FR3104882A1 - Electric heating device for motor vehicle - Google Patents

Abstract

Electric heating device for a motor vehicle Electric heating device (1) for a motor vehicle, comprising a heat exchange surface (2) capable of being traversed by a fluid and formed by a plurality of heating elements separated by spacers forming radiating elements, characterized in that the heat exchange surface (2) comprises a single flexible PTC-effect heating strip (6) forming the plurality of heating elements, said heating strip (6) forming at least a first linear segment (30) of heating strip ( 6) and a second linear segment (32) of heating strip (6), arranged on either side of a row of dividers (4). Abstract Figure: Figure 1

Description

Electric heating device for a motor vehicle

The present invention relates to the field of ventilation, heating and/or air conditioning installations of a motor vehicle and it relates more particularly to electric heating devices for heating a flow of air passing through a duct of such a facility.

More particularly, the invention relates to an electric heating device provided with at least one electrical resistance heating element with a positive temperature coefficient, known as PTC effect heating elements, which is capable of rapidly producing a supply of heat . Such heating elements make it possible, in particular when the vehicle is started in cold weather, to heat a flow of air passing through an exchange surface of the electric heating device before it enters the passenger compartment of the vehicle. Such an electric heating device is thus capable of transforming electrical energy stored on the vehicle into thermal energy restored in the air flow.

Usually, the PTC effect heating elements used in heating devices are in the form of thin plates made of ceramic material. One or more PTC effect heating elements are interposed between metal blades forming electrodes connected to an electrical supply network of the vehicle, and this set of plates and metal blades forms a heating bar which, placed next to other heating bars between which are arranged radiant elements in the form of fins, participates in forming a heat exchange surface with the air flow passing through the heating device. The calories generated by the electrical supply to the heating bars are transferred to the air flow as it passes through the heating device.

The invention falls within this context and aims to propose an alternative to this configuration of heating devices, in particular by proposing a simplified structure of the heating element which nevertheless presents, in this context of simplification, optimized thermal performance.

The invention therefore relates to an electric heating device for a motor vehicle comprising a heat exchange surface capable of being traversed by a fluid and formed by a plurality of heating elements separated by spacers forming radiant elements, characterized in that the heat exchange surface comprises a single flexible PTC effect heating strip forming the plurality of heating elements, said heating strip forming at least a first linear segment of heating strip and a second linear segment of heating strip, arranged on either side on the other a row of dividers.

The electric heating device can for example be a radiator, making it possible to heat the passenger compartment of a motor vehicle, the exchange surface constituting the part of the heating device within which the heat exchanges take place in order to heat a flow of air passing through the heating device and capable of being sent into the passenger compartment.

According to the invention, the flexible PTC-effect heating strip forms the heat-producing part of the heat exchange surface while the row of spacers forms the heat-diffusing part, heated by the heating strip, allowing the heat exchange with the air flow when the latter passes through the row of spacers. To this end, the strip heater is wrapped around the row of spacers to optimize heat transfer from the strip heater to the row of spacers. The flexible configuration of the heating strip thus makes it possible to obtain an exchange surface composed of a single strip wound around at least one row of spacers. The assembly of the electric heating device is thereby simplified since the number of components of this device is reduced.

According to one characteristic of the invention, the heating device comprises a frame composed of an openwork primary structure and a lattice forming two faces capable of being traversed by the fluid and arranged on either side of the heat exchange surface. heat, the primary structure comprising a support face of the heat exchange surface, the mesh being fixed on the primary structure so as to be arranged overlapping the heat exchange surface.

The perforated primary structure allows the flow of air to pass through the exchange surface arranged against the support face and allows the holding of each row of inserts and the single flexible heating strip arranged around the rows of spacers. In the same way, the trellis has a structure allowing the passage of the air flow through the exchange surface on which it is arranged overlapping. The mesh can then be secured to the primary structure for example by clipping and the single heating strip can be glued or compressed against the row of inserts or the support face of the primary structure by means of the mesh.

According to one characteristic of the invention, the heating strip comprises a curved segment arranged between the first linear segment and the second linear segment, the curved segment being arranged in the vicinity of a longitudinal end of the row of spacers. The curved segment has a radius of curvature which may for example be at least 2 mm. Such a curvature results from the assembly of the electric heating device during which the single heating strip arranged along one face of a row of spacers is wound around the end of this row of spacers to extend in reverse along the opposite side of this row.

According to one characteristic of the invention, the primary structure comprises means for fixing at least one stud to the longitudinal end of the row of inserts, the curved segment being partially wrapped around the stud. By means of fixing at least one pad, the aim is to protect on the one hand a zone of the primary structure in which a pad is secured to the primary structure and remains permanently in the electric heating device, with the segment curved segment wrapped around the stud left permanently, and/or on the other hand a zone for fixing a removable stud, which can be detached from the primary structure after the curved segment has been partially wrapped around this stud during assembly . Such a characteristic makes it possible to reuse the pad for mounting another electric heating device.

