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Technical Paper

Overall Results: Phase I Ad Hoc Diesel Fuel Test Program

The future of diesel-engine-powered passenger cars and light-duty vehicles in the United States depends on their ability to meet Federal Tier 2 and California LEV2 tailpipe emission standards. The experimental purpose of this work was to examine the potential role of fuels; specifically, to determine the sensitivity of engine-out NOx and particulate matter (PM) to gross changes in fuel formulation. The fuels studied were a market-average California baseline fuel and three advanced low sulfur fuels (<2 ppm). The advanced fuels were a low-sulfur-highly-hydrocracked diesel (LSHC), a neat (100%) Fischer-Tropsch (FT100) and 15% DMM (dimethoxy methane) blended into LSHC (DMM15). The fuels were tested on modern, turbocharged, common-rail, direct-injection diesel engines at DaimlerChrysler, Ford and General Motors. The engines were tested at five speed/load conditions with injection timing set to minimize fuel consumption.
Technical Paper

Design and Development of Method of Valve-Train Friction Measurement

The general trend in the IC engine design has been towards reduction in fuel consumption since the 1973 oil embargo. The improvement in combustion process has contributed greatly to a better fuel economy of today's engine and there are many challenges ahead on the GDI front towards the 3L/100km engine [1]. One of the biggest windows of opportunity in achieving higher engine fuel efficiency together with an acceptable emissions level is to reduce its friction. To achieve these an accurate method of assessing friction levels through the concept, design and development is paramount. Translation of friction torque to the total drive cycle's fuel consumption is carried out using Ford's in-house CAE analytical packages. A new method of directly measuring camshaft friction has been developed, which offers both exceptional accuracy and unprecedented convenience.
Technical Paper

Parametric Simulation of Significant Design and Operating Alternatives Affecting the Fuel Economy and Emissions of Spark-Ignited Engines

A fundamental thermodynamic model of the complete spark-ignited, homogeneous charge engine cycle has been used in several parametric analyses to predict the effects of engine design and operating alternatives on fuel consumption and emissions of NOx and unburned hydrocarbons (HC). The simulation includes sub-models for wall heat transfer, NOx and HC emissions, and the engine breathing processes. This work demonstrates the power and utility of a comprehensive engine simulation by presenting several independent parametric studies that were carried out in response to genuine engine design and/or operating strategy questions. Included in this compilation are the effects of cycle heat loss, exhaust port heat loss, combustion duration, and charge dilution (EGR and/or lean air-fuel ratio). In addition, the influence of the design variables associated with bore-stroke ratio, intake and exhaust valve lift, and cam timing are considered.
Technical Paper

The Effects of Load Control with Port Throttling at Idle- Measurements and Analyses

An experimental and analytical study was conducted to investigate the effects of load control with port throttling on stability and fuel consumption at idle. With port throttling, the pressure in the intake port increases during the valve-closed period due to flow past the throttle. If the pressure in the port recovers to ambient before the valve overlap period, back flow into the intake system from the cylinder is eliminated. This allows increased valve overlap to be used without increasing the residual mass fraction in the cylinder. Results showed that, with high valve overlap and port throttling, idle stability and fuel consumption can be maintained at values associated with low overlap in a conventionally throttled engine. However, implementation of this concept in production is regarded to require precision-fit and balanced port throttles, an external vacuum pump for vacuum systems support, and revision of the PCV system.
Technical Paper

Hybrid Powertrain Operation Optimization Considering Cross Attribute Performance Metrics

Hybrid electric vehicles are continuously challenged to meet cross attribute performance while minimizing energy usage and component cost in a very competitive automotive market. As electrified vehicles become more mainstream in the marketplace, hybrid customers are expecting more attribute refinement in combination with the enhanced fuel economy benefits. Minimizing fuel consumption, which tends to drive hybrid powertrain engines to operate under lugging type calibrations, traditionally challenge noise, vibration, and harshness (NVH) metrics. Balancing the design space to satisfy the cost metrics, energy efficiency, noise and vibration & drivability under the hybrid engine lugging conditions can be optimized through the use of multiple CAE tools. This paper describes how achieving NVH metrics can put undesirable boundaries on Powertrain Operation which could affect other performance attributes.
Technical Paper

