DISHWASHING MACHINE WITH HEAT PUMP DEVICE AND INTERMEDIATE CIRCUIT

Abstract

Dishwasher (2), comprising: a refrigeration circuit (6) comprising a refrigeration circuit hollow body (12) for receiving a refrigerant (16) and a compressor (8) for compressing the refrigerant (16) and for conveying the refrigerant (16) through the refrigeration circuit hollow body (12); an intermediate circuit (17) comprising an intermediate circuit hollow body (19) for receiving an intermediate fluid (18) and an intermediate circuit pump (22) for conveying the intermediate fluid (18) through the intermediate circuit hollow body (19); and a lye circuit (25) comprising a lye circuit hollow body (28) for receiving a rinsing liquid (24) and a lye circuit pump (27) for conveying the rinsing liquid (24) through the lye circuit hollow body (28); wherein the refrigeration circuit (6) comprises a condenser (9) configured to transfer heat from the refrigerant (16) to the intermediate fluid (18); wherein the dishwasher (2) comprises a coaxial heat exchanger (23) configured to transfer heat from the intermediate fluid (18) to the rinsing liquid (24), wherein the coaxial heat exchanger (23) comprises an outer hollow body (54) and an inner hollow body (55) arranged within the outer hollow body (54), wherein the inner hollow body (55) is configured to receive the rinsing liquid (24), wherein a cavity (59) between the outer hollow body (54) and the inner hollow body (55) is configured to receive the intermediate fluid (18); wherein the dishwasher (2) comprises a connecting unit configured to connect the intermediate circuit hollow body (19) to the outer hollow body (54) and to connect the liquor circuit hollow body (28) to the inner hollow body (55); wherein the connecting unit comprises a hollow body connecting part (56) with a first connecting section (56a), a second connecting section (56b) and a third connecting section (56c) as well as a first grommet (78), a second grommet (61) and a third grommet (57); wherein the first grommet (78) is configured to connect the first connecting portion (56a) to the intermediate circuit hollow body (19); wherein the second grommet (61) is configured to connect the second connecting portion (56b) to the lye circuit hollow body (28) and is configured to connect the second connecting portion (56b) to the inner hollow body (55), wherein the second grommet (61) comprises a receiving portion (62) for receiving the inner hollow body (55); and wherein the third grommet (57, 57a, 57b) is configured to connect the third connecting portion (56c) to the outer hollow body (54).

Description

[0001] The present invention relates to a dishwasher with a heat pump device and an intermediate circuit.

[0002] Such a dishwasher is known, for example, from DE 10 2013 111 670 B3. The dishwasher described therein is a programmable automatic dishwasher comprising a refrigerant circuit with an evaporator and a condenser, as well as a heat exchanger. The evaporator extracts energy from the machine's exhaust air and / or the ambient air and cools this air. The condenser heats fresh water, which, on the one hand, serves as the rinse water and, on the other hand, heats the rinse tank water via the heat exchanger.

[0003] DE 10 2013 111 670 B3 describes a method for washing dishes in a programmable automatic dishwasher and a programmable automatic dishwasher for washing dishes, in particular for carrying out such a method in which a heat pump is operated continuously over several washing processes and at least one interruption period between each two washing processes for manually inserting the dishes into the washing zone or for removing the dishes from the washing zone.

[0004] DE 10 2014 217 503 A1 describes a dishwasher for washing dishes, wherein the dishwasher has a liquid transport line with at least one supply line for supplying liquid at a first temperature and with at least one discharge line for discharging liquid at a second temperature, wherein the supply line and the discharge line run coaxially to one another, so that either the supply line or the discharge line forms an internal line which runs in the direction of extension of the liquid transport line within the respective other of the supply line or discharge line, which in turn forms an external line, and thus forms a counterflow heat exchanger.

[0005] CN 2 01 697 502 U describes a main body component for a heat exchanger and an electric heater formed by bonding or thermally fusing a straight plastic pipe, a three-way plastic pipe fitting and a four-way plastic pipe fitting.

[0006] It is an object of the present invention to provide a dishwasher with a heat pump device to improve efficiency and user-friendliness taking into account the desired applications and to reduce costs.

[0007] The above object is achieved by a dishwasher according to claim 1. Claims 2 to 15 relate to particularly advantageous implementations of the dishwasher according to claim 1.

[0008] A dishwasher according to the invention can, for example, be a conveyor dishwasher or a pass-through dishwasher and can be used in particular for commercial purposes.

[0009] The dishwasher comprises a refrigeration circuit comprising a refrigeration circuit hollow body, in particular a pipe or hose, for receiving a refrigerant, and a compressor for compressing the refrigerant and for conveying the refrigerant through the refrigeration circuit hollow body. The dishwasher further comprises an intermediate circuit comprising an intermediate circuit hollow body, in particular a pipe or hose, for receiving an intermediate fluid, and an intermediate circuit pump for conveying the intermediate fluid through the intermediate circuit hollow body; the intermediate circuit can, in particular, be a closed circuit or contain a closed circuit. The intermediate fluid can, in particular, be water or contain water.The dishwasher further comprises a lye circuit comprising a lye circuit hollow body for receiving rinsing liquid, lye liquid or rinsing tank water for a rinsing process and a lye circuit pump or rinsing tank circulation pump for conveying the rinsing liquid, lye liquid or rinsing tank water through the lye circuit hollow body.

[0010] The refrigeration cycle further includes a condenser or heat exchanger configured to transfer heat from the refrigerant to the intermediate fluid. The condenser can extract heat from the refrigerant and transfer the extracted heat to the intermediate fluid. The condenser can be part of the refrigeration cycle and / or the intermediate circuit.

[0011] The dishwasher further comprises a coaxial heat exchanger configured to transfer heat from the intermediate fluid to the rinsing liquid. The coaxial heat exchanger can extract heat from the intermediate fluid and transfer the extracted heat to the rinsing liquid. The coaxial heat exchanger comprises an outer hollow body, in particular a hose, and an inner hollow body, in particular a corrugated pipe, arranged within the outer hollow body. Preferably, the inner hollow body and the outer hollow body run parallel to one another. Preferably, cross sections of the inner hollow body and the outer hollow body, which are, for example, circular, are arranged concentrically. The inner hollow body is configured to receive the rinsing liquid, and a cavity or annular gap between the outer hollow body and the inner hollow body is configured to receive the intermediate fluid and to transfer the heat from the intermediate fluid to the rinsing liquid.In particular, the flushing fluid in the inner hollow body can flow countercurrently to the intermediate fluid in the cavity. Conversely, however, the inner hollow body can also be configured to contain the intermediate fluid, and the cavity can also be configured to contain the flushing fluid. The coaxial heat exchanger can be part of the intermediate circuit and / or the liquor circuit.

[0012] The dishwasher or coaxial heat exchanger further comprises a connecting unit configured to connect the intermediate circuit hollow body to the outer hollow body and to connect the liquor circuit hollow body to the inner hollow body. The connecting unit comprises a hollow body connecting part or T-piece with a first connecting section, a second connecting section, and a third connecting section, as well as a first nozzle, a second nozzle, and a third nozzle. Each of the first, second, and third nozzles can, in particular, be a hose nozzle or a pipe nozzle.

[0013] The first grommet is configured to connect, in particular to fasten or seal, the first connecting section to the intermediate circuit hollow body. Sealed here means in particular that the intermediate fluid circulating through the intermediate circuit hollow body and the outer hollow body cannot escape or leak through the connection between the intermediate circuit hollow body and the first connecting section. In particular, a first end section of the first grommet can be inserted into the first connecting section and pressed together therewith, for example by an O-ring located between the first grommet and the first connecting section, and the intermediate circuit hollow body can be inserted onto a second end section of the first grommet, wherein the second end section of the first grommet is arranged opposite the first end section of the first grommet.A hose clamp arranged around the intermediate circuit hollow body can also be used for connection. An O-ring is an annular sealing element, preferably with a round or O-shaped cross-section.

[0014] The second grommet is configured to connect, in particular to fasten or tightly fasten, the second connecting section to the lye circuit hollow body. "Tight" here means in particular that the rinsing liquid circulating through the lye circuit hollow body and the inner hollow body cannot escape or leak through the connection between the lye circuit hollow body and the second connecting section. In particular, a central section of the second grommet can be inserted into the second connecting section and pressed thereto, in particular by an O-ring located between the second grommet and the second connecting section, and the lye circuit hollow body can be inserted onto a first end section of the second grommet. Furthermore, a hose clamp arranged around the lye circuit hollow body can be used for the connection.

