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Technical Paper

Vehicle Trajectories After Intersection Collision Impact

1970-02-01
700176
The postcollision motion starts immediately upon completion of a collision impact where the vehicles obtain new sets of velocities through an exchange of momentum. Similitude with model study and fullscale automobile experiments indicate that the post-collision trajectory is essentially a plane motion, governed by inertia and tire friction. Trajectories depend on many parameters (such as tire friction coefficient, front wheel steering angle, vehicle geometrics, and whether wheels are locked or free to rotate) but not on the vehicle weight. Theoretical computation of trajectories are compared with experiments.
Technical Paper

Using μ Feedforward for Vehicle Stability Enhancement

2000-05-01
2000-01-1634
Vehicle stability augmentation has been refined over many years, and currently there are commercial systems that control right/left braking and throttle to create vehicles that remain controlled when road conditions are very poor. These systems typically use yaw rate and lateral acceleration in their control philosophy. The tire/road friction coefficient, μ, has a significant role in vehicle longitudinal and lateral control, and there has been associated efforts to measure or estimate the road surface condition to provide additional information for the stability augmentation system. In this paper, a differential braking control strategy using yaw rate feedback, coupled with μ feedforward is introduced for a vehicle cornering on different μ roads. A nonlinear 4-wheel car model is developed. A desired yaw rate is calculated from the reference model based on the driver steering input.
Technical Paper

Thermodynamic and Thermochemical Aspects of Combustion in Premixed Charge Engines Revisited

1993-03-01
930432
In principle, the thermodynamic and thermochemical processes evolve with time, irrespectively of their spatial orientation. They are, therefore, specified in terms of ordinary differential equations with respect to time as the only independent variable. This feature is well reflected in the literature by the so-called zero-dimensional models. Current demands of technological progress impose much stricter requirements upon the precision of such calculations than ever before. A methodology for catering to them is presented. Its application is illustrated by the performance analysis of a Renault engine, operated at full and part loads, with particular emphasis placed upon the formation of major combustion-generated pollutants, NOx and CO, in a premixed-charge engine.
Technical Paper

The Performance Effects of Edge-Based Heat Transfer on Lithium-Ion Pouch Cells Compared to Face-Based Systems

2014-04-01
2014-01-1866
Optimizing the hardware design and control strategies of thermal management systems (TMS) in battery packs using large format pouch cells is a difficult but important problem due to the limited understanding of how internal temperature distributions impact the performance and lifetime of the pack. Understanding these impacts is difficult due to the greatly varying length and time scales between the coupled phenomena, causing the need for complex and computationally expensive models. Here, an experimental investigation is performed in which a set of fixed one-dimensional temperature distributions are applied across the face of a Nickel-Cobalt-Manganese (NCM) cathode lithium ion pouch cell in order to study the performance impacts. Effects on the open circuit voltage (OCV), Ohmic resistance, bulk discharge and charge resistance and instantaneous power are investigated.
Technical Paper

Simulating a Complete Performance Map of an Ethanol-Fueled Boosted HCCI Engine

2015-04-14
2015-01-0821
This paper follows a cycle-simulation method for creating an engine performance map for an ethanol fueled boosted HCCI engine using a 1-dimensional engine model. Based on experimentally determined limits, the study defined operating conditions for the engine and performed a limited parameter sweep to determine the best efficiency case for each condition. The map is created using a 6-Zone HCCI combustion model coupled with a detailed chemical kinetic reaction mechanism for ethanol, and validated against engine data collected from a 1.9L 4-Cylinder VW TDI engine modified to operate in HCCI mode. The engine was mapped between engine speeds of 900 and 3000 rpm, 1 and 3 bar intake pressure, and 0.2 and 0.4 equivalence ratio, resulting in loads between idle and 14.0 bar BMEP. Analysis of a number of trends for this specific engine map are presented, such as efficiency trends, effects of combustion phasing, intake temperature, engine load, engine speed, and operating strategy.
Technical Paper

