FR2846736A1 - Stacked plate heat exchanger for motor vehicle air conditioning has separating wall to define separate heat exchange sections which can be selectively communicated for multiple stage operation - Google Patents

Abstract

The stacked plate heat exchanger for a motor vehicle air conditioner has the edges (3) of the plates (2) sealed to define fluid flow circuits. A separating wall (4) divides the plates into at least two heat exchange sections (6,8) each with multiple flow channels alternately for two fluids. The heat exchange sections can be selectively communicated to provide multistage heat exchange.

Description

Stacked plate heat exchange module, in particular for a vehicle

  The invention relates to heat exchangers, in particular to condensers, in particular for motor vehicles. More particularly, it relates to a heat exchange module comprising a multiplicity of stacked plates each provided with a peripheral edge, wherein the peripheral edges are sealingly assembled to delimit between the plates of the fluid flow circuits. Already known (DE-A-19511991 and EP 1 063 486) stacked plate heat exchangers used for example as oil coolers for motor vehicles, for cooling the engine oil or the engine oil cooler. The automatic transmission oil is cooled by heat exchange with a cooling fluid, usually that used to cool the vehicle engine. However, in plate heat exchangers of this type, the plates are grouped in a single stage, which does not allow to cool or sufficiently heat a fluid because the inlet temperature of the second fluid, with which it is in relation heat exchange, is not sufficiently low, respectively sufficiently high. In addition, the different

  plate heat exchangers, for example the one used for cooling the engine oil and the one used for cooling the oil of the automatic gearbox, occupy a large volume in the engine compartment of the engine. vehicle.

  The present invention relates to a heat exchange module that overcomes these disadvantages. For this purpose, it proposes a heat exchange module of the type defined above which comprises at least one partition wall which divides the plates into at least two heat exchange sections, each section comprising first channels of heat exchange. flow for a first fluid that alternate with second flow channels for a second fluid, said partition being provided adapted to allow passage from one section to another of at least one of said fluids. In order to ensure the independence of at least one of the exchange sections, at least one of the partition walls may not be

  have no communication passage.

  Thus, the two fluids circulating in one of the two heat exchange sections adjacent to the plate having no communication passage circulate independently of the two fluids flowing in the other heat exchange section located from the other side of the partition wall having no separation passage. two separate and completely separate heat exchange circuits are thus realized. It is thus possible to have two completely independent heat exchangers, for example an automatic gearbox oil radiator and an engine oil cooling oil radiator that are completely independent of one another with a great compactness. . This results in a decrease in the footprint under

the hood of the vehicle.

  On the contrary, if it is desired to establish communication between at least two heat exchange sections, at least one of the partition walls of the heat exchange module of the invention comprises a communication passage allowing the passage of one of the two fluids circulating in one of the sections on one side of the partition in the section on the other side of the partition in order to exchange heat with one of the two fluids flowing in the section

  exchange located on the other side of the partition.

  This produces a multistage heat exchanger. A same fluid is successively put into a heat exchange relationship with a first fluid flowing in a first heat exchange section and then with a second fluid flowing in a second heat exchange section. This fluid can thus be heated or cooled further. The fluid is heated to a certain temperature by

  heat exchange with the first fluid, then further heated by heat exchange with the second fluid.

  Conversely, it can be cooled to a certain temperature by heat exchange with the first fluid, and then further cooled by heat exchange with a second one.

fluid colder than the first.

  The partition walls may have very diverse embodiments. Preferably, however, they are constituted by current plates of the heat exchange module. Thus, the partition walls have a size that is not greater than that of a common plate. On the other hand, it is not necessary to provide special tools for making them. They can be made at the same time

than the other plates.

  Each plate generally has two communication passageways for allowing entry of the first and second fluids into a flow channel and two communication passages to allow the output of the first and second fluids.

fluids of this flow channel.

  According to one embodiment, one of these communication passages is absent in some of the plates of a heat exchange section, in order to determine passes for the circulation.

  of one of the first and second fluids.

  Thus, it is possible to realize a heat exchanger comprising 5 passes without having to provide additional parts. The partition walls are obtained directly by means of the current plates of the exchanger by not providing for a communication passage in one of the two inlet passages or

  two exit passages from a running plate.

