FR3096218A1 - radiant panel for motor vehicle interior - Google Patents

Abstract

The invention relates to a radiant panel (1) particularly intended to be installed inside a passenger compartment (3) of a vehicle (80), for example a motor vehicle, said radiant panel (1) comprising at least one electrode (11, 12) comprising at least one electric current input of first cross section S1 and a region remote from the input through which at least part of the electric current from said input passes, said remote region having a second cross section S2, S2 being smaller than S1 Figure for the abstract: Fig. 4

Description

radiant panel for motor vehicle interior

The field of the present invention relates to heating devices for the passenger compartment of a vehicle, in particular an automobile, and more particularly to radiant panels installed inside such a passenger compartment.

A radiant panel is a device generally comprising a network of electrodes supplying electric current to a conductive and resistive material arranged between the electrodes. The radiant panel is thus configured to deliver heat by Joule effect via the resistive part. The resistive material can be a layer of paint comprising carbon particles and/or metallic particles.

The thermal power P created by the Joule effect depends on the supply voltage U, as well as the electrical resistance R between the two electrodes (one being connected to the positive power supply terminal and the other electrode being connected to the negative terminal) and checks the law: P = U²/R. The resistance R being proportional to the distance d between the two electrodes, it is known to place the two electrodes at a constant distance d from each other in order to have a constant thermal power.

Once the radiant panel is powered by the vehicle's electrical network, an electric current flows through the electrode network and the resistive part. It is experimentally observed that the intensity of the current gradually decreases along the electrodes as the current is conveyed in the resistive material arranged between the electrodes. It is therefore difficult to obtain a thermal power, and therefore a thermal comfort, homogeneous over the entire surface of the radiant panel.

The present invention proposes to optimize the architecture of the network of electrodes of a radiant panel so as to overcome the problems of current drops observed.

To this end, the subject of the invention is a radiant panel in particular intended to be installed inside the passenger compartment of a vehicle, for example an automobile, said radiant panel comprising at least one electrode comprising at least one electric current input of first cross-section S1 and a region remote from the input through which at least part of the electric current coming from said input passes, said remote region having a second cross-section S2, S2 being smaller than S1.

Said radiant panel may further comprise one or more of the following characteristics, taken separately or in combination.

According to one aspect of the invention, the cross section of the electrode decreases continuously from the first cross section S1 to the second cross section S2.

According to another aspect of the invention, the cross section of the electrode decreases discontinuously from the first cross section S1 to the second cross section S2.

For example, the cross-section of the electrode decreases in successive stages.

According to an exemplary embodiment, the electrode has a thickness (e) measured along an axis locally perpendicular to the radiant panel, thickness (e) which is smaller in the second cross section S2 than in the first cross section S1.

As a variant of this embodiment, the electrode has a width (l) measured along an axis locally parallel to the radiant panel, width (l) which is identical in the second cross section S2 and in the first cross section S1.

According to another exemplary embodiment, the electrode has a width (l) measured along an axis locally parallel to the radiant panel, width (l) which is smaller in the second cross section S2 than in the first cross section S1.

As a variant of this embodiment, the electrode has a thickness (e) measured along an axis locally perpendicular to the radiant panel, thickness (e) which is identical in the second cross section S2 and in the first cross section S1.

The electrode has for example a trapezium shape when observed locally in a direction perpendicular to the radiant panel.

The electrode can also be in the form of a row of quadrilaterals, for example rectangles, when observed locally in a direction perpendicular to the radiant panel.

According to one aspect of the invention, the periphery of the electrode is formed by several rectilinear lines.

According to another aspect of the invention, the periphery of the electrode is formed by at least one curved part.

According to one aspect of the invention, the radiant panel comprises a dissipative region arranged to generate heat by Joule effect.

According to one example, the dissipative region has a shape chosen from any one of the following shapes: polygonal, rectangular, square, oval, circular, trapezoidal.