Raison d'Être of Fuel Cells and Hydrogen Fuel for Automotive Powerplants

2004-03-08
2004-01-0788
The paper presents reportage of the debate on the topic expressed by its title that was held as a special session at the SAE 2003 Congress, supplemented by commentaries on its highlights. The debate brought to focus the fact that fuel cells are, indeed, superb powerplants for automobiles, while hydrogen is at the pinnacle of superiority as the most refined fuel. The problems that remained unresolved, are: (1) when fuel cells will be practically viable to replace internal combustion engines and (2) under what circumstances hydrogen, as the ultimate fuel, will be economically viable in view of its intrinsically high cost and hazards engendered by its extraordinary flammability and explosive tendency.
Technical Paper

Prospects for Combustion in Piston Engines

2002-03-04
2002-01-0999
Presented here is a reportage of the panel debate on the proposition: “Is there a future for internal combustion engines beyond the technologies of Otto and Diesel?,” held at the SAE 2001 Congress. This is preceded by a recount of all the panel discussions on the future of combustion in engines, which have taken place at the SAE Congresses since 1997. In a commentary following the reportage, a prospective view of the future is provided. It puts forth the concept that the technology, inherited over a hundred years ago from Otto and Diesel, by which the exothermic process of combustion is executed in an engine cylinder, can be advanced significantly by adopting the best that modern micro-electronic and MEMS technology can offer.
Technical Paper

Pressure Diagnostics of Closed System in a Direct Injection Spark Ignition Engine

2003-03-03
2003-01-0723
The sole purpose of combustion in a piston engine is to generate pressure in order to push the piston and produce work. Pressure diagnostics provides means to deduce data on the execution of the exothermic process of combustion in an engine cylinder from a measured pressure profile. Its task is that of an inverse problem: evaluation of the mechanism of a system from its measured output. The dynamic properties of the closed system in a piston engine are expressed in terms of a dynamic stage - the transition between the processes of compression and expansion. All the phenomena taking place in its course were analyzed in the predecessor of this paper, SAE 2002-01-0998. Here, on one hand, its concept is restricted to the purely dynamic effects, while on the other, the transformation of system components, taking place in the course of the exothermic chemical reaction to raise pressure, are taken into account by the exothermic stage.
Technical Paper

Potential for Closed Loop Air-Fuel Ratio Management of a Diesel Engine

1999-03-01
1999-01-0517
The potential for improving the efficiency of a heavy duty turbocharged diesel engine by closed loop Air-Fuel Ratio (AFR) management has been evaluated. Testing conducted on a 12 liter diesel engine, and subsequent data evaluation, has established the feasibility of controlling the performance through electronic control of air management hardware. Furthermore, the feasibility of using direct in-cylinder pressure measurement for control feedback has been established. A compact and robust fiber optics sensor for measuring real time in-cylinder pressure has been demonstrated on a test engine. A preferred method for reducing the cylinder pressure data for control feedback has been established for continued development.
Technical Paper

Nonlinear Algorithms for Simultaneous Speed Tracking and Air-Fuel Ratio Control in an Automobile Engine

1999-03-01
1999-01-0547
Simultaneous control of speed and air-fuel ratio in a six-cylinder automobile engine is studied. A three-state engine model including rotational, air intake and fuel intake dynamics is used for control design. Control design focuses on application of nonlinear control techniques, specifically sliding mode control. Controllers are designed for tracking speed profiles and regulating air-fuel mixture. Multiple-surface sliding control is shown to result in good speed tracking in simulation and experiment. The production fuel controller and an observer-based sliding controller are shown to result in the best fuel control during speed transients. A standard sliding fuel controller is shown to result in high amplitude deviations due to oxygen sensor time delay. The best combination of controllers is shown to be the multiple-surface sliding speed controller and the observer-based fuel controller.
Technical Paper