  Furthermore, the invention relates to an air conditioning circuit, in particular of the passenger compartment of a motor vehicle, comprising an evaporator, a compressor, a condenser and an expansion valve, in which a cooling fluid circulates, the condenser being constituted by an exchanger according to the invention

at least two storeys.

  Such a circuit may equally well be used with a phase-changing refrigerant with a refrigerant remaining in the same phase.

  In a particular embodiment, at least one of the stages of the heat exchange module is cooled by the engine coolant, and the second stage is cooled by the cycle fluid itself of the air conditioning circuit.

  Preferably, the refrigerant flows through the second stage of the multi-stage heat exchanger after passing through the evaporator and before being compressed in the compressor. 30

  Other features and advantages of the invention will become apparent upon reading the following description of exemplary embodiments given for illustrative purposes in

  reference to the appended figures. In these figures: FIG. 1 is an external perspective view of a plate heat exchange module according to the invention; FIG. 2 is a sectional view of the heat exchange module shown in FIG. 1; FIGS. 3 and 4 respectively represent a perspective view and a sectional view of a heat exchange module represented on FIGS. Figures 1 and 2; - Figure 5 is a schematic perspective view which illustrates the flow of fluids within a heat exchange module constituting a multi-stage heat exchanger; Figures 6 and 7 illustrate an embodiment of the plates of the heat exchange module of the invention; FIG. 8 is a sectional detail view which shows a possible example of embodiment of fluid inlet or outlet tubing in a heat exchange module according to the present invention; - Figure 9 is a schematic view illustrating the operation of a conventional air conditioning circuit of the passenger compartment of a motor vehicle; Figure 10 is a diagram showing an air conditioning circuit according to the present invention; and

  Figure 11 is a perspective view of an air conditioning circuit according to the present invention.

  FIG. 1 shows an external perspective view of a heat exchange module according to the present invention and, in FIG. 2, a sectional view taken diagonally of the exchange module shown in FIG. Figure 1. The heat exchange module comprises a plurality of plates 2 (Figure 2) stacked on each other and each provided with a peripheral flange 3. The peripheral edges are assembled in a sealed manner to delimit between the plates first flow channels for a first fluid F1 which alternate with second flow channels for a second fluid F2. The heat exchange module comprises at least one partition wall 4 which divides the plates 2 into at least two heat exchange sections. The illustrated example comprises a single partition wall 4 which divides the plates into a first section 6 and a second heat exchange section 8. However, the heat exchange module could comprise a larger number of sections of the heat exchange module. heat exchange, for example three, four or more. The heat exchange sections may be independent of one another. In this case, the partition walls 4 disposed between these sections do not include any communication passage for the fluids flowing in each of them. Thus, there are as many independent heat exchangers as there are sections. If the partition 4 of the example shown does not include any communication passage, the heat exchange module will comprise two independent heat exchangers 6 and 8. Fluids Fl and F2 will flow in the first heat exchanger 6 in relation to heat exchange, independently of the fluids F3 and F4 of the second heat exchanger 8. This reduces the size of the

  exchangers by grouping them together in the same module.

  In another embodiment, the heat exchange sections 6 and 8 can communicate with each other via a communication passage provided in the partition 4. The communication passage allows the passage of one of the fluids, for example the fluid F2 of the heat exchange section 6, in the heat exchange section 8 located on the other side of the partition 4. Thus, the fluid F2 is in heat exchange relation with the fluid Fl in a first section heat exchange (section 6), then with the fluid F3 in a second heat exchange section. This produces a multistage heat exchanger. The multi-stage exchanger may comprise more than two stages, for example three or more. The partition wall 4 is preferably constituted by a common plate. This plate has only one communication passage 28, instead of the four passages provided in a

ordinary plate.

  The heat exchange module includes tubings that allow the entry and exit of fluids. In the example 15 shown, the heat exchange module 6 comprises an inlet pipe 12 for the fluid Fl and an outlet pipe 14 for the same fluid. Similarly, the exchange section 8 comprises an inlet pipe 16 for the fluid F3 and an outlet pipe 18 for the same fluid. If the heat exchange sections 6 and 8 are independent of each other, the module 6 will comprise an inlet pipe, for example the pipe 20 for the fluid F 2, and an outlet pipe (not shown ) for this same fluid also depending on the exchange module 6. In the same way, the heat exchange section 8 will comprise an inlet pipe, for example the pipe 22, for a fluid F4 and an outlet pipe. (not shown) for this same fluid. In total, the heat exchange module will comprise four tubes 30 depending on the exchange module 6 and four dependent tubes.

  exchange module 8, a total of eight tubes.

