FR2860288A1 - CIRCUIT ELEMENT FOR HEAT EXCHANGER, AND HEAT EXCHANGER THUS OBTAINED - Google Patents

Abstract

The invention provides a hydraulic circuit element (20) for heat exchange between a first fluid and a second fluid, which defines a path for the first fluid. The circuit element comprises at least one tube (22) having at least one open end and a tip (24). The tip (24) comprises a bottom which closes the end and a side wall which surrounds the tube in the vicinity of the end. The side wall has at least one opening (28b) in communication with a lateral opening (220) of the tube to help define the path of the first fluid. The side wall of the nozzle (24) is tightly applied to the tube (22) over its entire surface.

Description

VTM1494.FRD

  Circuit element for heat exchanger, and heat exchanger thus obtained.

  The invention relates to a circuit element for a heat exchanger, in particular a heat exchanger for the equipment of a motor vehicle.

  More specifically, it relates to a circuit element for heat exchange between a first fluid and a second fluid, defining a path for the first fluid.

  It also relates to heat exchangers obtained from these circuit elements, and more particularly to heat exchangers capable of withstanding high pressures.

  Such exchangers commonly consist of a bundle of parallel tubes mounted between two manifolds, the tubes alternating with interleaves for example corrugated type. Exchangers consisting of a single tube folded in the form of a coil are also known. These exchangers have many applications and can especially be used as condensers in motor vehicle air conditioning systems or as oil coolers.

  However, these known exchangers have many disadvantages. With regard to the technology of tube and collector exchangers, the latter increase the size of the exchangers without increasing their performance. The collector boxes do not make it possible to improve the heat exchange and cause a loss of space.

  On the other hand, the heat exchanger must be rectangular in shape because of the presence of the collector boxes. In addition, to create passes in the exchanger, it is necessary to add and integrate additional parts, the partitions, into the collector boxes.

  The manufacture of these exchangers is also difficult because it is necessary to punch and pop the collector plates. It is difficult to put thin tubes into a large collector with low tolerances. The manufacture of these exchangers is more expensive because the components are made by machining material.

  The coil exchangers do not allow passes to be made. Their manufacture is long because it is difficult to industrialize. It takes a long time to make a coil with a machine. As a result, heat exchangers made with this technology have a higher cost price than tube and collector heat exchangers.

  US 6196304 A proposes a heat exchanger comprising a stack of circuit elements. Each circuit element has a tube and two spacers that overlap the ends of the tubes. The ends of each tube are previously crushed and welded so that the fluid that passes through each tube can enter or exit only through transverse openings made in end regions of the tube, and not by the closed ends of the tube. Each spacer element is obtained from a folded sheet metal strip to form two branches. The branches of each spacer may comprise a transverse passage shaped to face the opening of the tube in the corresponding end zone, which forms a communication passage.

  The first fluid can flow from a given tube to an adjacent tube through this communication passage.

  The spacer members that overlap the ends of a given tube are in contact with the spacer members that overlap the ends of the adjacent tubes, and thereby provide a gap between two adjacent tubes to form a passage for the second fluid. This spacing also makes it possible to place an interlayer in the passage duct to improve the heat exchange.

  This structure does not have the aforementioned drawbacks of the commutator or coil exchangers. However, it is expensive because of the need to crush and solder the ends of the tube. Furthermore, the spacers do not allow to use an open-ended tube to the extent that they are not intended to prevent the first fluid to escape in the axial direction of the tube.

  FR 2834336 A proposes an exchanger also comprising a stack of circuit elements. Each circuit element has at least one tube and at least one endpiece at one end of the tube. The tip comprises at least one communication passage that defines the path of a first fluid. This tip does not have the drawbacks of the spacer element proposed by US 6196304 A, in that it comprises a bottom to prevent the fluid from escaping in the axial direction of the tube, which allows the use a tube having open ends (i.e., not crushed and not welded).

  However, each endpiece according to FR 2834336 A comprises at least one generally frustoconical boss. The bosses opposite two adjacent circuit elements are in abutment and thus define the spacing between two adjacent tubes. As a result, the pitch between two adjacent tubes of the exchanger is increased by the presence of the bosses, and the performance of the exchanger is not optimal. In addition, such an exchanger is not very resistant to high pressures because the bosses can be deformed.

  The present invention relates to a hydraulic circuit element for a heat exchanger that overcomes these disadvantages known from the prior art.

