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Technical Paper

Engine-Out Emissions from a Direct-Injection Spark-Ignition (DISI) Engine

The effects of operating parameters (speed, load, spark-timing, EGR, and end of fuel injection timing [EOI]) on engine-out, regulated (total HC, NOx, and CO) and speciated HC emissions have been investigated for a 1.83 L direct-injection, spark-ignition (DISI) engine. As the EOI is varied over the range from high to low stratification with other engine parameters held constant, the mole fractions of all regulated emissions vary sharply over relatively small (10-20 crank angle degrees [CAD]) changes in EOI, suggesting that emissions are very sensitive to the evaporation, mixing, and motion of the stratified fuel cloud prior to ignition. The contribution of unburned fuel to the HC emissions decreases while the olefinic partial oxidation products increase as the fuel stratification increases, increasing the smog reactivity of the HC in the exhaust gas by 25%.
Technical Paper

Further Experiments on the Effects of In-Cylinder Wall Wetting on HC Emissions from Direct Injection Gasoline Engines

A recently developed in-cylinder fuel injection probe was used to deposit a small amount of liquid fuel on various surfaces within the combustion chamber of a 4-valve engine that was operating predominately on liquefied petroleum gas (LPG). A fast flame ionization detector (FFID) was used to examine the engine-out emissions of unburned and partially-burned hydrocarbons (HCs). Injector shut-off was used to examine the rate of liquid fuel evaporation. The purpose of these experiments was to provide insights into the HC formation mechanism due to in-cylinder wall wetting. The variables investigated were the effects of engine operating conditions, coolant temperature, in-cylinder wetting location, and the amount of liquid wall wetting. The results of the steady state tests show that in-cylinder wall wetting is an important source of HC emissions both at idle and at a part load, cruise-type condition. The effects of wetting location present the same trend for idle and part load conditions.
Technical Paper

The Influence of Gas/Fuel Ratio on Combustion Stability and Misfire Limits of Spark Ignition Engines

The deterioration of combustion stability as lean operating limits and misfire conditions are approached has been investigated experimentally. The study has been carried out on spark ignition engines with port fuel injection and four-valves-per-cylinder. Test conditions cover fully-warm and cold operation, and ranges of air/fuel ratio, exhaust gas recirculation rates and spark timing. An approximate method of calculating gas/fuel ratio is described. This is used to show that combustion stability, characterised by the coefficient of variation of i.m.e.p., is a function of calculated gas/fuel ratio and spark timing until near to the limit of stability. A rapid deterioration in stability and the onset of weak, partial burning occurs at a gas/fuel ratio between 24:1 and 26:1 under fully-warm operating conditions, and around one gas/fuel ratio lower under cold operating conditions.
Technical Paper

The Use of Low Viscosity Oils to Improve Fuel Economy in Light Duty Diesel Engines

Historically, fuel cost conscious customers have tended to purchase diesel passenger cars. However, with increasing competition from alternative fuels and lean burn and direct injection gasoline fuelled engines, diesel engined vehicles currently face tough challenges from the point of fuel economy and emissions. In gasoline engines, low viscosity friction modified oils have demonstrated their potential for reducing internal engine friction and thus improving fuel economy, without adversely effecting engine durability. These fuel economy improvements have led to the introduction of such a low viscosity friction modified 5W-30 oil as the initial and service fill for the majority of Ford products sold in Europe. The trend towards even lower viscosities continues. To assess the potential benefits and issues of moving to 5W-20 in diesel engines, a short pilot study has been conducted using a Ford 1.8l direct injection diesel engine.
Technical Paper

High Strength Steel Skid Plates: A Design Optimization Study

The purpose of this paper is to show that certain steel skid plates can achieve up to a 50% weight reduction, with little or no increase in cost, by simply changing the shape and utilizing high strength steel. There are many factors that can influence the skid plate shape, including rail width, ground clearance, attachment points, drive shaft location, and the general shape of the object for which it is the skid plate's sole purpose to protect (fuel tank, transfer case, etc.). A skid plate is usually considered last from a design standpoint so that its design is dependent upon the environment which it is set in. For this reason, skid plates are generally heavy and flat to meet ground clearance requirements and have ribs inserted to increase stiffness. Sometimes design parameters require a skid plate to be heavy and flat. But more often, a stiffer lightweight design can be obtained.
Technical Paper

