Improved performance of the electromagnetic fuel injector solenoid actuator using a modelling approach

The aim of this investigation was to develop a specific modelling approach capable of reducing the size of the fuel injector solenoid device while improving its response time and attraction force. Several developed modelling and simulation procedures have focused on various aspects of solenoid component modifications in order to develop an evolution process of miniaturising a fuel injector solenoid, using the latest finite element method (FEM) tool software. The specific factors that influenced the optimum operation of the fuel injector solenoid were the geometrical shape of individual solenoid components, material properties, air-gap constraints, boundary conditions, current source conditions, mass constants, and damping coefficients of the plunger. The attraction force distribution in the main air-gap was directly influenced by the taper angle of the 2D and 3D plunger pole faces, plunger length and the permanent magnetism. The precise definition of the electro-mechanical motion of plunger was of enormous importance in reducing the fuel injector solenoid response time, closely related to stroke and mass of the plunger, spring characteristics, motion and rebound of the plunger. Using the developed approach, the initial size of the fuel injector has been reduced by 35%, the attraction force increased by 26% and the response time reduced by 76%. However, by frequently repeating the design trials and conducting a thorough experimental investigation, the final minimum response time was achieved by the virtual rebound delay model. The reduction in response time from the 'optimal' experimental to virtual model was by 35%. The simplicity and effectiveness of the developed methods, allowed for quick and accurate evaluation.