EP3016475B1 - Device with heatable surfaces of homogeneous heat distribution - Google Patents

Description

The invention relates to a device with a heatable surface of homogeneous heat distribution comprising an electrically highly conductive fleece comprising electrically insulating fibers and electrically conductive fibers, a control device, by means of which a voltage is adjustable to a current flow required in the device for achieving the desired heating power to ensure lines by means of which the contact to the control device for a data and / or signal exchange and / or supply of the web with electrical energy can be produced and the density of the electrically conductive fibers is so high that when voltage is applied, a current flow comes.

As electrical conductors media are referred to, which can be used to transport electrically charged particles and undergo structural realization using conductive components, such as metals, such as copper, silver, steel but also carbon and polymers using a variety of technologies. Thus, electrical conductors in the form of textiles made of electrically conductive fibers can be found that used in a variety of applications, such as electrically powered textile heating surfaces, which have a lower height and therefore especially for direct installation under floor coverings such as carpet, tiles and Recommend laminate. Thus, such heating surfaces are not only suitable for the application in housing construction, but are also used as industrial heating surfaces or heating surfaces in trade fair, sales and sports halls.
In the systems available so far, however, the problem arises on the one hand that the technology used or the material used is not suitable for a solid surface or large area due to a lack of homogeneous conductivity. On the other hand, some technologies or materials are vulnerable to breakage, not flexible or too soft for such an application.

The use of conductive fibers in a nonwoven fabric is characterized by the fact that it is flexible and allows a sufficient homogeneous conductivity. Such nonwovens, however, are mostly used as electromagnetic compatibility (EMC) protection and as drainage textile. These nonwoven fabrics do not show sufficient stability of the electrical property profile.

Nevertheless, some nonwovens with electrically conductive requirement profile are known on the current state of the art, such as in use as a heating element. A generic electrically conductive fleece is in the utility model DE 20 2011 100 936 U1 which discloses a heating fabric made of a nonwoven composite material. The properties of the nonwoven composite material are defined so that a full-surface heat release is possible, which is foldable, drapable, breathable and washable. The nonwoven composite material is incorporated as a layer of electrically conductive fibers between cover layers, wherein the electrical conductivity of the heating textile is based on carbon fibers. This material is therefore ideal for applications in the clothing and surface heating sectors.

Due to the very flexible design of the nonwoven composite material, however, this is not suitable for use as a nonwoven for heating large areas, since there is a lack of mechanical and chemical stability.

In the published patent application DE 199 11 519 A1 discloses a resistance surface heating based on a glass / carbon fiber electrically conductive nonwoven material with self-extinguishing or incombustible protective films. The contacting takes place by means of self-adhesive copper-based electrodes.
The problem here, however, is that a fiberglass-based nonwoven material is used, whereby the basis weight of the nonwoven fabric is drastically increased. Due to the increased cost of laying this nonwoven material, this is only partially suitable for use in large areas.

In the utility model DE 20 2013 006 258 U1 discloses an electrically conductive fleece with homogeneous heat distribution, which is positioned on the surface to be heated and contacted at a suitable location. The contacting takes place in such a way that the contact resistance between the electrical contact and the conductive textile is as low as possible in order to avoid energy losses. The nonwoven described is fixed with sticky, conductive binders.
In the disclosed nonwoven, however, the problem arises that a binder is necessary, which makes the production and laying of such a web more difficult and thus leads to higher costs.

In the published patent application WO 2007 110 06 181 A1 is a cellulose spunbond described as a surface heater. With an operating voltage of up to 1000 V, a power of up to 2 kW per square meter is achieved with a modular, contiguously contacted surface unit of 1 m length x 1 m width. The surface heater is characterized by a low production cost and good performance characteristics. The unusual voltage level with its high insulation requirements results in only a minimal achievable surface resistance of the structure of 500 ohms in the area mentioned.
The disclosed cellulose spunbonded fabric is designed to provide a small area heating system on a large area for a point heating, which heats and / or dries the entire space due to the large heating power. Thus, this fleece is not suitable as a large-scale heating system.

However, the disclosed in the prior art electrically conductive nonwoven materials are not suitable for the production of a large area surface heating, since then the number of points of contact of the electrically conductive fibers is greater, the greater the distance between the two poles. The consequence of this is that the applied voltage is distributed to a plurality of contact points and therefore only a small voltage is applied to the individual contact point. Since the electrically conductive fibers can inevitably corrode and / or oxidize on their surface, it can come to high resistances, which can be so large that the flow of current is interrupted. Thus, a certain minimum voltage at a contact point is required to maintain the flow of current. If the voltage is so low that the electrical line is interrupted, ends the purpose of use. One makes the experience that with increasing duration the Use a change in the resistance between adjacent fibers occurs, which manifests itself in a sudden increase in electrical resistance. This phenomenon is known and is referred to as so-called "frits". In such a case, ie a case of the occurrence of the so-called "frittens", the voltage must be increased so far that the resulting from corrosion and / or oxidation insulation "break through" again to restore a flow of current.

