Experiment Research on High Frequency Making and Breaking Characteristics of Automobile Horn Contacts

Horn with mechanical contacts is the key component in automobile security system owing to alarming function. The making and breaking frequency of horn contacts is about 500Hz, therefore tens of millions of arc erosion during its life time caused contact degeneration and failure. The waveforms of horn contact voltage, coil current and contact resistance during operations were captured. The arcing and extinguishing procedure of automobile horn was investigated explicitly by electrical and time parameters. The variation principles of these parameters were studied. The life test results show that the peak value of contact voltage and current, actuation current, actuation time, arc time, extinction time, keeping closed time of horn are relate to the degenerative process of tungsten contact arc erosion. The degradation failure mechanism of horn results from electrical contacts is clarified in whole.