1. Field of the invention

The field of the invention is that of the design and manufacture of heat exchangers that may in particular be used to carry out the function of evaporator for example in an automotive vehicle air-conditioning circuit.

2. Prior art

Tube heat exchangers comprising two header tanks between which tubes extend, these tubes leading into one of the header tanks at each of their ends, are known, the internal structure thereof determining the various flow passes of the refrigerant through the tubes.

Plate heat exchangers are also known. The present invention relates most particularly to exchangers of this type.

Figures 1 and 2 schematically illustrate a plate heat exchanger.

As shown in these figures, a plate exchanger 1 comprises a body made up of a stack of plates 1 0, an air flow space (not shown) being formed between the plates 1 0 to allow an air flow A to pass between the plates 10 through the exchanger. In the example illustrated in Figure 1 , the number of plates is equal to seven. In that illustrated in Figure 2, the number of plates is equal to three. Each plate 1 0 delimits internal channels 1 1 for circulating refrigerant. In the example illustrated, each plate comprises three channels. Each plate 1 0 comprises refrigerant distribution tanks 1 2, 1 3 at each of its ends. The channels 1 1 of each plate 10 are linked to a tank 1 2,1 3 at each of their ends. Each plate 1 0 thus comprises three tanks 1 2 at a first end of the exchanger and three tanks 1 3 at the opposite end. Thus, as is more clearly apparent from Figure 2, these plates 1 0 are linked to one another at one end by their distribution tanks 1 2 and at the other end by their distribution tanks 1 3, which respectively form three reservoirs 1 20 and 1 30 at each opposite end of the exchanger to allow the refrigerant to flow through various channels 1 1 of various plates 10 according to a desired circulation path inside the exchanger 1 .

In the example illustrated in Figure 2, the refrigerant enters the exchanger via the inlet E formed at the level of the upper tank 1 2 of the channel 1 1 located in the middle of the first plate 1 0. It passes from plate to plate through the upper tanks 12 constituting the reservoir 120 located in the middle and flows into each of the channels 1 1 in the middle of each plate 10 in a first pass.

The lower tank 13 of the channel 1 1 in the middle of the last plate 10 is in fluidic communication 14 with the upper tank 12 of the right-hand channel 1 1 of the last plate 10. The refrigerant passes from plate to plate through the upper tanks 12 forming the reservoir 120 located on the right and flows into each of the right-hand channels 1 1 of each plate 10 in a second pass.

The lower tank 13 of the right-hand channel 1 1 of the first plate 10 is in fluidic communication 15 with the lower tank 13 of the left-hand channel 1 1 of the first plate 10. The refrigerant passes from plate to plate through the lower tanks 13 forming the reservoir 130 located on the left and flows into each of the left-hand channels 1 1 of each plate 10 in a third and final pass.

The refrigerant leaves the exchanger via the outlet S linked to the top tank 12 of the left-hand channel 1 1 of the first plate 10.

The evaporator illustrated is therefore of the type having three rows of channels (or tubes) and three passes.

The efficiency of such an exchanger depends in particular on the uniformity of temperature inside the body and on its capacity to promote heat exchange between the refrigerant circulating inside and the air flowing therethrough.

The capacity to promote heat exchange increases with the size of the exchange area with the air, which is, for an exchanger of given volume, in particular proportional to the air opening, i.e. to the height h beneath the tanks 12, 13.

For an exchanger of given dimensions (height H, thickness p, width I and a given number of plates), one solution for increasing the exchange area would therefore consist in increasing the height h beneath the tanks, i.e. in decreasing the height h' of the upper and/or lower tanks.

However, decreasing the height of the upper and/or lower tanks tends to increase head loss inside the exchanger, which disrupts the circulation of refrigerant thereinside, negatively affects the uniformity of temperature inside the exchanger and its efficiency. There is therefore a need to provide exchangers having improved efficiency for a given volume.

3. Objectives of the invention

In particular, one objective of the invention is to provide an effective solution to at least some of these various problems.

In particular, according to at least one embodiment, one objective of the invention is to provide a plate-type heat exchanger having improved efficiency for a given volume.

In particular, one objective of the invention, according to at least one embodiment, is to provide such a heat exchanger inside which the temperature is more uniform.

