HEATING HOSE AND METHOD FOR PRODUCTION AND USE

Abstract

Heating hose (1, 20, 23, 30, 33, 40) for electrically heating a pipe (13), a container and / or a molded part from the outside, with at least one electrically conductive heating section (21, 24, 31, 38, 41) in the form of a heating resistor for heating the heating hose (1, 20, 23, 30, 33, 40) at least section by section, characterized in that the heating hose (1, 20, 23, 30, 33, 40) is designed as a shrink hose with a diameter (D) that can be shrunk at least section by heating for shrinking onto the pipe (13), the container and / or the molded part, and that the at least one heating section (21, 24, 31, 38, 41) comprises at least one thermoplastic material (4) and at least one electrically conductive filler (5) finely dispersed in a matrix of the at least one thermoplastic material (4), and that the at least one electrically conductive heating section (21,24,31,38,41) is designed to be applied to an electric heating voltage or an electric heating current for at least partial shrinkage of the diameter (D) as a result of heating the at least one heating section (21, 24, 31, 38, 41) and / or for inductive heating of the at least one heating section (21, 24, 31, 38, 41) via an alternating magnetic field and for at least partial shrinkage of the diameter (D) as a result of the inductive heating of the at least one heating section (21, 24, 31, 38, 41).

Description

[0001] The invention relates to a heating hose for electrically heating a pipeline, a container, and / or a molded part from the outside, comprising at least one electrically conductive heating section in the form of a heating resistor for heating the hose at least section by section. The invention further relates to a method for manufacturing such a heating hose and a method for shrinking such a heating hose.

[0002] Heating hoses of the type mentioned have been known in various designs for some time. They are used in particular as trace heating for heating pipes, containers, fittings, and the like. Due to their tubular shape, the heating hoses can accommodate the pipes, containers, or fittings, at least in sections, in order to heat them evenly from the outside around their circumference. For this purpose, the heating hoses contain one or more heating wires that are electrically conductive and have such high resistance that they form a heating element to which a heating voltage or current can be applied. As a result of the heating voltage or current applied to the heating hose, the heating wire heats up and then transfers the resulting heat to the heating hose and the pipe, container, and / or fitting inside the heating hose.

[0003] Trace heating is also available in the form of heating tapes, cables, and cords, which can be wrapped around pipes, containers, and fittings. These heating tapes, cables, and cords also contain a heating wire, to the ends of which a heating voltage or current can be applied to heat the wire, similar to resistance heating. The heating tapes, cables, and cords then transfer heat to the pipes, containers, and fittings around which they have been wrapped. Heating tapes, cables, and cords can typically be wrapped with relatively tight bending radii. However, care must be taken to ensure that they are not wound too tightly or too far apart to prevent overheating of the tapes, cables, and cords and to ensure that the pipes, containers, and fittings are heated sufficiently.This is less problematic with heated hoses; however, heated hoses are usually significantly more expensive than heating tapes, cables, and cords because they must be pre-configured and adapted to the specific application. The winding of the heating wires in heated hoses cannot be varied afterward, or only to a very limited extent.

[0004] DE 20 2005 004 602 U1 discloses a heated liquid line comprising a middle layer of an electrically conductive polymer and embedded electrical conductors. DE 10 2012 208 020 A1 discloses a heated conduit extruded with an electrically insulating inner layer and two electrically conductive layers. Furthermore, DE 198 07 950 A1 discloses a heating coil fitting with a shrink jacket, and DE 10 2009 012 345 A1 discloses a liquid line heated by a surface heating element.

[0005] The present invention is therefore based on the objective of designing and further developing the heating hose and the methods of the type mentioned at the outset and explained in more detail above in such a way that electrical heating of pipelines, containers and molded parts can be carried out more cost-effectively, reliably and at the same time more efficiently.

[0006] This problem is solved in a heating hose according to the preamble of claim 1 in that the heating hose is designed as a shrink hose with a diameter that can be shrunk at least partially by heating for shrinking onto the pipeline,the container and / or the molded part is designed and that the at least one heating section comprises at least one thermoplastic polymer and at least one electrically conductive filler finely dispersed in a matrix of the at least one thermoplastic polymer, and that the at least one electrically conductive heating section is designed to be applied to an electrical heating voltage or an electrical heating current for at least section-wise shrinkage of the diameter as a result of heating the at least one heating section and / or for inductive heating of the at least one heating section via an alternating magnetic field and for at least section-wise shrinkage of the diameter as a result of the inductive heating of the at least one heating section.

[0007] By designing the heating hose as a shrink-wrapped tube with at least one heating section containing finely dispersed conductive particles, the heating hose can be easily and quickly retrofitted, especially by sliding it onto, various pipes, containers, or fittings. At the same time, this ensures good thermal contact and heat transfer between the heating hose and the object being heated, provided the correct size and shrink ratio are selected. After shrinking, the heating hose fits snugly against the object being heated. For heating purposes, a conductive filler consisting of small, separate particles is finely dispersed within the thermoplastic material of the at least one heating section of the hose. Consequently, shrinking the heating hose cannot damage the heating section.

[0008] Shrinking, on the other hand, regularly reduces the electrical resistance of the at least one heating section. This must be taken into account beforehand, as needed, with regard to the quantity and type of conductive particles in the at least one heating section. The aim is twofold: firstly, to ensure that the at least one heating section reliably conducts the electric current; and secondly, to provide a sufficiently high resistance to the conduction of the electric current so that a sufficiently high heat flow is generated in the at least one heating section as soon as the heating voltage or current is applied to the heating tube.

