Heating device, especially for vehicles

Abstract

Heating device, in particular for vehicle The invention relates to a heating device (10) comprising a circulation chamber extending between a first plane (P1) and a second plane (P2), parallel to the first plane (P1), and: A hood (11); A casing (12) extending, along a height of the circulation chamber perpendicular to the first plane, from the second plane to the hood (11), the casing comprising a channel (13) in which a heat transfer fluid is intended to circulate, the channel (13) extending along a length (14) of the channel between an inlet (15) and an outlet (16) and forming a sinuous path; A plurality of electric heating elements (21, 22) of complementary shape to the channel (13), arranged in the channel, extending side by side within the same channel along the sinuous path, and arranged parallel to each other along a width (17) of the channel perpendicular to the height of the circulation chamber. (Figure 1)

Description

Title of the invention: Heating device, particularly for vehicles

[0001] The present invention relates to the field of electric heating devices, and in particular to electric heating devices for vehicles. Typically, a vehicle is equipped with one or more electric heating devices intended to heat a heat transfer fluid, which may, for example, be glycol, a mixture of water and glycol.

[0002] These heating devices are used in particular in vehicle passenger compartment heating systems to heat the heat transfer fluid which then heats the air intended for the passenger compartment as well as to heat a heat transfer fluid which heats the vehicle's electric battery.

[0003] The operation of these electric heating devices relies on the circulation of the heat transfer fluid within them. A key component of the electric heating device is its heating element, which is electrical in nature and typically uses a resistive material. When supplied with an electric current, the resistive material heats the rest of the heating element, which, in turn, transfers its heat to the heat transfer fluid in contact with the heating element. This process thus allows the heat transfer fluid to warm up as it passes through the heating device and is in direct contact with the heating element.

[0004] More specifically, a heating element comprises a resistive wire arranged in a tubular outer casing. Magnesia (MgO) powder, an excellent thermal conductor and electrical insulator, is compacted and arranged within the heating element. In addition to providing thermal conductivity and electrical insulation between the resistive wire and the casing, the magnesia powder helps to keep the resistive wire centered within the tubular casing. In the following, we will refer to this assembly as an electric heating element.

[0005] Such an electric heating element may have curved shapes. However, the radii of curvature must be sufficiently large, otherwise the magnesium powder will become loose, leading to poor electrical insulation between the resistive wire and the casing.

[0006] In existing solutions, in order to deliver a given thermal power, several heating elements, for example two heating elements, are integrated into the electric heating device. These heating elements are usually stacked one above the other in the height of the electric heating device. This arrangement has the advantage of ease of The heating elements are mounted in the heating device. This arrangement allows for the integration of two heating elements within a given surface area of ​​the heating device, while respecting the radii of curvature. Consequently, to meet a predetermined thermal power requirement, the electric heating device has a certain height that is difficult to reduce due to the overlapping of the electric heating elements.

[0007] Nevertheless, there is a need for increasingly compact heating devices with high thermal power density. In particular, it is desirable to have electric heating devices with a generally flat shape, i.e., low profile, to meet the compactness requirements when installed in vehicles.

[0008] The objective of the invention described in this document is therefore to overcome the drawbacks of the prior art by providing a heating device with a low profile, capable of delivering high thermal power. Furthermore, such a heating device also facilitates temperature control.

[0009] The present invention thus has as its main object a heating device intended to heat a heat transfer fluid, the heating device comprising a circulation chamber extending between a first plane and a second plane, parallel to the first plane, characterized in that it comprises a hood, a casing extending, along a height of the circulation chamber perpendicular to the first plane, from the second plane to the hood, the casing having at least one channel in which a heat transfer fluid is intended to circulate, the channel extending along a length of the channel between an inlet and an outlet and forming a sinuous path.The heating device also includes a plurality of electric heating elements complementary in shape to the channel, the plurality of electric heating elements being arranged in the channel and intended to be in contact with the heat transfer fluid, the plurality of electric heating elements extending side by side within the same channel along the sinuous path, said plurality of electric heating elements being arranged parallel to each other along a width of the channel perpendicular to the height of the circulation chamber.

