Water-bearing household appliance

Abstract

Water-bearing household appliance, in particular dishwasher, with a wash chamber (2) providing a wash chamber (3) for receiving items to be cleaned, a spray device (4) for supplying items to be cleaned with wash liquor and with a heat pump device (10) for heating wash liquor, wherein the heat pump device (10) has a condenser (14) and a collector (21), and wherein the condenser (14) has two tubes (19, 20) which are arranged coaxially to each other leaving an annular gap space (22), wherein the inner tube (20) surrounded by the annular gap space (22) is supplied with cleaning liquor and the annular gap space (22) provided by the outer tube (19) is supplied with refrigerant, characterized by that the condenser (14) and the collector (21) are combined to form a single component and that the annular gap space (22) opens into an additional volume (23) serving as a collector volume.

Description

[0001] The invention relates to a water-bearing household appliance, in particular a dishwasher, with a washing container providing a washing chamber for receiving items to be cleaned, a spray device for supplying items to be cleaned with washing liquor, and a heat pump device for heating washing liquor, wherein the heat pump device has a condenser and a collector.

[0002] Water-using household appliances such as washing machines, household dishwashers, cleaning and / or disinfection machines, and / or the like are well known from the prior art, which is why a separate printed reference is generally not required here. Therefore, reference is made only by way of example to EP 2 682 039 A1, which discloses a household appliance of this type in the form of a dishwasher.

[0003] The dishwasher, previously disclosed in EP 2 682 039 A1, has a wash chamber that provides a wash compartment. This compartment is accessible to the user via a loading opening, which can be sealed fluid-tight by means of a pivotally mounted wash compartment door. In its intended use, the wash chamber serves to hold items to be cleaned, such as dishes, cutlery, and / or the like.

[0004] To spray the items to be cleaned with cleaning fluid, the so-called wash liquor, the dishwasher has a spray system inside the wash tub. This spray system typically provides rotating spray arms, usually two or three of which are provided. Under normal operating conditions, the items to be cleaned are sprayed with the wash liquor by means of rotating spray arms.

[0005] The dishwasher, previously known from EP 2 682 039 A1, further comprises a heat pump unit for heating the dishwashing liquid. This is intended to reduce the dishwasher's energy consumption, particularly during the heating of the dishwashing liquid, as such heating accounts for the largest share of a dishwasher's energy consumption. The heat pump unit comprises, in a manner known per se, an evaporator, a compressor, a condenser, a receiver, an expansion device in the form of a throttle, and a flow circuit connecting these components.

[0006] The heat pump unit of the dishwasher according to EP 2 682 039 A1 is an air-to-water heat pump unit. During operation, the heat pump unit extracts thermal energy from the ambient atmosphere, i.e., the air surrounding the dishwasher, and transfers it to the wash liquor circulating inside the dishwasher. The condenser of the heat pump unit acts as a heat exchanger, transferring thermal energy from a working fluid circulated within the heat pump unit's flow circuit to the wash liquor.

[0007] In normal operation, the heat pump system draws in room air via fans to heat the cleaning solution and passes it over the evaporator. This cools the incoming room air, and the heat energy extracted from the air is transferred to the working fluid, causing it to evaporate in the evaporator. The working fluid, now in gaseous form, is then compressed in the compressor, raising its temperature. Finally, the gaseous working fluid is introduced into the condenser, where it liquefies, releasing energy in the process. The heat energy released during this process is used to heat the cleaning solution.

[0008] DE 24 57 182 A1 describes a dishwasher with a heat pump that extracts heat from the ambient air and transfers it to the water used for washing. The heat pump has a first condenser that heats the tank water and a downstream second condenser that simultaneously acts as a collector and subcooler and is preheated by the rinse water.

[0009] The use of water-to-water heat pump systems is also known from the prior art, for example from EP 2 206 824 A2. In its intended use, such a heat pump system extracts heat energy not from the ambient atmosphere, but from a liquid reservoir. This liquid reservoir can be, for example, a water-filled tank that houses the evaporator of the heat pump system. During operation, the water stored in the tank cools down as a result of the heat energy extraction, and this cooling can even lead to freezing.

