EP3773125A1 - Domestic appliance with at least one heater for a tubular piece through which a fluid flows - Google Patents

Abstract

The invention relates to a water-conducting domestic appliance (1) comprising at least one channel section (14) which can be heated from the outside and through which a fluid (15) can flow. For heating purposes, a plurality of electrically interconnected heat conductor elements (16) are provided. The domestic appliance is designed such that at least some of the heat conductor elements (16) are electrically connected together in parallel and are arranged such that a component of the conductor elements is arranged in the flow direction (F) of the fluid (15).

Description

 Household appliance with at least one heater for one

 fluid-carrying pipe section

The present invention relates to a water-conducting household appliance, such as a dishwasher, in particular domestic dishwasher, according to the preamble of claim 1.

For such water-bearing household appliances, uniform heat removal from the heater by flowing fluid is particularly important for proper operation without forming excessively high temperatures at the heater. Since some users are e.g. If a domestic dishwasher does not operate as intended with salt in the softening with detergent and rinse aid, but omit one of these components, for example forgotten, then the dishwasher chemistry is not in equilibrium. On the heater then pads can form, which hinder the energy transfer into the fluid, which usually leads to a partial overheating of a heat conductor. This then usually results in a defect of the heating.

With such a behavior of users, a deposit formation can not be completely avoided.

The invention is based on the problem to achieve an improvement in the life of the heater and to avoid defects as possible.

The invention solves the problem by an article having the features of claim 1. With regard to advantageous refinements and developments of the inven tion is made to the claims 2 to 17.

Characterized in that according to the invention, at least a part of the heating elements electrically connected in parallel and is arranged with a component in the direction of flow of the fluid, it is possible on the one hand that in a partial overheating only a small portion of the heating is defective and the vast majority of the heating continue to operate can. On the other hand, the arrangement of the heating element ensures a long heat transfer path into the fluid at least almost parallel to the flow direction of the fluid.

If, for example, the household appliance comprises a dishwasher, in particular a domestic dishwasher, with a washing container for receiving items to be washed, such as dishes, glasses, cutlery or the like, wherein the items to be washed via heated and with detergent and / or rinse aid and / or desiccant added, circulating Fluid, so-called. Flushing liquor, can be acted upon, this flushing liquor can be heated according to the invention, without the customer would require too much effort and without the aforementioned misconduct of the customer would have serious consequences.

Because if there is overheating on a heating conductor, which only has to provide a small proportion of power in relation to the total output, this heating conductor burns through, whereas the other heating conductors continue to function normally. With a sufficiently large number of heating conductors then heating of the fluid is possible almost over the entire circumference. To ensure this, a certain distance must be provided between the individual heating conductors, so that a resulting arc does not damage the adjacent heating conductors. Preferably, this transverse distance between the individual heating conductors is in the range between 0.4 and 5 millimeters. The distance is smaller than the transverse extent of a respective heat conductor.

If the fluid can be heated via a heating pump, a high degree of integration with a minimization of installation space and number of components is achieved.

In particular, the channel is surrounded by a circumferentially closed pipe section. Outside of this piece of pipe, the plurality of heating conductors is applied. On this pipe piece can be applied outside for a high efficiency of heat transfer to the flowing fluid in the pipe section in particular a thick film heater.

Conveniently, the heater, in particular thick film heater, formed with a plurality of parallel interconnected heating conductors that form Einzelheizwiderstände. Their respective width, perpendicular to the flow direction of the fluid, also plays a role for them this determines the number of parallel-connected Einzelheizwiderstände that can be distributed on the circumference of the heating tube determined. The optimum range for the width of this Einzelheizleiters is between 1 millimeter and 30 millimeters, preferably between 2 millimeters and 15 millimeters, so as to show on the one hand a suitable electrical resistance and on the other hand to be able to distribute as many individual heating conductors over the circumference. In this case, the heating conductors each have a relation to their width extension considerable longitudinal extent.

In particular, for a large heat introduction into the fluid at least 85% of the circumference of the heating tube, and in particular substantially along its entire longitudinal extent occupied by heating elements. Thus, a large area performance, ie a high heat input into the channel section, can be ensured. As area performance here the heat output per area is considered, which is introduced into a wall region surrounding the channel section.

Also, individual heating conductors can be up to 70 millimeters wide. In addition, the heating conductors can also have different widths.

Preferably, the pipe section or the pipe section extends substantially longitudinally, in particular substantially in a straight line. The fluid flows through this pipe section with a directional component substantially along the longitudinal extent of this pipe section.

In particular, the respective heating conductor extends from the input region to the output region of the pipe section.

