FR3150928A1 - Housing and method for protecting an electronic device housed in the housing in the presence of liquid on the housing - Google Patents

Abstract

A housing (2) configured to house electronic devices (9) and comprising an upper wall (3) and a lower wall (4) respectively comprising discharge ports (30) and intake ports (40) for an air flow in the housing (2), the housing (2) comprising an internal protective duct (10) internally delimiting an exposed volume and externally a protected volume, in which the electronic devices (9) extend and at least one of the intake ports (40) opens, the internal protective duct (10) comprising: - an upper end, into which the discharge ports (30) of the upper wall (3) open, and a lower end (8), opening into a receptacle, so as to confine a liquid infiltrated by the discharge ports (30) in the exposed volume; and – ventilation openings (13) configured to allow the circulation of air flow from the protected volume to the exposed volume. Abstract Figure: Figure 1

Description

Housing and method for protecting an electronic device housed in the housing in the presence of liquid on the housing

The present invention relates to the field of protection of electronic devices housed in a housing, in particular on board an aircraft, in the presence of pollution such as a liquid on the housing.

As is known, an aircraft computer comprises a set of electronic devices, in particular electronic cards comprising a printed circuit with electronic components, which are housed in one or more housings, themselves housed in a bay also known as a “rack”. A housing comprises an upper wall and a lower wall connected by side walls. The upper wall and the lower wall of the housing comprise guide rails for installing and uninstalling the electronic devices via a front opening. The electronic devices installed in the housing extend vertically between the lower wall and the upper wall and are plugged into connectors at a rear wall. A vertical segregation wall may extend between two electronic devices to limit propagation in the event of a fire and prevent a defect or damage to one of the electronic devices from impacting the other.

In practice, the components of electronic devices release heat during their operation, which is detrimental to the performance of the computer. It is thus known to cool electronic devices by circulating a vertical air flow admitted and discharged via orifices formed respectively in the lower wall and in the upper wall of the housing. The orifices are distributed over the entire surface of the lower and upper walls so as to comply with the ARINC 600 aeronautical standard which defines in particular an acceptable range of pressure losses for the air flow circulating in the housing as well as a minimum operating time in the event of failure of the air flow supply system.

In practice, the housing is also subject to the requirements of the aeronautical document RCTA DO-160 section 10, whose category Y requires protection from the risk of short-circuiting electronic devices when they are subjected to water condensation. It is thus known to coat electronic devices with a protective varnish, known to those skilled in the art as a "tropicalization varnish", to limit the risk of an electrical malfunction occurring in the aircraft computer, such as a short circuit. However, such a solution is insufficient for the new regulations now requiring category R, namely protection in the event of water falling on the housing. Indeed, the holes on the upper wall of the housing allow water to run down onto the electronic devices, the protective varnish of which is not sufficient to guarantee protection.

It is known from application FR3038992A1 to provide a hermetic enclosure for each electronic device in which a radiator and a fan are mounted. Such a solution has the disadvantage of being bulky and requiring a power supply for the fans, which is undesirable.

The invention thus aims to protect electronic devices housed in a housing in the event of the presence of liquid on the housing, by limiting the impact on cooling and the size of the housing.

PRESENTATION OF THE INVENTION

A housing configured to house a plurality of electronic devices is provided, the housing comprising a top wall and a bottom wall connected by side walls, the bottom wall comprising a plurality of ports for admitting an airflow into the housing, the top wall comprising a plurality of ports for discharging the airflow out of the housing.

• une extrémité supérieure, dans laquelle débouchent les orifices de refoulement de la paroi supérieure, et une extrémité inférieure, débouchant dans un réceptacle, de manière à confiner un liquide infiltré par les orifices de refoulement dans le volume exposé, et
• une pluralité d’orifices de ventilation configurés pour permettre la circulation du flux d’air depuis le volume protégé vers le volume exposé.

