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Viewing 1 to 30 of 88
1990-10-01
Technical Paper
902085
Eric W. Schneider, Daniel H. Blossfeld
A radiometric method has been developed for the determination of camshaft wear during engine operation. After a radioactive tracer is induced at the tips of one or more cam lobes by the technique of surface layer activation, calibration procedure are performed to determine the amount of radioactive material remaining versus the depth worn. The decrease in γ-ray intensity measured external to the engine is then directly related to cam lobe wear. By incorporating a high-resolution detector and an internal radioactive standard,measurement accuracy better than ±0.2 μm at 95% confidence has been achieved. Without the requirement of engine disassembly, this method has provided unique measurements of break-in wear and wear as a function of operating conditions. Because this approach requires only low levels of radiation, it has significant potential applications in wear control.
1975-02-01
Technical Paper
750028
Russell V. Fisher, James P. Macey
A general purpose data acquisition system has been developed which converts analog data to scaled, tabulated, and graphical output. A scanning synchronization unit ensures that each input channel is sampled synchronously with input data pulses. System input can be either direct from the test area or from an analog tape recorder, in which case time expansion is possible by the use of high record-low play/back speeds. A computer program controls the analog to digital conversion process. The on-line control of the program minimizes the subsequent data reduction, and through the use of input parameters, flexibility is attained in data formatting. The data reduction error is less than 1% and statistical programs included in the system provide estimates of the quality of the input data. The entire system including all associated hardware and software is described in detail, using acquisition of pressure data synchronously with crank angle as an example.
1975-02-01
Technical Paper
750088
Robert M. Storwick, Louis L. Nagy
One of the prime requisites for automobile radar systems is obstacle hazard evaluation, the extent needed being dependent upon the particular system application. Much of the information necessary for a radar system to assess the degree of hazard of a target must come from characteristics which can be measured by the radar itself. While the hazard evaluation capacity has not yet been developed for automobile radar systems, research to provide this capability is in progress. Continuous wave (CW) scattering measurements have been made in a manner which is consistent with automobile radar operation. Various aspects of simple targets and of an automobile were measured in a microwave anechoic chamber. Both horizontal and vertical linear polarizations were transmitted and their co-linear and cross polarizations received. These data have been used to confirm the existence of and to understand certain scattering mechanisms. They have also been subjected to analyses in order to determine the ability to discriminate among the various simple targets.
1975-02-01
Technical Paper
750675
E. D. Davison, M. L. Haviland
As part of General Motors effort to improve fuel economy, the effects of engine and power train lubricant viscosities were investigated in passenger car tests using either high- or low- viscosity lubricants in the engine, automatic transmission, and rear axle. Fuel economy was determined in both constant speed and various driving cycle tests with the car fully warmed-up. In addition, fuel economy was determined in cold-start driving cycle tests. Using low-viscosity lubricants instead of high-viscosity lubricants improved warmed-up fuel economy by as much as 5%, depending upon the differences in lubricant viscosity and type of driving. Cold-start fuel economy with low-viscosity lubricants was 5% greater than that with high-viscosity lubricants. With such improvements, it is concluded that significant customer fuel economy gains can be obtained by using the lowest viscosity engine and power train lubricants recommended for service. To determine if currently recommended engine oil, automatic transmission fluid, and rear axle lubricant viscosities can be reduced, extensive performance and durability testing will be required.
1975-02-01
Technical Paper
750849
James E. Bennethum, James N. Mattavi, Richard R. Toepel
In-cylinder sampling appears to be the only available means for obtaining detailed information of the diesel combustion process. This information is necessary to understand pollutant formation because of the intimate relationship between formation rates and local cylinder conditions. This paper discusses efforts to (1) examine and improve sampling valve design, (2) evaluate potential effects of the valve and the sampling system on sample composition, (3) find methods to extract useful information from sampling data. Sampling hardware is currently being used to study combustion in engines, but further work is needed to quantify the influence of hardware and procedures on sample composition and to design experiments to provide data containing maximum information.
