FR3103887A1 - Electric heating device for a heat transfer liquid for a motor vehicle - Google Patents

Abstract

The present invention relates to an electric heating device (1) of a heat transfer liquid for a motor vehicle, said electric heating device (1) comprising a housing delimiting: at least one heating chamber (3) inside which is intended to circulate the heat transfer liquid and in which extends at least one electric heating element (31), a housing (5) within which is arranged a printed circuit (51) electronic management, said printed circuit (51) comprising at at least one transistor (53), the housing (5) comprising a base (55) in contact with the heating chamber (3), the at least one transistor (53) being in contact with said base (55). The present invention also relates to the method of manufacturing such an electric heating device (1).

Description

Device for electric heating of a heat transfer liquid for a motor vehicle

The field of the present invention is that of electrical devices for heating and circulating a heat transfer liquid, in particular for a ventilation, heating and/or air conditioning installation for the passenger compartment of a motor vehicle. More particularly, the invention relates to electric heating devices used for such installations in motor vehicles, electric or hybrid, equipped with a high-voltage power supply network.

The heating of the air intended for the heat treatment of the passenger compartment of a motor vehicle with combustion engine is ensured by heat exchange between a flow of air and a heat transfer liquid, by means of a radiator. In the case of hybrid or electric vehicles, electric heating devices are known which form a heat source and in which a generally high-voltage electric current circulates to raise the temperature of an electric heating element on board this heating device. The heat transfer liquid to be heated thus passes through the electric heating device and is brought into contact with the electric heating element, an exchange of heat energy then takes place between the electric heating element and the heat transfer liquid. This heat transfer liquid then passes through the radiator located within the ventilation, heating and/or air conditioning system in order to heat the air flow to the passenger compartment.

The electrical heating element usually consists of electrical heating means, for example one or more heating resistors. In order to power and control such an electric heating element, the electric heating device generally comprises an electronic control printed circuit. This electronic printed circuit generally comprises at least one control transistor for the power electronics. Nevertheless, due to the compactness of the electrical heating device and the voltage applied, the transistors tend to heat up strongly and can switch to safety mode if a maximum temperature is reached. In safety mode, the power supply is cut off in order to prevent deterioration of the transistor by heat and also in order to lower its temperature. The heating of the heat transfer liquid is also interrupted.

The object of the present invention is therefore to remedy at least partially the drawbacks of the prior art and to propose an improved electric heating device and allowing the regulation of the temperature of the transistors within it.

• au moins une chambre de chauffe à l’intérieur de laquelle est destiné à circuler le liquide caloporteur et dans laquelle s’étend au moins un élément électrique chauffant,
• un logement au sein duquel est disposé un circuit imprimé électronique de gestion, ledit circuit imprimé comportant au moins un transistor,

le logement comportant un fond au contact de la chambre de chauffe, l’au moins un transistor étant au contact dudit fond.The present invention therefore relates to a device for electric heating of a heat transfer liquid for a motor vehicle, said electric heating device comprising a housing delimiting:

• at least one heating chamber inside which the heat transfer liquid is intended to circulate and in which extends at least one electric heating element,
• a housing within which is arranged an electronic management printed circuit, said printed circuit comprising at least one transistor,

the housing comprising a bottom in contact with the heating chamber, the at least one transistor being in contact with said bottom.

According to one aspect of the invention, the heating chamber has a cylindrical profile, the bottom of the housing extending tangentially to said heating chamber.

According to another aspect of the invention, the housing comprises, on one of its outer surfaces, fins at the location of the at least one transistor, said fins connecting the outer surface of the heating chamber with a portion from the bottom of the housing.

According to another aspect of the invention, the bottom of the housing comprises a thermally conductive layer on which the at least one transistor rests.

According to another aspect of the invention, the housing comprises a holding element configured to press the at least one transistor against the bottom of the housing.

According to another aspect of the invention, the holding element comprises an elastic element pressing against the at least one transistor.

According to another aspect of the invention, the printed circuit extends parallel to the bottom of the housing, the at least one transistor being arranged between the printed circuit and the bottom of the housing.

According to another aspect of the invention, the at least one transistor comprises electrical connectors connecting one of the sides of the transistor to the printed circuit, said connectors comprising an inflection bend.

