EP3728960A1

EP3728960A1 - Electrical heating device comprising earthing means

Info

Publication number: EP3728960A1
Application number: EP18833463.5A
Authority: EP
Inventors: Yann COUAPEL; Erwan Gogmos
Original assignee: Valeo Systemes Thermiques SAS
Current assignee: Valeo Systemes Thermiques SAS
Priority date: 2017-12-19
Filing date: 2018-12-10
Publication date: 2020-10-28
Also published as: WO2019122583A1; US20230142145A1; FR3075552A1; CN111566414A; FR3075552B1; CN111566414B; US11578893B2; US20200309409A1

Abstract

The invention relates to a heating device (1) for an air-conditioning housing, said heating device (1) comprising a heating body (2) supplied with current for heating an air flow passing through said heating body (2), said heating body (2) comprising heating elements through which said current passes and which are arranged in electrically insulated tubes (4) of the heating elements, said heating elements being controlled via a distribution unit (3), said heating device (1) comprising means for earthing a plurality of metal elements distributed in the heating body (2) and the distribution unit (3). Said heating device (1) is characterised in that said earthing means consist of a single earthing circuit which passes through the heating body (2) and the distribution unit (3) and is formed by arranging said metal elements in series with direct contact between said metal elements.

Description

ELECTRICAL HEATING DEVICE WITH GROUNDING MEANS

Field of the invention

The invention relates to a heating device for an air conditioning unit, comprising means for earthing. The invention also relates to an air conditioning unit comprising such a heating device. It will find its applications, especially in the field of motor vehicles.

State of the art

Electric heating devices are known to be integrated in vehicle air conditioning units. These are either additional radiators, combined with heating radiators covered by a heat transfer fluid, in vehicles with a combustion engine or main radiators, in electric or hybrid vehicles.

Such heating devices comprise a heating body accommodating heating units provided with heating elements supplied with electric current by electrodes. For reasons of electrical safety, it may be necessary to insulate the heating elements and their feed electrodes from the outside. For this, the heating units comprise tubes within which the heating elements and their electrode are located, the inner surface of the tube being provided with an electrically insulating layer to isolate the heating elements and their electrode.

These heating devices comprise a distribution unit capable of controlling the current flowing in the heating units, in particular via an electronic card.

Several elements belonging to both the heating body and the distribution unit must necessarily be grounded for safety.

As a reminder, the mass is the conductive part of electrical equipment likely to be touched by a person, who is not normally energized but can become so in the event of insulation fault of the active parts of this equipment.

Thus, all the metal carcasses of the heater must be connected to the ground for safety. In motor vehicles with a metal body, the body is used as electrical ground. It is customary to connect each metal element of the heating device to a stud itself connected to ground, that is to say the body in the example of the automobile. These include metal elements likely to be in contact with strong current in case of current leakage.

This implies a reduction of the links, often corresponding to ground cables, between each metal element and the stud. These connections to the pad are sometimes difficult to integrate, given the limited space available inside the heater. And there is a risk of interference between these links and others present within the heater.

Summary of the invention

The present invention aims to overcome the various disadvantages mentioned above, by a heating device allowing a grounding of its metal elements by means of a simple and easy construction within the heating body and the distribution unit, and where there is no risk of interference.

This object is achieved by means of a heating device for an air conditioning box comprising, in a conventional manner, a heating body supplied with current to heat a flow of air passing through said heating body, the heating element comprising heating elements traveled. by said current and being located in electrically insulated tubes of the heating elements, said heating elements being controlled via a distribution unit, the heating device comprising means for grounding a plurality of metal elements distributed in the heating body and the distribution unit.

This device is characterized principally in that the said grounding means consist of a single grounding circuit traversing the heating body and the distribution unit and formed by putting said metal elements in series by contact. direct between said metal elements.

The main idea of this invention is to provide a single ground circuit formed by a chain of metal elements to be grounded. In this chain, the metal elements are directly connected in pairs, so as to ensure electrical continuity. There is thus a series of metal elements in series within the heating device, forming the ground circuit. Each metal element forms a link in the electrical chain. There is no longer any specific wiring to be done when mounting the heater, which saves considerable time.

