Key parameters' correlation analysis on high-speed solenoid valve electromagnetic force under overall operating conditions

Abstract: Electronic unit pump (EUP) is a timing controlled fuel injection system used in diesel engines to meet the increasingly strict exhaust emission regulation and improve the economy of the fuel injection. As the key actuator of EUP, high-speed solenoid valve (HSV) determines the fuel injection timing and quantity in EUP. The electromagnetic force of HSV has a significant influence on the response speed and the stability of EUP, which depends greatly on the structure parameters of HSV. However, it is still not comprehensive in the parameter analysis of HSV for most experiments and simulations on the influence rules of single parameter on electromagnetic force or the parameters' influence rules for only one operating condition of HSV. In order to improve effectiveness of HSV's parameters' design and matching, six parameters' influence rules and the parameters' interaction principles on electromagnetic force under overall operating conditions were revealed by correlation analysis. Coils, armature and iron core were the most important parts for generating the electromagnetic force of HSV, and the 3D numerical simulation model of HSV was established in Ansoft Maxwell according to the three parts' actual structures, moreover the accuracy of the model was verified at different working air gaps and driving currents by experiment. Pole length, coil turns, coil location, armature thickness, damping hole location and damping hole radius were selected as the six key parameters of HSV and every parameter's three levels were determined based on their actual values. Due to HSV's working characteristics, the overall operating condition of HSV was dispersed into nine operating condition points to approximate HSV's entire working process. Based on the three levels of each of the six parameters, 47 sample points of the parameters combinations were obtained effectively and accurately by the method of design of experiments (DOE), in which the electromagnetic force was determined as a response variable and the six parameters were selected as experimental factors. Then the electromagnetic force of 423 sample points were got by using the 3D numerical simulation model of HSV to do experiment with the same times. At last, the correlation coefficients of first and second order factors formed by the six key parameters with electromagnetic force were explored under overall operating conditions according to the thought of correlation analysis. By making correlation analysis, the influence rules of the first order factors on electromagnetic force were revealed under overall operating conditions. The rules showed that one factor with significant correlation to electromagnetic force was coil turns, and the correlation decreased with the increase of driving current and increased with the increase of working air gap under different working conditions; the other factor with significant correlation to electromagnetic force was armature thickness, and the correlation increased with the increase of driving current and decreased with the increase of working air gap under different working conditions. The correlations of second order factors to electromagnetic force tended to be very complicate under overall operating conditions. In addition, the interaction principles of coil turns with armature thickness, armature thickness with damping hole location and damping hole location with damping hole radius were revealed. The electromagnetic force of HSV is determined by the complex interactions of characteristic parameters.