Heating element and electric heating system with at least one such heating element

Abstract

The invention relates to a heating element (1) with a carrier film (4), with two heating groups (5, 6), each having at least one heating zone (7) with PTC heating layers (9), and with at least two contact elements (10) arranged on the carrier film (4) for electrically contacting the PTC heating layers (9). The contact elements (10) each have a first, comb-shaped conductor structure (11) with electrically conductive contact electrodes (12) and a second, comb-shaped conductor structure (13) with electrically conductive contact electrodes (14) that interlock like fingers. Each heating group (5, 6) is assigned at least one contact element (10) such that the contact electrodes (12, 14) of a contact element (10) are electrically connected to at least the PTC heating layers (9) of the at least one heating zone (7) of a respective heating group (5, 6).The heating element (1) further comprises at least three electrically conductive busbars (16, 17, 18) which are electrically conductively connected to the two conductor structures (11) of the at least two contact elements (10). The invention also relates to an electric heating system (2) comprising at least one such heating element (1).

Description

The present invention relates to a heating element for an electric heating system according to the subject matter of claim 1.Heating elements are used in particular in cabin heaters or air conditioning devices of modern electric vehicles in order to heat cabin air to a temperature predefined by users of the vehicle. The known heating elements generally have ceramic PTC heaters (PTC positive temperature coefficients), in particular PTC thermistors, which ensure reliable operation in particular because of their current-limiting electrical properties (an electrical resistance which increases exponentially with the temperature). The disadvantage of the PTC heaters, in particular the PTC thermistors, is their high weight, the often complicated electrical connection and electrical insulation and the installation possibilities, which are thus structurally limited, in a cabin heater or an air-conditioning device. In addition, conventional PTC heaters, in particular the PTC thermistors, have portions of lead, which is undesirable for environmental reasons.The object of the invention is therefore to provide an improved or at least one other embodiment of a heating element. Furthermore, an electric heating system with at least one such heating element is to be specified.In the present invention, these objects are achieved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims, the description and the drawings.The first-mentioned object is achieved by a heating element for an electric heating system having a strip-shaped carrier film extending along a longitudinal axis and having at least two heating groups provided at a distance from one another in the direction of the longitudinal axis, each of which heating groups has at least one heating zone with strip-shaped PTC heating layers arranged flat on the carrier film and provided at a distance from one another in a line-up direction. The proposed heating element furthermore has at least two contact elements arranged on the carrier film for electrically contacting the PTC heating layers. The contact elements each have a first comb-shaped conductor structure with electrically conductive contact electrodes and a second comb-shaped conductor structure with electrically conductive contact electrodes, which engage in one another in a finger-like manner. Furthermore, each heating group of the at least two heating groups is assigned at least one contact element of the at least two contact elements. The assignment is realized in such a way that the contact electrodes of a contact element are aligned in a transverse direction running orthogonally to the line-up direction and / or are electrically conductively connected at least to the PTC heating layers of the at least one heating zone of a respective heating group. The heating element furthermore has at least three electrically conductive busbars arranged on the carrier film, wherein a first busbar of the at least three busbars is assigned to a first electrical potential and each further busbar of the at least three busbars is assigned to a second electrical potential different from the first electrical potential. Furthermore, it is provided that the first busbar of the at least three busbars is electrically conductively connected to the first conductor structures of the at least two contact elements and that each further busbar of the at least three busbars is assigned to a single heating group of the at least two heating groups and is electrically conductively connected to at least the one second conductor structure of the at least one contact element of a respective heating group. This provides a low-cost, lightweight heating element with a comparatively high power density. By the indicated electrical connection of the PTC heating layers by means of the contact elements and busbars, the area available on the carrier film can also be optimally utilized and / or individual controllability of the heating groups can be realized in such a way that the heating powers (heat emission per unit time) provided by the heating groups during operation of the proposed heating element can be adjusted independently of one another. This makes it possible for the heating powers of the heating groups of the proposed heating element to be flexibly adaptable to a heat requirement required in the region of a respective heating group.The strip-shaped carrier film is expediently designed to be flexible in the manner