FR3085100A1 - AVIONIC BAY WITH FLEXIBLE SEPARATION PARTITION - Google Patents

Abstract

Avionics bay for aircraft, comprising a rack device intended for the integration of equipment (5) and electrical wiring, as well as a device for cooling by circulation of a gas according to an incoming gas flow, called “cold flow ", Which arrives in the avionics bay to cool it, and an outgoing gas flow, called" hot flow ", which is evacuated from the avionics bay after passing through the equipment (5), the avionics bay comprising at least one box ( 4B, 4C) for gas circulation provided with a partition (8) for the cold flow and the hot flow delimiting two compartments (9, 10), this separation partition comprising a flexible veil.

Description

AVIONIC BAY WITH FLEXIBLE SEPARATION

DESCRIPTION

TECHNICAL FIELD [001] The invention relates to the field of aeronautics and relates to the avionics bays used in aircraft. The invention relates more precisely to the cooling of avionics bays.

Avionics bays are electrical cabinets on board an aircraft, which can accommodate electrical or electronic equipment, such as computers or other instruments, as well as electrical wiring connecting these equipment. These avionics bays are generally of considerable size and contain numerous electronic or electrical equipment close to each other, as well as a large quantity of cables. An avionics bay thus includes a rack device allowing the insertion and removal of equipment, and their mechanical support. An avionics bay moreover necessarily includes a cooling device ensuring that the equipment is kept within a temperature range acceptable for their operation. Avionics bay cooling devices generally include elements ensuring ventilation of the equipment by the circulation of a gas such as air.

STATE OF THE ART The patent application FR2957552 describes an avionics bay comprising two lateral uprights and shelves extending between these two lateral uprights. Each shelf is designed to support the equipment. Each shelf also forms an air circulation box, which is provided with a partition for separating the cold air flow and the hot air flow. The cold air flow arrives through one of the side uprights and is distributed to the shelves and is channeled so that an air flow passes through the equipment from the bottom up, the air flow leaving the equipment is then routed by the hot air compartment of the shelves and is then evacuated from the bay by the other lateral upright. In order to increase the thermal insulation of the flow separation walls and to increase the rigidity of these walls, this document proposes to produce this wall in a sandwich structure. This more rigid wall is considered to be more reliable and its insulating properties make it possible to avoid condensation phenomena on the partition wall. The partition wall being in contact with cold air on one of its faces and with hot air on the other of its faces, any humidity present in the flow of hot air may condense on the partition wall. Drops of water can form on the surface of the partition wall and can eventually run on electrical or electronic equipment. This turns out to be a critical risk for electrical or electronic aircraft equipment in general and for an avionics bay in particular, the latter containing all the equipment necessary for the flight of the aircraft.

The patent application FR2872640 describes an avionics bay comprising lateral uprights and shelves forming air circulation boxes each provided with a partition for separating the cold flow and the hot flow. In the avionics bay described, only one of the lateral uprights is used to supply the shelves with cold air and to evacuate the hot air. This lateral upright is itself an air circulation box and is also provided with a partition for separating the cold flow and the hot flow. These partition walls also present a risk linked to the appearance of condensation on the partition walls.

PRESENTATION OF THE INVENTION The invention aims to improve the avionics bays of the prior art by improving the cooling device so that it is lighter and quieter, and that the risk of condensation is eliminated. The avionics bay according to the invention is also simpler to manufacture and install.

To this end, the invention relates to an avionics bay for aircraft, comprising a rack device intended for the integration of electrical equipment and cables, as well as a device for cooling by circulation of a gas according to a incoming gas flow, called "cold flow", which arrives in the avionics bay to cool it, and an outgoing gas flow, called "hot flow", which is evacuated from the avionics bay after passing through the equipment, the avionics bay comprising at least one gas circulation box provided with a partition for separating the cold flow and the hot flow delimiting two compartments. The partition of this avionics bay comprises a flexible veil.

In such an avionics bay, the partition for separating the cold flow and the hot flow does not require any additional thermal insulation such as insulating foams. Indeed, it appears that the flexible veil of this partition wall prevents condensation phenomena even with a thin wall.

