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By utilizing high voltage diodes, a special ignition coil, and a special electronic module, a distributorless ignition system (DIS) having solid state high voltage distribution has been designed and constructed. The ignition coil has two opposite polarity high voltage outputs that alternate in phase upon each firing. Each high voltage terminal is connected to two spark plugs through a pair of high voltage diodes that are arranged in back-to-back polarity. The basic DIS package is suitable for igniting a four cylinder engine. DIS has significant advantages in the areas of RFI emissions, packaging, and “rotor registration”.

Preliminary test results are presented for an S.I. engine which used a focused laser beam and conventional spark ignition as ignition sources. The results show that for a steady running single-cylinder engine with MBT spark timing and fixed throttle position, engine performance and efficiency are improved, extension of the lean limit of operation by 5 air-fuel ratios is possible, and more NO is produced with laser ignition. The effects of EGR are also examined. The CO and HC emissions are essentially the same. With the laser, the spark location was found to have little effect on performance except when it was moved near the combustion chamber wall. The minimum laser pulse energy required for steady engine operation seems to be dictated by the minimum energy required to achieve breakdown of the laser pulse in air at the same pressure.

Scanning electron microscopy and microchemical analyses were conducted to determine the electrode erosion mechanisms of two different spark plugs, platinum-tip and nickel-alloy plugs, tested under various environments. The electrodes were eroded differently depending on the electrode materials and the operating environments. In bench test performed in a dry air pressure chamber, ejection of small molten particles from center electrodes and vaporization loss of side electrodes were the predominant erosion processes. In vehicle tests, the erosion mechanisms varied with the additives in the fuels used. Oxidation of base metal and electrode corrosion by fuel residues were the common erosion processes observed.

A squeal model for a proprietary fixed caliper disc brake is proposed which includes mass and stiffness parameters and allows for variations in the contact configuration of the pad and piston. The predicted and observed trends in squeal behaviour are shown to be in good agreement.

Previous investigations using a single-pin-disc system have suggested that the mechanism of disc brake squeal is explainable in terms of a geometrically induced or kinematic constraint instability. The experimental results and theoretical analysis to be presented further endorse this idea while demonstrating that interactive coupling effects using a two-pin system can produce both enlarged and reduced regions of noise generation. Two steel pins independently supported on flexible cantilevers are pressed into contact with a steel disc which rotates at a constant speed. Assuming the system to be undamped and having linear characteristics, the pin sub-systems are each modelled to have three degrees-of-freedom and the disc to have a single degree-of-freedom. The unstable regions are shown to depend primarily on the orientations of the pins to the disc surface.

Analyses of squealing disk brakes generally show main frequencies from 1 to 10 kHz. On a test stand holograms exposed by time average and double-pulse techniques are recorded from various types of disk brakes. Photographs of reconstructions from those holograms display a vibration pattern in a simple topographical map of fringes, which represents contours of equal vibration amplitudes on the brake components: That would be i.e. yoke-type or fist-type callipers, brake pads and brake disk. Holographic Vibration Analysis is a useful method for looking at these small vibration amplitudes to understand different mechanisms of coupling. Also it is possible to localize vibration sources in squealing disk brakes.

Better methods of analyzing combustion dynamics in internal combustion (IC) engines are needed as a consequence of increasing demands for greater thermal efficiency, lower pollutant output, and improved fuel flexibility. In response to these needs, both improved diagnostic devices and computational techniques are being developed. Together, these developments may lead to a more detailed understanding of the combustion process. In particular, advanced numerical simulation techniques, may ultimately produce the capability of calculating both the spatial and temporal evolution of the fuel/air mixture for the IC engine cycle as well as the combustion process itself. During the last several years, a number of publications have appeared, describing both one-dimensional and two-dimensional, transient computer codes which indicate steady progress toward the goal of a computational tool which is capable of making performance predictions at a reasonable cost.

A theoretical model has been developed for calculations of the evolution of fuel injected into internal combustion engine chambers. Fuel injection in the form of a gaseous jet and in the form of a liquid droplet spray are considered. The model uses the basic equations of conservation of mass, momentum, and energy in both the gaseous and liquid phases. Applications in two dimensional symmetry of the gaseous jet form of the numerical model are described in stagnant and swirling air flows. The liquid droplet spray model, including coupling between the droplets and the gas phase medium, is described. Applications of the two phase model are described for the case of axially symmetric injection. Finally, the liquid spray model and the gas jet model are applied to the same conditions, leading to a general assessment of the ranges of validity of the gas jet model.

The trade-off between engine operating efficiency and NOx emissions in the prechamber three-valve stratified-charge engine is examined in a series of parametric studies using an improved model developed at M.I.T. (1). Engine geometric, operating, and combustion parameters are varied independently and the effects on brake-specific-fuel-consumption, exhaust temperature and brake-specific-NO observed. Parameters chosen for study are: timing of the start of combustion, overall air-fuel ratio, prechamber air-fuel ratio at the start of combustion, main-chamber combustion duration, prechamber size (prechamber volume and orifice diameter), EGR (in main and prechamber intakes), and load. The results quantify trade-off opportunities amongst these design and operating variables which are available to the engine designer.

