Heating device and water-conducting domestic appliance with such a heating device

Abstract

A heating device for heating liquids, and in particular for generating steam, has an internally arranged flow-through water pipe, which consists at least partially of inductively heatable material. An annular outer water chamber with inner and outer walls extends around the flow-through water pipe at a distance. A circulating liquid pipe runs multiple times around the flow-through water pipe in this outer water chamber in a helical pattern and rests against the flow-through water pipe. An induction heating coil is provided radially outside the circulating liquid pipe and the outer water chamber and extends over at least 50% of the length of the heating device. The outer water chamber, or its inner wall, is sealed against the flow-through water pipe and thermally connected to it.

Description

Area of ​​application and state of the art

[0001] The invention relates to a heating device for a water-conducting household appliance and to such a water-conducting household appliance.

[0002] DE 102014206592 A1 discloses a heating device for heating water. A closed water pipe runs helically around a heater, so that the water is heated by the heater as it flows through. Task and solution

[0003] The invention is based on the object of creating a heating device for a water-conducting household appliance and such a water-conducting household appliance with which problems of the prior art can be solved and, in particular, it is possible to use the heating device efficiently during operation of the household appliance and also to clean it well.

[0004] This object is achieved by a heating device having the features of claim 1 and by a water-conducting household appliance having the features of claim 13. Advantageous and preferred embodiments of the invention are the subject of the further claims and are explained in more detail below. Some of the features are described only for the heating device or only for the household appliance. However, they are intended to be able to apply independently and independently of one another to both the heating device and the household appliance. The wording of the claims is incorporated into the description by express reference.

[0005] It is provided that the heating device for heating liquid and in particular for generating steam has an internally arranged continuous water line, which is preferably designed as a straight pipe. This inner continuous water line has inductively heatable material or consists at least partially of inductively heatable material. It also has an annular outer water chamber with a distance around the inner continuous water line, which has an inner wall and an outer wall. This annular outer water chamber can lie directly against the inner continuous water line, in particular for the best possible heat transfer, which will be explained in more detail below. It has a circulating liquid line in the outer water chamber, which runs in this and several times around the inner continuous water line in a helical shape. In this case, it lies against the continuous water line.

[0006] According to the invention, an induction heating coil is provided radially outside the circulating liquid line and preferably outside the outer water chamber. This supplies the energy to heat liquid, and preferably water, with the heating device, in particular also to generate steam. The induction heating coil runs in a helical shape over at least 50% of the length of the heating device. The outer water chamber and its inner wall are sealed against the inner flow-through water line and connected to each other in a thermally conductive manner. This allows the liquid or water to be heated inductively and thus very quickly and easily controlled. Inductive heating avoids potentially high temperatures such as those encountered with resistance heaters. Furthermore, energy transfer and thus heat input can also occur over somewhat greater distances, possibly even through other components.The design of the induction coil advantageously follows that of the course of the inner flow water pipe in the longitudinal direction.

[0007] In a further development of the invention, the flow-through water pipe can be designed in two parts, with an inner pipe and an outer pipe running around it, which lie directly against one another. This way, one of the pipes can be inductively heated, while the other pipe can be optimized for water transport. The inner pipe can advantageously be made of temperature-resistant plastic or stainless steel, in particular so that it is food-safe or harmless. In particular, it should be temperature-resistant and corrosion-resistant. The outer pipe can advantageously be made of a nickel-iron alloy or another material that can be inductively heated. It is separated from the flowing liquid by the inner pipe. It can also be separated from the water chamber by a wall, so that here too, no problems with corrosion arise.

[0008] In a further development of the invention, the inductively heatable material of the continuous water pipe can have a Curie point with a predetermined temperature between 90°C and 200°C, in particular between 98°C and 150°C, for this Curie point. Above the Curie point, the inductively heatable property decreases sharply, so that a type of temperature limitation can be created. This can eliminate the need for other temperature fuses, such as expensive Klixons, making the construction cheaper and simpler. The material can preferably comprise iron and nickel, which can be used to set a predetermined temperature for the Curie point.

