Electric heater and liquid heating container

Abstract

An electric heater and a liquid heating container wherein the electric heater for a liquid heating container comprises a base having an upper side for forming at least a portion of a floor of a liquid reservoir of the container and an underside to which an electric heating element is attached directly or indirectly. The base comprises a raised portion arranged to protrude upwardly into the reservoir, the raised portion comprising a thermal diffusion material and being arranged above the heating element such that heat generated by the heating element passes through the thermal diffusion material.

Description

Technical Field

[0001] The present utility model relates to an electric heater for a liquid heating container and a liquid heating container comprising such an electric heater, such as a kettle. Background Art

[0002] It is desirable to heat the liquid in a heating container, such as a kettle, as quickly as possible, whether it is heated to boiling or a lower temperature. To this end, high-power kettles with a power up to 3 kW have become very popular, at least in countries where a high supply voltage of 220 - 250 V AC can be used. However, increasing the power level of the heater in a liquid heating container may also increase the noise generated during the heating process. It is understood that this is related to the nucleation of small bubbles that emanate from the hot surface or near the hot surface of the kettle element, rise in the liquid, and then burst. During this process, they may generate noise equal to or greater than the normal speech volume (about 60 dBA). The hotter the element surface, the greater the speed and density of bubble generation.

[0003] For example, the known solutions for reducing the heating noise of a kettle discussed in WO 2008 / 071983 A2 may have an adverse effect on the heat transfer of the liquid being heated and may therefore increase the boiling time. This is especially true for under-floor heaters for kettles, where the electrical heating element is located below the heat-conducting base of the reservoir of the kettle, which is typically made of stainless steel. Summary of the Invention

[0004] According to one aspect of the present utility model, there is provided an under-floor heater for an electric kettle or the like, the heater comprising a raised portion including a heat-diffusing material located above the under-floor heating element so as to assist in transferring heat to the liquid to be heated. This can reduce noise and also improve the heating efficiency.

[0005] In one embodiment, the heat-diffusing material is located within or at least partially within the concave lower side of the raised portion and is preferably in good thermal contact with the concave lower side. The heat-diffusing material can be preformed or formed within the concave lower side.

[0006] Alternatively, the heat-diffusing material can be formed on or attached to the upper side of the under-floor heater so that it forms the raised portion itself.

[0007] There may be a heat-diffusing plate arranged or positioned between the heating element and the heat-diffusing material. The heat-diffusing plate can improve the heat in a direction perpendicular to the raised portion, thereby avoiding hot spots that may cause heating noise and / or improving the heat transfer to the liquid. The heat-diffusing plate can be integral with the heat-diffusing material or can be a separate component in thermal contact with the heat-diffusing material.

[0008] The raised portion can be raised relative to the central section of the plane and / or form the outer section of the substrate of the underfloor heater. The heating element is preferably arranged below the plane of the central section of the plane, for example to facilitate assembly.

[0009] The raised portion preferably tapers in the upward direction, away from the heating element and into the liquid to be heated. This can reduce noise, for example, by suppressing the bursting of bubbles. The raised portion can have a low-slope side and a higher-slope central section.

[0010] Preferably, the width of the raised portion is similar to the width of the heating element, so that efficient heat transfer can be achieved. For example, the width can be between 10 and 20 mm.

[0011] The height of the raised portion can be selected according to the limitations of the manufacturing process in order to achieve good noise reduction and / or heat transfer performance. For example, the height can be between 8 and 16 mm.

[0012] The heating element can be a sheathed heating element or a thick-film heating element.

[0013] Other aspects of the present utility model include a method for manufacturing an underfloor heater, wherein the heat-diffusing material is either preformed and then assembled to be at least partially located within the concave lower side of the raised portion, or formed within the concave lower side of the raised portion.

[0014] The scope of the present utility model extends to include a liquid heating container with an underfloor heater, such as a kettle, etc. Description of the Drawings

[0015] Specific embodiments will now be described with reference to the following drawings.

[0016] Figure 1 is an exploded cross-sectional view of an underfloor heater in an embodiment of the present utility model.

[0017] Figure 2 is an assembled cross-sectional view of the underfloor heater in this embodiment.

[0018] Figure 3 is a cross-sectional view of a part of an underfloor heater including a heating element.

[0019] Figure 4a is a plan view of the underfloor heater as seen from above.

[0020] Figure 4b is a plan view of the underfloor heater as seen from below.

[0021] Figure 5It is a cross-sectional view of a kettle including a bottom plate heater.