[0015] The second spout is also configured to connect, in particular to fasten or tightly fasten, the second connecting portion to the inner hollow body, wherein the second spout comprises a receiving portion for receiving the inner hollow body. Here, "tight" means in particular that neither the rinsing liquid nor the intermediate fluid can escape or leak through the connection between the inner hollow body and the second connecting portion. In particular, a central portion of the second spout can be inserted into the second connecting portion and pressed together therewith, as described above, and the inner hollow body can be inserted into the receiving portion up to a stop and pressed together therewith, as described in more detail below. The receiving portion can be a second end portion of the second spout, which is arranged opposite the first end portion of the second spout.The receiving portion can be formed as a portion of the second grommet with an inner diameter that is larger than an outer diameter of the inner hollow body, so that the inner hollow body can be inserted into the receiving portion and thereby received by the receiving portion. The stop can be formed as a portion of the second grommet with an inner diameter that is smaller than the outer diameter of the inner hollow body in order to limit insertion of the inner hollow body into the receiving portion.

[0016] The third nozzle is configured for connecting, in particular for fastening or sealing, the third connecting section to the outer hollow body. Sealed here means in particular that the rinsing liquid cannot escape or leak through the connection between the outer hollow body and the third connecting section. In particular, a first end section of the third nozzle can be inserted into the third connecting section and pressed against it, in particular by an O-ring located between the third nozzle and the third connecting section, and the outer hollow body can be inserted onto a second end section of the third nozzle, wherein the second end section of the third nozzle is arranged opposite the first end section of the third nozzle. A hose clamp arranged around the outer hollow body can also be used for the connection.

[0017] Since the first grommet connects the first connecting section to the intermediate circuit hollow body, and the third grommet connects the third connecting section to the outer hollow body, the hollow body connecting part, the first and third grommets together connect the intermediate circuit hollow body to the outer hollow body. Since the second grommet connects the second connecting section to the lye circuit hollow body, and the second connecting section to the inner hollow body, the hollow body connecting part and the second grommet connect the lye circuit hollow body to the inner hollow body.

[0018] The dishwashing liquid to be heated by the refrigeration circuit can be mixed with or contaminated with dishwashing chemicals and dirt particles, which are detached from the dishes to be cleaned, for example, during a dishwashing process. For this reason, the dishwashing liquid should not come into direct contact with the heat exchangers, in particular the condenser, of the refrigeration circuit, as this could otherwise become blocked or chemically attacked, thus damaging the dishwasher or reducing its efficiency. For this reason, the thermal energy provided by the refrigeration circuit via the condenser is first transferred to an intermediate fluid, which is then pumped to the coaxial heat exchanger, which forms a system separation between the intermediate circuit and the lye circuit. This prevents aggressive dishwashing liquid from entering the intermediate circuit. Furthermore, the intermediate circuit has the advantage that the entire heat pump, for example,In the event of a fault, it can be removed and reinstalled without interfering with the refrigeration circuit, as will be described in more detail later.

[0019] The connecting unit enables a particularly stable and tight connection between the intermediate circuit hollow body and the outer hollow body, and between the lye circuit hollow body and the inner hollow body, thereby achieving a secure system separation between the intermediate fluid and the rinsing fluid. The intermediate fluid flowing through the intermediate circuit hollow body and outer hollow body thus does not come into contact with the rinsing fluid flowing through the lye circuit hollow body and inner hollow body.

[0020] Furthermore, the second spout serves a dual function, connecting both the second connecting section to the liquor circuit hollow body and the second connecting section to the inner hollow body. Thus, a single spout can securely and tightly connect the liquor circuit hollow body to the inner hollow body, resulting in a particularly compact and cost-effective connecting unit and thus a particularly compact and cost-effective dishwasher.

[0021] Thus, the features of the dishwasher according to the invention increase the efficiency and user-friendliness of the dishwasher and reduce its costs.

[0022] In a preferred embodiment, the hollow body connecting part is T-shaped, wherein the second connecting section and the third connecting section are arranged parallel or substantially parallel and the first connecting section is arranged perpendicular or substantially perpendicular to the second connecting section and the third connecting section.

[0023] This results in a particularly compact, stable and easy-to-manufacture and therefore cost-effective connecting unit or dishwasher.

[0024] In a further preferred embodiment, the inner hollow body is designed as a corrugated pipe with one or more corrugations. The corrugated pipe is a pipe with a corrugated diameter that varies in a corrugated manner, i.e., one whose diameter alternates between smaller and larger in the direction of extension of the pipe. The receiving section of the second grommet is pressed onto the corrugated pipe via one or more O-rings, preferably one, two, three, four, or five O-rings, each of which is arranged in a corresponding corrugation of the corrugated pipe. An O-ring is an annular sealing element, preferably with a round or O-shaped cross-section.

[0025] This creates a particularly stable, secure, and tight connection between the second connecting section and the inner hollow body by means of the second spout, so that neither the rinsing liquid nor the intermediate fluid can escape or leak through the connection between the inner hollow body and the second connecting section. In particular, when the receiving section is pressed onto the corrugated pipe, the one or more O-rings can be deformed such that they completely fill the corresponding corrugations, thereby creating a tight connection with the receiving section. By using multiple O-rings, in particular three O-rings, the connection between the second connecting section and the inner hollow body is sealed particularly securely. Furthermore, O-rings can be produced and obtained inexpensively, thus reducing the cost of the dishwasher.

[0026] In a further preferred embodiment, the receiving portion has a projection that positively engages a corrugation of the corrugated pipe. For example, the receiving portion can be pressed onto the corrugated pipe via three O-rings, each arranged in a first, second, or third corrugation of the corrugated pipe, and the projection can positively engage a fourth corrugation of the corrugated pipe.

[0027] This ensures that the corrugated pipe cannot be pulled out of the receiving section, even under tensile load. This ensures a particularly stable, secure, and tight connection between the second connecting section and the corrugated pipe.

[0028] In a further preferred embodiment, an inner diameter of the second grommet decreases from the central portion toward the receiving portion. Preferably, the inner diameter decreases continuously from the central portion toward the receiving portion.

[0029] This reduces the pressure loss of the washing liquid flowing from the hollow body of the lye circuit into the hollow body of the inner body. This prevents damage to the connection unit or the dishwasher, or a reduction in its efficiency due to excessive pressure loss of the washing liquid.

[0030] In a further preferred embodiment, the connecting unit is configured to connect the intermediate circuit hollow body to a starting portion of the outer hollow body and to connect the liquor circuit hollow body to a starting portion of the inner hollow body, and the dishwasher comprises a further connecting unit configured to connect the intermediate circuit hollow body to an end portion of the outer hollow body and to connect the liquor circuit hollow body to an end portion of the inner hollow body.

[0031] Thus, the above-described advantages of the connecting unit according to the invention are achieved both at the initial section of the coaxial heat exchanger (e.g., the inlet side of the washing liquid) and at the end section of the coaxial heat exchanger (e.g., the outlet side of the washing liquid). Thus, the efficiency and user-friendliness of the dishwasher are further improved and its costs reduced.

[0032] In a further preferred embodiment, the intermediate circuit comprises a reservoir or equalization tank for receiving the intermediate fluid, wherein the reservoir is arranged upstream of the intermediate circuit pump with respect to a flow direction of the intermediate fluid. Upstream can mean, in particular, that the intermediate fluid flows through the intermediate circuit by first flowing through the reservoir, then through the intermediate circuit pump, then through other components of the intermediate circuit such as the condenser and the coaxial heat exchanger, and then again through the reservoir. In particular, the intermediate fluid can flow directly from the reservoir to the intermediate circuit pump without passing through other components of the intermediate circuit as described above.The dishwasher may further comprise an overflow hose connecting the storage container to a machine interior so that air or excess intermediate fluid can flow through the overflow hose from the storage container into the machine interior.

[0033] This prevents or minimizes the risk of cavitation in the intermediate circuit pump and makes certain losses of the intermediate fluid tolerable, e.g. as a result of minor leakage or due to a small amount of intermediate fluid flowing out via the overflow hose, without the intermediate circuit pump sucking in air and the volume flow in the intermediate circuit coming to a standstill.