[0009] Heating the heating hose by applying a heating voltage or current serves two purposes: firstly, to heat the hose itself and, secondly, to heat the object it encloses. Furthermore, the initial application of the heating voltage or current can heat the hose to a temperature sufficient for shrinking it onto the pipe, container, molded part, or similar object. This requires exceeding a minimum temperature, which is largely determined by the thermoplastic material(s) used. Shrinking the heating hose with a hot air gun is not necessary, thus eliminating or at least simplifying a work step. However, it may still be possible to shrink the heating hose using a hot air gun.Basically, the heating hose can be used for trace heating as well as for shrinking with direct current or alternating current.

[0010] The aforementioned problem is further solved according to claim 12 by a method for manufacturing a heating hose, preferably according to one of claims 1 to 10, - in which a raw hose comprising at least one heating section, at least one thermoplastic polymer and at least one conductive filler finely dispersed in the matrix of the thermoplastic polymer, is extruded, - in which the diameter of the extruded raw tube is widened, preferably by stretching and - in which, preferably, at least one heating section is connected to two electrical contacts for applying an electrical voltage or an electric current.

[0011] The extrusion of extrudates comprising at least one thermoplastic polymer and at least one conductive filler is already known from other applications, although in this case, unlike the known processes, no raw hose is extruded. However, here too, it is crucial to achieve the most homogeneous possible mixing of the filler and the thermoplastic polymer to produce a satisfactory heating section of the heating hose. The proportions and ratios of thermoplastic polymer and electrically conductive filler that are advantageous to use, and how homogeneous the distribution of the electrically conductive filler should be, depend heavily on the specific thermoplastic polymer and type of electrically conductive filler used. Furthermore, the particle size, porosity, and surface properties can be of considerable importance.Nevertheless, the expert will be able to provide a suitable extrudate or to further optimize it through a manageable number of trials.

[0012] Once the raw hose is extruded, it is expanded, which can be done using a stretching process, whereby the raw hose can be stretched, particularly in the radial and / or circumferential direction. During this process, the raw hose can be heated and stretched, increasing its diameter. The stretched raw hose can then be frozen in this shape by cooling. To apply a heating voltage or current to the heating hose, the at least one heating section can be provided with at least two electrical contacts, via which the at least one heating section can be connected to a voltage or power supply. Cable clamps, pipe clamps, and band clamps are examples of suitable contacts. However, instead of clamps, only point contacts, not circumferential, can be used, which may also be known from other applications.

[0013] If at least one heating section of the heating hose is heated inductively via an alternating magnetic field, corresponding contacts are generally unnecessary. The heating hose can be inductively heated both for shrinking the hose itself and for heating a pipe, container, and / or fitting. For example, it can be designed to inductively shrink the heating hose and heat the pipe, container, and / or fitting by applying an electrical voltage or current to contacts on the heating hose.

[0014] Furthermore, the term "clamp" is to be understood very broadly in this context and is intended to include other elements, even if these are not usually referred to as clamps. The clamps are to be provided on or within a corresponding section of the heating hose and should make electrically conductive contact with at least one heating section or electrically connect several heating sections to each other. Circumferential bands, O-rings, and the like are also suitable for this purpose. The clamps do not necessarily have to be made of a metallic material. They can also be made of a plastic containing a finely dispersed electrically conductive filler, similar to the heating hose itself. The clamp can also be designed as heat-shrink tubing for shrinking onto the heating hose, similar to the heating hose itself.

[0015] Furthermore, the aforementioned problem according to claim 16 is solved by a method for shrinking a heating hose, preferably according to one of claims 1 to 11 and / or manufactured according to one of claims 12 to 15, - where the heating hose is pulled onto a pipe, container and / or fitting, - in which at least two contacts of at least one heating section of the attached heating hose are connected to a heating voltage or a heating current and the heating voltage or heating current heats the at least one heating section in the form of a heating resistance and / or the at least one heating section is heated inductively via an alternating magnetic field and - in which the heating hose is shrunk onto the pipe, container and / or molded part as a result of the heating of at least one heating section, thereby reducing the diameter.

[0016] The heating hose, in its expanded form due to the increased diameter, can be easily pulled onto the pipe, container, and / or fitting. The object is then at least partially inside the heating hose, with a certain amount of play preferably existing between the object and the hose. The object is thus loosely held within the heating hose. The heating hose is not yet tightly fitted to the object. To achieve this tightness, at least partially, the heating hose can be connected to a heating voltage or current via the at least two contacts of the heating section, which heats the heating section, since the heating section is designed as a heating resistor.The (specific) resistance of the heating section is so high that the electric current, corresponding to the heating voltage or current, flows through the heating section, generating a significant amount of heat. Ultimately, a large amount of electrical energy is dissipated in the heating section and released as heat. This heat also leads to the heating hose itself heating up. If a minimum temperature is exceeded, the heating hose, similar to a shape-memory material, attempts to contract back to its original size with a smaller diameter. This process is also known as shrinkage. As a result of shrinkage, the heating hose fits snugly against the pipe, container, and / or fitting, a process also referred to as shrinking.

[0017] The shrinking of the heating hose can also be achieved inductively by exposing at least one heating section to an alternating magnetic field. An induction coil can be used for this purpose. An induction coil carrying an alternating current generates a magnetic field—alternating in direction—characterized by a magnetic flux. If a heating section is placed in this magnetic field, a voltage is induced in it. The induced voltage generates a current flow (Lenz's law). Eddy current losses occur in the conductive particles within the heating section, which are converted into heat. In principle, it would also be conceivable to shrink the heating hose by heating it with a hot air blower. The heat is then transferred directly to the heating hose via warm air.