[0009] In one possible embodiment of the invention, the circulating liquid line can be directly adjacent to the continuous water line, in particular to an aforementioned outer pipe. This should then also directly define the water chamber on the inside by the continuous water line. In another advantageous embodiment of the invention, the circulating liquid line can be separated from the continuous water line by a wall, in particular by a radially inner water chamber. In this case, the heat transfer from the heated continuous water line to the circulating liquid line is somewhat poorer, but not significantly. However, the material of such a wall can be designed to be highly thermally conductive, and it can also advantageously be relatively thin.

[0010] In a further development of the invention, the continuous water pipe can have a water pipe inlet, preferably at one end of the heating device, in particular at the lower end viewed in the vertical direction. It can also have a water pipe outlet, in particular at the other opposite end of the heating device, in particular at the upper end viewed in the vertical direction. The water pipe inlet and / or the water pipe outlet can preferably be arranged at opposite outer ends of the heating device, thereby allowing a maximum length. This allows water in the continuous water pipe to be heated as effectively as possible.

[0011] In a further development of the invention, a liquid inlet into the circulating liquid line and / or a liquid outlet from the circulating liquid line can be provided, which are arranged at opposite end regions of the heating device. Advantageously, they can be arranged extending laterally from the heating device. This can be radially outside the flow-through water line, preferably axially above a beginning and / or axially below an end of the flow-through water line or the heating device. Lateral access allows for the best possible use of available installation space.

[0012] Advantageously, the flow-through water pipe can be cylindrical and elongated or straight. In particular, it can be round-cylindrical or circular-cylindrical, so that it can be bent from a round pipe, for example. Alternatively, it can be manufactured by plastic injection molding or 3D printing.

[0013] The circulating fluid line can run in helical coils with a constant coil diameter, preferably in at least two longitudinal sections as a uniform coil. Within these longitudinal sections, the coils can abut one another to reduce the vertical installation space. In particular, the coils can lie directly against one another or touch one another.

[0014] In an advantageous embodiment of the invention, the circulating liquid line can be interrupted by a free space between two longitudinal sections. The axial length of such a free space can correspond to between 50% and 200% of the gradient of the helical course of the circulating liquid line, thus being relatively short. However, it can be sufficient for water rising from below to exit the lower longitudinal section and for heated water from the water chamber to enter the upper longitudinal section.

[0015] Particularly advantageously, one longitudinal section can be two to five times longer than the other. A lower longitudinal section can preferably be longer than an upper longitudinal section.

[0016] In a possible further development of the invention, the induction heating coil can be located against the outer wall of the water chamber, in particular wound onto it. Alternatively, the induction heating coil can be manufactured separately, in particular in the form of a tube, and slid onto the water chamber.

[0017] Preferably, a longitudinal section of the circulating liquid line runs radially within each turn of the induction heating coil so that it can be heated particularly well from the inside by the flow-through water line.

[0018] In one possible embodiment of the invention, a longer first heating section with the circulating liquid line and the induction heating coil can be provided in a lower region of the heating device, beginning at the liquid inlet. A shorter second heating section with the circulating liquid line and the induction heating coil can be provided at a distance between them, toward an upper region of the heating device or the liquid outlet. Advantageously, the liquid inlet can be provided at the lower beginning of the first heating section, while the liquid outlet is provided at the upper end of the second, upper heating section.

[0019] Preferably, the induction heating coil can be divided into two partial induction heating coils, wherein a first partial induction heating coil can be provided at the bottom of the first heating section. A second partial induction heating coil can be provided at the top of the second heating section. The first partial induction heating coil can be between 50% and 150% longer than the second partial induction heating coil, in particular between 75% and 125%. The two partial induction heating coils can either be designed independently of one another, so that they can heat independently of one another. Alternatively, they can be directly connected to one another and operated as a single induction heating coil, only with a spatial interruption.