The invention is remarkable in that the housing comprises at least one internal protective conduit delimiting internally an exposed volume and externally a protected volume, in which the electronic devices extend and at least one of the intake orifices opens, the internal protective conduit comprising:

• an upper end, into which the discharge orifices of the upper wall open, and a lower end, opening into a receptacle, so as to confine a liquid infiltrated by the discharge orifices in the exposed volume, and
• a plurality of ventilation ports configured to allow airflow from the protected volume to the exposed volume.

Thanks to the invention, in the event of liquid falling or dripping onto the upper wall of the housing, the electronic devices housed in the housing are advantageously protected, in particular from the risk of short circuit. Indeed, the internal protective conduit and the arrangement of the discharge ports make it possible to define a protected volume in the housing, so as not to expose the electronic devices housed therein. The housing according to the invention also makes it possible to ensure effective cooling of the electronic devices by air circulation from the intake ports to the discharge ports, via the ventilation ports.

According to one aspect of the invention, the internal protective conduit comprises at least one deflection element positioned vertically above at least one ventilation orifice and extending projecting into the exposed volume, the deflection element preferably being positioned vertically above all the ventilation orifices. This further improves the protection of the electronic devices located in the protected volume, by avoiding possible projections of liquid via the ventilation orifices. The deflection elements advantageously make it possible to deflect the liquid away from the ventilation orifices. The deflection elements also allow easy circulation of the cooling air flow.

According to a preferred aspect of the invention, the deflection element of the internal protection conduit comprises a blade oriented towards the receptacle and forming an angle with respect to a vertical axis of less than 90°. This makes it possible to guide the liquid towards the receptacle by gravity. The liquid is advantageously deflected out of the ventilation orifices. The deflection elements also allow easy circulation of the cooling air flow.

According to one aspect of the invention, the internal protective conduit comprises a plurality of deflection elements, each deflection element extending from an upper edge of an associated ventilation orifice. Each deflection element thus prevents the projection of liquid into the ventilation orifice that it protects. The protection of electronic devices against the risk of liquid dripping is further improved.

According to one aspect of the invention, the deflection element is made from the material of the internal protection duct, preferably from the material pierced and stamped to form a ventilation orifice. The internal protection duct is thus advantageously simple, quick and inexpensive to manufacture.

According to one aspect of the invention, the ventilation holes are spaced from the upper end by a maximum distance less than half of a total height of the housing. This forces a bottom-to-top circulation of the cooling air flow over the entire surface of the electronic devices, for uniform and efficient cooling.

According to one aspect of the invention, the receptacle is formed by a portion of the bottom wall. This facilitates the design of the housing.

According to one aspect of the invention, the receptacle comprises at least one liquid discharge orifice. This allows the liquid to be discharged from the housing.

According to one aspect of the invention, the internal protective conduit is formed by a first and a second partition mounted on the lower wall and on the upper wall. This facilitates the design of the housing.

The invention also relates to an assembly of a housing as described above and a plurality of electronic devices housed in the housing including at least one main electronic device and one auxiliary electronic device, the internal protection conduit being positioned in the housing so as to divide the protected volume into a first sub-volume, in which the main electronic device extends, and a second sub-volume, in which the auxiliary electronic device extends.

• le flux d’air circule dans le boîtier depuis les orifices d’admission vers les orifices de refoulement via les orifices de ventilation, et
• lorsque du liquide pénètre dans le boîtier via les orifices de refoulement, le conduit interne de protection confine le liquide dans le volume exposé, de manière à protéger le dispositif électronique dans le volume protégé.

The invention also relates to a method of protecting at least one electronic device housed in a housing as described above, in which:

• airflow circulates in the housing from the intake ports to the discharge ports via the ventilation ports, and
• When liquid enters the housing through the discharge ports, the internal protective conduit confines the liquid within the exposed volume, thereby protecting the electronic device within the protected volume.

PRESENTATION OF FIGURES

The invention will be better understood upon reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

There is a schematic perspective representation from the front of a housing according to an embodiment of the invention in which electronic devices are housed.

There is a schematic representation in vertical section of the housing of the without electronic devices.

There is a schematic top view representation of the housing of the .

