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The interest in electric propulsion of vehicles has increased in recent years and is being discussed extensively by experts as well as the public. Up to now the driving range and the utilization of pure electric vehicles are still limited in comparison to conventional vehicles due to the limited capacity and the long charging times of today's batteries. This is a challenge to customer acceptance of a pure electric vehicle, even for a city car application. A Range Extender concept could achieve the desired customer acceptance, but should not impact the “electric driving” experience, and should not cause further significant increases in the manufacturing and purchasing cost. The V2 engine concept presented in this paper is particularly suited to a low cost, modular vehicle concept. Advantages regarding packaging can be realized with the use of two generators in combination with the V2 engine.

In a gasoline engine, the unswept in-cylinder residual gas and introduction of external EGR is one of the important means of controlling engine raw NOx emissions and improving part load fuel economy via reduction of pumping losses. Since the trapped in-cylinder Residual Gas Fraction (RGF, comprised of both internal, and external) significantly affects the combustion process, on-line diagnosis and monitoring of in-cylinder RGF is very important to the understanding of the in-cylinder dilution condition. This is critical during the combustion system development testing and calibration processes. However, on-line measurement of in-cylinder RGF is difficult and requires an expensive exhaust gas analyzer, making it impractical for every application. Other existing methods, based on measured intake and exhaust pressures (steady state or dynamic traces) to calculate gas mass flowrate across the cylinder ports, provide a fast and economical solution to this problem.

In a gasoline engine, the cycle-by-cycle fresh trapped charge, and corresponding unswept residual gas fraction (RGF) are critical parameters of interest for maintaining the desired air-fuel ratio (AFR). Accurate fueling is a key precursor to improved engine fuel economy, and reduced engine out emissions. Asymmetric flow paths to cylinders in certain engines can cause differences in the gas exchange process, which in turn cause imbalances in trapped fresh charge and RGF. Variable cam timing (VCT) can make the gas exchange process even more complex. Due to the reasons stated above, simplified models can result in significant estimation errors for fresh trapped charge and RGF if they are not gas dynamics-based or detailed enough to handle features such as variable valve timing, duration, or lift. In this paper, a new air flow and RGF measurement tool is introduced.

Advanced technologies such as direct injection DI, turbocharging and variable valve timing, have lead to a significant evolution of the gasoline engine with positive effects on driving pleasure, fuel consumption and emissions. Today's developments are primarily focused on the implementation of improved full load characteristics for driving performance and fuel consumption reduction with stoichiometric operation, following the downsizing approach in combination with turbocharging and high specific power. The requirements of a relatively small cylinder displacement with high specific power and a wide flexibility of DI injection specifications lead to competing development targets and additionally to a high number of degrees of freedom during optimization. In order to successfully approach an optimum solution, FEV has evolved an advanced development methodology, which is based on the combination of simulation, optical diagnostics and engine thermodynamics testing.

Future HD Diesel engine technology is facing a combination of both extremely low exhaust emission standards (US 2002/2004, EURO IV and later US 2007, EURO V) and new engine test procedures such as the European Transient Cycle (ETC) in Europe and the Not-to-Exceed Area (NTE) in the US). Customers furthermore require increased engine performance, improved efficiency, and long-term durability. In order to achieve all targets simultaneously, future HD Diesel engines must have improved fuel injection and combustion systems and utilize suitable technologies such as exhaust gas recirculation (EGR), variable geometry turbine turbocharger systems (VGT) and exhaust gas after-treatment systems. Future systems require precision controlled EGR in combination with a VGT-turbocharger during transient operation. This will require new strategies and calibration for the Electronic Engine Control Unit (ECU).

Since the early inception of the adiabatic diesel engine in 1974, marked progress has taken place as a result of research efforts performed all over the world. The use of ceramics for heat engines in production applications has been limited to date, but is growing. Ceramic use for production heat engine has included: combustion prechambers, turbochargers, exhaust port liners, top piston ring inserts, glow plugs, oxygen sensors; and additional high temperature friction and wear components. The potential advantages of an adiabatic engine vary greatly with specific application (i.e., commercial vs. military, stationary vs. vehicular, etc.), and thus, a better understanding of the strengths and weaknesses (and associated risks) of advanced adiabatic concepts with respect to materials, tribology, cost, and payoff must be obtained.

