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Direct-injection spark-ignition (DISI) engines have been investigated for many years but only recently have shown promise as a next generation gasoline engine technology. Much of this new enthusiasm is due to advances in the fuel injection system, which is now capable of producing a well-controlled spray with small droplets. A physical understanding of new combustion systems utilizing this technology is just beginning to occur. This analytical and experimental investigation with a research single-cylinder combustion system shows the benefits of in-cylinder gasoline injection versus injection of fuel into the intake port. Charge cooling with direct injection is shown to improve volumetric efficiency and reduce the mixture temperature at the time of ignition allowing operation with a higher compression ratio which improves the thermodynamic cycle efficiency.

The purpose of this paper is to describe and define the interaction between a brake based stability control system and a passive coupler (viscous coupling unit) inside the transfer case of a Four-Wheel Drive (4WD) vehicle. This paper will focus on the driveline system and the impact that a stability control system can have on it. It will provide understanding of torque transfer on 4WD vehicles that are equipped with a brake based stability control system and use this knowledge to recommend ways to reduce the undesirable torque transfer interaction between the two systems. These recommendations can be readily applied to future 4WD/AWD vehicles to improve compatibility between the two systems.

A series of tests were conducted to determine the potential for reducing vehicle underhood temperatures by either 1) diverting the radiator fan air flow from the engine compartment or 2) by forced air cooling of the exhaust manifold in conjunction with shielding it or 3) by a combination of the two methods. The test vehicle was a Ford F-250 Light Truck with a 7.5L V-8 engine. The vehicle was tested in a dynamometer cell equipped with cell blowers to simulate road speed conditions. It was found that diverting the outlet air from the radiator will reduce underhood component temperatures when the vehicle is in motion and also at normal idle. However, if the vehicle is to be used for power takeoff applications requiring a “kicked” idle, then forced cooling of the exhaust manifolds is also required to maintain reduced underhood temperatures. A combination of these two techniques maximized the reduction of underhood temperatures for all operating conditions tested.

This paper describes two types of dielectric-effect sensors that may be used as alternatives to a dielectric-effect sensor using a single capacitor. In the first type, three capacitors are mounted in a compact module inserted into a vehicle fuel line. The three capacitors are connected together to form an electrical pi-filter network. This approach provides a large variation of output signal as the fuel changes from gasoline to methanol. The sensor can be designed to operate in the 1 to 20 MHz frequency range. The second type of sensor investigated uses a resonant-cavity structure. Ordinarily, sensors based on resonant cavities are useful only if the operating frequency is several hundred MHz or higher. The high relative dielectric constant of methanol allows useful sensors to be built using relatively short lengths of metal tubing for the cavities. For example, a sensor built using a fuel rail only 38.7 cm long operated in a frequency range from 31 to 52 MHz.

Exhaust pressures (P3) are hard parameters to measure and can be readily estimated, the cost of the sensors and the temperature in the exhaust system makes the implementation of an exhaust pressure sensor in a vehicle control system a costly endeavor. The contention with measured P3 is the accuracy required for proper engine and vehicle control can sometimes exceed the accuracy specification of market available sensors and existing models. A turbine inlet exhaust pressure observer model based on isentropic expansion and heat transfer across a turbocharger turbine was developed and investigated in this paper. The model uses 4 main components; an open loop P3 orifice flow model, a model of isentropic expansion across the turbine, a turbine and pipe heat transfer models and an integrator with the deviation in the downstream turbine outlet parameter.

Modern diesel engines employ a multitude of strategies for oxides of nitrogen (NOx) emission abatement, with exhaust gas recirculation (EGR) being one of the most effective technique. The need for a precise control on the intake charge dilution (as a result of EGR) is paramount since small fluctuations in the intake charge dilution at high EGR rates may cause larger than acceptable spikes in NOx/soot emissions or deterioration in the combustion efficiency, especially at low to mid-engine loads. The control problem becomes more pronounced during transient engine operation; currently the trend is to momentarily close the EGR valve during tip-in or tip-out events. Therefore, there is a need to understand the transient EGR behaviour and its impact on the intake charge development especially under unstable combustion regimes such as low temperature combustion.