[0034] Particularly preferably, the intermediate circuit hollow body comprises an inflow section which is arranged upstream of the storage container with respect to a flow direction of the intermediate fluid and is connected to the storage container such that the intermediate fluid can flow into the storage container through the inflow section, wherein a cross-sectional area of ​​the storage container perpendicular to a flow direction of the intermediate fluid through the storage container is larger than a cross-sectional area of ​​the inflow section perpendicular to a flow direction of the intermediate fluid through the inflow section. The flow direction of the intermediate fluid through the storage container can in particular run parallel to the earth's magnetic field when the dishwasher is in an operating state. The flow direction of the intermediate fluid through the inflow section can be parallel to the earth's magnetic field and / or parallel orto the flow direction of the intermediate fluid through the storage tank when the dishwasher is in the operating state. Furthermore, the dishwasher can comprise a heat pump device, wherein the heat pump device comprises the refrigeration circuit and a heat pump housing in which the refrigeration circuit is arranged, and the storage tank can be arranged within the heat pump housing, in particular at a highest point of the heat pump housing in the positive z-direction (when the earth's magnetic field points in the negative z-direction) or at a higher point in the positive z-direction than other components of the refrigeration circuit such as the compressor, the condenser, an evaporator and / or an expansion valve.

[0035] This enables particularly efficient venting of the intermediate circuit, as the intermediate fluid flowing into the reservoir through the inlet section of the intermediate circuit hollow body flows more slowly due to the expanded cross-section in the reservoir, allowing gas / air bubbles contained in the intermediate fluid to rise more easily in the reservoir (in the positive z-direction, i.e., the direction opposite to the Earth's magnetic field). Separating gas / air bubbles can then be vented into the machine interior, for example, via the overflow hose.

[0036] In a further preferred embodiment, the dishwasher or the liquor circuit comprises a tank or wash tank. The liquor circuit pump is configured to pump wash liquid from the wash tank to the coaxial heat exchanger and from the coaxial heat exchanger into the wash tank. The dishwasher is further configured to fill the wash tank with wash liquid, in particular with preheated wash liquid from a boiler, before the start of a wash cycle.The dishwasher is further configured to perform a heating process for heating the washing liquid in the washing tank, the heating process comprising: activating or switching on the compressor and the intermediate circuit pump at a first time to increase a temperature of the intermediate fluid; and activating or switching on the drain circuit pump at a second time after the first time when a difference between the temperature of the intermediate fluid and a temperature of the washing liquid in the washing tank exceeds a predetermined value. By activating the compressor and the intermediate circuit pump at the first time, the refrigerant is pumped through the refrigeration circuit, in particular through the condenser, and the intermediate fluid is pumped through the intermediate circuit, in particular through the condenser and the coaxial heat exchanger.In the condenser, heat is transferred from the refrigerant to the intermediate fluid, so that the temperature of the intermediate fluid is increased. By activating the liquor circuit pump at the second time, the rinsing liquid is then pumped from the tank to the coaxial heat exchanger. In the coaxial heat exchanger, heat is transferred from the intermediate fluid to the rinsing liquid, so that the temperature of the rinsing liquid rises. The rinsing liquid is then pumped from the coaxial heat exchanger back to the rinsing tank, so that the rinsing liquid in the rinsing tank is heated. Preferably, the intermediate circuit or the dishwasher comprises a temperature sensor or temperature probe that is configured to detect the temperature of the intermediate fluid and that is particularly preferably arranged between the condenser and the coaxial heat exchanger with respect to a flow direction of the intermediate fluid.Furthermore, the dishwasher preferably comprises a further temperature sensor or temperature probe configured to detect the temperature of the washing liquid in the washing tank.

[0037] This has the advantage that as long as the intermediate fluid in the intermediate circuit does not have a higher or sufficiently higher temperature than the rinsing liquid in the rinsing tank, the liquor circuit pump remains deactivated. If this were not the case, i.e. if the aforementioned heating process were not implemented and the liquor circuit pump were to be activated at the same time as the heat pump or compressor, whereby the temperature of the intermediate fluid in the intermediate circuit were possibly still lower than the temperature of the rinsing liquid in the rinsing tank, heat required for the rinsing process would be unnecessarily extracted from the rinsing tank and transferred to the intermediate fluid. The aforementioned heating process thus ensures that after the heat pump or compressor has started up.When the compressor is activated, the refrigerant is first heated, followed by the intermediate fluid in the intermediate circuit via the condenser, until heat transfer from the intermediate fluid to the washing liquid via the coaxial heat exchanger is possible and efficient enough. This further increases the efficiency and user-friendliness of the dishwasher.

[0038] Preferably, the dishwasher is configured to perform the heating process both while the wash tank is being filled with wash liquid and during the wash cycle. This makes the dishwasher significantly more efficient than if, for example, the wash liquid were heated exclusively by electric heaters built into the wash tank.

[0039] For example, the dishwasher can comprise a heat pump device that includes the refrigeration circuit, and an intake device that draws in machine air from an interior area of ​​the dishwasher and ambient air from an area surrounding the dishwasher, and supplies an air mixture of the machine air and the ambient air to the heat pump device. Heating the washing liquid in the washing tank while the washing tank is being filled, in particular before the dishwasher starts a washing cycle, can thus largely be achieved using the energy contained in the air in the room in which the dishwasher is installed, since no or only a small amount of vapor can be drawn in by an air system and used in the evaporator. This makes it significantly more efficient than heating the washing liquid exclusively via electric heaters installed in the washing tank.

[0040] Particularly preferably, the dishwasher is configured to execute the heating process when the water level of the washing liquid in the wash tank exceeds a minimum water level. Exceeding the minimum water level of the washing liquid in the wash tank is advantageous as a criterion for executing the heating process or for switching on the heat pump, since only then can the liquor circuit pump be operated safely without it sucking in air or cavitating.

[0041] In a further preferred embodiment, the dishwasher or the liquor circuit comprises a tank or rinse tank. The liquor circuit pump is configured to pump rinse liquid from the rinse tank to the coaxial heat exchanger and from the coaxial heat exchanger into the rinse tank. The dishwasher is configured to fill the rinse tank with preheated rinse liquid, in particular with preheated or preheated rinse liquid from a boiler, before the start of a rinse cycle. The dishwasher is further configured to perform a preheating process, wherein the preheating process comprises: activating or switching on the liquor circuit pump and the intermediate circuit pump at a preheating start time for preheating the refrigerant in the condenser using the preheated rinse liquid; and activating or switching on the compressor after a predetermined preheating period has elapsed from the preheating start time.By activating the lye circuit pump and the intermediate circuit pump at the preheating start time, the preheated rinsing liquid is pumped from the rinsing tank to the coaxial heat exchanger, and the intermediate fluid is pumped through the intermediate circuit, in particular through the coaxial heat exchanger and the compressor. In the coaxial heat exchanger, heat is transferred from the rinsing liquid to the intermediate fluid. This preheats the compressor. By activating the compressor after the predetermined preheating period has elapsed from the preheating start time, the refrigerant is then pumped through the refrigeration circuit, in particular through the condenser, so that heat can be transferred from the refrigerant to the intermediate fluid.

[0042] This has the advantage that the dishwasher can be started and operated safely even in cool ambient and installation conditions. If the aforementioned preheating process were not implemented, the condensing pressure of the refrigerant would be low or not present when the refrigeration circuit was completely cold when the compressor was activated, meaning that only a small amount of refrigerant would flow through the refrigeration circuit or an electronic expansion valve in the refrigeration circuit. If the compressor is already extracting refrigerant from an evaporator in the refrigeration circuit, but at the same time only a small amount of refrigerant is being injected into the evaporator, e.g. by the expansion valve, the pressure in the evaporator would drop and possibly fall below a lower switch-off threshold, which would cause the compressor to switch off. The aforementioned preheating process, on the other hand, creates a lower condensing pressure before the compressor is activated or switched off.When the compressor is switched on, the lye circuit pump is started simultaneously with the intermediate circuit pump for a predetermined period of time. This pumps preheated rinsing liquid from the rinsing tank to the coaxial heat exchanger, which then heats the intermediate fluid in the intermediate circuit. The intermediate fluid, in turn, heats the condenser and the refrigerant contained therein. As the refrigerant heats up in the condenser, the pressure of the refrigerant on the high-pressure side of the refrigeration circuit increases. When the compressor is activated or switched on, after the predetermined preheating period has elapsed, the heat pump or refrigeration circuit can be used right from the start due to the applied pressure of the refrigerant, e.g.upstream of the electronic expansion valve and the resulting refrigerant flow without significantly lowering the evaporation pressure of the refrigerant in the evaporator, without causing malfunctions due to insufficient evaporation pressure of the refrigerant in the evaporator. This further increases the efficiency and user-friendliness of the dishwasher.