1975-02-01
Technical Paper
750827
John J. Rodgers, Richard H. Kabel
A five-vehicle, 64 000-km test with 7.45 litre V-8 engines was conducted to determine if synthetic engine oils provided performance sufficiently superior to that of conventional engine oils to permit longer oil change intervals. The results show better performance in two areas of deposit control; inferior performance with respect to wear protection; and essentially equivalent performance in the areas of fuel and oil economies. Based on these data, it was concluded that synthetic engine oils do not provide the necessary performance required to safely recommend their use for extended oil change intervals. In addition, a cost analysis shows that the use of synthetic engine oils, even at a change interval of 32 000 km, will essentially double the customers' cost compared with conventional engine oils at GM's current 12 000-km change interval.
1974-02-01
Technical Paper
740993
Gregory A. Campbell, Edward M. Hagerman, Stanley A. Iobst, William C. Meluch, Robert J. Salloum, Clyde C. Culver
Several polymeric materials were developed and evaluated for possible inclusion in the neck structure of state-of-the-art anthropomorphic dummies. These included three types of foam-polyvinylchloride, polyethylene, and polyurethane, and two flexible polymers-polyurethane and a polyvinylchloride chlorinated polyethylene blend (PVC-CPE). Two materials, the polyurethane elastomer and the PVC-CPE blend, were found to be satisfactory in their dynamic response. Because of the ease of casting, the polyurethane material will be used in the GMR 1 state-of-the-art dummy.
1974-02-01
Technical Paper
740055
E. D. Davison, M. L. Haviland
Automatic transmission fluids can oxidize with use, causing marginal transmission performance and eventual transmission malfunction. Periodic fluid changes are presently recommended to alleviate this problem. Fluid oxidation is promoted in current transmissions because they breathe air freely through a vent tube. To reduce fluid oxidation, and thereby improve fluid and transmission durability, a one-way check valve, called the Transmission Air Breathing Suppressor (TABS), was designed to restrict the intake of air into the transmission and to replace the conventional vent tube. The effectiveness of the TABS valve in reducing fluid oxidation was determined in high temperature transmission cycling tests and in taxicab tests. Fluid oxidation results with the TABS valve-equipped transmissions were compared to those with normally-vented transmissions. By reducing the amount of oxygen in the transmission gas, the TABS valve nearly eliminated fluid oxidation. With such improvement, fluid change intervals may be extended or eliminated.
1974-02-01
Technical Paper
740588
Raymond F. Neathery, Harold J. Mertz, Robert P. Hubbard, Mark R. Henderson
Two Highway Safety Research Institute (HSRI) dummies were tested and evaluated. Based on the analysis given, the HSI dummy should not be used for vehicle qualification testing. However, many of its components offer viable alternatives for future dummy development. The dummy was found to have inadequate biomechanical fidelity in the head, neck, and chest, although its characteristics were very promising and, as a whole, biomechanically superior to the Hybrid II. Its repeatability and reproducibility in dynamic component tests were better than the Hybrid II dummy. In particular, the HSRI friction joints were outstanding in repeatability and had a significant advantage in usability in that they do not require resetting between tests. In three-point harness and ACRS systems tests, the values of injury criteria produced by the HSRI dummy were generally lower than those obtained with the Hybrid II, especially the femur loads in the ACRS tests. However, the repeatability and reproducibility of the HSRI dummy were significantly poorer than the Hybrid II.
1974-02-01
Technical Paper
740329
Curtis F. Vail
The assembly and particularly the reduction of the mass and stiffness matrix for a large system can be a significant portion of the computational cost of finding the mode shapes and natural frequencies. Therefore, parameter studies for design purposes can be prohibitive if these matrices are reassembled and reduced for each change. The purpose of this paper is to outline the procedure for using the modes of the original system to determine the dynamic characteristics of the changed system. The method also results in computational savings for boundary condition changes and for large systems that are nearly-symmetric except for a few mass and stiffness changes. To illustrate the method several changes are made to a ladder frame. The results from an analysis using the reconstructed mass and stiffness matrices and the modal synthesis technique are compared to show the accuracy and freedom requirements.