of a film, as a result of which the heating element can be adapted to arbitrarily shaped, in particular curved, surface contours. As a result, the proposed heating element has a relatively broad spectrum of use. In particular, it can be integrated in a space-saving manner in a heating system, in particular a cabin heater or an air-conditioning device of an electric vehicle. The carrier film can be produced from a plastic material, which facilitates cost-effective fabrication of the proposed heating element.The first electrical potential may be a positive potential. The second electrical potential is, for example, a negative electrical potential, an electrical ground potential or a basic electrical potential. A difference between the first electrical potential and the second electrical potential may have a high voltage level.It is conceivable for the strip-shaped carrier film to have a base body which extends along the longitudinal axis and is realized as a cuboidal film body. The base body or the film body can have two end narrow surfaces opposite one another in the direction of the longitudinal axis, furthermore two side narrow surfaces opposite one another in the direction of a depth direction perpendicular to the longitudinal axis, and furthermore two large surfaces opposite one another in a vertical direction perpendicular to the longitudinal axis and perpendicular to the depth direction. Expediently, the at least two heating groups of the heating element, the at least two contact elements of the heating element and the busbars of the heating element are arranged on a first large surface of the two large surfaces of the base body or of the film body of the carrier film and / or on a second large surface of the two large surfaces of the base body or of the film body of the carrier film.Furthermore, it is expedient if the PTC heating layers of the heating zones of the heating groups each generate the same heating powers. This can be achieved by the PTC heating layers each being identical. For example, they have identical layer thicknesses and / or identical layer areas. The layer surfaces result from a layer depth of a PTC heating layer and a layer width of the PTC heating layer, which are orthogonal to one another. Furthermore, the layer thickness of the PTC heating layer is orthogonal to the layer depth and the layer width.Expediently, it is provided that the PTC heating layers of the heating zones of the at least two heating groups are designed as organic PTC heating layers. The organic PTC heating layers can each have an electrically conductive, organic active material or be formed by such an active material. The active material has a positive temperature coefficient of the electrical resistance, as a result of which a PTC effect is generated, by means of which the said PTC heating layers conduct the current better at low temperatures than at higher temperatures. In these PTC heating layers, the electrical resistance increases significantly with temperature in a relatively narrow temperature window, so that they have a current-limiting effect and can be used, for example, as a heating element. Said active material can have a material composition with or made of, for example, an organic polymer.In particular, it is provided that the longitudinal axis and the line-up direction are oriented orthogonally or parallel to one another. This results in two different configurations of the heating elements. In the first design, in which the longitudinal axis and the line-up direction are orthogonal to one another, the strip-shaped PTC heating layers arranged on the carrier film are thus lined up one behind the other transversely to the longitudinal axis. As a result, during operation of the proposed heating element, in which the heating element is flushed by air moving in a flow direction oriented transversely to the longitudinal axis, the PTC heating layers are sequentially acted upon with air. This has the advantage that the PTC heating layers of a heating zone each operate at a temperature level, i.e. they do not see a temperature distribution along their respective extent. In the second design, in which the longitudinal axis and the line-up direction are parallel to one another, the strip-shaped PTC heating layers arranged on the carrier film are thus lined up one behind the other along the longitudinal axis. As a result, during operation of the proposed heating element, in which the heating element is flushed by air moving in a flow direction oriented transversely to the longitudinal axis, the PTC heating layers are continuously acted upon with air along their respective extent. This has the advantage that the PTC heating layers of a heating zone each see a temperature distribution along their respective extent.It is further expediently provided that the heating zones of the at least two heating groups have an even number or an odd number of PTC heating layers. This achieves favorable use of the surface area, so that a heating power provided by the proposed heating element or by the heating groups of the heating element is maximized. In addition, a space-saving interconnection of the PTC heating layers can thereby be realized.In particular, it can be provided that the carrier film has at least three electrical connections which are arranged on a side edge of the carrier film. It is expedient here if the first busbar of the at least three busbars is connected to a first electrical connection and each further busbar of the at least three busbars is connected to a respective further electrical connection of the at least three electrical connections.In this context, it can be provided that the at least three electrical connections are arranged on the carrier