DE102018100742A1 - Heating device with a plurality of electric surface heating elements - Google Patents

Abstract

The invention relates to a heating device (10) having a plurality of electric surface heating elements (18) and to a holding device which holds the surface heating elements (18) such that the surface heating elements (18) can be overflowed by a fluid to be heated. The respective surface heating element (18) comprises a carrier body (22) on which at least one resistance element (28) is arranged, which can be acted upon by electrical energy for heating the fluid. The carrier body (22) is formed from at least one plastic.

Description

The invention relates to a heating device with a plurality of electric surface heating elements and with a holding device which holds the surface heating elements such that the surface heating elements can be overflowed by a fluid to be heated. The respective surface heating element comprises a carrier body on which at least one resistance element is arranged. For heating the fluid, the resistance element can be acted upon by electrical energy.

The DE 100 32 099 C1 describes an electric booster heater for heating air flowing into an interior of a vehicle. In this case, formed on substrate strips, which are formed of ceramic or metal, formed from a resistor paste webs. In addition, at least one side of the carrier material strip is in heat-conducting contact with a heat dissipation body formed of metal, which is formed as a corrugated metal strip. Accordingly, electrical insulation is required between the tracks formed from the resistor paste and the heat dissipation body. If the carrier strip is formed of metal, then an additional electrical insulating layer between the strip of carrier material and the tracks formed from the resistor paste is provided.

A disadvantage here is the fact that such an air heater is constructed comparatively complex and thus expensive.

Object of the present invention is therefore to provide a particularly simple design heater of the type mentioned.

This object is achieved by a heating device having the features of patent claim 1. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

The heating device according to the invention comprises a plurality of electric surface heating elements and a holding device. The holding device holds the surface heating elements such that the surface heating elements can be overflowed by a fluid to be heated. The fluid may in particular be air, so that the heating device can be used as an air heater, for example as an electric booster heater for heating air supplied to a passenger compartment of a motor vehicle. The respective surface heating element comprises a carrier body on which at least one resistance element is arranged. For heating the fluid, the at least one resistance element can be acted upon by electrical energy. The carrier body is formed from at least one plastic. This makes it possible to dispense with a separate electrical insulation layer between the carrier body and the resistance element. Because the carrier body is formed from the at least one plastic, so no insulation film or the like between the carrier body and the resistance element needs to be arranged. Therefore, the heater is particularly simple.

Furthermore, a large-area arrangement of the at least one resistance heating element on the support body is possible, so that a very good and rapid heating of the fluid flowing over the surface heating elements during operation of the heating device can be achieved. This applies in particular in comparison to resistor elements designed as PTC elements, which are to be bonded in a complex manner to a carrier body and, in addition to the dissipation of the heat, require an arrangement of heat-dissipation bodies in the form of corrugated metal strips. In the present case, such heat-dissipating bodies can be dispensed with, since already the flat resistance elements of the heating device ensure good heat dissipation to the fluid during operation of the heating device. This also contributes to the particularly simple construction of the heater.

The simple structure of the heater, it is further beneficial that the carrier body is formed from the at least one plastic. Because so the carrier body can be very simple and little effort. Advantageously, the plastic is characterized by a high corrosion resistance.

Preferably, the carrier body is formed as a thermoset. Such a carrier body has several advantageous properties with respect to the heating device.

On the one hand, the carrier body formed from a thermoset is characterized by a low absorption of moisture, whereby it is at most weakly swellable. This is advantageous for an efficient heating operation of the heater. Furthermore, the carrier body formed as thermoset is preferably neither fusible nor soluble and has a high chemical resistance. Furthermore, the low thermal expansion coefficient of the carrier body is advantageous. This brings a high degree of dimensional stability, which is conducive to the heating of the heater and for the assembly of the heater.

In addition, the fire behavior of a formed as a thermoset carrier body is advantageous, and he has a high mechanical strength at high Temperatures up to the range of 180 ° C. Furthermore, the carrier body formed from a thermoset is characterized by a high corrosion resistance.

