EP1698840B1 - PTC heater, especially for a vehicle - Google Patents

Description

The invention relates to a PTC heater, in particular for a motor vehicle, according to the preamble of claim 1.

PTC heaters are known in which PTC elements are arranged between contact plates and glued to them or connected in a mechanical manner.

The document U.S. 5,598,502 discloses the preamble of claim 1.

However, such PTC heaters still leave something to be desired.

It is an object of the invention to provide an improved, cost-effective PTC heater available, in particular, the PTC element can be easily formed.

This object is achieved by a PTC heater with the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

According to the invention, a PTC heater is provided, which has at least one PTC element, which is arranged between two contact plates and electrically conductively connected thereto, wherein at least one contact plate on the side of the PTC elements or at least two differently structured and / or raised Has areas. These regions are also directly opposite the one or more PTC elements, at least in a partial region of the differently structured and / or raised regions. The different structurings of the regions can be formed, for example, by unprocessed regions, surface-deformed regions, deformed regions, coated regions, etched or otherwise processed regions. At least in the first areas a direct contact of the contact plate with the PTC element is provided. The PTC elements may be ceramic PTC elements as well as plastic PTC elements, in particular polymer PTC elements. Between the contact plates and the PTC element, a medium may be provided, for example, adhesive and / or thermal grease.

Characterized in that the contact sheets are attached directly to the PTC elements, for example by means of an adhesive or by means of a mechanical attachment, for example, a thermal paste between the PTC element and contact plate is provided eliminates the need for a coating of the PTC elements with an electrode. However, the PTC element is preferably provided with a coating, for example with a thin metal layer, in particular with a silver layer or a layer of a silver alloy. The contact plate in turn can be soldered to the adjacent corrugated fin sheet in a known manner. Even when using a low-cost, non-electrically conductive adhesive is due to the different heights of the contact plate - whether in the form of surface deformations, for example in the form of knurls, or in the form of a deformation of the contact plate - at least In some areas a direct contact ensured, so that a sufficiently good power transfer and improved heat transfer is possible. Furthermore, a sufficient adhesive layer is ensured on account of the spacing in other areas, so that a sufficiently strong mechanical connection between contact plate and PTC element is ensured.

The first regions, also referred to as contact regions, are preferably spaced from one another by, or surrounded by, or surrounded by second regions, hereinafter also referred to as intermediate regions. In this case, the second regions preferably have approximately the same size, longitudinal and / or width extension as the first regions, which in this case also deviations of up to +/- 20% should be understood. However, deviations of up to +/- 50% or more are possible.

Preferably, three to four first areas are provided in the longitudinal direction of the contact sheets, but more or less first areas are possible depending on the size dimensions and ratios. In this case, the first regions can also be arranged in groups and each extend over only a part of the length of the contact sheets.

In the width and / or the length one to five first areas are preferably provided. In this case, the first regions can also be arranged in a group.

The first regions may be formed by a surface deformation, in particular by a knurling. Even if there is no continuous surface contact in a correspondingly surface-deformed area, the entire area in which contact points is applied or areas, hereinafter referred to as the contact area and thus the first area. The second regions are preferably flat, but surface deformation, for example by embossing or knurling, may also be provided in the second regions, but preferably no direct contact of PTC element and contact plate is present in the second regions. The contact sheet preferably has first and second regions on both sides.

However, the first regions can also be formed by a continuous deformation of the contact sheet in the thickness direction, whereby combinations of surface deformations and deformations are also possible.

The height of the deformation and / or the surface deformation is preferably 0.005 mm to 2 mm, in particular up to a maximum of 1 mm. The height of the deformation and / or the surface deformation is particularly preferably 0.005 mm to 0.04 mm, in particular 0.01 mm to 0.015 mm. The deformation and / or Oberflächenvertormung is introduced in a controlled manner and provided in particular via the contact plate with a constant height.

The deformation preferably has the shape of a rectangle or a rounded rectangle. However, other forms are possible.

The bottom of the deformation is preferably flat, so that - depending on the arrangement - a uniform adhesive film thickness or a uniform contact surface with the PTC element is given.

There are preferably one to three or one to five, in particular four rectangular formations arranged side by side in the direction of the width of the contact sheet.