[0010] Thanks to these characteristics, the heating device can combine a small footprint with high thermal output. Indeed, several electric heating elements are placed in the channel to meet the heating requirements of the heat transfer fluid. The placement of several electric heating elements side-by-side in the channel limits the height of the heating device.

[0011] According to one embodiment, the winding path of the channel includes at least one half-turn between the inlet and the outlet.

[0012] According to an optional feature of the invention, each of the plurality of electric heating elements has an alternating succession of straight portions and U-shaped portions. Thus, satisfactory heating element lengths are obtained for a given volume of the heating device.

[0013] According to an optional feature of the invention, the straight portions are of identical length.

[0014] According to an optional feature of the invention, two successive U-shaped portions have a different radius of curvature. Thus, two side-by-side heating elements can be nested one inside the other.

[0015] According to an optional feature of the invention, the straight portions are parallel. Advantageously, the straight portions of the plurality of electric heating elements are all parallel to each other. Such a configuration offers better use of the available space in the heating device.

[0016] The electric heating elements extend along the same sinuous path within the channel, spaced apart, parallel to each other, and parallel to the second plane. This allows for a greater length of electric heating elements than the external length of the heating device, ensuring the correct level of thermal energy transfer from the electric heating elements to the heat transfer fluid, in order to deliver the desired thermal output.

[0017] According to an optional feature of the invention, the heating device further comprises at least one heat-sensitive element, for example a fuse, disposed on the housing, a lower surface of at least one fuse being located in the second plane, in particular in line with the plurality of electric heating elements.

[0018] According to an optional feature of the invention, the lower surface of at least one heat-sensitive element is located in a plane passing through the heat-sensitive element and coinciding with the section of the channel, the heat-sensitive element being arranged equidistant from the heating elements, or median with respect to the channel.

[0019] The thermosensitive element can also be a temperature sensor.

[0020] Thus arranged, the heat-sensitive element detects a casing temperature that exceeds a threshold temperature, indicating a malfunction in the heating device. Indeed, if the casing temperature is too high, this may indicate a problem in the circulation of the heat transfer fluid or in the heating element control system. In such a case, the fuse opens the electrical circuit to interrupt the heating for safety reasons. Thanks to its planar positioning within the heating element channel and the fuse's equidistant placement on the casing, particularly between the heating elements, the fuse is in measure to capture the energy density from all the heating elements. In other words, the sum of all the thermal paths to be traveled is shorter in the configuration of the invention than in that of the prior art where the heating elements are arranged one above the other in the channel.

[0021] According to an optional feature of the invention, each heating element has an electrical connection terminal at each end. In one embodiment, the connection terminals are arranged on the same side of the chamber and the number of half-turns is odd.

[0022] Arranging the connection terminals on the same side of the chamber allows for electrical connections to be made on the same side of the housing. This facilitates the electrical connection of auxiliary components.

[0023] According to an optional feature of the invention, the plurality of electric heating elements are of different lengths.

[0024] In another embodiment of the invention, the connection terminals are arranged on two opposite sides of the circulation chamber and the number of half-turns is even.

[0025] According to an optional feature of the invention, the plurality of electric heating elements are of identical length and / or the plurality of electric heating elements are identical.

[0026] The arrangement of the connection terminals on two opposite sides of the chamber allows for electric heating elements of identical length. The electric heating elements are identical to each other. This results in easier supply of electric heating elements since it is not necessary to provide different shapes and / or lengths of heating elements.

[0027] According to an optional feature of the invention, the heating device includes a device for holding in position the plurality of electric heating elements inside the channel.

[0028] The holding device allows the heating elements to be positioned relative to each other and to the wall of the channel. It allows the desired spacing to be maintained between the heating elements on the one hand and between the inner wall of the channel and the heating elements adjacent to the inner wall on the other.

