Electronic device for controlling an electric radiator.

Abstract

Title: Electronic device for controlling an electric radiator. The present invention relates to an electronic device for controlling an electric radiator, the electronic control device comprising at least one housing defining an internal volume bordered by a bottom wall (33) of the housing and in which at least one printed circuit board is housed, the printed circuit board comprising a power module (7) in which a plurality of electronic components are housed, characterized in that the power module (7) is arranged against the bottom wall (33) of the housing with a thermal paste (8) which is interposed between the power module (7) and the bottom wall (33) of the housing. (Figure 3)

Description

Title of the invention: Electronic device for controlling an electric radiator.

[0001] The present invention relates to the field of electric heating devices, and it relates more particularly to an electronic control device capable of controlling the operation of such electric heating devices.

[0002] Vehicles, and in particular motor vehicles, are frequently equipped with an electric heating device intended to be mounted in a ventilation, heating and / or air conditioning system of the motor vehicle for heating an air flow passing through a duct of this system. In this context, electric heating devices, also commonly called electric radiators, comprise an electronic control device and a heating block.

[0003] The heating block is intended to be crossed by the air flow such that a heat exchange takes place between heating members, arranged in the heating block, and the air flow passing through the duct of the ventilation, heating and / or air conditioning installation. The heating members are in particular resistive elements, electrically powered according to the calories that they must release to heat the air flow appropriately.

[0004] The electronic control device is intended in particular to transmit a control instruction to the heating members and to enable the electrical supply of these heating members. For this purpose, the electronic control device comprises a plurality of electronic components installed on a printed circuit board. Among the electronic components installed on this printed circuit board, it is possible in particular to distinguish transistors, for example of the IGBT type (English acronym for "Insulated Gate Bipolar Transistor" which can be translated as Insulated Gate Bipolar Transistor in French), which are respectively dedicated to one of the heating members for the transmission of the electrical supply and the transmission of instructions associated with this heating member. Each transistor present on the printed circuit board is thus connected to one of the heating members and to a dedicated microprocessor.

[0005] The evolution of ventilation, heating and / or air conditioning systems present on vehicles involves managing various functions and in particular implementing each of the heating elements of an electric radiator separately, and with increasingly greater electrical powers. This results in an increasingly significant dimensioning of the associated electronic control devices and the integration of more and more electronic components into printed circuit boards. This is incompatible with the requirements for reducing the size of automotive components.

[0006] The present invention falls within this context and aims to overcome certain drawbacks of the prior art, and in particular to reduce the size of the electronic control device without reducing the performance of the electric radiator.

[0007] The invention thus relates to an electronic device for controlling an electric radiator, the electronic control device comprising at least one housing defining an internal volume bordered by a bottom wall of the housing and in which at least one printed circuit board is housed, the printed circuit board comprising a power module in which a plurality of electronic components are housed, characterized in that the power module is arranged against the bottom wall of the housing with a thermal paste which is interposed between the power module and the bottom wall of the housing.

[0008] Such a power module makes it possible to group the functionalities of a plurality of transistors such as IGBTs, by grouping the various associated microprocessors into different layers within the same structure. It is understood that this grouping makes it possible in particular to save space within the electronic control device and more particularly space on the printed circuit board. Thus, the integration of a power module on the printed circuit board makes it possible to limit the size of the printed circuit board and therefore of the electronic control device as a whole. This free space can also be used to install other electronic components on the printed circuit board and increase the functionalities of the electronic control device and therefore of the associated electric radiator.

