Heat exchanger for a motor vehicle

Abstract

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

Description

Description Title: HEAT EXCHANGER FOR MOTOR VEHICLE Technical field [1] The present invention relates to the field of heat exchangers, in particular heat exchangers for motor vehicles. Such exchangers can be fitted to a thermal conditioning system fitted to a motor vehicle. Such a thermal conditioning system makes it possible to ensure thermal regulation of various parts of the vehicle, such as the passenger compartment or an electrical energy storage battery, when the vehicle is electrically powered. Heat exchanges are managed mainly by the compression and expansion of a refrigerant circulating in a circuit in which several heat exchangers are arranged. A compressor makes it possible to pass the refrigerant at high pressure and to circulate it in the circuit. Prior art [2] The refrigerant circuit usually includes a first heat exchanger ensuring the condensation of the high-pressure refrigerant discharged by the compressor, or its cooling in the case of a fluid in a supercritical state. The refrigerant circulating in this first exchanger gives off heat to a flow of air passing through the heat exchanger. [3] Furthermore, it is also common to cool an element of the vehicle's powertrain by circulating a heat transfer fluid. To do this, a heat transfer fluid receives heat from the element of the powertrain and dissipates heat, for example, in an air flow, at a second heat exchanger. [4] The integration of these two heat exchangers in the vehicle can be tricky, particularly due to their size when the two exchangers are offset from each other so as to simultaneously receive the same air flow. In order to limit the size, the two exchangers can also be aligned according to the direction of the air flow so as to be passed through successively by the same air flow. However, heating of the air as it passes through the upstream exchanger tends to penalize the efficiency of the downstream exchanger. [5] The present invention aims to propose a solution that is easier to integrate because it is more compact and provides improved thermodynamic performance. Summary [6] To this end, the present invention provides a heat exchanger for a motor vehicle, comprising: - a first heat exchange section configured to allow heat exchange between a refrigerant fluid and an air flow, the first heat exchange section comprising a first bundle of tubes forming a set of refrigerant fluid circulation channels configured to be arranged in the air flow, - a second heat exchange section configured to allow heat exchange between a heat transfer fluid and the air flow, the second heat exchange section comprising a second bundle of tubes forming a set of heat transfer fluid circulation channels configured to be arranged in the air flow, in which the tubes of the first bundle of tubes 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 flow of the air flow, and in which the second bundle of tubes is arranged between the first branch and the second branch of the tubes of the first bundle of tubes in the direction of flow of the air flow. [7] The U-shape of the tubes of the first bundle of tubes makes it possible to increase the length participating in the heat exchanges of the first heat exchange section, while limiting the frontal surface of the exchanger. The second heat exchange section being arranged in the free volume formed by the spacing of the branches of each of the U-shaped tubes of the first bundle of tubes, the presence of the second heat exchange section does not modify the external volume of the heat exchanger. The heat exchanger thus has a very compact. In addition, the first branch of the tubes is, for the circulation of the air flow, upstream of the second heat exchange section, which is itself upstream of the second branch of the tubes of the first heat exchange section. Each tube, or portion of tube, thus receives an air flow having a temperature adapted to the temperature of the fluid circulating inside. In other words, the first branch of the first heat exchange section receives a flow of fresh ambient air which has not been heated by its passage through a heat exchanger, which increases its efficiency. The air flow leaving the first branch of the first heat exchange section has a temperature low enough to guarantee good exchange efficiency with the second heat exchange section.Similarly, the air flow heated by its passage in the second heat exchange section still has a sufficiently low temperature to guarantee good 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 size, is thus optimized. In addition, possible maximum temperature constraints of the heat transfer fluid at the outlet of the second heat exchange section can be respected thanks to the proposed arrangement. [8] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination: [9] According to one aspect of the proposed heat exchanger, the second tube bundle is disposed downstream of the first branch of tubes of the first bundle and upstream of the second branch of tubes of the first bundle.

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

[0011] According to one mode of operation of the exchanger, the refrigerant circulating in the first heat exchange section gives off heat to the air flow.

[0012] In this mode of operation, the refrigerant circulates from the second branch of the tubes to the first branch of the tubes.

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

[0014] According to one mode of operation, the refrigerant circulating in the first heat exchange section receives heat from the air flow.

[0015] In this mode of operation, the refrigerant circulates from the first branch of the tubes to the second branch of the tubes.