According to one aspect of the invention, at least one of the electrodes comprises at least one dissipative branch, in particular a plurality of dissipative branches, said dissipative branch being arranged to produce electric current flowing in the dissipative region.

As a variant, each electrode comprises a plurality of dissipative branches arranged to produce electric current flowing in the dissipative region.

According to an exemplary embodiment, the radiant panel comprises two electrodes of different polarities. One of the two electrodes is for example connected to a +12V supply terminal, while the other electrode is connected to the negative terminal. Provision can be made for each of the two electrodes to comprise a single electric current input or several electric current inputs.

According to one example, the two electrodes are arranged so that each electrical current input is located on the same side of the radiant panel.

Advantageously, the two electrodes are arranged such that each electrical current input is located along two opposite sides of the radiant panel.

According to one aspect of the invention, each dissipating branch of the first electrode is arranged between two dissipating branches of the second electrode, so that the electric current can be established between the dissipating branch of the first electrode and the two neighboring dissipating branches of the second electrode.

According to one example, each dissipating branch of the first electrode is equidistant from the two neighboring dissipating branches of the second electrode.

According to one aspect of the invention, the plurality of dissipating branches of one of the electrodes is electrically connected to a distributing branch of this electrode at the level of a junction point J _i , said distributing branch being arranged at least partly in outside the dissipative region, in particular said distributing branch being arranged completely outside the dissipative region.

According to one aspect of the invention, the dissipating branches have a section which decreases from a first end defined by the junction point J _i to a second end at a distance from the junction point J _i .

For example, the junction points are regularly spaced along the distributing branch.

According to another example, the dissipating branches are arranged substantially perpendicular to the distributing branch.

The decrease in the section of the dissipating branches can be done continuously or in successive stages.

According to one aspect of the invention, the distributing branches are located equidistant from each other.

For example, the distributing branches are substantially rectilinear and parallel to each other.

According to one aspect of the invention, the distributing branches are connected to an electrical power supply at at least one of their ends, in particular at each of their ends.

According to one aspect of the invention, the distributing branches are of opposite polarity.

According to one aspect of the invention, the cross-section of a distributor branch decreases in successive stages.

The invention also relates to a vehicle interior, for example an automobile, comprising a radiant panel defined as above.

According to one aspect of the invention, the passenger compartment component which comprises the radiant panel is arranged to heat by thermal radiation or by thermal conduction or thermal contact, and not by heating by convection, for example by heat transported by moving air. In particular, the radiant panel is not crossed by any air flow intended to cool or heat the passenger compartment. Preferably, the panel is disconnected from the air movement system.

Other advantages and characteristics of the invention will appear more clearly on reading the following description given by way of illustrative and non-limiting example, and the appended drawings, among which:

Figure 1 schematically illustrates a radiant panel according to the prior art and in a perspective view.

Figure 2 is a schematic representation of the electrical network of the radiant panel of figure 1.

FIG. 3 is a graph showing the evolution of the intensity of the electric current flowing in the electrodes of the radiant panel of FIG. 1 along said electrodes.

FIG. 4 schematically illustrates a radiant panel arranged in the (xy) plane and observed along the z axis (ie seen from the front), according to a first embodiment of the present invention.

Figure 5 schematically illustrates the radiant panel of Figure 4 in a perspective view.

FIG. 6 schematically illustrates a radiant panel according to arranged in the (xy) plane and observed along the z axis (ie seen from the front), according to a second embodiment of the present invention.

Figure 7 schematically illustrates a variant of the radiant panel of Figure 4.

Figure 8 schematically illustrates another variant of the radiant panel of Figure 4.

Figure 9 schematically illustrates a radiant panel according to the invention.

FIG. 10 illustrates a motor vehicle interior equipped with a radiant panel according to the present invention.

It should be noted that the figures, characteristics, 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. others. One can in particular 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.

In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

It should be noted that the figures expose the invention in detail to implement the invention. Said figures can of course be used to better define the invention, if necessary.

