EP3101998B1 - Ptc heating element and electric heating device containing such a ptc heating element and method for manufacturing an electric heating device - Google Patents

Description

The present invention relates to a PTC heating element with at least one PTC element which is provided between conductor tracks.

Such a PTC element is used, for example, in electrical auxiliary heaters in motor vehicles. These auxiliary heaters are used to heat air. They have corrugated rib layers lying on opposite sides of the PTC element. Usually several layers of stacked PTC elements with corrugated rib layers resting on them are provided. Examples from the prior art of such air heaters are, for example EP 1 768 459 A1 , EP 2 109 345 B1 such as EP 1 768 458 A1 .

Generic PTC heating elements according to the present invention are also used in heaters for heating liquid media, such as those used in, for example EP 1 921 896 A1 are described.

The present invention relates in particular to a PTC heating element with the preamble features of claim 1. Such a PTC heating element is, for example, from EP 2 397 788 A1 known. In this prior art, silicone adhesive is filled in molten liquid into a tube which is closed at the end and which has previously been equipped with conductor tracks and PTC elements attached to them. Alternatively, such a unit can also be subsequently filled into the pipe filled with silicone adhesive. The corresponding procedure requires positioning strips or other inserts in the pipe, which must ensure that the conductor tracks do not come into direct contact with the walls of the pipe.

From the EP 2 211 589 A1 a heat exchanger with a PTC heating element with a plurality of PTC elements and conductor tracks lying thereon is known, which is surrounded by a circumferentially closed tube. The end of the conductor tracks are placed against spacers which enclose a free space between them and the PTC element, into which a silicone adhesive is filled. A heating unit prepared in this way is inserted into the pipe, which is then filled with a casting compound.

From the EP 1 768 457 A1 a heat-generating element is known which comprises at least one PTC element arranged in an opening of a positioning frame. On both sides of the PTC element there are contact plates as conductor tracks for energizing the PTC element. The receiving space for the PTC element formed by a frame opening in the positioning frame is hermetically sealed. For this purpose, sealing elements are provided on the positioning frame, which interact with insulating layers which are placed on the outside against the conductor track. Out DE 10 2012 013 770 A1 a similar heat generating element is known.

Basically, there is the problem of good heat dissipation. The PTC elements have self-regulating properties. If the heat generated by the PTC element is not dissipated well, the electrical performance of the PTC element cannot be fully used.

The present invention is based on the problem of specifying an improved PTC element and an improved electrical heating device. Furthermore, the present invention seeks to propose the production of an electrical heating device.

To solve the device-related problem, the first aspect of the present invention proposes a PTC heating element according to claim 1.

In particular in high-voltage applications, for example when installing the PTC heating element in an electrical heating device for an electrically driven motor vehicle, there is the problem of electrical flashovers, for example due to air and / or creepage distances. This problem is countered with the present invention in that at least one of the conductor tracks, preferably this one conductor track and the PTC element resting thereon on one side, is sealed into a compound at the end. The free end face of the conductor track is usually completely incorporated into the mass. The end face of the PTC element can only be partially incorporated into the mass and thus covered by it. The conductor track usually ends flush with the outer circumferential surface of the PTC element. Only electrical connection lugs usually protrude on one side beyond the PTC element. These connection lugs are located at opposite ends of the PTC element and are used to supply the same with different polarity.

This insulating mass usually comprises a silicone mass as the liquid phase. The liquid phase is preferably formed by an addition-crosslinking 2-component silicone that hardens at room temperature and hardens under heat. The mass has a viscosity at 25 ° C of between 100 and 200 Pa s. With a view to good flowability, gasoline or toluene is usually added to the 2-component silicone as a thinner in order to obtain a viscosity in a range of between 4 and 15, preferably between 5 and 8 Pa s at 25 ° C. The thermal conductivity of the mass (liquid phase + particles) is regularly between 3.0 and 5.0 W / (m K). In the crosslinked state, the component of the mass forming the liquid phase should have a Shore A hardness of about 10 - 40 and a dielectric strength CTI> 600. A predetermined solid content with high thermal conductivity is usually added to this liquid phase. The thermal conductivity of the filler component should be between 20 and 30 W (m K). The filler is preferably alumina. With a view to good flow properties, spherical aluminum oxide with an average grain size of approx. 4 to 6 μm is preferred. With a view to good thermal conductivity of the mass (liquid phase + filler content), the mass has a filler content of at least 50% by volume, particularly preferably between 85 and 95% by volume.

