FR3076169A1 - CORRELATED COMMON MODE MODE IMPEDANCE FILTER HEATING DEVICE FOR RADIOPHONIC WAVE RECEPTION ANTENNA GLASS - Google Patents

Abstract

A heating device (DC) equips a window (V) comprising a radio wave reception antenna (AR), and comprises an electric heating circuit (CCE) connected to first (F1) and second (F2) electric wires. coupled to a power supply network powered by an electric power source (SA). The first (F1) and second (F2) electrical leads respectively comprise first (11) and second (I2) common mode inductors (11) coupled via a magnetic core (NM), and a capacitive component (CCP) is connected in parallel with the first (F1) and second (F2) electrical wires between the electric heating circuit (CCE) and the first (11) and second (I2) common mode inductors, and defining with the latter (11, I2) a filter (FM) preventing the circulation of parasitic frequencies from the supply network and / or the electric heating circuit (ECC).

Description

The invention relates to electric heating devices which equip certain windows comprising an antenna for receiving radio waves.

Certain systems, such as for example certain vehicles (generally motor vehicles), comprise at least one window comprising an antenna for receiving radio waves and a heating device responsible for heating it to defrost or demist it. This heating device comprises an electric heating circuit, for example with heating resistors, connected to first and second electric wires which are coupled to a power network supplied by a power supply source of the system.

As those skilled in the art know, the electric heating circuit being placed near the antenna, the latter is frequently parasitized, when the electric heating circuit is supplied, by the conduction of the parasitic frequencies coming from the electronics of the electrical power network which includes the electrical power source and / or the electrical heating circuit. To avoid this interference, it has been proposed to add filters to the heating device. In fact, since the electric heating circuit only needs a strong direct current to operate, the two filterings described below have been proposed.

A first, partial filtering can be ensured by first and second inductors connected in series on the first and second electrical wires in order to allow direct current to pass while intercepting only the parasitic frequencies coming from the electronics of the network. power supply which includes the power source.

A second, complete filtering can be provided by first and second LC type filters mounted on the first and second electrical wires, having their respective capacitors connected to ground in order to intercept the spurious frequencies coming from the electronics of the network d electrical power supply of which the electrical power supply is a part and draining the parasitic frequencies collected by the electrical heating circuit towards two ground points.

This second filtering is certainly complete, but it requires close to the glass the presence of good quality ground points (in particular because the radio frequencies can sometimes go up to 240 MHz). In addition, access to such ground points can be problematic due to a lack of space for the passage of electrical grounding wires and / or the installation of the glass in a support in plastic or synthetic material (such as a tailgate or a plastic rear door of a vehicle). Consequently, one can be forced to define in the systems dedicated ground paths to carry out the groundings, which turns out to be expensive. The invention therefore aims in particular to improve the situation.

It notably proposes for this purpose a heating device, on the one hand, intended to form part of a window comprising an antenna for receiving radio waves and intended to equip a system comprising an electrical power source supplying a network of power supply, and, on the other hand, comprising an electric heating circuit connected to first and second electric wires suitable for being coupled to this supply network.

This heating device is characterized by the fact: - that the first electric wire comprises a first common mode inductor connected in series, and the second electric wire comprises a second common mode inductor connected in series and coupled to the first mode inductor common via a magnetic core, and - that it comprises a capacitive component connected in parallel to the first and second electric wires between the electric heating circuit and the first and second common mode inductors, and defining with these a filter preventing circulation parasitic frequencies from the electronics of the power supply and / or the electric heating circuit.

Thanks to this common mode operation of the first and second common mode inductors, there is a perfect pairing which avoids the problems of asymmetry induced by the dispersions of inductors, because the virtual ground point is by design perfectly balanced. In addition, the first and second common mode inductors intercept the spurious frequencies from the electronics of the power supply network which includes the electrical power source, and the capacitive component collects the spurious frequencies from the electrical heating circuit. , without any grounding.

