HEAT EXCHANGER FOR A MOTOR VEHICLE

Description

technical field

[0001] The present invention relates to the field of heat exchangers, particularly heat exchangers for motor vehicles. Such exchangers can be used in a vehicle's thermal conditioning system. This system ensures temperature regulation of various vehicle components, such as the passenger compartment or an electrical energy storage battery, when the vehicle is electrically powered. Heat exchange is primarily achieved through the compression and expansion of a refrigerant circulating in a circuit containing several heat exchangers. A compressor forces the refrigerant to a high pressure and circulate it within the circuit. Previous technique

[0002] The refrigerant circuit typically includes a first heat exchanger that condenses the high-pressure refrigerant discharged by the compressor, or cools it in the case of a supercritical fluid. The refrigerant circulates in this first exchanger and transfers heat to an airflow passing through it.

[0003] Furthermore, it is also common practice to cool a component of the vehicle's powertrain using a heat transfer fluid. For this, a heat transfer fluid absorbs heat from the powertrain component and dissipates heat, for example, into an airflow at a secondary heat exchanger.

[0004] Integrating these two heat exchangers into the vehicle can be challenging, particularly due to their size when they are offset from each other to simultaneously receive the same airflow. To minimize space, the two exchangers can also be aligned with the airflow direction so that they are successively traversed by the same airflow. However, the heating of the air as it passes through the upstream exchanger tends to reduce the efficiency of the downstream exchanger.

[0005] US-A-2019143921 describes a heat exchanger according to the preamble of claim 1.

[0006] The present invention aims to provide a solution that is easier to integrate because it is more compact and provides improved thermodynamic performance. Summary

[0007] To this end, the present invention proposes a heat exchanger for motor vehicles, comprising: a first heat exchange section configured to allow heat exchange between a refrigerant fluid and an airflow, the first heat exchange section comprising a first bundle of tubes forming a set of refrigerant circulation channels configured to be arranged in the airflow, a second heat exchange section configured to allow heat exchange between a heat transfer fluid and the airflow, the second heat exchange section comprising a second tube bundle forming a set of heat transfer fluid circulation channels configured to be arranged in the airflow, in which the tubes of the first tube bundle have a U-shape comprising a first branch and a second branch connected by a base, in which the first branch is arranged upstream of the second branch in a direction of airflow, and in which the second tube bundle is arranged between the first and second branches of the tubes of the first tube bundle in the direction of airflow.

[0008] The U-shaped design of the tubes in the first tube bundle increases the length of the sections involved in heat exchange within the first heat exchanger section, while minimizing the frontal surface area of ​​the exchanger. Since the second heat exchanger section is located within the free volume formed by the spacing of the branches of each of the U-shaped tubes in the first tube bundle, its presence does not alter the external volume of the heat exchanger. The heat exchanger thus has a very compact shape. Furthermore, the first tube branch is positioned upstream of the second heat exchanger section for airflow circulation, and this second section is itself upstream of the second tube branch of the first heat exchanger section. Each tube, or tube segment, therefore receives an airflow with a temperature appropriate to the temperature of the fluid circulating within it.In other words, the first branch of the first heat exchange section receives a flow of cool ambient air that has not been heated by passing through a heat exchanger, thus increasing its efficiency. The airflow exiting the first branch of the first heat exchange section has a sufficiently low temperature to ensure good heat exchange efficiency with the second heat exchange section. Similarly, the airflow heated by passing through the second heat exchange section still has a sufficiently low temperature to ensure good heat exchange efficiency with the refrigerant circulating in the second branch of the first heat exchange section. The efficiency of the heat exchanger, for a given footprint, is thus optimized. Furthermore, any maximum temperature constraints of the heat transfer fluid at the outlet of the second heat exchange section can be met thanks to the proposed arrangement.

[0009] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination: According to one aspect of the proposed heat exchanger, the second tube bundle is arranged downstream of the first branch of the tubes of the first bundle and upstream of the second branch of the tubes of the first bundle.

[0010] According to one operating mode of the heat exchanger, the first heat exchange section functions as a condenser of the refrigerant fluid.

[0011] According to one operating mode of the exchanger, the refrigerant circulating in the first heat exchange section gives up heat to the airflow.

[0012] According to this operating mode, the refrigerant flows from the second branch of the tubes to the first branch of the tubes.

[0013] According to another operating mode of the heat exchanger, the first heat exchange section functions as an evaporator of the refrigerant fluid.

[0014] According to one operating mode, the refrigerant circulating in the first heat exchange section receives heat from the airflow.

[0015] According to this operating mode, the refrigerant flows from the first branch of the tubes to the second branch of the tubes.

[0016] According to an example of heat exchanger implementation, the airflow is an airflow from outside the vehicle.

[0017] According to another example of heat exchanger implementation, the airflow is an internal airflow to the vehicle's passenger compartment.

[0018] In a heat exchanger application, the refrigerant can be a chemical fluid, such as R1234yf, or R134a.

[0019] In another application of the heat exchanger, the refrigerant can be R744 or R290.

[0020] The heat transfer fluid can be a mixture of water and glycol.

[0021] According to one aspect of the heat exchanger, each tube in the first tube bundle extends in a plane.

[0022] The tubes in the first tube bundle are arranged in parallel planes.

[0023] The tubes in the first tube bundle are aligned in a direction perpendicular to the plane of the tubes.

[0024] According to one embodiment of the heat exchanger, the second tube bundle extends between two parallel planes, these two planes being perpendicular to the plane of the tubes of the first bundle.

[0025] The heat exchanger thus has a compact shape, with the second heat exchange section filling the space left free between all the first branches of the tubes of the first heat exchange section and all the second branches of the tubes.

[0026] The first branch of a tube in the first tube bundle is connected to the first branch of a subsequent tube by a first set of fins.

[0027] The second branch of a tube in the first tube bundle is connected to the second branch of a consecutive tube by a second set of fins.

[0028] The fins improve heat transfer between the airflow and the refrigerant circulating in the tubes of the first heat exchange section.

[0029] The fins have slots to allow airflow.

