AIRCRAFT INSULATION SYSTEM AND AIRCRAFT AIR CONDITIONING AND INSULATION ARRANGEMENT

Abstract

An aircraft insulation system comprising a foil extending at a distance from an inner surface of an aircraft outer shell. An air gap is defined between the foil and the aircraft outer shell. A cabin exhaust air duct is arranged adjacent to an inner surface of the foil and being adapted to have cabin exhaust air flow through the duct.

Claims

1. An aircraft insulation system comprising: a foil extending at a distance from an inner surface of an aircraft outer shell, an air gap defined between the foil and the aircraft outer shell, and a cabin exhaust air duct arranged adjacent to an inner surface of the foil and being adapted to allow cabin exhaust air to flow through the duct.

2. The aircraft insulation system according to claim 1, wherein the cabin exhaust air duct comprises a cabin exhaust air outlet arranged in a ceiling region of an aircraft cabin.

3. The aircraft insulation system according to claim 1, wherein the cabin exhaust air duct extends from the ceiling region of the aircraft cabin substantially parallel to the aircraft outer shell into a lower deck of the aircraft.

4. The aircraft insulation system according to claim 1, further comprising a control unit adapted to control a flow of cabin exhaust air through the cabin exhaust air duct in such a manner that the cabin exhaust air, upon flowing through the cabin exhaust air duct, is cooled to a temperature of approximately 5 C. to 10 C.

5. The aircraft insulation system according to claim 1, wherein the foil is made of a watertight material.

6. The aircraft insulation system according to claim 1, wherein the foil is made of an airtight material.

7. The aircraft insulation system according to claim 1, wherein the foil comprises a plurality of foil sheets attached to an aircraft primary structure, the foil sheets extending between pairs of adjacent frames of the aircraft primary structure.

8. The aircraft insulation system according to claim 7, wherein the foil sheets are attached to the frames of the aircraft primary structure by means of a clamping arrangement.

9. The aircraft insulation system according to claim 8, wherein the clamping arrangement comprises a first and a second clamping element which are connected by means of a pin extending through a frame of the aircraft primary structure so as to fasten a first and a second foil sheet to opposing side surfaces of the frame.

10. The aircraft insulation system according to claim 8, wherein the clamping arrangement further comprises a clip extending from the inner surface of the aircraft outer shell adjacent to a side surface of the frame so as to be arranged between the first or the second clamping element and the side surface of the frame.

11. The aircraft insulation system according to claim 8, wherein a spacing between adjacent clamping arrangements in a circumferential direction of the aircraft outer shell is twice of the spacing between adjacent stringers of the aircraft primary structure.

12. An aircraft air conditioning and insulation arrangement comprising: an air conditioning unit for generating conditioned air, and an aircraft insulation system according to claim 1, wherein the air conditioning unit and the cabin exhaust air duct are connected to a mixer adapted to mix the conditioned air generated by the air conditioning unit with at least a part of the cabin exhaust air discharged from an aircraft cabin via the cabin exhaust air duct.

13. The aircraft air conditioning and insulation arrangement according to claim 12, wherein the cabin exhaust air duct is connected to a pressure regulation valve adapted to allow the discharge of at least a part of the cabin exhaust air flowing through the cabin exhaust air duct over board of the aircraft in order to regulate an aircraft cabin pressure.

14. A method of operating an aircraft air conditioning and insulation arrangement comprising: generating conditioned air by means of an air conditioning unit, discharging cabin exhaust air from an aircraft cabin via a cabin exhaust air duct, the cabin exhaust air duct being arranged adjacent to an inner surface of a foil extending at a distance from an inner surface of an aircraft outer shell so as to define an air gap between the foil and the aircraft outer shell, and mixing the conditioned air generated by the air conditioning unit with at least a part of the cabin exhaust air discharged from the aircraft cabin via the cabin exhaust air duct.

15. The method according to claim 14, wherein the cabin exhaust air is discharged from a ceiling region the aircraft cabin via a cabin exhaust air outlet of the cabin exhaust air duct.

16. The method according to claim 14, wherein the cabin exhaust air is directed through the cabin exhaust air duct from the ceiling region of the aircraft cabin substantially parallel to the aircraft outer shell into a lower deck of the aircraft.

