EP1768459B1 - Heat generating element of a heating device - Google Patents

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 conductor track through a metal strip, which is supported on the circumferentially closed metallic profile with intermediate storage of an electrical insulating layer. 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.

A generic heat generating element and a heating device according to the independent aspect of the present invention is known from EP 1 432 287 known. In this known prior art, the heater has a frame, which receives heat-emitting elements and heat-generating elements. For this purpose, the frame has the outer frame members associated spring elements which act on the alternately provided heat-emitting elements and heat-generating elements.

From the DE 28 45 894 a heat-generating element is known, which is provided between two metallic heating plates, which are connected to each other via screws. In the respective metallic plates flow channels are formed, through which a fluid flows. In order to avoid a short circuit of the voltage applied to the PTC element trace, located on the outside thereof each have an insulating layer which bears against the metallic plates. A similar heater describes the DE 30 22 034 , Also there, the PTC element is accommodated in a circumferentially closed metallic profile. Between the voltage applied to the PTC element traces and the circumferentially closed profile insulating discs are provided which prevent direct electrical contact between the tracks and the circumferentially closed profile.

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 an increased contact resistance, which may result in particular in the use of heat-generating elements in Zuheizem for motor vehicles because of the high currents that a local overheating occurs. By this thermal event, the heat-generating element can be damaged. In addition, the PTC elements are self-regulating resistance heaters, which emit a lower heat output with increased temperature, so that a local overheating can lead to the disturbance of 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, d. H. 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.

In heat-generating elements of the generic type, the PTC elements are usually arranged in a position frame which extends as a planar component substantially in the plane of the PTC elements. The position frame is used for positionally accurate positioning of the PTC elements during assembly of the heat-generating element, possibly also the support of the PTC elements in permanent operation. Although the position frame is made of plastic and as an injection molded part and thus has certain insulating properties. However, it has been shown that in generic heat-generating elements and in the application of high voltages, an electrical flashover due to low tracking resistance can not always be avoided.

There have been proposals in the art for shielding the PTC heaters from the environment. So revealed the DE 32 08 802 a heat generating element having a positioning frame and PTC heating elements sandwiched therein between opposing tracks, and this heat generating element is surrounded by a metallic capsule provided with an insulating silicone rubber tube on its inside so that the metallic capsule is not directly electrically conductive contacted with the tracks. This heat-generating element is for use in household appliances, press plates and the like and is included in a press plate for uniform dissipation of the heat generated in the heating element. There is the problem in this prior art that a uniform contact between the interconnects and the PTC elements can not always be guaranteed. Incidentally, the protection of the PTC elements from air and moisture, ie the rollover protection is effected solely by the PTC elements completely enveloping capsule, which complicates the production of heat-generating elements and not in all conceivable applications of the heat-generating elements, especially in the application the heat-generating elements may be used in an air heater in a motor vehicle.

From the US 4,327,282 is a heat-generating element is known, which is realized without position frame and in which the successively arranged PTC elements are taken together with these on both sides adjacent and forming the conductors baffles and arranged on the outside of insulating on the longitudinal sides. Through this longitudinal version of the layer structure should a sufficient contact between the PTC elements and the tracks are effected. The lateral version of the layer structure is formed by U-shaped silicone profiles, the legs of which are intended to rest on the insulating layer. However, it has been found that this can not achieve a sufficient securing of the PTC elements against penetrating moisture and air, in particular when using the heat-generating elements in an air heater of a motor vehicle. The silicone strips are also relatively soft and can be easily detached, for example, during assembly or repair work on the heater.

In an alternative, from the EP 0 026 457 known solution is the PTC heating element within a layer structure whose outer layers are each formed by an aluminum oxide layer, which clamp a conductor between itself and the PTC heating element. The aluminum oxide plates are supported on the edge of a rigid plastic frame. The track is formed by a layer of ductile solder. The application of such a solder layer but leads to manufacturing difficulties. In addition, in the operation of the heat-generating element has the problem that the solder liquefied in an inadmissible manner and causes a short circuit within the heat-generating element. Due to the rigid support of the aluminum oxide plates on the plastic frame, the previously known heat-generating element also lacks the ability within certain limits to respond flexibly to thermal expansion, so that in this prior art does not always secure contact between the conductors and the PTC heating element can be guaranteed. The same applies to the from the US 2003/0206730 known heat-generating element, in which also abut outer aluminum oxide plates on a frame surrounding the PTC elements.