[0030] According to one aspect of the heat exchanger, the base of a tube in the first tube bundle is spaced from the base of a subsequent tube.

[0031] When the first heat exchanger section operates as an evaporator while the outside temperature is below or near 0°C, ice can form on at least some of the tubes in the tube bundle. When the ice melts, water flows down the tubes to their base. The spacing between adjacent tubes allows the water to drain away and prevents it from accumulating at the base. This reduces the risk of the first heat exchanger section freezing again.

[0032] The outer edge of the tubes in the first tube bundle has an oblong cross-section. The tubes in the first tube bundle are, for example, microchannel tubes.

[0033] According to one embodiment of the heat exchanger, the outer perimeter of the tubes in the first tube bundle has an oblong cross-section, defining a major axis and a minor axis, and the major axis of the first branch of the tubes is parallel to the airflow.

[0034] According to one embodiment, the major axis of the second branch of the tubes is parallel to the airflow.

[0035] The tubes of the first tube bundle can be twisted in the vicinity of a junction between the first branch and the base.

[0036] Similarly, the tubes of the first tube bundle can be twisted in the vicinity of a junction between the base and the second branch.

[0037] In this embodiment, the major axis of the base of the tubes is perpendicular to the airflow.

[0038] According to an example of heat exchanger implementation, the base of the tubes in the first tube bundle defines a lower side of the heat exchanger when the heat exchanger is in its nominal installation position in the vehicle.

[0039] According to this example of heat exchanger implementation, the first branch of the tubes in the first tube bundle extends along a vertical axis when the heat exchanger is in its nominal installation position in the vehicle.

[0040] This configuration facilitates the drainage of water from the heat exchanger defrosting process when ice accumulates on the surface of the first and / or second heat exchange section and melts. The liquid water can flow freely along the tubes without encountering any obstructions that could cause a blockage.

[0041] According to another implementation example, the base of the tubes in the first bundle defines one lateral side of the heat exchanger when the heat exchanger is in its nominal installation position in the vehicle.

[0042] According to this example of heat exchanger implementation, the first branch of the tubes in the first tube bundle extends along a horizontal axis when the heat exchanger is in its nominal installation position in the vehicle.

[0043] This configuration prevents potential corrosion of the lowest part of the heat exchanger due to accumulated moisture. Furthermore, this configuration reduces the number of tubes required when the heat exchanger has a low height and a large width. Height refers to the dimension along the vertical axis, and width to the dimension along the transverse axis of the vehicle when the exchanger is installed in its nominal configuration. This simplifies the manufacturing of the exchanger for applications where the vehicle has a low front end.

[0044] One end of the tubes in the first tube bundle opens into a first distributor configured to distribute the refrigerant fluid between all the tubes in the first tube bundle.

[0045] The first distributor extends transversely to the axis of the tubes in the first tube bundle.

[0046] The first dispenser is cylindrical in shape.

[0047] The first distributor includes a refrigerant fluid inlet.

[0048] A second end of the tubes in the first tube bundle opens into a first manifold configured to collect the refrigerant fluid from all the tubes in the first tube bundle.

[0049] The first collector extends transversely to the axis of the tubes in the first tube bundle.

[0050] The first collector is cylindrical in shape.

[0051] The first manifold includes a refrigerant outlet.

[0052] The first collector and the first distributor extend in parallel directions.

[0053] The tubes in the first tube bundle are identical.

[0054] According to one embodiment, the refrigerant inlet and refrigerant outlet are opposite each other in a direction perpendicular to the axis of the first distributor.

[0055] According to an example of heat exchanger implementation, the first distributor is positioned downstream of the first manifold in the direction of airflow when the heat exchanger is in its nominal installation position in the vehicle.

[0056] In another example of heat exchanger implementation, the first manifold is positioned downstream of the first distributor in the direction of airflow when the heat exchanger is in its nominal installation position in the vehicle.

[0057] According to one embodiment of the heat exchanger, the first branch of the tubes in the first tube bundle and the second branch of the tubes in the first tube bundle have the same length. The length of the first and second branches of the tubes in the first tube bundle is, for example, between 300 millimeters and 600 millimeters.

[0058] According to another embodiment of the heat exchanger, the length of the first branch of the tubes in the first tube bundle is less than the length of the second branch of the tubes in the first tube bundle.

[0059] The amount of material used to create the first tube bundle is thus reduced. Furthermore, some of the tubes in the second tube bundle directly receive the airflow F, without any tubes from the first bundle being positioned upstream. The cost of the heat exchanger can be reduced without compromising its efficiency.

[0060] In this case, the length of the first branch of the tubes in the first tube bundle is, for example, between 100 millimeters and 300 millimeters. The length of the second branch of the tubes in the first tube bundle is, for example, between 300 millimeters and 600 millimeters.

[0061] According to one embodiment, the tubes of the second tube bundle extend transversely to the tubes of the first tube bundle.

[0062] The tubes in the second tube bundle are parallel to each other.

[0063] The tubes in the second tube bundle are identical.

[0064] The second heat exchange section is roughly parallelepiped in shape.

[0065] One end of the tubes in the second tube bundle opens into a second distributor configured to distribute the heat transfer fluid between all the tubes in the second tube bundle.

[0066] The second distributor extends transversely to the axis of the tubes in the second tube bundle.

[0067] The second distributor includes a heat transfer fluid inlet.

[0068] A second end of the tubes in the second tube bundle opens into a second manifold configured to collect the heat transfer fluid from all the tubes in the second tube bundle.

[0069] The second collector extends transversely to the axis of the tubes in the second tube bundle.

[0070] The second manifold includes a heat transfer fluid outlet.

[0071] The perimeter of the tubes in the second tube bundle has an oblong cross-section.

[0072] According to one embodiment, the heat exchanger includes a support disposed between at least a portion of the tubes of the second tube bundle and the base of at least a portion of the tubes of the first tube bundle.

[0073] The heat exchanger may include a support connecting the second heat exchange section to the base of the tubes in the first tube bundle.

[0074] The support provides mechanical support for the bases of the tubes in the first heat exchange section relative to the second heat exchange section, which helps to reduce the propagation of vehicle vibrations in the tubes of the first heat exchange section.