According to one characteristic of the invention, the heat exchange surface comprises at least a first row of spacers and a second row of spacers, parallel to each other, one of the linear segments of the heating strip being folded back on itself between the first row of dividers and the second row of dividers.

According to one characteristic of the invention, the linear segment of the heating strip folded back on itself forms a first portion of strip and a second portion of strip, parallel and facing each other, the first portion of strip facing the first row of spacers and the second strip portion facing the second row of spacers, a thermal insulation paste being placed between the first strip portion and the second strip portion of said linear segment of heating tape.

An advantage of such an arrangement of the heating strip is that it makes it possible to increase the heat exchanges between the heating strip and the rows of spacers, the first row of spacers being heated by two portions of strip, distinct from the portions of strip in contact with the second row of dividers. The thermal insulation paste, which can if necessary be replaced by a solid insulating material, of the Teflon, Kapton or even mica type, then makes it possible to prevent two adjacent heating strip portions from being directly in contact with one another. the other, this contact possibly causing overheating of the heating device.

According to one characteristic of the invention, the row of spacers comprises at least a first planar wall and at least a second planar wall which are parallel and at a distance from each other in the direction of stacking of the rows of spacers, each first planar wall being connected to a second planar wall by a junction wall extending substantially perpendicular to the first planar wall and the second planar wall. In this way, the first linear segment of heating strip is in contact with the at least one first flat wall, where appropriate of the plurality of first flat walls arranged in a coplanar fashion, and the second linear segment of heating strip is in contact with the at least one second planar surface, where applicable of the plurality of second planar walls arranged in a coplanar fashion.

It is understood that the row of dividers thus has a crenellated shape. Such a configuration of the row of spacers reduces the height of said row of spacers and therefore allows the use of more linear meters of heating strip within the heating device. This allows the dimensions of the heating device to be reduced, offering space savings in the motor vehicle while maintaining acceptable thermal performance.

According to a characteristic of the invention, the heating strip comprises an end for connection to an electrical network. The electrical network may for example be that of the motor vehicle in which the heating device is arranged.

According to one characteristic of the invention, the PTC-effect heating strip comprises at least one metallic conductor embedded in a PTC-effect polymer matrix.

The heating strip may in particular comprise two metal conductors, extending side by side, embedded in a matrix of PTC-effect polymer. These conductors can be made of a copper-nickel alloy.

The invention also relates to a heat exchanger composed of at least one sheet comprising the electric heating device as mentioned above.

According to a first configuration, the heat exchanger can comprise a single sheet and operate only in radiator mode, a control module being configured to activate or not the electrical supply of the heating strip according to the hot air needs of the vehicle.

According to a second configuration, the heat exchanger can comprise two sheets successively traversed by a flow of air, a first sheet comprising the electric heating device according to the preceding characteristics and a second sheet comprising a series of tubes arranged between connection blocks and inside which circulates a refrigerant capable of exchanging cold temperatures with the air flow.

The second sheet can thus be an evaporator of an air conditioning loop, the heat exchanger being controlled to operate according to the conditions as a radiator or evaporator. More specifically, a control module is then configured to, on the one hand, allow or not allow the passage of refrigerant fluid in the tubes of the second layer and, on the other hand, allow or not allow the power supply, depending on the desired mode of operation. .

The invention also relates to a method for mounting an electric heating device as previously described, comprising the performance of at least a first step during which the first row of inserts and the heating strip are placed on the face support of the primary structure, and the performance of at least a second step during which the heating strip is folded so as to place it on either side of the first row of inserts with a first curved segment of the heating strip positioned at a first longitudinal end of the first row of dividers.

According to one characteristic of the invention, the assembly method comprises at least one sequence of steps following said second step, during which initially a new row of spacers is placed on the support face of the structure primary so as to enclose the heating strip between this new row of spacers and the last row of spacers to have been arranged in the frame, and in a second step the heating strip is wound around one end of the new row of spacers, so that two linear segments of the heating strip are arranged on either side of the new row of spacers and a new curved segment is disposed at one longitudinal end of the new row of spacers.

According to a characteristic of the assembly method of the invention, the curved segments are alternately arranged at one and the other longitudinal end of the electric heating device.

According to a characteristic of the assembly method, during the first step the first row of inserts is positioned against a stud of the primary structure and in which during the second step the first curved segment of the heating strip is wound around said plot.

By way of example, a first stud can be positioned on the primary structure so that it faces the first longitudinal end of a first row of inserts while the second stud is placed on the primary structure of such that it faces the second longitudinal end of the second row of inserts.