Flame Temperature Correlation of Emissions from Diesels Operated on Alternative Fuels

Work by Plee, Ahmad, and coworkers in the 1980s [1, 2, 3, 4 and 5] showed that for changes in intake air state, Diesel NOx, soot, soluble organic fraction, and HC emissions could be correlated using the stoichiometric flame temperature calculated at SOC or peak pressure conditions. In the present work, similar flame temperature correlations are obtained for emissions from three test engines; a 1.2L high speed direct injection (HSDI) Diesel, a 2.4L HSDI Diesel, and a 2.34 L single cylinder direct injection (DI) Diesel engine, the first of which was tested using four alternative fuels. Use of the flame temperature correlations presented may reduce the number of engine tests required to evaluate the effects of EGR on emissions of NOx, particulate, and HC, even when alternative fuels are used.
Technical Paper

Fuel Permeation Performance of Polymeric Materials

This paper presents an extensive set of permeation data on automotive fuel system materials. It adds significantly to the information provided by the same authors in SAE paper 983160 [1]. The permeation measurements refer to three different test fuels: fuel C, CE10 and CM15 at 40, 50 and 60°C. The materials examined include poly-ethylenes, nylons, polyketons, ethylene-vinyl alcohol copolymers, acetals, fluoropolymers and fluoroelastomers. These data are important in the design of automotive fuel system components capable of meeting LEVII or PZEV requirements. In particular, data of this kind are crucial in optimizing the permeation performance of multilayer structures for fuel system applications.
Technical Paper

Modeling of HCCI Combustion and Emissions Using Detailed Chemistry

To help guide the design of homogeneous charge compression ignition (HCCI) engines, single and multi-zone models of the concept are developed by coupling the first law of thermodynamics with detailed chemistry of hydrocarbon fuel oxidation and NOx formation. These models are used in parametric studies to determine the effect of heat loss, crevice volume, temperature stratification, fuel-air equivalence ratio, engine speed, and boosting on HCCI engine operation. In the single-zone model, the cylinder is assumed to be adiabatic and its contents homogeneous. Start of combustion and bottom dead center temperatures required for ignition to occur at top dead center are reported for methane, n-heptane, isooctane, and a mixture of 87% isooctane and 13% n-heptane by volume (simulated gasoline) for a variety of operating conditions.
Technical Paper

Flow-Acoustic Coupling in Quarter-Wave Resonators Using Computational Fluid Dynamics

Quarter-wave resonators are commonly used as acoustic silencers in automotive air induction systems. Similar closed side branches can also be formed in the idle air bypass, exhaust gas recirculation, and positive crankcase ventilation systems of engines. The presence of a mean flow across these side branches can lead to an interaction between the mean flow and the acoustic resonances of the side branch. At discrete flow conditions, this coupling between the flow and acoustic fields may produce high amplitude acoustic pressure pulsations. For the quarter-wave resonator, this interaction can turn the silencer into a noise generator, while for systems where a valve is located at the closed end of the side branch the large pressure pulsations can cause the valve to fail. This phenomenon is not limited to automotive applications, and also occurs in natural gas pipelines, aircraft, and numerous other internal and external flows.
Technical Paper

Evaluation of Some Alternative Diesel Fuels for Low Emissions and Improved Fuel Economy

This paper reports on Ford's participation in the PNGV ‘Ad Hoc’ Diesel Fuel Test program - Phase I. The purpose of this program was to assess the potential benefits of various fuel properties aimed at reducing engine-out emissions of NOx and particulates to meet LEV2 and Tier 2 emission standards. Four alternative fuels were evaluated using a Ford 1.2L DIATA diesel engine: 1) California Certification fuel (CARB), 2) low sulfur hydro-cracked fuel (LSHC), 3) LSHC fuel with a 15% Dimethoxy Methane blend (DMM), and 4) neat Fischer-Tropsch (FT100) fuel. Design of Experiments (DOE) and conventional techniques were used to evaluate the fuels at five speed and load conditions. Exhaust gas recirculation (EGR), injection rail pressure, and beginning of injection (BOI) timing were controlled during the tests. Steady-state engine performance, emissions, and cylinder pressure (combustion) data were recorded for each fuel.
Technical Paper

