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The Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model incorporated fuel economy and electricity use of alternative fuel/vehicle systems simulated by the Powertrain System Analysis Toolkit (PSAT) to conduct a well-to-wheels (WTW) analysis of energy use and greenhouse gas (GHG) emissions of plug-in hybrid electric vehicles (PHEVs). Based on PSAT simulations of the blended charge depleting (CD) operation, grid electricity accounted for a share of the vehicle’s total energy use ranging from 6% for PHEV 10 to 24% for PHEV 40 based on CD vehicle mile traveled (VMT) shares of 23% and 63%, respectively. Besides fuel economy of PHEVs and type of on-board fuel, the type of electricity generation mix impacted the WTW results of PHEVs, especially GHG emissions.

Toyota Motor Corporation has developed the new compact-class hybrid vehicle (HV). This vehicle incorporates Toyota Hybrid System II (THS-II) to improve fuel efficiency. For this system we have developed a new power control unit (PCU) that features size reduction, light weight, and high efficiency. We have also improved the ability to mass produce these units with the expectation of rapid popularization of HV. The PCU, which plays an important role in THS-II, is our main focus in this paper. Its development is described.

Engine operating strategies typically geared towards higher fuel economy and lower NOx widely affect exhaust composition and temperature. These exhaust variables critically drive the performance of After Treatment (AT) components, and hence should guide their screening and selection. Towards this end, the effect of H2 level in diesel exhaust on the performance of a Diesel Oxidation Catalyst (DOC) was studied using flow reactor experiments, vehicle emission measurements and mathematical models. Vehicle chassis dynamometer data showed that exhaust from light-duty and heavy-duty diesel trucks contained very little to almost no H2 (FTP average CO/H2 ∼ 40 to 70) as compared to that of a gasoline car exhaust (FTP average CO/H2 ∼ 3). Two identical flow reactor experiments, one with H2 (at CO/H2 ∼ 3) and another with no H2 in the feed were designed to screen DOCs under simulated feed gas conditions that mimicked these two extremes in the exhaust H2 levels.

Selective catalytic reduction (SCR) is allowing diesel engines to reach NOx emission levels which are unachievable in-cylinder. This technology is still evolving, and new catalyst formulations which provide higher performance and greater durability continue to be developed. Usually, their performance is measured on a flow reactor using ammonia as the reductant. However, in mobile applications a urea-water solution is used instead, and urea decomposition by thermolysis and hydrolysis provides the required ammonia to the catalyst. It is well known that urea decomposition is incomplete by the inlet face of the converter, and this is at least one reason why on-engine performance is generally lower than would be expected from reactor tests. Previous modeling of urea-water droplets has focused on developing detailed sub-models that can be implemented into computational fluid dynamics (CFD) codes.

Wet clutches are widely used in automotive systems. They are essential parts of automatic transmissions, modern All-Wheel-Drive systems or dual-clutch transmissions. Regardless of the area of application, a good knowledge of clutch friction behaviors is crucial for the clutch control system development. This paper considers two important factors of the wet clutch dynamics: coefficient of friction behavior and thermal dynamics. An Active Limited Slip Differential wet clutch with carbon fiber-based friction lining material is experimentally characterized by using a precise wet clutch setup. The characterization of the coefficient of friction behavior includes influence of clutch slip speed, applied force, and friction surface temperature. The clutch thermal dynamics is characterized based on the heat power balance law applied to the clutch separator plate with a variable heat transfer coefficient. The results of the thermal model experimental validation are presented, as well.

Diesel injection parameters effect on liquid-phase diesel spray penetration after the end-of-injection (EOI) is investigated in a constant-volume chamber over a range of ambient and injector conditions typical of a diesel engine. Our past work showed that the maximum liquid penetration length of a diesel spray may recede towards the injector after EOI at some conditions. Analysis employing a transient jet entrainment model showed that increased fuel-ambient mixing occurs during the fuel-injection-rate ramp-down as increased ambient-entrainment rates progress downstream (i.e. the entrainment wave), permitting complete fuel vaporization at distances closer to the injector than the quasi-steady liquid length. To clarify the liquid-length recession process, in this study we report Mie-scatter imaging results near EOI over a range of injection pressure, nozzle size, fuel type, and rate-of-injection shape. We then use a transient jet entrainment model for detailed analysis.

The local equivalence ratio, Φ, was measured in fuel jets using laser-induced spontaneous Raman scattering in an optical heavy duty diesel engine. The measurements were performed at 1200 rpm and quarter load (6 bar IMEP). The objective was to study factors influencing soot formation, such as gas entrainment and lift-off position, and to find correlations with engine-out particulate matter (PM) levels. The effects of nozzle hole size, injection pressure, inlet oxygen concentration, and ambient density at TDC were studied. The position of the lift–off region was determined from OH chemiluminescence images of the flame. The liquid penetration length was measured with Mie scattering to ensure that the Raman measurement was performed in the gaseous part of the spray. The local Φ value was successfully measured inside a fuel jet. A surprisingly low correlation coefficient between engine-out PM and the local Φ in the reaction zone were observed.

