Air extraction unit for avionics bay

An air extraction unit taking the form of a body, the geometric shape of which makes it easier to incorporate into an avionics bay of an aircraft. The air extraction unit derives from a multipurpose approach to the operational components of the avionics bay of an aircraft aimed at achieving weight and cost savings. All of the elements of the air extraction circuit are arranged in a compact housing of the body and are protected by the structure thereof. The air extraction unit can be used as a floor of an avionics bay that can be walked on, with a lateral organization.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the French patent application No. 20120062614 filed on Dec. 21, 2012, the entire disclosures of which are incorporated herein by way of reference.

BACKGROUND OF THE INVENTION

The present invention relates to the ventilation of electrical devices in an avionics bay.

The avionics bay of an aircraft, more commonly referred to as an E/E bay, is arranged in a compartment situated under the floor structure of the flight deck, between the nose of the aircraft and the cargo compartment.

Here, most of the aircraft electrical and/or electronic equipment is grouped together in racks. A rack, in the known way, comprises a framework made up of vertical uprights joined together by horizontal transverse shelves, to form a plurality of housings. The electrical and/or electronic equipment of the aircraft is introduced into these housings in the form of functional units. The face of the rack via which the units can be introduced will be referred to in the rest of the description as the open face.

During operation, the electrical equipment in the avionics bay dissipates heat and requires continuous cooling. For this purpose, ventilation circuits based on a principle of blowing and extracting air are installed in the avionics bay. Some elements that make up the ventilation circuits are bulky because they pass round the racks and are complicated to fix in the avionics bay.

FIG. 1illustrates the circuit used for ventilating a set of racks1in an avionics bay of an aircraft. A set of racks is defined as a row of a plurality of racks3positioned side by side. The respective frameworks of each of the racks3are then fixed together, to form a framework that is common to the set of racks1.

The ventilation circuit for a set of racks1comprises two independent circuits: an air blowing circuit C1and an air extraction circuit C2. These two circuits C1, C2are connected to a plurality of air transmission pipes5of the set of racks1. More specifically, each rack3comprises at least one air transmission pipe5which passes through it from top to bottom in order to cover the largest possible surface area for exchange of heat with the electrical/electronic equipment housed in the rack3. Each air transmission pipe5has a first end6situated at the top of the rack, near the top of the avionics bay, and a second end7situated at the bottom of the rack, near the floor for walking on of the avionics bay.

The path followed by the flows of air through the various elements illustrated inFIG. 1is embodied by arrows.

The blowing circuit C1is made up of main inlet trunking K1for blowing cold air (arrow Fa) into each rack3of the set of racks, which trunking is coupled to a plurality of air inlet pipes E1. Each air inlet pipe E1is connected to a first end6of an air transmission pipe5.

The cold air becomes heated up as it passes along an air transmission pipe5. The hot air (arrow Fc), leaving each air transmission pipe5, is discharged by the air extraction circuit C2which comprises a plurality of air extraction pipes E2. Each air extraction pipe E2is connected to a second end7of an air transmission pipe. The air extraction pipes E2are coupled to main hot air extraction trunking K2which, connected to suction means (not depicted in the figure), is able to suck up the hot airflows. The sucked-up hot air is then discharged (arrow Fd) from the aircraft or treated (arrow Fd) on board the aircraft.

InFIG. 1, and for the sake of making the figure less cluttered, the extraction trunking K2is depicted in the bottom part of the avionics bay. In real life, the main trunking K1and K2are generally situated in the upper part of the avionics bay. The air extraction circuit C2therefore occupies a great deal of space because the air extraction pipes E2continue over most of the height (axis z) of the avionics bay.

As a result, the volume occupied by the air extraction circuit C2presents a great many problems in designing aircraft, especially since, in aircraft of more recent design, the size and number of sets of racks is constantly increasing. However, the size of the avionics bay has to be contained given the constraints on the availability of space within an aircraft.

Thus, installing an air extraction circuit C2is a complex and costly matter because it entails the production of a great many components of different types and shapes so as to free up as much space as possible in the avionics bay. Some of these components are delicate and the technicians moving around in the avionics bay have therefore to take a great many precautions when performing maintenance operations in the avionics bay. Further, an air extraction circuit C2comprises multiple complex and heavy systems, such as air suction fans or various valves for example. The weight of these systems means that they have to be fixed to the structure of the aircraft and that additional support elements have therefore to be provided, all of this undermining the very desirable search to find ways of reducing size and bulk in aircraft.