According to a characteristic of the mounting method, each stud can be removed from the primary structure of the frame once the heating strip is wound around these studs. The studs are thus removable in the sense that they can be detached from the primary structure of the frame. In this way, the pads can be reused in an assembly process for a subsequent heating device.

Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several examples of embodiment given by way of indication and not limitation with reference to the appended schematic drawings on the other. part, on which:

is a general perspective view of an electric heating device according to a first embodiment of the invention, comprising a heat exchange surface with a plurality of rows of spacers and a heating strip arranged so as to surround these rows dividers;

is a schematic view of a PTC-effect polymer-based heater strip;

is an exploded perspective view of a frame of the electric heater according to a second embodiment of the invention;

is a general perspective view of the electric heating device according to the second embodiment, specific in that it comprises the frame of FIG. 3;

is a general perspective view of an electric heating device according to a third embodiment of the invention;

is a partial schematic representation of the electric heater of Figure 5;

is a general perspective view of an electric heating device according to a fourth embodiment of the invention;

is a general perspective view of the heating strip according to the invention before its assembly within the electric heating device;

is a perspective view of a method of mounting the electric heating device according to a first embodiment of the invention;

is a perspective view of the subsequent assembly process of the electric heater of Figure 8;

is a perspective view of a method of mounting the electric heating device according to a second embodiment of the invention;

is a perspective view of the rest of the assembly process of the electrical heating device of Figure 10.

The features, variants and different embodiments of the invention may be associated with each other, in various combinations, insofar as they are not incompatible or exclusive of each other. It is possible in particular to imagine variants of the invention comprising only a selection of characteristics described below in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from to the state of the prior art.

FIG. 1 illustrates an electric heating device 1 according to a first embodiment intended to be installed in a ventilation, heating and/or air conditioning installation of a vehicle, for example an automobile. The electric heating device 1 is configured to produce heat under the effect of an electric power supply and to be traversed by a fluid, for example air, at the level of an exchange surface 2 configured to allow the exchanges of calories thus generated between the electric heating device 1 and the fluid passing through it.

The exchange surface 2 is composed of at least one row of spacers 4 and a single flexible heating strip 6 configured to be arranged on either side of this row of spacers.

In the example illustrated in Figure 1, the exchange surface 2 comprises a series of seven rows of inserts 4, stacked on top of each other in a direction here vertical with reference to the vertical axis V of the trihedron L, V,T, being parallel to each other. At least one of the rows of inserts 4 is formed by a sheet of corrugated profile, which extends between a first longitudinal end 8 and a second longitudinal end 10, opposite to the first longitudinal end 8 in a longitudinal direction L of the heating device electric 1. The row of dividers 4 thus extends over a first distance D1, measured along a straight line parallel to the longitudinal direction L of the heating device 1, between the first longitudinal end 8 and the second longitudinal end 10.

More specifically, the wavy shape of the row of spacers 4 generates first vertical vertices 12 and second vertical vertices 14, opposite each other in the vertical direction V of the electric heating device 1. A first side is then defined 16 of the row of dividers 4 corresponding to all of the first vertical vertices 12 of the same row of dividers 4 and a second side 18 corresponding to the set of second vertical vertices 14 of the same row of dividers 4.

The row of inserts 4 forms a radiant element, or heat dissipation means, of the heating device 1, that is to say the means making it possible to increase the exchange surface between the fluid capable of recovering the calories transferred by the heating element and said row of spacers 4 associated. It is understood that the characteristics of the row of spacers 4 mentioned above apply to each of the rows of spacers 4 of the electric heating device 1.

The heat exchange surface 2 also comprises the flexible heating strip 6, visible in FIG. 2 and forming a heating element with a PTC effect, that is to say with a positive temperature coefficient effect. According to the invention, and as will be described in more detail below, the flexible heating strip is configured, and in particular folded at each longitudinal end of a row of spacers, to form a single piece of a plurality heating segments respectively arranged between two rows of inserts.

The heating strip 6, as it can be seen in detail in FIG. 2, is composed of at least one metallic conductor 20, here in the example illustrated, of two parallel metallic conductors 20, each metallic conductor 20 being embedded in a semi-crystalline polymer matrix 22 doped with conductive particles, preferably carbon black, so as to constitute a positive temperature coefficient (PTC) thermistor. The metal conductors 20 are for example copper-nickel wires, forming the heating part of the flexible heating strip 6 with PTC effect and whose end emerging from the heating strip 6 is connected to the internal electrical network. The end of the metal conductors emerging from the heating strip is then defined as an electrical connection end 28.

The assembly is also provided with at least one layer of dielectric material 24 surrounding the polymer matrix 22 and which aims to electrically insulate the assembly formed by the metal conductors 20 and the polymer matrix 22 while allowing heat transfer released by the operation of this set.

Furthermore, the PTC-effect heating strip 6 is provided with a protection element which surrounds the layer of dielectric material 24. This protection element may for example be directly formed by the casing of the heating strip or else be produced by a specific protective sheath 26.

