EP1768458A1 - Heat generating element of a heating device - Google Patents

Abstract

The unit has a positive temperature coefficient (PTC)-unit (6) and electrical conductor paths (4) that rest against opposite side surfaces of the PTC-unit. The electrical conductor paths are surrounded in an external-side by a non-electrical conductive insulating layer (8). The insulating layer has a ceramic plate and a plastic foil, where the plastic foil is arranged in an outer side of the ceramic plate and is laminated on the outer side of the ceramic plate. An independent claim is also included for a heating device for air heating.

Description

The present invention relates to a heat-generating element of a heater for air heating, comprising at least one PTC element and voltage applied to opposite side surfaces of the PTC element electrical conductor tracks. Such a heat-generating element is, for example, from the date of the present applicant EP 1 061 776 known.

The heat-generating element is used in particular in a heater for a motor vehicle and comprises a plurality of successively arranged in a row PTC elements which are energized via parallel to each other, flat on opposite sides of the PTC elements voltage applied electrical conductors. The conductor tracks are usually formed by parallel metal strips. The heat-generating elements thus formed are used in a heating device for air heating in a motor vehicle, which comprises a plurality of layers of heat-generating elements, abut on the opposite sides of heat-emitting elements. These heat-emitting elements are applied via a holding device in relatively good heat-transfer contact to the heat-generating elements.

In the aforementioned prior art, a holding device of the heating device is formed by a frame in which a plurality of mutually parallel layers of heat-generating and heat-emitting elements are spring-loaded. In an alternative embodiment, which also discloses a generic heat-generating element and a generic heater and the example in the EP 1 467 599 is described, the heat generating element is formed by a plurality of in a row in a plane successively arranged PTC elements, which are also referred to as ceramic elements or PTC thermistors, which are energized on opposite side surfaces by voltage applied to these tracks. One of the tracks is formed by a circumferentially closed profile. The other trace by a metal strip, the intermediate storage of an electrical insulating layer on the circumferentially closed supported metallic profile. The heat-emitting elements are formed by lamellae arranged in several parallel layers, which extend at right angles to the metal profile which is closed at the circumference. At the time of the EP 1 467 599 known generic heating device a plurality of circumferentially closed metal profiles formed in the manner described above are provided, which are arranged parallel to each other. The lamellae partially extend between the circumferentially closed profiles and partially protrude beyond them.

In the aforementioned heat generating elements, there is a requirement that the electrical traces must be in good electrical contact with the PTC elements. Otherwise, there is the problem of increased contact resistance, which can lead to a local overheating, in particular when using the heat-generating elements in auxiliary heaters for motor vehicles because of the high currents. By this thermal event, the heat-generating element can be damaged. In addition, the PTC elements are self-regulating resistance heaters that provide lower heat output at elevated temperature, so local overheating can interfere with the self-regulating properties of the PTC elements.

Moreover, at high temperatures in the range of an auxiliary heater vapors or gases can develop, which can lead to an immediate endangerment of persons located in the passenger compartment.

Accordingly problematic is the use of the generic heat-generating elements even at high operating voltages, for example at voltages up to 500 V. Here, on the one hand the problem that the heat-emitting elements flowing air moisture and / or dirt with it, which penetrate into the heater and here an electric flashover, ie can cause a short circuit. On the other hand, there is basically the problem of protecting persons working in the area of the heating device from the live parts of the heating device or the heat-generating element.

With the present invention, a heat-generating element of a heating device for air heating, as well as a corresponding heating device are given, which provide increased security. In particular, the present invention aims to increase the safety with regard to a possible electrical flashover.

To solve this problem, a generic heat-generating element is further developed by the present invention in that the outside of the two electrical conductor tracks, a non-conductive insulating layer is provided. This insulating layer is a non-electrically conductive layer. By the non-conductive electrical insulating layer, the large-scale upper and lower sides of the PTC elements and the electrical conductor tracks on the outside are electrically stripped. This prevents dust or splash water from reaching the live electrical conductor tracks directly. In the case of out of the EP 1 467 599 known heat generating element, for example, to achieve the invention, the circumferentially closed metal profile surrounded by an insulating layer. In the heat generating element of EP 1 061 776 For example, at least the electrical strip conductors forming sheet metal strips are surrounded by an insulating layer.

The insulating layer should preferably rest directly on the electrical conductor tracks, so that the heat transfer from the heat-generating elements to the heat-emitting elements is impaired only to a small extent. The insulating layer should have the best possible thermal conductivity. The aim is a thermal conductivity of more than 20 W / (m K). As appropriate in terms of the best possible protection against short circuit, an insulating layer with an electrical insulation of more than 20 kV / mm has been found. The insulating layer should preferably have an electrical breakdown strength of at least 2000 V in the transverse direction of the layer structure.

