Cooking device with a cooling device

Abstract

The invention relates to a cooking appliance (2) comprising a housing (4), a cooking chamber (6) arranged in the housing (4), a heating device (8) for heating the cooking chamber (6) in a heating mode of the cooking appliance (2), and a cooling device (10) for cooling the cooking chamber (6) in a cooling mode of the cooking appliance (2), characterized in that the cooling device (10) has a heat pipe (12), wherein an evaporator section (14) of the heat pipe (12) faces the cooking chamber (6) and a condenser section (16) of the heat pipe (12) faces away from the cooking chamber (6) in the housing (4). The invention further relates to a cooling device (10) for a cooking appliance (2).

Description

[0001] The invention relates to a cooking appliance with a cooling device of the type mentioned in the preamble of claim 1.

[0002] Such cooking appliances with a cooling device and cooling devices for a cooking appliance are already known from the prior art. For example, from publications CN 110 537 834 A and US 6 27464 B1.

[0003] Further cooking appliances are known from the documents WO 2012 062 875 A1 and JP S5 922 8391 A.

[0004] Document EP 1 938 092 B1 discloses a measuring device for a cooking appliance with a heating tube. The known cooking appliances comprise a housing, a cooking chamber arranged within the housing, a heating device for heating the cooking chamber in a heating mode, and a cooling device for cooling the cooking chamber in a cooling mode. This makes it possible, for example, to place food in the cooking chamber of the appliance well in advance of the cooking process. The food can then be cooled in the cooking chamber until the start of the cooking process. The cooking process can be started, for example, manually via an app or similar device from an external device such as a smartphone, or automatically via a timer on the cooking appliance.

[0005] The invention therefore addresses the problem of improving a cooking appliance with a cooling device.

[0006] According to the invention, this problem is solved by a cooking appliance with the features of claim 1.

[0007] Heat pipes are also known as heat tubes. The cooking appliance according to the invention can be designed as an oven, a steam cooker, a microwave oven, or a combination appliance with a plurality of different heating methods. Furthermore, the cooking appliance according to the invention can be designed as a household appliance or a commercial appliance, i.e., a cooking appliance for professional use. Advantageous embodiments and further developments of the invention are described in the following dependent claims.

[0008] The advantage achievable with the invention lies particularly in the fact that a cooking appliance with a cooling device is improved. Due to the design of the cooking appliance according to the invention, the cooking appliance can be realized in a particularly simple manner from a structural and manufacturing perspective. Furthermore, the operation of the cooking appliance in its cooling mode is significantly simplified. Thermal decoupling of the cooling device from the cooking chamber in the heating mode of the cooking appliance is also considerably facilitated by the invention.

[0009] In principle, the cooking device according to the invention can be freely selected within wide suitable limits with regard to type, function, material and dimensions. See, for example, the above descriptions of the cooking device according to the invention.

[0010] An advantageous further development of the cooking appliance according to the invention provides that thermal insulation surrounding the heat pipe is arranged in the housing between the evaporator section and the condenser section. In this way, the thermal decoupling of the condenser section of the cooling device from the cooking chamber of the cooking appliance is further improved.

[0011] A further advantageous embodiment of the cooking appliance according to the invention provides that a cooking chamber rear wall is arranged in the housing, wherein the cooking chamber rear wall separates the cooking chamber from an intermediate space, and wherein the evaporator section is arranged in the intermediate space. This means that the evaporator section, and thus the heating element, is not located directly in the cooking chamber, so that the cooking chamber's functionality is not impaired by the heating element. For example, this significantly simplifies manual cleaning of the cooking chamber. Furthermore, the heating element is thermally well connected to the cooking chamber by virtue of its arrangement in the aforementioned intermediate space.

[0012] Another advantageous embodiment of the cooking device according to the invention provides that the evaporator section is in thermal conduction connection with an evaporator heat sink of the cooling device, preferably that the evaporator heat sink substantially completely surrounds the evaporator section, and / or that the evaporator heat sink is arranged in a flow path of a circulating air fan that is flow-conducting and connected to the cooking chamber. In this way, the heat transfer from the cooking chamber to the evaporator section of the heat tube is significantly improved. This applies particularly to the preferred embodiments of this embodiment.