1974-02-01
Technical Paper
740325
Hilario L. Oh, Neng-Ming Wang
To compute the tearing energy of nicked rubber strips in extension, one has to solve first the associated stress-deformation involving finite elasticity. In the past, this was a formidable task so that the tearing energy had been determined solely by experiments and only for a few testpieces. With the aid of the finite element method (FEM), it is shown that this may now be done simply through the use of the Rice's J integral. Tearing energy for two testpieces are computed and results compared with existing experimental data. The agreement is good. Because of FEM's ability to treat general geometric and loading conditions, the use of the J integral in combination with FEM to cmpute the tearing energy now allows a wider application of the tearing energy concept to more complex units than hitherto known.
1974-02-01
Technical Paper
740344
R. K. Leverenz, B. L. Ng, W. D. Birchler, A. R. Periard, L. Esselink
Interactive graphics is an aid which eliminates the data management problems that arise when manually preparing finite element models. Line and surface data representations of sheet metal automotive stampings are displayed on a cathode ray tube (CRT), and these data are then used for building finite element models. Elements are built by creating node points with the light pen or by using automatic mesh generating techniques. By using the interactive capability, the user immediately sees the results of his modeling decisions and can make changes in his model as a result of viewing his work. The interactive graphics system allows the user to define his elements, load cases, boundary conditions, and freedom sets without worrying about the grid point or element numbers. All information is communicated through the use of either the light pen or the keyboard. As information is supplied about the model, it is stored in a data base for review and possible change. After the structure is complete, the data base is processed and the information is formatted for either of three finite element codes.
1974-02-01
Technical Paper
740159
J. J. Rodgers, N. E. Gallopoulos
During development of the General Motors rotary engine, the lubricant was recognized as important to its success because certain lubricants produced deposits which tended to stick both side and apex seals. Consequently, it was decided to develop a rotary engine-dynamometer test, using a Mazda engine, which could be used for lubricant evaluation. In an investigation using an SE engine oil with which there was rotary engine experience, engine operating variables and engine modifications were studied until the greatest amount of deposits were obtained in 100 h of testing. The most significant engine modifications were: omission of inner side seals, plugging of half the rotor bearing holes, pinning of oil seals, grinding of end and intermediate housings, and using a separate oil reservoir for the metering pump. Using this 100 h test procedure, three engine oils and five automatic transmission fluids were evaluated. Generally, the automatic transmission fluids controlled deposits better than the engine oils.
1974-02-01
Technical Paper
740187
R. F. Stebar, F. B. Parks
Hydrogen-supplemented fuel was investigated as a means of extending lean operating limits of gasoline engines for control of NOx. Single-cylinder engine tests with small additions of hydrogen to the fuel resulted in very low NOx and CO emissions for hydrogen-isooctane mixtures leaner than 0.55 equivalence ratio. Significant thermal efficiency improvements resulted from the extension beyond isooctane lean limit operation. However, HC emissions increased markedly at these lean conditions. A passenger car was modified to operate at 0.55-0.65 equivalence ratio with supplemental hydrogen. Vehicle emissions, as established by the 1975 Federal Exhaust Emissions Test, demonstrated the same trends as the single-cylinder engine tests. The success of the hydrogen-supplemented fuel approach will ultimately hinge on the development of both a means of controlling hydrocarbon emissions and a suitable hydrogen source on board the vehicle. Reported efforts to develop a satisfactory onboard hydrogen generator (gasoline reformer) appear restricted by fuel economy considerations.
1974-02-01
Technical Paper
740102
Carl A. Schiele, Stephen F. DeNagel, James E. Bennethum
The development of a variable valve timing (VVT) camshaft was initiated as a potential means of controlling exhaust emissions from a spark ignition piston engine. This approach was based on the fact that valve overlap influences internal exhaust gas recirculation which in turn affects spark ignition engine emissions and performance. The design, fabrication, bench tests and engine durability tests of a unit incorporating splines to allow the intake cams to move relative to the exhaust cams is discussed. Preliminary test data from a 350 CID (5700 cm3) engine fitted with the VVT camshaft are discussed with regard to durability and emissions.