From practical experiments of the inventors, it has been found that the insulating layer should preferably comprise both a ceramic plate and a plastic foil. The combination of both elements can best represent the required insulation properties. The ceramic plate can be formed, for example, of aluminum oxide with a thermal conductivity of more than 24 W / (m K) and an electrical insulation of 28 kV / mm. The plastic film may be, for example, a polyimide film, which, like the aluminum oxide, has a relatively good thermal conductivity of 0.45 W / (m K) and a sufficient dielectric strength of 4 kV.

The ceramic plate of the insulating layer can be applied as a relatively smooth component with high accuracy over the entire surface of the electrical conductor. If desired, the insulating layer can be bonded directly to the electrical conductor. To improve the thermal conductivity between the conductor track and the insulating layer of the adhesive should be provided in a thin layer as possible below 20 microns. For the same reasons, the plastic film is preferably laminated to the ceramic plate. For this purpose, the film preferably has on one side a wax layer of between 10 to 15 .mu.m, which in particular melts under the operating conditions of the heat-generating element, ie at higher temperatures of about 80.degree. C., and when the insulating layer is pressed against the conductor track, and enables efficient heat transfer. In this case, it is beneficial to arrange the heater from parallel extending layers of heat-generating and heat-emitting elements in a frame and to keep this layer structure under spring tension in the frame, as this basically already going back to the applicant EP 0 350 528 is known. An alternative embodiment was, for example, in the EP 1 515 588 described.

The heat-generating element may be formed by a plurality of PTC elements arranged one behind the other, which cover the conductor tracks on both sides, and insulating layers surrounding the conductor tracks on the outside. All components of this layer structure can be connected to one another, in particular adhesively bonded. In this case, the electrically conductive insulating layer should preferably project beyond the electrical conductor track so that the electrically conductive and energized components of the heat-generating element are at a distance behind the outer, insulated edges of the heat-generating element, that is to say offset at a distance from the inside. The electrical conductor can project beyond the insulating layer only to form an electrical contact point.

In order to avoid access to the current-carrying parts of the heat-generating element between the insulating layers, and in particular for accurate positioning PTC elements, it is proposed according to a further preferred embodiment of the present invention to provide on the heat generating element a known position frame which forms a frame opening for receiving the at least one PTC element. This known per se positioning frame is, for example, in the aforementioned EP 0 350 528 described and is usually made of a non-conductive material, in particular a plastic material. The frame is usually formed as an elongate member, which leaves in the plane of the PTC elements or the heat-generating element for one or more PTC elements a frame openings. In this frame opening or the PTC elements are positioned.

With regard to the application of relatively high voltages, it is proposed according to the invention that the insulating layer projects beyond the conductor track at least in the transverse direction of the elongate frame, wherein the electrical conductor tracks and the at least one PTC element are circumferentially spaced from the position frame by an insulating gap. It has been found that with the use of high voltages, an electrical flashover by the thermoplastic material of the position frame can not always be avoided when the electrically conductive parts abut directly adjacent to or on the position frame. The preferred development with the insulating gap here provides relief from the risk of electrical flashover by a sufficiently large gap between the current-carrying parts and the material of the position frame is realized. To comply with this insulating gap, for example, the insulating layer can be firmly connected to the current-carrying parts of the heat-generating element and in turn fixed relative to the position frame. Thus, for example, it is possible to form the insulating layer at least in the width direction, ie transversely to the longitudinal extent of the elongate heat-generating element, with sections which project beyond the current-carrying parts, in particular the electrical conductor track in the width direction. These protruding portions of the insulating layer are preferably connected to the position frames, for example via an adhesive layer. With such a configuration, for example, the current-carrying parts of the heat-generating element, that is, the PTC element as well as the adjacent thereto conductor tracks, are completely encapsulated. The insulating layer covers the current-carrying parts on both sides and closes sealingly against the edges of the position frame on. As a result, an electrically non-conductive encapsulation in the circumferential direction of the heat-generating element is formed. In a cross-sectional view of the heat-generating element are in this preferred embodiment, the energized parts, ie, the electrical conductors and the interposed PTC elements in the middle. This layer structure is bounded on top and bottom by the insulating layer. This in turn bears with its outer edges each sealingly on the position of the plastic frame formed. In this preferred embodiment, there is no possibility that moisture or contamination, which is entrained by the heat-generating element inflowing air, can reach the live parts. In this preferred embodiment, only the current-carrying parts, especially the contact sheets, can project beyond the insulating layer on one or both end sides of the heat-generating element. There, however, the electrical conductor tracks are regularly added to the holding device of the heater and by the structural elements of this holding device, the current-carrying parts can be sealed against the incoming air.