  For this purpose, the invention proposes a hydraulic circuit element 40 for the exchange of heat between a first fluid and a second fluid, defining a path for the first fluid. The circuit element comprises at least one tube having at least one open end and a tip, the tip comprising a bottom closing said end and a side wall surrounding the tube adjacent said end. The side wall has at least one opening in communication with a lateral opening of the. tube to help define the path of the first fluid. Advantageously, the side wall of the nozzle is tightly applied to the tube over its entire surface.

  Optional features of the circuit element according to the invention, complementary or substitution, are set out below: each tip consists of a sheet metal strip stamped to form the bottom and folded to form two branches, the side wall including the branches.

  - The two branches of each tip are of equal length.

  The two branches of each end are of unequal length.

  - The branches have a generally flat surface.

  - The said tube or tubes are generally flat.

  each tube has multiple channels. The circuit element comprises a single tube having a terminal end at each of its ends.

  The circuit element consists of several tubes, an intermediate nozzle being present between two successive tubes.

  - The circuit element has a rectilinear shape.

  - The circuit element has a broken general shape.

  The invention further proposes a heat exchanger, in particular for a motor vehicle, comprising a stack of circuit elements according to one of the preceding characteristics communicating with each other via the openings of the end pieces to allow passage of the first fluid. between the circuit elements.

  Optional features of the heat exchanger according to the invention, complementary or substitution, are set out below: The circuit elements come into contact with the branches of their respective ends when they are stacked, so that the branches of a circuit element rest on the branches of the adjacent circuit elements.

  The heat exchanger contains a coolant as the first fluid and the coolant as a second fluid.

  - The heat exchanger contains a refrigerant fluid as a first fluid and as a second fluid.

  - Said refrigerant is the fluid R744.

  The heat exchanger contains the oil as the first fluid and the coolant as the second fluid.

  The Ptube pitch which separates the respective tubes from two adjacent circuit elements is equal to 2 * branch + tube, where branch means the thickness of a branch of a fitting and tube means the thickness of the tube.

  - The heat exchanger has two side plates brazed on the stack of circuit elements.

  - The exchanger comprises an outer casing in which is arranged the stack of circuit elements.

  The outer casing consists of casing elements 5 brazed together.

  - The housing elements comprise half-shells, and two covers welded to the ends formed by the half-shells.

  - The outer housing is a plastic molded part in which is placed the stack of soldered circuit elements.

  - The heat exchanger comprises a turbulator arranged in the space defined by two adjacent circuit elements.

  Other features and advantages of the invention will be apparent from the following detailed description, and the accompanying drawings in which: - Figure 1 is a view of a tube and collector heat exchanger according to the prior art; FIG. 2 is a view of a coil heat exchanger according to the prior art; FIG. 3 is a perspective view of an exchanger according to the present invention; FIG. 4a is a partial perspective view of the right portion of the exchanger shown in FIG. 3; Figure 4b is a perspective view of a circuit element of the exchanger shown in Figure 3; - Figures 5 to 7 are various views which show folding steps of a sheet metal strip to form a nozzle according to the invention; FIG. 8a is a perspective view of the end of an exemplary tube comprising a communication opening; Figure 8b is a longitudinal sectional view of the end of a circuit element according to the invention; - Figures 9 and 10 are various views which show folding steps of a sheet metal strip to form a tip having branches of unequal lengths; - Figures 11 to 13 are partial perspective views of an exchanger according to the present invention; FIGS. 14 to 16 are perspective views of an exchanger according to a first embodiment of the invention; FIGS. 17 to 19 are perspective views of an exchanger according to a second embodiment of the invention; and Figures 20 and 21 are perspective views of alternative tubes.

  The drawings contain, for the most part, elements of a certain character. They can therefore not only serve to better understand the description, but also contribute to the definition of the invention, if any.

  There is shown in Figure 1 a conventional type heat exchanger comprising a bundle of flat tubes interposed between two manifolds. The beam 2 is formed of a multiplicity of flat tubes 4 arranged parallel to each other and alternating with corrugated inserts 6. These spacers are formed from a metal strip which is deformed to form corrugations. An interlayer 6 is disposed between two adjacent tubes 4 and comes into respective contact with these two tubes 4 by end regions of the corrugations.