17. The method according to claim 14, wherein at least a part of the cabin exhaust air flowing through the cabin exhaust air duct is discharged over board of the aircraft via a pressure regulation valve connected to the cabin exhaust air duct in order to regulate an aircraft cabin pressure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Preferred embodiments of the invention now are described in greater detail with reference to the appended schematic drawings, wherein

[0032] FIG. 1 shows an aircraft air conditioning and insulation arrangement, and

[0033] FIG. 2 shows a detailed view of an aircraft insulation system employed in the aircraft air conditioning and insulation arrangement of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] An aircraft air conditioning and insulation arrangement 100 according to FIG. 1 comprises an aircraft insulation system 10 and an air conditioning unit 12. The air conditioning unit 12 is operable so as to provide cool conditioned air to a mixer 14. As becomes apparent from FIG. 1, the air conditioning unit 12 and the mixer 14 are arranged in the region of a lower deck 16 of the aircraft. The lower deck 16 is separated from an upper deck 18, which accommodates an aircraft cabin 20, for example, a passenger cabin, by a floor 22.

[0035] The aircraft cabin 20 is air-conditioned by supplying air from the mixer 14 into the aircraft cabin 20 via conditioned air inlets 24 which are formed in sidewalls of the aircraft cabin 20 close to the floor 22. The conditioned air exits the conditioned air inlets 24 at a low speed of approximately 0.1 to 0.5 m/s so as to form a conditioned air layer over the floor area. The conditioned air then rises at heat sources present in the aircraft cabin 20, for example passengers, due to natural convection at a speed of approximately 0.05 m/s and exits the aircraft cabin 20 via a cabin exhaust air outlet 26 of a cabin exhaust air duct 28. The cabin exhaust air outlet 26 is arranged in the region of a ceiling 30 of the aircraft cabin 20. The cabin exhaust air duct 28 extends from the ceiling region of the aircraft cabin 20 in a circumferential direction of an aircraft outer shell 32 into the lower deck 16. In particular, the cabin exhaust air duct 28 extends substantially parallel to the aircraft outer shell 32 between the aircraft outer shell 32 and back walls of interior components such as ceiling panels 34, overhead luggage compartments 36 and sidewall panels 38. Basically, the cabin exhaust air duct 28 may be defined by a line or pipe. Preferably, however, the cabin exhaust air duct 28, in the region of the upper deck 18, is defined by a free space existing between the aircraft outer shell 32 and the back walls of the interior components.

[0036] In the region of the lower deck 16, the cabin exhaust air duct 28 comprises a first branch 28a and a second branch 28b. The first branch 28a of the cabin exhaust air duct 28 opens into the mixer 14 so as to supply cabin exhaust air discharged from the aircraft cabin 20 via the cabin exhaust air duct 28 to the mixer 14 as recirculation air. Within the mixer 14, the cabin exhaust air is mixed with the conditioned air generated by the air conditioning unit 12 and finally recirculated into the aircraft cabin 20 via the conditioned air inlets 24. The second branch 28b of the cabin exhaust air duct 28 is connected to a pressure regulation valve 40. Via the pressure regulation valve 40, cabin exhaust air flowing through the cabin exhaust air duct 28 may be discharged over board of the aircraft if needed for regulating an aircraft cabin pressure.

[0037] The cabin exhaust air duct 28, which forms a part of the aircraft insulation system 10, at a side facing the aircraft outer shell 32, is delimited by a foil 42. The cabin exhaust air duct 28 thus is arranged adjacent to an inner surface 43 of the foil 42. The foil 42, which is made of an airtight and watertight material, in particular an airtight and watertight plastic material, extends at a distance from an inner surface 44 of the aircraft outer shell 32. In particular, the foil 42 extends substantially parallel to the aircraft outer shell 32, wherein the distance between the inner surface 44 of the aircraft outer shell 32 and the foil 42 substantially corresponds to the extension of stringers 46, which form components of the aircraft primary structure 48, from the inner surface 44 of the aircraft outer shell 32 in a radial direction.

[0038] An air gap 50 is defined between the foil 42 and the aircraft outer shell 32. The air gap 50 is filled with air that is entrapped between the foil 42 and the aircraft outer shell 32. The air entrapped between the foil 42 and the aircraft outer shell 32 already provides for a thermal insulation of an interior of the aircraft cabin 20 against the aircraft outer shell 32 which during flight operation of the aircraft may be cooled to a temperature of approximately 30 C. to 55 C. A further insulation layer, which effectively insulates the aircraft cabin 20 against the cold aircraft outer shell 32, is formed by the warm and humid cabin exhaust air that is discharged from the aircraft cabin via the cabin exhaust air duct 28.