The electrically non-conductive encapsulation is preferably created by the fact that the sections of the insulating layer which project beyond the electrical trace are sealed with the interposition of a sealing element in relation to the position frame. The sealing element is preferably formed of an insulating material, for example an elastic plastic. Preferably, however, the sealing element is formed by a plastic adhesive connecting the position frame and the insulating layer, so that not only a circumferential encapsulation of the current-carrying parts is effected, but also the current-carrying parts together with the insulating layers attached thereto together with the position frame to a structural Unit are connected.

It should be noted that the position frame can be made of an electrically high-quality insulating material and that completely dispenses with the use of a conventional thermoplastic material. For example, the positioning frame may be formed by a uniform silicone component. It is also possible, the positioning frame by injecting a highly insulating, preferably adhesive sealing compound between the at the opposite side surfaces of the PTC elements form adjacent layers. In such a case, the PTC elements can be positioned with respect to the remaining layers of the layer structure for assembly purposes and finally fixed in position by injecting the highly insulating mass. The position frame is not used in such a case as a positioning aid during assembly, but only to ensure a predetermined position of the PTC elements or the permanent operation of the heat-emitting element.

If the position frame is formed as an injection-molded component from a high-quality electrical insulation material and used as a positioning aid during assembly, by introducing an adhesive between the opposing layers and adjacent to the PTC element these together with the PTC elements and the silicone frame to a structural unit to be glued. Even in such a case can be dispensed with a conventional Spitzgießteil from a conventional thermoplastic for forming the position frame.

The electrical conductor track is preferably formed by a contact plate, which projects beyond the at least one PTC element. At least one electrical contacting point in the form of a plug element is formed by the contact plate on the side projecting beyond the at least one PTC element, through which the electrical connection of the heat-generating element to a power supply can take place. Accordingly, the contact plate preferably projects beyond the PTC element at least on the end face of the heat-generating element. However, it is also possible to design the contact plate such that it projects beyond the PTC element in the width direction.

Preferably, the current-carrying contact sheets are used in particular to hold the PTC elements within the frame opening formed by the positioning frame. Accordingly, a portion of the support frame extends between the opposing projecting ends of the contact sheets. In other words, the holding frame is also provided between the opposing contact plates, so that the current-carrying parts of the heat-generating element held within certain limits in the position frame in the height direction are. Compliance with the Isolierspaltes between the contact plates and the material of the position frame can be effected, for example, by an insulating spacer means which is provided in the insulating gap between the PTC element projecting edge of the contact plate and the material of the positioning frame. Preferably, this spacing means extends in the transverse direction of the positioning frame to the outer end of the contact sheet. The insulating spacer means is preferably formed by a plastic material which has a higher electrical breakdown strength than the material of the positional frame (eg silicone, polyurethane).

Case designs are conceivable in which the PTC element or elements are held loosely in the frame opening between the two contact plates. This case design is to be taken in particular if, for reasons of good electrical contact between the PTC elements and the contact plate is dispensed with an adhesive bond between the two parts. In order to avoid a direct contact of the PTC elements on the material surrounding the frame opening of the position frame and to ensure a safe adherence to the insulation gap, it is proposed according to a preferred development of the present invention that the insulating spacer means surrounds the circumference surrounding this frame opening Edge is formed extending. Accordingly, the insulating spacer means is located in the plane receiving the PTC elements and immediately adjacent to an end face of the PTC element opposite the position frame.

The sealing element extends at least in the longitudinal direction of the position frame. With a view to the most accurate arrangement and positioning of the sealing element, in particular with respect to the projecting ends of the insulating layer, this is provided adjacent to a Dichtmittelbegrenzungsrand, which preferably extends continuously in the longitudinal direction of the positioning frame and is formed by the position frame. This sealant-limiting edge extends in the height direction of the positioning frame, that is, in a direction which is aligned both perpendicular to the transverse direction of the positioning frame and perpendicular to the longitudinal direction of the positioning frame. The Dichtmittelbegrenzungsrand should preferably via extend the entire longitudinal extension of the position frame, ie the sealing element on the opposite longitudinal sides of the position frame grasp.

In the same direction and in view of the most accurate positioning of the insulating layer extending in the height direction preferably has a boundary edge, which extends in the height direction in any case up to the level in which the insulating layer is located. Between opposite boundary edges, the respective insulating layers are accordingly provided. In this case, the front end of the insulating layer is arranged at a distance from the insulating boundary edges with a view to the highest possible safety against electrical breakdown. However, since the insulating layer is not actually an electrically conductive component, it can certainly be tolerated with regard to a rational production that the insulating layer directly contacts the boundary edge on one side. The boundary edges are mainly used for the exact positioning of the insulating layer in the width direction of the position frame.