[0009] According to the invention, the power module is arranged against the bottom wall of the housing with a thermal paste interposed between the power module and the bottom wall of the housing. It is understood that the power module is arranged as close as possible to the bottom wall of the housing so that the exchange of calories taking place between the power module and the bottom wall, and therefore with the exterior of the housing of the electronic control device, is optimal. In other words, the arrangement of the power module relative to the bottom wall is carried out in such a way that no insulating element, such as a layer of air, limits the exchange of calories between the power module and the bottom wall. In this context, the thermal paste is a highly heat-conducting element and makes it possible to ensure that the entire surface of the power module participates in exchanging calories with the bottom wall.Therefore, it is advantageous if the power module is pressed against the wall of . bottom by compressing the thermal paste. It is understood that the thermal paste makes it possible to overcome manufacturing and assembly tolerances and the risk of seeing air present between the power module and the bottom wall. The malleability of the thermal paste when the power module is attached to the bottom wall allows the thermal paste to fill the empty spaces and allows the entire surface of the power module intended to be pressed against the bottom wall to exchange calories with the bottom wall. Locally, depending on the surface roughness in particular and the malleability of the thermal paste, the power module may be in direct contact with the bottom wall or in indirect contact with interposed thermal paste.

[0010] According to a characteristic of the invention, the power module is interposed between the bottom wall and the printed circuit board.

[0011] It is understood that the power module disposed against the bottom wall of the housing is in contact with a face of the printed circuit board opposite the bottom wall of the housing. It should be noted that the power module comprises pins passing through the printed circuit board so as to be able to be connected to at least one track of the printed circuit board. These pins or connection tabs of the power module are soldered to the track on the face of the printed circuit board opposite the face of the printed circuit board opposite the bottom wall.

[0012] According to a characteristic of the invention, the printed circuit board is fixed by fixing elements to the housing, the power module being pressed against the bottom wall of the housing by the printed circuit board.

[0013] The fixing elements are intended to fix the position of the printed circuit board. These fixing elements may take the form of screws cooperating with fixing means secured to the housing or elastic fitting means such as clips. Their implementation helps to bring the printed circuit board closer to the bottom wall of the housing, so that this fixing of the printed circuit board makes it possible to constrain the power module between the printed circuit board and the bottom wall of the housing.

[0014] According to a characteristic of the invention, the electronic control device comprises at least one heat dissipation means integral with the housing and projecting from an external face of the bottom wall of the housing.

[0015] According to a characteristic of the invention, the power module is at right angles to the heat dissipation means.

[0016] This arrangement of the power module in line with the heat dissipation means makes it possible to efficiently evacuate the calories released by the operation of the power module, since the heat dissipation means is arranged as close as possible to the power module.

[0017] According to a characteristic of the invention, the at least one heat dissipation means is made in one piece with the housing.

[0018] According to a characteristic of the invention, the at least one heat dissipation means extends mainly in a longitudinal and vertical plane, with the vertical direction substantially perpendicular to the bottom wall, the power module being arranged in the center of the heat dissipation means in said longitudinal direction.

[0019] According to a characteristic of the invention, the housing is formed from a metallic material, preferably aluminum. Such a material allows the housing to have, among other things, thermal conductivity characteristics making it capable of easily discharging the heat generated by the various electronic components within the housing. It should be noted that the housing may be formed from a metallic material other than aluminum provided that this material has thermal conductivity characteristics making it capable of easily discharging the heat generated in particular by the operation of the power module within the housing.

[0020] According to a characteristic of the invention, the thermal paste is formed from polyphenylene sulfide loaded with 30% glass fibers.

[0021] According to a characteristic of the invention, the housing comprises a bowl for receiving the thermal paste.

[0022] This receiving bowl prevents the thermal paste from spreading uncontrollably in the housing. It should be noted that this receiving bowl can accommodate or receive the power module depending on the dimensions of the receiving bowl.

[0023] The present invention also relates to an electric radiator comprising an electronic control device in accordance with any one of the preceding characteristics.

[0024] The invention also relates to a method of assembling an electronic control device, the assembly method implements: - at least a first step during which the thermal paste is deposited on the bottom wall of the case, - at least a second step during which the power module is placed on the thermal paste and pressed against the bottom wall of the case, - at least a third step during which the printed circuit board is fixed to the housing.

[0025] According to a characteristic of the invention, the assembly method implements at least one second additional step occurring before the second step and during which the power module is secured to the printed circuit board.