[0018] This ensures very good and close contact between the heating hose and the pipe, container, and / or molded part, thus guaranteeing good heat transfer from the heating hose to the object it surrounds. This makes it possible to precisely control the temperature of the object, at least in the relevant section, without risking local overheating. At the same time, this is also very efficient, as heat loss through air gaps between the object and the heating hose is avoided. Finally, the risk of the heating hose being damaged and rendered unusable by a break in the heating wire is also eliminated. With the heating hose according to the invention, partial damage to the heating section can be tolerated if it is sufficiently wide.Then an electrically conductive connection still remains between the electrical contacts of the heating hose.

[0019] In a first particularly preferred embodiment of the heating hose, the at least one electrically conductive filler is carbon-based and is formed, in particular, from carbon black and / or graphite. The electrically conductive filler can also be formed, either additionally or alternatively, from metallic particles, with iron and / or copper particles being particularly suitable. Alternatively or additionally, the at least one thermoplastic material can be a polyolefin, in particular polyethylene (PE) or polypropylene (PP), polyamide (PA), fluoroethylene propylene (FEP), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), Viton, polyvinyl chloride (PVC), and / or polytetrafluoroethylene (PTFE). The physical and, in particular, the electrical properties of the heating hose are determined to a considerable extent by the choice of materials.Therefore, by selecting appropriate materials, the specialist can influence the desired physical properties of the heating hose. All of the aforementioned materials are available at relatively low, albeit varying, costs.

[0020] The heating hose can be manufactured, at least in part, from a raw hose formed by extrusion. This is a very reliable and cost-effective method for producing a heating hose. Alternatively or additionally, the heating hose can be manufactured, at least in part, by expanding the diameter of the raw hose produced by extrusion or another method. This expansion can be achieved, for example, similarly to blown film production, by blowing pressurized air into the raw hose. The raw hose is thereby expanded in a radial direction. The expanded heating hose is then used to be fitted onto the pipeline, container, and / or molded part and is thus expanded to a suitable extent for this purpose.As an alternative to extrusion, the heated hose can also be formed from a film that has at least one heating section and whose edges are joined, in particular welded. A raw hose can also be formed in this way, which can then be further processed as described.

[0021] To give the heating hose, especially the raw hose, a high degree of shape memory for subsequent shrinkage, it can be advantageous if the molecules of the at least one thermoplastic material are at least partially cross-linked. If this occurs before the diameter is expanded, it can lead to even greater shape memory. One way to achieve this cross-linking practically, simply, reliably, and reproducibly is to irradiate the at least one thermoplastic material with electrons. This process is fundamentally known, for example, from the production of plastic films.

[0022] The diameter of a raw hose can be expanded independently by stretching. The raw hose is stretched radially, beyond its elastic yield strength, causing the molecules to align in the direction of stretching. This alignment results in the molecules lying closer together, thus creating stronger attractive forces between them. Stretching can be carried out at elevated temperatures, followed by cooling to essentially maintain the molecular alignment. If the thermoplastic is subsequently heated, the molecules realign more randomly, and thus become more isotropic, causing the hose to contract, or shrink.

[0023] For some applications, it can be disadvantageous if the heating hose is essentially electrically conductive. In such cases, it may be advantageous to design the heating hose with multiple layers, which can preferably be aligned at least substantially concentrically to each other. The layers are then either concentric or only substantially concentrically aligned. A mathematically exact concentric arrangement is therefore not essential. If the pipe, container, and / or fitting is made of an electrically conductive material, it can be avoided that the object is energized during heating with the heating hose if an inner layer is electrically insulating.The electrically conductive heating section of the heating hose does not come into direct contact with the electrically conductive pipe, the electrically conductive container and / or the electrically conductive molded part.

[0024] Alternatively or additionally, an outer layer can be electrically insulating against at least one heating element. In such a case, the risk of electric shock is reduced, as is the risk of a short circuit. Furthermore, it is impossible for the current from the heating element to transfer to any other object in contact with the heating hose.

[0025] If the heating hose has contacts at both opposite ends for applying the heating voltage or current, it can be supplied with a heating voltage or current without complex wiring. Furthermore, a uniform current density and thus uniform heating of the hose can be achieved. In such a case, it may be advantageous for at least one heating section to extend around the entire length of the hose and / or along at least substantially its entire length. The heating section can therefore extend along the entire length of the hose or only along substantially its entire length. It is therefore functionally acceptable if the heating section does not extend completely along the entire length of the hose.

[0026] Alternatively or additionally, the heating hose can also have at least two heating sections that are electrically separated from each other circumferentially over at least approximately their entire longitudinal extent. The heating sections can therefore be electrically separated from each other circumferentially only approximately over their entire longitudinal extent, or preferably be electrically separated from each other circumferentially over their entire longitudinal extent. Here, and in the following, "circumferentially" can generally be understood as along the circumference or in the circumferential direction. In this way, it can be achieved that the current in the at least two separate heating sections flows in different directions, in particular in opposite directions, for example, longitudinally or circumferentially.This ultimately allows the heating hose to be connected to the heating voltage or current from one end via corresponding contacts on at least two separate heating sections. Depending on the length of the heating hose, this can save a considerable amount of cable length for connecting the hose. However, this is not necessary. Alternatively, at least two longitudinally extending heating sections can be provided, which are nevertheless equipped with contacts at opposite longitudinal ends for applying a heating voltage or current. Alternatively or additionally, each heating section can have its own contact.