The invention also makes it possible to dispense with a sandwich structure or other insulators inserted into the thickness of the partition and which make this partition heavier or more complex and expensive to manufacture. The partition according to the invention provides a gain in mass.

The use of insulating foams glued to the partition wall is also not required. These foams present risks of moisture retention and appearance as a consequence of mold, as well as risks of detachment which can hinder the proper passage of the cooling gas.

The partition walls of the avionics bay according to the invention are not sensitive to vibrations and do not transmit the vibrations that they receive. This characteristic is essential because it has been observed in the avionics bays of the prior art a tendency to the vibration of the partition walls inside their air circulation box. These partition walls are thin walls relative to the rigid elements constituting the frame of the bay and their vibratory behavior is difficult to predict. These vibrations are a source of unwanted noise and are likely to reduce the reliability and service life of the cooling device. These vibrations also constitute a risk for the general operating safety of the avionics bay because they introduce uncertainty as to the natural frequency of vibration of the bay, in which the flows of cooling gases intervene. For this reason, the partitions of the prior art generally require good rigidity or the addition of reinforcements increasing in both cases the mass.

The partition comprising a flexible veil is not only insensitive to vibrations but also damps them, so that the general vibrational behavior of the avionics bay is improved.

In addition to acoustic comfort, the invention therefore provides better fatigue resistance.

The manufacturing method including the flexible veil is more simple and inexpensive. Great precision is not necessary in the manufacture and assembly of such a partition because it adapts well to differences in shape and position.

Maintenance is simplified: a partition which would be soiled by the passage of dirty air would not need to be cleaned on site. It would suffice to change it for a clean partition, and to wash it later for later use. End-of-life recovery and recycling of the flexible veil are also permitted.

According to one embodiment, the partition has a breathability characteristic so that a leak of the cooling gas is allowed between the two compartments delimited by the partition.

Thanks to this characteristic, a slight diffusion is allowed between the cold flow, which is under overpressure, and the hot flow, which is under depression. This slight diffusion creates on the surface of the partition, on the side of the hot flow, a film of fresh air forming a thermal barrier which adds to the efficiency of thermal insulation intrinsic to the partition.

According to one embodiment, the flexible veil of the partition wall is made of textile, woven or nonwoven. Textile fibers are favorably insulating.

The avionics bay according to the invention may include the following additional characteristics, alone or in combination:

- the flexible veil of the partition walls is a textile;

- the partition is arranged between two side members of the box;

- The box includes an inlet for the cold flow and an outlet for the hot flow, the partition being disposed between the outlet mouth and the inlet mouth;

- the avionics bay comprises a diaphragm for at least one of the inlet and outlet openings, the diaphragm being fixed on the partition wall;

- the partition is made of a single piece of flexible material;

- the partition is formed of a flat piece of material;

- the partition is formed of a piece of preformed material in three dimensions;

- The partition is formed of several parts forming a preform;

- at least one of said parts has conductive characteristics;

- at least one of said parts has breathability characteristics;

- the partition allows a leak between 0.1% and 0.5%;

- the partition includes a braid of conductive mass;

- the avionics bay comprises a lateral entry upright distributing the cold flow and a lateral exit upright recovering the hot flow, as well as shelves extending between these uprights and forming said at least one gas circulation box;

- The avionics bay has a lateral inlet and outlet upright distributing the cold flow and recovering the hot flow, the lateral upright forming said at least one box.

PRESENTATION OF THE FIGURES [0019] Other characteristics and advantages of the invention will appear on reading the nonlimiting description which follows, with reference to the appended drawings in which:

- Figure 1 is a schematic front view of an avionics bay according to the invention;

- Figure 2 is a perspective view of a shelf of the bay of Figure 1, devoid of partition;

- Figure 3 is a perspective view of a shelf in the bay of Figure 1, the partition being in place;

- Figure 4 shows a cross section of an electrical equipment of the rack of Figure 1 and the two adjacent shelves;

- Figure 5 is a detail of a partition wall of Figure 4;

- Figures 6 and 7 relate to a second embodiment of the invention and respectively represent an avionics bay viewed from the side and one of its uprights seen from above.