  The tubes 4 of the bundle are inserted, at each of their ends, in openings made in collector plates 8, also called collectors. The collector plates 8 are closed by a cover 9 to form collector boxes 10, for example coolant or air boxes.

  To allow the mounting of the tubes 4 it is necessary to punch the collector plates 8 and / or to burst them. The mounting of the tubes is not an easy operation.

  The presence of the manifolds 10 increases the size of the exchanger without increasing its performance.

  To create passes in the exchanger, it is necessary to integrate partitions 12 which divide the manifolds 10 into separate chambers.

  There is shown in Figure 2 another known type of exchanger, namely a coil heat exchanger. The exchanger consists of a single tube 14 folded in the form of a coil. Corrugated spacers 6 may be arranged between the back and forth of the coil. A heat exchanger of this type is simpler than the tube and collector heat exchanger shown in Figure 1. It has fewer parts. However the industrialization of its manufacture is delicate and in total, a coil heat exchanger is more expensive to manufacture than a tube and collector heat exchanger. In addition, an exchanger of this type can not be arranged to include passes.

  The exchangers described above must be further reinforced for use with fluids at high pressure, especially pressures above 100 bar. This reinforcement is often achieved by components obtained by machining material (for example collector boxes), which is expensive.

  FIG. 3 shows an external perspective view of a heat exchanger according to the present invention and in FIG. 4 a sectional view of the right part.

  The heat exchanger consists of stacked circuit elements.

  Figure 4b shows a circuit element according to the invention. Each circuit element 20 consists of a tube 22 having two "open" ends, that is to say which allow the entry of fluid into the tube or the outlet of the fluid coming from the tube. As will be described later, a circuit element may comprise several tubes.

  In the example of FIGS. 3 and 4b, a tip 24 is attached to each open end of the tube 22.

  Each tip 24 includes a side wall which surrounds the tube on an end portion which is located adjacent the associated open end. The side wall is closely supported on the tube 22 over its entire surface, in particular to prevent swelling of the tube when the first fluid reaches high pressures.

  In a particular embodiment, each endpiece consists of a sheet metal strip stamped and folded to form a bottom 42 and two branches 31 of generally flat surface and without boss, shown in Figure 4b. The lateral part of the tip 24 is constituted by the two branches 31. The manufacture of a stamped part is not expensive, and therefore the use of a nozzle according to the invention reduces the manufacturing costs. The remainder of the description will be made with reference to this particular embodiment, by way of non-limiting example.

  The bottom 42 closes the corresponding end of the tube to prevent the fluid from escaping in the axial direction of the corresponding tube.

  Figure 3 does not show the delimitation between the upper branch and the lower branch, and the bottom of the tip for clarity and to simplify the representation of the general structure of the invention.

  The circuit elements are shaped such that, when stacked, the lower (respectively upper) branch of a tip of a circuit element 20 bears with the upper (respectively lower) branch of the element. adjacent circuit.

  As a result, the various circuit elements 20 which constitute the exchanger shown in Figure 3 are supported on each other via the generally flat branches of their respective ends.

  In FR 2834336 A, the surface of the branches comprises an outwardly frustoconical boss and the bosses facing two adjacent circuit elements are supported.

  Thus, the contact area between two adjacent circuit elements according to the present invention is greater than in FR 2834336 A. The side wall of each nozzle has at least one opening which communicates with a lateral opening of the associated tube 22.

  In particular, a branch 31 of a tip 24 may be full, that is to say have no opening. In this case, it does not allow the passage of the first fluid. In contrast, a branch 31 of a tip 24 may include an opening that allows the passage of the first fluid.

  In FIG. 3, the closed branches are shown schematically by a small hatched circle 28a, and the perforated branches, allowing the passage of the first fluid, by a small circle 28b without hatching. These small circles 28a and 28b are connected to the corresponding branch by a dotted line for clarity.

  In Figure 4a, the opening 28b of the branch of a tip 24 is represented by a small unhatched rectangle while the absence of opening of the branch of a tip is designated by a small hatched rectangle. The lateral openings of the tube are designated 220.

  In Figure 4b, the openings of the end pieces and the tube are not shown for clarity.

  Each tube 22 has been assembled with its respective ends 24, beforehand. The ends of each tube allow the passage of the first fluid through the openings 28b of the branches and corresponding openings 220 of the tubes. They also make it possible to retain the fluid that can escape from the tube, thanks to the bottom 42 shown in FIGS. 4a and 4b.

