The field of the present invention is that of heat exchangers which equip air- conditioning installations for a vehicle, in particular a motor vehicle. The invention relates more specifically to a device for distribution of a cooling fluid inside a header box which a heat exchanger of this type comprises, and means for retention of the distribution device in a header box of this type.

Vehicles are commonly equipped with an air conditioning installation in order to treat thermally the air which is present in, or conveyed to, the passenger space of the vehicle. An installation of this type comprises a closed circuit inside which a cooling fluid circulates. In succession in the direction of circulation of the cooling fluid through it, the circuit substantially comprises a compressor, a condenser, a pressure-reducing unit, and at least one heat exchanger.

The heat exchanger commonly comprises a bundle of tubes interposed between a header box and a box for return of the cooling fluid. The cooling fluid is admitted inside the header box, circulates according to successive paths in the tubes of the bundle between the header box and the return box, and is then discharged from the heat exchanger.

The heat exchanger is for example an evaporator which provides an exchange of heat between the cooling fluid and a flow of air which passes through it. In this case, the cooling fluid circulates inside tubes of the bundle, and the flow of air circulates along tubes of the bundle in order to cool them.

It is known to accommodate inside the header box a device for distribution of the cooling fluid comprising a duct provided with a plurality of orifices. The cooling fluid in the liquid phase is thus sprayed through the orifices in the form of droplets along the entire length of the duct, as indicated in document EP2392886A2.

A general technical problem consists in the industrial implementation of a concept of this type. In particular, the means for securing and/or retention of the distribution device in the header box are not dealt with.

More particularly, the production of a heat exchanger in conformity with the aforementioned document can give rise to deformations of the distribution device, affecting its structure and/or its position inside the header box. This has the effect of making the distribution device fragile by generating buckling of it along the length of the header box, and consequently disrupting obtaining of homogeneous distribution of the cooling fluid towards each of the tubes which the heat exchanger comprises.

The subject of the present invention is a header box for a heat exchanger equipped with a device for distribution of a cooling fluid inside the header box. The subject of the invention is also a heat exchanger equipped with a header box according to the invention.

An objective of the invention is to improve the means for retention of the position and/or maintenance of the shape of the distribution device inside the header box.

An effect sought by the invention is to improve the homogeneous supply of cooling fluid from the header box towards each of the tubes of a bundle of tubes which the heat exchanger comprises, in order to improve the homogeneity of the temperature of the heat exchanger in operation, and finally its performance.

Another objective of the invention is to propose a header box and/or a heat exchanger of this type which can be obtained industrially at lower costs, whilst being able to provide the reliability and performance required for the distribution of the cooling fluid inside the header box and/or towards each of the tubes of the bundle of tubes.

The header box for a heat exchanger according to the invention can have a cooling fluid passing through it. The header box comprises a wall delimiting a chamber which accommodates a device for distribution of the cooling fluid inside the chamber. The distribution device comprises at least one duct which extends between two ends along a longitudinal axis. At least one of the ends of the ducts is provided with an input mouth for intake of the cooling fluid inside the distribution device. The distribution device is provided with at least one orifice for the discharge of the cooling fluid from the distribution device to the chamber.

According to the invention, at least one unit for centring the distribution device inside the chamber is disposed between the ends of the distribution device along the longitudinal axis.

In other words, the distribution device is configured to spray towards the chamber, through the orifice(s), the cooling fluid previously admitted inside the distribution device via the input mouth. The distribution device and/or the duct(s) which it comprises extend longitudinally along the longitudinal axis.

The ends between which at least one centring unit is placed are the longitudinal ends of the distribution device.

The orifice(s) open(s) onto the chamber, whilst being arranged on a longitudinally median part of a duct which the distribution device comprises. The longitudinally median part of the duct extends inside the chamber, between two longitudinal ends of the distribution device which are secured on the wall of the header box, in particular by welding.

More particularly, the longitudinal ends of at least one duct which the distribution device comprises are secured on the wall of the header box. The end parts of the duct which are situated at the end of the duct along the longitudinal axis are for example secured on plates which the wall of the header box comprises, and which are oriented in a direction transverse to the longitudinal axis.

The centring unit(s) is/are more specifically disposed inside the chamber, between the longitudinal ends of the distribution device which are secured on the wall of the header box, in particular on the plates which it comprises. In other words, the centring unit(s) is/are disposed along the longitudinal axis in one or a plurality of locations situated on the longitudinally median part of the duct comprising the orifice(s).

