Hermann Rottengruber

Tracer-based laser-induced fluorescence measurement technique for quantitative fuel/air-ratio measurements in a hydrogen internal combustion engine

A measurement technique for the quantitative investigation of mixture formation processes in hydrogen internal combustion engines (ICEs) has been developed using tracer-based laser-induced fluorescence (TLIF). This technique can be employed to fired and motored engine operation. The quantitative TLIF fuel/air-ratio results have been verified by means of linear Raman scattering measurements. Exemplary results of the simultaneous investigation of mixture formation and combustion obtained at an optical accessible hydrogen ICE are shown.

Wasserstoff-Dieselmotor mit Direkteinspritzung, hoher Leistungsdichte und geringer Abgasemission

In einem von der Bayerischen Forschungsstiftung geforderten Projekt kooperierten die MAN B&W Diesel AG, Augsburg, mit dem Lehrstuhl A fur Thermodynamik und dem Lehrstuhl fur Verbrennungskraftmaschinen und Kraftfahrzeuge (LVK) der Technischen Universitat Munchen. Der vorliegende Bericht umfasst die am LVK durchgefuhrten experimentellen und theoretischen Untersuchungen eines Wasserstoff-Dieselmotors mit direkter Kraftstoffeinblasung, bei dem der Wasserstoff nahe dem oberen Totpunkt gasformig unter hohem Druck in den Brennraum eingeblasen und durch Selbstzundung entflammt wird. An einem Einzylinder-Versuchsmotor wird dieses Verfahren erstmals im realen Motorbetrieb systematisch untersucht.

Experimental studies on spark stability in an optical combustion vessel under flowing conditions

Besides mixture formation and combustion, ignition and robust flame kernel formation are the main parameters needed to realize the otto-cycle process. During much of the development history of combustion systems, the requirements on the ignition system have steadily increased but could always be fulfilled by the inductive ignition system. In contrast, some current developments in gasoline engine combustion concepts focus on the increase of cylinder charge which is often associated with supercharging or the increase of exhaust gas recirculation and/or air dilution. In such cases, the ignition and flame kernel formation becomes challenging. The increase of specific power by charging leads to higher gas densities at ignition requiring high ignition voltages of up to 40 kV which have to be covered by the ignition system. At part load conditions the ignition voltage demand is considerably lower, however the ignition conditions are much more critical due to low gas temperatures at ignition point and low chemical reactivity of lean mixtures. The electrical properties of the spark plasma, such as spark current, spark energy and spark duration as well as the interaction of the spark plasma with the internal engine flow are key factors in order to meet the aforementioned challenges.

Real-time assessment of in-cylinder pressure for fresh air mass estimation using the example of modern spark-ignited combustion engines:

This article describes an approach suitable for real-time application, which enables the estimation of the trapped air mass in the cylinder of a modern spark ignition engine using the information of a combustion pressure sensor. First of all, different criteria are derived and assessed from the in-cylinder pressure signal. Then, an empirical model on the basis of engine test bench measurements is developed. Finally, the results of the methods are compared with cylinder and cycle individually to a reference air mass, which is obtained by the engine measurements and a subsequent zero-dimensional low-pressure-based air mass calculation.

Sprayvermessung einer Benzin-Wasser-Emulsion

In der Geschichte des Verbrennungsmotors hat die Wassereinspritzung schon fruh Anwendung gefunden, insbesondere bei Flugzeugen und im Motorsport. Jedoch hat sie sich nie grosflachig im Serieneinsatz durchsetzen konnen. Grundsatzlich wird bei der ottomotorischen Wassereinspritzung die hohe Verdampfungsenthalpie des Wassers genutzt, um die Temperatur der Frischladung im Brennraum zu senken und damit die Motorleistung und den Wirkungsgrad zu steigern sowie die Abgasemissionen zu reduzieren.

Potential of Series-Compatible In-Cylinder Pressure Sensors for Gasoline Engines Using the Example of Ignition Angle Control

To meet increasingly stringent emission legislations, improving the combustion efficiency becomes essential in the development of modern gasoline engines. This paper presents a comprehensive overview of available methods to improve the spark timing for maximum break torque under use of the in-cylinder pressure signal. The suitability of a series-compatible pressure sensor for the use of ignition angle control is summarized and reviewed. Finally, the results of spark timing control in a test vehicle are discussed on base of chassis dyno measurements.

Measurement of a Direct Water-Gasoline-Emulsion-Injection

The investigation focus for combustion engines is on reduction of emissions as well as fuel consumption. By introducing the gasoline direct injection combined with downsizing the efficiency and the fuel consumption of gasoline engines has been optimized. An additional potential to the previous solutions provides the water injection. The article include the results of the fundamental research of water injection for combustion engines, it shows the influence of the amount of water in a water-gasoline-emulsion on the spray in a high pressure injection chamber. Therefor the spray of a gasoline direct injection injector is visualized by a high speed camera using the shadowgraph technique. DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4753

Self - sensing control of a single cylinder ICE with directly coupled PMSM

A system consisting of an internal combustion engine (ICE) directly coupled to a permanent magnet synchronous machine (PMSM) is considered, which can be used as a range extender in hybrid electric vehicles (HEV) or as a power unit. For control of both, the synchronous machine and the engine, it is necessary to know the position of the rotor / crankshaft. Instead of using a position sensor, the position will be determined indirectly by using only electric variables of the PMSM by a self-sensing method. In general the angle determined in this way is only used for the field orientation and speed control of the PMSM. In this paper it is shown that it can be also used to control the ICE. Therefore, the electric angle has to be transformed to an absolute angle of the ICE relative to the top dead centre (TDC). This angle can be used to set the ignition point, control the timing of the valves and the injection. To transform the electric angle to an absolute angle, the ICE is used as a sensor to determine the TDC. Therefore the compression torque of the ICE is estimated through the PMSM and compared with an ideal model. The resulting benefit of the proposal is that the TDC can be obtained sensorless, with an accuracy of +/- 0.8 degrees.

Efficient control of internal combustion engines for electric power generation without throttle actuator

A system consisting of an internal combustion engine (ICE) and an electric generator, as used in serial electric hybrid vehicles (EHV) or range-extended electric vehicles, is considered in this paper. The use of a torque controlled generator provides an additional actuating variable for the control of the ICE. In this way, the power of the ICE can be controlled without using throttle actuator while following nearly maximum efficiency trajectory. A simple control algorithm is proposed for this approach based on an inner speed and outer power control loop. The resulting system is simple, robust and efficient requiring less energy storage than the usual on/off control strategy for EHV. The proposed algorithm has been implemented in a prototype and validated experimentally.

Vorausschauende Betriebsstrategie von Hybridfahrzeugen mit Backend-Anbindung

Zusammenfassung Um die steigende Komplexität von Hybridfahrzeugen zu beherrschen und deren Potential vollständig auszuschöpfen, ist eine intelligente Betriebsstrategie notwendig. Die mathematische Optimierung solcher Strategien benötigt hohe Rechenleistung und Kenntnis über die vorausliegende Strecke. Da beides nur eingeschränkt im Fahrzeug verfügbar ist, wird in diesem Beitrag vorgeschlagen, die Mobilfunk-Verbindung moderner Fahrzeuge zu nutzen. Die Prädiktion auf Basis von aufgezeichneten Fahrprofilen anderer Fahrzeuge, und die nachfolgende Optimierung der Betriebsstrategie werden auf stationären Backend-Servern durchgeführt.