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One of the main problems experimenters are faced with in studying the diesel engine noise is the separation between the contributions of direct exciting forces, i.e. the combustion noise, and of indirect exciting forces, i.e. the so-called mechanical noise. In this paper an approach based on complementary techniques is presented, by which the combustion noise is investigated and separated from other vibrational phenomena in a running engine, analyzing the evolution of the time history as a function of engine speed and load, as well as the correlation between pressure cycles and noise. In fact a combination of techniques, such as near field intensity measurements, multiple and partial coherence methods, time-domain signal processing, can be successfully applied in order to improve the required discrimination.

This paper presents a procedure for reducing diesel engine sound levels by combining analytical models and test data. Four elements previously analyzed individually; 1) structure modal characteristics, 2) forcing functions, 3) dynamic response, and 4) acoustical radiation were combined to accurately predict changes in diesel engine sound levels due to structural modifications.

This paper describes the data acquisition and processing system of the Machines and Machine Construction Laboratory of the University of Gent. A system incorporating a minicomputer has been found to give by far most possibilities. Its flexibility, modular design, simplicity in use and computing capacity are particularly appreciated. The installation is fixed in order to have a reliable system. Analog lines for the signals and digital lines for the operators console connect the test rigs to the data logger. The calculation of the static pressure level from dynamic measurements is described as a possible application of the system.

Component groups in domestic vehicle designs with significant weight savings potential through conversion to magnesium die castings are reviewed. The criteria for part selection and basic magnesium properties are discussed. Four component groups having a number of parts meeting this study’s criteria were selected--bracketry, pumps and metering bodies, housings and transmission components. Examples of specific parts in each category are given, including estimates of cost savings or cost penalty per kilogram of weight saved.

The magnesium industry is in a growth trend thru the 1980s. The most accelerated growth will come from magnesium’s use in steel desulfurization and in die casting. It is expected that the automotive industry will be a significant part of this growth. Production capabilities will rise to meet the increase in demand through productivity improvements and expansion of existing facilities.

The purpose of this paper is to assist the designer of die castings in utilizing successful concepts early in the stages of the product design cycle. Included are guidelines for alloy selection, wall thickness, taper, draft and achievement of greater part strength. Ideas are also presented on cast-in bearing possibilities, tooling substitution, locating ejector pins, gating, corrosion protection and finishes. This practical approach to the design of castings for magnesium includes examples of successes and areas of casting design and applications to avoid.

For many years cast magnesium alloy components requiring extensive machining have found application in many industries. Unfortunately, those least familiar with magnesium continue to regard its machining as a highly dangerous undertaking. Consequently, magnesium in part because of “safety considerations” has been ruled out of a number of applications where it should have been the material of choice. This paper discusses the machining characteristics of magnesium and the safe handling and disposal of chips.

Human nose sensory properties call out two different nervous systems: the true olfactory system transfers actual olfactory information and the trigeminal system transfers irritancy. Both present specific properties and play their part in the offensive effect felt by the population and measured by a conventionnal nose panel. By using a novel olfactometer sensitive only to true olfactory excitation and not to trigeminal excitation, it is possible to afford an explanation for the lack of correlation between nose panel data and DOAS data. The irritant aspect of Diesel exhaust fumes seems thus to play a leading part in the sensory offensiveness.

The CRC-APRAC CAPI-1-64 Odor Panel was formed in 1973 to assess an instrumental measurement system for diesel exhaust odor (DOAS) developed under CRC-APRAC CAPE-7-68 by Arthur D. Little, Inc. Four cooperative studies were conducted by nine participating laboratories using common samples. The objectives of these studies were to define the DOAS system variables and to validate and improve the sampling and collection procedures. A fifth study, serving as a review of each analysis step, showed that analysis of common derived odorant samples could be conducted within acceptable limits by the participating laboratories. Three in-house sampling system design and operating parameter studies were conducted simultaneously with the cooperative work. The combined findings from the in-house and cooperative studies led to a tentative recommended procedure for measuring diesel exhaust odor.

An analytical technique has been optimised for the measurement of the concentrations of diesel exhaust odorants. Application of this technique to combustion bomb studies shows that preflame reactions with diesel fuel produce high concentrations of odorants. The effects of engine variables on exhaust odorant concentrations are presented for direct and indirect injection engines. Analysis of these data shows that diesel exhaust odorants are produced from three sources: (a) the fuel-lean mixture produced during the ignition delay period, (b) fuel emptying from the nozzle sac volume of direct injection engines after injection, (c) a fuel-rich source which becomes significant at high load. The practical measures for control of odorants are outlined.

The data from a round-robin program, run by the X-ray Division of the SAE Fatigue Design and Evaluation Committee to evaluate x-ray techniques for measuring retained austenite, have been studied. This program involved the measurement by twenty-three companies of four specimens containing 0–40% retained austenite. The results show that laboratories using proper techniques can achieve an interlaboratory standard deviation of less than 4% retained austenite at the 40% level and less than 1.5% at the 5% level.