Another objective of the invention, according to at least one embodiment, is to provide such a heat exchanger inside which head loss is decreased.

Another objective of the invention, according to at least one embodiment, is to provide such a heat exchanger having a larger air opening.

Another objective of the invention, in at least one embodiment, is to provide such a heat exchanger having a modular design, in particular in terms of number of passes and/or positioning of the inlet/outlet of the exchanger.

Another objective of the invention, in at least one embodiment, is to provide such a heat exchanger having a simple design and/or being straightforward to manufacture and/or economical.

4. Disclosure of the invention

To achieve this, the invention provides a heat exchanger comprising a stack of plates, each plate comprising:

three first refrigerant distribution tanks, positioned at a first end; and a second refrigerant distribution tank, positioned at a second end, and delimiting three internal channels for circulating a refrigerant, each of said channels being in fluidic communication with two tanks, each of said tanks having a passage for refrigerant, the size of said passage of each of said second tanks being smaller than that of at least one of said first tanks along the longitudinal axis of said plates, said second tanks extending laterally beyond the channel with which they are respectively in fluidic communication. Thus, according to this aspect of the invention, the fact that the height of the passage opening of the two tanks placed at one end of the exchanger is less than that of at least one first tank placed at the other end of the exchanger makes it possible to increase the height beneath the tanks and thus to increase the exchange area with the air.

The fact that this tank extends laterally beyond the channel with which it is in communication makes it possible to compensate, at least partly, for the decrease in its section caused by the decrease in its height, and thus to limit head loss due to the flow of air out of the exchanger resulting from the increase in the height beneath the tanks.

The invention therefore makes it possible to provide an exchanger having three rows of channels (or tubes) providing a higher level of performance, for the same volume, than an exchanger having three rows of tubes according to the prior art using three tanks at each end rather than using three tanks at one end and a single tank at the other.

According to one conceivable preferred feature, each of said channels is in fluidic communication with two tanks having passages of substantially equal section.

In this case in which the tanks to which a channel is linked at each of its ends have substantially identical passage sections, the head loss due to the flow of refrigerant into the exchanger is limited. This makes it possible to improve the uniformity of temperature inside the exchanger and to increase its efficiency.

According to another conceivable preferred feature, said passages of the assembly of said tanks have substantially equal sections.

In this case in which all of the tanks have substantially identical passage sections, the head loss due to the flow of refrigerant into the assembly of the channels is limited. This makes it possible to improve the uniformity of temperature inside the exchanger and its efficiency still further.

According to one possible feature, the width of said second tanks is substantially equal to the width of said plates.

The height beneath the upper and lower tanks is then at its lowest and the air opening at its maximum to increase the exchange area with the air. According to one possible feature, said channels extend essentially in parallel with respect to one another.

According to one possible feature, two of said channels of each of said plates are in fluidic communication.

The fact that two channels are in fluidic communication makes it possible to omit two tanks on one side of the exchanger to free space for the single tank located on this side to extend laterally to have a minimum height for the same section and thus to increase the air opening of the exchanger.

In this case, according to one possible feature, the three channels of each of said plates comprise:

a first channel in fluidic communication with a first of said first tanks and with said second tank;

second and third consecutive channels, respectively in fluidic communication with a second and a third of said first tanks at one end, are in fluidic communication with one another at the opposite end.

This corresponds to one possible plate configuration according to the invention, which makes it possible to provide an exchanger having a large air opening and high efficiency in a straightforward manner.

According to one possible feature, said channels in fluidic communication form a U having a bottom oriented on the side of said second tank.

It is thus possible to free space beneath the U-shaped junction of the channels in fluidic communication to free space there for the second tank.

According to one possible feature, said second tank of each of said plates then extends over at least part of the width of the U.

According to one possible feature, said plates delimit pairwise a passage for the circulation of air between them.

In this case, said air passages house inserts which make it possible to improve the exchanges between the air flowing through the body of the exchanger and the refrigerant circulating thereinside.