1974-02-01
Technical Paper
740114
Robert Hickling, William R. Smith
Tests of laser ignition are conducted in a combustion bomb. A range of fuels is investigated comprising isooctane, cyclohexane, n-heptane, n-hexane, clear indolene, and No. 1 diesel fuel. The ignition characteristics of laser-induced sparks are compared with sparks generated with a spark plug for different air/fuel ratios. The power density required to produce laser induced sparks is investigated. Although laser ignition appears to be impractical as an ignition device because of its low efficiency and high cost, it presents some interesting possibilities compared to the standard spark plug in that the laser spark is electrodeless and can be positioned anywhere inside the combustion chamber. Its primary use appears to be as a research tool.
1974-02-01
Technical Paper
740109
Irvin D. Wilken, Robert Hickling, Harold V. Wiknich
A single-wheel trailer has been designed and built to study the origins of tire noise and its basic characteristics. The single test tire, nominally the 10.00/20 size usually mounted on large trucks and semitrailers, is located 12.2 m (40 ft) behind the rear axle of the towing vehicle to isolate it from other noise sources. Reflective surfaces that could interfere with noise measurements are minimized by the high, single-beam construction of the trailer. The towing vehicle is modified to reduce its noise and wake in the vicinity of the test tire, which can be loaded to 22.2 kN (5000 lb) by dead weights and rolled at expressway speeds. Because of its unusual configuration, the dynamic behavior of the trailer was studied prior to design to help determine several design parameters and show that the trailer would follow well. Extensive stress analyses of the trailer beam and other structural elements were also required. The trailer has been built and operated, and adequately overcomes anticipated mechanical problems.
1973-02-01
Technical Paper
730051
John M. Brown, Richard C. Drutowski
This paper evaluates the tendency of lip seals to fracture in a test apparatus in which dynamic runout is 0.010 in and the temperature is cycled between -30 and 0 F. Seals made of eight different polyacrylate polymers were soap-sulfur cured with various types and amounts of carbon black. Physical tests included room-temperature flexibility defined by Young's modulus at small strains, standard tensile tests at room temperature, flexibility at sub-zero temperatures determined by a Gehman test, and sub-zero starting torques of the seals. Primary determinant of successful fracture resistance is a low starting torque resulting from good low-temperature flexibility. The effect of adding graphite to some of these formulations is described and some current commercially available seals are evaluated.
1973-02-01
Technical Paper
730129
Garth L. Maxam, Oliver T. McCarter, Donald E. Schofield
This paper defines the overall problem of electromotive interference (EMI) from an automotive viewpoint. First, the general conditions (coupling modes) that apply within the automobile are described, then the automobile as a source of interference is examined. Performance criteria for electromagnetic automobile radiation limits as defined by various organizations are compared. Methods of measuring EMI are discussed, then the authors examine the environment both inside and outside of the automobile. Finally, the paper presents detailed test results of automotive impedance studies.
1973-02-01
Technical Paper
730133
Robert M. Storwick, David C. Schlick
Noise produced by automotive ignition systems can deteriorate the performance of nearby communication systems. An important step toward alleviating this difficulty is to characterize the ignition noise. Measurements have been made of the noise peak amplitude distribution of a number of identically equipped vehicles over a fixed period of time. Both vertical and horizontal polarizations were used, and measurements were made at two frequencies, 145 and 230 MHz. These statistics were then compared to various probability distributions to attempt to characterize the amplitude distribution of the noise. The distributions studied were: the log-normal, the exponential, the Rayleigh, and the Weibull distributions. It was concluded that the best fit was provided by the Weibull distribution. The parameters of the best fitting distribution are primarily a function of the antenna's polarization, with frequency having only a minor effect.
1973-02-01
Technical Paper
730153
Ather A. Quader
This study describes the effect of spark plug location on NO and HC emissions from a single-cylinder engine with a specially modified combustion chamber. The effects of changes in combustion duration caused either by spark location, dual spark plugs, or charge dilution on NO and HC emissions were also examined. Experiments were run at constant speed, constant load, and mbt spark timing. Nitric oxide emissions were the same with the spark plug located either near the intake or exhaust valve, but were higher with the spark plug midway between the valves or with dual ignition. Hydrocarbon emissions were lowest with the spark plug nearest the exhaust valve and increased with the distance of the spark plug from the exhaust valve. With charge dilution the decrease in NO emission was isolated into a pure dilution effect and a combustion duration effect. The combustion duration effect was minimal at rich mixtures and increased with air-fuel ratio. The implications of these results are presented and discussed.
