Heat exchanger, and associated electronic system and motor vehicle

Abstract

The invention relates to a heat exchanger comprising: - a housing which delimits a sealed housing and which has an inlet opening and an outlet opening for a heat-transfer fluid, said housing comprising a main wall, and - at least two fins stacked on the main wall at a distance from each other in said sealed housing. According to the invention, the main wall has a main opening which on the sealed housing side is bordered by a tube, and the at least two fins each have an opening engaging with the tube so as to be in contact therewith.

Description

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 housing which delimits a sealed housing and which has an inlet opening and an outlet opening for heat transfer fluid, this housing 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 storage battery equipped with this electronic system and a motor vehicle equipped with this storage battery. STATE OF THE ART

[0004] Electric or hybrid vehicles include a battery of accumulators.

[0005] Such a storage battery 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 if necessary. These components are positioned along a bus bar in which the input or output current of 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 resort to rapid charging using high electrical power.

[0009] Fast charging generates a strong temperature increase, especially in the electrical components, which generates a temperature increase in the bus bar.

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

[0011] These hot spots can eventually damage electronic components.

[0012] To preserve the electronic components, the case is usually 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 overcome the aforementioned drawback of the state of the art, the present invention proposes to directly cool the hot spots of the housing.

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

[0015] The plaintiff noted that the hot spots are generally located at the bus bar attachment elements.

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

[0017] The fixing element (screw, snap-in pin, etc.) is therefore introduced into the heat exchanger, through its main opening and its tube. Thus, thanks to the invention, the heat exchanger is in thermal contact with the fixing element over its entire height.

[0018] 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 efficient dissipation of the accumulated heat. The fixing element is thus cooled efficiently.

[0019] In addition, the use of the fixing element to fix the heat exchanger means that no additional fixing means is required and thus the overall size and mass of the assembly are optimized.

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

[0021] Other advantageous and non-limiting characteristics of the heat exchanger according to the invention, taken individually or in all technically possible combinations, are the following: - the housing comprises a partly cylindrical side wall with a flat surface and in which the main wall and the at least two fins have contours of partly circular and partly straight shapes; - the casing has an electrically insulating coating on the external face; - each fin comprises a main plate and a stop projecting from the main plate to maintain a spacing between the main plates of the fins, said stop preferably having an annular shape running along the edge of said opening.

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

[0023] Other advantageous and non-limiting characteristics of the heat exchanger according to the invention, taken individually or in all technically possible combinations, are the following: - the platform comprises at least one heat transfer fluid outlet conduit connected to said inlet and / or outlet opening of said heat exchanger; - said heat transfer fluid is a gas; - a compressor is provided 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 liquid reservoir is provided, a line for supplying the dielectric liquid into the inlet opening of the heat exchanger which is equipped with a pump and at least one return conduit configured to convey the dielectric liquid 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 which is located upstream of said heat exchanger.

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

[0025] Furthermore, the invention also provides a motor vehicle equipped with such an accumulator battery.

[0026] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. DETAILED DESCRIPTION OF THE INVENTION

[0027] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[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 a portion 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 Figure 1; and

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

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

[0035] As shown in Figures 1-3, the heat exchanger 100 includes a housing 110 that houses fins 120.

[0036] The housing 110 delimits a sealed housing. For this purpose, 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 they make it possible to close the sealed housing at the ends of the side wall 116.

[0037] The main wall 113 has a main opening 114 which is bordered on the inside of the sealed housing by a tube 115 which extends to the cover 119. The cover 119 has a similar shape but is devoid of 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, with the exception of one side where it has a flat parallel to this axis.

[0039] The main wall 113 and the cover 119 then have contours of corresponding shapes (with an arc-shaped 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 Figure 1, the inlet 111 and outlet 112 openings are shown opposite each other, they thus extend along parallel axes and form an angle of 180° around the axis of the tube 115. Alternatively, the inlet 111 and outlet 112 openings could be placed differently and form any angle, 90° or 45° for example. These openings are however offset in height (along the axis of the tube 115), to promote the passage of the fluid along all the fins 120.

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

[0042] Alternatively, the inlet 111 and outlet 112 openings may be bare and conduits external to the heat exchanger 100 may be attached thereto.

[0043] At least two fins 120 are provided positioned in 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 on the tube 115. Preferably, the tube 115 is cylindrical of revolution and the openings 121 of the fins are circular. Their diameters are equal, apart from the mounting 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 at a distance from each other 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 the shape of washers which border the openings 121, on one side only of the main plates 122. Due to their thickness, they make it possible to maintain a spacing between each of the main plates 122 of the fins 120. For example, the stops 123 have a thickness of 1 mm. The fins 120 can thus be assembled so as to be glued to each other, the projections 12 defining a spacing of 1 mm 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 here have an outer diameter of 30 mm. The housing 110 is adjusted to the dimensions of the fins. Thus, here, the main wall 113 of the housing 110 has an outer 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 hot spots to cool.

[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, with the exception of the one placed against the cover 119. This fin 120A (figure 2) is in fact 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 cover 119, such that its end face extends at the height of the external face of the cover 119.

[0052] It will 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 cover 119, as well as between the cover and the aforementioned stop 123A and between the latter and the tube 115, which gives the assembly its hermetic 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 which passes through the sealed space delimited by the housing 110 and is then renewed, allowing a continuous heat exchange. Each fin can thus dissipate up to 100W of thermal power.

[0055] In order to improve heat conduction, the housing 110 and the fins 120 are here made of aluminum. Alternatively, the fins 120 and the tube 115 could be made of any heat-conducting material, preferably metallic, such as for example 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 employed to cool the electronic system 200 illustrated in FIG. 4.