[0010] The common feature of previously known designs is that at the beginning of normal operation of the heat pump system, a comparatively large quantity of gaseous working fluid must be reliquefied in the condenser, while less is required at the end of operation. This results in more liquefied working fluid being produced at the end of operation than is subsequently evaporated in the evaporator. Therefore, intermediate storage of the liquefied working fluid is necessary. For this reason, heat pump systems known from the prior art have a receiver that is located downstream of the condenser or upstream of the evaporator. This receiver serves as a buffer storage tank that, when needed, temporarily stores liquefied working fluid from the condenser before it enters the evaporator.

[0011] Although the aforementioned design has proven its worth in everyday practical use, there is room for improvement, particularly with regard to simplified and therefore more cost-effective manufacturing. It is therefore the object of the invention to further develop a generic household appliance in such a way that its design enables simplified manufacturing.

[0012] To solve this problem, the invention proposes a household appliance of the generic type with the features of claim 1.

[0013] According to the prior art, the condenser and the collector of the heat pump unit are designed as separate components, which are fluidically connected to each other via corresponding pipes in the final assembly state. In contrast, the inventive design proposes to structurally combine the condenser and the collector into a single component. This inventive design offers the advantage of simplified handling during manufacturing, since only one component, rather than two, needs to be stocked and installed. In particular, this eliminates the soldering process required for the fluidic connection of the collector and condenser via a corresponding pipe.The combination of condenser and collector according to the invention also has the advantage that the installation space required for the heat pump unit is reduced, thus enabling optimized use of the available installation space. Due to the elimination of previously required soldered joints for the flow-related connection of the condenser and collector, the number of potential leakage points is reduced, which advantageously increases operational reliability.

[0014] According to a further feature of the invention, the one-piece construction of the condenser and receiver is preferably achieved by designing the receiver as an integral part of the condenser. Thus, a condenser known per se from the prior art is extended according to the invention to include the function of a receiver. The result of this design is a condenser that provides an additional volume for the working fluid of the heat pump system, which serves as a buffer storage tank for temporarily storing liquefied working fluid. This additional volume therefore serves as the receiver volume, meaning the receiver is an integral part of the condenser.

[0015] The condenser is designed as a heat exchanger and, according to a further feature of the invention, has two tubes which are arranged coaxially to each other while leaving an annular gap space, wherein the inner tube surrounded by the annular gap space is supplied with flushing liquor and the annular gap space provided by the outer tube is supplied with refrigerant.

[0016] Accordingly, the condenser of the heat pump system is designed as a coaxial heat exchanger. It has a first tube, the so-called rinse water tube, through which the rinse water from the dishwasher's wash chamber is passed under normal operating conditions. A second tube, the so-called refrigerant tube, carries the working fluid of the heat pump system, also known as the refrigerant, under normal operating conditions. The rinse water tube is located inside the refrigerant tube, with the rinse water tube forming the inner tube and the refrigerant tube the outer tube.

[0017] The inner tube has an outer diameter that is smaller than the inner diameter of the outer tube, so that the two tubes are arranged coaxially to each other while leaving an annular gap.

[0018] In its intended use, the coaxial heat exchanger, i.e., the condenser, is subjected to a flow of both cleaning liquor and working fluid, preferably in counterflow. The pipe wall of the inner tube, i.e., the cleaning liquor tube, serves as the interaction surface through which heat exchange takes place between the cleaning liquor and the working fluid.

[0019] The tubes of the coaxial heat exchanger can be straight or, for example, bent into loops. Depending on the embodiment, the effective length of the tubes is between 0.5 m and 3 m, for example 2.20 m, 2.40 m, or the like. With regard to their outer and inner diameters, the two tubes are matched such that the annular gap has a clearance of between 0.15 mm and 1 mm, preferably between 0.3 mm and 0.8 mm, and even more preferably 0.5 mm, depending on the application.

[0020] According to a further feature of the invention, the annular gap space opens into an additional volume serving as a collector volume. Accordingly, an additional volume is provided that is fluidically connected to the annular gap volume by virtue of the latter opening into the additional volume. The working fluid of the heat pump system, which passes through the annular gap space of the condenser during the intended process cycle, thus enters the additional volume after flowing through the annular gap space. In this additional volume, the working fluid can be temporarily stored before being directed to the evaporator, if necessary. In this respect, the additional volume serves as a collector volume.