The heating conductors are arranged substantially in the flow direction of the fluid for the above-mentioned reasons. This does not mean that they have to be completely parallel to the flow direction. Rather, the extension of the heating element can be at an acute angle a between 0.1 ° and 30 ° with respect to the flow direction of the fluid, in particular at an angle between 5 ° and 20 °. As a result of this slight inclination, in a screen printing process for applying the heating conductors, a doctor used in the circumferential direction can be pulled over the heating conductors without the doctor being pressed into a depression between the heating conductors and starting to oscillate. The division into several individual heating resistors also divides the electrical power. Should a particular resistor burn out due to overload, the total power of the heating element is reduced by the heating power of this single heating resistor. It is therefore advantageous if a single heating resistor has only the lowest possible power component, so that the total power loss is as low as possible when a heating resistor blows.

Running in the circumferential direction of the channel section, preferably two electrical conductor tracks are provided on the outside for providing two electrical potentials at both ends of the respective heating conductor. In each case, the heating conductors extend between these two interconnects or their potentials. Preferably, the first electrical conductor for the first electrical potential in the direction of flow of the fluid as viewed at the beginning of the pipe section and the second electrical conductor for the second electrical potential is provided in the flow direction of the fluid approximately at the end of the pipe section. The heating conductors are thus electrically connected in parallel with each other.

Therefore, it is advantageous if the number of Einzelheizwiderstände is as large as possible. For this reason, 5 to 100 heating conductors, in particular 10 to 60 heating conductors, particularly advantageously 20 to 40 heating conductors, are distributed over the circumference of the channel in a very advantageous manner.

Other developments of the invention are given in the dependent claims.

The above-explained and / or reproduced in the subclaims advantageous embodiments and refinements of the invention can - in addition to z. B. in cases of clear dependencies or incompatible alternatives - individually or in any combination with each other.

The invention and its advantageous embodiments and further developments and their advantages will be explained in more detail with reference to exemplary embodiments illustrative drawings. They show, in each case in a schematic outline sketch:

1 is a water-conducting household appliance, here a dishwasher with a front door and a washing container inside, in a schematic perspective view obliquely from the front,

2 is a detail view of a arranged in the base of the household appliance heating pump for combined fluid delivery and heating,

3 shows the heating pump of Figure 2 in an exploded view of their parts,

4 shows the heatable pipe section in a schematic single part illustration,

5 is a perspective view of the heatable pipe section,

6 is a view similar to Figure 5, wherein the view is rotated relative to Figure 5 in the circumferential direction of the pipe section,

7 shows two only schematic views of the heating element which is "unwound" as a model of thought from the circumference of the tube section,

The water-conducting household appliance 1 shown schematically in FIG. 1 here is a dishwashing machine, namely a domestic dishwasher. Also, a washing machine or other device in which a fluid is heated, such. a coffee maker come into consideration.

In the figures 1-7 corresponding parts are provided with the same reference numerals. Only those components of a domestic dishwasher are provided with reference numerals and explained which are necessary for the understanding of the invention. It goes without saying that the dishwasher according to the invention can comprise further parts and assemblies. The domestic dishwasher shown here has, as part of a partially open to the outside or closed device body 5 a washing container 2 for receiving ware to be processed dishes such as dishes, pots, cutlery, glasses, cooking utensils u. on. The items to be washed can, for example, be loaded in loading units 10, 11, namely according to the drawing in dish racks 11 and / or a cutlery drawer 10, and can be acted upon by so-called rinsing liquor. Here, by way of example, two baskets 1 1 one above the other and in the upper region of the washing container 2, an additional cutlery drawer 10 is arranged. This arrangement is not mandatory. The loading units 10, 11 can be designed, for example, manually or by motor and automatically height-adjustable or without height adjustment. In Figure 1, the loading units 10, 11 are shown partially pulled out to the front side V of the dishwasher, which faces the user in the installed position.

The rinsing container 2 may have an at least substantially rectangular floor plan with a front side V facing a user in the operating position. This front V can form a part of a kitchen front of kitchen furniture standing side by side or even be without reference to other furniture in a stand-alone device.

The washing container 2 can be closed by a door or flap 3, in particular on this front side V. Thus, the washing container 2 can be opened for its loading and unloading or closed for the flushing operation via this door 3. The front door 3 is here by way of example in the direction 4 pivotally, which is not mandatory. In Figure 1, it is shown in partially open and then inclined to the vertical position. In its closed position, however, it stands upright and is according to the drawing to its opening about a lower horizontal axis about a door hinge axis 13 to the front and down in the direction of arrow 4 swung open, so that it is at least almost horizontal in the fully open position.