[0075] According to an example of an embodiment of the heat exchanger, the support has a thermal conductivity lower than the thermal conductivity of the tubes of the first bundle, preferably less than 10% of the thermal conductivity of the tubes of the first bundle.

[0076] Thus, the support thermally insulates the base of the tubes in the first heat exchange section from the second heat exchange section, preventing the formation of a thermal bridge.

[0077] The support is, for example, made of plastic, in particular polyamide reinforced with glass fibers (for example PA6 reinforced with 30% glass fibers) or polypropylene reinforced with glass fibers (for example PP reinforced with 30% glass fibers).

[0078] The support can secure the second heat exchange section to the base of the tubes in the first tube bundle.

[0079] According to one embodiment, the second heat exchange section includes a face arranged opposite the base of the tubes of the first tube bundle, and the support connects the base of the tubes of the first tube bundle with the face arranged opposite it.

[0080] According to one embodiment of the heat exchanger, the support includes a sealed wall connecting the second heat exchange section to the base of the tubes of the first tube bundle so as to block airflow between the second heat exchange section and the base of the tubes of the first tube bundle.

[0081] The airtight wall prevents airflow from entering the space between the base of the first tube bundle and the opposite face of the second heat exchanger section. This prevents any of the airflow F from exiting the heat exchanger without exchanging heat with the second heat exchanger section.

[0082] The support may have a trapezoidal cross-section.

[0083] The smaller base of the trapezoid is opposite the second heat exchange section. The larger base is opposite the base of the tubes in the first tube bundle.

[0084] Thus, the support guides the airflow from near the base of the tubes in the first tube bundle towards the second heat exchange section. Furthermore, water from the defrosting phases can also be guided to the bottom of the exchanger, facilitating its drainage.

[0085] According to one embodiment, the support is fixed to the base of each of the tubes in the first bundle of tubes.

[0086] The support provides mechanical stability to the tubes relative to each other, thus limiting the amplitude of vibrations. The mechanical robustness of the heat exchanger is improved.

[0087] The support is, for example, overmolded onto the base of the tubes in the first tube bundle.

[0088] Alternatively, the face of the second heat exchange section can be joined to the base of the tubes of the first heat exchange section, in particular by brazing.

[0089] According to one embodiment, the tubes of the second tube bundle extend parallel to the first branch of the tubes of the first tube bundle.

[0090] This arrangement allows the second manifold or distributor to be positioned opposite the base of the tubes in the first tube bundle. The base of the refrigerant tubes can then be attached to the second manifold or distributor. The bracket for securing the second heat exchange section to the base of the tubes in the first tube bundle is not required. Furthermore, one of the distributors or manifolds in the second tube bundle can be aligned with the upstream refrigerant manifold / distributor. This minimizes airflow disturbance through the heat exchanger, improving its efficiency for a given footprint. Brief description of the drawings

[0091] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which: [ Fig. 1 ] is a schematic, side and cross-sectional view of a heat exchanger according to a first embodiment of the invention, [ Fig. 2 [ ] is a schematic, front view of the heat exchanger of the figure 1 , [ Fig. 3 ] is a schematic, side and cross-sectional view of a heat exchanger according to a second embodiment of the invention, [ Fig. 4 ] is a schematic detail view, side and cross-sectional, of a variant of a heat exchanger according to the invention, [ Fig. 5 [ ] is a partial schematic, perspective view of a heat exchanger according to the invention. Fig. 6 ] is a partial schematic, top view of three variants of a heat exchanger according to the invention, [ Fig. 7] is a partial schematic view of a tube from the first tube bundle of a heat exchanger according to the invention. Description of the implementation methods

[0092] To facilitate the reading of the figures, the different elements are not necessarily drawn to scale. In these figures, identical elements have the same reference numbers. Some elements or parameters may be indexed, that is, designated, for example, as first element or second element, or first parameter and second parameter, etc. This indexing aims to differentiate between similar, but not identical, elements or parameters. This indexing does not imply any priority of one element or parameter over another, and the designations can be interchanged.

[0093] In the following description, the term "a first element upstream of a second element" means that the first element is placed before the second element with respect to the direction of flow, or path, of a fluid. Similarly, the term "a first element downstream of a second element" means that the first element is placed after the second element with respect to the direction of flow, or path, of the fluid in question.

[0094] The term "a second element is placed between a first element and a third element" means that the shortest path from the first element to the third element passes through the second element.

[0095] When it is specified that a subsystem includes a given element, this does not exclude the presence of other elements in that subsystem.

[0096] The term "exchanger" is equivalent to the term "heat exchanger" as well as the term "thermal exchanger".

[0097] The heat exchanger 50, which will be described below, can be integrated into a thermal conditioning system. The thermal conditioning system comprises a refrigerant circuit and a heat transfer fluid circuit. The refrigerant circuit forms a closed loop in which the refrigerant can circulate. The refrigerant circuit is leak-proof when it is in its nominal operating condition, that is, without any faults or leaks. Similarly, the heat transfer fluid circuit forms a closed and leak-proof loop in which a heat transfer fluid can circulate.

[0098] The thermal conditioning system includes a compressor that compresses the refrigerant to a high-pressure, high-temperature state. This high-pressure, high-temperature refrigerant is then sent to a first heat exchange section 1 of the heat exchanger 50, where it transfers heat to an airflow F. The heat exchanger 50 is, for example, located at the front of the vehicle and receives an airflow F from outside the vehicle's passenger compartment, resulting in particular from the vehicle's movement. The cooled refrigerant then passes through an expansion valve, reducing its pressure, and evaporates in a second heat exchanger. This second heat exchanger is, for example, located within the vehicle's heating, ventilation, and / or air conditioning system, commonly referred to as HVAC.The second heat exchanger thus cools the vehicle's passenger compartment. Alternatively, this second heat exchanger can be a cooling exchanger thermally coupled to an electrical energy storage battery. This second exchanger then cools the battery, particularly during fast charging. In other applications of the thermal conditioning system, the heat exchanger 50 can receive low-pressure refrigerant and evaporate it. These applications correspond to heating or dehumidifying the passenger compartment air.

