The field of the present invention is that of heat exchangers that form part of a refrigerant circuit with which a motor vehicle is equipped. The subject of the invention is such a heat exchanger.

A motor vehicle is commonly equipped with a heating, ventilation and/or air conditioning installation for thermally treating the air present in or sent into the motor vehicle interior. In order to do this, such an installation is associated with a closed circuit inside which a refrigerant flows. The refrigerant circuit comprises, in succession, a compressor, a gas condenser or cooler, an expansion member and a heat exchanger. The heat exchanger is housed inside the heating, ventilation and/or air conditioning installation to allow an exchange of heat between the refrigerant and an air flow circulating through the said installation, prior to the air flow being delivered to the vehicle interior.

According to one mode of operation of the refrigerant circuit, the heat exchanger is used as an evaporator to cool the air flow. In that case, the refrigerant is compressed inside the compressor, then the refrigerant is cooled inside the gas condenser or cooler, then the refrigerant undergoes expansion in the expansion member and finally the refrigerant picks up heat energy from the air flow inside the heat exchanger. The refrigerant, as it leaves the expansion member and as it enters the heat exchanger, is in the biphasic state and is present in a liquid phase and a gas phase.

The heat exchanger is notably a heat exchanger in which the refrigerant flows along a U-shaped path. To this end, the heat exchanger comprises a header tank and a return tank between which tanks a core bundle of tubes is interposed. The return tank is formed of an enclosure which delimits a unit volume extending from one side of the heat exchanger to the other. The tubes are arranged in two parallel layers which extend between two lateral edges of the heat exchanger. A first layer of first tubes is in fluidic communication with the return tank and a first chamber housed inside the header tank. A second layer of second tubes is in fluidic communication with the return tank and a second chamber likewise housed inside the header tank. During operation of the refrigerant circuit, the refrigerant is admitted to the heat exchanger through an inlet opening that the first chamber comprises. Then the refrigerant flows between the first chamber of the header tank and the return tank, using the first tubes of the first layer. Then the refrigerant flows between the return tank and the second chamber, using the second tubes of the second layer. Finally, the refrigerant is discharged from the heat exchanger through an outlet opening formed through the second chamber.

One general problem that arises lies in the difficulty there is in uniformly supplying the tubes of the core bundle with regard to the different phases of the refrigerant. A first problem lies in the difficulty there is in uniformly supplying the second tubes with refrigerant. A second problem lies in the difficulty there is in uniformly supplying the first tubes with refrigerant.

Now, heterogeneity in the supply of refrigerant to the second tubes and, possibly, to the first tubes, leads to heterogeneity in the temperature of the air flow that passes in succession across the first layer and then the second layer. This heterogeneity is liable to give rise to inappropriate and undesired differences in temperature between zones of the vehicle interior, and this is detrimental. Document US2015/0121950 proposes placing a pipe provided with a plurality of orifices inside the first chamber of the header tank. The liquid-phase refrigerant is then sprayed through the orifices in the form of droplets along the length of the pipe. Document US2015/0121950 also proposes arranging the return tank in a single enclosure in communication with all of the tubes of the core bundle.

Such organization is not optimal from the viewpoint of homogenizing the distribution of refrigerant within the heat exchanger and, more particularly, from the viewpoint of optimizing a mixing of a liquid phase, which is heavy, with a gas phase, which is lighter than the liquid phase, which phases have a tendency to separate. The result of this is heterogeneity in the circulation of refrigerant in the heat exchanger, and heterogeneity in the surface temperature of the heat exchanger, which leads to heterogeneity in the temperature of the air flow leaving the heat exchanger, and this is unsatisfactory. A general objective of the invention is to perfect the homogeneity of the distribution of refrigerant within the heat exchanger and notably within the second tubes that make up the second layer in order ultimately to improve the efficiency and output thereof, with a view to delivering to the vehicle interior an airflow at the desired temperature.

One particular objective of the invention is to optimize a mixing of a liquid phase of the refrigerant with a gas phase of the refrigerant in order to optimize the surface temperature of the heat exchanger and, as a result, the temperature of the air fluid passing through this exchanger, whatever the point of the heat exchanger through which the airflow passes, and/or whatever point of the heat exchanger with which the airflow is in contact.

The heat exchanger of the present invention is a heat exchanger through which a refrigerant is intended to pass; the heat exchanger comprises a header tank and a return tank between which tanks a first layer of first tubes and a second layer of second tubes are interposed. The first tubes comprise a first end in fluidic communication with the return tank and a second end in fluidic communication with the header tank. The second tubes comprise a third end in fluidic communication with the return tank and a fourth end in fluidic communication with the header tank. According to the present invention, the return tank houses at least one refrigerant homogenizing member.

The refrigerant homogenizing member advantageously exhibits at least any one of the following features, on their own or in combination:

- the refrigerant homogenizing member is designed to mix a liquid phase of the refrigerant with a gas phase of the refrigerant,

- the refrigerant homogenizing member is designed to direct the refrigerant from a centre of the return tank towards the third end of the second tubes of the return tank,

- the refrigerant homogenizing member comprises at least one shaft equipped with at least one centrifugal wall,

- the shaft extends at the centre of the return tank,

- the centrifugal wall extends between the shaft and a wall of the return tank,

- there are a plurality of the centrifugal walls all identical to one another, - the centrifugal walls are continuous between two longitudinal ends of the refrigerant homogenizing member,

- the centrifugal wall comprises mixing elements which are borne by the shaft and which are separated from one another by at least one notch,

- the mixing elements are iteratively repeated along the shaft,

- each mixing element is arranged in a helix or a portion of a helix,

- each mixing element extends between a first edge and a second edge which between them make a first angle comprised between 70° and 110°,

- the first edge of a mixing element forms, with a second edge of an adjacent mixing element, a second angle comprised between 70° and 110°,

- each mixing element comprises at least two mixing motifs which are identical and of opposite hand to one another,

- the mixing motif extends between a first lip and a second lip which between them make a lip angle,

- the lip angle is zero,

- the first lip of a mixing motif forms, with a second lip of an adjacent mixing motif, a third angle comprised between 70° and 110°,

- the refrigerant homogenizing member comprises at least one centrifugal wall configured to segment a refrigerant distribution along an axis of elongation of the refrigerant homogenizing member,

- the centrifugal wall extends between a first longitudinal end of the refrigerant homogenizing member and a second longitudinal end of the refrigerant homogenizing member,