According to one possible feature, each of said plates comprises two half-plates that are joined to one another, said half-plates being symmetric with respect to their joint face. The plates of a heat exchanger according to the invention may thus be manufactured in a very straightforward and economical manner on the basis of half-plates made of pressed sheet metal, for example made of clad metal, then joined together by brazing, for example.

According to one possible feature, the walls of said plates comprise deformations extending transversely into said channels.

This implementation allows the pressure resistance of the plates and of the exchanger to be substantially increased.

In this case, the ends of said deformations extending facing one another, of two half-plates that are joined to one another, come into contact with one another.

According to one possible feature, said three first tanks and said second tanks are respectively in fluidic communication to allow said refrigerant to pass from plate to plate, said exchanger comprising at least one dividing plate, each dividing plate being interposed between two plates to form two groups of plates on either side, some of the tanks of each of said dividing plates being closed off to multiply the number of passes of said refrigerant through said exchanger.

The use of one or more dividing plates makes it possible to increase the number of passes of the exchanger. Thus, without a dividing plate, an exchanger according to the invention is of the type having three rows of tubes and three passes. With one dividing plate, it becomes an exchanger of the type having three rows of tubes and six passes. With two dividing plates, it becomes an exchanger of the type having three rows of tubes and eight passes, and so on.

According to one possible feature, a heat exchanger according to the invention comprises first and second end plates that are configured to define a path for the circulation of refrigerant inside said exchanger.

These plates make it possible to isolate the tanks from the outside and to place them in communication with one another according to the path that it is desired for the refrigerant to follow inside the exchanger.

According to one possible feature, said first and second ends are respectively intended to be oriented towards the top and towards the bottom of said exchanger. 5. List of figures

Other features and advantages of the invention will become more apparent upon reading the following description of particular embodiments, which is given by way of simple nonlimiting illustrative example, and the appended drawings, in which:

Figures 1 and 2 illustrate examples of plate heat exchangers according to the prior art;

Figures 3 to 6 illustrate one exemplary embodiment of a plate of a heat exchanger according to the invention;

Figure 7 illustrates a perspective view of one example of a heat exchanger according to the invention;

Figures 8 and 9 illustrate two modes for the circulation of refrigerant through an exchanger according to Figure 7;

Figure 10 illustrates a partial view of an exchanger according to Figure 7.

6. Description of particular embodiments

6.1. Brief summary of the invention

The present invention consists in producing a heat exchanger by stacking plates defining three internal channels and comprising three refrigerant distribution tanks at one end and a single refrigerant distribution tank at the other end, the single tank:

having a passage opening of smaller size than that of the other tanks placed at the other end on a longitudinal axis along the plates; and extending laterally beyond the channel leading thereinto.

The air opening of the exchanger, and its efficiency, are improved by decreasing the height of the passage opening of the single tank placed at one end of each plate of the exchanger with respect to that of the tanks placed at the other end of each plate.

The head loss inside the exchanger caused by the decrease in the height of the single tank placed at one end of each plate with a view to increasing the air opening is at least partly compensated for by the fact that this single tank extends laterally beyond the channel with which it is in communication. The invention therefore makes it possible to provide an exchanger having three rows of channels (or tubes) providing a higher level of performance, for the same volume, than an exchanger having three rows of tubes according to the prior art using three tanks at each end rather than using three tanks at one end and a single tank at the other.

6.2. Plate architecture

An example of a plate according to the invention is presented with reference to Figures 3 to 6.

As shown in Figure 3, a plate 2 consists of two half-plates 20 joined together.

Each half-plate 20 comprises a wall 27 through a first end of which three first openings for the passage of refrigerant 21 pass and through a second end of which (i.e. the opposite end) a second opening for the passage of refrigerant 22 passes.

The first and second ends will hereinafter respectively be referred to as the upper and lower ends, and the first and second openings will hereinafter respectively be referred to as the upper and lower openings. These upper and lower positions could however be inverted.

The peripheral edge of each opening 21 , 22 comprises a boss 23 which protrudes outwards from the half-plate 20.

A first internal partitioning portion 24 protrudes from the inner side of each half-plate 20. It extends from the upper end of the half-plate between first and second upper openings 21 down to the lower opening 22 located at the other end.

A second internal partitioning portion 25 protrudes from the inner side of each half-plate 20. It extends from the upper end of the half-plate between the second and third upper openings 21 without reaching the lower opening 22 located at the other end.