[0099] The heat transfer fluid circuit of the thermal conditioning system cools a component of the vehicle's electric powertrain. This component may include an electrical energy storage battery, an electronic control module for an electric traction motor, or the motor itself. The heat transfer fluid thus receives heat from the powertrain component, and this heat is dissipated in a second heat exchange section 2 of the heat exchanger 50.

[0100] We have represented on the figure 1 A heat exchanger 50 according to a first embodiment. The heat exchanger 50 is, for example, a heat exchanger for a motor vehicle. In the various figures, the X-axis corresponds to the longitudinal axis of the vehicle, the Y-axis corresponds to the transverse axis, and the Z-axis corresponds to the vertical axis.

[0101] The 50 heat exchanger for motor vehicles includes: a first heat exchange section 1 configured to allow heat exchange between a refrigerant fluid and an airflow F, the first heat exchange section 1 comprising a first bundle 11 of tubes 3 forming a set of refrigerant fluid circulation channels configured to be arranged in the airflow F, a second heat exchange section 2 configured to allow heat exchange between a heat transfer fluid and the airflow F, the second heat exchange section comprising a second bundle 12 of tubes 4 forming a set of heat transfer fluid circulation channels configured to be arranged in the airflow F. Tubes 3 of the first bundle 11 of tubes have a U shape comprising a first branch 5 and a second branch 7 connected by a base 6. The first branch 5 is positioned upstream of the second branch 7 according to an airflow direction F, and the second bundle of tubes 12 is arranged between the first branch 5 and the second branch 7 of the tubes 3 of the first bundle of tubes 1 according to the direction of flow of the airflow F.

[0102] The U-shape of the tubes 3 in the first bundle 11 of tubes 3 increases the length contributing to heat exchange in the first heat exchange section, while limiting the frontal surface area of ​​the heat exchanger 50. Furthermore, a portion of the tubes, forming the first branch 5, receives ambient air directly, unheated by another heat exchanger, thus increasing the efficiency of the heat exchange. The second heat exchange section 2 is located within the free volume formed by the spacing of the branches 5, 7 of each of the U-shaped tubes 3 in the first bundle 11 of tubes. The presence of the second heat exchange section 2 does not alter the external volume of the heat exchanger 50. The heat exchanger 50 therefore has a very compact and thermally optimized shape.

[0103] Furthermore, the first branch 5 of the tubes 3 is positioned, relative to the airflow F, upstream of the second heat exchange section 2, which is itself positioned upstream of the second branch 7 of the tubes 3 of the first heat exchange section 1. Each tube, or portion of a tube, thus receives an airflow with a temperature suitable for the temperature of the fluid circulating within that tube. In other words, the first branch 5 of the first heat exchange section 1 receives a flow of fresh ambient air that has not been heated by passing through a heat exchanger, which increases its efficiency for heat exchange. The airflow exiting the first branch 5 of the first heat exchange section 1 has a sufficiently low temperature to ensure good heat exchange efficiency with the fluid circulating in the second heat exchange section 2.Similarly, the airflow heated by its passage through the second heat exchange section 2 still has a temperature low enough to guarantee good exchange efficiency with the refrigerant circulating in the second branch 7 of the first heat exchange section 1. The efficiency of the heat exchanger 50, for a given footprint, is thus optimized.

[0104] The fact that the tubes of the first bundle 11 have a U-shape means that the tubes comprise a first straight section, called the first branch 5, fluidically connected to a second straight section, called the second branch 7, by an intermediate section called the base 6. The first branch 5 and the second branch 7 extend parallel to each other. The intermediate section 6 extends transversely to the first branch 5 and the second branch 7. The intermediate section is straight. The first branch 5, the second branch 7, and the intermediate section 6 are arranged in the same plane. According to an alternative (not shown), the intermediate section may have a curved shape.

[0105] The second bundle of tubes 12 is arranged downstream of the first branch of tubes 3 of the first bundle 11 and upstream of the second branch 7 of tubes 3 of the first bundle 11.

[0106] According to one operating mode of the heat exchanger 50, the first heat exchange section 1 functions as a condenser of the refrigerant fluid.

[0107] According to this operating mode of the heat exchanger 50, the refrigerant circulating in the first heat exchange section 1 transfers heat to the airflow F. The same occurs when the refrigerant used is in a supercritical state. In this case, the heat exchanger 50 functions as a cooler for the refrigerant, without condensation. Such operation occurs, for example, when the refrigerant used is R744a.

[0108] According to this mode of operation in condenser and / or cooler, the refrigerant flows from the second branch 7 of the tubes 3 to the first branch 5 of the tubes 3. In other words, the hottest refrigerant arrives in the first heat exchange section 1 through the portion of the tubes arranged furthest downstream according to the circulation of the air flow F.

[0109] According to another operating mode of the heat exchanger 50, the first heat exchange section 1 functions as an evaporator of the refrigerant fluid.

[0110] According to this operating mode, the refrigerant circulating in the first heat exchange section 1 receives heat from the airflow F. This operating mode corresponds, for example, to the heat pump mode.

[0111] According to this operating mode, the refrigerant flows from the first branch 5 of tubes 3 to the second branch 7 of tubes 3. In other words, the refrigerant enters the first heat exchange section 1 via the upstream portion of the tubes, following the airflow direction F. Preferably, the direction of refrigerant flow is reversed depending on whether the heat exchanger 50 is operating as a condenser or an evaporator. This reversal of the flow direction, depending on the operating mode of the heat exchanger, is optional.

[0112] According to an example of the implementation of the heat exchanger 50, the airflow F is an airflow external to the vehicle. In this case, the exchanger 50 is, for example, located at the front of the vehicle, behind the grille.

[0113] According to another example of the implementation of the heat exchanger 50, the airflow F is an interior airflow within the vehicle's passenger compartment. The exchanger 50 is then located within the vehicle's heating, ventilation and / or air conditioning system.

[0114] In one application of the heat exchanger 50, the refrigerant can be a chemical fluid, such as R1234yf or R134a. In another application of the heat exchanger, the refrigerant can be R744 or R290.