[0039] As a result, in the aircraft insulation system 10, conventional primary insulation packages can be dispensed with. Due to the presence of the foil 42, the air entrapped between the foil 42 and the aircraft outer shell 32 is separated from the warm and humid cabin exhaust air flowing through the cabin exhaust air duct 28 and hence, thermal energy losses can be reduced. Furthermore, icing of the inner surface 44 of the aircraft outer shell 32 due to the humidity contained in the cabin exhaust air is prevented.

[0040] As indicated in FIG. 1, upon flowing through the cabin exhaust air duct 28, the cabin exhaust air, due to the transfer of thermal energy to the cold aircraft outer shell 32, is cooled from a temperature of approximately 30 C. in the region of the cabin exhaust air outlet 26 to approximately 10 C. in the region of the floor 22. Specifically, a flow of cabin exhaust air through the cabin exhaust air duct, by means of a control unit 52, is controlled in such a manner that the cabin exhaust air, upon flowing through the cabin exhaust air duct, is cooled to a temperature of approximately 5 C. to 10 C. For example, the control unit 52 may control a conveying device (not shown) for conveying the cabin exhaust air through the cabin exhaust air duct 28 in such a manner that the volume flow of cabin exhaust air through the cabin exhaust air duct 28 is suitably adjusted in dependence on the temperature of the aircraft outer shell 32 in order to ensure cooling of the cabin exhaust air upon flowing through the cabin exhaust air duct 28 to the desired temperature of approximately 5 C. to 10 C.

[0041] Due to being precooled upon flowing through the cabin exhaust air duct 28, the cabin exhaust air enters the mixer 14 at a temperature that is significantly lower than the temperature at the cabin exhaust air in the region of the cabin exhaust air outlet 28. As a result, energy consumption of the air conditioning unit 12 for providing cold conditioned air to be mixed with the cabin exhaust air can be reduced. In addition, when the cabin exhaust air, upon flowing through the cabin exhaust air duct, by means of the control unit 52, is cooled to a temperature of approximately 5 C. to 10 C., the formation of ice due to the condensation of moisture contained in the cabin exhaust air, for example at the inner surface of the foil 42, can be avoided.

[0042] As becomes apparent from FIG. 2, the foil 42 comprises a plurality of foil sheets 42a, 42b, 42c that are attached to the aircraft primary structure 48. In particular, the individual foil sheets 42a, 42b, 42c extend in a circumferential direction along of the aircraft outer shell 32 between pairs of adjacent frames 54 of the aircraft primary structure 48. The foil sheets 42a, 42b, 42c are attached to the frames 54 by means of clamping arrangements 56.

[0043] Each clamping arrangement 56 comprises a first and a second clamping element 58, 60 which are connected to each other by means of a pin 62 extending through one of the frames 54, while clamping edges of two adjacent foil sheets 42a, 42b, 42c therebetween against opposing side surfaces 64, 66 of the frame 54. The foil sheets 42a, 42b, 42c thus are fastened to the opposing side surfaces 64, 66 of the frame 54. Each of the first and the second clamping element 58, 60 is made of a plastic material and has an L-shape cross-section with a first leg 58a, 60a and a second leg 58b, 60b. The first leg 58a, 60a, which abuts against the inner surface 43 of the foil 42, presses the foil 42 against a surface 68 of a stringer 46 which faces the aircraft cabin 20. The second leg 58b, 60b, which also abuts against the inner surface 43 of the foil 42, presses the foil 42 against a side surface 64, 66 of the frame 54. The clamping arrangement 56 further comprises a clip 70 extending from the inner surface 44 of the aircraft outer shell 32 adjacent to a side surface 64 of the frame 54 so as to be arranged between the first clamping element 58 and the side surface 64 of the frame 54.

[0044] A spacing between adjacent clamping arrangements 56 in a circumferential direction of the aircraft outer shell 32 is twice of the spacing between adjacent stringers 46 of the aircraft primary structure 48. Deformation and in particular sagging of the foil 42 can thus be prevented.

[0045] If the foil 42 is attached in a non-sealing manner, for example as described above, a certain air exchange between the cabin exhaust air duct 28 and the air gap 50 defined between the foil 42 and the aircraft outer shell 32 inevitably occurs even in case the foil 42 itself is made of an airtight material. Hence, the barrier defined by the foil 42 is permeable to air to such an extent that a desired pressure equalization between the cabin exhaust air duct 28 and the air gap 50 defined between the foil 42 and the aircraft outer shell 32 is possible.

[0046] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, the terms a or one do not exclude a plural number, and the term or means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.