There is a schematic perspective representation of the inner surface of the internal protective conduit of the housing of the .

There is a schematic perspective representation of the exterior surface of the internal protective conduit of the housing of the .

There is a schematic representation of the circulation of a ventilation air flow in the housing of the .

There is a schematic representation of water runoff entering the housing of the via the discharge ports.

It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate.

DETAILED DESCRIPTION OF THE INVENTION

In reference to the , the invention relates to a housing 2 configured to house electronic devices 9, such as electronic cards comprising a printed circuit with electronic components. The electronic cards are for example communication cards and power cards, operating in particular in pairs. The housing 2 is conventionally housed in a bay, also known as a "rack". The housing 2 extends along a vertical axis Y oriented from bottom to top (see ) and comprises an upper wall 3 and a lower wall 4 connected by side walls 6. The upper wall 3 and the lower wall 4 of the housing 2 conventionally comprise guide rails 31, 41 for installing and uninstalling the electronic devices 9 through a front opening O. The electronic devices 9 installed in the housing 2 extend vertically between the lower wall 4 and the upper wall 3 and are, in this example, plugged into connectors 50 mounted on an electronic card 5 at a rear face of the housing 2. The electronic card 5 is known to those skilled in the art under the term “backplane card”.

As illustrated in FIGS. 1 and 2, the housing 2 comprises intake ports 40 for an air flow formed in the lower wall 4 and discharge ports 30 for the air flow formed in the upper wall 3. The air flow is conventionally supplied by an external conduit opening at the lower wall 4 of the housing 2. The circulation of the air flow in the housing 2 from the intake ports 40 to the discharge ports 30 makes it possible to cool by thermal convection the electronic devices 9 which give off heat during their operation. The discharge ports 30 make it possible to evacuate the air flow from the housing 2.

• une extrémité supérieure 7, dans laquelle débouchent les orifices de refoulement 30 de la paroi supérieure 3, et une extrémité inférieure 8, débouchant dans un réceptacle 42, de manière à confiner un liquide infiltré par les orifices de refoulement 30 dans le volume exposé V1, et
• des orifices de ventilation 13 configurés pour permettre la circulation du flux d’air depuis le volume protégé V2 vers le volume exposé V1.

According to the invention and still with reference to figures 1 and 2, the housing 2 also comprises an internal protection conduit 10 internally delimiting an exposed volume V1 and externally a protected volume V2, in which the electronic devices 9 extend and at least one of the intake orifices 40 opens. Still according to the invention, the internal protection conduit 10 comprises:

• an upper end 7, into which the discharge orifices 30 of the upper wall 3 open, and a lower end 8, opening into a receptacle 42, so as to confine a liquid infiltrated by the discharge orifices 30 in the exposed volume V1, and
• ventilation holes 13 configured to allow the circulation of air flow from the protected volume V2 to the exposed volume V1.

The internal protective conduit 10 and the arrangement of the discharge orifices 30 of the housing 2 according to the invention advantageously make it possible to protect the electronic devices 9 installed in the housing 2 in the event of a fall or runoff of liquid, in particular water, in particular on the upper wall 3. Indeed, the liquid present on the upper wall 3 penetrates into the discharge orifices 30 which all open into the internal protective conduit 10. This makes it possible to confine the liquid infiltrated in the exposed volume V1 ( ) and to protect the electronic devices 9 located in the protected volume V2 ( ).

According to a preferred aspect illustrated on the , one or more deflection elements 14 project from an internal surface Sint of the internal protective conduit 10, so as to deflect the liquid away from the ventilation holes 13. This prevents the liquid from entering the ventilation holes 13 and reaching the protected volume V2. Such a housing 2 thus complies with the requirements of category R of the aeronautical document RCTA DO-160 section 10 regarding the protection of the electronic devices 9 in the event of falling water, in particular a risk of short circuit. The electronic devices 9 may additionally be covered with a protective varnish, known to those skilled in the art as a “tropicalization varnish” to be protected in the event of water condensation on the housing 2, for example from humidity or salt spray.