The ground circuit is thus simplified, especially since it requires fewer components, and those remaining are shorter and simpler than usual.

According to the different embodiments of the invention, which can be taken together or separately:

the heating device comprises a metal heat dissipation plate through which the grounding circuit passes.

the heating device comprises an electrical connection element between the heating body and said plate.

- The tubes are electrically connected to each other via heat sinks which are electrically conductive, the ground circuit passing successively by these tubes and heatsinks.

- The said electrical connection element is disposed between the plate and a tube belonging to the heating body.

said electrical connection element is disposed between the plate and a heat sink belonging to the heating body.

said electrical connection element is arranged between the plate and a metal cheek belonging to the heating body and in contact with at least one heat sink: the metal cheek may consist of an inter-dissipator plate, located between two adjacent dissipators, or may consist in a plate located between a dissipator and a lateral side of the frame delimiting the heating body.

said electrical connection element is arranged between the plate and any other conductive element of the heating body.

- The said electrical connection element is disposed between the plate and any other conductive element electrically connected to the heating body. - The said electrical connection element consists of a flexible blade clip adapted to ensure electrical continuity between said plate and the heating body.

- The clip comprises a first section adapted to hook on a flange of the plate, and a second section with the flexible blade resting on the heater.

- Said plate consists of a perforated plate, the first section of the clip having a free end on which is formed a shoulder which is inserted into a perforation of the plate, providing an elastic interlocking of the clip in the plate. the second section has a V shape with a branch connected to the first section and a free branch corresponding to said flexible blade capable of deforming by reducing the angle of the V to exert a constant pressure against the heating body.

said electrical connection element consists of a metal pin passing through an orifice provided for this purpose in said plate, said pin being able to ensure electrical continuity between said plate and the heating body.

said electrical connection element consists of a metal part fixed on the one hand to the heating body by welding or by any other technique ensuring electrical continuity between the heating element and the metal part, and on the other hand to said plate by resilient interlocking in a groove provided for this purpose in the plate.

- The dispensing unit comprises an electronic control board on which are attached heat-generating components, said plate being in contact with these components: these include transistors.

the heat sinks, of the fin type, extend from the tubes and touch each other between two adjacent tubes: the grounding circuit passes through these heat sinks. said plate is connected, via a metal connecting bar passing through the distribution unit, to a grounding stud arranged at the input of the distribution unit.

said connecting bar is overmolded in the housing, and forms an insert: this overmolding makes it possible to make part of the grounding circuit invisible, and to protect this part from the other components arranged in the housing; distribution unit. Indeed, overmolding prevents any contact of this circuit part with the other components. The overmolding also makes it possible to avoid any risk of detachment of the bar because of the vibrations of the on-board heating device. Advantageously, the bar forms an insert in the housing, which makes it possible to stiffen the protective housing. In this way, it is possible to combine both a grounding function with a protection box stiffening function, by means of a single bar. This pooling of functions also makes it possible to contribute to the compactness of the distribution unit.

- Said connecting bar is made of an electrically conductive material, metal type aluminum, steel, brass.

said protective case is made of an electrically insulating material, of the plastic type.

said bar comprises:

a first end electrically connected to the plate;

a central part overmolded in the casing;

- A second free end, overmolded in the housing, and connected to a grounding stud.

the bar extends orthogonally to the plate.

- The bar extends over substantially the entire length of the electronic card and remote from the electronic card: this avoids contact with the components attached to the electronic card. The invention also relates to an air conditioning unit comprising a heating device as described above.

Presentation of figures

The invention will be better understood, and other objects, details, features and advantages thereof will become more clearly apparent in the following detailed explanatory description of at least one embodiment of the invention given to As a purely illustrative and non-limiting example, with reference to the accompanying schematic drawings.

On these drawings:

FIG. 1 is a perspective view of a heating device according to the invention,

FIG. 2 is an enlarged view of FIG. 1 showing more particularly the dispensing unit according to the invention,

FIG. 3 shows in perspective an electrical connection element between a tube of the heating body and the plate of the distribution unit,

FIG. 4 is an enlarged view of the electrical connection element according to FIG.