In the from the US 6,178,192 known heat generating element is sandwiched between two tracks PTC element of an insulating sheath completely covered, which is formed of an electrically non-conductive plastic, so that the heat dissipation is hindered by the PTC heating element due to the poor thermal conductivity of the plastic material. The desire to form the envelope with very small wall thickness, are also limits, otherwise there is the problem that the envelope is permeable, causing the circumferential insulation would be destroyed by the PTC element. Also, the pouring of the layer structure of printed conductors and PTC elements is a time-consuming production step, which also requires curing or cooling times, whereby the manufacturing process is additionally slowed down.

With the present invention, a heat-generating element of a heater for air heating and a corresponding heating device is to be specified, which allows increased safety even when using high operating voltages. It should be paid to an economic manufacturability of the heat-generating element and thus the this installing heater. In particular, the invention seeks to provide a heat-generating element which provides improved safety against a potential electrical flashover.

To solve this problem, the present invention provides a heat-generating element having the features of claim 1. This differs from the generic state of the art in that at least one insulating layer is provided, which covers the conductor on its side facing away from the frame outside, wherein the insulating layer is in any case sealed against the longitudinal sides of the frame by a compressible Dichtwulst.

The longitudinal side of the positional frame is understood to mean, in particular, the edge of the positional frame that is oblong in plan view, ie, that marginal strip which surrounds the frame opening or the frame openings on the edge in a flat plane which forms the upper or lower side of the frame and surrounds the receiving opening , On these long sides a compressible sealing bead is provided, against which the insulating layer is tight. The compressibility of the sealing bead is chosen such that the printed conductor is pressed against the PTC elements by a compressive force applied by the insulating layer, even if, due to manufacturing tolerances and / or due to different thermal expansions of the position frame on the one hand and the electrical On the other hand, the designed dimensioning of the heat-generating element is no longer consistent with the actual dimensions. The compressible sealing bead is suitable thereafter, different thermal expansions or tolerances between the layer structure comprising the PTC element (s) and the conductor tracks and the position frame. The compressible sealing bead can compensate in the same way any tolerances on the side insulating layer, which is preferably formed from a flat ceramic plate. The ceramic plate is ideally about the width of the elongated position frame, in any case not usually extends beyond the position frame in the width direction, but is wider than the width of the frame opening. In each case a compressible sealing bead is preferably provided parallel to the two side edges of the elongated position frame between the insulating layer and the position frame, preferably substantially over the entire longitudinal extension of the elongate insulating layer. At the end faces, the insulating layer can be sealed in the same way via a compressible sealing bead relative to the position frame, so that one or all formed by the frame frame openings within the circumferential, formed by the compressible sealing beads seal and are sealed so hermetically against the outside. The heat generating element may have on both sides of the positioning frame identically provided insulating layers sealed from the positioning frame. Alternatively, the seal can be rigidly provided on one side of the position frame, for example, by an insulating layer surrounding the conductor outside, which is rigidly and firmly connected to the position frame, for example by encapsulation of the insulating layer by itself or together with the conductor track. In this case, a tolerance compensation or a compensation of different length expansions takes place exclusively on the other upper side of the position frame. There, in this case, the sealing bead is thicker to dimension than in the case of sealing beads on opposite sides of the position frame.

The heat-generating element according to the invention ensures at all times intimate contact between the track and the PTC element or elements, in particular when the elements of this electrically conductive layer structure of the heat-generating element are applied against each other by an external pressure force. Contact problems at the transition between the track and the PTC element are thus avoided.

The sealing bead can be placed on the positioning frame. With regard to a simpler Production of the heat-generating element, however, it is preferable to stick the sealing bead on the positioning frame and / or the insulating layer. The sealing bead can also bond the position frame with the insulating layer. In such a case, the sealing bead is formed, for example, of a silicone adhesive or the like.

The sealing bead is preferably formed from a highly insulating plastic, d. H. a plastic that shows a high level of safety against electrical breakdown even at high operating voltages, such as a silicone adhesive. What is desired is a highly insulating support of the PTC element or elements in the position frame with a CTI value of at least 400, preferably 600, compared to leakage current. The position frame may be formed of a plastic. In this case, the plastic should be temperature resistant. It is conceivable, for example, the production of the position frame made of polyamide. Considering a possible operating voltage of about 500 V, the support of the PTC element within the position frame should reach a CTI value of at least 600. For this purpose, preferably used materials for forming the position frame are electrically non-conductive ceramics or a high-quality plastic, such as polyurethane, silicone or other highly insulating elastomers. The electrical breakdown strength of the material forming the position frame should be at least 2 kV / mm, at least for those parts of the position frame which are immediately adjacent to and / or contact the PTC element (s).

