Search Results

A 1.8L turbocharged diesel engine valvetrain friction was investigated, and the effectiveness of using a solid film lubricant (SFL) coating in reducing friction was determined throughout the operable speed range. This valvetrain design features direct acting mechanical bucket valve lifters. Camshaft journal bearing surfaces and all camshaft rubbing surfaces except lobe tips were coated. The direct acting bucket shims were etched with a cross hatch pattern to a depth sufficient to sustain a SFL film coating on the shim rubbing surfaces subjected to high surface loads. The SFL coated valvetrain torque was evaluated and compared with uncoated baseline torque. Coating the cam bearing journal surfaces alone with II-25D SFL reduced valvetrain friction losses 8 to 17% for 250 to 2000 rpm cam speed range (i.e. 500 - 4000 rpm engine speed). When bucket tappet and shims were also coated with the SFL, further significant reductions in coated valvetrain friction were observed.

The demand for improved fuel economy in both cars and trucks has emphasized the need for lighter weight components. The application of high strength steel to wheels, both rim and disc, represents a significant opportunity for the automotive industry. This paper discusses the Ranger HSLA wheel program that achieved a 9.7 lbs. per vehicle weight savings relative to a plain carbon steel wheel of the same design. It describes the Ranger wheel specifications, the material selection, the metallurgical considerations of applying HSLA to wheels, and HSLA arc and flash butt welding. The Ranger wheel design and the development of the manufacturing process is discussed, including design modifications to accommodate the lighter gage. The results demonstrate that wheels can be successfully manufactured from low sulfur 60XK HSLA steel in a conventional high volume process (stamped disc and rolled rim) to meet all wheel performance requirements and achieve a significant weight reduction.

An integrated engineering approach using computer modeling, laboratory and vehicle testing enabled the Ford GT engineering team to achieve supercar thermal management performance within the aggressive program timing. Theoretical and empirical test data was used during the design and development of the engine cooling system. The information was used to verify design assumptions and validate engineering efforts. This design approach allowed the team to define a system solution quickly and minimized the need for extensive vehicle level testing. The result of this approach was the development of an engine cooling system that adequately controls air, oil and coolant temperatures during all driving and environmental conditions.

A single cylinder indirect injection diesel engine was used to evaluate the emissions, fuel consumption, and ignition delay of non-petroleum liquid fuels derived from coal, shale, and tar sands. Correlations were made relating fuel properties with exhaust emissions, fuel consumption, and ignition delay. The results of the correlation study showed that the indicated fuel consumption, ignition delay, and CO emissions significantly correlated with the H/C ratio, specific gravity, heat of combustion, aromatics and saturates content, and cetane number, Multiple fuel properties were necessary to correlate the hydrocarbon emissions. The NOx emissions did not correlate well with any fuel property. Because these fuels from various resources were able to correlate succesfully with many of the fuel properties suggests that the degree of refinement or the chemical composition of the fuel is a better predictor of its performance than its resource.

New regulations from the state of California have established, for the first time, reactivity-based exhaust emissions standards for new vehicles and require that any clean alternative fuels needed by these vehicles be made available. Contained in these regulations are provisions for “reactivity adjustment factors” which will provide credit for vehicles which run on reformulated gasoline. The question arises: given two fuels of different chemical composition, but both meeting the criteria for CA Phase 2 gasoline (reformulated gasoline), how different might the specific reactivity of the exhaust hydrocarbons be? In this study we explored this question by examining the engine-out HC emissions from a single-cylinder version of the 5.4 L modular truck engine run on two different CA Phase 2 fuels.

A 1990 Ford Taurus operated on reformulated gasoline was tested under three modes of malfunction: disabled heated exhaust gas oxygen (HEGO) sensor, inactive catalytic converter, and controlled misfire. The vehicle was run for four U.S. EPA UDDS driving schedule (FTP-75) tests at each of the malfunction conditions, as well as under normal operating conditions. An extensive set of emissions data were collected. In addition to the regulated emissions (HC, CO, and NOx), a detailed chemical analysis was carried out to determine the gas- and particle-phase non-regulated emissions. The effect of vehicle malfunction on gas phase emissions was significantly greater than it was on particle phase emissions. For example, CO emissions ranged from 2.57 g/mi (normal operation) to 34.77 g/mi (disable HEGO). Total HCs varied from 0.22 g/mi (normal operation) to 2.21 g/mi (blank catalyst). Emissions of air toxics (1,3-butadiene, benzene, acetaldehyde, and formaldehyde) were also significantly effected.