Thus, according to one embodiment, the centring unit is interposed between the wall of the header box and the distribution device, in a direction transverse to the longitudinal axis.

More specifically, the centring unit(s) extend(s) in a direction transverse to the longitudinal axis from one to the other of the distribution device and a wall element of the header box surrounding the distribution device. The centring unit(s) is/are in contact with the distribution device and the wall of the header box, for their welding firstly around the distribution device and secondly on the wall of the header box.

The centring unit thus has a bearing for support of the distribution device inside the chamber, between its ends which are secured on the wall of the header box. The centring unit then forms a unit for retention of the distribution device between its longitudinal ends, against any buckling of the device. Buckling of this type is potentially caused during the welding of the distribution device on the wall of the header box, and/or during an operation of welding of the heat exchange components to one another.

The distribution device is advantageously secured on the wall of the header box, firstly via its longitudinal ends, and secondly via the centring unit(s). The distribution device is thus firmly retained in position inside the chamber, not only at each of its longitudinal ends, but also in its longitudinally median part which extends inside the chamber.

The operation of welding of the distribution device on the wall of the header box and/or the operation of welding of the components of the heat exchanger to one another are carried out in particular by brazing in an oven. The said components comprise in particular at least the header box and the tubes of a bundle of tubes which the heat exchanger comprises, and which are supplied with cooling fluid from the header box. The said components also comprise the distribution device, the retention of which on the wall of the header box via the centring unit(s) protects it against any buckling during the brazing in the oven of the components of the heat exchanger to one another.

According to one embodiment, the orifice(s) is/are oriented in one or a plurality of directions transverse to the longitudinal axis. A plurality of orifices are distributed along the duct, whilst being for example aligned along a straight line oriented parallel to the longitudinal axis.

The input mouth is in particular arranged at a first longitudinal end of the distribution device along the longitudinal axis. The second longitudinal end of the distribution device, opposite its first longitudinal end along the longitudinal axis, is closed, in order to force the spraying of the cooling fluid from the distribution device through the orifice(s), ensuring mixing of the fluid between a liquid phase and a gaseous phase.

The distribution device is for example installed inside the chamber, whilst being coaxial along the longitudinal axis relative to the median axis of longitudinal extension of the chamber.

The header box is configured in particular to supply with cooling fluid the tubes of the bundle of tubes which the heat exchanger comprises. The wall of the header box comprises in particular a plate through which there are arranged openings for discharge from the header box, towards each of the tubes, of the cooling fluid previously distributed in the chamber by the distribution device. The wall of the header box also comprises a cover which covers the plate, providing an envelope which delimits the chamber, and surrounding the distribution device along the longitudinal axis. The cover surrounds the distribution device spaced transversely relative to the longitudinal axis, providing between them a space for circulation of the cooling fluid at least partly around the distribution device towards the openings.

According to one embodiment, the centring unit is interposed between at least two orifices. In other words, a gap of at least one orifice is disposed along the longitudinal axis from one side to the other of at least one centring unit.

According to one embodiment, the centring unit has a partition which divides the chamber along the longitudinal axis into cells which are independent from one another. At least one orifice and at least one opening for discharge of the cooling fluid from the chamber open onto each of the cells.

The cells provide spaces for circulation of cooling fluid from the orifices towards the openings which are independent from one another. The circulation of the cooling fluid takes place in each of the cells around the distribution device, i.e. from the orifices towards the openings on each side of the longitudinal axis. The homogeneous supply with cooling fluid to each of the tubes of the heat exchanger is thus improved.

The number of orifices and/or the number of openings which open onto the cells can be identical or differentiated between two distinct cells. The number of orifices and/or the number of openings opening onto a single cell can be identical or differentiated.

According to one embodiment, a plurality of centring units are distributed along the longitudinal axis. The number of centring units depends on the length of extension of the distribution device along the longitudinal axis, and is at least equal to a number designed to prevent buckling of the device during the welding of the distribution device on the wall of the header box, in particular by brazing in an oven of the components of the heat exchanger to one another.

According to one embodiment, a plurality of centring units are distributed equally along the distribution device, or in other words are disposed equally spaced from one another along the longitudinal axis. According to an alternative embodiment, a plurality of centring units can also be distributed at variable distances from one another along the distribution device, or in other words be distributed at variable distances from one another along the longitudinal axis. There are at least two centring units, and the number of cells is then at least three. In this case, the number of centring units is adapted in particular according to the extent of the distribution device, in order to keep it in shape as well as possible along its entire length, and/or in order to delimit a number of cells which assists in the best possible way the homogeneous distribution of the cooling fluid to each of the tubes.