SUMMARY OF THE INVENTION

The invention seeks to overcome the aforementioned constraints by providing an air extraction unit that combines, within a compact volume, a set of functions that were formerly reserved for the air extraction circuits of an avionics bay having a lateral organization.

To this end, the invention proposes an air extraction for an aircraft avionic bay, said unit comprising a body having a housing in which are arranged suction means and discharge means, said suction means being configured to aspirate airflows, hereinafter referred to as suction airflows, from the housing via a plurality of air tappings arranged on the body and to deliver said airflows outside the housing, the delivered airflows being referred to as delivery airflows, via the discharge means which are configured to discharge the delivery airflows from the housing, said air extraction unit comprising a plurality of airflow guide elements arranged in the housing so as to direct the suction airflows toward said suction means and isolate said suction airflows in an airtight manner from the delivery airflows, and the body has a bottom, a lid, these two being substantially parallel to one another, and four side walls adjoining the bottom and the lid, each of the airflow guide elements being resistant to bending and having a first face fixed to an upper face of the bottom, a lower face of the lid being fixed to each of the four side walls and to a second face of each of the airflow guide elements.

Advantageously, the plurality of airflow guide elements is arranged in the housing in such a way as to divide the housing into a chamber, a central zone, a discharge zone and a plurality of ducts which are isolated in an airtight manner from said discharge zone, each duct connecting an air tapping to the central zone in which the plurality of ducts converges, said central zone communicating with the discharge zone via the chamber in which the suction means are situated, said discharge means being situated in the discharge zone.

For preference, the plurality of air tappings is distributed over the four side walls.

Advantageously, the body is of parallelepipedal shape.

For preference, the bottom, the lid and the four side walls and the plurality of airflow guide elements are made of composite. Furthermore, the bottom and the four side walls are preferably produced as a single component obtained by molding.

In one embodiment of the invention, the discharge means comprise at least one valve arranged in an opening made in the bottom and control electronics associated with said at least one valve, the control electronics being configured to control the opening or closing of said at least one valve.

In one embodiment of the invention, the air extraction unit comprises a plurality of fixing means arranged on the body.

The invention also relates to an avionics bay comprising a first and a second set of racks separated by a safety space and each having an open face, the open faces of the first and of the second set of racks facing one another, each one of the first and of the second set of racks comprising a framework, a plurality of air transmission pipes opening into the safety space being distributed along the open face of each of the first and second set of racks, said avionics bay being one which comprises an air extraction unit according to the invention.

For preference, with the air extraction unit being arranged in the safety space, said air extraction unit having its two first side walls parallel to the open faces of the first and second set of racks, each of the plurality of air tappings is connected to one end of each of the plurality of air transmission pipes via a coupling, each of the plurality of fixing means being distributed over the side walls of the air extraction unit that are parallel to the open faces of the first and of the second set of racks and fixed to the framework of the first or second set of racks.

The invention finally relates to an aircraft comprising an air extraction unit as described hereinabove.

Throughout these figures, identical references denote elements that are identical or analogous. The air extraction unit illustrated inFIGS. 2 to 7comprises, by way of nonlimiting example, just six air tappings, in order not to make the figures overly cluttered.

The frame of reference (O, z) is a frame of reference associated with the aircraft when the latter is on the ground. The axis z denotes the vertical or height axis. The terms “upper” or “top”, “lower” or “bottom”, and derivatives thereof are defined with reference to this frame of reference.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the context of the invention, provision is thus made for the avionics bay of an aircraft to be organized with a lateral organization. More specifically, with this organization, two sets of racks are positioned facing one another and separated from one another by a safety space. One set of racks is therefore on one side of the fuselage of the aircraft while the other set of racks is situated on the other side of the fuselage of the aircraft, with respect to the sagittal plane of the fuselage.

Giving the avionics bay a lateral organization allows some of the elements that make up the air circuits of each of the two sets of racks to be common to both. Installing the air extraction circuits in an avionics bay that has a lateral organization is then easier as a result and the weight and space savings are considerable.

