FR2793016A1 - EXTENDED COLLECTOR BOX FOR HEAT EXCHANGER RESISTANT TO HIGH INTERNAL PRESSURES - Google Patents

Abstract

The header box is formed from a multiplicity of stacked plates, namely a header plate (4) having transverse openings (5) intended to communicate with flat tubes, a solid bottom (11) and intermediate plates (7-10 ) forming an insert (12). The plates of the insert have longitudinal slots (15a-15e) for some and transverse slots (14a, 14b) for others, together defining separate chambers for the fluid. The contacting surfaces of the different plates are brazed so as to form between the collector plate and the bottom a dense network of connecting bridges giving the collector box high resistance to internal pressure. Application to vehicle air conditioning loops using CO2 as refrigerant fluid.

Description

4,

  Elongated manifold for resistive heat exchanger

  both at high internal pressures The invention relates to an elongated manifold for heat exchanger, in particular for a refrigerant

  in a vehicle air conditioning system

the.

  EP-A-0 563 471 describes such a manifold, comprising

  both: a) a first wall defining a collecting plate and having at least one row of openings intended to allow fluid communication between the interior of the

  manifold and a bundle of flat sample tubes

  heat gor, mutually aligned in the longitudinal direction of the manifold and elongated in the lateral direction thereof; b) a second wall opposite the first, defining a substantially solid bottom; and c) an insert housed inside the manifold, extending substantially over the entire length and over the entire width of the latter and brazed to the internal faces of said

first and second walls.

  In air conditioning systems for motor vehicles

  biles, refrigerants are now used which, such as CO2, must be subjected to very high pressures, for example several hundred bars. The insert described in the aforementioned document defines longitudinal ducts of a relatively large width, allowing each opening of the collector plate to communicate through any

  its length with the same conduit. If such a box collects

  was used with a high pressure refrigerant, the extended surfaces of its walls, adjacent to the duct, would be exposed to the pressure of the fluid and

  would therefore be subject to deformation, unless increased

  ter the thickness of the walls and therefore the weight and

cost of the heat exchanger.

  The object of the invention is to allow the manifold to withstand more internal pressures without damage.

  while maintaining the wall thicknesses

  tiles in air conditioning exchangers.

  The invention relates in particular to a manifold of the kind defined in the introduction, and provides that the insert forms a network of brazed bridges between the collector plate and the bottom, this network being dense both in the longitudinal direction and in the transverse direction of so as to strengthen the resistance to internal pressure of the manifold.

  Optional features of the invention, complementary

  or alternative, are set out below:

  - Each strip of material separating two consecutive openings

  ves of said row is connected to the bottom by a multiplicity

  of bridges distributed in the transverse direction.

  - The distance between two consecutive bridges in the longitudinal direction or in the transverse direction does not exceed

millimeters.

  - The insert delimits conduits which generally extend

  in said longitudinal direction to establish communication

  fluid cation between said openings.

  - Said walls are substantially flat and the insert is

  formed of at least one flat plate provided with longitudinal slots

  nales defining said passages.

  - The insert is formed from a multiplicity of flat plates mutually stacked and brazed face to face, at least one of which is provided with longitudinal slots defining

said passages.

  - Said flat plates are provided, one with longitudinal slots, the other with transverse slots whose position in the longitudinal direction corresponds to that

said openings.

  - Said stacked plates have superimposed recesses communicating with said slots and opening into the peripheral edge of the plates to form an entry

  or a fluid outlet from the heat exchanger.

  - The insert is obtained by stacking plates with

said recesses.

  - Said recesses are obtained by machining the plates

previously stacked.

  - Said walls are substantially planar and the insert is formed of a thick block with planar faces crossed by slots

  longitudinal defining said passages.

  - A cavity formed by stamping the bottom communicates with said longitudinal slots and with an opening in the bottom to form an inlet or an outlet for fluid

of the heat exchanger.