The peripheral inner edge of the half-plate 20 forms a joint face 26 with the inner surface of the internal partitioning portions 24, 25. This joint face 26 is offset with respect to the inner surface of the wall 27 of the half-plate 20 to form three channel portions 28, 29, 30 inside each half-plate. The first channel portion 28 links the first upper opening 21 and the lower opening 22. The second channel portion 29 leads into the second upper opening 21 and is in communication with the third channel portion 30 which leads into the third upper opening 21 . The second 29 and third 30 channel portions essentially form a "U" and are in fluidic communication at the end opposite that at which they are in communication with the upper openings 21 .

Reliefs or deformations 31 in the form of ribs or bosses (dimples) extend from the inner surface of each half-plate towards the inside of each channel portion 28, 29, 30 up to the joint face 26.

The half-plates 20 are preferably produced by pressing.

The two half-plates 20 forming a plate 2 are symmetrical with respect to their joint face 26. They will for example be made of clad metal and joined together by brazing.

Once joined together, two half-plates 20 form a plate 2 delimiting first 280, second 290, and third 300 internal channels for circulating a refrigerant (respectively formed by the channel portions 28, 29, 30 of the half-plates).

The channels are essentially parallel to one another. They preferably have a section that is identical in a plane perpendicular to their longitudinal axis.

The term "section" is understood to mean the passage area defined by the peripheral edge of the element under consideration (channel, passage for refrigerant, etc.). Having an identical section means having an identical passage area but not necessarily a passage peripheral edge of identical shape.

An upper end of the plate 2 comprises first 210i, second 2102 and third

2103 upper refrigerant distribution tanks, each upper tank being formed by the corresponding upper openings 21 and bosses 23 and comprises a passage for refrigerant formed by the corresponding passage openings. The lower end of the plate comprises a single lower refrigerant distribution tank 220 formed by the corresponding lower openings 22 and bosses 23 and comprises a passage for refrigerant formed by the corresponding passage openings.

The first channel 280 leads, on either side, into the first upper tank 210i and into the lower tank 220. The second channel 290 leads into the second upper tank 21 02, and is in fluidic communication with the third channel 300 which leads into the third upper tank 2103.

The first channel 280 is separated from the others by the first partition 240 formed by joining the partitioning portions 24.

The channels 290 and 300 are separated by the second partition 250 formed by joining the partitioning portions 25. However, these second and third channels are in fluidic communication due to the partition 250 not extending all the way along the channels, thereby forming a passage 4 therebetween. They are in fluidic communication at the end opposite that at which they are in communication with the upper tanks 2102, 21 03. The section of the passage 4 will preferably be equal to that of a channel 290 or 300 so as to limit head loss inside the exchanger.

The second 290 and the third 300 channels form a "U" which extends from the side of the lower tank 220.

Each channel is in communication with two tanks, either directly (the case of the first channel 280) or via another channel (the case of the second and third channels 290, 300, which are in fluidic communication with one another).

The section of the passages for refrigerant through the first 21 0i , second 21 02, and third 21 03 upper tanks and through the lower tank 220 are essentially equal.

At the very least, the two tanks with which one and the same channel is in fluidic communication will have passages for refrigerant having essentially equal sections. This makes it possible to limit head loss in the channel under consideration. Of course, the fact of all tanks having essentially equal passage sections makes it possible to limit head loss in the overall body of the evaporator.

The dimension of the lower tank 220 along the longitudinal axis of the plates is however smaller than the dimension of the first 210i , second 21 02, and third 21 03 upper tanks along the longitudinal axis of the plates. The longitudinal axis of a plate extends between its first and second ends. To achieve this, the lower tank 220 extends laterally beyond the first channel 280 at least partly beneath the bottom of the "U" formed by the channels 290 and 300, and preferably across the entire width L of the plate. The greater the width of the lower tank 220, the smaller the dimension of the plate along the longitudinal axis, for a given passage section, and the greater the height h beneath the tanks.

This makes it possible to increase the exchange area with the air while limiting head loss, and thus to improve the uniformity of temperature in the exchanger and its efficiency for a given volume.