[0027] At the opposite end, relative to the electrical contacts and the connection for the heating voltage or current, the at least two heating sections can be electrically connected to each other to close the corresponding circuit. For simplicity, the at least two heating sections can be connected to each other via an electrically conductive clamp, which is provided to make contact with the heating sections. The clamp should then be electrically conductive to such an extent that the at least two heating sections are electrically connected to each other via the clamp. As mentioned previously, the term "clamp" can be interpreted very broadly in this context. If necessary, the term "clamp" can also include elements that are not usually referred to as clamps.The clamps should be positioned on or within a corresponding section of the heating hose and make electrically conductive contact with at least one heating section or electrically connect several heating sections together. Bands, O-rings, and similar components, particularly circumferential ones, are also suitable. The clamps do not necessarily have to be made of a metallic material. They can also be made of a plastic containing a finely dispersed electrically conductive filler, similar to the heating hose itself. Alternatively, the clamp can be designed as heat-shrink tubing for shrinking onto the heating hose, similar to the heating hose itself.

[0028] In the case of at least two heating sections, at least two contacts for applying the heating voltage or current can be assigned to one end of the heating hose. Supplying the heating voltage or current to the heating hose from one end may then be sufficient. For the sake of simplicity, each heating section can be assigned one contact to save unnecessary contacts and wires.

[0029] The at least two heating sections can also be connected to each other via at least two connecting sections, which can extend at least substantially over the entire longitudinal extent of the heating hose. The connecting sections can have an electrical conductivity that means they can be considered, at least in principle, as being electrically connected in parallel. If the connecting sections have a significantly, and in particular much, lower resistance than the heating sections, the heating hose can be considered in an equivalent circuit diagram as a parallel connection of the heating resistances of the heating sections. Therefore, the heating resistance of the heating sections can decrease with increasing length of the heating hose. The power output per unit length of the heating hose then increases with increasing length.In contrast, with heating elements connected in series, the heating resistance can increase with the length of the heating hose, and the power output per unit length decreases. Therefore, in such a series connection, the heating elements of the heating sections should be specifically adjusted to provide the desired power output per unit length. Connecting the heating elements in parallel is more practical with regard to the manufacture and use of the heating hoses. The power output per unit length is then not limited for a given voltage from the power source.

[0030] For this purpose, the connecting sections, in contrast to the heating sections, have such low resistance that no significant or a very small, in particular negligible, heat flow is generated in the connecting sections compared to the heating sections. The specific resistances of the at least two heating sections can therefore each be at least twice as high, preferably at least five times as high, and in particular at least ten times as high, as the specific resistances of the at least two connecting sections.

[0031] Alternatively or additionally, at least two connecting sections can be co-extruded with the heating sections. The conductivity of the connecting sections can then be specifically adjusted in this area by introducing conductive fillers into the matrix of a thermoplastic material. This filler need not necessarily be the same thermoplastic material and / or material as in the heating sections. Alternatively or additionally, at least one metallic wire, one metallic strip, and / or one metallic wire mesh can be provided in the connecting sections. The wire, the metallic strip, and / or the wire mesh can be incorporated into the thermoplastic material of the connecting section or be used up on it, for example, after the co-extrusion of the heating hose and / or tubular hose.The increased conductivity in the area of ​​the connection sections can alternatively or additionally be achieved by applying a conductive coating, especially in the form of a paint, to the area of ​​the connection sections.

[0032] To enable varying heating of the pipeline, container, and / or fitting across the circumference of the heating hose, at least one heating section can be provided circumferentially over a length of less than 70%, preferably less than 50%, and particularly less than 30% of the circumference. The remaining part of the circumference of the heating hose can then be insulated or partially formed by at least one further heating section.

[0033] In a first particularly preferred method for manufacturing a heating hose, the raw hose can be co-extruded from at least two different extrudates, wherein at least one extrudate does not contain any electrically conductive filler. An electrically non-conductive non-heating section extending longitudinally and / or an inner and / or outer circumferential, electrically non-conductive non-heating section can then be co-extruded with the at least one extrudate, which contains at least substantially no electrically conductive filler.

[0034] If a section formed with the non-conductive extrudate extends longitudinally along the heating tube, corresponding areas can be selectively excluded from heating. If at least two such longitudinally extending sections of the heating tube are provided, these can circumferentially separate two separate, electrically conductive heating sections from each other, so that the current in these heating sections can flow in different, in particular opposite, directions.

[0035] By co-extruding an inner, circumferential non-heating section, such as a non-heating layer, electrical insulation can be provided between the heating hose and the object enclosed by the heating hose for heating. If, additionally or alternatively, an outer circumferential non-heating section, such as a non-heating layer, is provided, reliable electrical insulation of the heating hose is ensured against any electrically conductive objects that may be in contact with the outside of the heating hose. This is preferred, for example, for safety reasons and / or to prevent short circuits.

[0036] Alternatively or additionally, two longitudinally extending heating sections, separated at least substantially from each other circumferentially, can be co-extruded from at least one extrudate containing at least one electrically conductive filler. This allows the current to flow in one direction in one heating section and in the opposite direction in the other heating section, in order to provide varying current densities and / or to allow the heating hose to be connected to the heating voltage or current at only one end.

[0037] In order to electrically connect at least two heating sections, a circumferential clamp or another, in particular circumferential, connection can be provided which is electrically conductive at least in sections and is designed to contact the heating sections there, at least in the connection area between two circumferentially adjacent heating sections.