[0057] This electronic system 200 is, in this embodiment, used for connecting a storage battery to the electrical circuit of an electric or hybrid motor vehicle. It thus equips the storage battery and is connected to one of its two electrical terminals. In practice, two identical electronic systems 200 may be used, respectively connected to the two electrical terminals of the battery.

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

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

[0060] The electronic components here are used to cut off the electrical current. For example, the platform here houses a relay 310, a switch 320 and a fuse 330.

[0061] Relay 310 and switch 320 play a similar role to fuse 330, i.e. they open the electrical circuit and therefore stop the propagation of electric current in the vehicle's electrical network. Relay 310 is controlled and is used during normal use of the motor vehicle, in particular to cut off the power after the vehicle has been 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 an accident involving the motor vehicle.

[0062] The bus bar 220 is suitable for carrying electrical current between these electrical components. For example, it can carry a current of 500 amperes. Its various parts are here fixed to the platform 210 using eight fixing screws 221.

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

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

[0065] The fixing is thus carried out by clamping the tube 115 and the main wall 115 against the bus 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 heat dissipation function as well as possible.

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

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

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

[0069] The heat exchanger 100 thus makes it possible to occupy a reduced space and to optimize the size of the electronic system 200. In addition, the heat exchanger 100 represents a low weight and makes it possible not to weigh down the electronic system 200.

[0070] In order to prevent 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 100 are positioned at a distance of at least 2 mm from each other, this distance being in practice at least 8 mm here.

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

[0073] In fact, it includes in its thickness at least one outlet duct 211. Here, it includes as many as there are heat exchangers 100.

[0074] Each of these outlet ducts 211 here has a mouth equipped with a seal to receive one of the end pieces 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 in the form of a fan, for example. This compressor 230 is here connected to the heat exchangers 100 by fluid supply lines 241. It will be noted that these supply lines are preferably made of insulating materials, or at least having high electrical resistances.

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

[0078] When the air leaves the heat exchangers 100, it enters the outlet ducts 211 integrated into the platform and then opens outwards. In order to avoid whistling noises linked to the air flow, each outlet duct 211 here comprises a sound reducer 212 (figure 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 therefore the possible whistling airflow) may consist of basalt, flax or hemp wool for example. Alternatively, the sound reducer may be a ball or baffle sound reducer. The sound reducer 212 may be screwed or forced into the platform 210.

[0080] Alternatively, the heat transfer fluid may be a dielectric liquid. In this case, the electronic system 200 comprises a reservoir of dielectric liquid, lines 241 for supplying the dielectric liquid to each of the heat exchangers 100 and a conduit for returning the liquid to the reservoir. A pump is then provided for circulating the dielectric liquid to the inlet openings 111 of the heat exchangers 100.

[0081] In all cases, the electronic system 200 preferably comprises at least one electrically controlled valve 250 (figure 4), located at the inlet of at least one heat exchanger 100. Here, the electronic system 200 comprises six valves 250 (here solenoid valves) making it possible to regulate the flow rate of heat transfer fluid conveyed to each heat exchanger 100. The valves 250 can for example be controlled by a control unit which makes it possible to adapt the flow rate of each heat exchanger 100 according to the temperature detected at the level of 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) making it possible to regulate the flow of heat transfer fluid for each heat exchanger 100.

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

[0084] Typically, the heat exchangers 100 could be attached not to the ends of the busbar portions, but to the middle of those portions.

Claims

CLAIMS

1. Heat exchanger (100) comprising: - a housing (110) which delimits a sealed housing and which has an inlet opening (111) and an outlet opening (112) for a heat transfer fluid, this housing (110) comprising a main wall (113), and - at least two fins (120) stacked on the main wall (113) in said sealed housing, characterized in that the main wall (113) has a main opening (114) which is bordered on the side of the sealed housing by a tube (115), and in that the at least two fins (120) each have an opening (121) engaged on the tube (115) so as to be in contact with the latter.

2. Heat exchanger (100) according to claim 1, in which the housing (110) comprises a side wall (116) which is partly cylindrical with a flat and in which the main wall (113) and the at least two fins (120) have contours of partly circular and partly straight shapes.

3. Heat exchanger (100) according to one of claims 1 or 2, in which the housing (110) has an electrically insulating coating on its external face.

4. Heat exchanger (100) according to one of claims 1 to 3, in which 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 running along the edge of said opening (121).

5. Electronic system (200) comprising: - a platform (210) adapted to accommodate electronic components, - a bus bar (220) adapted to carry electric current between the electronic components and fixed on the platform (210) by means of at least one fixing element (221), and - at least one heat exchanger (100) according to one of claims 1 to 4 fixed on the platform (210) by means of said fixing element (221), said fixing element (221) passing through the main opening (114).

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

7. Electronic system (200) according to one of claims 5 and 6, 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).

8. The electronic system (200) of claim 7, wherein the output conduit (211) comprises a sound reducer (212).

9. Electronic system (200) according to one of claims 5 and 6, wherein said heat transfer fluid is a dielectric liquid and in which it is provided: - a reservoir of dielectric liquid, - a line for supplying 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 conduit configured to convey the dielectric liquid from the outlet opening (112) of the heat exchanger (100) to said reservoir.

10. Electronic system (200) according to one of claims 5 to 9, further comprising at least one valve (250) for regulating the flow rate of heat transfer fluid which is electrically controlled and which is located upstream of said heat exchanger (100).

11. Accumulator battery for a motor vehicle, comprising electrochemical cells and at least one electronic system (200) according to one of claims 5 to 10.

12. Motor vehicle, characterized in that it comprises an accumulator battery according to claim 11.

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