[0043] Preferably, the dishwasher is configured such that it does not perform the preheating process if a condensing pressure of the refrigerant exceeds a minimum condensing pressure. Particularly preferably, the dishwasher comprises a high-pressure sensor for detecting or sensing the condensing pressure of the refrigerant or a high-pressure-side refrigerant pressure that is equal to, corresponds to, or substantially corresponds to the condensing pressure, and the dishwasher is configured such that it does not perform the preheating process if the condensing pressure of the refrigerant detected by the high-pressure sensor exceeds the minimum condensing pressure.

[0044] This can avoid unnecessary preheating processes and thus an unnecessary reduction in the overall efficiency of the dishwasher if the condenser still has a sufficiently high temperature.

[0045] Preferably, the dishwasher is configured to perform the preheating process while the wash tank is being filled with wash liquid. This increases the efficiency of the dishwasher. Particularly preferably, the dishwasher is configured to perform the preheating process when the water level of the wash liquid in the wash tank exceeds a minimum water level. This has the advantage that the liquor circuit pump can be operated safely without sucking in air or cavitating.

[0046] Some of the aspects of the present invention mentioned in the preceding sections can be realized independently of the inventive design of the coaxial heat exchanger and / or independently of the inventive connection unit. In particular, the present invention also relates to a dishwasher comprising: a refrigeration circuit comprising a refrigeration circuit hollow body for receiving a refrigerant and a compressor for compressing the refrigerant and for conveying the refrigerant through the refrigeration circuit hollow body; an intermediate circuit comprising an intermediate circuit hollow body for receiving an intermediate fluid and an intermediate circuit pump for conveying the intermediate fluid through the intermediate circuit hollow body; and a liquor circuit comprising a liquor circuit hollow body for receiving a rinsing liquid and a liquor circuit pump for conveying the rinsing liquid through the liquor circuit hollow body.wherein the refrigeration circuit comprises a condenser configured to transfer heat from the refrigerant to the intermediate fluid; wherein the dishwasher comprises a coaxial heat exchanger configured to transfer heat from the intermediate fluid to the rinsing liquid; wherein the liquor circuit comprises a rinsing tank; wherein the dishwasher is configured to fill the rinsing tank with rinsing liquid before starting a rinsing cycle; and wherein the dishwasher is configured to perform a heating process for heating the rinsing liquid in the rinsing tank, the heating process comprising: activating the compressor and the intermediate circuit pump at a first time to increase a temperature of the intermediate fluid;and activating the lye circuit pump at a second time after the first time when a difference between the temperature of the intermediate fluid and a temperature of the rinsing liquid in the rinsing tank exceeds a predetermined value;

[0047] The invention further relates to a dishwasher comprising: a refrigeration circuit comprising a refrigeration circuit hollow body for receiving a refrigerant and a compressor for compressing the refrigerant and for conveying the refrigerant through the refrigeration circuit hollow body; an intermediate circuit comprising an intermediate circuit hollow body for receiving an intermediate fluid and an intermediate circuit pump for conveying the intermediate fluid through the intermediate circuit hollow body; and a liquor circuit comprising a liquor circuit hollow body for receiving a rinsing liquid and a liquor circuit pump for conveying the rinsing liquid through the liquor circuit hollow body; wherein the refrigeration circuit comprises a condenser configured to transfer heat from the refrigerant to the intermediate fluid; wherein the dishwasher comprises a coaxial heat exchanger configured to transfer heat from the intermediate fluid to the rinsing liquid.wherein the liquor circuit comprises a wash tank; wherein the dishwasher is configured to fill the wash tank with preheated wash liquid before the start of a wash cycle; and wherein the dishwasher is configured to perform a preheating process, the preheating process comprising: activating the liquor circuit pump and the intermediate circuit pump at a preheating start time to preheat the refrigerant in the condenser using the preheated wash liquid; and activating the compressor after a predetermined preheating period has elapsed from the preheating start time.

[0048] Furthermore, the present invention relates to a heating method for a dishwasher, preferably a dishwasher according to one of claims 1 to 15 or a dishwasher as described above, wherein the heating method is a method for heating the washing liquid in the washing tank, wherein the heating method comprises: activating the compressor and the intermediate circuit pump at a first time to increase a temperature of the intermediate fluid; and activating the drain circuit pump at a second time after the first time when a difference between the temperature of the intermediate fluid and a temperature of the washing liquid in the washing tank exceeds a predetermined value.

[0049] Furthermore, the present invention relates to a preheating method for a dishwasher, preferably a dishwasher according to one of claims 1 to 15 or a dishwasher as described above, wherein the preheating method comprises: activating the drain circuit pump and the intermediate circuit pump at a preheating start time for preheating the refrigerant in the condenser by means of the preheated washing liquid; and activating the compressor after a predetermined preheating period has elapsed from the preheating start time.

[0050] These and other features and advantages of the invention will become clear from the accompanying drawings, which show particularly advantageous embodiments. They show: Fig. 1 a schematic overall overview of an embodiment of a dishwasher according to the invention; Fig. 2 the refrigeration circuit of the dishwasher Fig. 1; Fig. 3 the intermediate circuit of the dishwasher Fig. 1; Fig. 4 the lye circuit of the dishwasher Fig. 1; Fig. 5 the air system with drying zone of the dishwasher Fig. 1; Fig. 6 a schematic view of a connecting unit and another connecting unit; Fig. 7 a schematic view of a connecting unit; Fig. 8A a heat pump; and Fig. 8B an enlarged section of Fig. 8A.

[0051] The following description refers to a conveyor dishwasher 2 as an example of a dishwasher 2; however, the invention is not limited to a conveyor dishwasher 2, but relates generally to a dishwasher 2, which may also be, for example, a pass-through dishwasher.Likewise, in the following, a heat pump 1 is used as an example of a heat pump device 1, vapors 3 is used as an example of machine air 3, room air 4 is used as an example of ambient air 4, dishes 5 is used as an example of items to be washed 5, room air / vapor mixture 43 is used as an example of an air mixture 43, an installation room 45 is used as an example of an ambient area 45, a grease filter 46 is used as an example of a filter unit 46, an intermediate circuit temperature sensor 47 is used as an example of a temperature sensor 47, a pre-wash zone 51 and / or a main wash zone 52 and / or a final wash zone 31 are used as examples of a wash zone 51, 52, 31, a hose 54 is used as an example of an outer hollow body 54, a corrugated pipe 55 is used as an example of an inner hollow body 55, a T-piece 56 is used as an example of a hollow body connecting part 56, a hose nozzle 57 is used as an example of a third nozzle 57 or a first nozzle 78, a hose nozzle of the rinsing liquid inlet or outlet.Outlet 61 as an example of a second grommet 61, an annular gap 59 as an example of a cavity 59, a receptacle 62 as an example of a receptacle section 62, a front sheet metal tab as an example of a holding element, a stop tab as an example of a guide element, and a fourth corrugated pipe shaft for positive locking 77 as an example of a projection 77. Furthermore, additional room air intake 38 refers to a system comprising or consisting of one or more heat pump housing openings and an integrated filter unit 46, e.g. an integrated grease filter 46. Furthermore, the terms machine air 3 and machine exhaust air 3, refrigeration circuit 6 and refrigeration circuit 6 are used synonymously, as are intermediate circuit 17 and secondary intermediate circuit 17, intermediate fluid 18 and secondary fluid 18, lye circuit 25 and lye circuit 25, lye circuit pump 27 and tank circulation pump 27 as well as control unit and dishwasher control unit.

[0052] Fig. 1 shows a schematic overall overview of an embodiment of a dishwasher 2 according to the invention; Fig. 2 shows in particular a refrigeration circuit 6 of the dishwasher 2 from Fig. 1; Fig. 3 shows in particular an intermediate circuit 17 of the dishwasher 2 from Fig. 1; Fig. 4 shows in particular a lye circuit 25 of the dishwasher 2 from Fig. 1; and Fig. 5 shows in particular an air system with drying zone 53 of the dishwasher 2 from Fig. 1.

[0053] In particular, Fig. 1 to 5 each show a commercial conveyor dishwasher 2 for the high recovery of heat energy contained in the machine exhaust air 3 and the room air 4 surrounding the dishwasher 2, which heat energy is transferred to the machine exhaust air 3 and room air 4 by the washing processes within the dishwasher 2, by the dishwasher 2 itself, and by the washed dishes 5. By high heat recovery from the machine exhaust air 3 and room air 4 and transferring this energy back to the washing processes, the energy required to maintain the washing processes is significantly reduced. In this way, a large portion of the heat and moisture that was previously transferred to the machine exhaust air 3 and room air 4 by the washing processes, the dishwasher 2 itself, and the warm / moist dishes 5 is removed from the machine exhaust air 3 and room air 4.