In addition to these vertically extending mounting aids, the positioning frame preferably also extends in the vertical direction, i. in a direction transverse to the bearing plane of the PTC element extending boundary webs. These boundary webs project beyond the boundary edges and serve to position a heat-emitting element adjacent to the heat-generating element. This lies with the interposition of the insulating layer on the electrical conductor.

While the boundary edges and the boundary webs of the positioning of the insulating layer or the heat-emitting elements will serve in the transverse direction of the position frame, also proposed with regard to the most accurate positioning of the various components of the heat-generating element in the production of the same according to another preferred embodiment, on the positioning frame at least one transverse to the bearing plane of the PTC element, ie, to provide a vertically extending fixing web, which serves to fix the insulating layer in the longitudinal direction of the position frame. Due to the Isolierschichtbegrenzungsränder and the Fixiersteges the insulating layer during installation is relatively fixed to the frame. The insulating layer is then reliably arranged within predetermined limits in the transverse or longitudinal direction.

For positionally accurate positioning of the electrical conductor, which is preferably formed by a contact plate, the position frame further comprises in the height direction, i. transverse to the bearing plane of the PTC element extending pin. Each of the pins is precisely in engagement in a recess which is recessed in the contact plate. By melting the pin, a thickening is formed above the contact plate, through which the contact plate is secured to the position frame. In this embodiment, the contact plate is accurately positioned by the positive connection of pin and recess. The thickening secures the contact plate with respect to the position frame form-fitting. The insulating layer is preferably adhered to the unit so formed, wherein the adhesive connection is preferably between the position frame and the insulating layer.

In this way, a preassembled structural unit comprising the positional frame, the at least one PTC element and the contact sheets and the insulating layers can be formed. During the later merging of the heat-generating element with the heat-emitting element no longer has to be taken in the later steps that the individual layers of the heat-generating element are accurately positioned in the context of Entmontage.

In any case, according to a preferred development, the contact plate forms on one of its end faces a plug connection which is formed by sheet metal processing as a one-part element on the contact plate and has been reshaped such that it extends transversely to the plane of the sheet. This plug connection is located in the aforementioned development in a slot which is recessed on the positioning frame and opens outwards to an end face of the position frame. By this configuration, an electrical plug connection is in any case formed on the end face of the position frame, which can be inserted into the holding device of a heating device in order to connect the heat-generating element to the power supply.

Preferably, there are two slots on the front side and it grip the opposing contact plates with their respectively formed by sheet metal processing plug connections in the respective, recessed on the positioning frame slots.

In an alternative embodiment, the plug connection is formed by sheet metal processing of the contact plate in any case at its end face. The male terminal preferably extends parallel to the remainder of the contact sheet, but is bent over in a plane spaced outwardly from the plane containing the contact sheet. This preferred embodiment is particularly suitable for such situations in which the two contact plates on the same end side form electrical connection elements that should be widely spaced from each other with regard to the most secure insulation and space requirements of connector receptacles for the connections.

The heating device according to the invention comprises a plurality of heat-generating elements of the aforementioned type as well as a plurality of heat-emitting elements arranged in parallel layers. These heat-emitting elements are applied on opposite sides of a heat-emitting element. For example, in the embodiment according to the EP 0 350 528 be provided on each of the opposite sides of the heat-emitting element directly or with the interposition of another element of the layer structure, a heat-emitting element. As an element of the layer structure are in particular also spring elements which hold the layer structure under bias in the holding device forming frame. In an alternative embodiment according to the EP 1 061 776 are a variety of transversely to the circumferentially closed profile provided radiator elements on the circumferentially closed profile, which receives the heat-generating element in itself. According to the invention, the heat-emitting elements are in each case with the interposition of an insulating layer on opposite sides of the heat-generating element. Thereafter, on both sides of the heat-generating element, there is an insulating layer which is located between the PTC element and the heat-emitting elements generated by the PTC element. On both opposite sides of the heat-emitting element, is located thus an insulating layer through which heat is transferred to the heat-emitting element.

The heating device according to the invention is further developed by the development discussed above with reference to the heat-generating element.