There is a great need for an electrically highly conductive nonwoven that ensures the heating of a large area and overcomes the above problems. In addition, the fleece should be fully functional even with large dimensions. In particular, the problem of so-called "fritting" is to be solved, which designates the irregular sudden fluctuations of the electrical resistance caused by variable contact resistances. The consideration of the "frying" has the advantage that can be dispensed with for the production of the desired heating power on the application of electrical high voltage, but only a comparatively low voltage is required, which is considered non-threatening for adult people and normal applications. This has significant economic benefits as well as safety aspects.

The object of the invention is therefore to provide a device with a heatable surface of homogeneous heat distribution comprising an electrically highly conductive fleece, which ensures a homogeneous heat distribution over the entire surface despite low supply voltage.

Furthermore, this device should be quickly and easily adaptable to different sizes, as well as inexpensive to manufacture and install and durable. Another object of the invention is to provide such a low basis weight device to ensure a wide range of applications.

This object is achieved by the device with heatable surface of homogeneous heat distribution with the features of the independent claim, in particular by increasing the heating power at a certain applied voltage, the operating voltage, the controller briefly increases the voltage by the surge "Δ U ₁ " to subsequently return to the output voltage, in the event that the actual value of the heating power is still below the setpoint, the control unit generates a renewed surge "Δ U ₂ " from the control unit, wherein "Δ U ₂ " greater than "Δ U ₁ is, in the event that the actual value of the heating power is still below the setpoint, the controller generates a new surge "Δ U ₃ " from the controller, where "Δ U ₃ " is greater than "Δ U ₂ " and for the Case that the actual value of the heating power is still below the setpoint, the above steps are repeated n times, the voltage st o "Δ U _n " is greater than "ΔU _i ", where i = 1 to (n-1).

It is a device with a heatable surface of homogeneous heat distribution comprising a highly electrically conductive nonwoven, which comprises electrically insulating fibers and electrically conductive fibers with sufficient density, proposed a control device and lines.

The control unit changes the electrical property profile of the nonwoven, wherein the electrical conductivity of the nonwoven increases or the electrical resistance of the nonwoven is reduced. The control unit does not regulate the fleece by means of a voltage change, in the sense that the operating voltage is adapted to the desired heating power. As a rule, such a control would be effected by means of a sensor which measures physical parameters, such as the temperature, and increases or decreases the voltage and thus the current flow required to achieve the desired heating power.

The control device according to the invention changes the resistance of the nonwoven by the controller increases the voltage briefly and gradually over the operating voltage of the web until the operating voltage ensures the required for the achievement of the desired heat flow in the fleece. By briefly increasing the voltage across the operating voltage of the web, so by a surge, it comes to "breakthrough" and the formation of bridges, so that consequently increases the conductivity of the web or the resistance of the web decreases. After the brief increase in the voltage, the control unit regulates this again to the operating voltage, so that at the same operating voltage, the heating power of the web has risen. This is based on the fact that due to the voltage surge above the operating voltage of the nonwoven, the previously not "broken through" contact points, which are still oxidized and / or corroded, break through and produce a conductive bridge. This increases the conductivity of the fleece.

It is then determined whether the first short-term increase in the voltage across the operating voltage of the mat is sufficient to the To ensure the achievement of the desired heating power required flow of current in the web.

If this is not the case, the controller increases over a renewed surge briefly and gradually the voltage across the operating voltage of the web. The voltage of the renewed surge is higher than the previous increase in voltage. The short-term and incremental, i. Cascade-like, voltage increases over the operating voltage of the web until the current flow required in the web to achieve the desired heating power is produced.

It has been found that in the present nonwoven fabric in a permanent installation, ie, no mechanical movement, the effect of "frizzing" and the need for "breakthrough" at a certain corroded and / or oxidized contact points occurs only once. The nonwoven uses stainless steel fibers, in particular stainless steel fibers, which constitute an oxidation-free material. However, due to the high number of contact points between the steel fibers, at which a minimal oxidation and / or corrosion layer can arise, a plurality of resistors, which are configured in the end chaotically in series and in parallel. The effect of this minimal layer on a single contact point is not measurable individually, but in the sum, ie over the total length of the nonwoven. Thus, the problem of "fringing" first arises and is measurable that in the entire web a plurality of contact points occur, which in turn generates a high number of series and parallel resistors.