[0021] According to a further feature of the invention, the additional volume is provided by the outer tube of the coaxial heat exchanger, i.e., the condenser. The invention proposes various design alternatives in this regard.

[0022] According to a first alternative of the invention, the outer tube has a section extending longitudinally with an inner diameter that is larger than the rest of the inner diameter. Accordingly, an outer tube is provided that has a radial bulge. In the area of ​​this radial bulge, an enlarged annular gap is created, thereby generating the additional volume. Depending on the application, the additional or collector volume is between 15 cm³ and [missing information]. 3 and 55 cm 3 , preferably between 25 cm 3 and 45 cm 3 , even more preferred 35 cm 3 large. Accordingly, the inner diameter of the outer tube in the area of ​​radial expansion and / or the length of the radial expansion in the longitudinal direction of the tube must be designed.

[0023] According to a second alternative, the outer tube is provided with a radial bulge extending longitudinally along its length. Preferably, several such radial bulges are provided, ideally arranged evenly distributed around the circumference of the tube. This embodiment proposes an outer tube with a contour that deviates from a circular shape. In the area of ​​the radial bulges, the distance to the inner tube enclosed by the outer tube is increased, thereby creating the additional volume that serves as the collector volume.

[0024] According to a third alternative, the outer pipe is designed to carry a pipe stub that provides the additional volume. This pipe stub interacts with a flow opening provided by the outer pipe, thus ensuring the fluidic connection of the additional volume provided by the pipe stub to the annular gap space.

[0025] According to a further development of the invention, a plurality of pipe stubs of the aforementioned type can be provided, preferably arranged one behind the other in the longitudinal direction of the outer pipe. Each pipe stub provides a portion of the additional volume, so that the sum of all partial volumes creates the additional volume serving as the collector volume.

[0026] According to a further feature of the invention, the pipe stub is radially aligned with the outer pipe. This alignment is particularly preferred for reasons of simplified manufacturing.

[0027] The inventive design proposes an overall construction which, in contrast to the prior art, eliminates the need for an additional component such as the collector, thus improving storage, manufacturing, and operational reliability. In particular, the soldering step is eliminated, minimizing manufacturing costs and reducing the number of potential leak points.

[0028] Furthermore, improved efficiency of the heat exchanger is achieved because the working fluid or refrigerant can be slightly subcooled during normal operation. This subcooling increases the amount of heat that can be transferred to the cleaning solution. Additionally, the subcooling reduces the vapor content in the evaporator inlet area. This advantageously allows for greater heat absorption there as well.

[0029] Different annular gap dimensions can be incorporated along the length of the condenser, which is designed as a coaxial heat exchanger. This allows for section-by-section increases in refrigerant-side heat transfer or reduction in refrigerant-side pressure loss. This leads to higher efficiency of the heat pump system or a reduction in its overall size.

[0030] Furthermore, by reducing the annular gap dimensions in areas with high refrigerant density on the high-pressure side, it is possible to reduce the total required refrigerant charge. Suitable areas for this reduction include the area with liquefied refrigerant directly behind the receiver and the area with refrigerant containing a low vapor content directly in front of the receiver.

[0031] According to one embodiment, the condenser has an annular gap with a first dimension in a section located upstream of the collector or the additional volume in the flow direction of the working fluid, and an annular gap with a second dimension in a section located downstream of the collector or the additional volume in the flow direction of the working fluid. The first dimension and the second dimension are between 0.15 mm and 1 mm. The first dimension and the second dimension can be the same. Preferably, however, the second dimension is different from the first dimension, preferably smaller. The first dimension can, for example, be between 0.4 mm and 1 mm, and the second dimension between 0.15 mm and 0.4 mm, in particular about 0.2 mm.