In the example illustrated, the layer of insulating material, or else layer of dielectric material 24, consists of a specific insulation sheath arranged around the polymer matrix 22 and forming part of the heating strip 6.

It should be noted that in Figure 2, the layer of dielectric material 24, also forming the protective sheath 26, has been illustrated cut to reveal part of the polymer matrix 22 and the end of the metal conductors 20, it being noted that this layer of dielectric material 24 extends over the length of the heating strip 6 so as to completely cover the polymer matrix 22.

The heating strip 6 with PTC effect has a self-regulating effect particularly suited to the implementation of an electric heating function in a heating device 1 in accordance with the invention. When the electric heating device 1, and therefore the heating strip 6 present in this device, is subjected to a low temperature, the polymer matrix 22 shrinks and the conductive carbon particles which it contains are close to each other and favor the current flow having the effect of decreasing the resistance and increasing the output power. This process is reversed as the temperature increases. The polymer matrix 22 stretches due to molecular expansion and the distance between the carbon particles increases. The number of electrical paths decreases, the resistance increases and the power dissipated by the heating strip 6 decreases. In this way, the heating strip 6 is self-regulating in that it is capable of increasing the output power when the air passing through the electric heating device 1 is cold and in that it is capable of decreasing the power outlet if the passing air is warm enough and does not require significant heat exchange.

The heating strip 6 according to the invention is flexible, that is to say that it has the property of being bent without this deformation causing the heating strip 6 to break or lowering its thermal performance. The heating strip 6 is then folded in such a way that it is wound around at least one of the rows of inserts 4 making up the exchange surface 2. In the example illustrated in FIG. 1, the heating strip 6 is wound successively around each of the seven rows of inserts 4 making up the exchange surface 2 of the heating device 1.

In this context according to the invention of a single flexible heating strip folded to be wound around a row of spacers, the heating strip 6 comprises at least two consecutive linear segments, and for example a first linear segment 30 and a second linear segment 32, arranged on either side of a first row of spacers 4a and respectively in contact with the first side 16a and the second side 18a of the first row of spacers 4a. It is thus understood that the first linear segment 30 and the second linear segment 32 of the heating strip 6 are in contact respectively with all of the first vertical vertices 12 and the second vertical vertices 14 of the first row of inserts 4a.

The heating strip 6 also comprises at least one curved segment and for example a first curved segment 34 arranged in the continuity of the first linear segment 30 and placed between this first linear segment 30 and the second linear segment 32, so that it is disposed overlapping one end, here the first longitudinal end 8, of the first row of dividers 4a.

As illustrated in Figure 1, the first linear segment 30 and the second linear segment 32 of the heating strip 6 both extend over a second distance D2, measured along a straight line parallel to the longitudinal direction L of the heating device 1, the second distance D2 being strictly greater than the first distance D1 of the first row of dividers 4a.

The heat exchange surface consists of a stack of rows of spacers alternating with linear segments forming part of the single flexible heating strip. Each row of inserts is covered in the direction, here vertical, of this stack by two linear segments forming part of the single flexible heating strip.

Returning to Figure 1, a second row of spacers 4b, adjacent to the first row of spacers 4a, is then in contact with the second linear segment 32 of the heating strip 6, at its first side 16b. In other words, the second linear segment 32 of the heating strip 6 is sandwiched between the first row of spacers 4a and the second row of spacers 4b. In this way, the second linear segment 32 is in contact both with all of the second vertical vertices 14 of the first row of spacers 4a and with all of the first vertical vertices of the second row of spacers 4b.

A third linear segment 36 of heating strip 6, obtained by folding the second linear segment around the second longitudinal end 10 of the rows of inserts, then extends opposite the second linear segment 32 with respect to the second row of spacers 4b, that is to say along the second side of the second row of spacers 4b. The third linear segment 36 of heating strip 6 extends against all of the second vertical vertices 14 of the second row of inserts 4b according to the same characteristics mentioned previously.

The heating strip 6 then comprises a second curved segment 38 between the second linear segment 32 and the third linear segment 36 of the heating strip 6, such that it is disposed at the level of the second longitudinal end 10 of the second row of spacers 4b.

The foregoing can be repeated from one vertical end to the other of the heat exchange surface, so that it is then understood that the characteristics of the arrangement of the heating strip 6 against the first row of spacers 4a and the second row of inserts 4b apply to the arrangement of the heating strip against each of the rows of inserts 4 which make up the exchange surface 2, the arrangement of the linear segments 29 and of the successive curved segments 33 of the heating strip 6 repeating itself from one vertical end to the other, the curved segments being alternately arranged near a first longitudinal end then a second longitudinal end.

