Abstract
Due to the tendentious raise of goods traffic especially in the growing European market and due to the raise of public traffic in urban centers commercial vehicles become more and more trendsetters under the aspects of environmental pollution. The trend towards low emission vehicles and fuel saving trucks and buses are some of the biggest impulses for the developing groups. Overall emission regulations as i.e. EURO IV claim to consider all kinds of energy saving potentials.
One of the non neglectible systems within this field of vehicles is the engine cooling system together with its aggregates. In case of commercial vehicles this system has to be seen under a lot of complex aspects. i.e. high fluid temperatures are reducing friction, low intake air temperatures are demanded by regulations, controlled fan drives are saving fuel and help to come towards low noise emissions, EGR systems and retarders are charging the cooling package to its maximum,
Because of complexity the stages of prototyping and optimizing are more and more supported by simulation methods to avoid fruitless development steps, to save money and time and to promote engineers creativity.
The aim of simulating the overall thermal management of vehicles is not only to find out the right dimensions and positions of the components, it gives us also a possibility to display various strategies of thermal management. The possibility to simulate i.e. the transient behavior of the viscous fan, to compare aggregates, to control various valves and thermostats can help to understand the linked systems and their interaction.
The simulation tool KULI was developed further to cover this field of automotive application. All cooling circuits as (coolant, charge air, oil, EGR) with their components can be seen from both points of view, the fluid side and the cooling air side. Control aggregates like thermostats and externally controlled viscous fan can be integrated within this model too. Branched fluid circuits as well as complex interlocked cooling packages can be set up using highly sophisticated physical models. The variation of ambient conditions also under transient conditions can be defined individually.
To implement user-defined control systems the software was opened towards MATLAB/SIMULINK (M/S). The advantages are that entire M/S models can be used further, extended by a proper heat management simulation tool and entire cooling system models can be extended by special user defined control algorithms.
The practical usage of this tool is shown in an actual example containing latest technology.