Model for Control of Combustion in a Piston Engine

2006-04-03
2006-01-0401
Significant improvement of engine performance can be achieved by ushering in a micro-electronic system to control the execution of combustion - an exothermic process whose sole purpose is to generate pressure. Hence, the primary feedback for the controller is provided by a pressure transducer. The activators are piezo-electrically activated pintle valves of MEMS type. The task of the micro-electronic processor is to provide an accurate feed-forward signal for the actuators on the basis of the information obtained from the feedback signal, within a time interval between consecutive cycles. Furnished here for this purpose is an algorithm for an interface module between the pressure sensor and the governor. Concomitantly, the gains thus attainable in the reduction of fuel consumption and curtailment of pollutant formation are thereby assessed. The implementation of this method of approach is illustrated by application to a HCCI engine.
Technical Paper

Model and Control of Heat Release in Engines

1996-02-01
960601
The concept of the paper stems from the premise that the process of “heat release” in engines involves in essence the evolution and deposition of exothermic energy generated by combustion-events that can be governed promptly by a feedback, adaptive micro-electronic control system. The key to its realization is the principle of DISC (Direct Injection Stratified Charge) engine, implemented by a multi-jet system. The background and the salient features of such a system, referred to as a CCE (Controlled Combustion Engine), have been described in a companion paper (SAE 951961). Presented here are fundamental aspects of the model of the exothermic process and the intrinsic properties of its control system.
Technical Paper

Meeting Both ZEV and PNGV Goals with a Hybrid Electric Vehicle - An Exploration

1996-08-01
961718
This paper is written to provide information on the fuel efficiency, emissions and energy cost of vehicles ranging from a pure electric (ZEV) to gasoline hybrid vehicles with electric range varying from 30 mi (50km) to 100 mi (160km). The Federal government s PNGV and CARB s ZEV have different goals, this paper explores some possibilities for hybrid-electric vehicle designs to meet both goals with existing technologies and batteries. The SAE/CARB testing procedures for determining energy and emission performance for EV and HEV and CARB s HEV ruling for ZEV credit are also critically evaluated. This paper intends to clarify some confusion over the comparison, discussion and design of electric- hybrid- and conventional- vehicles as well.
Technical Paper

Jet Plume Injection and Combustion

1992-02-01
920414
The concept of JPIC (Jet Plume Injection and Combustion) is introduced as a radical refinement of DISC (Direct Injection Stratified Charge). The system for its implementation consists of a fuel injector and a PJC (Pulsed Jet Combustion) generator (described in our previous papers) connected in series via a check valve. In operation, rich air-fuel mixture is admitted thereby first to a lean charge in the cylinder, forming a turbulent jet plume, and, thereupon, the process of combustion is executed using a pulsed jet of combustion products created upon ignition, by means of a conventional spark discharge, of the mixture remaining in the cavity of the PJC generator. Charge stratification thus obtained affects not only chemical composition, but also the scale and intensity of turbulence. The latter is, under such circumstances, associated with a significant amount of entrainment due to the large scale vortex structure of the turbulent plume.
Technical Paper

Influence of Charge Dilution on the Dynamic Stage of Combustion in a Diesel Engine

2001-03-05
2001-01-0551
A study of the influence of dilution, attained by air excess, upon the dynamic stage of combustion - the nucleus of a work producing cycle - in a diesel engine, is reported as a sequel of SAE 2000-01-0203. While the latter has been restricted to variation in dilution obtained by bleeding air compressed by the supercharger, here the scope of engine tests was expanded by incorporating an additional stage of compression. Besides revealing the mechanism of the dynamic stage, the paper demonstrates that its effectiveness is a linear function of the air excess coefficient, irrespectively how it is attained.
Journal Article

Experimental Investigation of Channel Aspect Ratio on Interdigitated PEMFC Performance

2014-04-01
2014-01-1828
Novel water management and reactant distribution strategies are critical to next generation polymer electrolyte membrane fuel cell systems (PEMFCs). Improving these strategies in PEMFCs leads to higher power density and reduced stack size for vehicle applications, which reduces weight and improves the price competitiveness of these systems. Interdigitated flow fields induce convective transport (cross flow) through the porous GDL between adjacent channels and are superior at water removal beneath land areas, which can lead to higher cell performance. However, the head loss due to flow, among other factors, may cause cross flow maldistribution of reactants down the channel. Such maldistribution may lead to areas of low or areas of excess cross flow. This, in turn, can cause areas of low oxygen concentration and water build up, and therefore higher pressure losses and uneven membrane hydration, all of which reduce overall cell performance.
Journal Article

