Evaluation of fuel efficiency of the car owing to change of engine cylinders dimensions under condition of breaking force stream in transmission

Abstract

Problem. Application of repair dimensions method predetermines enlargement of cylinders liners diameters by means of boring, which causes increase of engine capacity. This will change not only the engine thrust, but also the indicators of its fuel efficiency, which requires further research. Goal. Computer simulation of car movement was conducted with different engine options, which took into account breaking of force stream while switching stepped gear box. For this typical riding cycles were used, which are regulated by current Ukrainian standards. Results. Computations of maximal acceleration while reverse gear is engaged are laid down into car raising simulation algorithm. The algorithm allows taking into account shifting of gear from lower to higher speed. The moment of gear shift is the point in time, when engine crankshaft rotation frequency reaches its maximum. In this case, there is a need to take into account breaking of force stream during gear switching with the help of the clutch. In this moment, the power is not transmitted to driving wheels and the speed is decreasing as a result of the act of running resistance force. Simulations results has shown that slight increase of cylinder diameter up to a repair size do not worsen indicators of car fuel efficiency (and even improve them up to 1,2%) because of increase of compression ratio. Originality. Algorithms of car movement simulation under conditions of typical riding cycles are implemented as software. Computer program, written in Delphi object–oriented language, provides high level of results accuracy, which was confirmed by road trials. Practical. Obtained results showed high efficiency of car engine repair by the means of repair dimensions method applied upon its cylinders. It was demonstrated, that such repair activities do not impair fuel-efficiency indicators of the car and will lead to substantial cost savings on spare parts.

Keywords

• fuel-efficiency
• automotive vehicle
• car engine
• stepped gear-box
• computer simulation