[0032] According to a further embodiment, the condenser has, in the flow direction of the working fluid, a first section upstream of the collector or the additional volume, with a first annular gap dimension, and a second section arranged between the first section and the collector or the additional volume, with a second annular gap dimension different from the first. The second annular gap dimension is preferably smaller than the first annular gap dimension. The first annular gap dimension can, for example, be between 0.6 mm and 0.8 mm, while the second annular gap dimension can, for example, be between 0.3 mm and 0.5 mm. Furthermore, the condenser can have another section located downstream of the collector or the additional volume in the flow direction of the working fluid, with an annular gap dimension that is even smaller than the second annular gap dimension, preferably between 0.15 mm and 0.4 mm, for example, around 0.2 mm.

[0033] Water-bearing household appliances for which the inventive design can be applied include, in particular, dishwashers, washing machines, washer-dryers and / or similar appliances.

[0034] Further features and advantages of the invention will become apparent from the following description with reference to the figures. These show Fig. 1 in a purely schematic representation a dishwasher designed according to the invention; Fig. 2 in schematic perspective representation a condenser designed according to the invention in a first embodiment; Fig. 3 in schematic side view a condenser designed according to the invention in a second embodiment; Fig. 4 in schematic side view a condenser designed according to the invention in a third embodiment; Fig. 5 in a schematic front view the liquefier Fig. 4; Fig. 6 in schematic perspective view a liquefier according to the invention in a fourth embodiment; Fig. 7 in schematic front view the liquefier Fig. 6; Fig. 8 in schematic side view the liquefier after Fig. 6; Fig. 9 in schematic perspective representation a liquefier according to the invention in a fifth embodiment; Fig. 10 in a schematic front view the liquefier Fig. 9; Fig. 11 in schematic side view the liquefier after Fig. 9; Fig. 12 in schematic perspective view a liquefier according to the invention in a sixth embodiment; Fig. 13 in a schematic side view the liquefier Fig. 12; and Fig. 14 in a purely schematic representation a dishwasher according to the state of the art.

[0035] Fig. Figure 14 shows, in a purely schematic representation, a water-bearing household appliance in the form of a dishwasher 1 known from the prior art.

[0036] The exemplary in Fig. The dishwasher 1 shown in Figure 14 has a wash container 2 which provides a wash chamber 3. In its intended use, the wash chamber 3 serves to hold items to be cleaned and in Fig. 14 items of dishwashing not shown in detail.

[0037] A spray device 4, located inside the wash tank 2, serves to supply the items to be cleaned with the cleaning solution. In the illustrated embodiment, the spray device 4 has a total of three spray arms 5, each rotatably arranged inside the wash tank 2.

[0038] The rinsing chamber 3 leads into a section detailed in Fig. The dishwasher 1 has a collection tank 6 (not shown) of the wash tank 2, to which a circulation pump 7 is fluidically connected. The spray arms 5 of the spray unit 4 are fluidically connected to the circulation pump 7 via the supply lines 9 and the water diverter 8. In normal use, the spray arms 5 can thus be supplied with wash water by means of the circulation pump 7. The dishwasher 1 also has a heat pump unit 10. This unit comprises an evaporator 12, a compressor 13, a condenser 14, a receiver 15, an expansion device in the form of a throttle 16, and a line 18 that fluidically connects these components and through which a working fluid or refrigerant is carried.

[0039] The evaporator 12 is arranged inside a tank 11 which is filled with a heat transfer medium, preferably water.

[0040] In the intended use of the heat pump unit 10, heat is transferred from the working fluid, which flows through line 18 of the heat pump unit 10, to the cleaning solution via the condenser 14. For this purpose, a line 17, connected to the circulation pump 7, is provided for the circulation of the cleaning solution. The heat energy released in the condenser 14 during operation by the condensation of the working fluid is thus transferred to the cleaning solution circulated through line 17.

[0041] According to the preferred embodiment shown in the figures, the condenser 14 is designed as a coaxial heat exchanger and has two tubes arranged coaxially to each other, leaving an annular gap. The inner tube serves as the purge tube and is connected to line 17. The outer tube surrounding the inner tube serves as the refrigerant tube and is connected to line 18 of the heat pump unit 10. In normal operation, the working fluid flows through the annular gap, and the purge fluid flows through the inner tube.