As specified previously, the metal conductors 20 of the heating strip form a projection at a free end of the flexible heating strip, for the electrical connection of this heating strip. It should be noted that this simplifies the distribution of current, by providing only one connection point. Despite this single connection point, the device is configured in such a way that the current flows in all of the heating segments 29 and that each stage of the stack of rows of inserts 4 is capable of exchanging calories with the air passing through the device.

A second embodiment of the electric heating device 1 will now be described with particular reference to Figures 3 and 4, with Figure 3 showing an exploded view of a frame 40 of the electric heating device 1 and Figure 4 showing the heating device 1 integrated in its frame 40. It should then be considered that only the distinct characteristics of the first embodiment will be detailed in the remainder of the description. For identical characteristics, reference should be made to the description given above with reference to Figures 1 and 2.

The frame 40 according to the invention comprises a primary structure 42 and a lattice 44. The primary structure 42 as it is visible in FIG. 3 comprises at least one face 46 supporting the exchange surface 2 of the heating device 1 and at least one stud 48, and in the illustrated example seven studs 48. As will be detailed below, and in particular during the description of an example of a method for mounting the device, a frame could be devoid of studs .

The support face 46 is presented as a perforated face, so that the fluid can cross the exchange surface 2 right through, and the periphery of which is delimited by a frame 50, here taking the form of a quadrilateral. The frame 50 then comprises a first edge 52a and a third edge 52c parallel to each other and a second edge 52b and a fourth edge 52d, parallel to each other and in such a way that they connect the first edge 52a and the third edge 52c together.

At least one stiffening rib 54 is arranged across the perforated face and therefore inside the frame 50. In the example illustrated, the primary structure comprises six stiffening ribs 54. More specifically, the ribs stiffening 54 extend inside the frame 50 such that they are in contact with the second edge 52b and the fourth edge 52d of the frame 50. In the example illustrated, the stiffening ribs 54 are arranged in such a way that they form an internal “V” reinforcement in the frame 50. The stiffening ribs 54 make it possible both to reinforce the primary structure and to ensure the maintenance in position of the surface of exchange 2 on the support face 46, the latter being perforated as mentioned above.

The studs 48 of the primary structure 42 extend projecting from the support face 46, perpendicular to the main extension plane of this support face.

The studs 48 are arranged on the frame 50 and more precisely on two edges facing each other, here the second edge 52b and the fourth edge 52d of said frame 50. In the example illustrated, each stud 48 is disposed at one end of the stiffening ribs. In this way, and as shown, each of the studs 48 arranged on one of the edges of the frame, here the second edge 52b, is offset with respect to the studs 48 arranged on the opposite edge, here the fourth edge 52d , frame 50. This results in an arrangement of studs in two series arranged transversely at a distance from each other, and with a vertical offset from one series of studs to the other. According to the example illustrated, four studs 48 are arranged on the fourth edge 52d of the frame 50 and three studs 48 are arranged on the second edge 52b of the frame 50.

Such a configuration of the studs, as can be seen in FIG. 4, makes it possible to ensure that the studs 48 are arranged alternately opposite the first longitudinal ends 8 and the second longitudinal ends 10 of each of the rows of inserts 4 of the surface exchange 2. Such a characteristic then makes it possible to use each of the studs to unroll the single flexible heating strip 6 continuously between rows of inserts and around the studs 48. More precisely, at least one of the curved segments 33 of the heating strip 6 is partially wound around one of the studs 48 of the primary structure 42. In the example shown, each curved segment 33 of the heating strip is wound around one of the studs 48 of the primary structure 42 It is then understood that the studs 48 have the function of increasing the maintenance of the heating strip 6 within the heating device 1 and of facilitating the winding of said heating strip 6 around the rows of inserts 4 by exercising a function of 'support.

The primary structure 42 also includes at least one fixing shank 56, here six in number in the example shown. The fixing barrels 56 are hollow and are arranged in series on the two opposite edges of the frame 50 not provided with studs 48, namely here a first series 58 of three barrels arranged on the first edge 52a and a second series 60 of three barrels arranged on the third edge 52c of the frame 50. Each of the fixing barrels 56 of the same series is spaced by a third non-zero distance D3 from an adjacent fixing barrel 56.

The frame 40 of the heating device 1 also includes the trellis 44 visible in Figure 3, configured to be secured to the primary structure 42 so as to overlap the exchange surface 2 as can be seen in Figure 4. The trellis 44 then has a perforated surface in order to allow the passage of the fluid through the exchange surface 2 of the heating device 1.

The trellis 44 consists of an intersection of bars 61 whose ends 62 are respectively equipped with a pin 68 forming a projection substantially perpendicular to the plane in which the bars 61 extend. As illustrated, these pins are distributed three by three in a first series disposed at a first vertical end 64 of the trellis 44 and in a second series disposed at a second vertical end 66 of the trellis 44, opposite the first vertical end 58 of the trellis 44 in the vertical direction V of the heating device 1 represented arbitrarily in Figure 3.

