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

Elkady M Elmarakbi A

doi:10.4172/2167-7670.1000105

Abstract

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.

Highlights

The concept of control system to improve the performance and to satisfy constant engine torque for internal combustion engines is well established
A main disadvantage of the conventional spark ignition engine (SIE) is decreasing of volumetric efficiency at most engine speeds that cause reducing in engine torque [1,2]
This mass is a function of engine speed, throttle valve position and valve timing, for a conventional engine the maximum volumetric efficiency will occur at a specific engine speed

Summary

Introduction

The concept of control system to improve the performance and to satisfy constant engine torque for internal combustion engines is well established. The variable valve timing is one of the ways used to improve the performance and satisfy constant engine torque requirements. Engine volumetric efficiency depends on the actual mass charge entering the cylinder in the admission stroke [3,4]. This mass is a function of engine speed, throttle valve position (engine load) and valve timing, for a conventional engine the maximum volumetric efficiency will occur at a specific engine speed

Objectives

Results

Conclusion