Tony Sandberg

Modeling and Validation of Traveling Resistance for Heavy Trucks

Low fuel consumption is very important for a heavy truck. Doing measurements of fuel consumption in a real vehicle is though complicated and very time-consuming. The main problem is that measuremen ...

Tire Temperature Measurements for Validation of a New Rolling Resistance Model

Abstract Rolling resistance of inflated tires contributes greatly to the total load and fuel consumption of heavy vehicles. Correct modeling of rolling resistance is hence very important in order to be able to predict fuel consumption and emissions by computer simulations. Traditional models for rolling resistance are normally only valid under steady state conditions. A new model with improved transient characteristics has been derived in previous work. In this work the temperature dependent part of the adopted model is evaluated by experiments on a heavy truck tire. The measurements have been carried out on both a chassis dynamometer as well as on a truck in actual driving. The temperature has been measured on several positions inside the tire and in the encapsulated air. The results show very good repeatability indicating that tire temperature is an appropriate input to the model. The temperature rise due to a change in velocity shows an exponential relation to time, which corresponds to the new model. The study has been carried out for a number of different velocities and vertical loads. The results show that the temperature model can accurately capture both load and speed dependence. The study clearly shows that the model is able to reproduce tire temperatures measured on a truck driving on real roads with very good accuracy.

A SIMULATION TOOL FOR PREDICTING FUEL CONSUMPTION FOR HEAVY TRUCKS

Abstract Low fuel consumption is very important for a heavy truck. The best combination of engine. gearbox, central gear and tire dimension varies depending on transport task and road conditions. For these reasons it is important to find the best combination of powertrain components so that the optimum operationalarea of the engine can be used as much as possible. The differences between different combinations are usually very small so it is necessary to drive long distances to ensure a certain difference. This makes the problem suitable for computer simulation. A computer program to simulate fuel consumption and emissions for heavy trucks in long haulage has been created, using the object-oriented software DYMOLA. It has a longitudinal vehicle model and an engine model based on steady-state measurements. To control the simulations a special graphical user interface (GUI) is built in MATLAB. The GUI is used both as a preprocessor, for specifying vehicle and road, and as a postprocessor to evaluate and display results. Simulations are performed on recordings of real roads. In the program it is possible to simulatethe whole production range of engines, gearboxes, tire dimensions and so on.