[0054] The heat pump 1 is installed in a heat pump housing 15 and contains a refrigeration circuit 6 consisting of an evaporator 7, a compressor 8, a series circuit of a condenser 9 and a subcooler 10, an electronic expansion valve 11, and the pipes 12 of different nominal diameters connecting the aforementioned components. The refrigeration circuit 6 further contains a high-pressure sensor 13 for detecting the high-pressure refrigerant pressure, which corresponds or substantially corresponds to the condensation pressure of the refrigerant, a low-pressure sensor 14 for detecting the low-pressure refrigerant pressure, which corresponds or substantially corresponds to the evaporation pressure of the refrigerant, and other components.

[0055] A refrigerant 16 circulates in the refrigeration circuit 6. At low pressure in the evaporator 7, it absorbs thermal energy from the machine exhaust air 3, thereby evaporating and cooling the machine exhaust air 3. In the process, some of the water vapor contained in the machine exhaust air 3 also condenses. This condensation energy is also transferred to the refrigerant 16 via the evaporator 7. The compressor 8 then draws in the gaseous refrigerant 16 and compresses it to a higher pressure. In the process, the refrigerant 16 heats up considerably and is cooled in the condenser 9 located downstream (from the refrigerant perspective) of the compressor 8, where it is then condensed / liquefied again. The thermal energy released is transferred to a secondary fluid 18 circulating in a secondary intermediate circuit 17, which is heated in the process.The completely or at least partially liquefied refrigerant 16 is then further cooled / subcooled in the subcooler 10, which is located downstream of the condenser 9 from the refrigerant perspective, or the remaining gaseous refrigerant 16 is first liquefied / condensed. The heat energy released in this process is transferred to a post-rinse liquid 93 located in the post-rinse system 94, which is sucked in from a water network separator / air gap 50 by a post-rinse pump 49 and then conveyed to the subcooler 10, preheated therein, and subsequently heated to a desired post-rinse temperature in an electrically heated boiler 48. The completely liquefied and subcooled refrigerant 16 is now expanded back to a lower pressure by the electronic expansion valve 11 downstream of the subcooler 10 from the refrigerant perspective, during which it cools down significantly and partially evaporates again.This mixture of still liquid and gaseous refrigerant 16 is then fed back into the evaporator 7 and the process begins again.

[0056] The evaporator 7 of the heat pump 1 is part of the air system 33, which, in addition to the evaporator 7, essentially consists of a first intake area 34 on the dish inlet side 35, a second intake area on the dish outlet side 37 or, depending on the dishwasher variant, an additional room air intake 38, a speed-adjustable exhaust air fan 39, and a system of air ducts 40. The mixture of room air 4 and vapors generated during the washing process, the so-called room air / vapor mixture 43, sucked in by the exhaust air fan 39 at the first intake area 34 and second intake area or the additional room air intake 38, is guided through the system of air ducts 40 to the heat pump housing 15 and cooled and dehumidified by heat exchange with the refrigerant 16 by means of the evaporator 7.The exhaust air fan 39 is housed downstream of the evaporator 7, from the perspective of the room air / vapor mixture 43, in a separate fan housing 42 mounted above the heat pump housing 15. The cooled and dehumidified room air / vapor mixture 43 exits through a plurality of openings 44 in the fan housing 42 into the installation space 45 surrounding the dishwasher 2. To separate dirt and droplets and protect the air system 33 from coarser contaminants, a grease filter 46 is integrated in each of the first intake area 34, the second intake area, and the additional room air intake 38.

[0057] The secondary intermediate circuit 17, whose secondary fluid 18 was heated by the condenser 9, is a circuit open to the atmosphere of the installation room of the commercial conveyor dishwasher 2 or the dishwasher interior 20. The secondary intermediate circuit 17 consists of a reservoir 21 to ensure a certain water level for the intermediate circuit pump 22, which is arranged downstream from the perspective of the secondary fluid 18 and conveys the secondary fluid 18 to the condenser 9, an intermediate circuit temperature sensor 47 at the outlet of the condenser 9, the coaxial heat exchanger 23, which transfers the thermal energy contained in the secondary fluid 18 after its heating in the condenser 9 to a rinsing liquid 24 and represents a system separation from the lye circuit 25, as well as the various hose connections between the aforementioned components (not described in detail).The secondary intermediate circuit 17 is filled with rinse liquid 93 through an intermediate circuit filling valve 29 connected to the rinse system 94 via hoses until the secondary intermediate circuit 17 is completely filled and overflows into the rinse zone 31 via an overflow hose 30. This filling process is activated by a dishwasher control unit and deactivated again after the filling process is completed.

[0058] The aforementioned lye circuit 25 serves to suck in the washing liquid 24 required for the washing process in a first main washing zone 52 located downstream of an optionally present pre-wash zone 51 in the dish transport direction and mixed with appropriate washing chemicals and dirt particles rinsed off the dishes 5 from a washing tank 26 and to convey it by means of a tank circulation pump 27 to the coaxial heat exchanger 23, in which the washing liquid 24 is heated by the thermal energy contained in the secondary fluid 18. The washing liquid 24 then flows back into the washing tank 26. The coaxial heat exchanger 23, used for system separation, ensures that the washing liquid 24 loaded with washing chemicals and dirt particles does not come into contact with the secondary fluid 18, thus protecting the condenser 9 of the heat pump 1.

[0059] As particularly in Fig. 6 and Fig. As can be seen in Figure 7, the dishwasher 2 according to an embodiment of the present invention comprises: a refrigeration circuit 6, which comprises a refrigeration circuit hollow body 12 for receiving a refrigerant 16 and a compressor 8 for compressing the refrigerant 16 and for conveying the refrigerant 16 through the refrigeration circuit hollow body 12; an intermediate circuit 17, which comprises an intermediate circuit hollow body 19 for receiving an intermediate fluid 18 and an intermediate circuit pump 22 for conveying the intermediate fluid 18 through the intermediate circuit hollow body 19; and a liquor circuit 25, which comprises a liquor circuit hollow body 28 for receiving a rinsing liquid 24 and a liquor circuit pump 27 for conveying the rinsing liquid 24 through the liquor circuit hollow body 28; wherein the refrigeration circuit 6 comprises a condenser 9 configured to transfer heat from the refrigerant 16 to the intermediate fluid 18;wherein the dishwasher 2 comprises a coaxial heat exchanger 23 configured to transfer heat from the intermediate fluid 18 to the rinsing liquid 24, wherein the coaxial heat exchanger 23 comprises an outer hollow body 54 and an inner hollow body 55 arranged within the outer hollow body 54, wherein the inner hollow body 55 is configured to receive the rinsing liquid 24, wherein a cavity 59 between the outer hollow body 54 and the inner hollow body 55 is configured to receive the intermediate fluid 18; wherein the dishwasher 2 comprises a connecting unit configured to connect the intermediate circuit hollow body 19 to the outer hollow body 54 and to connect the liquor circuit hollow body 28 to the inner hollow body 55;wherein the connection unit comprises a hollow body connection part 56 with a first connection section 56a, a second connection section 56b and a third connection section 56c as well as a first grommet 78, a second grommet 61 and a third grommet 57; wherein the first grommet 78 is configured to connect the first connection section 56a to the intermediate circuit hollow body 19; wherein the second grommet 61 is configured to connect the second connection section 56b to the lye circuit hollow body 28 and is configured to connect the second connection section 56b to the inner hollow body 55, wherein the second grommet 61 comprises a receiving section 62 for receiving the inner hollow body 55; and wherein the third grommet 57 is configured to connect the third connection section 56c to the outer hollow body 54.

[0060] In particular, a first end section 78a of the first grommet 78 can be inserted into the first connecting section 56a and pressed thereto, and the intermediate circuit hollow body 19 can be inserted onto a second end section 78b of the first grommet 78. Furthermore, a central section 61c of the second grommet 61 can be inserted into the second connecting section 56b and pressed thereto, and the lye circuit hollow body 28 can be inserted onto a first end section 61a of the second grommet 61. Furthermore, the inner hollow body 55 can be inserted into the receiving section 62 up to a stop 63 and pressed thereto. The receiving section 62 can be a third end section 61b of the second grommet 61. Furthermore, a first end portion 57a ​​of the third grommet 57 can be inserted into the third connecting portion 56c and pressed therewith, and the outer hollow body 54 can be inserted onto a second end portion 57b of the third grommet 57.

