Search Results

The importance of high shear conditions in automotive lubrication is discussed with respect to the influence on lubricant rheological properties. The distribution of shearing effects in lubricated components is also discussed. Two methods of simulating high shear conditions-an elastohydrodynamic lubrication simulator and a capillary viscometer-are presented, along with some data obtained from them on polymer-containing oils.

Several sets of both police-reported and in-depth traffic accident data are queried with respect to the involvement of vehicle malfunctions or defects in accident causation. It is concluded that accident-causing defects are inconsistently reported, are often attributable to the lack of appropriate maintenance practices, and are evidently not being corrected by present motor vehicle inspection systems. Although vehicle malfunctions are less frequently identified as accident causes than either human or environmental factors, they are noted often enough to be considered a problem. It is suggested that the automotive engineer has already built into the vehicle many detection systems which serve notice to the vehicle owner/operator that a component needs attention. Finally, it is suggested that further efforts in this direction may supplement state authorized periodic inspection programs in minimizing the incidence of vehicle defects in accidents.

A program is underway at the DOT/Transportation Systems Center to study the nondestructive detection of defects in tires, and to determine the relationship between these defects and tire failure. Ultrasonics, x-ray, infrared, holography, and other techniques are being used to determine their effectiveness as well as their limitations in this task. This paper describes the use and modification of the equipment for nondestructive inspection of new and retreaded tires. It also describes the use of a computer data bank for data collection, storage, and retrieval in the correlation of results.

An experimental technique has been developed to measure the minimum oil film thickness of dynamically loaded journal bearings. Inductive transducers were used to measure the motion of the journal within the bearing clearance and with this information the relative oil film thickness was determined. The measured film thickness correlated closely with analytically predicted values for five base oils. However, tests on four oils which met the SAE multiviscosity engine oil classification (three SAE 10W-30 and one SAE 10W-40) showed that the low shear rate viscosity of these oils could not be used to predict the bearing oil film thickness developed by these oils.

A bench test has been developed to simulate the ability of engine crankcase oil to flow from the sump to the pump inlet. The design of the system is geometrically equivalent to that found in a Chevrolet 230 CID L-6 engine. A number of crankcase lubricants have been evaluated in the rig to determine the effects of V.I. improver chemistry, soak time, fuel diluent content, and pour point on pumping rig delivery. In a more detailed phase of this study, the cold flow properties of 10 commercial oils have been compared to pumping rig results obtained at -20 and -30°F. The data suggest that the Brookfield viscometer is a more reliable indicator of oil pumpability than the GM pour time, CCS viscosity, or ASTM pour point.

The viscosity-shear dependence of multiviscosity oils measured in a rotary viscometer at low shear rates fits the Power Law model, relating viscosity to shear rate. A simulated oil pan rig permitted calculation of critical shear conditions and viscosities for engine pumpability. Critical conditions of apparent viscosity and shear stress were computed to be 400 poise at 5000 dynes/cm2 from data on a series of ASTM reference pumpability oils.

This paper presents the development of the concept of emission testing on a mass basis and the establishment of emission baselines and standards. Data from tests run on several fleets to establish equivalency factors between average exhaust emissions when testing according to the 1970 (7-mode), 1972 (CVS-C), and the 1975 (CVS-CH) federal test procedures are listed. These data were used to establish the 1972, 1973-1974, 1975, and 1976 standard values. Tests were run on 30 precontrol vehicles by both the 7-mode and CVS-C procedures to derive the factors used to translate the 7-mode procedure baseline data into equivalent CVS-C procedure baseline data for precontrol vehicles. These values were used to establish the 1972-1974 hydrocarbon (HC) and carbon monoxide (CO) light-duty vehicle standards. Similar tests were run on 138 1970 vehicles to establish standards for the CVS-C procedure that were equivalent to the 1970 standards using the 7-mode procedure.

Current evidence indicates that cars manufactured after 1974 or 1975 will be required to operate on unleaded gasoline. To determine the level of octane quality justified when refineries are producing only unleaded gasoline, improvements in mileage attainable by using gasoline of higher octane number were compared to costs of raising octane number. Motorists' total gasoline costs per mile are lowest when the octane number of the unleaded gasoline pool is in the range of 85 to 87 Motor octane number. And, dividing the unleaded pool into at least two octane grades -- one at 1 or 2 units above and one at 2 or 3 units below the pool value -- maximizes car satisfaction for any given pool quality.

In the scope of efforts at air purification, a registration system has been developed on behalf of the Ministry of Labor, Health, and Social Affairs of North-Rhine-Westfalia considering every kind of emission contributing to air pollution. The emissions of motor vehicle traffic, industry, small business and domestic furnaces are registered. The system establishes data with regard to place, time, duration, quantity, type, condition, and temperature of the emissions. The present state of investigation regarding motor vehicle traffic is discussed in this paper for the area of Cologne, West Germany.

This paper reviews the development of the LA 4 road route, and discusses efforts directed toward development of a short repetitive dynamometer cycle based upon the road route Also described are the instrumentation, methods, and selection process used to obtain a speed profile of a typical drive over the 12 mile long route The methods used to shorten the speed profile to 7.5 miles, and to shorten the average trip length, while preserving trip description such as average speed, idle time, number of stops, etc., are explained. A measure of the correlation of emissions from vehicles driven over the EPA Urban Dynamometer Driving Schedule (UDDS) and over the full LA 4 driving schedule is provided. The UDDS is a speed-trace consisting of 18 profiles. separated by idle periods of 0-39 s duration The schedule covers 7.46 miles in 1372 s for an average speed of 19.6 mph.

