Robert Boschgmbh

Bayerische Motoren Werke Aktiengesellschaft

Dr. Ing. H.c. F. Porsche Aktiengesellschaft

Audi Ag

Volkswagen Ag

Bmw Ag

Siegfried Wesinger

Helmut Denz

Andreas Blumenstock

Stephan Pelters

Johann Siebler

Kurt Almstadt

Axel-Rene Michelet

Andreas Schuers

Martin Scholz

Axel Michelet

Fuel supply system of an internal-combustion engine

The invention is directed to a method of checking the tightness of a tank-venting apparatus for a motor vehicle having a fuel tank and an internal combustion engine including a lambda controller and an air intake pipe. The tank-venting apparatus includes an adsorption filter, a supply line interconnecting the adsorption filter and the fuel tank, a connecting line interconnecting the adsorption filter and the intake pipe and a tank-venting valve mounted in the connecting line between the adsorption filter and the intake pipe. The method includes the steps of: measuring the pressure difference between pressure in the tank and ambient pressure; when the tank-venting valve is opened, determining whether the pressure difference increases above a threshold value and whether a lean correction by the lambda controller is required; and, drawing the conclusion that the tank-venting apparatus leaks when neither a lean correction is determined nor the pressure difference exceeds the threshold value. The method is based on the recognition that, when the tank-venting valve is open, either an underpressure must build up in the tank or a lean correction must be determined by the lambda controller based on the fuel vaporizing in the tank. The method is very reliable by simultaneously carrying out these two checks.

Tank-venting apparatus as well as a method and arrangement for checking

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Furstenfeldbruck, Germany

Siegfried Wesinger