The width L of the plate, along a direction inscribed in a plane passing through the longitudinal axes of the channels and perpendicular thereto, is preferably less than or equal to 40 millimetres.

6.3. Exchanger architecture

Figure 7 illustrates a heat exchanger 5 according to the invention. As shown, such an exchanger 5 comprises a stack of a plurality of identical plates 2.

The plates 2 are bonded to one another at the level of the bosses 23 and placed such that:

the first upper tanks 210i are in communication with one another to form a first upper reservoir 51 ;

the second upper tanks 2102 are in communication with one another to form a second upper reservoir 52;

the third upper tanks 2103 are in communication with one another to form a third upper reservoir 53;

the lower tanks 220 are in communication with one another to form a fourth, lower reservoir 54.

By virtue of the bosses 23, an air flow space 61 is formed between consecutive plates 2 (see figure 10).

Each of these air flow spaces is preferably filled by an insert 62 conventionally allowing heat exchange between the air flowing on the outside of the exchanger and the refrigerant circulating thereinside to be promoted.

The heat exchanger 5 comprises a refrigerant inlet pipe 55 and a refrigerant outlet pipe 56. The inlet pipe 55 is linked to the second 52 or to the third 53 reservoir while the outlet pipe 56 is linked to the first reservoir 51 . In one variant, the inlet pipe 55 will be linked to the first reservoir 51 while the outlet pipe 56 will be linked to the second 52 or to the third 53 reservoir.

The heat exchanger 5 comprises a dividing plate 2' which is interposed between two groups 59 and 60 of plate 2 stacks. The number of plates 2 of each group 59 and 60 may be the same or different.

The dividing plate 2' is identical to the other plates 2. However, the first upper tank 210i and one of either the second and third upper tanks 2102 and 2103 are closed off.

The choice of whether to close off either the second or third upper tank 2102, 2103 will depend on whether it is desired for the refrigerant to enter the exchanger via the second 52 or third 53 reservoir, or potentially into the first reservoir 51 .

The heat exchanger comprises a first end plate 57 on the side of the pipes 55 and 56 and a second end plate 58 at the opposite end.

As will become more clearly apparent below, the first end plate 57 is configured to define the inlet and the outlet of the exchanger while the second end plate 58 is configured to place the first independent channel 280 in fluidic communication with one of the second 290 and third 300 channels, which are in fluidic communication with one another, to define a determined circulation path for the refrigerant through the exchanger.

An air flow space 61 is formed between each end plate and the plate adjacent thereto.

Figure 8 illustrates the circulation of the refrigerant inside the heat exchanger when the inlet pipe 55 is linked to the second reservoir 52 located in the middle of the body of the exchanger and the outlet pipe 56 is linked to the first reservoir 51 of the first group 59.

For the sake of simplicity, only one plate 2 of each group 59 and 60 is shown, although each group comprises multiple plates 2.

In this case, the first 210i and second 2102 upper tanks of the dividing plate 2' are closed off.

The first end plate 57 is configured: to close off the lower tank 220 of the first plate 2 with respect to the outside;

to place the pipes 55 and 56 in communication with the upper tanks

2102 and 2101 , respectively, of the first plate 2;

to close off the upper tank 2103 of the first plate 2 with respect to the outside.

The second end plate 58 is configured:

to close off the lower 220 and upper 210i , 2102, 2103 tanks of the last plate 2 with respect to the outside;

to place the first 210i and second 2102 upper tanks of the last plate in fluidic communication.

The refrigerant is let into the heat exchanger via the inlet pipe 55 which leads into the second reservoir 52 of the group 59. The refrigerant then flows into the second upper tank 2102 of each plate to pass from plate to plate of the first group 59. It flows from these second upper tanks 2102 through the second channel 290 of each plate in a first pass.

The refrigerant next passes through the passages 4 to flow through the third channel 300 of each plate 2 in a second pass until it is located in the third reservoir 53 of the group 59.

The refrigerant next passes into the second group 60 of plates by flowing from the third reservoir 53 of the first group 59 into the third reservoir 53 of the second group 60 by passing through the third upper tank 2103 of the dividing plate 2'.