The objective of this work is to develop a strategy to reduce the penalties in the diesel engine performance, fuel economy and HC and CO emissions, associated with the operation in the low temperature combustion regime. Experiments were conducted on a research high speed, single cylinder, 4-valve, small-bore direct injection diesel engine equipped with a common rail injection system under simulated turbocharged conditions, at IMEP = 3 bar and engine speed = 1500 rpm. EGR rates were varied over a wide range to cover engine operation from the conventional to the LTC regime, up to the misfiring point. The injection pressure was varied from 600 bar to 1200 bar. Injection timing was adjusted to cover three different LPPCs (Location of the Peak rate of heat release due to the Premixed Combustion fraction) at 10.5° aTDC, 5 aTDC and 2 aTDC. The swirl ratio was varied from 1.44 to 7.12. Four steps are taken to move from LTC to ALTC.

The high temperature tribology issue for uncooled Low Heat Rejection (LHR) diesel engines where the cylinder liner piston ring interface exceeds temperatures of 225°C to 250°C has existed for decades. It is a problem that has persistently prohibited advances in non-watercooled LHR engine development. Though the problem is not specific to non-watercooled LHR diesel engines, it is the topic of this research study for the past two and one half years. In the late 1970s and throughout the 1980s, a tremendous amount of research had been placed upon the development of the LHR diesel engine. LHR engine finite element design and cycle simulation models had been generated. Many of these projected the cylinder liner piston ring top ring reversal (TRR) temperature to exceed 540°C[1]. In order for the LHR diesel to succeed, a tribological solution for these high TRR temperatures had to be developed.

Several mechanisms are discussed to understand the formation of both regulated and unregulated emissions in a high speed, direct injection, single cylinder diesel engine using low sulphur diesel fuel. Experiments were conducted over a wide range of injection pressures, EGR rates, injection timings and swirl ratios. The regulated emissions were measured by the standard emission equipment. Unregulated emissions such as aldehydes and ketones were measured by high pressure liquid chromatography and hydrocarbon speciation by gas chromatography. Particulate mass was measured with a Tapered Element Oscillating Microbalance (TEOM). Analysis was made of the sources of different emission species and their relationship with the combustion process under the different operating conditions. Special attention is given to the low temperature combustion (LTC) regime which is known to reduce both NOx and soot. However the HC, CO and unregulated emissions increased at a higher rate.

The occurrence of abnormal combustion events leading to high peak pressures and severe knock can be considered to be one of the main challenges for modern turbocharged, direct-injected gasoline engines. These abnormal combustion events have been referred to as Stochastic Pre-Ignition (SPI) or Low-Speed Pre-Ignition (LSPI). The events are characterized by an undesired, early start of combustion of the cylinder charge which occurs before or in parallel to the intended flame kernel development from the spark plug. Early SPI events can subsequently lead to violent auto-ignitions that are often referred to as Mega- or Super-Knock. These heavy knock events lead to strong pressure oscillations which can destroy production engines within a few occurrences. SPI occurs mainly at low engine speed and high engine load, thus limiting the engine operating area that is in particular important to achieve good drivability in downsized engines.

Vehicle OEM’s for MHD applications are facing significant challenges in meeting the stringent 2027 low-NOx and GHG emissions regulations. To meet such challenges, advanced engine and aftertreatment technologies along with powertrain electrification are being applied to achieve robust solutions. FEV has previously conducted model-based assessments to show the potential of 48V engine and aftertreatment technologies to simultaneously meet GHG and low NOx emission standards. This study focuses on evaluating the full potential of 48V electrification technology through addition of 48V P3 hybrid system to the previously developed 48V advanced engine and aftertreatment technology package. Previously, a model-based approach was utilized for selection and sizing of a 48V system-enabled engine and aftertreatment package for class 6-7 MHD application.

This paper investigates theoretically the effects of heat transfer characteristics, such as crank-angle phasing and wall temperature swings, on the thermodynamic efficiency of an IC engine. The objective is to illustrate the fundamental physical basis of applying thin thermal barrier coatings to improve the performance of military and commercial IC engines. A simple model illustrates how the thermal impedance and thickness of coatings can be manipulated to control heat transfer and limit the high temperatures in engine components. A friction model is also included to estimate the overall improvement in engine efficiency by the proper selection of coating thickness and material.

Raising interest in Diesel powered passenger cars in the United States in combination with the government mandated policy to reduce dependency of foreign oil, leads to the desire of operating Diesel vehicles with Biodiesel fuel blends. There is only limited information related to the impact of Biodiesel fuels on the performance of advanced emission control systems. In this project the implementation of a NOx storage and a SCR emission control system and the development for optimal performance are evaluated. The main focus remains on the discussion of the differences between the fuels which is done for the development as well as useful life aged components. From emission control standpoint only marginal effects could be observed as a result of the Biodiesel operation. The NOx storage catalyst results showed lower tailpipe emissions which were attributed to the lower exhaust temperature profile during the test cycle. The SCR catalyst tailpipe results were fuel neutral.