In the context of the invention, it has been found that after the "breakthrough" of the corroded and / or oxidized contact points of the fibers by means of an applied "breakdown voltage" these contact points are activated, in such a way that at exactly these "broken" contact points a kind of plasma discharge and micro welding takes place, whereby conductive bridges are generated, which contribute to a significant increase in the flow of current. In other words, due to the "breakdown" and the bridges created, the electrical property profile of the nonwoven is changed, whereby the electrical conductivity of the nonwoven is increased or the electrical resistance of the nonwoven is reduced.

In a flexible installation, i. After the "breakthrough", the applied voltage is lowered, and if the nonwoven is moved and / or subjected to mechanical stress, then again it can happen that the contact points corrode again and / or oxidize or break the conductive bridges mechanically again. Of course, this can also occur during the aging process of the fleece.

Due to the large number of fibers in the nonwoven, the flow of current comes about. Due to Ohm's law, not all of the voltage applied to the device, but only a fraction thereof, is present at the junction between adjacent fibers. As a rule of thumb, the greater the number of transitions between the adjacent poles, the lower the voltage applied to adjacent fibers (neglecting the respective different electrical resistances). It is determined by the distance of the non-woven and the power supply electrical poles. With the same nonwoven texture, the number of transitions will be greater with a large pole distance and vice versa.

Against the background of developing a device comprising an electrically highly conductive fleece with low insulation requirements for use as a large-area surface heating, while the "frits" should not be prevented .. Rather, it is provided that by means of the controller, a corresponding voltage at the of highly conductive web formed surface is adjustable and controllable, which ensures a required for the achievement of the desired heating power flow in the device. Basically, a corroded contact works like a diode in lock-up mode. First, the resistance is so great that no current can flow. From a certain "breakdown voltage", the resistor then collapses and the current can flow again. This "breakdown voltage" is at least 13 mV, but preferably 24mV to 30mV. The current flow continues until a certain (other) voltage is fallen below again. In the end, due to the large number of electrical contacts, the fleece changes its current intensity and thus the heating power as a function of the supply voltage.

In order to achieve a current flow to achieve the desired heating power in the fleece at all, a sufficient density of the fibers contained in the fleece is necessary. The sufficient density of the fibers contained in the nonwoven, in particular the electrically conductive fibers, is required so that they at least partially touch and thus a flow of current can even come about. The minimum fiber density is at a steel content, in particular stainless steel, of at least 7.5 vol.% In the Entity of the fleece to ensure a homogeneous flow of electricity at all. Understandably, a higher steel content in the entirety of the nonwoven fabric is also conceivable.

In the most general case, the duration of the single surge in the invention is basically arbitrary. Practical tests have shown, however, that the duration of a single surge is to be chosen so that it is at least one millisecond, but not more than three seconds. As explained in detail, is done by increasing the voltage a "breakthrough" and consequently the formation of an electrically conductive bridge between fibers, which are interrupted at lower voltages and thus electrically non-conductive. The result of the formation of a bridge is that this newly created current path continues in the manner of a ramification and forms further bridges and thus creates additional current paths that arise in multiple and successive sequences. Essentially, it is about creating a cascading spread of bridges over the entire surface of the web. The formation of bridges does not happen simultaneously but chronologically one after the other, which takes a certain amount of time. Experience shows that with a voltage surge of less than one millisecond, the successive formation of bridges and consequently the formation of several current paths is omitted. On the other hand, measurements have shown that a period of max. 3 sec is sufficient for the formation of a variety of ramifications even with larger areas and distances between the electrode poles. Longer surges do not require improvement and increase in the current passed through. For this reason it is recommended to choose the duration of the surge from the suggested time interval.

In the stepwise loading of the web with short-term surges only those bridges are formed or transitions activated, the breakthrough lies within the voltage interval, which can be bridged by the height of the surge. The formation of additional and additional bridges, however, require a shock with a higher voltage value. The gradual increase of the voltages in the successive surges leads to the formation of more and more bridges, consequently a higher conductivity or a lower resistance of the web and the formation of higher currents. After applying a certain number of surges, the electrical resistance becomes so low that, when returning to the operating voltage, the current flow or the heating power will be greater than desired, ie the actual value is above the desired value. The smaller the distance of the voltage surge from the previous voltage surge is, whose difference is thus as small as possible, the smaller will be the exceeding of the actual value. The smaller the voltage difference between adjacent surges, the more accurate the actual value will be. The required accuracy of the application or the tolerable measurement errors specify an interval around the actual value in which the desired value should be later. At a large interval, the voltage values of the adjacent successive surges may be greater, so that in a few steps, the control process is completed, as if a very narrow range of values for the actual value is specified. The voltage values of adjacent and successively applied surges increasing from control step to control step are smaller in their difference, the higher the requirements for the accuracy of the desired actual value becomes. Conversely, if the accuracy requirements are low, the voltage difference between adjacent surges may be correspondingly greater than the deviations from the actual value.