[0026] The power module is pressed against the bottom wall of the housing and is constrained between the bottom wall and the printed circuit board. This arrangement of the power module can be carried out in conjunction with the installation of the printed circuit board in the housing or independently. Indeed, the power module can be installed on the printed circuit board and the pins of the power module soldered on said board prior to the installation of the printed circuit board in the housing. Thus, the installation of the printed circuit board in the housing is carried out in conjunction with the installation of the power module in the housing with a thermal paste previously deposited on the bottom wall of the housing and interposed between the bottom wall and the module.

[0027] The module can also be pressed against the bottom wall with the thermal paste interposed between the bottom wall and the power module, then the printed circuit board is installed in the housing and constrains the power module between the bottom wall and the printed circuit board.

[0028] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several exemplary embodiments given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0029] [Fig. 1] schematically represents an electric radiator comprising a heating body and an electronic control device according to the invention;

[0030] [Fig.2] schematically represents a housing of the electronic control device represented by [Fig.l];

[0031] [Fig.3] schematically represents a sectional view of a lower compartment of the electronic control device during an assembly process in which a power module is intended to be pressed against a bottom wall of the housing;

[0032] [Fig.4] schematically represents the lower compartment of the housing in which the power module represented by [Fig.3] is pressed against a bottom wall of the housing;

[0033] [Fig.5] schematically represents a sectional view of the lower compartment of the housing as represented by [Fig.4];

[0034] [Fig.6] schematically represents a top view of the lower compartment in which a printed circuit card is housed;

[0035] [Fig.7] schematically represents another embodiment of the invention in which a receiving bowl is intended to receive a thermal paste.

[0036] It should first be noted that although the figures set out the invention in detail for its implementation, these figures can of course be used to better define the invention, where appropriate. It should also be noted that these figures only set out examples of embodiments of the invention.

[0037] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the state of the art.

[0038] In the figures, the elements common to several figures retain the same reference.

[0039] [Fig.l] represents an electric radiator 1 according to one aspect of the invention configured to be installed in a heating, ventilation and / or air conditioning installation of a motor vehicle. The electric radiator 1 is in particular intended to heat a flow of air circulating in a duct of the heating, ventilation and / or air conditioning installation, said electric radiator being arranged across this duct so that a heating body 2 of the electric radiator is crossed by the flow of air.

[0040] The electric radiator 1 comprises at least the heating body 2 and an electronic control device 3. The heating body 2 extends in a main vertical elongation direction substantially parallel to the axis V and comprises a plurality of heating members arranged parallel to each other within the heating body 2. These heating members, in particular resistive elements electrically powered via the electronic control device, are intended to carry out an exchange of calories with the air flow passing through the electric radiator 1.

[0041] The electronic control device 3 is arranged at a vertical end of the electric radiator 1 and makes it possible to control the operation and to electrically power the heating members of the electric radiator 1. For this purpose, the electronic control device 3 comprises a housing 31 in which several electronic components are housed. The housing 31 comprises a high-voltage connection member 41 intended to be connected with a high-voltage power supply cable and a low-voltage connection member 42 intended to be connected with a low-voltage power supply cable.

[0042] Furthermore, the housing 31 is, in the embodiment shown, formed from aluminum. Such a material has excellent characteristics in terms of thermal conductivity, i.e. aluminum is an excellent heat conductor. This property of aluminum makes it possible to efficiently transmit the heat emitted by the electronic components within the housing and mainly here by the power module which will be described later and which is intended according to the invention to be in contact with a metal wall, preferably made of aluminum, of the housing. It is understood that this emitted heat is subsequently dissipated towards the environment outside the housing 31. In other words, the material from which the housing is formed helps to cool the electronic control device 3. It should be noted that more broadly, the housing 31 could be formed from another material, in particular metal, provided that the latter has a thermal conductivity allowing the housing 31 to be cooled.

[0043] [Fig. 2] represents the housing 31 of the electronic control device 3. The housing 31 is formed of a lower compartment 311 and an upper compartment 312. The lower and upper compartments 311 and 312 are fixed to each other, here by means of a snap-fastening system by elastic deformation. More precisely, this snap-fastening system by elastic deformation is formed by the cooperation between a plurality of elastically deformable tabs 5 and a plurality of holding pins 51, each holding pin 51 being associated with a tab 5.