  If, on the contrary, the heat exchange sections 6 and 8 communicate with each other, the fluid F2 will enter the section 6 through the inlet pipe 20 and emerge from the section 8, after passing through the partition wall 4 by the outlet pipe 22. It can be seen that in this case the heat exchange module has only three pipes on each of the heat exchange sections, ie six pipes.

  in total instead of eight previously.

  FIGS. 3 and 4 show a perspective view and a cross-sectional view of a heat exchange module according to the invention with two heat exchange sections 6 and 8 communicating between 10 they through a communication passage 28. Fl fluid enters

  in the exchange section 6 by the inlet pipe 12 and out through the outlet pipe 14, as shown by the arrows, after exchanging heat with the fluid F2 which enters the exchange section 6 by the inlet pipe 20.

  The fluid F2 leaves the exchange section 6 through the communication passage 28 and enters through the same passage (shown in two parts in FIG. 3) in the heat exchange section 8. In this section, it exchanges the heat with the

  F3 fluid which enters through the intake manifold 16 and out through the outlet manifold 18, as shown schematically by the arrows.

  The fluid F2 then comes out at the bottom of the

exchange section 8.

  Thus, the fluid F2 can be cooled a first time by heat exchange with the fluid F1, then further cooled by the fluid F3, the inlet temperature of which is lower than the inlet temperature of the fluid F1. Conversely, the fluid fluid F2 may be heated by heat exchange with fluid F1, and then further heated in exchange section 8 by heat exchange with fluid F3 whose inlet temperature is greater than the inlet temperature of fluid Fl in the heat exchange module 6. The multi-stage heat exchanger thus produced allows an increase in the amplitude of the cooling or the heating. In practice, the fluid Fl will be, for example, a liquid such as the engine coolant, and the fluid F3 a gas, for example the refrigerant gas of the air conditioning circuit of the passenger compartment of the motor vehicle. Figure 4 shows very schematically how the plates 2 delimit between them first channels 30 for the fluid Fl that alternate with second channels 32 for the fluid F2. The fluid F1 flows from right to left, according to the figure, in the flow channels 30, while the fluid F2 flows from the left to the right in the flow channels 32. After having traveled the last channel 32, the fluid F2 passes through the partition wall 4 through the communication passage 28 and then flows from right to left in the flow channels 34 which alternate with the flow channels 36 in which circulates,

left to right, fluid F3.

  FIG. 5 shows diagrammatically an exploded perspective view which illustrates in another manner the flow of fluids in a heat exchange module according to the invention comprising heat exchange sections 6 and 8 communicating between they by a communication passage. The fluid F2, whose path is shown schematically in solid lines, enters the upper part of the section 6 through the pipe 20 in a conduit 40 which crosses the entire height of this section to the partition wall (not shown) arranged between the two sections. This duct 40 thus fulfills the role of a collecting box in a

exchanger of conventional type.

  In the same way, the Fl fluid, whose path is schematized in dashed lines, enters through the inlet pipe 12 at the upper part of the exchange section 6 to the partition wall 4 in a pipe 42 constituting a collecting box. The fluids F1 and F2 pass through the exchange section 6 diagonally, in a single pass, in the flow channels 30 and 32, as shown in FIG. 4. Of course, as will be described in more detail later, the Fl and F2 fluids circulation could be carried out in

several passes.

  The fluid F1 then circulates from bottom to top, as shown schematically by the arrows, to emerge at the upper part of the exchange section 6 through the tubing 14, while the fluid

  F2, after passing through the communication passage 28 (FIGS. 3 and 4), enters a conduit 44 forming a collection box of the exchange section 8. Moreover, the fluid F3 enters the lower part of the exchange section 8 through 15 the tubing 16 in a duct 46 forming a collector box.

  The fluids F2 and F3 pass through the flow channels 34 and 36 diagonally, as shown in FIG. 4. The fluid F3 goes down to the lower part of the exchange section 8, as shown by the arrows, and leaves the exchanger through outlet pipe 18, while fluid F2 leaves

  the exchanger through the outlet pipe 22, also located at the lower part of the exchange section 8. In the example shown, the flow of fluids F2 and F3 is effected in a single pass. But, of course, it could be done in several passes.