- the centrifugal wall is wound around the shaft over at least a portion of the length of the refrigerant homogenizing member between the first longitudinal end of the refrigerant homogenizing member and the second longitudinal end of the refrigerant homogenizing member,

- the centrifugal wall is a helical wall wound around the shaft with a first pitch,

- the centrifugal wall is inclined towards either one of the first longitudinal end of the refrigerant homogenizing member and the second longitudinal end by an angle of inclination comprised between 45° and 80°,

- there are a plurality of the centrifugal walls, these being equidistant from one another along the axis of elongation of the refrigerant homogenizing member, - in a section through the refrigerant homogenizing member taken on a transverse plane, the centrifugal walls are equally angularly distributed around the shaft,

- the centrifugal walls are formed symmetrically around the shaft,

- the centrifugal wall comprises at least one first mixing motif and at least one second mixing motif,

- the first mixing motif and the second mixing motif are identical and are arranged top to toe one after the other along the axis of elongation,

- the first mixing motif is twisted in a clockwise direction about the axis of elongation, whereas the second mixing motif is twisted in an anticlockwise direction about the axis of elongation,

- the lip angle is comprised between 70° and 110°,

- the first mixing motif and the second mixing motif delimit a channel,

- the channel extends between the shaft and the peripheral envelope of the refrigerant homogenizing member,

- the lip angle is comprised between 0° and 90°,

- at least one of the lips is delimited by a crest and by a trough which extend in a plane transverse to the axis of elongation between two adjacent mixing motifs,

- the centrifugal wall is continuous from one mixing motif to another,

- the first lip of a first mixing motif coincides with the second lip of a second mixing motif immediately adjacent to the first mixing motif,

- the first mixing motif is twisted in a clockwise direction about the axis of elongation, whereas the second mixing motif is twisted in an anticlockwise direction about the axis of elongation,

- the first mixing motif and the second mixing motif adjacent to the first mixing motif together form a mixing element repeated along the axis of elongation,

- each mixing motif is arranged in a helix or a portion of a helix,

- the refrigerant homogenizing member comprises a plurality of motifs connected by a shaft, at least two of these motifs being arranged in opposition relative to the shaft,

- a first motif extends radially in a first angular sector whereas a second motif extends radially in a second angular sector that complements and is distinct from the first angular sector, each of these angular sectors extending over 180°,

- at least two mixing motifs emerge from at least two distinct longitudinal segments of the shaft, along an axis of elongation of the shaft to which the motifs are connected, - the mixing motifs have a U-shaped or V-shaped profile,

- the first mixing motif has a U-shaped profile,

- the second mixing motif has a V-shaped profile,

- the shaft and the centrifugal wall are formed as a one-piece component,

- the refrigerant homogenizing member is made from a porous material.

The heat exchanger as provided with the refrigerant homogenizing device installed in the return tank may advantageously also comprise at least one mixing member which extends along and inside the header tank of the heat exchanger, such a mixing member comprising for example any one of the features of the refrigerant homogenizing device.

The invention also relates to a refrigerant circuit comprising at least one such heat exchanger. The invention also relates to a use of such a heat exchanger as an evaporator housed within a housing of a heating, ventilation and/or air conditioning installation with which a motor vehicle is equipped.

The invention also relates to a method for obtaining such a refrigerant homogenizing member from a mould comprising a first mould cavity and a second mould cavity which jointly form a moulding space identical to the refrigerant homogenizing member described in the present document.

Further features, details and advantages of the invention will become apparent from reading the detailed description given hereinbelow by way of illustration and with reference to the drawings of the attached plates, in which:

- Figure 1 is a schematic depiction of a refrigerant circuit comprising a heat exchanger of the present invention,

- Figure 2 is a schematic perspective illustration of a first alternative form of embodiment of the heat exchanger illustrated in Figure 1,

- Figure 3 is a schematic perspective illustration of a first alternative form of embodiment of a refrigerant homogenizing member intended to be fitted in the heat exchanger depicted in Figure 2, - Figure 4 is a schematic perspective illustration of a second alternative form of embodiment of a refrigerant homogenizing member intended to be fitted in the heat exchanger depicted in Figure 2,

- Figure 5 is a schematic cross-sectional illustration of a portion of the refrigerant homogenizing member depicted in Figure 4,

- Figure 6 is a schematic face-on illustration of the refrigerant homogenizing member depicted in Figures 4 and 5,

- Figures 7, 8 and 9 are schematic perspective illustrations of a third alternative form of embodiment of a refrigerant homogenizing member, partially depicted and intended to be fitted in the heat exchanger depicted in Figure 2,

- Figure 10 is a detailed view of the refrigerant homogenizing member depicted in Figures 7, 8 and 9,

- Figure 11 is a schematic perspective illustration of a fourth alternative form of embodiment of a refrigerant homogenizing member intended to be fitted in the heat exchanger depicted in Figure 2,

- Figure 12 is a schematic side-view illustration of a fifth alternative form of embodiment of a refrigerant homogenizing member intended to be fitted in the heat exchanger depicted in Figure 2,

- Figure 13 is a schematic perspective illustration of a second alternative form of embodiment of the heat exchanger illustrated in Figure 1.

The figures and the description thereof set out the invention in detail and according to particular ways of implementing same. They may serve the better to define the invention, where appropriate.

Figure 1 depicts a closed circuit 1 in which a refrigerant FR circulates. In the exemplary embodiment illustrated, the refrigerant circuit 1 comprises, in succession, in a direction SI in which the refrigerant FR circulates within the refrigerant circuit 1, a compressor 2 for compressing the refrigerant FR, a gas condenser or cooler 3 for cooling the refrigerant FR, an expansion member 4 in which the refrigerant FR experiences an expansion and a heat exchanger 5. The heat exchanger 5 is housed within a housing 6 of a heating, ventilation and/or air conditioning installation 7 within which an air flow circulates. The heat exchanger 5 allows heat transfer between the refrigerant FR and the air flow FA coming into contact with it and/or passing through it, as illustrated in Figure 2. According to the mode of operation of the refrigerant circuit 1 described hereinabove, the heat exchanger 5 is used as an evaporator to cool the air flow FA, as the air flow FA comes into contact with and/or passes through the heat exchanger 5.

