FR3073116A1 - HEATING UNIT COMPRISING A HEATING BLOCK OVERMOLDED BY A SEALING ELEMENT - Google Patents

Abstract

The invention relates to a heating unit (4) comprising at least one heating block (5) configured to generate heat, the heating unit (4) comprising a sealing element (17) at least partially overmoulding the block heater (5) for sealing the heating block (5).

Description

The invention relates to a heating unit for a motor vehicle.

The invention applies more particularly to ventilation, heating and / or air conditioning devices of motor vehicles (called HVAC, from the English "Heating, Ventilation and Air-Conditioning" in English).

In the automotive field, it is known to provide motor vehicles with a heating device. Such a heating device can in particular be used to heat air before it enters the passenger compartment of the motor vehicle.

In particular, in the context of hybrid or electric motor vehicles, it is known to use a so-called “high voltage” heating device.

The heating device conventionally comprises heating units, each received in a tube, the tubes being in contact with plates and / or fins aimed at improving the heat exchange with the air to be heated which circulates outside the tubes.

Each heating unit comprises, for example, one or more heating means electrically powered by two electrodes, the assembly comprising the heating means (s) and two electrodes being covered by electrical insulating elements. The heating means is for example an element with a positive temperature coefficient (or PTC, from the English "Positive Temperature Coefficient").

In order to ensure optimal operation of the device, and in particular to avoid any short circuit at the electrodes, it is necessary to avoid the infiltration of fluid or of contaminants, such as dust, into the heater.

In existing heating devices, a seal is achieved for this purpose at the two ends of the tube in which the heating unit is arranged.

However, it may be advantageous to circulate fluid, such as the air to be heated, inside the tube so as to promote the heat exchange between the fluid and the heating means, and thus optimize the operation of the device. of heating.

In addition, the seal produced at the ends of the tube can be long and difficult to achieve, requiring a welding step, and resulting in an additional cost during the manufacture of the heating device.

The object of the invention is to at least partially remedy these drawbacks.

To this end, the subject of the present invention is a heating unit comprising at least one heating block configured to generate heat, the heating unit comprising a sealing element at least partially overmolding the heating block to ensure sealing of the heating block.

According to one embodiment, the heating block is positioned between at least two insulating elements, the sealing element at least partially overmolding the two insulating elements.

According to another embodiment, each insulating element comprises an external face, the external faces comprising a part devoid of sealing element.

According to another embodiment, the two insulating elements are configured to form a heating chamber in which the heating block is arranged.

According to another embodiment, the sealing element is arranged in the heating chamber formed by the insulating elements.

According to another embodiment, the sealing element is configured to assemble the insulating elements together.

According to another embodiment, the sealing element is a curable material chosen from a silicone adhesive or gel, a rubber, a polyurethane adhesive or gel, and an epoxy adhesive or gel.

According to another embodiment, the heating block comprises at least one heating means and two electrodes in contact with the heating means.

The invention also relates to a heating device for a motor vehicle comprising at least one heating unit according to the invention and a tube, the heating unit being arranged inside the tube.

The invention also relates to a method for manufacturing a heating unit according to the invention, comprising at least the steps consisting in: placing the heating block in a mold, and overmolding the heating block with the sealing element.

According to one embodiment, the step for overmolding the heating block is carried out by compressing the heating block in the mold.

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the detailed explanatory description which follows, of several embodiments of the invention given by way of purely illustrative and nonlimiting examples, with reference to the appended schematic drawings, in which:

- Figure 1A shows a front view of a heating device for a motor vehicle;

- Figure 1B shows a sectional view along the cutting plane IB of the heating device of Figure 1 A;

- Figure 2 shows an exploded perspective view of a heating unit devoid of sealing element according to an embodiment of the invention;

- Figure 3 shows a perspective view of the heating unit devoid of sealing element of Figure 2 in an assembled configuration;

- Figure 4A shows a perspective view of the heating unit in Figure 3 molded by a sealing element;

- Figure 4B shows a sectional view along the section plane IVB of the heating unit and the heating block of Figure 4A;

- Figures 5A-5F show sectional views of a heating unit and a heating block molded by a sealing element according to other exemplary embodiments of the invention; and

- Figure 6 shows a top view of an example of a mold for overmolding the heating unit and the heating block of Figure 3 with the sealing element in order to obtain the overmolded heating unit of Figure 4A.

Heating device

As illustrated in FIGS. 1A and 1B, the invention relates to a heating device 1 for a motor vehicle. Such a heating device 1 is used in particular in electric and / or hybrid motor vehicles.

The heating device 1 can allow the heating of air intended for a passenger compartment of the motor vehicle. However, the heating device 1 can also make it possible to heat another fluid, such as the cooling fluid for a heat engine or water for a water circuit for heating the passenger compartment of the electric vehicle.