film in two groups spaced apart from one another in such a way that the first electrical connection which has the first electrical potential forms a first group of these two groups and the further electrical connections which each have the second electrical potential form a second group of these two groups.In other words, electrical potentials of the same name are thereby combined, wherein the spacing of the groups from one another simplifies the electrical contacting of the proposed heating element via the connection contacts. It is understood that the two groups are galvanically separated from each other, so that they can have different potentials.Furthermore, it can be provided that each heating group of the at least two heating groups has a plurality of separate heating zones, wherein each heating group of the at least two heating groups is assigned a number of contact elements which corresponds to the number of heating zones of a respective heating group of the at least two heating groups. Thus, the number of contact elements of the heating element corresponds to the number of heating zones of the heating element. In this case, the contact elements assigned to a heating group of the at least two heating groups are each assigned to a single heating zone of this heating group, and the contact electrodes of these contact elements are electrically conductively connected exclusively to the PTC heating layers of a respective heating zone.Alternatively, it can be provided that each heating group of the at least two heating groups has a plurality of separate heating zones, wherein exactly one single contact element is assigned to each heating group of the at least two heating groups. Thus, the number of contact elements of the heating element corresponds to the number of heating groups of the heating element. For the electrical contacting of the heating zones, it is expedient if the contact element assigned to a heating group of the at least two heating groups is arranged on the heating zones of this heating group in such a way that the contact electrodes of this contact element are electrically conductively connected to all PTC heating layers of these heating zones. This specifies preferred connections of the PTC heating layers, by means of which the area available on the carrier film can be optimally utilized.In particular, it can be provided that at least one temperature sensor for detecting the temperature of the carrier film and / or an air flow of air moving in a flow direction oriented transversely to the longitudinal axis is arranged on the carrier film. The operation of the proposed heating element can be monitored, for example regulated, by means of the at least one temperature sensor. The at least one temperature sensor can be arranged on an outflow side of the carrier film. For a space-saving arrangement, the at least one temperature sensor can furthermore be integrated into the carrier film in the region of a PTC heating layer of a heating zone arranged on the outflow side of the carrier film.The object mentioned at the beginning is achieved by an electric heating system, in particular as a component of a cabin heating system or as a component of an air conditioning device of an electric vehicle, having at least one heating element according to the preceding description and a duct through which an air stream of air flows. The at least one heating element is arranged flat on the channel such that during operation of the heating system heat provided by the at least one heating element is transferred from the at least one heating element to the air flow of air flowing through the channel. Optionally, it can be provided that the electric heating system is equipped with a further duct through which an air stream of air flows, wherein the at least one heating element is arranged in a planar manner on the further duct in such a way that the at least one heating element is arranged in a sandwich-like manner between the duct and the further duct and, during operation of the heating system, heat provided by the at least one heating element is transferred from the at least one heating element to the air stream of air flowing through the further duct. This specifies an advantageous heating system having at least one heating element. To improve the heat transfer, heat exchanger ribs, for example heat exchanger ribs of zigzag configuration, can be provided in the channel or in the channel and the further channel. The heat exchanger ribs are each arranged parallel to a flow direction of the air flow of air in the channel and / or a flow direction of the air flow of air in the further channel, so that the heat exchanger ribs are favorably surrounded by air.To summarize, the invention relates preferably to a heating element having a carrier film, having two heating groups, each of which has at least one heating zone having PTC heating layers, and having at least two contact elements arranged on the carrier film for electrically contacting the PTC heating layers. It is provided that the contact elements each have a first comb-shaped conductor structure with electrically conductive contact electrodes and a second comb-shaped conductor structure with electrically conductive contact electrodes, which engage in one another in a finger-like manner. Each heating group is assigned at least one contact element in such a way that the contact electrodes of a contact element are electrically conductively connected at least to the PTC heating layers of the at least one heating zone of a respective heating group. The heating element furthermore has at least three electrically conductive busbars which are electrically conductively connected to the two conductor structures of the at least two contact elements. The invention also relates to an electrical heating system comprising at least one such heating element.Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention. The above-mentioned components of a superordinate unit, such as a device, a device or an arrangement, which are designated separately, can form separate components or components of this unit or can be integral regions or sections of this unit, even if this is illustrated differently in the drawings.Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally the same components.In each case, diagrammatically show, FIG. 1 shows a greatly simplified heating system according to a first embodiment, FIG. 2 shows a greatly simplified heating system according to a second embodiment, FIG. 3 shows a heating element according to a first embodiment in a plan view, FIG. 4 shows a heating element according to a second embodiment in a plan view, FIG. 5 shows a heating element according to a third embodiment in a plan view, FIG. 6 shows a heating element according to a fourth embodiment in a plan view, FIG. 7 shows a heating element according to a fifth embodiment in a plan view, FIG. 8 shows a heating element according to a sixth embodiment in a plan view, FIG. 9 shows a heating element according to a seventh embodiment in a plan view and last FIG. 10 shows a heating element according to an eighth embodiment in a plan view.FIG. 1 shows an electric heating system according to a first embodiment, which is denoted overall by the reference numeral 2 and is provided in particular in a cabin heater or an air-conditioning device of an electric vehicle for the targeted heating of cabin air to a temperature predefined by users of the vehicle. The proposed electric heating system 2 has an electric heating element 1 and a duct 29 through which air flows in a flow direction 31 by an air stream 32. The heating element 1 is arranged flat on the channel 29 so that during operation of the heating system 2 heat provided by the heating element 1 is conductively transferred from the heating element 1 to the channel 29 and then from the channel 29 to the air flow 32 flowing through the channel 29.FIG. 2 shows a heating system 2 according to a second embodiment. In contrast to the embodiment according to FIG. 1, it has, in addition to the electric heating element 1 and the channel 29, a further channel 30 through which air flows. A heat exchanger rib, not illustrated here, provided for improving the heat transfer can likewise be inserted into the further channel 30. The heating element 1 is positioned in a sandwich-like manner between the channel 29 and the further channel 30 and is arranged flat on the one hand on the channel 29 and on the other hand on the further channel 30. As a result, during operation of the heating system 2, heat which is provided by the heating element 1 can be conductively transferred from the heating element 1 to the duct 29 and the further duct 30 and then transferred from the duct 29 to the air stream 32 flowing through the duct 29 and from the further duct 30 to the air stream 32 flowing through the further duct 30.FIG. 3 shows an electrical heating element denoted overall by the reference numeral 1 according to a first, schematic embodiment in a plan view. The heating element 1 has a carrier film 4 which is of strip-like shape and extends along a longitudinal axis 3. The carrier film 4 is designed to be elastically flexible in the manner of a film, as a result of which the heating element 1 can be adapted to almost arbitrarily shaped, in particular curved, surface contours of an electric heating system 2, in particular a cabin heating system or an air conditioning device of an electric vehicle. As a result, the proposed heating element 1 has a relatively broad spectrum of use. The carrier film 4 has a (film) base body which is preferably produced from a plastic material and which has mutually opposite end narrow surfaces in the direction of the longitudinal axis 3, furthermore two side narrow surfaces which are mutually opposite in the direction of a depth direction perpendicular to the longitudinal axis 3 and furthermore two large surfaces which are mutually opposite in a vertical direction perpendicular to the longitudinal axis 3 and perpendicular to the depth direction, of which only one large surface 33 is visible in FIG. 3.In order to be able to provide heat, the electric heating element 1 in the present case has two heating groups 5, 6 which are provided at a distance from one another in the direction of the longitudinal axis 3 and are each indicated in FIG. 3 by a dashed box. It is understood that instead of two heating groups 5, 6, alternatively three, four or more such heating groups could be provided. It can be seen directly in FIG. 3 that the heating groups 5, 6 each have exactly three separate heating zones, which are each indicated in FIG. 3 by a dashed box and are each denoted by the reference numeral 7 for the sake of better clarity.The heating zones 7 form the regions of the heating element 1 that are actually thermally active and each have a plurality of, here exactly four, PTC heating layers 9 (PTC positive temperature coefficient) arranged flat on the large surface 33 of the carrier film 4 and arranged one behind the other at regular distances from one another along a line-up direction 8, which is indicated by an arrow in FIG. 3. In this case, the PTC heating layers 9 each have a main extent oriented transversely to the line-up direction 8, which is also understood here as the layer width, a layer depth oriented orthogonally to the main extent, and a layer thickness oriented orthogonally to the layer depth and orthogonally to the main extent. The