In Figure 2, the heat exchanger 5 comprises a header tank 8 and a return tank 9 between which tanks a core bundle of tubes 10, 10a, 10b is interposed. Overall, the heat exchanger 5 extends parallel to a first plane PI containing the header tank 8, the core bundle of tubes 10, 10a, 10b and the return tank 9. The header tank 8 surmounts the core bundle of tubes 10, 10a, 10b which are themselves situated above the return tank 9, notably when the heat exchanger 5 mounted inside the housing 6 is in its position of use. In other words, in this position of use, the header tank 8 is a top tank of the heat exchanger 5, whereas the return tank 9 is a bottom tank of the heat exchanger 5. The air flow FA flows through the heat exchanger 5 in a direction preferably orthogonal to the first plane PI, between the top tank and the bottom tank.

The tubes 10, 10a, 10b are, for example, rectilinear and extend along a first axis of overall extension Al between the header tank 8 and the return tank 9. The header tank 8 extends along a second axis of overall extension A2, and the return tank 9 extends along a third axis of overall extension A3. For preference, the second axis of overall extension A2 and the third axis of overall extension A3 are parallel to one another, being orthogonal to the first axis of overall extension Al. The core bundle of tubes 10, 10a, 10b is provided with fins 15 which are interposed between two successive tubes 10, 10a, 10b to encourage an exchange of heat between the air flow FA and the tubes 10, 10a, 10b as the air flow FA passes through the heat exchanger 5, the air flow FA circulating in a direction substantially orthogonal to the first plane PI. The heat exchanger 5 comprises a first opening 16 through which the refrigerant FR enters the heat exchanger 5. The first opening 16 constitutes an intake opening admitting the refrigerant FR into a first chamber 13 which is delimited inside the header tank 8. The heat exchanger 5 comprises a second opening 17 through which the refrigerant FR is removed from the heat exchanger 5.

The heat exchanger according to the invention is a heat exchanger in which the refrigerant FR flows along a U-shaped path. The tubes 10a, 10b are arranged parallel to one another being distributed in two layers 11, 12, these including a first layer 11 of first tubes 10a and a second layer 12 of second tubes 10b. The first layer 11 and the second layer 12 are formed within respective planes which are parallel to one another and parallel to the first plane PI. The first tubes 10a of the first layer 11 comprise a first end 101 which is in fluidic communication with the return tank 9, and a second end 102 which is in fluidic communication with the first chamber 13. The second tubes 10b of the second layer 12 comprise a third end 103 which is in fluidic communication with the return tank 9, and a fourth end 104 which is in fluidic communication with a second chamber 14, likewise delimited within the header tank 8. The first chamber 13 and the second chamber 14 are contiguous and sealed relative to one another.

The first chamber 13 extends along a fourth axis of overall extension A4, and the second chamber 14 extends along a fifth axis of overall extension A5. For preference, the fourth axis of overall extension A4 and the fifth axis of overall extension A5 are parallel to one another, and parallel to the second axis of overall extension A2. The fourth axis of overall extension A4 and the fifth axis of overall extension A5 together define a second plane P2, which is preferably orthogonal to the first plane PI. In other words, the return tank 9 forms the base of the U whereas the first layer 11 and the second layer 12 of tubes 10a, 10b form the branches of the U, the first chamber 13 and the second chamber 14 forming the ends of the U. According to this second alternative form, the second opening 17 equips the second chamber 14 of the header tank 8.

During use of the refrigerant circuit 1, the refrigerant FR enters the heat exchanger 5 through the first opening 16 in the first chamber 13, possibly being distributed along the header tank 8 along the second axis of overall extension A2 by a distribution homogenizing device 18. The presence of the distribution homogenizing device 18 is optional which means that the heat exchanger 5 of the present invention comprises either a single refrigerant homogenizing member 200 placed in the return tank, or a refrigerant homogenizing member placed in the return tank in combination with a distribution homogenizing device 18 installed in the first chamber 13 and/or at the level of the second tubes 10b. Thus, in Figure 2, the heat exchanger 5 is free of the distribution homogenizing device 18, whereas in Figure 13, the heat exchanger 5 is provided with a distribution homogenizing device 18 which is housed inside the first chamber 13 of the header tank 8.

Whatever the alternative form of embodiment of the heat exchanger 5, the refrigerant FR flows between the first chamber 13 of the header tank 8 and the return tank 9, using the first tubes 10a of the first layer 11. Then the refrigerant FR flows between the return tank 9 and the second chamber 14, using the second tubes 10b of the second layer 12. Finally, the refrigerant FR is discharged from the heat exchanger 5 through the second opening 17 after having circulated through the second chamber 14. For preference, a first tube 10a of the first layer 11 is aligned with a second tube 10b of the second layer 12 in a third plane P3 which is perpendicular to the first plane PI and which is parallel to the first axis of overall extension Al.

According to the present invention, the return tank 9 houses a homogenizing member 200 for homogenizing the refrigerant inside the return tank 9 and/or the second tubes 10b. Such a refrigerant homogenizing member 200 seeks to homogeneously distribute the refrigerant FR, in the liquid - gas biphasic state, along the return tank 9 and in fine inside the collection of second tubes 10b. Such a refrigerant homogenizing member 200 also seeks to homogeneously distribute the refrigerant FR inside the heat exchanger 5, including when the refrigerant FR is present inside the heat exchanger 5 in two distinct phases, liquid and gas, in variable respective proportions. More specifically, such a refrigerant homogenizing member 200 seeks to stir the phases of the refrigerant FR inside the return tank 9 so that the refrigerant FR is homogeneous as soon as it is admitted into second tubes 10b. The refrigerant homogenizing member 200 is intended to encourage mixing between the liquid and gas phases of the refrigerant FR. In order to do this, the refrigerant homogenizing member 200 is a member that acts as an obstacle able to stir the liquid phase of the refrigerant FR and the gas phase of the refrigerant FR in such a way as to mix these together. The refrigerant homogenizing member 200 is also designed to avoid any buildup of refrigerant in the liquid state in a lower region of the return tank 9 when the latter is in the position of use. The refrigerant homogenizing member 200 is also designed to disrupt the flow of refrigerant FR inside the return tank 9 so as to mix the liquid and gas phases of the refrigerant FR. In other words, the refrigerant homogenizing member 200 forms at least one baffle and preferably a plurality of baffles impeding laminar flow parallel to the third axis of overall extension A3. In general terms, the refrigerant homogenizing member 200 acts as an obstacle to the flow of refrigerant FR inside the return tank 9. The refrigerant homogenizing member 200 extends longitudinally along an axis of elongation A6 which is preferably parallel to, or even coincident with, the third axis of overall extension A3 of the return tank 9.

