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Several characteristics distinguish the combustion in large-bore engines from ordinary automotive engines; namely low rpm and associated long combustion duration, natural gas fuel, multiple spark plugs, lean (Φ ≈ 0.8) operation, substantial unmixedness due to direct gas injection during compression, and low surface to volume ratio. In order to better appreciate the effects of these factors on NOx formation, a phenomenological model of combustion in a 20-inch bore two-cycle natural gas engine is described. The model accounts for random “unmixedness” of the initial charge, stratification, and temperature gradients arising from successively burned zones. Predictions are compared with experimental data for the effects of variations in timing, fuel-air ratio, stratified charge, EGR, and turbulence.

The safety of a motor vehicle transport system requires examination of the total system to assure its compatibility with human behavior capability. A lack of time available for driver decision and response to unexpected hazards as well as traffic control directives is a critical deficiency present in roadway operations.

Annual projections of the amounts of metallic and non-metallic materials available for resource recovery from the average junk car in the time period 1974 through 1995 are presented. The amounts and the composition of the ferrous and non-ferrous metals and the non-metallic material derived from the recycling of junk cars will undergo large changes in the future due to the material changes adopted in the manufacture of current and future automobiles. Implications important to the recycling industry due to these changes are identified and related research and development programs which need addressing are discussed.

In order to improve the reliability of oil seals in practical use, it is considered that further basic investigation for maintaining good sealing characteristics of seals are necessary. However, the result of analysing phenomena in oil seals which has caused the oil leakage in the market shows that about 60 % of oil leakage is caused by the seal installation to housing bore or shaft, about 30 % thereof by unsuitable operating condition and remaining 10 % by the design of oil seals. From the point, oil leakage troubles and their countermeasures on oil seals for automotive application are discussed.

The single-chip microcomputer is very appropriate for automotive control applications. Selecting a product, designing with it, and moving it into production needs to be carefully planned to avoid unexpected costs and delays. Included, as an appendix, is a glossary of buzz words, used to describe single-chip microcomputers.

A new microcomputer family has been designed with the intent of minimizing system parts count by integrating typical system requirements “on chip.” The tendency toward over specialization has been avoided by increasing the microcomputer family members to allow system upgrading with minimum overkill. The S2000 microcomputer family is an example of next generation low cost single chip microcomputers designed with system applications in mind.

The microcomputer technology has been improving rapidly in terms of processing power, cost, size and reliability. It has now become cost effective in the automobile and its applications within the automotive manufacturing system have been rapidly increasing. This paper discusses some advanced concepts for automotive controls. It explains how the speed and power of the chip computer is utilized for real time integrated controls and how loops are closed for adaptive controls. The worrisome question of how the service industry will handle these new controls is addressed with emphasis on the computer's ability to diagnose its own control systems. Finally, the rapidly spreading use of microprocessors in the automotive manufacturing plants is described, and the resulting opportunities in mass production functional control are indicated.

The application of a bonded-in P.T.F.E. bearing material liner to the lip of an oil seal has dramatically increased the seal's ability to function in high-speed, pressure, or heavily-contaminated applications. This has resulted in relatively inexpensive solutions to several difficult sealing problems.

Nitrile, silicone and fluorocarbon polymers were evaluated in square and round cross-section rings using stress relaxation to determine retained sealing force under static conditions at elevated temperatures. Stress-relaxation data were combined with a stress-decay formulation to predict the life of the seals while examining the effect that squeeze, cross-sectional shape, and state of cure have on performance. Regardless of material used, square cross-section rings exert a greater sealing force than their round counterparts for a longer time period. This improvement in seal life is due to cross-sectional shape and state of cure.

Valve stem seals are important to control consumption of lubricating oil for engines and to prevent an air pollution problem by unclean exhaust. It is required for valve stem seals to have stable characteristics of a controlled oil leakage related to frictional characteristics. In this papor, the concept of designing valve stem seals which possess the above characteristics have been discussed by applying an inverse problem of hydrodynamic lubrication.

RTV silicone formed-in-place gaskets are used throughout industry as a replacement for preformed cork, paper, and rubber gaskets. The RTV silicone rubbers offer a unique property, performance and cost profile that make them ideally suited for formed-in-place gas-keting applications. The concept is rather simple. A thin bead of paste consistency RTV silicone is applied to one of two mating surfaces. When assembled the RTV silicone flows between them filling all voids and irregularities. The gasket cures to a solid silicone rubber gasket that has excellent flexibility, thermal stability and fluid resistance.

The flowfield in a motored axisymmetric reciprocating internal combustion engine is calculated as a function of space and time throughout the complete four stroke cycle, by means of a computational procedure which solves the governing partial differential equations on a mesh which expands and contracts with the motion of the piston, using an implicit, iterative, finite-difference scheme. Numerical results are presented for laminar and turbulent conditions. In the last case, two additional conservation equations, the kinetic energy of turbulence and its dissipation rate, are solved. In both cases, an axisymmetric configuration and a centrally-located valve, which opens and closes instantaneously have been studied. The results corresponding to the laminar case show the formation of a large vortex during the intake stroke. As the fluid is compressed, the intensity of the vortex decays, and its decay persists throughout most of the expansion stroke.