The individual components of the PTC heating element are preferably joined to form a unit by the insulating mass. The PTC heating element according to the present invention preferably does not have a frame that joins and / or surrounds the components.

According to a preferred development of the present invention, the PTC element has an insulating layer projecting beyond the end of the conductor track, which, with the conductor track and / or the PTC element, defines a receiving area that receives the insulating compound. The insulating layer is an electrical insulating layer. It can consist of a hybrid film which comprises a polyimide film and an electrically insulating, but preferably highly thermally conductive, mass applied to it as the second layer of the insulating layer. This mass preferably has the same material composition as the electrically insulating mass for sealing the conductor track.

The insulating layer usually projects beyond the PTC element on all sides. As a result, a gusset is formed between the PTC element and the insulating layer, which forms the aforementioned receiving area. The electrically insulating compound can be introduced into this gusset-shaped receiving area and cured there.

The PTC heating element according to the invention is produced as a separate component and designed to be adapted for insertion into an electrical heating device, in particular for insertion into a U-shaped recess of a heater housing. This U-shaped recess preferably extends from a partition which separates a circulation chamber from a connection chamber. The U-shaped recess is provided within a heating rib that extends from the partition in the circulation chamber protrudes and delimits the U-shaped recess in a fluid-tight manner with respect to the circulation chamber. The recess only opens towards the connection chamber. The circulation chamber is designed to accommodate a liquid medium, ie it is sealed and provided with inlet and outlet connections for connecting the circulation chamber to a circuit for liquid medium. The electrical heating device has a preferably trough-shaped lower housing part which encloses the circulation chamber between a housing base, the partition wall extending parallel thereto and the housing side walls extending at right angles thereto. Connecting pieces for connecting the electrical heating device to a circuit for a liquid medium protrude from the side walls of the lower housing part. These connecting pieces are sealingly connected to the housing side walls. The lower housing part can be made of plastic. The circulation chamber is liquid-tight.

The filling volume of the circulation chamber in water heaters of the type described above is between 450 ml and 200 ml, preferably between 400 ml and 220 ml and particularly preferably between 300 ml and 230 ml. This filling volume also includes the filling volume of the connecting piece. Each nozzle has a filling volume of about 7 ml. The embodiment shown is usually integrated in a cooling water circuit in a vehicle, which has a volume of about 5 to 6 liters. At least one heat exchanger for heating air in the passenger compartment can be integrated into this cooling water circuit. In addition or as an alternative, the cooling water circuit can also have heat exchanger surfaces for technical components of an electric vehicle in order to bring them to the required operating temperature when the ambient temperature is cold. The PTC element according to the invention is therefore used in particular in a heater of an electrically powered motor vehicle, in which the liquid medium is heated, for example to heat a unit or the interior of the electrically powered vehicle. In such an application, the PTC heating element is energized with a high voltage, so that special care must be taken here that creeping and / or air gaps are eliminated.

With a view to a good heat-conducting introduction of the PTC element into such a U-shaped recess, the PTC element is preferably wedged in the recess, as shown in FIG EP 2 637 475 A1 or the EP 1 921 896 A1 is known. For this purpose, according to a further preferred embodiment of the present invention, a sliding plate is proposed that can be connected, for example glued, to the PTC element via the electrically insulating mass. This results in a prefabricated intermediate product which can be inserted as a unit into the U-shaped recess. The intermediate product consists of the PTC element and the conductor tracks provided on both sides. These conductor tracks are usually formed by contact sheets. The conductor tracks are connected to the PTC element, preferably glued. Insulating layers are preferably provided in each case on opposite free areas of the conductor tracks. The PTC heating element, that is to say the PTC element and the conductor tracks lying thereon on both sides, is enclosed between the two insulating layers. Said sliding plate rests against one of the insulating layers.