[0115] The refrigerant flows in parallel in tubes 3 of the first bundle 11 of tubes.

[0116] Similarly, the heat transfer fluid circulates in parallel in tubes 4 of the second bundle 12 of tubes. The heat transfer fluid can be a mixture of water and glycol.

[0117] There figure 5This illustrates the first heat exchange section 1 and the second heat exchange section 2 taken in isolation. In other words, the second heat exchange section 2 and the first heat exchange section 1 have been offset along the transverse axis Y so as to be more easily distinguished. As shown schematically in this figure, each tube 3 of the first tube bundle 11 extends in a plane P1. The tubes 3 of the first tube bundle 11 are arranged in parallel planes. On the figure 5 Nine tubes 3 are shown. More generally, the first bundle 11 can contain any number of tubes 3.

[0118] The tubes 3 of the first bundle 11 of tubes are aligned along a direction D perpendicular to the plane of the tubes.

[0119] The tubes 3 of the first beam 11 can be made of aluminum or copper, among other materials. Similarly, the tubes 4 of the second beam 12 can be made of aluminum or copper, for example.

[0120] According to the illustrated example, the second bundle 12 of tubes 4 extends between two parallel planes P2, P24, these two planes being perpendicular to the plane of the tubes 3 of the first bundle 1. The plane P2 is represented on the figure 6 , which is a schematic top view of heat exchanger 50.

[0121] The heat exchanger 50 thus has a compact shape, the second heat exchange section 2 filling the space left free between the set of first branches 5 of the tubes 3 of the first heat exchange section 1 and the set of second branches 7 of the tubes 3.

[0122] As can be seen particularly on the figure 2 , the first branch 5 of a tube 3 of the first bundle 11 of tubes is connected to the first branch of a consecutive tube by a first set of fins 23. In other words, two neighboring tubes of the first bundle 11 of tubes are connected by a set of fins 23.

[0123] In a similar way, the second branch 7 of a tube 3 of the first bundle 11 of tubes is connected to the second branch of a consecutive tube by a second set of fins 24.

[0124] The fins 23, 24 improve the heat transfer between the airflow F and the refrigerant circulating in the tubes 3 of the first heat exchange section 1.

[0125] The fins 23, 24 have slots 25 for the passage of the airflow F. The slots 25 improve the heat transfer between the airflow F and the fins 23, 24.

[0126] Similarly, a tube 4 of the second tube bundle 12 is connected to the adjacent tube by a set of fins 32. These fins improve heat transfer between the airflow F and the heat transfer fluid circulating in the second heat exchanger section 2. On the figure 2, only part of the first 11 tube bundle has been shown, so as to make visible part of the second heat exchange section 2.

[0127] The base 6 of a tube 3 in the first bundle 11 of tubes is spaced from the base of an adjacent tube 3. In other words, the bases of the tubes 3 in the first bundle 11 of tubes are spaced apart. The free space between the bases 6 of two consecutive tubes can be constant.

[0128] When the first heat exchanger section 1 operates as an evaporator while the outside temperature is below or near 0°C, ice can form on at least part of the tubes in the tube bundle 11. When the ice melts, water flows down the tubes 3 to the base 6 of the tubes. The spacing between two adjacent tubes 3 allows the water to flow away and prevents water from accumulating at the base 6 of the tubes. The risk of the first heat exchanger section 1 freezing again is thus reduced.

[0129] The outer circumference of the tubes 3 in the first bundle 11 of tubes has an oblong cross-section. The tubes 3 in the first bundle 11 of tubes are, for example, microchannel tubes. In other words, each tube 3 comprises a plurality of parallel channels. Microchannel tubes are formed by extrusion and then shaped to obtain the desired U-shape. The outer circumference of the tubes 3 in the first bundle 11 of tubes has an oblong cross-section, defining a major axis a and a minor axis b. The major axis a of the first branch 5 of the tubes is parallel to the airflow F. The major axis of the second branch 7 of the tubes 3 is also parallel to the airflow F. The figure 7 schematically details the external shape of tubes 3. In this figure, the micro-channels have not been shown.

[0130] The tubes 3 of the first bundle 11 of tubes can be twisted in the vicinity of a junction 35 between the first branch 5 and the base 6. Similarly, the tubes 3 of the first bundle 11 of tubes can be twisted in the vicinity of a junction 36 between the base 6 and the second branch 7. In other words, the major axis a of a cross-section of a tube 3 rotates progressively by 90° around the extension axis D5 of the first branch 5 of a tube 3 in the junction zone 35 between the first branch 5 and the base 6. This deformation of the tube makes it possible to achieve the U shape without excessively deforming the material of the tubes.

[0131] In this embodiment, the major axis a of the base 6 of the tubes 3 is perpendicular to the airflow F.

[0132] According to an example of the implementation of the heat exchanger 50, the base 6 of the tubes 3 of the first tube bundle 11 defines a lower side of the heat exchanger 50 when the heat exchanger 50 is in its nominal installation position in the vehicle. In other words, the base 6 extends in a plane parallel to the X, Y plane. The various figures represent the heat exchanger 50 oriented in this way.

[0133] The first branch 5 of the tubes 3 of the first bundle 11 of tubes extends along a vertical axis Z when the heat exchanger 50 is in nominal installation position in the vehicle.

[0134] This configuration is favorable for the drainage of water from the heat exchanger defrosting process, when ice deposits accumulated on the surface of the first heat exchange section melt. Indeed, the liquid water can flow along the tubes without encountering any obstruction that could create a blockage.

[0135] According to another implementation example, not shown, the first branch 5 of the tubes 3 of the first tube bundle 11 extends along a horizontal axis when the heat exchanger 50 is in its nominal installation position in the vehicle. This horizontal axis is, for example, the vehicle's transverse Y-axis. The base 6 of the tubes 3 of the first bundle 11 then defines a lateral side of the heat exchanger 50 when the heat exchanger 50 is in its nominal installation position in the vehicle. In other words, the base 6 then extends in a plane parallel to the Y, Z plane. This configuration is particularly well-suited to applications where the vehicle has a low, wide front end.