  - The peripheral edges of the first and second walls are spaced from each other, the fluid tightness between said edges being achieved by the interposition of the peripheral edge

of the insert.

  - The insert has longitudinal slots mutually aligned in the longitudinal direction and / or transverse slots mutually aligned in the direction

  lateral to allow more fluid circulation

  several passes between the manifold and the tubes.

  - At least one of the first and second walls belongs to a bowl-shaped part, the peripheral edge of which is tightly connected to that of the other wall, and the insert is a corrugated sheet, the crests of which are corrugated are oriented longitudinally and brazed alternately at the two walls. - The corrugated sheet has, in the region of the corrugation ridges brazed to the collector plate and opposite the openings of the latter, notches intended to allow the passage of the ends of the protruding tubes

  inside the manifold.

  The invention also relates to a heat exchanger, in particular for a refrigerant in an air conditioning installation of a motor vehicle, comprising at least one manifold as defined above, and at least

  a row of flat tubes mutually aligned in the direction

  longitudinal, each tube communicating by one of its

  ends with one of the openings of the collecting plate

  this. In the case of a heat exchanger comprising a single manifold, the invention provides that each tube can have a multiplicity of separate circulation channels opening at its two ends, its end opposite to the manifold being capped with a plug. which allows a

  communication between the different channels for a circulation

tion in U in the tube.

  The characteristics and advantages of the invention will be

  described in more detail in the description below, in

referring to the attached drawings.

  FIG. 1 is a partial view in longitudinal section of a heat exchanger according to the invention, usable in particular as a high pressure exchanger or as an evaporator in an air conditioning loop using CO2 in

as coolant.

  Figure 2 is an exploded perspective view of the box

  collector shown in Figure 1.

  FIG. 3 is a partial view of one of the tubes of the

  beam, in section along line III-III of Figure 1.

  Figure 4 is a partial perspective view of a manifold showing a hollowed-out insert for entry or

fluid outlet.

  Figure 4a is a perspective view of a spacer

  machined inlet / outlet intended to be inserted in the recess

is lying.

  FIG. 5 is a view similar to FIG. 4, relating to

variant.

  Figures 5a and 5b are perspective views showing respectively a tubular spacer and a tubing

  adapted to the recess shown in Figure 5.

  Figure 6 is an exploded perspective view of a manifold usable as a replacement for that of Figure 2. Figure 7 is a view similar to Figure 6, showing the

  bottom and insert of the manifold, in a variant.

  Figure 8 is a partial view, in cross section along line VIII-vIII of Figure 9, of another exchanger

of heat according to the invention.

  Figure 9 is a longitudinal sectional view of this

  exchanger, according to line IX-IX of Figure 8.

  The heat exchanger illustrated in Figures 1 to 3

  conventionally includes a row of tubes 1 mutual-

  ment aligned from left to right in Figure 1 and separated from each other by corrugated spacers 2, to form a beam. These tubes are flat, that is to say that their cross section is elongated in a direction (from left to right of FIG. 3) perpendicular to their longitudinal direction (from top to bottom of FIGS. 1 and 3) and their direction of mutual alignment. Each tube is traversed from one end to the other by a multiplicity of independent channels 3, mutually aligned in the longitudinal direction of the cross section of the tube (8 channels in the example illustrated). At their upper end, the

  channels 3 communicate with the interior of a collection box

  trice whose bottom wall consists of a substantially flat header plate 4, having transverse openings 5 in which engage the ends of the respective tubes, the plate being deformed downward around each opening 5 to form a collar 6 brazed tightly over the entire periphery of the tube. On plate 4 are stacked five other flat plates 7-11, likewise

  rectangular outline as plate 4, the intermediate plates

  diaries 7 to 10 forming an insert 12 and the six plates

  together forming the manifold 13.

