FR3083952A1 - HEATING UNIT, ELECTRIC HEATING RADIATOR AND ASSOCIATED AIR CONDITIONING UNIT - Google Patents

Abstract

The invention relates to a heating unit (10) comprising a plurality of heating elements (14) intended to generate heat when they are traversed by an electric current, said heating unit (10) further comprising a first and second electrodes (17, 18) in electrical connection with the heating elements (14) for establishing said current in said heating elements (14), at least some of the heating elements (14) being distributed in a plurality of heating rows (13).

Description

Field of the invention

The present invention relates to a heating unit, a heating radiator comprising such a heating unit and an air conditioning unit equipped with such a heating radiator. It will find its applications, in particular, in the field of motor vehicles.

State of the art

Electric heating radiators are known which are intended to be integrated into vehicle air conditioning units. These are either additional radiators, combined with heating radiators through which a heat transfer fluid flows, in vehicles with an internal combustion engine, or main radiators, in electric or hybrid vehicles.

Such radiators include a heating body accommodating heating units, provided with heating elements intended to generate heat when they are traversed by an electric current. The heating elements are conventionally located one after the other and are in the form of a heating row. Such heating units are separated from each other by fins capable of dissipating the heat generated by the heating elements and are intended to be brought into contact with an air flow passing through the radiator to heat said air flow. .

Said heating units comprise electrodes in electrical connection with connection faces of the heating elements so as to allow restoration of the current in the row of heating elements once the electrodes are respectively brought to different electrical potentials.

Conventionally, the heat generated is maximum at the heating elements and then decreases as we approach the dissipating fins.

However, heat exchangers fitted with such heating units do not always have good thermal performance.

Unexpectedly, the applicant has found that by interposing a plurality of heating rows between the electrodes of each heating unit instead of a single row of heating elements, it was possible to substantially improve thermal performance.

Also, the invention relates to a heating unit comprising a plurality of heating elements, intended to generate heat when they are traversed by an electric current, said heating unit further comprising first and second electrodes in connection electric with the heating elements for restoring said current in said heating elements, at least some of the heating elements being distributed in a plurality of heating rows.

There is thus a heating unit with improved thermal performance, in particular a heating unit in which the distribution of the heating elements can be better adapted to possible disparities in the flow of fluid to be heated along the element. heating. Indeed, using a plurality of rows rather than a single row makes it possible to diversify the distribution of the heating elements in the heating unit.

According to other characteristics of the invention which can be taken together or separately:

- some of the heating elements are transverse and extend perpendicular to the heating rows;

- said transverse heating elements extending from one longitudinal edge of one electrode to the other;

- transverse heating elements are, for example regularly, interposed between the heating elements of the heating rows, said heating rows being discontinuous;

- The heating elements are substantially regularly spaced from each other;

- said heating rows include a first heating row and a second heating row;

- The heating elements of said first and second heating rows are located opposite one another;

- The heating elements of said first and second heating rows are staggered;

- According to a first variant, a volume defined between the electrodes and said heating elements is empty;

- According to a second variant, a volume defined between said first and second electrodes and said heating elements is filled with an electrically insulating material;

- Said volume comprises main flow zones allowing a direct injection and flow of the material and secondary flow zones allowing an indirect flow of the material coming from the main flow zones;

- the secondary flow zones are oriented substantially perpendicular to the main flow zones;

- the secondary flow zones are oriented substantially parallel to the main flow zones;

- The secondary flow zones are separated from said main flow zones by at least one crossing point at which the flow path of the material is modified;

- Said crossing point is located at the junction of several heating elements and / or heating rows;

- the material is thermally conductive.

The invention also relates to a heating radiator comprising one or more heating units as described above.

The invention further relates to an air conditioning unit comprising the above-mentioned heating radiator.

Advantageously, said air conditioning unit can further comprise a fluid flow circuit, said heating radiator being positioned in said circuit so that said radiator heats said fluid when said radiator is in operation, the radiator having a or first zones and one or second zones, the fluid flow being intended to be higher at the level of the first zone or zones, said heating rows being configured so that a density of heating elements is reinforced at the first zone (s) and limited to the level of the second zone (s).