[0136] As illustrated on the figure 5A first end 15 of the tubes 3 of the first tube bundle 11 opens into a first distributor 9 configured to distribute the refrigerant among all the tubes 3 of the first tube bundle 11. The first distributor 9 extends transversely to the axis of the tubes 3 of the first tube bundle 11.

[0137] The first distributor 9, for example, is cylindrical in shape. The first distributor 9 includes a refrigerant inlet 13.

[0138] A second end 16 of the tubes 3 of the first tube bundle 11 opens into a first collector 10 configured to collect the refrigerant from all the tubes 3 of the first tube bundle 11. The first collector 10 extends transversely to the axis of the tubes 3 of the first tube bundle 11.

[0139] The first manifold 10, for example, is cylindrical in shape. The first manifold 10 includes a refrigerant outlet 14.

[0140] The first collector 10 and the first distributor 9 extend in parallel directions.

[0141] The tubes 3 are hermetically connected to the first distributor 9 at their first end 15. Similarly, the tubes 3 are hermetically connected to the first collector 10 at their second end 16. The tubes 3 are, for example, brazed to the first distributor 9 as well as to the first collector 10.

[0142] In the illustrated example, particularly at the figure 5 , tubes 3 of the first bundle 11 of tubes are identical.

[0143] The refrigerant inlet 13 and the refrigerant outlet 14 can be arranged relative to each other in various ways. figure 6 schematically illustrates several possible configurations.

[0144] According to the illustrated examples, the refrigerant inlet 13 and the refrigerant outlet 14 are positioned opposite each other in a direction perpendicular to the axis of the first distributor 9. In other words, the refrigerant inlet 13 and outlet 14 are located on the same lateral edge of the heat exchanger 50. According to variants not shown, the refrigerant inlet 13 and the refrigerant outlet 14 can be located on opposite lateral edges along the axis of the first distributor 9. The refrigerant inlet 13 and the refrigerant outlet 14 can also be located near the midpoint of the first distributor 9 and the first manifold 10, along their principal direction of extension. Such an arrangement can reduce refrigerant pressure losses and improve refrigerant distribution. Indeed, the distance between the refrigerant inlet and the furthest tube is thus reduced.The same applies to the distance between the refrigerant outlet and the furthest outlet.

[0145] It should be noted that the refrigerant inlet 13 and outlet 14 are not intrinsically defined for the heat exchanger 50, but can change depending on the refrigerant circulation pattern within the heat conditioning system in which the exchanger is integrated. In other words, what corresponds to a refrigerant inlet 13 in one operating mode can become a refrigerant outlet 14 in another operating mode. Indeed, once the heat exchanger 50 is integrated into a heat conditioning system, the direction of refrigerant flow is determined by a set of valves that can be selectively opened or closed. By controlling the various valves, the direction of refrigerant flow in the first heat exchange section 1 can be reversed.It is therefore possible to change the direction of refrigerant flow according to the desired operating mode, for example in condenser or evaporator mode.

[0146] According to an example of the implementation of the heat exchanger 50, illustrated in part A of the figure 6 The first distributor 9 is positioned downstream of the first manifold 10 in the direction of airflow F when the heat exchanger 50 is in its nominal installation position in the vehicle. This configuration is preferably used when the heat exchanger 50 operates as a condenser or gas cooler. In other words, in this operating mode, the refrigerant inlet is on the side of the first branch 5 of the tubes 3 located furthest upstream in the direction of airflow.

[0147] In another example of the implementation of the heat exchanger 50, shown schematically in part B of the figure 6The first manifold 10 is positioned downstream of the first distributor 9 in the direction of airflow F when the heat exchanger 50 is in its nominal installation position in the vehicle. This configuration is preferably used when the heat exchanger 50 operates as an evaporator, particularly in heat pump mode. In other words, in this operating mode, the refrigerant inlet is on the side of the second branch 7 of the tubes 3, located furthest downstream in the direction of airflow.

[0148] In the first embodiment, illustrated in particular on the figure 1 and the figure 2The first branch 5 and the second branch 7 of the tubes 3 of the first bundle 11 are approximately the same length. This length is, for example, between 300 millimeters and 600 millimeters. The tubes 4 of the second bundle 12 extend, along the Z-axis, along the entire length of the first branch 5 and the second branch 7. In other words, the entire second bundle of tubes 12 is arranged between the first branch 5 and the second branch 7 of the tubes 3 of the first bundle of tubes 1 according to the direction of airflow F.

[0149] There figure 3This illustrates a second embodiment of the heat exchanger 50. In this embodiment, the length L1 of the first branch 5 of the tubes 3 of the first tube bundle 11 is less than the length L2 of the second branch 7 of the tubes 3 of the first tube bundle 11. In other words, only a portion of the tubes 4 of the second heat exchange section 2 is aligned with the first branch 5 of the tubes 3 of the first heat exchange section 1.

[0150] The amount of material used to make the first tube bundle 11 is thus reduced. Furthermore, a portion of the tubes 4 in the second tube bundle 12 directly receives the airflow F, without any tubes from the first bundle 11 being positioned upstream. This portion of the tubes 4 is therefore particularly efficient in terms of heat exchange. The cost of the heat exchanger 50 can be reduced without compromising its efficiency.

[0151] In this case, the length L1 of the first branch 5 of the tubes 3 of the first bundle 11 of tubes 3 is, for example, between 100 millimeters and 300 millimeters. The length L2 of the second branch 7 of the tubes 3 of the first bundle 11 of tubes 3 is, for example, between 300 millimeters and 600 millimeters.

[0152] According to the embodiment illustrated in the figures, the tubes 4 of the second bundle 12 of tubes extend transversely to the tubes 3 of the first bundle 11 of tubes. The tubes 4 of the second bundle 12 of tubes are parallel to each other. The tubes 4 of the second bundle 12 of tubes are, for example, identical. As schematically illustrated in the figure 5 , tubes 4 of the second bundle 12 of tubes extend along the transverse axis Y.

[0153] The second heat exchange section 2 is roughly parallelepiped in shape.