[0029] According to an optional feature of the invention, each heating element has an electrical connection terminal at each end, at least one of these ends protruding in a direction secant to the second plane, preferably perpendicular to the second plane.

[0030] Such an arrangement of the ends of the electrical connection terminals allows the electrical connection to be oriented in a different direction from the fluid connection that supplies the heat transfer fluid into the channel. This avoids any risk of the heat transfer fluid coming into contact with the electrical connection terminals.

[0031] Preferably, at least two of said plurality of electric heating elements are arranged parallel to each other along a width of the channel and arranged on the same plane over at least 70%, preferably at least 80%, preferably at least 90% of the length of the sinuous path.

[0032] Advantageously, the circulation chamber is formed between the hood and the housing.

[0033] The invention also relates to a heating device for heating a fluid heat transfer fluid, the heating system comprising: - a circulation chamber formed between a hood and a housing, the circulation chamber comprising at least one channel in which a heat transfer fluid is intended to circulate, the channel extending along a length of the channel between an inlet and an outlet and forming a sinuous path; - a plurality of electric heating elements arranged in the channel and intended to be in contact with the heat transfer fluid; the plurality of electric heating elements extending side by side within the same channel along the winding path, at least two of said plurality of electric heating elements are arranged parallel to each other along a width of the channel and arranged on the same plane over at least 70%, preferably at least 80%, preferably at least 90% of the length of the winding path.

[0034] The invention may also include one or more of the features mentioned above.

[0035] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and the illustrative and non-limiting examples of embodiments given with reference to the accompanying drawings on the other hand, in which:

[0036] [Fig-1] is a partial perspective view of a heating device according to the invention.

[0037] [Fig.2] is a bottom view of the heating device according to the embodiment of the [Fig.1], without the hood.

[0038] [Fig.3] is a partial perspective view of a variant of a heating device according to the invention.

[0039] [Fig.4] is a perspective view of the heating device variant according to the invention shown in [Fig.3], without the case.

[0040] [Fig.5] is a cross-sectional view of the circulation chamber of the heating device according to a plan P3 shown in [Fig.1].

[0041] [Fig.6] is a cross-sectional view of the channel and the electric heating elements according to a plane parallel to plane P2.

[0042] [Fig.7] is a schematic cross-sectional view of a positioning device two electric heating elements inside the channel.

[0043] [Fig-8] is a partial perspective view of the heating device according to the invention, without the hood.

[0044] The features, variants, and different embodiments of the invention, as described or as they will be presented in the detailed description that follows, can be combined in various ways, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0045] For the sake of clarity, the same elements are designated by the same references in the different figures.

[0046] Figure 1 is a partial perspective view of a heating device 10 according to the invention. Such a heating device 10 is intended to heat a heat transfer fluid. The heat transfer fluid is, for example, a mixture of water and glycol, the mass composition of which may be 50% water and 50% glycol. The heating device 10 comprises a circulation chamber extending between a first plane P1 and a second plane P2, parallel to the first plane P1. According to the invention, the heating device 10 comprises a cover 11. As shown, the cover 11 is generally planar in shape. However, the cover 11 is not necessarily planar.

[0047] The heating device 10 comprises a casing 12 extending, over a height h of the circulation chamber perpendicular to the first plane PI, from the second plane P2 to the cover 11. In other words, planes PI and P2 are separated by the height h, which thus represents the height of the circulation chamber. The casing includes at least one channel 13 in which the heat transfer fluid is intended to circulate. The channel 13 extends over a length 14 of the channel between an inlet 15 and an outlet 16 and forms a sinuous path comprising at least one half-turn between the inlet 15 and the outlet 16. In [Fig. 1], by way of non-limiting example, the channel comprises five half-turns. The sinuous path is the path followed by the heat transfer fluid as it passes through the heating device. By sinuous, it is understood that the path is not straight and forms undulations.We also speak of a wavy or tortuous path, which presents a series of curves oriented in different directions.