Figure 1 shows a perspective view of a radiant panel 1 of the prior art. Radiant panel 1 includes:

- a dissipative region 10,

- a network of electrodes (11, 12) composed of a first electrode 11 and a second electrode 12, arranged to cause an electric current to flow in the dissipative region 10 so as to generate heat by Joule effect in said dissipative region 10.

The electrodes (11, 12) are in electrical connection with an electrical power source which is capable of delivering an electric current of intensity I flowing through said electrodes (11, 12) and capable of delivering a voltage U between the electrode of positive polarity 11 and the electrode of negative polarity 12.

The electrodes (11, 12) are substantially parallel to each other and substantially rectilinear. They are equidistant from each other and have a substantially square cross section.

Since the dissipative region 10 is supplied with electric current by the electrodes (11, 12), it is able to generate heat by the Joule effect.

In the example shown in Figures 1 and 2, each electrode (11, 12) has an electrical current input located at one of its ends. The electrical current input of the first electrode 11 is connected to the positive terminal of a power supply, and the electrical current input of the second electrode 12 is connected to the negative terminal of this same power supply. In this example, the two current inputs are located on the same side of radiant panel 1.

FIG. 2 schematically illustrates the electrical network as described in FIG. 1. The dissipative region is symbolized by a set of N resistors connected in parallel between the two electrodes (11, 12).

According to Kirschhoff's laws, it is possible to deduce the intensity of the electric current I or J flowing along the first electrode 11 and the second electrode 12 respectively, depending on the intensity of the current i flowing in the dissipative region 10.

Regarding the first electrode 11:

I ₂ = I ₁ – i ₁

index 2 referring to the section of the first electrode 11 located between the ^1st and the ^2nd node, and i ₁ being the intensity of the current flowing in the resistor 1 ^era.

I _N+1 = I _N – i ₁

the index N referring to the section of the first electrode 11 located between the node N-1 and the node N, and i ₁ being the intensity of the current flowing in the 1 ^st resistor.

Regarding the second electrode 12:

J ₁ = J ₂ + i ₁

index 2 referring to the second electrode portion 12 located between the ^1st and the ^2nd node, and i ₁ being the intensity of the current flowing in the resistor 1 ^era.

J _N = J _N+1 + i ₁

the index N referring to the section of the second electrode 12 located between the node N-1 and the node N, and i ₁ being the intensity of the current flowing in the 1 ^st resistor.

Furthermore, the voltage U measured between the two electrodes at different nodes of the electrical circuit changes as follows:

U _N < U _N-1 < … < U ₁

FIG. 3 illustrates the drop in current observed experimentally along the electrodes (11, 12) as the electric current is transmitted to the dissipative region 10. x represents the abscissa of the point where the current intensity along the electrode (11, 12) and L corresponds to the total length of the electrode (11, 12).

The voltage U and the intensity of the current (I, J) not being constant, the electrical power P = RI² = U² / R and therefore the heat dissipated by Joule effect in the resistive part ( ie . the dissipative region 10) , is not constant.

The radiant panel 1 of the prior art shown in Figure 1 therefore does not heat evenly.

An object of the present invention is to propose configurations of the electrical network of a radiant panel making it possible to improve its heating performance.

Figure 4 schematically illustrates a radiant panel 1 arranged in the (xy) plane and observed along the z axis. Seen from the front, the radiant panel 1 has a generally frustoconical shape.

The radiant panel 1 comprises two electrodes (11, 12) of different polarities:

- a first electrode 11 comprising an electrical current input connected to the positive terminal of an electrical supply network of a vehicle,

- a second electrode 12 comprising an electric current input connected to the negative terminal of an electric power supply network of a vehicle.

Each of the two inputs is located at one end of the corresponding electrode.

The electrical current input of the first electrode 11 is connected to the positive terminal of a power supply, and the electrical current input of the second electrode 12 is connected to the negative terminal.

In this example, the two inputs (+ terminals and - terminals) are located on the same side of radiant panel 1.