  According to the invention, each of the plates of the insert 12 is traversed in its thickness by longitudinal or transverse slots. The plate 7, adjacent to the collector plate 4, and the plate 9 are identical and each has transverse slots arranged in two rows. Each opening 5 of the collector plate faces two slots 14a, 14b belonging respectively to the two rows, the slot 14a facing the channels 3 with a half-width of a tube 4 and the slot 14b facing the channels

the other half-width.

  The plates 8 and 10 framing the plate 9 are identical and have longitudinal slots. In the half of the width of each of them situated above the row of slots 14a are provided slots mutually aligned by three, namely a slot 15a close to one end of the plate, an intermediate slot 15b and a slot 15c near the other end of the plate. The slot 15b is longer than the slots 15a and 15c. The set of slots 15b is separated from the set of slots 15a and the set of

  slots 15c respectively by two strips of material trans-

  verses 16a and 16b. In the other half of the width of the plate are provided slots mutually aligned by two, namely a slot 15d adjacent to the same end of the plate as the slots 15a, and a slot 15e adjacent to the other end. The set of slots 15d is separated from

  all of the 15th slots by a strip of transverse material

dirty 16c.

  In the completed heat exchanger, the six plates forming the manifold 13 are mutually brazed in a fluid-tight manner by all their contacting surfaces, thanks to a brazing coating provided on all their faces or on some of them only . Thus, the slots 14 and 15 represent the only free volumes accessible to the fluid inside the manifold, the configuration of which contributes to defining the path of circulation of the fluid in the heat exchanger. To complete the definition of this path, each tube 4 is for example capped at its lower end with a plug 17 which seals vis-à-vis the outside of the ends of the eight channels 3 while allowing their mutual communication . Alternatively, the lower ends of the tubes can open into a second identical or different manifold

to box 13.

  The set of slots 15a of the plates 8 and 10 defines, with some of the slots 14a of the plates 7 and 9, a first chamber of the manifold. Two other chambers are formed by the slots 15b on the one hand and the slots 15c on the other hand, with the other slots 14a. Two other chambers are also formed by the slots 15d on the one hand and e on the other hand, with the slots 14b. The fluid circulates in eight passes between these chambers, the circulation in each tube comprising a downward path by four channels 3

  followed by an ascending path by the other channels.

  There is shown in Figure 2 appendices 18 optionally provided on the plates of the insert and projecting relative to the rectangular outline thereof. These appendages have a keying function, visual or mechanical, avoiding

  stack the plates in the wrong position.

  Openings, not shown in Figure 2, must be provided for the inlet and outlet of the fluid. These openings can be formed by recessing the insert,

  as shown in Figures 4 and 5.

  FIG. 4 shows a manifold comprising an insert 12 composed as above of six superimposed plates between the manifold plate 4 and the bottom 11. Each plate of the insert has a notch 20 which communicates with at least one of the slots of the plate and opens onto its peripheral edge, the notches of the various plates overlapping to form a recess 21 of the insert which

  communicates with one of the chambers of the manifold.

  This recess, of parallelepiped shape in the example illustrated, can receive the body 22, of corresponding shape, of a machined spacer 23 shown in FIG. 4a, provided with a tubular connection 24 for connection to the rest

  of the refrigerant loop.

  Figure 5 shows an insert 12 similar to that of Figure 4, but whose plates do not have predefined notches. A circular hole 25 is machined in the assembled insert, from its peripheral edge, to play the same role as the recess 21. this hole can receive a tubular spacer 26 shown in FIG. 5a, or

  the end of a tube 27 of circular section represented

  partially shown in Figure 5b, part of the circuit

refrigerant.

  In FIG. 6, the stack of plates constituting the insert is replaced by a solid part 30 obtained by cutting off an extruded profile. This insert 30 is traversed in its thickness by longitudinal slots 31 having the same arrangement as the slots 15 of the plates 8 and 10 described above. To make a fluid inlet or outlet, the bottom 32 of the manifold is stamped locally to form a cavity communicating with a group of slots 31, this cavity opening to the outside through an opening

  33, on the peripheral edge of the manifold.

