Modeling and Experimental Verification of Contact Sliding Behavior for Flexible Spring Components Within Electromechanical Relays

The electrical contact reliability of electromechanical relays is affected by the mechanical contact sliding behavior greatly. The whole contact sliding behavior of spring components involves the free travel stage and the overtravel stage. In this paper, a novel mathematic model of the typical flexible spring components within electromechanical relays is built to calculate the contact sliding distance (SD). Two variant types of this model are presented to satisfy different spring components configurations. The main influencing factors of contact SD, including the length of the movable spring, contact gap between two contacts, the head height, and diameter of the movable contact, are studied in detail. Furthermore, the contact SD and broadside lines of contact pair are captured in situ and measured by introducing a charge-coupled device (CCD) camera with a highpixel resolution. The comparison between analytical calculation results and experimental results shows the accuracy of the built model. Finally, the interrelation between contact force, electrical contact resistance, and contact SD is experimentally investigated. It is found that approximately linear relationships exist between the contact SD, contact force, and the forward distance of the push rod.