The term "heatable area device of homogeneous heat distribution" refers to a device which comprises an electrically operated, heatable element and is adaptable to a size of less than 1m ² to several 100m ² . Preferably, the device is designed flame retardant and / or flame retardant.

In the most general case, the device comprises an electrically highly conductive fleece, a control device and lines, which can be easily applied to a surface to be heated. That is, the device is placed on the surface, for example, applied, applied, laminated, glued, sewn, needled and / or calendered or integrated into the surface to be heated. The lines usually have to fulfill different functions. They serve to supply the fleece with electrical energy that is emitted by the control unit in a defined manner. Additional lines for data and signal exchange are available, are passed through the corresponding information from the fleece to the edge area and there undergo appropriate processing. Thus, for example, the attachment of a temperature sensor within the nonwoven serve to check whether the heating power applied by means of the control unit corresponds to the desired value. If the temperature is too low, the control unit can be enabled to increase the heating power or the supplied current in the sense described within the scope of the invention. The measured value of the temperature sensor does not necessarily have to be used to control the control unit, but can also be used to obtain the corresponding information about the temperatures exclusively display and convey. But also the use of sensors of other types, the z. As the detection of moisture, pressure and / or elongation are used, where it is necessary to lead the measurement data via signal or data lines to a receiving or display device.
Preferably, the device is a surface heating with homogeneous heat distribution to avoid unevenness in the heating of the surface. The surface heating transfers the heat directly to the surroundings via the heated surfaces and / or indirectly via adjacent components, for example a building, and is dimensioned such that it is integrated either in the complete surface or only in part of the surface and these covers. A surface heating is suitable for the heating of any surfaces, such as wall, ceiling or roof and / or floor surfaces and / or for the heating of any components of a building. For example, the surface heating is a wall heating, ceiling heating, roof heating, (floor) floor heating and / or component heating.

In an advantageous embodiment, the device is lightweight and has a basis weight of at most 1000 g / sqr to serve a wide range of applications. The Square (sqr) is a non-metric area measure, where 1 sqr corresponds to a square area with a side of 10 feet or 9,290,304 square meters. Even more preferably, the device has a basis weight of 450g / sqr, 400g / sqr, 350g / sqr, 300g / sqr, 250g / sqr or 200g / sqr. Most preferably at a maximum of 190g / sqr, 180g / sqr, 170g / sqr, 160g / sqr, 150g / sqr, 140g / sqr, 130g / sqr, 120g / sqr, 110g / sqr or 100g / sqr. Most preferably, the basis weight of the nonwoven is at most 160 g / sq.

The term "highly electrically conductive nonwoven" refers to a structure of fibers of any kind and of any origin that have been somehow joined together to form a nonwoven and joined together in some way. Such webs or nonwovens are mostly flexible sheets, i. H. they are easily flexible, their main structural elements are fibers and they have a comparatively small thickness compared to their length and width. The structure of the nonwoven is arbitrary, with a normally structured nonwoven having increased strength and an open-structured nonwoven is particularly suitable for a needle-punching process. Preferably, the nonwoven fabric is designed flame retardant and / or flame retardant.

The nonwoven fabric according to the invention comprises a high proportion of stainless steel fibers, in particular stainless steel fibers, whereby a high degree of mechanical and chemical stability is given. In addition, the nonwoven fabric is designed so that it is light and weather resistant and long-term stable, i. stable over a period of at least 1 year, 2 years, 3 years or 4 years. Even more preferably, the web is stable for a period of at least 5, 10, 15, 20 or more years. Furthermore, the nonwoven fabric is preferably flexible and, in its average value based on the area, consistently highly electrically conductive.

The term "lines" relates to such lines by means of which the contact, in particular the electrical contact, to the control device for a data and / or signal exchange and / or a supply of the web with electrical energy can be produced. The data and / or signal exchange and the power / voltage supply can be made via a cable or a cable.

The lines are preferably light and weather resistant and chemically stable. The base component is therefore a little reactive metal and / or a less reactive metal alloy.

The term "controller" refers to an electronic device for controlling the voltage and current in the device. In a preferred variant, the control of the voltage and the current is controlled in dependence on the data and / or signal exchange from the fleece and / or external sensors.

