Heat exchanger, associated electronic system and motor vehicle

Abstract

The invention relates to a heat exchanger comprising: - a casing that defines a sealed compartment and has an inlet and an outlet for a heat transfer fluid, this casing having a main wall, and - at least two fins stacked on the main wall at a distance from each other within said sealed compartment. According to the invention, the main wall has a main opening that is bordered on the side of the sealed compartment by a tube, and the at least two fins each have an opening engaged with the tube so as to be in contact with it. Figure for the abstract: Fig. 3

Description

Title of the invention: Heat exchanger, associated electronic system and motor vehicle. Technical field of the invention

[0001] The present invention relates generally to the cooling of electronic devices.

[0002] It relates more particularly to a heat exchanger comprising: - a casing that defines a sealed housing and has an inlet and outlet opening for the heat transfer fluid, this casing comprising a main wall, and - at least two fins stacked on the main wall in said sealed housing.

[0003] It also relates to an electronic system, typically a power cut-off system, comprising such a heat exchanger. It also relates to a battery equipped with this electronic system and a motor vehicle equipped with this battery. State of the art

[0004] Electric or hybrid vehicles include a battery pack.

[0005] Such a battery pack comprises a casing that houses a large number of electrochemical cells connected together in such a way that the voltage across the battery terminals is high. This voltage can typically be several hundred volts.

[0006] It is then necessary to equip the battery with electronic safety components (relays, fuses) in order to cut off the current when needed. These components are positioned along a busbar through which the input or output current from the battery flows.

[0007] Among the aforementioned vehicles, some are rechargeable.

[0008] In order to reduce the charging time of these vehicles, it is common to use fast charging with high electrical power.

[0009] Fast charging generates a sharp increase in temperature, particularly at the level of the electrical components, which in turn generates a temperature increase at the level of the bus bar.

[0010] Areas where the temperature is highest are called hot spots.

[0011] These hot spots may eventually degrade the electronic components.

[0012] To protect the electronic components, the housing is then generally actively cooled. However, this solution requires actively cooling a large volume and is therefore not very efficient. Presentation of the invention

[0013] In order to remedy the aforementioned drawback of the prior art, the present invention proposes to directly cool the hot spots of the housing.

[0014] More specifically, the invention proposes a heat exchanger as defined in the introduction, in which it is provided: - that the main wall has a main opening which is bordered on the side of the sealed housing by a tube, and - that at least two fins each have an opening engaged on the tube so as to be in contact with the latter.

[0015] The applicant noted that the hot spots are generally located at the level of the fixing elements of the bus bar.

[0016] The invention here proposes to cleverly combine the fixing of the heat exchanger with the fixing of this omnibus bar, so as to cool the hot spot as close as possible.

[0017] The fastening element (screw, snap pin, etc.) is thus inserted into the heat exchanger through its main opening and its tube. Therefore, thanks to the invention, the heat exchanger is in thermal contact with the fastening element along its entire height.

[0018] The thermal contact between the hot bridge and the tube, then between the tube and the fins, and finally between the fins and the heat transfer fluid, allows for efficient dissipation of the accumulated heat. The fastening element is thus efficiently cooled.

[0019] Furthermore, the use of the fixing element to fix the heat exchanger makes it possible not to add an additional fixing means and thus to optimize the size and mass of the assembly.

[0020] Finally, the heat exchanger is secured by tightening the fastening element onto the tube. In this way, no force is applied to the fins, and the fins are not deformed by the attachment of the cooling system.

[0021] Other advantageous and non-limiting features of the heat exchanger according to the invention, taken individually or in all technically possible combinations, are as follows: - the casing includes a side wall that is partly cylindrical with a flat section and in which the main wall and the at least two fins have contours of shapes that are partly circular and partly straight; - the casing has an electrically insulating coating on its outer face; - Each fin comprises a main plate and a protruding stop on the main plate to maintain a spacing between the main plates of the fins, said stop preferably having an annular shape along the edge of said opening.

[0022] The invention also proposes an electronic system comprising: - a platform suitable for accommodating electronic components, - a busbar adapted to carry electric current between electronic components and fixed to the platform by means of at least one fixing element, and - at least one heat exchanger as above, fixed to the platform by means of said fixing element, said fixing element passing through the main opening.

