Search Results

Improvement of fuel economy is one of the most important development targets of modern passenger car engines. Modern solutions such as Direct Injection, Variable Valve Trains, or Cylinder Deactivation help to obtain this requirement. Each one of these techniques optimize the thermodynamic efficiency of the engine. However, the mechanical structure of combustion engines shows many areas of possible optimization regarding the mechanical efficiency. Engine friction affects the overall fuel consumption, mainly under low speed conditions combined with part load. Low speed/part load conditions are relevant for the real life fuel consumption of an engine, as well as friction improvements have significant effects on the fuel economy. The valve train drive produces the dominant friction portion under these conditions. Hence the friction optimization of this engine subsystem is one of the key issues regarding mechanical efficiency.

Due to the current changes in the automotive industry several new technologies are being developed and the old ones analyzed. The epicyclic gear trains, or planetary gear trains, are important in the automatic transmissions. In this paper a model is presented to describe the behavior of the transmission during the process of gear change. For this the system chose must be fully described, that means the relation among the rotations of the components must established.

Epicyclic gear trains are important part of automotive transmissions. They are present in automatic transmissions and in differentials of most vehicles. The dynamic behavior of a single epicyclic gear is well known, and this study presents the results obtained based in a model of a complete transmission. Initially the Wilson gearbox is presented. The main principles of the model are described. Following, the results of a simulation using the model are shown. Finally, the influence of the inertias in the model are presented and it is done some discussion about it

The aim of this article is to compare three strategies for motorization control of a servo assisted wheelchair. A servo assisted wheelchair is new conception of a therapeutic wheelchair. The model used in this development is based on doubled bicycle model which driven force applied over the rear wheels and the steering over the front wheels. For this article three strategies were developed and simulated one “on-off” control, one rule control and a fuzzy control. The most appropriated strategy for the studied system was a rule control, because it has a best performance in terms of the system displacement.