Manage and Optimize Power System to Maximize Steering Assist and Stop-Start Availability

Auto stop-start (Engine stop-start, ESS) has become a widely used feature to reduce fuel consumption and CO2 emissions particularly in congested cities. Typically, vehicles equipped with such systems include two DC power sources that are coupled in parallel: a primary and a secondary power source. The primary power source supplies energy to the starter to crank the engine, while the secondary power source supplies energy to the rest of the vehicle electric loads. During an auto-stop event, a controllable switch decouples the two power sources. Moreover, operating current, voltage and the State of Charge (SOC) are monitored to ensure enough energy for the next auto-start event. When any of these operating parameters are below the threshold values, the controllable switch opens to isolate the two batteries and then the engine is automatically started.
Technical Paper

Study on the Interaction of Clearance Flow and Shock Wave in a Turbine Nozzle

Radial flow Variable Nozzle Turbine (VNT) enables better matching between the turbocharger and engine. At partial loading or low-end engine operating points, the nozzle vane opening of the VNT is decreased to achieve higher turbine efficiency and transient response, which is a benefit for engine fuel consumption and emission. However, under certain small nozzle opening conditions (such as nozzle brake and low-end operating points), strong shock waves and strong nozzle clearance flow are generated. Consequently, strong rotor-stator interaction between turbine nozzle and impeller is the key factor of the impeller high cycle fatigue and failure. In present paper, flow visualization experiment is carried out on a linear turbine nozzle. The turbine nozzle is designed to have single-sided clearance, and the Schlieren visualization method is used to describe the formation and development process of clearance flow and shock wave under different clearance and expansion ratio configurations.
Technical Paper

CFD Topology and Shape Optimization for Port Development of Integrated Exhaust Manifolds

Modern cylinder-head designs for gasoline engines are guiding the exhaust gas to the turbocharger system via an integrated exhaust manifold (IEM) which has several advantages like weight and cost reduction. On the other hand, the exhaust ports are running through a package labyrinth and are heavily bent within smallest space. Increased pressure drop, reduced mass flow rate, and deteriorated port flow efficiency could be the consequences leading to higher emissions, increased fuel consumption, and higher knock sensitivity. The optimization of the individual ports by computational fluid dynamics (CFD) is a proper means to minimize or even delete these drawbacks. Meanwhile, there are several powerful optimization methods for three-dimensional flows on the market. In this paper, a combined optimization strategy using CFD topology optimization followed by a shape optimization is presented.
Technical Paper

A Methodology of Real-World Fuel Consumption Estimation: Part 1. Drive Cycles

To assess the fuel consumption of vehicles, three sets of input data are required; drive cycles, vehicle parameters, and environmental conditions. As the first part of a series of studies on real-world fuel consumption, this study focuses on the drive cycles. In principle, drive cycles should represent real-world usage. Some of them aim at a specific usage such as a city driving condition or an aggressive driving style. However, the definition of city or aggressive driving is very subjective and difficult to quantitatively correlate with the real-world usage. This study proposes a methodology to quantify the speed and dynamics of drive cycles, or vehicle speed traces in general, against the real-world usage. After reviewing parameter sets found in other studies, relative cubic speed (RCS) and positive kinetic energy (PKE) are selected to represent the speed and dynamics through energy flow balance at the wheels.
Technical Paper

MMLV: Chassis Design and Component Testing

The Multi Material Lightweight Vehicle (MMLV) developed by Magna International and Ford Motor Company is a result of a US Department of Energy project DE-EE0005574. The project demonstrates the lightweighting potential of a five passenger sedan, while maintaining vehicle performance and occupant safety. Prototype vehicles were manufactured and limited full vehicle testing was conducted. The Mach-I vehicle design, comprised of commercially available materials and production processes, achieved a 364kg (23.5%) full vehicle mass reduction, enabling the application of a 1.0-liter three-cylinder engine resulting in a significant environmental benefits and fuel consumption reduction. As part of this project, several automotive chassis components were selected for development and evaluation on the MMLV C/D segment passenger sedan.
Technical Paper