1973-02-01
Technical Paper
730478
Michael L. McMillan, Chester K. Murphy
An analysis of oil pumpability reveals that engine oil pumping failures may occur because either the oil cannot flow under its own head to the oil screen inlet, or the oil is too viscous to flow through the screen and inlet tube fast enough to satisfy pump demands. To determine which factor is controlling, the behavior of commercial, multigraded oils was observed visually at temperatures from -40 to 0°F (-40 to - 17.8°C) in a laboratory oil pumpability test apparatus. Test results revealed that pumping failures occur by the first alternative: a hole is formed in the oil, and the surrounding oil is unable to flow into the hole fast enough to satisfy the pump. Of 14 oils tested, 7 failed to be pumped because of air binding or cavitation which developed in this manner. A model, which explains these failures in terms of yield point considerations and the low shear apparent viscosity of the oils, is proposed.
1973-02-01
Technical Paper
730494
W. R. Brandstetter, M. J. Carr
To lower emissions from a multicylinder engine, the air-fuel ratio must be optimized in all cylinders. If uniform fuel distribution is achieved, then the cylinder-to-cylinder air distribution is of particular interest. A probe system has been developed to measure mass flow rates to individual cylinders during operation of a complete engine. Fast response measurements of pressure, temperature, and flow velocity are made in the intake port near the valve during the intake portion of the cycle. High-speed collection of the large volume of data was accomplished through on-line use of an IBM 1800 computer. A V8 455 CID (7457 cm3) engine with stock intake and single exhaust system was used in the initial application of the mass flow probe. Measurements of 30-40 individual cycles were combined to calculate the mean volumetric efficiency for each cylinder. When measurements for all of the cylinders had been made, the cylinder-to-cylinder distributions were computed as deviations from the overall average.
1973-02-01
Technical Paper
730493
Donald J. Pozniak, Robert M. Siewert
Secondary air scheduling and average delivery rate have a great influence on the performance (carbon monoxide and hydrocarbon cleanup) of rich thermal manifold reactors. A continuously modulated secondary air system was devised to provide a tailpipe air-fuel ratio that did not change significantly with engine speed or load when a “flat” carburetion calibration was incorporated. This system involved throttling the inlet of the air pump(s) so that the air pump and engine intake pressures were equal. The continuous air modulation system was compared with an unmodulated system and a step-modulated system. The secondary air systems were investigated with both GMR “small volume” cast iron thermal reactors and Du Pont V thermal reactors on modified 350 CID V-8 engines in 1969 Chevrolet passenger vehicles. It was found that thermal reactor performance improved with each increase in control of the secondary air schedule. With the continuous air modulation system a reduction in CO emissions of approximately 45% (on the 1972 Federal Test Procedure emissions test) was achieved relative to an unmodulated system.
1973-02-01
Technical Paper
730573
H. R. Mitchell, R. N. McGill
Most transducers offered commercially are suitable for laboratory, aerospace, or industrial process applications but do not meet additional, stringent automotive requirements. A need exists, both present and future, for various types of transducers in automotive powerplant control systems. Possible electronic systems and subsystems requiring transducers are discussed, and the types of transducers needed for these systems are described along with a discussion of a general set of specifications with respect to accuracy, reliability, and durability. Substantial transducer development is needed to enhance the advancement of certain automotive electronic systems. This paper points out these requirements to the electronics industry in an effort to encourage a mutual industry development that will advance the technology.