Each pawn is spaced from an adjacent pawn of the same series by a fourth non-zero distance D4.

The fourth distance D4 is substantially equal to the third distance D3 so that each of the pins 68 of the trellis 44 can cooperate by interlocking with one of the hollow fixing shafts 56 of the primary structure 42 of the frame 40.

Thus, as can be seen in FIG. 4, the cooperation between the primary structure 42 and the trellis 44 makes it possible to freeze the position of the heating strip 6 and of the rows of inserts 4 against the support face 46 of the frame 40. winding of the heating strip 6 around the pads 48, and the tightening of the rows of spacers between two linear segments of this heating strip which results therefrom, mainly prevents the movements of the said heating strip 6 and of the rows of spacers 4 according to the longitudinal L and vertical V directions of the heating device 1, that is to say the directions parallel to the main extension plane of the frame 40 and of the electric heating device, while the cooperation of the pins 68 fitted into the fixing barrels 56 mainly prevents the movements of the heating strip 6 and of the rows of spacers 4 in the transverse direction T of the electric heating device 1, perpendicular to the vertical V and longitudinal L directions of the electric heating device 1.

A third embodiment of the heating device 1 will now be described with reference to FIGS. 5 and 5b. As for the second embodiment, only the distinct characteristics of the first and second embodiment will be detailed in the following description. For identical characteristics, reference should be made to the description made with reference to Figures 1 to 4.

In the illustrated example of this third embodiment of the invention, only the studs 48 of the frame 40 having a configuration distinct from the other embodiments have been represented. It should then be considered that the other constituent elements of the frame 40 are identical to the previous embodiments and for example the frame and its shafts as well as the trellis and its pins. In this third embodiment, the frame differs from the above in that all of the studs 48 are positioned on the same edge of the frame (not shown), here the second edge.

In this embodiment, and as is more particularly visible in the schematic representation of FIG. 5b, at least one linear segment 29 of the heating strip 6, for example the second linear segment 32, is folded back on itself by such that it forms a first strip portion 70 and a second strip portion 72, parallel and facing each other. More precisely, the second linear segment 32 arranged between the first row of spacers 4a and the second row of spacers 4b is folded over on itself so that the first portion of band 70 is facing the first row spacers 4a and the second portion of strip 72 is opposite the second row of spacers 4b.

To this end, the heating strip 6 comprises at least one portion fold 74 between the first strip portion 70 and the second strip portion 72, said portion fold 74 being provided near the first longitudinal end 8 of the first and second row of inserts 4a, 4b, that is to say here near the longitudinal end arranged opposite the studs 48.

Opposite the portion fold 74, at least one of the curved segments 33 of the heating strip 6 is arranged partially around one of the studs 48 disposed at the second longitudinal end 10 of the first row of spacers 4a. In the example illustrated in FIG. 5, all of the curved segments 33 of the heating strip 6 are wound around the studs 48 of the primary structure and the structural characteristics of the linear segment 29 mentioned in this third embodiment, with two strips resting one on the other, apply to all of the linear segments 29 making up the exchange surface 2. A thermal insulation paste 73, particularly visible in the schematic detail figure 5b, can be placed between the first strip portion 70 and the second strip portion 72 in order to thermally insulate said first strip portion 70 and second strip portion 72 from each other. In this way, direct contact between the first strip portion 70 and the second strip portion 72 is avoided, thus limiting the overheating of the heating device 1.

An advantage of this third embodiment is that it increases the thermal performance of the heating device 1, due to the increase in linear meter of heating strip 6 in contact with the rows of inserts 4 of the heat exchange surface 2 , and this with a relatively small increase in size.

A fourth embodiment will now be described with reference to FIG. 6, where only the exchange surface 2 is illustrated, it being understood that it should be considered that the exchange surface 2 of the heating device 1 of this fourth embodiment can be integrated into a framework in accordance with what has been previously described.

In this fourth embodiment, at least one of the rows of spacers 4, for example the first row of spacers 4a has a crenellated shape. More specifically, the first row of inserts 4a comprises at least a first flat wall 76 participating in forming the first side 16a of the row of inserts 4a and a second flat wall 78 participating in forming the second side 16a of the row spacers 4a, these two flat walls being parallel to each other and offset from each other along the longitudinal direction L of the heating device 1. At least one junction wall 80 then connects the first flat wall 76 and the second planar wall 78 from each of their longitudinal ends, extending perpendicular to each of the planar walls 76, 78.

More particularly, the first row of dividers 4a is composed of a succession of first flat walls 76 and second flat walls 78 arranged alternately and connected together by junction walls 80, from its first longitudinal end 8 to its second longitudinal end 10. As mentioned above, the set of first flat walls 76 of the first row of dividers 4a then forms the first side 16a and the set of second flat walls 78 of the first row of dividers 4a forms its second side 18a.