According to one embodiment, the centring unit is obtained from a wall of the duct of the distribution device through which the orifice is provided.

The centring unit can for example be provided by machining, by deformation, and/or by forming of the wall of the duct through which the orifice(s) is/are provided. The centring unit can also be added, in particular by welding, onto the distribution device, and more specifically onto the duct provided with the orifice(s).

For example, the centring unit is formed by deformation of a wall of the distribution device through which the orifice is provided. More particularly, the centring unit is for example configured as a ring formed by transverse folding back of the wall of the distribution device through which the orifice(s) is/are provided.

Also for example, the centring unit is formed by at least one helix wound along an axis of winding.

The helix comprises at least one turn. The winding of a turn around the axis of winding can be less than a complete turn. The winding of a turn around the axis of winding is a complete turn in order to provide the independence of the cells between two immediately adjacent turns along the longitudinal axis. At least one helix can comprise a plurality of turns.

The axis of winding of the helix is in particular oriented parallel to the longitudinal axis. According to a more specific embodiment, the axis of winding of the helix and the longitudinal axis coincide.

According to one example, there is a single helix comprising a plurality of successive turns distributed along the duct, forming a monolithic body interposed between the distribution device and the wall of the header box. The helix is for example formed by extrusion of a cylinder during the formation of the duct from the said cylinder. A plurality of helices and/or the turns of a single helix are in particular distributed along the distribution device, with a pitch which is preferably regular. The distribution pitch of the helices and/or of the turns of a single helix are for example equal to the distribution pitch of the orifices and/or to the distribution pitch of the openings along the longitudinal axis. Also for example, the distribution pitch of the helices and/or of the turns of a single helix is equal to a multiple of the distribution pitch of the orifices and/or of the distribution pitch of the openings along the longitudinal axis.

A plurality of helices with at least one turn can be distributed along the distribution device, in particular equally spaced from one another. One or a plurality of helices with at least one turn can also be added around the distribution device with which the helix/helices can be integrated, in particular by welding.

According to one embodiment, the centring unit is formed by a flange comprising an eyelet through which the distribution device passes, the flange being indexed on a plate of the header box.

The plate is in particular an element of the wall of the header box which extends parallel to the longitudinal axis, and comprises the openings for discharge of the cooling fluid from the chamber to the tubes of the bundle of tubes which the heat exchanger comprises.

According to a particular embodiment, the distribution device comprises at least two ducts. A first duct provided with the input mouth is surrounded by a second duct provided with the orifice. The first duct comprises at least one passage for discharge of the cooling fluid from the first duct towards the orifice.

It will be noted that the second duct surrounds the first duct transversely spaced relative to the longitudinal axis, providing between them a channel for circulation of the cooling fluid. The passage(s) is/are oriented in particular in a direction which is transverse relative to the longitudinal axis. The passage(s) is/are angularly offset relative to the orifice(s) in order to optimise the path travelled by the cooling fluid inside the channel.

Advantageously, the first duct and the second duct are coaxial. The passages are for example distributed along the first duct, whilst being aligned along a straight line parallel to the longitudinal axis, and therefore parallel to the straight line along which the orifices are aligned. The cooling fluid which is discharged from the first duct through the passage(s) then circulates inside the channel, around the first duct, before being discharged from the distribution device through the orifice(s). A step of homogenisation of the cooling fluid between a liquid phase and a gaseous phase is thus provided before the fluid is discharged from the distribution device through the orifice(s). Homogeneous distribution of the cooling fluid between a liquid phase and gaseous phase inside the chamber is therefore improved by this means.

The distribution device is secured at its longitudinal ends on the wall of the header box via at least one out of the first duct and/or the second duct. In other words, the distribution device can be secured at its longitudinal ends on the wall of the header box either via the first duct or via the second duct, or via the first duct and the second duct.

The invention also relates to a heat exchanger comprising a header box according to the invention.

The heat exchanger is more specifically configured to equip an installation for ventilation, heating, and/or air conditioning which equips a vehicle, in particular a motor vehicle.

The wall of the header box comprises openings through it which are distributed along the longitudinal axis, whilst each being oriented perpendicularly to the longitudinal axis. Each of the openings opens individually onto tubes of a bundle of tubes which the heat exchanger comprises. In particular, the openings are provided through the plate which the wall of the header box comprises.