Thus, although in sum the benefits of a thermoset outweigh, so can other plastics are used, which have at least a portion of the advantageous properties for use in the heater properties.

By using the carrier body formed from the at least one plastic material, from which the fluid flowing over the electrical surface heating elements directly decreases the heat, fall in comparison to that from the DE 100 32 099 C1 known air heater several components and complex manufacturing steps away. In particular, by providing a substantially flat coating of the surfaces of the carrier body which can be overflowed by the fluid with the at least one resistance element, provision can be made for the provision of the method described in US Pat DE 100 32 099 C1 described heat dissipation body are completely omitted, or such heat sink body can be reduced. As a result, the flowability of the heater for the fluid is improved. Nevertheless, the fluid can be heated very quickly and efficiently.

In addition, a manufacturing process for providing the surface heating elements or the heating device is particularly largely simplified. For example, the application of the at least one resistance element to the carrier body with a desired layout can be accomplished very simply automatically, for example by application, in particular by means of a printing technique such as screen printing and / or by spraying or spraying.

The formation of the carrier body from the at least one plastic also makes it possible in a particularly simple manner to provide the surface heating elements with additional turbulence elements, which cause the fluid to flow over the surface heating elements in a turbulent manner. As a result, the heat transfer from the surface heating elements to the fluid can be improved or the air flow rate during operation of the heating device can be optimized with regard to heat transfer to the fluid, in particular to the air.

As described above, therefore, the at least one plastic is preferably formed as a thermoset. Because thermosets show no softening even in the high temperatures occurring in the heating mode of the heater. Such a material thus maintains its mechanical strength even at high temperatures. As thermosetting polyester and / or a synthetic resin can be used in particular. As further advantageous, it has been shown, if in the at least one plastic reinforcing fibers, such as glass fibers, are embedded. This too is conducive to high mechanical stability of the carrier body.

The at least one resistance element is preferably designed as a dispersion applied to at least one surface of the carrier body. This is because the at least one resistance element can be applied with little effort and simply applied to the surface of the carrier body, for example by printing, in particular screen printing and / or spraying, in particular spraying.

The dispersion may in particular comprise carbon particles distributed in a dispersion medium. The use of such a carbon dispersion is particularly simple since the dispersion only needs to be dried in order to achieve a good bond with the plastic carrier body. For example, drying may occur at a temperature of about 150 degrees Celsius. The manufacturing process is thereby significantly easier than, for example, in the case of a burn-in, which is required when providing a resistance element in thick-film technology. In addition, a complex gluing can be omitted, as is necessary when attaching a PTC module (PTC = positive temperature coefficient, positive temperature coefficient).

For example, the dispersant may comprise at least one acrylate in which the carbon particles are dispersed. A size of the carbon particles is preferably less than five microns. In particular, the carbon particles may be formed as carbon nanotubes. However, it is also possible to use graphite or carbon particles formed from graphite. The comparatively small particle size of the carbon particles means that a very uniform layer thickness of the resistance element can be achieved. This results in the operation of the heater to a particularly uniform heating of the fluid or the air, so to an improved temperature uniformity.

The at least one resistance element is preferably applied flat on at least one surface of the carrier body. This makes it very easy to ensure that in the heating operation of the heater electrical current flows through the resistive element, even without a high precision when applying the at least one resistive element is required on the support body.

Additionally or alternatively, the at least one resistance element in the form of a Plural of separate, electrically parallel and / or electrically connected in series tracks to be applied to the at least one surface of the carrier body. Thus, it can be avoided that the electric current during operation of the heating device preferably flows through partial areas of a planar resistance element which have a lower electrical resistance than adjacent partial areas of the planar resistance element. The desired electrical resistance of the at least one resistance element can be adjusted in particular by providing a specific layer thickness of the resistance element.

