FR2894656A1 - Collector box for a heat exchanger in an air conditioner circuit, comprises a double-wall reservoir with inner and peripheral chambers for refrigerant fluid to be cooled and cooling fluid respectively - Google Patents

Abstract

A collector box (30) for a heat exchanger in an air conditioner circuit with refrigerant fluid, comprises a double-walled reservoir with an outer wall (32) and an inner wall (34) defining an inner chamber (36) and a peripheral chamber (38) separated by the internal partition (34), used respectively for the passage of fluid to be cooled and cooling fluid so as to constitute an internal heat exchanger integrated with the collector box. Independent claims are included for (1) a heat exchanger for an air conditioner circuit as above, comprising a bundle of heat exchanger tubes (40) and at least one collector box as described above (2) an air conditioner circuit with a heat exchanger as above .

Description

Advanced manifold for a circuit heat exchanger

  The invention relates to the field of heat exchangers, in particular for motor vehicles.

  It relates more particularly to an improved header box 10 for a heat exchanger, in particular a gas cooler, of an air conditioning circuit.

  It is known that in an air-conditioning circuit operating with a refrigerant constituted by a natural gas such as carbon dioxide (CO2), this fluid remains essentially in the gaseous state and can reach particularly high operating pressures and temperatures. . Such a circuit has a heat exchanger, called a gas cooler, which replaces the condenser used in conventional air conditioning circuits where the coolant is present in the gas phase and in the liquid phase. Such a circuit essentially comprises a compressor, a gas cooler, an expander and an evaporator 25 traversed in this order by the gaseous cooling fluid. In addition, such a circuit comprises an internal exchanger comprising a first branch through which the refrigerant flowing from the gas cooler (coolant to be cooled) and a second branch through which the refrigerant flowing from the evaporator (coolant coolant) passes. .5 The gas cooler comprises, in a conventional manner, a bundle of tubes mounted between two collecting boxes

  On the other hand, the internal heat exchanger is embodied as a separate component which has circulation channels for the coolant to be cooled and circulation channels for the cooling coolant. Thus, in this internal heat exchanger, the refrigerant exchanges heat with itself.

  The invention particularly aims to simplify the realization of such an air conditioning circuit.

  It also aims to provide such a circuit grouping several components in a single component.

  The invention proposes for this purpose a manifold of a heat exchanger for an air conditioning circuit 20 traversed by a refrigerant.

  According to the invention, the manifold is a double-walled tank having an outer wall and an inner wall for delimiting an inner chamber and a peripheral chamber separated by the inner wall and adapted to be traversed by the refrigerant fluid. cool and the other by the same coolant coolant, so as to form an internal heat exchanger integrated in the manifold. Thus, the two circulation branches of the internal heat exchanger are formed by the inner chamber and the peripheral chamber delimited both in the header box of the heat exchanger.

  This makes it possible to simplify the circuit construction, to reduce its size, and to further limit the risk of leakage.

  In a preferred embodiment, the inner chamber and the peripheral chamber are adapted to be traversed respectively by the coolant to be cooled and by the cooling coolant. In this case, the heat exchanger comprises tubes which pass through both the outer wall and the inner wall to open into the inner chamber. This makes it possible to increase the brazed surface between the tubes and the header box thus limiting the deformations undergone by the ends of the tubes, which are traversed by a fluid under high pressure. This also results in an improvement in the mechanical strength and fatigue resistance of the heat exchanger.

  It is conceivable also to provide a reverse arrangement, that is to say in which the inner chamber and the peripheral chamber would be traversed respectively by the coolant coolant and the coolant to be cooled.

  According to another characteristic of the invention, spacers are arranged between the inner wall and the outer wall to divide the peripheral chamber into several parallel channels for circulating the refrigerant fluid.

  Other complementary and / or alternative features of the invention are indicated below. - The outer wall and the inner wall have different thicknesses, the thickness of the outer wall being greater than the thickness of the inner wall.

  The outer wall and the inner wall are cylindrical walls of circular section, arranged concentrically.

  - The outer wall and the inner wall are cylindrical walls of evolutionary section. - The manifold includes two end walls clean closing the inner chamber at both ends.

  20 - The manifold comprises two end rings adapted to close the peripheral chamber at both ends.

  The collection box comprises at least one connecting block adapted to be arranged against the outer wall and having an opening adapted to open into the peripheral chamber to establish a fluid communication with the latter.