Characterisation of Diesel Engine Transient Pumping-loss and Control Methodology for Transient Specific Fuel Consumption (SFC)

This study measures, during various transients of speed and load, in-cylinder-, intake-/exhaust- (manifold) pressures and engine torque. The tests were conducted on a typical high power-density, passenger car powertrain (common-rail diesel engine, of in-line 4-cylinder configuration equipped with a Variable Geometry Turbocharger). The objective was to quantify the deterioration (relative to a steady-steady condition) in transient Specific Fuel Consumption (SFC) that may occur during lagged-boost closed-loop control and thus propose an engine control strategy that minimises the transient SFC deterioration. The results, from transient characterisation and the analysis method applied in this study, indicate that transient SFC can deteriorate up to 30% (function of load transient) and is primarily caused by excessive engine pumping-loss.
Technical Paper

Control Oriented Model and Dynamometer Testing for a Single-Cylinder, Heated-Air HCCI Engine

In recent years, HCCI (Homogeneous Charge Compression Ignition) combustion concept has attracted attention due to its potential for high fuel efficiency and low emissions. The essence of HCCI combustion is auto ignition of a very lean, homogeneous air-fuel mixture. However it leads to a major challenge for control engineers – controlling combustion timing to achieve required torque and optimal fuel consumption. There is a need for a simplified HCCI engine model to guide control strategy development. This paper presents such a control oriented model for a “heated intake air” HCCI engine concept that uses two streams of air (cold and hot) to achieve a variable temperature at intake valve closing.
Technical Paper

A Statistical Approach to Assess the Impact of Road Events on PHEV Performance using Real World Data

Plug in hybrid electric vehicles (PHEVs) have gained interest over last decade due to their increased fuel economy and ability to displace some petroleum fuel with electricity from power grid. Given the complexity of this vehicle powertrain, the energy management plays a key role in providing higher fuel economy. The energy management algorithm on PHEVs performs the same task as a hybrid vehicle energy management but it has more freedom in utilizing the battery energy due to the larger battery capacity and ability to be recharged from the power grid. The state of charge (SOC) profile of the battery during the entire driving trip determines the electric energy usage, thus determining overall fuel consumption.
Technical Paper

Mode Transition Optimisation for Variable Displacement Engines

The deactivation of one or more cylinders in internal combustion engines has long been established in literature as a means of reducing engine pumping losses and thereby improving brake specific fuel consumption. As down-sizing and down-speeding of modern engines becomes more extreme, drivability issues associated with mode transition become more acute and need to be managed within a suitable calibration framework. This paper presents methodology by which a calibration may be deduced for optimal mode-transitioning in respect of minimising the torque disturbance as cylinders are deactivated and re-activated. At the outset of this study a physics based engine model is used to investigate the key parameters that influence the transition. Having understood these, experiments are designed to establish the level of mode transition disturbance using quantitative statistical indicators such that the cost function may be defined and an optimisation undertaken.
Technical Paper

Pricing of Renewable Gasoline and Its Impact on Greenhouse Gas Emission Reduction Planning for Automakers and Electricity Generators

With increasing evidence for climate change in response to greenhouse gasses (GHG) emitted by human activities, pressure is growing to reduce fuel consumption via increased vehicle efficiency and to replace fossil fuels with renewable fuels. While real-world experience with bio-ethanol and a growing body of research on many other renewable fuel pathways provide some guidance as to the cost of renewable transportation fuel, there has been little work comparing that cost to alternative means for achieving equivalent GHG reductions. In earlier work, we developed an optimization model that allowed the transportation and electricity generation sectors to work separately or jointly to achieve GHG reduction targets, and showed that cooperation can significantly reduce the society cost of GHG reductions.
Technical Paper