  In the variant of FIG. 7, the bottom 35 of the manifold is again planar, and a recess 36 is provided in the one-piece insert 37 for the entry or exit of fluid, this recess communicating with a group of slots

  and opening into the peripheral edge of the insert.

  Figures 8 and 9 illustrate another embodiment of a heat exchanger according to the invention, in which the flat bottom 40 of the manifold belongs to a part 41 in the form of a bowl, the peripheral edge 42 of which is brazed to that of the collecting plate 6. The reinforcing insert housed in the collecting box is here a thin solid plate 43 having undulations oriented in the direction

  longitudinal of the manifold, the crests of undula-

  tion being brazed alternately to the internal faces of the

plate 6 and bottom 40.

  In this example, a multiplicity of separate longitudinal paths for the fluid are defined inside the manifold, between the insert 43 and the plate 4, each tube communicating with several of these paths. Alternatively, the corrugated insert may have uniformly distributed perforations, with a daylight rate of less than 50%, or "louvers", that is to say parts cut and folded in the shape of a U, to allow the fluid to flow also

between the insert and the bottom 40.

  In the case where, contrary to what is shown in FIGS. 8 and 9, the tubes would protrude inside the manifold, notches could be made

  in the insert to accommodate their ends.

  In the embodiments of Figures 6 and 7, as in

  that of FIGS. 8 and 9, and in the case of plates comprising

  as long as only longitudinal slots, the insert delimits separate longitudinal conduits for the circulation of the fluid (subject to the inlet and outlet cavities). On the contrary, in the embodiment of Figures 1 to 3, and in the case where the corrugated insert has perforations or louvers and / or notches, different longitudinal ducts communicate with each other to define an overall oriented path of a generally in the direction

  longitudinal of the manifold.

  In all of the embodiments described, the insert is linked to the bottom of the manifold by continuous longitudinal brazing lines, juxtaposed a short distance from each other, and to the manifold plate by longitudinal brazing lines also close to each other, each of these last lines having interruptions corresponding only to the width of the passage opening of a tube. In addition, in the embodiment of FIGS. 1 to 3, the constituent plates of the insert are linked to each other by soldering zones which are spaced apart from each other, in the longitudinal direction and in the lateral direction, a distance corresponding to the width of the slots 14 and 15. These connections therefore form a dense network of brazed bridges ensuring a high resistance of the manifold to

internal pressure.

  In the case where the insert is formed from stacked plates, the number of these is advantageously between four and six, and their thickness between 0.5 and 3 mm. Instead of two types of plates having respectively longitudinal and transverse slots, one type can be provided

  of longitudinal slit plates.

  Of course, the configuration of circulation of the fluid in the heat exchanger described in relation to FIG. 2 is only one example of the multiple possibilities offered in this regard, depending on the number and the length of the slots provided in the 'insert and the presence or absence of a second manifold. For a heat exchanger supplied with CO2, the number of passes is advantageously between six and sixteen, and preferably chosen from the values eight, twelve and sixteen, so that the inlet and the outlet of the

  fluid are carried out on the same manifold.

  A heat exchanger according to the invention can also be used with a conventional fluid such as R134a, the number of passes then advantageously being between four and six.

