Air-separation device, inerting device and aircraft comprising such a device

Abstract

The invention relates to an air-separation device comprising a generally cylindrical casing housing a filtration element including a bundle of hollow oblong fibers forming a membrane, the longitudinal axis of the fibers being parallel to the longitudinal axis (A) of the cylindrical casing, said casing comprising an air inlet at a first end and an outlet for purified gas at a second end. The device comprises a member for maintaining the fiber bundle in the casing, characterized in that the maintenance member comprises at least one spring member disposed inside the casing, said spring member being loaded between an end-stop formed by the casing and a longitudinal end of the fiber bundle in order to maintain the fiber bundle longitudinally in place while allowing it to dilate and contract.

Claims

1. An inerting device for an aircraft tank comprising an air separation device, said air separation device comprising: a casing having a generally cylindrical form and a longitudinal axis and having an air inlet orifice and a purified gas outlet orifice at first and second ends thereof, respectively; a filtration element enclosed within said casing, said filtration element comprising a bundle of hollow oblong fibers forming a membrane, a longitudinal axis of the fibers being parallel to said longitudinal axis of said cylindrical casing, said bundle having, at one or both ends thereof, a rigid layer of a material; a first retention unit supported on said rigid layer and being adapted and configured to retain said bundle of fibers in said casing, said first retention unit comprising at least one spring unit arranged inside said casing, each of said at least one spring unit of said first retention unit being compressed between a first longitudinal end of the bundle of fibers and a first stop that is formed by said casing so as to permit expansion or contraction of said bundle of fibers.

2. The device of claim 1, wherein said at least one spring unit of said first retention unit comprises at least one resilient washer.

3. The device of claim 2, wherein said at least one spring unit of said first retention unit further comprises a flat support washer that is arranged between, said at least one resilient washer of said first retention unit and the first longitudinal end of the bundle of fibers.

4. The device of claim 3, wherein said flat support washer is in contact with said at least one resilient washer of said first retention unit.

5. The device of claim 2, wherein said at least one spring unit of said first retention unit comprises a plurality of said resilient washers.

6. The device of claim 1, wherein said at least one spring unit of said first retention unit comprises at least one wavy resilient washer.

7. The device of claim 6, wherein said at least one wavy resilient washer comprises a plurality of wavy resilient washers and each of said plurality of wavy resilient washers of said first retention unit is stacked on a same side of said casing.

8. The device of claim 1, further comprising a second retention unit comprising at least one spring unit, said at least one spring unit of said second retention unit comprises at least one resilient washer, wherein: said bundle has a second longitudinal end opposite said first longitudinal end; and said at least one resilient washer of said at least one spring unit of said second retention unit being arranged between a second stop formed by said casing and said second longitudinal end of said bundle of fibers.

9. The device of claim 1, wherein said casing comprises two ends which are assembled to one another and form, respectively, a base and a cover of said casing.

10. The device of claim 9, further comprising a cylindrical central sleeve arranged in said casing around said bundle of fibers.

11. The device of claim 1, wherein said material of said rigid layer is a thermosetting material.

12. An aircraft comprising said inerting device of claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Other particular features and advantages will become apparent from reading the following description, provided with reference to the figures, in which:

(2) FIG. 1 represents a schematic partial view in cross section illustrating a first embodiment of a separation device according to the invention;

(3) FIG. 2 illustrates a front view in half cross section of an example of a resilient unit or spring which can be used in the separation device according to the invention;

(4) FIG. 3 represents a partial schematic view in cross section of an end of a separation device according to another embodiment of the invention;

(5) FIG. 4 represents a view in perspective of a cross section of an example of a retention unit for the device in FIG. 3.

(6) FIG. 5 illustrates an aircraft including an OBIGGS device including the separation device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(7) The air separation device represented in FIG. 1 comprises a casing 1, 2 with a generally cylindrical form which accommodates a filtration element comprising a bundle of hollow oblong fibers 3 forming a membrane. For example, these membranes are those marketed by the company MEDAL.

(8) As illustrated in FIG. 1, the casing can be formed by two ends 1, 2 which are assembled to one another and form respectively a base and a cover of the cylindrical casing.

(9) One or both ends 1, 2 can delimit the cylindrical central part of the casing. In addition, a cylindrical central core 7 (which for example is made of metal) can be provided. This cylindrical central core 7 can be connected to at least one of the two ends 1, 2. The central longitudinal axis of the cylinder is represented in FIG. 1.

(10) The longitudinal axis of the bundle of fibers 3 is parallel to the longitudinal axis of the cylindrical casing 1, 2 (i.e. parallel to the generatrices of the cylindrical part). Conventionally, at one end, the casing 1, 2 comprises an air inlet orifice 4, and, at a second end, a purified (nitrogen-enriched) gas outlet 5. For the purpose of simplification, the filtered gas (oxygen) discharge orifice is not represented in the figures.

(11) According to an advantageous feature, the device comprises a unit for longitudinal retention of the bundle of fibers 3 in the casing 1, 2, constituted by a spring such as a resilient washer 6. The resilient washer 6 is arranged inside the casing 1, 2 and is compressed between a stop 12 formed by the casing 1, 2 and an end of the bundle of fibers 3. By this means, the washer 6 ensures resilient axial retention of the bundle of fibers 3 in the casing 1, 2. In other words, the resilient washer 6 permits expansion or contraction of the bundle of fibers 3 in the casing (according in particular to the temperature of use. The outer diameter of the resilient washer 6 preferably corresponds to the inner diameter of the casing 1, 2).