  There is shown in Figures 6 and 7 a preferred embodiment of the plates of a heat exchange module according to the invention. These plates are stacked according to a so-called "flake" assembly technique. Each of the exchange sections 6 and 8 (see FIGS. 1 to 5) comprises first plates 50 which alternate with second plates 52 of different configuration.The first plates 50 each have a bottom 54 surrounded by a peripheral edge 56 raised towards the The bottom 54 is provided with corrugations 58 of substantially sinusoidal shape defined by generatrices parallel to each other and which extend in a first direction D1 (Figure 7) .The second plates 52, arranged alternately with the 5 first plates 50, each have a bottom 20, 60 surrounded by a raised peripheral edge 62, having a shape homologous to that of the aforementioned peripheral edge 56. The bottom 60 has corrugations 54 of substantially sinusoidal shape defined by generatrices extending into a second direction D2 which is substantially perpendicular to the first direction D1

  (Figure 7). The plates 50 and 52 are formed by stamping a metal sheet, preferably based on aluminum. They are, in the example, of a generally rectangular shape but could have another shape, provided that their raised edges can fit in pairs.

  The plates are stacked and thus come into mutual contact at their periphery by their respective raised edges 56 and 62 which are brazed to provide a sealed mechanical connection. Moreover, the corrugations 58 of a first plate are in

  contact with the corrugations 64 of a second adjacent plate.

  The plates 50 and 52 thus delimit between them channels for the first fluid Fl that alternate with channels for the

second fluid F2.

  The respective undulations 58 and 64 make it possible to give the channels a particular three-dimensional structure which

  promotes a turbulent flow of Fl and F2 fluids.

  Referring to Figures 6 and 7, h represents half of the maximum spacing between respective ridges 67 and 68 of the respective corrugations 58 and 64 of a first plate 50 and

  a second plate 52 adjacent.

  The hydraulic diameter is defined by the relation D = 4 x volume occupied by the fluid / wet surface. It is essential

  that the hydraulic diameter of the channels has a chosen value.

  This value is preferably between 0.1 and 3 mm.

  The improvement of the mechanical strength at the internal pressure of the exchanger is obtained thanks to the raised edges of the plates stacked one inside the other and, possibly, thanks to several reinforced end plates added to the heat exchange module. , as well as through the contacts between plates

  at the level of the undulations that present them.

  The inlet and outlet pipes of fluids Fl, F2, F3, F4 can be made in various ways. Spacers (not shown), for example of circular shape, arranged between the plates of the exchanger may be provided. In a preferred embodiment, as shown in FIG. 8, every other plate, for example the plates 50, has bowls 70 whose bottom has a through hole 72 and which are sealed to the bottom of the plate 52. adjacent. The pipes or manifolds 40, 42, 44, 46 are thus defined without the need for any additional parts. In addition, thanks to this method, it is possible to make a multiple-pass heat exchanger without having to provide additional partition walls. It is sufficient to provide that some of the plates 50 and 52 will not include a communication passage at appropriate places chosen

  to achieve a multi-pass traffic.

  FIG. 9 is a diagrammatic view of an air conditioning device of the passenger compartment of a motor vehicle. It comprises a compressor 76 which compresses the refrigerant fluid in the gaseous state. This fluid is introduced into the condenser 78 that it runs through a succession of passes. After the last pass, the coolant leaves the condenser 78 via an outlet pipe 80 into which a restriction 82 is integrated and enters the tank 84. The refrigerant leaves the tank 84 via an outlet pipe 86 to be expanded in an expansion valve 88 and to the evaporator 90. By passing from the liquid state to the gaseous state, the refrigerant absorbs heat, which allows to refrigerate the passenger compartment of the vehicle. After the evaporator 90, the refrigerant returns to the

  compressor 76 and the cycle starts again.

  In a conventional air conditioning circuit of this type, the condenser 78 is generally cooled by a flow of air 10 which circulates in contact with corrugated inserts arranged between tubes in which the coolant circulates. An exchanger of this type has only one cooling stage. The invention concerns (FIG. 10) a condenser intended for

  air conditioning circuit of the passenger compartment of a vehicle having two cooling stages and thus allowing a better condensation of the refrigerant and consequently an improvement of the performance of the air conditioning circuit.