The wall of the header box, in particular the wall elements which it comprises, the distribution device and the tubes, can advantageously be assembled to one another during a single welding operation, in particular by brazing in an oven, without affecting the retention in position of the distribution device inside the chamber.

The centring unit(s) can be secured on, or incorporated in, the distribution device before its installation inside the chamber. This is carried out for example in the case when the centring unit(s) is/are formed by at least one helix or by fold-backs obtained from the wall of a duct which the distribution device comprises.

According to an alternative embodiment, the centring units can be welded interposed between the wall of the header box and the distribution device during the operation of brazing of the components of the heat exchanger to one another. This is carried out for example in the case when the centring units are formed by flanges.

Other characteristics, details and advantages of the present invention will become more apparent from reading the following description provided by way of indication, and for example in relation with the drawings of the appended figures, in which:

- figure 1 is a schematic illustration of an embodiment of a heat exchanger comprising a header box equipped with a device for distribution of a cooling fluid inside the header box;

- figure 2, figure 3 and figure 4 are schematic representations of various embodiments of header boxes according to the invention;

- figure 5, figure 6 and figure 7 are partially exploded illustrations in perspective of different embodiments of header boxes according to the invention.

It should be noted firstly that the figures disclose the present invention in detail and according to particular modes of its implementation. It will be appreciated that the said figures and their detailed descriptions can be used as required to define the invention better.

In figure 1, a heat exchanger 1 is for example dedicated to the cooling of a flow of air FA which passes through it in order to treat thermally the air of the passenger space of the vehicle, in particular a motor vehicle, or for example also to cool a unit of the vehicle in operation. Also for example, the heat exchanger 1 can be dedicated to the cooling of a liquid which is used to cool a unit of the vehicle in operation, such as one or a plurality of batteries which supply electrical energy for propulsive electrical motorisation of the vehicle.

The heat exchanger 1 comprises a bundle 2 of tubes 3 interposed between a header box 4 and a return box 5. The header box 4 extends in a longitudinal direction Dl which is oriented perpendicularly to a direction D2 of extension of the tubes 3, between the header box 4 and the return box 5. The header box 4 delimits a chamber 6 which accommodates a device 7 for distribution of a cooling fluid FR, in order to supply the header box 4 with cooling fluid FR.

For this purpose, the distribution device 7 comprises at least one duct 8 with a longitudinal axis Al which is for example centred inside the chamber 6, whilst being oriented in the longitudinal direction Dl of the header box 4. A first longitudinal end 9a of the distribution device 7 is provided with an input mouth 10 for the intake of a cooling fluid FR inside the distribution device 7. A second longitudinal end 9b of the distribution device 7 is closed.

Along the longitudinal axis Al, the duct 8 comprises a plurality of orifices 11 in order to distribute the cooling fluid FR admitted into the distribution device 7 towards the chamber 6. The cooling fluid FR then circulates inside the chamber 6 towards the tubes 3 to cool the tubes, then is discharged from the heat exchanger 1 through an output mouth 12.

In the example illustrated, the output mouth 12 is provided through a compartment 13 for discharge of the cooling fluid FR from the heat exchanger 1, which compartment is adjacent to a compartment of the header box 4 containing the chamber 6. In this case, the heat exchanger 1 is a heat exchanger with circulation in the form of a“U”.

According to a variant, the output mouth 12 can be provided through the return box 5. In this case, the heat exchanger 1 is a heat exchanger with circulation in the form of an

In figures 2 to 7, a header box 4 according to the invention comprises a wall 14 delimiting the chamber 6 which accommodates the distribution device 7. The distribution device 7 extends longitudinally along the longitudinal axis Al, whilst being welded at each of its longitudinal ends 9a, 9b on transverse wall elements l4a which the wall 14 of the header box 4 comprises. The transverse wall elements l4a delimit the chamber 6 along the longitudinal axis Al, whilst being oriented perpendicularly to the longitudinal axis Al. In the examples illustrated in figures 5 to 7, the transverse wall elements l4a are for example arranged in the form of plates 15.

The wall 14 of the header box 4 also comprises longitudinal wall elements l4b, l4c, which delimit the chamber 6 along the longitudinal axis Al between the transverse wall elements l4a. The longitudinal wall elements l4b, l4c are disposed spaced from the distribution device 7, transversely relative to the longitudinal axis Al, in order to provide inside the chamber 6 a space El for circulation of the cooling fluid FR around the distribution device 7, before the discharge of the cooling fluid FR from the header box 4 to the tubes 3 which the heat exchanger 1 comprises, as illustrated in figures 2 to 4.

