Andreas Walter

ESTIMATION OF THE INSTANTANEOUS ENGINE TORQUE FOR VEHICLES WITH DUAL MASS FLYWHEEL (DMF)

Abstract Today, in many passenger cars and light trucks, the conventional driveline is extended by a dual mass flywheel (DMF). The DMF reduces driveline oscillations by mechanically decoupling the crankshaft and the transmission. Existing engine control systems are designed for conventional single mass flywheel (SMF) systems. In the future, to facilitate the optimal control of engines equipped with advanced DMF systems, such conventional control systems may require adaptation, modification or even replacement. In this approach, a method for estimating the instantaneous engine torque of vehicles with conventional combustion engines and dual mass flywheel is introduced. The reconstructed engine torque can be used advantageously for advanced controller designs (e.g. cylinder balancing, misfire detection, anti-jerk control, etc.) as well as for analysing the current state of the combustion engine regarding injection time and quantity, combustion quality, incylinder pressure, etc.

Compensation of sub-harmonic vibrations during engine idle by variable fuel injection control

Today, in many passenger cars and light trucks, the conventional driveline is extended by a dual mass flywheel (DMF). The DMF reduces driveline oscillations by mechanically decoupling the transmission from the periodic combustion events that excite the engine crankshaft. Existing engine control systems are designed for conventional single mass flywheel (SMF) systems. In the future, to facilitate the optimal control of engines equipped with advanced DMF systems, such conventional control systems may require adaptation, modification or even replacement. The basic task of idle speed control systems is to maintain a defined setpoint of rotational engine speed independent from engine operating conditions (e.g. load disturbances). Due to the torque reactions of the DMF, control systems designed for engines with SMF can be disturbed, leading to unstable engine idle (e.g. sub-harmonic vibrations, oscillations following load rejection, etc.) In this approach, an optimised solution for idle speed control regarding conventional combustion engines equipped with DMF is introduced. The enhanced control system is based on conventional PID-control strategies with improved fuel injection scheduling. Using incremental (i.e. tooth-to-tooth) engine speed, critical dead times, which can lead to limit cycles in non-linear closed-loop control circuits, are minimised. Limit cycles, which are distinguishable as sub-harmonic vibrations at the same frequency, are effectively reduced by improving load rejection at idle. The implementation of these solutions in current engine management systems requires no additional sensors or other hardware.

A MODEL-BASED COMPARISON OF TIME-DIVISION MULTIPLEX ACCESS AND NETWORK BASED COMMUNICATION SYSTEMS FOR SAFETY-RELEVANT AUTOMOTIVE ELECTRONIC ARCHITECTURES

Abstract As a possible alternative to TDMA-based automotive communication systems, a network based approach was presented in (Nenninger et al. 2006). Because of the complex topology dependent properties of the approach, an analytical investigation is only feasible for a limited set of parameters and topologies. Therefore a model of the network based approach, as well as a FlexRay model was implemented. Using these models, the two approaches are compared under different aspects. It is shown that the network based approach gives good results even for asymmetrical topologies and high network load.

Das Zweimassenschwungrad als virtueller Sensor

Im Rahmen eines Kooperationsprojekts der Universitat Karlsruhe (Th) mit der Firma LuK wurde ein Verfahren entwickelt, das es ermoglicht, auf Basis systemtechnischer Modellierung des Zweimassenschwungrads eine genaue Schatzung des in den Antriebsstrang indizierten Motormoments sowie des Antriebsstrangruckmoments durchzufuhren. Die Kenntnis des kontinuierlichen Motormoments uber den gesamten Arbeitsbereich des Verbrennungsmotors erlaubt eine effiziente und kostengunstige Umsetzung zahlreicher Steuerungs- und Diagnoseaufgaben aktueller und zukunftiger Motormanagementkonzepte.

The DMF as a virtual sensor: Real-time reconstruction of instantaneous engine and driveline torques

In a co-operative project between the University Karlsruhe (TH) and the company LuK a new method has been developed, which permits an accurate estimation of both the instantaneous engine and driveline torques, based upon the systematic modelling of the dual mass flywheel. Real time knowledge of the instantaneous engine torque allows the realisation of efficient and cost-effective algorithms for control and diagnosis (e.g. cylinder balancing and OBD-misfire detection) within future engine management systems.

Real-time calculation of the nitric oxide formation as an add-on for a zero-dimensional model of the diesel combustion

Abstract In this paper an approach is presented, to calculate the nitric oxide exhaust of the diesel combustion. To be able to use the model in HIL-simulations, it must be executed in real-time on special hardware. Therefore the model was developed as an enhancement for a zero-dimensional model of the diesel combustion, which is already used for a HIL-test-bench. After a description of the diesel combustion-model, the calculation of the nitric oxide formation is presented, which is divided into three parts. First, the temperature of the hot combustion zone must be calculated, because the average in-cylinder temperature of the zero-dimensional model is not adequate as input data for the subsequent parts. With the temperature of the hot combustion zone, the equilibrium of the combustion products can be solved. The concentration of these species are finally used for the calculation of the nitric oxide formation by the well-known Zeldovich-mechanism.