DETAILED DESCRIPTION [0020] FIG. 1 schematically represents an avionics bay 1 according to the invention seen from the front. The avionics bay 1 comprises two lateral uprights 2,3 between which extend in this example five shelves 4A, 4B, 4C, 4D, 4E. These elements, possibly fitted with known “chair” type supports, constitute a rack device receiving electrical or electronic equipment and their wiring.

The avionics bay 1 further comprises a cooling device arranged to circulate a cooling gas in the equipment 5. The cooling gas is, in this example, fresh air from the air conditioning system (not shown) of the aircraft. This fresh air is channeled inside the avionics bay 1 to pass through the equipment 5 then to come out warmer from the equipment 5 and then be evacuated from bay 1.

In the example of Figure 1, the cooling air circuit is the same as that described in document FR2957552. According to this arrangement, the fresh air pulsed by the air conditioning system enters through the lateral upright 2 which channels it to distribute it to each of the shelves 4A to 4E. Each of the shelves 4A to 4E is hollow to form an air circulation box. The shelves 4A to 4E may simply consist of a parallelepiped forming a shelf capable of mechanically supporting the equipment 5 and forming, inside the parallelepiped, a conduit for the circulation of the cooling air. The shelves 4A to 4E can, alternatively, be constituted by any suitable means making it possible to form an air circulation box by delimiting an interior space which channels the circulation of air.

In Figure 1, the lowest shelf 4A forms a box comprising a single compartment dedicated to the circulation of the cold air flow coming from the lateral entry upright 2. The lateral upright 2 is said to be "upright d 'entry' and the side upright 3 is said to be 'exit amount'.

This shelf 4A has, on its upper wall, perforations allowing the fresh air coming from the lateral entry upright 2 to pass through the equipment 5. These perforations can be produced for example on the shelf itself or on “chair” type devices which are fixed on the shelf 4A. The air passing through the equipment 5 heats up and this hot air then passes through perforations in the bottom wall of the shelf 4B above the equipment concerned. The hot air is then channeled through the top shelf 4B to the side outlet post 3. The lateral outlet post 3 is itself connected to the air conditioning system of the aircraft for the evacuation of hot air.

The fresh air which has not yet passed through the equipment 5 is here called "cold flow" and the air flow leaving the equipment 5, which has been heated by the equipment 5, is here called "hot flow" .

In Figure 1, the highest shelf 4E consists of a box delimiting a single compartment dedicated to the circulation, up to the lateral outlet 3, of the hot air after it has passed through the highest row of equipment 5.

Apart from the shelves 4A and 4E which have a single compartment due to their high and low end position, the three other shelves 4B, 4C, 4D interleaves each form a box in which two compartments are delimited: a dedicated compartment to the circulation of the cold flow and another compartment dedicated to the circulation of the hot flow. In this example, the intermediate shelves 4B, 4C, 4D delimit an internal parallelepiped volume, in the same way as the end shelves 4A, 4E. However, each of the intermediate shelves 4B, 4C, 4D comprises an opposite inlet mouth 6 and an outlet mouth 7, and comprises a partition wall 8 (shown diagrammatically in dotted lines in FIG. 1) arranged so as to separate: a first compartment 9 intended for the cold flow and communicating with the inlet mouth 6; and a second compartment 10 intended for the hot flow and communicating with the outlet mouth 7.

Thus, in each of the intermediate shelves 4B, 4C, 4D, the cold flow coming from the inlet upright 2 enters through the inlet mouth 6 and is channeled into the first compartment 9, then passes through the perforations of the wall top of the shelf to reach the equipment 5. In the second compartment 10 of the same shelf, the hot flow from the equipment 5 located below the shelf considered enters this shelf through the perforations of its bottom wall and circulates in its second compartment 10 to the outlet mouth 7 to join the lateral outlet upright 3 and then be evacuated from the avionics bay 1.