3

- Figure 5 shows in perspective a ground bar connected to the plate.

detailed description

With reference to FIG. 1, the invention relates to an electric heater 1. This is, for example, a heating device 1, said high voltage, that is to say intended to be supplied by a direct current (DC) or AC (AC) having a voltage greater than 60 V, especially between 60 and 1000 V, more particularly between 180 and 600 V, and / or for releasing a heating power on the air or an electric power consumption greater than 2 kW, in particular between 2 kW and 10 kW.

Said heating device 1 comprises a heating body 2 supplied with electric power to heat a flow of air passing through said heating body 2.

Said heating body 2 here has a substantially parallelepipedal configuration, extending on the surface. It is intended to be positioned transversely to the flow of air to be heated. More specifically, said airflow is intended to be oriented perpendicularly to said heating body 2, that is to say perpendicularly to the plane of FIG. 1.

The heating body 2 comprises heating elements (not shown) traversed by said stream. The heating elements are, for example, PTC resistors (for positive temperature coefficient).

The heating elements are located inside metal tubes 4. To avoid any electrical contact between the heating elements and the tubes 4, a layer of electrically insulating and thermally conductive material coats the inner surface of the tubes 4.

Each set tube 4 / heating elements form what is called a heating unit.

Said heating units are selectively powered. This means that each heating unit is supplied with current independently of the others and can therefore be traversed by a different current, including its intensity, the current flowing through the other heating units. The value of the current in play here is in particular the value of the average current or the effective current.

The heating body 2 may comprise heat sinks 13, for example fins, in thermal contact relation with the tubes 4. The heat sinks 13 are positioned, in particular, between said tubes 4. For the sake of clarity, only certain heat sinks 13 extending end tubes 4 have been shown, so as not to overload Figure 1.

Said heating body 2 comprises a frame 5, in particular made of plastic material, accommodating said heating units and serving to hold said tubes 4.

Intermediate bars 14 are also provided between the tubes 4 in order to keep them in position.

Preferably, the heating device 1 further comprises a distribution unit 3 able to control the current flowing in said heating body 2.

Said distribution unit 3 is advantageously configured to control the current supplying the heating body 2, in particular the different heating units, for example by means of controlled switches, making it possible respectively to control a current flow in each of the heating units. heated. These are, in particular, transistors 12, for example of the Mosfet or IGBT type, operating in particular by width modulation pulse. These transistors 12 are particularly visible in FIG. 5, and are mounted on an electronic card 1 1 T-shaped, thus having a central axis of symmetry.

Said distribution unit 3 comprises a housing 8, visible in FIGS. 1, 2, 6 and 7, which completely covers said electronic card 1 1, and which comprises a connecting face 83, used for mounting and / or mechanical fixing of the This housing 8 is preferably designed in a plastic material, having electrically insulating properties, and obtained by molding.

During the operation of the heating elements, the transistors 12 emit a lot of heat. In order to avoid any overheating within the housing 8, a heat dissipation plate 6 is provided in the heating device 1. This plate 6 consists of a perforated plate, positioned in a plane parallel to the plane of the heating body 2, and located in front of the tubes 4 so that the flow of air passing through the heater body 2 also passes through this perforated plate 6. Thus, this plate 6 helps to heat the air flow.

The plate 6 consists mainly of a body 63 perforated which extend tabs (hidden by the transistors 12 in Figure 5) adapted to come into contact with the transistors 12 so as to draw the calories emanating from the transistors 12. The plate 6 heats up, via the transistors 12, and is then cooled via the air flow.

In such a heater 1, it is essential that the metal elements are grounded, so as to secure electrically.

To do this, there is a grounding circuit that passes through the entire heating device 1, so that each metal element can be connected to it. In particular, this grounding circuit consists of a succession of metal elements positioned in series and in direct contact two by two, and thus forming the circuit.

