Flexible heating structure in particular for a motor vehicle

Abstract

Disclosed is a flexible heating structure (1), comprising: - a flexible substrate (3), - at least one resistive layer (5, 5', 5") configured to produce heat, the resistive layer (5, 5', 5") in particular being a resistive ink deposited on the flexible substrate (3), - at least two electrodes (7, 73) making electrical contact with the resistive layer (5, 5', 5") so as to allow an electric current to flow through the resistive layer (5, 5', 5") between these two electrodes (7, 73), - at least one circuit of negative-temperature-coefficient thermistors (10) that is electrically insulated from the at least one resistive layer (5, 5', 5") by at least one electrically insulating layer (12, 12', 12"), the negative-temperature-coefficient thermistors (10) being distributed over the entire area covered by the at least one resistive layer (5, 5', 5").

Description

Description Title of the invention: Flexible heating structure, particularly for a motor vehicle

[0001] The present invention relates to a comfort system, in particular for a motor vehicle and more particularly to a heating structure intended to be arranged within the passenger compartment.

[0002] In order to generate heat locally, for example within a passenger compartment, it is known to place heating panels at defined locations. These heating panels may in particular comprise a heating structure comprising at least one resistive layer, for example a carbon-based sheet, deposited on a substrate and configured to generate heat under the action of an electric current.

[0003] However, such heating structures can heat up to high temperatures, for example around 110°C. It is therefore necessary to provide a safety system to detect if a user comes into contact with the heating structure.

[0004] Furthermore, in order to allow good integration within the vehicle, and in particular within the motor vehicle, it is necessary that the heating structure can adapt to the different shapes and reliefs of the passenger compartment.

[0005] One of the aims of the present invention is therefore to remedy at least partially the drawbacks of the prior art and to propose an improved heating structure which can be adapted within the passenger compartment and is secure.

[0006] The present invention therefore relates to a flexible heating structure, in particular intended to be installed inside a passenger compartment of a vehicle, in particular a motor vehicle, said heating structure comprising: - a flexible substrate, - at least one resistive layer configured to produce heat when this resistive layer is traversed by an electric current, this resistive layer being in particular a resistive ink deposited on the flexible substrate, - at least two electrodes in electrical contact with the resistive layer so as to allow an electric current to flow through the resistive layer between these two electrodes, - at least one negative temperature coefficient thermistor circuit, said at least one negative temperature coefficient thermistor circuit being electrically insulated from the at least one resistive layer by at least one electrically insulating layer, said negative temperature coefficient thermistors being distributed over the entire surface covered by the at least one resistive layer.

[0007] According to one aspect of the invention, the at least one electrically insulating layer comprises a base chosen from one or more of the following components: acrylic, epoxy, polyurethane, silicone varnish, acrylic and urethane mixture, fluoropolymer varnish, fluorocarbon varnish, perfluoroether varnish.

[0008] According to another aspect of the invention, the negative temperature coefficient thermistors of the same circuit are connected to each other by a flexible electrical connector.

[0009] According to another aspect of the invention, the negative temperature coefficient thermistors are spaced from each other by a distance of between 1 cm and 2 cm, preferably 1.5 cm.

[0010] According to another aspect of the invention, the negative temperature coefficient thermistors have a length of between 0.2 mm and 1 mm and a width of between 0.5 mm and 0.1 mm.

[0011] According to another aspect of the invention, the flexible heating structure corresponds to a stack successively comprising: - the flexible substrate, - at least one negative temperature coefficient thermistor circuit, - at least one electrically insulating layer, - at least one resistive layer.

[0012] According to another aspect of the invention, the flexible heating structure corresponds to a stack successively comprising: - the flexible substrate, - at least one resistive layer, - at least one first electrically insulating layer, - at least one negative temperature coefficient thermistor circuit, - at least one second electrically insulating layer.

[0013] According to another aspect of the invention, the flexible heating structure corresponds to a stack successively comprising: - the flexible substrate, - at least one first resistive layer, - at least one first electrically insulating layer, - at least one negative temperature coefficient thermistor circuit, - at least one second electrically insulating layer, - at least a second resistive layer.

[0014] According to another aspect of the invention, the negative temperature coefficient thermistors are connected in series within the same circuit.

[0015] According to another aspect of the invention, the negative temperature coefficient thermistors are connected by a bus with individual addressing or by groups within the same circuit.

[0016] The present invention also relates to a heating device comprising a flexible heating structure as described above, the at least one negative temperature coefficient thermistor circuit being connected to an electronic controller configured to cut off the power supply to the at least one resistive layer upon detection of a drop in temperature on at least one negative temperature coefficient thermistor.