Such a heating device 1 comprises a plurality of heating modules 2. The heating modules 2 are in contact with fins 3 for heat exchange. The fins 3 are configured to dissipate heat on contact with the fluid to be heated.

The heating modules 2 are superimposed with respect to each other, in a stacking direction Y, the fins 3 extending between the heating modules 2.

The heating modules 2 extend mainly in a longitudinal direction X. The longitudinal direction X is orthogonal to the stacking direction Y of the heating modules 2.

The heating module 2 comprises a heating unit 4 which can be received in a tube 5 as visible in FIG. 1 B.

As illustrated in FIG. 2, the heating unit 4 comprises a heating block 5, advantageously electric. The heating tank 5 comprises two electrodes 6, 7 and at least one heating means 8 configured to generate heat.

According to one embodiment, the heating body 8 is an element with a positive temperature coefficient (also called PTC element for “Positive

Temperature Coefficient ”. A PTC element is configured to generate heat from an electric current.

As shown in FIG. 2, the heating block 5 can comprise a plurality of heating means 8. The heating means 8 are distributed, preferably regularly, in the longitudinal direction X.

The electrodes 6, 7 are configured to circulate an electric current in the heating means 8. The electrodes 6, 7 advantageously make it possible to apply a high voltage to the heating means 8, for example between 100 V and 1000 V.

As illustrated more particularly in FIGS. 2 and 4B, each electrode 6, 7 has a rectangular shape and extends in the longitudinal direction X. Each electrode 6, 7 thus comprises an internal face 6a, 7a and an external face 6b, 7b , advantageously parallel to each other.

The expressions “internal” and “external” according to the present invention are understood to designate what is closer and more distant, respectively, relative to the heating means 8.

When the heating block 5 is assembled, the heating means 8 are arranged between the electrodes 6, 7. More specifically, the electrodes 6, 7 enclose the heating means 8, so that the electrodes 6, 7 and the heating means 8 are superimposed in the stacking direction Y orthogonal to the longitudinal direction X. Each heating means 8 advantageously comes into contact with the internal faces 6a, 7a of the electrodes 6, 7.

The heating unit 4 also comprises at least two electrical insulating elements 9, 10. The insulating elements 9, 10 are configured to allow electrical insulation of the heating block 5. The insulating elements 9, 10 are also configured to allow thermal conduction heat generated by the heating means 8.

As illustrated more particularly in FIGS. 2, 4B and 3, each insulating element 9, 10 has a rectangular shape and extends in the longitudinal direction X. Each insulating element 9, 10 thus comprises an internal face 9a, 10a and a face external 9b, 10b, advantageously parallel to each other (the expressions “internal” and “external” must be understood as previously).

The insulating elements 9, 10 enclose the heating block 5, so that the insulating elements 9, 10 and the heating block 5 are superimposed in the stacking direction Y orthogonal to the longitudinal direction X. Each internal face 9a, 10a of an insulating element 9, 10 advantageously comes into contact with the external face 6b, 7b of one of the electrodes 6, 7.

According to one embodiment, the two insulating elements 9, 10 are arranged one with the other to form a heating chamber 13 in which the heating block 5 is arranged.

According to this embodiment, each insulating element 9, 10 comprises a flange 11, 12 projecting from its internal face 9a, 10a. The flange 11, 12 extends over a part, see over the whole, of the periphery of the insulating element 9, 10. The flanges 11,12 of the two insulating elements 9, 10 are opposite one another so as to delimit the heating chamber 13, as visible for example in FIG. 4B, 5A, 5B and 5C.

The heating chamber 13 can be open to the outside as can be seen for example in FIG. 3. In particular, the insulating elements 9, 10 can form an opening 18, in particular at the end 4a of the heating unit 4, making it possible to connect the heating chamber 13 with the outside.

In addition, the flanges 11, 12 of the two insulating elements 9, 10 may also not be in contact with each other, as illustrated in FIG. 5C.

According to another embodiment, the two insulating elements 9, 10, in particular the internal faces 9a, 10a, are substantially planar. In particular, the two insulating elements 9, 10 do not include a rim, as illustrated in FIGS. 5D, 5E and 5F.

So that electric current flows in the heating block 5, each electrode 6, 7 comprises an electrical terminal 14, 15 visible in particular in FIGS. 2 and 3. The terminals 14, 15 are arranged at one end 4a of the unit of heating 4 in the longitudinal direction X. As illustrated for example in FIGS. 2 and 3, the terminals 14, 15 can be in the form of plugs or connectors projecting from the insulating elements 9, 10 of the heating unit 4. The two terminals 14, 15 are advantageously located at the same end 4a of the heating unit 4.