The refrigerant homogenizing member 200 may extend inside and over the entire length of the return tank 9. The refrigerant homogenizing member 200 may also fill all of the volume delimited by the return tank 9. According to the alternative forms described herein below, the refrigerant homogenizing member 200 is preferably of cylindrical overall shape or alternatively of any other shape formed around the axis of elongation A6. It will be appreciated that such a shape is defined overall by a peripheral envelope 201 of the refrigerant homogenizing member 200. The peripheral envelope 201 of the refrigerant homogenizing member 200 is formed of those surfaces of the refrigerant homogenizing member 200 which are positioned facing walls delimiting the return tank 9.

It follows from these measures that the refrigerant FR entering the heat exchanger 5 via the first opening 16 flows inside the header tank 8. The refrigerant FR then flows through the core bundle of first tubes 10a as far as the return tank 9. Inside the return tank 9, the liquid and gas phases of the refrigerant FR are mixed with one another by the refrigerant homogenizing member 200. The refrigerant FR thus mixed then takes the second tubes 10b in order to reach the second chamber 14 and finally be discharged from the heat exchanger 5 via the second opening 17.

When the refrigerant FR passes through the return tank 9 thus equipped with the refrigerant homogenizing member 200, the refrigerant FR encounters multiple obstacles which encourage mixing between its liquid and gas phases. In addition, it then follows that the refrigerant homogenizing member 200 encourages homogenization of the distribution of refrigerant FR within the tubes 10b of the second layer 12. In Figures 3 to 12, the refrigerant homogenizing member 200 comprises a shaft 202 bearing at least one centrifugal wall 203.

The shaft 202 preferably extends longitudinally at a centre C of the return tank 9 along the axis of elongation A6 of the refrigerant homogenizing member 200. The centre C of the return tank 9 corresponds to a central zone thereof, notably one that is central with respect to an inlet face via which the air flow FA enters the heat exchanger 5 and an outlet face via which the air flow FA leaves the heat exchanger 5, which means to say in the thickness of the heat exchanger 5. The shaft 202 is also cylindrical, being formed at the centre C of the return tank 9. The shaft 202 is made up of a central core of the refrigerant homogenizing member 200 that forms a continuity of material from a first longitudinal end 204a to a second longitudinal end 204b, as illustrated in Figure 4. The shaft 202 is, for example, arranged transversely to the centre of mass of the refrigerant homogenizing member 200. The shaft 202 is preferably shaped into a rectilinear rod from which the centrifugal wall 203 extends. The centrifugal wall 203 extends from the shaft 202 as far as the peripheral envelope 201 of the refrigerant homogenizing member 200.

In Figures 3 to 6 and Figure 11, the centrifugal wall 203 is a single wall and extends from first longitudinal end 204a of the refrigerant homogenizing member 200 as far as the second longitudinal end 204b of the refrigerant homogenizing member 200. In such an instance, the centrifugal wall 203 is considered as being continuous between the two longitudinal ends 204a, 204b of the refrigerant homogenizing member 200. In the case of Figure 4, the refrigerant homogenizing member 200 comprises a plurality of centrifugal walls 203 formed in this way.

In Figures 7 to 10 and 12, the centrifugal wall 203 is discontinuous. It will be appreciated here that the mixing elements 205 that make up the centrifugal wall 203 are separated from one another by notches 206. The mixing elements 205 are, for example, identical to one another and repeated iteratively along the axis of elongation A6. In other words, the mixing elements 205 are, for example, similar to one another and can be geometrically substituted for one another without modifying the configuration of the refrigerant homogenizing member 200. In addition, the mixing elements 205 are, for example, repeated one after another, being identical to one another, thereby giving the refrigerant homogenizing member 200 geometric homogeneity from the first longitudinal end 204a to the second longitudinal end 204b. Each mixing element 205 is, for example, also formed of two mixing motifs 207 which are identical to one another but butted together head to toe along the axis of elongation A6.

According to an alternative form of embodiment of the refrigerant homogenizing member 200, illustrated in Figure 3, the refrigerant homogenizing member 200 comprises a single centrifugal wall 203 wound longitudinally along the shaft 202. The centrifugal wall 203 is arranged in at least one twist, and preferably a plurality of twists, for example identical to one another but liable to be distinct from one another. In particular, two successive twists are liable to be different from one another either in terms of their respective shape and size or in terms of their spatial layout. The refrigerant homogenizing member 200 is notably configured into a helical screw comprising a single thread formed of the centrifugal wall 203 and a central core formed of the shaft 202. The helix pitch is, for example, determined so that one pitch feeds into one second tube 10b. In other words, the pitch of the helix is equal to a distance between two immediately adjacent second tubes 10b.

According to an alternative form of embodiment of the refrigerant homogenizing member 200 illustrated in Figure 4, the refrigerant homogenizing member 200 comprises a plurality of centrifugal walls 203 which are continuous over at least a portion of the length of the refrigerant homogenizing member 200, for example from the first longitudinal end 204a as far as the second longitudinal end 204b. These centrifugal walls 203 are thus wound longitudinally along the shaft 202. In the example illustrated, the refrigerant homogenizing member 200 comprises six centrifugal walls 203 longitudinally equidistant from one another. The refrigerant homogenizing member 200 is configured into a helical screw comprising for example six threads formed by the six centrifugal walls 203 and a central core formed by the shaft 202. In that case, the pitch of the helices is the same from one helix to another. The pitch of the helices is equal to a distance between two immediately adjacent second tubes 10b of the heat exchanger 5.

As illustrated in Figure 5, the centrifugal walls 203 extend from the shaft 202 as far as the peripheral envelope 201 of the refrigerant homogenizing member 200. The centrifugal walls 203 extend from the first longitudinal end 204a as far as the second longitudinal end 204b and are wound longitudinally along the shaft 202. The centrifugal walls 203 are, for example, equidistant from one another along the axis of elongation A6 and two successive centrifugal walls 203 are formed at a first distance Dl which is constant. Each centrifugal wall 203 is shaped into a helicoidal strip formed at a first pitch XI . In the example illustrated, the refrigerant homogenizing member 200 comprises six centrifugal walls 203, and the refrigerant homogenizing member 200 is configured into a helical screw comprising six threads formed by the six centrifugal walls 203 and a central core formed by the shaft 202. In that case, the threads have a first pitch XI, which is the same from one thread to another. Each centrifugal wall 203 is, for example, inclined towards the first longitudinal end 204a of the refrigerant homogenizing member 200 by an angle of inclination o l comprised between 45° and 90°, in order to facilitate the flow of the refrigerant along the shaft 202.