[0154] There is play, along the longitudinal direction X, between the first branch 5 of the tubes 3 of the first bundle 11 and the tubes 4 of the second bundle 12. Similarly, there is play, along this same longitudinal direction X, between the tubes 4 of the second bundle 12 and the second branch 7 of the tubes 3 of the first bundle 11.

[0155] A first end 17 of the tubes 4 of the second tube bundle 12 opens into a second distributor 19 configured to distribute the heat transfer fluid among all the tubes 4 of the second tube bundle 12. The second distributor 19 extends transversely to the axis of the tubes 4 of the second tube bundle 12. The second distributor 19 includes a heat transfer fluid inlet 21.

[0156] A second end 18 of the tubes 4 of the second tube bundle 12 opens into a second manifold 20 configured to collect the heat transfer fluid from all the tubes 4 of the second tube bundle 12. The second end of the tubes 4 and the second manifold 20 are not visible on the figure 2 , because they are positioned behind the first branch 5 of the tubes 3 shown.

[0157] The tubes 4 of the second tube bundle 12 are hermetically connected to the second distributor 19 at their first end 17. Similarly, the tubes 4 of the second tube bundle 12 are hermetically connected to the second manifold 20 at their second end 18. The tubes 4 of the second tube bundle 12 are, for example, brazed to the second distributor 19 as well as to the second manifold 20.

[0158] The second manifold 20 extends transversely to the axis of the tubes 4 of the second tube bundle 12. The second manifold 20 includes a heat transfer fluid outlet 22. The second manifold 20 and the second distributor 19 extend along the vertical axis Z.

[0159] The relative position of the heat transfer fluid inlet 21 and outlet 22 can vary, depending on different embodiments. For example, in the figure 5 , of the figure 2 and part C of the figure 6 The heat transfer fluid inlet 21 and the heat transfer fluid outlet 22 are located on opposite lateral sides of the heat exchanger 50. See part A and part B of the example. figure 6 The inlet 21 and outlet 22 are on the same side. The circulation of the heat transfer fluid in the manifold and distributor is adapted accordingly.

[0160] The perimeter of the tubes 4 of the second bundle 12 of tubes has an oblong cross-section.

[0161] There figure 4 describes an alternative embodiment in which the heat exchanger 50 includes a support 30 disposed between at least a part of the tubes 4 of the second tube bundle 12 and the base 6 of at least a part of the tubes 3 of the first tube bundle 11.

[0162] In the example shown, the heat exchanger 50 includes a support 30 connecting the second heat exchange section 2 to the base 6 of the tubes 3 of the first tube bundle 11.

[0163] The support 30 provides mechanical support for the bases 6 of the tubes 3 of the first heat exchange section 1 relative to the second heat exchange section 2, which helps to reduce the propagation of vehicle vibrations in the tubes 3 of the first heat exchange section 1.

[0164] The support 30 has a thermal conductivity lower than the thermal conductivity of the tubes 3 of the first bundle 11, preferably less than 10% of the thermal conductivity of the tubes 3 of the first bundle 11.

[0165] Thus, the support 30 thermally insulates the base 6 of the tubes 3 of the first heat exchange section 1 from the second heat exchange section, avoiding the formation of a thermal bridge.

[0166] Support 30 is for example made of plastic, in particular polyamide reinforced with glass fibers (for example PA6 reinforced with 30% glass fibers) or polypropylene reinforced with glass fibers (for example PP reinforced with 30% glass fibers).

[0167] The support 30 can secure the second heat exchange section 2 with the base 6 of the tubes 3 of the first bundle 11 of tubes.

[0168] In the example illustrated at the figure 6, the second heat exchange section 2 includes a face 26 arranged opposite the base 6 of the tubes 3 of the first bundle 11 of tubes, and the support 30 connects the base 6 of the tubes 3 of the first bundle 11 of tubes with the face 26 arranged opposite.

[0169] The support 30 here includes a sealed wall 27 connecting the second heat exchange section 2 to the base 6 of the tubes 3 of the first bundle 11 of tubes so as to block a circulation of the air flow F between the second heat exchange section 2 and the base 6 of the tubes 3 of the first bundle 11 of tubes.

[0170] The airtight wall 27 prevents airflow from entering the space between the base of the tubes 3 of the first bundle 11 and the face 26 of the second heat exchange section, which is located opposite. The airtight wall 27 thus prevents any part of the airflow F from exiting the exchanger 1 without exchanging heat with the second heat exchange section 2.

[0171] The support 30 here has a trapezoidal cross-section. The small base 28 of the trapezoid is opposite the second heat exchange section 2. The large base 29 is opposite the base 6 of the tubes 3 of the first tube bundle 11.

[0172] Thus, the support 30 guides the airflow F flowing near the base 6 of the tubes 3 of the first tube bundle 11 towards the second heat exchange section 2. Furthermore, water from the defrosting phases can also be guided downwards through the sealed wall 27 of the heat exchanger 50, thereby facilitating the drainage of this water.

[0173] According to one embodiment, the support 30 is integral with the base 6 of each of the tubes 3 of the first bundle 11 of tubes.

[0174] The support 30 provides mechanical support for the tubes 3 relative to each other, which limits the amplitude of vibrations. The mechanical robustness of the heat exchanger 50 is improved.

[0175] The support 30 is for example overmolded onto the base 6 of the tubes 3 of the first bundle 11 of tubes.

[0176] According to an alternative design (not shown), face 26 of the second heat exchange section 2 can be joined to the base 6 of the tubes 3 of the first heat exchange section 1, notably by brazing. In this case, the support 30 is not present. There is no play along the Z-axis between face 26 of the second heat exchange section 2 and the base 6 of the tubes 3 of the first heat exchange section 1.

[0177] According to yet another embodiment, the tubes 4 of the second tube bundle 12 extend parallel to the first branch 5 of the tubes 3 of the first tube bundle 11. This arrangement allows the second manifold 20 or the second distributor 19 to be positioned opposite the base 6 of the tubes 4 of the first tube bundle 11. The base 6 of the refrigerant tubes can thus be fixed to the second manifold 20, or to the second distributor 19, in order to secure the U-shaped tubes of the tube bundle 11 in the first heat exchange section 1.

