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Engine operation with spark ignition retarded from MBT timing is used at cold start to reduce HC emissions and increase exhaust gas temperature; however it also results in increased cyclic variations. Steady-state cold fluids testing was performed to better understand the causes of the cycle-to-cycle variations. Detailed analysis of individual cycles was performed to help gain an understanding of the causes of cyclic variations. The important results were: The primary cause of cyclic variations in IMEP is variations in the combustion phasing (location of 50% mass fraction burned). The expansion ratio decreases rapidly during combustion for retarded spark timing and therefore the phasing determines individual cycle thermal efficiency and IMEP. Variations in the late burn have little impact on the IMEP as this combustion occurs close to EVO and does little expansion work.

The oxidation of surrogate diesel fuels composed of mixtures of three pure hydrocarbons with and without their cetane numbers chemically enhanced using 2-ethylhexyl nitrate (2-EHN) is studied in a variable pressure flow reactor over a temperature range 500 - 900 K, at 12.5 atmospheres and a fixed reaction time of 1.8 sec. Changes in both low temperature, intermediate temperature, and hot ignition chemical kinetic behavior are noted with changes in the fuel cetane number. Differences appear in the product distribution and in heat release generated in the low and intermediate temperature regimes as cetane number is increased. A chemically enhanced cetane fuel shows nearly identical oxidation characteristics to those obtained using pure fuel blends to produce the enhanced cetane value. The decomposition chemistry of 2-EHN was also studied. Pyrolysis data of 10% 2-EHN in n-heptane and toluene are reported.

In vehicle-pedestrian impacts, the kinematics and severity of pedestrian injuries are affected by vehicle front shapes. Accident analyses and multibody simulations showed that for mini vans the injury risk to the head is higher, while that to the legs is lower than for bonnet-type cars. In mini-van pedestrian impacts, pedestrians ran high risks of a head impact against stiff structures such as windshield frames. When pedestrians are struck by a car with a short hood length, their heads are likely to strike into or around the windshield. The injury risks to the head by such an impact were examined by head form impact tests. The HIC rises from contact with the cowl, windshield frame or A pillar, and it lessens with increasing distance from these structural elements.

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.

Early activation of catalyst by quickly raising the temperature of the catalyst is effective in reducing exhaust gas during cold starts. One such technique of early activation of the catalyst by raising the exhaust temperature through substantial retardation of the ignition timing is well known. The present research focuses on the realization of quick warm-up of the catalyst by using a method in which the engine is fed with a large volume of air by feedforward control and the engine speed is controlled by retarding the ignition timing. In addition, an intake air flow control method that comprises a flow rate correction using an adaptive sliding mode controller and learning of flow rate correction coefficient has been devised to prevent control degradation because of variation in the flow rate or aging of the air device. The paper describes the methods and techniques involed in the implementation of a quick warm-up system with improved adaptability.

This paper discusses a study conducted by GM to better understand the factors that influence injury potential in vehicle-to-vehicle side impacts. A number of other studies have been done which focus primarily on frontal vehicle-to-vehicle compatibility. GM focused on side impact compatibility in this study due to the risk of harm generally associated with this type of crash. Real world field performance was studied through an extensive six-state field analysis of recent model year (‘94+) vehicles. Of particular interest in this study was an efficacy analysis of the MVSS 214 dynamic side impact standard, which was phased-in starting with some 1994 model year passenger cars. Physical side impact crash testing of a 1997 passenger car was used to investigate the relationship of impacting mass, speed, geometric profile and stiffness on side impact intrusion and occupant injury.

The vehicle fleet differs in mass, geometry, stiffness and many other parameters. These differences are consequences of different design objectives for these vehicles and result from consumer demand, environmental and safety considerations etc. Accident research shows that the injury outcome differs in some cases, when two vehicles collide. Scientists often discuss a list of features that are assumed to be relevant for compatibility of vehicles. The relevance of these potentially important compatibility features and expected compatibility measures is examined from the perspective of accident analysis. An overview of this accident research is given and crash tests and measures are discussed that correspond with these findings.