  The surface of the branches 31 is tightly applied to the tube, which allows in particular to keep it tight. In the example shown in perspective in FIG. 3 and in partial perspective view in FIG. 4a, the first fluid enters the exchanger in the upper right portion of the exchanger, as shown by the arrow 30. located opposite the inlet of the fluid in the exchanger being closed (closed bottom 28a), the first fluid moves from right to left (arrow 32) and runs through the upper tube 22 of the exchanger. The fluid reaches the nozzle 24 located in the left part (according to Figure 3) of the upper tube 22 of the exchanger. The upper branch is closed (28a), while the lower branch of the nozzle 24 has an opening (28b).

  The fluid can thus pass from the upper circuit element 20 to the immediately lower circuit element, as shown schematically by the arrow 34. The first fluid then flows through the second circuit element 20 from left to right according to FIGS. At the right end of the second circuit element 20, it passes into the lower circuit element (arrow 36) through the openings 28b provided in the branches of the adjacent ends, as previously described.

  The fluid thus makes a series of trips back and forth in the tubes of the circuit elements from right to left and from left to right, exactly as in a coil heat exchanger of the type shown in FIG. 2. The first fluid leaves the exchanger in the left part of the latter, as schematized by the arrow 38.

  During its alternative path in the tubes 22 of the exchanger, the first fluid is in heat exchange relation with a second fluid which circulates between the tubes in the axial direction of the tubes 22.

  The absence of boss on the surface of the tips 24 decreases the risk of deformation at the contacts between the tubes, when the first fluid reaches high pressures.

  The circuit elements according to the invention also make it possible to reduce the pitch between the adjacent tubes in the exchanger, with respect to the circuit elements provided with bosses of FR 2834336 A. The Ptube pitch between the adjacent tubes is given by the relation next: Ptube = 2 * ebranche + etube, where ebranche denotes the thickness of a tip branch and tube, the thickness of the tube.

  In prior art collector plate heat exchangers, it is difficult to reduce the pitch between two adjacent tubes. However, such a step reduction makes it possible to place more tubes in an exchanger having a given size, and therefore to increase the thermal performance of the exchanger while reducing the pressure losses in the exchanger.

  Thus, a heat exchanger 40 has been made in a simple manner that makes it possible to exchange heat between a first high-pressure fluid and a second low-pressure fluid, especially the engine coolant or a heat exchange between a first high-pressure fluid. pressure, and a second fluid at high pressure, for example an exchange between a first CO2 fluid and a second CO2 fluid.

  Such an exchanger is capable of withstanding high pressures without requiring additional reinforcement or machining of the exchanger components.

  In the example shown in Figures 3 to 4b, there is formed an exchanger which defines a path for the first fluid similar to that of a coil heat exchanger. However, the realization of the exchanger from the circuit elements according to the invention makes the modular exchanger and allows to obtain different types of route. In particular, the number and the length of the circuit elements can be chosen as a function of the size of the installation in which the exchanger is used (for example a car air-conditioning installation), and the performances required for the heat exchange. etc. Moreover, the presence or absence of openings in a branch makes it possible to very simply perform passes in the exchanger. Thus, it is not necessary to provide added additional parts such as partition walls 12 (see Figure 1) usually present to form divisions in the manifolds 10 exchangers of conventional type.

  To make passes in an exchanger according to the invention, it is sufficient to provide a circuit element whose tips do not have an opening at the appropriate place.

  The use of a collection box is thus no longer necessary to obtain separate rooms. This results in a reduction in the number of parts and a simplification of the exchanger.

  FIGS. 5 to 7 show different views of a nozzle 24 intended for a circuit element 20 of a heat exchanger according to the invention, in particular a heat exchanger represented in FIGS. 3 to 4b. . As can be seen in Figure 5, the tips are made by stamping and bending a metal sheet strip, preferably aluminum, to form two branches 31 generally flat surface and without boss. The stamping allows for possible openings of the branches. As a simplification, the openings 28b are not shown in FIGS. 5 to 7.

  A stamp 42 is formed in the aluminum strip between the branches 31. The stamp 42 constitutes the bottom of the nozzle 24.

  The sheet metal strip is then folded so as to bring the two branches together, as can be seen in FIG.