At the level of the heating body 2, the tubes 4 as well as the dissipators 13 and the intermediate bars 14 are metallic. In the configuration of the heating device 1 according to the invention, the heatsinks 13 are all connected to a tube 4 by direct contact, and the heatsinks 13 of two adjacent tubes 4 meet and are in direct contact too, or meet at the level of an intermediate bar 14. Consequently, the entire row of tubes 4, dissipators 13, and intermediate bars 14 are in electrical contact with each other, and the grounding circuit passes through the entire tubes 4, heatsinks 13, and intermediate bars 14 of the heater body 2. At the outlet of this row of tubes 4, dissipators 13, and intermediate bars 14, an electrical connection element 7 is arranged between an end tube 4 and the perforated plate 6, as illustrated in particular in FIGS. 5. This electrical connection element 7 ensures electrical continuity between the row of tubes 4 and the perforated plate 6.

In relation to FIGS. 3 and 4, showing a possible example of the invention, the electrical connection element 7 consists of a clip 7 formed by:

a first section 71 in the shape of an inverted U which is positioned astride the upper flange 62 of the perforated plate 6;

a second V-shaped section 72, of which a branch 75 is connected to the first section 71, and whose free branch 74 consists of a flexible blade 74 bearing against the outer wall of the tube 4.

More specifically, the angle of the V is dimensioned so that the flexible blade

74 exerts sufficient pressure on the tube 4 so that the electrical contact is properly established.

The first section 71 and the second section 72 of the clip 7 comprise a branch

75 in common.

The free end of the first section 71 is provided with a shoulder 73 directed towards the inside of the staple 7, and dimensioned so as to be able to penetrate inside a perforation 61 of the perforated plate 6 so as to ensure an elastic engagement of the staple 7 in the plate 6.

Any other form of clip 7 may be considered. The invention is not limited to this precise form of staple 7. In particular, it is possible to envisage an electrical connection element in the form of a pin fixed to the plate 6 and to the tube 4 via orifices, or else a connecting element consisting of a part clipped into a groove formed in the plate 6. In general, the connecting element can take any possible shape, as long as it connects the plate 6 to the tube 4 by providing a electrical continuity.

This electrical connection element is made of a metallic material.

The grounding circuit passes through this electrical connection element and then through the perforated plate 6.

The grounding circuit then continues through a metal bar 9, for example made of aluminum, steel or brass, passing over the entire electronic card 1 1 along its axis of symmetry, as is particularly visible in Figure 5. This bar 9 extends orthogonally perforated plate 6.

The bar 9 comprises: A first end 91 fixed to the perforated plate 6

A central portion 94 extending on the electronic card 1 1

• a second free end 92 and connected to a grounding stud 10.

More specifically, the first end 91 consists of a paw perpendicular to the central portion 94. It is fixed by welding for example to a central tab 64 extending from the body 63 perforated plate 6. It can be fixed by any other means to ensure electrical continuity between the perforated plate 6 and the bar 9.

More specifically, the second end 92 has an orifice in which is bolted the stud 10 of grounding. The bar 9 has a shoulder 93 located just upstream of the second end 92.

The grounding circuit thus ends at the pad 10. In the case of a motor vehicle, for example, this pad 10 will be connected to the vehicle body, which is the reference grounding.

The grounding circuit can also take the opposite path, that is to say passing through the pad, the bar, the plate, the staple, then the row of tubes / fins / intermediate bars.

Advantageously, this bar 9 is overmolded in the protective housing 8, as shown in FIG. Such overmoulding also makes it possible to position the bar 9 at a distance from the electronic card 1 1 in order to avoid any contact with the components of the card 1 1.

In particular, the central portion 94 and the second end 92 of the bar 9 are entirely embedded in the material of the protective housing 8. The first end 91 in turn is flush with the housing 8. There is a top plastic layer and a lower plastic layer belonging to the protective housing 8 and sandwiching the bar 9.

The bar 9 thus consists of an insert, serving in particular to stiffen the housing 8. Thus, in addition to its function of grounding, the bar 9 has a consolidation function of the housing 8.

The stud 10 protrudes from the housing 8 of protection, in order to be accessible for its connection with the ground. In this way, there is no particular wiring to be performed within the heating device 1 to achieve the grounding of the metal elements. All the metal elements of the heating device 1 come into contact with each other, in series, so as to form a single ground circuit passing through the heating device 1.