PTC heating layers 9 of one heating zone 7, or of all heating zones 7, are designed identically to one another, so that their main extents, layer depth and layer thicknesses are the same. This ensures that the PTC heating layers 9 of one heating zone 7, or of all heating zones 7, can generate the same heating powers. Furthermore, the PTC heating layers 9 are designed as organic PTC heating layers. Accordingly, they comprise or are formed by an electrically conductive, organic active material. The active material has a positive temperature coefficient of the electrical resistance, as a result of which a PTC effect is generated, by means of which the said PTC heating layers 9 conduct the current better at low temperatures than at higher temperatures. Moreover, in these PTC heater layers 9, the electric resistance significantly increases with temperature in a relatively narrow temperature window, so that they have a current-limiting effect. For the sake of better clarity, FIG. 3 shows only the PTC heating layers 9 of a single heating zone 7 with reference numerals. It should also be mentioned that the heating zones 7 in the present case have an even number of PTC heating layers 9.The heating element 1 has at least one or more contact elements 10 for electrically contacting the PTC heating layers 9 per heating group 5, 6, wherein a total of six such contact elements 10 are provided in the present case, wherein three contact elements 10 are assigned to each heating group 5, 6, wherein the contact elements 10 assigned to a heating group 5, 6 are each arranged on a heating zone 7. The contact elements 10 each have a first comb-shaped conductor structure 11 and a second comb-shaped conductor structure 13. The first conductor structure 11 has mutually parallel, electrically conductive contact electrodes 12, each having a free end and being connected at the foot to a conductor structure busbar of the first conductor structure 11 running orthogonally to the contact electrodes 12. The second conductor structure 13 is constructed analogously to the first conductor structure 11 and has mutually parallel, electrically conductive contact electrodes 14, each having a free end and being connected at the foot side to a conductor structure busbar of the second conductor structure 13 running orthogonally to the contact electrodes 14. The conductor structures 11, 13 are arranged in such a way that their contact electrodes 12, 14 engage one another in a finger-like manner with a mutual spacing.According to FIG. 3, it is provided that the contact elements 10 are arranged on the heating zones 7 of the heating groups 5, 6 in such a way that the contact electrodes 12, 14 of the contact elements 10 are aligned in a transverse direction 15 running orthogonally to the line-up direction 8 and are each electrically conductively connected to the PTC heating layers 9 of a single heating zone 7 of a respective heating group 5, 6.It can also be seen in FIG. 3 that the heating element 1 has three electrically conductive busbars 16, 17, 18 arranged on the large surface 33 of the carrier film 4, which busbars serve for the electrical contacting of the contact elements 10. It is provided that a first busbar 16 is assigned a first, positive electrical potential 20, a second busbar 17 is assigned a second, negative electrical potential 21, different from the first electrical potential 20, and the second, negative electrical potential 21 is assigned a third busbar 18. Furthermore, the first busbar 16 is electrically conductively connected to the first conductor structures 11 of all contact elements 10 of the heating groups 5, 6. The first conductor structures 11 of the contact elements 10 therefore likewise have the first, positive electrical potential 20. In this case, the second and third collecting conductors 17, 18 are electrically conductively connected to the second conductor structures 13 of the contact elements 10 of a respective heating group 5, 6. In other words, the second busbar 17 is assigned exclusively to the left-hand, second heating group 6 in the present case and is connected to the conductor structures 13 of the contact elements 10 of this second heating group 6. The third bus bar 18 is in the present case assigned exclusively to the right-hand first heating group 5 and is connected to the conductor structures 13 of the contact elements 10 of this first heating group 5. This provides a low-cost, lightweight heating element with a comparatively high power density. By the indicated electrical connection of the PTC heating layers 9 by means of the contact elements 10 and busbars 16, 17, 18, the area available on the carrier film 4 can be optimally utilized and individual controllability of the heating groups 5, 6 can be realized.Furthermore, it should be mentioned that, in the embodiment illustrated in FIG. 3, the longitudinal axis 3 and the line-up direction 8 of the PTC heating layers 9 are oriented orthogonally with respect to one another. This results in a design of the heating element 1, in which the strip-shaped PTC heating layers 9 arranged on the carrier film 4 are arranged one behind the other orthogonally to the longitudinal axis 3. As a result, during operation of the proposed heating element 1, in which the heating element 1 is flushed by air by an air stream 32 moving in a flow direction 31 oriented transversely to the longitudinal axis 3, the PTC heating layers 9 are acted upon sequentially, that is to say in succession, with air. As a result, a PTC heating layer 9 arranged upstream in the air flow 32 sees a comparatively cool air flow 32, that is to say a lower temperature level, while a further PTC heating layer 9 arranged downstream in this respect experiences