  The collection box comprises at least one connection block adapted to be arranged against the outer wall and having an opening adapted to open into the inner chamber to establish a fluid communication with the latter. The connection block has a clean opening to open into the peripheral chamber and an opening capable of opening into the inner chamber. -The opening is delimited by a pipe made in one piece with the connection block. - The connection block includes an insert opening into the inner chamber.

  In another aspect, the invention relates to a heat exchanger, in particular a gas cooler, for an air-conditioning circuit traversed by a refrigerant fluid, comprising a bundle of heat exchange tubes and at least one collecting box such as than previously defined. The invention also relates to an air conditioning circuit comprising a heat exchanger as defined above.

  In the description which follows, given by way of example only, reference is made to the accompanying drawings, in which:

  FIG. 1 schematically represents an air conditioning circuit operating with a refrigerant fluid of the CO2 type and comprising a gas cooler and an internal heat exchanger; FIG. 2 is a partial sectional view of a header box of a gas cooler according to the invention, also showing part of a tube opening into the header box; FIGS. 3 and 4 are two schematic diagrams of an air conditioning circuit comprising a gas cooler with at least one header box according to the invention; Figure 5 is a sectional view of a header box according to the invention; - Figure 6 is another sectional view of a header box according to the invention; - Figure 7 is a sectional view similar to Figure 5, taken along the line VII-VII of Figure 8, further showing a tube opening into the inner chamber; Figure 8 is a sectional view along the line VIII-VIII of Figure 7; FIG 9 is a front view of a double connection block according to the invention; FIG. 10 is a front view of a simple connection block according to the invention; FIG. 11 is an enlarged sectional view along the line XI-XI of FIG. 9 or FIG. 10; - Figure 12 is a sectional view, on a larger scale, along the line XII-XII of Figure 9; FIG. 13 is a sectional view of a manifold and connection block according to the invention in an alternative embodiment; - Figure 14 is another sectional view of a similar manifold in another embodiment; FIG. 15 is a representation of the insert of the connection block of FIG. 14; Figure 16 is another sectional view of a manifold and a splice block in another embodiment of the invention; FIG. 17 is a sectional view of a header box whose walls have a cylindrical shape with a progressive section; and - Figure 18 is a view similar to Figure 17 in an alternative embodiment.

  Referring first to Figure 1 which shows an air conditioning circuit 10 traversed by a gaseous refrigerant such as carbon dioxide (CO2) operating in the supercritical state. This means that this fluid remains essentially in the gaseous state during the entire operating cycle. The circuit 10 comprises a compressor 12 capable of compressing the coolant and sending it into a heat exchanger, namely a gas cooler 14, where the hot and high-pressure coolant is cooled in part by a flow. air as represented by the arrow Fi. At the outlet of the gas cooler 14, the refrigerant passes through an internal heat exchanger 16 and more particularly a branch 18 of the latter to then gain a pressure reducer 20.

  At the outlet of the regulator, the refrigerant then passes through an evaporator 22 swept by a flow of air, as represented by the arrow F2, which makes it possible to produce a flow of conditioned air to be sent for example into the passenger compartment. a motor vehicle. At the outlet of the evaporator 22, the fluid gains a reservoir 24, also called a bottle, to then gain a second branch 26 of the internal exchanger 16 and return to the compressor 12 to perform a new cycle of operation, and thus to after. In the internal heat exchanger 16, the hot and high pressure refrigerant fluid that passes through the branch 18 exchanges heat with the same refrigerant fluid at a lower temperature and lower pressure which circulates in the branch 26. In other words, the branch 18 is traversed by a coolant to be cooled, while the branch 26 is traversed by a coolant coolant. In the previously known solutions, the cooler 14 and the internal heat exchanger 16 are separate components.

  Referring now to Figure 2 which shows a portion of a gas cooler 28 according to the invention which incorporates an internal heat exchanger. The gas cooler 28 comprises a manifold 30 constituted by a double-walled tank, in the example of generally cylindrical shape, having an outer wall 32 and an inner wall 34. In the example, the walls 32 and 34 are cylindrical walls of circular section, arranged concentrically. These two walls make it possible to limit an inner chamber 36 and a peripheral chamber 38 which are separated from one another by the inner wall 34 and which are adapted to be traversed by the coolant to be cooled and the other by the cooling coolant. which makes it possible to constitute an internal heat exchanger integrated directly into the header box 30.

  In the example shown, the inner chamber 36 and the peripheral chamber 38 are respectively traversed by the coolant to be cooled and by the coolant coolant.

