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Theoretical and Experimental Analysis of Electromagnetic Variable Valve Timing Control Systems for Improvement of Spark Ignition Engine Performance

Elkady M, Elmarakbi A, Knapton D, Saleh M, Abdelhameed M and Bawady A

The objective of this paper is to meet the requirements of higher torque values at all engine speeds. This can be achieved by varying the valve timing automatically using a new variable valve timing system (VVT), which gives continuously variable valve actuation at all engine speeds. A model engine is designed using dimensional analysis methods and then implemented to verify the proposed control system. Moreover, microcontroller and computeraided control systems are constructed and used to modify the variable valve timing control in the laboratory. In this paper, a mathematical model of variable valve timing is developed to obtain the best volumetric efficiency with optimum valve timing at different engine speeds. From this model, the look-up table is created at all ranges of the engine speed. A single cylinder engine is used to estimate engine performance characteristics for conventional camshaft. In addition, a model engine is designed and constructed to apply the Variable Valve Timing control system. The investigations show that the system is flexible throughout the entire range of operation speeds and is able to alter valve timing concerning both valve opening and closing. The ability of valve opening and closing can be realized with rates higher than these of the conventional timing mechanisms.