• au moins une chambre de chauffe à l’intérieur de laquelle est destiné à circuler le liquide caloporteur et dans laquelle est destiné à s’étendre au moins un élément électrique chauffant,
• un logement comportant un fond au contact de la chambre de chauffe,

ledit procédé comportant les étapes suivantes:

• positionnement d’au moins un transistor dans le logement de sorte qu’il soit au contact du fond dudit logement,
• positionnement d’un circuit imprimé dans le logement de sorte que l’au moins un transistor soit disposé entre le fond du logement et ledit circuit imprimé,
• connexion électrique au moyen de connecteurs entre le circuit imprimé et l’au moins un transistor.

The present invention also relates to a method of manufacturing a device for electric heating of a coolant for a motor vehicle, said electric heating device comprising a housing delimiting:

• at least one heating chamber inside which the heat transfer liquid is intended to circulate and in which at least one electric heating element is intended to extend,
• a housing comprising a bottom in contact with the heating chamber,

said method comprising the following steps:

• positioning at least one transistor in the housing so that it is in contact with the bottom of said housing,
• positioning a printed circuit in the housing so that the at least one transistor is placed between the bottom of the housing and said printed circuit,
• electrical connection by means of connectors between the printed circuit and the at least one transistor.

According to another aspect of the method according to the invention, said method comprises an additional step of positioning a holding element configured to press the at least one transistor against the bottom of the housing, said step being carried out between the step of positioning the at least one transistor and the step of positioning the printed circuit.

Other characteristics and advantages of the present invention will appear more clearly on reading the following description, provided by way of illustration and not limitation, and the appended drawings in which:

Figure 1a is a schematic representation in perspective of an electric heating device,

Figure 1b is a schematic representation in exploded perspective of the electric heating device of Figure 1a,

Figure 2 is a schematic representation in perspective of the printed circuit of the electric heating device,

Figure 3 is a schematic representation in perspective and in section of an electric heating device,

Figure 4 is a schematic representation in top view of an electric heating device,

Figure 5 is a flowchart of a method of manufacturing an electric heater.

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

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

In the present description, it is possible to index certain elements or parameters, such as for example first element or second element as well as first parameter and second parameter or else first criterion and second criterion, etc. In this case, it is a simple indexing to differentiate and name elements or parameters or criteria that are close, but not identical. This indexing does not imply a priority of one element, parameter or criterion over another and it is easy to interchange such denominations without departing from the scope of the present description. Nor does this indexing imply an order in time, for example, to assess such and such a criterion.

Figures 1a and 1b show a schematic representation in perspective of an electric heating device 1 respectively in assembled view and in exploded view.

The electric heating device 1 comprises a casing delimiting at least one heating chamber 3 inside which the heat transfer liquid is intended to circulate. More specifically, the heating chamber 3 comprises a cavity 32 within which the heat transfer liquid enters and leaves the heating chamber 3 at the level of connection end pieces 3a opening out into said cavity 32. In FIGS. 1a and 1b, only a connection end piece 3a, for example, an outlet is shown. The heating chamber 3 also includes another inlet connection end piece (not shown).

Within this heating chamber 3 extends at least one electric heating element 31 intended to heat the heat transfer liquid. This electrical heating element 31 may for example comprise one or more electrical resistors and having a helical profile and intended to come into contact with the heat transfer liquid. The electric heating element 31 closes in particular the heating chamber 3 and more precisely the cavity 32 so that the heat transfer liquid can only circulate from one inlet connection end piece to an outlet connection end piece 3a.

The electric heating device 1 may also include an extension 4 of the heating chamber 3, allowing access to the electrical connectors of the electric heating element 31. This extension 4 can be closed by means of a cover 41. The liquid coolant does not circulate in this extension 4.

The electric heating device 1 also comprises a housing 5 within which is arranged a printed circuit 51 electronic management. This housing 5 may in particular comprise a cover 52 which closes it. The housing 5 also includes electrical connectors 50 allowing the electrical supply of the printed circuit 51, generally in low voltage current (for example from 12 to 48 V), and also of the electric heating element 31, generally in high voltage current ( for example that can go beyond 500 V for an electric vehicle).

As shown in more detail in Figure 2, the printed circuit 51 includes at least one transistor 53, here four. These transistors 53 may in particular be Insulated Gate Bipolar Transistor (IGBT).