  The gas cooler 28 further comprises a beam formed of a multiplicity of tubes 40 having respective ends 42 which successively pass through the outer wall 32 and the inner wall 34 to open into the inner chamber 36. A fluid communication is thus permitted. between the tubes 40 of the bundle and the inner chamber 36, which corresponds to the first branch 18 of the internal heat exchanger 16 of FIG. 1. In the example shown, the tubes 40 are flat tubes having a cross section of general shape rectangular and having a multiplicity of parallel internal channels (not shown in the drawing). The end of the tube 42 is twisted or twisted at 90 relative to the body of the tube as seen in FIG.

  In an alternative embodiment (not shown), the ends 42 of the tubes 40 could open in the peripheral chamber 38 and not in the inner chamber 36, the fluid to be cooled, that is to say the fluid under high pressure, circulating then in the peripheral chamber 38 and the coolant fluid then flowing in the inner chamber 36.

  Furthermore, as seen in Figure 2, spacers 44 are disposed between the inner wall 34 and the outer wall 32 to divide the peripheral chamber 38 into a plurality of parallel channels 46 for the circulation of the refrigerant. Fluid communication is established between the channels 46 by machining (not shown) made at selected locations in the spacers 44.

  Referring now to Figure 3 which shows schematically an air conditioning circuit comprising a gas cooler 28 according to the invention having two manifolds 30 into which open respectively the tubes (not shown) of the beam.

  In the example, each of the manifolds 30 integrates an internal heat exchanger and is crossed on the one hand by the coolant to be cooled and on the other hand by the coolant coolant that comes from the evaporator 22. In this first for example, the coolant coolant from the evaporator 22 gains a first manifold 30 (that on the right side of Figure 3) by a pipe 48 and then gains the second manifold 30 (the one on the left side of Figure 3) by a second pipe 50 before returning to the compressor 12 by a third pipe 52.

  In the alternative embodiment of Figure 4, the pipe 48 is divided into two branches 48-1 and 48-2 which respectively feed the manifolds located on the right side and the left side of Figure 4. At the outlet of the manifolds 30 , the refrigerant reaches the compressor 12 via a pipe 52. Reference is now made to FIG. 5, which shows, in more detail, a manifold 30 similar to that of FIG. 2. It can be seen that the outer wall 32 and the inner wall 34 have different thicknesses. In this case, the thickness of the outer wall is greater than the thickness of the inner wall, and this to provide a better resistance to pressure.

  The inner chamber 36 is traversed by the refrigerant whose pressure may be, for example, of the order of 115 bar and the temperature between 35 C and 135 C. In contrast, the peripheral chamber 38 is traversed by the same fluid refrigerant coolant, whose pressure is of the order of 40 bars and the temperature between 5 C and 38 C. These values are given for information only and may vary widely in practice.

  The inner wall 34 has an inner diameter d1 and an outer diameter d2 and a thickness e = (d2-d1) / 2, while the outer wall 32 has an inner diameter D1 and an outer diameter D2 and a thickness E = (D2 -dl) / 2. In an exemplary embodiment, the dimensions are as follows. dl = 7 mm d2 = 8 mm e = 0.5 mm D1 = 12 mm D2 = 18 mm E = 3 mm In this example, the thickness of the outer wall is thus six times that of the inner wall.

  As seen in Figure 5, the manifold 30 further comprises a plurality of passages 54 arranged radially to allow each time the insertion of an end 42 of a tube 40 (see Figure 2). In the embodiment shown, the manifold 30 has four spacers 44, one of which is arranged to define the passages 54 above.

  As can be seen from FIGS. 2 and 5, because the ends 42 of the tubes pass through both the walls 32 and 34, the contact area between the tubes and the manifold 30 is increased, which allows a good connection by brazing. This also limits the deformation of the ends 42 of the tubes under the effect of pressure, resulting in a better mechanical strength and fatigue of the heat exchanger.

  In the embodiment of Figure 6, the manifold 30 has an enlarged passage 56 adapted to receive a manifold 58 into which the respective ends 42 of the tubes of the beam. In the drawing, the manifold 58 is shown in a position before insertion into the passage 56.

  FIG. 7, which is a sectional view along the line VII-VII of FIG. 8, shows the manifold 30 of FIG. 5 with one of the tubes 40 whose end 42 is engaged in a passage 54.

  Referring now to Figure 8 which is a sectional view along the line VIII-VIII of Figure 7. At each end of the manifold 40 the inner chamber 36 and the peripheral chamber 38 are closed.

