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A combination of laboratory reactor measurements and vehicle FTP testing has been combined to demonstrate a method for diagnosing the formation of NO2 from a diesel oxidation catalyst (DOC). Using small cores from a production DOC and simulated diesel exhaust, the laboratory reactor experiments are used to support a model for DOC chemical reaction kinetics. The model we propose shows that the ability to produce NO2 is chemically linked to the ability of the catalyst to oxidize hydrocarbon (HC). For thermally damaged DOCs, loss of the HC oxidation function is simultaneous with loss of the NO2 production function. Since HC oxidation is the source of heat generated in the DOC under regeneration conditions, we conclude that a diagnostic of the DOC exotherm is able to detect the failure of the DOC to produce NO2. Vehicle emissions data from a 6.6 L Duramax HD pick-up with DOC of various levels of thermal degradation is provided to support the diagnostic concept.

Exhaust Emission Control: DPF Systems. Presenter Shingo Iwasaki, NGK Insulators, Ltd.

The present production General Motors 2-Mode Hybrid system for full-size SUVs and pickup trucks integrates truck utility functions with a full hybrid system. The 2-mode hybrid system incorporates two electro-mechanical power-split operating modes with four fixed-gear ratios. The combination provides fuel savings from electric assist, regenerative braking and low-speed electric vehicle operation. The combination of two power-split modes reduces the amount of mechanical power that is converted to electric power for continuously variable transmission operation, meeting the utility required for SUVs and trucks. This paper describes how fuel economy functionality was blended with full-size truck utility functions. Truck functions described include: Manual Range Select, Cruise Control, 4WD-Low and continuous high load operation.

This paper details the design and operating attributes of a triple input clutch, layshaft automatic transmission (TCT) with a torque converter in a rear wheel drive passenger vehicle. The objectives of the TCT design are to reduce fuel consumption while increasing acceleration performance through the design of the gearing arrangement, shift actuation system and selection of gear ratios and progression. A systematic comparison of an 8-speed TCT design is made against a hypothetical 8-speed planetary automatic transmission (AT) with torque converter using an energy analysis model based upon empirical data and first principles of vehicle-powertrain systems. It was found that the 8-speed TCT design has the potential to provide an approximate 3% reduction in fuel consumption, a 3% decrease in 0-100 kph time and 30% reduction in energy loss relative to a comparable 8-speed planetary AT with an idealized logarithmic ratio progression.

The purchase of a new automobile is unquestionably a significant investment for most customers, and with this recognition, comes a correspondingly significant expectation for quality and reliability. Amongst automotive systems -when it comes to considerations of reliability - the brakes (perhaps along with the tires) occupy a rarified position of being located in a harsh environment, subjected to continuous wear throughout their use, and are critical to the safe performance of the vehicle. Maintenance of the brake system is therefore a fact of life for most drivers - something that almost everyone must do, yet given the potentially considerable expense, it is something that of great benefit to minimize.

This study emphasizes the fact that there lies value and potential savings in harmonizing some of the inherent differences between the USA, EU, and China regulations with respect to the role of vehicle mass and lightweighting within Fuel Economy (FE) and Green House Gas (GHG) regulations. The definition and intricacies of FE and mass regulations for the three regions (USA, EU, and China) have been discussed and compared. In particular, the nuances of footprint-based, curb-mass-based, and stepped-mass-based regulations that lead to the differences have been discussed. Lightweighting is a customer benefit for fuel consumption, but in this work, we highlight cases where lightweighting, as a CO2 enabler, has incentives that do not align with rational customer values. A typical vehicle’s FE performance sensitivity to a change in mass on the standard regional certification drive cycles is simulated and compared across the three regions.

This paper describes the development of the GM Allison 10-Speed Heavy Duty (HD) Transmission. The trend of increased towing capacity and engine horsepower in the automotive heavy-duty truck segment has been steadily climbing for the past 10 years. The development of 10-Speed HD Transmission is designed to be best in class in for towing performance in the 2500/3500 series segment while optimizing fuel economy. The 10-Speed HD Transmission also gives the customers the option to order an integrated power take-off (PTO) unit that benefits downstream installation of utility accessories such as hydraulic pumps, generators, etc.

