HEATING MEANS, PUMP WITH SUCH A HEATING MEANS AND WATER-CONDUCTING DOMESTIC APPLIANCE

Abstract

A heating means installed in a pump for heating water during pumping has a tubular cylindrical holder that defines a heating chamber for the water. On the outside of the holder, a plurality of heating conductor tracks are connected together in series. The heating means is configured for operation of the pump in the horizontal state, such that its longitudinal axis extends horizontally. In this horizontal state, the heating means has a residual water level as a horizontal plane that lies roughly in the lower third. Apart from two heating conductor tracks, the heating conductor tracks extend below this residual water level, while said two heating conductor tracks extend above the residual water level. In the absence of cooling water on the inner surface of the heating chamber, they can overheat more quickly and be locally destroyed as an emergency safety device before the entire heating means is at risk of overheating.

Claims

1. A heating means for heating water, said heating means having: a tubular holder being closed circumferentially and defining a heating chamber for said water, a plurality of heating conductor tracks on said tubular holder, said heating conductor tracks being connected together in series and extending over a contiguous region of an outer circumference of said holder, said heating means being configured for operation in a horizontal state and being arranged in such a way that a longitudinal axis or a longitudinal axis of said holder extends substantially horizontally, wherein, in said horizontal state, said heating means has a residual water level lying between a lowest point and a highest point of said heating chamber, apart from precisely one, two or at most four of said heating conductor tracks being connected together in series, said heating conductor tracks extend below said residual water level, and said precisely one, two or at most four heating conductor tracks extend above said residual water level.

2. The heating means as claimed in claim 1, wherein precisely two said heating conductor tracks extend above said residual water level, said heating conductor tracks being guided in parallel, and connected together in series using a conductor bridge at a free end region at maximum height above said residual water level.

3. The heating means as claimed in claim 2, wherein said precisely two heating conductor tracks are connected together in such a way to have the same length above said residual water level.

4. The heating means as claimed in claim 1, wherein all said heating conductor tracks are connected together in series and have precisely two electrical terminals, one said electrical terminal at a start and one said electrical terminal at an end of a series interconnection of all said heating conductor tracks.

5. The heating means as claimed in claim 1, wherein said heating conductor tracks reach above said residual water level to from 10% to 60% higher than said residual water level.

6. The heating means as claimed in claim 1, wherein a tuning region is provided being arranged below said residual water level, wherein said heating conductor tracks extend in said tuning region next to one another and are connected together in series, there being provided between said two heating conductor tracks a shorting jumper for electrical tuning of said heating means, wherein said shorting jumper can be manufactured subsequently to reduce an electrical resistance of said series interconnection of said two heating conductor tracks.

7. The heating means as claimed in claim 1, wherein at least one temperature sensor is a discrete component and is arranged on said holder above said residual water level.

8. The heating means as claimed in claim 7, wherein said temperature sensor is arranged on said holder above said residual water level by 2% to 20% of a diameter of said holder.

9. The heating means as claimed in claim 1, wherein an electrical connection device is provided on said holder above said residual water level.

10. The heating means as claimed in claim 9, wherein said electrical connection device is arranged on a different side from said heating conductor tracks projecting above said residual water level.

11. The heating means as claimed in claim 1, wherein said holder is formed from a rectangular metal sheet by bending together and welding with a weld seam along edges mutually facing each other, said weld seam extending above said residual water level and outside said heating conductor tracks.

12. The heating means as claimed in claim 11, wherein said weld seam extends in a height range of at least 75% of a height of said heating means.

13. The heating means as claimed in claim 1, wherein all said heating conductor tracks are of identical width.

14. The heating means as claimed in claim 1, wherein said heating conductor tracks extending above said residual water level are longer than said other heating conductor tracks.

15. The heating means as claimed in claim 1, wherein all said heating conductor tracks extend parallel to one another or are of linear configuration.

16. The heating means as claimed in claim 1, wherein said heating conductor tracks are thick-film heating conductor tracks.

17. The heating means as claimed in claim 1, wherein said holder consists of metal.

18. A pump with said heating means as claimed in claim 1, wherein said heating means or said heating chamber of said heating means form at least part of said pump chamber or essentially forms said pump chamber, a pump rotor is arranged within said heating means or within said heating chamber.

19. The pump as claimed in claim 18, wherein said pump takes a form of a radial pump with an axial pump inlet being coaxial with said longitudinal axis of said holder of said heating means, and with a lateral pump outlet, said lateral pump outlet being arranged above said residual water level.

20. The pump as claimed in claim 19, wherein said pump outlet is arranged above a longitudinal axis of said holder and at a height of an uppermost region of said holder.

21. The pump as claimed in claim 19, wherein said pump outlet is arranged at a height such that water automatically exits therefrom until said water level remaining in said pump or in said pump chamber is at said residual water level.

22. A water-conducting domestic appliance with a heating means as claimed in claim 1, wherein said holder of said heating means has a longitudinal axis and is arranged in said domestic appliance with said longitudinal axis being substantially horizontal.