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

[0017] According to another example of implementation of the heat exchanger, the air flow is an air flow inside the vehicle 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 of the first tube bundle extends in a plane.

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

[0023] The tubes of 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 bundle of tubes 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, the second heat exchange section filling the space left free between all of the first branches of the tubes of the first heat exchange section and all of the second branches of the tubes.

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

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

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

[0029] The fins have slots for airflow.

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

[0031] When the first heat exchange section operates as an evaporator while the outside temperature is below or close to 0°C, ice may form on at least some of the tubes in the tube bundle. When the ice melts, water flows down the tubes to the base of the tubes. The gap between two neighboring tubes allows the water to flow out and prevents water from accumulating at the base of the tubes. This reduces the risk of re-icing the first heat exchange section.

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

[0033] According to one embodiment of the heat exchanger, the outer periphery of the tubes of the first bundle of tubes 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 air flow.

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

[0035] The tubes of the first tube bundle may be twisted near a junction between the first branch and the base.

[0036] Similarly, the tubes of the first tube bundle may be twisted near 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 air flow.

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

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

[0040] This configuration is favorable to the evacuation of water from the defrosting of the heat exchanger, when a deposit of ice accumulated on the surface of the first heat exchange section and / or the second heat exchange section melts. Indeed, the liquid water can flow along the tubes without encountering any obstacle that could create a hold-up.

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

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

[0043] This configuration prevents possible corrosion of the lowest part of the heat exchanger due to accumulated moisture. In addition, this configuration limits 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 refers to the dimension along the transverse axis of the vehicle when the exchanger is installed in the vehicle nominally. This makes the manufacture of the exchanger easier for applications in which the vehicle has a low front face.

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

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

[0046] The first distributor is cylindrical in shape.

[0047] The first distributor includes a refrigerant inlet.

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

[0049] The first collector extends transversely to the axis of the tubes of 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 fluid inlet and the refrigerant fluid outlet are opposite each other in a direction perpendicular to the axis of the first distributor.

[0055] According to an example of implementation of the heat exchanger, the first distributor is arranged downstream of the first collector in a direction of flow of the air flow when the heat exchanger is in the nominal installation position in the vehicle.

[0056] In another example of implementation of the heat exchanger, the first collector is arranged downstream of the first distributor in a direction of flow of the air flow when the heat exchanger is in the nominal installation position in the vehicle.

[0057] According to one embodiment of the heat exchanger, the first branch of the tubes of the first bundle of tubes and the second branch of the tubes of the first bundle of tubes have the same length. The length of the first branch and the second branch of the tubes of the first bundle of tubes 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 of the first bundle of tubes is less than the length of the second branch of the tubes of the first bundle of tubes.

[0059] The amount of material used to make the first tube bundle is thus reduced. In addition, some of the tubes in the second tube bundle receive the air flow F directly, without any tubes from the first bundle being placed upstream. The cost of the exchanger can be reduced without compromising its efficiency.

[0060] In this case, the length of the first branch of the tubes of the first tube bundle is, for example, between 100 millimeters and 300 millimeters. The length of the second branch of the tubes of 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 of the second tube bundle are parallel to each other.

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

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

[0065] A first end of the tubes of the second bundle of tubes opens into a second distributor configured to distribute the heat transfer liquid between all of the tubes of the second bundle of tubes.

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

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

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

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

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

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

[0072] According to one embodiment, the heat exchanger comprises 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 of the first tube bundle.

[0074] The support provides mechanical support for the bases of the tubes of 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 exemplary 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 of the first heat exchange section from the second heat exchange section, avoiding the formation of a thermal bridge.

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

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

[0079] According to an exemplary embodiment, the second heat exchange section comprises a face arranged opposite the base of the tubes of the first bundle of tubes, and the support connects the base of the tubes of the first bundle of tubes with the face arranged opposite.

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

[0081] The sealed wall prevents the air flow from circulating in the space between the base of the tubes of the first bundle and the face of the second heat exchange section, which is located opposite. The sealed wall thus prevents part of the air flow F from leaving the exchanger without exchanging heat with the second heat exchange section.

[0082] The support may have a trapezoidal section.

[0083] The small base of the trapezoid is opposite the second heat exchange section. The large base is opposite the base of the tubes of the first tube bundle.