Alternatively or additionally, the electrically highly effective insulating support of the PTC elements can take place in that an insulating gap is provided between the PTC element and the frame opening surrounding the surrounding material of the position frame. In the proposed solution according to the invention is prevented due to the insulating gap that the PTC element comes directly to the opposite inner surfaces of the position frame to the plant. The insulating gap may be an air gap that is kept between the PTC element (s) and the frame opening material. In this embodiment, care must be taken to ensure that the PTC element is circumferentially spaced from the positioning frame by a sufficient distance which prevents an electrical flashover on the position frame is.

This positioning can be carried out in particular by an insulating layer, which keeps the one or more PTC element (s) in a predetermined position, for example, by the PTC element (s) connected directly or indirectly to the insulating layer, in particular adhesively bonded. The insulating layer is also opposite the position frame, e.g. secured in position by gluing using a sealing bead. Although the bonding of the aforementioned elements is preferable from the viewpoint of easier manufacture and also from the viewpoint of sealing the current-carrying parts from the environment that can be realized by an adhesive layer, it is also possible to use the PTC element or elements (FIG. e) to space by positive engagement with respect to the position frame while maintaining the insulating gap. The insulating properties of this insulating layer are preferably chosen so that the insulating layer in the transverse direction of the layer structure ensures a dielectric strength of at least 2000 V.

In order to produce a prefabricated structural unit, a securing means embracing the insulating layer on its outer side is preferably provided. This securing means preferably surrounds only the insulating layer at its edge, so that the middle part of the insulating layer is free of securing means and in the case of the formation of the securing means by a ceramic sheet whose outside forms a flat contact surface for a heat-emitting element of a heater for air heating, in the the heat generating element according to the invention can be installed.

The securing means is designed in such a way that it generates a prestressing force pressing the conductor track against the associated PTC element and / or a pretensioning force which seals the insulating layer against the associated sealing bead. Thus, each heat generating element of a plurality of layers of heat generating elements having heating device is biased sealingly. Accordingly, a spring holding the layer structure of the heater under bias can be used alone, the heat-emitting elements against the preferably formed by the insulating outer side of the provided as a structural unit to generate heat generating elements. The spring force is not consumed to bias the compressible sealing beads ie to seal the insulating layer against the position frame. Such a development allows a more accurate interpretation of the heater. Furthermore, an electrical flashover is also reliably prevented if the layer structure of the heater under bias holding spring element fails or at least causes insufficient spring force. Also, the heat-generating and heat-emitting elements of the auxiliary heater can be placed against each other in other ways than by spring force, for example by gluing, without contact problems between the PTC element and the elements are to be feared.

The securing means may be formed by an encapsulation, which is formed on the positioning frame. The encapsulation can be formed after production of the position frame, and this material may be formed differently or identical to the material frame. Alternatively, the securing means is formed by an integrally formed on the positioning frame encapsulation, which brings with it the advantage that the securing means and the position frame can be created in one step.

Preferably, the securing means is formed by a clamping element, which surrounds the two outer sides of the heat-generating element, preferably outside bears directly against the insulating layer. The clamp element thus unites a prefabricated layer structure consisting of the position frame, the PTC element (s) received in this frame, the insulating layers sealingly applied to the position frame, and the two interconnects therebetween. In a simple embodiment, the clamp element is designed as a separate component. This development does not require a complicated technique for producing the heat-generating element. However, the parts of the layer structure and the clip elements must be positioned and joined.

In an alternative embodiment, the securing means is arranged integrally pivotable on the positioning frame and thus movable relative to the positioning frame to the insulating layer, optionally together with the conductor in pivoted Place securing means against the sealing bead and apply the insulating layer against the sealing bead due to the spring-back securing means. The securing means may in this preferred embodiment, for example, comprise two latching arms, which surround the insulating layers, which surround the frame outside the frame. These latching arms are preferably centered, that is connected at their junction via a common joint to the position frame. The joint can be formed by a film hinge. Alternatively, the joint may also have a certain rigidity to allow the movement of the locking arms for mounting, while maintaining the necessary spring force to bias the insulating layer against the compressible sealing bead. This spring force can be generated in whole or in part by the choice of material and the dimensioning of the latching arms.

With regard to the lowest possible air resistance when using the heat-generating element according to the invention in the heater is preferable to provide the locking arms frontally, d. H. at the short ends of the elongated positional frame. The height of the heat-generating element, which is usually exposed in the heater within a frame, is determined in this embodiment substantially by the height of the side wall of the position frame, which in turn substantially corresponds to the height of the PTC element received herein. The latching arms can project beyond this height, but are preferably located outside the area swept by the air to be heated and within a frame or other housing of the heating device holding the layer structure of the auxiliary heater.