At its vertical in the closed position, the user facing the outside door 3 may be provided with a decorative plate 6, so as to experience a visual and / or haptic appreciation and / or adaptation to surrounding kitchen furniture. The dishwasher is designed here as a stand-alone or as a so-called. Partially integrated or as a fully integrated device. In the latter case, the device body 5 can also be substantially complete with the outer walls of the washing compartment 2. A surrounding this exterior housing can then be partially or completely omitted or unnecessary in particular in the area of the side walls, rear wall, and / or ceiling wall of the washing. In the lower area of the dishwasher, a base 12 for receiving in particular functional elements, such as a circulating pump for rinsing liquor, are located. This circulating pump can also be heated, in particular, so as to bring the rinsing liquor to the desired temperature in the respective program step. Then, a combined heat pump 17 is formed.

The movable door 3 is assigned in the embodiment according to the drawing in its upper part a transverse direction Q of the dishwasher extending control panel 8, which may include an accessible from the front V engagement opening 7 for manually opening and / or closing the door 3. So this is preferably a so-called semi-integrated device. In the transverse direction Q, the dishwasher often has an extension of 45, 50 or 60 centimeters. In the depth direction T from the front V to the rear, the extension is often also about 60 centimeters. The values are not mandatory. The dishwasher can stand on an outer bottom B, which is ideally at least almost horizontal.

The dishwasher or the other domestic appliance 1 has at least one channel section 14 which can be heated from the outside and can flow through the fluid 15. As fluid 15 preferably water comes into consideration, which may be added, for example, with detergent, rinse aid and / or a desiccant, for example. Such a fluid is often referred to as a rinse. For heating the fluid 15, a plurality of electrically interconnected heating conductors 16 are provided, which are applied to a carrier, for example a pipe section 18. This pipe section 18 may, for example, have a round-symmetrical cross-section and here form part of the heating pump 17, such as a diffuser space. However, this is not mandatory, but increases the integration and reduces the space requirement and the number of components required. The application of the heating conductors 16 can be done, for example, by a printing process, a plasma coating or another method for forming layers. These layers each form a heating conductor 16. These heating conductors are thus present in a plurality and at least partially electrically connected in parallel to one another and in each case arranged with a component in the direction of flow F of the fluid 15. Here, over the circumference of the pipe section 18, two different electrical potentials are formed, between which the heating conductors 16 are extended.

The heating conductors 16 are present in a plurality and at least partially electrically connected in parallel to one another and in each case arranged with a component in the direction of flow F of the fluid 15. Here, over the circumference of the pipe section 18, two different electrical potentials are formed, between which the heating conductors 16 are extended. Running in the circumferential direction of the channel section, preferably two electrical conductor tracks are provided on the outside for providing two electrical potentials at both ends of the respective heating conductor. Viewed in the direction of flow of the fluid through the pipe section, the first electrical conductor for the first electrical potential is preferably provided approximately at the beginning of the pipe section and the second electrical conductor for the second electrical potential in the direction of flow of the fluid preferably approximately at the end of the pipe section. In each case, the heating conductors extend between these two interconnects or their potentials. The heating conductors are thus electrically connected in parallel with each other. As a result, in the event of failure of one of the heating conductors 16, the function of the others is not disturbed. In the case of a large number of heating conductors, therefore, even after the failure of one, two or three heating conductors, sufficient functionality is still guaranteed. A thermal overload of a single Heizleiterelements 16 therefore no longer has a total failure of the heater result, but this can continue with only minor performance losses, the household appliance 1 remains functional.

The heating conductor elements 16 surround the channel section 14 over a substantial part of its outer surface and carry in operation, in which they are current-flow, thermal surface power in the channel section 14 a. For this purpose, the pipe section 18 enveloping the duct section 14 is subjected to a thermal load on the outside of the pipe section 18 by the plurality of heating conductor elements 16 interconnected electrically in parallel with one another at their location locations. This causes a Heat input at the respective location of the respective heating element per given heat input surface such as per 1 cm ² in the shell of the pipe section 18 and corresponding thereto in the channel section 14th

Outside on the pipe section 18 is here in particular a thick-film heater 19 is applied with the heating conductors 16, which is formed with the largest possible number of parallel interconnected heating conductors that form Einzelheizwiderstände. These each have a considerable longitudinal extension compared to their width extension b1.

Preferably, the pipe section or the pipe section 18 extends substantially longitudinally, in particular substantially in a straight line. The fluid flows through this pipe section with a directional component substantially along the longitudinal extent of this pipe section. In particular, the respective heating conductor extends on the outside of the pipe section from the input area to the outlet area of the pipe section. As already described in the advantages, the heating conductors 16 are arranged substantially in the direction of flow F of the fluid 15, but are advantageously not exactly parallel to the flow direction F, but at an angle a between 0.1 ° and 30 ° with respect to the flow direction F, in particular at an angle a between 5 ° and 20 °, as can be seen for example Figure 4 to Figure 7.

The drawn in the drawing distance a1 perpendicular to the flow direction F is between the heating conductors 16 between 0.4 and 5 millimeters.

