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Technical Paper

Optimization of a CNG Driven SI Engine Within a Parallel Hybrid Power Train by Using EGR and an Oversized Turbocharger with Active-WG Control

2010-04-12
2010-01-0820
The hybrid power train technology offers various prospects to optimize the engine efficiency in order to minimize the CO₂ emissions of an internal-combustion-engine-powered vehicle. Today different types of hybrid architectures like parallel, serial, power split or through-the-road concepts are commonly known. To achieve lowest fuel consumption the following hybrid electric vehicle drive modes can be used: Start/Stop, pure electric/thermal driving, recuperation of brake energy and the hybrid mode. The high complexity of the interaction between those power sources requires an extensive investigation to determine the optimal configuration of a natural-gas-powered SI engine within a parallel hybrid power train. Therefore, a turbocharged 1.0-liter 3-cylinder CNG engine was analyzed on the test bench. Using an optimized combustion strategy, the engine was operated at stoichiometric and lean air/fuel ratio applying both high- and low-pressure EGR.
Technical Paper

Simulation of the Post-Oxidation in Turbo Charged SI-DI-Engines

2011-04-12
2011-01-0373
Turbocharged SI-DI-engines in combination with a reduction of engine displacement (“Downsizing”) offer the possibility to remarkably reduce the overall fuel consumption. In charged mode it is possible to scavenge fresh unburnt air into the exhaust system if a positive slope during the overlap phase of the gas exchange occurs. The matching of the turbo system in SI-engines always causes a trade-off between low-end torque and high power output. The higher mass flow at low engine speeds of an engine using scavenging allows a partial solution of this trade-off. Thus, higher downsizing grades and fuel consumption reduction potential can be obtained. Through scavenging the global fuel to air ratio deviates from the local in-cylinder fuel to air ratio. It is possible to use a rich in-cylinder fuel to air ratio, whereas the global fuel to air ratio remains stochiometrical. This could be very beneficial to reduce the effect of catalytic aging on the one hand and engine knock on the other hand.
Technical Paper

Resonance Charging Applied to a Turbo Charged Gasoline Engine for Transient Behavior Enhancement at Low Engine Speed

2017-09-04
2017-24-0146
Upcoming regulations and new technologies are challenging the internal combustion engine and increasing the pressure on car manufacturers to further reduce powertrain emissions. Indeed, RDE pushes engineering to keep low emissions not only at the bottom left of the engine map, but in the complete range of load and engine speeds. This means for gasoline engines that the strategy used to increase the low end torque and power by moving out of lambda one conditions is no longer sustainable. For instance scavenging, which helps to increase the enthalpy of the turbine at low engine speed cannot be applied and thus leads to a reduction in low-end torque. Similarly, enrichment to keep the exhaust temperature sustainable in the exhaust tract components cannot be applied any more. The proposed study aims to provide a solution to keep the low end torque while maintaining lambda at 1. The tuning of the air intake system helps to improve the volumetric efficiency using resonance charging effects.
Journal Article

The Development of an Highly Modular Designed Zero-Dimensional Engine Process Calculation Code

2010-04-12
2010-01-0149
The main objective of the FVV-project “Cylinder Module” was the development of a profoundly modular designed concept for object-oriented modeling of in-cylinder processes of internal combustion engines. It was designed in such a way, that it can either be used as a stand-alone real working-process calculation tool or in tools for whole vehicle simulations. It is possible to run the “Cylinder Module”-code inside the FVV-“GPA”-software for transient vehicle and driving cycle simulations and it is possible to use the graphical user interface “ATMOS” of the “GPA”-project. The code can also be used as a user-subroutine in 1-D-flow simulation codes. Much effort was spent on the requirements of flexibility and expandability in order to be well prepared to cope with the diversity of both today's and future tasks. The code is freely available for members of the German Research Association for Combustion Engines (FVV).
Technical Paper

Validity of a Steady-State Friction Model for Determining CO2 Emissions in Transient Driving Cycles

2019-09-09
2019-24-0054
Due to its high benefit-cost ratio, decreasing mechanical friction losses in internal combustion engines represents one of the most effective and widely applicable solutions for improved engine efficiency. Especially the piston group – consisting of piston, rings and pin – shows significant potential for friction reduction, which can be evaluated through extensive experimental parameter studies. For each investigated variant, the steady-state friction measurements are fitted to an empirical polynomial model. In order to calculate the associated fuel consumption and CO2 emissions in transient driving cycles, the steady-state friction model is used in a map-based vehicle simulation. If transient engine operation entails friction phenomena that are not included in the steady-state model, the simulation could yield erroneous fuel consumption and CO2 predictions.
Technical Paper

Friction Reduction by Optimization of Local Oil Temperatures

2019-09-09
2019-24-0177
The reduction of engine-out emissions and increase of the total efficiency is a fundamental approach to reduce the fuel consumption and emissions of vehicles driven by combustion engines. Conventional passenger cars are operated mainly in lower partial loads most of their lifetime. Under these conditions, oil temperatures which are far below the maximum temperatures allowed, dominate inside the journal bearings. Therefore, the objective of this research project was to investigate possible potentials of friction reduction by optimization of the thermal management of the oil circuit of a combustion engine. Within the engine investigations, it was shown that especially the friction of the main and connecting rod bearings can be reduced with an increase of the oil supply temperature.
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