[0042] A collector 15 is connected downstream of the condenser 14 in terms of flow direction. This collector 15 provides a buffer volume that serves to temporarily store the working fluid liquefied in the condenser 14 before it passes through the throttle 16 to the evaporator 12 for re-evaporation in the further course of the process cycle.

[0043] In contrast to the two-part design of condenser 14 and collector 15, the invention proposes that the condenser 14 and the collector 15 be combined into a single component. This design according to the invention is in Fig. 1 shown.

[0044] Fig. Figure 1 shows a dishwasher 1 designed according to the invention, which, in contrast to a dishwasher 1 according to the prior art, Fig. 14 has a liquefier 14 which has a collector 21 as an integral component.

[0045] The combined design of condenser 14 and collector 21 into a single component offers the particular advantage of simplified manufacturing due to easier handling, thus reducing costs. Furthermore, according to current technology, it eliminates the need for solder joints for the flow-related connection between condenser 14 and collector 15, thereby minimizing potential leakage points and maximizing operational reliability.

[0046] The condenser 14 designed according to the invention is described in different embodiments in the following Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12 to Fig. 13 shown.

[0047] As can be seen, for example, from the presentation according Fig. As shown in Figure 2, the condenser 14 is designed as a coaxial heat exchanger and has two tubes: an inner tube 20 and an outer tube 19. The two tubes 19 and 20 are arranged coaxially relative to each other, leaving an annular gap 22. In its intended use, the inner tube 20 serves to convey cleaning liquor, while the outer tube 19, which houses the inner tube 20, serves to convey a refrigerant in counterflow to the cleaning liquor, as shown in Figure 2. Fig. The three arrows 25 and 26 shown indicate the direction of flow. Arrow 26 represents the flow direction for the refrigerant, and arrow 25 represents the flow direction for the cleaning solution.

[0048] For the purpose of integral design of the collector 21, the condenser 14 provides an additional volume 23 which opens into the annular gap space 22, as can be seen from a first embodiment, for example, from Fig. 2. In the illustrated embodiment, the additional volume 23 is formed by a section 28 of the outer tube 19 extending in the longitudinal direction 27 of the tube, which has an inner diameter that is larger than the rest of the inner diameter. The outer tube 19 thus has a radial expansion in the region of section 28, thereby creating the additional volume 23 that serves as a collector volume.

[0049] Fig. 3 shows one to Fig. 2. Similar embodiment. Here, a standing arrangement of the condenser 14 is shown, so that in the intended operating case, liquefied working medium accumulates in the additional volume 23 according to the level 24.

[0050] Furthermore, according to the embodiment, Fig. Three consecutive pipe sections with different dimensions for the annular gap 22 are provided in the longitudinal direction of the pipe. For example, a first section I with an annular gap of, for example, 0.8 mm, a second section II with an annular gap of, for example, 0.4 mm, and a third section III with an annular gap of, for example, 0.2 mm are provided. These different annular gaps serve in particular to optimize the total required refrigerant charge, taking into account the fact that smaller annular gaps may be provided for areas where the refrigerant has a higher density. The refrigerant has the highest density in section III, in particular, because it is already liquefied in the flow direction 25 here.

[0051] The collector volume provided by the collector 21, i.e., the additional volume 23 of the outer pipe 19, serves to compensate for different operating conditions of the heat pump unit 10. This is because, under normal operating conditions, the refrigerant levels in the evaporator often vary considerably, and the collector 21 prevents a backflow of liquefied refrigerant into the condenser, which could otherwise lead to a sharp increase in high pressure and potentially to a fault shutdown.

[0052] An alternative embodiment of the liquefied liquid according to the invention is shown in the Fig. 4 and Fig. 5. In contrast to the embodiments already described, this embodiment provides a longer section 28 in the longitudinal direction 27 of the tube. Due to the longer design of section 28, the inner diameter of the outer tube 19 in the region of section 28 can be smaller than in the embodiments described above, provided the additional volume 23 is identical.