A model has been developed for simulating the combustion in a three-valve stratified charge spark ignition engine. The conservation equations for mass, momentum, chemical species, and energy are numerically integrated for a one-dimensional flame using an empirical model for turbulent diffusivity. The chemical reaction of the fuel and air is modeled using simple kinetics in a one-step reaction and experimentally determined ignition delays are used. Nitric oxide emissions are calculated using a simple Zeldovich model with steady state atomic nitrogen and equilibrium atomic oxygen. Effects of various assumptions and parameters in the model are discussed and comparisons with experimental data from a single-cylinder engine are presented.

One-dimensional unsteady analysis of turbulent flame propagation has been used to determine the heat release rate. This model considers the combustion chamber geometry, piston face profile and spark plug location. The chemical kinetic analysis has been used to predict NO emission level as function of time and chamber position. Equilibrium calculation of CO emission level at the end of combustion process has been performed. A computer program has been developed to solve the flame propagation and kinetic equation. The results have been verified by comparing the experimental data such as flame velocity, combustion duration, mass fraction of burned gas versus crank angle, rate of pressure rise and emission levels of NO and CO with those predicted by the model.

A combustion bomb has been used to compile a comprehensive set of well-characterized experiments which may be used to validate computer models of IC engine combustion. Extensive variations of experimental conditions allow the kinetics and fluid mechanics in the codes to be independently evaluated. Thermodynamic properties of the swirling, uniform precombustion mixture are characterized by measuring pressure, temperature distribution (with thermocouple probes), velocity/turbulence (with laser Doppler velocimetry) and equivalence ratio. Combustion diagnostics include pressure histories, high-speed laser shadowgraph filming, flame position determined with a laser refraction technique, and time- and space-resolved density using laser Rayleigh scattering.

The vibration transmission in engine structures has been studied to develop analytical models which predict changes in the noise related vibration of the engine as a function of design changes in the engine components. The models are based on vibration measurements made on non-running engines. This paper outlines the basic procedures for the necessary vibration measurements and for the development of the models. Two examples are given of models developed for different vibration transmission paths in different engines. The vibration transmission from the cylinder pressure to the engine block is modeled for a 4 cylinder DI diesel engine and compared with a simulated vibration transmission measurement with the engine not running. The vibration transmission from the engine block to covers and shields is modeled for a 6 cylinder in-line diesel and compared with the measured vibration transmission with the engine running.

The study of unsteady gas exchange processes in the intake and exhaust systems of an internal combustion engine is presented in this paper. A finite difference scheme is used for solving the equations defining these systems. The transient properties like the pressure, temperature and velocity in these systems are computed by the present scheme and are compared with the results obtained using the pressure measuring devices and an ultrasonic instrument which can simultaneously measure the gas temperature and velocity.

The vibration mode analysis of an automotive diesel engine for the purpose of obtaining a lower level of noise emission will be described in the paper. Since the noise emission corresponds to the vibration of certain components of the engine, the vibration of engine structure was analyzed in several running conditions. Vibration distribution shows a natural vibration mode which was proven by coincidence with the result obtained by modal analysis. When measurement of the vibration mode is very difficult due to the high mechanical impedance and especially the big damping factor of the component, a new method of vibration mode analysis for the engine component excited by cylinder pressure was proven to be useful. Some attempts for controlling the noise and an analysis of damping effects will also be described in the paper.

A technique of calculating the evolution of turbulence during the combustion phase of a reciprocating engine cycle is presented. The method is based on a local linearization of the full non-linear equations of motion. It is valid when the turbulence is distorted more rapidly by the changes in mean flows than it interacts with itself. The theory requires as input strain rates of the deterministic mean motion, and the initial state of turbulence. Calculations are presented for the particular case of a cylindrical chamber geometry. In the burning process it is assumed that the spark plug is located on the cylinder axis and the strain field is that established by the flame front. The theory calculates the turbulence parameters during the combustion period. Combustion rates, and durations, as a function of equivalence ratio and the initial turbulent and thermodynamic conditions.

Data from 101 front seat automobile occupant fatality crashes that the authors had investigated were reviewed along with 70 front seat automobile occupants who had the more severe (AIS 3, 4, or 5) level injuries who did not die. The effectiveness of the lap belt alone, lap-shoulder belt, air bag alone, air bag with lap belt, and the passive shoulder belt were made. The estimates reveal that none of the restraints would have prevented 42 to 51 of the fatalities. The air bag with lap belt, and the lap-shoulder belt system, have the highest effectiveness for reducing fatalities (AB+LB, 34%; LB+SH, 32%). The air bag with lap belt has an effectiveness of 68% in reducing the more serious injuries with the lap-shoulder belt nearly as equal (64%). NHTSA's fatality reduction estimates are excessively high and overly optomistic compared to ours, but theirs are noticeably lower for serious injury reduction than are ours. Comparisons with other restraint effectiveness studies are also made.