For example, each of the first and second common mode inductors can have an inductance between 0.1 μΗ and 100 μΗ.

Also for example, the capacitive component can have a capacity of between 0.1 pF and 100 pF. The invention also provides a window comprising an antenna for receiving radio waves and intended to equip a system comprising an electrical power source supplying a power network. This window is characterized by the fact that it also includes a heating device of the type presented above and suitable for being coupled to this supply network. The invention also provides a system comprising a source of electrical power supplying a power supply network and at least one window of the type of that presented above.

Such a system can, for example, constitute a vehicle, possibly a motor vehicle.

For example, when this system constitutes a motor vehicle, it may comprise a tailgate comprising the window, or a rear door comprising the window, or a windscreen, or a side window, or even a rear window comprising the window. Other characteristics and advantages of the invention will appear on examining the detailed description below, and the attached drawing, in which the single figure illustrates schematically and functionally, a vehicle tailgate equipped with an antenna and 'an embodiment of a heating device according to the invention. The object of the invention is in particular to propose a DC heating device intended to form part of a pane V, also comprising an antenna AR for receiving radio waves and intended to equip a system comprising an electrical power source SA supplying a power network.

It is considered in what follows, by way of nonlimiting example, that the system is a motor vehicle, such as for example a car. However, the invention is not limited to this type of system. It relates in fact to any system comprising at least one window comprising an antenna for receiving radio waves. Consequently, it concerns any type of vehicle (land, sea (or river), and air), installations, possibly of industrial type, and buildings.

In addition, it is considered in what follows, by way of nonlimiting example, that the window V is intended to equip a tailgate of a motor vehicle. However, in general, this invention can be used on any glazing of a motor vehicle serving as an antenna support, such as for example a rear door window, a windshield, or a side window, but also any non-metallic surface such as for example a plastic car fender.

In the single figure is schematically and functionally represented a tailgate HV of a vehicle comprising a window V equipped with an antenna AR for receiving radio waves and of an exemplary embodiment of a DC heating device according to the invention .

A DC heating device according to the invention comprises, as illustrated, an electric heating circuit CCE, first F1 and second F2 electric wires and an FM filter with common mode impedances 11 and I2.

The CCE electric heating circuit comprises, for example, at least one resistive element, possibly of PTC type (“Positive Temperature Coefficient”), and responsible for generating calories to heat the window V when it is traversed by an electric current . This electric heating circuit CCE further comprises a terminal connected to the first electric wire F1 and another terminal connected to the second electric wire F2. It will be noted that in a variant the electric heating circuit CCE could provide heating by induction.

The first electrical wire F1 is suitable for being coupled to a first terminal (for example positive) of a supply network supplied by an electrical supply source SA of the system, such as for example an electrical supply network coupled to a possibly rechargeable battery. In addition, this first electrical wire F1 comprises a first common mode inductor 11 forming part of the FM filter and connected in series between the first terminal of the power supply network and one of the terminals of the electric heating circuit CCE.

For example, this first common mode inductor 11 may have an inductance between 0.1 μΗ and 100 μΗ.

The second electrical wire F2 is suitable for being coupled to a second terminal (for example negative) of the supply network (supplied by the electrical supply source SA). In addition, this second electrical wire F2 comprises a second common mode inductor I2 forming part of the FM filter, connected in series between the second terminal of the power supply network and the other terminal of the electric heating circuit CCE, and coupled to the first common mode inductor 11 via an NM magnetic core.

For example, this second common mode inductor I2 can have an inductance between 0.1 μΗ and 100 μΗ.

It will be noted that the first 11 and second I2 common mode inductors are not necessarily exactly identical.

Also for example, this NM magnetic core can be made of ferrite. The first 11 and second I2 inductors are wound on this magnetic core NM (a bit like in a transformer).

This common mode operation of the first 11 and second I2 common mode inductors advantageously offers perfect pairing which makes it possible to avoid the asymmetry problems induced by the dispersions of inductors.