a comparatively warm air flow 32, that is to say a higher temperature level. This can result in different temperature loads for the individual PTC heating layers 9 of a heating zone 7.The carrier film 4 also has three electrical connections 22, 23, 24, which are arranged on a side edge 25 of the carrier film 4. In this case, the first busbar 16 of said three busbars 16, 17, 18 is connected to a first electrical connection 22, the second busbar 17 of said three busbars 16, 17, 18 is connected to a second electrical connection 23, and the third busbar 18 of said three busbars 16, 17, 18 is connected to a third electrical connection 23. The lateral arrangement of the three electrical connections 22, 23, 24 on the side edge 25 facilitates the mounting of the heating element 1.FIG. 4 shows a heating element 1 according to a second, schematic embodiment in a plan view. The heating element 1 differs from the preceding embodiment illustrated in FIG. 3 in particular in that only a single contact element 10 is assigned to each heating group 5, 6. In this case, the contact elements 10 are arranged on the heating zones 7 of the heating groups 5, 6 in such a way that the contact electrodes 12, 14 of the contact elements 10 extend over the PTC heating layers 9 of the heating zones 7 of a respective heating group 5, 6, which heating layers are arranged one behind the other in the longitudinal axis 3, or electrically conductively connect the PTC heating layers 9 of the heating zones 7 of a respective heating group 5, 6, which heating layers are arranged one behind the other.As a result, fewer contact elements 10 are required for the electrical contacting of the PTC heating layers 9.FIG. 5 shows a heating element 1 according to a third, schematic embodiment in a plan view. The heating element 1 differs from the first embodiment illustrated in FIG. 3 in particular in that each heating zone 7 has an odd number of PTC heating layers 9 instead of an even number of PTC heating layers 9. Specifically, the heating zones 7 have exactly five PTC heating layers 9 which are arranged flat on the large surface 33 of the carrier film 4 and are arranged one behind the other at regular distances from one another and are aligned parallel to one another and are strip-shaped or rectangular.FIG. 6 shows a heating element 1 according to a fourth, schematic embodiment in a plan view. The heating element 1 differs from the first embodiment illustrated in FIG. 3 in particular in that, as in the preceding embodiment according to FIG. 5, each heating zone 7 has an odd number of PTC heating layers 9 instead of an even number of PTC heating layers 9. Specifically, the heating zones 7 have exactly five PTC heating layers 9 which are arranged flat on the large surface 33 of the carrier film 4 and are arranged one behind the other at regular distances from one another and are aligned parallel to one another and are strip-shaped or rectangular. Furthermore, the present embodiment is characterized in that the three electrical connections 22, 23, 24 are arranged on the carrier film 4 in two groups 26, 27 spaced apart from one another. In this case, the first electrical terminal 22, which has the first electrical potential 20, forms a first group 26 of these two groups 26, 27. the two other electrical terminals 23, 24, which each have the second electrical potential 21, form the other group 27. By combining the electrical potentials of the same name and by spacing the groups 26, 27 from one another, the electrical contacting of the proposed heating element 1 can be simplified.FIG. 7 shows a heating element 1 according to a fifth, schematic embodiment in a plan view. The heating element 1 differs from the first embodiment illustrated in FIG. 3 in particular in that the heating element 1 has a fourth, electrically conductive busbar 19 arranged on the large surface 33 of the carrier film 4, which busbar, together with the remaining busbars 16, 17, 18, serves for the electrical contacting of the contact elements 10. It is provided that the fourth busbar 19 has the first, positive electrical potential 20, as is the first busbar 16. The fourth busbar 19 is electrically conductively connected to the first conductor structures 11 of the contact elements 10 of the left, second heating group 6. The first conductor structures 11 of the contact elements 10 therefore likewise have the first, positive electrical potential 20. Furthermore, the fourth bus bar 19 is likewise led to the side edge 25 of the carrier film 4 and is provided there with a fourth electrical connection 34 for the electrical contacting of the heating element 1. A further difference compared to the first embodiment illustrated in FIG. 3 can be that the longitudinal axis 3 and the line-up direction 8 are oriented parallel to one another.FIG. 8 shows a heating element 1 according to a sixth, schematic embodiment in a plan view. The heating element 1 differs from the first embodiment illustrated in FIG. 3 in particular in that the longitudinal axis 3 and the line-up direction 8 are parallel to one another. As a result, the strip-shaped PTC heating layers 9 arranged on the carrier film 4 are arranged one behind the other along the longitudinal axis 3, wherein their main extents are oriented orthogonally to the longitudinal axis 3. As a result, during operation of the heating element 1, in which the heating element 1 is flushed by air by said air flow 32 moving in a flow direction 31 oriented transversely to the longitudinal axis 3, the PTC heating layers 9 are continuously acted upon with air along their respective main extent. This has the advantage that the PTC heating layers 9 of the heating zones 7 each see a temperature distribution along their