Presentation of the figures

Other objects and characteristics of the invention will appear more clearly in the description which follows, given with reference to the appended figures, in which:

- Figure 1 schematically illustrates, in front view, a heating radiator according to the invention;

FIG. 2 illustrates schematically and simplified, in perspective, a heating unit according to the invention,

- Figures 3a to 3c, 4a to 4 ^e and 5a to 5c illustrate schematically, in front view, heating units according to the invention.

detailed description

Referring to Figure 1, the invention relates to an electric heating radiator. It is, for example, a heating radiator, said to be high voltage, that is to say intended to be supplied by direct current (DC) or alternating current (AC) having an electrical voltage greater than 60 V, in particular between 60 and 1000 V, more particularly between 180 and 600 V, and / or allowing a heating power to be released on the air or a consumed electric power greater than 2 kW, in particular between 2 kW and 10 kW.

As a variant, it may also be a low-voltage heating radiator, in particular 12 or 48 V.

Said heating radiator comprises, for example, a heating body 1 supplied with electric current to heat a fluid, in particular an air flow F (FIG. 2), passing through said heating body 1.

Said heating body 1 here has a substantially parallelepiped configuration, extending on the surface. It is intended to be positioned transversely to the air flow F to be heated. More specifically, said air flow is intended to be oriented perpendicular to said heating body 1, that is to say perpendicular to the plane of Figure 1.

The heating body 1 comprises heating units 10, extending horizontally in the figure. Said heating body 1 may also include heat sinks 8, for example fins, in thermal contact relation with the heating units 10. The heatsinks 8 are positioned, in particular, between said heating units 10 in the stacking direction , illustrated by the arrow marked X. Said heating body further comprises here a frame 2, in particular of plastic material, accommodating and holding said heating units 10 and / or the heat sinks 8. The air flow F passes between the heating units 10, through the heatsinks 8.

Preferably, the heating radiator further comprises a unit 3 for distributing and / or controlling the current flowing in said heating body 1. Said unit 3 for distributing and / or controlling is advantageously configured to control the current supplying the body of heater 1, in particular the different heater units 10, for example using piloted switches, making it possible to respectively control the flow of current in each of the heater units 10. These are, in particular, transistors, for example of the MOSFET or IGBT type, operating in particular by pulse width modulation.

As illustrated in FIG. 2, the heating units 10 comprise a plurality of heating elements 14. Said heating elements 14 are intended to generate heat when they are traversed by an electric current. The said heating element (s) 14 are, for example, PTC effect resistors (for positive temperature coefficient).

The heating elements 14 advantageously have a first and a second face 147, 148, called connection faces, intended to be brought to different electrical potentials for the establishment of said current in said heating elements 14.

The heating unit 10 further comprises a first electrode 17, intended to be brought to a first potential, and a second electrode 18 intended to be brought to a second potential. These are, for example, metallic electrodes. The heating elements 14 are interposed between said first and second electrodes 17, 18.

More specifically, the first electrode 17 is in electrical connection with the first connection face 147 of the heating elements 14 and the second electrode 18 is in electrical connection with the second connection face 148 thus allowing the circulation of current in the element or elements heating 14 when the first and second electrodes 17, 18 are supplied. For this, the first and second electrodes 17, 18 are preferably connected to said distribution and / or control unit 3 (illustrated in FIG. 1). Said heating elements 14 are advantageously electrically connected in parallel between the electrodes 17, 18.

Advantageously, said connection faces 147, 148 are opposite and substantially parallel. The connection faces 147, 148 are substantially planar. The electrodes 17, 18 are substantially planar, mutually parallel and parallel to the connection faces 147, 148.

Preferably, said heating elements 14 further comprise one or more lateral flanges 146 connecting said first and second connection faces 147, 148. The lateral flanges 146 here form the thickness of the heating elements 14 and determine the spacing between the electrodes 17 , 18, except to take into account the thickness of any electrically insulating and thermally conductive insulating films which can be interposed between the heating elements 14 and the electrodes. Said edges are straight, that is to say generated by a straight line, here they are planar, and perpendicular to the first and second connection faces 147, 148.