In other words, each centrifugal wall 203 is configured as a helicoidal strip which is wound around the shaft 202 from the first longitudinal end 204a as far as the second longitudinal end 204b. Such winding is performed evenly with a first pitch XI which is constant along the axis of elongation A6 of the refrigerant homogenizing member 200.

According to an alternative form of embodiment of the refrigerant homogenizing member 200, illustrated in Figures 7 to 10, the centrifugal wall 203 comprises a plurality of mixing elements 205 separated from one another by notches 206. The mixing elements 205 are identical to one another and repeated iteratively along the axis of elongation A6. In other words, the mixing elements 205 are butted together successively, beginning on the shaft 202. Each mixing element 205 extends longitudinally between a first edge 208 and a second edge 209. The first edge 208 and the second edge 209 are each formed of an edge corner of the centrifugal wall 203 which is substantially orthogonal to the shaft 202 and which delimits the centrifugal wall 203 in relation to the notches 206. The first edge 208 and the second edge 209 are longitudinally opposed to one another along the axis of elongation A6.

Each mixing element 205 comprises a first mixing motif 207a and a second mixing motif 207b, in the continuation of one another as is the case in Figure 11, or separated from one another as is the case in Figures 7 to 9 and 12.

According to these alternative forms, the first edge 208 and the second edge 209 of a mixing element 205 form between them a first angle a comprised between 70° and 110°, preferably equal to 90°. Again by way of example, a first edge 208 of a mixing element 205 forms, with a second edge 209 of an adjacent mixing element 205, a second angle β comprised between 70° and 110°, preferably equal to 90°. This first angle and this second angle are measured between the relevant edges once they have been projected onto a plane of projection perpendicular to the axis of elongation A6. Each mixing element 205 is, for example, formed of two mixing motifs 207 which are identical to one another but butted together head to toe along the axis of elongation A6. In other words, a direction of winding of one mixing motif 207 is the opposite to the direction of winding of an adjacent mixing motif 207 which motifs make up the mixing element 205. Put differently again, if considering two successive mixing motifs 207, the centrifugal wall 203 of one of them turns in a clockwise direction and the centrifugal wall 203 of the other one turns in an anticlockwise direction.

Each mixing element 205 is formed of two mixing motifs 207 which are identical to one another and butted together head to toe along the axis of elongation A6. What will be understood by an arrangement whereby two mixing motifs 207 are butted together head to toe is an arrangement whereby the two mixing motifs 207 can be superposed in an identical configuration to one another after being pivoted through 180° towards one another in a fourth plane P4 containing the axis of elongation A6. Moreover, a direction of winding of a first mixing motif 207 is the opposite to a direction of winding of an adjacent second mixing motif 207, which motifs make up the one same mixing element 205. In other words, if considering two successive mixing motifs 207, the centrifugal wall 203 of one of them turns in a clockwise direction and the centrifugal wall 203 of the other one turns in an anticlockwise direction. Put differently again, a curvature of a first mixing motif 207 is the inverse of the curvature of the second mixing motifs 207 which directly flank it. It will therefore be appreciated here that when perusing the refrigerant homogenizing member 200 along the axis of elongation A6, a first mixing motif 207 is twisted in a clockwise direction whereas the next second mixing motif 207 that immediately follows it is twisted in an anticlockwise direction.

Figure 10 depicts a first mixing motif 207a of the mixing element 205 illustrated in Figures 7 to 9, of which the centrifugal wall 203 is configured into a portion of a helix formed around the shaft 202. Each mixing element 205 extends longitudinally between a first lip 210 and a second lip 211. The first lip 210 and the second lip 211 are each formed of an edge corner of the centrifugal wall 203 which is substantially orthogonal to the shaft 202 and which delimits the centrifugal wall 203 in relation to a channel 212 formed between two mixing motifs 207. The first lip 210 and the second lip 211 are longitudinally opposed to one another with respect to the axis of elongation A6.

As can be seen in Figures 7 or 9, the first lip 210 and the second lip 211 of a mixing motif 207 are, for example, parallel. Again by way of example, a first lip 210 of a mixing motif 207 forms, with a second lip 211 of an adjacent mixing motif 207 forming part of the same mixing element 205, a third angle γ comprised between 70° and 110°, preferably equal to 90°. This third angle is measured between the relevant lips once they have been projected onto a plane of projection perpendicular to the axis of elongation A6.

These measures are such that the refrigerant FR entering the return tank 9 is distributed homogeneously to all of the second tubes 10b, even in the case of a refrigerant FR present inside the heat exchanger 5 in two phases, liquid and gas.

In addition, the presence of such a refrigerant homogenizing member 200 avoids any buildup of the liquid phase of the refrigerant FR in a lower region of the return tank 9 when the latter is in the position of use.

In Figure 11, the refrigerant homogenizing member 200 comprises a wall 203 which is continuous over at least a portion of the length of the refrigerant homogenizing member 200, and notably between the first longitudinal end and the second longitudinal end of the refrigerant homogenizing member 200. Such a wall 203, qualified as a centrifugal wall 203, is configured in such a way as to direct the refrigerant FR that comes into contact with it in a direction that is radial to the refrigerant homogenizing member 200.

The centrifugal wall 203 is partially or completely twisted between the first longitudinal end and the second longitudinal end. The centrifugal wall 203 has a thickness that is preferably constant between the first longitudinal end and the second longitudinal end. The centrifugal wall 203 is, for example, arranged in one layer that takes the form of a twist.

When the refrigerant homogenizing member 200 is in its position of use inside the return tank 9, as illustrated in Figures 2 and 13, the refrigerant homogenizing member 200 preferably extends longitudinally at a centre C of the return tank 9 along the axis of elongation A6 of the refrigerant homogenizing member 200. The centre C of the return tank 9 corresponds to a central, for example cylindrical, zone thereof.