Preferably, the voltage and thus the current flow at the control unit manually and / or automatically adjustable. In the case of the automatic control of the voltage, the device regulates itself, which is additionally connected and / or integrated with a control system for self-regulation and / or self-evaluation. It is within the skill of the art to make such a designed controller.

In a further development, DC or AC voltage is applied to the control unit. However, alternating voltage is preferably applied, since the use of alternating voltage also offers the advantage that polarization effects and / or galvanic processes at the electrodes are avoided.

Advantageous developments of the invention, which can be implemented individually or in combination, are shown in the subclaims.

In a further development, the control unit regulates the current flow required for the achievement of the desired heating power by means of amplitude modulation and / or modulation of the pulse width in the case of rectangular pulses.

The term "amplitude modulation" is understood within the meaning of the invention, a method in which the voltage applied to the control unit is interrupted in phases and the energy and power transmission is reduced, in which the control unit is repeatedly turned on and off. In this way, the energy supplied by the control unit to the fleece is emitted in a pulse-like manner, wherein breaks between the pulses are present in each case. The longer the pauses between the pulses, the lower the amount of energy transferred.
In the context of the invention, it is conceivable that the voltage applied to the control unit and the fleece voltage is constant, the transmission power is increased or decreased by the pauses. It is conceivable to lengthen or shorten the pulse length with regard to the pause length, and vice versa.
Such an amplitude modulation of the control is important to the safety system, as this leads to an increase in the detectability of the fault currents. The safety system serves to prevent fire.

A "modulation of the pulse width in the case of rectangular pulses" is understood to mean a modulation type in which a technical variable, such as, for example, the electrical voltage, changes between two values, ie a minimum and a maximum, in a rectangular pulse.

By means of the pulse width modulation, the signal is switched on and off again, whereby the intervals of the switching on and off again can be modulated. Depending on whether you want to heat continuously and / or the Heizvlies is turned on at certain intervals for a certain period of time, the heating power or energy is changed over time. In this way it is achieved that the performance of the control unit is controlled by the change of the distances.

In embodiments, the nonwoven comprises electrically insulating fibers and electrically conductive fibers which are light and weather resistant and chemically stable. Furthermore, all fibers are preferably water-absorbing. The electrically conductive fibers are either bare metallic fibers or metallically coated fibers with an electrically insulating core, wherein the cores are coated with a metal, in particular silver, and / or a plastic and / or galvanized plastic fibers. Thus, the (back) jump of the contact resistance between the individual fibers, which indicates a change in the transmission property or contact resistance, by the addition of additives to the fiber material, such as silver or silver fibers, sufficiently reduced. Preferably, the metal used is a low-reactivity metal and / or a low-reactivity metal alloy.

By modifying the mixing ratio of conductive coated / galvanized plastic fibers and metallic fibers, individual conductivity can be achieved.

The nonwoven fabric of the invention is highly conductive or highly conductive, so that performances preferably in the order of 1 to several kW / m ^{2 are achieved} with a supply voltage of only 42 volts AC. The AC voltage is SELV (Safety Extra Low Voltage).

Due to the current / voltage characteristic, large-area applications of the nonwoven are thus possible, such as heaters in the floor, ceilings and / or wall area. This ensures heating and / or drying of rooms, as well as outdoor de-icing, for example of bridges, roads, driveways, traffic systems, aircraft, trucks and / or roofs.

The fleece is additionally made breathable, whereby moisture can directly overcome the fleece and thus surfaces are dried quickly. Due to the breathability, the fleece is also suitable as a room freshener in filter systems, wherein the air flowing through is heated, cleaned and / or ionized.

The electrical contact resistance is preferably in the milliohm range. The sheet resistance of the nonwoven is between 1 and 1000 ohms / sq.

For the realization of high current densities, a very good contacting is necessary, in particular within the fleece and between individual fleeces. It is also important that the resistance of the connection contacts is also low, otherwise the supply voltage must increase.

In this case, the lines are integrated in the weft and / or warp direction in a fabric, in which strands, wires, conductive yarns and / or conductive threads are woven.

The nonwoven preferably forms at least two layers. The fabric is disposed between the layers of the web.

The current flow preferably runs horizontally through the nonwoven, ie, the plus and minus poles are arranged in the same plane of the nonwoven. The positive and negative poles are arranged at a certain distance from each other, preferably at an ideal distance of z. B. 50 cm. Of course, the selected distance may also be smaller or larger than said distance.
The positive pole is preferably arranged on one edge of the fleece and the negative pole on the opposite edge. In order to heat a large area, it is thus necessary that several nonwovens are placed next to each other and contacted with each other. Continuing the above-mentioned orientation of the nonwoven plus and minus pole alternate with each other. It is important that the electrodes have the same distance to each other, so that the partial resistances of the nonwoven sections are the same.

