METHOD FOR OPERATING HOT-FILM AIR-FLOW SENSORS

摘要

The invention relates to a method for operating a hot-film air-flow sensor (110), which can be used in particular for measuring air-flow streams in the induction tract of an internal combustion engine. The hot-film air-flow sensor (110) comprises a sensor chip (122) containing a sensor frame (138) and a sensor membrane (124) with at least one heating element (126) and at least two temperature sensors (128), a chip carrier (118) for retaining the sensor chip (122) and at least one additional heating element (150). The latter (150) enables the sensor chip (122) to be heated. Immediately after the internal combustion engine has been switched off, the heating element(s) (126) of the sensor membrane (124) is or are switched off or switched to a lower heating output. In addition, the additional heating element(s) (150) is or are switched on for a predetermined post-heating phase. The method is particularly suitable for preventing the contamination of the hot-film air-flow sensor (110) by oil.