According to a further preferred embodiment of the present invention, the position frame has a frame head, which projects beyond the at least one insulating layer on the outside and thereby forms a securing means at least for fixing the end of the insulating layer relative to the position frame. The position frame head may be provided substantially symmetrically with respect to the longitudinal axis of the position frame and thus form latching arms which press the insulating layers against the position frame on both sides.

The position frame head preferably has at least one passage opening for a Contact tongue, which is provided on a conductor strip forming sheet metal strip. In any case, this contact tongue preferably forms the contact sheet on one of its end faces. Usually, the contact terminal forming a plug connection is formed by free cutting of the sheet metal strip on an end face thereof, possibly deformed, so that the contact tongue extends transversely to the plane of the sheet metal. In this embodiment, the contact tongue is integrally formed on the sheet metal strip, but with significantly smaller width than the frame opening covering sheet metal strip, which bears against the PTC element. The position frame head may further have a positioning opening for the positive fixing of the sheet metal strip on the other end face.

The contact tongue may also be located in a slot which is recessed on the position frame and opens outwardly 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.

For positionally accurate positioning of the electrical conductor, the position frame further comprises in the height direction, d. H. 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. In the later merging of the heat-generating element with the heat-emitting element no longer need to be taken in the later process steps that the individual layers of the heat-generating Elementes are positioned accurately in the context of final assembly.

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 further developments described above preferably have separate sealing beads. The Dichtwülste.können but equally well integrally formed with the position frame. This realization arises in particular inevitably when the position frame is formed of an electrically high-quality material. In any case, the insulating layer can be connected on one side by encapsulation with the position frame. In particular, in this development sealing beads can be formed in an encapsulation of the insulating layer on one side of the position frame on the opposite side by means of injection, against which the insulating layer rests on the other side of the position frame. It can also integrally formed with the position frame on opposite sides of the position frame Dichtwülstemittels injection molding and the insulating layers are applied to this. Periodically, in such a case, the sealing bead will not develop the adhesive force sufficiently connecting the insulating layer to the position frame. The insulating layer can thus be placed on the sealing beads or glued or connected in any other way with the positioning frame. In particular, it is intended to clip the insulating layer to the position frame, either by means of clip elements attached to it the positioning frame are arranged, or by securing or locking means for the insulating layer, which are preferably integrally formed on the positioning frame and in particular distributed at least at the longitudinal edges of the position frame continuously or over the entire length of the position frame in discrete sections. Such a locking means may additionally be formed as a lateral fixing and mounting aid for voltage applied to the insulating heat-emitting element. Also, the locking means may be formed as a separate component relative to the position frame.

The present invention further provides a heater under protection, which makes use of the heat generating element according to the invention and accordingly can be operated at high voltages. The heater has a plurality of heat-emitting elements arranged in parallel layers, which abut opposite sides of a heat-generating element. The heat-generating and heat-emitting elements are held in a housing, for example a frame which is substantially flat and whose width substantially corresponds to the width of the heat-emitting and / or heat-generating elements. Spring voltages can be generated and / or introduced into the layer structure via the frame. For this purpose, a separate spring element integrated in the layer structure or be provided in the region of the frame. The spring may be integrated in a frame spar, such as the EP 0 350 528 can be seen. Alternatively, the spring preload can also be applied by elastic connections of frame members extending at right angles. Preferably, a plurality of heat-generating elements are provided in the layer structure, on whose upper and lower sides in each case a heat-emitting element is applied. The system can also be produced by an adhesive connection.

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 Längsschnittansicht eines Endstücks eines alternativen Ausführungsbeispiels eines erfindungsgemäßen wärmeerzeugenden Elementes;

Fig. 6

eine Querschnittsansicht des in Fig. 6 gezeigten Ausführungsbeispiels durch ein drittes Ausführungsbeispiel eines erfindungsgemäßen wärmeerzeugenden Elementes;

Fig. 7

eine Querschnittsansicht eines dritten Ausführungsbeispiels des erfindungsgemäßen wärmeerzeugenden Elementes; und

Fig. 8

eine Seitenansicht in Explosionsdarstellung eines vierten Ausführungsbeispiels eines erfindungsgemäßen wärmeerzeugenden Elementes;

Fig. 9

das linke stirnseitige Ende des in Fig. 8 gezeigten Ausführungsbeispiels;