Four vehicle fleets, consisting of 3 to 4 vehicles each, were emission tested on a 48″ roll chassis dynamometer using both the FTP urban dynamometer driving cycle and the REP05 driving cycle. The REP05 cycle was developed to test vehicles under high speed and high load conditions not included in the FTP. The vehicle fleets consisted of 1989 light-duty gasoline vehicles, 1992-93 limited production FFV/VFV methanol vehicles, 1992-93 compressed natural gas (CNG) vehicles and their gasoline counterparts, and a 1992 production and two prototype ethanol FFV/VFV vehicles. All vehicles (except the dedicated CNG vehicles) were tested using Auto/Oil AQIRP fuels A and C2. Other fuels used were M85 blended from A and C2, E85 blended from C1, which is similar to C2 but without MTBE, and four CNG fuels representing the range of in-use CNG fuels. In addition to bag measurements, tailpipe exhaust concentration and A/F data were collected once per second throughout every test.

A model is presented which incorporates the key mechanisms in the formation and reduction of unburned HC emissions from spark ignited engines. The model includes the effects of piston crevice volume, oil layer absorption / desorption, partial burns, and in-cylinder and exhaust port oxidation. The mechanism for the filling and emptying of the piston crevice takes into account the location of the flame front so that the flow of both burned gas and unburned gas is recognized. Oxidation of unburned fuel is calculated with a global, Arrhenius-type equation. A newly developed submodel is included which calculates the amount of unburned fuel to be added to the cylinder as a result of partial burns. At each crankangle, the submodel compares the rate of change of the burned gas volume to the rate of change of the cylinder volume.

A flow network method was developed to predict the underhood temperature distribution of an automobile. The method involves the solution of simplified energy and momentum equations of the air flow in control volumes defined by subdividing the air space between the surfaces of the underhood components and the front-end geometry. The control volumes are interconnected by ducts with branches and bends to form a flow network. Conservation of mass and momentum with appropriate pressure-loss coefficients leads to a system of algebraic equations to be solved for the flow rates through each volume. The computed flow rates are transferred to a thermal model to calculate the temperatures of the air and the major vehicle components that affect the underhood environment. The method was applied to a 1986 3.0L Taurus and compared with vehicle experiments conducted in a windtunnel.

Although there was a safety awareness from the earliest days of the automobile, systematic approaches to designing for safety became more widespread after 1950 when large numbers of vehicles came into use in both the United States and Europe, and governments in both continents undertook a widespread highway development. Industry response to safety objectives and also to government regulation has produced a large number of safety enhancing engineering developments, including radial tires, disc brakes, anti-lock brakes, improved vehicle lighting systems, better highway sign support poles, padded instrument panels, better windshield retention systems, collapsible hood structures, accident sensitive fuel pump shut-off valves, and other items. A significant development was the design of the energy absorbing front structures.

A four-stroke, spark-ignition engine is described that seeks to achieve high expansion ratio and low throttling losses at light load, whilst retaining good knock resistance at full load operation and without the need for expensive mechanical changes to the engine. The engine does, however, incorporate a second inlet (transfer) valve and associated transfer port linked to the intake port. The timing of the transfer valve is different from that of the main inlet valve. Load modulation is achieved by control of the gas outflow from the transfer port. A computer model of the engine is first validated against measured data from a conventional engine. Comparisons are made of incylinder pressure at part load conditions, total air flowrate through the engine and intake port air velocities as a function of crank angle position.

Combustion flame geometry calculation is a critical task in the design and analysis of combustion engine chamber. Combustion flame directly influences the fuel economy, engine performance and efficiency. Currently, many of the flame geometry calculation methods assume certain specific chamber and piston top shapes and make some approximations to them. Even further, most methods can not handle multiple spark plug set-ups. Consequently, most of the current flame geometry calculation methods do not give accurate results and have some built-in limitations. They are particularly poor for adapting to any kind of new chamber geometry and spark plug set-up design. This report presents a novel methodology which allows the accurate calculation of flame geometry regardless of the chamber geometry and the number of spark plugs. In this methodology, solid models are used to represent the components within the chamber and unique attributes (colors) are attached respectively to these components.

Automakers have the opportunity to utilize bio-based composite materials to lightweight cars while replacing conventional, nonrenewable resource materials. In this study, Life Cycle Assessment (LCA) is used to understand the potential benefits and tradeoffs associated with the implementation of bio-based composite materials in automotive component production. This cradle-to-grave approach quantifies the fiber and resin production as well as material processing, use, and end of life for both a conventional glass-reinforced polypropylene component as well as a cellulose-reinforced polypropylene component. The comparison is calculated for an exterior component on a high performance vehicle. The life cycle primary energy consumption and global warming potential (GWP) are evaluated. Reduced GWP associated with the alternative component are due to the use of biomass as process energy and carbon sequestration, in addition to the alternative material component's lightweighting effect.

Although much has been learned in recent years about the atmospheric reactivity of the hydrocarbon (HC) emissions from gasoline-fueled vehicles, there is only a limited database of corresponding information for exhaust emissions from diesel-fueled vehicles. An assessment of exhaust reactivity requires “speciation”, or measurement of the individual species of the HC fraction. The HC exhaust emissions are a complex mixture of unburned and partially burned fuel components. Because diesel fuel contains a much higher molecular weight range (typically C9-C26) than gasoline (typically C5-C12), new methodology was required to accommodate the collection and analysis of the >C12 fraction of the HC exhaust. As part of a study of the effects of fuel and other factors on the chemical nature of diesel emissions, we have developed a method for the collection and analysis of the semivolatile or heavy HC (>C12) fraction of the exhaust.