Figures 2 and 3 illustrate an embodiment of the partition 8. Figure 2 shows in perspective one of the intermediate shelves 4B, 4C, 4D, devoid of partition 8 and equipment 5. The the interior of the box formed by the shelf is thus visible.

The shelf 4B, 4C, 4D has two rails 11 for fixing the equipment 5. A ground bar 12 is further mounted on one of the rails 11, or on both. The earth bar (s) 12 are essential for mounting equipment 5 with a metal frame on a shelf 4B, 4C, 4D when this shelf is made of a non-conductive material, such as a composite material commonly used for making avionics bays .

Between the two side rails 11, the shelf 4B, 4C, 4D is arranged according to the equipment 5 to be fixed. The shelf 4B, 4C, 4D can receive, for example, one or more upper covers for its portions not occupied by a piece of equipment 5. The shelf 4B, 4C, 4D can also receive, for example, a perforated cover with a piece of equipment 5 attached above, or directly receive equipment 5 provided with its perforations. The shelf 4B, 4C, 4D can also receive, for example, "chair" type fasteners which include perforations, the equipment 5 being mounted on these fasteners.

The inlet ports 6 and the outlet ports 7 are visible on either side of the interior volume delimited by the shelf.

Figure 3 is identical to Figure 2 except that the partition 8 has been put in place. The partition wall 8 is here produced by a flexible veil held on the two longitudinal members 11 and is arranged so that:

- on the side of the outlet openings 7, the partition 8 is stretched between the two longitudinal members 11:

- on the side of the inlet openings 6, the partition 8 is on the contrary not stretched between the two longitudinal members 11 and thus follows the bottom of the box, passing under the inlet openings 6.

In this way, the partition 8 delimits, in the box formed by the shelf, two compartments, one of which is dedicated to the cold flow and the other is dedicated to the hot flow.

In the example of Figure 3, the partition 8 consists of a flat sheet of flexible material such as, for example, a woven or nonwoven fabric. It is the tensioned or non-stretched arrangement between the side members 11 which makes it possible (as illustrated in FIG. 3) to delimit two separate compartments each in communication with one of the inlet 6 or outlet 7. The flat sheet of fabric constituting the partition 8 has, when it is flat, substantially a trapezoid shape whose large base is located on the side of the inlet openings 6.

The partition 8 is fixed to the beams 11 for example by being sandwiched between a possible ground bar 12 and the beam 11 or directly between the equipment 5 and the beam 11. Alternatively, the partition 8 can be fixed to the side member 11 or to the edge of the shelf by any means such as gluing, stapling or the like.

The tightness between the partition 8 and the shelf can possibly be improved at the level of the inlet 6 and outlet 7 openings by any means such as fitting a joint or bonding. Another option to improve this tightness consists in sewing diaphragms 13 on the partition 8. The diaphragms 13 are elements as described in document FR2900308 and making it possible to calibrate the air flow entering or leaving the shelf. The diaphragms 13 can for example be made of a flexible cellular material which can be sewn. The stitching of the diaphragms 13 on the partition 8 allows on the one hand to improve the tightness of the partition 8 around the corresponding inlet 6 or outlet 7 openings, and also makes it possible to simplify the mounting of the diaphragms 13 , the partition 8 then being integral with the diaphragms at each of its edges adjacent to the inlet 6 and outlet 7 ports.

According to a preferred feature, the shelf does not have a ground bar 12 and the partition wall 8 has, on one of its flanges adjoining the side rails 11, or on both, a ground braid 14 which can be integrated into the textile of the partition 8, for example by metallic threads sewn or braided with this portion of the partition 8, or by sewing a metal grid on the partition 8.

The partition 8 can also be made of several textile pieces sewn or joined together, which can give a specific shape to the partition 8 which, although being flexible, is then preformed. This allows for example to give a shape to the partition 8 to optimize the flow of air.

