Variable capacity fuel tank

A fuel tank assembly for storing liquid fuel, the fuel tank assembly comprising:

• a tank defining a chamber;
• wherein the chamber defines a first maximum fill level defined by a first fuel blend and a second maximum fill level defined by a second fuel blend;
• wherein the first fuel blend has a density different from the second fuel blend;
• a fill tube defining an opening for receiving a nozzle and defining a first passageway that provides fluid communication between the opening and the chamber;
• a vent system including a vent tube defining a second passageway from the chamber to the exterior of the tank to permit air displaced by liquid fuel from the first passageway to be vented from the chamber;
• a floater attached to the vent tube;
• wherein:
• the second passageway is obstructable such that air is prevented from venting from the chamber through the vent system;
• the vent tube includes an inlet within the chamber;
• the inlet is in fluid communication with the first passageway via the second passageway;
• and
• a height of the inlet within the chamber is adjustably variable within a predetermined vertical range by vertical movement of the floater;
• wherein:
• the predetermined vertical range is limited by the first maximum fill level of the chamber and the second maximum fill level of the chamber;
• the floater exhibits buoyancy which is variable with a chemical composition of the liquid fluid;
• and
• adjustment of the height of the inlet is limited to adjustment within the predetermined vertical range;
• and
• wherein the vent system is configured such that whether the second passageway is obstructed, such that air is prevented from venting from the chamber through the vent system, is dependent upon the total volume of liquid fuel in the chamber and the height of the inlet defined at least partially by the chemical composition of liquid fuel in the chamber.

A fuel tank assembly that is fillable by a fuel pump, the fuel pump having a nozzle through which the fuel pump delivers liquid fuel and being configured such that the existence of a predetermined condition causes the fuel pump to stop delivering fuel, the fuel tank assembly comprising:

• a tank defining a chamber having a first maximum fill level and a second maximum fill level;
• a fill tube defining an opening configured to receive the nozzle of the fuel pump and defining a first passageway that provides fluid communication between the opening and the chamber to transfer liquid fuel from the nozzle to the chamber;
• a fuel pump shut-off system that is configured such that whether the predetermined condition exists when the nozzle is in the opening depends on a total volume of liquid fuel in the chamber and a chemical composition of the liquid fuel in the chamber;
• wherein:
• the fuel pump shut-off system is a vent system that defines a second passageway that extends from the chamber to the first passageway;
• the second passageway includes an inlet within the chamber;
• the inlet is obstructable to prevent passage of air from the chamber to the first passageway via the second passageway;
• a height of the inlet within the chamber is adjustably variable between the first maximum fill level and the second maximum fill level and adjustment of the height of the inlet is limited to a predetermined range defined by the first maximum fill level and the second maximum fill level;
• the first maximum fill level is defined by a first fuel blend having a first chemical composition;
• the second maximum fill level is defined by a second fuel blend having a second chemical composition;
• the liquid fuel in the chamber is comprised of at least one of the first fuel blend and the second fuel blend;
• the fuel pump shut-off system includes a sensor to sense a material property indicative of the chemical composition of the liquid fuel in the chamber and to cause adjustment of the height of the inlet to an adjusted height;
• wherein the adjusted height is between the first and second heights and is defined by the chemical composition of the liquid fuel in the chamber;
• and
• wherein the predetermined condition is the inlet at the adjusted height being sufficiently obstructed by the liquid fuel in the chamber flowing through the inlet and into the second passageway to prevent the passage of air via the second passageway from the chamber to the first passageway.