Patent ID: 7163004

Claim:
A ventilation system for the fuel tank ( 1 ) of an internal combustion engine ( 3 ), in which a) the ventilation passes through an adsorption filter ( 4 ), b) the adsorption filter is regenerable by backwashing with atmospheric air, c) the backwashing air is supplied to the air intake area of the internal combustion engine ( 3 ), d) the connections leading from the adsorption filter ( 4 ) on the one hand to the atmosphere and to the intake area of the internal combustion engine ( 3 ) on the other hand can be interrupted by a first and second cutoff valve ( 9 , 10 ), e) the interior of the tank ( 1 ) and the air carrying area between the tank ( 1 ) and the cutoff valves ( 9 , 10 ) is connected to a pressure-measuring device for determining the pressure inside this entire area containing air when the cutoff valves ( 9 , 10 ) are closed, f) a pump ( 11 ) may be provided in the area carrying the backwashing air between the adsorption filter ( 4 ) and the intake area of the internal combustion engine ( 3 ), so that with the help of this pump, fresh air from the atmosphere can be introduced into the area between the tank ( 1 ) and the cutoff valves ( 9 , 10 ), comprising at least one of the following features: g) the first cutoff valve ( 9 ) leading to the atmosphere is in a line ( 8 ) which leads from the adsorption filter ( 4 ) through the air intake filter ( 2 ) of the internal combustion engine ( 3 ) to the atmosphere, through which a connection to the atmosphere is possible only through the air intake filter ( 2 ), h) if a pump ( 11 ) is present, it is connected with the atmosphere during intake of fresh air, to be introduced in the region between the tank, on the one hand, and the valves ( 9 , 10 ) on the other hand, by way of the air intake filter ( 2 ) of the internal combustion engine ( 3 ).