Preferably, an electrically insulating protective layer is arranged on an upper side of the at least one resistance element facing the fluid. Thus, a particularly safe handling of the heater is possible, in particular, a touch of the resistance element is not associated with a risk. The protective layer is preferably apolar and may in particular comprise silicone. In particular, the protective layer may be formed as a silicone mixture, for example as a silicone resin. Furthermore, it is preferred if the protective layer is free of solvents. Also, a two-component silicone, which is preferably solvent-free, may be used to provide the protective layer. Such a two-component silicone includes a silicone rubber and a crosslinking agent. By such, in particular silicone having protective layer can be achieved very easily a desired electrical insulation of the resistive element.

Preferably, a thickness of the protective layer is in the range between 20 microns and 100 microns. The thickness of the protective layer may in particular be about 50 micrometers. A protective layer having such a thickness does not hinder the heat dissipation of the resistance heating elements formed, for example, as heating layers. Nevertheless, even with such a very thin protective layer, a dielectric strength for a voltage of up to 1500 volts can be ensured. In particular, the protective layer may have a dielectric strength of at least 15 kilovolts per millimeter.

A very regular layer thickness of the electrically insulating protective layer can be achieved if the protective layer is applied to the resistor element by screen printing and / or spraying. By such a uniform thickness of the protective layer can be a local overheating avoid or ensure a very uniform heat dissipation from the resistor element.

Preferably, the at least one resistance element is electrically conductively connected to a collecting device arranged on at least one surface of the carrier body, which has a lower electrical resistance than the resistance element. Thus, the electric current can be supplied to the resistance element via the collecting device and be removed from the resistance element via a further collecting device. The collecting device thus serves the electrical contacting of the resistive element.

As collecting means, in particular a material which can be applied to the carrier body in a planar manner or in webs can be used, for example a silver conductive paste, a highly conductive plastic, a copper conductive paste, a paste containing carbon particles or the like. By using such a pasty material to provide the at least one collecting device, the supply and removal of electrical current to the resistive element or from the resistive element can be realized in a particularly simple manner in terms of production technology. This can be done, for example, by the pasty material is applied by a printing process, for example by screen printing, on the carrier body, wherein the electrically conductive contact is made with the resistive element.

Preferably, the collecting device is electrically conductively connected to an electrical conductor arranged on the holding device. For example, as an electrical conductor, a metal sheet or a metal strip, a cable or the like may be injected into a material of the holding device or pressed or punched. The electrical conductor thus serves to supply or dissipate the electric current and may be formed, for example, of copper and / or of an aluminum alloy or the like.

In particular, the electrical conductor may include a leading to a power supply or voltage source line and at least one spring element which is connected to the line, for example, is soldered to the line. By providing at least one such spring element can be achieved that the electrical conductor is connected to form a surface pressure with the collecting device.

For example, a pre-bent metal part may be connected to the electrical line, and the pre-bent metal part, through which the spring element is formed, presses against the collector due to the mechanical tension of the spring element. So can be a very reliable electrical contacting of the Flächenheizelemente be ensured.

Additionally or alternatively, the electrical conductor may be materially connected to the collecting device. By way of example, the electrical conductor can be connected to the collecting device by gluing, by means of a conductive paste, in particular silver conductive paste, by soldering and / or lasers. For this purpose, terminals of the electrical conductor may have a contact surface on which the cohesive connection is made with the collecting device.

A cohesive connection between the electrical conductor and the collecting device can furthermore be provided, for example by an electrically highly conductive silicone contacting the collecting device on the one hand and an electrical line arranged in the holding device, for example in the form of a metal sheet, a metal strip and / or a cable. The electrically conductive silicone can be applied by means of a metering device and thus automatically at the desired location.

Furthermore, an electrical contacting of the collecting device by means of a ring contact element is possible. For this purpose, in the plastic material of the carrier body, a hole or a through hole may be formed, through which a metal pin is passed, which projects beyond the carrier body to one side or to both sides. On such a metal pin, an annular contact element can be attached, which can then be attached to a nut and / or by clips or clips and / or by gluing, by caulking or the like.