Recent measurements in transient diesel jets have shown that fuel in the wake of the injection pulse mixes with ambient gases more rapidly than in a steady jet. This rapid mixing after the end of injection (EOI) can create fuel-lean regions near the fuel injector. These lean regions may not burn to completion for conditions where autoignition occurs after EOI, as is typical of low-temperature combustion (LTC) diesel engines. In this study, transient diesel jets are analyzed using a simple one-dimensional jet model. The model predicts that after EOI, a region of increased entrainment, termed the “entrainment wave,” travels downstream at twice the initial jet propagation rate. The entrainment wave increases mixing by up to a factor of three. This entrainment wave is not specific to LTC jets, but rather it is important for both conventional diesel combustion and LTC conditions.

A thorough understanding of vehicle exhaust aftertreatment system performance requires time-resolved emissions measurements that accurately follow driving transients, and that are correctly time-aligned with exhaust temperature and flow measurements. The transient response of conventional gas analyzers is characterized by both a time delay and an attenuation of high-frequency signal components. The distortion that this imposes on transient emissions measurements causes significant errors in instantaneous calculations of aftertreatment system efficiency, and thus in modal mass analysis. This creates difficulties in mathematical modeling of emissions system performance and in optimization of powertrain control strategies, leading to suboptimal aftertreatment system designs. A mathematical method is presented which improves the response time of emissions measurements. This begins with development of a model of gas transport and mixing within the sampling and measurement system.

Spray-guided gasoline direct injection SI engines attract as one of new generation lean-burn engines to promise CO2 reduction. These typically adopt “narrow-spacing” concept in which an injector is centrally mounted close to a spark plug. Therefore, geometric targets of the fuel spray and a position of the spark plug have to be exactly limited to maintain a proper mixture in the spark gap. In addition, the stable combustion window is narrow because the spark ignition is limited in a short time during and immediately after the injection. These spatial and temporal restrictions involve some intractable problems concerning the combustion robustness due to the complicate phenomena around the spark plug. The local mixture preparation near the spark plug significantly depends on the spray-induced charge motion. The intense flow induced by the motion blows out and stretches the spark, thereby affecting the spark discharge performance.

Empirical models for engine-out oxides of Nitrogen (NOx) and smoke emissions have been developed for the purpose of minimizing transient emissions while maintaining transient response. Three major issues have been addressed: data acquisition, data processing and modeling method. Real and virtual transient parameters have been identified for acquisition. Accounting for the phase shift between transient engine events and transient emission measurements has been shown to be very important to the quality of model predictions. Several methods have been employed to account for the transient transport delays and sensor lags which constitute the phase shift. Finally several different empirical modeling methods have been used to determine the most suitable modeling method for transient emissions. These modeling methods include several kinds of neural networks, global regression and localized regression.

A production version of a V-8 engine was redesigned to run on partially premixed charge compression ignition (PCCI) combustion mode with conventional diesel fuel. The objective of the PCCI combustion experiments was to obtain low engine-out nitrogen oxide (NOx) and after-treatment tolerant soot emission level. Two fuel injection strategies were used during the PCCI combustion experiments: a) pilot-with-main injection strategy (Pil-M), b) pilot-with-main-and-post (PMP) injection strategy. In the Pil-M injection strategy, a significant fraction of the fuel was delivered early during the compression stroke. The early pilot helped to prepare a lean-mixture of enhanced homogeneity before the combustion was initiated. The combustion of this pilot injection followed by the main combustion helped to reduce soot for a constant NOx value. The pilot-injection timing and quantity had to be selected appropriately to retain the fuel-efficiency.

Quantitative planar laser-induced fluorescence (PLIF) of gaseous acetone as a fuel-tracer has been used in an optically accessible engine, fueled by direct hydrogen injection. The purpose of this article is to assess the accuracy and precision of the measurement and the associated data reduction procedures. A detailed description of the acetone seeding system is given as well. The key features of the experiment are a high-pressure bubbler saturating the hydrogen fuel with acetone vapor, direct injection into an optical engine, excitation of acetone fluorescence with an Nd:YAG laser at 266 nm, and detection of the resulting fluorescence by an unintensified camera. Key steps in the quantification of the single-shot imaging data are an in-situ calibration and a correction for the effect of local temperature on the fluorescence measurement.

The upcoming Euro VI emission legislation for Heavy Duty Diesel engines can be complied with by using a combination of a wall flow DPF and a UREA SCR-system. This paper describes investigations of NOx and PM reduction by a combination of SCR-catalyst and an (uncoated) Diesel particulate filter (DPF), performed on a fully transient heavy-duty test bench. Soot loading and passive regeneration of the DPF for different configurations of both components and active regeneration by fuel injection into the exhaust gas line were investigated. The impact of DPF on SCR-catalyst as well as SCR-catalyst impact on DPF was analyzed in terms of NOx-conversion and regeneration efficiency of the filter under steady-state and transient operating conditions. The NOx-conversions for the configuration SCR-catalyst in front of DPF were higher for all operating conditions than for the combination DPF in front of SCR-catalyst.