Evaluation and Modification of Constant Volume Sampler Based Procedure for Plug-in Hybrid Electric Vehicle Testing

2011-08-30
2011-01-1750
Plug-in hybrid electric vehicles (PHVs) consume both fossil fuel and grid electricity, which imposes emission testing challenges on the current constant volume sampler (CVS) test method. One reason is that in the charge-depleting cycle, PHVs having all-electric range operate the engine for a small portion of the traction energy need, causing the CVS to overdilute the exhaust gas. The other reason is that the dilution factor (DF) in the EPA calculation has an error caused by ignoring the CO₂ concentration in ambient air. This paper evaluates these challenges by testing a Toyota PHV on the industry standard CVS system combined with additional continuous sampling methodology for continuous diluents, smooth approach orifice (SAO) measurement for ambient air flow, and fuel flow meter (FFM) measurement for fuel consumption. The current EPA DF can produce an error resulting in higher mass calculation.
Technical Paper

Evaluating Particulate Emissions from a Flexible Fuel Vehicle with Direct Injection when Operated on Ethanol and Iso-butanol Blends

2014-10-13
2014-01-2768
The relationship between ethanol and iso-butanol fuel concentrations and vehicle particulate matter emissions was investigated. This study utilized a gasoline direct injection (GDI) flexible fuel vehicle (FFV) with wall-guided fueling system tested with four fuels, including E10, E51, E83, and an iso-butanol blend at a proportion of 55% by volume. Emission measurements were conducted over the Federal Test Procedure (FTP) driving cycle on a chassis dynamometer with an emphasis on the physical and chemical characterization of particulate matter (PM) emissions. The results indicated that the addition of higher ethanol blends and the iso-butanol blend resulted in large reductions in PM mass, soot, and total and solid particle number emissions. PM emissions for the baseline E10 fuel were characterized by a higher fraction of elemental carbon (EC), whereas the PM emissions for the higher ethanol blends were more organic carbon (OC) in nature.
Technical Paper

Emissions and Redox Activity of Biodiesel Blends Obtained from Different Feedstocks from a Heavy-Duty Vehicle Equipped with DPF/SCR Aftertreatment and a Heavy-Duty Vehicle without Control Aftertreatment

2014-04-01
2014-01-1400
The primary objective of this study was to evaluate the impact of three different biodiesel feedstocks on emissions compared to a baseline CARB ULSD with two heavy-duty trucks equipped with and without aftertreatment technologies. The biodiesels included a soybean oil methyl ester (SME), a waste cooking oil methyl ester (WCO), and a methyl ester obtained from animal fat (AFME), blended at a 50% level by volume with the CARB diesel. The vehicles were equipped with a 2010 Cummins ISX-15 engine with a selective catalytic reduction (SCR), diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF) and with a 2002 Cummins ISX-450 engine. Both vehicles were tested over the Urban Dynamometer Driving Schedule (UDDS) on a heavy-duty chassis dynamometer. For this study, nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO2), total hydrocarbons (THC), methane (CH4), non-methane hydrocarbons (NMHC), and particulate matter (PM) were measured.
Journal Article

Electrical Architecture Optimization and Selection - Cost Minimization via Wire Routing and Wire Sizing

2014-04-01
2014-01-0320
In this paper, we propose algorithms for cost minimization of physical wires that are used to connect electronic devices in the vehicle. The wiring cost is one of the most important drivers of electrical architecture selection. Our algorithms perform wire routing from a source device to a destination device through harnesses, by selecting the optimized wire size. In addition, we provide optimized splice allocation with limited constraints. Based on the algorithms, we develop a tool which is integrated into an off-the-shelf optimization and workflow system-level design tool. The algorithms and the tool provide an efficient, flexible, scalable, and maintainable approach for cost analysis and architecture selection.
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