Arbitrary arrangement of the transformations of any shape is possible, for example, staggered arrangements or irregular arrangements in order to improve the current introduction in certain areas and to improve the mechanical connection in other areas.

Preferably, the contact plate on both sides transformations. Advantageously, the size of the surface, the height and / or the number of transformations on both sides of the contact plate are identical, so that the contact plates can be contacted on both sides with PTC elements.

Between the contact plates and the PTC element advantageously another medium is provided. The contact sheets are preferably bonded to the PTC element by means of an insulating, low cost adhesive such that the price of the adhesive does not significantly add to the cost of manufacture and the application of slightly too much adhesive squeezed laterally between the PTC elements and contact sheets This may also have a short-circuit preventing function, does not matter. In a further variant, the contact sheets can also be connected to the PTC element by means of an electrically conductive and / or thermally conductive adhesive. Alternatively or additionally, a thermal compound may also be applied between the contact sheets and the PTC element.

The PTC element is preferably formed cuboid or plate-shaped, wherein at least the surfaces are flat in the direction of the contact plates. However, manufacturing-related slight surface irregularities may be present.

The surfaces of the PTC element may preferably be coating-free, at least in the direction of the contact sheets, ie it is not Coating process in the context of the production of the PTC element required so that reduce the manufacturing cost thereof. Due to the design of the PTC elements with flat surfaces, however, coatings can also be provided in a simple manner, which is preferably continuous coatings of the greatest possible uniform thickness.

Fig. 1

eine Ansicht eines PTC-Heizers gemäß dem ersten Ausführungsbeispiel,

Fig. 2

eine perspektivische Ansicht eines Kontaktblechs, wie es beim PTC-Heizer von Fig. 1 verwendet wird,

Fig. 3

eine Ansicht des Kontaktblech von Fig. 2 von unten,

Fig. 4

eine Ansicht eines Kontaktblechs gemäß dem zweiten Ausführungsbeispiel,

Fig. 5

einen perspektivisch dargestellten Schnitt durch das Kontaktblech von Fig. 3,

Fig. 6

einen perspektivisch dargestellten Schnitt durch ein Kontaktblech gemäß dem dritten Ausführungsbeispiel,

Fig. 7

einen perspektivisch dargestellten Schnitt durch das Kontaktblech von Fig. 2,

Fig. 8

eine Detailansicht von Fig. 7,

Fig. 9

eine Ansicht eines Kontaktblechs gemäß dem vierten Ausführungsbeispiel,

Fig. 10

eine Ansicht eines Kontaktblechs gemäß dem fünften Ausführungsbeispiel,

Fig. 11

eine Ansicht eines Kontaktblechs gemäß dem sechsten Ausführungsbeispiel,

Fig. 12

eine Ansicht eines Kontaktblechs gemäß dem siebten Ausführungsbeispiel, und

Fig. 13

eine Ansicht eines Kontaktblechs gemäß dem achten Ausführungsbeispiel; und

Fig. 14

einen Schnitt durch ein Kontaktblech gemäß Fig. 9 und;

Fig. 15

eine Schnittdarstellung gemäß Fig. 14 mit beidseitig angeordneten PTC-Elementen.

In the following the invention will be explained in detail by means of embodiments with reference to the drawing. In the drawing show:

Fig. 1

a view of a PTC heater according to the first embodiment,

Fig. 2

a perspective view of a contact plate, as in the PTC heater of Fig. 1 is used,

Fig. 3

a view of the contact sheet of Fig. 2 from underneath,

Fig. 4

a view of a contact plate according to the second embodiment,

Fig. 5

a perspective section through the contact plate of Fig. 3 .

Fig. 6

a perspective section through a contact plate according to the third embodiment,

Fig. 7

a perspective section through the contact plate of Fig. 2 .

Fig. 8

a detailed view of Fig. 7 .

Fig. 9

a view of a contact plate according to the fourth embodiment,

Fig. 10

a view of a contact plate according to the fifth embodiment,

Fig. 11

a view of a contact plate according to the sixth embodiment,

Fig. 12

a view of a contact plate according to the seventh embodiment, and

Fig. 13

a view of a contact plate according to the eighth embodiment; and

Fig. 14

a section through a contact plate according to Fig. 9 and;

Fig. 15

a sectional view according to Fig. 14 with PTC elements arranged on both sides.