The first electrode 11 includes an electrical current input of first cross-section S1 and a region remote from this input through which at least part of the electrical current coming from this input passes. This remote region has a second cross-section S2 smaller than S1.

It is specified that in FIG. 4, the electrical current input is located at one end of the first electrode 11 and the region remote from this electrical current input corresponds for example to the opposite end of this same electrode.

The cross section S _i is defined by the product of the thickness (e _i ) of the electrode measured along an axis locally perpendicular to the radiant panel 1 (here the z axis) and the width (l _i ) of this electrode measured along an axis locally parallel to the radiant panel (here the y axis). It is given by the formula:

S _i = e _i × l _i

The width (w₂for the first electrode 11 and l₂' for the second electrode 12) measured at the second cross section being smaller than the width (l₁for the first electrode 11 and l₁' for the second electrode 12) measured at the first cross section, the cross section (S2 for the first electrode 11 and S2' for the second electrode 12) is smaller than the cross section (S1 for the first electrode 11 and S1 'for the second electrode 12).

Each of the two electrodes (11, 12) has a trapezium shape when observed locally in a direction perpendicular to the radiant panel 1 ( ie along the z axis).

According to the embodiment illustrated in Figures 4 and 5, the periphery of each electrode (11, 12) is straight and the cross section (S_Iassociated with the first electrode 11 and S_I' associated with the second electrode 12) decreases continuously from the first cross section (S1 or S1’) to the second cross section (S2 or S2’).

By varying the section of the electrodes, it is therefore possible to anticipate the electrical current losses along said electrodes, while maintaining a constant distance d between the electrodes. It is therefore no longer necessary to oversize the size of the electrodes.

By varying the section of the electrodes, the quantity of conductive material constituting the electrodes is thus optimized, this material being generally expensive. Using less of this material reduces the total cost of the radiant panel. Finally, the optimization of the section of the electrodes makes it possible to maximize the heating zones on said panel.

The radiant panel 1 shown in Figure 4 further comprises a dissipative region 10 disposed between the first and second electrodes (11, 12). The dissipative region 10 is arranged to generate heat by the Joule effect when it is traversed by an electric current. Indeed, the electrodes (11, 12) are arranged to circulate this electric current in the dissipative region 10.

The dissipative region 10 is for example in the form of a layer of partially resistive conductive material.

The partially resistive conductive material is for example paint comprising carbon particles and/or metallic particles.

Advantageously, the radiant panel 1 comprises a support (not shown in the figures) on which the partially resistive conductive material is placed. The electrodes (11, 12) are for example obtained by screen printing on this support.

Figure 5 shows the radiant panel of Figure 4 shown in perspective. This view makes it possible to make visible the thickness (e) of each electrode, (e) being measured along the z axis locally perpendicular to the radiant panel 1.

The thickness (e ₂ for the first electrode 11 or e ₂ ' for the second electrode 12) measured at the level of the second cross section being smaller than the thickness (e ₁ for the first electrode 11 or e ₁ ' for the second electrode 12), the cross section (S2 _, S2') is smaller than the cross section (S1, S1').

According to a variant not shown, to vary the section of the electrodes, it is possible to vary only one of the parameters chosen from the thickness (e) or the width (l) while keeping the other parameter constant.

The radiant panel 1, shown in front view in Figure 6, differs from that shown in Figure 4 in that the first electrode 11 and the second electrode 12 are arranged such that each electric current input (positive terminal or negative terminal) is located on two opposite sides of this radiant panel 1.

According to this embodiment, the periphery of each electrode (11, 12) is rectilinear and the cross section (S_Iassociated with the first electrode 11 and S_I' associated with the second electrode 12) decreases continuously from the first section (S1 or S2) to the second section (S2 or S2’).

By varying the section of the electrodes (11, 12), it is therefore possible to limit the current losses along said electrodes, while maintaining a constant distance d between the electrodes.

Figures 7 and 8 illustrate variants of the radiant panel 1 of Figure 6.