For electrical contacting of the collecting device, a metal part, for example produced by punching, can furthermore be arranged in the holding device such that the metal part is in contact with the collecting device and a connection which can be connected to an electrical line is provided by the metal part.

Due to the design of the carrier body made of plastic can be provided by the plastic material, in particular at one end a thickening having, pin or rod, which passes through the collecting device. An annular contact element may be attached to such a pin or bar, such as by attaching the annular contact element to the pin or bar having the thickening by clipping. Thus, an electrical contact between the collecting device and the annular contact element of the electrical conductor can be produced in a particularly simple manner. In particular, this also gives a simple mechanical solubility of the electrical contact.

For producing an electrically conductive connection between an electrical voltage supply or voltage source and the collecting device, a bonding method may also be used, for example in the form of aluminum bonding and / or copper bonding. In this case, several thin aluminum strands or copper strands distributed over the width of the collector are soldered, which then bundled the stream out an electrical conductor. Advantageously, the collecting device is contacted not only at one point and a single faulty contacting hardly affects the power supply. As a bonding method, for example, the thermosonic bonding or preferably the ultrasonic bonding can be used. Due to the low operating temperature, such a bonding method is significantly more advantageous compared to soldering, which takes place at temperatures well above 200 ° C, and therefore could destroy or damage the plastic substrate.
Furthermore, pins, in particular rivet-shaped pins, can be used as contact elements of the electrical conductor, which can be connected to the collecting device by gold bonding, thick-wire bonding, in particular aluminum thick-wire bonding, and the like.

Preferably, the surface heating elements are held exchangeably on the holding device. As a result, for example, in case of failure, the surface heating elements concerned can be easily replaced. This increases the ease of maintenance or repair friendliness of the heater.

For example, the surface heating elements can be inserted into grooves, which are formed on the one hand in a base part of the holding device and on the other hand in a cover part of the holding device. Thus, a secure and at the same time non-destructively detachable arrangement of the surface heating elements is achieved on the holding device.

However, in particular by the arrangement of the grooves, an orientation of the surface heating elements can also be specified. For example, the surface heating elements can be arranged obliquely or even perpendicular to the inflow direction, ie to the flow direction of the fluid flowing through the heating device. Preferably, however, the surface heating elements are arranged parallel to the flow direction of the fluid. This is because a particularly good heat transfer to the fluid flowing past the surface heating elements can be achieved.

In an arrangement of the Flächenheizelemente obliquely, in particular perpendicularly, to the flow direction of the fluid and a plurality of relatively staggered surface heating elements or plate-shaped carrier body can be arranged with the at least one resistive element in the flow direction of the fluid through the heater in a row. However, even with an arrangement of the surface heating elements parallel to the flow direction, several of the surface heating elements can be arranged offset one behind the other in the flow direction in order to achieve good heat transfer from the surface heating elements to the fluid flowing past.

The holding device may be designed in the manner of a frame on which the preferably plate-like surface heating elements are arranged, in particular are arranged interchangeable. Such a frame may in particular comprise the base part and the cover part, so that the holding device may be modular. In particular, a plastic may be used as the material for the holding device, for example polybutylene terephthalate (PBT) and / or at least one polyamide, for example PA6.6 or PA66. This also makes the provision of the holding device particularly inexpensive and inexpensive.

Finally, it has proven to be advantageous if the respective surface heating element comprises at least one electrical fuse element. For example, can be provided as a fuse element, a fuse, or it can be used a melt paste, which is in electrical contact with the resistive element. It is also conceivable that the fuse is formed by a portion of the resistive element formed as a heating layer or the collecting means itself.

If such a fuse is present on each carrier or carrier strip, a failure affects only a single carrier strip, and the remaining surface heating elements can continue to perform their function.