Thanks to the ventilation holes 13, the housing 2 according to the invention also has the advantage of ensuring effective cooling of the electronic devices 9, so as to comply with the aeronautical standard ARINC 600 which defines in particular an acceptable range of pressure losses for the air flow circulating in the housing as well as a minimum operating time in the event of failure of the air flow supply system.

The housing 2 is advantageously adapted to be housed in a bay on board the hold of an aircraft and to house the electronic devices 9 of an aircraft computer 1. It goes without saying, however, that the housing 2 is also suitable for ground applications.

Referring to Figures 1 and 2, the internal protective conduit 10 extends into the housing 2 and is fixed at its upper end 7 to the upper wall 3. As illustrated in the , all the discharge orifices 30 are formed in a portion 32 of the upper wall 3, so as to open into the internal protection duct 10. No discharge orifice 30 thus opens into the protected volume V2. The portion 32 preferably extends over 10% to 30% of the upper wall 3. The discharge orifices 30 preferably extend over at least 50% of the depth defined from front to back of the upper wall 3. This makes it possible to limit the size of the internal protection duct 10 in the housing 2.

According to a preferred aspect illustrated in FIGS. 1 and 2, the internal protective conduit 10 is fixed at its lower end 8 to the lower wall 4. The receptacle 42 is thus formed by a portion of the lower wall 4 onto which the lower end 8 of the internal protective conduit 10 opens. Preferably, the receptacle 42 comprises one or more discharge orifices 43, in this example formed in the lower wall 4, which are configured to discharge the liquid out of the housing 2. Such discharge orifices 43 are in themselves adapted to admit the air flow into the housing 2, as are the inlet orifices 40. In the example of the , the intake ports 40 all open into the protected volume V2 while the exhaust ports 43 open into the exposed volume V1.

In this example, the internal protective conduit 10 is formed by a first and a second partition 11, 12 extending vertically along the vertical axis Y in the housing 2, the inner surface Sint of which is turned towards the exposed volume V1 and the outer surface Sext of which is turned towards the protected volume V2. The partitions 11, 12 have curved ends 16, 17 fixed to the upper wall 3 and to the lower wall 4, for example by bolts or rivets or by welding. As illustrated in the , the partitions 11, 12 are preferably integral with the electronic card 5 at the rear face of the housing 2 to close the exposed volume V1. The partitions 11, 12 are preferably integral at a front end 18, so that the exposed volume V1 is closed at the front opening O.

According to a preferred aspect illustrated in FIGS. 1 and 6, the internal protection conduit 10 also has a segregation function between a first sub-volume V2A and a second sub-volume V2B of the protected volume V2 extending respectively on either side of the internal protection conduit 10. This makes it possible to limit the spread of a fire between the two sub-volumes V2A, V2B. Electronic devices 9A, 9B with the same function are preferably mounted in the two sub-volumes V2A, V2B for redundancy purposes. In the event of a fire or any malfunction in the first sub-volume V2A where a main electronic device 9A extends, an auxiliary electronic device 9B in the second sub-volume 9B can advantageously continue the functions of the main electronic device 9A.

Referring to Figures 2 and 6, as previously described, ventilation holes 13 are formed in the internal protective duct 10, in this example in the partitions 11, 12, in order to allow the circulation of the air flow F from the protected volume V2 to the exposed volume V1. In this example, the ventilation holes 13 form transverse rows relative to the vertical axis Y (see ). Still in this example, the ventilation orifices 13 of the partitions 11, 12 extend opposite for uniform circulation of the air flow F in the sub-volumes V2A, V2B (see ).

With reference to Figures 2, 6 and 7, the ventilation orifices 13 are preferably protected from liquid E splashes by one or more deflection elements 14 extending in projection from the internal surface Sint of the internal protection conduit 10 into the exposed volume V1. Each deflection element 14 comprises a blade oriented towards the receptacle 42 forming an angle α relative to the vertical axis Y of less than 90°, and preferably greater than 20° (see ). The deflection elements 14 advantageously allow the air flow F to circulate in the ventilation orifices 13 ( ) but not the liquid E, which is guided towards the receptacle 42 by gravity.