In this example, the first linear segment 30 of heating strip 6 is then placed against the first flat walls 76 and the second linear segment 32 of the heating strip 6 is placed against the second flat walls 78.

as illustrated, the characteristics of the first row of inserts 4a as they have just been explained can apply to all of the rows of inserts 4 of the exchange surface 2 of this fourth mode of achievement.

Such a configuration of the rows of spacers 4 makes it possible to increase the exchange surface by increasing the contact zone between the heating strip 6 and the rows of spacers 4, through the flat walls 76, 78. Also, the configuration of the rows of inserts 4 allows them to reduce their height, measured along the vertical direction V of the heating device 1, and therefore allows the use of more than one linear meter of heating strip 6 within the heating device 1, for example by folding on themselves the linear segments in two bands as mentioned in the previous embodiment. It is thus possible to combine compliance with the size constraints in the motor vehicle and the desire not to penalize or on the contrary to improve the thermal performance of the electric heating device 1.

A method of mounting the heating device 1 according to a first exemplary embodiment will now be described in relation to FIGS. 7, 8 and 9. In this first exemplary embodiment of the assembly, the primary structure 42 has no studs 48.

The heating strip 6 before its installation within the electrical heating device 1 is presented as a straight strip, as visible in FIG. 7, with electrodes protruding from one of the ends forming a connection end 28, the straight strip having a flexibility allowing this strip to deform in order to be rolled up on either side of at least one row of dividers 4 of the exchange surface 2.

At a first step of the process, illustrated in FIG. 8, the first row of dividers 4a is arranged on the support face 46 of the primary structure 42 of the frame 40 such that the first longitudinal end 8 faces the fourth edge 52d of the frame 50 and that the second longitudinal end 10 faces the second edge 52b of the frame 50, the first row of inserts 4a being placed in abutment against the stiffening ribs 54 of the primary structure 42.

In this step of the method, the heating strip 6 is also placed against the first row of spacers 4a, and more particularly against the first side 16a of the first row of spacers 4a. More particularly, the heating strip is positioned between the barrels 56 forming a projection from the first edge 52a of the frame 50 and the first side 16a of the first row of inserts 4a, so as to be held in position by the pressure exerted by the row of dividers. In this way, it is ensured that the first linear segment 30 of the heating strip is facing the first row of spacers.

In a second step of the process, the heating strip 6 is then bent in order to place the second linear segment 32 against the second side 18a of the first row of spacers 4a. The folding of the heating strip 6 then forms the first curved segment 34, visible in FIG. 9, of the heating strip 6, said first curved segment 34 being arranged opposite the first longitudinal end 8 of the first row of spacers 4a .

At a third step, illustrated in particular by FIG. 9, the second row of spacers 4b is arranged on the support face 46 of the primary structure 42 so that it is parallel to the first row of spacers 4a and encloses the second linear segment 32 of the heating strip between it and the first row of spacers 4a. More precisely, the second row of inserts 4b is placed in such a way that its first side 16b is in contact with the second linear segment 32 of the heating strip 6. Subsequently, the heating strip 6 is folded in such a way that the third linear segment 36 is in contact with the second side 18b of the second row of dividers 4b. The folding of the heating strip 6 then forms the second curved segment 38, arranged opposite the second longitudinal end 10 of the second row of spacers 4b, between the second linear segment 32 and the third linear segment 36.

These steps of positioning the rows of inserts 4 and winding of the heating strip 6 are carried out, with the linear segments 29 and the curved segments 33, for all the rows of inserts 4 of the heating device 1.

Once all the rows of inserts 4 of the heating device 1 have been installed with the single flexible heating strip 6 folded in several successive zones so that linear segments of this single heating strip are arranged on either side of each row of dividers 4, the trellis 44 (not shown here) of the frame 40 is arranged to overlap the exchange surface 2 so that the pins it carries fit into the fixing barrels 56 of the primary structure 42.

A second exemplary embodiment of the assembly method of the electric heating device 1 will now be described in relation to FIGS. 10 and 11. Only the structural and functional characteristics different from the first exemplary embodiment of the assembly method will be detailed in the remainder of the description. For the common characteristics, reference should be made to the description of the process made with reference to Figures 7 to 9.

In this second exemplary embodiment, the primary structure 42 comprises the studs 48 mentioned previously. Thus, in the first step, the first row of dividers 4a is placed in such a way that the first longitudinal end 8 faces a first stud 48a placed on the fourth side 52d of the frame 50 of the primary structure 42. It is understood that at this stage, the presence of the stud makes it possible to ensure the longitudinal position of the row of inserts, by abutment of the latter against the stud.