In particular, as a fuse element, which is intended to prevent only temporary temperature increases beyond a critical level addition, a PTC thermistor (PTC element), in particular a resettable PPTC (polymeric positive temperature coefficient) can be used.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention. Thus, embodiments are also included and disclosed by the invention, which are not explicitly shown or explained in the figures, however, emerge and can be produced by separated combinations of features from the embodiments explained. Thus, embodiments and combinations of features are also to be regarded as disclosed which do not have all the features of an originally formulated independent claim. Moreover, embodiments and combinations of features, in particular by the embodiments set out above, are to be regarded as disclosed which go beyond the feature combinations set out in the back references of the claims or deviate therefrom.

• 1 schematisch einen Lufterhitzer mit Flächenheizelementen, welche parallel zur Strömungsrichtung der den Lufterhitzer im Betrieb durchströmenden Luft ausgerichtet sind;
• 2 schematisch eine Anordnung von als Heizflächen ausgebildeten Widerstandselementen auf einem jeweiligen Trägerkörper der Flächenheizelemente des Lufterhitzers gemäß 1;
• 3 eine weitere Möglichkeit der Anordnung von Heizbahnen auf dem Trägerkörper;
• 4 eines der Flächenheizelemente des Lufterhitzers, wobei die Heizfläche mittels einer Schutzschicht abgedeckt ist;
• 5 eine schematische Schnittansicht eines der Flächenheizelemente und die elektrische Kontaktierung desselben;
• 6 Metallfedern zum elektrischen Kontaktieren der Flächenheizelemente;
• 7 weitere Möglichkeiten der elektrischen Kontaktierung der Flächenheizelemente;
• 8 die Verwendung eines elektrischen leitfähigen Silikons zum Kontaktieren der Flächenheizelemente;
• 9 weitere Komponenten, welche dem elektrischen Kontaktieren der Flächenheizelemente des Lufterhitzers dienen;
• 10 in einer Schnittansicht eine weitere Möglichkeit der elektrischen Kontaktierung der Flächenheizelemente;
• 11 eine Variante der elektrischen Kontaktierung, bei welcher ein Kontaktring mit einem Stift elektrisch leitend verbunden wird, indem der Stift verstemmt wird; und
• 12 ein Sicherungselement zur elektrischen Absicherung des Lufterhitzers.

Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and from the drawings. Showing:

• 1 schematically an air heater with surface heating elements, which are aligned parallel to the flow direction of the air heater in operation flowing through the air;
• 2 schematically an arrangement of heating elements designed as heating elements on a respective carrier body of the surface heating of the air heater according to 1 ;
• 3 a further possibility of arranging heating tracks on the carrier body;
• 4 one of the surface heating elements of the air heater, wherein the heating surface is covered by a protective layer;
• 5 a schematic sectional view of the surface heating elements and the electrical contacting thereof;
• 6 Metal springs for electrically contacting the surface heating elements;
• 7 further possibilities of electrical contacting of the surface heating elements;
• 8th the use of an electrically conductive silicone to contact the surface heating elements;
• 9 other components which serve to electrically contact the surface heating elements of the air heater;
• 10 in a sectional view, a further possibility of electrical contacting of the surface heating elements;
• 11 a variant of the electrical contact in which a contact ring is electrically connected to a pin by the pin is caulked; and
• 12 a fuse element for electrical protection of the air heater.

1 shows highly schematically a heating device in the form of an air heater 10 , The air heater 10 For example, it can be used as an electric heater in a motor vehicle in order to heat air to be introduced into a passenger compartment. The air heater 10 includes one present as a frame 12 trained holding device, which is a lower part 14 or base part and a cover part 16 trained upper part comprises. In the frame 12 are a plurality of surface heating elements 18 held. Through gaps 20 between the surface heating elements 18 can during operation of the air heater 10 the air to be heated flow.