This paper presents procedures for calculating the emissions of the population-average diesel- and gasoline-fueled vehicles in a range of operating modes. These procedures, together with a simple, but flexible, model of vehicle driving patterns, are used to show how changes in traffic flow and driving patterns can influence the vehicular source of emissions along urban roadways. The procedures are applied to predict emission rates in hypothetical traffic flows and in real traffic conditions as measured in central Edinburgh, Scotland, where the relative contributions of individual traffic groups to the vehicular emission sources have been assessed.

This paper describes a technique for programming accelerated laboratory fatigue tests which is called the “peak-valley-pair” (P-V-P) method. As presented, the P-V-P method applies to automotive structural components which are insensitive to frequency and subjected to unidirectional loading. The P-V-P algorithm operates on the measured service responses of the component (displacement, load, strain, etc.) to yield the control signal for a laboratory fatigue test. Associated data processing and an example of this methodology are also presented.

The paper illustrates the high degree of correlation now attainable with practical vehicle test results, using a reduced-scale dynamometer. The techniques for achieving this state-of-the-art are described in relation to the parameters generally known to influence vehicle/laboratory correlation. As a result of the investigation, the following additional parameters are submitted: history of pad use, correct temperature/time simulation of the car by the machine, and rate of work input during a test. The simulation item is the subject of a special study in which the thermal conditions in a brake are examined on an analog computer by means of a 2 d.f. model. A discussion of the possible applications of the scale dynamometer leads to the conclusion that a machine could now be developed to provide meaningful data on linings for the use of friction material, brake, and vehicle manufacturers, as well as legislators.

Emission engineers are currently evaluating several catalyst substrate designs, such as monoliths and beads, for use in automotive converters. One of their problems is to design converters that provide adequate control of the engine exhaust emissions but that do not significantly increase back pressure. In this paper, the design tradeoffs between pressure drop and conversion efficiency are examined for monolith, bead, Raschig ring, and wire mesh catalyst substrates. It is shown that monolith substrates provide the best flexibility when designing converters to satisfy vehicle installation space and engine back pressure requirements. Bead substrates have higher potential conversion efficiencies than monoliths but are less adaptable to vehicle space requirements.

The paper briefly reviews the principle of a dynamometer that permits laboratory simulation of the road behavior of an actual passenger car, under all conditions. Also presented are the results obtained with United States Federal Motor Vehicle Safety Standard 105 on a passenger car making both road and simulator tests. These results show an excellent correlation with road testing. Furthermore, a comparison with road testing allows us to state that a better quality of testing is obtained with the simulator test bench.

Latest results with dual catalyst systems incorporating GEM nickel-copper alloy NOx reduction catalysts are reported. Progress in optimizing system design to provide rapid warmup, maintenance of operating temperature, and controlled carburetion to maximize NOx removal and minimize the risk of over-temperature is discussed. Results of vehicle durability tests of GEM catalysts run on dynamometers are also presented. Rapid warmup of the catalyst system can be obtained by keeping NOx reduction catalyst mass low and utilizing the ability of the reduction catalyst to oxidize CO, H2, and HC under net reducing conditions. This ability to oxidize CO, H2, and HC is also used to maintain system operating temperature. Carburetion is controlled to ±0.4 A/F with a four-barrel research carburetor, the design of which is described in detail.

The Federal Standards pertaining to the exhaust emission control of the 1976 model year automobiles presumably demand the catalytic conversion of the pollutants involved. Provided the air-fuel ratio is maintained at a stoichiometric value, some problems (for instance, fuel economy) can be solved. A closed-loop system was developed, consisting of an electronic fuel injection system and a special oxygen sensor, called the λ-sensor, in the exhaust manifold. First results on vehicles indicate that this control system offers an promising solution to the reduction of harmful contaminants. The closed-loop system can be used with a three-way catalytic converter or with a dual-bed system. It has not yet been investigated whether the durability of the two systems is adequate, apart from the general problems of the durability of each catalyst.

The use of a new tool for the evaluation of driver visibility requirements is described. The tool takes the form of a program written for an interactive computer graphics system. XYZ coordinates of window openings, visual obstructions, mirror systems and driver eye points are supplied as data. Polar coordinate line drawings are then generated on the graphics display simulating what a driver would see directly to the front and sides or indirectly to the rear through a rear view mirror. The program can be used to evaluate driver visibility in terms of forward and rearward visibility target areas in actual vehicles or in vehicle concepts (clay models, prototypes and car body drawings) which are sufficiently well developed to permit the specification of window coordinates.

This paper presents an analytical treatment of a mechanical-mathematical model of an air bag inflation process integrated with a model for the interaction between the air bag and a standing child dummy. The inflation model consists of a one-dimensional gas dynamics analysis of the flow system which delivers the gas to inflate the bag. The interaction model then provides a method for calculating the forces exerted by the inflating bag on the standing child. The results show that the unacceptably high contact forces recorded in standing-child air bag tests are due to impact of the unopened portion of the bag on the standing child. A single-membrane concept is thus suggested to reduce this impact severity.

This paper is a summation of various efforts to develop and improve passive restraints (air bags) for front-seat compact car occupants. The results of 140 system sled tests and of two full-scale crash tests with the system are presented. Several tests were conducted with offset and obliquely positioned occupants. Numerous other tests were also conducted to compare the 5th percentile female with the 50th and 95th percentile male.