Alternatively, the flow of current is vertical through the web, d. H. that plus and minus pole are arranged in different horizontal planes of the fleece.

The fabric with the integrated lines is preferably contacted or connected to the entire surface of the web. The mechanical, chaotic metal-metal contacting of the individual fibers forms an electrically conductive network with mechanically temporarily stable contacting bridges.

Preferably, the strands and / or wires woven in the fabric are additionally needled with the fibers in the nonwoven production process, sewn, calendered and / or flamed to allow optimal contact. The strands and / or wires of the fabric are contacted directly in the needling process with the electrically conductive fibers by penetrating the electrically conductive leads and optimally use the surface of the leads. In the needling process, it is important that the web has an open structure so that it is not destroyed during needling. The needles allow for optimal contacting between the fabric and the web as the conductive fibers are transported from the open-structured web to the fabric. The contacting can be fixed by further process steps, such as calendering, flaming, needle loom finish and / or lamination.
Alternatively, the fabric is contacted with the conductive yarns and / or conductive threads with the fabric. Of course, the contacting may also be such that a combination of strands, wires, conductive yarns and / or conductive threads is used. For a complete contacting of the entire surface can be realized, and to achieve a maximum contact surface.

By adding highly conductive additives to the fiber material, such as silver or silver fibers, an electrical base network is formed which can be fixed in further process chains. In this way, a cross-sensitivity of the nonwoven fabric is adjustable, which is defined during manufacture. The fixation or cross-sensitivity to moisture, pressure and / or elongation takes place, for example, by means of calendering, flaming, needle loom finishing and / or lamination of foils or by means of powder coating. Interference for lines concerning the data and / or signal exchange and / or actuator components are excludable.
Due to the mixing ratio of the metallic electrically conductive fibers and the silver fibers, the selectivity can be defined in addition to the process chain.

The fleece is additionally a sensory fleece, which can be adjusted to a fixed cross sensitivity. The nonwoven thus responds to a change in state with a change in sheet resistance at the surface and / or volume through resistance. In this way, compressions of the nonwoven, whose compressive strength by means of the basis weight and further process steps, such as calendering, is set specifically, compresses the conductive materials and changes the electrical properties of the nonwoven. This change can be influenced as a function of the compression hardness. That is, with such a constructed nonwoven structures as pressure and / or force sensors are conceivable.
Such a nonwoven with the property profile of a pressure sensor is used for example for intelligent monitoring and / or as intercommunication of floor systems. This allows anonymous, large-scale monitoring of activities of an area.

The same applies to the case of stretching of the nonwoven, with similar effects occur. Important here is the specific, related to the elongation, targeted adjustment of the characteristics of the electrical property profile of the fleece.

The non-woven is preferably water-repellent and / or comprises water-absorbent fibers and / or equipment. The electrical property profile of the fleece can be influenced as a function of moisture by absorption or release of water. In addition, a measurement of the moisture is possible, wherein a sensor is that the fleece reacts only to a physical size with a known cross-sensitivity.
Large-area humidity sensors locate and / or quantify moisture damage and / or actively counteract this by heating the surface. This is useful when monitoring large areas, such as halls, dam walls and / or roof structures. Advantageously, the monitoring is carried out over the entire surface, ie not only selectively, the installation or the onset of the web is very simple, fast and inexpensive.

In the context of the present invention, it is likewise conceivable that different sensory fleeces are combined with one another, so that the fleece in its entirety has the property profile of a temperature sensor, pressure sensor and / or moisture sensor.

It is understood that the definitions and embodiments of the above terms apply to all aspects described below in this specification, unless otherwise specified.

Further details, features and advantages of the invention will become apparent from the following description of the preferred embodiment in conjunction with the subclaims. In this case, the respective features can be implemented on their own or in combination with one another. The invention is not limited to the embodiments. The embodiments are shown schematically in the figures. The same reference numerals in the individual figures designate the same or functionally identical or with respect to their function corresponding elements.