(12) The resilient washer 6 thus makes it possible to absorb the axial compression forces, whilst allowing the cylinder of fibers to expand and contract freely, longitudinally, according to the development of the temperature.

(13) The resilient washer 6 is preferably a wavy resilient washer as represented in FIG. 2. One face of the ring formed by the resilient washer 6 is supported in the casing (or an element secured in the casing), whereas the other face of the washer 6 is supported on an end of the bundle of fibers 3.

(14) It will be appreciated that any other type of resilient unit such as a washer or spring can be envisaged, for example a (metal or other) compression spring forming a plurality of lobes which undulate according to a transverse cross section. For example the spring unit can comprise a wavy washer which is marketed by the company BORELLY and in particular a washer designated by the trade mark ONDULFIL?.

(15) In the case when the end of the bundle of fibers 3 is embedded in a rigid thermosetting material, the resilient washer 6 transmits forces to the fibers, without giving rise to shearing of this rigid part.

(16) In addition, the resilient washer 6 does not affect the surface of exchange of the gases between the bundle of fibers 3 and the remainder of the cylinder.

(17) The opposite longitudinal ends of the bundle of fibers 3 can each comprise a hollow area which is designed for the centering (these hollow areas are optional and unused in this example).

(18) The washer 6 can be used alone (as illustrated in FIG. 1), or it can be associated with a flat support washer 16 (which is not wavy, and therefore not resilient). For example, the flat support washer 16 can be arranged in contact with the bundle of fibers 3, whereas the wavy washer 6 is arranged between a stop of the casing 1, 2 and the flat support washer 16.

(19) The support washer 16 makes it possible to distribute the force applied to the bundle of fibers 3 better than the wavy washer 6 (unlike a flat washer 16, a resilient washer 6 is in contact with the bundle of fibers 3 only discontinuously).

(20) In a possible variant, a resilient washer 6 (alone or associated with a support washer 16) can also be arranged in the same manner at the other end of the bundle of fibers 3. In other words, the resilient retention is formed on both sides of the bundle of fibers 3.

(21) In addition, as illustrated in FIG. 4, the retention unit can be constituted by a plurality of stacked resilient washers 6 (for example two or three washers or more).

(22) The number of resilient washers 6 used can be selected according to the level of expansion of the bundle of fibers 3, and the precision of machining of the various parts.

(23) Thus, if a plurality of resilient washers 6 are necessary, they can be positioned on the same side of the bundle 3 in order to thrust the bundle of fibers 3 to the base of the casing 1, 2. In this case, the variation of dimension during the expansion of the membrane will take place entirely on the side where the resilient washers 6 are present (with a decrease in the volume of the chamber). On the contrary, this variation of volume will be distributed equally on both sides of the bundle 3 when the resilient washers 6 are provided on both sides of the bundle of fibers 3.

(24) The resilient washers 6 can be positioned entirely on the cover 2 side, i.e. on the inlet side. Since the pressure is generally greater on the gas inlet side, this arrangement has the advantage of making the spring or the washers work only to compensate for the dimensional variations caused by the thermal expansions or contractions.

(25) FIG. 3 illustrates a separation device in which the retention unit comprises two pairs of stacked washers at an end of the bundle of fibers 3, each pair of washers comprising a resilient washer 6 and a flat retention washer 16. The support washer 16 for one of the pairs of washers 6, 16 is supported on the end of the bundle of fibers 3, on the end impregnated with the rigid material (represented spotted with dots in FIG. 3). As illustrated in FIG. 3, the periphery of the bundle of fibers 3 impregnated with the rigid material 8 can comprise an outer layer 88 of pure rigid material (i.e. without the fibers of the membrane). This layer 88 of pure rigid material can be designed to accommodate at least one seal 14 for sealing with the casing 1, 2 (for example an O-ring seal). In addition, in order not to obstruct part of the active surface, the washer(s) 6, 16 is/are preferably supported on this layer 88 of pure rigid material (and not on the layer of rigid material mixed with the fibers).

(26) In the non-limiting example represented in FIG. 3, the bundle of fibers 3 comprises a central tube 12 (which for example is made of aluminum), the end of which is closed by a stopper 13 (which for example is screwed into the tube 12).

(27) The above-described solution(s) permit(s) symmetrical machining of the rigid parts of the device, and therefore undifferentiated fitting in one direction or the other. In addition, the number of parts used in the fitting is relatively limited, and makes possible a reliable system.

(28) In addition, the solutions described allow the assembly of the fibers (membrane) to expand and contract freely, by limiting or reducing the lever arm which is applied to the epoxy ends of the membrane, in comparison with the solutions where the retention force is applied to the central part.

(29) As illustrated in FIG. 5, the device 11 can be used in a system (OBBIGS) for inerting the tank 10 of an aircraft.

(30) While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.

(31) The singular forms a, an and the include plural referents, unless the context dearly dictates otherwise.

(32) Comprising in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing i.e. anything else may be additionally included and remain within the scope of comprising.

(33) Comprising is defined herein as necessarily encompassing the more limited transitional terms consisting essentially of and consisting of; comprising may therefore be replaced by consisting essentially of or consisting of and remain within the expressly defined scope of comprising.

(34) Providing in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.

(35) Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

(36) Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.

(37) All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.