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Technical Paper

Combined Particulate Matter and NOx Aftertreatment Systems for Stringent Emission Standards

2007-04-16
2007-01-1128
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.
Technical Paper

Tier 2 Intermediate Useful Life (50,000 Miles) and 4000 Mile Supplemental Federal Test Procedure (SFTP) Exhaust Emission Results for a NOx Adsorber and Diesel Particle Filter Equipped Light-Duty Diesel Vehicle

2005-04-11
2005-01-1755
Due to its high efficiency and superior durability the diesel engine is again becoming a prime candidate for future light-duty vehicle applications within the United States. While in Europe the overall diesel share exceeds 40%, the current diesel share in the U.S. is 1%. Despite the current situation and the very stringent Tier 2 emission standards, efforts are being made to introduce the diesel engine back into the U.S. market. In order to succeed, these vehicles have to comply with emissions standards over a 120,000 miles distance while maintaining their excellent fuel economy. The availability of technologies such as high-pressure common-rail fuel systems, low sulfur diesel fuel, NOx adsorber catalysts (NAC), and diesel particle filters (DPFs) allow the development of powertrain systems that have the potential to comply with the light-duty Tier 2 emission requirements. In support of this, the U.S.
Technical Paper

Future Potential and Development Methods for High Output Turbocharged Direct Injected Gasoline Engines

2006-04-03
2006-01-0046
With rising gasoline prices in the US the need for increasingly fuel efficient powertrain concepts has never been more critical. Evaluation of the market on the other hand shows that the vehicle-buying consumer is unwilling to compromise engine power output for this needed fuel efficiency. Boosted, direct-injected gasoline engines with high specific output and low end torque seem to be the most logical path to satisfying both good part load fuel economy and generous power and torque characteristics. Turbo lag and subsequent lack of torque during transient acceleration (with low initial engine speeds) are characteristics of current turbocharged gasoline engines. These phenomena have prevented successful penetration of these boosted powertrains into the marketplace. Larger displacement, naturally aspirated gasoline engines have been the preferred choice.
Technical Paper

Potential of the Spray-guided Combustion System in Combination with Turbocharging

2008-04-14
2008-01-0139
Based on the TurboDISI engine presented earlier [1], [2], a new Spray Guided Turbo (SGT) concept with enhanced engine performance was developed. The turbocharged engine was modified towards utilizing a spray-guided combustion system with a central piezo injector location. Higher specific power and torque levels were achieved by applying specific design and cooling solutions. The engine was developed utilizing a state-of-the-art newly developed charge motion design (CMD) process in combination with single cylinder investigations. The engine control unit has a modular basis and is realized using rapid prototyping hardware. Additional fuel consumption potentials can be achieved with high load EGR, use of alternative fuels and a hybrid powertrain. The CO2 targets of the EU (120 g/km by 2012 in the NEDC) can be obtained with a mid-size vehicle applying the technologies presented within this paper.
Technical Paper

Diesel Combustion Control with Closed-Loop Control of the Injection Strategy

2008-04-14
2008-01-0651
Current and future emission legislations require a significant reduction of engine-out emissions for Diesel engines. For a further reduction of engine-out emissions, different measures are necessary such as: Especially an advanced emission and closed-loop combustion control has gained increased significance during the past years.
Technical Paper

Fuel Property Effects on Emissions and Performance of a Light-Duty Diesel Engine

2009-04-20
2009-01-0488
Increased demand for highly fuel efficient propulsion systems drives the engine development community to develop advanced technologies allowing improving the overall thermal efficiency while maintaining low emission levels. In addition to improving the thermal efficiencies of the internal combustion engine itself the developments of fuels that allow improved combustion as well as lower the emissions footprint has intensified recently. This paper will describe the effects of five different fuel types with significantly differing fuel properties on a state-of-the-art light-duty HSDI diesel engine. The fuels cetane number ranges between 26 and 76. These fuels feature significantly differing boiling characteristics as well as heating values. The fuel selection also contains one pure biodiesel (SME - Soy Methyl Ester). This study was conducted in part load and full load operating points using a state of the art HSDI diesel engine.
Technical Paper

A Multi-Cylinder Airflow & Residual Gas Estimation Tool Applied to a Vehicle Demonstrator