The sliding plate preferably projects beyond the PTC element as well as the conductor tracks. Furthermore, the sliding plate preferably protrudes over one of the insulating layers at the end and engages over this insulating layer with a leg that extends at a distance from the PTC element on the underside. A space thus formed between the leg and the PTC element is completely or partially filled with the electrically insulating compound. The corresponding leg of the sliding plate preferably forms a stop which defines the penetration depth of the PTC heating element into the U-shaped recess. The insulating layer protruding beyond the conductor path at least on the underside provides a minimum distance between the sliding plate and the PTC element. This distance is preferably between 2.5 and 4 mm.

According to a preferred development of the present invention, the sliding plate is formed from a sheet metal material at least by punching and bending and has a spacer formed by this processing. With this spacer, the PTC heating element is held at a predetermined distance from an inner surface of the U-shaped recess. So the spacer is preferably dimensioned so that the PTC heating element rests against the inner surface of the U-shaped recess with the interposition of the insulating layer, whereas on the opposite side the sliding plate limits the package of PTC heating element and insulating layers attached to it on the outside, and from the the side of the spacer facing away from the PTC heating element protrudes and rests against the other inner surface of the U-shaped recess. A plurality of spacers are preferably provided. The spacers can be formed, for example, by spring elements which can be provided one above the other in the direction of insertion of the PTC element into the U-shaped recess. Preferably, two spacers enclose between them a contact or sliding surface for a wedge element which braces the PTC element in the U-shaped recess.

According to a preferred development of the present invention, a sheet metal is provided which encompasses the PTC element and the conductor tracks on one side, for example on the underside. This sheet metal element can for example be formed by the sliding plate. The sheet metal element can form a lower stop through which the PTC heating element is in its end position is given in the U-shaped recess. The electrically insulating compound preferably completely or partially fills the space between the stop and the PTC element.

The sliding plate can be connected, for example glued, to the PTC element. Usually, the sliding plate preferably forms a U-shaped receptacle for the PTC element together with the conductor tracks resting thereon and an insulating layer delimiting them on the outside. This prefabricated unit can be held in the U-shaped receptacle by means of clamping.

According to a preferred development of the present invention, the conductor tracks protrude beyond the PTC element in the direction in which it is inserted at least on one side and at the end, preferably on an underside of the PTC element opposite the terminal lugs, lie against a bar whose thickness is the thickness of the PTC element plus the thickness of the two conductor tracks does not exceed. In this preferred embodiment, the conductor tracks are preferably formed by contact plates which have connection lugs formed thereon in one piece by means of punching. The connection lugs can pass through a further strip, which is provided opposite the first, previously described strip and is also connected to the conductor tracks. This upper bar usually has openings for the connection lugs of the contact plates. To avoid an air gap and creepage distance between the end sections of the conductor tracks protruding beyond the PTC element, the electrically insulating mass is provided between these end sections and the bar. The other two end faces, i.e. regularly the longitudinal side surfaces of the PTC element, also here preferably end flat with the conductor tracks. The bar can have a central projection that forms contact surfaces for the contact plates.

According to the present invention, the ground is provided around the PTC element and / or the conductor track. According to the invention, the compound is applied as an adhesive bead to seal the PTC element and / or the conductor tracks around these components. The insulating layer, particularly preferably both insulating layers, preferably forms the PTC element protruding edges. The electrically insulating compound is glued to these edges as an adhesive compound. The electrically insulating mass preferably runs around the PTC element. The edges of the insulating layer also project beyond the PTC element on all sides. Accordingly, a circumferential bead from the electrically insulating compound results between opposing insulating layers, through which the PTC element is completely sealed. Only the connection lugs pass through the insulating mass and are on one connection side of the PTC heating element free. The connection lugs preferably protrude through a connection flange for holding and positioning the PTC heating element in the U-shaped recess. This connection flange is glued to the PTC element via the adhesive, electrically insulating compound. Thus, in this embodiment, the PTC element and the conductor tracks adjacent to it are preferably completely covered and sealed in by the electrically insulating compound.
According to a further aspect, the present invention proposes an electrical heating device, in particular for a motor vehicle, with heat-emitting surfaces that accommodate at least one PTC heating element between them. This PTC heating element is shaped according to one of the configurations discussed above.

