Capacitive filling level sensor for determining filling level of aqueous urea solution for denitrification of exhaust gases of internal combustion engine, has electrically non-conductive layer covering electrodes in fluid switching region

摘要

The sensor (1) has measurement electrodes (3, 4) provided with an electrically non-conductive layer (5) such as anodic coating layer and hard anodized layer. The electrically non-conductive layer completely covers the electrodes in a fluid switching region. Layer thickness of the anodic coating layer and the hard anodized layer is constant in a longitudinal direction of the electrodes. The anodic coating layer exhibits layer thickness of 20 to 25 micrometers and/or the hard anodized layer exhibits 40 to 120 micrometers. The electrodes are made of aluminum.