[0038] A previously manufactured raw tube, particularly by extrusion, can be irradiated with electrons before expansion, causing the thermoplastic molecules to cross-link. This imparts a certain shape memory to the raw tube for subsequent shrinking. Alternatively, the raw tube can be heated before expansion and cooled afterward. This also imparts a certain shape memory. Upon reheating, the heated tube contracts and can then be shrunk onto an object. This principle is known from the production of electrically insulating heat-shrink tubing.

[0039] The invention will now be explained in more detail with reference to a drawing that merely illustrates exemplary embodiments. The drawing shows Fig. 1A-B a method according to the invention for producing a heating hose according to the invention and a method according to the invention for shrinking the heating hose, each in a schematic representation, Fig. 2 a second heating hose according to the invention in a perspective side view, Fig. 3 a third heating hose according to the invention in a perspective side view, Fig. 4 a fourth heating hose according to the invention in a perspective side view, Fig. 5 a fifth heating hose according to the invention in a perspective side view and Fig. 6A-C shows a sixth heating hose according to the invention in a perspective side view, an equivalent circuit and a perspective sectional view.

[0040] In the Fig. Figure 1A describes a process for manufacturing a heating hose 1. In this process, a raw hose 7 is first extruded through a suitable die 6 using an extruder 2 and an extrudate 3 comprising a thermoplastic material 4 and a particulate filler 5 consisting of electrically conductive, fine particles. The electrically conductive particles of the filler 5 are either finely dispersed in the thermoplastic material 4 within the extruder 2, or a raw material consisting of a thermoplastic material 4 in which the filler 5 is already finely dispersed is fed to the extruder 2. The raw hose 7 extruded in this way then has a matrix of the thermoplastic material 4 as a continuous phase, in which the particulate filler 5, consisting of electrically conductive particles at least section by section, is finely dispersed as a dispersed phase.The pipe hose 7 is therefore electrically conductive, with the electrical conductivity of the pipe hose 7 being very homogeneously distributed in the pipe hose 7 or the corresponding heating section 8.

[0041] After extrusion, the raw tube 7 is moved through or placed in an irradiation device 9, where it is irradiated with electrons. This irradiation causes the molecules of the thermoplastic material 4 to cross-link with one another. Such irradiation devices 9 are generally known from other applications.

[0042] In the described and thus preferred method, the finished cross-linked raw tube 7 is cut to size and then heated by means of an external heat source 10. The heated raw tube 7 is then stretched radially beyond its elastic yield strength, as indicated by the arrows. This increases the diameter d of the extruded raw tube 7 to the diameter D of the correspondingly expanded heating tube 1. The expanded heating tube 1 is then cooled by means of a cooling device 11 and fitted with electrical contacts 12. The ratio of the diameters d and D may represent the shrinkage factor of the heating tube 1, which may, but need not, correspond to the diameter ratio.Whether this is the case is determined by whether the heating hose 1, which is not attached to an object, could theoretically shrink to the diameter d of the raw hose 7 or not.

[0043] The heating hose 1 does not necessarily have to be fitted with electrical contacts 12. This can be advantageous for pre-assembly and easier, subsequent installation of the heating hose 1. In this case, the contacts 12 should preferably be captive and permanently attached to the heating hose 1. However, in other cases, it may be desirable to attach the contacts 12 only after or shortly before the installation of the heating hose 1. In such a case, the final length of the heating hose 1 acting as a heating element can be determined on-site and thus very precisely. For example, the heating hose 1 is cut to the exact required length on-site and then fitted with contacts 12 at opposite ends or with a contact 12 at only one end.

[0044] The heating hose 1, now completed in this respect, can then be transported to its place of use, where the heating hose 1 is inserted into the Fig. The heating hose 1 is pushed onto a pipe 13 as described in Figure 1B and is thus the preferred method. The pipe 13 has a diameter R that is larger than the diameter d of the pipe hose 7 but simultaneously significantly smaller than the diameter D of the heating hose 1 in its expanded state. In a next step, the heating hose 1 is connected via the electrical contacts 12 to a voltage or current source 14, which applies a heating voltage or heating current to the heating hose 1. In principle, either a direct current (DC) or alternating current (AC) voltage can be applied. The heating hose 1 is essentially formed by a conductive heating section 8, the conductivity of which is caused by the conductive particles of the filler 5 finely dispersed in the thermoplastic polymer 4.The resistance of the heating section 8 is so high that heat is generated as a result of the heating voltage or current applied to the heating hose 1. This heat is so high that the heating hose 1 is heated to such a high temperature that it contracts on its own, i.e., shrinks, as is known from electrically non-conductive heat shrink tubing. The heating hose 1 shrinks to such an extent that it is shrunk firmly and in full contact with the pipe 13.

[0045] The heating hose 1, which has been shrunk onto the pipe 13 in this way, can in the future be supplied with a heating voltage or a heating current as desired, although this does not lead to any further shrinkage of the heating hose 1, but merely to heat generation and heating of the pipe 13. Thus, the pipe 13 can be heated from the outside by applying a suitable voltage or current to the heating hose 1 in the sense of trace heating.

[0046] The shrinking of the heating hose 1 can also be achieved, if required, without applying an electrical voltage or current to the heating section 8 via the contacts 12 of the heating hose 1. Instead, the heating hose 1 can be shrunk inductively without contact by applying an alternating magnetic field. The alternating magnetic field induces a voltage in the heating section 8, which leads to eddy current losses that cause the heating hose 1 to heat up. Once a sufficient temperature is reached, the heating hose 1 shrinks analogously to how it would shrink if a voltage or current were applied to the contacts 12 of the heating hose 1. A sufficient temperature can also be achieved by applying hot air from a hot air blower to the heating hose 1.