Modeling and simulation are crucial in the development of advanced energy efficient control strategies. Utilizing real-world driving data as the underlying basis for control design and simulation lends veracity to projected real-world energy savings. Standardized drive cycles are limited in their utility for evaluating advanced driving strategies that utilize connectivity and on-vehicle sensing, primarily because they are typically intended for evaluating emissions and fuel economy under controlled conditions. Real-world driving data, because of its scale, is a useful representation of various road types, driving styles, and driving environments. The scale of real-world data also presents challenges in effectively using it in simulations. A fast and efficient simulation methodology is necessary to handle the large number of simulations performed for design analysis and impact evaluation of control strategies.

Reliable driveaway from frozen condition is one of the challenging design and control problem for fuel cell applications. Different approaches for warmup from frozen conditions have been developed by OEMs, e.g. low voltage inefficient operation, or use of coolant heaters. However, most methods result in water generation which risk icing and blocking the valves and rendering them nonfunctional till they thaw. One such valve is the anode drain valve which is needed to remove water that crosses over across the membrane to anode side. This work discusses characterization of dynamics of water crossover to anode balance of plant via step response experiments on full scale systems, and development of an online estimator to detect onset of anode water crossover via this online observer. In addition, detection via voltage dip-based feedback is also presented.

An investigation of high speed direct injection (DI) compression ignition (CI) engine combustion fueled with gasoline (termed GDICI for Gasoline Direct-Injection Compression Ignition) in the low temperature combustion (LTC) regime is presented. As an aid to plan engine experiments at full load (16 bar IMEP, 2500 rev/min), exploration of operating conditions was first performed numerically employing a multi-dimensional CFD code, KIVA-ERC-Chemkin, that features improved sub-models and the Chemkin library. The oxidation chemistry of the fuel was calculated using a reduced mechanism for primary reference fuel combustion. Operation ranges of a light-duty diesel engine operating with GDICI combustion with constraints of combustion efficiency, noise level (pressure rise rate) and emissions were identified as functions of injection timings, exhaust gas recirculation rate and the fuel split ratio of double-pulse injections.

This investigation was aimed at measuring the relative performance of two spray-guided, single-cylinder, spark-ignited direct-injected (SIDI) engine combustion system designs. The first utilizes an outwardly-opening poppet, piezo-actuated injector, and the second a conventional, solenoid operated, inwardly-opening multi-hole injector. The single-cylinder engine tests were limited to steady state, warmed-up conditions. The comparison showed that these two spray-guided combustion systems with two very different sprays had surprisingly close results and only differed in some details. Combustion stability and smoke emissions of the systems are comparable to each other over most of the load range. Over a simulated Federal Test Procedure (FTP) cycle, the multi-hole system had 15% lower hydrocarbon and 18% lower carbon monoxide emissions.

Mid 2006 a study group at General Motors developed the concept for the electric vehicle with extended range (EREV),. The electric propulsion system should receive the electrical energy from a rechargeable energy storage system (RESS) and/or an auxiliary power unit (APU) which could either be a hydrogen fuel cell or an internal combustion engine (ICE) driven generator. The study result was the Chevrolet VOLT concept car in the North American Auto Show in Detroit in 2007. The paper describes the requirements, concepts, development and the performance of the battery used as RESS for the ICE type VOLTEC propulsion system version of the Chevrolet Volt. The key requirement for the RESS is to provide energy to drive an electric vehicle with “no compromised performance” for 40 miles. Extended Range Mode allows for this experience to continue beyond 40 miles.

This paper describes rationale for determining the apportionment of variable or ‘shuttered’ airflow and non-variable or static airflow through openings in the front of a vehicle as needed for vehicle cooling. Variable airflow can be achieved by means of a shutter system, which throttles airflow through the front end and into the Condenser, Radiator, and Fan Module, (CRFM). Shutters originated early in the history of the auto industry and acted as a thermostat [1]. They controlled airflow as opposed to coolant flow through the radiator. Two benefits that are realized today are aerodynamic and thermal gains, achieved by restricting unneeded cooling airflow. Other benefits exist and justify the use of shutters; however, there are also difficulties in both execution and practical use. This paper will focus on optimizing system performance and execution in terms of the two benefits of reduced aerodynamic drag and reduced mechanical drag through thermal control.

Cast aluminum alloys are increasingly used in cyclically loaded automotive structural applications for light weight and fuel economy. The fatigue resistance of aluminum castings strongly depends upon the presence of casting flaws and characteristics of microstructural constituents. The existence of casting flaws significantly reduces fatigue crack initiation life. In the absence of casting flaws, however, crack initiation occurs at the fatigue-sensitive microstructural constituents. Cracking and debonding of large silicon (Si) and Fe-rich intermetallic particles and crystallographic shearing from persistent slip bands in the aluminum matrix play an important role in crack initiation. This paper presents fatigue life models for aluminum castings free of casting flaws, which complement the fatigue life models for aluminum castings containing casting flaws published in [1].