With its secondary aspect, the present invention also proposes a method for producing an electrical heating device with the features of claim 13. In this process, the conductor tracks are glued to the PTC element to create a PTC heating cell. The PTC heating cell produced in this way is placed between two electrical insulating layers and sealed in by an electrically insulating compound, which is applied as a bead of adhesive that seals at least one of the conductor tracks and / or the PTC element, so that the insulating compound is applied against exposed front edges of the conductor track and at least partially against exposed frontal edges of the PTC element. In this case, the electrically insulating mass can initially be placed on protruding edges of an insulating film that forms the insulating layer. The PTC heating cell was previously placed on this film. The electrically insulating compound is applied around the PTC heating cell and on one layer of the film. Then the insulating film is turned over to seal the PTC heating cell and placed on the other of the conductor tracks. By folding over the insulating film, the PTC heating cell is surrounded by the electrically insulating mass. This then extends between the opposite inner surfaces of the insulating film and preferably glues the two film sections to one another. Excess insulating mass can be pushed out on the front side via the PTC heating element. The PTC heating element prepared in this way and designed to be externally insulating can then be inserted into a U-shaped recess of a heater and electrically insulated therein by casting with the electrically insulating compound, but inserted with good thermal conductivity.

Figur 1

eine perspektive Seitenansicht eines ersten Aufführungsbeispiels eines PTC-Heizelementes;

Figur 2

eine perspektive Seitenansicht gemäß Figur 1 nach dem Umlegen der Hybridfolie;

Figur 3

eine perspektive Seitenansicht eines zweiten Aufführungsbeispiels eines PTC-Heizelementes;

Figur 4

eine perspektive Seitenansicht eines Aufführungsbeispiels eines Gleitbleches;

Figur 5

eine Querschnittsansicht einer Heizrippe eines nicht weiter dargestellten Ausführungsbeispiels einer elektrischen Heizvorrichtung nach dem Einsetzen eines vierten Aufführungsbeispiels eines PTC-Heizelementes gemäß Figur 1, 2 zusammen mit dem Gleitbleches nach Figur 4;

Figur 6

eine perspektivische, teilweise geschnittene Darstellung eines nicht weiter dargestellten Ausführungsbeispiels einer elektrischen Heizvorrichtung nach dem Einsetzen eines vierten Aufführungsbeispiels eines PTC-Heizelementes gemäß Figur 9;

Figur 7

eine perspektive Seitenansicht eines dritten Aufführungsbeispiels eines PTC-Heizelementes;

Figur 8

das in Figur 7 gezeigte Ausführungsbeispiel bei teilwiese weggenommener Masse und

Figur 9

eine perspektive Seitenansicht eines vierten Aufführungsbeispiels eines PTC-Heizelementes.

Further details and advantages of the present invention emerge from the following description of an exemplary embodiment in conjunction with the drawing. In this show:

Figure 1

a perspective side view of a first embodiment of a PTC heating element;

Figure 2

a perspective side view according to Figure 1 after turning over the hybrid film;

Figure 3

a perspective side view of a second embodiment of a PTC heating element;

Figure 4

a perspective side view of an embodiment of a slide plate;

Figure 5

a cross-sectional view of a heating rib of an embodiment (not shown) of an electrical heating device after the insertion of a fourth embodiment of a PTC heating element according to FIG Figure 1 , 2 together with the sliding plate Figure 4 ;

Figure 6

a perspective, partially sectioned illustration of an embodiment (not shown) of an electrical heating device after the insertion of a fourth embodiment of a PTC heating element according to FIG Figure 9 ;

Figure 7

a perspective side view of a third embodiment of a PTC heating element;

Figure 8

this in Figure 7 Shown embodiment with partially removed mass and

Figure 9

a perspective side view of a fourth embodiment of a PTC heating element.