[0023] Other advantageous and non-limiting features of the heat exchanger according to the invention, taken individually or in all technically possible combinations, are as follows: - the platform includes at least one heat transfer fluid outlet duct connected to said inlet and / or outlet opening of said heat exchanger; - said heat transfer fluid is a gas; - a compressor is planned which is fixed to the platform and which is configured to circulate the gas in said heat exchanger; - the outlet duct includes a sound reducer; - said heat transfer fluid is a dielectric liquid; - a dielectric fluid reservoir is provided, along with a dielectric fluid supply line to the inlet opening of the heat exchanger equipped with a pump, and at least one return line configured to carry the dielectric fluid from the outlet opening of the heat exchanger to said reservoir; - at least one heat transfer fluid flow control valve is provided, which is electrically controlled and located upstream of said heat exchanger.

[0024] The invention also proposes a battery of accumulators for motor vehicles, comprising electrochemical cells and at least one electronic system as described above.

[0025] In addition, the invention also proposes a motor vehicle equipped with such a battery of accumulators.

[0026] Of course, the different features, variants and embodiments of the invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive. Detailed description of the invention

[0027] The following description with regard to the attached drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be carried out.

[0028] On the attached drawings:

[0029] [Fig.1] is a schematic view of a heat exchanger according to the invention;

[0030] [Fig.2] is an exploded view of part of the housing and fins of the heat exchanger of [Fig.1];

[0031] [Fig.3] is a schematic view of the housing and fins of the heat exchanger of [Fig.1];

[0032] [Fig.4] is a schematic view of an electronic and / or mechatronic system according to the invention and comprising the heat exchanger of [Fig.1]; and

[0033] [Fig.5] is a schematic cross-sectional view of part of the electronic and / or mechatronic system of [Fig.4].

[0034] Figure 1 schematically represents a heat exchanger 100 intended here to equip an electronic and / or mechatronic system of a battery of accumulators of a motor vehicle. This system, hereinafter referred to as the electronic system 200, will be described in a second part of this presentation.

[0035] As shown in figures 1 to 3, the heat exchanger 100 comprises a housing 110 which accommodates fins 120.

[0036] The housing 110 defines a watertight compartment. It comprises a main wall 113, a cover 119, and a side wall 116. The main wall 113 and the cover 119 are flat and allow the watertight compartment to be closed at the ends of the side wall 116.

[0037] The main wall 113 has a main opening 114 which is bordered on the inner side of the sealed housing by a tube 115 which extends to the hood 119. The hood 119 has a similar shape but is without a tube.

[0038] The side wall 116 has a cylindrical shape. More precisely, it has a shape of revolution around the axis of the tube 115, except for one side where it has a flat side parallel to this axis.

[0039] The main wall 113 and the hood 119 then have contours of corresponding shapes (with a circular arc part and a straight part).

[0040] The side wall 116 of the housing has an inlet opening 111 and an outlet opening 112 for the circulation of a heat transfer fluid. In [Fig. 1], the inlet opening 111 and outlet opening 112 are shown opposite each other, extending along parallel axes and forming an angle of 180° around the axis of the tube 115. Alternatively, the inlet opening 111 and outlet opening 112 could be positioned differently and form any angle, for example, 90° or 45°. These openings are, however, offset vertically (along the axis of the tube 115) to facilitate the passage of the fluid along all the fins 120.

[0041] The inlet opening 111 and outlet opening 112 are here traversed by fittings 111A, 112A facilitating their connection to hoses. These fittings can be metallic (aluminum, for example) or made of polymer material (ABS, for example). The end caps are fixed to the side wall 116. They can be screwed, snapped on, or even glued or welded.

[0042] Alternatively, the inlet opening 111 and outlet opening 112 can be bare and external conduits to the heat exchanger 100 can be attached to them.

[0043] At least two fins 120 are provided, positioned within the sealed housing. The fins 120 are therefore immersed in the heat transfer fluid. The heat exchanger 100 here comprises seven fins 120. Alternatively, the heat exchanger 120 could comprise dozens of fins 120.