Signals indicative of in-cylinder combustion have been under investigation for the control of diesel engines to meet stringent emission standards and other production targets in performance and fuel economy. This paper presents the results of an investigation on the use of the ion current signal for the close loop control of a heavy duty four cylinder turbocharged diesel engine equipped with a common rail injection system. A correlation is developed between the start of ion current signal (SIC) and the location of the peak of premixed combustion (LPPC) in the rate of heat release trace. Based on this correlation, a PID closed loop controller is developed to adjust the injection timing for proper combustion phasing under steady and transient engine operating conditions.

Thermal barrier coatings are becoming increasingly important in providing thermal insulation for heat engine components. Thermal insulation reduces in-cylinder heat transfer from the engine combustion chamber as well as reducing component structural temperatures. Containment of heat also contributes to increased in-cylinder work and offers higher exhaust temperatures for energy recovery. Lower component structural temperatures will result in greater durability. Advanced ceramic composite coatings also offer the unique properties that can provide reductions in friction and wear. Test results and analysis to evaluate the performance benefits of thin thermal barrier coated components in a single cylinder diesel engine are presented.

The HSDI Diesel engine contributes substantially to the decrease of fleet fuel consumption thus to the reduction of CO2 emissions. This results in the rising market acceptance which is supported by desirable driving performance as well as greatly improved NVH behavior. In addition to the above mentioned requirements on driving performance, fuel economy and NVH behavior, continuously increasing demands on emissions performance have to be met. From today's view the Diesel particulate trap presents a safe technology to achieve the required reduction of the particle emission of more than 95%. However, according to today's knowledge a further, substantial NOx engine-out emission reduction for the Diesel engine is counteracts with the other goal of reduced fuel consumption. To comply with current and future emission standards, Diesel engines will require DeNOx technologies.

An experimental setup using rapid compression machine to provide excellent optical access to visualize simulated high-speed small-bore direct injection diesel engine combustion processes is described. Typical combustion visualization results of diesel spray combustion under different EGR, swirl, and injection pressure and nozzle conditions are presented. Different swirl intensities are achieved using an air nozzle with variable orientations and a check valve to connect the compression chamber and the combustion chamber. Different EGR ratios are achieved by pre-injection of diesel fuel prior to the main observation sequence. Clear visualization of the high-pressure fuel injection, ignition, combustion and spray/wall/swirl interactions is obtained. The injection system is a high-pressure common-rail system with either a VCO or a mini-sac nozzle. High-speed movies up to 35,000 frame-per-second are taken using a framing drum camera to record the combustion events.

The purpose of this paper is to investigate combustion and performance characteristics for an advanced class of diesel engines which support future Army ground propulsion requirements of improved thermal efficiency, reduced system size and weight, and enhanced mobility. Advanced ground vehicle engine research represents a critical building block for future Army vehicles. Unique technology driven engines are essential to the development of compact, high-power density ground propulsion systems. Through an in-house analysis of technical opportunities in the vehicle ground propulsion area, a number of dramatic payoffs have been identified as being achievable. These payoffs require significant advances in various areas such as: optimized combustion, heat release phasing, and fluid flow/fuel spray interaction. These areas have been analyzed in a fundamental manner relative to conventional and low heat rejection “adiabatic” engines.

JP-8 is an aviation turbine engine fuel recently introduced for use in military ground vehicle applications and generators which are mostly powered by diesel engines. Many of these engines are designed and developed for commercial use and need to be adapted for military applications. This requires more understanding of the auto- ignition and combustion characteristics of JP-8 under different engine operating conditions. This paper presents the results of a comparative analysis of an engine operation using JP-8 and ultra low sulfur diesel fuel (ULSD). Experiments were conducted on 0.42 liter single cylinder, high speed direct injection (HSDI) diesel engine equipped with a common rail injection system. The results indicate that the distillation properties of fuel have an effect on its vaporization rate. JP-8 evaporated faster and had shorter ignition delay as compared to ULSD. The fuel economy with JP-8 was better than ULSD.

Crude oils with a wide range of properties were investigated for direct use as fuel in U. S. Army high-speed four-cycle diesel engines. Crude oil properties were divided into two groups; 1. those properties which would be of importance for short-term operational effects, and 2. those properties whose effects would manifest during longer-term operation. Effects of crude oil use on engine subsystem hardware such as fuel filters and fuel injection pumps were investigated. Performance and combustion data were determined using pre-cup and direct injection configurations of the single cylinder CLR diesel engine operating on various crude oils. Performance data, wear and deposition effects of crude oil use were obtained using the TACOM single cylinder diesel engine. Results of this investigation showed that a wide range of crude oils with proper selection and pretreatment are feasible emergency energy sources for U. S. Army four-cycle high-speed diesel engines.