[0020] In a further development, a further additional outlet from the outer water chamber can be provided near a lower end of the heating device, advantageously at the inlet to the flow-through water line. A second inlet or outlet of the outer water chamber can be provided near the upper end of the heating device. For example, additives such as cleaning agents or the like can be introduced at the top and discharged at the bottom to clean the entire water chamber, for example, including for descaling.

[0021] In an advantageous development, a casing can be provided around the induction heating coil to protect it. This casing can be made of plastic and thus be easily manufactured.

[0022] A water-conducting household appliance according to the invention comprises the aforementioned heating device and a power supply for the induction heating coil of the heating device. For this purpose, it also comprises a controller, and this controller is designed to detect a drop in power at the induction heating coil as soon as it has exceeded a predetermined temperature. Thus, heating can not only be automatically stopped or limited, but this can also be detected. This can be used during operation of the household appliance, for example, to limit the power supply.

[0023] In a possible further development, the induction heating coil can be made of a conductive material with a PTC effect, and / or, in a possible aforementioned heating device, the inductively heatable material of the flow-through water pipe can have a Curie point at a predetermined temperature, i.e., slightly above 100°C. Thus, at a temperature above the predetermined temperature, inductive heating no longer occurs.

[0024] The household appliance may be provided with a dosing circuit with water pipes, valves, and a dosing device for cleaning agents, etc., into one of the water pipes of the dosing circuit. The heating device, the continuous water pipe, or the circulating liquid pipe may be connected to one of the water pipes or looped into this water pipe.

[0025] These and other features emerge not only from the claims but also from the description and the drawings. The individual features may be implemented individually or in combination in an embodiment of the invention and in other fields, and may represent advantageous and individually protectable embodiments for which protection is claimed here. The division of the application into individual sections and subheadings does not limit the generality of the statements made therein. Brief description of the drawings

[0026] Embodiments of the invention are illustrated schematically in the drawings and explained in more detail below. The drawings show: Fig. 1 is a schematic representation of a washing machine according to the invention in which a heating device according to the invention is installed, and Fig. 2 is a sectional representation through the heating device according to the invention. Detailed description of the implementation examples

[0027] In the Fig. 11 shows a washing machine 11 according to the invention with a housing 12 and a drum receptacle 14, in which a rotatable drum with laundry therein is arranged in the usual way for washing. In the washing machine 11 or in the housing 12, a water guide 16 is arranged with several water pipes and an inlet from the outside and an outlet to the outside. This corresponds to the prior art. Above the drum receptacle 14, a dosing device 18 is arranged, which contains detergent or can be filled with detergent and doses this into water. This water is then applied into the drum or onto the laundry arranged therein using a corresponding nozzle device 19. This is also prior art and does not need to be explained in more detail here. In front of the nozzle device 19, a heating device 20 according to the invention is arranged. This heating device 20 will be explained in more detail below.

[0028] A drain 40 leads from the drum receiving container 14 to a filter 41, with a valve interposed therebetween. This allows the amount of water remaining in the drum receiving container 14 to be controlled. Behind the filter 41, a pump 43 with additional water lines and a valve is provided, which can be designed in a known manner. Since the heating device 20 is provided, the pump 43 itself does not need to be heated, as is known per se from the prior art. Additional water lines with valves lead back to the dosing device 18 as part of the water guide 16.

[0029] From the inlet into the washing machine 11, a water line L1 also leads to the heating device 20. In this water line L1, a throttle 45 is arranged to adjust the water pressure for the heating device 20.

[0030] The heating device 20 is connected to a washing machine control 47, which advantageously assumes all further control functions of the washing machine 11. It is further connected to a power supply 49, which provides the power for the heating device 20, in particular embodied as an inverter. This power supply 49 can be controlled by the washing machine control 47.