[0017] The present invention also relates to a method of manufacturing a flexible heating structure, said method comprising the following steps: - installation of at least one negative temperature coefficient thermistor circuit on a flexible substrate, - deposition of at least one electrically insulating layer covering the at least one negative temperature coefficient thermistor circuit, - depositing at least one resistive layer on the at least one electrically insulating layer.

[0018] The present invention also relates to a method of manufacturing a flexible heating structure, said method comprising the following steps: - deposition of at least one resistive layer on a flexible substrate, - depositing at least one first electrically insulating layer on the at least one resistive layer, - installation of at least one negative temperature coefficient thermistor circuit, - depositing at least one second electrically insulating layer covering the at least one negative temperature coefficient thermistor circuit.

[0019] The present invention also relates to a method of manufacturing a flexible heating structure, said method comprising the following steps: - deposition of at least a first resistive layer on a flexible substrate, - depositing at least one first electrically insulating layer on the at least one first resistive layer, - installation of at least one negative temperature coefficient thermistor circuit, - deposition of at least one second electrically insulating layer covering the at least one negative temperature coefficient thermistor circuit, - depositing at least one second resistive layer on the at least one second electrically insulating layer.

[0020] Other characteristics and advantages of the present invention will appear more clearly on reading the following description, provided for illustrative and non-limiting purposes, and the appended drawings in which:

[0021] [Fig 1] Figure 1 is a schematic sectional representation of the interior of the passenger compartment of a motor vehicle,

[0022] [Fig 2] Figure 2 is a schematic perspective representation of a flexible heating structure according to a first variant,

[0023] [Fig 3] Figure 3 is a schematic perspective representation of a flexible heating structure according to a second variant,

[0024] [Fig 4] Figure 4 is a schematic representation in top view of a flexible heating structure,

[0025] [Fig 5] Figure 5 is a schematic sectional representation of a flexible heating structure according to a first embodiment,

[0026] [Fig 6] Figure 6 is a schematic cross-sectional representation of a flexible heating structure according to a second embodiment

[0027] [Fig 7] Figure 7 is a schematic cross-sectional representation of a flexible heating structure according to a third embodiment.

[0028] In the various figures, identical elements bear the same reference numbers.

[0029] The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Single features of different embodiments may also be combined and / or interchanged to provide other embodiments.

[0030] In this description, certain elements or parameters may be indexed, such as first element or second element, as well as first parameter and second parameter, or first criterion and second criterion, etc. In this case, it is a simple indexing to differentiate and name elements or parameters or criteria that are close, but not identical. This indexing does not imply a priority of one element, parameter or criterion over another and such names can easily be interchanged without departing from the scope of this description. This indexing also does not imply an order in time, for example, to assess this or that criterion.

[0031] Figure f shows an interior view of a passenger compartment f00 of a motor vehicle V. Also shown are a door 101 and the roof f02 of the passenger compartment. Seats 103 for passengers are also visible.

[0032] In the example described, heating devices comprising heating structures f are integrated into the roof f02 of the passenger compartment. These heating devices can, for example, be coupled to lighting devices or flexible heating structures 1 can be installed alone. Such heating structures can thus be arranged on various components of a passenger compartment, such as, for example: - a component designed to be integrated into a vehicle door, - a component designed to be integrated into a dashboard, - a component for dressing a foot cellar, - a component of a roof or passenger compartment roof trim, - an armrest trim component, - a component of a glove box, - a pillar cladding component.

[0033] The passenger compartment component which comprises a heating structure 1 is in particular arranged to heat by thermal radiation or by thermal conduction or thermal contact, and not by heating by heat transported by air in forced movement within the passenger compartment.

[0034] As illustrated in Figure 2, a flexible heating structure 1 comprises a flexible substrate 3 as well as at least one resistive layer 5 arranged to produce heat when this resistive layer 5 is traversed by an electric current I.

[0035] The flexible substrate 3 may be of the textile type, woven or knitted, or of the non-woven type. The non-woven may comprise a mixture of polypropylene fibers and / or polyester fibers. Other fibers may be used, for example natural fibers.

[0036] Alternatively, the flexible substrate 3 may be a flexible plastic sheet or a foam such as TPU (thermoplastic polyurethane).

[0037] The flexible substrate 3 may in particular have a thickness of less than 1 cm, and an area of at least 10 cm2, or at least 50 cm2, or at least 500 cm2.