2010-04-12
2010-01-0169
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.
Technical Paper

Systematic Approach to Analyze and Characterize Pre-ignition Events in Turbocharged Direct-injected Gasoline Engines

2011-04-12
2011-01-0343
Downsized direct-injected boosted gasoline engines with high specific power and torque output are leading the way to reduce fuel consumption in passenger car vehicles while maintaining the same performance when compared to applications with larger naturally aspirated engines. These downsized engines reach brake mean effective pressure levels which are in excess of 20 bar. When targeting high output levels at low engine speeds, undesired combustion events called pre-ignition can occur. These pre-ignition events are typically accompanied by very high cylinder peak pressures which can lead to severe damage if the engine is not designed to withstand these high cylinder pressures. Although these pre-ignition events have been reported by numerous other authors, it seems that their occurrence is rather erratic which makes it difficult to investigate or reliably exclude them.
Technical Paper

Gas Exchange Optimization and the Impact on Emission Reduction for HSDI Diesel Engines

2009-04-20
2009-01-0653
The main tasks for all future powertrain developments are: regulated emissions, CO2-values, comfort, good drivability, high reliability and affordable costs. One widely discussed approach for fuel consumption improvement within passenger car applications, is to incorporate the downsizing effect. To attain constant engine performance an increase of boost pressure and/or rated speed is mandatory. In both cases, the mass flow rate through the intake and exhaust ports and valves will rise. In this context, the impact of the port layout on the system has to be reassessed. In this paper, the impact of the port layout on a modern diesel combustion system will be discussed and a promising concept shall be described in detail. The investigations shown include flow measurements, PIV measurements of intake flow, CFD simulations of the flow field during intake and results from the thermodynamic test bench. One of the important topics is to prove the impact of the flow quality on the combustion.
Technical Paper

A New Approach to Boost Pressure and EGR Rate Control Development for HD Truck Engines with VGT

2002-03-04
2002-01-0964
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).
Technical Paper

Cooled EGR - A Must or an Option for 2002/04

2002-03-04
2002-01-0962
The introduction of the new emission standards in 2002/04 for heavy-duty diesel engines requires a substantial reduction of the NOx emissions while the particulate emissions remain on a constant level. The application of cooled EGR appears to be the most common approach in order to achieve the required target, although other means such as advanced combustion systems and the application of emission control devices to reduce NOx emissions have to be taken into account as well. The purpose of this study is to investigate the potential of such alternative solutions in comparison with cooled EGR to meet the upcoming emission standards.
Technical Paper

Tier 2 Useful Life (120,000 miles) Exhaust Emission Results for a NOx Adsorber and Diesel Particle Filter Equipped Light-Duty Diesel Vehicle

2006-04-03
2006-01-0424
Due to its high efficiency and superior durability, the diesel engine is again becoming a prime candidate for future light-duty vehicle applications within the United States. While in Europe the overall diesel share exceeds 40%, the current diesel share in the United States is 1%. Despite the current situation and the very stringent Tier 2 emission standards, efforts are being made to introduce the diesel engine back into the U.S. market. In order to succeed, these vehicles have to comply with emissions standards over a 120,000 miles distance while maintaining their excellent fuel economy. The availability of technologies-such as high-pressure, common-rail fuel systems; low-sulfur diesel fuel; oxides of nitrogen (NOx) adsorber catalysts or NACs; and diesel particle filters (DPFs)-allow the development of powertrain systems that have the potential to comply with the light-duty Tier 2 emission requirements. In support of this, the U.S.
Technical Paper

A Model for On-Line Monitoring of In-Cylinder Residual Gas Fraction (RGF) and Mass Flowrate in Gasoline Engines

2006-04-03
2006-01-0656
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.
Technical Paper

NVH Target Cascading from Customer Interface to Vehicle Subsystems

2013-05-13
2013-01-1980
The definition of vehicle and powertrain level targets is one of the first tasks toward establishing where a vehicle will reside with respect to the current or future state of industry. Though development of sound quality metrics is ongoing to better correlate objective data with subjective assessments, target setting at the vehicle level is relatively straightforward. However, realization of these targets depends on effective cascading to system and component levels. Often, component level targets are derived based on experience from earlier development programs, or based on selected characteristics observed during component level benchmarking. An approach is presented here to complement current strategies for component level target definition. This approach involves a systematic concept for definition of component NVH targets based on desired vehicle level performance and a consequent target break down.
Technical Paper