Fig. 10

eine Querschnittsansicht eines fünften Ausführungsbeispiels des erfindungsgemäßen wärmeerzeugenden Elementes; und

Fig. 11

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 in Fig. 1 embodiment shown;

Fig. 3

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

Fig. 4

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

Fig. 5

a longitudinal sectional view of an end piece of an alternative embodiment of a heat generating element according to the invention;

Fig. 6

a cross-sectional view of in Fig. 6 embodiment shown by a third embodiment of a heat generating element according to the invention;

Fig. 7

a cross-sectional view of a third embodiment of the heat generating element according to the invention; and

Fig. 8

an exploded side view of a fourth embodiment of a heat generating element according to the invention;

Fig. 9

the left frontal end of the in Fig. 8 shown embodiment;

Fig. 10

a cross-sectional view of a fifth embodiment of the heat generating element according to the invention; and

Fig. 11

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 in an 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-layer insulating layer 8, comprising an outer insulating film 10 and an inner, directly adjacent to the contact plate 4 ceramic plate 12. The ceramic plate 12 is a relatively thin alumina plate, which has 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 polyamide film having a good thermal conductivity of about 0.45 W / (m K) and a dielectric strength of 4 kV / mm. 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, there is no risk that the relatively brittle ceramic layer breaks.

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 formed with a smaller width than the insulating layer 8. 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. To the in Fig. 1 Right end, the contact plate 4 has a 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, in relation 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 in particular in Fig. 1 and 4 can be seen, the positioning frame 2 in addition to the pin 26 further positioning aids for 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 bounding edge 30 is surmounted on both sides by limiting webs 32 with inner locking 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 Fig. 3 results in - 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 it turned out Fig. 1 results, 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. By the insulating gap 38 thereafter, the current-carrying parts of the heat-generating element, ie, the two contact plates 4 and the PTC elements 6 are spaced from the material of the positioning frame 2. This distance is in the embodiment shown the Fig. 1 to 4 secured by an insulating spacer 40 which circumferentially surrounds the front end of the inner edge 38. 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 rim 42 formed circumferentially around the frame opening 34 formed by the inner edge 38. The spacer means 40 may thereafter also be referred to as the inner frame opening 34 circumferentially surrounding edge umkleidender insulating jacket can be understood, which prevents 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 minimum distance between the ensured parts.

In addition to an electrical insulation of the current-carrying parts of the heat-generating element offers in the Fig. 1 to 4 embodiment shown also a complete encapsulation of these parts. For this purpose, the insulating layer has a transverse direction ( Fig. 3 ) on both sides over the contact plate 4 extending edge portion 44. Between this edge portion 44 and the inner edge 38 of the position frame 2 is a sealing bead 46, which is applied sealingly against both the position frame 2 and against the insulating layer 8. In the circumferential direction, ie in the width direction, the encapsulation then has the insulating layers 8 lying opposite one another and the arrangement of two sealing elements 46 extending substantially at right angles thereto with the material of the positional frame 2 provided therebetween. The encapsulation is chosen so that no moisture or contamination from the outside can reach the live parts.

The sealing bead 46 is formed by a plastic adhesive, which fixes the insulating layer 8 with respect to the position frame 2 and thus includes all provided within the insulating layers 8 parts of the heat-generating element. 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 bead 46 in the form of an adhesive. In particular Fig. 2 can be seen, the sealing bead 46 extends in the longitudinal direction of the position frame and is provided between the outer edge of the frame opening 34 and the boundary edge 30. The sealing element bears against the inner edge 38, which is reduced in thickness. Immediately adjacent to the sealing element 46 is on the outside a Dichtmittelbegrenzungsrand 48 is provided, which is formed by the positioning frame 2. With a view to the best possible sealing, the sealing bead 46 can rest against this edge, which extends transversely to the receiving plane for the PTC elements.

The FIGS. 5 and 6 show an alternative embodiment of a heat generating element according to the invention with a positioning frame 2, on which the present lower contact plate 4u is arranged by encapsulation. After the injection-molding production of the positioning frame 2, this forms a unit together with the lower contact plate 4u. For this purpose, the contact plate 4u can have recesses or openings at its edge, through which the highly insulating plastic mass forming the position frame can flow during injection molding and thus can connect the contact plate 4 to the position frame 2. The lower contact plate 4u is at its ends to the center of the position frame out, so that the contact plate 4u is securely surrounded by the frame 2 forming the material. In the embodiment shown, the positioning frame 2 is made of an electrically high-quality, temperature-resistant (200 ° C) silicone. The embodiment then has a CTI value that ensures safe operation at voltages of about 500V.