What is understood here by the continuity of the centrifugal wall 203 between the first longitudinal end and the second longitudinal end of the refrigerant homogenizing member 200 is that the refrigerant homogenizing member 200 is made up of a plurality of mixing elements 205 which are butted together. The mixing elements 205 are, for example, identical to one another and repeated iteratively along the axis of elongation A6. In other words, the mixing elements 205 are, for example, similar to each other and can be geometrically substituted for one another without modifying the configuration of the refrigerant homogenizing member 200. In addition, the mixing elements 205 are, for example, repeated one after another, being identical to one another, give or take the manufacturing tolerances, thereby giving the refrigerant homogenizing member 200 geometric constancy from the first longitudinal end to the second longitudinal end.

As far as Figure 11 is concerned, each mixing element 205 extends longitudinally between a first edge 208 and a second edge 209. The first edge 208 and the second edge 209 are each formed of a crest 50 of the centrifugal wall 203. The crest 50 and a trough 51 are both substantially orthogonal to the axis of elongation A6. The crest 50 forms a line of reversal of slope at which a convex curvature of the twist becomes reversed. The trough 51 forms a line of reversal of slope at which a concave curvature of the twist becomes reversed. In other words, on either side of the crest 50 and of the trough 51, the centrifugal wall 203 changes direction of winding, passing from a clockwise direction to an anticlockwise direction or alternatively from an anticlockwise direction to a clockwise direction.

As far as Figures 7 to 11 are concerned, each mixing element 205 is of a first length LI, measured parallel to the axis of elongation A6, between the first edge 208 and the second edge 209. Two successive mixing elements 205 can be exactly superposed on one another following a translational movement along the axis of elongation A6 by a distance equal to the first length LI.

According to this alternative form, the first edge 208 and the second edge 209 are parallel to one another and orthogonal to the axis of elongation A6. The same applies to the troughs 51 in Figure 11.

Again by way of example, a first edge 208 of a mixing element 205 forms, with a second edge 209 of an adjacent mixing element 205, a zero angle, because the first edge 208 of one mixing element 205 forms or is coincident with a second edge 209 of an adjacent mixing element 205. This angle is measured between the relevant edges once they have been projected onto a plane of projection perpendicular to the axis of elongation A6.

Each mixing element 205 is formed of two mixing motifs 207a, 207b, which are identical to one another, give or take the manufacturing tolerances, and which are butted together head to toe along the axis of elongation A6. What will be understood by an arrangement whereby two mixing motifs 207a, 207b are butted together head to toe is an arrangement whereby the two mixing motifs 207a, 207b can be superposed in an identical configuration to one another after being pivoted through 180° towards one another in a fourth plane P4 containing the axis of elongation A6. As is evident from Figures 7 to 11, a direction of winding of a first mixing motif 207a is the opposite to a direction of winding of an adjacent second mixing motif 207b, which motifs make up the one same mixing element 205. In other words, if considering two successive mixing motifs 207a, 207b, the centrifugal wall 203 of one of them turns in a clockwise direction and the centrifugal wall 203 of the other one turns in an anticlockwise direction. Put differently again, a curvature of a first mixing motif 207a is the inverse of the curvature of the second mixing motifs 207b. It will therefore be appreciated here that when perusing the refrigerant homogenizing member 200 along the axis of elongation A6, a first mixing motif 207a is twisted in a clockwise direction whereas the next second mixing motif 207b that immediately follows it is twisted in an anticlockwise direction.

One mixing motif, which may just as well be the first motif 207a as the second motif 207b, of the mixing element 205 illustrated in Figure 11, is configured into a portion of a helix winding around the axis of elongation A6. Each mixing motif 207a, 207b extends longitudinally along the axis of elongation A6 between a first lip 210 and a second lip 211. The first lip 210 and the second lip 211 are each formed of a crest 50 and of a trough 51 of the centrifugal wall 203, at which features the curvature of this wall reverses.

The first lip 210 and the second lip 211 are joined together to ensure the continuity of the centrifugal wall 203. A first lip 210 of a first mixing motif 207a forms, with a second lip 211 of an adjacent second mixing motif 207b forming part of the same mixing element 205, because the first lip 210 of a first mixing motif 207a and the second lip 211 of an adjacent second mixing motif 207b are butted together.

The first lip 210 and the second lip 211 of the one same mixing motif 205 form between them a lip angle δ. The lip angle δ is preferably comprised between 0° and 90°, or even comprised between 0° and 20° and is measured between lips once they have been projected onto a plane of projection perpendicular to the axis of elongation A6 of the refrigerant homogenizing member 200.

The first edge 208 and/or the second edge 209 which delimits a mixing element 205, and a first lip 210 and/or a second lip 211 which delimits a mixing motif 207a, 207b, is formed of a crest 50 and a trough 51. Specifically, crest and trough each extend in a complementary half- section of the refrigerant homogenizing member 200 and are advantageously aligned. The crest 50 therefore extends along a radially extending straight line that begins on the axis of elongation A6, whereas the trough 51 extends along a radially extending straight line which begins on the axis of elongation A6. These two straight lines may be coincident.

In the case of Figures 7 to 11, the shapes of these mixing motifs 207a, 207b and their layout along the axis of elongation A6 of the shaft 202 make it possible to improve the homogenization of the refrigerant FR and make it possible to direct this refrigerant FR from a centre C of the refrigerant homogenizing member 200 towards the peripheral envelope 201 of the refrigerant homogenizing member 200.

In Figure 12, the refrigerant homogenizing member 200 comprises the shaft 202 to which at least two mixing motifs 207a and 207b are attached. The refrigerant homogenizing member 200 allows the liquid and gas phases that make up the refrigerant FR to be mixed together as it arrives inside the return tank 9. Thus, the refrigerant FR is homogenized when this refrigerant arrives at the core bundle of second tubes 10b. The shaft 202 and the mixing motifs 207a, 207b may be produced as a single piece which may advantageously be inserted into the return tank 9. When this single-piece component is sectioned along the axis of elongation A6, it is noticed that the mixing motifs 207a, 207b have U-shaped and V-shaped profiles alternating with one another along this axis of elongation A6.