[0038] The resistive layer 5 may in particular be a resistive ink that can be deposited on the flexible substrate 3 by printing, screen printing or lamination. This resistive ink may in particular be a carbon-based ink.

[0039] The heating structure 1 further comprises two distribution electrodes 7, which are in electrical contact with the resistive layer 5 so as to allow an electric current to flow through the resistive layer 5 between these two electrodes 7.

[0040] The electrodes 7 may in particular comprise parallel sections between which the resistive layer 5 is located. The electrodes 7 may also comprise electrical supply wires 71.

[0041] The electrodes 7 can be deposited on the substrate 3 by printing, screen printing or lamination of several materials.

[0042] The electrodes 7 may be made of conductive material, in particular metallic material such as ink charged with conductive particles, in particular silver or copper particles.

[0043] In another example illustrated in Figure 3, the heating structure 1 may comprise an array of electrodes 7' as well as a plurality of resistive layers 5' distributed over the flexible substrate 3. This array of electrodes 7' may in particular comprise two distribution electrodes 72 and a plurality of contact electrodes 73 supplied with electric current by the distribution electrodes 72. The distribution electrodes 72 may be seen as "parent" electrodes and the contact electrodes 73 as "child" electrodes. Several contact electrodes 73 are thus connected to the same distribution electrode 72.

[0044] The contact electrodes 73 form pairs each associated with a dedicated resistive layer 5'. These resistive layers 5 can in particular be separated from each other and form several heating zones, for example with repetitive patterns.

[0045] As illustrated in Figure 4, the flexible heating structure 1 further comprises at least one negative temperature coefficient thermistor circuit 10. This at least one negative temperature coefficient thermistor circuit 10 is electrically insulated from the at least one resistive layer 5, 5', 5” by at least one electrically insulating layer 12, 12', 12” (visible in Figures 5 to 7). The negative temperature coefficient thermistors 10 are more particularly distributed over the entire surface covered by the at least one resistive layer 5, 5', 5”.

[0046] The negative temperature coefficient thermistors 10 make it possible to detect the drop in temperature of the heating structure caused by contact, for example, with a finger, a hand or an object or member having a temperature lower than the heating structure 1. Indeed, during this contact, the temperature of the heating structure 1 will drop locally by heat transfer to the object or member in contact.

[0047] The flexible heating structure 1 can thus be integrated into a heating device in which the negative temperature coefficient thermistor circuit 10 can be connected to an electronic controller configured to cut off the electrical power supply to the at least one resistive layer 5, 5', 5” upon detection of a drop in temperature on at least one negative temperature coefficient thermistor 10, in order to limit the risks of discomfort or burns.

[0048] The at least one electrically insulating layer 12, 12', 12” may in particular comprise a base chosen from one or more of the following components: acrylic, epoxy, polyurethane, silicone varnish, acrylic and urethane mixture (ARUR), fluoropolymer varnish, fluorocarbon varnish, perfluoroether varnish. This electrically insulating layer 12, 12', 12” makes it possible in particular to isolate the negative temperature coefficient thermistor circuit 10 and to avoid short circuits, in particular with the at least one resistive layer 5, 5', 5”.

[0049] The deposition of at least one such electrically insulating layer 12, 12', 12” can be carried out using various spraying or other processes. These processes may optionally include a thermal or UV polymerization treatment step depending on the insulator used.

[0050] In order to maintain the flexible aspect, the negative temperature coefficient thermistors 10 of the same circuit can in particular be connected to each other by a flexible electrical connector 11, for example of the Flex PCB type.

[0051] The negative temperature coefficient thermistors 10 may more particularly be spaced from each other by a distance of between 1 cm and 2 cm, preferably 1.5 cm. This spacing allows in particular that objects or a finger pressing on the flexible heating structure 1 is detected.

[0052] In order to maintain good sensitivity of the detection zone as well as good reactivity of the negative temperature coefficient 10 thermistors, the latter can have a length between 0.2 mm and 1 mm and a width between 0.5 mm and 0.1 mm. This reduced size of the negative temperature coefficient 10 thermistors means that the latter have low thermal inertia and therefore better reactivity.

[0053] As illustrated in Figure 4, negative temperature coefficient thermistors 10 can be connected in series within the same circuit.

[0054] However, it is quite possible to imagine other types of connection of thermistors with negative temperature coefficient 10. Thus, the latter can not be connected in series but be linked by a bus with individual addressing or by groups within the same circuit.

[0055] According to a first embodiment illustrated in figure 5, the flexible heating structure can correspond to a stack successively comprising: - the flexible substrate 3, - at least one negative temperature coefficient thermistor circuit 10, - at least one electrically insulating layer 12, - at least one resistive layer 5.