The Figure 1 shows a perspective side view of a PTC heating element 2 with a PTC element 4, which is arranged between two conductor tracks 6 designed as contact plates made of sheet metal. In Figure 1 only the upper of the two contact plates 6 is shown. The PTC element 4 is located below. The PTC element 4 and the two contact plates 6 basically have the same base area. The contact plates 6 are only on the upper side to form a contact lug 6.1 formed in one piece on the sheet metal element. extended over the PTC element 4. To form a PTC heating element, the contact plates 6 are connected to the PTC element 4 via an adhesive, preferably an electrically conductive adhesive. This prefabricated PTC heating cell 7 is placed on a hybrid film 8 which is wider than the PTC heating element 2. The hybrid film 8 consists of a relatively thin film to which an electrically non-conductive pasty mass is applied.

On the in Figure 1 The path of the hybrid film 8 shown, the PTC heating element 2 is placed. Since the insulating layer formed by the hybrid film 8 protrudes slightly beyond the PTC element in the width direction, the hybrid film 8 forms edges 8.1 that protrude in the width direction. The hybrid film 8 also protrudes quite considerably beyond the PTC heating element 2 on its underside and to a certain extent on the upper side, ie where the influence flags 6. This results in peripheral edges 8.1 around the PTC heating element 2. On these edges 8.1. the electrically insulating, but thermally conductive mass 10, which is also used to produce the hybrid film 8, is applied as a bead. The electrically insulating mass 10 thus lies at the end against the exposed frontal edges of the two contact plates 6, which take the PTC element 2 between them. The bead made of insulating compound 10 is applied with a sufficient volume so that the height of the bead corresponds approximately to 1/2 to 4/5 of the height of the PTC element 4 plus the height of one of the two contact plates 6.

Then the hybrid film 8 is turned over and on the in Figure 1 still exposed top of the upper contact plate 4 applied. The bead of adhesive formed from the compound 10 then contacts the hybrid film 8 and seals the PTC element 4 and / or one of the contact plates 6 in full. Only the terminal lugs 6.1 enforce this circumferential, electrically insulating enclosure of the PTC element.

Fig. 2 shows the embodiment Fig. 1 in a perspective side view after the hybrid film 8 has been turned over. As can be seen, the hybrid film 8 protrudes beyond the bead of the compound 10 on all sides Receiving area 11, which is formed continuously in the width direction of the PTC heating element 2.

The Figure 3 shows an alternative embodiment. The same components are identified by the same reference numerals as in the previously described exemplary embodiment.

The PTC heating element 2 after Figure 3 has two insulating layers 12 extending parallel to one another. These insulating layers 12 can be layers of the aforementioned hybrid film. Alternatively, insulating layers made of a ceramic and / or of a ceramic coated with a plastic film can also be provided. In this exemplary embodiment, too, the mass 10 is provided in the manner of a circumferential adhesive bead so that at least one of the conductor tracks 6 is completely covered by the mass 10 and the PTC element 4 is completely covered, but not over its entire height, but only up to a height of approximately 1/2 the thickness of the PTC element 4 is sealed.

The Figure 4 shows a perspective side view of an embodiment of a sliding plate 14, which is bent over by two bending to form a U-shaped profile in the side view. A U-shaped receptacle 16 formed in this way is dimensioned in such a way that the previously described with reference to FIG Figures 1 to 3 The embodiments of PTC heating elements discussed above each fit into the U-shaped receptacle 16. On an outer surface, the sliding plate 16 forms a sliding surface 18 over which spacers 20 protrude on both sides, which are formed by bending the material forming the sliding plate 14. The spacers 20 extend in the longitudinal direction of the sliding plate 14, and they are only provided in the upper part of the sliding plate 14. As an extension of these spacers 20, inclined surfaces 22 are provided, which run in the shape of a funnel obliquely towards the sliding surface 18 and slightly project beyond this sliding surface 18. The spacers 20 and the inclined surfaces 22 form a lateral boundary of an in Figure 5 wedge element identified by reference numeral 24.