[0053] Another embodiment of the inventive design is the Fig. 6, Fig. 7 to Fig. 8. According to this embodiment, the outer tube 19 has radial bulges 29 extending in the longitudinal direction 27 of the tube. Two radial bulges 29 are provided, as can be seen in particular from the illustration according to Fig. This results in 7. The radial bulges are 29, which can also be seen from the representation according to Fig. 7 results in an even distribution of the dimensions along the circumference of the outer tube 19. As a result of this design, the outer tube 19 has an outer dimension that deviates from a circular shape.

[0054] Another embodiment is the Fig. 9, Fig. 10 to Fig. 11. According to this embodiment, a pipe stub 30 provided by the outer pipe 19 is provided, which supplies the additional volume 23 serving as a collector volume. As can be seen from a summary of the Fig. 9, Fig. 10 to Fig. 11 results in the pipe stub being preferably aligned radially to the outer pipe 19.

[0055] In addition to the Fig. 9, Fig. 10 to Fig. 11 show the Fig. 12 and Fig. 13 Another embodiment in which a plurality of pipe stubs 30 are provided. These pipe stubs 30 are arranged one behind the other in the longitudinal direction 27 of the pipe, preferably at equidistant intervals, as can be seen in particular from the illustration according to Fig. 13 results. Reference sign 1 dishwasher 2 washing containers 3. Dishwashing area 4 Spray device 5 spray arms 6 Collection pot 7 Circulation pump 8 Water diverter 9 Supply line 10 Heat pump system 11 Tank 12 evaporators 13 compressors 14 liquefiers 15 collectors 16 Throttle 17 Management 18 Management 19 Outer pipe 20 inner tube 21 collectors 22 annular gap 23 additional volumes 24 Water level 25 Arrow 26 Arrow 27 Pipe longitudinal direction Section 28 29 Radial bulge 30 pipe fittings

Claims

[1] Water-carrying household appliance, in particular dishwasher, with a washing container (2) providing a washing chamber (3) for receiving items to be cleaned, a spray device (4) for supplying items to be cleaned with washing liquor and with a heat pump device (10) for heating washing liquor, wherein the heat pump device (10) has a condenser (14) and a collector (21), and wherein the condenser (14) has two tubes (19, 20) which are arranged coaxially to each other leaving an annular gap space (22), wherein the inner tube (20) surrounded by the annular gap space (22) is supplied with cleaning liquor and the annular gap space (22) provided by the outer tube (19) is supplied with refrigerant, characterized by , that the condenser (14) and the collector (21) are combined to form a single component and that the annular gap space (22) opens into an additional volume (23) serving as a collector volume. [2] Device according to claim 1, characterized by , that the collector (21) is formed as an integral part of the liquefier (14). [3] Device according to claim 1 or 2, characterized by , that the additional volume (23) is provided by the outer tube (19). [4] Device according to any one of claims 1 to 3, characterized by , that the outer tube (19) has a section (28) extending in the longitudinal direction (27) of the tube with an inner diameter that is larger than the rest of the inner diameter. [5] Device according to any one of claims 1 to 3, characterized by , that the outer tube (19) is provided with a radial bulge (29) extending in the longitudinal direction (27) of the tube. [6] Device according to claim 5, characterized by, that the outer tube (19) has a plurality of radial protrusions (29) extending in the longitudinal direction (27) of the tube, which are arranged equally distributed in the circumferential direction of the outer tube (19). [7] Device according to any one of claims 1 to 3, characterized by , that the outer pipe (19) carries a pipe nozzle (30) providing the additional volume (23). [8] Device according to claim 7, characterized by that the pipe stub (30) is radially aligned to the outer pipe (19). [9] Device according to any one of claims 1 to 8, characterized by , that the condenser (14) has an annular gap space (22) with a first dimension in a section (I, II) located in the flow direction of the working medium upstream of the additional volume (23) and an annular gap space (22) with a second dimension, which is in particular different from the first dimension and preferably smaller, in a section (III) located downstream of the additional volume (23). [10] Device according to any one of claims 1 to 9, characterized by , that the condenser (14) has, in the direction of flow of the working fluid, a first section (I) with a first annular gap dimension and a second section (II) arranged between the first section (I) and the additional volume (23) with a second annular gap dimension different from the first, preferably smaller.

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