As illustrated in the sectional view of Figure 3, the housing 5 has a bottom 55 in contact with the heating chamber 3. This bottom 55 is generally flat. The transistors 53 of the printed circuit are arranged in contact with said bottom 55. This arrangement of the transistors 53 allows them to be cooled by means of the heat transfer liquid circulating in the heating chamber 3 by thermal diffusion through the bottom 55. Indeed, the maximum temperature of the heat transfer liquid is generally of the order of 90°C whereas the safety temperature at which the transistors 53 go into safety is of the order of 120°C. In order to allow good thermal conduction, the bottom 55 of the housing 5 may in particular have a thickness of the order of 2.5 mm.

According to the example illustrated in Figures 1a to 3, the heating chamber 3 has a cylindrical external profile. Likewise, the cavity 32 inside which the heat transfer liquid circulates is also cylindrical. The connection end pieces 3a are arranged at one end of the heating chamber 3 and the extension 4 through which the electric heating element 31 is inserted is arranged at the opposite end. The bottom 55 of the housing 5 extends tangentially to the heating chamber 3.

It is however quite possible to imagine other shapes for the heating chamber 3, for example parallelepipedic, without departing from the scope of the present invention.

The casing of the electric heating device 1 may also comprise, on one of its outer surfaces, fins 33 at the location of the transistors 53. These outer surfaces may in particular correspond to the sides of the casing of the electric heating device 1. These fins 33 connect the outer surface of the heating chamber 3 with a portion of the bottom 55 of the housing 3. In the case where the heating chamber 3 has a cylindrical outer profile, the fins 33 connect the outer surface of the heating chamber 3 with a portion of the bottom 55 of the housing 3 overflowing from the contact zone between the bottom 55 and the heating chamber 3. These fins 33 allow a structural reinforcement of the housing while limiting the increase in the weight of the housing. These fins 33 also allow better cooling of the transistors 53 by thermal conduction.

Still according to the example illustrated in FIGS. 1a, to 3, the printed circuit 51 extends parallel to the bottom 55 of the housing 5. The transistors 53 are then arranged between the printed circuit 51 and the bottom 55 of the housing 5. This particular arrangement allows to have a housing 5 and therefore a compact electric heating device 1.

The transistors 53 comprise electrical connectors 530 (visible in FIG. 2) connecting one of their sides to the printed circuit 51. These connectors 530 may in particular comprise an inflection bend in order to position the transistor 53 parallel to the bottom 55 of the housing 5 and to present a face of the transistor 53 with a sufficient surface for good heat exchange and able to come into contact with the bottom 55 of the housing 5. This bend of inflection can in particular have an angle of 90° when the printed circuit 51 extends parallel to the bottom 55 of the housing 5. In order to avoid the formation of electric arcs, the distance between the inflection bend and the side of the transistor 53 is preferably of the order of 4 mm.

As illustrated in FIGS. 3 and 4, the housing 5 may include one or more holding elements 59 configured to press the transistors 53 against the bottom 55 of the housing 5. These holding elements 59 allow good contact between the transistor 53 and the bottom 55 of the housing 5 in order to improve the thermal conduction between these two elements and therefore allow better cooling of the transistors 53. For this, the holding element 59 comprises an elastic element 590 (visible in FIG. 4) pressing against the transistor 53. This elastic element 590, as in the example illustrated in FIG. 4, is an elastic lamella integral with the holding element 59. The pressure exerted by this elastic element 590 on the transistor 53 can be of the order of 70 N.

The holding element 59 is in particular fixed to the bottom 55 of the housing 5, for example by means of screws as illustrated in FIG. 4. In this figure, a single holding element 59 is shown. This same holding element 59 presses on two transistors 53 by means of two elastic strips 590. A second holding element 59, not shown for the sake of clarity, allows pressing on the other two transistors 53.

As illustrated in FIG. 4, the bottom 55 of the housing 5 comprises a thermally conductive layer 57 on which the transistors 53 rest. This thermally conductive layer 57 makes it possible to absorb the irregularities of the bottom 55 and of the transistors optimal thermal. In addition, the thermally conductive layer 57 provides electrical insulation between the transistors 53 and the bottom 55.

Figure 5 shows a flowchart of a method of manufacturing an electric heating device 1 as described above.