A PTC heater 1 according to the first embodiment has a plurality of plate-shaped PTC elements 2 serving as electric heaters. The PTC elements 2 are provided on two opposite sides, each with a thin silver coating. Each of these PTC elements 2 is electrically contacted in the region of the silver coatings by means of two aluminum contact plates 3, which allow Stromzu- and -ableitung, for which a part of the contact plates 3 protrude laterally and are connected to the voltage source. On the opposite of the PTC element 2 Side of the contact plates 3 are arranged as heat radiator corrugated fins 4 are arranged. The contact sheets 3 are glued to the PTC elements 2 by means of a low-cost, insulating adhesive. In addition to the current transition, the contact sheets 3 also serve to transfer heat from the PTC element to the adjacent corrugated fins 4.

A contact plate 3 is in Fig. 2 shown, wherein the side connected to the adjacent corrugated fin 4 page can be seen in the figure. How out Fig. 3 can be seen, the underside of the contact plate 3 with individual spaced-apart knurled first areas, hereinafter referred to as contact areas 5, provided. In this case, the surfaces of the contact regions 5 each correspond approximately to the surfaces of the second regions arranged therebetween, which are also designated as intermediate regions (cf. Fig. 3 ). Thus, the contact plate 3 on its directly opposite to the PTC element 2 side two differently structured areas. In the region of the ends of the contact plate 3 no knurls are provided.

An enlarged section through a contact region 5 is shown in FIG FIG. 8 shown. It can be seen that in the contact region 5, the surface is increased by the knurling, as a result of the material displacement elevations 6 and recesses 7 have arisen. In the areas between the contact areas 5 and at the ends, the surface is substantially flat, ie the surface unevenness is significantly smaller than in the contact areas 5. The depth of the recesses 7 in the present case is about 0.01 mm.

Due to the surface irregularities in the contact areas 5 and a sufficient pressure during bonding, it is ensured that in the region of the elevations 6 a direct contact of contact plate 3 and PTC element 2 is provided without an insulating adhesive layer, so that a good flow of current and thus a good heat output - if necessary even without the provision of an electrode coating on the PTC element 2 - is possible.

In the second regions arranged between the contact regions 5, the film thickness of the adhesive is so great that it has an insulating effect. However, it is ensured by this adhesive film that the mechanical connection holds at the expected loads, so that the electrical contact in the contact areas 5 is ensured.

For bonding, a glue cord is applied to two contact sheets 3 in a manner known per se. Subsequently, a large or a plurality of smaller PTC elements 2 and then the second contact plate 3 are positioned. Finally, the entire assembly is pressed together so tightly that the adhesive spreads and forms a thin film which is penetrated in the contact areas 5 of the elevations 6, wherein excess adhesive collects in the recesses 7. The pressure is maintained until the adhesive has fully cured. To accelerate the curing, a voltage may be applied so that the one or more PTC elements 2 heat up. If a plurality of PTC elements 2 are provided, they may be adjacent to one another as well as spaced from each other, as in FIG Fig. 1 can be arranged, wherein the distance of the PTC elements 2 is in principle independent of the arrangement of the contact areas 5 of the contact plates 3, but a sufficient overlap of the contact areas 5 as well as the interposed areas should be ensured. Due to the significantly better thermal conductivity of the contact sheet 3 in comparison to the adhesive film in addition to the current transition, the heat transfer in particular in the contact areas 5, but also, although somewhat obstructed by the adhesive film, in the other areas.

According to a variant not shown in the drawing, a mechanical connection of the assembly contact plates - PTC element. Instead of the adhesive, a thermal compound is provided between the contact plates and the PTC element, which provides optimum heat transfer from PTC element to the contact plates and thus also to the corrugated fins. As a result of the mechanical connection, in turn, a direct contact of contact plates and PTC elements is provided by displacing the thermal paste in the contact areas. Alternatively, a fixation by means of compression is possible.

The following is with reference to the FIGS. 4 and 5 a second embodiment explained in more detail, wherein the same or equivalent elements are provided with 10 higher reference numerals.

