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With digital Fast Fourier Transform (FFT) analysis, which enables rapid identification of resonant frequencies, mode shapes, and modal parameters, a designer can optimize viscoelastic damping material applications for real structures. This paper will discuss the use of FFT analysis in the design of damping applications for eliminating resonant high cycle fatigue in specific light weight structural components.

Structural Dynamics Research Corporation has been involved in the development and application of advanced testing and analysis techniques for improving the vibration performance of vehicles for over ten years. Techniques such as narrow band spectrum analysis, modal testing, and building block simulation have been the topic of several technical papers, 1,2,3,4,5,6 and have been widely accepted by the automotive industry as useful techniques for vehicle vibration improvement. In this paper, the authors describe a new method of application of modal analysis and building block technology which has been made possible by advances in minicomputer software. Examples of recent projects performed by SDRC* are described, which illustrate how a test engineer can identify and evaluate various fixes to a vehicle vibration problem utilizing a minicomputer based hardware-software system in his laboratory.

A program was initiated to improve the emission and fuel economy measurement accuracy and test cell to test cell correlation. Improvements were made to the Constant Volume Sampling System, electric dynamometer, instrument calibration ranges and system checks were initiated to improve the accuracy of the bag emissions, modal emissions, calculated and measured fuel economy. Unique emission and fuel economy problems associated with gasoline and diesel testing were studied and resolutions effected when possible.

A major problem in Vehicle Exhaust Emissions and Fuel Economy Testing has been the variability in the measurements. An extensive test program was undertaken to identify and quantify the sources of variation. The test program was designed using four test vehicles on five CTE-50 Clayton Dynamometer cells whereby four repeats for each combination were provided for a total of 80 CVS-C/H Emissions and F.E. Tests. During each test a total of 23 test variables were monitored and recorded in real time. Nine other variables were also observed for a total of 32 variables: 5 vehicle related variables, 16 engine related, 4 dynamometer variables, 3 driver related, and 4 environment variables. The paper reports various results of this experiment and describes an instrumentation package that was developed for “on-line” data recording.

The microprocessor is only one component of a larger system called a microcomputer. The microcomputer is a component used to control a larger system, product, or instrument. Information is transferred between these various parts and systems via interfacing devices. The function of these devices and interfaces and the nature of the information transferred are described.

The effect of soaking temperature on exhaust emissions and fuel consumption was investigated using a variety of automobiles representing different emission control levels including diesel engine powered vehicles. Tests were performed at soaking and ambient temperatures of 20°C down to -20°C (68°F to -4°F). It was found that emissions and fuel consumption are dependent on soaking temperature. Hydrocarbon and carbon monoxide emissions were higher at -20°C than at 20°C: hydrocarbon (HC), 1 to 4 times; carbon monoxide (CO), 1 over 3 times. The smallest increase of 1 to 1.04 time belonged to vehicles equipped with diesel engines. Nitrogen oxides (NOx) emissions were higher or lower at -20°C than at 20°C depending on emission control technologies -0.75 to 1.11 times. Analysis of the data has indicated that HC and CO emissions from the cold start phase of the Federal test were the most sensitive to soaking temperature.

This paper summarizes the emission and fuel economy data obtained when ten dissimilar cars were run using the 75 Federal Test and the Highway Fuel Economy Test Procedures. The soak and test temperatures used for the modified standard procedures varied from 0 to 110°F. The influence of the cars' air conditioners was also determined. The purpose of the program was to determine how well the emission control equipment designed to be effective at normal FTP test temperatures would work at temperatures ranging between 0 to 110°F.

Mechanical and automotive engineers cannot escape the impact of the microprocessor. Fortunately, the microprocessor and its related parts can be well understood without an extensive knowledge of electronics. The functions of the parts of a microcomputer and their interactions are presented. The microprocessor, clock, memory, and input/output section are defined and discussed. The relationship of binary and hexadecimal numbers to machine language and assembly language programming is made clear. This information will enable the engineer to better understand papers, presentations, and sales literature related to microcomputers.

A vehicle has been built to incorporate a number of fuel economy improvement components with an Electronically Programmed Engine Control (EPEC) system. The vehicle system was optimized for fuel economy within driveability and emission constraints and provided a 12.5 percent improvement in fuel economy on the combined FTP tests. An evaluation of the fuel economy benefit of the combined system and individual components is presented.

Volkswagen had a contract with DOT-TSC to generate a data base which would yield a consistent set of information about the factors affecting fuel economy of engines especially the impact of different emission standards and their influence on unregulated emissions and consumer attributes as well. Main important standards were 0.41/3.4/1.0 and 0.41/3.4/0.4 gpm HC/CO/NOx. It was found that for setting engineering goals at least a factor of 0.5 was necessary regarding HC and CO, and a factor of 0.25 regarding NOx. The concepts achieving engineering goals mainly consistent of Volkswagen engine families are described. All fuel economy, emissions, noise, startability, driveability, acceleration performance, and gradeability data obtained with these engine families are included.