1973-02-01
Technical Paper
730570
Gerald J. Barnes, Richard L. Klimisch
The use of relatively small catalytic converters containing alumina-supported platinum (Pt) and palladium (Pd) catalysts to control exhaust emissions of hydrocarbons (HC) and carbon monoxide (CO) was investigated in full-scale vehicle tests. Catalytic converters containing 70-80in3 of fresh catalyst were installed at two converter locations on the vehicle. Carburetion was richer than stoichiometric, with air-fuel ratios (A/F) comparable to those proposed for dual-catalyst systems containing an NOx reduction catalyst. The vehicle was equipped with exhaust manifold air injection. Homogeneous thermal reaction in the exhaust manifolds played a significant role in the overall control of HC and CO. Four Pt catalysts, three Pd catalysts, and one Pt-Pd catalyst were prepared and evaluated. Total metal loadings were varied 0.01-0.07 troy oz. Hydrocarbon conversion efficiencies varied 62-82%, measured over the 1975 cold-hot start weighted Federal Test Procedure. Corresponding CO conversions ranged 89-97%.
1973-02-01
Technical Paper
730575
William J. Fleming, David S. Howarth, David S. Eddy
Various proposals for emissions cleanup systems have shown the desirability of regulating engine air-fuel ratio within precise limits. For this purpose a prototype exhaust sensor has been investigated. The sensor is a ceramic device, made of stabilized zirconia, which operates via electrochemical principles. It is placed directly in the exhaust stream and generates a voltage signal which is an approximate indication of engine air-fuel ratio. Several sensors have been installed in situ on engines operated under controlled dynamometer conditions. Fundamental response characteristics of the sensors have been determined. The results of this investigation, together with descriptions of the construction and installation configuration of the prototype sensor, are discussed.
1973-02-01
Technical Paper
730598
N. E. Gallopoulos, J. C. Summers, R. L Klimisch
Platinum, palladium, and copper-chromium oxidation catalysts for exhaust emission control were exposed to exhaust gases from a steady-state engine dynamometer test in which the amount of oil consumed per unit volume of catalyst was high. When unleaded gasoline (0.004 Pb g/gal, 0.004 P g/gal) was used, conventional SE oil caused somewhat greater loss of catalyst activity than an ashless and phosphorus-free (“clean”) oil. Chemical analysis of the catalyst indicated that phosphorus from the conventional oil was probably responsible for the difference. However, a test run with low-lead (0.5 Pb g/gal, 0.004 P g/gal) gasoline and “clean” oil caused much greater catalyst activity deterioration than either of the tests with unleaded gasoline. The findings of this study indicate that engine oil effects on catalyst durability are of secondary practical importance, and that conventional SE engine oils will probably be acceptable for cars equipped with catalytic converters for the oxidation of exhaust hydrocarbons and carbon monoxide.
1973-02-01
Technical Paper
730982
R. F. Neathery, T. E. Lobdell
Abstract This paper summarizes an analysis, design, and test project in which a dummy chest structure was developed. The chest consisted of mechanical elements that had been characterized by computer simulations as giving responses to blunt frontal impacts necessary for biofidelity. An analysis of mechanical rib structures indicated that materials having a high ratio of yield stress to modulus of elasticity were required. Only metals having unusually high yield strengths, such as spring steels, qualified. A mechanical system was developed with steel ribs pivoted at each end as a primary spring. A secondary spring was a pair of commercially available die springs acting in parallel with the ribs after 25.4 mm (1.00 in) deflection. A fluid damper was developed to provide the damping. The chest structure was tested under conditions modified from those used by Kroell. The modifications were holding the spine rigidly and reducing the impact masses. The response of the mechanical system was similar to that predicted by the mathematical model.
1973-02-01
Technical Paper
730981
R. M. Schreck, David C. Viano
Abstract The following work was done in support of a continuing program to better characterize the behavior of the human chest during blunt sternal impact. Previous work on this problem has focused on determining the force-time, deflection-time, and force-deflection response of embalmed and fresh cadavers to impact by a 15 cm (6 in) diameter striker of variable mass traveling at velocities of 22.5-51 km/h (14-32 mph) and striking the sternum at the level of the fourth intercostal space. Additional questions persist concerning whether the anterior and posterior regions of the chest behave as highly damped masses or oscillate after impact, the relationship between force delivered to the surface of the body and the acceleration of the underlying regions, and the influence of air compressed in the lung on thoracic mechanics. Experiments were performed, using the carcasses of freshly sacrificed swine (sus scrofa), on which accelerometers were fastened to the sternum and backbone at the level of the fourth intercostal space.
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