Fig. 1

eine perspektivische Seitenansicht auf ein Ausführungsbeispiel eines wärmeerzeugenden Elementes in Explosionsdarstellung;

Fig. 2

eine Draufsicht aus dem in Fig. 1 gezeigten Ausführungsbeispiel;

Fig. 3

eine Querschnittsansicht entlang der Linie III-III gemäß der Darstellung in Fig. 2;

Fig. 4

eine perspektivische Seitenansicht des in den Fig. 1 bis 3 gezeigten Ausführungsbeispiels in zusammengebautem Zustand;

Fig. 5

eine perspektivische Seitenansicht eines weiteren Ausführungsbeispiels eines wärmeerzeugenden Elementes;

Fig. 6

eine Querschnittsansicht entlang der Linie V-V gemäß der Darstellung in Fig. 4 und

Fig. 7

eine perspektivische Seitenansicht eines Ausführungsbeispiels einer Heizvorrichtung.

Further details and advantages of the present invention will become apparent from the following description of embodiments in conjunction with the drawings. In this show:

Fig. 1

a side perspective view of an embodiment of a heat generating element in exploded view;

Fig. 2

a plan view of the embodiment shown in Figure 1;

Fig. 3

a cross-sectional view taken along the line III-III as shown in Fig. 2;

Fig. 4

a side perspective view of the embodiment shown in Figures 1 to 3 in the assembled state.

Fig. 5

a side perspective view of another embodiment of a heat generating element;

Fig. 6

a cross-sectional view along the line VV as shown in Fig. 4 and

Fig. 7

a perspective side view of an embodiment of a heater.

In Fig. 1 is a side perspective view of the essential parts of an embodiment of a heat generating element is shown in exploded view. The heat generating element has a molded plastic injection frame 2, whose central longitudinal axis forms a plane of symmetry of the heat-generating element. This is formed essentially mirror-symmetrical and has on each side of the positioning frame 2 initially provided contact plates 4, which receive between them in the position frame 2 recorded PTC elements 6. On the outside of the contact sheets 4 is a two-ply insulating layer 8 comprising an outer insulating film 10 and an inner ceramic plate 12 directly adjacent to the contact sheet 4. The ceramic plate 12 is a relatively thin alumina plate having a very good dielectric strength of about 28 kV / mm and a good thermal conductivity of more than 24 W / (m K) provides. The plastic film 10 is presently formed by a Polymidfolie having a good thermal conductivity of about 0.45 W / (m K) and a dielectric strength of 4 kV. Between the plastic film 10 and the ceramic plate 12 is a few microns thick wax layer whose melting point is tuned with respect to the operating temperature of the heat-generating element, in such a way that the wax melts at operating temperature and between the plastic film and the ceramic plate 12, the abut each other under compressive stress, so distributed that a compensating film is created, which promotes good heat transfer between the two parts 10, 12 of the insulating layer 8. The combination of plastic film 10 and ceramic plate 12 leads to an insulating part 8, which has good electrical properties and thermal conduction properties and in particular against breakdown voltages of up to 2000 V, but which also shows the necessary strength at the same time. By the external insulating foil any voltage spikes, which can be generated in particular when applied by pressure against the heat-generating element heat-emitting elements, degraded and homogenized. The arranged between the two parts 10, 12 of the insulating wax, optionally also an additional there provided and both parts 10, 12 interconnecting adhesive favors this degradation of voltage spikes. Accordingly, even at higher compressive stresses, which hold a layer structure of heat-generating and heat-emitting elements under bias, not the risk that breaks the relatively brittle ceramic layer.

The insulating layer 8 is preferably glued to the outside of the contact plate 4. This is located approximately in the middle of the insulating layer 8 and is smaller in width as the insulating layer 8 is formed. However, the respective contact plate 4 projects beyond the insulating layer 8 at the end faces. The contact plate 4 is at this the insulating layer 8 superior ends initially significantly reduced in width. At the right in Fig. 1 end, the contact plate 4 a by free cutting with respect to the width of the contact plate 4 tapered mounting web 14, in which a recess 16 is recessed. At the opposite, with respect to FIG. 1 left end, a corresponding tapered fastening web 18 is also provided with a recess 16. From the lateral edge of this fastening web 18, a web 20 bent out of the plane of the contact sheet 4 goes off, forming the base of a plug connection 22 projecting from the front side of the positioning frame 2.