[0061] The hollow body connecting part 56 can be T-shaped, with the second connecting section 56b and the third connecting section 56c arranged parallel and the first connecting section 56a arranged perpendicular to the second connecting section 56b and the third connecting section 56c. The inner hollow body 55 can be designed as a corrugated tube 55 with one or more corrugations, with the receiving section 62 of the second grommet 61 being pressed onto the corrugated tube via one or more O-rings 64, preferably via three O-rings 64, each of which is arranged in a corresponding corrugation of the corrugated tube. The receiving section 62 can have a projection 77 that positively engages a corrugation of the corrugated tube. An inner diameter of the second grommet 61, 61a-c can decrease from a central section of the second grommet 61, 61a-c toward the receiving section 62.The connecting unit can be configured to connect the intermediate circuit hollow body 19 to an initial section of the outer hollow body 54 and to connect the liquor circuit hollow body 28 to an initial section of the inner hollow body 55, wherein the dishwasher 2 comprises a further connecting unit configured to connect the intermediate circuit hollow body 19 to an end section of the outer hollow body 54 and to connect the liquor circuit hollow body 28 to an end section of the inner hollow body 55.

[0062] In other words, the dishwasher 2 can include a coaxial heat exchanger 23 for system separation between the lye circuit 25 and the secondary intermediate circuit 17.

[0063] The rinsing liquid 24 to be heated by the heat pump 1 may be contaminated with rinsing chemicals and dirt particles and should not come into direct contact with the heat exchangers of the cooling circuit 6 of the heat pump 1 to prevent them from becoming clogged or chemically attacked. For this reason, the thermal energy provided by the heat pump 7 via the condenser 9 to heat the rinsing tank 26 is first transferred to a secondary fluid 18, which is then pumped by the intermediate circuit pump 22 to a coaxial heat exchanger 23, which forms a system separation from the secondary intermediate circuit 17 and the lye circuit 25. This prevents aggressive rinsing liquid 24 from entering the secondary intermediate circuit 17. In the coaxial heat exchanger 23, the secondary fluid 18 is cooled in countercurrent, and the rinsing liquid 24 is heated.The cooled secondary fluid 18 is then sucked back into the intermediate circuit pump 22 via a reservoir tank 21 and pumped back to the condenser 9. The secondary intermediate circuit 17 is thus self-contained, but is connected to the dishwasher interior 20 via an overflow hose 30, which is why no overpressure builds up in the reservoir tank 21 of the secondary intermediate circuit 17 compared to the atmosphere of the dishwasher interior 20 and thus the installation space 45 of the dishwasher 2.

[0064] The coaxial heat exchanger 23 essentially consists of a corrugated pipe 55 located in a hose 54, as well as two special T-pieces 56 at the beginning and end of the coaxial heat exchanger 23 to which both the corrugated pipe 55 and the hose 54 are tightly fastened.

[0065] The rinsing liquid 24, which is mixed with rinsing chemicals and dirt particles and is to be heated, flows through the corrugated pipe 55 via the straight connections of the T-piece 56. The cooling secondary fluid 18 flows in countercurrent in the annular gap 59 formed between the corrugated pipe 55 and the hose 54.

[0066] The hose 54 is sealed to the T-piece 56 on the inlet and outlet sides of the coaxial heat exchanger 23 by means of hose nozzles 57 and hose clamps 58, with the hose nozzles 57 being inserted into the T-pieces 56 and pressed together. The compression between the T-piece 56 and the hose nozzle 57 is sealed accordingly by an O-ring 60 located in the compression.

[0067] The connection of the corrugated pipe 55 with the hose nozzle of the flushing liquid inlet or outlet 61 has the feature that the hose nozzle 61 is designed such that it can be pressed into the T-piece 56 as already described above, and also contains a receptacle 62 for the corrugated pipe 55, into which the corrugated pipe can be inserted up to a stop 63. The seal between the receptacle 62 and the corrugated pipe 55 is achieved by means of three O-rings 64 specially adapted to the corrugated pipe diameter in the first three corrugations of the corrugated pipe 55, which are deformed when the receptacle 62 is pressed onto the corrugated pipe 55 so that they completely fill the corrugations and create a tight connection with the receptacle 62. The pressing of the receptacle 62 reduces the diameter of the receptacle 62 only to such an extent that the O-rings 64 lie tightly against the corrugated pipe 55 and the receptacle 62, but the corrugated pipe 55 is not damaged in the process.Furthermore, according to one aspect of the present invention, when the receptacle 62 is pressed together, a positive connection is established between the receptacle 62 and the fourth corrugation of the corrugated pipe 55, so that the corrugated pipe 55 cannot be pulled out of the receptacle 62 even when the corrugated pipe is subjected to tensile stress. The hose nozzle 61 is also designed such that its inner diameter continuously decreases up to the stop 63 of the corrugated pipe 55, so that the flow of the flushing liquid 24 experiences a minimal pressure loss at this point. The described connection of the corrugated pipe 55 to the hose nozzle 61 is identical on the inlet and outlet sides of the flushing liquid 24 of the coaxial heat exchanger 23.

[0068] The inlet and outlet of the secondary fluid 18 takes place via the side connection 65 of the T-pieces 56, again via a hose nozzle 78, which is tightly and firmly connected to the T-piece 56 by means of pressing with an O-ring 60.

[0069] As particularly in Fig. 1 to Fig. 5, the liquor circuit 25 may comprise a wash tank 26; wherein the dishwasher 2 is configured to fill the wash tank 26 with preheated wash liquid 24 before the start of a wash cycle; and wherein the dishwasher 2 is configured to execute a preheating process, the preheating process comprising: activating the liquor circuit pump 27 and the intermediate circuit pump 22 at a preheating start time to preheat the refrigerant 16 in the condenser 9 using the preheated wash liquid; and activating the compressor 8 after a predetermined preheating period has elapsed from the preheating start time. The dishwasher 2 may be configured not to execute the preheating process if a condensing pressure of the refrigerant 16 exceeds a minimum condensing pressure.

[0070] In other words, the dishwasher 2 can include a condenser 9 which can be preheated before a cold start of the heat pump 1 when filling the dishwasher 2.

[0071] Since the commercial conveyor dishwasher 2 with heat pump 1 must be started and operated safely even in cool ambient and installation conditions, according to one aspect of the present invention, a preheating process for the condenser 9 of the heat pump 1 is implemented in the dishwasher control unit.

[0072] The reason for this is that when the refrigeration circuit 6 is completely cold, there is no or only a low condensation pressure, measured by the high-pressure sensor 13, when the compressor 8 starts up, or has been built up by the compressor 8, so that as a result, only a small amount of refrigerant 16 flows through the electronic expansion valve 11. Since the compressor 8 is already sucking refrigerant 16 out of the evaporator 7, but at the same time only a small amount of refrigerant 16 is being injected into the evaporator 7 by the expansion valve 11, the pressure in the evaporator 7 drops and can possibly fall below a lower shutdown threshold, which leads to the compressor 8 being switched off.

[0073] When heat pump 1 is first started, while dishwasher 2 is being filled with water preheated in boiler 48, and before compressor 8 is switched on, tank circulation pump 27 is started simultaneously with intermediate circuit pump 22 for a predefined time. This pumps preheated dishwashing liquid 24 from wash tank 26 to coaxial heat exchanger 23, where it then heats secondary fluid 18 of secondary intermediate circuit 17 in countercurrent. Secondary fluid 18, in turn, heats condenser 9 and the refrigerant 16 also contained therein.Due to the heating of the refrigerant 16 in the condenser 9, the pressure of the refrigerant 16 on the high-pressure side of the heat pump 1 increases and the heat pump 1 can start right from the start when the compressor 8 is switched on, after a defined preheating time has elapsed, due to the applied pressure of the refrigerant upstream of the electronic expansion valve 11 and a resulting refrigerant flow without a significant drop in the evaporation pressure of the refrigerant 16 in the evaporator 7, without a malfunction occurring due to the evaporation pressure of the refrigerant 16 in the evaporator 7 being too low.

[0074] This preheating process is only ever performed when the dishwasher 2 is refilled with water. In a further embodiment, the preheating process of the condenser 9 is also only performed when the condensing pressure measured by the high-pressure sensor 13 or the resulting condensing temperature of the refrigerant 16 falls below a defined value. This avoids unnecessary preheating processes and thus an unnecessary reduction in the overall efficiency of the dishwasher 2 with heat pump 1, should the condenser 9 still have a sufficiently high temperature.