The refrigerant homogenizing member 200 has mixing motifs 207a, 207b which are arranged in a U or in a V shape. First mixing motifs 207a have a U-shaped profile and are arranged in a first half-portion 213 of the refrigerant homogenizing member 200, whereas second mixing motifs 207b having a V-shaped profile are arranged in a half-portion 214 of the refrigerant homogenizing member 200. The first half-portion 213 therefore exhibits a succession of mixing motifs 207a arranged in a U-shape along the axis of elongation A6 of the shaft 202, whereas the second half-portion 214 exhibits a succession of second mixing motifs 207b arranged in a V-shape along this same axis of elongation A6 of the shaft 202. According to one embodiment of the present invention, the shaft 202 exhibiting the mixing motifs 207a, 207b may be arranged in such a way that its axis of elongation A6 is interposed between the two half-portions 213, 214. The mixing motifs 207a, 207b are opposed in relation to the shaft 202. In other words, at least one first mixing motif 207a, arranged in a U- shape, extends radially in a first angular sector 215 of the shaft 202 and at least one second motif 207b, arranged in a V-shape, extends radially in a second angular sector 216 and in an opposite direction in relation to a direction of radial extension of the first mixing motif 207a arranged in a U-shape. The result of this is an alternation of U-shaped first mixing motifs 207a and of V-shaped second mixing motifs 207b , along the axis of elongation A6 of the shaft 202.

The first angular sector 215 is centred on the shaft 202 and extends about the latter over an angle equal to 180°. The second angular sector 21 is centred on the shaft 202 and extends about the latter over an angle equal to 180°opposite the first angular sector 215.

According to one configuration of the present invention, at least two mixing motifs 207 emerge from at least two distinct longitudinal segments of the shaft 202 along its axis of elongation A6, and so, according to this configuration of the present invention, the U- shaped first mixing motifs 207a and the V-shaped second mixing motifs 207b do not overlap axially.

The shapes of these mixing motifs 207a, 207b and their layout along the axis of elongation A6 of the shaft 202, all as illustrated in Figure 12, make it possible to improve the homogenization of the refrigerant FR and make it possible to direct this refrigerant FR from a centre C of the refrigerant homogenizing member 200 towards the peripheral envelope 201 of the refrigerant homogenizing member 200. The alternation of the first mixing motifs 207a and of the second mixing motifs 207b extends from a first longitudinal end to a second longitudinal end of the shaft 202.

The alternation of the first and second mixing motifs 207a, 207b arranged respectively in a U-shape and in a V-shape gives rise to modifications of the cross section for the passage of the refrigerant FR along the axis of elongation A6 of the shaft 202, and this likewise contributes to improving the homogeneity of the refrigerant FR. This passage cross section is effectively reduced in the region of the U-shaped first mixing motifs as well as in the region of the V-shaped second mixing motifs, whereas it is larger between these mixing motifs 207a, 207b.

In addition, the refrigerant homogenizing member 200 makes it possible, thanks to all of its features, to improve the distribution of refrigerant FR in the core bundle of the second tubes 10b, whatever the distance separating them from the second refrigerant FR opening 17.

Whatever the embodiment selected, the refrigerant homogenizing member 200 according to the present invention can be formed from a synthetic material or from a metallic material.

The refrigerant homogenizing member 200 is, for example, thus produced from a method of obtaining it by moulding a polymer material. The refrigerant homogenizing member 200 is designed to be obtained by moulding without a relief angle. The refrigerant homogenizing member 200 is, for example, obtained using a mould comprising a first mould cavity and a second mould cavity which jointly form a moulding space identical in shape to the refrigerant homogenizing member 200.

For preference, the refrigerant homogenizing member 200 is a one-piece element combining the shaft 202, the centrifugal walls 203 and the mixing elements 205 in a single piece, which cannot be dismantled into several elements without destroying the refrigerant homogenizing member 200.

When the refrigerant homogenizing member 200 is made from a metallic material, it is appropriate to use a metal sheet made up of at least two layers of metals exhibiting different properties. In this particular instance, the metal sheet used comprises a core and at least one braze layer, advantageously two braze layers one on each side of the core. These two braze layers and the core of the metal sheet have different melting points, the braze layer or layers having a melting point lower than the melting point of the core. Thus, during a brazing operation, the components are heated until the melting point of the braze layer is reached, allowing the parts to be joined together without any alteration or mechanical deformation of the core. The metallic sheet or sheets used for forming the refrigerant homogenizing member 200 comprising the shaft 202 and the first and second mixing motifs 207a, 207b may be a sheet of aluminium or of an aluminium alloy, incorporating at least one braze layer, as described hereinabove.

Another advantage of the present invention lies in the process used for manufacturing it.

The shape of the refrigerant homogenizing member 200 effectively allows the creation of a mould and thus allows the parts to be mass-produced by injection moulding of plastic or by pressing, depending on the embodiment chosen. It is also conceivable to create a mould that allows the refrigerant homogenizing member 200 to be manufactured in various sizes so that they suit different types of heat exchanger 5. As a result, the profitability associated with producing these refrigerant homogenizing members 200 is improved, as is that of the elements in which these refrigerant homogenizing members 200 can be incorporated, particularly the heat exchanger 5.

The refrigerant homogenizing member 200 therefore makes it possible to improve the distribution of the refrigerant FR in the core bundle of the second tubes 10b of the heat exchanger 5 and thus to obtain a more readily controllable temperature within the interior of the vehicle comprising this heat exchanger 5. In addition, the shape of this refrigerant homogenizing member 200 makes it possible to conceive of mass-producing it, thanks to the manufacture of moulds of simple design.

According to an alternative form of embodiment, the refrigerant homogenizing member 200 may also be made from a porous material. In other words, the thickness and the length of this refrigerant homogenizing member 200 are formed by the porous material. It should be understood here that a porous material is notably a cellular material which allows an ordered or disordered diffusion and circulation of the refrigerant FR through the refrigerant homogenizing member 200. Thus, the cellular material has open cells, thereby offering a plurality of circulation pathways through the refrigerant homogenizing member 200. The porous material is, for example, a foam formed from metallic and/or synthetic fibres which delimit the refrigerant circulation pathways. The porous material is, again for example, an agglomerate formed of roughly ovoid or spherical granules which delimit the circulation pathways. The porous material may just as well be formed from a metallic, notably aluminium, material as from a ceramic material the elements of which are welded and/or bonded together. By way of further example, the porous material is a steel wool.

In Figure 13, the header tank 8 possibly houses a distribution homogenizing device 18. The distribution homogenizing device 18 notably comprises a pipe 19 extending along an axis of symmetry A7 which is parallel to, or even coincident with, the second axis of overall extension A2 and/or the fourth axis of overall extension A4, between a first terminal part 20 and a second terminal part 21 of the pipe 19.