[0056] In order to maintain a correct visual appearance as well as an acceptable feel of the flexible heating surface 1, the at least one electrically insulating layer 12 can completely cover the negative temperature coefficient thermistors 10 and thus present a flat surface on which the at least one resistive layer 5 is deposited.

[0057] Another solution not shown may also be that the at least one resistive layer 5 may have a sufficient thickness to completely cover the negative temperature coefficient thermistors 10 and thus present a flat surface.

[0058] The method of manufacturing the flexible heating structure 1 according to this first embodiment can thus comprise the following steps: - installation of at least one negative temperature coefficient thermistor circuit 10 on a flexible substrate 3, - deposition of at least one electrically insulating layer 12 covering the at least one negative temperature coefficient thermistor circuit 10, - depositing at least one resistive layer 5 on the at least one electrically insulating layer 12.

[0059] According to a second embodiment illustrated in Figure 6, the heating structure- flexible fan 1 can correspond to a stack comprising successively: - the flexible substrate 3, - at least one resistive layer 5, - at least one first electrically insulating layer 12', - at least one negative temperature coefficient thermistor circuit 10, - at least a second electrically insulating layer 12”.

[0060] In order to maintain a correct visual appearance as well as an acceptable feel of the flexible heating surface 1, the at least one second electrically insulating layer 12” can completely cover the at least one negative temperature coefficient thermistor circuit 10 and thus present a flat surface.

[0061] The method of manufacturing the flexible heating structure 1 according to this second embodiment can thus comprise the following steps: - depositing at least one resistive layer 5 on a flexible substrate 10, - depositing at least one first electrically insulating layer 12' on the at least one resistive layer 5, - installation of at least one negative temperature coefficient thermistor circuit, - deposition of at least one second electrically insulating layer 12” covering the at least one negative temperature coefficient thermistor circuit 10.

[0062] According to a variant, the at least one negative temperature coefficient thermistor circuit 10 may be electrically insulated beforehand and have an electrically insulating layer 12', 12” on these two faces. The steps of depositing the electrically insulating layers 12', 12” may thus be carried out beforehand. The deposition of the at least one resistive layer 5 on the flexible substrate 10 and the installation of the at least one negative temperature coefficient thermistor circuit 10 may thus be simultaneous.

[0063] According to a third embodiment illustrated in figure 7, the flexible heating structure 1 can correspond to a stack successively comprising: - the flexible substrate 3, - at least a first resistive layer 5', - at least one first electrically insulating layer 12', - at least one negative temperature coefficient thermistor circuit 10, - at least a second electrically insulating layer 12”, - at least a second 5” resistive layer.

[0064] In order to maintain a correct visual appearance as well as an acceptable feel of the flexible heating surface 1, the at least one second electrically insulating layer 12” can completely cover the at least one negative temperature coefficient thermistor circuit 10 and thus have a flat surface on which the at least one second resistive layer 5” is deposited.

[0065] The method of manufacturing the flexible heating structure 1 according to this third embodiment can thus comprise the following steps: - deposition of at least a first resistive layer 5' on a flexible substrate 10, - depositing at least one first electrically insulating layer 12' on the at least one first resistive layer 5', - installation of at least one circuit of thermistors with negative temperature coefficient 10, - deposition of at least one second electrically insulating layer 12” covering the at least one negative temperature coefficient thermistor circuit 10.

[0066] According to a variant, the at least one negative temperature coefficient thermistor circuit 10 may be electrically insulated beforehand and have an electrically insulating layer 12', 12” on these two faces. The steps of depositing the electrically insulating layers 12', 12” may thus be carried out beforehand. The deposition of the at least one first resistive layer 5' on the flexible substrate 10 and the installation of the at least one negative temperature coefficient thermistor circuit 10 may thus be simultaneous.

[0067] Thus, it is clear that due to its flexible aspect, the heating structure 1 can be easily arranged on elements, in particular of the passenger compartment of a motor vehicle, which are not flat. This flexibility of the heating structure 1 thus makes it possible to adapt to most of the shapes of these elements. In addition, the manufacturing method is particularly simple to implement, which makes it possible to reduce the costs of such a flexible heating structure 1.