In this view of reducing mass and bulk, the invention proposes grouping the air extraction circuit elements for the two sets of racks together into a smaller size air extraction unit that can be prefabricated and be installed quickly in an aircraft. To this end, the air extraction unit according to the invention is intended to be installed in the safety space and has a novel structure that allows it both to incorporate the elements of the extraction circuit of each of the two sets of racks positioned facing one another and also to act as a floor for walking on between the two sets.

With reference toFIG. 2andFIG. 3, the air extraction unit according to the invention takes the form of a body15comprising a housing22in which suction means30and discharge means40are arranged. The suction means30of the air extraction unit are configured to suck up airflows (arrows Fc), hereinafter referred to as suction airflows, from the housing200via a plurality of air tappings23arranged on the body15, and to deliver airflows, referred to as delivery airflows (arrows Fc′), to the discharge means40of the air extraction unit. The discharge means40are configured to discharge the delivery airflows (arrows Fc′) from the housing200. The air extraction unit comprises a plurality of airflow guide elements18arranged in the housing200so as to direct the suction airflows (arrows Fc) toward the suction means30and isolate in an airtight manner the suction airflows (arrows Fc) from the delivery airflows (arrows Fc′).

The body15comprises a lower wall, hereinafter referred to as the bottom16, an upper wall, hereinafter referred to as the lid17(not depicted in the view showing hidden detail inFIGS. 2 and 3) which are substantially parallel to one another, and four side walls19,20,21,22(not depicted inFIG. 2) adjoining the bottom16and the lid17.

The airflow guide elements18are designed and arranged in the housing according to the desired aeraulic configuration for the housing200. What is meant by aeraulic configuration is the distribution of the various airflows in the housing200. Various shapes of airflow guide elements18are thus arranged in the housing200in order to isolate in an airtight fashion the suction airflows (arrows Fc) from the delivery airflows (arrows Fc′) in order to ensure that the air extraction unit operates effectively.

One aeraulic configuration of the cavity will be described in detail in conjunction withFIG. 3. The plurality of airflow guide elements18is arranged in the housing200in such a way as to divide it into a chamber50, a central zone51, a discharge zone52and a plurality of ducts53which are isolated in an airtight manner from the discharge zone52. The ducts53are arranged in the housing200in such a way as to connect the air tappings23to the central zone51in which they converge. The central zone51communicates with the discharge zone52via the chamber50in which the suction means30of the extraction unit according to the invention are situated.

Each of the air tappings23, via which the housing200communicates with a space outside the body, is intended to be connected to the second end of an air transmission pipe running through a rack.

The plurality of six air tappings23is preferably distributed over the side walls19,20,21,22so as to keep the upper face of the lid17free. This arrangement makes it easier for operators to move around on the lid17when the air extraction unit according to the invention is mounted in an avionics bay of an aircraft.

The suction means30comprise at least two fans and control electronics associated with these fans. The fan control electronics allow control over the rotational speed of the rotor of each fan on which blades are mounted.

The fan control electronics are an electronic device of the microcontroller type combining the essential elements of a computer: processor, memories and input/output interfaces.

The discharge means40comprise at least one valve arranged on the body15, preferably on the bottom16. The housing200communicates with a space outside the body15via the valve arranged on the body15when this valve is open. The discharge means40also comprise the valve control electronics for controlling the opening or closing of the valves. The valve control electronics are also an electronic device of the microcontroller type.

The invention will be detailed more specifically with the description of one embodiment of the air extraction unit, described in conjunction withFIGS. 3 to 6.

According to this embodiment, the body15and the housing200are of parallelepipedal shape. The side walls19,20,21,22are perpendicular in pairs and in the remainder of the description the two side walls19,20that have the largest surface area will be referred to as first side walls. The other two side walls21,22are referred to as second side walls.

The plurality of six air tappings23is preferably distributed over the two first side walls19,20with equal distribution on each of the two first side walls.

Advantageously, the air tappings23arranged on one of the first side walls19are arranged facing the air tappings23arranged on the other of the first side walls20. This arrangement, through symmetry, simplifies the aeraulic configuration of the air extraction unit according to the invention.