[0044] Furthermore, the lower compartment 311 comprises a plurality of fixing means 32 intended to accommodate a fixing means such as a screw, for example for fixing the electric radiator 1 to the heating, ventilation and / or air conditioning installation.

[0045] The housing 31 defines within it an internal volume defined between the upper compartment 312 and the lower compartment 311 and intended to house at least one printed circuit board on which is connected at least a part of the electronic components participating in the operation of the electronic control device 3. This internal volume is delimited in particular by a bottom wall 33 of the housing 31, and more precisely of the lower compartment 311. The bottom wall 33 comprises a window 331 intended to be crossed by electrical connection means, not shown here, allowing the connection of the heating body 2 to the electronic control device 3.

[0046] As will be more particularly described in connection with [Fig. 4], the housing 31 comprises fixing means 34 projecting from the bottom wall 33 in a direction parallel to the axis V. These fixing means 34 are intended to cooperate with a fixing element, such as screws, in order to secure to the lower compartment 311 a printed circuit board as mentioned previously, namely a board on which the various components making it possible to control the operation of the electric radiator 1 are installed.

[0047] The lower compartment 311 also comprises a heat dissipation means 35 extending in a vertical direction, parallel to the axis V, from an external face of the lower compartment 311, and more particularly an external face of the bottom wall 33, opposite the internal volume of the housing 31. This means of dissipating thermal dissipation 35 allows, as will be described in more detail in connection with [Fig.3], to evacuate the heat emitted by the electronic components installed in the housing 31, and in particular the heat emitted by a power module which will now be described.

[0048] The bottom wall 33 comprises a receiving zone 6 intended to receive such a power module 7. This power module 7 is more particularly visible in [Fig. 3], which is a sectional view of the lower compartment 311 of the housing 31 along a longitudinal and vertical sectional plane, extending along the axis L and the axis V. The power module 7 is here represented during the assembly process of the electronic control device 3, at a distance from the bottom wall 33, it being understood that at the end of the assembly process, the power module is intended to be as close as possible to the bottom wall.

[0049] The power module 7 is an electronic device in which a plurality of electronic components are housed, these electronic components in particular ensuring the functions of a plurality of transistors, for example of the IGBT type, within a single device. This power module 7 comprises a plurality of pins 71 intended to be connected to at least one track of the previously mentioned printed circuit board. It should be noted that such a power module 7 generates a large quantity of heat which must be evacuated from the housing 31 to ensure the proper functioning of the various electronic components installed in the housing 31.

[0050] The power module 7 is arranged as close as possible to the bottom wall 33 so that the heat generated by the power module 7 is transmitted to the bottom wall 33 of the housing 31 in order to be evacuated. It should be understood by an arrangement of the power module 7 as close as possible to the bottom wall that the aim is to ensure that no layer of air that could limit the heat exchange between the power module 7 and the bottom wall 33 is interposed between the power module 7 and the bottom wall 33.

[0051] For this purpose, a thermal paste 8 is deposited on the bottom wall 33 of the housing 31. More precisely and as shown in [Fig. 4], this thermal paste 8 is deposited at the receiving zone 6 of the bottom wall 33 of the housing 31. The power module 7 is then placed on the thermal paste 8 and pressed against the bottom wall 33, with the thermal paste 8 interposed between the power module 7 and the bottom wall 33. The pressing of the power module 7 tends to deform the thermal paste, which fills the gaps between the facing faces of the bottom wall and the power module, namely the lower face of the power module 7 and the internal face of the bottom wall 33. Where appropriate, depending on the surface roughness, the power module 7 may be in direct contact with the bottom wall.

[0052] As can be seen in particular from [Fig.2], the reception zone 6 is arranged in line with the heat dissipation means 35. As a result, the power module 7 and the thermal paste 8, interposed between the bottom wall 33 and the power module 7, are arranged vertically above the heat dissipation means 35, directly in line with the latter, to optimize the transfer of calories to the outside of the electronic control device 3, and allow the heat dissipation means 35 to optimally cool the power module 7.