[0047] In the Fig. Figure 2 shows a perspective view of a heating hose 20, which is pulled onto and shrunk onto a pipe 13. The heating hose 20 is formed from a continuous layer of a mixture of a thermoplastic polymer 4 and a finely dispersed, electrically conductive, particulate filler 5. The heating hose 20 therefore forms a continuous heating section 21 in both the longitudinal and circumferential directions. The entire heating section 21, and thus the entire heating hose 20, can therefore be subjected to a heating current from one end to the other when the heating hose 20 is connected to a heating voltage or a heating current.For this purpose, the opposite longitudinal ends of the heating section 21 in the illustrated and thus preferred heating hose 20 are provided with circumferential clamps 26, which are connected to a voltage supply or power supply for applying the heating voltage or heating current. The heating current thus flows through the heating section 21 and thereby generates heat, which is transferred to the pipe 13 partially enclosed by the heating hose 20. In this way, a medium flowing through the pipe 13 can be heated.

[0048] In the Fig. Figure 3 shows another heating hose 23 in a perspective view, although for the sake of clarity, the additional pipework has been omitted. The heating hose 23 is made from a co-extruded raw hose. Four different areas are created around the circumference during co-extrusion. Two of these areas are heating sections 24, which contain a thermoplastic material 4 and a finely dispersed, electrically conductive filler 5. The heating sections 24 are electrically conductive and can serve as heating resistors. Two other areas are non-conductive, non-heating sections 25. These non-heating sections 25 are therefore not suitable as heating resistors.It cannot be ruled out that the non-heating sections 25 contain an electrically conductive filler 5, however, the proportion of the filler 5 is so small and its resistance so high that the non-heating sections 25 hardly conduct the electric current.

[0049] The heating sections 24 and the non-heating sections 25 are arranged alternately around the circumference, so that the heating sections 24 are separated circumferentially by the non-heating sections 25. In the illustrated and thus preferred heating hose, the heating sections 24 and the non-heating sections 25 extend with at least substantially a constant width over at least substantially the entire length of the heating hose 23. A clamp 26 is provided at one longitudinal end of the heating hose 23, which is electrically conductive and contacts the heating sections 24 on the one hand and electrically connects them to each other on the other. At the end of the heating hose 23 opposite the clamp 26, an electrical contact 27 is provided on each heating section 24, which can be connected to a voltage or current source 14 to apply the heating voltage or heating current.In this case, the heating current flows through a heating section 24 to the clamp 26 and through the clamp 26 into the other heating section 24, in order to flow back to the voltage source 14 in this heating section 24. This generates heat which can be transferred to the object that is at least partially enclosed in the heating hose 23.

[0050] A clamp could, for example, be a band or O-ring made of a circumferentially conductive plastic, at least in sections. The plastic could contain a finely dispersed, electrically conductive filler, at least in the relevant areas. If necessary, the band could be made of the same plastic and / or contain the same filler as the rest of the heating hose 1. The circumferential band could also be designed as heat-shrink tubing, like the actual heating hose 1, and shrunk onto the pipe 13 or another object to be heated, together with the actual heating hose 1. It would also be conceivable to cut off an end piece of the heating hose 1, rotate it by 90°, for example, and pull it over the corresponding end of the heating hose 1 to form a clamp for electrically connecting the heating sections 24 at that end of the heating hose.The term "Schelle" can therefore be understood very broadly as needed and is used here as a kind of general umbrella term for the sake of better understanding, also to avoid unnecessary repetitions.

[0051] In this context, it is understood that instead of the clamp 26, another means may be provided to connect the heating sections 24 section by section. These means can also be integrated into the hose material, for example by providing a sufficient quantity of electrically conductive filler 5, similar to the heating sections 24. It is also conceivable that more than two heating sections 24 and, accordingly, several non-heating sections 25 between them are provided.

[0052] In the Fig. Figure 4 shows a heating hose 30 which has a heating section 31 and a non-heating section 32 around its circumference. The heating section 31 and the non-heating section 32 are essentially the same as the heating sections 24 and the non-heating sections 25 of the heating hose 23 according to Fig. 3. The heating section 31 and the non-heating section 32 extend over the entire longitudinal extent of the heating hose 30 and each form a part of the circumference of the heating hose 30. The electrical contacts 22 are located at opposite ends of the heating section 31 to apply a heating voltage or heating current to the heating hose 30. Since the heating section 31 in the illustrated and thus preferred heating hose 30 extends only over approximately half the circumference, a pipeline can be selectively heated from one side using the heating hose 30, but not from the other side, even if this were desirable.

[0053] In the Fig. Figure 5 shows a heating hose 33 formed from three concentrically arranged layers 34, 35, 36, all of which are firmly bonded together. The three layers 34, 35, 36 are preferably formed together by co-extrusion. The inner and outer layers 34, 36 are designed as non-heating sections 37 over their entire circumference, which can also be referred to as non-heating layers. The inner layer 34 and the outer layer 36 contain so little electrically conductive filler 5 that these two layers 34, 36 do not conduct, or conduct almost none of, the electric current applied to the middle layer 35 of the heating hose 33.The inner layer 34 and the outer layer 36 thus act as electrical insulation against the middle layer 35, which in the illustrated and thus preferred heating hose 33 is designed over its entire circumference as a heating section 38, which can also be referred to as a heating layer.

