Nitrogen enriched air supply system and aircraft

Patent metadata

Field	Value
Publication number	US-2016009408-A1
Application number	US-201314070811-A
Country	US
Kind code	A1
Filing date	Nov 4, 2013
Priority date	Nov 9, 2012
Publication date	Jan 14, 2016
Grant date	—

Abstract

To provide a system which supplies nitrogen enriched air (NEA) produced by using bleed air as a supply source of the NEA to a fuel tank, and which can further improve the fuel consumption. The present invention employs an NEA supply system 10 that controls a supply in a flow control valve (FCV) 11 so as to obtain a supply flow rate Fs as a value obtained by adding a small margin flow rate Fm to a required amount Fn of nitrogen enriched air required to be supplied to a first fuel tank 15, in at least a part of a descent phase of an aircraft 100. Accordingly, explosion of the first fuel tank 15 can be prevented, and the fuel consumption of an engine 1 can be improved in the descent phase.

First claim

1 . A nitrogen enriched air supply system which supplies nitrogen enriched air that is enriched with nitrogen to a fuel tank of an aircraft, the system comprising:
a nitrogen enrichment unit that produces the nitrogen enriched air upon supply of bleed air from a flight engine of the aircraft; a flow regulation unit that controls a supply of the nitrogen enriched air to the fuel tank; a residual fuel detector that detects an amount of residual fuel remaining in the fuel tank during a flight of the aircraft; and a control unit that controls the supply in the flow regulation unit and acquires information regarding the amount of residual fuel detected by the residual fuel detector, wherein the control unit controls the supply in the flow regulation unit so as to obtain a supply flow rate Fs having a predetermined relationship with a required amount Fn of the nitrogen enriched air required to be supplied to the fuel tank in at least a part of a descent phase of the aircraft, the required amount Fn being dependent upon the amount of residual fuel remaining in the fuel tank.

2 . The nitrogen enriched air supply system according to claim 1 , wherein
the required amount Fn is determined based on a state equation for gas, and the supply flow rate Fs is given by adding a margin flow rate Fm to the required amount Fn.

3 . The nitrogen enriched air supply system according to claim 2 , wherein
the required amount Fn is determined based on a following expression (3):
Δ n=ΔP*Vu/R*T   (3)

where Δn is a physical amount of the gas, ΔP is a pressure variation per unit time, Vu is an empty capacity of an internal space of the fuel tank, R is a constant of the gas, and T is a temperature, wherein a calculation of Vu is performed by the control unit and is based upon the amount of residual fuel remaining in the fuel tank.

4 . The nitrogen enriched air supply system according to claim 1 , wherein
the supply flow rate Fs is given based on data held in the control unit in advance in which the required amount Fn and a value obtained by adding the margin flow rate Fm to the required amount Fn are related to each other.

5 . The nitrogen enriched air supply system according to claim 1 , wherein
a concentration of nitrogen contained in the nitrogen enriched air supplied to the fuel tank is gradually decreased, in the descent phase of the aircraft.

6 . The nitrogen enriched air supply system according to claim 1 , wherein
a concentration of oxygen contained in the nitrogen enriched air supplied to the fuel tank is gradually increased, in the descent phase of the aircraft.

7 . The nitrogen enriched air supply system according to claim 2 , wherein
the supply flow rate Fs is given by adding the margin flow rate Fm to the required amount Fn, in at least the part of the descent phase of the aircraft.

8 . The nitrogen enriched air supply system according to claim 1 , wherein
the supply flow rate Fs is lower than the required amount Fn, in at least a part of the descent phase of the aircraft.

9 . The nitrogen enriched air supply system according to claim 1 , wherein
the system further includes an altimeter that detects an altitude of the aircraft during a flight, the control unit acquires information regarding the altitude detected by the altimeter, and controls the supply flow rate Fs not to be increased, when the detected altitude reaches a reference value or a value lower than the reference value in the descent phase of the aircraft.

10 . An aircraft comprising the nitrogen enriched air supply system according to claim 1 .

11 . A nitrogen enriched air supply system which supplies nitrogen enriched air that is enriched with nitrogen to a fuel tank of an aircraft, the system comprising:
a nitrogen enrichment unit that produces the nitrogen enriched air upon supply of bleed air from a flight engine of the aircraft; a flow regulation unit that controls a supply of the nitrogen enriched air to the fuel tank; a residual fuel detector that detects an amount of fuel remaining in the fuel tank during a flight of the aircraft and a control unit that controls the supply in the flow regulation unit and acquires information regarding the amount of residual fuel detected by the residual fuel detector, wherein the control unit controls a supply flow rate Fs of the nitrogen enriched air which is supplied to the fuel tank so as to gradually increase in at least a part of a descent phase of the aircraft, the supply flow rate Fs being dependent upon the amount of residual fuel remaining in the fuel tank.

12 . The nitrogen enriched air supply system according to claim 11 , wherein
an oxygen concentration in the nitrogen enriched air gradually increases, in at least the part of the descent phase of the aircraft.

13 . The nitrogen enriched air supply system according to claim 11 , wherein
a nitrogen concentration in the nitrogen enriched air gradually decreases, in at least the part of the descent phase of the aircraft.

14 . An aircraft comprising the nitrogen enriched air supply system according to claim 11 .

15 . The nitrogen enriched air supply according to claim 1 , wherein the nitrogen enrichment unit comprises a polymer membrane that decreases a concentration of nitrogen contained in the nitrogen enriched air supplied to the fuel tank in the descent phase of the aircraft and increases a concentration of oxygen contained in the nitrogen enriched air supplied to the fuel tank in the descent phase of the aircraft.

16 . The nitrogen enriched air supply according to claim 1 , further comprising:
a temperature instrument that detects a temperature of an internal space of the fuel tank, wherein the control unit acquires information regarding the temperature detected by the temperature instrument, the required amount Fn being dependent upon the temperature detected by the temperature instrument.

17 . The nitrogen enriched air supply according to claim 11 , further comprising:
a temperature instrument that detects a temperature of an internal space of the fuel tank, wherein the control unit acquires information regarding the temperature detected by the temperature instrument, the supply flow rate Fs being dependent upon the temperature.

Assignees

• Mitsubishi Aircraft Corp

Inventors

• Fukuda Koki

Classifications

• B01D2258/06

  Polluted air · CPC title

• B64D2013/0677

  comprising on board oxygen generator systems · CPC title

• B01D2257/104

  Oxygen · CPC title

• B01D2256/10

  Nitrogen · CPC title

• B01D2053/224

  with hollow fibres · CPC title