[0084] Thus, the support guides the air flow flowing near the base of the tubes of the first tube bundle towards the second heat exchange section. In addition, the water from the defrosting phases can also be guided towards the bottom of the exchanger, which promotes the evacuation of this water.

[0085] According to an exemplary embodiment, the support is secured to the base of each of the tubes of the first bundle of tubes.

[0086] The support ensures mechanical support of the tubes relative to each other, which limits the amplitude of vibrations. The mechanical robustness of the heat exchanger is improved.

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

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

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

[0090] This arrangement allows the second collector or the second distributor to be positioned opposite the base of the tubes of the first tube bundle. The base of the refrigerant tubes can thus be fixed to the second collector, or to the second distributor. The support for securing the second heat exchange section to the base of the tubes of the first tube bundle is not necessary. Additionally, one of the distributor and the collector of the second tube bundle can be aligned with the upstream refrigerant collector / distributor. This reduces the airflow 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 upon analyzing the attached drawings, in which:

[0092] [Fig. 1] is a schematic side and sectional view of a heat exchanger according to a first embodiment of the invention,

[0093] [Fig. 2] is a schematic, front view of the heat exchanger of Figure 1,

[0094] [Fig. 3] is a schematic side and sectional view of a heat exchanger according to a second embodiment of the invention,

[0095] [Fig. 4] is a schematic detail view, from the side and in section, of a variant of a heat exchanger according to the invention,

[0096] [Fig. 5] is a partial schematic view, in perspective, of a heat exchanger according to the invention.

[0097] [Fig. 6] is a partial schematic view, from above, of three variants of a heat exchanger according to the invention,

[0098] [Fig. 7] is a partial schematic view of a tube of the first tube bundle of a heat exchanger according to the invention. Description of the embodiments

[0099] To facilitate reading the figures, the different elements are not necessarily represented to scale. In these figures, identical elements have the same references. Some elements or parameters may be indexed, i.e. designated for example by first element or second element, or first parameter and second parameter, etc. This indexing is intended to differentiate similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another and the names may be interchanged.

[0100] 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 relative to the direction of circulation, 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 relative to the direction of circulation, or path, of the fluid in question.

[0101] 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.

[0102] When it is specified that a subsystem includes a given element, this does not exclude the presence of other elements in this subsystem.

[0103] The term "exchanger" is equivalent to the term "heat exchanger" as well as the term "heat exchanger".

[0104] The heat exchanger 50 to be described may 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 circuit in which the fluid can circulate. refrigerant. The refrigerant circuit is sealed when it is in a nominal operating state, i.e. without defects or leaks. Similarly, the heat transfer fluid circuit forms a closed and sealed circuit in which a heat transfer fluid can circulate.

[0105] The thermal conditioning system comprises a compressor that causes the refrigerant to enter a high-pressure, high-temperature state. The high-pressure, high-temperature refrigerant can be sent to a first heat exchange section 1 of the heat exchanger 50 where the refrigerant will transfer heat to an air flow F. The heat exchanger 50 is, for example, arranged in the front face of the vehicle and receives an air flow F outside the passenger compartment of the vehicle, resulting in particular from the vehicle moving forward. The cooled refrigerant can then pass through an expansion valve and enter a low-pressure state, then evaporate in a second heat exchanger. The second heat exchanger is, for example, arranged in the vehicle's heating, ventilation and / or air conditioning system, frequently referred to as "HVAC" for "Heating, Ventilating and Air Conditioning".The second heat exchanger thus allows the vehicle's passenger compartment to be cooled. Alternatively, the second heat exchanger may be a cooling exchanger thermally coupled to an electrical energy storage battery. The second exchanger thus allows the battery to be cooled, particularly during fast charging phases. According to other modes of use of the thermal conditioning system, the heat exchanger 50 can receive low-pressure refrigerant and carry out evaporation of the refrigerant. The phases of heating or dehumidification of the air in the passenger compartment correspond to these modes of use.

[0106] The heat transfer fluid circuit of the thermal conditioning system allows cooling of an element of the electric powertrain of the vehicle. The element of the electric powertrain may comprise an electrical energy storage battery, or an electronic module for controlling an electric traction motor of the vehicle, or the motor itself. The heat transfer fluid thus receives heat from the element of the powertrain, and this heat is dissipated at a second heat exchange section 2 of the exchanger 50.