[0075] As particularly in Fig. 1 to Fig. 5, the intermediate circuit 17 can comprise a storage tank 21 for receiving the intermediate fluid 18, wherein the storage tank 21 is arranged upstream of the intermediate circuit pump 22 with respect to a flow direction of the intermediate fluid 18. The intermediate circuit hollow body 19 can comprise an inflow section which is arranged upstream of the storage tank 21 with respect to a flow direction of the intermediate fluid 18 and is connected to the storage tank 21 such that the intermediate fluid 18 can flow into the storage tank 21 through the inflow section, wherein a cross-sectional area of ​​the storage tank 21 perpendicular to a flow direction of the intermediate fluid 18 through the storage tank 21 is larger than a cross-sectional area of ​​the inflow section perpendicular to a flow direction of the intermediate fluid 18 through the inflow section.The liquor circuit 25 may comprise a wash tank 26; wherein the dishwasher 2 is configured to fill the wash tank 26 with wash liquid 24 before the start of a wash cycle; and wherein the dishwasher 2 is configured to carry out a heating process for heating the wash liquid 24 in the wash tank 26, wherein the heating process comprises: activating the compressor 8 and the intermediate circuit pump 22 at a first time to increase a temperature of the intermediate fluid 18; and activating the liquor circuit pump 27 at a second time after the first time when a difference between the temperature of the intermediate fluid 18 and a temperature of the wash liquid 24 in the wash tank 26 exceeds a predetermined value.The intermediate circuit may comprise a temperature sensor 47 arranged between the condenser 9 and the coaxial heat exchanger 23 with respect to a flow direction of the intermediate fluid and configured to detect the temperature of the intermediate fluid 18.

[0076] In other words, the dishwasher may include a secondary intermediate circuit 17 with a storage tank 21 and an intermediate circuit temperature sensor 47 at the outlet of the secondary fluid 18 at the condenser 9.

[0077] As already described, the secondary intermediate circuit 17 contains a reservoir 21 with a defined height and diameter to ensure a certain water reservoir for the intermediate circuit pump 22. This prevents or minimizes the risk of cavitation in the intermediate circuit pump 22 and makes certain losses of secondary fluid 18, e.g., due to minor leakage or due to a small amount of secondary fluid 18 flowing out via the overflow hose 30, tolerable without the intermediate circuit pump 22 sucking in air and the volume flow in the secondary intermediate circuit 17 coming to a standstill.For this purpose, the storage tank 21 is mounted at the highest point in the heat pump housing 15, which additionally enables the venting of the secondary intermediate circuit 17. The secondary fluid 18 flowing into the upper area of ​​the storage tank 21 flows more slowly due to the cross-sectional expansion in the storage tank 21, allowing gas / air bubbles contained in the secondary fluid 18 to rise more easily in the storage tank 21. Separating gas / air bubbles are then vented into the machine interior 20 via the overflow hose 30.

[0078] Furthermore, shortly after the secondary fluid 18 exits the condenser 9, the secondary intermediate circuit 17 contains an intermediate circuit temperature sensor 47, which measures the temperature of the secondary fluid and transmits it to the dishwasher control unit. If the heat pump 1 is in regular operation, i.e., the previously described preheating process is not active, it heats the secondary fluid 18 conveyed in the secondary intermediate circuit 17 by the intermediate circuit pump 22 via the condenser 9 according to one aspect of the present invention, without the tank circulation pump 27 being activated, until the temperature of the secondary fluid 18, measured by the intermediate circuit temperature sensor 47, is higher by a defined temperature difference than the temperature of the washing liquid 24 in the washing tank 26, which is measured by a temperature sensor.Only then is the tank circulation pump 27 activated and, as a result, rinsing liquid 24 is pumped from the rinsing tank 26 to the coaxial heat exchanger 23, where it is heated due to the secondary fluid 18 being at a higher temperature than the rinsing liquid 24. According to one aspect of the present invention, the process described above ensures that the tank circulation pump 27 remains deactivated as long as the secondary fluid 18 in the secondary intermediate circuit 17 does not have a higher temperature than the rinsing liquid 24 in the rinsing tank 26. If this were not the case, i.e. if the aforementioned process were not implemented, and the tank circulation pump 27 were activated at the same time as the heat pump 1, which, however, might still have a lower temperature of the secondary fluid 18 in the secondary intermediate circuit 17 than the temperature of the rinsing liquid 24 in the rinsing tank 26, heat required for the rinsing process would be unnecessarily extracted from the rinsing tank 26 and transferred to the secondary fluid 18.After starting, the heat pump 1 should first heat itself and the secondary fluid 18 in the secondary intermediate circuit 17 until heat transfer via the coaxial heat exchanger 23 to the rinsing fluid 24 is possible and sensible.

[0079] As particularly in Fig. 1 to Fig. 5, the dishwasher 2 can be configured to perform the heating process both during the filling of the wash tank 26 with wash liquid 24 and during the washing process. The dishwasher 2 can be configured to perform the heating process when a water level of the wash liquid 24 in the wash tank 26 exceeds a minimum water level. The dishwasher 2 can further be configured to perform the preheating process during the filling of the wash tank 26 with wash liquid 24; preferably, the dishwasher 2 is configured to perform the preheating process when a water level of the wash liquid 24 in the wash tank 26 exceeds a minimum water level.

[0080] In other words, the dishwasher may include a rinsing tank 26, wherein the rinsing liquid 24 in the rinsing tank 26 may be heated during the filling of the dishwasher 2 with water.

[0081] In order to be able to heat the wash tank 26 of the dishwasher 2 efficiently by means of the heat pump 1 via the secondary intermediate circuit 17 and the lye circuit 25 while the wash tank 26 is being filled with wash liquid 24, the heat pump 1 is activated once a defined fill level of the wash liquid 24 in the wash tank 26 is exceeded. At the same time as the heat pump 1, the intermediate circuit pump 22 is also activated, as well as, if necessary, as already described, the tank circulation pump 27, provided that a preheating process for the condenser 9 of the heat pump 1 is appropriate.

[0082] Exceeding the defined fill level of the rinsing liquid 24 in the rinsing tank 26 is therefore advantageous as a criterion for switching on the heat pump 1, since only then can the tank circulation pump 27 be operated safely without it sucking in air or cavitating.

[0083] The heating of the rinsing liquid 24 in the rinsing tank 26 by the heat pump 1 during the filling of the dishwasher 2, i.e. before the rinsing process of the dishwasher 2 starts, is carried out largely by using the energy contained in the room air 4 of the installation room 45, since no or only a small amount of vapors can be sucked in by the air system 33 and used in the evaporator 7 and is therefore significantly more efficient than if the heating of the rinsing liquid 24 were to take place exclusively via electric heaters installed in the rinsing tank 26.

[0084] As particularly in Fig. 8A and Fig. As can be seen in Figure 8B, the heat pump 1 can be quickly replaced, e.g. in the event of a fault, by only loosening a few connections by pulling out / inserting the complete heat pump 1.

[0085] In the event of a fault, for example, the entire heat pump 1 can be removed and reinstalled in a few simple steps without interfering with the refrigeration circuit 6. To do so, only four mounting brackets 74 need to be removed, the electrical connectors 75 between the heat pump 1 and the dishwasher control unit need to be disconnected, one hose each needs to be disconnected on the suction side of the intermediate circuit pump 22 and at the outlet of the secondary fluid 18 at the top of the condenser 9, and the two hoses of the rinse system 94 need to be removed from the subcooler 10.