This paper describes the development of a mathematical model for the compression, combustion, expansion, exhaust and intake processes of a three-valve stratified charge engine. After calculating the mixture formation at the end of compression process, a simple combustion model was developed to compute the gas temperature, gas pressure and the rate of formation of NO and CO at each crankangle, using basic energy and reaction kinetic equations for both the auxiliary and main chambers. The evaluation of the model was carried out by comparing the computed and experimental data. A satisfactory correlation was observed between them.

This paper reviews 20 years of data dealing with customer reaction to gasoline octane quality. Four technical studies and one marketing survey are covered. An analysis of the data shows that customer reaction to engine knock has not changed during this period. Agreement among three of the technical studies was good. ΔRON, the difference in Research Octane Number requirements between trained observers and customers, varied from 3.0 RON at the 50th percentile satisfaction level to 1.7 RON at the 90th percentile satisfaction level. The marketing survey shows that these values of ΔRON are a good measure of the number of customers in the marketplace who consider knock to be a problem. The fourth technical study measured ΔRON to be at least twice as large as the values in the other studies. This discrepancy is traced to the design of the questionnaire used to evaluate customer reaction to knock.

Octane requirements of late model vehicles were determined by trained knock raters and compared with those determined by customers. Average differences of independent distributions of customer and rater requirements were about 3 Research Octane Numbers/2 Motor Octane Numbers at part-throttle and 6 RON/4 MON at full-throttle and maximum octane requirement conditions. Five percent of the customers objected to knock when their cars were operated on fuel matching rater requirements, while 50 percent objected when using fuel 6 RON/4 MON lower. Another program is planned because differences between rater and customer octane requirements were greater than expected.

The influence of driving procedures and extraneous car noise on perception of engine knock has been studied with late model cars. Year to year changes in reports of knock by both customers and raters and changes in octane requirements were also reviewed. Customers generally accelerated cars less vigorously and tended to perceive knock less often than raters. However, in cars that had maximum octane requirements at part-throttle, customers perceived knock about as frequently as raters. Octane requirements, as determined by raters, were reduced by about 2 Research Octane numbers when the car radio was turned on and the windows closed. Both customers and raters reported more knock with 1975-1977 model cars than with earlier models. Since 1975, octane requirements of certain car models tended to be adjusted to the octane quality of available gasoline.

The Acceleration Performance Instrument was developed to reduce the manpower and equipment required for vehicle performance testing. Using only a single person and test vehicle, data may be obtained in five operating modes. The instrument prints time-to-speed and time-to-distance information on paper tape during vehicle acceleration and coastdown. Acceleration testing may utilize a standing or moving start at any speed up to 99 mph. Vehicle coastdown data may be obtained between any two speeds and is useful for determining aerodynamic drag and rolling resistance. Special modes provide Federal consumer passing information without the use of additional personnel or vehicles. The instrument requires the addition of a 5th wheel and an AC power inverter for operation. THE ACCELERATION PERFORMANCE INSTRUMENT was developed to meet the demands of increased performance measuring capability using reduced manpower and vehicle time.

The preparation and testing of polyurethane foam for seating applications is described. Designed experimentation utilizing low vapor pressure isocyanates was used to optimize conditions. Components and conditions which produced the most satisfactory product are noted.

Problem areas of general applicability in the field of detection of knock in commercial engines are discussed. These include (a) the expedients adopted to reduce the effect of noise on the sensibility of the measuring instrument, (b) the characteristics of the pass-band electronic filter employed in this type of instrumentation and possible distortion effects, (c) the type and mounting of the transducer employed, with emphasis on devices outside the combustion chamber, and (d) the interpretation of the phenomena as detected with the devices used and its relation to the energy released from knock and the danger of mechanical damage.

Spark plug pressure transducers were used in an experimental study to determine the suitability of such devices for measuring indicated work in internal combustion engines. Three piezoelectric transducers were studied to compare response of the spark plug unit with a reference device; the comparative data were obtained from a single-cylinder engine fitted with both a flush mounted pressure transducer and a spark plug pressure transducer. Signals from both transducers were recorded simultaneously, combined with a volume function, and analyzed for output differences. The volume function used in the calculations of indicated work was generated about an angular reference point recorded with the pressure data. Typically, indicated work calculated from the spark plug pressure transducer was found to be from -3.2 to +7.6% of that calculated from the flush mounted pressure transducer. The sources of inaccuracy associated with the spark plug pressure transducer are discussed.

A new method which automates collection and processing of brake test data has been developed to replace the more traditional methods of using an observer or Ultra Violet recorder. This method improves accuracy and also substantially reduces cost and can be applied to vehicle or dynamometer testing. Improved versions of the instrument would allow investigation of transient conditions.

A new knock intensity meter, based on a criterion which correlates knock intensity and kinetic energy associated to knock-typical pressure oscillations, is described. Operating principles, electronic chain, as well as the method that led to an instrument able of accurate measurements (both on laboratory engines and on automotive engines at high speed) are analysed.

A Microcomputer Based Eight Channel Data Acquisition System has been developed for customer correlation and routine vehicle field testing applications. The eight channel system includes a self-contained signal conditioning system designed for a variety of transducer types and data frequency requirements. Calibration, signal gain, and channel zero offset adjustments can be performed under software control. The microcomputer system is based on a Motorola M6800 microprocessor and a non-volatile core memory module. The paper describes the design, development, field performance, and data processing characteristics of the system and presents specific automotive applications and field test results.