Each heating unit 10 advantageously comprises a tube (not illustrated in FIG. 2) made of a thermally conductive material inside which the said heating element or elements 14, said first electrode 17 and / or said second electrode 18 are located for them. electrically insulate from the outside tube. The tubes are preferably in contact with the dissipators 8.

Said heating units 10 also include layers of material (not shown), electrically insulating and thermally conductive, said layers of material being located between each of the electrodes 17, 18 and one of the walls of the tube. In this way, the tube is electrically isolated from the electrodes 17, 18 and the heating elements 14 but thermally in relation to them.

According to the invention, the heating elements 14 are distributed in a plurality of heating rows 13, here two in number. However, it is not necessary for all the heating elements 14 of a heating unit 10 to be distributed in heating rows 13. The heating rows 13 are positioned adjacent to each other in a transverse direction Z, perpendicular to the direction of the stack X of the tubes, that is to say in the direction of propagation of the air flow F.

Preferably, the heating rows 13 are substantially regularly spaced from one another by a distance d2. However, the distance d2 between two neighboring heating rows 13 can vary within the same heating unit 10, or even from one heating unit 10 to another within the same heating radiator. Preferably, the distance d2 between two heating rows 13 is at least equal to 2 mm, in particular to facilitate overmolding or to take account of manufacturing uncertainties.

The heating elements 14 according to the invention are therefore arranged in a two-dimensional arrangement. In other words, the heating elements 14 are distributed in two directions, along the longitudinal direction Y of the tube and along the transverse direction Z of the tube.

The two-dimensional arrangement of the heating elements 14, in particular in a plurality of heating rows 13 is particularly advantageous. In fact, it is generally expected that the air flow passing through the heating radiator is constant along the heating body 1. However, certain heating conditions and / or certain configurations of the circuits inside which the flow d he air to be heated leads to the establishment of a variable flow from one zone to another of the heating radiator. The two-dimensional arrangement of the heating elements 14 within the heating unit 1 makes it possible to adapt the density of heating elements 14 to such differences in flow rate.

For example, the heating radiator could have one or more first zones and one or more second zones, for which the fluid flow rate is intended to be higher at the level of the first zone or zones.

The term "zone" is intended to mean a portion of the heating radiator intended to heat the air flow F passing through said zone in a substantially homogeneous manner. In other words, a zone delimits a portion of the heating radiator in which the heating elements 14 have substantially the same arrangement and the same density of presence, independently of the row (s) of heating 13 and the (s) heating unit (s) 10 to which these heating elements 14 belong.

Still according to the previous example, said heating rows 13 can be configured so that the density of heating elements 14 is reinforced at the level of the first zone or zones and limited at the level of the second zone or zones. A heating radiator is thus obtained in which the heating of the fluid is adapted to the flow rate of said fluid. As will be described in the following sections, the density of heating elements 14 between said first zone (s) and said second zone (s) can be changed by adjusting the position and / or number and / or orientation of the heating elements 14, in particular on the surface of the electrodes.

It is also possible to use heating elements having different intrinsic characteristics so as to vary their thermal performance, in particular from one element to another and / or from one row to another.

A volume 15 defined between the electrodes 17, 18 and the heating elements 14 can be left empty, that is to say that said volume is filled with air. This volume 15 is likely to vary on the one hand as a function of the distance between the electrodes, of the spacing di between the heating elements 14 and of the spacing d2 between the heating rows 13.

FIG. 3a illustrates a heating unit 10 according to the invention. The heating unit 10 is seen in section. As a result, electrode 18, opposite electrode 17, is not apparent. Said first and second heating rows 13a, 13b here comprise the same number of heating elements 14a, 14b. However, it is not excluded that this number may vary from one heating row 13 to another or from one heating unit 10 to another.

Preferably, within the same heating row 13, the heating elements 14 are substantially aligned with respect to each other in a longitudinal direction Y perpendicular to the stacking direction X within each heating row 13.

According to a first aspect of the invention, within a same heating row 13, the heating elements 14 are substantially regularly spaced from each other. In other words, the spacing di between the heating elements 14 is preferably constant along the heating row 13. However, the distance di between the heating elements 14 can vary from one heating unit to another within from the same heating radiator. That said, this distance di is at least equal to 2 mm, in particular to facilitate overmolding or to take account of manufacturing uncertainties.