The effects of fuel composition and additives (antioxidant and detergent) on intake system cleanliness have been studied using Japanese automobile engines equipped with EGR systems. The following conclusions were obtained. Cleanliness of the intake system (carburetor and intake manifold) is influenced remarkably by the fuel characteristics, namely the olefin content and the type of antioxidant. The detergent gives a large improvement in the cleanliness of carburetors and intake manifolds, but shows little or no effect on the intake valves. A carrier oil used together with the detergent does reduce the deposit formation especially on the intake valves. The increase of the aromatic content appears to augment the deposits on the cylinder head.

This report covers work undertaken at the U.S. Army Fuels and Lubricants Research Laboratory to develop a laboratory bench procedure for the evaluation of dispersant-detergent gasoline additive effectiveness used for the control and/or inhibition of carburetor and engine intake system deposition. The development of the synthetic crankcase off-gas liquid in Phase I of this project has made it possible to develop a bench procedure that correlates to actual engine results in: 1. The carburetor throttle plate and throat area, 2. The induction system (port and valve areas), and 3. Additive effectiveness. The apparatus is simple in design and operation, and provides the advantage of evaluating both carburetor and intake deposits simultaneously.

The paper critically reviews the requirements for internal combustion reciprocating engines to meet present and future noise legislations according to their specific road vehicle applications. It reviews the significance of the vibration characteristics of structure elements in relation to the combustion systems employed and attempts to identify the importance of the balance between mechanical and combustion induced noise in engines falling into specific categories.

IN THE YEARS FOLLOWING the introduction of the 4-cylinder diesel engine for the Volkswagen Rabbit 5- and 6-cylinder diesel engines were developed for passenger cars and light duty trucks. As in the 4-cylinder version these engines employ the swirl chamber process. They are in-line OHC configurations with bucket tappets and with the valves being parallel to the cylinder axis. Cylinder volume is 400 cm3. For the passenger car version power output of the 5-cylinder engine is 50 kW, and 60 kW for the 6-cylinder engine both at a rated speed of 4800 rpm. Cast iron cylinder blocks and aluminum cylinder heads are used. The paper describes the basic design, development highlights and gives the performance characteristics such as of power, durability, emissions and fuel economy.

Recent admendments to the Federal Motor Vehicle Safety Standard No. 108 open new markets for headlamps of sealed construction utilizing the higher efficiency halogen regenerative cycle light sources. The terminology related to halogen-cycle lamps and the chemical/thermal cycle phenomena are explained for the automotive lighting engineers and references will allow researchers to review previous work. The history and practical applications of halogen lamps is traced from 1912 to the present halogen sealed beam headlamps that are available on numerous 1979 model automobiles. The new halogen sealed beam headlamps may be the initial step toward evolutionary new headlamp designs, involving new materials and new manufacturing processes to meet the changing needs of the automotive industry and society.

A new blade fuse has been developed for low voltage (32 volts or less) automotive applications. Due to its smaller size and greater reliability it offers many advantages not previously available with cartridge type fuses. To insure proper interfacing in the automobile's electrical system, it is important to understand what a fuse is, what are its performance characteristics and how are they evaluated, and how the typical vehicle environment can affect fuse performance and to what extent. Only with such information can the circuit designer optimize his selection of the correct fuse for safe, inexpensive and trouble-free circuit protection.

The effects of unleaded gasoline properties on the formation of carburetor deposits were studied by analyzing data from six field tests and by conducting a laboratory engine test program which investigated a wide range of gasoline properties. The results showed that increasing sulfur, nonbasic nitrogen, olefin, and existent gum contents and 10% and 90% evaporation points increased carburetor throttle body deposits. The most practical and economical way to control carburetor deposits is with the use of an effective deposit control additive. Such an additive can also clean up and keep clean critical areas of a new design variable venturi carburetor. Problems of measuring fleet fuel economy are also discussed.

A Couette viscometer is described which is capable of measuring the viscosity of engine lubricants at a temperature of 150°C and shear rates from 105 to 106 s-1. A novel feature of the instrument is the introduction of an electrical capacitance method for measuring the size of the annular gap. Operating procedures are discussed in detail and mathematical corrections are established for dealing with temperature rise in the test sample. Viscometric data for some single-grade oils and multigrade oils are presented.

Over the years, plastic components have gradually been adopted where applicable in the mechanisms of windshield wiper systems - from motors to wiper blades. This paper describes the changes and thereby illustrates typical applications of the use of plastics in automotive and commercial vehicle mechanisms.

The high temperature permanent and temporary viscosities of oils run in a diesel injector shear stability test were compared with similar data for two European laboratory engine tests. Low shear rate permanent viscosity losses for oils run in selected European cars were compared with laboratory data. Shear stability as commonly determined by the diesel injector test and low shear rate viscosity measurements does not permit adequate assessment of the shear stability of engine oils. The viscosities measured at high shear rates and high temperatures appear to provide a more useful dimension in the characterization of oils than do standard viscosity measurements. Temporary viscosity losses tend to be larger than permanent viscosity losses.