Furthermore, the air to be heated in the operation of the air heater 10 through gaps 20 flow between the frame 12 and those surface heating elements 18 are formed, which immediately adjacent to the frame 12 are arranged. If instead of air, another fluid is to be heated, so can through these spaces 20 also flow another fluid.

In the present case, the surface heating elements 18 arranged parallel to the flow direction, in which the air to be heated through the interstices 20 passes. In variants of the air heater 10 can the surface heating elements 18 also be arranged obliquely or perpendicular to this flow direction. Furthermore, it can be provided that in the interstices 20 Heat conducting approximately in the form of fins or the like extend, which in heat-conducting connection with the surface heating elements 18 are. Due to the below explained in more detail embodiment of the surface heating 18 However, it is also possible to dispense with such heat-conducting elements in the present case, as this 1 can be seen.

According to, for example 2 include the respective surface heating elements 18 a plate-shaped carrier body 22 whose narrow side 24 through the air heater 10 facing passing air flow or fluid flow. Consequently, the air to be heated or heated flows over surfaces in the form of broadsides 26 the carrier body 22 (see 2 ). On at least one of these, but preferably on both of these end faces or narrow sides 24 adjacent broadsides 26 are respective resistive elements 28 arranged. These electrical resistance elements 28 serve to heat the air when the resistance elements 28 during operation of the air heater 10 be charged with electrical energy. In the present case comes as a heating layer, through which the resistance elements 28 are formed, preferably a carbon dispersion used, which on at least one of the broadsides 26 trained surfaces of the respective carrier body 22 is applied.

How out 2 further, this heating layer or the resistance element can 28 flat on the broadside 26 of the carrier body 22 be applied (upper illustration in 2 ). However, it is also possible that at least one resistance element 28 in the form of separate, electrically connected in parallel and / or electrically connected in series tracks on the surface of the carrier body 22 to apply (compare 2 , middle illustration). Furthermore, the heating layer can meander-shaped or in different turns on the surface of the carrier body 22 be upset (compare 2 , lower illustration).

Also from 3 is such a meandering course of trained as a heating layer or heating element resistance element 28 out. Here, individual strands of the heating track are arranged parallel to each other, wherein respective ends of the strands with conductor tracks 30 are electrically connected, which is the electrical contacting of the heating layer or the heating tracks, so the at least one resistive element 28 serve. To provide these tracks 30 For example, a silver conductive paste, a copper conductive paste, a highly conductive plastic or the like may be used, which may be applied to the carrier body 22 is applied.

The carrier body 22 of the respective surface heating element 18 In the present case, it is formed from at least one plastic, preferably from a thermosetting plastic, which may be reinforced with reinforcing fibers, for example glass fibers. As a result, in contrast to a surface heating element with a metallic carrier body between the support body and the resistance element 28 no electrical insulation layer to be provided.

Out 4 it can be seen that the conductor tracks 30 supplying electrical current to the at least one resistance element 28 or serve to dissipate the electric current and are thus designed as a current collector or collecting devices. The collection devices in the form of printed conductors 30 may also be formed as a dispersion or paste with a high carbon density. The tracks 30 can at a certain distance from serving as a heating surface at least one resistive element 28 be contacted by terminals and / or screws or the like electrically.

Furthermore, it is off 4 it can be seen that the heating layer or the preferably flat resistance element 28 (see 2 ) on its upper side facing the air with an electrically insulating protective layer 32 is provided.

The protective layer 32 preferably has silicone, or may be formed as a silicone mixture or as a two-component silicone. Preferably, the protective layer becomes 32 with a thickness between 20 microns and 100 microns, in particular with a thickness of about 50 microns on the support body 22 applied. This is how the protective layer works 32 the heat emission of the heating layers or resistive elements 28 not hindered, and yet a high dielectric strength is ensured. With a very uniform thickness, the protective layer can be 32 provide, if by a printing process such as screen printing or by a spray on the broadside 26 of the carrier body 22 is applied, on which the at least one resistive element 28 located.

