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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

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

Increasing Efficiency in Gasoline Powertrains with a Two-Stage Variable Compression Ratio (VCR) System

2013-04-08
2013-01-0288
Downsizing in combination with turbocharging currently represents the main technology trend for meeting CO2 emissions with gasoline engines. Besides the well-known advantages of downsizing the compression ratio has to be reduced in order to mitigate knock at higher engine loads along with increased turbocharging demand to compensate for the reduction in power. Another disadvantage occurs at part load with increasing boost pressure levels causing the part load efficiencies to deteriorate. The application of a variable compression ratio (VCR) system can help to mitigate these disadvantages. The 2-stage VCR system with variable kinetic lengths entails variable powertrain components which can be used instead of the conventional components and thus only require minor modifications for existing engine architectures. The presented variable length connecting rod system has been continuously developed over the past years.
Technical Paper

Developing Drivetrain Robustness for Small Engine Testing

2013-04-08
2013-01-0400
The increased demand in fuel economy and the reduction of CO₂ emissions results in continued efforts to downsize engines. The downsizing efforts result in engines with lower displacement as well as lower number of cylinders. In addition to cylinder and displacement downsizing the development community embarks on continued efforts toward down-speeding. The combination of the aforementioned factors results in engines which can have high levels of torsional vibrations. Such behavior can have detrimental effects on the drivetrain particularly during the development phase of these. Driveshafts, couplings, and dynamometers are exposed to these torsional forces and depending on their frequency costly damages in these components can occur. To account for these effects, FEV employs a multi-body-system modeling approach through which base engine information is used to determine optimized drivetrain setups. All mechanical elements in the setup are analyzed based on their torsional behavior.
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

Development and Calibration of On-Board-Diagnostic Strategies Using a Micro-HiL Approach

2011-04-12
2011-01-0703
Beginning in 2010, implementation of on-board diagnostics (OBD) is mandatory for all the heavy-duty engine applications in the United States. The task of developing OBD strategies and calibrating them is a challenging one. The process involves a strong interdependency on base engine emissions, controls and regulations. On top of that the strategies developed as a result of the regulatory requirements need to go through a stringent and time-intensive process of software implementation and integration. The recent increasing demands to minimize the development process have been pushing the envelope on the methodologies used in developing the strategies and the calibration for robust monitoring. The goal of this paper is to provide a concise overview of a process utilized to help the development, testing and calibration of the OBD strategies on a 2010 model year heavy-duty diesel engine.
Technical Paper

Road Map for Addressing Future On-Board-Diagnostic Challenges in Light and Heavy-Duty Diesel Engines

2012-04-16
2012-01-0895
Since the 1990's regulatory requirements for On-Board-Diagnostics (OBD) have continuously evolved with an increasing application of advanced electronics and control systems that have been adopted for automotive applications. The current and future demands on emissions and performance requirements are pushing the envelope with respect to management of complex control software strategies, hardware components and their interactions. This further challenges the implementation of OBD. In order to build a robust monitor for a complex system which has minimum risk of false detection, a thorough understanding of both system and components is required. In this paper, several methods will be presented that can be utilized to achieve a successful and robust diagnostic system implementation. Implementation begins with a discussion of the major challenges to achieve consistent performance in the base system control.
Technical Paper

Virtual Testing and Simulation Environment [Micro-HiL] for Engine and Aftertreatment Calibration and Development -Part 2

2012-04-16
2012-01-0928
The growing complexity of powertrain control strategies, software, and hardware is proving to be a significant challenge to the engineering community with regard to managing effective optimization to meet the desired performance. With an increased emphasis on shorter development time and the use of additional sensors and actuators becoming common, the increased dependence on physical models and use of complex interdependent control systems demands a thorough system understanding. This also encourages the use of process improvement tools to assist in an effective engineering process. In this paper, such a tool is discussed in its second phase of development. The Micro-HiL system will be discussed over a wide scope that focuses on the interests of the calibration and development community. The purpose of this paper is to provide an update on the Phase 2 activity of Micro-HiL development; Phase 1 was discussed in-depth at the 2011 SAE World Congress [2011-01-0703].
Technical Paper

Transient Drive Cycle Modeling of Supercharged Powertrains for Medium and Heavy Duty On-Highway Diesel Applications

2012-09-24
2012-01-1962
The problem with traditional drive cycle fuel economy analysis is that kinematic (backward looking) models do not account for transient differences in charge air handling systems. Therefore, dynamic (forward looking) 1D performance simulation models were created to predict drive cycle fuel economy which encompass all the transient elements of fully detailed engine and vehicle models. The transient-capable technology of primary interest was mechanical supercharging which has the benefit of improved boost response and "time to torque." The benefits of a supercharger clutch have also been evaluated. The current US class 6-8 commercial vehicle market exclusively uses turbocharged diesel engines. Three vehicles and baseline powertrains were selected based on a high-level review of vehicle sales and the used truck marketplace. Fuel economy over drive cycles was the principal output of the simulation work. All powertrains are based on EPA 2010 emission regulations.
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.
Journal Article