The heating unit 4 according to the invention also comprises a sealing element 17.

The sealing element 17 is configured to seal the heating block 5.

According to one embodiment, the sealing element 17 is also configured to fix the two insulating elements 9, 10 together.

The expressions “sealing” and “sealing” according to the present invention are understood to denote an element making it possible to prevent the introduction of a fluid, in particular of water, or also of any other contaminants in contact with the heating block 5 from the 'outside.

The expression "exterior" according to the present invention is understood to denote what is located outside of the heating unit 4.

According to the invention, the sealing element 17 is initially in the form of a fluid, viscous or pasty product, capable of solidifying thereafter.

The sealing element 17 may be made of a curable material, such as a silicone polymer. The sealing element 17 can in particular be a thermosetting material, such as a polymer commonly used to coat electronic circuits (also called "potting" in English). By way of nonlimiting example, the sealing element 17 can be chosen from a silicone adhesive or gel, a rubber, a polyurethane adhesive or gel, an epoxy adhesive or gel.

The sealing element 17 is advantageously temperature resistant.

The sealing element is molded onto the heating block 5 of the heating unit 4.

We understand the expression "molded" according to the present invention as designating an element arranged around the heating block 5 once the heating block is assembled. The sealing element thus makes it possible to seal the heating block 5.

The sealing element 17 is however not disposed between the electrodes 6, 7 and the heating means 8, this in order not to interfere with the electrical conduction in the heating block 5.

According to the embodiments of the invention illustrated in FIGS. 5E and 5F, the sealing element 17 can be disposed between the insulating elements 9, 10. In this way, the sealing of the heating block is ensured by the element d and the insulating elements 9, 10.

In particular, according to the embodiment of FIG. 5E, the sealing element is arranged up to the end, that is to say at the edge, of the insulating elements

9, 10. However, this embodiment is not limiting and the sealing element 17 can be disposed beyond or before the end of the insulating elements 9,

10, as illustrated respectively in FIGS. 5D and 5F.

According to the embodiments of the invention illustrated in FIGS. 5A, 5B and 5C, the sealing element 17 can be placed in the heating chamber 13 delimited by the two insulating elements 9, 10.

According to the embodiments of the invention illustrated in FIGS. 4A, 4B, 5A, 5B and 5C, the sealing element 17 can also overmold the insulating elements 9, 10.

In particular, according to the embodiment of FIG. 5A, the sealing element 17 completely molds the insulating elements 9, 10. According to this embodiment, the sealing element 17 completely covers the external faces 9b, 10b of the insulating elements 9 , 10.

As a variant, according to the embodiments of FIGS. 4A, 4B, 5B, 5C and 5D, at least part of the external faces 9b, 10b of the insulating elements 9, 10 are not covered by the sealing element 17.

The external faces 9b, 10b of the insulating elements 9, 10 are then at least partially devoid of sealing element 17. This can make it possible to prevent the sealing element 17 from interfering with the thermal conduction produced by the insulating elements 9 , 10 outwards.

More precisely, according to the embodiment of FIG. 4B, a part 19a, 19b of the external faces 9b, 10b of the insulating elements 9, 10 is not covered by the sealing element 17. According to the embodiments of FIGS. 5B, 5C and

5D, all of the external faces 9b, 10b of the insulating elements 9, 10 are not covered by the sealing element 17.

In general, the sealing element 17 can be arranged by overmolding the heating block 5 in any conceivable way making it possible to seal the heating block 5, and in particular the electrodes 6, 7 of the heating block 5 and of the heating means 8.

Assembly process

The invention also relates to a method of assembling a heating unit 4 for a motor vehicle. An assembly method corresponding to the assembly of a heating unit 4 according to the embodiment of FIGS. 4A and 4B is described below.

The method includes a step of preliminary assembly of the heating unit 4.

During the assembly step, there is the heating unit 4, in particular the heating block 5 in a mold 20.

The method then comprises a compression step of the heating unit 4. The compression step is for example carried out by means of the mold 20 as illustrated in FIG. 6.

According to the embodiment illustrated in FIG. 6, the mold 20 comprises a fixed part 21 and a mobile part 22. The mobile part 22 is configured to be moved relative to the fixed part 21. For this purpose, the mobile part 22 can comprise pressure elements 23, such as one or more springs 23, configured to keep the movable part 22 in compression towards the fixed part 21.

The fixed part 21 includes a bottom wall 24.

According to one embodiment, a recess 25 protrudes from the bottom wall of the part 21. The recess is advantageously a flat surface which has a shape corresponding to the part 19a of the external face 9b of the insulating element 9 as illustrated in Figure 4B.

The mobile part 22 also includes a bottom wall 26.

