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The high load limit of a boosted homogeneous-charge-compression-ignition (HCCI) engine operating on negative-valve-overlap (NVO) was assessed. When operating under stoichiometric condition with no external dilution, the load, as measured by the net indicated mean effective pressure (NIMEP), increased with increase in manifold absolute pressure (MAP), and with decrease in trapped amount of residual gas. The maximum pressure rise rate (MPRR), however, also increased correspondingly. When the MAP and the amount of residual gas were adjusted so that the engine operating point could be held at a constant MPRR value, the NIMEP increased with the simultaneous decrease in MAP and residual until the misfire limit was reached. Therefore if a MPRR ceiling is imposed, the high load limit of an HCCI engine is at the intersection of the constraining MPRR line and the misfire line.

Mechanisms of NH₃ generation using LNT-like catalysts have been studied in a bench reactor over a wide range of temperatures, flow rates, reformer catalyst types and synthetic exhaust-gas compositions. The experiments showed that the on board production of sufficient quantities of ammonia on board for SCR operation appeared feasible, and the results identified the range of conditions for the efficient generation of ammonia. In addition, the effects of reformer catalysts using the water-gas-shift reaction as an in-situ source of the required hydrogen for the reactions are also illustrated. Computations of the NH₃ and NOx kinetics have also been carried out and are presented. Design and impregnation of the SCR catalyst in proximity to the ammonia source is the next logical step. A heated synthetic-exhaust gas flow bench was used for the experiments under carefully controlled simulated exhaust compositions.

The increasing use of diesel and gasoline particulate filters requires advanced on-board diagnostics (OBD) to prevent and detect filter failures and malfunctions. Early detection of upstream (engine-out) malfunctions is paramount to preventing irreversible damage to downstream aftertreatment system components. Such early detection can mitigate the failure of the particulate filter resulting in the escape of emissions exceeding permissible limits and extend the component life. However, despite best efforts at early detection and filter failure prevention, the OBD system must also be able to detect filter failures when they occur. In this study, radio frequency (RF) sensors were used to directly monitor the particulate filter state of health for both gasoline particulate filter (GPF) and diesel particulate filter (DPF) applications.

The effects of cooled exhaust gas recirculation (EGR) on a boosted direct-injection (DI) spark ignition (SI) engine operating at stoichiometric equivalence ratio, gross indicated mean effective pressure of 14-18 bar, and speed of 1500-2500 rpm, are studied under constant fuel condition at each operating point. In the presence of EGR, burn durations are longer and combustion is more retard. At the same combustion phasing, the indicated specific fuel consumption improves because of a decrease in heat loss and an increase in the specific heat ratio. The knock limited spark advance increases substantially with EGR. This increase is due partly to a slower combustion which is equivalent to a spark retard, as manifested by a retarded value of the 50% burn point (CA50), and due partly to a slower ignition chemistry of the diluted charge, as manifested by the knock limited spark advance to beyond the value offered by the retarded CA50.

This paper explores the combined effects of boosting, intake air temperature, trapped residual gas fraction, and dilution on the Maximum Pressure Rise Rate (MPRR) in a boosted single cylinder gasoline HCCI engine with combustion controlled by negative valve overlap. Dilutions by both air and by cooled EGR were used. Because of the sensitivity of MPRR to boost, the MPRR constrained maximum load (as measured by the NIMEP) did not necessarily increase with boosting. At the same intake temperature and trapped residual gas fraction, dilution by recirculated burn gas was effective in reducing the MPRR, but dilution by air increased the value of MPRR. The dependence of MPRR on the operating condition was interpreted successfully by a simple thermodynamic analysis that related the MPRR value to the volumetric heat release rate.

The combustion process after auto-ignition is investigated. Depending on the non-uniformity of the end gas, auto-ignition could initiate a flame, produce pressure waves that excite the engine structure (acoustic knock), or result in detonation (normal or developing). For the “acoustic knock” mode, a knock intensity (KI) is defined as the pressure oscillation amplitude. The KI values over different cycles under a fixed operating condition are observed to have a log-normal distribution. When the operating condition is changed (over different values of λ, EGR, and spark timing), the mean (μ) of log (KI/GIMEP) decreases linearly with the correlation-based ignition delay calculated using the knock-point end gas condition of the mean cycle. The standard deviation σ of log(KI/GIMEP) is approximately a constant, at 0.63. The values of μ and σ thus allow a statistical description of knock from the deterministic calculation of the ignition delay using the mean cycle properties