[0048] It is therefore understood that the housing 12 is pressed against the cover 11 so as to create a sealed space between the two; this space is the channel 13. When the heat transfer fluid circulates inside the channel 13, it cannot therefore escape between the housing 12 and the cover 11. The heat transfer fluid enters the heating device 10 through the inlet 15 of channel 13 and leaves the heating device, after having passed through the entire length 14 of channel 13, by the outlet 16.

[0049] The heating device 10 comprises a plurality of electric heating elements 21, 22 of a shape complementary to the channel 13. This means that the electric heating elements have a sinuous, or tortuous, shape so as to be able to be arranged in the channel 13. The electric heating elements are intended to be in contact with the heat transfer fluid in the channel.

[0050] As can be seen in [Fig. 1], the electric heating elements 21, 22 extend side by side within the same channel 13 along the winding path. The plurality of electric heating elements 21, 22 are arranged parallel to each other along a width 17 of the channel perpendicular to the height of the circulation chamber. Each electric heating element extends within the channel 13 and follows the winding path of the channel. The electric heating elements 21, 22 are arranged within the channel 13. Each electric heating element is spaced from the adjacent electric heating element. The electric heating elements do not come into contact with each other, nor do they touch the inner wall 13a (visible in [Fig. 2]) of the channel 13. They extend along the channel, coplanarly, in a plane parallel to the second plane P2, side by side. In axial projection onto the second plane P2, the electric heating elements are side-by-side..

[0051] Thanks to these features, the heating device of the invention has a lower height than a prior art heating device with superimposed electric heating elements. The arrangement of several electric heating elements side by side in the channel ensures the desired thermal output while avoiding excessive height of the heating device.

[0052] It should be noted that in [Fig. 1], the entire heating system is not shown. [Fig. 1] illustrates the circulation chamber, the housing, the cover, and the electric heating elements.

[0053] In an alternative embodiment of the invention, not shown, the winding path comprises only one half-turn. In this configuration, the electric heating elements form a U-shape, that is, they extend along a first straight section, a half-turn, and a second straight section (also U-shaped), parallel to the first straight section. Such an embodiment ensures the compactness of the heating device.

[0054] In another variant, as shown in [Fig. 1], the winding path involves several half-turns. The path therefore consists of a succession of straight sections and U-shaped sections, with two straight sections being connected on either side of a U-shaped section.

[0055] The particular shape of the channel forming the sinuous path between its inlet and outlet makes it possible to have the length of electric heating elements required to obtain the thermal power to be delivered. In other words, the winding path of the channel, and therefore the winding path of the electric heating elements, allows for a significantly greater length of heating elements within the heating system than the overall length of the heating system. This results in a very favorable ratio between the available thermal power and the overall size of the heating system. This ratio is even more advantageous with parallel straight sections and successive half-turns with varying radii of curvature.

[0056] In the figures, two electric heating elements are shown. However, the scope of the invention remains unchanged when the heating device comprises three, four or more electric heating elements.

[0057] The plurality of heating elements extends within the same channel, from the channel inlet to the channel outlet. Regardless of the number of heating elements, one heating element is arranged next to another heating element.

[0058] Fig. 2 is a bottom view of the heating device according to the embodiment of Fig. 1, without the cover. Each of the plurality of electric heating elements 21, 22 has an alternating succession of straight portions 213, 223 and U-shaped portions 214, 224. Following the winding path from the inlet 15 of the channel 13 to the outlet 16 of the channel 13, the heating element 21 comprises a first straight portion 213, then a first U-shaped portion 214, a second straight portion 213, and a second U-shaped portion 214, a third straight portion 213, a third U-shaped portion 214, a fourth straight portion 213, a fourth U-shaped portion 214, a fifth straight portion 213, a fifth U-shaped portion 214 and finally a sixth straight portion 213 which joins the outlet 16.The heating element 22 is composed in a similar way with the straight portions 223 and the U-shaped portions 224.