A model has been developed to interpret experimental results for emissions and air/fuel ratio variations recorded during warm-up from cold starts at temperatures down to -20°C. The model describes fuel transport and utilisation after injection to its exhaust as fuel products or loss to the crankcase, and allows for the storage of fuel in films on the intake port surface, in-cylinder surfaces and in the piston “crevice”. Engine-out emissions of unburned hydrocarbons are treated as being comprised of contributions from the bulk charge, fuel returning from in-cylinder wetted surfaces and from fuel stored in the piston crevices. The model characterises engine-out emissions and air/fuel ratio variations successfully under both quasi-steady and transient engine operating conditions during warm-up. Good agreement between experimental data and model predictions has been achieved for a wide range of engine operating conditions.

The National Highway Traffic Safety Administration (NHTSA) routinely measures the force exerted on the barrier in crash tests. Thirty-six load cells on the face of the rigid barrier measure the force. This study examines the load cell barrier data collected during recent years of NCAP testing to determine how it can be used to assess vehicle structural crash characteristics and vehicle compatibility in car to car crashes. To illustrate the value of the data, the load cell measurements for an SUV are compared with a small car. Several aggressiveness metrics are proposed for different crash modes. The proposed metrics for frontal crash modes are the force at 250 mm of crush, the linear stiffness at various levels of crush, and the height of the center of force at 250 mm of crush. For front-to-side vehicle crashes, some additional metrics are proposed. The force distribution when the loading is sufficient to cause intrusion of the side door is proposed as the basis for a metric.

Up to now, incompatibility of cars was mainly derived from theoretical considerations due to differences with regard to mass, stiffness, and geometry. Numerous accident analyses and reports only showed, that mass is a dominant factor for the injury outcome in car-to-car collisions. The same analyses have difficulties to assess the influence of stiffness and geometry. One reason is the wide scattering of the injury outcome due to other more important variables than incompatibility. A second reason is the fact that stiffness correlates more or less with the mass. A third reason is the effect of the non-linearity of the geometry influence that means a positive influence of incompatible weak structures causes a reduced acceleration, but with an increased risk of intrusion into the passenger compartment. This can be observed at high impact speeds and/or low overlap degrees. These effects can be seen from accident analysis.

As one method of meeting current and future emission regulations on vehicles, automakers have increased PGM loadings in three-way catalysts. Engine dynamometer and FTP testing after accelerated engine agings were performed to compare current Pd:Rh and Pt:Rh catalysts with new Pd:Rh and Pt:Rh catalysts. This comparison demonstrated that enhanced three way performance can be obtained in the new catalysts with reduced Pd loadings or with the use of Pt:Rh instead of Pd:Rh. These improved catalysts will reduce the demand for high PGM loadings as well as provide flexibility in the PGM combinations used in exhaust systems.

To gain a better understanding of mixture requirements during starting, a diode laser based spectroscopic technique was developed to simultaneously measure the cycle-by-cycle fuel vapor-air equivalence ratio and residual gas CO2 concentration inside the cylinder of an operating engine. Cranking to startup conditions were simulated in a single-cylinder CFR engine installed in a cold test facility. In separate tests using propane, isopentane, and gasoline as fuel it was found that combustion began in the first cycle in which the fuel vapor-air equivalence ratio exceeded the lean flammability limit of the fuel. In the range of temperatures 22°C to -12°C, richer mixtures were required to start the engine and keep it firing consistently at lower temperatures. Intake charge dilution caused by the residual burned gas left over from the combustion in a previous cycle was found to contribute to misfires in some of the succeeding cycles.

We have conducted technical research to achieve levels of evaporative emissions very close to zero. In the conventional fuel tank system, the internal pressure in the fuel tank and vapor lines varies between positive and negative values due to the outside temperature, rendering emission control and performance in the actual vehicle very difficult. We have developed a control system utilizing the negative pressure in the engine intake manifold to maintain a negative pressure (vacuum) in the fuel tank at all times. By always maintaining such a vacuum, the variation in internal pressure that depends on diurnal variation in ambient temperature and the rise in internal pressure that depends on engine load, have been eliminated, enabling emissions from the fuel system to be reduced significantly. This paper gives an outline of the technology mentioned above.

Despite extensive media coverage to the contrary, mismatches among cars, utility vehicles, and pickups in crashes is not a big problem from a societal perspective. On the other hand, if you are riding in a small car that is about to be hit by a big utility vehicle, then the problem looms large. Crash compatibility has attracted a lot of attention lately because utility vehicles have become so popular. The concern is that their designs pose a threat to people riding in smaller cars. But the fact is, two-vehicle collisions between cars (including passenger vans) and utility vehicles or pickups account for only about 15 percent of all car occupant deaths. As a result, countermeasures that focus on making utility vehicles and pickups more crash compatible, however appropriate, can have only small effects on crash injuries and fatalities. On the other hand, improvements in crashworthiness not only reduce crash incompatibilities but also protect across a wider spectrum of crashes.