  The stamping is shaped to accommodate an end of the corresponding tube so as to retain the liquid exiting this end. It thus prevents the liquid from escaping in the axial direction of the tube after assembly of the circuit element. For this, the section of the stamping 42 is adapted to the section of the corresponding tube and the bottom of the stamping may be substantially rounded so that the corresponding end does not rest entirely against the bottom wall of the stamped 42. Thus, the stamp 42 allows to provide an internal volume to retain the fluid from the end of the tube while providing satisfactory resistance to high pressures.

  Thus, the tips allow not only the passage of the first fluid of a given tube to the adjacent tube but also the closure of the open end of the tubes.

  In Figure 7, the two branches 31 have been fully folded and the tip is shown completed. It is then assembled, for example by fitting or crimping on a tube 22 before soldering. Auxiliary openings 44 and 45 facilitate brazing of the tip on the end of the tube 20.

  With this production, the problem that is encountered in conventional tube-bundle and collector-box heat exchangers, namely the problem of threading a small tube into a large collector with small dimensions and low tolerances.

  With the circuit elements according to the invention, it is sufficient to assemble end caps 24 on tubes 22 of the same dimensions. The mechanical function of introducing tubes into drilled manifolds is suppressed. This results in extreme simplification of assembly and manufacture of the exchanger. The absence of boss on the bits also simplifies the manufacture of the circuit elements.

  The manufacture of the exchanger will therefore include a production station for producing the tubes, a press for producing the end pieces and an automatic machine for inserting the end pieces on the tubes. Then passes directly to the assembly of the exchanger by superposition circuit elements thus manufactured. The assembly is then assembled by soldering.

  FIG. 8a shows a perspective view of an open end of a tube 22 for constituting a circuit element according to the invention. This tube is preferably a multichannel extruded tube to withstand high pressures. It comprises for example seven channels 46 separated by six partition walls 48. Such a tube is intended, in particular, to contain a fluid under high pressure. The partition walls 48 reinforce the tube and prevent it from bulging under the pressure of the fluid.

  In addition, the tube has a lateral circular opening 220 on one of its end portions or on both of its end portions (only one end shown) as it is connected to one or two end pieces. This opening 220 of the tube is adapted to the possible openings 28b of the corresponding endpiece.

  More specifically, the tip 24 is fitted on the end of the tube so that the opening 220 is located substantially opposite the opening or openings 28b of the branches 31, which forms the passage of the first fluid. .

  Figure 8b is a longitudinal sectional view of the end of a circuit element 24 according to the invention. The tip 24 of the circuit element shown has two branches 31 of branch thickness, the upper branch having an opening 28b while the lower branch has no opening. The tip is fitted into a tube 22 of thickness andube, which has an opening 220 of diameter greater than or equal to the diameter of the opening 28b of the upper tube. The tube 22comporte several channels 46 which open into the opening 220 of the tube. The tip comprises a stamping having a U-shaped bottom and auxiliary openings 45 to facilitate brazing. The outer diameter of the tube is substantially equal to the internal diameter of the nozzle. Thus when the end portion of the tube 22 is inserted into the nozzle 24, it abuts against the walls of the stamping without reaching the bottom. The fluid arriving in the tube through the openings 28b and 220 (the circulation of which is represented by the arrow in solid lines) can not escape from the circuit element thanks to this stamp 42 and circulates along the channels.

  FIG. 9 shows a perspective view of another embodiment of a nozzle according to the present invention. It differs from previous tips in that the two branches 31 are of different lengths.

  Indeed, the tips shown in Figures 3 to 8b all have branches of the same length which are superimposed and bear against each other when fully folded as can be seen for example in Figure 7 The tip shown in Figure 9 has branches 31 of different lengths. Each branch has a generally flat surface and no boss.

  Endpieces having branches 31 of unequal lengths make it possible, for example, to adapt the geometrical shape of the exchanger to the space available in the vehicle. This facilitates its implementation and is an advantage over the exchangers that use manifolds 10 (Figure 1) and must necessarily be rectangular.

  In the embodiments described above, the exchanger consists of circuit elements comprising a single tube 22. The circuit elements which constitute the exchanger of the invention may also comprise two tubes as shown in FIG. 11 or more than two tubes as shown in Figure 12, for example three or more tubes. In this case, each circuit element 20 comprises two different types of tips: on the one hand the end caps or end caps 24 previously described, on the other hand intermediate ends designated by the reference 124. The intermediate ends are distinguish end caps by the fact that they are connected to two separate tubes instead of being attached to the end of a single tube. The circuit elements of the heat exchanger shown in FIG. 11 comprise a single intermediate nozzle 124. The circuit elements of the exchanger shown in FIG. 12 comprise two intermediate tips 124.