The partition wall 8 can be made from any suitable textile. The choice of textile and its thickness will preferably be made taking into account the desired thermal insulation properties to avoid condensation phenomena on the partition 8. The vast majority of textile fibers are favorably insulating.

Figure 4 schematically shows a row of equipment 5 arranged between two shelves 4B, 4C, all seen in section and from the side (with reference to Figure 1). Only the metal carcass of the equipment 5 has been shown to simplify the figure. This equipment 5 is fixed to the two longitudinal members 11 of the shelf 4B below. In this example, the upper part of the shelf 4B does not have a perforated cover and the equipment 5 is directly mounted on the side rails 11, possibly with a “chair” type attachment. Perforations 15 made directly in the carcass of the equipment 5 (or of the possible chair) allow the cold flow to pass through it.

The partition 8 is sandwiched, by its edges, between the equipment 5 and each spar 11. The sectional view of Figure 4 shows that the partition 8 is mounted between the spars 11 so that the cold flow present in the first compartment 9 stretches the textile with respect to the hot flow located in the second compartment 10. The pressure prevailing in the first compartment 9 is in fact greater than the pressure prevailing in the second compartment 10 because the flow cold, which is pulsed, comes from the air conditioning system with a slight pressure while the hot flow is sucked in by the air conditioning system and is therefore in slight depression.

When the cold flow passes through the equipment 5, the air exits through upper perforations 16 of the equipment 5 and then joins the second compartment 10 of the shelf 4C above, through perforations 17.

According to one embodiment, the textile of the partition wall 8 is slightly breathable. The textile or flexible material constituting the partition 8 then has air permeability which, although low, is here functional. Indeed, the slight pressure difference which keeps the partition 8 in tension also makes it possible, in the case of a permeable fabric, to create a slight leak between the compartments 9, 10. FIG. 5 illustrates this characteristic and shows l 'one of the partition walls 8 of Figure 4 enlarged and sectional view. In FIG. 5, the upper pressure on the side of the first compartment 9 and the lower pressure on the side of the second compartment 10 are symbolized by signs + and -. Relative leakage causes a small amount of air to pass between the cold flow and the hot flow. This air leakage is contained by the permeability of the partition 8 (which is altogether low) and creates a film of fresh air 18 surrounding the partition 8 on the side of the second compartment 10. This film 18 forms a thermal barrier s' adding to the efficiency of thermal insulation intrinsic to the material constituting the partition 8.

The breathable nature of the partition 8 is its ability to allow a leak. This leak is a quantity which is measured, at a certain pressure, in m ³ of air per hour and per m ² of partition. The material and the thickness of the partition 8 must be chosen so that the leakage allowed between the compartments 9, 10 is of the order of 0.1 to 0.5%. A leakage of 0.5% means that only 99.5% of the mass of air injected into the lateral inlet upright 2 will be recovered at the outlet of the lateral outlet upright 3. The amount of fresh air passing through the wall towards the zone of hot air remaining weak, the impact on the fluid dimensioning of the cooling system (flow rates, pressure drops, etc.) is minimal or even negligible.

Figures 6 and 7 relate to a second embodiment of the invention. In this second embodiment of the invention, elements similar to the first embodiment of Figure 1 have the same reference numerals.

This second embodiment relates to an avionics bay 1 in which the cooling device is arranged as described in the document FR2872640. According to this arrangement, the cold flow and the hot flow are respectively distributed to the shelves and collected from the shelves by only one of the lateral uprights.

Figure 6 is a side view of an avionics bay 1 according to this second embodiment. This side view shows a lateral upright 19 which forms an air circulation box delimited in two separate compartments: an inlet compartment 2 and an outlet compartment 3. The cold flow circulating in the inlet compartment 2 is distributed. to entry ports 6 and is channeled inside the shelves 4A to 4E to pass through the electrical equipment. The hot flow which comes from this equipment is recovered by the top shelf and is channeled in this shelf to an outlet mouth 7 which communicates with the outlet compartment 3 to then be evacuated.

The lateral upright 19 comprises a partition 8 formed from a flexible veil, as in the first embodiment.