  Two end walls 60, only one of which is visible in FIG. 8, are suitable for closing the inner chamber 36 at its two ends. These two end walls can be made for example in the form of metal plugs which are brazed inside the inner wall 34. The manifold further comprises two end rings 62 (only one of which is visible on the Figure 8) to close the peripheral chamber at both ends.

  On the section of Figure 8, there are two successive tubes 40 whose respective ends 42 are twisted at 90 so that their longitudinal direction coincides with the axial direction of the manifold. These two ends 42 are arranged contiguously.

  Between the respective bodies of the tubes are corrugated spacers 64 forming heat exchange fins. The respective undulations of these spacers are brazed each time on the bodies of the tubes, in a manner known per se.

  Referring now to Figure 9 which shows a connection block 66 adapted to be disposed against the outer wall 32 of the manifold. This connection block is of parallelepipedal general shape and has a first opening 68 capable of opening into the peripheral chamber 38 (FIG. 11) and a second opening 70 able to open into the internal chamber 36 in order to establish a fluid communication with the latter. . The opening 68 is delimited by a tubing 72 (FIGS. 9 and 11) which passes through the outer wall 32 to open into the peripheral chamber 38, here in a region opposite to that of the tubes 40. The connection block 66 comprises two opposite walls. 74 which fit closely around the outer wall 32 to allow a sealed connection by soldering. The connection block 66 has an inner end 76 for connecting a suitable conduit (not shown). The tubing 72 thus allows the entry or the exit of the cooling coolant fluid, that is to say at low pressure.

  On the outer wall 32 of the manifold is provided another connection block 78 (Figure 10) which comprises a single tube 72 similar to that of Figure 9 and thus defining an opening 68. Thus, the tubing 72 of the block 66 and the tubing 72 of the block 78 serve one for admission and the other for the discharge of the refrigerant fluid at low pressure.

  As can be seen in FIGS. 11 and 12, the high pressure coolant, which is to be cooled, enters the inner chamber 36 via the tubes 40 as represented by the arrows F3. After heat exchange, this fluid must be evacuated through the opening 70 of the connection block 66 (FIGS. 9 and 12). This opening 70 is delimited by a pipe 80 which successively passes through the outer wall 32 and the inner wall 34 to open into the inner chamber 36. Also seen in the section of FIG. 12 are the two lateral walls 74 of the connection block 66 which come close to the outer shape of the collector box. A tip 82 allows the connection of a tubing (not shown) for the discharge of the high-pressure refrigerant from the inner chamber 36.

  Therefore, the outer wall of the manifold 40 receives on the one hand the connection block 66, which allows a double connection, and the connection block 78 which allows a simple connection. In the embodiment of Figures 9 to 12, the opening 68 or 70 is delimited respectively by a tubing 72 or 80 which is formed in one piece with the connecting block 66 or 78, as appropriate.

  However, other embodiments are possible.

  Thus, in the embodiment of FIG. 13, the outer wall 32 is arranged to define a base 84 providing a flat surface of generally rectangular shape 25 for receiving the connection block 78. An insert 86 made for example by stamping, comprises a collar 88 inserted between the base 84 and the connection block 78 and a pipe 90 which successively passes through the wall 32 and the wall 34 of the header box 30 to open into the inner chamber 36. This insert can be stamped, brazed on both sides on the base 84 of the manifold and on the connection block 78, or else glued on the base 84 and the connection block 78. The insert may for example be tightly tightened through the wall internal cylindrical 34 of the manifold 40.

  Furthermore, the connection blocks 66 and 78 may be brazed or bonded to the outer wall 32 of the header.

  In the variant embodiment of FIGS. 14 and 15, an insert 92 is disposed between the walls 32 and 34 in alignment with the opening 70, which makes it possible to avoid the presence of a tube passing successively through the two walls. More particularly, the insert 92 is placed between a circular opening 94 of the outer wall 32 and a circular opening 96. The insert is shown alone in FIG.

  This insert 92 can also be stamped and punched, assembled with the manifold, then brazed on both sides on the concentric walls 32 and 34. Alternatively, the insert can be stamped, assembled on the collector, perforated and then brazed on both sides on the concentric walls.

  In the embodiment of FIG. 16, the opening 68 of the connection block 66 or 78 emerges directly opposite a circular opening 98 formed in the thickness of the outer wall 32 to open directly into the peripheral chamber 38. This allows, by analogy with the embodiment of FIGS. 14 and 15, to avoid the use of a tubing (tubing 72 of FIGS. 9, 10 and 11) passing through the thickness of the outer wall 32.