The Contribution of Engine Mechanics to Improved Fuel Economy

2014-04-01
2014-01-1663
Measures for reducing engine friction within the powertrain are assessed in this paper. The included measures work in combination with several new technologies such as new combustion technologies, downsizing and alternative fuels. The friction reduction measures are discussed for a typical gasoline vehicle. If powertrain friction could be eliminated completely, a reduction of 15% in CO2 emissions could be achieved. In order to comply with more demanding CO2 legislations, new technologies have to be considered to meet these targets. The additional cost for friction reduction measures are often lower than those of other new technologies. Therefore, these measures are worth following up in detail.
Journal Article

Influence of Ethanol Blends on Low Speed Pre-Ignition in Turbocharged, Direct-Injection Gasoline Engines

2017-03-28
2017-01-0687
Modern combustion engines must meet increasingly higher requirements concerning emission standards, fuel economy, performance characteristics and comfort. Especially fuel consumption and the related CO2 emissions were moved into public focus within the last years. One possibility to meet those requirements is downsizing. Engine downsizing is intended to achieve a reduction of fuel consumption through measures that allow reducing displacement while simultaneously keeping or increasing power and torque output. However, to reach that goal, downsized engines need high brake mean effective pressure levels which are well in excess of 20bar. When targeting these high output levels at low engine speeds, undesired combustion events with high cylinder peak pressures can occur that can severely damage the engine. These phenomena, typically called low speed pre-ignition (LSPI), set currently an undesired limit to downsizing.
Journal Article

Impact of the Future Fuel Economy Targets on Powertrain, Driveline and Vehicle NVH Development

2017-06-05
2017-01-1777
The automotive industry continues to develop new technologies aimed at reducing overall vehicle level fuel consumption. Powertrain and driveline related technologies will play a key role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. Specifically, use of technologies such as downsized engines, idle start-stop systems, aggressive torque converter lock-up schedules, wide-ratio spread transmissions, and electrified propulsion systems are vital towards meeting aggressive fuel economy targets. Judicious combinations of such powertrain and driveline technology packages in conjunction with measures such as the use of low rolling resistance tires and vehicle lightweighting will be required to meet future OEM fleet CO2 targets. Many of the technologies needed for meeting the fuel economy and CO2 targets come with unique NVH challenges. In order to ensure customer acceptance of new vehicles, it is imperative that these NVH challenges be understood and solved.
Technical Paper

Novel Approach to Integration of Turbocompounding, Electrification and Supercharging Through Use of Planetary Gear System

2018-04-03
2018-01-0887
Technologies that provide potential for significant improvements in engine efficiency include, engine downsizing/downspeeding (enabled by advanced boosting systems such as an electrically driven compressor), waste heat recovery through turbocompounding or organic Rankine cycle and 48 V mild hybridization. FEV’s Integrated Turbocompounding/Waste Heat Recovery (WHR), Electrification and Supercharging (FEV-ITES) is a novel approach for integration of these technologies in a single unit. This approach provides a reduced cost, reduced space claim and an increase in engine efficiency, when compared to the independent integration of each of these technologies. This approach is enabled through the application of a planetary gear system. Specifically, a secondary compressor is connected to the ring gear, a turbocompounding turbine or organic Rankine cycle (ORC) expander is connected to the sun gear, and an electric motor/generator is connected to the carrier gear.
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

Reduction of Parasitic Losses in Front-End Accessory Drive Systems: Part 2

2018-04-03
2018-01-0326
Demanding CO2 and fuel economy regulations are continuing to pressure the automotive industry into considering innovative powertrain and vehicle-level solutions. Powertrain engineers continue to minimize engine internal friction and transmission parasitic losses with the aim of reducing overall vehicle fuel consumption. In Part 1 of the study (2017-01-0893) described aspects of the test stand design that provides flexibility for adaptation to various test scenarios. The results from measurements for a number of front-end accessory drive (FEAD) components were shown in the context of scatterbands derived from multiple component tests. Key results from direct drive and belt-driven component tests were compared to illustrate the influence of the belt layout on mechanical efficiency of the FEAD system. The second part of the series will focus exclusively on the operation of the alternator. Two main elements of the study are discussed.
Technical Paper

NVH Aspects of Electric Drive Unit Development and Vehicle Integration

2019-06-05
2019-01-1454
The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle-level fuel consumption. Specifically, the use of electrified propulsion systems is expected to play an increasingly important role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. This will also include a strong growth in the global demand for electric drive units (EDUs). The change from conventional vehicles to vehicles propelled by EDUs leads to a reduction in overall vehicle exterior and interior noise levels, especially during low-speed vehicle operation. Despite the overall noise levels being low, the NVH behavior of such vehicles can be objectionable due to the presence of tonal noise coming from electric machines and geartrain components as well as relatively high shares of road/wind noise. In order to ensure customer acceptance of electrically propelled vehicles, it is imperative that these NVH challenges are understood and solved.
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