The web 20 is engaged in a recess 24 recessed on the positioning frame 2, which opens towards the end face of the positioning frame 2. The positioning frame 2 also has at its front end portions on pins 26 which extend in the vertical direction of the heat generating element, ie, at right angles depart from the surface of the position frame 2. During assembly, these pins 26 are inserted into the recesses 16. Thereafter, the pin 26 is melted to form a melt thickening and secured the contact plate 4 in this manner with respect to the positioning frame 2. As can be seen in particular in FIGS. 1 and 4, the positioning frame 2 has, in addition to the pins 26, further positioning aids for the positionally accurate arrangement of the contact plate 4 on the positioning frame 2. Thus, the positioning frame 2 forms on the one hand at the front ends of the contact plate 4 end fixing webs 28, which extend slightly over the top of the contact plate 4 and whose distance from one another corresponds approximately to the length of the contact plate 4. As a result, the contact plate 4 is positioned in the longitudinal direction. In the transverse direction of the positioning frame 2 to the other over almost the entire longitudinal extent of the contact plate 4 extending boundary edges 30, which also extend beyond the top of the contact plate 4 and whose distance from each other is a little larger than the width of the contact plate 4. This boundary edge 30 is surmounted on both sides by boundary webs 32 with inner latching projections, by means of which a heat-emitting element to be arranged on the heat-generating element can be fixed for assembly purposes.

In the heat-generating element are - as is apparent from Fig. 3 - opposite surfaces of the PTC elements 6 on the inner surfaces of the contact plates 4 and are fixed in a frame opening 34 of the positioning frame 2. As is apparent from Fig. 1, there are six PTC elements 6 within a frame opening 34. There are two longitudinally successively arranged equally sized frame openings 34 are provided. The packing of the PTC elements is spaced from the material of the positioning frame 2 by an insulating gap 36. This insulating gap 36 also extends in a direction parallel to the bearing plane between the inside of the contact plate 4 and a tapered inner edge 38 of the position frame surrounding the frame opening 34 circumferentially. Through the insulating gap 38 thereafter, the current-carrying parts of the heat-generating element, d. H. the two contact plates 4 and the PTC elements 6 spaced from the material of the positioning frame 2. This distance is secured in the illustrated embodiment of Figs. 1 to 4 by an insulating spacer means 40 which surrounds the front end of the inner edge 38 circumferentially. The insulating spacer means 40 is formed in the embodiment shown by a silicone strip which receives the front portion of the inner edge 38 in and surrounding it circumferentially.

It is not absolutely necessary that the current-carrying parts of the heat-generating element abut directly on the insulating spacer means 40. Rather, the spacing means should only prevent the live parts coming into direct contact with the plastic material of the positioning frame 2. The insulating properties of the spacer means 40 are chosen so that this has a better insulation effect than the plastic material of the positioning frame 2 anyway. The width of the spacing means 40 in the width direction is selected such that it in any case reaches as far as the wide-side end of the contact sheet 4. The spacer means 40 covers the upwardly and downwardly exposed sides of the inner edge 30 and a peripheral edge formed by the inner edge 38, the frame opening 34 peripherally surrounding edge 42. The spacer means 40 can then also as the inner, the frame opening 34 circumferentially surrounding edge enclosing insulating jacket considered be prevented, both a direct contact between the PTC element 6 and the thermoplastic material of the positioning frame 2 as well as a direct contact of the contact plates 4 on the positioning frame 2 and to be observed for electrical insulation ensures minimum distance between these parts.

In addition to an electrical insulation of the current-carrying parts of the heat-generating element, the embodiment shown in FIGS. 1 to 4 also provides a complete encapsulation of these parts. For this purpose, the insulating layer has an edge section 4 which extends on both sides over the contact plate 4 in the transverse direction (FIG. 3). Between this edge portion 4 and the inner edge 38 of the position frame 2 there is a sealing element 46, which is sealingly applied both against the position frame 2 and against the insulating layer 8. In the circumferential direction, d. H. In the width direction, the encapsulation then has the insulating layers 8 located opposite one another and the arrangement of two sealing elements 46 extending substantially at right angles thereto with the material of the positioning frame 2 provided therebetween. The encapsulation is chosen so that no moisture or contamination from the outside can reach the live parts.

The sealing element 46 is formed by a plastic adhesive which fixes the insulating layer 8 with respect to the positioning frame 2 and thus encloses all parts of the heat-generating element provided within the insulating layers 8. In this embodiment can be dispensed with a fixation of the PTC elements 6 with the contact plates 4 with respect to the insulating layer 8 with respect to a positional positioning during operation of the heat-generating element. Nevertheless, such a fixation for manufacturing reasons may be useful.

Elastomers, for example silicone or polyurethane, have proven to be suitable for forming the sealing element 46 in the form of an adhesive. As can be seen in particular from FIG. 2, the sealing element 46 extends in the longitudinal direction of the positioning frame and is provided between the outer edge of the frame opening 34 and the delimiting edge 30. The sealing element bears against the inner edge 38, which is reduced in thickness. Immediately adjacent to the sealing member 46, a sealant limiting edge 48 is provided on the outside, which is formed by the positioning frame 2. With a view to the best possible sealing, the sealing element 46 can rest against this edge, which extends transversely to the receiving plane for the PTC elements.