[0031] In the Fig. 2the heating device 20 is shown in an enlarged section. It has an outer housing 22, advantageously in the form of a round tube, which has an outer wall on the outside. An inner flow-through water pipe 24 is arranged in the outer housing 22, which runs in a straight line and advantageously also has a round or circular cross-section. The flow-through water pipe is designed in two parts, so to speak, and has, on the one hand, an inner pipe 25, which is made of plastic, for example, or alternatively of stainless steel, and meets the hygienic requirements of a washing machine. This inner pipe 25 is surrounded by an outer pipe 26 or is arranged therein, for example, in the case of plastic, also injected. The outer pipe 26 is made of a nickel-iron alloy and can therefore be heated inductively. As explained above, the alloy of the outer pipe 26 can be designed orThe tube 26 should be configured such that it has a Curie point with a predetermined temperature between slightly below 100°C and 150°C, for example, approximately 130°C. If the outer tube 26 becomes hotter than this temperature, its Weiss domains rearrange themselves, and the outer tube 26 loses its ability to be inductively heated. Thus, it can no longer heat the water flowing through the continuous water line 24 or the inner tube 25 because it itself cannot be further heated inductively.

[0032] For this inductive heating, an inductive heating system, namely a lower induction heating coil 27 with corresponding windings and an upper induction heating coil 28 with corresponding windings, run within the outer housing 22, relatively close to an outer wall. Both induction heating coils 27 and 28 each have externally directed electrical connections that are connected to the aforementioned power supply 49. Thus, the washing machine control system 47 can control the inductive heating of the continuous water line 24. If the temperature exceeds the aforementioned values ​​or the Curie point is exceeded, the outer pipe 26 is no longer heated. This, in turn, is immediately detected in the power supply 49, which can mean that the washing machine control system 47 no longer operates the induction heating coils 27 and 28 or suspends their operation for a short or longer period of time based on this temperature information.After, for example, one or two minutes, you can try to resume the inductive heating to avoid too long an interruption or too slow heating of the water.

[0033] The induction heating coils 27 and 28 can be wound directly onto the outer wall of the outer housing or the water chamber formed thereby; alternatively, they can be manufactured separately and slipped over as a single unit. They can be enclosed externally by a protective housing 29, both for electrical insulation and to protect against contamination, etc.

[0034] A circulating liquid line runs in a helical configuration within the water chamber 23 within the outer housing 22, with tightly spaced turns that are also tightly wound onto or adjacent to the inside of the water chamber 23. It can be made of plastic, for example, particularly by 3D printing. The circulating liquid line is divided into a lower circulation line 31 and an upper circulation line 32. The lower circulation line has approximately eighteen turns, while the upper circulation line 32 has just under two turns. The lower circulation line 31 extends outward with its lower end and can be connected, for example, to the water guide 16 of the washing machine 11, or possibly even to the water line L1. Its upper outlet leads into the upper region of the water chamber 23. A lower inlet into the upper circulation line 32 is arranged slightly above it.Its upper outlet, in turn, leads from the heating device 20 or from the outer housing 22 and can, for example, be led into the drum receptacle 14. Corresponding connections are not shown here, but they are easily implemented by a person skilled in the art.

[0035] During operation, the basic principle is that water flowing through the flow-through water line 24 or through the inner pipe 25 is heated and used as the main wash water for a wash cycle in the washing machine 11. Temperatures of 30°C or 40°C are often sufficient for this purpose today. Due to the noticeably large cross-section of the inner pipe 25, a relatively large quantity of water can be heated in the flow-through. This is also possible by passing the water through several times before it is brought into the drum receptacle 14, for example by means of the nozzle device 19. This water in the flow-through water line 24 is heated indirectly, so to speak, via the inductively heated outer pipe 26, which is heated by at least the lower induction heating coil 27 and advantageously also by the upper induction heating coil 28. By dividing the pipe into two, the power can be varied more effectively.Self-regulating temperature control using the Curie point has been explained above. Additionally, temperature sensors can, of course, also be provided, either in the heating device 20 itself or behind an outlet from it. Advantageously, the water flows in the... Fig. 2 from bottom to top, so that at the bottom end of the lower induction heating coil 27 there is a water line inlet mentioned above. The water line outlet is then at the opposite end of the flow-through water line 24.