The FM filter also includes a capacitive component CCP connected in parallel, on the one hand, to the first electric wire F1 between the first common mode inductor 11 and one of the terminals of the electric heating circuit CCE, and, on the other hand , to the second electric wire F2 between the second common mode inductor 12 and the other terminal of the electric heating circuit CCE.

For example, this CCP capacitive component can be a capacitor. But it could be an electrical component whose capacitive nature is predominant.

Also for example, this CCP capacitive component can have a capacity of between 0.1 pF and 100 pF.

The first 11 and second I2 common mode inductors and the capacitive component CCP together define an FM filter which prevents the circulation of parasitic frequencies coming from the electronics of the power supply network of which the power supply SA and / or from the CCE electric heating circuit. More precisely, the first 11 and second I2 common mode inductors intercept the spurious frequencies which come from the electronics of the electrical power supply network of which the electrical power source SA is a part, and the capacitive component CCP collects the spurious frequencies which come from the CCE electric heating circuit. In fact, the differential layout of the CCP capacitive component defines a "virtual" mass for the CCE electric heating circuit.

Thanks to the invention, there is no longer any need to carry out a grounding. Consequently, it is now possible to install the window V in an environment which is far from a metallic element, such as for example on a support made of plastic or synthetic material (in particular a tailgate or a plastic rear door of a vehicle), or in a constrained environment where there is a lack of space for the passage of electrical grounding wires. In addition, the invention makes it possible to avoid having to install two LC type filters on the first F1 and second F2 electric wires, on either side of the CCE electric heating circuit.

In addition, the use of common mode inductors allows them to be perfectly matched, and therefore to obtain optimal performance without carrying out an expensive sorting of inductors. This also makes it possible to reduce the magnetic field necessary for filtering and therefore to use a substantially smaller magnetic core than in the case of the use of two separate inductors.

Claims (10)

1. Heating device (DC) for a window (V) comprising an antenna (AR) for receiving radio waves and intended to equip a system comprising an electrical power source (SA) supplying a power network, said device (DC) comprising an electrical heating circuit (CCE) connected to first (F1) and second (F2) electrical wires suitable for being coupled to said supply network, characterized in that said first electrical wire (F1) comprises a first common mode choke (11) connected in series, and said second electric wire (F2) comprises a second common mode choke (I2) connected in series and coupled to said first common mode choke (11) via a magnetic core ( NM), and in that it comprises a capacitive component (CCP) connected in parallel to said first (F1) and second (F2) electrical wires between said electrical heating circuit (CCE) and said first (11) and second e (I2) common mode inductors, and defining with these (11, I2) a filter (FM) preventing the circulation of parasitic frequencies coming from the electronics of said supply network and / or of said electric heating circuit (CCE ). 2. Device according to claim 1, characterized in that each of said first (11) and second (I2) common mode inductors with an inductance between 0.1 μΗ and 100 μΗ. 3. Device according to claim 1 or 2, characterized in that said capacitive component has a capacity between 0.1 pF and 100 pF. 4. Glass (V) comprising an antenna (AR) for receiving radio waves and intended to equip a system comprising an electrical power source (SA) supplying a power network, characterized in that it further comprises a heating device (DC) according to one of the preceding claims, suitable for being coupled to said supply network. 5. System comprising an electrical power source (SA) supplying a power network, characterized in that it further comprises at least one window (V) according to claim 4. 6. System according to claim 5, characterized in that it constitutes a vehicle. 7. System according to claim 6, characterized in that it constitutes a motor vehicle. 8. System according to claim 7, characterized in that it constitutes a motor vehicle comprising a tailgate comprising said window (V). 9. System according to claim 7, characterized in that it constitutes a motor vehicle comprising a rear door comprising said window (V). 10. System according to claim 7, characterized in that it constitutes a motor vehicle comprising a rear window comprising said window (V).