[0044] The fins 120 each comprise a flat main plate 122 and a stop 123 projecting from the main plate 122. They are stacked in the housing, in contact with each other, between the main wall 113 and the cover 119, over the entire height of the housing.

[0045] The main plate 122 of each fin has an opening 121 engaged with the tube 115. Preferably, the tube 115 is cylindrical and the openings 121 of the fins are circular. Their diameters are equal, within the assembly clearance, so as to ensure effective thermal contact between these elements. Alternatively, the tube 115 could be a rectangular parallelepiped and the openings 121 of the fins 120 could be rectangular.

[0046] The stops 123 keep the main plates 122 of the fins apart so that the heat transfer fluid can circulate between them. Here, each stop 123 is formed as a single piece with the main plate 122, but alternatively, they could be formed from separate pieces.

[0047] The stops 123 here have washer-like shapes that border the openings 121 on one side only of the main plates 122. Due to their thickness, they maintain a spacing between each of the main plates 122 and the fins 120. For example, the stops 123 are 1 mm thick. The fins 120 can thus be assembled so as to be glued to one another, the projections 12 defining a 1 mm spacing between the main plates 122.

[0048] The main plates 122 here also have a thickness of 1 mm. More generally, the thickness of the main plates 122 can be between 0.4 and 2 mm.

[0049] The main plates 122 of the fins 120 have an outside diameter of 30 mm. The housing 110 is adjusted to the dimensions of the fins. Thus, the main wall 113 of the housing 110 has an outside diameter of 34 mm. The dimensions of the heat exchanger are not limiting and can be adapted to the dimensions of the electronic system 200 and the hot spots to be cooled.

[0050] Preferably, the contact surfaces between the tube 115 and the fins 120 are machined to have minimal roughness to increase thermal contact.

[0051] All the fins 120 are identical here, except for the one placed against the hood 119. This fin 120A ([Fig.2]) is distinguished from the others by its stop 123A which has a thickness greater than that of the stops 123 of the other fins 120. Thus this stop 123A can engage in the circular opening provided in the hood 119, so that its end face extends to the height of the outer face of the hood 119.

[0052] It should be noted that the different parts of the housing 110 are laser welded together, here at the edges of the main wall 113 and the hood 119, as well as between the hood and the aforementioned stop 123A and between the latter and the tube 115, which gives the whole its airtight character.

[0053] The heat exchanger 100 is in particular intended to cool an element which is inserted into the main opening 114, through the tube 115. Preferably, the main opening 114 and the tube 115 are adapted to the shape of this element to be cooled so as to maximize the thermal contact between the tube 115 and the element.

[0054] Thus, this element exchanges its heat with the tube 115, the tube 115 exchanges its heat with the fins 120, and the fins 120 exchange their heat with the heat transfer fluid. The heat transfer fluid forms a continuous flow that passes through the sealed space delimited by the housing 110 and is thus renewed, allowing for continuous heat exchange. Each fin can therefore dissipate up to 100W of thermal power.

[0055] To improve heat conduction, the housing 110 and the fins 120 are made of aluminum. Alternatively, the fins 120 and the tube 115 could be made of any heat-conducting material, preferably metallic, such as copper (or aluminum). The cover 119 and the side wall 116 of the housing 110 could be made of materials different from that of the tube, for example, a polymer such as ABS.

[0056] Here, the heat exchanger 100 is used to cool the electronic system 200 illustrated in [Fig.4].

[0057] In this embodiment, this electronic system 200 is used to connect a battery to the electrical circuit of an electric or hybrid motor vehicle. It is thus fitted to the battery and connected to one of its two electrical terminals. In practice, two identical electronic systems 200 can be used, each connected to one of the two electrical terminals of the battery.

[0058] The electronic system 200 here comprises a platform which supports a busbar in which the electric current flows, electronic components, and at least one heat exchanger 100 of the aforementioned type.

[0059] In practice, the busbar is made up of several separate parts, each part being fixed to the platform via two fixing elements. It is then preferably provided as many 100 heat exchangers as there are fixing elements.

[0060] The electronic components here have the function of being able to interrupt the electric current. For example, the platform here accommodates a relay 310, a switch 320 and a fuse 330.