At the in Fig. 6 In the embodiment shown, the position frame is produced while retaining the basic structure already described with reference to the previous embodiments, in which a sealing adhesive edge 46 is provided between the material of the positioning frame 2 and the insulating layer 8, which is presently formed from an elastomeric adhesive. With the interposition of this adhesive strip 46, the mutual insulating layers 8 abut against the positioning frame 2. In this case, the voltage applied to the lower insulating layer 8u strip 46 in particular serves the adhesive connection. Its sealing properties are not so important. The insulating layer 8 can also be glued alternatively or in addition flat on the outside of the contact plate 4u.

But there are also alternative embodiments possible, in which both the electrical conductor 4u and the adjoining insulating layer 8u in an injection molding are inserted and overmolded by the highly insulating plastic mass of the positioning frame 2 ( Fig. 7 ). After removal from the mold, the PTC elements 6 are inserted into the frame openings 34. On the opposite side, an electrical conductor 4 is now applied to the PTC element (s) 6. With an adhesive edge 46 with sealing function, the immediately applied to this electrical conductor 4 insulating layer 8 is connected to the position frame 2. Otherwise corresponds to in Fig. 7 shown and the modification described here with respect to the positioning of the contact sheet (s) 4 and the formation of the contact elements at the or the front end (s) of the position frame 2 the embodiments described above.

The FIGS. 8 and 9 show a fourth embodiment of a heat generating element according to the invention. Identical components are identified with the same reference numerals with respect to the preceding embodiments.

In the in the FIGS. 8 and 9 In the embodiment shown, the PTC elements 6 are accommodated in two frame openings 34 of an elongated position frame 2. The PTC elements 6 can bear directly on the edge of the frame 2 surrounding the frame openings 34. Between the frame openings 34 and the oblong side edge of the positioning frame 2, there are also two sealing beads 46 in the form of a band-shaped glued-on silicone strip which projects beyond the upper side of the positional frame. In the embodiment shown, the opposite upper sides of the sealing beads 46 are approximately at the level of the top of the PTC elements. In other words, the two sealing beads 46 together with the thickness of the positioning frame 2 at this lateral edge thereof have a height which corresponds approximately to the height of the PTC elements.

At both front ends of the positioning frame 2, the positioning frame 2 is provided on both sides with superior positioning frame heads 100, which form positioning aids for positionally accurate arrangement of the contact sheets 4. Each of the contact plates 4 has its front ends cut out tongues, wherein the left tongue forms the male connector terminal 50 and on the right side only a positioning tongue 102 is provided, which is on all sides insulating received by the right position frame 100 in a recessed therein positioning opening 104, so that the contact plate 4 is held in position secured in position in the longitudinal and transverse direction relative to the position frame 2. The position frame head 100 further has a through hole 105 for the male terminal 50.

The position frame heads 100 also form securing means in the form of latching arms 106, which surround the insulating layer 8 on the outside, on its end face. The latching arms 106 are articulated via a common torsion joint 108 on the immovable part of the position frame head 100. When mounting the in the FIGS. 8 and 9 In the embodiment shown, the latching arms 106 can be pivoted about this torsion joint 108, so that the opposing latching arms 106 release a free space between them, which can just accommodate the insulating layer 108 formed as a flat ceramic plate. After relief of the torsion joint 108 swing the locking arms back and overlap the insulating layer 106. In this case, the insulating layer 8 is biased toward the position frame 2 with the interposition of the sealing bead 46.

That in the FIGS. 8 and 9 embodiment shown may be formed on one side with correspondingly detent against the position frame 2 battered insulating 8, whereas on the other side, the insulating layer and / or the contact plate 4 may be secured in a manner to the positioning frame 2, as already described above with reference to the FIGS. 6 and 7 has been described.
In Fig. 10 a further modified embodiment is shown. Also in this embodiment, the same components with respect to the previously discussed embodiments are provided with the same reference numerals.