[0086] The heat pump 1 can now be pulled out of the heat pump housing 15 via sliding rails 76. All other non-removable connections and components are arranged so that they can remain in place during installation / removal of the heat pump 1. Reinstallation of the heat pump 1 is carried out in the reverse order. List of reference symbols 1 heat pump device, heat pump 2 Dishwasher, conveyor dishwasher 3 Machine air, machine exhaust air, vapors 4 Ambient air, room air 5 Dishes, dishes 6 refrigeration circuit, refrigeration circuit 7 evaporators 8 compressors 9 Condenser 10 subcoolers 11 Expansion valve 12 refrigeration circuit pipes 13 High pressure sensor 14 Low pressure sensor 15 heat pump housing 16 Refrigerants 17 Intermediate circuit, secondary intermediate circuit 18 Intermediate fluid, secondary fluid 19 intermediate circuit hollow body 20 Dishwasher interior 21 storage tanks 22 Intermediate circuit pump 23 coaxial heat exchangers 24 Flushing liquid 25 lye cycle, lye cycle 26 Rinse tank 27 Lye circuit pump, tank circulation pump 28 lye circle hollow bodies 29 Intermediate circuit filling valve 30 overflow hose 31 Rinse zone, rinse zone 33 Air system 34 First intake area 35 Dish inlet side 37 Dish outlet side 38 Additional room air intake 39 Exhaust air fan 40 system of air pipes 42 fan housing 43 Air mixture, room air / vapour mixture 44 openings in the fan housing 45 Surrounding area, installation room 46 Filter unit, grease filter 47 Temperature sensor, intermediate circuit temperature sensor 48 boilers 49 Rinse pump 50 water network separators, Airgap 51 Rinse zone, pre-rinse zone 52 Rinse zone, main rinse zone 53 Dry Zone 54 Outer hollow body, hose 55 inner hollow body, corrugated pipe 56 Hollow body connecting part, T-piece 56a First connecting section 56b Second connecting section 56c Third connecting section 57 Third nozzle, hose nozzle 57a First end section of the third spout 57b Second end section of the third grommet 58 hose clamp 59 Cavity, annular gap 60 O-ring 61 Second nozzle, hose nozzle of the rinsing liquid inlet or outlet 61a First end section of the second grommet 61c Middle section of the second spout 61b End section of the second grommet 62 Recording section, recording 63 stop 64 O-ring for corrugated pipe 65 side connection 66 exhaust air 74 mounting brackets 75 electrical plugs 76 sliding rails 77 Projection, fourth corrugated tube wave for positive locking 78 First nozzle, hose nozzle 78a First end section of the first spout 78b Second end section of the first grommet 91 Inlet water 92 Wastewater 93 Rinse liquid 94 Rinse system 95 Transport device 96 blowers

Claims

[1] Dishwasher (2), comprising: a refrigeration circuit (6) comprising a refrigeration circuit hollow body (12) for receiving a refrigerant (16) and a compressor (8) for compressing the refrigerant (16) and for conveying the refrigerant (16) through the refrigeration circuit hollow body (12); an intermediate circuit (17) comprising an intermediate circuit hollow body (19) for receiving an intermediate fluid (18) and an intermediate circuit pump (22) for conveying the intermediate fluid (18) through the intermediate circuit hollow body (19); and a lye circuit (25) comprising a lye circuit hollow body (28) for receiving a rinsing liquid (24) and a lye circuit pump (27) for conveying the rinsing liquid (24) through the lye circuit hollow body (28); wherein the refrigeration circuit (6) comprises a condenser (9) configured to transfer heat from the refrigerant (16) to the intermediate fluid (18); wherein the dishwasher (2) comprises a coaxial heat exchanger (23) configured to transfer heat from the intermediate fluid (18) to the rinsing liquid (24), wherein the coaxial heat exchanger (23) comprises an outer hollow body (54) and an inner hollow body (55) arranged within the outer hollow body (54), wherein the inner hollow body (55) is configured to receive the rinsing liquid (24), wherein a cavity (59) between the outer hollow body (54) and the inner hollow body (55) is configured to receive the intermediate fluid (18); wherein the dishwasher (2) comprises a connecting unit configured to connect the intermediate circuit hollow body (19) to the outer hollow body (54) and to connect the liquor circuit hollow body (28) to the inner hollow body (55); wherein the connecting unit comprises a hollow body connecting part (56) with a first connecting section (56a), a second connecting section (56b) and a third connecting section (56c) as well as a first grommet (78), a second grommet (61) and a third grommet (57); wherein the first grommet (78) is configured to connect the first connecting portion (56a) to the intermediate circuit hollow body (19); wherein the second grommet (61) is configured to connect the second connecting portion (56b) to the lye circuit hollow body (28) and is configured to connect the second connecting portion (56b) to the inner hollow body (55), wherein the second grommet (61) comprises a receiving portion (62) for receiving the inner hollow body (55); and wherein the third grommet (57, 57a, 57b) is configured to connect the third connecting portion (56c) to the outer hollow body (54). [2] Dishwasher (2) according to claim 1, wherein the hollow body connecting part (56) is T-shaped, wherein the second connecting portion (56b) and the third connecting portion (56c) are arranged in parallel and the first connecting portion (56a) is arranged perpendicular to the second connecting portion (56b) and the third connecting portion (56c). [3] Dishwasher (2) according to one of the preceding claims, wherein the inner hollow body (55) is designed as a corrugated tube (55) with one or more corrugations, wherein the receiving section (62) of the second spout (61) is pressed with the corrugated tube via one or more O-rings (64), preferably via three O-rings (64), each of which is arranged in a corresponding corrugation of the corrugated tube. [4] Dishwasher (2) according to one of the preceding claims, wherein the receiving portion (62) has a projection (77) which positively engages in a shaft of the corrugated pipe. [5] Dishwasher (2) according to one of the preceding claims, wherein an inner diameter of the second spout (61, 61a-c) decreases from a central portion of the second spout (61, 61a-c) towards the receiving portion (62). [6] Dishwasher (2) according to one of the preceding claims, wherein the connecting unit is configured to connect the intermediate circuit hollow body (19) to a starting portion of the outer hollow body (54) and to connect the liquor circuit hollow body (28) to a starting portion of the inner hollow body (55), wherein the dishwasher (2) comprises a further connecting unit configured to connect the intermediate circuit hollow body (19) to an end portion of the outer hollow body (54) and to connect the liquor circuit hollow body (28) to an end portion of the inner hollow body (55). [7] Dishwasher (2) according to one of the preceding claims, wherein the intermediate circuit (17) comprises a storage container (21) for receiving the intermediate fluid (18), wherein the storage container (21) is arranged upstream of the intermediate circuit pump (22) with respect to a flow direction of the intermediate fluid (18). [8] Dishwasher (2) according to claim 7, wherein the intermediate circuit hollow body (19) comprises an inflow section which is arranged upstream of the storage container (21) with respect to a flow direction of the intermediate fluid (18) and is connected to the storage container (21) so that the intermediate fluid (18) can flow into the storage container (21) through the inflow section, wherein a cross-sectional area of ​​the storage container (21) perpendicular to a flow direction of the intermediate fluid (18) through the storage container (21) is larger than a cross-sectional area of ​​the inflow section perpendicular to a flow direction of the intermediate fluid (18) through the inflow section. [9] Dishwasher (2) according to one of the preceding claims, wherein the lye circuit (25) comprises a rinsing tank (26); wherein the dishwasher (2) is configured to fill the washing tank (26) with washing liquid (24) before starting a washing process; and wherein the dishwasher (2) is configured to carry out a heating process for heating the washing liquid (24) in the washing tank (26), the heating process comprising: - activating the compressor (8) and the intermediate circuit pump (22) at a first time to increase a temperature of the intermediate fluid (18); and - activating the lye circuit pump (27) at a second time after the first time when a difference between the temperature of the intermediate fluid (18) and a temperature of the rinsing liquid (24) in the rinsing tank (26) exceeds a predetermined value. [10] Dishwasher (2) according to claim 9, wherein the intermediate circuit comprises a temperature sensor (47) arranged between the condenser (9) and the coaxial heat exchanger (23) with respect to a flow direction of the intermediate fluid and configured to detect the temperature of the intermediate fluid (18). [11] Dishwasher (2) according to claim 9 or 10, wherein the dishwasher (2) is configured to carry out the heating process both during the filling of the washing tank (26) with washing liquid (24) and during the washing process. [12] Dishwasher according to claim 11, wherein the dishwasher (2) is configured to carry out the heating process when a water level of the washing liquid (24) in the washing tank (26) exceeds a minimum water level. [13] Dishwasher (2) according to one of the preceding claims, wherein the lye circuit (25) comprises a rinsing tank (26); wherein the dishwasher (2) is configured to fill the washing tank (26) with preheated washing liquid (24) before starting a washing process; and wherein the dishwasher (2) is configured to perform a preheating process, the preheating process comprising: - activating the lye circuit pump (27) and the intermediate circuit pump (22) at a preheating start time for preheating the refrigerant (16) in the condenser (9) by means of the preheated rinsing liquid; and - Activating the compressor (8) after a predetermined preheating period has elapsed from the preheating start time. [14] Dishwasher (2) according to claim 13, wherein the dishwasher (2) is configured not to perform the preheating process when a condensing pressure of the refrigerant (16) exceeds a minimum condensing pressure. [15] Dishwasher (2) according to one of claims 13 or 14, wherein the dishwasher (2) is configured to carry out the preheating process during the filling of the washing tank (26) with washing liquid (24); preferably, the dishwasher (2) is configured to carry out the preheating process when a water level of the washing liquid (24) in the washing tank (26) exceeds a minimum water level.

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