In this paper we investigate the optimal forming of conical cups of AL 2008-T4 through the use of real-time process control. We consider a flat, frictional binder the force of which can be determined precisely through closed-loop control. Initially the force is held constant throughout the forming of the cup, and various levels of force are tested experimentally and with numerical simulation. Excellent agreement between experiment and simulation is observed. The effects of binder force on cup shape, thickness distribution, failure mode and cup failure height are investigated, and an “optimal” constant binder force is determined. For this optimal case, the corresponding punch force is recorded as a function of punch displacement and is used in subsequent closed-loop control experiments. In addition to the constant force test, a trial variable binder force test was performed to extend the failure height beyond that obtained using the “optimal” constant force level.

Draw beads are widely utilized as a mechanism for providing proper restraining force to a sheet in a forming operation. In this paper, numerical simulations using the nonlinear finite element method are conducted to model the process of drawing a sheet through various draw bead configurations to study the mechanics of draw bead restraint. By examing the sensitivity of the draw bead restraining force due to the change of the draw bead penetration, the work shows that the penetration has the potential to be a very good element for varying and controlling restraining force during the process. A closed-loop feedback control of draw bead penetration using a proportional-integral controller is achieved by the combination of the original finite element simulation and a special element which links penetration to a pre-defined restraining force trajectory.

This paper presents a numerical model of the rotational and lateral dynamics of the piston (secondary motion) and piston slap in mixed lubrication. Piston dynamic behavior, frictional and impact forces are predicted as functions of crank angle. The model considers piston skirt surface waviness, roughness, skirt profile, thermal and mechanical deformations. The model considers partially-flooded skirt and calculates the pressure distributions and friction in the piston skirt region for both hydrodynamic and boundary lubrication. Model predictions are compared with measurements of piston position using gap sensors in a single-cylinder engine and the comparison between theory and measurement shows remarkable agreement.

A model has been developed which predicts engine-out hydrocarbon (HC) emissions for spark-ignition engines. The model consists of a set of scaling laws that describe the individual processes that contribute to HC emissions. The model inputs are the critical engine design and operating variables. This set of individual process scaling relations was then calibrated using production spark-ignition engine data at a fixed light-load operating point. The data base consisted of engine-out HC emissions from two-valve and four-valve engine designs with variations in spark timing, valve timing, coolant temperature, crevice volume, and EGR, for five different engines. The model was calibrated separately for the three different engines to accommodate differences in engine design details and to determine the relative magnitudes of each of the major sources. A good fit to this database was obtained.

Cranking and startup fuel control has become increasingly important due to ever tightening emission requirements. Additionally, engine-off strategies during idle will require substantially more engine startup events with the associated need for very clean starts. Thus, knowledge of an engine's Air-Fuel Ratio (AFR) during its early cycles is necessary in order to optimize cranking and startup fueling. This paper examines and compares two methods of measuring an engine's AFR during engine startup (approximately the first second of operation); an in-cylinder technique using a Fast Flame Ionization Detector (FFID) and the conventional exhaust based Universal Exhaust Gas Oxygen (UEGO) sensor method. Engine starts using a Ford Zetec engine were performed at three different temperatures (0, 20 and 90 C) as well as different initial engine starting positions.

The knocking characteristics of several fuels are studied using a single cylinder test engine with variations in key engine operating parameters. Compression ratio, spark advance, fuel equivalence ratio, exhaust gas recirculation, engine speed, charge inlet pressure and charge inlet temperature were varied to yield a range of engine cylinder pressure-temperature histories as the base for this study. The fuels studied include three reference fuels containing isooctane and heptane with isooctane volume percents of 80, 90 and 100. Two wide boiling range gasolines were also studied. A number of empirical relationships for autoignition times of isooctane and heptane blends are employed in conjunction with the experimentally obtained pressure-temperature histories to predict onset of knock. The accuracies of the predictions with respect to the experimentally determined knock points are discussed.

One of the goals of designing engineering systems is to maximize the system's reliability. A reliable system must satisfy its functional requirements without failure throughout its intended lifecycle. The typical means to achieve a desirable level of reliability is through preventive maintenance of a system; however, this involves cost. A more fundamental approach to the problem is to maximize the system's reliability by preventing failures from occurring. A key question is to find mechanisms (and the means to implement them into a system) that will prevent its system range from going out of the design range. Functional periodicity is a means to achieve this goal. Three examples are discussed to illustrate the concept. In the new electrical connector design, it is the geometric functional periodicity provided by the woven wire structure. In the case of integrated manufacturing systems, it is the periodicity in scheduling of the robot motion.