The refrigerant then flows into the third upper tank 2103 of each plate to pass from plate to plate of the second group 60. It flows from these third upper tanks 2103 through the third channel 300 of each plate in a third pass.

The refrigerant next passes through the passages 4 to flow through the second channel 290 of each plate 2 in a fourth pass until it is located in the second reservoir 52 of the group 60.

The refrigerant next flows from the second reservoir 52 to the first reservoir 51 via the second end plate 58. It then flows, in a fifth pass, through each first channel 280 of each plate of the second group 60 in the direction of the lower tanks 220 until it is located in the fourth reservoir 54. It next passes through the lower tank 220 of the dividing plate 2' to flow into the fourth reservoir 54 of the first group 59 of plates 2. The refrigerant then flows through the first channel 280 of each plate 2 of the first group 59 to the first upper tank 210i in a sixth pass.

The refrigerant then flows into the first reservoir 51 and leaves the exchanger via the outlet pipe 56.

Figure 9 illustrates the circulation of the refrigerant inside the heat exchanger when the inlet pipe 55 is linked to the third reservoir 53 and the outlet pipe 56 is linked to the first reservoir 51 of the first group 59.

For the sake of simplicity, only one plate 2 of each group 59 and 60 is shown, although each group comprises multiple plates 2.

In this case, the first 210i and third 2103 upper tanks of the dividing plate 2' are closed off.

The first end plate 57 is configured:

to close off the lower tank 220 of the first plate 2 with respect to the outside;

to place the pipes 55 and 56 in communication with the upper tanks

2103 and 210i , respectively, of the first plate 2;

to close off the upper tank 2102 of the first plate 2 with respect to the outside.

The second end plate 58 is configured:

to close off the lower 220 and upper 210i , 2102, 2103 tanks of the last plate 2 with respect to the outside;

to place the first 210i and third 2103 upper tanks of the last plate in fluidic communication.

The refrigerant is let into the heat exchanger via the inlet pipe 55 which leads into the third reservoir 53 of the group 59. The refrigerant then flows into the third upper tank 2103 of each plate to pass from plate to plate of the first group 59. It flows from these third upper tanks 2103 through the third channel 300 of each plate in a first pass.

It next passes through the passages 4 to flow through the second channel 290 of each plate 2 in a second pass until it is located in the second reservoir 52 of the group 59. The refrigerant next passes into the second group 60 of plates by flowing from the second reservoir 52 of the first group 59 into the second reservoir 52 of the second group 60 by passing through the second upper tank 2102 of the dividing plate 2'.

The refrigerant then flows into the second upper tank 2102 of each plate to pass from plate to plate of the second group 60. It flows from these second upper tanks 2102 through the second channel 290 of each plate of the group 60 in a third pass.

It next passes through the passages 4 to flow through the third channel 300 of each plate 2 in a fourth pass until it is located in the third reservoir 53 of the group 60.

The refrigerant then flows from the third reservoir 53 to the first reservoir 51 of the group 60 via the second end plate 58. It then flows, in a fifth pass, through each first channel 280 of each plate of the second group 60 in the direction of the lower tanks 220 until it is located in the fourth reservoir 54 of the group 60.

It then passes through the lower tank 220 of the dividing plate 2' to flow into the fourth reservoir 54 of the first group 59 of plates 2. The refrigerant next flows through the first channel 280 of each plate 2 of the first group 59 in a sixth pass until reaching the first upper tank 210i. It then flows into the first reservoir 51 and leaves the exchanger via the outlet pipe 56.

According to these two variants, the heat exchanger is of the type having three rows of channels (or tubes) and six passes.

The number of passes could however be increased by increasing the number of dividing plates separating the plates into multiple groups.

The use of any dividing plate will make it possible to obtain an exchanger of the type having three rows of channels (or tubes) and three passes.

6.5. Variants

The lower and upper positions of the exchanger ends could be inverted such that the lower end could comprise three tanks and the upper end a single tank.

A heat exchanger according to the invention may for example be used to carry out the function of an evaporator.

The present invention is particularly applicable to refrigerant-based thermodynamic circuits, in particular heating, ventilation and/or air- conditioning installations, and in particular to the field of equipment for automotive vehicles.