Research on Temperature Suppression Scheme of Electromagnetic Valve Train Based on Pumping Effect

Abstract:

Electromagnetic valve train (EMVT) in camless engine offers large potential for both part load fuel economy and high load engine torque. However, the temperature rise of EMVT at the high engine speed and full load is serious because of its large power density, which barricades the development of EMVT. According to the structure characteristic and operating principle of moving coil electromagnetic valve train, a novel scheme based on pumping effect of moving coil was proposed to enhance the gas flow rate and flow velocity in air gap between the moving coil and permanent magnetics, and strengthen the effect of convective heat transfer without additional drivers. Based on the theoretical analysis of convective heat and mass transfer, the main influential factors of this temperature suppression scheme were got, which includes the gas flow and gas peak velocity in air gap. Numerical model of flow area was established to analyze the dynamic responses of annular throttleslice and gas flow status, then structure of the scheme was improved accordingly. Simulation results indicate that the improved scheme, of which the material of annular throttleslices is carbon fiber and its working stroke is 0.2mm, then the gas flow and peak velocity of each cycle have reached to the maximum about 1.21mg and 58.9m/s under typical condition, respectively. Finally the temperature tests of electromagnetic valve train were carried out under longtime operation, results show that the improved scheme has achieved a better efficiency to suppress the temperature of electromagnetic valve train, it has a significant drop about 12.1℃ in maximum for one measuring point under typical condition.