Computer simulation of the behavior of the automotive cooling system is becoming increasingly common, so as to reduce the dependency on costly testing. The simulation of transient cooling system behavior has become easier with the use of 1-D simulation tools. However, accurate prediction of transient coolant temperature after thermostat operation has been limited by the difficulty in accurately modeling the behavior of the automotive thermostat. Physical models of the thermostat are often inaccurate due to the complexity of the thermostat. Therefore an empirical model has been developed, which can be used to model any automotive thermostat, once a few simple tests have been conducted on the part. This thermostat model can be used in conjunction with a 1-D flow simulation tool to predict coolant transient temperature response during thermostat operation.

Exhaust gas air-fuel ratio (A/F) sensors are common devices in powertrain feedback control systems aimed at minimizing emissions. Both resistive (using TiO2) and electrochemical (using ZrO2) mechanisms are used in the high temperature ceramic devices now being employed. In this work a new mechanism for making the measurement is presented based on the change in the workfunction of a Pt film in interaction with the exhaust gas. In particular it is found that the workfunction of Pt increases reversibly by approximately 0.7 V at that point (the stoichiometric ratio) where the exhaust changes from rich to lean conditions. This increase arises from the adsorption of O2 on the Pt surface. On returning to rich conditions, catalytic reaction of the adsorbed oxygen with reducing species returns the workfunction to its original value. Two methods, one capacitive and one thermionic, for electrically sensing this workfunction change and thus providing for a practical device are discussed.

In assessing the sound quality of electric motors (e.g., seat, mirror, and adjustable pedal motors), the sensation of Fluctuation Strength - a measure of intensity or frequency variation - has become important. For electric motors, it is typically caused by variation in the load, creating frequency modulation in the sound. An existing method for calculating Fluctuation Strength proved useful initially, but more extensive testing identified unacceptable performance. There were unacceptable levels of both false positives and false negatives. A new method is presented, which shows improved correlation with perceived fluctuation in sounds. Comparisons are made to the previous method and improvement is shown through examples of objective-subjective correlation for both seat motor sounds and adjustable pedal motor sounds. The new method is also shown to match subjective data from which the original measure of Fluctuation Strength was derived.

We have developed a new wall wetting model to predict the transient Air/Fuel ratio excursion in a port fuel injected (PFI) engine due to changes in air or fuel flow. The quasi-dimensional model accounts for fuel films both in the port as well as in the cylinder of a PFI engine and includes the effects of back-flow on the port fuel films to redistribute and vaporize the fuel. A multi-component fuel model is included in the simulation; it gives realistic fuel behavior and allows the effects of different fuel distillation curves to be studied. The multi-component fuel model calculates the changing composition of the fuel puddles in the port and cylinder during the cycle. The inclusion of an in-cylinder fuel film allows the model to be used for cold start conditions down to 290 K. The model uses the Reynold's analogy to calculate the fuel vaporization process and uses a boundary layer calculation to solve for the liquid film flow.

A technique is presented that has been successfully demonstrated to non-intrusively and quickly sample gases typically found in PCV systems. Color Detection Tubes (CDTs) were used with a simple sampling arrangement to monitor CO2, NOx, O2, and H2O(g) at the closure line, crankcase, and PCV line. Measurements were accurate and could be made instantaneously. Short Path Thermal Desorbtion Tubes (SPTDTs) were used at the same engine locations for the characterization of fuel- and oil-derived hydrocarbon (HC) fractions and required only 50 cc samples. High engine loads caused pushover of blowby vapors as indicated by increased concentrations of CO2, NOx, H2O(g), and fuel HCs in the engines' fresh air inlets during WOT operation. Peak concentrations of blowby vapors were measured in the crankcase under no load and part throttle conditions. Oxygen concentrations always opposed the trends of CO2, NOx, and H2O(g).

As automakers strategize approaches to sustainable vehicle technologies, alternative powertrains must be considered to reduce future fleet vehicle emissions and improve energy security. These alternative vehicles include different fuels and electrification. The ultimate for on-road CO2 reductions is a zero emission vehicle, which can be achieved by either a hydrogen fuel cell or battery electric vehicle. These vehicles would also require a renewable energy source to provide their propulsion energy in order to achieve maximum sustainability for both CO2 reduction and energy security. Renewable energy sources such as wind or solar result in heat or electricity that needs to be generated into an energy carrier such as hydrogen or stored in a battery. When examining these options based strictly on the efficiency path, previous analysis have concluded fuel cell vehicles may not be an appropriate suitability strategy in comparison to battery electric vehicles.