According to the second embodiment, the contact plate 13 as first regions or contact areas 15 approximately rectangular elevations 16 by 1 mm, wherein on the other side of the contact plate 13, a trough-shaped recess of 1 mm is formed. The production takes place by means of a forming process, which is why reference is made to the depression as a deformation. By the elevations 16, the adhesive is pushed aside in this area during bonding and the electrical contact of contact plate 13 and PTC element provided. In the areas around the ridges 16 and between the contact areas 15, there is sufficient adhesive film thickness at the recesses 17 so that these areas serve for the mechanical fastening. Thus, the contact areas 15 according to the second embodiment correspond in their function (current transition and heat transfer) the elevations 6 of the first embodiment. The contact plate 13 thus has according to the second embodiment on its directly opposite to the PTC element side two differently raised areas,

According to a variant of the second embodiment, the contact sheets 13 are arranged the other way round, i. rotated by 180 ° about the longitudinal axis of the contact element, glued to the PTC element. That is, according to the variant, the contact regions 15 of the second exemplary embodiment correspond to trough-shaped depressions in which the adhesive collects and ensures mechanical fastening, and thus to the second regions. On the other hand, the adhesive in the other areas, i. around the wells and between the wells are substantially completely displaced, so that in these areas of the current transfer and improved heat transfer takes place so that they serve as the first areas. Excess adhesive is also squeezed out at the sides, thereby ensuring - with an appropriate excess amount - that no short circuit can occur between the contact sheets, i. He also serves as an insulator.

According to a third embodiment, two rectangular elevations 16 are arranged parallel to each other (see Fig. 6 ). In the present case, the distance between the elevations 16 corresponds approximately to the width of one of the elevations 16 and the lateral edge corresponds to approximately half the width of an elevation 16. Four pairs of elevations 16 are provided one after the other in the longitudinal direction.

Of course, as a variant of the third embodiment, the twisted arrangement according to the variant of the second embodiment is possible.

Likewise, the juxtaposed contact areas according to the third embodiment may be staggered.

Fig. 9 shows a contact plate 13 according to the fourth embodiment with four groups of three parallel to each other and in the longitudinal direction of the contact plate extending first areas or contact areas 15, which are formed according to the contact areas of the second embodiment. The individual contact areas 15 in the form of elevations 16 are surrounded by the second area. The longitudinal extent of the individual groups is slightly larger than the distance of the adjacent groups. A section according to the registered section line AA is in Fig. 14 shown. The elevations 16 have a width a which is equal to the width b of the second regions or the intermediate regions. Conveniently, this width is 0.5 to 1.5 mm. The depth t of the transformations on both sides of the contact plate is 0.005 mm to 0.15 mm. Advantageously, the width and / or depth of the transformations over the entire contact plate is constant.

Fig. 15 shows the arrangement of Fig. 14 each with a PTC element 2 on both sides of the contact sheet 13. The width of the PTC elements 2 corresponds approximately to the width of two elevations 16 and two intermediate regions or depressions 17, that is, in total about four times the distance a. As a result, it is ensured, for example, during a displacement of the PTC element that the contact surface of the PTC element, regardless of its arrangement in the width direction of the contact plate, in sum, in each case the same size surfaces of elevations 16 and intermediate areas 17 and floors. As a result, a displacement of the PTC element in the width direction of the contact sheet does not change the total area of the contact, the adhesive surface or the surface that is not in direct contact. In Fig. 15 This is illustrated by the displacement of the lower PTC element with respect to the upper one. Assuming that the widths a and b are approximately the same, the result is thus a favorable width of the PTC elements 2 in the event that they correspond approximately to an even multiple of the widths a and b, respectively.

According to the fifth embodiment, which is in Fig. 10 is shown, the contact plate 13 is provided with three groups of twelve transverse first regions or contact areas 15. The individual contact regions 15 are in turn surrounded by the second region. The distance between the individual groups is slightly less than the length of the individual groups.

Fig. 11 shows the sixth embodiment, according to the three parallel to each other and in the longitudinal direction of the contact plate 13 extending first areas or contact areas 15 are provided, which are separated from each other by second areas and surrounded by the same on all sides.