23. A water-conducting domestic appliance with a pump as claimed in claim 18, wherein said holder of said heating means has a longitudinal axis and is arranged in said domestic appliance with said longitudinal axis being substantially horizontal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Exemplary embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings:

[0023] FIG. 1 is a schematic functional depiction of a dishwasher according to the invention representing a water-conducting domestic appliance with a pump according to the invention,

[0024] FIG. 2 is a sectional representation through a pump according to the invention with a heating means according to the invention that is installed horizontally in the dishwasher of FIG. 1,

[0025] FIG. 3 is a developed view of the heating means of the pump of FIG. 2 showing the course of the heating conductor tracks for the heating means and

[0026] FIG. 4 shows a modification of a heating means similar to FIG. 3 with heating conductor tracks in mesh configuration.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0027] FIG. 1 is a greatly simplified depiction of a dishwasher 11 according to the invention with fundamentally known structure. The dishwasher 11 has a housing 12 and a washing compartment 13 therein. A drain 15 for exiting water extends down from the washing compartment 13. In the washing compartment 13, an upper spray arm 17a is arranged right at the top and a lower spray arm 17b is arranged right at the bottom, these being supplied via water lines. Below the washing compartment 13, a pump 20 according to the invention is arranged, specifically horizontally or with the longitudinal axis of a pump chamber extending horizontally. The pump 20 has a pump motor 21. Coming from the drain 15 on the left is a line connected to a pump inlet 22. The pump 20 takes the form of a radial pump and has a radially exiting pump outlet 24 to the side of the pump chamber. The pump outlet 24 extends via lines to the upper spray arm 17a and the lower spray arm 17b. As is known from the prior art, water is heated by the pump 20 during pumping, as specifically the pump chamber thereof is heated.

[0028] FIG. 2 shows a section through a pump 20 according to the invention, which is arranged horizontally when in operation or the longitudinal axis of which extends horizontally. The pump 20 has an impeller 25, which is driven by the above-stated pump motor 21. The impeller 25 runs inside the heating means 26, which forms or has a heating compartment 27 corresponding to a pump chamber. A tubular holder 28, in particular of circular configuration, is provided for the heating means 26. A developed view of the holder 28 is shown in FIG. 3 therebelow. It is readily apparent that the holder 28 consists of a rectangular part, in particular of a stainless steel sheet, and is bent at the left- and right-hand narrow sides of FIG. 3 to form the tube of FIG. 2. These narrow sides are joined tightly together by means of a weld seam 29, see top of FIG. 2.

[0029] It is clear from FIG. 3 that a base insulation 31, for example containing glass, is deposited on the outer surface of the holder 28, as the metallic holder 28 itself is electrically conductive. Four heating conductor tracks 33 are deposited on the base insulation 31, but more are also possible. All the heating conductor tracks 33 are configured parallel to one another and at the same time parallel to the longitudinal edges of the developed view of the holder 28. They extend fully on the base insulation 31. In precisely the same way as this base insulation 31, the heating conductor tracks 33 may also be deposited thereon using a thick-film method, in particular by screen printing.

[0030] The upper two heating conductor tracks 33a and 33b are considerably longer than the lower two heating conductor tracks 33c and 33d, here roughly twice as long. They are here of the same length, which is not essential, however, as they could also be of different lengths, both below and/above the residual water level RWHN. As is apparent from FIG. 2, when actually installed they are arranged with their left-hand ends, at which the uppermost heating conductor track 33a has a first terminal 34a, roughly at the point where a residual water level RWHN extends due to the central pump inlet 22. In FIG. 3, RWHN is shown in dashed lines close to the left-hand ends of the heating conductor tracks 33. To the right thereof, RWHN is likewise shown in dashed lines at the point where it once again intersects according to FIG. 2 with the holder 28. It is thus readily apparent that the heating conductor tracks 33a and 33b extend markedly beyond RWHN in a protrusion region 35, see also FIG. 2, right-hand side above RWHN. In this protrusion region 35, the two heating conductor tracks 33a and 33b may protrude by around 25% above RWHN, but this may advantageously be up to 60%, preferably around 40% to 50%. As stated above, it could also be just one single heating conductor track 33, for example the upper heating conductor track 33a. The lower heating conductor track 33b could then be embodied as an extension of the conductor bridge 36ab as far as the other conductor bridge 36bc and consist of material with a considerably higher electrical conductivity. It is apparent from FIG. 2 that when the pump chamber, corresponding to the heating compartment 27, is filled completely or to more than 60%, water is present opposite all the heating conductor tracks 33 on the inner surface of the holder 28, i.e., sufficiently good heat uptake from the heating conductor tracks 33 is guaranteed. In particular, on operation of the pump with an impeller 25, water is located substantially over the entire inner surface of the holder 28. If, however, the water level falls below the maximum height of the protrusion region 35 with the two heating conductor tracks 33a and 33b, uptake of the heat therefrom is no longer as good or becomes ever worse. Due to the arrangement of the pump inlet 22, RWHN is at most this high; under certain circumstances even less residual water may be present in the pump chamber or in the heating compartment 27. As the water level falls or if the water level is at RWHN, the heating conductor tracks 33a and 33b overheat in the protrusion region 35. This may also be further increased by the fact that they consist of a PTC material, and therefore their electrical resistance increases as temperature rises. If the two heating conductor tracks 33a and 33b in the protrusion region 35, which is not cooled by water, heat up, the temperature rises, as does the electrical resistance. However, this is the case only within the protrusion region 35, such that due to the small fraction of the whole, the total resistance increases only slightly. Therefore, a high current continues to flow through the heating means 26 or through the heating conductor tracks 33 thereof, which then leads to an increasing and thus under certain circumstances very high temperature in the uncooled protrusion region 35. In this case, in the fault scenario of too little water, one of the heating conductor tracks 33a or 33b in the protrusion region 35 can or even is intended to burn through or be destroyed. Current flow through the entire heating means 26 then stops immediately. The heating means 26 is then destroyed and has to be replaced. More significant damage to the entire pump 20 or even to the dishwasher 11 can, however, be avoided thereby.