  It will be understood that various embodiments are possible to allow the connection of the air conditioning circuit with the inner chamber 36 or the peripheral chamber 38.

  Figure 17 shows a sectional view of a manifold 30, shown schematically, and wherein the outer wall 32 and the inner wall 34 10 are cylindrical walls of evolutive section, so non-circular. For example, the inner wall 34 may be of circular section and the outer wall 32 of oval or ovoid shape, which makes it possible to limit the deformation of the manifold under the effect of the pressure and thus the level of the resistance under voltage.

  In the embodiment of Fig. 17, the manifold includes passages 54 similar to those previously described (Fig. 5) for inserting the ends of the tubes. As a result, the manifold plays both the role of tank and collector.

  In the embodiment of FIG. 18, which is similar to that of FIG. 17, the manifold comprises a passage 56 similar to that of FIG. 6 for the reception of a manifold 58 which, itself, receives the ends 42 of the tubes of the bundle.

  The invention thus makes it possible to simplify the production of the air-conditioning circuit by the fact that the internal heat exchanger is integrated in at least one of the two collector boxes of a heat exchanger, in particular a heat exchanger. gas.

  The invention also relates to the heat exchangers 5 thus obtained and the air conditioning circuits which comprise them.

  The invention has particular application to heat exchangers for motor vehicles and in particular to gas coolers for air conditioning circuits.

Claims (16)

claims   A heat exchanger collector box for an air-conditioning circuit traversed by a refrigerant, characterized in that the collector box (30) is a double-walled tank having an outer wall (32) and an inner wall (34). ) to delimit an inner chamber (36) and a peripheral chamber (38) separated by the inner wall (34) and adapted to be traversed by the cooling fluid to be cooled and the other by the same refrigerant coolant so to form an internal heat exchanger integrated in the manifold.   2. header box according to claim 1, characterized in that the inner chamber (36) and the peripheral chamber (38) are adapted to be traversed respectively by the coolant to be cooled and by the cooling coolant, the heat exchanger comprising tubes (40) passing through the outer wall (32) and the inner wall (34) to open into the inner chamber (36).   3. header box according to one of claims 1 and 2, characterized in that spacers (44) are arranged between the outer wall (32) and the inner wall (34) to divide the peripheral chamber (38) into several channels parallel (46) circulation of the refrigerant.   4. header box according to one of claims 1 to 3, characterized in that the outer wall (32) and the inner wall 19 (34) have different thicknesses, the thickness of the outer wall (32) being greater than 1 thickness of the inner wall (34).   5. header box according to one of claims 1 to 4, characterized in that the outer wall (32) and the inner wall (34) are cylindrical walls of circular section, arranged concentrically.   6. header box according to one of claims 1 to 4, characterized in that the outer wall (32) and the inner wall (34) are cylindrical walls of evolutive section.   7. collector box according to one of claims 1 to 6, characterized in that it comprises two end walls (60) adapted to close the inner chamber (36) at its two ends.   8. header box according to one of claims 1 to 7, characterized in that it comprises two end rings (62) adapted to close the peripheral chamber (38) at both ends.   9. header box according to one of claims 1 to 8, characterized in that it comprises at least one connecting block (66; 78) adapted to be disposed against the outer wall (32) and having an opening (68). adapted to open into the peripheral chamber (38) for establishing a fluid communication with the latter.   10. header box according to one of claims 1 to 9, characterized in that it comprises at least one block of connection (78) adapted to be arranged against the outer wall (32) and having an opening (70) clean to unclog in the inner chamber (36) to establish a fluid communication therewith.   Container according to claims 9 and 10, characterized in that the connection block (66) has an opening (68) suitable for opening into the peripheral chamber (38) and an opening (70) capable of opening into the chamber interior (36).   12. header box according to one of claims 9 to 11, characterized in that the opening (68, 70) is delimited by a pipe (72, 80) formed integrally with the connection block.   Container according to claim 10, characterized in that the connection block (78) comprises an insert (86; 92) opening into the inner chamber (36).   14. Heat exchanger for an air-conditioning circuit traversed by a refrigerant, characterized in that it comprises a bundle of heat exchange tubes (40) and at least one header (30) according to one of claims 1 at 13.   15. Heat exchanger according to claim 14, characterized in that it is in the form of a gas cooler.   16. An air conditioning circuit comprising a heat exchanger according to one of claims 14 and 15.