Study On Loop Resistance And Temperature Rise Of Contact Spring System Within Relays

Electromagnetic relays,as typical control components,are widely used in electrical and electronic systems such as aerospace,industry,and home appliances.The contact spring system of relay plays the role of conducting and breaking current,which is the main part of its structure.In order to scientifically and accurately evaluate the continuous power capacity of electromagnetic relay and its electrical contact reliability,this paper takes the contact spring system of electromagnetic relay as the research object,and carries out theoretical modeling analysis,finite element simulation analysis and experimental research on its loop resistance and contact temperature rise respectively.Firstly,the theoretical analysis method of loop resistance including contact resistance and contact temperature rise of contact spring system is put forward completely.The structural characteristics of three typical contact spring system are analyzed and summarized.The structural mechanics model of contact spring system is established by material mechanics,and the corresponding relationship between push rod displacement and contact pressure is obtained.Furthermore,the mathematical models of push rod displacement and contact resistance and loop resistance are established.Based on the thermal balance equation and φ-θ theory,the theoretical model of the contact temperature rise is established.It is found that the contact pressure increases linearly with the stroke of the push rod in the overrun stage,and the resistance of the loop and the contact temperature rise decrease linearly with the stroke of the push rod increasing.Secondly,a mechanical-electric-thermal coupling finite element simulation method for loop resistance and contact temperature rise of contact spring system is proposed.The contact stress,electric potential and temperature distribution nephogram of contact spring system are obtained by simulation calculation,and the relationship between contact pressure,loop resistance and contact temperature rise and moving spring displacement is analyzed.The influence of the length of the reed,the radius of curvature of the moving contact and the different structure types on the loop resistance is analyzed.The effects of film resistivity,comprehensive heat dissipation coefficient,current and ambient temperature on the contact temperature rise of the contact spring system are analyzed.Finally,the loop resistance and contact temperature rise experiment system with adjustable mechanical parameters of contact spring system are designed.The relationship between loop resistance,contact temperature rise,contact pressure,conduction current and conduction time is determined,and the simulation model of contact spring system is modified by experimental results.Combining experiments and simulation studies,the relationship between the limiting continuous current and the contact pressure in the contact spring system under the long-term work and the relationship between the maximum conduction current and the single conduction time under the short-time work are analyzed.The research in this paper can be used to optimize the structural parameters of electromagnetic relay contact spring system.