FIGS. 5 and 6 show an alternative embodiment of the heat-generating element according to the invention. Identical components are identified by the same reference numerals with respect to the previously discussed embodiments.

The embodiment shown in Figs. 5 and 6 is narrower, d. H. it may be formed with a smaller width than the previously discussed embodiment. This is because the sealing member 46 abuts directly on the spacer means 40, as is apparent from the sectional view of FIG. The contact plate 4 each has a width approximately corresponding to the width of the PTC element. In each of the frame openings 34, only one PTC element 6 is arranged. In the longitudinal direction of the position frame 2, a plurality of PTC elements 6 are arranged one behind the other. The boundary edge 30 serves only the lateral abutment of the sealing element 46. The insulating layer 8 also extends with height distance to the upper edge of the boundary edge 30, so that any deviations in the widthwise alignment of the insulating layer 8 with respect to the position frame 2 can be compensated without affecting the performance of the heat generating element.

Also in the embodiment shown in FIGS. 5 and 6, the current-carrying parts are circumferentially encapsulated. In a direction transverse to the bearing plane of the PTC elements 6, this encapsulation is formed by the two sealing elements 46 and the spacing means 40 arranged therebetween.

In the width direction, the outer surface of the heat-generating element is completely flat and is formed solely by the outer surface of the insulating layer 8. Only in the region of the front ends, these upper layer 8 are superior elements which engage in corresponding recesses 16 of the contact plates 4 in the form of the pins 26 which, as already described above with reference to the first embodiment. In addition, the top is surmounted by fixing webs 28, which serve in this embodiment, in particular the positioning of the heat-emitting fins in the longitudinal direction.

Another difference is that the contact plates 4 are bent over at the end faces to the outside and there form substantially parallel to the plane of the contact plate 4 extending connector terminals 50. The positioning frame 2 extends in the longitudinal direction to beyond the outwardly deflected region of the contact plate 4 and thus provides reliable insulation and spacing of the two current-carrying components.

It should be noted that in the embodiment shown in FIG. 5 instead of two plug connections only a single plug connection 50 can be provided. In this case, the energization of the other contact plate 4, for example, by a structural component of the holding device for holding the heat-generating elements, for example via the attachment web 14, which projects beyond the insulating layer 8 at the opposite end of the plug connector 50.

In Fig. 7, an embodiment of a heating device according to the invention is shown. This comprises a holding device in the form of a circumferentially closed frame 52, which is formed by two frame shells 54. Within the frame 52 a plurality of mutually parallel layers of identically formed heat-generating elements (for example, according to FIGS. 1 to 4) are received. Further, the frame 52 includes a spring, not shown, by which the layer structure is held under pretension in the frame 52. Preferably, all the heat-emitting elements 56 are disposed immediately adjacent to a heat-generating element. The heat-emitting elements 56 shown in FIG. 7 are formed by meandering bent aluminum sheet metal strips. The heat-generating elements are located between these individual heat-emitting elements 56 and behind the longitudinal struts 58 of the Luftein- or outlet opening of the frame 52 passing through the grid. One of these longitudinal struts 58 is removed in the middle of the frame 52 for the sake of illustration, so that there is a heat generating element 60 can be seen.

Since the heat-emitting elements 56 with the interposition of an insulating layer 8 against the current-carrying parts abut, the heat-emitting elements 56, that is, the radiator elements, potential-free. The frame 52 is preferably made of plastic, whereby the electrical insulation can be further improved. An additional protection especially against unauthorized contact with the live parts of the heater is additionally provided by the grid, which is also formed of plastic and formed integrally with the frame shells 54.

On a front side of the frame 52 is located in a conventional manner, a plug connection, depart from the power supply and / or control lines through which the heater can be connected in terms of control and Stromversorgungsmäßig in a vehicle. On the front side of the frame 52, a housing is indicated, which in addition to the plug connection may also have control or regulating elements.

LIST OF REFERENCE NUMBERS

2

position frame

4

contact sheet

6

PTC element

8th

insulating

10

Plastic film

12

ceramic plate

14

fastening web

16

recess

18

fastening web

20

web

22

connector

24

slot

26

spigot

28

fixing web

30

boundary edge

32

limiting web

34

frame opening

36

insulating gap

38

inner wall

40

spacer

42

edge

44

edge section

46

sealing element

48

Sealant boundary edge

50

connector

52

frame

54

frame shell

56

heat-emitting element

58

along longwall

60

heat generating element

Claims (22)