The NVH Behavior of Internal Combustion Engines used in Range Extended Electric Vehicles

2013-05-13
2013-01-2002
The electrification of vehicle propulsion has changed the landscape of vehicle NVH. Pure electric vehicles (EV) are almost always quieter than those powered by internal combustion engines. However, one of the key challenges with the development of range extended electric vehicles (ReEV) is the NVH behavior of the vehicle. Specifically, the transition from the EV mode to one where the range extender engine is operational can cause significant NVH issues. In addition, the operation of the range extender engine relative to various driving conditions can also pose significant NVH concerns. In this paper internal combustion engines are examined in terms of their acoustic behavior when used as range extenders. This is done by simulating the vibrations at the engine mounting positions as well as the intake and exhaust orifice noise. By using a transfer path synthesis, interior noise components of the range extenders are calculated from these excitations.
Technical Paper

A Low NVH Range-Extender Application with a Small V-2 Engine - Based on a New Vibration Compensation System

2012-10-23
2012-32-0081
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.
Technical Paper

Development of an Emission Controls Concept for an IDI Heavy-Duty Diesel Engine Meeting 2007 Phase-In Emission Standards

2007-04-16
2007-01-0235
In order to allow continued production of the AM General Optimizer 6500 during MY 2007 through 2010 this IDI engine (Indirect Injection - swirl chamber) requires sophisticated aftertreatment controls while maintaining its fuel economy and durability. The main purpose of the development program was to retain the relatively inexpensive and simple base engine with distributor pump and waste-gated turbocharger, while adding hardware and software components that allow achievement of the phase-in emission standards for 2007 through 2010. The aftertreatment system consists of Diesel Oxidation Catalyst (DOC), NOx Adsorber Catalyst (or DeNOx Trap - DNT) and Diesel Particle Filter (DPF). In addition to the base hardware, an intake air throttle valve and an in-exhaust fuel injector were installed. The presented work will document the development process for a 2004 certified 6.5 l IDI heavy-duty diesel engine to comply with the 2007 heavy-duty emission standards.
Technical Paper

In-Use Compliance Opportunity for Diesel Powertrains

2018-04-03
2018-01-0877
In-use compliance under LEV III emission standards, GHG, and fuel economy targets beyond 2025 poses a great opportunity for all ICE-based propulsion systems, especially for light-duty diesel powertrain and aftertreatment enhancement. Though diesel powertrains feature excellent fuel-efficiency, robust and complete emissions controls covering any possible operational profiles and duty cycles has always been a challenge. Significant dependency on aftertreatment calibration and configuration has become a norm. With the onset of hybridization and downsizing, small steps of improvement in system stability have shown a promising avenue for enhancing fuel economy while continuously improving emissions robustness. In this paper, a study of current key technologies and associated emissions robustness will be discussed followed by engine and aftertreatment performance target derivations for LEV III compliant powertrains.
Technical Paper

Analysis of the Impact of Production Lubricant Composition and Fuel Dilution on Stochastic Pre-Ignition in Turbocharged, Direct-Injection Gasoline Engines

2019-04-02
2019-01-0256
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.
Journal Article

Strategies for Meeting Phase 2 GHG and Ultra-Low NOx Emission Standards for Heavy-Duty Diesel Engines

2018-04-03
2018-01-1429
When considered along with Phase 2 Greenhouse Gas (GHG) requirements, the proposed Air Resource Board (ARB) nitrogen oxide (NOx) emission limit of 0.02 g/bhp-hr will be very challenging to achieve as the trade-off between fuel consumption and NOx emissions is not favorable. To meet any future ultra-low NOx emission regulation, the NOx conversion efficiency during the cold start of the emission test cycles needs to be improved. In such a scenario, apart from changes in aftertreatment layout and formulation, additional heating measures will be required. In this article, a physics-based model for an advanced aftertreatment system comprising of a diesel oxidation catalyst (DOC), an SCR-catalyzed diesel particulate filter (SDPF), a stand-alone selective catalytic reduction (SCR), and an ammonia slip catalyst (ASC) was calibrated against experimental data.
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