Out 5 is in synopsis with 1 seen that in the frame 12 an electrical conductor 34 can be integrated to the power supply. In 1 is a corresponding connector 35 for connecting the electrical conductor 34 to a voltage source shown schematically. The electrical conductor 34 can metal plates 36 include (compare 6 ), which in the frame 12 , so in the lower part 14 on the one hand and in the lid part 16 on the other hand are integrated. This can be done, for example, by molding these metal plates 36 with a plastic material of the frame 12 and / or by introducing or pushing in the metal plates 36 in the plastic material of the frame 12 be reached.

For electrical contacting of the conductor collectors or collecting devices serving conductor tracks 30 can with the metal plates 36 metal springs 38 be connected. For example, the metal springs 38 with the metal plates formed for example from aluminum and / or copper 36 be soldered. The metal springs 38 and the metal plates 36 but can also be made in one piece. For example, as the metal springs 38 trained components of the electrical conductor 34 practice at the 1 and 5 shown variant of the air heater 10 a surface pressure on the tracks 30 out. This makes it easy to frame 12 with the surface heating elements 18 to equip and here for the contacting of the tracks 30 So for the connection of the tracks 30 to provide the voltage source. In addition, the surface heating elements 18 If necessary, simply replaced.

As is apparent in particular from the schematic representation in FIG 5 can be seen in the lid part 16 of the frame 12 on the one hand and in the lower part 14 of the frame 12 on the other hand, respective grooves 40 be formed, in which the respective surface heating elements 18 are held or detained. The respective groove 40 in this case, for example, between the opposing and the respective surface heating element 18 pinching metal springs 38 be educated (cf. 6 ). Furthermore, it is possible to use the carrier body formed from plastic 22 in such grooves 40 to lead, so that an abutment for the of the at least one metal spring 38 applied surface pressure is provided.

Also from 6 shows that with the metal plates 36 connected metal springs 38 are preferably formed as pre-bent metal parts, so that these metal springs 38 can exercise the surface pressure.

Out 7 It can be seen that one of the functioning of one of the metal springs 38 corresponding spring element 42 for contacting the conductor tracks 30 of the respective surface heating element 18 also in one piece with the respective metal plate 36 can be trained. So can a free end of each leg 43 the metal plate 36 , which in each case one of the surface heating elements 18 is assigned as the spring element 42 be educated. Such a spring element 42 can with one outward so to the gap 20 out (compare 1 ) directed force against the tracks 30 press (compare 7 , left view) or with an inward force (cf. 7 , right representation). Accordingly, the conductor tracks 30 at their the flowing past the fluid facing upper sides by means of the spring element 42 be contacted (see 7 , right-hand representation) or on the undersides opposite these tops (cf. 7 , left illustration).

By 8th Another way of contacting is illustrated. It is between two holding legs 44 a highly conductive silicone 45 brought in. The electrically conductive silicone 45 is with the metal plate 36 on the one hand and with the tracks 30 on the other hand in contact. The conductive silicone 45 can on the metal plate 36 be applied, for example by means of a metering device. When inserting the carrier body 22 between the respective holding leg 44 becomes the conductive silicone 45 up into a gap between the retaining legs 44 and the tracks 30 pressed and thus provides the electrical connection to the metal plate 36 ago. The holding leg 44 Can be integral with the lower part 14 and / or the lid part 16 of the frame 12 be educated.

Another way of contacting the tracks 30 should be based on 9 schematically illustrating which the contacting serving items before assembly. Thus, in the plastic material of the carrier body 22 a passage opening 46 be formed. In this passage 46 can be a pin, preferably a metal pin 48 be introduced so that the metal pin 48 on both sides of the surface heating element 18 a little way out of the carrier body 22 protrudes ,. An annular contact element or a Kontraktring 50 can then with this protruding area of the metal pin 48 be connected, for example by means of a (not shown) nut, which on the metal pin 48 is screwed, and / or by clipping, gluing, clamping, stapling, caulking, riveting or the like, wherein on the carrier body 28 or the support plate in the region of the passage opening 46 applied trace 30 with the contact ring 50 is electrically connected.