[0053] The thermal paste 8 is, in the embodiment shown, formed from polyphenylene sulfide loaded with 30% glass fibers. This thermal paste 8 advantageously makes it possible to improve the heat transfer from the power module 7 to the heat dissipation means 35, by preventing the presence of a layer of air between the power module 7 and the bottom wall 33 associated with the heat dissipation means 35.

[0054] [Fig. 5] represents a sectional view of the lower compartment 311 comprising the power module 7 pressed against the bottom wall 33 along a sectional plane extending in a direction parallel to the axis T and a direction parallel to the axis V.

[0055] As visible in this [Fig.5], the heat dissipation means 35 is integral with the housing 31. More precisely, the heat dissipation means 35 is, in the embodiment shown, made of a single material with the housing 31. It is understood that the heat dissipation means 35 is, like the housing 31, formed by aluminum. As mentioned previously, aluminum has thermal conductivity properties allowing the heat generated by the power module to be transmitted to the bottom wall 33 and then to the heat dissipation means 35. This heat captured by the heat dissipation means 35 is then exchanged with the environment outside the electronic control device 3 in order to cool the interior of the housing 31.

[0056] As visible in [Fig. 5], the heat dissipation means 35 extends mainly in a vertical and longitudinal elongation plane, having a plurality of fingers which each extend in a vertical main elongation direction, that is to say a direction substantially parallel to the axis V. More precisely, these fingers extend, in this vertical main elongation direction, beyond the electronic control device 3 so that the fingers are opposite the heating body 2. Furthermore, the fingers are arranged longitudinally in series, to allow an exchange of calories with the air flow passing through the heating body over the entire longitudinal dimension thereof.

[0057] As can be seen in the illustrated example, the power module 7 can advantageously be arranged against the bottom wall of the housing so as to be arranged substantially in the center of the heat dissipation means 35 along the main longitudinal elongation direction. This arrangement of the power module 7 at center of the heat dissipation means 35 in the longitudinal direction makes it possible to effectively cool the power module 7.

[0058] [Fig. 6] represents the lower compartment 311 of the housing 31, and more precisely a part of the internal volume of the housing 31 in which a printed circuit board 9 as previously mentioned is arranged.

[0059] As seen in this [Fig.6], the printed circuit board 9 is secured to the housing 31 by a plurality of fixing elements 341, formed, in the embodiment shown, by screws. Each fixing element 341 is housed in a fixing means 34 so as to fix the position of the printed circuit board. During the fixing operation, the printed circuit board 9 is constrained between the fixing means 34 and the associated fixing elements 341 and this printed circuit board 9 tends to move closer to the bottom wall 33.

[0060] In this way, the power module 7 is interposed between the bottom wall 33 and the printed circuit board 9, the latter participating in pressing the power module 7 against the bottom wall 33. It should be noted that the power module 7 is fixed on this printed circuit board 9 by soldering the pins 71 of the power module on a face of the printed circuit board traversed by at least one track electrically connecting these pins 71 to power supply means and other electronic components present in the housing. More particularly, when the power module 7 is between the bottom wall 33 and the printed circuit board 9, the pins 71 of the power module 7 pass through the printed circuit board 9 so as to be connected on the face of the printed circuit board 9 opposite the face of the printed circuit board 9 which is opposite the power module 7.

[0061] It is understood from what has been described in connection with [Fig. 6] and from what has been previously mentioned that the method of assembling the electronic control device involves a first step during which the thermal paste 8 is deposited on the bottom wall 33 of the lower compartment 311 and more particularly at the level of the receiving zone 6. Then during a second step, the power module 7 is pressed against the bottom wall 33 of the housing 31, being placed on the thermal paste 8. Finally, during a third step, the printed circuit board 9 is fixed to the housing 31. This fixing is advantageously carried out by means of the fixing elements 341 and so that the power module 7, located between the printed circuit board 9 and the bottom wall 33, is pressed against the latter by the printed circuit board 9.