A new estimator for IC engine A/F ratio is described. A/F ratio is important for engine operation since it determines the quantities of engine emissions, such as HC, CO, NOx, the conversion efficiency of catalyst systems, and the engine combustion stability. The A/F ratio estimator described in this paper is based on a fundamental metric that relies on inducing and detecting crankshaft speed fluctuations caused by modulating the engine's fuel injection pulse widths. Fuel pulse width modulation varies the instantaneous combustion A/F ratio crankshaft velocity. Synchronous measurement of crankshaft velocity provides a metric that, when used with other engine state variables as inputs to a conventional neural network, can accurately estimate A/F ratio. The estimator provides A/F information when a physical sensor is not available.

Traction drive continuously variable transmissions (TCVTs) are under active investigation by a number of OEMs and suppliers. Along with advances in control systems and metallurgy, improved traction fluids will be key to successful implementation of this technology. Traction fluids will need to function over a wide range of temperatures and contact pressures. Contact pressures may reach as high as 4 GPa, while temperatures may range from about - 40 C to about 140 C. It is widely recognized that low temperature fluidity at start-up is an issue, since fluids which give high traction coefficients and adequate viscosity under normal operating temperatures generally exhibit high viscosity at low temperatures. However, fe published data are available on traction behavior at temperatures below about 20 C and at contact pressures above about 2 GPa.

An analytical model is developed to describe the longitudinal response of the timing chain and the associated torsional response of all the sprockets and tensioner. A closed form equilibrium analysis reveals that equilibrium tensions are functions of tensioner stiffness, chain preload, steady cam torques and engine speed. The equations of motion are linearized about the equilibrium position to determine natural frequencies, mode shapes of the torsional modes and the forced response due to cam torque harmonics. Experimental measurements of the system natural frequencies and the forced amplitudes are in good agreement with the theoretical predictions.

Speciated HC emissions from the exhaust system of a production engine without an active catalyst have been obtained with 3 sec time resolution during a 70°F cold start using two control strategies. For the conventional cold start, the emissions were initially enriched in light fuel alkanes and depleted in heavy aromatic species. The light alkanes fell rapidly while the lower vapor pressure aromatics increased over a period of 50 sec. These results indicate early retention of low vapor pressure fuel components in the intake manifold and exhaust system. Loss of higher molecular weight HC species does occur in the exhaust system as shown by experiments in which the exhaust system was preheated to 100° C. The atmospheric reactivity of the exhaust HC emissions for photochemical smog formation increases as the engine warms.

The recent development of TiAl-based alloys by the aerospace community has provided an excellent material alternative for hot components in automotive engines. The low density combined with an elevated temperature strength similar to that of Ni-base superalloys make TiAl-based alloys very attractive for exhaust valve applications. Lighter weight valvetrain components improve performance and permit the use of lower valve spring loads which reduce noise and friction and enhance fuel economy. However, difficult fabricability and a perception that TiAl alloys are high cost, low volume aerospace materials must be overcome in order to permit consideration for use in high-volume automotive applications. This paper provides a comparison of properties for several exhaust valve alternative materials. The density of TiAl alloys is lower than Ti alloys with creep and fatigue properties equivalent to IN-751, a current high performance exhaust valve material.

A computer code for predicting cooling air flow through the radiator and the condenser has been developed. The Reynolds-averaged Navier-Stokes equations, together with the porous flow model for the radiator and the condenser, were solved to simulate front end air flow and the engine compartment flow simultaneously. These transport equations were discretized based on a finite-volume method in a transformed domain. The computational results for a simplified engine compartment showed overall flow information, such as the cooling air flow through the radiator and the condenser, the effects of an air dam, and the effects of fresh air vents near the top of the radiator and the condenser. Comparison of the available experimental data with the analysis showed excellent prediction of the cooling air flow through the radiator and the condenser.

The thermal durability of a large frontal area cordierite ceramic wall-flow filter for light-duty diesel engine is examined under various regeneration conditions. The radial temperature distribution during burner regeneration, obtained by eight different thermocouples at six different axial sections of a 75″ diameter x 8″ long filter, is used together with physical properties of the filter to compute thermal stresses via finite element analysis. The stress-time history of the filter is then compared with the strength and fatigue characteristics of extruded cordierite ceramic monolith. The successful performance of the filter over as many as 1000 regenerations is attributed to three important design parameters, namely unique filter properties, controlled regeneration conditions, and optimum packaging design. The latter induces significant radial and axial compression in the filter thereby enhancing its strength and reducing the operating stresses.