[0036] The water chamber 23 contains water that flows from below into the lower circulation line 31, for example, pumped in by the pump 43. At the upper end of the lower circulation line 31, the heated water flows out and, so to speak, completely fills the water chamber 23. There, it is heated or reheated by the flow-through water line 24 or the inductively heated outer pipe 26. Due to the resulting pressure, and in particular due to the onset of steam formation, a mixture of steam and hot water enters the lower end of the upper circulation line 32. There, it is guided in almost two more turns before, after further heating, exiting the heating device 20 mainly as steam. This steam can also be directed into the drum receiving container 14 or into the drum arranged therein and onto the laundry there, for example for treating laundry exclusively with steam.Alternatively, hygiene requirements can be met or the washing machine 11 can be cleaned with hot steam, at least in the area of ​​the drum receiving container 14 and the drum.

[0037] The water in the water chamber 23, and thus also in the circulation lines 31 and 32, is also heated by the inductively heated outer pipe 26. Thus, its heat is dissipated both radially inward into the water in the continuous water line 24 and radially outward into the water in the water chamber 23 and in the circulation lines 31 and 32.

[0038] From the Fig. 2It is also clearly visible that the lower induction heating coil 27 and the lower circulation line 31 extend at approximately the same axial height, as do the upper induction heating coil 28 and the upper circulation line 32. Thus, the division of the induction heating coil into two partial induction heating coils primarily serves to more specifically heat the heated water or the generated steam. Water is also located in a space 34 between the two circulation lines 31 and 32, which is heated by the hot outer tube 26 and forced upwards into the upper circulation line 32. This space 34 thus corresponds to the free space mentioned above. In a further embodiment of the invention, it can be provided that a drain leads out of the water chamber 23, in particular at the lower end or at a lowest point of the water chamber 23.There, impurities, especially limescale or particles, can be collected and then removed, for example, from the entire washing machine 11. This can also be used to perform the aforementioned descaling.

[0039] In a further embodiment of the invention, it is also possible to manufacture not only the outer tube 26 from a material with a specific Curie point, so that a type of overtemperature protection is automatically provided. The induction heating coils 27 and 28 can also be made from a corresponding material that changes its electrical or other properties significantly above a certain temperature. A conductor material with a PTC effect is particularly suitable for this purpose. A sharp increase in the electrical resistance of the induction heating coils 27 and / or 28 at a temperature of, for example, 100°C to 120°C could be detected very quickly by the power supply 49 and used by the washing machine control 47 as a reason to reduce the heating output or stop the heating operation. This can be independent of the effect of the Curie point of the outer tube 26.

[0040] In a further embodiment of the invention, it can be provided that at least the flow-through water line 24 carries not only pure or clear water, but possibly also water already mixed with detergent or other additives. In this way, their effectiveness can potentially be influenced or specifically enhanced. This depends on whether and, if so, how the heating device 20 is integrated into the water supply 16 in the washing machine 11 or connected to its dosing device 18.

[0041] In yet another embodiment of the invention, Fig. 2A lower outlet 36 and an upper outlet 37 are shown in dashed lines. Here, water can be heated again in a continuous flow process, for example, again for the dosing device 18. Alternatively, a cleaning solution, in particular a descaler, can be introduced into the water chamber 23, for example, at the upper outlet 37. After a certain exposure time, the liquid with dissolved limescale can be discharged at the lower outlet 36 and, in particular, flushed out of the washing machine 11.

Claims

1. Heating device for heating liquid and in particular for generating steam, the heating device comprising: - an internally arranged continuous water line, preferably as a straight pipe, which comprises inductively heatable material or which consists at least partially of inductively heatable material, - an annular outer water chamber with a distance around the inner continuous water line, which has an inner wall and an outer wall, - a circulating liquid line in the outer water chamber, which runs several times around the inner continuous water line in a helical shape and rests against the continuous water line, characterized in that- an induction heating coil is provided radially outside the circulating liquid line and preferably outside the outer water chamber, - the induction heating coil runs helically over at least 50% of the length of the heating device, - the outer water chamber or its inner wall are sealed against the inner flow-through water line and are thermally conductively connected to one another.