[0062] It should be noted that in a first embodiment of the assembly method, during a second additional step, occurring before the second step, the power module 7 is secured to the printed circuit board 9. In this first embodiment, the pins 71 of the power module 7 are soldered to the track of the printed circuit board 9, and the assembly formed by the power module and the printed circuit board is installed in the housing 31, the fixing of the printed circuit board participating in pressing the power module against the bottom wall 33.

[0063] In a second embodiment of the assembly method, the power module 7 is pressed against the bottom wall 33 of the housing 31 and then the printed circuit board 9 is installed in the housing 31, the pins 71 of the power module being soldered in a second step to the track of the printed circuit board 9. This embodiment makes it easier to position the power module precisely on the receiving area 6 covered with thermal paste, but it should be noted that this involves careful positioning of the printed circuit board so that the pins 71 of the power module already in place pass through holes provided in the printed circuit board 9.

[0064] [Fig. 7] represents an alternative embodiment of the invention in which the lower compartment 311 comprises a receiving bowl 10 for the thermal paste 8. This receiving bowl 10 is bordered by a retaining wall 101 for the thermal paste 8. This receiving bowl 10 advantageously makes it possible to contain the thermal paste 8 and to prevent the thermal paste 8 from overflowing beyond the part of the bottom wall 33 against which the power module 7 is pressed.

[0065] The invention, as just described, achieves the aims it set itself, by proposing an electronic control device in which a power module grouping the functionalities of a plurality of electronic components is connected to a printed circuit board, thus limiting the size of the printed circuit board but also of the electronic control device, the power module being arranged as close as possible to a wall of the housing of the electronic control device and optimizing the transfer of calories to the outside of this housing.Variants not described here could be implemented without departing from the context of the invention, since, in accordance with the invention, they comprise an electronic control device in which a power module connected to a printed circuit board is arranged as close as possible to a wall delimiting the electronic control device, with a thermal paste interposed between the power module and this wall to promote the transfer of calories.

Claims

Claims

1. Electronic control device (3) for an electric radiator (1), the electronic control device (3) comprising at least one housing (31) defining an internal volume bordered by a bottom wall (33) of the housing (31) and in which is housed at least one printed circuit board (9), the printed circuit board (9) comprising a power module (7) in which is housed a plurality of electronic components, characterized in that the power module (7) is arranged against the bottom wall (33) of the housing (31) with a thermal paste (8) which is interposed between the power module (7) and the bottom wall (33) of the housing (31), the printed circuit board (9) being fixed by fixing elements (341) to the housing (31), the power module (7) being pressed against the bottom wall (33) of the housing (31) by the printed circuit board (9).

2. Electronic control device (3) according to the preceding claim, characterized in that the power module (7) is interposed between the bottom wall (33) and the printed circuit board (9).

3. Electronic control device (3) according to any one of the preceding claims, characterized in that it comprises at least one heat dissipation means (35) integral with the housing (31) and projecting from an external face of the bottom wall (33) of the housing (31).

4. Electronic control device (3) according to the preceding claim, characterized in that the power module (7) is at right angles to the at least one heat dissipation means (35).

5. Electronic control device (3) according to any one of claims 3 and 4, characterized in that the at least one heat dissipation means (35) is made in one piece with the housing (31).

6. Electronic control device (3) according to any one of claims 3 to 5, characterized in that the at least one heat dissipation means (35) extends mainly in a longitudinal and vertical plane, with the vertical direction substantially perpendicular to the bottom wall (33), the power module being arranged in the center of the heat dissipation means (35) in said longitudinal direction.

7. Electronic control device (3) according to any one of the preceding claims, characterized in that the housing (31) comprises a receiving bowl (10) for the thermal paste (8).

8. Electric radiator (1) comprising an electronic control device (3) according to any one of the preceding claims.

9. Method for assembling an electronic control device (3) according to any one of the preceding claims, the assembly method implementing: - at least a first step during which the thermal paste (8) is deposited on the bottom wall (33) of the housing (31), - at least a second step during which the power module (7) is arranged on the thermal paste (8) and pressed against the bottom wall (33) of the housing (31), - at least a third step during which the printed circuit board (9) is fixed to the housing (31).

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