• Figur 1 den Aufbau des elektrisch hochleitfähigen Vlieses mit den Leitungen;
• Figur 2 ein Gewebe der Leitungen in Schuss- und/oder Kettrichtung;
• Figur 3 ein Gewebe der Leitungen im Mehrlagenaufbau zwischen zwei Lagen des elektrisch hochleitfähigen Vlieses.
• Figur 4 der Spannungsverlauf bei der Beaufschlagung des Vlieses

In detail shows:

• FIG. 1 the structure of electrically highly conductive fleece with the lines;
• FIG. 2 a fabric of the lines in the weft and / or warp direction;
• FIG. 3 a fabric of the lines in multilayer structure between two layers of electrically highly conductive nonwoven.
• FIG. 4 the voltage curve during the application of the fleece

The FIG. 1 shows a schematic isometric view of the structure of electrically highly conductive fleece (101) with the lines (110), by means of which the electrical contact to a control device for a data and / or signal exchange and / or a supply of fleece (101) with electrical energy can be produced. The lines (110) can be integrated in a weft (111) in weft and / or warp direction, light and weather resistant and chemically stable. The fabric (111) is contacted with the integrated lines (110) over the entire area with the web (101).

The nonwoven (101) comprises a high proportion of stainless steel fibers, whereby a high degree of mechanical and chemical stability is given. In addition, this is light and weather resistant and long-term stable, i. stable over a period of at least 5 years. The nonwoven (101) is further designed flame retardant and / or flame retardant, as well as flexible and full surface uniformly highly electrically conductive. The fleece (101) is additionally made breathable, whereby moisture directly overcomes the fleece (101).

The nonwoven (101) comprises electrically insulating fibers (103) and electrically conductive fibers (104), which are also light and weather resistant and chemically stable. The electrically conductive fibers (104) are bare metallic fibers or metallically coated fibers with an electrically insulated core, wherein the metallically coated non-conductive fibers coated with a metal, in particular silver, and / or a plastic and / or galvanized plastic fibers.

The electrically highly conductive fleece (101) achieves powers in the order of 1 to several kW / m ² with a supply voltage of only 42 volts AC, which is considered non-threatening to adult humans and normal applications. Thus, the fleece (101) offers many advantages for safety-related aspects. In addition, this opens up a variety of applications of the fleece (101), such as heaters in the floor, ceilings and / or wall area, heating and / or drying of rooms, as well as a de-icing in the outdoor area.

The nonwoven fabric (101) is additionally a sensory nonwoven, whereby this to a fixed cross sensitivity by adding highly conductive additives to the fiber material, such as silver or silver fibers, is adjustable by an electrical base network is realized, which is fixable in other process chains. In this way, in the production of the web (101) a cross-sensitivity is adjustable. Thus, the nonwoven (101) has the property profile of a temperature sensor, pressure sensor and / or moisture sensor. Although it is true for a sensor that the fleece (101) reacts only to a physical size with a known cross-sensitivity. However, it is also possible to realize a fleece (101) in which different sensory fleeces (101) are combined with one another so that the fleece (101) in its entirety has a plurality of property profiles.

FIG. 2 shows a schematic isometric view of the fabric (111) with the integrated lines (110) in the weft and / or warp direction (112, 113), which are light and weather resistant and chemically stable. Leads, wires, conductive yarns and / or conductive threads are woven into the fabric.

The FIG. 3 shows a schematic representation of the inventive device (100) comprising the fabric (111) with the integrated lines (110) in multi-layer structure between two layers (102) of electrically highly conductive web (101), wherein the control device is not shown. The inventive device (100) can be easily applied to a surface to be heated and is very light with a weight per unit area of 160 g / sqr.

It can be clearly seen that the nonwoven (101) forms two layers (102), wherein the lines (101) in the fabric (111) between the Layers (102) of the web (101) are arranged. In this case, the current flow runs horizontally through the fleece (101), ie that plus and minus poles are arranged in the same layer (102) of the fleece (101), or vertically through the fleece (101), ie that plus and minus pole in different layers (102) of the web (101) are arranged.

The fabric (111) with the integrated lines (110) is contacted over its entire surface with the nonwoven (101), so that an electrically highly conductive network with mechanically temporarily stable contacting bridges is formed due to the mechanical, chaotic metal-metal contacting of the individual fibers. In the nonwoven production process, the strands and / or wires woven in the fabric (111) are additionally needled, calendered and / or flamed with the fibers (103, 104) or the conductive yarns and / or conductive threads are contacted with the nonwoven fabric (101) , This allows optimal contact.

FIG. 4 shows a diagram of the voltage waveform upon application of the device according to the invention for generating a lower electrical resistance. The ordinate is the voltage U and the abscissa the time t. Starting from an operating voltage U ₀ , a voltage surge Δ U ₁ is briefly applied to the device. In this case, AU _{1 is} the voltage which is above the operating voltage at the first surge and exceeds this by the specified value. After the applied voltage at the end of the surge, which has been simplified as a rectangle, was moved back to the operating voltage U ₀ , a check is made to see whether the now existing current flow at the operating voltage U _{0 is} sufficient to provide the desired heat output , If this is not the case, the admission is carried out with the second voltage surge, wherein the peak value of the voltage is now above the value of the first voltage surge, ie that Δ U _{2 is} greater than Δ U ₁ . Then the conditions are created that additional bridges can be formed to increase the conductivity.