A first longitudinal wall element l4b covers a second longitudinal wall element l4c through which there are provided openings 16 for the discharge of the cooling fluid FR from the header box 4 to the tubes 3 which the heat exchanger 1 comprises. In the examples illustrated in figures 5 to 7, the first longitudinal wall element l4b is designed as a cover 17, and the second longitudinal wall element l4c is designed as a plate 18. The cover 17 and the plate 18 are welded to one another and on the plates 15.

The orifices 11 are provided along a longitudinally median part 9c of the distribution device 7 which extends inside the chamber 6, between the longitudinal ends 9a, 9b of the distribution device 7 welded on the wall 14 of the header box 4. In other words, the longitudinally median part 9c of the distribution device 7 extends inside the chamber 6, between the inner faces of the transverse wall elements l4a which are oriented towards the inside of the chamber 6.

In the examples illustrated, the orifices 11 are aligned along a first straight line Ll parallel to the longitudinal axis Al. The orifices 11 open onto the space El opposite the openings 16 relative to the longitudinal axis Al. In other words, the orifices 11 and the openings 16 open onto the space El transversely on both sides of the longitudinal axis Al.

In this context, the distribution device 7 is retained in position inside the header box 4 not only via its longitudinal ends 9a, 9b which are welded on the transverse wall elements l4a, but also via one or a plurality of centring units 19 disposed inside the chamber 6. The centring unit(s) 19 is/are interposed between the longitudinally median part 9c of the distribution device and the wall 14 of the header box 4, extending inside the chamber 6 in a direction transverse to the longitudinal axis Al, between the distribution device 7 and the wall 14 of the header box 7.

The centring unit(s) 19 form a unit for retention in position of the distribution device 7 inside the chamber 6. The distribution device 7 is thus retained inside the chamber 6, via the centring unit(s) 19, in a position centred on the longitudinal axis Al over all of its length, between its longitudinal ends 9a, 9b which are welded on the wall 14 of the header box 7.

The centring unit(s) 19 is/are interposed between at least two orifices 11 and/or at least two openings 16. In other words, two immediately adjacent centring units 19 along the longitudinal axis are liable to be separated from one another by a portion of the distribution device 7 comprising at least one orifice 11, and/or by a portion of the wall 14 of the header box 7 comprising at least one opening 16. The centring unit(s) 19 is/are liable to surround all or part of the periphery of the distribution device 7. As illustrated in figures 2 to 7, one or a plurality of centring units 19 surround(s) all of the periphery of the distribution device 7. Thus, as shown more particularly in figures 2 to 4, the centring units 19 each form a partition which divides the space El into a plurality of cells 20 distributed along the longitudinal axis Al. The cells 20 are independent from one another, or in other words are successively separated from one another along the longitudinal axis Al by a centring unit 19 which prevents circulation of the cooling fluid FR between two immediately adjacent cells 20.

A variant cannot be excluded according to which at least a first centring unit 19 surrounds the distribution device 7 partly, whilst being interposed along the longitudinal axis Al between two second centring units 19 which surround all of the periphery of the distribution device 7. In this case, only the second centring units 19 form partitions which delimit a cell 20 between them.

As illustrated in figures 2 to 4, the cooling fluid FR is sprayed through the orifices 11 in order to be discharged from the distribution device 7 towards each of the cells 20. The cooling fluid FR then circulates inside each of the cells 20, around the distribution device 7, before being discharged from the chamber 6 through the openings 16 which open onto the different cells 20. The homogeneity of the supply of cooling fluid FR of each of the tubes 3 which the heat exchanger 1 comprises is optimised, and the performance of the heat exchanger 1 is improved accordingly.

The distribution device 7 can be installed inside the chamber 6 by introduction of one of its longitudinal ends 9a, 9b through one of the transverse wall elements l4a along the longitudinal axis Al. Then, the distribution device 7 can be inserted by sliding along the longitudinal axis Al inside the chamber 6, whilst being guided along a median axis of longitudinal extension A2 of the header box 4 via the centring unit(s) 19. The insertion by sliding of the distribution device 7 inside the chamber 6 then takes place until its other longitudinal end 9a, 9b is received by the transverse wall element l4a which is allocated to it.

The median axis of extension A2 of the header box 4 corresponds in particular to the centring axis defined by the centring unit(s) 19 retaining the distribution device 7 in position inside the chamber 6. According to the examples illustrated in figures 2 to 7, the median axis of extension A2 of the header box 4 and the longitudinal axis of extension Al of the distribution device 7 coincide. According to a possible variant, the median axis of extension A2 of the header box 4 and the longitudinal axis of extension Al of the distribution device 7 can be eccentric relative to one another.