• une première étape 101 de positionnement des transistors 53 dans le logement 5 de sorte qu’ils soient au contact du fond 55 dudit logement 5,
• une deuxième étape 102 de positionnement d’un circuit imprimé 51 dans le logement 5 de sorte que les transistors 53 soient disposés entre le fond 55 du logement 5 et ledit circuit imprimé 51, et
• une troisième étape 103 de connexion électrique au moyen de connecteurs 530 entre le circuit imprimé 51 et les transistors 53.

The process comprises the following steps:

• a first step 101 of positioning transistors 53 in housing 5 so that they are in contact with bottom 55 of said housing 5,
• a second step 102 of positioning a printed circuit 51 in housing 5 so that transistors 53 are arranged between bottom 55 of housing 5 and said printed circuit 51, and
• a third stage 103 of electrical connection by means of connectors 530 between the printed circuit 51 and the transistors 53.

The manufacturing method may also include an additional step 104 of positioning a holding element 59 configured to press the transistors 53 against the bottom 55 of the housing 5. This additional step 104 is carried out between the first step 101 of positioning the transistors 53 and the second step 102 of positioning the printed circuit 51.

Thus, it is clear that due to the positioning of the transistors 53 within the housing, the electric heating device 1 allows good cooling of the latter.

Claims (10)

Device (1) for electric heating of a heat transfer liquid for a motor vehicle, said electric heating device (1) comprising a housing delimiting:

• at least one heating chamber (3) inside which the heat transfer liquid is intended to circulate and in which extends at least one electric heating element (31),
• a housing (5) within which is arranged an electronic management printed circuit (51), said printed circuit (51) comprising at least one transistor (53),

characterized in that the housing (5) comprises a bottom (55) in contact with the heating chamber (3), the at least one transistor (53) being in contact with said bottom (55). Electric heating device (1) according to the preceding claim, characterized in that the heating chamber (3) has a cylindrical profile, the bottom (55) of the housing (5) extending tangentially to the said heating chamber (3) . Electric heating device (1) according to any one of the preceding claims, characterized in that the casing comprises, on one of its outer surfaces, fins (33) at the level of the location of the at least one transistor ( 53), said fins (33) connecting the outer surface of the heating chamber (3) with a bottom portion (55) of the housing (3). Electric heating device (1) according to any one of the preceding claims, characterized in that the bottom (55) of the housing (5) comprises a thermally conductive layer (57) on which the at least one transistor (53) rests. . Electric heating device (1) according to any one of the preceding claims, characterized in that the housing (5) comprises a holding element (59) configured to press the at least one transistor (53) against the bottom (55 ) of the housing (5). Electric heating device (1) according to the preceding claim, characterized in that the holding element (59) comprises an elastic element (590) pressing against the at least one transistor (53). Electric heating device (1) according to any one of the preceding claims, characterized in that the printed circuit (51) extends parallel to the bottom (55) of the housing (5), the at least one transistor (53) being disposed between the printed circuit (51) and the bottom (55) of the housing (5). Electric heating device (1) according to any one of the preceding claims, characterized in that the at least one transistor (53) comprises electric connectors (530) connecting one of the sides of the said transistor (53) to the printed circuit (51 ), said connectors (530) having an inflection bend. Method of manufacturing an electric heating device (1) for a heat transfer liquid for a motor vehicle, said electric heating device (1) comprising a housing delimiting:

• at least one heating chamber (3) inside which the heat transfer liquid is intended to circulate and in which at least one electric heating element (31) is intended to extend,
• a housing (5) comprising a bottom (55) in contact with the heating chamber (3),

said method comprising the following steps:

• positioning of at least one transistor (53) in the housing (5) so that it is in contact with the bottom (55) of said housing (5),
• positioning a printed circuit (51) in the housing (5) so that the at least one transistor (53) is arranged between the bottom (55) of the housing (5) and said printed circuit (51),
• electrical connection by means of connectors (530) between the printed circuit (51) and the at least one transistor (53).

Method of manufacturing an electric heating device (1) according to the preceding claim, characterized in that it comprises an additional step of positioning a holding element (59) configured to plate the at least one transistor (53) against the bottom (55) of the housing (5), said step being performed between the step of positioning the at least one transistor (53) and the step of positioning the printed circuit (51).