FordS Zero Emission P2000 Fuel Cell Vehicle

The P2000 Fuel Cell Electric Vehicle developed by Ford Motor Company is the first full-performance, full-size passenger fuel cell vehicle in the world. This development process has resulted in a vehicle with performance that matches some of today's vehicles powered by internal combustion engines. The powertrain in Ford's P2000 FCEV lightweight aluminum vehicle consists of an Ecostar electric motor/transaxle and a fuel cell system developed with XCELLSiS-The Fuel Cell Engine Company (formerly dbb Fuel Cell Engines, Inc.). Ballard's Mark 700 series fuel cell stack is a main component in the fuel cell system. To support this new FCEV, Ford has constructed the first North American hydrogen refueling station capable of dispensing gaseous and liquid hydrogen. On-going research and development is progressing to optimize fuel cell vehicle performance and refueling techniques.
Technical Paper

Eliminating Maps from Engine Fueling Control Algorithms

Presented in this paper is an adaptive steady state fueling control system for spark ignition-internal combustion engines. Since the fueling control system is model based, the engine maps currently used in engine fueling control are eliminated. This proposed fueling control system is modular and can therefore accommodate changes in the engine sensor set such as replacing the mass-air flow sensor with a manifold air pressure sensor. The fueling algorithm can operate with either a switching type O2 sensor or a linear O2 sensor. The steady state fueling compensation utilizes a feedforward controller which determines the necessary fuel pulsewidth after a throttle transient to achieve stoichiometry. This feedforward controller is comprised of two nonlinear models capturing the steady state characteristics of the fueling process. These models are identified from an input-output testing procedure where the inputs are fuel pulsewidth and mass-air flow signal and the output is a lambda signal.
Technical Paper

Simultaneous Reduction of NOx and Particulate Emissions by Using Multiple Injections in a Small Diesel Engine

The diesel fuel injection system is the heart of the diesel engine and has become one of the critical emissions control technologies in recent years with the advance of electronically controlled fuel injection. The main objective of this study was to investigate the effect of pilot, post and multiple fuel injection strategies on engine performance and emissions. The study was carried out on a 4-cylinder 1.2-liter small-bore direct injection diesel engine equipped with a high pressure common rail fuel injection system. A large amount of engine performance, emissions, and cylinder pressure data over several engine operating points was obtained and analyzed. It was determined that use of pilot injection does not lead to a simultaneous reduction of NOx and particulate emissions unless optimized combinations of EGR rate, main injection timing, pilot injection timing, quantity and dwell before main injection were achieved.
Technical Paper

An Artificial UEGO Sensor for Engine Cold Start - Methodology, Design, and Performance

The AFR control accuracy in the cold start is crucial to lowering emissions from IC-engine vehicles. An artificial UEGO “sensor” for estimating the real-time AFR during the engine cold start has been developed on the basis of a fuel-perturbation algorithm at Ford Scientific Research Labs. The AFR values calculated by the artificial UEGO sensor have been used in the closed-loop fuel control. Considering that the engine cold start AFR is an uncertain, non-linear problem, some other techniques for optimizing the input stimulation signal and the output-filtering model are integrated together with the fuel perturbation. This artificial sensor was realized and its performance was tested on a Ford vehicle for EPA75 cold 505 test. The assessment of the artificial sensor was quite different in comparison with that of a real UEGO sensor.
Technical Paper

An Overhead Cam Wear and Valvetrain Dynamics Study

A 22 hour engine test was developed to evaluate the effects of fuels, lubricants, and valvetrain dynamics on the wear of OHC 2.3L engine camshafts and finger followers. Procedures include a break-in to improve test repeatability and a test sequence to allow single-shift operation. A surface analyzer capable of measuring cam lobe wear profiles to micro-inch accuracy provided a quantitative wear comparison. A pure mineral oil, as expected, resulted in higher camshaft wear than using a fully formulated SF lubricant. Cam and follower wear increased significantly when ethanol replaced gasoline as fuel. The combination of ethanol, mineral oil and heavy duty valve springs was selected to increase test severity for hardware discrimination. The average wear of the intake lobes was greater than the exhausts. Kinematic analysis and visual inspection of the valve train mechanism revealed differences in the relative motion and contact stress pattern.
Technical Paper