respective extent, wherein an upstream region of a respective PTC heating layer 9 sees a colder air stream 32 than a region of this PTC heating layer 9 arranged further downstream.FIG. 9 shows a heating element 1 according to a seventh, schematic embodiment in a plan view. The heating element 1 differs from the first embodiment illustrated in FIG. 3 in particular in that a single heating group 5 having a single heating zone 7 is provided on the carrier film 4, wherein the five PTC heating layers 9 of the heating zone 7 are electrically contacted analogously to the preceding embodiments by means of a single contact element 10 which has two conductor structures 11, 13 with contact electrodes 12, 14 engaging one another in fingerlike fashion. Furthermore, a first bus bar 16 having a first, positive electrical potential 20 is provided, as is a second bus bar 17 having a second electrical potential 21. The first busbar 16 is electrically conductively connected to the first conductor structure 11 of the contact element 10. The second busbar 17 is electrically conductively connected to the second conductor structures 13 of the contact element 10. The first and second bus bars 16, 17 are led to a side edge 25 of the carrier film 4 and are each provided there with an electrical connection 22, 23 for the electrical contacting of the heating element 1. It should also be mentioned that the heating element 1 has, via a temperature sensor 28 arranged on the carrier film 4 for detecting the temperature of the carrier film 4 and / or the temperature of the air stream 32 of air moving in a flow direction 31 oriented transversely to the longitudinal axis 3. For a space-saving arrangement of the temperature sensor 28 on the carrier film 4, it is provided that the last PTC heating layer 9 of the heating zone 7, viewed in the direction of the flow direction 31, is shortened transversely to the line-up direction 8, wherein the region on the carrier film 4 thus exposed defines a placement surface 35 for arranging the temperature sensor 28.FIG. 10 shows a heating element 1 according to an eighth, schematic embodiment in a plan view. The heating element 1 differs from the embodiment illustrated in FIG. 9 in particular in that the longitudinal axis 3 and the line-up direction 8 are parallel to one another, as in the embodiment according to FIG. 8, for example. As a result, the strip-shaped PTC heating layers 9 arranged on the carrier film 4 are line-up one behind the other along the longitudinal axis 3, wherein their main extents are aligned orthogonally to the longitudinal axis 3. As a result, during operation of the heating element 1, in which the heating element 1 is flushed by air by said air flow 32 moving in a flow direction 31 oriented transversely to the longitudinal axis 3, the PTC heating layers 9 are continuously acted upon with air along their respective main extent. This has the advantage that the PTC heating layers 9 of the heating zones 7 each see a temperature distribution along their respective extent, wherein an upstream region of a respective PTC heating layer 9 sees a colder air stream 32 than a further downstream region of this PTC heating layer 9. For the space-saving arrangement of the temperature sensor 28 on the carrier film 4, it is provided in the present case that two adjacent PTC heating layers 9 of the heating zone 7 are shortened in the direction of the flow direction 31, wherein the region on the carrier film 4 thus exposed defines a placement surface 35 for the arrangement of the temperature sensor 28.List of reference characters1 Heating element 2 Heating system 3 Longitudinal axis 4 Carrier film 5 First heating group 6 Second heating group 7 Heating zones 8 Line-up direction 9 PTC heating layers 10 Contact element 11 First conductor structure 12 Contact electrodes 13 Second conductor structure 14 Contact electrodes 15 Transverse direction 16 First collecting conductor 17 Second collecting conductor 18 Third collecting conductor 19 Fourth collecting conductor 20 First electrical potential 21 Second electrical potential 22 First electrical terminal 23 Second electrical terminal 24 Third electrical terminal 25 Side edge of the carrier film 26 First group 27 Second group 28 Temperature sensor 29 Channel 30 Further channel 31 Flow direction 32 Air flow 33 Large surface 34 Fourth electrical terminal 35 Mounting surface

Claims

Heating element (1) for an electric heating system (2), - with a strip-shaped carrier film (4) extending along a longitudinal axis (3), - with at least two heating groups (5, 6) provided at a distance from one another in the direction of the longitudinal axis (3), which each have at least one heating zone (7) with strip-shaped PTC heating layers (9) arranged flat on the carrier film (4) and at a distance from one another along a line-up direction (8), - with at least two contact elements (10) arranged on the carrier film (4) for electrically contacting the PTC heating layers (9), which each have a first comb-shaped conductor structure (11) with electrically conductive contact electrodes (12) and a second comb-shaped conductor structure (13) with electrically conductive contact electrodes (14), which engage one another in the manner of fingers, - wherein each heating group (5, 6) of the at least two heating groups (5, 5), The arrangement of at least one contact element (10) is assigned to the at least two contact elements (10) in such a way that the contact electrodes (12, 14) of a contact element (10) are aligned in a transverse direction (15) running transversely to the line-up direction (8) and are electrically conductively connected at least to the PTC heating layers (9) of the at least one heating zone (7) of a respective