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The paper investigates the impact of the drive cycle choice on the Plug-in Hybrid Electric Vehicle (PHEV) design, and particularly the selection of component sizes. Models of representative Power-Split and Series PHEVs have been built and validated first. Then, the performance and energy/power usage metrics were obtained by simulating the vehicle behavior over real-world (naturalistic) drive cycles recorded during Field Operational Tests in South East Michigan. The PHEV performance predictions obtained with real-world driving cycles are in stark contrast to the results obtained by using a sequence of repeated federal drive cycles. Longer commutes require much higher peak power and consume much greater amount of energy per mile than EPA UDDS or HWFET cycle. The second part of the paper investigates the sensitivities of the PHEV attributes, such as the charge depleting range and the fuel economy in the charge sustaining mode, to component size variations.

A series hydraulic hybrid concept (SHHV) has been explored as a potential pathway to an ultra-efficient city vehicle. Intended markets would be congested metropolitan areas, particularly in developing countries. The target fuel economy was ~100 mpg or 2.4 l/100km in city driving. Such an ambitious target requires multiple measures, i.e. low mass, favorable aerodynamics and ultra-efficient powertrain. The series hydraulic hybrid powertrain has been designed and analyzed for the selected light and aerodynamic platform with the expectation that (i) series configuration will maximize opportunities for regeneration and optimization of engine operation, (ii) inherent high power density of hydraulic propulsion and storage components will yield small, low-cost components, and (iii) high efficiency and high power limits for accumulator charging/discharging will enable very effective regeneration.

Extending the operating range of the gasoline HCCI engine is essential for achieving desired fuel economy improvements at the vehicle level, and it requires deep understanding of the thermal conditions in the cylinder. Combustion chamber deposits (CCD) have been previously shown to have direct impact on near-wall phenomena and burn rates in the HCCI engine. Hence, the objectives of this work are to characterize thermal properties of deposits in a gasoline HCCI engine and provide foundation for understanding the nature of their impact on autoignition and combustion. The investigation was performed using a single-cylinder engine with re-induction of exhaust instrumented with fast-response thermocouples on the piston top and the cylinder head surface. The measured instantaneous temperature profiles changed as the deposits grew on top of the hot-junctions.

Using dynamic causal models for a direct-hydrogen fuel cell and a DC/DC converter we design decentralized and multivariable controllers regulating the bus voltage and preventing fuel cell oxygen starvation. Various controller gains are used to span the fuel cell operation from load-following to load-leveling, and hence, determine the required fuel cell-battery sizing (hybridization level) and the associated trends in the fuel economy. Our results provide insight on the strategy and calibration of a fuel cell hybrid electric vehicle with no need for a supervisory controller that typically depends on optimal power split during a specific driving cycle. The proposed controllers directly manipulate actuator commands, such as the DC/DC converter duty cycle, and achieve a desired power split. The controllers are demonstrated through simulation of a compact sedan using a mild and an aggressive driving cycle.

Medium trucks constitute a large market segment of the commercial transportation sector, and are also used widely for military tactical operations. Recent technological advances in hybrid powertrains and fuel cell auxiliary power units have enabled design alternatives that can improve fuel economy and reduce emissions dramatically. However, deterministic design optimization of these configurations may yield designs that are optimal with respect to performance but raise concerns regarding the reliability of achieving that performance over lifetime. In this article we identify and quantify uncertainties due to modeling approximations or incomplete information. We then model their propagation using Monte Carlo simulation and perform sensitivity analysis to isolate statistically significant uncertainties. Finally, we formulate and solve a series of reliability-based optimization problems and quantify tradeoffs between optimality and reliability.

Two methods for mitigating unacceptably high HCCI heat-release rates are investigated and compared in this combined experimental/CFD work. Retarding the combustion phasing by decreasing the intake temperature is found to have good potential for smoothing heat-release rates and reducing engine knock. There are at least three reasons for this: 1) lower combustion temperatures, 2) less pressure rise when the combustion is occurring during the expansion stroke, and 3) the natural thermal stratification increases around TDC. However, overly retarded combustion leads to unstable operation with partial-burn cycles resulting in high IMEPg variations and increased emissions. Enhanced natural thermal stratification by increased heat-transfer rates was explored by lowering the coolant temperature from 100 to 50°C. This strategy substantially decreased the heat-release rates and lowered the knocking intensity under certain conditions.

Automotive manufacturers are continually pushing for reduced cost, increased fuel economy, lower emissions and improved performance. Magnesium is the lightest structural metal and has therefore enjoyed a double-digit annual growth in automotive applications since 1990, aimed at reducing vehicle platform weights to increase fuel economy. Nevertheless the progress of magnesium as an alternative lightweight structural material (compared to aluminum, engineered plastics and high alloy steels) is being impeded by the lack of published alloy properties and general knowledge of the material. Thixomat, Inc. is conducting independent fundamental studies to measure the influence of Thixomolding® process parameters on a variety of physical and mechanical properties for injection molded magnesium alloys. Determination of conventional mechanical properties are being complemented with fatigue behavior studies using new ultrasonic fatigue instrumentation at the University of Michigan.

Today, in a typical car, electromechanical components contribute roughly 30% to the total vehicle cost with Embedded Real Time Systems (ERTS) responsible for roughly 80% of major controls functions. ERTS units influence the quality of the end product, and thus customer satisfaction. Quality means conformance to requirements in terms of functionality, usability, reliability, performance and supportability. In software design terms, it means traceability, portability, interoperability, and reusability. This paper introduces a MDA approach for building portable, interoperable, and reusable software systems. Through architectural separation of concerns, MDA addresses quality from the perspectives of the customer and software design. To illustrate the effectiveness of MDA, we present a software design of an Engine Idle Speed Control Unit.

The purpose of this study was to determine the effect of the partial pressure of O2 in the intake charge of an I.D.I. diesel engine on the various operating parameters and the exhaust emissions. The oxygen content in the intake was varied between 21% and 40% by volume. Engine performance and emissions were evaluated at constant engine speed and injection timing while fueling was varied. The research revealed that enriching the intake air with oxygen led to a large decrease in ignition delay and reduced combustion noise. The fuel economy, the power output and the exhaust temperature remained almost constant. HC and CO emissions decreased and smoke levels dropped substantially, while NOX emissions increased pro-rata with the O2 added. Theoretical analysis using the Zel’dovich kinetics showed that nitric oxide emissions are sensitive to “mean NO-formation temperature” and the combustion duration associated with this temperature, and, to a lesser extent, the atomic oxygen concentration.