Predicting the service lifetime of elastomeric automotive components is key to improving customer satisfaction over a 10 year / 150,000 mile desired lifetime. Achieving a good correlation between artificially aged components and those which have seen real customer usage can be a daunting task, considering the possible variations in climate, exposure and driver aggressiveness. In natural rubber (NR) components, the quantity and structure of the network crosslinks as a function of time can be used to explore some of the most basic aging mechanisms seen in the real world, as well as to validate protocols developed within the laboratory environment to accelerate the simulation of real-world mechanisms. This paper explores the findings of such a study on an NR engine mount, and examines the information learned by comparison between actual used components and test specimens subjected to accelerated degradation.

For the assessment of vehicle acoustics in the early design stages of a vehicle program, the use of full vehicle SEA models is becoming the standard analysis method in the US automotive industry. One benefit is that OEM's and Tier 1 suppliers are able to cascade lower level acoustic performance targets for NVH systems and components. Detailed SEA system level models can be used to assess the performance of systems such as dash panels, floors and doors, however, the results will be questionable until test data Is available. Correlation can be accomplished with buck testing, which is a common practice in the automotive industry for assessing the STL (sound transmission loss) of vehicle level components. The opportunity to conduct buck testing can be limited by the availability of representative bodies to be cut into bucks and the availability of a transmission loss suite with a suitably large opening.

The pulse flame combustor was adapted by researchers at Ford Motor Company in the early 1970s in order to produce exhaust gas simulating the combustion products of the internal combustion engine for the evaluation of automotive catalysts. Over the years, the pulse flame combustor has found application in a wide variety of research oriented tasks associated with automotive catalysts and emissions. More recent research and development efforts which have resulted due to elevated demands toward lower vehicle emission levels have prompted continuing refinements of the apparatus and effected innovative approaches to the study of emerging automotive catalyst and emission control issues with the pulse flame combustor. This report provides an overview of the operation and design evolution of the pulse flame combustor. In addition, recent applications of this laboratory device for studying automotive catalysts, alternative fuels, and other automotive emission control topics are reviewed.

The electrical principle of operation, the geometrical and electrical circuit constraints on the design of, and the electrical and in-engine performance of a multigap spark plug developed for automotive applications are described. The electrical principle of operation is based on successively breaking down an array of spark gaps through the use of a resistive ladder network. The measurements evaluating the electrical performance of various multigap designs indicate that these plugs can deliver up to twice the energy of a single gap plug to the arcs, using the same ignition system. The increased amount of energy is also delivered in a shorter time than for single gap plugs.

In this study, the particle emission characteristics of 10% alternative diesel fuel blends (Rapeseed Methyl Ester and Gas-to-Liquid) were investigated through the tests carried out on a light duty common-rail Euro 4 diesel engine. Under steady engine conditions, the study focused on particle number concentration and size distribution, to comply with the particle metrics of the European Emission Regulations (Regulation NO 715/2007, amended by 692/2008 and 595/2009). The non-volatile particle characteristics during the engine warming up were also investigated. They indicated that without any modification to the engine, adding selected alternative fuels, even at a low percentage, can result in a noticeable reduction of the total particle numbers; however, the number of nucleation mode particles can increase in certain cases.

A detailed description of the oxidative stability of GM's DEXRON®-VI Factory Fill Automatic Transmission Fluid (ATF) is provided, which can be integrated into a working algorithm to estimate the end of useful oxidative life of the fluid. As described previously, an algorithm to determine the end of useful life of an automatic transmission fluid exists and is composed of two simultaneous counters, one monitoring bulk oxidation and the other monitoring friction degradation [1]. When either the bulk oxidation model or the friction model reach the specified limit, a signal can be triggered to alert the driver that an ATF change is required. The data presented in this report can be used to develop the bulk oxidation model. The bulk oxidation model is built from a large series of bench oxidation tests. These data can also be used independent of a vehicle to show the relative oxidation resistance of this fluid, at various temperatures, compared to other common lubricants.

The occurrence of flash boiling in the fuel spray of a Port Fuel Injected (PFI) spark ignition engine has been observed and photographed during normal automotive vehicle operating conditions. The flash boiling of the PFI spray has a dramatic affect on the fuel spray characteristics such as droplet size and spray cone angle which can affect engine transient response, intake valve temperature and possibly hydrocarbon emissions. A new method of correlating the spray behavior using the equilibrium vapor/liquid (V/L) volume ratio of the fuel at the measured fuel temperature and manifold pressure is introduced.