The bottom16and the four side walls19,20,21,22are produced as a single component, referred to as a shell, which is obtained by molding. The use of a single component to make the bottom16and the four side walls19,20,21,22allows the structural strength of the body15to be improved. This body is made up by fixing the lid17to the shell as well as the airflow guide elements18. For this purpose, the lower face of the lid17is fixed, for example by bonding, to each of the side walls19,20,21,22.

The structure of the body is made of composite. More specifically, the shell is made of a monolithic composite and the lid17is made of composite with a structure of the sandwich construction. The airflow guide elements18are likewise made of composite, with a thin (of the order of 4 mm) sandwich structure.

The way in which the airflow guide elements18are installed is as follows: they are first of all fixed, for example by bonding, to the bottom16. The airflow guide elements18thus have a first face fixed to the upper face of the bottom16. A second face of each airflow guide element18is coated with adhesive, to be fixed to the lower face of the lid17when the latter is placed in contact with the side walls19,20,21,22for bonding it.

In order to ensure that the airflow guide elements18can be fitted accurately and quickly, these elements are equipped with indexing pegs distributed over their faces that are intended respectively to be fixed to the lower face of the lid17and to the upper face of the bottom16. The indexing pegs are positioned in correspondence with drillings made in the lower face of the lid17and the upper face of the bottom16. The drillings are situated at determined locations on the lower face of the lid17and on the upper face of the bottom16, according to the desired aeraulic configuration for the air extraction unit.

The airflow guide elements18are designed to be resistant to bending. Thus, they play a structural role because they keep the lid16and the bottom17a given distance apart and are thus able to absorb the tensile or compressive loadings to which the body15may be subjected.

Those faces of the airflow guide elements18that are in contact with the side walls19,20,21,22are themselves bonded thereto, thus giving the airflow guide elements18their functional role. Specifically, attaching the airflow guide elements18to the side walls19,20,21,22, to the upper wall of the bottom16and to the lower wall of the lid17makes it possible to determine within the housing200, the aeraulic configuration of the extraction circuit.

The way in which the suction means30(not depicted inFIG. 5) are installed in the air extraction unit according to the preferred embodiment of the invention will be described in conjunction withFIGS. 2, 4 and 5, while the installation of the discharge means40will be described in conjunction withFIG. 6.

The suction means30are designed to be incorporated directly into the chamber50without additional components, to make fitting and maintenance operations easier.

To this end, the suction means30are incorporated into a unit31comprising an air inlet131and an air outlet133for each of the fans. The fan air inlets131are arranged on one and the same lateral face135of the unit31and open onto the central zone51when the unit31is installed in the chamber50. The fan air outlets133are also arranged on one and the same lateral face137of the unit31, opposite the face on which the air inlets are arranged, and open onto the discharge zone52when the unit is installed in the chamber50. The connection between the fan inlets131and the central zone51is achieved by means of flexible couplings32. The connection between the fan outlets133and the discharge zone52is likewise achieved using flexible couplings33.

The unit31comprises on its lower face, which is intended to be in contact with the upper face of the bottom16, a plurality of drillings arranged in a particular pattern. Indexing pegs are arranged on the upper face of the bottom16, at the location designed for accepting the unit31. These indexing pegs are intended to be inserted into the drillings made in the unit31and are therefore arranged in a pattern that corresponds to the pattern of the drillings of the unit. Fitting the unit31into the housing200therefore requires no complex positioning step and the risks of incorrect handling are therefore set aside. Fan maintenance operations can therefore be performed quickly and in complete safety, notably operations of cleaning the fan blades.

Fixing means known to those skilled in the art are provided for securing the unit31to the housing200(not depicted inFIGS. 4 and 5).

An access opening is arranged on the lid17so that the suction means30can be extracted or introduced without the need to remove the lid17from the shell. The access opening is arranged on the lid17in such a way that the chamber50is in line with the access opening when the lid17is fixed to the base.

A soundproofing box34covers the access opening and soundproofs the fans. The box34is fixed to the upper face of the lid17via quick-fit/disconnect means, such as fixings of the wing nut/bolt or spring clip type.

In the preferred embodiment of the invention, the discharge means comprise two valves, a main valve41and an overload valve42.