In 10 another variant is shown. It is in the carrier body formed from the plastic 22 of the surface heating element 18 a contact element 52 or introduced a metal contact, for example by molding, gluing, pushing in, punching or the like. This is preferably done before the trace 30 in the form of the conductive paste or the conductive plastic on the carrier body 22 is applied, since the contact element 52 then under the track 30 arranged and surface connected to this electrically conductive, in particular soldered or glued. The contact element 52 can a pin 54 have, which on one of the conductor track 30 opposite side of the carrier body 22 protrudes and the connection of the respective surface heating element 18 to the power supply or power supply is used. It is also conceivable that the pin 54 on the same side of the carrier body 22 is arranged, on which the conductor track 30 located.

In another variant, the metal pin occurs 48 not through the carrier body 22 but is inside the carrier body 22 attached at one end, such as by molding or gluing. This is in 11 shown, with here the contact ring 50 by caulking the metal pin 48 on the carrier body 22 is attached and in this case the conductor track 30 contacted.

The tracks 30 In addition, they can be contacted with all types of pin-shaped connection parts which have a contact surface for connection to the conductor track 30 respectively. The contact surface can with the conductor tracks 30 electrically conductive, for example by gluing, by using a silver paste, by soldering and / or by laser, by caulking, by riveting or the like.

In 12 is a melting paste 70 shown once in the initial state and once in the molten state. Such a melting paste 70 may suitably be electrically conductive with the resistive elements 28 be connected and act as a security element. Alternatively, a recoverable securing element may be used, for example in the form of a PPTC. It is particularly advantageous in both variants mentioned above, when the fuse element is designed as a paste and so easy to the interconnects 30 can be connected

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10032099 C1 [0002, 0013]

Claims (10)

Heating device with a plurality of electric surface heating elements (18) and with a holding device which holds the surface heating elements (18) such that the surface heating elements (18) can be overflowed by a fluid to be heated, wherein the respective surface heating element (18) has a carrier body (22). comprises, on which at least one resistance element (28) is arranged, which is acted upon for heating the fluid with electrical energy, characterized in that the carrier body (22) is formed from at least one plastic. Heating device after Claim 1 , characterized in that the at least one plastic is formed as a thermoset and / or in the at least one plastic reinforcing fibers are embedded. Heating device after Claim 1 or 2 Characterized in that the at least one resistance element (28) applied as in at least one surface of the support body (22), comprising in particular distributed in a dispersion medium carbon particles dispersion is formed. Heating device according to one of Claims 1 to 3 , characterized in that the at least one resistance element (28) is applied flat and / or in the form of a plurality of separate, electrically parallel and / or electrically connected in series on at least one surface of the carrier body (22). Heating device according to one of Claims 1 to 4 , characterized in that on an upper side of the at least one resistance element (28) facing the fluid, an electrically insulating protective layer (32), in particular comprising silicone, is arranged. Heating device according to one of Claims 1 to 5 , characterized in that the at least one resistance element (28) with an on at least one surface of the carrier body (22) arranged collecting means is electrically connected, which has a lower electrical resistance than the resistance element (28). Heating device after Claim 6 , characterized in that the collecting device with an arranged on the holding device, in particular metallic, electrical conductor (34) is electrically connected. Heating device after Claim 7 , characterized in that the electrical conductor (34) is connected to form a surface pressure and / or materially connected to the collecting device. Heating device according to one of Claims 1 to 8th , characterized in that the surface heating elements (18) are held interchangeably on the, in particular as a base part (14) and a cover part (16) comprehensive frame (12) formed and / or formed of at least one plastic, holding device. Heating device according to one of Claims 1 to 9 , characterized in that the respective surface heating element (18) has at least one electrical fuse element (68).

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