[0059] Since the electric heating elements are arranged parallel to each other along the width 17 of the channel, a U-shaped portion of one heating element is located inside a U-shaped portion of another heating element. For example, if we consider the first and second straight portions 213 and the first U-shaped portion 214 of the heating element 21 and the first and second straight portions 223 and the first U-shaped portion 224 of the heating element 22, we see that the portions 223, 224, 223 of the heating element 22 extend inside the portions 213, 214, 213 of the heating element 21. This implies that the U-shaped portion 224 has a smaller radius of curvature than the U-shaped portion 214. In prior art solutions, this small radius of curvature was a limiting factor because it could lead to damage to the heating element.The heating device of the invention thus presents an innovative solution for . Positioning heating elements side-by-side is possible using heating elements with a small radius of curvature. This is achieved through a specific manufacturing process that involves heating the heating element to a temperature above its recrystallization temperature before bending it into shape. This process is known as recrystallization annealing. This step gives the outer shell a higher hardness and helps maintain the compaction of the magnesium oxide despite the small radius of curvature. Therefore, it is possible to use heating elements with a small radius of curvature.

[0060] Due to this configuration, the straight portions 213, 223 are in particular of identical length and, for the same element, two successive U-shaped portions have a different radius of curvature.

[0061] According to an optional feature of the invention, the channel 13 is formed by the housing itself. The housing 12 has the shape of the channel. This particular shape of the housing 12 makes it possible to form the channel 13 without the need for additional parts.

[0062] Each heating element 21, 22 has an electrical connection terminal 215, 216 (for element 21) and 225, 226 (for element 22) at each end. In [Fig. 2], the connection terminals are arranged on the same side of the chamber and the number of half-turns is odd. Note that the electrical heating elements 21, 22 are of different lengths.

[0063] This configuration has the advantage of providing all electrical connection terminals on the same side of the heating device. This results in easy connection to auxiliary components.

[0064] As described previously, each heating element 21, 22 has an electrical connection terminal at each end. In one embodiment of the invention, at least one of these ends protrudes in a direction secant to the second plane P2, preferably perpendicular to the second plane. This arrangement is visible in Figures 1 and 2. The inlet 15 and outlet 16 of the channel 13 are oriented to allow the heat transfer fluid to flow parallel to the plane P2. This orientation of the electrical connection terminals prevents the electrical connections of the heating elements from overlapping with the fluid connection of the heat transfer fluid to the channel.

[0065] Figure 3 is a partial perspective view of a variant of the heating device 100 according to the invention. Figure 4 is a perspective view of the variant of the heating device according to the invention shown in Figure 3, without the housing 12.

[0066] The heating device 100 is identical to the heating device 10. It differs from the heating device 10 described above in the number of half-turns of the channel. In the heating device 100, there are four. that is to say an even number of half-turns. In this variant, the connection terminals are arranged on two opposite sides of the circulation chamber.

[0067] This configuration has the advantage of featuring electric heating elements 21, 22 of identical length. Since the electric heating elements have the same cross-section, it follows that they are identical to each other. This simplifies the manufacture and supply of electric heating elements, as it is not necessary to provide different shapes and / or lengths of heating elements.

[0068] Figure 5 is a cross-sectional view of the circulation chamber of the heating device along a plane P3 shown in Figure 1. Plane P3 is perpendicular to the straight portions of the heating elements 21, 22. The spacing between two adjacent heating elements is visible. They are arranged along the width 17 of the channel 13 so as to be spaced apart from each other and from the inner wall 13a. Being spaced apart means that they are not in contact and that a gap separates them. This means that each heating element is intended to be in contact with the heat transfer fluid only when the heat transfer fluid circulates through the channel 13.