Heat generating element of a heating device for air heating comprising at least one PTC element (6) and on opposite side surfaces of the PTC element (6) adjacent electrical conductor tracks (4),
characterized,
that the two electrical conductor tracks (4) on the outside of a non-electrically conductive insulating layer (8) are surrounded. Heat-generating element according to claim 1, characterized in that the insulating layer (8) rests directly on the associated electrical conductor track (4). Heat-generating element according to claim 1 or 2, characterized in that the insulating layer (8) comprises a ceramic plate (1) and a plastic film (10). Heat-generating element according to claim 3, characterized in that the plastic film (10) is arranged on the outside of the ceramic plate (12) and laminated thereon. Heat generating element having a position frame (2) forming at least one frame opening (34) for receiving the at least one PTC element (6) according to one of claims 1 to 4, characterized in that the insulating layer (8) at least in the transverse direction electrical conductor track (4) projects beyond and that the electrical conductor track (4) and the at least one PTC heating element (6) is circumferentially spaced from the material of the positioning frame (2) by an insulating gap (36). Heat-generating element according to one of the preceding claims, characterized by a PTC element (6) and the electrical conductor tracks (4) completely encapsulating and the insulating layer (8) comprising electrically non-conductive encapsulation (8, 26, 8, 46, 40). Heat-generating element according to one of the preceding claims, characterized in that the insulating layer (8) has a the electrical trace (4) projecting portion (44) which is sealed with the interposition of a sealing element (46) relative to the positioning frame (2). Heat generating element according to claim 7, characterized in that the sealing element (46) by a the insulating layer (8) with the positioning frame (2) connecting plastic adhesive is formed. Heat generating element according to claim 7 or 8, characterized in that the sealing element (46) is provided extending at least in the longitudinal direction of the positioning frame (2). Heat-generating element according to one of claims 7 to 9, characterized in that the sealing element (46) adjacent to a by the positioning frame (2) formed, at least in the longitudinal direction of the positioning frame (2) extending Dichtmittelbegrenzungsrand (48) is arranged. Heat-generating element according to one of the preceding claims, characterized in that the positioning frame (2) extending transversely to the bearing plane of the PTC element (6), a receptacle for the insulating layer (8) and / or the electrical conductor track (4) laterally delimiting Boundary edges (30) forms. Heat generating element according to claim 11, characterized in that the positioning frame (2) extending transversely to the bearing plane of the PTC element (6) extending beyond the boundary edges (30) limiting webs (32) for positioning a voltage applied to the heat generating element (60) forming heat-emitting element (56). Heat-generating element according to one of claims 5 to 12, characterized in that in the insulating gap (36) at least between a the at least one PTC element (6) projecting edge of the electrical conductor track (4) and the material of the positioning frame (2) an insulating spacer means (40) is arranged. Heat-generating element according to 13, characterized in that the spacer means (40) between the frame opening (34) circumferentially surrounding edge (42) and the PTC element (6) is formed. Heat generating element according to one of claims 5 to 14, characterized in that the positioning frame (2) frontally at least one transversely to the bearing plane of the PTC element (6) extending fixing web (28) for fixing the insulating layer (8) in the longitudinal direction of the position frame (2). Heat generating element according to one of claims 5 to 15, characterized in that the positioning frame (2) forms transverse to the bearing plane of the PTC element (6) extending pin (26) formed in the electrical conductors (4) recesses ( 16) are engaged and form a thickening formed by melting, by which the electrical conductor tracks (4) on the position frame (2) are secured. Heat generating element according to one of claims 5 to 16, characterized in that the position frame (2) is formed as a plastic injection molded part of an insulating material. Heat generating element according to one of claims 5 to 17, characterized in that the position frame (2), the at least one PTC element (6), the electrical conductor tracks (4) and the insulating layers (8) form a preassembled structural unit. Heat-generating element according to one of claims 5 to 18, characterized in that the electrical conductor track is formed by a contact plate (4), which forms at least on one of its end faces a formed by sheet metal processing connector (22) which extends transversely to the sheet plane and received in an outwardly opening slot (24) recessed at an edge of the position frame (2). Heat generating element according to one of claims 5 to 18, characterized in that the contact plate (4) at least one of its end faces formed by sheet metal processing connector (50) ausformt provided by bending over the contact plate (4) containing plane outwardly spaced is. A heating device for air heating with a plurality of heat-generating elements (60) comprising at least one PTC element (6) and on opposite side surfaces of the PTC element (6) voltage applied electrical conductors (4) and a plurality of arranged in parallel layers heat-emitting elements (56), the held on opposite sides of the heat-generating element (60),
characterized,
in that the heat-emitting elements (56) rest on the opposite sides of the heat-generating element (56) with the interposition of an insulating layer (8). Heating device for air heating characterized by at least one heat-generating element according to one of claims 1 to 20.

Images