The main valve41is installed in an opening arranged on the bottom16, while the overload valve42is installed in an opening arranged on one of the two first side walls19,20.

The control electronics that control the valves41,42are connected to the fan control electronics in order to synchronize the opening/closing of the valves41,42to the rotational speed of the fans. The valves41,42are configured, when open, to discharge the delivery airflows (arrows Fc′) to outside the housing200.

In conjunction withFIGS. 2 and 3, the way in which the air extraction unit according to the invention works is as follows: a flow (arrow Fc) of hot air from a rack is sucked up from the housing200under the action of the suction means30. The suction airflows (arrows Fc) then pass through the air tappings23to the central zone51via the ducts53. The suction airflows (arrows Fc) arriving in the central zone51are then delivered (arrow Fc′) by the suction means30to the discharge zone52, where the discharge means40are situated.

The way in which the extraction unit according to the invention is incorporated into an avionics bay with a lateral organization will now be described in conjunction withFIGS. 7 and 8. The description that is to follow relates to the extraction unit according to the preferred embodiment of the invention, although it remains valid for other embodiments.

InFIG. 8, the avionics bay100is located, by way of example, under the floor120of the flight deck.

The avionics bay100comprises two sets of racks1,2(the set of racks1is depicted to show hidden detail inFIG. 7) placed facing one another. A set of racks1,2is defined as a row of a plurality of racks3placed side by side. The respective frameworks of each of the racks3are then fixed to one another to form a framework in common for the set of racks1.

The avionics bay100comprises an air blowing circuit. The air blowing circuit C1is connected to a plurality of air transmission pipes of the set of racks1,2. More specifically, each rack3of the set of racks1,2comprises at least one air transmission pipe which passes through it from top to bottom so as to cover a surface area that is as large as possible for exchanging of heat with the electrical/electronic equipment housed in the rack3. Each air transmission pipe has a first end situated at the top of the rack, at the upper part of the avionics bay, and a second end situated at the bottom of the rack, near the floor for walking on of the avionic bay.

The blowing circuit is made up of main inlet trunking for blowing cold air into each rack3of the set of racks1,2, which trunking is coupled to a plurality of air inlet pipes. Each air inlet pipe is connected to a first end of an air transmission pipe5.

The racks3of a set of racks1,2are all oriented in the same way so as to define an open face for the set of racks and each of the sets of racks has its open face facing the open face of the other set of racks. The open face of a set of racks is that face of the set of racks via which the units can be introduced into the racks that make up the set of racks1,2. Thus, the second end7of the air transmission pipes5of each of the racks3of the two sets of racks1,2opens into the safety space.

The air extraction unit according to the invention is then arranged in the safety space in such a way that each of its first side walls19,20is arranged parallel to the open face of each of the sets of racks1,2and that the upper face of the lid17is the upper face of the air extraction unit.

Advantageously, the air extraction unit then acts as a floor for walking on of the avionics bay100. Specifically, the air extraction unit is installed in the lower part of the avionics bay, with its air tappings23situated near the second ends7of the air transmission pipes of the racks3. The solid construction of the air extraction unit made of composite makes it capable of bearing the weight of the operators who may work in the safety space moving around on the upper face of the lid17.

The upper face of the lid17is then preferably covered with an attack-resistant coating in order to protect its composite structure from the repeated passage of operators.

In a first alternative form of embodiment, the air extraction unit according to the invention is fixed to the structure of the aircraft110via structural supports known to those skilled in the art and which will not be detailed.

For preference, and according to a second alternative form of embodiment, the air extraction unit is held directly in the environment of the avionics bay100in a fixture of the suspended type. Mounting the air extraction unit in a suspended manner frees up a volume115that had previously been fixed with air extraction circuit elements according to the prior art. The volume115is situated between the skin111of the aircraft110and the lower face of the bottom16. The volume115can be used to house certain elements of the avionics bay100, such as part of the air conditioning system for example.

To mount the air extraction unit in a suspended manner, fixing means29are arranged on the body. The fixing means29are, for example, mechanical components of the fitting or bracket type or any other mechanical component of known type that allows one element to be fixed to another.

