Valve system for a fuel tank

A valve system for a fuel tank for the controlled, regulated, or guided output or input of a fluid from the or into the fuel tank, the valve system comprising:

• a) a housing;
• a1) a tank connection defined in the housing to connect the valve system to a fuel tank;
• a2) a filter connection defined in the housing to connect the valve system to an activated carbon filter;
• and
• a3) a filling tube connection defined in the housing to connect the valve system to a filling tube of the fuel tank;
• b) a main vent duct defined in the housing, wherein the tank connection and either of the filter connection or the filling tube connection are configured to be fluidically connected to one another by the main vent duct, wherein at least one main vent valve with a valve element is arranged in the main vent duct that closes the main vent duct in a closing position and releases the main vent duct in a releasing position;
• c) a secondary vent duct defined in the housing, wherein the tank connection or a tank-side main vent duct area in fluid communication with the tank connection and the filling tube connection or a filling tube-side main vent duct area in fluid communication with the filling tube connection are configured to be fluidically connected by the secondary vent duct;
• and
• d) at least one valve group with at least one secondary vent valve is defined in the secondary vent duct, the at least one secondary vent valve that closes the secondary vent duct in a closing position and releases the secondary vent duct in a releasing position, the at least one secondary vent valve being configured to be activated independently from the at least one main vent valve.