  FIG. 13 shows a perspective view which illustrates the production of an intermediate nozzle 124. Intermediate tips, such as end caps, are obtained from a sheet, preferably an aluminum sheet. At first, this sheet is cut to obtain a Y shape (not shown). The Y shape is folded in two and the edges are folded so as to obtain a closed form of upper and lower faces generally flat and without boss, as shown in Figure 13. A tube 22 is then fitted to each of the ends of this closed form. The intermediate tips may have an angle as shown in Figures 11, 12 and 13. However, the intermediate tips could also be straight.

  The invention is also not limited to tube 22 described above with reference to FIG. 8. In fact, other types of tubes can be used.

  For example, the tube 22 shown in Figure 20 is similar to the tube 22 of Figure 8a, except that it is made by shaping a folded sheet 70 and not by extrusion. This sheet 70 has two longitudinal edges 72 which are joined together. Furthermore, this sheet has internal folds 74 adapted to define partitions defining seven interior channels 46. The tube further comprises a lateral circular opening 220 similar to that of the tube of Figure 8a. Such a tube is particularly suitable for use in an oil cooler.

  Another example of tube 22 is shown in FIG. 21. This tube 22, which is also similar to that of FIG. 8, is a flat tube that can be made by extrusion. This tube internally houses a corrugated insert 76, which makes it possible to define a multiplicity of circulation channels 46 inside the tube. It further comprises a lateral circular opening 220 similar to that of the tube of Figure 8a. Such a tube is also suitable for use in an oil cooler.

  The circuit element of the invention can be used to realize different types of heat exchanger and in particular condensers for motor vehicle air conditioning plants and oil coolers.

  Figures 14 to 16 illustrate an exchanger according to a first embodiment of the invention. The exchanger shown is able to withstand high pressures typically greater than 100 bar. It is particularly suitable for use with: a first fluid at high pressure (especially greater than 100 bar), for example the refrigerant CO2 (R744) or the fluid R134a, and a second fluid at low pressure (especially lower 5 to 10 bar), for example the engine coolant.

  This exchanger can be used as cooler or oil heater and in this case heat exchange occurs between the oil (first fluid) and the engine coolant (second fluid).

  It can also be used as a heat exchanger for automotive air conditioning systems operating with CO2 or R744 refrigerant.

  In particular, it can be used as an evaporator between the CO2 fluid and the cooling liquid to be cooled. The coolant then circulates in a "cold" radiator in the ventilation and air conditioning unit of the passenger compartment of the vehicle.

  It can still be used as a heat exchanger (with a heating or cooling function) between the R744 refrigerant and the engine coolant.

  Conventional heat exchangers using the coolant as a second fluid, for example for cooling the oil, generally comprise a stack of plates instead of a bundle of tubes. But such exchangers poorly withstand the high pressure of the first fluid without significant reinforcements. The heat exchanger proposed hereafter is both simple and modular while resisting high pressures.

  FIG. 14 shows a partial perspective view of a heat exchanger 2 'according to the first embodiment of the invention. This view shows a beam of circuit elements 20 obtained by pre-assembling each tube 22 with its respective tips and stacking the circuit elements on each other.

  Figure 14 shows in particular the inlet 58 and outlet 60 pipes of the first fluid. The path of the first fluid is illustrated by arrows in broken lines and the path of the second fluid by arrows in solid lines.

  The first high pressure fluid is alternately circulated in the tubes 22 as previously described due to the structure of the circuit elements.

  The second fluid at low pressure circulates between the tubes outside in the axial direction of the tubes and in the opposite direction to the flow direction of the first fluid. The outlet tubing 52 of the second fluid is shown in FIG.

  The bundle of stacked tubes 35 is arranged in an outer casing 64 consisting of several casing elements brazed together after placement of the bundle. Side plates are previously brazed to the beam to force the flow of the second fluid between the tubes.

  In Fig. 16, which shows an enlarged detail of Fig. 14, the tubes 22 of a circuit element are shown with their respective end-pieces 24. In the example of Fig. 16, small-channel tubes made by extrusion for good resistance to high pressures, especially greater than 130 bar.