[0178] Since the tubes 3 of the first coil 11 of refrigerant can be either horizontal or vertical, and the tubes 4 of the second coil 12 of heat transfer fluid can also be either horizontal or vertical, four arrangements are possible.

Claims

1. A heat exchanger (50) for a motor vehicle, comprising: - a first heat exchange section (1) configured to allow heat exchange between a refrigerant and an air flow (F), the first heat exchange section (1) comprising a first bundle (11) of tubes (3) forming a set of refrigerant circulation channels configured to be arranged in the air flow (F), - a second heat exchange section (2) configured to allow heat exchange between a heat transfer liquid and the air flow (F), the second heat exchange section comprising a second bundle (12) of tubes (4) forming a set of heat transfer liquid circulation channels configured to be arranged in the air flow (F), characterized in that the tubes (3) of the first bundle (11) of tubes have a U shape comprising a first branch (5) and a second branch (7) connected by a base (6), the first branch (5) is positioned upstream of the second branch (7) in a direction of flow of the air flow (F), and the second bundle of tubes (12) is arranged between the first branch (5) and the second branch (7) of the tubes (3) of the first bundle of tubes (1) in the direction of flow of the air flow (F).

2. The heat exchanger (50) as claimed in claim 1, wherein each tube (3) of the first bundle (11) of tubes extends in a plane, wherein the tubes (3) of the first bundle (11) of tubes are arranged in parallel planes, and wherein the tubes (3) of the first bundle (11) of tubes are aligned in a direction (D) perpendicular to the plane of the tubes.

3. The heat exchanger (50) as claimed in the preceding claim, wherein the second bundle (12) of tubes (4) extends between two parallel planes (P2, P2'), these two planes (P2, P2') being perpendicular to the plane of the tubes (3) of the first bundle (1).

4. The heat exchanger (50) as claimed in one of the preceding claims, wherein the base (6) of a tube (3) of the first bundle (11) of tubes is spaced apart from the base of a consecutive tube (3).

5. The heat exchanger (50) as claimed in one of the preceding claims, wherein the outer periphery of the tubes (3) of the first bundle (11) of tubes has an oblong cross section, defining a major axis and a minor axis, wherein the major axis of the first branch (5) of the tubes is parallel to the air flow (F), wherein the major axis of the second branch (7) of the tubes (3) is parallel to the air flow (F), and wherein the major axis of the base (6) of the tubes (3) is perpendicular to the air flow (F).

6. The heat exchanger (50) as claimed in one of the preceding claims, wherein the base (6) of the tubes (3) of the first bundle (11) of tubes defines a lower side of the heat exchanger (50) when the heat exchanger (50) is in the nominal position of installation in the vehicle, and wherein the first branch (5) of the tubes (3) of the first bundle (11) of tubes extends along a vertical axis (Z) when the heat exchanger (50) is in the nominal position of installation in the vehicle.

7. The heat exchanger (50) as claimed in one of claims 1 to 6, wherein the base (6) of the tubes (3) of the first bundle (11) of tubes defines a lateral side of the heat exchanger (50) when the heat exchanger (50) is in the nominal position of installation in the vehicle, and wherein the first branch (5) of the tubes (3) of the first bundle (11) of tubes extends along a horizontal axis when the heat exchanger (50) is in the nominal position of installation in the vehicle.

8. The heat exchanger (50) as claimed in one of claims 1 to 7, wherein a first end (15) of the tubes (3) of the first bundle (11) of tubes opens into a first distributor (9) configured to distribute the refrigerant between all of the tubes (3) of the first bundle (11) of tubes, wherein a second end (16) of the tubes (3) of the first bundle (11) of tubes opens into a first manifold (10) configured to collect the refrigerant coming from all of the tubes (3) of the first bundle (11) of tubes, and wherein the first distributor (9) is positioned downstream of the first manifold (10) in a direction of flow of the air flow (F) when the heat exchanger (50) is in the nominal position of installation in the vehicle.

9. The heat exchanger (50) as claimed in one of claims 1 to 7, wherein a first end (15) of the tubes (3) of the first bundle (11) of tubes opens into a first distributor (9) configured to distribute the refrigerant between all of the tubes (3) of the first bundle (11) of tubes, wherein a second end (16) of the tubes (3) of the first bundle (11) of tubes opens into a first manifold (10) configured to collect the refrigerant coming from all of the tubes (3) of the first bundle (11) of tubes, and wherein the first manifold (10) is positioned downstream of the first distributor (9) in a direction of flow of the air flow (F) when the heat exchanger (50) is in the nominal position of installation in the vehicle.

10. The heat exchanger (50) as claimed in one of the preceding claims, wherein the length (L1) of the first branch (5) of the tubes (3) of the first bundle (11) of tubes is smaller than the length (L2) of the second branch (7) of the tubes (3) of the first bundle (11) of tubes.

11. The heat exchanger (50) as claimed in one of the preceding claims, comprising a support (30) connecting the second heat exchange section (2) to the base (6) of the tubes (3) of the first bundle (11) of tubes.

12. The heat exchanger (50) as claimed in the preceding claim, wherein the support (30) has a thermal conductivity lower than the thermal conductivity of the tubes (3) of the first bundle (11), preferably lower than 10% of the thermal conductivity of the tubes (3) of the first bundle (11).

13. The heat exchanger (50) as claimed in claim 11 or 12, wherein the support (30) comprises a sealed wall (27) connecting the second heat exchange section (2) to the base (6) of the tubes (3) of the first bundle (11) of tubes in such a way as to block circulation of the air flow (F) between the second heat exchange section (2) and the base (6) of the tubes (3) of the first bundle (11) of tubes.

14. The heat exchanger (50) as claimed in one of claims 1 to 13, wherein the tubes (4) of the second bundle (12) of tubes extend transversely to the tubes (3) of the first bundle (11) of tubes.

15. The heat exchanger (50) as claimed in one of claims 1 to 13, wherein the tubes (4) of the second bundle (12) of tubes extend parallel to the first branch (5) of the tubes (3) of the first bundle (11) of tubes.