[0013] An alternative or additional advantageous embodiment of the cooking device according to the invention provides that the condenser section is in thermal conduction connection with a condenser cooling element of the cooling device, preferably that the condenser cooling element substantially completely surrounds the condenser section, and / or that the condenser cooling element is arranged in a flow path of a cooling fan of the cooking device. This significantly improves the heat transfer from the condenser section of the heat pipe to an environment in thermal conduction connection with the condenser section, analogous to the aforementioned embodiment. This applies particularly to the preferred embodiments of this embodiment.For example, heat transfer from the condenser section of the heat pipe via the condenser cooling element to a cooling airflow conveyed by the aforementioned cooling fan is significantly improved.

[0014] Accordingly, an advantageous embodiment of the cooking device according to the invention provides that the evaporator section is in thermal conduction connection with an evaporator cooling element of the cooling device, preferably that the evaporator cooling element substantially completely surrounds the evaporator section. According to the invention, the condenser section is in thermal conduction connection with a condenser cooling element of the cooling device.

[0015] According to an advantageous further development, the condenser cooling element essentially completely surrounds the condenser section.

[0016] A further advantageous embodiment of the cooking device according to the invention provides that the cooling device includes a Peltier element, wherein the Peltier element is arranged in thermal conductivity with the condenser section, preferably that the Peltier element is in thermal conductivity with the condenser heat sink. In this way, forced cooling, i.e., active cooling of the condenser section of the heat pipe, is enabled in a structurally and manufacturably simple manner, either as an alternative or in addition to the aforementioned cooling fan.

[0017] A particularly advantageous embodiment of the cooking appliance according to the invention provides that, in a typical operating position of the cooking appliance, the heating tube with its evaporator section projects from above into the cooking chamber or into the space behind the rear wall of the cooking chamber. This arrangement of the heating tube is particularly advantageous because, for example, a cooling channel through which a cooling airflow, conveyed by a cooling fan of the cooking appliance, is conveyed, is usually located above the cooking chamber in the housing of the cooking appliance. Accordingly, the condenser section of the heating tube can be easily connected to the aforementioned cooling channel and / or to the cooling airflow conveyed in this cooling channel. Furthermore, a simple thermal connection of the evaporator section of the heating tube to the cooking chamber is also possible.This applies in particular to the second alternative of this further training, since a circulating air blower, which is in flow communication with the cooking chamber, is usually arranged in the aforementioned intermediate space.

[0018] A further advantageous embodiment of the cooking device according to the invention provides that the cooling device has a thermally conductive connector for a thermally conductive connection between the heat pipe and the condenser cooling element, wherein the connector is in thermal conduction with the heat pipe essentially throughout the entire condenser section, preferably that the connector is designed and arranged such that heat conduction from the heat pipe to essentially the entire surface of the condenser cooling element facing the heat pipe is enabled. In this way, the heat transfer connection between the heat pipe on the one hand and the condenser cooling element on the other, namely the thermal conduction connection between the condenser section of the heat pipe and the condenser cooling element of the cooling device, is further improved.

[0019] An embodiment of the invention is shown schematically in the drawing and is described in more detail below. It shows the single figure. Figure 1 shows an embodiment of the cooking appliance according to the invention with the cooling device in a partial, cutaway side view.

[0020] In the Fig. 1 An embodiment of the cooking appliance according to the invention, including the cooling device, is shown purely as an example.

[0021] The cooking appliance 2 is designed as a household oven and comprises a housing 4, a cooking chamber 6 arranged in the housing 4, a heating device 8 designed as a radiant heating element for heating the cooking chamber 6 in a heating mode of the cooking appliance 2 and a cooling device 10 for cooling the cooking chamber 6 in a cooling mode of the cooking appliance 2.

[0022] According to the invention, the cooling device 10 has a heat pipe 12, wherein an evaporator section 14 of the heat pipe 12 faces the cooking chamber 6 and a condenser section 16 of the heat pipe 12 faces away from the cooking chamber 6 are arranged in the housing 4. The heat pipe 12 is designed here as a circular cylindrical metal tube approximately 20 cm long.