[0069] According to an optional feature of the invention, the heating device 10 may further comprise at least one temperature-sensitive element such as a fuse 30 disposed on the housing 12. The invention is subsequently described in the case of a fuse. However, the temperature-sensitive element may be any other element that reacts to a temperature change, for example, a temperature sensor. In [Fig. 5], only one fuse 30 is shown, but it is entirely possible to position several others at other locations on the housing. A lower surface 31 of the fuse 30 is located in the second plane P2, aligned with the plurality of electric heating elements, and in a plane passing through the fuse and coinciding with the cross-section of the channel 13, the fuse 30 is disposed equidistant from the heating elements, or median with respect to the channel. The lower surface 31 is the sensitive surface of the fuse 30, which allows the temperature of the housing 12 to be detected.If the temperature detected at the level of box 12 is higher than a predefined temperature, signifying abnormal heating of the heating device for example due to a lack of heat transfer fluid, the fuse opens to guarantee the safety of users and to prevent damage to the heating device.

[0070] Generally, a layer of thermal interface material is disposed between the lower surface and the housing. A thermal interface material (also known by its acronym TIM) fills the tiny microscopic voids present between two non-uniform surfaces with a substance that has better thermal conductivity than air. TIMs can include various materials used to improve thermal conductivity, thus ensuring efficient heat transfer between the housing and the fuse.

[0071] The fuse is positioned on the housing 12, above the heating elements, equidistant from them, or medianally with respect to the channel. This means that the fuse is as close as possible to each of the heating elements, facing each of them, as much as possible. Arranging the electric heating elements side by side in the channel allows for better positioning of the fuse relative to the heating elements, thus improving its performance. In particular, the fuse can receive the full energy density from the channel. This results in more precise temperature detection since the fuse is equidistant from the electric heating elements and is therefore able to best capture the temperature inside the channel.

[0072] Figure 6 is a cross-sectional view of the channel 13 on the one hand (upper part of the figure) and of the electric heating elements 21, 22 on the other hand (lower part of the figure) along a plane parallel to plane P2. This view allows visualization of the complementary shape of the electric heating elements to that of the channel, so that the straight portions of the heating elements take position in the associated straight portion of the channel and the U-shaped portions of the heating elements take position in the curved portions of the channel.

[0073] Figure 7 is a schematic cross-sectional view of a positioning device 40 for two electric heating elements 21, 22 inside the channel 13. The heating device according to the invention may indeed include a positioning device 40 for the plurality of electric heating elements 21, 22 inside the channel 13. The positioning device 40 is designed to hold the heating elements 21, 22 at the desired spacing between them and with respect to the inner wall 13a of the channel 13. The positioning device 40 comprises a plurality of clamping legs 43, here four in number. The positioning device 40 includes two clamping legs 43 per heating element in the channel. The clamping legs 43 clamp around the heating elements 21, 22.Each clamping leg 43 extends from a head 45 in contact with the upper wall of the channel 13 to a lateral foot 44, in contact with the cover 11 and a lower part of the inner wall 13a of the channel, and a central foot 46, in contact with the cover. It is therefore understood that the holding device 40 comprises a number of heads 45 equal to the number of heating elements. And the number of central feet 46 is equal to the number of heating elements minus one (here we see one central foot for two heating elements).

[0074] Figure 8 is a partial perspective view of the heating device according to the invention, without the hood. The perspective view of Figure 8 represents the chamber of Circulation viewed from below. In this view, the electric heating elements 21, 22 are seen near their electrical connection terminals 215, 225 (not visible in this view) at the inlet 15 of channel 13. Channel 13 is intended to be supplied with heat transfer fluid (indicated by arrow 154) through an opening 151. Channel 13 is closed by a closing element 152. Thus, the electrical connection terminals 215, 225 are isolated from the heat transfer fluid.