[0061] Relay 310 and switch 320 play a similar role to fuse 330, namely, they open the electrical circuit and thus stop the flow of electrical current in the vehicle's electrical system. Relay 310 is controlled and used during normal vehicle operation, particularly to cut off the power after the vehicle is parked. Fuse 330 automatically cuts off the power in the event of a short circuit. Switch 320 is controlled and is preferably of the pyroswitch type: it cuts off the power in the event of a vehicle accident.

[0062] The busbar 220 is adapted to carry the electric current between these electrical components. For example, it can carry a current of 500 amperes. Its various parts are fixed to the platform 210 by means of eight fixing screws 221.

[0063] In use, for example when charging the battery, the bus bar 220 can heat up (due to the electrical components), which generates hot spots, particularly at the fixing screws 221.

[0064] The heat exchangers 100 are then fixed to the busbar 220 (and therefore to the platform 210) at the fixing screws 221 and by means of these screws. In other words, the fixing screws 221 allow both the busbar 220 and the heat exchangers 100 to be fixed. They are threaded through the tubes 115 of the heat exchangers 100 for this purpose.

[0065] The fixing is thus achieved by clamping the tube 115 and the main wall 115 against the omnibus bar, which then makes it possible to exert no force on the fins 120. These fins are thus not deformed and they can therefore perform their function of evacuating heat in the best possible way.

[0066] This fixing is carried out in such a way that the main wall 113 or the hood 119 of the heat exchanger applies against the bus bar, to promote heat exchange.

[0067] In order to improve this thermal contact, layers of thermal paste (commonly called "thermal pad" in English) can be positioned between the heat exchangers 100 and the bus bar 220. Preferably, the main walls 113 and the hoods 119 of the housings 110 are machined to have minimal roughness to improve thermal contact, or even perfect flatness.

[0068] To fix the heat exchangers 100 as close as possible to the electronic components, the flat surface of the side wall 116 of each housing 110 is placed in contact with one of the electronic components. This flat surface also prevents any rotation of the heat exchanger 100 during its fixing, which facilitates its installation.

[0069] The heat exchanger 100 thus allows for a reduced space and optimizes the footprint of the electronic system 200. In addition, the heat exchanger 100 has a low weight and does not increase the weight of the electronic system 200.

[0070] In order to avoid the formation of electric arcs, the housing 110 of the heat exchanger 100 here has an electrically insulating coating on its outer face.

[0071] Still with the aim of avoiding the formation of electric arcs, two neighboring heat exchangers are positioned at a distance of at least 2 mm from each other, this distance being in practice here at least 8 mm.

[0072] The platform 210 is also configured to allow the circulation of the heat transfer fluid through the heat exchangers 100.

[0073] It includes in its thickness at least one outlet conduit 211. It has as many of these as there are heat exchangers 100.

[0074] Each of these outlet conduits 211 here has an opening equipped with a seal to receive one of the tips 112A of a heat exchanger 100 and an outlet.

[0075] In the embodiment illustrated in figures 4 and 5, the heat transfer fluid is pulsed air.

[0076] The platform 210 then carries means adapted to circulate this air. Here, it carries a compressor 230, for example, in the form of a fan. This compressor 230 is connected to the heat exchangers 100 by fluid supply lines 241. It should be noted that these supply lines are preferably made of insulating materials, or at least materials with high electrical resistance.

[0077] Alternatively, the air can be compressed, i.e. the electronic system 200 can include a pump configured to circulate air in the heat exchangers 100.

[0078] When the air exits the heat exchangers 100, it enters the outlet ducts 211 integrated into the platform and then flows outwards. In order to avoid whistling noises related to the airflow, each outlet duct 211 includes a sound reducer 212 ([Fig.5]).

[0079] The sound reducer here comprises a perforated duct and, around it, a layer of sound-absorbing material. The perforated duct is, for example, made of aluminum. The sound-absorbing material, intended to absorb sound waves (and thus any whistling of the airflow), may be made of basalt wool, flax, or hemp, for example. Alternatively, the sound reducer It may be a ball or baffle sound reducer. The sound reducer 212 can be screwed or pressed into the platform 210.