With the adoption of the California Low-Emission Vehicle Regulations and the associated lower emission standards such as LEV (Low-Emission Vehicle in 1990), ULEV (Ultra-Low-Emission Vehicle), and LEV II (1998 with SULEV-Super Ultra Low Emission Vehicle), concerns were raised by emissions researchers over the accuracy and reliability of collecting and analyzing emissions measurements at such low levels. The primary concerns were water condensation, optimizing dilution ratios, and elimination of background contamination. These concerns prompted a multi-year research program looking at several new sampling techniques. This paper will describe the cooperative research conducted into one of these new technologies, namely the Bag Mini-Diluter (BMD) and Direct Vehicle Exhaust (DVE) Volume system.

HONDA has developed technology to fulfill the strictest emissions standards to date. That is, we have developed the technology necessary to satisfy the state of California's SULEV (LEV–II) regulations. We were able to move from the conventional 600–cell, 4.3mil three–way catalyst to a 1200–cell, 2.0mil catalyst through the application of new canning technology. We were also able to achieve early catalyst light–off and improved conversion performance without increasing the precious metal content. However, it was not possible to satisfy the SULEV standards using only these improvements to the catalyst. It was also necessary for us to develop new emission control technology for the various stages of engine operation: cold, warm–up and post warm–up. Specifically, we developed technology that dramatically increases catalyst light–off speed by controlling intake air and ignition timing.

This paper describes new technologies for achieving exhaust emission levels much below the SULEV standards in California, which are the most stringent among the currently proposed regulations in the world. Catalyst light-off time, for example, has been significantly reduced through the adoption of a catalyst substrate with an ultra-thin wall thickness of 2 mil and a catalyst coating specifically designed for quicker light-off. A highly-efficient HC trap system has been realized by combining a two-stage HC trap design with an improved HC trap catalyst. The cold-start HC emission level has been greatly reduced by an electronically actuated swirl control valve with a high-speed starter. Further, an improved Air Fuel Ratio (AFR) control method has achieved much higher catalyst HC and NOx conversion efficiency.

Steer-by-wire and other “by-wire” systems (as defined in the paper) offer many passive and active safety advantages. To help ensure these advantages are achieved, a comprehensive system-safety process should be followed. In this paper, we review standard elements of system safety processes that are widely applied in several industries and describe the main elements of our proposed analysis process for by-wire systems. The process steps include: (i) creating a program plan to act as a blueprint for the process, (ii) performing a variety of hazard analysis and risk assessment tasks as specified in the program plan, (iii) designing and verifying a set of hazard controls that help mitigate risk, and (iv) summarizing the findings. Vehicle manufacturers and suppliers need to work together to create and follow such a process. A distinguishing feature of the process is the explicit linking of hazard controls to the hazards they cover, permitting coverage-based risk assessment.

This paper reports on a parametric study of side impact crash tests. Relative changes in injury risk are assessed for both front and rear struck side occupants in tests with variation of mass, stiffness, geometry and speed of the impacting mobile deformable barrier. The study concludes that the ground clearance of the MDB face and impact velocity have a significantly greater effect on injury risk than the other parameters. The paper also includes consideration of tests to further investigate the effects of mass ratio between the struck and striking vehicle. This cooperative project between the Australian Department of Transport and Regional Services and Transport Canada includes analysis of intruding door behaviour and consequent effects on injury risk.

This paper summarises the results of a project on vehicle crash compatibility, run by European automotive industry together with some research institutes. The project was funded by the European commission as BE97-4049. There are three main issues that can be detected in real world accidents, influencing vehicle compatibility. These issues are mass differences, compartment integrity with regard to frontal car-to-car impact, and differences in bumper and sill height in side impact. Longitudinal mismatch in frontal impact, front end stiffness and other items which are from a theoretical point of view responsible for vehicle aggressiveness are not seen influential from the view point of real world accidents. On the other hand, compartment collapse occurs, when there is not sufficient deformation energy available in vehicle front-end. And deformation energy is available, when it is provided by vehicle structures and when these structures interact.