A promising SCR-only solution is presented to meet post-2010 NOx emission targets for heavy duty applications. The proposed concept is based on an engine from a EURO IV SCR application, which is considered optimal with respect to fuel economy and costs. The addition of advanced SCR after treatment comprising a standard and a close-coupled SCR catalyst offers a feasible emission solution, especially suited for EURO VI. In this paper, results of a simulation study are presented. This study concentrates on optimizing SCR deNOx performance. Simulation results of cold start FTP and WHTC test cycles are presented to demonstrate the potential of the close-coupled SCR concept. Comparison with measured engine out emissions of an EGR engine shows that a close-coupled SCR catalyst potentially has NOx reduction performance as good as EGR. Practical issues regarding the use of an SCR catalyst in close-coupled position will be addressed, as well as engine and exhaust layout.

A laboratory study was performed to optimize a zoned configuration of an iron (Fe) SCR catalyst and a copper (Cu) SCR catalyst in order to provide high NOx conversion at lean A/F ratios over a broad range of temperature for diesel and lean-burn gasoline applications. With an optimized space velocity of 8,300 hr-1, a 67% (by volume) Fe section followed by a 33% Cu section provided at least 80% NOx conversion from approximately 230°C to 640°C when evaluated with 500 ppm NO and NH3. To improve the lean lightoff performance of the SCR catalyst system during a cold start, a Cu SCR catalyst that was 1/4 as long as the rear Cu SCR catalyst was placed in front of the Fe SCR catalyst. When evaluated with an excess of NH3 (NH3/NO ratio of 2.2), the Cu+Fe+Cu SCR system had significantly improved lightoff performance relative to the Fe+Cu SCR system, although the front Cu SCR catalyst did decrease the NOx conversion at temperatures above 475°C by oxidizing some of the NH3 to N2 or NO.

Porous materials are extensively used in the construction of automotive sound package parts, due to their intrinsic capability of dissipating energy through different mechanisms. The issue related to the optimization of sound package parts (in terms of weight, cost, performances) has led to the need of models suitable for the analysis of porous materials' dynamical behavior and for this, along the years, several analytical and numerical models were proposed, all based on the system of equations initially developed by Biot. In particular, since about 10 years, FE implementations of Biot's system of equations have been available in commercial software programs but their application to sound package parts has been limited to a few isolated cases. This is due, partially at least, to the difficulty of smoothly integrating this type of analyses into the virtual NVH vehicle development.

Since 1992, Toyota Motor Corporation (TMC) has been working on the development of fuel cell system technology. TMC is designing principal components in-house, including fuel cell stacks, high-pressure hydrogen storage tank systems, and hybrid systems. TMC developed the ‘02 model TOYOTA FCHV, the world-first market-ready fuel cell vehicle, and started limited lease of the vehicles in December 2002. In June 2008, TMC developed a new TOYOTA FCHV-adv which obtained vehicle type certification in Japan, and is currently available for leasing in Japan and the United States. In the development of the TOYOTA FCHV-adv, TMC has improved the cruising range and cold start/drive capability from the previous TOYOTA FCHV. The TOYOTA FCHV-adv has achieved an actual cruising range of over 500 km, which is equivalent to that of current gasoline vehicles. In addition, the TOYOTA FCHV-adv has proven starting/driving capability at -30°C temperature.

This paper proposes a new returnless LPG fuel supply system designed to increase the efficiency of current LPG engines. With a conventional engine fuel supply system, the fuel pump is driven at a certain speed to pressurize the fuel to an excessive level, and excess fuel that is discharged from the fuel pump but not injected from the injector is returned to the fuel tank via a pressure regulator and a return line. This arrangement keeps the pressure in the fuel supply line at a constant level. Accordingly, during engine idling, fuel cut-off or other times when very little or no fuel is injected from the injector, nearly all the fuel discharged from the fuel pump is returned to the fuel tank via the pressure regulator and return line. Therefore, the energy (electric power) applied to drive the fuel pump is wastefully consumed. Moreover, returning a large amount of excess fuel to the fuel tank can raise the fuel temperature in the tank, causing the fuel to evaporate.

A dual piston Variable Compression Ratio (VCR) engine has been newly developed. This compact VCR system uses the inertia force and hydraulic pressure accompanying the reciprocating motion of the piston to raise and lower the outer piston and switches the compression ratio in two stages. For the torque characteristic enhancement and the knocking prevention when the compression ratio is being switched, it is necessary to carry out engine controls based on accurate compression ratio judgment. In order to accurately judge compression ratio switching timing, a control system employing the Hidden Markov Model (HMM) was used to analyze vibration generated during the compression ratio switching. Also, in order to realize smooth torque characteristics, an ignition timing control system that separately controls each cylinder and simultaneously performs knocking control was constructed.