In the embodiment shown, the sealing beads 46 are formed integrally on opposite side surfaces of the positioning frame 2 on the positioning frame 2 formed as an injection molding component. In the embodiment shown, the position frame 2 is injection molded from silicone. The PTC elements 6 are inserted in this frame 2. The insulating layers 8 are placed on both sides of the sealing bead 46. The recorded within the position frame 2 components, contact plate 4th and PTC elements 6 are clamped between the insulating layers 8. These in turn are biased against each other via separate clamping elements 62, which may be formed for example by C-shaped plastic clips, both bias the insulating layers 8 against each other with the interposition of the position frame 2 and the relatively soft and labile position frame 2 serve as a lateral boundary, so that the positioning frame 2 can not bulge outward substantially in the bearing plane of the PTC elements 6. Accordingly, the clamping elements 62 are arranged distributed at predetermined intervals over the entire longitudinal extension of the positioning frame 2 in any case. The cooperating with the insulating layer 8 locking projections of the clip elements 62 may be associated with locking recesses or detents which are mounted on the side of the insulating layer. Also, the locking projections may be connected by gluing with the insulating layer 8. Conceivable is any configuration that prevents the practical use of the heat generating element on the one hand slipping of the clip elements 62 of the surface of the insulating layer 8 and on the other hand, a possible flat contact the heat-emitting elements on the outside of the insulating layer 8 is not hindered.

In Fig. 11 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 60 (for example Fig. 1 to 4 ). 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 60. In the Fig. 11 shown heat-emitting elements 56 are formed by meandering bent aluminum sheet metal strips. The heat-generating elements 60 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.

The force of the spring received in the frame 52 may be such that not only the heat-generating elements 60 and the heat-emitting elements 56 are braced against each other, but also the corresponding sealing beads 46 sealingly biased against the insulating layer 8 and the positioning frame 2, respectively be pressed. The sealing effect can be generated solely by spring force. In addition, the individual heat-generating elements can be provided under bias clamping clip elements or other securing means. It is also possible to adhesively adhere the sealing bead to the insulating layer and / or the position frame. In this case, in any case due to the bias of the spring received in the frame of the sealing bead is compressed and the contact plate 4 flush against the top of the PTC element 6 is applied in order to achieve good contact there. It goes without saying that on the position frame recessed lead-through or positioning opening 104, 105 are dimensioned in this case so that they allow a certain mobility of the contact plate 4 for compression of the sealing bead 46.

At the in FIG. 11 the embodiment shown, the heat-emitting elements, ie the radiator elements, potential-free, since this rests with the interposition of the insulating layer 8 against the current-carrying parts. 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.

Since the heat-emitting elements 56 rest with the interposition of an insulating layer 8 against the current-carrying parts, the heat-emitting elements 56, ie 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.

Although in the in the FIGS. 8 and 9 1, the mounting surface for the sealing bead 46 superior, molded on the positioning frame 2 mounting edge 30 is missing, the lateral surface of the heat-generating element is formed in this embodiment, the side surface to be recognized in the side view substantially by the side wall of the position frame. In the embodiment of the FIGS. 8 and 9 the contact surface for the sealing bead 46 on the side of the positioning frame 2 is surmounted only by the relatively thin sealing bead 46 and the thin ceramic plate 8. It should be noted that in the FIGS. 8 and 9 embodiment shown has a perfectly smooth and continuous in the width direction of the heat-generating element surface. The attachment of the ceramic plate 8 to the position frame 2 is carried out only on the provided on the front side locking arms 106. If the thus applied contact pressure is not sufficient to press the ceramic plate 8 in the central region of the sealing bead 46, so there is a corresponding contact force and thus shielding the PTC elements with respect to the air flowing to the heat generating elements when installing the same in a housing, preferably a frame due to the spring bias of the pressed together in the frame layer.

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 bead

48

Sealant boundary edge

50

connector

52

frame

54

frame shell

56

heat-emitting element

58

along longwall

60

heat generating element

62

clip element

100

position head

102

position arms

104

position opening

105

Through opening

106

locking arms

108

torsion

Claims (27)

