation has been developed which permits a detailed transient simulation of the engine warmup period from initial ambient conditions to a fully warmed up state. The simulation combines a detailed crankangle-by-crankangle calculation of in-cylinder processes and of engine air flow, with finite element heat conduction calculations of heat transfer from the gases, through the structure to the coolant. The paper describes one particular application of the simulation to the warmup of a 2.5ℓ spark ignited engine from cold start to a fully warmed up state at several speeds ranging from 1600 to 5200 rpm and loads ranging from 25% to 100% at each speed. The response of structure temperatures, charge temperature at IVC and of the exhaust temperature has been calculated and is documented in terms of characteristic warmup times.
1990-02-01
Technical Paper
900682
P. C. Baruah
A generalized computer model for analysis of multicylinder spark-ignition engines under transient conditions is presented. The model utilizes a two-zone combustion submodel based on flame propagation. It accounts for heat transfer and uses a chemical-kinetics-based procedure for the prediction of nitric oxide and carbon monoxide concentrations. Non-linear wave interactions in the exhaust and intake manifolds are considered. For the transient analysis, a vehicle model is coupled to the engine via a geartrain. The model was used to predict the behavior of two four-cylinder engines under a variety of transient operating conditions. The simulation enabled systematic analysis of the interaction between various dynamic, thermodynamic, and emission variables under transient operating conditions of the engines.