It will be noted that any element that extends along the axis of symmetry A7 which is defined by the longest dimension of the pipe 19 is termed longitudinal. Any element that extends inside a transverse plane Pt which is orthogonal to the axis of symmetry A7 is termed transverse.

Referring more specifically to Figure 13, the first terminal part 20 is formed of one end of the pipe 19, whereas the second terminal part 21 is formed of the other end of the pipe 19, longitudinally opposite the first terminal part 20.

According to an alternative form of embodiment, the first terminal part 20 of the pipe 19 is intended to be placed in fluidic communication with the first opening 16 of the heat exchanger 5. According to another alternative form of embodiment, the first opening 16 houses the pipe 19 of which the first terminal part 20 is placed in fluidic communication with a pipeline of the refrigerant circuit 1. According to these two alternative forms, the second terminal part 21 is blind and forms a dead end with regards to the circulation of the refrigerant FR inside the pipe 19. The pipe 19 is, for example, shaped into a cylinder, or alternatively into a parallelepiped, or alternatively into any other shape formed around the axis of elongation A7. The pipe 19 comprises a peripheral wall 23 which is cylindrical in cross section when the pipe 19 is shaped into a cylinder, parallelepipedal in cross section when the pipe 19 is a parallelepiped. The peripheral wall 23 is the one that gives the pipe 19 its overall shape.

The peripheral wall 23 comprises orifices 22 which are formed through the peripheral wall 23 of the pipe 19. The orifices 22 are preferably aligned along an axis of alignment which is parallel to the axis of symmetry A7.

According to one alternative form, the orifices 22 are equidistant from one another. According to another alternative form, the orifices 22 are separated from one another by a variable distance. The orifices 22 are, for example, orifices of circular section, but could be of any shape, notably rectangular, elliptical, oblong.

The pipe 19 constitutes an enclosure which delimits an internal space 24 around which the pipe 19 is formed. In other words, the pipe 19 borders the internal space 24 that the pipe 19 surrounds. The peripheral wall 23 of the pipe 19 comprises an internal face which delimits the internal space 24, the internal face preferably being circular in cross section.

The pipe 19 houses a mixing member 25 which extends inside the internal space 24. The mixing member 25 is intended to encourage mixing between the liquid and gas phases of the refrigerant FR. The mixing member 25 is more particularly designed to direct the refrigerant FR towards the internal face of the pipe 19 so that this refrigerant strikes this pipe thereby increasing the mixing of the liquid and gas phases of the refrigerant. The mixing member 25 is also intended to duct at least some of the refrigerant the tubes 10a furthest away from the first opening 16. The mixing member 25 is able to exhibit any one of the features of the refrigerant homogenizing member 200 described above. That is to be understood as meaning that the mixing member 25 is in accordance with at least any one of the aforementioned features, such as overall or partial shape, geometric detail, dimension or arrangement of the refrigerant homogenizing member 200, or even with any one of the possible combinations of the features of the refrigerant homogenizing member 200 which have been set out hereinabove.

In other words, the mixing member 25 is identical to the refrigerant homogenizing member 200 which has just been described in its alternative forms or in any one of the combinations of these alternative forms. Reference may therefore be made to the detailed description of one of the embodiments of the refrigerant homogenizing member 200, which can be applied to the mixing member 25, in terms of its implementation, its installation and its technical effects. In general terms, the mixing member 25 is a member which generates a turbulent, notably centrifugal, flow of the refrigerant FR towards the internal face of the pipe 19. The mixing member 25 is also designed to disrupt a laminar flow of the refrigerant FR inside the pipe 19 so as to mix the liquid and gas phases of the refrigerant FR. In other words, the mixing member 25 forms at least one baffle and preferably a plurality of baffles impeding laminar flow of the refrigerant FR parallel to the axis of extension A7. In general terms, the mixing member 25 acts as an obstacle to the laminar flow of refrigerant FR inside the internal space 24.

It follows from these measures that the refrigerant FR, entering the heat exchanger 5, enters the internal space 24 of the pipe 19 via the first opening 16 formed through one terminal wall of the header tank 8. The refrigerant FR then spreads out inside the internal space 24, being mixed by the mixing member 25. This notably results in a mixing of the liquid and gas phases of the refrigerant FR, which is then homogenized longitudinally along the pipe 19. The refrigerant FR then uses the orifices 22 to flow out of the pipe 19 towards the first chamber 13. The refrigerant FR then flows through the core bundle of first tubes 10a, as described hereinabove, as far as the return tank 9. The refrigerant homogenizing device 200 stirs this refrigerant in order to mix its liquid and gas phases. The refrigerant thus mixed then circulates through the second tubes 10b to emerge into the second chamber 14 of the header tank 8. Finally, the refrigerant FR is discharged from the heat exchanger 5 through the second opening 17.

As the refrigerant FR is passing through the pipe 19 thus equipped with the mixing member 25, the refrigerant FR encounters multiple obstacles which also encourage mixing between its liquid and gas phases. In addition, such a pipe 19 encourages homogenization of the distribution of refrigerant FR within the tubes 10, 10a, 10b.

It will also be noted that the better the two, liquid and gas, phases of the refrigerant FR are mixed by the mixing member 25 inside the internal space 24 of the pipe 19, better and more homogeneously this refrigerant FR is sprayed as it passes through the orifices 22 in order thereafter to be supplied homogeneously to the core bundle of tubes 10, 10a, 10b. In other words, first of all, the mixing member 25 allows a longitudinal distribution of refrigerant FR which is homogeneous along the axis of symmetry A7, the spraying of the refrigerant FR through the orifices 22 being performed in a second phase, after the refrigerant FR has been homogenized in the internal space 24, this guaranteeing better homogeneous distribution of the refrigerant FR as it leaves the pipe 19 and, subsequently, inside the heat exchanger 5.

However, the invention is not restricted to the means and configurations described and illustrated herein and extends, likewise, to all equivalent means or configurations and to any technically operational combination of such means. In particular, the forms and disposition of the mixing elements 205 and/or of the mixing motifs 207a, 207b associated with the shaft 202 may be modified without detriment to the invention, in so far as they provide the functionalities described in the present document.

The embodiments that are described hereinabove are entirely nonlimiting; it will be possible, in particular, to imagine alternative forms of embodiment of the invention that comprise only a selection of the features described below, in isolation from the other features described in this document, if this selection of features is sufficient to confer a technical advantage or to distinguish the invention from the state of the art.