Changing Habits to Improve Fuel Economy

In recent years we have witnessed increased discrepancy between fuel economy numbers reported in accordance with EPA testing procedures and real world fuel economy reported by drivers. The debates range from needs for new testing procedures to the fact that driver complaints create one-sided distribution; drivers that get better fuel economy do not complain about the fuel economy, but only the ones whose fuel economy falls short of expectations. In this paper, we demonstrate fuel economy improvements that can be obtained if the driver is properly sophisticated in the skill of driving. Implementation of SmartGauge with EcoGuide into the Ford C-MAX Hybrid in 2013 helped drivers improve their fuel economy on hybrid vehicles. Further development of this idea led to the EcoCoach that would be implemented into all future Ford vehicles.
Technical Paper

Literature Survey of Water Injection Benefits on Boosted Spark Ignited Engines

The automotive industry has been witnessing a major shift towards downsized boosted direct injection engines due to diminishing petroleum reserves and increasingly stringent emission targets. Boosted engines operate at a high mean effective pressure (MEP), resulting in higher in-cylinder pressures and temperatures, effectively leading to increased possibility of abnormal combustion events like knock and pre-ignition. Therefore, the compression ratio and boost pressure in modern engines are restricted, which in-turn limits the engine efficiency and power. To mitigate conditions where the engine is prone to knocking, the engine control system uses spark retard and/or mixture enrichment, which decrease indicated work and increase specific fuel consumption. Several researchers have advocated water injection as an approach to replace or supplement existing knock mitigation techniques.
Technical Paper

1D Model for Correcting the Rate of Injection Signal Based on Geometry and Temperature Influence

The fuel consumption and emissions of diesel engines is strongly influenced by the injection rate pattern, which influences the in-cylinder mixing and combustion process. Knowing the exact injection rate is mandatory for an optimal diesel combustion development. The short injection time of no more than some milliseconds prevents a direct flow rate measurement. However, the injection rate is deduced from the pressure change caused by injecting into a fuel reservoir or pipe. In an ideal case, the pressure increase in a fuel pipe correlates with the flow rate. Unfortunately, real measurement devices show measurement inaccuracies and errors, caused by non-ideal geometrical shapes as well as variable fuel temperature and fuel properties along the measurement pipe. To analyze the thermal effect onto the measurement results, an available rate measurement device is extended with a flexible heating system as well as multiple pressure and temperature sensors.
Technical Paper

A Variable Displacement Supercharger Performance Evaluation

The Variable Displacement Supercharger (VDS) is a twin helical screw style compressor that has a feature to change its displacement and its compression ratio actively during vehicle operation. This device can reduce the parasitic losses associated with supercharging and improve the relative fuel economy of a supercharged engine. Supercharging is a boosting choice with several advantages over turbocharging. There is fast pressure delivery to the engine intake manifold for fast engine torque response providing the fun to drive feel. The performance delivered by a supercharger can enable engine fuel economy actions to include engine downsizing and downspeeding. The cost and difficulty of engineering hot exhaust components is eliminated when using only an air side compressor. Faster catalyst warm up can be achieved when not warming the turbine housing of a turbocharger.
Technical Paper

A Method for Rapid Durability Test Development

Designing a durability test for an automatic transmission that appropriately reflects customer usage during the lifetime of the vehicle is a formidable task; while the transmission and its components must survive severe usage, overdesigning components leads to unnecessary weight, increased fuel consumption and increased emissions. Damage to transmission components is a function of many parameters including customer driving habits and vehicle and transmission characteristics such as weight, powertrain calibration, and gear ratios. Additionally, in some cases durability tests are required to verify only a subset of the total parameter space, for example, verifying only component modifications. Lastly, the ideal durability test is designed to impose the worst case loading conditions for the maximum number of internal components, be as short as practicable to reduce testing time, with minimal variability between tests in order to optimize test equipment and personnel resources.