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The strong focus on reducing brake drag, driven by a historic ramp-up in global fuel economy and carbon emissions standards, has led to renewed research on brake caliper drag behaviors and how to measure them. However, with the increased knowledge of the range of drag behaviors that a caliper can exhibit comes a particularly vexing problem - how should this complex range of behaviors be represented in the overall road load of the vehicle? What conditions are encountered during coastdown and fuel economy testing, and how should brake drag be measured and represented in these conditions? With the Environmental Protection Agency (amongst other regulating agencies around the world) conducting audit testing, and the requirement that published road load values be repeatable within a specified range during these audits, the importance of answering these questions accurately is elevated. This paper studies these questions, and even offers methodology for addressing them.

Particulate emissions from heavy-duty buses were measured in real time under conditions encountered during the standard Central Business District (CBD) driving cycle. The buses tested were equipped with 1994 Detroit Diesel Engine Corporation 6V92-TA engines, and some included after treatment devices on the exhaust. Instantaneous, time-resolved measurements of CO2 and amorphous carbon concentrations were obtained using an optical extinction technique and compared to simultaneous results obtained using conventional dilution tunnel sampling methods. Good agreement was obtained between the real-time extinction measurements and the diluted CO2 and cycle-integrated filter measurements. The instantaneous measurements revealed that acceleration transients accounted for roughly 80% of the particulate mass emitted during the cycle but only about 45% of the fuel consumption.

This study reports on laser-based diagnostics to temporally track the evolution of liquid and gaseous fuel in the cylinder of a direct injection production type Diesel engine. A two-dimensional Mie scattering technique is used to record the liquid phase and planar laser-induced fluorescence of Diesel is used to track both liquid and vaporised fuel. LIF-Signal is visible in liquid and gas phase, Mie scattering occurs only in zones where fuel droplets are present. Distinction between liquid and gaseous phase becomes therefore possible by comparing LIF- and Mie-Signals. Although the information is qualitative in nature, trends of spray evolution are accessible. Within this study a parametric variation of injection pressure, in-cylinder conditions such as gas temperature and pressure as well as piston geometry are discussed. Observations are used to identify the most sensitive parameters and to qualitatively describe the temporal evolution of the spray for real engine conditions.

Results of three-dimensional computations of non-vaporizing and vaporizing Diesel sprays in a very high pressure (up to 18.4 MPa without combustion) environment are presented. These pressures and corresponding density ratios of ambient gas to injected liquid are about a factor of two greater than those in current Diesel engines. The spray model incorporates a line source for drops, heat, mass and momentum exchange between the gas and liquid phases, turbulent dispersion of drops, collisions and coalescences, and drop breakup. The accuracy of the model is assessed by making comparisons of computed and measured spray penetrations. Reasonable agreement is obtained for a broad range of conditions. A scaling for time and axial distance clarifies these results.

Novel Combustion technologies and strategies show high potential in reducing the fuel consumption of gasoline spark ignition (SI) engines. In this paper, a comparison between various gasoline combustion concepts at two representative engine operating points is shown. Advantages of the combustion concepts are analyzed using thermodynamic split of losses method. In this paper, a tool for thermodynamic assessment (Split of Losses) of conventional and new operating strategies of SI engine and its derivatives is used. Technologies, like variable valve actuation and/or gasoline direct injection, allow new strategies to run the SI engine unthrottled with early inlet valve closing (SI-VVA) combined with high EGR, charge stratification (SI-STRAT) and controlled auto ignition (CAI), also known as gasoline homogeneous charge compression ignition (HCCI). These diverse combustion concepts show thermodynamic gains that stem from several, often different sources.

The US Environmental Protection Agency (EPA)’s heavy duty diesel emission standard was tightened beginning from 2007 with the introduction of ultra-low-sulfur diesel fuel. Most heavy duty diesel applications were required to equip Particulate Matter (PM) after-treatment systems to meet the new tighter, emission standard. Systems utilizing Diesel Oxidation Catalyst (DOC) and Catalyzed-Diesel Particulate Filter (DPF) are a mainstream of modern diesel PM after-treatment systems. To ensure appropriate performance of the system, periodic cleaning of the PM trapped in DPF by its oxidation (a process called “regeneration”) is necessary. As a result, of this regeneration, DOC’s and DPF’s can be exposed to hundreds of thermal cycles during their lifetime. Therefore, to understand the thermo-mechanical performance of the DOC and DPF is an essential issue to evaluate the durability of the system.

The range of Robert Bosch in-line pumps is designed for engines with cylinder outputs of up to 200 kW. Within this family of pumps the MW pump is used in small IDI engines and medium-sized DI engines with cylinder outputs in the region of 30 kW. More stringent exhaust emission legislation and the need to ensure optimum fuel economy call for efficient fuel-injection systems for diesel engines. In both of its designs the new MW pump meets these more exacting requirements and forms the contribution of Robert Bosch GmbH toward developing advanced diesel engines.

