The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 23, 1993
Filed:
Mar. 19, 1992
Johann Siebler, Fahlenbach, DE;
Stephan Pelters, Tiefenbronn, DE;
Andreas Blumenstock, Ludwigsburg, DE;
Helmut Denz, Stuttgart, DE;
Axel-Rene Michelet, Karlsfeld, DE;
Siegfried Wesinger, Furstenfeldbruck, DE;
Kurt Almstadt, Wendeburg, DE;
Jens Druckhammer, Braunschweig, DE;
Robert Bosch GmbH, Stuttgart, DE;
Audi AG, Ingolstadt, DE;
BMW AG, Munich, DE;
Dr.Ing.h.c. F. Porsche Aktiengesellschaft, Stuttgart-Zuffenhausen, DE;
Volkswagen AG, Wolfsburg, DE;
Abstract
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.