The radiant panels 1 of FIGS. 6 to 8 comprise a dissipative region 10 supplied with electric current by the electrodes (11, 12) and capable of generating heat by the Joule effect.

The radiant panel 1 shown in Figure 5 further comprises a dissipative region 10 disposed between the first and second electrodes (11, 12). The dissipative region 10 is arranged to generate heat by the Joule effect when it is traversed by an electric current.

In the variants represented in FIGS. 6 to 8, the shape of the dissipative region 10 and/or the arrangement of the electric current inputs are varied. In Figures 6 and 8, the dissipative region 10 is in the form of a parallelogram and in Figure 7, it is in the form of a rectangle. The radiant panel 1 of Figure 8 differs from that illustrated in Figure 6, in that the position of the positive terminal and the negative terminal is reversed.

Advantageously, the total heating surface is greater when the electrical current inputs are located on two opposite sides of the radiant panel (embodiment illustrated in Figures 6 to 8) than when the electrical current inputs are located on the same side of the radiant panel (embodiment shown in Figures 4 and 5).

Figure 9 shows a radiant panel 1 according to the invention comprising a dissipative region 10 arranged to generate heat by Joule effect. The radiant panel 1 further comprises a first electrode 11 and a second electrode 12 arranged to produce an electric current in the dissipative region 10 so as to generate heat by Joule effect.

The first electrode 11 and the second electrode 12 are arranged as follows: each of the electrodes (11, 12) comprises a plurality of dissipative branches 13. These dissipative branches 13 are arranged to produce electric current flowing in the dissipative region 10.

In this example, the dissipating branches 13 are arranged as follows: each dissipating branch 13 of the first electrode 11 is arranged between two dissipating branches 13 of the second electrode 12. In this way, the electric current can be established between the dissipating branch 13 of the first electrode 11 and the two neighboring dissipating branches of the second electrode 12.

The dissipating branches 13 are substantially arranged alternately with each other (so-called “comb” shaped arrangement).

By the term "adjacent", it is understood that at least one of the dissipative branches of the first electrode is located at a sufficiently close distance from the two dissipative branches of the second electrode for the electric current to be able to flow in the dissipative region.

In this particular example, the plurality of dissipating branches 13 of the first electrode 11 are electrically connected to a distributing branch 14 (or bus bar ) of this first electrode 11 at a junction point J ₁₁ . This distributor branch 14 is arranged completely outside the dissipative region 10.

Conversely, the plurality of dissipating branches 13 of the second electrode 12 are electrically connected to a distributing branch 15 (or bus bar ) of this second electrode 12 at a junction point J ₁₂ . This distributing branch 15 is arranged completely outside the dissipative region 10.

The distributing branches (14, 15) therefore have the function of supplying the electric current to the dissipating branches 13. They are in electrical connection with an electric power source capable of delivering an electric current of an intensity I. This source is also able to deliver a voltage U applied between the distributing branch 14 and the distributing branch 15.

Several lines of electric current circulating in the dissipative region 10 have been represented in FIG. 9. By convention, the direction of circulation of the electric current circulates from the positive terminal (+12V) to the negative terminal.

In this particular example, the first electrode 11 comprises two electric current inputs at +12V. Each of these inputs is located at one end of the first electrode 11.

The first electrode 11 comprises an electric current inlet of first cross-section S1 at each of its ends and a region remote from this inlet through which at least part of the electric current coming from each inlet passes. This remote region has a second cross-section S2 smaller than S1. It is specified that the electrical current inputs are located on the distributing branch 14 of the first electrode 11.

Each electric current inlet is located at one end of the distributor branch 14 and the region remote from this electric current inlet is substantially located at half the total length of said distributor branch 14 that is substantially rectilinear.

According to this example, the cross-section of the distributing branch 14 decreases in successive stages.

The second electrode 12 comprises an electric current inlet of first cross-section S1′ at one of its ends and a region remote from this inlet through which at least part of the electric current coming from this inlet passes. This remote region has a second cross-section S2' smaller than S1'.