[0080] Alternatively, the heat transfer fluid may be a dielectric liquid. In this case, the electronic system 200 includes a dielectric liquid reservoir, supply lines 241 for the dielectric liquid to each of the heat exchangers 100, and a return line for the liquid to the reservoir. A pump is then provided to circulate the dielectric liquid to the inlet openings 111 of the heat exchangers 100.

[0081] In all cases, the electronic system 200 preferably includes at least one electrically controlled valve 250 ([Fig.4]), located at the inlet of at least one heat exchanger 100. Here, the electronic system 200 includes six valves 250 (here solenoid valves) allowing the regulation of the flow of heat transfer fluid delivered to each heat exchanger 100. The valves 250 can, for example, be controlled by a control unit which allows the flow of each heat exchanger 100 to be adapted according to the temperature detected at the corresponding fixing screw (or the temperature of the fluid at the outlet of the exchanger).

[0082] Alternatively, each fluid inlet could have a shape (for example Venturi) allowing the flow of heat transfer fluid to be regulated for each heat exchanger 100.

[0083] The present invention is in no way limited to the embodiment described and represented, but a person skilled in the art will be able to make any variation in accordance with the invention.

[0084] Typically, the heat exchangers 100 could be fixed not to the ends of the busbar parts, but to the middle of these parts.

Claims

Demands

1. Electronic system (200) comprising: - a platform (210) adapted to accommodate electronic components, - a busbar (220) adapted to carry electric current between the electronic components and fixed to the platform (210) by means of at least one fastening element (221), and - at least one heat exchanger (100) comprising: H a housing (110) which delimits a sealed compartment and which has an inlet opening (111) and an outlet opening (112) for a heat transfer fluid, this housing (110) having a main wall (113) which has a main opening (114) bordered on the side of the sealed compartment by a tube (115), and H at least two fins (120) stacked on the main wall (113) in said sealed compartment, each of which has an opening (121) engaged on the tube (115) so as to be in contact with the latter,said heat exchanger (100) being fixed to the platform (210) by means of said fixing element (221), said fixing element (221) passing through the main opening (114).

2. Electronic system (200) according to claim 1, in which the housing (110) has a side wall (116) that is partly cylindrical with a flat and in which the main wall (113) and the at least two fins (120) have contours of shapes that are partly circular and partly straight.

3. Electronic system (200) according to any one of claims 1 or 2, wherein the housing (110) has an electrically insulating coating on its outer face.

4. Electronic system (200) according to any one of claims 1 to 3, wherein each fin (120) comprises a main plate (122) and a stop (123) projecting from the main plate (122) to maintain a spacing between the main plates (122) of the fins (120), said stop (123) preferably having an annular shape along the edge of said opening (121).

5. Electronic system (200) according to any one of claims 1 to 4, wherein the platform (210) comprises at least one outlet conduit (211) of heat transfer fluid connected to said inlet (111) and / or outlet (112) opening of said heat exchanger (100).

6. Electronic system (200) according to any one of claims 1 to 5, wherein said heat transfer fluid is a gas and wherein a compressor (230) is provided which is fixed to the platform (210) and which is configured to circulate the gas in said heat exchanger (100).

7. Electronic system (200) according to claim 6, wherein the output conduit (211) includes a sound reducer (212).

8. Electronic system (200) according to any one of claims 4 and 5, wherein said heat transfer fluid is a dielectric liquid and wherein the following are provided: - a reservoir of dielectric liquid, - a supply line for the dielectric liquid (241) into the inlet opening (111) of the heat exchanger (100) which is equipped with a pump and - at least one return line configured to carry the dielectric liquid from the outlet opening (112) of the heat exchanger (100) to said reservoir.

9. Electronic system (200) according to any one of claims 4 to 8, further comprising at least one heat transfer fluid flow control valve (250) which is electrically controlled and which is located upstream of said heat exchanger (100).

10. A motor vehicle accumulator battery comprising electrochemical cells and at least one electronic system (200) conforming to any one of claims 4 to 9.

11. Motor vehicle, characterized in that it comprises a battery of accumulators conforming to claim 10.

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