The Figures 5 and 6th illustrate the installation situation of a PTC heating element 2 received in the U-shaped receptacle 16 of the sliding plate 14. Reference numeral 26 denotes a part of an upper housing part that can be placed on a trough-shaped lower housing part (not shown) to create a circulation chamber for the liquid medium to be heated train like this from the EP 1 872 986 A1 is known. The disclosure content of this document - insofar as it relates to the heating device as such and in particular to the details of the lower housing part and upper housing part, is incorporated into the disclosure of the present application by this reference.

The upper housing part 26 has a dividing wall 28, which usually extends parallel to the bottom of the lower housing part, and usually a plurality of heating ribs 30 protruding at right angles from this dividing wall 28, which opens via a U-shaped recess 32 to a connection side of a heater for liquid media (in particular water heater) .

In the U-shaped recess, the unit of PTC heating element 2 and sliding plate 14, which was previously preassembled by inserting into the U-shaped receptacle 16 of the sliding plate 14, is inserted until the end of the U-shaped sliding plate 14 is on a Bottom 34 of the U-shaped recess 32 is seated.

How out Figure 6 As can be seen, the U-shaped recess 32 has lateral guide grooves 36 which extend in the insertion direction and the U-shaped recess 32 is enlarged at the edge and in the direction of thickness. These guide grooves 36 form receptacles for the spacers 20, in which the sliding plate 14 is guided and positioned when the sliding plate 14 is inserted with the PTC heating element 2. The spacers 20 press against the inner walls of the U-shaped Recess 32 exposes a wedge element receiving opening 38 into which the wedge element 24 is inserted after the sliding plate 14 with the PTC heating element 2 has been completely inserted. The wedge element 24 is provided on at least one side, preferably on opposite main side surfaces, with a water-based PTFE lubricating varnish with an organic binder. Alternatively or in addition, such a lubricating varnish can be provided on a contact surface formed by the U-shaped recess 32 for the wedge element 24 and / or the sliding surface 18. Such a coating serves as dry lubrication during the introduction movement of the wedge element 24. The slip-reducing coating ensures reproducible assembly results, since surface roughness and the like, which can vary during the manufacture of the individual components, are compensated for by the coating. Essentially the same introduction forces are necessary in order to apply different PTC heating elements 2 with a predetermined surface pressure against mutually opposite inner surfaces of one of the U-shaped recesses 32. This pressing serves, on the one hand, to conduct heat effectively from the PTC element 4 into the inner surfaces of the U-shaped recess and, on the other hand, to introduce current from the contact surfaces of the PTC heating element 2 into the PTC element 4.

Like the whole of the Figures 1 to 6 As can be seen, the insulating layers, which can be formed by the hybrid film 8 or the insulating layers 12, project beyond the sliding plate 14 in the width direction on the outside of the conductor tracks 6 and also project beyond the sliding plate 14 in the height direction towards the terminal lugs 6.1. The insulating layers protrude at least the area in which the sliding plate 14 is in direct contact with the insulating layers (cf. Figure 6 ). This increases the air gap and creepage distance between the conductor tracks and the upper housing part 26 and thus the electrical safety of the heating device. In addition, the bead of the insulating mass 10 is also located above the PTC element 4 and accordingly between the terminal lugs 6.1 of different polarity. This also increases the creepage distance. In fact, at least one of the conductor tracks 6 is completely encased by the mass 10, so that there is considerable security against leakage current. The other of the two conductor tracks 6 can be exposed circumferentially.

In the third embodiment according to Figure 7 the conductor tracks 6 are formed by metal sheets. As described above, the metal sheets have connection lugs 6.1 cut free by punching for the electrical connection of the contact sheets 6. Like the one presented to further illustrate this exemplary embodiment Figure 8 it can be seen in which the longitudinal beads of the mass 10 have been removed for reasons of improved visibility of the details, the contact plates 6 each end flush with the PTC element 4 in a direction at right angles to this, ie in the joining direction, the contact plates 6 project beyond the PTC element 4 on both sides. They each rest on a strip 39 or 40. The two strips 39, 40 have a thickness which corresponds to the thickness of the PTC heating element 2 plus the two thicknesses of the contact plates 6. A flat outer surface is thus formed on the outside by the side surfaces of the strips 39, 40 on the one hand and the outer surfaces of the contact plates 6 on the other.