According to a variant not shown, the dissipating branches 13 may have a section which decreases from a first end defined by the junction point (J ₁₁ or J ₁₂ ) to a second end at a distance from this junction point.

FIG. 10 illustrates an example of integration of radiant panels 1 as previously described in a passenger compartment 3 of a motor vehicle 80. The radiant panels 1 are distributed in the passenger compartment 3 to locally generate heat in the direction of the zones intended to be occupied by one or more users of the motor vehicle 80. According to the example embodiment illustrated in FIG. 10, the radiant panels 1 are placed on various interior surfaces of the passenger compartment 3, such as the roof of the vehicle, the uprights windows, a lower part of the dashboard such as the footwell, or even the seat backs. Of course, other interior surfaces could be equipped with radiant panels 1 according to the configuration of the passenger compartment 3 and/or according to the needs of the users of the vehicle 80, such as the floor of the vehicle or the walls of the doors. Interior surfaces means surfaces facing the areas of the passenger compartment 3 occupied by users.

Of course, the characteristics, the variants and the different embodiments of the invention can be associated with each other, according to various combinations, insofar as they are not incompatible or exclusive of each other. In particular, variants of the invention may be imagined 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. In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

Claims (12)

Radiant panel (1) in particular intended to be installed inside a passenger compartment (3) of a vehicle (80), for example an automobile, said radiant panel (1) comprising at least one electrode (11, 12) comprising at least an electric current input of first cross section S1 and a region remote from the input through which at least a part of the electric current coming from said input passes, said remote region having a second cross section S2, S2 being smaller than S1. Radiant panel (1) according to claim 1, wherein the electrode has a thickness (e) measured along an axis locally perpendicular to the radiant panel (1), which thickness (e) is smaller in the second cross section S2 than in the first cross section S1. Radiant panel (1) according to one of the preceding claims, in which the electrode (11, 12) has a width (l) measured along an axis locally parallel to the radiant panel (1), which width (l) is smaller in the second section S2 than in the first section S1. Radiant panel (1) according to one of the preceding claims, said radiant panel (1) comprising two electrodes (11, 12) of different polarities. Radiant panel (1) according to claim 4, wherein the two electrodes (11, 12) are arranged such that each electrical current input is located on the same side of the radiant panel (1). Radiant panel (1) according to claim 4, wherein the two electrodes (11, 12) are arranged such that each electrical current input is located on two opposite sides of the radiant panel (1). Radiant panel (1) according to any one of the preceding claims, the radiant panel (1) comprising a dissipative region (10) arranged to generate heat by the Joule effect. Radiant panel (1) according to any one of the preceding claims, in which at least one of the electrodes (11, 12) comprises at least one dissipating branch (13), in particular a plurality of dissipating branches (13), said branch dissipator (13) being arranged to produce electric current flowing in the dissipative region (10). Radiant panel (1) according to claim 8, wherein each dissipating branch (13) of a first electrode (11) is arranged between two dissipating branches (13) of a second electrode (11), so that the electric current can be established between the dissipating branch (13) of the first electrode (11) and the two neighboring dissipating branches of the second electrode (12). Radiant panel (1) according to one of claims 8 to 9, in which the plurality of dissipating branches (13) of one of the electrodes (11, 12) is electrically connected to a distribution branch (14, 15) of this electrode at a junction point (J ₁₁ , J ₁₂ ), said distributor branch (14, 15) being arranged at least in part outside the dissipative region (10), in particular said distributor branch (14, 15) being arranged totally outside the dissipative region (10). Radiant panel (1) according to claim 10, taken in combination with one of claims 8 to 9, in which the dissipating branches (13) have a section which decreases from a first end defined by the junction point (J ₁₁ , J ₁₂ ) to a second end remote from the junction point (J ₁₁ , J ₁₂ ). Interior (3) of a vehicle (80), for example an automobile, comprising a radiant panel (1) defined according to any one of the preceding claims.