According to a preferred aspect illustrated in Figures 2, 4 and 5, a deflection element 14 is associated with each ventilation opening 13 and extends from the upper edge 15 of the associated ventilation opening 13. The deflection element 14 thus forms a protective hood or visor above the associated ventilation opening 13, for optimum protection.

According to a preferred aspect illustrated in Figures 2, 4 and 5, the ventilation holes 13 and the associated deflection elements 14 are obtained by drilling and stamping the internal protection duct 10 in a simple and practical manner. The method consists in drilling the internal protection duct 10 so as to form a lower edge 15' of the ventilation hole 13, then stamping an area above the lower edge 15' from the external surface Sext towards the internal surface Sint. The stamped area forms the deflection element 14 while the hole formed corresponds to the associated ventilation hole 13. Preferably, as illustrated in , the ventilation orifice 13 has a transverse width L greater than its vertical height H13 to facilitate stamping. The shape of the ventilation orifices 13 is arbitrary as long as the air circulation is sufficient.

Alternatively, the deflection elements 14 could be mounted in a reported manner on the internal surface Sint of the internal protection duct 10. Preferably, each deflection element 14 extends over a height H14 at least equal to 50% of the height H13 of the associated ventilation orifice 13. Furthermore, a deflection element 14 could be common to several ventilation orifices 13. Furthermore, only the upper row of ventilation orifices 13 could be protected by deflection elements 14.

Preferably, the ventilation holes 13 have a surface area of between 30mm² and 60mm² and the internal protective duct 10 comprises between 60 and 100 ventilation holes 13. This helps to comply with the aeronautical standard ARINC600. According to a preferred aspect, the ventilation holes 13 extend over at least 50% of the defined depth from front to rear of the internal protective duct, preferably at least 75% of the depth as illustrated in the . This ensures uniform cooling of electronic devices 9.

According to another preferred aspect illustrated on the , the ventilation holes 13 are spaced from the upper end 7 by a maximum distance Hinf less than 50% of the total height H2 of the housing 2. Concentrating the ventilation holes 13 in an upper half ensures the circulation of the air flow F ( ) from bottom to top in the protected volume V2 before joining the exposed volume V1. The minimum distance Hsup separating the ventilation orifices 13 from the upper end 7 is preferably greater than 10% of the total height H2 of the housing 2. This prevents liquid E from being splashed into the ventilation orifices 13 of the upper row.

• le flux d’air F circule dans le boîtier 2 depuis les orifices d’admission 40 vers les orifices de refoulement 30 via les orifices de ventilation 13 (voir ), et
• lorsque du liquide E pénètre dans le boîtier 2 via les orifices de refoulement 30, le conduit interne de protection 10 confine le liquide E dans le volume exposé V1, de manière à protéger les dispositifs électroniques 9A, 9B dans le volume protégé V2 (voir ).

With reference to figures 6 and 7, a method of protecting the electronic devices 9A, 9B installed in the housing 2 consists of:

• the air flow F circulates in the housing 2 from the intake ports 40 to the discharge ports 30 via the ventilation ports 13 (see ), And
• when liquid E enters the housing 2 via the discharge ports 30, the internal protection conduit 10 confines the liquid E in the exposed volume V1, so as to protect the electronic devices 9A, 9B in the protected volume V2 (see ).

The protection method advantageously does not require any control or electrical or mechanical power supply to be implemented. In normal operation, i.e. in the absence of liquid drop E, as illustrated in the , the air flow F enters the housing 2 via the intake ports 40, circulates from bottom to top in the protected volume V2 in contact with the electronic devices 9A, 9B, then is admitted into the exposed volume V1 via the ventilation ports 13 before being evacuated to the outside via the discharge ports 30. This ensures effective cooling of the electronic devices 9A, 9B.