Eigenvalues of a simple rotating flexible disk-shaft system are obtained using different methods. The shaft is supported radially by non-rigid bearings, while the disk is situated at one end of the shaft. Eigenvalues from a finite element and a multi-body dynamic tool are compared against an established analytical formulation. The Campbell diagram based on natural frequencies obtained from the tools differ from the analytical values because of oversimplification in the analytical model. Later, detailed whirl analysis is performed using AVL Excite multi-body tool that includes understanding forward and reverse whirls in absolute and relative coordinate systems and their relationships. Responses to periodic force and base excitations at a constant rotational speed of the shaft are obtained and a modified Campbell diagram based on this is developed. Whirl of the center of the disk is plotted as an orbital or phase plot and its rotational direction noted.

Gear profile deviation is the difference in gear tooth profile from the ideal involute geometry. There are many causes that result in the deviation. Deflection under load, manufacturing, and thermal effects are some of the well-known causes that have been reported to cause deviation of the gear tooth profile. The profile deviation caused by gear tooth profile deformation due to interference-fit assembly has not been discussed previously. Engine timing gear trains, transmission gearboxes, and wind turbine gearboxes are known to use interference-fit to attach the gear to the rotating shaft. This paper discusses the interference-fit joint design and the mechanism of tooth profile deformation due to the interference-fit assembly in gear trains. A new analytical method to calculate the profile slope deviation change due to interference-assembly of parallel axis spur gears is presented.

Reliable means for on-board detection of particulate filter failures or malfunctions are needed to meet diagnostics (OBD) requirements. Detecting these failures, which result in tailpipe particulate matter (PM) emissions exceeding the OBD limit, over all operating conditions is challenging. Current approaches employ differential pressure sensors and downstream PM sensors, in combination with particulate filter and engine-out soot models. These conventional monitors typically operate over narrowly-defined time windows and do not provide a direct measure of the filter’s state of health. In contrast, radio frequency (RF) sensors, which transmit a wireless signal through the filter substrate provide a direct means for interrogating the condition of the filter itself.

With the recent advancement in sensing and controller technologies architecture design of an autonomous driving system becomes an important issue. Researchers have been developing different sensors and data processing technologies to solve the issues associated with fast processing, diverse weather, reliability, long distance recognition performance, etc. Necessary considerations of diverse traffic situations and safety factors of autonomous driving have also increased the complexity of embedded software as well as architecture of autonomous driving. In these circumstances, there are almost countless numbers of possible architecture designs. However, these design considerations have significant impacts on cost, controllability, and system reliability. Thus, it is crucial for the designers to make a challenging and critical design decision under several uncertainties during the conceptual design phase.

Three-piece oil control rings (TPOCR) are widely used in the majority of modern gasoline engines and they are critical for lubricant regulation and friction reduction. Despite their omnipresence, the TPOCRs’ motion and sealing mechanisms are not well studied. With stricter emission standards, gasoline engines are required to maintain lower oil consumption limits, since particulate emissions are strongly correlated with lubricant oil emissions. This piqued our interest in building a numerical model coupling TPOCR dynamics and oil transport to explain the physical mechanisms. In this work, a 2D dynamics model of all three pieces of the ring is built as the main frame. Oil transport in different zones are coupled into the dynamics model. Specifically, two mass-conserved fluid sub-models predict the oil movement between rail liner interface and rail groove clearance to capture the potential oil leakage through TPOCR. The model is applied on a 2D laser induced fluorescence (2D-LIF) engine.

We report on a feasibility study of an optical micro-electro-mechanical systems (MEMS) flow sensor to measure flow rate using Moiré fringe displacement of a floating element. Due to constraints on weight, power, and size for space environmental systems, the development of sensor components that minimize the equivalent systems mass (ESM) while maintaining or exceeding required specifications is highly desirable. A feature of the optical detection method is a physical separation of electrical components from the flow stream. The geometric Moiré fringe shift optically amplifies small displacements by the ratio of the fringe pitch to the movable grating pitch that is detected using an external CCD imager, providing an electrically isolated, robust, direct scheme for detecting flow from shear stress induced displacement.