Compressed natural gas (CNG) currently is used as an alternative fuel for internal combustion engines in motor vehicles. This paper presents results of an analysis of leaks from a model isolated section of CNG fuel system. Discharge of CNG was modeled as vent flow of a real gas hydrocarbon mixture through an orifice from a reservoir with finite volume. Pressures typically used in CNG fuel systems result in choked flow for gas venting directly to atmosphere, producing an under-expanded, momentum-dominated, turbulent free jet with well defined velocity and concentration fields. This paper presents results of analyses of reservoir pressure decay, and vent flow and concentrations fields for CNG venting from a pressurized reservoir into the atmosphere. A combination of empirically-derived analytical relationships and detailed two-dimensional high resolution computational fluid dynamic modeling was used to determine the velocity and concentrations fields of the resulting CNG jet.

A comprehensive experimental and theoretical approach was undertaken to understand the phenomenon of pre-ignition and to assess parameters to improve or even eliminate it completely. Oil mixing with fuel was identified as the leading theory of self ignition of the fuel. End of compression temperature has to meet a minimum level for pre-ignition to take place. In this work a comprehensive list of parameters were identified that have a direct and crucial role in the onset of pre-ignition including liner wetting, injection targeting, stratification, mixture motion and oil formulation. Many secondary effects were identified including ring dynamics, ring tension, spark plug electrode temperature and coolant temperature. CFD has been extensively used to understand test results including wall film, A/F ratio distribution and temperature at the end of compression when looked at in the context of fuel evaporation and mixing.

Energy efficient HVAC system is becoming increasingly important as higher Corporate Average Fuel Economy (CAFE) standards are required for future vehicle products. The present study is a preliminary attempt at designing energy efficient HVAC system by introducing localized heating/cooling concepts without compromising occupant thermal comfort. In order to achieve this goal of reduced energy consumption while maintaining thermal comfort it is imperative that we use an analytical model capable of predicting thermal comfort with reasonable accuracy in a non-homogenous enclosed thermal environment such as a vehicle's passenger cabin. This study will primarily focus on two aspects: (a) energy efficiency improvements in an HVAC system through micro-cooling/heating strategies and (b) validation of an analytical approach developed in GM that would support the above effort.

The diesel particulate filters (DPF) are considered the most robust technologies for particle emission reduction both in terms of mass and number. On the other hand, the increase of the backpressure in the exhaust system due to the accumulation of the particles in the filter walls leads to an increase of the engine fuel consumption and engine power reduction. To limit the filter loading, and the backpressure, a periodical regeneration is needed. Because of the growing interest about particle emission both in terms of mass, number and size, it appears important to monitor the evolution of the particle mass and number concentrations and size distribution during the regeneration of the DPFs. For this matter, in the presented work the regeneration of a catalyzed filter was fully analyzed. Particular attention was dedicated to the dynamic evolution both of the thermodynamic parameters and particle emissions.

The present paper describes the results of a cooperative research project between GM Powertrain Europe and Istituto Motori - CNR aimed at studying the capability of GM Combustion Closed-Loop Control (CLCC) in enabling seamless operation with high biodiesel blending levels in a modern diesel engine for passenger car applications. As a matter of fact, fuelling modern electronically-controlled diesel engines with high blends of biodiesel leads to a performance reduction of about 12-15% at rated power and up to 30% in the low-end torque, while increasing significantly the engine-out NOx emissions. These effects are both due to the interaction of the biodiesel properties with the control logic of the electronic control unit, which is calibrated for diesel operation. However, as the authors previously demonstrated, if engine calibration is re-tuned for biodiesel fuelling, the above mentioned drawbacks can be compensated and the biodiesel environmental inner qualities can be fully deployed.

Fuel economy improvement and stringent emission regulations worldwide require advanced air charging and combustion technologies, such as low temperature combustion, PCCI or HCCI combustion. Furthermore, NOx aftertreatment systems, like Selective Catalyst Reduction (SCR) or lean NOx trap (LNT), are needed to reduce vehicle tailpipe emissions. The information on engine-out NOx emissions is essential for engine combustion optimization, for engine and aftertreatment system development, especially for those involving combustion optimization, system integration, control strategies, and for on-board diagnosis (OBD). A physical NOx sensor involves additional cost and requires on-board diagnostic algorithms to monitor the performance of the NOx sensor.