Claims

Claims

1. Flexible heating structure (1), in particular intended to be installed inside a passenger compartment of a vehicle, in particular a motor vehicle, said heating structure (1) comprising: - a flexible substrate (3), - at least one resistive layer (5, 5', 5”) configured to produce heat when this resistive layer (5, 5', 5”) is traversed by an electric current, this resistive layer (5, 5', 5”) being in particular a resistive ink deposited on the flexible substrate (3), - at least two electrodes (7, 73) in electrical contact with the resistive layer (5, 5', 5”) so as to allow an electric current to flow through the resistive layer (5, 5', 5”) between these two electrodes (7, 73), - at least one negative temperature coefficient thermistor circuit (10) said at least one negative temperature coefficient thermistor circuit (10) being electrically insulated from the at least one resistive layer (5, 5', 5”) by at least one electrically insulating layer (12, 12', 12”), said negative temperature coefficient thermistors (10) being distributed over the entire surface covered by the at least one resistive layer (5, 5', 5”).

2. Flexible heating structure (1) according to the preceding claim, characterized in that the at least one electrically insulating layer (12, 12', 12”) comprises a base chosen from one or more of the following components: acrylic, epoxy, polyurethane, silicone varnish, acrylic and urethane mixture, fluoropolymer varnish, fluorocarbon varnish, perfluoroether varnish.

3. Flexible heating structure (1) according to any one of the preceding claims, characterized in that the negative temperature coefficient thermistors (10) of the same circuit are connected to each other by a flexible electrical connector (11).

4. Flexible heating structure (1) according to any one of the preceding claims, characterized in that the negative temperature coefficient thermistors (10) are spaced from each other by a distance of between 1 cm and 2 cm, preferably 1.5 cm.

5. Flexible heating structure (1) according to any one of the preceding claims, characterized in that the negative temperature coefficient thermistors (10) have a length of between 0.2 mm and 1 mm and a width of between 0.5 mm and 0.1 mm.

6. Flexible heating structure (1) according to any one of claims 1 to 5, characterized in that it corresponds to a stack successively comprising: - the flexible substrate (3), - at least one negative temperature coefficient thermistor circuit (10), - at least one electrically insulating layer (12), - at least one resistive layer (5).

7. Flexible heating structure (1) according to any one of claims 1 to 5, characterized in that it corresponds to a stack successively comprising: - the flexible substrate (3), - at least one resistive layer (5), - at least one first electrically insulating layer (12'), - at least one negative temperature coefficient thermistor circuit (10), - at least one second electrically insulating layer (12”).

8. Flexible heating structure (1) according to any one of claims 1 to 5, characterized in that it corresponds to a stack successively comprising: - the flexible substrate (3), - at least one first resistive layer (5'), - at least one first electrically insulating layer (12'), - at least one negative temperature coefficient thermistor circuit (10), - at least one second electrically insulating layer (12”), - at least a second resistive layer (5”).

9. Flexible heating structure (1) according to any one of claims 1 to 8, characterized in that the negative temperature coefficient thermistors (10) are connected in series within the same circuit.

10. Flexible heating structure (1) according to any one of claims 1 to 8, characterized in that the negative temperature coefficient thermistors (10) are connected by a bus with individual addressing or by groups within the same circuit.

11. A heating device comprising a flexible heating structure (1) according to any one of the preceding claims, characterized in that the at least one negative temperature coefficient thermistor circuit (10) is connected to an electronic controller configured to cut off the power supply to the at least one negative temperature coefficient thermistor circuit (10). at least one resistive layer (5, 5', 5”) upon detection of a temperature drop on at least one negative temperature coefficient thermistor (10).

12. A method of manufacturing a flexible heating structure (1), said method comprising the following steps: - placing at least one negative temperature coefficient thermistor circuit (10) on a flexible substrate (3), - deposition of at least one electrically insulating layer (12) covering the at least one negative temperature coefficient thermistor circuit (10), - depositing at least one resistive layer (5) on the at least one electrically insulating layer (12).

13. A method of manufacturing a flexible heating structure (1), said method comprising the following steps: - depositing at least one resistive layer (5) on a flexible substrate (10), - depositing at least one first electrically insulating layer (12') on the at least one resistive layer (5), - installation of at least one negative temperature coefficient thermistor circuit (10), - depositing at least one second electrically insulating layer (12”) covering the at least one negative temperature coefficient thermistor circuit (10).

14. A method of manufacturing a flexible heating structure (1), said method comprising the following steps: - depositing at least a first resistive layer (5') on a flexible substrate (10), - depositing at least one first electrically insulating layer (12') on the at least one first resistive layer (5'), - installation of at least one negative temperature coefficient thermistor circuit (10), - depositing at least one second electrically insulating layer (12”) covering the at least one negative temperature coefficient thermistor circuit (10), - depositing at least one second resistive layer (5”) on the at least one second electrically insulating layer (12”).

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