[0054] However, this is not strictly necessary. For example, the middle layer 35 could contain several heating sections 38 and one or more non-heating sections 37. It is also conceivable that several middle layers 35 exist, each with a different configuration of heating section 38. Alternatively or additionally, the inner layer 34 (non-heating layer) or the outer layer 36 (non-heating layer) could be omitted. In the illustrated heating hose 33, only the inner layer 35 (heating layer) conducts the electric current. Thus, heat is generated only in the inner layer 35 through the dissipation of electrical energy. However, this heat can still be used, for example, to heat a pipe 13 without subjecting it to an electric current. Furthermore, the heat is sufficient to shrink the heating hose onto the pipe 13.

[0055] In the Fig. Figure 6A shows another heating hose 40 in a perspective view. The heating hose 40 is manufactured, for example, from a co-extruded raw hose. Four different areas are created around the circumference during co-extrusion. Two of these areas are heating sections 41, which consist of a thermoplastic material 4 and a finely dispersed, electrically conductive filler 5. The heating sections 41 are electrically conductive and can serve as heating resistors. Two further areas are connecting sections 42 with a significantly lower electrical resistance compared to the heating resistors of the heating sections 41.

[0056] The connecting sections 42 therefore do not form a heating resistance of the heating hose 40. Each connecting section 42 is provided with a contact 43 for connection to a heating voltage or heating current via the voltage or current source 14. In the illustrated and thus preferred heating hose 40, the contacts 43 are, for the sake of simplicity, located at the same longitudinal end of the heating hose 40. Due to the low electrical resistance of the connecting sections 42 compared to the heating sections 41, the connecting sections 42, unlike the heating sections 41, do not act as heating resistances, but rather connect the heating sections in parallel to each other to the voltage or current source 14.

[0057] The heating sections 41 and the connecting sections 42 are arranged alternately around the circumference, so that the heating sections 41 are separated circumferentially by the connecting sections 42. In the illustrated and thus preferred heating hose 40, the heating sections 41 and the connecting sections 42 extend with at least substantially a constant width over at least substantially the entire length of the heating hose 40.

[0058] In this case, the heating current flows longitudinally along the heating hose 40 through the connecting sections 42 and circumferentially through the heating sections 41. The heating hose 40, connected to the voltage or current source 14 via the contacts 43, can be represented as an equivalent circuit according to Fig. 6B is shown in which the heating resistors RH of the heating sections 41 are arranged in parallel to the voltage or current source 14.

[0059] In the Fig.Figure 6C shows the heating hose 40 in a perspective sectional view through the opposing connection sections 42. The length LS of the heating hose 40, the length LW of a heating element in a heating section 41, and the thickness ID of the heating hose 40 are indicated. The heating element RH of a heating section 41 is determined according to... RH=r∗LW / A=r∗LW / (ID∗LS), where U is the voltage of the voltage source 14, r is the specific resistance of the heating section 41, and A is the cross-sectional area of ​​the heating resistor or heating section. The electrical power P when the heating resistors RH of the heating hose 40 are connected in parallel is therefore calculated as follows: P=2∗U2 / RH=2∗U2∗A / (r∗LW)=2∗U2∗ID∗LS / (r∗LW).

[0060] Thus, the heating resistance RH of the heating hose 40 decreases with the length LS of the heating hose 40, and the power P increases with the length LS of the heating hose 40. The power P related to the length LS of the heating hose 40 is therefore not limited for a given voltage U of the power source 14.

[0061] The connecting sections 42 of the heating hose 40 are manufactured by co-extrusion with the heating sections 41. To provide sufficient conductivity, the connecting sections 42 may have a higher concentration of electrically conductive filler 5 than the heating sections 41 and / or a more conductive filler than the filler 5 of the heating sections 41. Wires and / or metal mesh may also be incorporated into the connecting sections 42. Metallic strips may also be incorporated into the thermoplastic material of the connecting sections 42, and the metallic strips, wires, and / or wire mesh may also be applied to the co-extruded areas of the connecting sections 42. Conductivity can also be provided by a conductive coating, in particular a conductive paint, on the co-extruded areas of the connecting sections 42. Reference symbol list 1 heating hose 2 extruders 3 Extrudate 4 plastic 5 Filler 6 nozzle 7 Pipe hose 8 Heating section 9 Irradiation facility 10 Heat source 11 Cooling unit 12 Contact 13 Pipeline 14 Voltage or current source 20 heating hoses 21 Heating section 22 Contact 23 Heating hose 24 Heating section 25 non-heating sections 26 bells 27 Contact 30 heating hose 31 Heating section 32 Non-heating section 33 Heating hose 34 inner layer 35 middle layer 36 outer layer 37 Non-heating section 38 Heating section 40 heating hose 41 Heating section 42 Connecting section 43 Contact d diameter of pipe hose Diameter of heating hose ID Thick Heating Hose R pipe diameter

