Method and arrangement for detecting icing in pumps utilized in the diagnosis of tank leakage in motor vehicles

Abstract

A tank-venting system includes an active charcoal filter ( ), which is connected to a tank ( ). An intake manifold ( ) of an internal combustion engine is connected to a tank-venting valve ( ). The active charcoal filter ( ) stores fuel vaporized in the tank ( ). When the tank-venting valve ( ) is driven open by the control unit ( ), air from the ambient is drawn by suction through the active charcoal filter ( ) and the fuel stored therein is released to the inducted air. A pump ( ) is provided for checking the tightness of the tank-venting system and is connected to the control unit ( ). A switchover valve ( ) is connected downstream of the pump ( ). A reference leak ( ) is arranged in parallel to the switchover valve ( ). A throughflow sensor ( ) and a temperature sensor ( ) are connected forward of the pump ( ) which detect the scavenging air quantity, which is used to scavenge the active charcoal filter ( ), as well as the intake air temperature. The sensors transmit the scavenging air quantity and the temperature to the control unit ( ). Based on the scavenging air quantity and the intake air temperature, the control unit determines whether the pump ( ) is iced at the particular time point. In case of a determination of “iced”, the tightness measurement is not enabled by a control signal and/or the output of a fault signal, which indicates non-tightness of the tank-venting system, is suppressed.