汽车继电器触点瞬态接触传热特性数值模拟分析

继电器是车辆电器控制的重要控制元器件,其工作环境是瞬间大电流通过周期性闭合的触点,由于接触触点间接触电阻在闭合瞬间大电流的作用下产生焦耳热,导致触点极易发生熔焊的可能,严重影响继电器的使用性能,危害行车安全,据统计触点部分的故障率占到继电器故障率的90%以上。揭示汽车继电器触点瞬态接触传热特性,对改善继电器触点触点熔焊故障具有重要的现实意。本文采用分型接触理论建立接触电阻模型,综合考虑触点间接触力、接触面积及材料的比热容、导热系数等,建立了继电器触点闭合瞬间大电流作用下的有限元模型,模拟计算触点间的瞬态热场分布,为改善继电器触头熔焊现象提供理论支撑。

Numerical Simulation Analysis of Transient Contact Heat Transfer Characteristics of Automobile Relay Contacts

Relay is an important control component for vehicle electrical control.Its working environment is that instantaneous high current passes through periodically closed contacts.The contact resistance between the contacts generates Joule heat under the action of the instantaneous high current closing,resulting in contacts.The possibility of welding is extremely prone to seriously affect the performance of the relay and endanger driving safety.According to statistics,the failure rate of the contact part accounts for more than 90%of the failure rate of the relay.Revealing the transient contact heat transfer characteristics of automotive relay contacts has important practical signifi cance for improving the welding failure of relay contacts.This paper adopts the sub-type contact theory to establish a contact resistance model,comprehensively considers the contact force between the contacts,the contact area,the specifi c heat capacity and thermal conductivity of the material,etc.,establishes a fi nite element model under the action of a large current when the relay contacts are closed,and simulates the calculation of the contacts.The transient thermal fi eld distribution provides theoretical support for improving the welding phenomenon of relay contacts.