Inerting device, tank and aircraft provided with such a device, and corresponding method

A method for inerting a fuel tank of an aircraft, comprising the steps of:

• providing an aircraft;
• determining, with an electronic logic unit, the pressure differential between a pressure of an interior of a separate overflow space of the fuel tank and a pressure of an exterior of the tank;
• and when the pressure differential falls below a predetermined threshold S, allowing a flow of nitrogen-enriched gas from nitrogen-enriched gas generator into the overflow space via a second extremity, the aircraft comprising an aircraft fuel tank of the pressurized type, the electronic logic unit allowing the flow of nitrogen-enriched gas to the overflow space from the generator when the pressure of the exterior of the tank is greater than a pressure of the overflow space by at least 70% of a predetermined value associated with a second non-return valve, wherein the aircraft fuel tank comprises:
• a main vessel intended to store liquid fuel;
• the separate overflow space, the overflow space being fluidly connected to the main vessel in order to absorb temporarily, but without retaining, any overflows of liquid fuel from the main vessel, the overflow space communicating with an exterior of the tank via a first non-return valves and the second non-return valve, the first non-return valve only allowing a flow of gas from the overflow space to an exterior of the tank and being calibrated to open only when a pressure of the overflow space is greater than a pressure of the exterior of the tank by a predetermined value associated with the first non-return valve, the second non-return valve only allowing a flow of gas from the exterior of the tank to the overflow space and being calibrated to open only when the pressure of the exterior of the tank is greater than the pressure of the overflow space by the predetermined value associated with the second non-return valve;
• and
• an inerting device for a aircraft fuel tank of the pressurized type that is provided with a main vessel and with a separate overflow space, said inerting device comprising:
• the nitrogen-enriched gas generator;
• a circuit for transferring the nitrogen-enriched gas produced by the generator, the transfer circuit comprising an upstream extremity connected to the generator, a first downstream extremity which can be coupled to the main vessel and the second downstream extremity, the second downstream extremity which can be coupled to the overflow space;
• an array of sensors for measuring a pressure differential between a pressure of an interior of the overflow space and a pressure of an exterior of the tank, the array of sensors comprising at least one of the following:
• a sensor for the differential pressure, a couple of pressure sensors, a sensor for the altitude of the aircraft, a sensor for the atmospheric pressure around the aircraft, a sensor for the atmospheric temperature around the aircraft, a sensor for the rate of descent of the aircraft, a sensor for the fuel consumption of the aircraft, a sensor for the pressure of the inlet air supplying the generator for the purpose of its enrichment with nitrogen, a sensor for the temperature of the inlet air supplying the generator for the purpose of its enrichment with nitrogen, a sensor for the flow of nitrogen-enriched gas at the outlet from the generator, a sensor for the concentration of oxygen/nitrogen in the flow of nitrogen-enriched gas at the outlet from the generator, a sensor for the flow of nitrogen-enriched gas at the outlet from a buffer tank for storing the nitrogen-enriched gas produced by the generator, and a sensor for the concentration of oxygen/nitrogen in the flow of nitrogen-enriched as at the outlet from a buffer tank for storing the nitrogen-enriched gas produced by the generator;
• and
• the electronic logic unit for receiving the measured pressure differential from the array of sensors, the electronic logic unit being connected to the generator and/or to the transfer circuit, the electronic logic unit being designed to control a supply of the flow of the nitrogen-enriched gas to the second downstream extremity when the pressure differential is less than a predetermined threshold S, the first downstream extremity of the transfer circuit being coupled to the main vessel and the second downstream extremity of the transfer circuit being coupled to the overflow space.