The invention also relates to an air conditioning unit comprising a heating device 1 as described above. Said air conditioning unit comprises a circulation body of the air flow inside which said heating device 1 is located.

With respect to the above description, the optimal dimensional relationships for the parts of the invention, including variations in size, materials, shapes, function and modes of operation, assembly and use are considered apparent and obvious to those skilled in the art, and all relationships equivalent to what is illustrated in the drawings and what is described in the specification are intended to be included in the present invention.

Claims

claims

1. Heating device 1 for an air conditioning unit, said heating device 1 comprising a heating body 2 fed with current to heat a flow of air passing through said heating body 2, the heating body 2 comprising heating elements traveled. by said current and being located in tubes 4 electrically insulated from the heating elements, said heating elements being controlled via a distribution unit 3, the heating device 1 comprising means for grounding a plurality of metal elements distributed in the heating body 2 and the distribution unit 3,

characterized in that said grounding means consist of a single grounding circuit traversing the heating body 2 and the distribution unit 3 and formed by placing said metal elements in series by direct contact between said elements metal.

2. Heating device 1 according to the preceding claim, characterized in that the distribution unit comprises a metal plate 6 of heat dissipation, through which passes the ground circuit.

3. Heating device 1 according to the preceding claim, characterized in that it comprises an electrical connection element 7 between the heating body 2 and said plate 6.

4. Heating device 1 according to the preceding claim, characterized in that the tubes 4 are electrically connected to each other via heat sinks 13 which are electrically conductive, the ground circuit passing successively by these tubes 4 and these dissipators 13.

5. Heating device 1 according to one of claims 3 to 4, characterized in that said electrical connecting element 7 is disposed between the plate 6 and a tube 4, or between the plate 6 and a heat sink 13, or between the plate 6 and a metal cheek in contact with at least one heat sink 13, or between the plate 6 and any other conductive element of the heating body 2, or between the plate 6 and any other conductive element and electrically connected to the heating body 2.

6. Heating device 1 according to the preceding claim, characterized in that said electrical connecting element 7 consists of a staple 7 with flexible blade 74 adapted to provide electrical continuity between said plate 6 and the heating body 2.

7. Heating device 1 according to the preceding claim, characterized in that the clip 7 comprises a first section 71 adapted to hook on a flange 62 of the plate 6, and a second section 72 with the flexible blade 74 in support on the heater 2.

8. Heating device 1 according to the preceding claim, characterized in that said plate 6 consists of a perforated plate 6, the first section 71 of the clip 7 having a free end on which is formed a shoulder 73 to fit into a perforation 61 of the plate 6, ensuring an elastic interlocking of the clip 7 in the plate 6.

9. Heating device 1 according to the preceding claim, characterized in that the second section 72 has a V shape with a branch 75 connected to the first section 71 and a free branch 74 corresponding to said flexible blade 74 adapted to deform by reducing the angle of the V in order to exert a constant pressure against the heating body 2.

10. Heating device 1 according to claim 5, characterized in that said electrical connecting element 7 consists of a metal pin passing through an orifice provided for this purpose in said plate 6, said pin being adapted to provide electrical continuity between said plate 6 and the heating body 2.

1 1. Heating device 1 according to claim 5, characterized in that said electrical connecting element 7 consists of a metal part fixed on the one hand to said heating body 2 by welding or by any other technique ensuring electrical continuity between the heating body 2 and the metal part, and secondly to said plate 6 by elastic interlocking in a groove provided for this purpose in the plate 6.

12. Heating device 1 according to one of claims 2 to 1 1, characterized in that the distribution unit 3 comprises an electronic control card 1 1 on which are attached components 12 releasing heat, said plate 6 being in contact with these components 12.

13. Heating device 1 according to claim 4, characterized in that the heat sinks 13 of the fins type extend from the tubes 4 and touch between two adjacent tubes 4.

14. Heating device 1 according to one of claims 2 to 13, characterized in that said plate 6 is connected, via a metal connecting rod 9 through the distribution unit 3, to a grounding stud arranged at the input of the distribution unit 3.

15. An air conditioning unit comprising a heater 1 according to any one of the preceding claims.