After completion of the second surge by returning to the operating voltage U ₀ , in turn, a corresponding check, whether now a corresponding current is present. This is denied in the example shown in the drawing and two more surges are applied in the manner described above. It is always true that the height of the surge of the next step must be greater than that of the previous steps, since only in such a case, the hope exists to form additional electrically conductive bridges.
With the completion of the fourth surge now a current is reached, which corresponds to the desired value, the actual value.
As a result, one would have realized by the proposed measures at constant operating voltage U ₀ higher current. Contrary to popular belief that when needed a higher current the voltage is to be increased accordingly, the invention is a completely different way, which has in its essential core content, to increase the heating power to lower the electrical resistance. This is made possible by electrical means by the steps described in the invention.

LIST OF REFERENCE NUMBERS

100

inventive device

101

electrically highly conductive fleece

102

Layers of the fleece

103

electrically insulating fibers

104

electrically conductive fibers

110

cables

111

tissue

112

Weft direction of the lines

113

Chain direction of the lines

Claims (12)

1. Device having a heatable surface of homogeneous heat distribution, comprising

   - a highly electrically conductive non-woven fabric (101), which comprises electrically insulating fibres (103) and electrically conductive fibres (104),

   - a control device, by means of which a voltage is adjustable, to ensure the current flow in the device that is necessary to achieve the desired heating output;

   - cables (110), by means of which the contact to the control device can be produced for data exchange and/or signal exchange and/or to supply the nonwoven fabric (101) with electrical energy; and

   - the density of the electrically conductive fibres is so high that, when a voltage is present, a current flow arises; characterised in that

   - to increase the heating output for a particular applied voltage, the operating voltage, the control device briefly increases the voltage by the voltage surge "Δ U₁", in order subsequently to return to the initial voltage;

   - for the case in which the actual value of the heating output still lies below the setpoint value, the control device generates another voltage surge "Δ U₂", wherein "Δ U₂" is greater than "Δ U₁";

   - and for the case in which the actual value of the heating output still lies below the setpoint value, the control device generates another voltage surge "Δ U₃", wherein "Δ U₃" is greater than "Δ U₂";

   - and for the case in which the actual value of the heating output still lies below the setpoint value, the above described steps are repeated n times, wherein the voltage surge "Δ U_n" is greater than "Δ U_i", where i = 1 (to n-1);
2. Device according to Claim 1, characterised in that the duration of the individual voltage surge lies in the time interval from minimum 1 ms to max. 3 sec.
3. Device according to claim 1 or 2, characterised in that the differences of the voltage surges Δ U_i - Δ U_i-1 are chosen so small that, in the case in which the setpoint value of the heating output is exceeded, the actual value that is obtained by virtue of the last voltage surge that is performed lies in a predetermined range above the setpoint value.
4. Device according to one of the preceding claims, characterised in that the control device regulates the current flow that is required to achieve the desired heating output by means of amplitude modulation and/or modulation of the pulse width in the case of square pulses.
5. Device according to one or the preceding claims, characterised in that the nonwoven fabric (101) comprises water-repellent and/or water-absorbent electrically insulating fibres (103) and electrically conductive fibres (104) and/or textile finishes.
6. Device according to one of the preceding claims, characterised in that the nonwoven fabric (101) is formed by at least two layers (102).
7. Device according to the preceding claim, characterised in that the cables (110) are integrated in a fabric (111) in the warp and/or weft direction (112, 113), the fabric (111) being disposed between the layers (102) of the nonwoven fabric (101).
8. Device according to one of the preceding claims, characterised in that the electrically insulating fibres (104) are bare metal fibres or metal-coated non-conductive fibres.
9. Device according to the preceding claim, characterized in that the metal-coated non-conductive fibres (104) are coated with a metal, in particular silver, and/or a synthetic material and/or are electroplated synthetic fibres.
10. Device according to one of the preceding claims, characterized in that the nonwoven fabric (101) is a sensor nonwoven fabric, wherein the latter is adjustable to a specified cross-sensitivity.
11. Device according to the preceding claim, characterized in that the nonwoven fabric (101) comprises a temperature sensor, pressure sensor and/or moisture sensor.
12. Device according to one of the preceding claims, characterized in that the device (100) can be applied to a surface to the heated.

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