[0107] Figure 1 shows 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.

[0108] 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 air flow 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 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. 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 arranged 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.

[0109] The U-shape of the tubes 3 of the first bundle 11 of tubes 3 makes it possible to increase the length participating in the heat exchanges of the first heat exchange section, while limiting the frontal surface of the exchanger 50. In addition, a portion of the tubes, forming the first branch 5, directly receives ambient air that has not been heated by another heat exchanger, which increases the efficiency of the heat exchange. The second heat exchange section 2 is arranged in the free volume formed by the spacing of the branches 5.7 of each of the U-shaped tubes 3 of the first bundle 1 1 of tubes. The presence of the second heat exchange section 2 does not modify the external volume of the heat exchanger 50. The heat exchanger 50 thus has a very compact and thermally optimized shape.

[0110] In addition, the first branch 5 of the tubes 3 is arranged, relative to the circulation of the air flow F, upstream of the second heat exchange section 2, which is itself arranged upstream of the second branch 7 of the tubes 3 of the first heat exchange section 1. Each tube, or portion of tube, thus receives an air flow having a temperature adapted to the temperature of the fluid circulating inside this tube. In other words, the first branch 5 of the first heat exchange section 1 receives a flow of fresh ambient air which has not been heated by passing through a heat exchanger, which increases its efficiency for the heat exchange. The air flow leaving the first branch 5 of the first heat exchange section 1 has a temperature sufficiently low to guarantee good exchange efficiency with the fluid circulating in the second heat exchange section 2.Likewise, the air flow heated by its passage in the second heat exchange section 2 still has a sufficiently low temperature 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 size, is thus optimized.

[0111] By the fact that the tubes of the first bundle 11 have a U-shape, it is understood that the tubes comprise a first rectilinear portion, called the first branch 5, fluidly connected to a second rectilinear portion, called the second branch 7, by an intermediate portion called the base 6. The first branch 5 and the second branch 7 extend parallel to each other. The intermediate portion 6 extends transversely to the first branch 5 and to the second branch 7. The intermediate portion is here rectilinear. The first branch 5, the second branch 7 and the intermediate portion 6 are arranged in the same plane. According to a variant not shown, the intermediate portion may have a curved shape.

[0112] 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.

[0113] According to one mode of operation of the heat exchanger 50, the first heat exchange section 1 operates as a condenser of the refrigerant fluid.

[0114] According to this mode of operation of the exchanger 50, the refrigerant circulating in the first heat exchange section 1 gives up heat to the air flow F. The same is true when the refrigerant used is in a supercritical state. In this case, the exchanger 50 operates as a cooler of the refrigerant, without condensation occurring. Such operation occurs, for example, when the refrigerant used is R744.

[0115] According to this mode of operation as a condenser and / or cooler, the refrigerant circulates 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 via the portion of the tubes located furthest downstream according to the circulation of the air flow F.

[0116] According to another mode of operation of the heat exchanger 50, the first heat exchange section 1 operates as an evaporator of the refrigerant fluid.

[0117] In this operating mode, the refrigerant circulating in the first heat exchange section 1 receives heat from the air flow F. This operating mode corresponds, for example, to the heat pump mode.

[0118] According to this operating mode, the refrigerant circulates from the first branch 5 of the tubes 3 to the second branch 7 of the tubes 3. In other words, the refrigerant arrives in the first heat exchange section 1 via the portion of the tubes located furthest upstream according to the circulation of the air flow F. Preferably, the direction of circulation of the refrigerant is reversed depending on whether the exchanger 50 operates as a condenser or as an evaporator. This reversal of the direction of circulation depending on the operating mode in which the heat exchanger is used is optional.

[0119] According to an exemplary implementation of the heat exchanger 50, the air flow F is an air flow outside the vehicle. In this case, the exchanger 50 is for example arranged on the front face of the vehicle, behind the grille.

[0120] According to another example of implementation of the heat exchanger 50, the air flow F is an air flow inside the passenger compartment of the vehicle. The exchanger 50 is then arranged in the heating, ventilation and / or air conditioning installation of the vehicle.

[0121] In one application of the heat exchanger 50, the refrigerant may be a chemical fluid, such as R1234yf, or R134a. In another application of the heat exchanger, the refrigerant may be R744 or R290.

[0122] The refrigerant fluid circulates in parallel in the tubes 3 of the first bundle 11 of tubes.