1. Heat-generating element of a heating device for heating air, comprising at least one PTC element (6), electric strip conductors (4) lying on the PTC element (6) and a longish positioning frame (2) that forms at least one frame opening (34) for holding the at least one PTC element (6),
   characterised in that
   at least one insulating layer (8) that covers the strip conductors (4) on their exterior side facing away from the positioning frame (2) is provided, and
   in that the insulating layer (8) is sealed against the positioning frame (2) at least the long sides thereof by at least one compressible sealing bead (46).
2. Heat-generating element according to Claim 1, characterised in that the sealing bead (46) is formed continuously along the length of the positioning frame (2).
3. Heat-generating element according to Claim 1 or Claim 2, characterised in that the sealing bead (46) is glued on to the positioning frame (2).
4. Heat-generating element according to any one of the preceding Claims, characterised in that the sealing bead (46) is glued to the insulating layer (8).
5. Heat-generating element according to any one of the preceding Claims, characterised in that the sealing bead (46) is made from a highly insulating plastic material.
6. Heat-generating element according to any one of the preceding Claims, characterised by a securing means (42, 106) that encompasses the insulating layer (8) along the edge of the exterior side.
7. Heat-generating element according to Claim 6, characterised in that the securing means (62, 106) creates a pre-tensioning force that presses the strip conductor (4) against the assigned PTC element (6) and / or a pre-tensioning force that holds the insulating layer (8) against the assigned sealing bead (46) in a way that forms a seal.
8. Heat-generating element according to Claim 6 or Claim 7, characterised in that the securing means (106) is formed by moulding around the positioning frame (2).
9. Heat-generating element according to Claim 8, characterised in that the moulded around securing means (106) is formed as a single piece on the positioning frame (2).
10. Heat-generating element according to any one of Claims 6 to 9, characterised in that the securing means (106) is formed by a clamp element (62) that encompasses at least the one exterior side of the heat-generating element (60).
11. Heat-generating element according to Claim 10, characterised in that the clamp element (62) is formed as a separate component.
12. Heat-generating element according to Claim 10 or Claim 11, characterised in that the clamp element (62) encompasses the heat-generating element (60) on both sides.
13. Heat-generating element according to any one of Claims 6 to 12, characterised in that the securing means (106) is formed on to the positioning frame (2) as a single piece and in such a way that it is pivotable relative to the positioning frame (2).
14. Heat-generating element according to any one of Claims 6 to 13, characterised in that the securing means comprises two locking arms (106) that encompass the insulating layers (8) surrounding the outside of the positioning frame (2), said locking arms (106) being connected to the middle of the positioning frame (2) via a shared hinged joint (108).
15. Heat-generating element according to Claim 14, characterised in that the locking arms (106) encompass the insulating layers (8) on the face side.
16. Heat-generating element according to any one of the preceding Claims, characterised by at least one positioning frame head (100), which is formed frontally on the positioning frame (2) and which projects beyond the insulating layers (8) on the exterior and / or top sides and positions these layers with respect to the positioning frame (2).
17. Heat-generating element according to Claim 16, characterised in that the positioning frame head (100) forms at least one lead-through opening (105) for a contact tongue (50) that is provided on one of the strips of metal (4) forming the strip conductor.
18. Heat-generating element according to Claim 16 or 17, characterised in that the positioning frame head (100) supports the locking arms (106).
19. Heat-generating element according to any one of the preceding Claims, characterised in that one of the insulating layers (8) and / or the strip conductor (4) covered by this insulating layer (8) is secured to the positioning frame (2) by moulding around and is sealed with respect to this positioning frame (2) at least in lengthwise direction thereof, and in that the insulating layer (8) provided on the opposite side of the positioning frame (2) lies against the positioning frame (2), with the compressible sealing bead (46) being placed in between.
20. Heat-generating element according to any one of the preceding Claims, characterised in that the insulating layer (8) is formed by a flat ceramic plate.
21. Heat-generating element according to any one of the preceding Claims, characterised in that the insulating layer (8) is essentially provided with the width of the positioning frame (2).
22. Heat-generating element according to any one of the preceding Claims, characterised in that the heat-generating element (60) is formed as a layered, prefabricated unit comprising the positioning frame (2), the two insulating layers (8) attached thereto in such a way as to form a seal, the two electric strip conductors (4) provided in between, and the at least one PTC element provided in between.
23. Heat-generating element according to Claim 22, characterised in that the side surface of the layered unit is essentially formed by the side wall of the positioning frame (2).
24. Heating device for heating air, with multiple heat-generating elements (60) comprising at least one PTC element (6), electric strip conductors (4) lying on the PTC element (6) and at least one longish positioning frame (2) that forms a frame opening (34) for holding the at least one PTC element (6) and several heat-emitting elements (56) arranged in parallel layers, said heat-emitting elements (56) being held so that they lie on opposing sides of the heat-generating element (60), characterised by at least one heat-generating element according to any one of Claims 1 to 23.
25. Heating device according to Claim 24, characterised in that the heat-emitting elements (56) are held in a frame (52) with an initial tension so that they lie on the heat-generating elements (60).
26. Heating device according to Claim 24 or Claim 25, characterised in that the insulating layer (8) of the at least one heat-generating element (60) is positioned against the assigned sealing bead (46) in a manner that forms a seal under the force of a spring that effects the spring bias in the frame.
27. Heating device according to Claim 24 or Claim 25, characterised in that a heat-emitting element (56) lies directly on the exterior side of the insulating layer (8) of the assigned heat-generating element (60).

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