For example, as illustrated in FIG. 3b, the spacing di between the heating elements 14 of the heating unit 10 is reduced in comparison with the heating unit 10 of FIG. 3a (to the left of the dividing line AA). By decreasing the spacing between the heating elements 14, the density of heating elements 14 is increased. Conversely, it is also possible to increase the spacing di between the heating elements 14 to decrease the density d 'elements (to the right of the dividing line AA). Preferably, the spacing di between the heating elements 14 is at least equal to 2 mm, in particular to facilitate overmolding or to take account of manufacturing uncertainties. Preferably, the heating elements 14 located at the ends of the heating rows 13 are separated by a distance ds at least equal to 2 mm relative to the edges at the longitudinal ends of the electrodes 17, 18 so as not to limit the passage of the flux of air, which would limit the heating efficiency.

Furthermore, as can still be seen in FIG. 3b, the heating unit 10 comprises a third heating row 13c, adjacent to the second heating row 13b. The third heating row 13c here has the same characteristics as said first and second heating rows, that is to say that the number of heating elements 14 is equal to the number of heating elements

14a and 14b and that the spacing di between the heating elements 14c is identical to that between the heating elements 14a and 14b respectively. In the illustrated configuration, although the density of heating elements 14 does not vary, the number of heating elements 14 capable of heating the fluid increases.

According to a first variant of the invention illustrated in FIG. 3c, the heating elements 14a, 14b of said first and second heating rows 13a, 13b are staggered, that is to say that the heating elements 14a, 14b are offset longitudinally from each other. In other words, the lateral edges 146 of said heating elements 14a of the first heating row 13a are offset longitudinally with respect to the heating elements 14b of the second heating row 13b.

According to a second variant of the invention illustrated in FIG. 4a, some of the heating elements 14 'are transverse and extend perpendicular to the heating rows 13, said transverse heating elements 14' extending substantially from a longitudinal edge to the other of an electrode. In other words, the largest dimension of the heating element 14 'corresponds approximately to the width of the electrodes 17, 18. Preferably, said transverse heating elements 14' have the same dimensions as the heating elements 14, or even are identical to these.

This second variant of the invention is available in several configurations.

In the example illustrated in FIG. 4a, the transverse heating elements 14 ’are located at the ends of the heating unit 10 and delimit said first and second heating rows 13a, 13b.

In the configuration illustrated in FIG. 4b, a transverse heating element 14 ’is regularly interposed between the heating elements 14a and 14b of said heating rows 13a, 13b. Said heating rows 13a, 13b are therefore discontinuous. More specifically, here, the number of successive heating elements 14a per portion of heating row 13a is two. It is the same for the heating elements 14b of the heating row 13b. The number of heating elements 14 per portion of heating row 13 can also vary.

Indeed, as illustrated in FIGS. 4c and 4d, the number of successive heating elements 14 within the same row 13 is one or three respectively. These exemplary embodiments are not limiting.

In the configuration illustrated in FIG. 4e, a plurality, here two transverse heating elements 14 ’are regularly interposed between the heating elements 14a and 14b of said heating rows 13a, 13b. However, whatever the number of transverse heating elements 14 interposed along the heating rows 13, the distribution of said heating elements 14 advantageously responds to a two-dimensional arrangement.

According to another aspect of the invention, the volume 15 defined between said first and second electrodes 17, 18 and said heating elements 14 is filled with an electrically insulating material 20. The use of material 20 makes it possible to limit the risk of establishing a short-circuit current along the surfaces of the heating elements 14 located between the first and second electrodes, from one electrode to the other.

Preferably, the material 20 is thermally conductive. This ensures efficient conduction of the heat generated by the heating elements 14.

The distribution of the heating elements 14 into a plurality of heating rows is particularly advantageous for filling the volume 15 in this variant of the invention. Indeed, the two-dimensional arrangement of the heating elements 14 facilitates the injection of the material 20 along the heating elements 14 and / or the heating rows 13, by a single or a limited number of injection points.

As can be seen more clearly in FIG. 5a, the volume 15 comprises main flow zones 30 allowing direct injection and flow of the material 20. These main flow zones 30 are located between the heating elements 14 along heated rows. In other words, they are located along the side edges 146 of the heating elements.