According to one embodiment, a recess projects from the bottom wall of the part 21. The recess is advantageously a flat surface which has a shape corresponding to the part 19b of the external face 10b of the insulating element 10 as illustrated on Figure 4B.

During the compression step, the heating unit 4 is placed between the fixed part 21 and the mobile part 22 of the mold 20. The heating unit 4 is then compressed between the two fixed and mobile parts 21, 22 of the mold 20. The heating unit 4 is more particularly compressed by being in contact at the level of the external faces 9b, 10b of the insulating elements 9, 10 with the recesses 25, 27 respectively of the fixed and movable parts 21, 22 of the mold 20.

The compression step ensures satisfactory contact between all of the components of the heating unit 4 in order to optimize the dissipation of the heat generated by the heating means 8 during the operation of the heating device 1.

The compression step also makes it possible to prevent the sealing element 17 from being interposed between the electrodes 6, 7 and the heating means 8 during the filling step as described below, which could otherwise interfere with the electrical operation of the heating unit 4.

While keeping the heating unit compressed, the process then includes a filling step. During the filling step, the space left free 28 in the mold 20 is filled with the sealing element 17 around the heating block 5 and the heating unit 4.

The heating block 5 and the heating unit 4 are thus overmolded with the sealing element 17.

The method can then include a heating step. During the heating step, the heating unit 4 is heated in order to solidify the sealing element 17 in the case where it is a thermosetting material.

Once the sealing element 17 has solidified, the heating unit 4 can be removed from the mold 20, which is then overmolded as shown in FIG. 4A.

Although the method which has just been described corresponds to the assembly of a heating unit as illustrated in FIGS. 4A and 4B, other variants of this method are possible for the other embodiments of heating unit 4 illustrated in the figures. In particular, it is possible to mold only the heating block 5 in the mold and then to place the insulating elements 9, 10 on either side of the heating block 5 thereafter to obtain a heating unit 4 as shown by example in Figures 5E and 5F.

Benefits

As already indicated, the overmolding by the sealing element 17 makes it possible to avoid certain contaminants or fluid being able to be in contact with the heating block 5, which could otherwise lead to a short circuit and to a malfunction of the device. heating 1.

In addition, the overmolding by the sealing element 17 also makes it possible to assemble the two insulating elements 9, 10 one with the other in a solid manner so as to obtain a heating unit 4 in one piece.

The heating unit 4 can then be placed in a tube 5 forming part of the heating device 1 of the motor vehicle, as illustrated in FIG. 1 B.

Obviously, the invention is not limited to the embodiments described above and provided only by way of example. It includes various modifications, alternative forms and other variants that a person skilled in the art may envisage within the framework of the present invention and in particular any combination of the different operating modes described above, which can be taken separately or in combination.

Claims (11)

1. Heating unit (4) comprising at least one heating block (5) configured to generate heat, characterized in that the heating unit (4) comprises a sealing element (17) at least partially overmolding the heating block (5) to seal the heating block (5). 2. Heating unit (4) according to claim 1, in which the heating block (5) is positioned between at least two insulating elements (9, 10), the sealing element (17) at least partially overmolding the two insulating elements (9, 10). 3. Heating unit (4) according to any one of the preceding claims, in which each insulating element (9, 10) comprises an external face (9b, 10b), the external faces (9b, 10b) comprising a part (19a , 19b) devoid of sealing element (17). 4. Heating unit (4) according to claim 2 or 3, wherein the at least two insulating elements (9, 10) are configured to form a heating chamber (13) in which is disposed the heating block (5). 5. Heating unit (4) according to claim 4, wherein the sealing element (17) is arranged in the heating chamber (13) formed by the insulating elements (9, 10). 6. Heating unit (4) according to any one of claims 2 to 5, wherein the sealing element (17) is configured to assemble the insulating elements (9, 10) together. . 7. Heating unit (4) according to any one of the preceding claims, in which the sealing element (17) is a curable material chosen from a silicone adhesive or gel, a rubber, a polyurethane adhesive or gel, and an epoxy glue or gel. 8. Heating unit (4) according to any one of the preceding claims, in which the heating block (5) comprises at least one heating means (8) and two electrodes (6, 7) in contact with the heating means (8). 9. Heating device (1) for a motor vehicle comprising at least one heating unit (4) according to any one of the preceding claims and a tube (5), the heating unit (4) being arranged inside. of the tube (5). 10. A method of manufacturing a heating unit (4) according to any one of claims 1 to 8, comprising at least the steps consisting in: place the heating block (5) in a mold (20), and overmold the heating block (5) with the sealing element (17). 11. The method of claim 10, wherein the step for overmolding the heating block (5) is performed by compressing the heating block (5) in the mold (20).