[0022] Figure 6 It is a flow chart of the first method for forming the bottom plate heater.

[0023] Figure 7 It is a flow chart of the second method for forming the bottom plate heater. Detailed implementation mode

[0024] The electric heater for a liquid heating container in an embodiment of the present invention includes an electrical heating element 1, such as a sheathed heating element disposed on the lower side (i.e., the dry side) of a stainless-steel base 2, the base 2 forming at least a part of the bottom plate of an electric kettle 50, and can be attached to the side wall 51 of the electric kettle directly or indirectly (e.g., via an adapter ring), as Figure 5 shown. Such attachment can use the applicant's Easifix (RTM) system, as described, for example, in WO99 / 17645 and its developments. Alternatively, the base 2 can be directly welded to the metal side wall of the kettle, or can be arranged to be sealed on the glass wall of the kettle, as described, for example, in WO2002 / 001992.

[0025] In the following description, terms indicating orientation or direction (such as "lower" and "upper") are with reference to the orientation in which the kettle stands upright on a surface. References to "central", "inner" and "outer" are with reference to the nominal central vertical axis of such a kettle.

[0026] As Figure 5 shown, the kettle 50 has a reservoir or liquid reservoir 52, the bottom of which is formed by the base 2 and the sides of which are formed by the side wall 51. The kettle 50 has a base portion 53, which is attached to the side wall 51 and / or the base 2 to form a bottom plate compartment 54, which can accommodate, for example, a kettle controller for controlling the switch of the element 1 to heat the water in the reservoir 52 to a desired temperature, such as boiling. The main power supply can be supplied to the kettle 50 through a power cord or a wireless connector. Conventionally, the kettle 50 also has a handle 55, a lid 56 and a spout 57. Embodiments of the present invention can alternatively be used with other types of liquid heating containers (such as hot water urns, Turkish teapots, hot water jugs, wort boiling kettles, etc.). Embodiments of the present invention are not limited to water boiling containers, because bubbles formed by local boiling may also generate noise before the main body of the liquid reaches the boiling point. Therefore, embodiments of the present invention are capable of being applied to liquid heating containers designed to heat a liquid to a sub-boiling temperature.

[0027] The base 2 is made of a stainless steel plate and has a central section 2a with a substantially horizontal plane, a raised portion 2b positioned radially outward from the central section 2a, and an outer edge 2c which may form a substantially vertical flange around which a sealing ring is arranged to seal the side wall of the kettle, for example using the Easifix (RTM) system described above.

[0028] The material thickness of the base 2 can be in the range of 0.5 mm to 4 mm, depending on the structural and / or heat conduction requirements.

[0029] The raised portion 2b is configured to be aligned with the heating element 1, for example opposite to and directly above the heating element 1. When viewed from above, as Figure 4a shown, the raised portion 2b can be substantially circular / annular or in the form of a circular section / annular section. When viewed from below, as Figure 4b shown, the heating element 1 can be in the form of a circular section / annular section, with cold tails 1a, 1b arranged at either end of the annular section for connecting electrical energy to the heating element 1. When the raised portion 2b is in the form of an annular section, this can be aligned with the annular section of the heating element 1; for example, the raised portion 2b can have a lower section which is close to or at the level of the central section 2a of the plane and is located between the cold tails 1a, 1b of the heating element 1.

[0030] The sheathed heating element 1 can include an electric heating wire or coil which is wrapped in a metal sheath (such as an aluminum sheath) filled with a heat-conducting but electrically insulating material (such as magnesium oxide).

[0031] The heating element 1 is attached to the lower side of a diffuser plate or heat diffuser plate 3 which is made of aluminum, for example. The upper side of the diffuser plate 3 is provided with a heat-diffusing material 4 which is in the form of fitting into the concave lower side of the raised portion 2b so as to form a heat conduction bridge between the diffuser plate 3 and the base 2. For example, the cross-section of the raised portion 2b can be generally triangular or tapering upwards, as shown in the figure, and the heat-diffusing material 4 can have a complementary generally triangular and / or upwards-tapering cross-sectional shape which fits into and makes thermal contact with the lower side of the raised portion.

[0032] As Figure 3 shown by the dashed arrows in the figure, the heat generated by the heating element 1 flows through the diffuser plate 3 and the heat-diffusing material 4 to the raised portion 2b of the base 2 and enters the water being heated through the base 2. The heat can also flow laterally into the central section 2a and / or the outer edge 2c through the diffuser plate 3, spreading the heat and reducing the local maximum temperature of the base 2, thereby reducing the formation of steam bubbles during the heating process.