2. Heating device according to claim 1, characterized in that The flow-through water pipe is made up of two parts, with an inner pipe and an outer pipe running around it, which lie directly next to each other.

3. Heating device according to claim 2, characterized in that the inner tube is made of temperature-resistant plastic or stainless steel and / or the outer tube is made of a nickel-iron alloy.

4. Heating device according to one of the preceding claims, characterized in thatthe inductively heatable material of the flow-through water pipe has a Curie point with a predetermined temperature between 90°C and 200°C, in particular between 98°C and 150°C, wherein the material preferably comprises iron and nickel.

5. Heating device according to one of the preceding claims, characterized in that the circulating liquid line is directly connected to the flow-through water line, in particular to an outer pipe according to claim 2.

6. Heating device according to one of the preceding claims, characterized in that the flow-through water pipe has a water pipe inlet, preferably at one end of the heating device, and a water pipe outlet, in particular at the other opposite end of the heating device, wherein preferably the water pipe inlet and / or water pipe outlet are arranged at opposite outer ends of the heating device.

7. Heating device according to one of the preceding claims, characterized in that a liquid inlet into the circulating liquid line and / or a liquid outlet from the circulating liquid line are arranged at opposite end regions of the heating device, in particular are provided laterally on the heating device, preferably radially outside the flow-through water line and axially above a start and / or axially below an end of the flow-through water line or the heating device.

8. Heating device according to one of the preceding claims, characterized in thatthe circulating liquid line is interrupted by a free area between two longitudinal sections, wherein preferably an axial length of such a free area corresponds to between 50% and 200% of a gradient height of the helical course of the circulating liquid line, wherein in particular one longitudinal section is two to five times longer than the other longitudinal section, wherein preferably a lower longitudinal section is longer than an upper longitudinal section.

9. Heating device according to claim 8, characterized in that at least in the two longitudinal sections, the turns of the circulating liquid line lie against one another, in particular directly against one another or touching one another.

10. Heating device according to one of the preceding claims, characterized in thatthe induction heating coil rests against the outer wall of the water chamber, in particular is wound onto it, wherein a longitudinal section of the circulating liquid line preferably runs radially within each turn of the induction heating coil.

11. Heating device according to claim 7 and 10, characterized in thatin a lower region of the heating device, starting at the liquid inlet, a longer first heating section with the circulating liquid line and the induction heating coil is provided and extends with a distance therebetween towards an upper region of the heating device orthe liquid outlet, a shorter second heating section with the circulating liquid line and the induction heating coil is provided, wherein the liquid inlet is provided at the lower beginning of the first heating section and the liquid outlet is provided at the upper end of the second heating section, wherein preferably the induction heating coil is divided into two partial induction heating coils and a first partial induction heating coil is provided at the bottom in the first heating section and a second partial induction heating coil is provided at the top in the second heating section, wherein in particular the first partial induction heating coil is between 50% and 150% longer than the second partial induction heating coil.

12. Heating device according to one of the preceding claims, characterized in thatan outlet from the outer water chamber is provided near a lower end of the heating device, wherein preferably a second outlet from the outer water chamber is provided near the upper end of the heating device.

13. Water-conducting household appliance with a heating device according to one of the preceding claims, characterized in that the household appliance has a power supply for the induction heating coil of the heating device with a controller, wherein the controller is designed to detect a drop in power at the induction heating coil as soon as it has exceeded a predetermined temperature.

14. Household appliance according to claim 13, characterized in thatthe induction heating coil consists of a conductor material with PTC effect, and / or that in a heating device according to claim 4 the inductively heatable material of the flow-through water pipe has a Curie point at a predetermined temperature and is no longer inductively heatable at a temperature above the predetermined temperature.

15. Household appliance according to claim 13 or 14, characterized in that the household appliance has a dosing circuit with water pipes, valves and a dosing device for cleaning agents or the like into one of the water pipes of the dosing circuit, wherein the heating device or the flow-through water pipe or the circulating liquid pipe is connected to one of the water pipes or is looped into this water pipe.

Images