[0123] In a similar manner, the heat transfer fluid circulates in parallel in the tubes 4 of the second bundle 12 of tubes. The heat transfer fluid can be a mixture of water and glycol.

[0124] Figure 5 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 distinguishable. As shown schematically in this figure, each tube 3 of the first bundle 11 of tubes extends in a plane P1. The tubes 3 of the first bundle 11 of tubes are arranged in parallel planes. In Figure 5, nine tubes 3 are shown. More generally, the first bundle 11 may comprise any number of tubes 3.

[0125] The tubes 3 of the first bundle 11 of tubes are aligned in a direction D perpendicular to the plane of the tubes.

[0126] The tubes 3 of the first bundle 11 may be made of aluminum or copper. Similarly, the tubes 4 of the second bundle 12 may be made of aluminum or copper, for example.

[0127] 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 shown in Figure 6, which is a schematic top view of the heat exchanger 50.

[0128] The heat exchanger 50 thus has a compact shape, the second heat exchange section 2 filling the space left free between all of the first branches 5 of the tubes 3 of the first heat exchange section. I and the set of second branches 7 of tubes 3.

[0129] As can be seen particularly in 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.

[0130] In a similar manner, the second branch 7 of a tube 3 of the first bundle II of tubes is connected to the second branch of a consecutive tube by a second set of fins 24.

[0131] The fins 23, 24 improve the heat transfer between the air flow F and the refrigerant circulating in the tubes 3 of the first heat exchange section 1.

[0132] The fins 23, 24 have slots 25 for the passage of the air flow F. The slots 25 improve the heat transfer between the air flow F and the fins 23, 24.

[0133] In a similar manner, a tube 4 of the second bundle 12 of tubes is connected to the neighboring tube by a set of fins 32. These fins improve the heat transfer between the air flow F and the heat transfer liquid circulating in the second heat exchange section 2. In Figure 2, only a part of the first bundle 11 of tubes has been shown, so as to make a part of the second heat exchange section 2 visible.

[0134] The base 6 of a tube 3 of the first bundle 1 1 of tubes is spaced from the base of a consecutive tube 3. In other words, the bases of the tubes 3 of the first bundle 1 1 of tubes are spaced from each other. The free space between the bases 6 of two consecutive tubes can be constant.

[0135] When the first heat exchange section 1 operates as an evaporator while the outside temperature is below 0°C or close to 0°C, ice may form on at least some of the tubes of the tube bundle 11. When the ice melts, the water flows along the tubes 3 to the base 6 of the tubes. The gap between two neighboring tubes 3 allows the water to flow, and prevents the accumulation of water at the base 6 of the tubes. The risk of re-icing the first heat exchange section 1 is thus reduced.

[0136] The outer periphery of the tubes 3 of the first bundle 11 of tubes has an oblong cross-section. The tubes 3 of the first bundle 11 of tubes are, for example, micro-channel tubes. In other words, each tube 3 comprises a plurality of parallel channels. The micro-channel tubes are formed by extrusion and then shaped to obtain the desired U-shape. The outer periphery of the tubes 3 of 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 air flow F. The major axis of the second branch 7 of the tubes 3 is also parallel to the air flow F. Figure 7 schematically details the outer shape of the tubes 3. In this figure, the micro-channels have not been shown.

[0137] The tubes 3 of the first bundle 11 of tubes may 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 may 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 gradually rotates 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 produce the U-shape without excessively deforming the material of the tubes.

[0138] In this embodiment, the major axis a of the base 6 of the tubes 3 is perpendicular to the air flow F.

[0139] According to an example of implementation of the heat exchanger 50, 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 installation position in the vehicle. In other words, the base 6 extends in a plane parallel to the X, Y plane. The different figures represent the exchanger 50 oriented in this way.

[0140] 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 installation position in the vehicle.

[0141] This configuration is favorable for the evacuation of water from the defrosting of the heat exchanger, when a deposit of ice accumulated on the surface of the first heat exchange section melts. Indeed, the liquid water can flow along the tubes without encountering any obstacle that could create a hold-up.

[0142] According to another example of implementation, not shown, 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 installation position in the vehicle. This horizontal axis is for example the transverse axis Y of the vehicle. 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 the nominal installation position in the vehicle. In other words, the base 6 then extends in a plane parallel to the plane Y, Z. This configuration is particularly suitable for applications in which the vehicle has a front face of low height and great width.