[0033] The raised portion 2b increases the surface area of the base 2 above the heating element 1, thus reducing the local power density and temperature on the upper surface of the base 2, thereby reducing the formation of steam bubbles during heating, and thus reducing the heating noise. The arrangement of the raised portion 2b can also improve heat conduction in the water by increasing the surface area of the base 2 above the heating element 1 and / or by promoting the convection of the heated water. In addition, the cross-sectional profile of the raised portion 2b can suppress the rupture of steam bubbles when they rise along the surface of the raised portion 2b. One or more of these effects can result in effects of noise reduction and / or heat transfer improvement, and the advantages of the embodiments of the present invention do not depend on any particular operating theory.

[0034] Relative to a conventional flat base, the raised portion 2b can increase the stiffness of the base 2, thereby reducing or altering vibrations in the base 2, such as mains hum caused by the heating element 1, and these vibrations may cause heating noise. The increased stiffness of the base 2 can alternatively or additionally reduce the noise generated by bubble nucleation and rupture by changing the natural frequency or resonance frequency of the component(s).

[0035] As Figure 3 shown, the cross-sectional profile of the raised portion 2b can include: side portions 2b1, 2b3 with a low slope (e.g., 25 - 50°) to increase the surface area of the base 2 above the heating element; and an intermediate section 2b2 with a higher slope (e.g., 60 - 85° or even partially 90°) to form a peak that protrudes upward into the cooler water, thereby promoting convection. As shown, the intermediate section 2b2 can have a slope that varies with the radius, such as having a vertical or nearly vertical side and a central circular / rounded portion. The side portions 2b1, 2b3 can also have a slope that varies with the radius. Other cross-sectional shapes can be used, but generally an upwardly tapering shape is advantageous because its peak remains relatively cool, thereby forming a thermal gradient that draws heat away from the heating element.

[0036] The width of the cross-section of the raised portion 2b is preferably approximately equal to or slightly greater than the width of the heating element 1. For example, the width of the raised portion can be in the range of 10 - 20 mm, but can also be greater or less than this range, depending on the width of the heating element 1.

[0037] The height of the raised portion 2b (e.g., the height above the central section 2a of the plane) is preferably approximately equal to its width. For example, the height of the raised portion 2b can be in the range of 8 - 16 mm; this may depend on the process used to form the raised portion 2b, which may limit the radius of curvature that can be achieved.

[0038] In an alternative embodiment, the diffuser plate 3 and the heat-diffusing material 4 may be formed as an integral part. In another alternative embodiment, the diffuser plate 3 may be omitted, and the heating element 1 may be directly attached to the lower side of the heat-diffusing material 4, the width of which lower side may be greater than the width of the heating element 1. The heating element 1 is preferably not located within the raised portion 2b, but below the plane of the central section 2a.

[0039] In another alternative embodiment, the raised portion 2b of the base 2 may be omitted, and the heat-diffusing material 4 may be attached to the upper surface of the base 2 and located above the heating element 1.

[0040] Figure 6 Generally shown is a method of forming a heater in an embodiment, in which the heat-diffusing material 4 is preformed before being positioned below the raised portion 2b. In step S1, the base 2 is formed, for example, by pressing a stainless steel sheet. In step S2, the heat-diffusing material 4 is formed as a separate part or group of parts from the base 2. For example, the part or group of parts may form a diffusion material ring. The order of step S1 and step S2 may be reversed or they may be performed simultaneously.

[0041] In step S3, one or more parts forming the heat-diffusing material 4 are positioned on the concave lower side of the raised portion 2b. If the diffuser plate 3 is a separate part from the heat-diffusing material 4, then in step S4 the diffuser plate 3 may be attached to the base 2 and / or the lower surface of the heat-diffusing material. The heating element 1 may also be attached at this stage, or may have been previously attached to the diffuser plate 3 (if present) or to the lower side of the heat-diffusing material 4.

[0042] The heat-diffusing material 4 may be formed by, for example, pressing, casting or extrusion. As an alternative to aluminum, the heat-diffusing material 4 may be formed of one or more alternative or additional materials such as magnesium oxide.