In the presence of liquid E on the upper wall 3, the liquid E enters the housing 2 only via the discharge ports 30 which open into the exposed volume V1. The internal protection conduit 10 leads the liquid E to the receptacle 42 by gravity, the liquid E preferably being evacuated from the housing 2 via the discharge ports 43. Preferably, the deflection elements 14 make it possible to deflect the liquid E to prevent it from entering the ventilation ports 13. The architecture of the housing 2 and in particular of the internal protection conduit 10 is thus both suitable for cooling the electronic devices 9A, 9B and for protecting them in the presence of water on the housing 2.

Of course, the various features, variants and/or embodiments of the present invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

Furthermore, the invention is not limited to the embodiments described above and provided solely as examples. It encompasses various modifications, alternative forms and other variations that may be envisaged by those skilled in the art within the scope of the present invention and in particular any combinations of the different modes of operation described above, which may be taken separately or in combination.

Claims (10)

Housing (2) configured to house a plurality of electronic devices (9), the housing (2) comprising an upper wall (3) and a lower wall (4) connected by side walls (6), the lower wall (4) comprising a plurality of intake ports (40) for an air flow (F) into the housing (2), the upper wall (3) comprising a plurality of discharge ports (30) for the air flow (F) out of the housing (2), the housing (2) being characterized in that'it comprises at least one internal protection conduit (10) internally delimiting an exposed volume (V1) and externally a protected volume (V2), in which the electronic devices (9) extend and at least one of the intake orifices (40) opens, the internal protection conduit (10) comprising:

• an upper end (7), into which the discharge orifices (30) of the upper wall (3) open, and a lower end (8), opening into a receptacle (42), so as to confine a liquid (E) infiltrated by the discharge orifices (30) into the exposed volume (V1), and
• a plurality of ventilation ports (13) configured to allow the circulation of the air flow (F) from the protected volume (V2) to the exposed volume (V1).

Housing (2) according to claim 1, wherein the internal protective duct (10) comprises at least one deflection element (14) positioned vertically above at least one ventilation orifice (13) and extending projecting into the exposed volume (V1), the deflection element (14) preferably being positioned vertically above all the ventilation orifices (13). Housing (2) according to one of claims 1 and 2, in which the internal protective duct (10) comprises a plurality of deflection elements (14), each deflection element (14) extending from an upper edge (15) of an associated ventilation orifice (13) projecting into the exposed volume (V1). Housing (2) according to one of claims 2 and 3, in which the deflection element (14) is made from the material of the internal protection conduit (10), preferably from the material pierced and stamped to form a ventilation orifice (13). Housing (2) according to one of claims 1 to 4, in which the ventilation openings (13) are spaced from the upper end (7) by a maximum distance (Hinf) less than half of a total height (H2) of the housing (2). Housing (2) according to one of claims 1 to 5, in which the receptacle (42) is formed by a portion of the lower wall (4). Housing (2) according to one of claims 1 to 6, in which the receptacle (42) comprises at least one evacuation orifice (43) for the liquid (E). Housing (2) according to one of claims 1 to 7, in which the internal protection conduit (10) is formed by a first and a second partition (11, 12) mounted on the lower wall (4) and on the upper wall (3). Assembly of a housing (2) according to one of claims 1 to 8 and of a plurality of electronic devices (9) housed in the housing (2) including at least one main electronic device (9A) and one auxiliary electronic device (9B), the internal protection conduit (10) being positioned in the housing (2) so as to divide the protected volume (V2) into a first sub-volume (V2A), in which the main electronic device (9A) extends, and a second sub-volume (V2B), in which the auxiliary electronic device (9B) extends. Method for protecting at least one electronic device (9) housed in a housing (2) according to one of claims 1 to 8, in which:

• the air flow (F) circulates in the housing (2) from the intake ports (40) to the discharge ports (30) via the ventilation ports (13), and
• when liquid (E) enters the housing (2) via the discharge ports (30), the internal protection conduit (10) confines the liquid (E) in the exposed volume (V1), so as to protect the electronic device (9) in the protected volume (V2).