A new generation Northstar DOHC V8 engine has been developed for a new family of rear-wheel-drive (RWD) Cadillac vehicles. The new longitudinal engine architecture includes strategically selected technologies to enable a higher level of performance and refinement. These technologies include four-cam continuously variable valve timing, low restriction intake and exhaust manifolds and cylinder head ports, a steel crankshaft, electronic throttle control, and close-coupled catalysts. Additional design features beyond those required for RWD include optimized block ribbing, improved coolant flow, and a newly developed lubrication and ventilation system for high-speed operation and high lateral acceleration. This new design results in improved performance over the entire operating range, lower emissions, improved fuel economy, improved operating refinement, and reduced noise/vibration/harshness (NVH).

Earlier work [1] shows that kinetics of Diesel soot oxidation is different from that of ethylene diffusion flame soot oxidation [2], possibly due to metals from lube oil. This study investigates the influence of metals on soot oxidation and the exhaust particle emissions using lube oil dosed fuel (2 % by volume). This method does not simulate normal lube oil consumption, but is used as a means of adding metals to particles for oxidation studies. This study also provides insight into the effect of systems that mix lube oil with fuel to minimize oil change service. The HTO-TDMA (High Temperature Oxidation-Tandem Differential Mobility Analyzer) technique [1] was used to measure the surface specific oxidation rate of Diesel particles over the temperature range 500-750 °C. Diesel particles sampled from the exhaust stream of a Diesel engine were size segregated by differential mobility and oxidized in situ in air in a heated flow tube of known residence time and temperature profile.

A previous study by the authors has shown an efficiency benefit of up to Δηi = 10 % for stratified operation of a high pressure natural gas direct injection (DI) spark ignition (SI) engine compared to the homogeneous stoichiometric operation with port fuel injection (PFI). While best efficiencies appeared at extremely lean operation at λ = 3.2, minimum HC emissions were found at λ = 2. The increasing HC emissions and narrow ignition time frames in the extremely lean stratified operation have given the need for a detailed analysis. To further investigate the mixture formation and flame propagation und these conditions, an optically accessible single-cylinder engine was used. The mixture formation and the flame luminosity have been investigated in two perpendicular planes inside the combustion chamber.

A key element of General Motors' Advanced Propulsion Technology Strategy is the electrification of the automobile. The objectives of this strategy are reduced fuel consumption, reduced emissions and increased energy security/diversification. The introduction of hybrid vehicles was one of the first steps as a result of this strategy. To determine future opportunities and direction, an extensive study was completed to better understand the ability of Plug-in Hybrid Electric Vehicles (PHEV) and Extended-Range Electric Vehicles (E-REV) to address societal challenges. The study evaluated real world representative driving datasets to understand actual vehicle usage. Vehicle simulations were conducted to evaluate the merits of PHEV and E-REV configurations. As derivatives of conventional full hybrids, PHEVs have the potential to deliver a significant reduction in petroleum usage.

The tightening of Heavy Duty Diesel (HDD) emissions legislation throughout the world is leading to the development of emission control devices to enable HDD engines to meet the new standards. NOx and Particulate Matter (PM) are the key pollutants which these emission control systems need to address. Diesel Particulate Filters (DPFs) are already in use in significant numbers to control PM emissions from HDD vehicles, and Selective Catalytic Reduction (SCR) is a very promising technology to control NOx emissions. This paper describes the development and performance of the Compact SCR-Trap system - a pollution control device comprising a DPF-based system (the Continuously Regenerating Trap system) upstream of an SCR system. The system has been designed to be as easy to package as possible, by minimising the total volume of the system and by incorporating the SCR catalysts on annular substrates placed around the outside of the DPF-based system.

The reduction of nitrous oxides in the exhaust gases of internal combustion engines using a urea water solution is gaining more and more importance. While maintaining the future exhaust gas emission regulations, like the Euro 6 for passenger cars and the Euro 5 for commercial vehicles, urea dosing allows the engine management to be modified to improve fuel economy as well. The system manufacturer Robert Bosch has started early to develop the necessary dosing systems for the urea water solution. More than 300.000 Units have been delivered in 2007 for heavy duty applications. Typical dosing quantities for those systems are in the range of 0.01 l/h for passenger car systems and up to 10 l/h for commercial vehicles. During the first years of development and application of urea dosing systems, instantaneous flow measuring devices were used, which were not operating fully satisfactory.