[0031] It is therefore also recommended, even if the heating means 26 has more than four heating conductor tracks 33, that actually just one heating conductor track, exactly two heating conductor tracks or a maximum of four heating conductor tracks 33 protrude beyond RWHN in the protrusion region 35.

[0032] Such an above-stated fault scenario, which is intended to be handled thereby so to speak, may arise if the water supply either stops, is clogged or is not functional. It may alternatively arise if, despite the heating means 26 being operated or energized, the pump motor 21 cannot convey any water.

[0033] The two lower heating conductor tracks 33c and 33d could also still, as shown with dashed lines, extend further to the right-hand dashed line for RWHN. The lowermost heating conductor track 33b has the second electrical terminal 34b. Conductor tracks (not shown) connect the electrical terminals 34a and 34b to the electrical connector plug 43. As is apparent from FIGS. 2 and 3, the electrical connector plug 43 is arranged below or outside the weld seam 29 and in particular can be arranged, as it were uncooled, at a location above RWHN. At the same time, however, the heating conductor tracks 33 are at a significant distance therefrom.

[0034] A discrete temperature sensor 41 is arranged between the electrical connector plug 43 and the heating conductor tracks 33. It may be, for example, an SMD component. The temperature sensor 41 is also connected by way of conductor tracks (not shown) to the electrical connector plug 43, as is known from the prior art.

[0035] Further heating conductor tracks in parallel form could also be provided, for example above the upper heating conductor track 33a. These should then, however, be just as short as the lower heating conductor tracks 33c and 33d or shorter than the heating conductor tracks 33a and 33b, in particular they should not project into the protrusion region 35.

[0036] The two lower heating conductor tracks 33c and 33d have an above-stated tuning region 38. Precisely one shorting jumper 39, for example made from a similar material to the conductor bridges 36, or alternatively from a more easily depositable material, is deposited therebetween for this purpose. In this case, the shorting jumper 39 is set in place at a precisely determined location. The electrical resistance here between these two heating conductor tracks 33c and 33d and also for the series interconnection of all the heating conductor tracks 33, accordingly becomes smaller, since a specific length of these two heating conductor tracks, namely to the right beside the shorting jumper 39, is as it were electrically cut off. An electrical resistance value for the heating means 26 can thus be precisely set in known manner. Such a tuning region 38 should of course always be below RWHN and thus where it is most likely to be cooled by water below RWHN.

[0037] FIG. 4 shows a heating means 126 with a rectangular holder 128 which is a developed view of a tubular heating means for a pump similar to FIG. 2. The heating means 126 has four heating conductor tracks 133a to 133d. These heating conductor tracks are all of identical width or identically constructed, specifically in mesh form or mesh- or grid-like manner according to WO 2021/170331 A1. They have a width of around three or four grid-like meshes. This is also generally an advantageous option for the development of the heating conductor tracks 133 in addition to those of FIG. 3, which are full-surface or continuous.

[0038] On the left, they begin in each case at the RWHN shown with dash-dotted lines corresponding to FIGS. 2 and 3. The upper two heating conductor tracks 133a and 133b project to the right beyond the right-hand dash-dotted RWHN line with a protrusion region 135, where they are connected by a conductor bridge 136ab. Otherwise, a further conductor bridge 136bc is additionally provided between the heating conductors 133b and 133c and a conductor bridge 136cd between the heating conductors 133c and 133d. The terminals 134a and 134b provide an electrical connection to the heating conductor tracks 133.

[0039] On the basis of the depiction in FIG. 4 in comparison with FIG. 3, it is also easy to conceive how various developments of the heating conductor tracks might be combined. Mesh form or mesh- or grid-like heating conductor tracks corresponding to FIG. 4 can accordingly be combined, specifically in any desired way, with heating conductor tracks with a full-surface or continuous configuration corresponding to FIG. 3. For example, in a development similar to FIG. 3, the uppermost heating conductor track 33a and the lower two heating conductor tracks 33c and 33d could be of full-surface or continuous configuration, while the second uppermost heating conductor track 33b could in contrast be in mesh form or of mesh- or grid-like configuration corresponding to FIG. 4. Each heating conductor track is advantageously in itself, i.e., between the ends thereof or between the terminals 34 or conductor bridges 36, of identical construction such that there is here no change between mesh form and continuous.