heating group (5, 6), - with at least three electrically conductive busbars (16, 17, 18) arranged on the carrier film (4), - wherein a first busbar (16) of the at least three busbars (16, 17, 18) is assigned to a first electrical potential (20) and each further busbar (17, 18) of the at least three busbars (16, 17, 18) is assigned to a second electrical potential (21) different from the first electrical potential (20), - wherein the first busbar (16) of the at least three busbars (16, 17, 18), 18) is electrically conductively connected to the first conductor structures (11) of the at least two contact elements (10), - wherein each further busbar (17, 18) of the at least three busbars (16, 17, 18) is assigned to a single heating group (5, 6) of the at least two heating groups (5, 6) and is electrically conductively connected to at least the one second conductor structure (13) of the at least one contact element (10) of a respective heating group (5, 6).Heating element (1) according to claim 1, characterised in that - the PTC heating layers (9) of the heating zones (7) of the at least two heating groups (5, 6) are formed as organic PTC heating layers.Heating element (1) according to claim 1 or 2, characterised in that - the longitudinal axis (3) and the line-up direction (8) are aligned orthogonally or parallel to one another.Heating element (1) according to one of the preceding claims, characterized in that - the heating zones (7) of the at least two heating groups (5, 6) have an even number or an odd number of PTC heating layers (9).Heating element (1) according to one of the preceding claims, characterized in that - the carrier film (4) has at least three electrical connections (22, 23, 24) which are arranged on a side edge (25) of the carrier film (4), - wherein the first busbar (16) of the at least three busbars (16, 17, 18) is connected to a first electrical connection (22) and each further busbar (17, 18) of the at least three busbars (16, 17, 18) is connected to in each case a further electrical connection (23, 24) of the at least three electrical connections (22, 23, 24).Heating element (1) according to claim 5, characterised in that - the at least three electrical connections (22, 23, 24) are arranged on the carrier film (4) in two groups (26, 27) spaced apart from one another in such a way that the first electrical connection (22), which has the first electrical potential (20), forms a first group (26) of these two groups (26, 27) and the further electrical connections (23, 24), which have the second electrical potential (21), form a second group (27) of these two groups (26, 27).Heating element (1) according to one of the preceding claims, characterized in that - each heating group (5, 6) of the at least two heating groups (5, 6) has a plurality of separate heating zones (7), - wherein each heating group (5, 6) of the at least two heating groups (5, 6) is assigned a number of contact elements (10) which corresponds to the number of heating zones (7) of a respective heating group (5, 6) of the at least two heating groups (5, 6), - wherein the contact elements (10) assigned to a heating group (5, 6) of the at least two heating groups (5, 6) are each assigned to a single heating zone (7) of this heating group (5, 6) and the contact electrodes (12, 14) of these contact elements (10) are electrically conductively connected exclusively to the PTC heating layers (9) of a respective heating zone (7).Heating element (1) according to one of claims 1 to 6, characterised in that - each heating group (5, 6) of the at least two heating groups (5, 6) has a plurality of separate heating zones (7), - wherein each heating group (5, 6) of the at least two heating groups (5, 6) is assigned exactly one single contact element (10), - wherein the contact element (10) assigned to a heating group (5, 6) of the at least two heating groups (5, 6) is assigned to the heating zones (7) of this heating group (5, 6) and the contact electrodes (12, 14) of this contact element (10) are electrically conductively connected to the PTC heating layers (9) of these heating zones (7).Heating element (1) according to one of the preceding claims, characterized in that - at least one temperature sensor (28) for detecting the temperature of the carrier film (4) and / or an air stream (32) of air flowing over the heating element (1) in a flow direction (31) oriented transversely to the longitudinal axis (3) is arranged on the carrier film (4).Electric heating system (2), in particular as a component of a cabin heater or as a component of an air-conditioning device of an electric vehicle, having - at least one heating element (1) according to one of the preceding claims and a duct (29) through which an air stream (32) of air flows, - wherein the at least one heating element (1) is arranged in a planar manner on the duct (29) in such a way that, during operation of the heating system (2), heat which is provided by the at least one heating element (1) is transferred from the at least one heating element (1) to the air stream (32) of air flowing through the duct (29), and - optionally with a further duct (30) through which the air stream (32) of air flows, wherein the at least one heating element (1) is furthermore arranged in a planar manner on the further duct (30) in such a way, the at least one heating element (1) being arranged in a sandwich-like manner between the channel (29) and the further channel (30), and heat provided by the at least one heating element (1) being transferred from the at least one heating element (1) to the air stream (32) of air flowing through the further channel (30) during operation of the heating system (2).

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