During assembly according to this second embodiment, the first linear segment 30 and the second linear segment 32 of the heating strip 6 are placed on either side of the first row of inserts 4a according to the same characteristics as the first example. carrying out the method, with the difference that the heating strip 6 is bent in such a way that the first curved segment 34 is partially around the first pad 48a of the primary structure 42.

In the third step of the method, the second row of spacers 4b is placed against the support face 46 so that it is in contact with the second linear segment 32 of the heating strip 6, according to the same characteristics as the first example. carrying out the method, and also in such a way that its second longitudinal end 10 faces a second stud 48b placed on the second edge 52b of the frame 50. The heating strip 6 is then folded in such a way that the second curved segment 38 partially surrounds the second stud 48b of the primary structure 42.

These steps of positioning the rows of spacers 4 and winding of the heating strip 6 are carried out, with the linear segments 29 and the curved segments 33 around the pads 48, for all the rows of spacers 4 of the heating device 1 according to the same characteristics as for the installation of the first row of spacers 4a and the second row of spacers 4b. Subsequently, the trellis 44 is arranged to overlap the exchange surface 2 according to the preceding characteristics.

Alternatively, at least one stud 48 can be detached from the primary structure 42 once the heating device 1 has been mounted. In this way, it allows the reuse of said pad 48 during subsequent assembly of a heating device. It may then be necessary to add plugs instead of studs 48 in order to prevent the heating device from presenting passages for the fluid through the heat exchange surface in which the fluid is not at the spacer contact.

Of course, the invention is not limited to the examples which have just been described and many adjustments can be made to these examples without departing from the scope of the invention.

The invention, as it has just been described, achieves the goal that it had set itself, and makes it possible to propose a heating device that is more ergonomic and has improved thermal capacities. Variants not described here could be implemented without departing from the context of the invention, provided that, in accordance with the invention, they comprise at least one heating strip in accordance with the aspect of the invention.

Claims (10)

Electric heating device (1) for a motor vehicle, comprising a heat exchange surface (2) capable of being traversed by a fluid and formed by a plurality of heating elements separated by spacers forming radiating elements, characterized in that the heat exchange surface (2) comprises a single flexible PTC-effect heating strip (6) forming the plurality of heating elements, said heating strip (6) forming at least a first linear segment (30) of heating strip ( 6) and a second linear segment (32) of heating strip (6), arranged on either side of a row of dividers (4). Heating device (1) according to the preceding claim, in which the heating strip (6) comprises a curved segment (33) disposed between the first linear segment (30) and the second linear segment (32), the curved segment (33) being arranged in the vicinity of a longitudinal end (8, 10) of the row of inserts (4). Heating device (1) according to one of the preceding claims, comprising a frame (40) composed of a perforated primary structure (42) and of a trellis (44) forming two faces capable of being traversed by the fluid and arranged either side of the heat exchange surface, the primary structure (42) comprising a support face (46) of the heat exchange surface (2), the lattice (44) being fixed to the structure primary (42) so as to be arranged overlapping the heat exchange surface (2). Heating device (1) according to the preceding claim, in which the primary structure (42) comprises means for fixing at least one stud (48) to the longitudinal end (8, 10) of the row of inserts (4 ), the curved segment (33) being partially wrapped around the pad (48). Heating device (1) according to any one of the preceding claims, in which the heat exchange surface (2) comprises at least a first row of spacers (4a) and a second row of spacers (4b), parallel one from the other, one of the linear segments (30, 32) of the heating strip (6) being folded back on itself between the first row of spacers (4a) and the second row of spacers (4b) . Heating device (1) according to the preceding claim, in which the linear segment (30, 32) of the heating strip (6) folded on itself forms a first portion of strip (70) and a second portion of strip (72) , parallel and facing each other, the first strip portion (70) facing the first row of inserts (4a) and the second strip portion (72) facing the second row spacers (4b), a thermal insulation paste (73) being placed between the first strip portion (70) and the second strip portion (72) of said linear segment (30, 32) of heating strip (6) . Heating device (1) according to any one of the preceding claims, in which the PTC-effect heating strip (6) comprises at least one metallic conductor (20) embedded in a PTC-effect polymer matrix (22). Heat exchanger composed of at least one layer comprising the electric heating device (1) according to one of the preceding claims. Method of mounting an electric heating device (1) according to one of Claims 1 to 7, comprising the performance of at least a first step during which the first row of inserts (4a) and the strip (6) on the support face (46) of the primary structure (42), and the performance of at least a second step during which the heating strip (6) is folded so as to place it on either side other side of the first row of spacers (4a) with a first curved segment (34) of the heating strip (6) positioned at a first longitudinal end (8) of the first row of spacers (4a). Method of mounting a heating device (1) according to the preceding claim, in which during the first step the first row of spacers (4a) is positioned against a stud (48) of the primary structure (42) and in which during the second step the first curved segment (34) of the heating strip (6) is wound around said stud (48).