A View of Flexible Fuel Vehicle Aldehyde Emissions

The aldehyde emissions of 1.6L and 5.0L flexible fuel vehicles (FFV) have been measured, with and without a catalyst, on a range of fuels. The “zero mile” catalyzed emission levels of formaldehyde when operating on M85 (85% methanol and 15% gasoline) are in the 5-15 mg/mi range, but as mileage accumulates they tend to be in the 30-50 mg/mi range. The feedgas levels are high and appear to correlate with engine displacement. The formaldehyde and methanol emissions are higher when operating on M100, compared to M85, but the non-oxygenated hydrocarbon emissions are about the same for both fuels, which suggests that the use of M85 may actually provide more air quality benefit than M100. High mileage control of aldehydes to the level of gasoline vehicles does not appear possible with current technology.
Technical Paper

Emissions Performance of Bi-fuel CNG and Bi-fuel LPG Passenger Cars Using Sequential Multi-point Injection Systems

This paper describes a study into the emissions performance of a passenger car running on natural gas and liquified petroleum gas. The gasoline engine was modified to allow the introduction of the alternative fuels into the engine. The effect of fuel system hardware on emissions was investigated. Modifications were carried out to the gasoline EMS to allow control of the alternative fuel systems. A number of changes were made to the gasoline calibration to allow operation on the alternative fuels. Emissions tests were conducted on commercial grade natural gas and liquid petroleum gas. The results were compared with gasoline emission results of an equivalent vehicle.
Technical Paper

Effects of Fuel Injection Pressure in an Optically-Accessed DISI Engine with Side-Mounted Fuel Injector

This paper presents the results of an experimental study into the effects of fuel injection pressure on mixture formation within an optically accessed direct-injection spark-ignition (DISI) engine. Comparison is made between the spray characteristics and in-cylinder fuel distributions due to supply rail pressures of 50 bar and 100 bar subject to part-warm, part-load homogeneous charge operating conditions. A constant fuel mass, corresponding to stoichiometric tune, was maintained for both supply pressures. The injected sprays and their subsequent liquid-phase fuel distributions were visualized using the 2-D laser Mie-scattering technique. The experimental injector (nominally a hollow-cone pressure-swirl design) was seen to produce a dense filled spray structure for both injection pressures under investigation. In both cases, the leading edge velocities of the main spray suggest the direct impingement of liquid fuel on the cylinder walls.
Technical Paper

Comparison of Emission Indexes within a Turbine Combustor Operated on Diesel Fuel or Methanol

The emission index (grams of species per kilogram of fuel) field within a regenerative turbine combustor has been mapped using a water-cooled sampling probe. The probe employed a choked orifice to simultaneously determine the local temperature. Derived from measurements are: air-fuel ratio, combustion efficiency, average fuel velocity and fuel distribution factor. Methods of averaging the discrete data are developed. A comparison of the data obtained when the combustor was operated on each of two fuels revealed that the use of methanol leads to lower nitric oxide but higher carbon monoxide emission than does the use of diesel fuel.
Technical Paper

50,000 Mile Vehicle Road Test of Three-Way and NOx Reduction Catalyst Systems

The performance of three way and NOx catalysts was evaluated on vehicles utilizing non-feedback fuel control and electronic feedback fuel control. The vehicles accumulated 80,450 km (50,000 miles) using fuels representing the extremes in hydrogen-carbon ratio available for commercial use. Feedback carburetion compared to non-feedback carburetion improved highway fuel economy by about 0.4 km/l (1 mpg) and reduced deterioration of NOx with mileage accumulation. NOx emissions were higher with the low H/C fuel in the three way catalyst system; feedback reduced the fuel effect on NOx in these cars by improving conversion efficiency with the low H/C fuel. Feedback had no measureable effect on HC and CO catalyst efficiency. Hydrocarbon emissions were lower with the low H/C fuel in all cars. Unleaded gasoline octane improver, MMT, at 0.015g Mn/l (0.06 g/gal) increased tailpipe hydrocarbon emissions by 0.05 g/km (0.08 g/mile).