Claims (18)

Claims   1. Elongated manifold box (13) for a heat exchanger, in particular for a refrigerant in an air conditioning installation of a motor vehicle, comprising: a) a first wall defining a manifold plate (4) and having at least one row of openings (5) intended to allow fluid communication between the interior of the manifold and a bundle of flat tubes (1) of the heat exchanger, mutually aligned in the longitudinal direction of the manifold and elongated in the lateral direction of it; b) a second wall opposite the first, defining a substantially solid bottom (11); and c) an insert (12) housed inside the manifold, extending substantially over the entire length and over the entire width of the latter and brazed to the internal faces of said first and second walls, characterized in that the insert forms a network of brazed bridges between the collector plate and the bottom, this network being dense both in the longitudinal direction and in the transverse direction so as to reinforce the   resistance to the internal pressure of the manifold.   2. Collector box according to claim 1, in which each strip of material separating two consecutive openings (5) of said row is connected to the bottom (11) by   a multiplicity of bridges distributed in the trans- versal.   3. Collector box according to one of claims 1 and 2,   in which the distance between two consecutive bridges in the longitudinal direction or in the transverse direction does not exceed 10 millimeters.   4. Collector box according to one of claims   preceding, in which the insert delimits conduits which generally extend in said longitudinal direction to establish a communication of fluid between said openings.   5. Collector box according to one of claims   previous, wherein said walls are substantially planar and the insert is formed of at least one planar plate (8,) provided with longitudinal slots (15a-15e) defining said passages.   6. Collector box according to claim 5, in which the insert is formed from a multiplicity of flat plates (7-10) mutually stacked and brazed face to face, at least one of which (8, 10) is provided with slots   longitudinal (15a-15e) defining said passages.   7. A manifold according to claim 6, wherein said planar plates are provided, some (8,) of longitudinal slots (15a-15e), others (7, 9) of transverse slots (14a, 14b) whose position in the   longitudinal direction corresponds to that of said openings res (5).   8. Collector box according to one of claims 6 and 7,   wherein said stacked plates have recesses   superimposed elements (20) communicating with said slots and opening into the peripheral edge of the plates to form   a heat exchanger fluid inlet or outlet.   9. Collector box according to claim 8, in   which the insert is obtained by stacking plates presented both said recesses (20).   10. Collector box according to claim 8, in which said recesses (25) are obtained by machining the plates previously stacked.   11. Collector box according to one of claims 1 to 4,   wherein said walls (4, 32) are substantially planar and the insert is formed from a thick block (30) with faces   planes traversed by defined longitudinal slots (31) the said passages.   12. Collector box according to claim 11, in which a cavity formed by stamping the bottom (32) communicates with said longitudinal slots and with a   opening (33) formed in the bottom to form an inlet or outlet for fluid from the heat exchanger.   13. Collector box according to one of claims 5 to 12,   in which the peripheral edges of the first and second walls (4, 11) are spaced from one another, the fluid tightness between said edges being achieved by the interposition   from the peripheral edge of the insert (12).   14. Collector box according to one of claims 5 to 13,   in which the insert has longitudinal slots   mutually aligned in the longitudinal direction (15a-   e) and / or transverse slots mutually aligned in the lateral direction (14a, 14b) to allow circulation of fluid in several passes between the box manifold and tubes.   15. Collector box according to one of claims 1 to 4,   in which at least one (40) of the first and second walls (6, 40) belongs to a bowl-shaped part (41) whose peripheral edge (42) is tightly connected to that of the other wall , and the insert (43) is a corrugated sheet whose corrugation ridges are oriented   longitudinally and brazed alternately at the two walls.   16. Collector box according to claim 15, in which the corrugated sheet has, in the region of the corrugation ridges brazed to the collector plate and opposite the openings of the latter, notches intended to allow the ends of the tubes to pass through.   protruding inside the manifold.   17. Heat exchanger, in particular for a refrigerated fluid   rant in a motor vehicle air conditioning installation, comprising at least one manifold (13)   according to one of the preceding claims, and at least one   row of flat tubes (1) mutually aligned in the longitudinal direction, each tube communicating by one of its ends with one of the openings (5) of the plate collector (4).   18. Heat exchanger according to claim 17, comprising   nant a single manifold (13) and in which each tube has a multiplicity of separate circulation channels (3) opening at its two ends, its end opposite to the manifold being capped with a plug (17) which allows communication between different channels   for U-shaped circulation in the tube.