For preference, the fixing means29are arranged on each of the two first side walls19,20of the body. The air extraction unit is then fixed, via the fixing means29, to the framework of each of the sets of racks1,2of the avionics unit100. More specifically, each fixing means29is fixed, for example by screwing, to the upright of one of the racks3. The upright to which the fixing means29is fixed is the one situated on the open face of the set of racks1,2which faces the first side wall19,20.

The possibility of mounting the air extraction unit according to the invention on the framework of the sets of racks1,2means that it can be secured and connected to the avionics bay in a non-critical mounting zone. More specifically, the air extraction unit can be mounted securely in the avionics bay100and connected (this then means electrical and aeraulic connection) thereto outside of the aircraft110, i.e. outside of the critical mounting zone. The avionics bay, in the form of a pallet or of a container, can then be installed in the airplane via the cargo compartment thereof for example. That makes it possible to limit the length of time for which operators are present in the avionics bay100, given that a large proportion of the securing and electrical connection operations would have already been carried out outside of the aircraft110.

The suction means40and the discharge means41are connected to the electrical network of the avionics bay via a wiring system internal to the air extraction unit according to the invention.

Aeraulic connection means the connection of the air tappings23of the air extraction unit to the second ends7of the air transmission pipes of the racks3of the avionics bay100. This connection is performed using couplings9. Each coupling9connects an air tapping23of the air extraction unit to a second end7of an air transmission pipe5of a rack3.

When the avionics bay comprising the air extraction unit according to the invention is installed in the aircraft, the main valve41arranged on the bottom16of the air extraction unit is connected to an external ejection valve45of the aircraft A, via a coupling. The external ejection valve45is used for ejecting airflows from the aircraft110and is generally installed in an opening arranged in the skin111of the aircraft110, in the lower part thereof.

In order to save installation time and for preference, a single valve, referred to as the fuselage vent, may replace the main valve41and the external ejection valve45. In such case, when the air extraction unit is being assembled in the aircraft, the fuselage vent is connected to the air extraction unit via a coupling. When the air extraction unit is offered up into the aircraft, the fuselage vent is then fixed to the fuselage via screws at the periphery of an opening arranged in the skin111of the aircraft110, in the lower part thereof Screwing is done from outside the airplane.

The rotational speed of the rotors of the fans of the suction means30and the opening/closing of the valves41,42is dependent on a signal sent by a control device that monitors the cooling of the racks3. This cooling control device comprises temperature and pressure sensors installed in each of the racks3of the avionics bay100. The device that controls the cooing of the racks3commands the opening or closing of the valves41,42and controls the fan control electronics to increase or decrease suction and thus control the cooling of the racks according to the temperature and pressures detected in the racks.

To make the task of the operators easier, the soundproofing box34is preferably provided so that it forms a bump that an operator can sit on. Specifically, the low height of the avionics bay100in an aircraft110does not allow an operator to stand upright and the bump therefore makes fitting or maintenance operations easier.

The parallelepipedal shape of the air extraction unit according to the invention allows the latter to be designed quickly and uncomplicatedly. By way of example, an air extraction unit according to the invention, having six air tappings23distributed equally between the two first side walls19,20, comprises fewer than ten or so airflow guide elements18.

The upper face of the lid17is preferably flat. However, its shape may be adapted for the purposes of incorporating it into an avionics bay. As depicted by way of illustration inFIGS. 5 and 7, the lid17has an inclined part60extending upwards so as to suit the configuration of the avionics bay100.

Mounting, inspecting or repairing the elements incorporated in the housing200(which is not depicted inFIGS. 7 and 8) are made easier by the installation of inspection hatches arranged on the bottom16or the lid17. When open, each inspection hatch has an opening providing access to the housing200. The inspection hatches are fitted with seals in order to seal the housing200when they are closed.

For preference, an inspection hatch is provided in the bottom16, opposite an inspection hatch arranged on the lid17or facing the access opening provided for accessing the fans. This arrangement allows rapid access to the volume115situated between the bottom16and the skin111of the aircraft110. This arrangement for example allows rapid access to the volume115in which electrical systems of the aircraft (ground power connector of the aircraft110and electrical connection of power cables) are installed.

All of the elements that perform functions previously reserved for a great many bulky and expensive systems of the air extraction circuit of an aircraft bay, and which are arranged in the housing200, are protected by the compact structure of the body15.