[0043] Figure 7 Generally shown is an alternative method of forming a heater in an embodiment, in which the heat-diffusing material 4 is formed within the concave lower side of the raised portion 2b. In step S10, the base 2 is formed as in step S1 above, for example. In step S11, the diffuser 4 is formed within the concave lower side of the raised portion 2b. Before attaching the diffuser plate 3 and / or the heating element 1 as in step S12, the heat-diffusing material 4 may be formed by pouring or compacting a material into the concave lower side of the raised portion 2b of the base 2, which concave lower side may be used, for example, as a mold for forming the heat-diffusing material 4.

[0044] The shape of the raised portion 2b depends at least in part on the process of forming the base 2 and the requirements for the structural integrity of the base 2. For example, the raised portion 2b is not necessarily circular / annular in a plan view; it may have an annular section form that matches the shape of the annular section of the heating element 1.

[0045] The heating element 1 can be a thick film element instead of a sheathed heating element. For example, the heating track is deposited on the lower side of the element plate instead of the diffuser plate 3. In this case, the raised portion can be arranged above the heating track. There can be multiple heating tracks, and thus multiple raised portions, with the width of each raised portion being approximately the same as or wider than the heating track.

[0046] Although the above specific description mainly relates to an electric kettle, a similar heating arrangement can also be provided in other water heating containers (such as urns, Turkish teapots, etc.). Although the above noise problem mainly occurs when heating water, some embodiments can be applied to containers for heating other liquids, where a similar noise problem may also occur.

[0047] Alternative embodiments

[0048] Alternative embodiments that may occur to those skilled in the art after reading the above description may also fall within the scope of the present utility model as defined by the appended claims.

Claims

1. An electric heater for a liquid heating container, the heater comprising a base having an upper side and a lower side, the upper side being adapted to form at least a part of the bottom plate of the liquid reservoir of the container, and an electrical heating element being directly or indirectly attached to the lower side, wherein, The base includes a raised portion that is arranged to project upwardly into the reservoir, the raised portion including a heat diffusion material and being arranged above the heating element such that heat generated by the heating element passes through the heat diffusion material.

2. The electric heater according to claim 1, wherein, The base includes a plate, and the raised portion is formed in the plate, wherein the heat diffusion material is arranged at least below the raised portion of the plate.

3. The electric heater according to claim 2, wherein, The heat diffusion material is at least partially located within the concave lower side of the raised portion.

4. The electric heater according to claim 3, wherein, The heat diffusion material includes a preformed composition.

5. The electric heater according to claim 3, wherein, The heat diffusion material is formed within the concave lower side of the raised portion.

6. The electric heater according to claim 2, wherein, The heat diffusion material includes magnesium oxide or aluminum.

7. The electric heater according to claim 6, wherein, The plate includes stainless steel.

8. The electric heater according to claim 1, wherein, The electric heater includes a heat diffuser plate arranged between the heating element and the heat diffusion material.

9. The electric heater according to claim 8, wherein, The heat diffuser plate and the heat diffusion material are integrally formed.

10. The electric heater according to claim 1, wherein, The base has a planar central section, and the raised portion is arranged outwardly from the planar central section and projects upwardly from the plane of the central section.

11. The electric heater according to claim 10, wherein, The base includes an outer edge arranged outwardly from the raised portion.

12. The electric heater according to claim 10, wherein, The electrical heating element is arranged below the plane of the central section.

13. The electric heater according to claim 1, wherein, The heat diffusion material is formed on or attached to the upper surface of the base so as to form the raised portion.

14. The electric heater according to claim 1, wherein, The raised portion tapers in the upward direction.

15. The electric heater according to claim 14, wherein, At least a part of the raised portion is triangular in cross-section.

16. The electric heater according to claim 14, wherein, The raised portion has at least one side portion with a low slope and an intermediate section with a higher slope.

17. The electric heater according to claim 1, wherein, The raised portion is annular or an annular section in a plan view.

18. The electric heater according to claim 1, wherein, The width of the raised portion is greater than or equal to the width of the heating element.

19. The electric heater according to claim 18, wherein, The width of the raised portion is between 10 mm and 20 mm.

20. The electric heater according to claim 1, wherein, The height of the raised portion is between 8 mm and 16 mm.

21. The electric heater according to claim 1, wherein, The heat diffusion material includes magnesium oxide or aluminum.

22. The electric heater according to claim 1, wherein, The base includes stainless steel.

23. The electric heater according to claim 1, wherein, The electrical heating element includes a sheathed heating element.

24. The electric heater according to claim 1, wherein, The electrical heating element includes a thick film heating element.

25. A liquid heating container, wherein, The liquid heating container includes the electric heater as claimed in claim 1.

Images