X-ray residual stress measurements were made near the fatigue crack tip in round-robin specimens by the X-Ray Fatigue Division of the SAE Fatigue Design and Evaluation Committee. Steel specimens, furnished by the Cumulative Fatigue Damage Division from their fatigue program, were of two strength levels and either constant-amplitude or program loaded. Results showed the need for more work in establishing the small beam x-ray technique. Residual stress patterns ahead of the crack correlated qualitatively with the Rice model, and higher compressive stresses in the higher strength material correlated with increased resistance to crack propagation in the fatigue program. Stresses measured across the crack also reinforced the Elber crack closure concept.

Electronic devices have been markedly improved in recent years and in particular, electronic control is most predominant, thanks mainly to advances in LSI technology. Car audio units, for example, are not an exception. The industry trend is to develop more electronically controlled car tuners and tape decks. The electronically controlled tape mechanism is being applied to car audio at a rapid pace and it will result in reducing the dashboard space required for car stereo. Due to reduced space available, automotive designs call for a more compact, thinner chassis, higher-performance mechanism for car audio systems. On the other hand, pricing competition is keen among more advanced devices, so there is an imminent need to minimize the cost of the electronic controlled tape mechanism. Thus, the ultra compact, full logic cassette mechanism has been developed to meet the needs of Auto Sound Design Engineers.

A theoretical study of distortion due to multipath propagation is presented. For application in an antenna-diversity system a distortion detector has been developed which indicates not only multipath distortions as a result of great time delays between superimposed waves but also indicates noise interference as well as co-channel interference and nonlinear distortions as a result of large signal interference. Main feature of this detector is its extremely short detection time of 25 µs which is limited to the group delay time of the IF-filters of the receiver. On the basis of this fast indicating distortion detector the efficiency of antenna-diversity is investigated as a function of the number of implemented antennas among which that with the best signal is selected. The results show that the improvement factor increases considerably by the number of antennas applied.

This paper describes a digital Phase-Locked Loop (PLL) frequency synthesizer designed for AM/FM radios. The synthesizer utilizes an upconversion technique which enables tuning of both the AM and FM bands using one Voltage Controlled Oscillator (VCO) operating between 98 and 118 MHz. The scheme reduces the cost associated with the AM front end as a result of eliminating three matched varactor diodes and the labor involved in the five to six adjustments for alignment.

Ever since FM radios became popular in automobiles, the phrase “well that's one of the limitations of FM” has been heard with respect to the annoying noises and distortions associated with mobile VHF reception. This paper deals with identification of the causes of these disruptions and minimization of their effects. FIFTEEN YEARS AGO most markets were dominated by AM radio stations. While FM stations existed nearly everwhere in the U.S. at that time, their limited acceptance did not make quality reception in a moving vehicle the highest priority. Since that time, FM radio has grown in popularity to the point where, in most markets, FM stations hold many of the top spots in the ratings. Because of this, customers are no longer satisfied with “that's one of the limitations of FM”. With this in mind, most radio receiver and IC manufacturers have developed circuitry to eliminate or at least minimise the effects of these conditions.

The origin of the car radio is, like that of the automobile, an obscure one. This paper attempts to describe its early-history in the United States and Western Europe, briefly describing at the end some recent developments made possible by modern technology.

This paper attempts to open a dialogue between broadcasters and receiver manufacturers regarding standardization of transmitter and receiver frequency response to increase consumer satisfaction with AM. The problems, politics, and economics of the broadcasters are discussed. A family of pre-emphasis curves and a single “quasi-wideband” de-emphasis curve are presented. The authors believe these to be the most effective compromise between the “wideband” and “narrowband” camps. These curves permit the bandwidth of the receiver to be substantially widened without introduction of unpleasant stridency or other undesirable effects. Simultaneously, they are highly effective in improving the perceived high frequency response of existing narrowband radios. Together, the pre-emphasis and de-emphasis provide “quasi-high-fi” audio which can sound very similar to FM to the consumer listening in the car.

The regeneration behaviour of the ceramic diesel particulate filter is investigated. It is found that regeneration of the vaporizable components absorbed by the soot is promoted. The addition of manganese leads to a second conversion maximum. When additives are used, ceramic filters pass through a “running-in” phase. As regards Mn emissions, emissions of Mn oxides of all valency stages as well as Mn-SO4may occur. These emissions amount to a maximum of 2.2 µg Mn/mile. Dispersion calculations for worst case situations have shown, that the maximum Mn-immission caused by using manganese fuel additives is still within the level of present immissions. Families of characteristics are shown for emissions of the diesel particulate filter for particles and NOx. By using filters with higher efficiency the particulate emissions may fall below 0,08g/miie. The particulate filter and the additive metering system have proved satisfactory in a field test in the US.

Changes in the coating structure of four hot-dip coated steels (Type 1 aluminized steel, 55%Al-Zn alloy coated steel, 5%Al-Zn alloy coated steel and galvanized steel) due to heating and their subsequent corrosion resistance towards muffler condensate were investigated to evaluate their basic performance as automotive muffler materials. Test methods used included continuous or cyclic heating and a muffler condensate test. Zn-Al alloy coatings are converted into the mixture of locally formed Fe-Zn intermetallic compounds outbursts and relatively uniform Fe-Al intermetallic compounds layer by heating at temperatures above 400°C. The former compounds become the initiating spots for the local corrosion of steel substrate with muffler condensate. Micro crevices, formed on 55%Al-Zn alloy coating by cyclic heating at around 300°C, accelerate muffler condensate corrosion.