Reducing Carbon Dioxide (CO2) emissions is one of the major challenges for automobile manufacturers. This is driven by environmental, consumer, and regulatory demands in all major regions worldwide. For conventional vehicles, a host of technologies have been applied that improve the overall efficiency of the vehicle. This reduces CO2 contributions by directly reducing the amount of energy consumed to power a vehicle. The hybrid electric vehicle (HEV) continues this trend. However, there are limits to CO2 reduction due to improvements in efficiency alone. Other major improvements are realized when the CO2 content of the energy used to motivate vehicles is reduced. With the introduction of Extended Range Electric Vehicles (E-REVs) and Plug-in HEVs (PHEVs), electric grid energy displaces petroleum. This enables the potential for significant CO2 reductions as the CO2 per unit of electrical energy is reduced over time with the improving mix of energy sources for the electrical grid.

Well-to-Wheels analyses are important tools that provide a rigorous examination and quantify the environmental burdens associated with fuel production and fuel consumption during the vehicle use phase. Such assessments integrate the results obtained from the Well-to-Tank (WtT) and the Tank-to-Wheels (TtW) analysis components. The purpose of this study is to provide a preliminary Tank-to-Wheels assessment of the benefits associated with the introduction of alternative powertrains and fuels in the Chinese market by the year 2015 as compared to the results obtained with conventional internal combustion engine vehicles (ICEVs). An emphasis is given on the vehicles powered by those fuels that have the potential to play a major role in the Chinese auto-sector, such as: M10, M85, E10, E85, Di-methyl Ether (DME) and Coal-to-Liquids (CTL). An important conclusion of this report is that hybridization reduces fuel consumption in all propulsion systems.

A two-dimensional optimization process which simultaneously adjusts the spark timing and air-fuel ratio of a lean-burn natural gas fueled engine has been demonstrated. This has been done by first mapping the thermal efficiency against spark timing and equivalence ratio at a single speed and load combination to obtain the 3-D surface of efficiency versus the other two variables. Then the ability of the control system to find and hold the combination of timing and air-fuel ratio which gives the highest thermal efficiency was explored. The control system described in SAE Paper No. 940546 was used to map the thermal efficiency versus equivalence ratio and ignition timing. NOx, CO, and HC maps were also obtained to determine the tradeoffs between efficiency and emissions. A load corresponding to a brake mean effective pressure of 0.467 MPa was maintained by a water brake dynamometer. A speed of 2000 rpm was maintained by a fuel-controlled governor.

An advanced variable valve actuation (VVA) system is characterized following end-of-life testing to enable fuel economy solutions for passenger car applications. The system consists of a switching roller finger follower (SRFF) combined with a dual feed hydraulic lash adjuster and an oil control valve that are integrated into a four cylinder gasoline engine. The SRFF provides discrete valve lift capability on the intake valves. The motivation for designing this type of VVA system is targeted to improve fuel economy by reducing the air pumping losses during part load engine operation. This paper addresses the durability of a SRFF for meeting passenger car durability requirements. Extensive durability tests were conducted for high speed, low speed, switching, and cold start operation. High engine speed test results show stable valvetrain dynamics above 7000 engine rpm. System wear requirements met end-of-life criteria for the switching, sliding, rolling and torsion spring interfaces.

Measured vehicle loads, taken during durability events, are commonly used to drive in-lab vehicle subsystem validation testing. The use of measured loads can be problematic due to (a) off-nominal characteristics of the test vehicle, (b) post-test changes to vehicle tuning - bushings, springs, and shocks for example, (c) scheduling, timing and weather requirements, (d) modification of vehicle characteristics by the inclusion of transducers and (e) the cost of executing tests. A general process for supplementing and rationalizing measured vehicle data through the use of correlated multi-body dynamic simulations is presented. Difficulties in modeling tires and other components, as well as difficulties in model correlation for abusive load events are also discussed.

The stricter worldwide emission legislation and growing demands for lower fuel consumption and CO2-emission require for significant efforts to improve combustion efficiency while satisfying the emission quality demands. Ethanol fuel combined with boosting on direct injection gasoline engines provides a particularly promising and, at the same time, a challenging approach. Brazil is one of the main Ethanol fuel markets with its E24 and E100 fuel availability, which covers a large volume of the national needs. Additionally, worldwide Ethanol availability is becoming more and more important, e.g., in North America and Europe. Considering the future flex-fuel engine market with growing potentials identified on downsized spark ignition engines, it becomes necessary to investigate the synergies and challenges of Ethanol boosted operation. Main topic of the present work focuses on the operation of Ethanol blends up to E100 at high loads up to 30 bar imep.

Fuel economy of two-wheelers is an important factor influencing the purchasing psychology of the consumer within the emerging markets. Additionally, air pollution being a major environmental topic, there is a rising concern about vehicle emissions, especially in the big cities and their metropolitan areas. Potentially, the relatively expensive engine management systems are providing more features and value in comparison to the carburettor counterpart. The combustion system analysis is carried out on a 125 cm3 motorcycle engine and the subsequent numerical simulation comparing the carburettor and the Electronic (Port) Fuel Injection which provides a basis to establish the fuel consumption benefit for the electronic injection systems [1].