[0143] As illustrated in Figure 5, 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 fluid between all of the tubes 3 of the first bundle 11 of tubes. The first distributor 9 extends transversely to the axis of the tubes 3 of the first bundle 11 of tubes.

[0144] The first distributor 9 is for example cylindrical in shape. The first distributor 9 comprises a refrigerant fluid inlet 13.

[0145] A second end 16 of the tubes 3 of the first bundle 11 of tubes opens into a first collector 10 configured to collect the refrigerant fluid coming from all of the tubes 3 of the first bundle 11 of tubes. The first collector 10 extends transversely to the axis of the tubes 3 of the first bundle 11 of tubes.

[0146] The first collector 10 is for example cylindrical in shape. The first collector 10 comprises a refrigerant outlet 14.

[0147] The first collector 10 and the first distributor 9 extend in parallel directions.

[0148] The tubes 3 are tightly connected to the first distributor 9 at their first end 15. Similarly, the tubes 3 are tightly 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.

[0149] In the example illustrated, in particular in figure 5, the tubes 3 of the first bundle 11 of tubes are identical.

[0150] The refrigerant inlet 13 and the refrigerant outlet 14 can be arranged relative to each other in different ways. Figure 6 schematically illustrates several possible configurations.

[0151] According to the examples illustrated, the refrigerant fluid inlet 13 and the refrigerant fluid outlet 14 are opposite each other in a direction perpendicular to the axis of the first distributor 9. In other words, the refrigerant fluid inlet 13 and outlet 14 are arranged on the same lateral edge of the exchanger 50. According to variants not illustrated, the refrigerant fluid inlet 13 and the refrigerant fluid outlet 14 can be arranged on opposite lateral edges along the axis of the first distributor 9. The refrigerant inlet 13 and the refrigerant outlet 14 may also be arranged near the middle of the first distributor 9 and the first collector 10, according to their main direction of extension. Such an arrangement can reduce the refrigerant pressure losses and improve the distribution of the refrigerant. Indeed, the distance between the refrigerant inlet and the most distant tube is thus reduced. The same is true for the distance between the refrigerant outlet and the most distant outlet.

[0152] It will be noted that the refrigerant inlet 13 and outlet 14 are not defined intrinsically to the exchanger 50, but may change depending on the mode of circulation of the refrigerant within the thermal conditioning system in which the exchanger is integrated. In other words, what corresponds to an inlet 13 of refrigerant fluid in one operating mode can become an outlet 14 of refrigerant fluid in another operating mode. Indeed, once the heat exchanger 50 is integrated into a thermal conditioning system, the direction of circulation of the refrigerant fluid is imposed by a set of valves which can be selectively opened or closed. By controlling the different valves, the direction of circulation of the refrigerant fluid in the first heat exchange section 1 can be reversed. It is thus possible to modify the direction of circulation of the refrigerant fluid according to the desired operating mode, for example in condenser or evaporator.

[0153] According to an exemplary implementation of the heat exchanger 50, illustrated in part A of FIG. 6, the first distributor 9 is arranged downstream of the first collector 10 in a direction of flow of the air flow F when the heat exchanger 50 is in the 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 mode of operation, the refrigerant fluid inlet is on the side of the first branch 5 of the tubes 3 located furthest upstream in the direction of flow of the air flow.

[0154] In another example of implementation of the heat exchanger 50, shown diagrammatically in part B of FIG. 6, the first collector 10 is arranged 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 installation position in the vehicle. This configuration is preferably used when the heat exchanger 50 operates as an evaporator, in particular for the heat pump mode. In other words, in this operating mode, the refrigerant fluid inlet is on the side of the second branch 7 of the tubes 3, located furthest downstream in the direction of flow of the air flow.

[0155] In the first embodiment, illustrated in particular in Figure 1 and Figure 2, the first branch 5 and the second branch 7 of the tubes 3 of the first bundle 11 have substantially 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 tube bundle 12 is arranged between the first branch 5 and the second branch 7 of the tubes 3 of the first tube bundle 1 in the direction of flow of the air flow F.

[0156] Figure 3 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 bundle 11 of tubes is less than the length L2 of the second branch 7 of the tubes 3 of the first bundle 11 of tubes. In other words, only a portion of the tubes 4 of the second heat exchange section 2 is opposite the first branch 5 of the tubes 3 of the first heat exchange section 1.