[0075] The invention relates particularly to the circulation chamber, the housing 12 forming the channel 13 in which the electric heating elements are arranged. Such a heating device also includes an electronic compartment located above the circulation chamber and to which the electric heating elements, and where applicable the temperature-sensitive element, are connected.

[0076] The invention effectively solves the problem it set out to address by proposing a heating device that meets the requirements of compactness for easy installation in a vehicle and offers high thermal power density. Furthermore, the heating device ensures precise and reliable temperature control during operation.

[0077] Of course, the invention is not limited to the examples just described, and many modifications can be made to these examples without departing from the scope of the invention. In particular, the features of different embodiments of the invention can be combined to carry out the invention, provided that these embodiments are not incompatible with each other.

Claims

Demands

1. Heating device (10, 100) intended to heat a heat transfer fluid, the heating device (10) comprising a circulation chamber extending between a first plane (PI) and a second plane (P2), parallel to the first plane (PI), characterized in that it comprises: - A hood (11); - A casing (12) extending, along a height of the circulation chamber perpendicular to the first plane (PI), from the second plane (P2) to the hood (11), the casing having at least one channel (13) in which a heat transfer fluid is intended to circulate, the channel (13) extending along a length (14) of the channel between an inlet (15) and an outlet (16) and forming a sinuous path; - A plurality of electric heating elements (21, 22) of complementary shape to the channel (13), the plurality of electric heating elements (21, 22) being arranged in the channel (13) and intended to be in contact with the heat transfer fluid;the plurality of electric heating elements (21, 22) extending side by side within the same channel (13) along the winding path, said plurality of electric heating elements being arranged parallel to each other along a width (17) of the channel perpendicular to the height of the circulation chamber.;

2. Heating device (10, 100) according to claim 1, wherein the sinuous path of the channel includes at least one half-turn between the inlet (15) and the outlet (16)

3. Heating device (10, 100) according to claim 1 or 2, wherein each of the plurality of electric heating elements (21, 22) has an alternating succession of straight portions (213, 223) and U-shaped portions (214, 224), the straight portions (213, 223) in particular being of identical length and two successive U-shaped portions (214, 224) having a different radius of curvature.

4. Heating device (10, 100) according to claim 3 in which the straight portions (213, 223) of the plurality of electric heating elements (21, 22) are all parallel to each other.

5. Heating device (10, 100) according to any one of claims 1 to 4, further comprising at least one heat-sensitive element, for example a fuse (30), disposed on the housing (12), a lower surface (31) of at least one heat-sensitive element (30) being located in the second plane (P2) in particular at the right of the plurality of electric heating elements.

6. Heating device (10, 100) according to the preceding claim in which, in a plane passing through the heat-sensitive element and coinciding with the channel section, the heat-sensitive element is arranged equidistant from the heating elements, or median with respect to the channel.

7. Heating device (10, 100) according to any one of claims 1 to 6, wherein each heating element (21, 22) has an electrical connection terminal (215, 216; 225, 226) at each end.

8. Heating device (10) according to claim 7, wherein the connection terminals are arranged on the same side of the chamber and the number of half-turns is odd.

9. Heating device (10) according to any one of the preceding claims wherein the plurality of electric heating elements (21, 22) are of different lengths.

10. Heating device (100) according to claim 7 in which the connection terminals are arranged on two opposite sides of the circulation chamber and the number of half-turns being even.

11. Heating device (100) according to any one of claims 1 to 7 or according to claim 10, wherein the plurality of electric heating elements (21, 22) are of identical length and / or the plurality of electric heating elements (21, 22) are identical.

12. Heating device (10, 100) according to any one of claims 1 to 11, comprising a device for holding in position (40) the plurality of electric heating elements (21, 22) inside the channel (13).

13. Heating device (10, 100) according to any one of claims 7, 8, or 10, wherein each heating element (21, 22) has an electrical connection terminal (215, 216; 225, 226) at each end, at least one of these ends protruding in a direction secant to the second plane (P2), preferably perpendicular to the second plane.