  Figure 15 is an external view of the housing 64 of the exchanger 2 'after assembly. The inlet and outlet pipes 58 and 60 of the first fluid are generally oriented in the normal direction to the faces of the tubes (z axis) and the inlet and outlet pipes 50 and 52 of the second fluid are generally oriented in the perpendicular direction. to the axis of the tubes and to the faces of the tubes (x-axis). A housing 64 allows the circulation of the second fluid at low pressure in the exchanger. This housing consists of two half-housings 640 and 641 brazed together.

  The housing 64 tightly channels the fluid flowing between the tubes, which improves heat exchange.

  The heat exchanger described above also has satisfactory resistance to high pressures unlike the exchangers of the prior art which use the coolant as the second fluid.

  Figures 17 to 19 illustrate an exchanger according to a second embodiment of the invention. The exchanger shown is able to withstand high pressures typically greater than 100 bar. It is suitable for use with: a first fluid at high pressure (especially greater than 100 bar), for example the refrigerant 002 (R744), and a second high pressure fluid, also the refrigerant CO2 for example.

  It can be used as a heat exchanger for automotive air conditioning systems operating with 002 refrigerant, such as the Internal Heat Exchanger (IHX Internal Heat Exchanger).

  Figure 17 is an overall perspective view showing a heat exchanger 2 "according to the second embodiment of the invention.

  The exchanger comprises a bundle of tubes 35 This bundle consists of a stack of circuit elements according to the invention.

  The circuit elements of the tube bundle 35 "define a passage for the circulation of the first fluid as previously described.

  Fig. 17 shows in particular the outlet tubing 60 "of the first fluid, the flow of the first fluid is illustrated by arrows in broken lines.

  Figure 17 also shows the inlet pipe 50 "of the second fluid, the pipe 50" is prefixed on the beam 35 ", the circulation of the second fluid is illustrated by the arrows in solid lines, and the second fluid at high pressure circulates between the tubes outside in the axial direction of the tubes and in the opposite direction to the flow direction of the first fluid.

  The beam 35 "is arranged in a housing 64" consisting of several housing elements brazed together after introduction of the beam. In particular, this housing consists of two half-shells 640 "and 641" brazed together to form substantially a cylinder and two side covers, in particular in the form of a half-sphere, which close the ends of the cylinder. Only a cover 642 "is shown in Figure 17 to reveal the inner elements of the exchanger 2".

  Referring to Figure 18 which is an internal perspective view of the exchanger 2 ", side plates 70 are previously brazed to the beam to force the flow of the second fluid between the tubes.

  In FIG. 19 which is a fragmentary view on a larger scale of the exchanger, the tubes 22 are shown with their respective end-pieces 24. The tubes are also tubes with small channels that can be obtained by extrusion for holding at high pressures. , especially greater than 130 bars.

  In the exchangers described with reference to the first and second embodiments, the outer casing is obtained by brazing the casing elements and the circuit elements in a single operation. Alternatively, the outer casing may be a molded plastic part, in which is placed the stack of pre-brazed circuit elements.

  A turbulator may be added in the space between the tubes in the exchangers of the first and second embodiments of the invention to improve heat exchange and mechanical strength. It can be made by wheel or stamped. When assembling the components of the exchanger, it is brazed on the tubes.

  Such exchangers make it possible to replace the machined components of the prior art, such as the collector, with a less expensive modular structure. The number and length of the circuit elements can be changed simply. The exchange surface is easily modifiable without the use of tools.

  Of course, the exchangers described above according to the first and second embodiments of the invention are not limited to use for an air conditioning circuit operating with the refrigerant CO2, and can use any kind of fluid to achieve the heat exchange (gas, multi-phase liquid, etc.). Furthermore, the invention is not limited to the exchangers described above according to the first and second embodiments. Other types of heat exchangers made from the circuit element of the invention can be envisaged. In general, such exchangers may comprise: a bundle consisting of stacked circuit elements according to the invention; - side plates brazed with the beam; and - housing elements, welded together to form an outer casing after introduction of the beam, this outer casing channeling the second fluid, or a molded plastic casing in which is placed the stack of brazed circuit elements beforehand .