[0157] The quantity of material used to produce the first bundle 11 of tubes is thus reduced. In addition, a portion of the tubes 4 of the second bundle 12 of tubes directly receives the air flow F, without any tube of the first bundle 11 being arranged upstream. This portion of the tubes 4 is therefore particularly efficient in terms of heat exchange. The cost of the exchanger 50 can be reduced without compromising its efficiency.

[0158] 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.

[0159] 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 1 1 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 illustrated schematically in Figure 5, the tubes 4 of the second bundle 12 tubes extend along the transverse Y axis.

[0160] The second heat exchange section 2 is of substantially parallelepipedal shape.

[0161] A clearance is present, in 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, a clearance is present, in 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.

[0162] A first end 17 of the tubes 4 of the second bundle 12 of tubes opens into a second distributor 19 configured to distribute the heat transfer liquid between all of the tubes 4 of the second bundle 12 of tubes. The second distributor 19 extends transversely to the axis of the tubes 4 of the second bundle 12 of tubes. The second distributor 19 comprises an inlet 21 for heat transfer liquid.

[0163] A second end 18 of the tubes 4 of the second bundle 12 of tubes opens into a second collector 20 configured to collect the heat transfer liquid coming from all of the tubes 4 of the second bundle 12 of tubes. The second end of the tubes 4 and the second collector 20 are not visible in Figure 2, because they are arranged behind the first branch 5 of the tubes 3 shown.

[0164] The tubes 4 of the second bundle 12 of tubes are connected in a sealed manner to the second distributor 19 at their first end 17. Similarly, the tubes 4 of the second bundle 12 of tubes are connected in a sealed manner to the second collector 20 at their second end 18. The tubes 4 of the second bundle 12 of tubes are for example brazed to the second distributor 19 as well as to the second collector 20.

[0165] The second collector 20 extends transversely to the axis of the tubes 4 of the second bundle 12 of tubes. The second collector 20 comprises an outlet 22 for heat transfer liquid. The second collector 20 and the second distributor 19 extend along the vertical axis Z.

[0166] The relative position of the heat transfer liquid inlet 21 and outlet 22 may vary, according to different embodiments. In the example of Figure 5, Figure 2 and part C of Figure 6, the heat transfer liquid inlet 21 and the heat transfer liquid outlet 22 are arranged on opposite lateral sides of the heat exchanger 50. In the example of part A and part B of Figure 6, the inlet 21 and the outlet 22 are on the same lateral side. The circulation of the heat transfer liquid in the collector and the distributor is adapted accordingly.

[0167] The circumference of the tubes 4 of the second bundle 12 of tubes has an oblong cross-section.

[0168] Figure 4 describes an alternative embodiment in which the heat exchanger 50 comprises a support 30 arranged between at least a portion of the tubes 4 of the second bundle 12 of tubes and the base 6 of at least a portion of the tubes 3 of the first bundle 11 of tubes.

[0169] In the example shown, the heat exchanger 50 comprises 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.

[0170] The support 30 ensures mechanical support of the bases 6 of the tubes 3 of the first heat exchange section 1 relative to the second heat exchange section 2, which makes it possible to attenuate the propagation of vibrations of the vehicle in the tubes 3 of the first heat exchange section 1.

[0171] 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.

[0172] Thus, the support 30 thermally insulates the base 6 of the tubes 3 of the first heat exchange section 1 relative to the second heat exchange section, avoiding the formation of a thermal bridge.

[0173] The support 30 is for example made of plastic, in particular polyamide loaded with glass fibers (for example PA6 loaded with 30% glass fibers) or polypropylene loaded with glass fibers (for example PP loaded with 30% glass fibers).

[0174] 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.

[0175] In the example illustrated in Figure 6, the second heat exchange section 2 comprises 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.

[0176] The support 30 here 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 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.

[0177] The sealed wall 27 prevents the air flow from circulating in 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 sealed wall 27 thus prevents part of the air flow F from leaving the exchanger 1 without exchanging heat with the second heat exchange section 2.

[0178] The support 30 here has a trapezoidal 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 bundle 11 of tubes.