After its injection into the main flow zones 30, the material 20 can continue to flow by indirect flow in secondary flow zones 32. This indirect flow in the secondary zones 32 is preferably carried out along the edges of the elements of heats 14 so that the entire gap between the electrodes 17, 18 is completely filled.

Also advantageously, the spacing di left between the heating elements 14 of a heating row and the distance d2 left between the heating rows 13, which as a reminder are at least 2 mm promotes this type of flow, by capillarity or other.

Certain secondary flow areas 32 are oriented substantially perpendicular and / or parallel to the main flow areas 30. These are in particular the secondary flow areas 32 separated from said main flow areas 30 by a crossing point 34, illustrated by arrows intercepting at a point at the mouth of the main zones 30. These are also the secondary flow zones 32 separated from the main flow zones by several crossing points 34.

It is thus understood that the method of injecting the material 20 into the volume 15 is facilitated because the number of injection points is reduced compared to a heating unit 10 which would have a single heating row. Indeed, in such a heating unit, it would then be necessary to apply the material between each heating element. For example, the reduction factor can be halved by considering that the material 20 is capable of crossing two successive crossing points 34.

As illustrated in FIGS. 5b and 5c, the presence of transverse heating elements 14 ’does not call into question the significant advantage provided by the two-dimensional arrangement of the heating elements with regard to this injection process. Indeed, the number of injection points remains reduced compared to a heating unit 10 which would include a single heating row 13.

Claims (14)

1. A heating unit (10) comprising a plurality of heating elements (14), intended to generate heat when they are traversed by an electric current, said heating unit (10) further comprising a first and a second electrodes (17, 18) in electrical connection with the heating elements (14) for establishing said current in said heating elements (14), at least some of the heating elements (14) being distributed in a plurality of rows heating (13). 2. Heating unit (10) according to claim 1, wherein the heating elements (14) are substantially regularly spaced from each other. 3. Heating unit (10) according to claim 1, wherein said heating rows (13) comprise a first heating row (13a) and a second heating row (13b). 4. Heating unit (10) according to claim 3, wherein the heating elements (14a, 14b) of said first and second heating rows (13a, 13b) are located opposite each other and / or in a staggered arrangement. 5. Heating unit (10) according to any one of the preceding claims, in which some of the heating elements (14 ') are transverse and extend perpendicular to the heating rows (13), said heating elements (14') transverse extending from one longitudinal edge to the other of an electrode. 6. Heating unit (10) according to claim 5, in which transverse heating elements (14 ’) are interposed between the heating elements (14) of the heating rows (13), said heating rows (13) being discontinuous. 7. Heating unit (10) according to any one of the preceding claims, in which a volume (15) defined between the electrodes (17, 18) and said heating elements (14) is empty. 8. Heating unit (10) according to any one of claims 1 to 6, in which a volume (15) defined between said first and second electrodes (17, 18) and said heating elements (14) is filled with a electrically insulating material (20). 9. A heating unit (10) according to claim 8, in which said volume (15) comprises main flow zones (30) allowing a direct injection and flow of the material (20) and secondary flow zones ( 32) allowing an indirect flow of the material (20) coming from the main flow zones (30). 10. Heating unit (10) according to claim 9, in which the secondary flow zones (32) are oriented substantially perpendicular and / or parallel to the main flow zones (30) and separated from said main flow zones ( 30) by at least one crossing point (34) at which the material flow path (20) is modified, said crossing point (34) being located at the junction of several heating elements (14) and / or heated rows (13). 11. Heating unit (10) according to one of claims 8 to 10, in which the material (20) is thermally conductive. 12. Heating radiator comprising one or more heating units (10) according to any one of the preceding claims. 13. Air conditioning unit comprising a heating radiator according to the preceding claim. 14. Air conditioning unit according to claim 13, comprising a fluid flow circuit, said heating radiator being positioned in said circuit so that said radiator heats said fluid when said radiator is in operation, the radiator having one or more first zones and one or more zones, the fluid flow rate being intended to be higher at the level of the first zone or zones, said heating rows (13) being configured so that a density of heating elements ( 14) is reinforced at the level of the first zone (s) and limited to the level of the second zone (s).