According to the seventh exemplary embodiment, transversely extending first regions or contact regions 15 are provided over almost the entire longitudinal extent of the contact sheet 13, which are surrounded on all sides by second regions.

Fig. 13 shows the eighth embodiment, according to which a single first area or contact area 15 is provided, which is surrounded by a second area on all sides.

Of course, in the case of the embodiments four to eight, an arrangement is also possible in which the contact plate is rotated through 180 ° about its longitudinal axis, so that in terms of function the first regions become second regions and the second regions become first regions.

The relatively large elevations or depressions described above with reference to the exemplary embodiments two et seq. May also, according to a further variant, also be surface-deformed, that is to say for example embossed or knurled. Here, the height of the Surface deformation preferably 0.005 mm to 0.05 mm, in particular 0.01 to 0.015 mm.

Claims (18)

1. PTC heater, having at least one PTC element (2), which is disposed between two contact latches (3; 13) and is connected to the same in an electrically conductive manner, wherein at least one contact latch (3; 13) has at least two differently structured and/or raised areas on the side of the one or the multiple PTC elements (2), and wherein at least one partial area of the at least two differently structured and/or raised areas are positioned directly opposite of the one or the multiple PTC elements (2), wherein at least one contact latch (3; 13) has multiple first areas (5; 15) on the side of the PTC element (2) of the two differently structured and/or raised areas, characterized in that a direct contact of the contact latch (3; 13) with the PTC element (2) is provided in the first areas.
2. PTC heater according to one of the previous claims, characterized in that the first areas (5; 15) are spaced from each other by means second areas (8), and/or are surrounded by the second areas (8), and/or surround the second areas (8).
3. PTC heater according to claim 2, characterized in that the ratio of the total surface size and/or of the longitudinal extension of the first (5, 15) to the second (8) areas is defined, and is about one, with a maximum deviation of +/- 50%.
4. PTC heater according to one of the claims 2 to 3, characterized in that the contact latch (3; 13) has first (5; 15) and second (8) areas on both sides.
5. PTC heater according to one of the previous claims, characterized in that at least the first area (5) is formed by a surface deformation.
6. PTC heater according to claim 4, characterized in that the first area (5) is formed by knurling.
7. PTC heater according to one of the previous claims, characterized in that at least the first area (15) is formed by a mechanical deformation (16) of the contact latch (13) continuously extending in the direction of the thickness.
8. PTC heater according to claim 2, characterized in that the deformation (16) has the shape of a rectangle, or of a rounded rectangle.
9. PTC heater according to claims 7 or 8, characterized in that the bottom of the deformation (16) is embodied in a plane manner.
10. PTC heater according to one of the claims 7 to 9, characterized in that one to five rectangular deformations (16) are disposed next two each other in the direction of the width and/or the length of the contact latch (13).
11. PTC heater according to one of the previous claims 5 or 7, characterized in that the height of the deformation and/or the surface deformation is 0.005 mm to 2 mm, in particular up to a maximum of 1 mm.
12. PTC heater according to one of the previous claims 7 to 11, characterized in that the height of the deformation and/or of the surface deformation is 0.005 mm to 0.05 mm, in particular 0.01 mm to 0.015 mm.
13. PTC heater according to one of the previous claims, characterized in that an additional medium is provided between the contact latch (3; 13) and the at least one PTC element (2).
14. PTC heater according to one of the previous claims, characterized in that the contact latches (3; 13) are connected to the at least one PTC element (2) by means of an insulating adhesive.
15. PTC heater according to one of the previous claims, characterized in that the contact latches (3; 13) are connected to the at least one PTC element (2) by means of an electrically conducting adhesive.
16. PTC heater according to one of the previous claims, characterized in that a heat transfer paste is provided, at least in some areas, between the contact latches (3; 13) and the at least one PTC element (2).
17. PTC heater according to one of the previous claims, characterized in that multiple PTC elements (2) are disposed between two contact latches (3; 13).
18. PTC heater according to one of the previous claims, characterized in that the at least one PTC element (2) is embodied in a prismatic or plate shaped manner, wherein at least the surfaces in the direction of the contact latches (3; 13) are embodied in a plane manner.

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