The strips 39, 40 each have inwardly protruding contact webs 42, which each form contact surfaces for the contact plates 6. The strips 39, 40 are provided at a distance from the opposite end face of the PTC element 4. In other words, a free space remains between a free front face of the respective contact web 42 and the face of the PTC element 4.

As the Figures 7 and 8th To illustrate, the PTC element is completely sealed in by the bead from the insulating compound 10 in this exemplary embodiment as well. As in the previously discussed embodiment, the mass 10 does not have to extend over the entire thickness of the PTC element 4.

On the long sides, the bead made of compound 10 lies on the in Figure 7 already turned over, hybrid film 8 and covers the in Fig. 7 lower conductor track 6 almost completely at the end and part of the PTC element 4 at the end. The PTC element 4 is completely surrounded by the mass 10. On opposite end faces, ie adjacent to the strips 39, 40, the mass 10 not only serves to increase the creepage and air gap on the end face of the PTC element 4, but also as an adhesive that connects the strips 39, 40 to the connects to ordered conductor track 6. The in Figure 8 The bead 10.1, 10.2 shown made of electrically insulating compound 10 bridges the gap between the contact web 42 and the opposite end face of the PTC element 4. As a result, the clearance and creepage distance on the end faces between the conductor tracks 6 of different polarity is laid.

It goes without saying that the in Figure 7 Bead 10.3 of the mass 10 shown on the long side also extend over the entire length of the conductor track 4 and can accordingly cover it completely on the long side.

An essential aspect of the present invention is also the Figure 8 can be seen, after which the mass 10 is applied to a protruding edge of the insulating layer (in this case the hybrid film 8) in order to cover one of the conductor tracks 6 and the PTC element 4 to increase the clearance and creepage distance.

The Figures 5 and 9 show a further modified embodiment of a PTC heating element 2 when viewed together. In the case of this PTC heating element 2, the upper bar 40 is L-shaped, so that a relatively large-area contact leg results for the contact of the insulating layer 12. As in the previously discussed embodiment according to Figures 7 and 8th the upper bar 40 has recesses which are designed to be adapted to the implementation of the terminal lugs 6.1. The design of the in Figure 9 built-in sliding plate 14 corresponds to the embodiment according to Figures 4 and 6th . The sliding plate 14 thus encloses the lower bar 39. The lower bar 39 rests on the inside against a crosspiece of the U-shaped receptacle 16 of the sliding plate 14 (cf. Figure 5 ). The lower power 39 in the present case extends beyond the insulating layer 12 as well as the sliding plate 14 in the width direction, partially surrounds the longitudinal bead 10.3 and forms a stop for the relative positioning of adjacent PTC heating elements 2 in an elongated U-shaped recess of a heating rib. The lower bar 39 can be a plastic injection molded part.

One or both strips 39, 40 can be connected to the contact plates 6 by overmolding, for which purpose a contact plate at the level of a corresponding strip can have bores into which a plastic forming the strip can enter in molten form in order to connect the strip to the contact plate in a form-fitting manner. The other contact sheet is regularly glued against the other bar. The mass 10 can also be used to fill a free space between the bar and the PCT element 4 and / or to connect the bar 39 to the PTC element 4.

The lower bar 39 usually has slightly rounded outer edges, especially when the hybrid film 8 is to be wrapped around the bar 39 at the end. The rounded edges reduce the risk of damage to the hybrid film 8 during assembly.

List of reference symbols

2

PTC heating element

4th

PTC element

6th

Conductor track / contact plate

6.1

Connection lug

7th

PTC heating cell

8th

Hybrid film

8.1

edge

10

Dimensions

10.1

bead on top

10.2

underside bead

10.3

longitudinal bead

11

Recording area

12

Insulating layer

14th

Sliding plate

16

U-shaped mount

18th

Sliding surface

20th

Spacers

22nd

Bevel

24

Wedge element

26th

Housing upper part

28

partition wall

30th

Heating rib

32

U-shaped recess

34

ground

36

Guide groove

38

Wedge element receiving opening

39

strip

40

strip

Claims (14)