Figure 7 is a top view of the side upright 19 of Figure 6. The domed shape visible in Figure 7 is created by the tensioning of the partition 8 due to the overpressure in the inlet compartment 2 relative to the outlet compartment 3.

This partition 8 can have the same characteristics and options as that of the first embodiment, in particular be made in several pieces so as to have a preform adapted to the channeling of the fluid inside the lateral upright 19, and optional permeability to create an insulating air film.

Other variants can be envisaged without departing from the scope of the invention. For example, the edges of the partition 8 can be reinforced against tearing by sewing a pleat at the periphery. This fold can cooperate with the optional ground braid 14 or the diaphragm 13.

The flexible veil can be woven with anti static electricity conductive wire in order to improve the quality of reception of the equipment by reducing the electrostatic charge of the air flow in the shelf.

The partition 8 can be formed of several pieces sewn, glued or welded together, each of these pieces of flexible material may have different characteristics. For example, only certain zones of the partition 8 can be breathable, while other zones can be metallized to form the ground braid 14.

The partition wall 8 can also be preformed in three dimensions in order to adapt to particular geometries in one piece.

Claims (16)

1. Avionics bay (1) for aircraft, comprising a rack device intended for the integration of equipment (5) and electrical wiring, as well as a device for cooling by circulation of a gas according to an incoming gas flow , called "cold flow", which arrives in the avionics bay (1) to cool it, and an outgoing gas flow, called "hot flow", which is evacuated from the avionics bay (1) after passing through the equipment (5 ), the avionics bay (1) comprising at least one box (4B, 4C, 4D, 19) for gas circulation provided with a partition (8) for separating the cold flow and the hot flow delimiting two compartments (9, 10 ), this avionics bay (1) being characterized in that the partition (8) comprises a flexible veil. 2. Avionics bay according to claim 1, characterized in that the flexible veil of the partition walls (8) is a textile. 3. Avionics bay according to any one of the preceding claims, characterized in that the partition (8) is arranged between two beams (11) of the box. 4. avionics bay according to any one of the preceding claims, characterized in that the box comprises an inlet mouth (6) for the cold flow and an outlet mouth (7) for the hot flow, the partition wall (8) being disposed between the outlet mouth (7) and the inlet mouth (6). 5. Avionics bay according to claim 4, characterized in that it comprises a diaphragm (13) for at least one of the inlet (6) and outlet (7) outlets, the diaphragm (13) being fixed on the partition wall (8). 6. avionics bay according to any one of the preceding claims, characterized in that the partition wall (8) is formed from a single piece of flexible material. 7. Avionics bay according to claim 6, characterized in that the partition wall (8) is formed of a flat piece of material. 8. Avionics bay according to claim 6, characterized in that the partition wall (8) is formed of a piece of material preformed in three dimensions. 9. Avionics bay according to one of claims 1 to 5, characterized in that the partition wall (8) is formed of several parts forming a preform. 10. Avionics bay according to claim 9, characterized in that at least one of said parts has conductive characteristics. 11. Avionics bay according to one of claims 9 or 10, characterized in that at least one of said parts has breathability characteristics. 12. Avionics bay according to any one of the preceding claims, characterized in that the partition has a breathability characteristic so that a leak of the cooling gas is permitted between the two compartments (9, 10) delimited by the partition wall (8). 13. Avionics bay according to claim 12, characterized in that the partition (8) allows a leak between 0.1% and 0.5%. 14. Avionics bay according to any one of the preceding claims, characterized in that the partition comprises a ground braid (14) conductive. 15. Avionics bay according to any one of the preceding claims, characterized in that it comprises a lateral entry upright (2) distributing the cold flow and a lateral exit upright (3) recovering the hot flow, as well as shelves (4B, 4C, 4D) extending between these uprights (2, 3) and forming said at least one gas circulation box. 16. Avionics bay according to any one of the preceding claims, characterized in that it comprises a lateral upright (19) of inlet and outlet distributing the cold flow and recovering the hot flow, the lateral upright (19) forming said at least one box.