  The condenser 100 consists of a first exchange section 6 and a second exchange section 8 separated by the partition wall 4 which may be constituted, for example, by a common plate having a single communication passage 26 (Figure 3). The cooling fluid Fl of the exchange section 6 is constituted by the water of the engine cooling circuit. The gaseous refrigerant flowing out of the compressor 76 penetrates at 40 in section 6. This refrigerant constitutes the fluid F2 that has been discussed in the examples

previously described.

  The fluids F1 and F2 travel through the heat exchange section 35 in several passes (not shown). The cooling water leaves the condenser 100 through the outlet pipe 14. The cooling fluid F2 passes through the partition wall through the communication passageway and enters the cooling section 8. In this section, it is cooled further by exchange. of heat with a fluid 5 F3. This fluid is none other than the refrigerant cycle fluid

  it itself at the outlet of the evaporator 90. After leaving the exchange section 8, the fluid F3 is directed towards the compressor 76. The coolant F2, subcooled, leaves the condenser through the outlet pipe 82 as in the prior art described with reference to Figure 9.

  It can thus be seen that the cooling fluid of the air conditioning circuit appears in two different roles. It is both the fluid F2 to be cooled and the cooling fluid F3. The second stage 8 of the exchanger thus makes it possible to lower the temperature of the air conditioning fluid after the first stage.

  6 and improve the performance of air conditioning.

  FIG. 11 shows a perspective view of the air conditioning circuit according to the invention shown in FIG. 10. This figure shows the condenser 100 consisting of the two exchange sections 6 and 8, the bottle or reservoir 24, the expander 88, the evaporator 90, the compressor 76. The condenser 100 may have a plate structure

  stacked, as described above, or other.

Claims (8)

claims   A heat exchange module comprising a plurality of stacked plates (2, 50, 52), each provided with a peripheral edge (3), wherein the peripheral edges are sealingly assembled to delimit between the plates of the plates. fluid flow circuits (30, 34), characterized in that it comprises at least one partition wall (4) which divides the plates into at least two heat exchange sections (6, 8), each section with first channels   for flow (30, 34) for a first fluid (F1, F3) which alternate with second flow channels (32, 36) for a second fluid (F2), said separating partition being adapted to allow the passing from one section to another from one to more than one of said fluids.   2. Heat exchange module according to claim 1, characterized in that at least one of the partition walls (4) has no communication passage (28). 3. Heat exchange module according to claim 1, characterized in that at least one of the partition walls (4) comprises a communication passage (28) allowing the passage of one of the fluids (F2). circulating in one of the sections (6) on one side of the partition (4) in the heat exchange section (8) on the other side of the partition (4) in order to achieve a heat exchange with a fluid (F3) flowing in the exchange section (8) located on the other side of the partition (4). 30   4. Heat exchange module according to one of claims 1 to 3, characterized in that the partition walls (4) consist of common plates (2, 50, 52) of the heat exchange module.   5. Heat exchange module according to one of the claims   1 to 4, characterized in that each plate (2, 50, 52) generally comprises two communication passages for allowing the entry of the first and second fluids (F1, F2) into a flow channel (30, 32) and two communication passages for allowing the first and second fluids of said flow channel to exit, and in that one of these communication passages is suppressed in some of the plates of a heat exchange section ( 6, 8) to determine passes for the flow of one of the first and second fluids (F1, F2).   6. Heat exchange module according to one of claims 1 to 5, characterized in that it comprises ducts or manifolds (40, 42, 44, 46) constituted by bowls (72) 15 formed in the plates (50) of the heat exchange module.   7. Air conditioning circuit, particularly for the passenger compartment of a motor vehicle, comprising an evaporator (90), a compressor (76), a condenser (100), an expansion valve (88), in which a fluid circulates refrigerant, characterized in   the condenser (100) is constituted by a two-stage heat exchanger (6, 8) at least according to one of claims 3 to   Circuit according to Claim 7, characterized in that   at least one of the stages (6, 8) of the multi-stage exchanger (100) is cooled by the cooling fluid (Fl) of the engine and the second stage (8) is cooled by the fluid of refrigerant cycle itself (F3) of the air conditioning circuit.   9. Circuit according to claim 7, characterized in that the coolant (F3) flows through the second stage (8) of the multi-stage heat exchanger (100) after passing through the evaporator (90), and before to be compressed in the compressor (76).