In this case, the distance a1 is smaller than the transverse extent b1 of a respective heating conductor 16 whose transverse extent b1 is between 1 millimeter and 30 millimeters. This transverse extension b1 is here also plotted perpendicular to the flow direction F. It is between two millimeters and 15 millimeters.

Distributed over the circumference of the channel section 14 are preferably 5 to 100 heating conductors 16, in particular 10 to 60 heating conductors 16, in a typical heating pump 17 with a pipe section 18 of less than 10 centimeters in diameter, in particular 20 to 40 heating conductors 16. These can - but do not have to - applied in a uniform distribution be as shown in Figure 6. This results in a particularly uniform liquid heating over the circumference.

Due to the possibility of being able to continue operating the heater 19 as a whole even when individual heating elements 16 are burned through, this results in a quality optimization with regard to the service life. In addition, the robustness of the household appliance 1 - even against the aforementioned operating errors - increased.

The Heizleiterelemente 16 can be applied in particular by a high-impedance paste system, this results in a cost reduction. In addition, there is a reduction in the material weight for the Heizleiterpaste.

LIST OF REFERENCE NUMBERS

1 home appliance,

 2 washing containers,

 3 door,

 4 opening direction,

5 device bodies,

 6 decorative plate,

 7 recessed grip,

 8 control panel,

 10 cutlery drawer,

11 crockery basket,

 12 sockets,

 13 door hinge axis,

14 channel section,

 15 fluid,

 16 heating conductors,

 17 heating pump,

 18 pipe piece,

 19 thick-film heating,

F flow direction, a1 distance,

b1 width extension,

Q transverse direction,

 T depth direction

 B floor

Claims

claims 1. A water-conducting domestic appliance (1) with at least one heatable from the outside and of fluid (15) through-flow channel portion (14), wherein for heating a plurality of electrically interconnected Heizleiterelementen (16) is provided  characterized,  in that at least some of the heating conductor elements (16) are electrically connected in parallel with one another and are arranged with a component in the direction of flow (F) of the fluid (15). 2. Household appliance (1) according to claim 1,  characterized,  in that the domestic appliance (1) comprises a dishwasher, in particular a domestic dishwasher, with a washing container (2) for receiving items to be washed, such as dishes, glasses, cutlery or the like, the items to be washed being heated and with detergent and / or rinse aid and / or or desiccant offset, circulating fluid (15), so-called. Flushing liquor, can be acted upon. 3. Household appliance (1) according to one of claims 1 or 2,  characterized,  the fluid (15) can be heated via a heating pump (17). 4. Household appliance (1) according to one of claims 2 or 3,  characterized,  that the channel (14) is encompassed by a peripherally closed tube piece (18). 5. Household appliance (1) according to claim 4,  characterized, that outside of the pipe section (18) a heater, in particular thick film heater (19) is applied. 6. Household appliance (1) according to one of claims 1 to 5,  characterized,  in that the heater, in particular thick film heater (19), is formed with a multiplicity of heating conductors (16) which are connected in parallel with one another and form the individual heating resistors. 7. Household appliance (1) according to one of claims 1 to 6,  characterized,  in that the heating conductors (16) have a considerable longitudinal extension in relation to their width. 8. Household appliance (1) according to one of claims 1 to 7,  characterized,  in that the heating conductors (16) are arranged substantially in the direction of flow (F) of the fluid (15). 9. Household appliance (1) according to claim 8,  characterized,  the extent of the heating conductors (16) is at an angle (a) between 0.1 ° and 30 ° with respect to the direction of flow (F) of the fluid (15). 10. Household appliance (1) according to claim 9,  characterized,  the extent of the heating conductors (16) is at an angle (a) between 5 ° and 20 ° with respect to the flow direction (F) of the fluid (15). 1 1. Household appliance (1) according to one of claims 7 to 10,  characterized,  the heating conductors (16) have a distance (a1) between 0.4 and 5 millimeters between them. 12. Household appliance (1) according to claim 11, characterized, that the distance is smaller than the transverse extent (b1) of a respective heating conductor (16). 13. Household appliance (1) according to claim 12,  characterized,  that the transverse extent (b1) is between one millimeter and 30 millimeters. 14. Household appliance (1) according to claim 13,  characterized,  that the transverse extent (b1) is between two millimeters and 15 millimeters 15. Household appliance (1) according to one of claims 1 to 14,  characterized,  that over the circumference of the channel (14) distributed 5 to 100 heating conductors (16) are arranged. 16. Household appliance (1) according to claim 15,  characterized,  that distributed over the circumference of the channel (14) 10 to 60 heating conductors (16) are arranged. 17. Household appliance (1) according to claim 16,  characterized,  that distributed over the circumference of the channel (14) 20 to 40 heating conductors (16) are arranged.