Windshield Fogging Prevention by Means of Mean Radiant Temperature Sensor

Abstract

To improve driving safety it is of outmost importance to guarantee that the windshield never starts fogging by means of an automatic and reliable procedure. To reach this goal and keeping always in mind comfort and fuel consumption, a fogging condition estimation algorithm has been developed. It requires a Mean Radiant Temperature (MRT) sensor and a humidity sensor. The MRT sensor is placed on the cabin compartment roof and points towards the dashboard and the windshield. Therefore it may be used to estimate windshield inner surface temperature. Combining this last piece of information with cabin relative humidity measured by the humidity sensor, the estimation algorithm forecasts fogging conditions so that the automatic thermal control system is able to take actions before fogging starts to appear. Centro Ricerche Fiat has already developed for Fiat Auto and patented a cabin thermal control that uses as feedback just MRT and blown air temperature one. This approach is not only safer, but it allows also cost savings with respect to state of the art sensor layout.