[0179] Thus, the support 30 guides the air flow F flowing near the base 6 of the tubes 3 of the first bundle 11 of tubes towards the second heat exchange section 2. In addition, the water coming from the defrosting phases can also be guided towards the bottom of the exchanger 50 by the sealed wall 27, which promotes the evacuation of this water.

[0180] According to an exemplary embodiment, the support 30 is integral with the base 6 of each of the tubes 3 of the first bundle 11 of tubes.

[0181] The support 30 ensures mechanical support of the tubes 3 relative to each other, which limits the amplitude of vibrations. The mechanical robustness of the heat exchanger 50 is improved.

[0182] The support 30 is for example overmolded on the base 6 of the tubes 3 of the first bundle 11 of tubes.

[0183] According to a variant not shown, the face 26 of the second heat exchange section 2 can be secured to the base 6 of the tubes 3 of the first heat exchange section 1, in particular by brazing. In this case, the support 30 is not present. No play along the Z axis is present between the face 26 of the second heat exchange section 2 and the base 6 of the tubes 3 of the first heat exchange section 1.

[0184] According to another embodiment, 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. This arrangement makes it possible to arrange the second collector 20 or the second distributor 19 opposite the base 6 of the tubes 4 of the first bundle 11 of tubes. The base 6 of the refrigerant fluid tubes can thus be fixed to the second collector 20, or to the second distributor 19, in order to ensure that the U-shaped tubes of the bundle 11 of tubes of the first heat exchange section 1 are held in place.

[0185] The tubes 3 of the first bundle 11 of refrigerant fluid can be either horizontal or vertical, and the tubes 4 of the second bundle 12 of heat transfer liquid can also be either horizontal or vertical, four arrangements are possible.

Claims

Claims

1. Heat exchanger (50) for a motor vehicle, comprising: - a first heat exchange section (1) configured to allow heat exchange between a refrigerant fluid and an air flow (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 air flow (F), - a second heat exchange section (2) configured to allow heat exchange between a heat transfer fluid and the air flow (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 air flow (F), in which 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), in which the first branch (5) is arranged upstream of the second branch (7) in a flow direction of the air flow (F), and in which 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 flow direction of the air flow (F).

2. A heat exchanger (50) according to 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. Heat exchanger (50) according to the preceding claim, in which 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. Heat exchanger (50) according to one of the preceding claims, in which the base (6) of a tube (3) of the first bundle (11) of tubes is spaced from the base of a consecutive tube (3).

5. Heat exchanger (50) according to one of the preceding claims, in which 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, in which the major axis of the first branch (5) of the tubes is parallel to the air flow (F), in which the major axis of the second branch (7) of the tubes (3) is parallel to the air flow (F), and in which the major axis of the base (6) of the tubes (3) is perpendicular to the air flow (F).

6. Heat exchanger (50) according to one of the preceding claims, in which 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 installation position in the vehicle, and in which 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 installation position in the vehicle.

7. Heat exchanger (50) according to 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 installation position 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 installation position in the vehicle.

8. Heat exchanger (50) according to one of claims 1 to 7, in which 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 fluid between all of the tubes (3) of the first bundle (11) of tubes, in which a second end (16) of the tubes (3) of the first bundle (11) of tubes opens into a first collector (10) configured to collect the fluid refrigerant coming from all the tubes (3) of the first bundle (11) of tubes, and in which the first distributor (9) is arranged downstream of the first collector (10) according to a direction of flow of the air flow (F) when the heat exchanger (50) is in the nominal installation position in the vehicle.

9. Heat exchanger (50) according to 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 fluid 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 collector (10) configured to collect the refrigerant fluid coming from all of the tubes (3) of the first bundle (11) of tubes, and wherein the first collector (10) is arranged 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 installation position in the vehicle.

10. Heat exchanger (50) according to 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 less than the length (L2) of the second branch (7) of the tubes (3) of the first bundle (11) of tubes.

11. Heat exchanger (50) according to 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. Heat exchanger (50) according to 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 less than 10% of the thermal conductivity of the tubes (3) of the first bundle (11).

13. Heat exchanger (50) according to claim 11 or 12, in which 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 (1 1 ) 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 (1 1 ) of tubes.

14. Heat exchanger (50) according to one of claims 1 to 13, in which the tubes (4) of the second bundle (12) of tubes extend transversely to the tubes (3) of the first bundle (11) of tubes.

15. Heat exchanger (50) according to 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.

Images