Wolfram Schmid

Die neue Dieselmotorenbaureihe für schwere Nutzfahrzeuge von Daimler

Im Rahmen der Konzernweiten globalen Vereinheitlichung des Produktportfolios entwickelt die Daimler AG eine neue Motorenbaureihe — die „Heavy Duty Engine Platform” fur den Einsatz in schweren Nutzfahrzeugen. Mit der Vorstellung des Detroit Diesel DD15 wurde aktuell der erste Motor dieser Motorenfamilie mit 14,8 l Hubraum auf dem nordamerikanischen Markt eingefuhrt. Weitere Varianten dieser Plattform werden mit den Hubraumen 15,6 l, 12,8 l sowie 10,6 l folgen. Diese Motoren halten dann Schritt fur Schritt Einzug in alle Lkw der Daimler AG.

Local Linear Model Tree (LOLIMOT) for Nonlinear System Identification of a Turbocharger with Variable Turbine Geometry (VTG)

Abstract This paper deals with nonlinear dynamic system identification by local basis function networks. A special kind of local basis function network generated by a tree construction algorithm is proposed. This local linear model tree (LOLIMOT) is applied for identification of a truck Diesel engine exhaust turbocharger with variable turbine geometry (VTG). The charging pressure is modelled as the output of a nonlinear second order multiple input system with engine speed, pulse width of injection and VTG control signal as inputs. The LOLIMOT approach was capable to identify the turbocharger with measured signals from engine test stand experiments and with fifteen local linear models in less than one minute on a Pentium PC.

Innovative Variable Turbine Concept for Turbochargers

New concepts for the optimisation of supercharging systems have been analysed to improve fuel consumption, emissions and transient diesel engine response. In addition to the conventional VTG (Variable Turbine Geometry) where the variability takes place upstream of the turbine impeller, a new innovative variable turbine geometry called VOT (Variable Outlet Turbine) is investigated in this paper where the variability takes place at impeller exit. The flow variability is achieved by variation of the flow cross-section at the turbine outlet using an axial displacement of a sliding sleeve over the exducer and provides a simple solution for flow variability. The flow field of the VOT is calculated by means of steady state 3D-CFD simulations to predict the aerodynamic performance as well as to analyse the loss mechanisms. The VOT design is optimised by finding a good balance between clearance and outlet losses to improve the turbine efficiency. Furthermore, experimental results of the VOT are presented and compared to a turbine equipped with a waste gate (WG) that verify the efficiency advantage of the VOT. In general, it is found that the use of the VOT at high specific speed is important to reduce the outlet losses and to improve the turbine efficiency over a wide operating range.Copyright