  The use of circuit elements in the exchangers makes it possible to simplify their manufacture. The manufacturing method of the exchangers in accordance with the invention can thus comprise: the pre-assembly of the tubes with their respective ends, the stacking of the circuit elements, to form the beam, the brazing of the bundle with side plates, introducing the beam into one of the housing portions, and welding all the housing elements.

  The use of the circuit elements in the exchangers according to the invention thus makes it possible to obtain both a simplified and less expensive structure than the embodiments of the prior art, a resistance to high pressures, a reduced Ptube pitch between the tubes. of the beam, a small footprint, and a satisfactory heat exchange.

Claims (24)

claims   A hydraulic circuit element (20) for exchanging heat between a first fluid and a second fluid, defining a path for the first fluid, the circuit element comprising at least one tube (22) having at least one an open end and a tip (24), said tip (24) comprising a bottom (42) closing said end and a side wall surrounding the tube in the vicinity of said end, the side wall having at least one opening (28b) in communication with a lateral opening (220) of the tube to help define the path of the first fluid, characterized in that the side wall of the nozzle (24) 15 is tightly applied to the tube (22) over its entire surface.   2. Circuit element according to claim 1, characterized in that each tip consists of a sheet metal strip pressed to form said bottom (42) and folded to form two branches (31), the side wall comprising said branches.   3. Circuit element according to claim 2, characterized in that the two branches (31) of each end piece (24) are of equal lengths.   4. Circuit element according to claim 2, characterized in that the two branches (31) of each endpiece (24) are of unequal length.   5. Circuit element according to one of claims 2 to 4, characterized in that said branches have a generally flat surface.   6. Circuit element according to one of claims 1 to 5, characterized in that the or said tubes (22) are generally flat.   Circuit element according to claim 6, characterized in that each tube (22) has multiple channels.   8. Circuit element according to one of claims 1 to 7, characterized in that it comprises a single tube (22) having a terminal end (24) at each of its ends.   9. Circuit element according to one of claims 1 to 7, characterized in that it consists of several tubes (22), an intermediate nozzle (124) being present between two tubes (22) successive.   10. Circuit element according to claim 9, characterized in that it has a rectilinear shape.   Circuit element according to claim 9, characterized in that it has a general broken shape.   12. Heat exchanger (2; 2 '), in particular for a motor vehicle, comprising a stack of elements (35; 35') circuit (20) according to one of the preceding claims communicating with each other through the intermediary of openings (28b) of said tips (24) to allow passage of the first fluid between said circuit elements.   13. Heat exchanger according to claim 12, characterized in that the circuit elements (20) come into contact with the branches of their respective ends (24) when they are stacked, so that a branch (31) a circuit element (20) rests on a branch (31) of an adjacent circuit element (20).   14. Heat exchanger according to one of claims 12 and 13, characterized in that it contains a coolant as a first fluid and the coolant as a second fluid.   15. Heat exchanger according to one of claims 12 and 13, characterized in that it contains a refrigerant fluid as a first fluid and as a second fluid.   2860288 27 16. Heat exchanger according to one of claims 14 and 15, characterized in that said coolant is the fluid R744.   17. Heat exchanger according to one of claims 12 and 13, characterized in that it contains the oil as a first fluid and the coolant as a second fluid.   18. Heat exchanger according to one of claims 12 to 17, characterized in that the Ptube pitch between the respective tubes of two adjacent circuit elements (20) is equal to 2 * ebranche + etube where ebranche designates the thickness d A branch of a mouthpiece (24) and a tube means the thickness of the tube (22).   19. Heat exchanger according to one of claims 12 to 18, characterized in that it comprises two side plates (70) brazed to the stack of circuit elements (35).   20. Heat exchanger according to one of claims 12 to 19, characterized in that it comprises an outer casing (64; 64 ') in which is arranged the stack (35; 35') of circuit elements ( 20).   21. Heat exchanger according to claim 20, characterized in that the outer casing (64) consists of casing elements (641, 641, 641 ", 640", 642 ") brazed together.   22. Heat exchanger according to claim 21, characterized in that the housing elements comprise half-shells (641 ", 640"), and two covers (642 ") welded to the ends formed by said half-shells.   23. Heat exchanger according to claim 20, characterized in that the outer casing (64; 64 ') is a molded plastic part in which is placed the stack (35; 35') of brazed circuit elements.   24. Heat exchanger according to one of claims 12 to 23, characterized in that it comprises a turbulator arranged in the space defined by two adjacent circuit elements.