According to the embodiment illustrated in figure 5, the centring unit(s) 19 is/are installed on the wall 14 of the header box 4 before the installation of the distribution device 7 inside the chamber 6. In this context, the distribution device 7 is guided in sliding along the median axis A2 of the header box 4 when it is installed inside the chamber 6, after its passage through the centring unit(s) 19.

According to the embodiments illustrated in figures 6 and 7, the centring unit(s) are integrated in the distribution device 7 before its installation inside the chamber 6. In this context, the distribution device 7 is guided in sliding along the median axis A2 of the header box 4 during its installation inside the chamber 6, further to the contact between the centring unit(s) 19 along the wall 14 of the header box 4.

In figure 5, the centring units 19 are formed by flanges 21. According to the embodiment illustrated, the flanges 21 and the plates 15 have configurations which are advantageously identical. The flanges 21 are welded firstly on the periphery of the distribution device 7, and secondly on the cover 17 and on the plate 18. The flanges 21 are each configured as bearings for retention of the distribution device 7 inside the chamber 6, and each comprise an eyelet 22 through which the distribution device 7 passes along the longitudinal axis Al, during its installation inside the chamber 6.

In figure 6, the centring units 19 are each formed by a turn 23 which at least one helix 24 wound around the distribution device 7 comprises. The axis of winding A3 of the helix 24 and the longitudinal axis Al of the distribution device 7 are in particular coaxial. According to the embodiment illustrated, there is a single helix 24 which is integrated in the duct comprising the orifices 11. The helix 24 extends along the longitudinal axis Al, in particular along almost all of the length of the longitudinally median part 9c of the distribution device 7. The helix 24 can thus for example be formed by extrusion together with the formation of a duct 27 which the distribution device 7 comprises, and which comprises the orifices 11.

In figure 7, the centring units 19 are each formed by a ring 25 which surrounds the distribution device 7. According to the example illustrated, the rings 25 are integrated in the distribution device 7. The rings 25 are for example welded around the distribution device 7 before its installation inside the chamber 6, or, as illustrated, they are obtained from the duct 27 which the distribution device 7 comprises, and which comprises the orifices 11, for example by formation of fold-backs along its wall.

In figures 2 to 7, the distribution device 7 can comprise a single duct 8 or a plurality of ducts 26, 27 extending along the longitudinal axis Al.

In figures 2 and 3, the distribution device 7 comprises a single duct 8 provided with the input mouth 10 at a first longitudinal end 8a, and closed at its second longitudinal end 8b. The duct 8 comprises orifices 11 through which the cooling fluid FR is discharged from the distribution device 7 towards the chamber 6. The longitudinal ends 8a, 8b of the duct 8 are welded on the transverse wall elements l4a in order to secure the distribution device 7 at its longitudinal ends 9a, 9b on the wall 14 of the header box 4.

In figures 4 to 7, the distribution device 7 comprises two ducts 26, 27, which are coaxial and centred on the longitudinal axis Al.

Shown more particularly in figure 4, a first duct 26 is provided with the input mouth 10 at a first longitudinal end 26a, and is closed at its second longitudinal end 26b. The first duct 26 is surrounded by a second duct 27 provided with the orifices 11, and is closed at its longitudinal ends 27a, 27b. The second duct 27 surrounds the first duct 26 spaced transversely from the longitudinal axis Al, in order to provide a channel 28 for circulation of the cooling fluid FR inside the distribution device 7.

The first duct comprises passages 29 for discharge of the cooling fluid FR from the first duct 26 towards the channel 28. According to the example illustrated, the passages are aligned along a second straight line L2 parallel to the first straight line Ll of alignment of the orifices 11. Transversely to the longitudinal axis Al, the passages 29 open onto the channel 28 opposite the opening of the orifices 11 onto the space El provided inside the chamber 6.

Thus, the cooling fluid FR admitted inside the distribution device 7 through the input mouth 10 circulates inside the first duct 26, then is discharged towards the channel 28 through the passages 29. The cooling fluid FR circulates inside the channel 28 around the first duct 26, before being discharged from the distribution device 7 through the orifices 11. Mixing of the cooling fluid FR between a liquid phase and a gaseous phase is thus provided inside the distribution device 7, before the discharge of the cooling fluid FR through the orifices 11 out of the distribution device towards the space El.