Claims

[1] Heating hose (1, 20, 23, 30, 33, 40) for electrically heating a pipeline (13), a container and / or a molded part from the outside, with at least one electrically conductive heating section (21, 24, 31, 38, 41) in the form of a heating resistor for heating the heating hose (1, 20, 23, 30, 33, 40) at least section by section, characterized by, that the heating hose (1, 20, 23, 30, 33, 40) is designed as a heat shrink hose with a diameter (D) that can be shrunk at least section by heating for shrinking onto the pipe (13), the container and / or the molded part, and that the at least one heating section (21, 24, 31, 38, 41) comprises at least one thermoplastic material (4) and at least one electrically conductive filler (5) finely dispersed in a matrix of the at least one thermoplastic material (4), and that the at least one electrically conductive heating section (21, 24, 31, 38, 41) is designed for application of an electrical heating voltage or an electrical heating current for shrinking the diameter (D) at least section by heating the at least one heating section (21, 24, 31, 38, 41) and / or for inductive heating of the at least one heating section (21, 24, 31, 38, 41).41) is designed via an alternating magnetic field and for at least partial shrinkage of the diameter (D) as a result of the inductive heating of the at least one heating section (21, 24, 31, 38, 41). [2] Heating hose according to claim 1, characterized by , that the at least one electrically conductive filler (5) is carbon-based, in particular carbon black and / or graphite, and / or is formed by metallic particles, preferably iron and / or copper particles, and / or that the at least one thermoplastic polymer (4) is a polyolefin, in particular polyethylene (PE) or polypropylene (PP), polyamide (PA), fluoroethylene propylene (FEP), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), Viton, polyvinyl chloride (PVC) and / or polytetrafluoroethylene (PTFE). [3] Heating hose according to claim 1 or 2, characterized by, that the heating hose (1,20,23,30,33,40) is manufactured at least in sections from a raw hose (7) formed by extrusion and / or that the heating hose (1,20,23,30,33,40) is manufactured at least in sections by widening the diameter (d) of a raw hose (7) for fitting onto the pipe (13), the container and / or the molded part. [4] Heating hose according to one of claims 1 to 3, characterized by , that the heating hose (1,20,23,30,33,40) has several at least substantially concentric layers (34,35,36) and that an inner layer (34) and / or outer layer (36) with respect to the at least one heating section (38) is electrically insulating towards the at least one heating section (38). [5] Heating hose according to any one of claims 1 to 4, characterized by, that the heating hose (20,30,33) has contacts (22) assigned to its two opposite ends for applying the heating voltage or heating current and that, preferably, the at least one heating section (21,31,38) is provided circumferentially and / or over at least substantially the entire longitudinal extent of the heating hose (20,30,33). [6] Heating hose according to any one of claims 1 to 5, characterized by , that the heating hose (23,40) has at least two heating sections (24,41) that are electrically separated from each other at least over approximately the entire longitudinal extent and that, preferably, the heating hose (23,40), in particular at one longitudinal end, has at least two contacts (27,43) for applying the heating voltage or heating current and / or each heating section (24,41) is assigned a contact (27,43). [7] Heating hose according to claim 6, characterized by, that the at least two heating sections (24) are assigned to a longitudinal end, preferably connected to each other by means of a circumferential clamp (26) that is at least partially electrically conductive, or that the at least two heating sections (41) are electrically connected in parallel to each other by means of at least two electrically conductive connecting sections (42) that extend at least substantially over the entire longitudinal extent of the heating hose (40). [8] Heating hose according to claim 7, characterized bythat the specific resistances of the at least two heating sections (41) are each at least twice as large, preferably at least five times as large, in particular at least ten times as large, as the specific resistances of the at least two connecting sections (42) and / or that the at least two connecting sections (42) are co-extruded with the at least two heating sections (41), have at least one wire, strip and / or wire mesh and / or are formed by a conductive coating, in particular a varnish. [9] Heating hose according to any one of claims 1 to 8, characterized by , that the at least one heating section (24,31,41) is provided circumferentially over a length of less than 70%, preferably less than 50%, in particular less than 30%, of the circumference. [10] Method for manufacturing a heating hose (1, 20, 23, 30, 33, 40), according to any one of claims 1 to 9, - in which a raw hose (7) with at least one heating section (21, 24, 31, 38, 41), comprising at least one thermoplastic polymer (4) and at least one conductive filler (5) finely dispersed in the matrix of the thermoplastic polymer (4), is extruded, - wherein the diameter (d) of the extruded raw tube (7) is widened, preferably by stretching and - in which, preferably, at least one heating section (21, 24, 31, 38, 41) is connected to two electrical contacts (22, 27, 43) for applying an electrical voltage or an electric current. [11] Method according to claim 10, - in which the raw tube (7) is co-extruded from at least two different extrudates (3) and - in which at least one extrudate (3) does not contain an electrically conductive filler (5) and - in which an electrically non-conductive non-heating section (32,37) extending longitudinally and / or an inner and / or outer circumferential, electrically non-conductive non-heating section (37) is co-extruded with the extrudate (3) which has at least one filler (5) which does not contain an electrically conductive material. [12] Method according to claim 11, - in which at least two longitudinally extending heating sections (24) are co-extruded from at least one extrudate (3) with at least one electrically conductive filler (5) and - in which, preferably, the at least two heating sections (24) are electrically connected circumferentially, in particular with a circumferential clamp (26). [13] Method according to any one of claims 10 to 12, - in which the raw tube (7) is irradiated with electrons after extrusion and before expansion, such that molecules of the thermoplastic material (4) are cross-linked and / or - in which the raw hose (7) is heated before expansion and cooled after expansion. [14] Method for shrinking a heating hose (1, 20, 23, 30, 33, 40), according to any one of claims 1 to 11 and / or manufactured according to any one of claims 10 to 13, - where the heating hose (1, 20, 23, 30, 33, 40) is pulled onto a pipe (13), a container and / or a molded part, - wherein at least two contacts (22, 27, 43) of at least one heating section of the attached heating hose (1, 20, 23, 30, 33, 40) are connected to a heating voltage or heating current and the heating voltage or heating current heats the at least one heating section (21, 24, 31, 38, 41) in the form of a heating resistance and / or the at least one heating section (21, 24, 31, 38, 41) is heated inductively via an alternating magnetic field and - in which the heating hose (1,20,23,30,33,40) is shrunk onto the pipe (13), the container and / or the molded part as a result of the heating of at least one heating section (21,24,31,38,41) with a reduction in diameter (D).

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