1. PTC heating element (2) with at least one PTC element (4) provided between strip conductors (6), and an insulating mass (10) sealing at least one of the strip conductors (6) and/or the PTC element (4) over the whole circumference, wherein the insulating mass (10) is applied as a glue bead which seals the strip conductor (6) and/or the PTC element (4) circumferentially, characterized in that the insulating mass (10) is laid against free front side edges of the strip conductor (6) and at least in part against free front side edges of the PTC element (4).
2. PTC heating element (2) according to claim 1, characterized by an insulation layer (8, 12) which projects over the strip conductor (6) at the end side and which with the strip conductor (6) and/or the PTC element (4) defines a receiving portion receiving the insulating mass (10).
3. PTC heating element (2) according to any one of the preceding claims, characterized in that the insulating mass (10) in thickness direction partly surrounds the PTC element (4) and one of the strip conductors (6).
4. PTC heating element (2) according to claim 2, characterized by a slide sheet (14) lying against the insulation layer (8, 12).
5. PTC heating element (2) according to one of the preceding claims 2 or 4, characterized in that the insulation layer (8, 12) and/or the slide sheet (14) projects over the PTC element (4) and the strip conductor (6) at the edge and that the insulating mass (10) seals the strip conductor (6) and/or the PTC element (4) at the edge.
6. PTC heating element (2) according to one of the preceding claims 4 or 5, characterized in that the slide sheet comprises at least one spacer (20) which is formed by punching and bending from a sheet material forming the slide sheet (14).
7. PTC heating element (2) according to any one of the preceding claims, characterized in that the strip conductors (6) project over the PTC element (4) at the end side and lie at the end side against at least one bar (39, 40), the thickness of which does not exceed the thickness of the PTC element (4) plus the thickness of the two strip conductors (6).
8. PTC heating element (2) according to claim 7, characterized in that the bar (40) is glued to the PTC element (4) by an insulating mass (10), which is formed as an adhesive insulating mass and seals at least one of the strip conductors (6) and/or the PTC element (4) at the end side.
9. PTC heating element (2) according to any one of the preceding claims, characterized in that the insulating mass (10) is formed as an adhesive insulating mass and is applied to an insulation layer (8) to surround the PTC element (4), and that the insulating layer (8) covers at least an outer surface of the strip conductors (6) that faces away from the PTC element (4).
10. Electric heating device particularly for an automotive vehicle with heat-emitting surfaces, which receive at least one PTC heating element (2) thereinbetween, with a PTC element (4) which is contacted at both sides with strip conductors (6) which serve the electrical connection of the PTC element (4), and of which at least one is provided with an insulation layer (8, 12) on its outer surface facing away from the PTC element (4), wherein the PTC heating element (2) is formed according to any one of the preceding claims.
11. Electric heating device according to claim 10, characterized in that the heat-emitting surfaces are formed by opposite inner surfaces of a U-shaped recess (32) of a heater housing, and that the electrically insulating mass (10) is just provided between the inner surfaces of the U-shaped recess (32) and a front side of the PTC heating element (2).
12. Electric heating device according to claim 11, characterized in that the PTC heating element (2) is formed according to claim 6 and held at a predetermined distance from an inner surface of the U-shaped recess (32) via the spacer (20).
13. Method for producing an electric heating device comprising at least one PTC element (4) provided between strip conductors (6), in which the strip conductors (6) are glued to the PTC element (4) for producing a PTC heating cell (7) and at least one of the strip conductors (6) and/or the PTC element (4) are sealed over the whole circumference by an electrically insulating mass (10), wherein the insulating mass (10) is applied as a glue bead which seals the strip conductor (6) and/or the PTC element (4) circumferentially, characterized in that the insulating mass (10) is laid against free front side edges of the strip conductor (6) and at least in part against free front side edges of the PTC element (4).
14. Method according to claim 13, characterized in that the PTC heating cell (7) is placed with one of the strip conductors (6) on an insulating film (8), the insulating mass is applied against projecting edges (8.1) of the insulating film (8), and the insulating film (8) is folded in for the sealing inclusion of the PTC heating cell (7) and is placed on the other one of the strip conductors (6).

Images