[0023] For the purpose of good thermal decoupling between the evaporator section 14, which is in heat transfer connection with the cooking chamber 6 on one side, and the condenser section 16 on the other side, a thermal insulation 18 surrounding the heat pipe 12 is arranged in the housing 4 between the evaporator section 14 and the condenser section 16.

[0024] Furthermore, a cooking chamber rear wall 20 is arranged in the housing 4, wherein the cooking chamber rear wall 20 separates the cooking chamber 6 from an intermediate space 22, and wherein the evaporator section 14 is arranged in the intermediate space 22. As is customary, a circulating fan 24 of the cooking appliance 2 is arranged in the intermediate space 22, wherein the circulating fan 24 is in flow-conducting contact with the cooking chamber 6 by means of holes arranged in the cooking chamber rear wall 20 and other openings of the cooking chamber 6 (not shown) such that air (not shown) from the cooking chamber 6 is drawn in by the circulating fan 24 through the holes in the cooking chamber rear wall 20 and is guided back into the cooking chamber 6 via the intermediate space 22 and the aforementioned other openings of the cooking chamber 6. Since the evaporator section 14 of the heat pipe 12, as shown in the Fig. 1 As can be seen, in the space 22, the air conveyed by means of the recirculating air blower 24 in the aforementioned manner enters into heat transfer contact with the evaporator section 14 of the heat pipe 12.

[0025] To intensify the aforementioned heat transfer connection from the air to the evaporator section 14, the evaporator section 14 is in thermal conduction connection with an evaporator cooling element 26 of the cooling device 10. In the present embodiment, the evaporator cooling element 26 substantially completely surrounds the evaporator section 14 of the heat pipe 12. The evaporator cooling element 26 is arranged in a flow path of the convection fan 24, namely the intermediate space 22, which is connected to the cooking chamber 6 in a flow-conducting manner. The flow path of the convection air conveyed by the convection fan 24, namely the air from the cooking chamber 6 already described above, is located in the Fig. 1 symbolized by an arrow 27.

[0026] To further increase the efficiency of cooling the cooking chamber 6 in the cooling mode of the cooking appliance 2, the condenser section 16 of the heat pipe 12 is additionally in thermal conduction connection with a condenser cooling element 28 of the cooling device 10, wherein the condenser cooling element 28 substantially completely surrounds the condenser section 16, and wherein the condenser cooling element 28 is arranged in a flow path of a cooling fan 30 of the cooking appliance 2. The flow path of cooling air conveyed by the cooling fan 30 is in the Fig. 1 symbolized by an arrow 31.

[0027] As from the Fig. 1 As can be seen, the heat pipe 12 is arranged such that the heat pipe 12 with its evaporator section 14 is in a position in the Fig. 1 In the depicted position of use of the cooking appliance 2, it projects from above into the space 22 located behind the rear wall 20 of the cooking chamber.

[0028] As furthermore from the Fig. 1 As can be seen, the cooling device 10 has a Peltier element 32 in addition to the cooling fan 30, wherein the Peltier element 32 is in thermal conduction connection with the condenser section 16 on the one hand and in thermal conduction connection with the condenser cooling element 28 on the other.

[0029] The cooling device 10 further comprises a thermally conductive connector 34 for a thermally conductive connection between the heat pipe 12 and the condenser cooling element 28, wherein the connector 34 is in thermal conductivity with the heat pipe 12 substantially throughout the entire condenser section 16, and wherein the connector 34 is designed and arranged such that heat conduction from the heat pipe 12 to substantially the entire surface 36 of the condenser cooling element 28 facing the heat pipe 12 is enabled. In the present embodiment, the aforementioned connector 34 is designed as a copper cone with a circular cylindrical opening corresponding to the heat pipe 12, in which the heat pipe 12 is thermally received.

[0030] Thus, in the present embodiment, the cooling device comprises the heat pipe 12, wherein in a Fig. 1 In the illustrated installation position of the cooling device 10, the evaporator section 14 of the heat pipe 12 faces the cooking chamber 6 and the condenser section 16 of the heat pipe 12 faces away from the cooking chamber 6 in the housing 4. Furthermore, the cooling device 10 comprises the evaporator cooling element 26 and the condenser cooling element 28, as well as the associated fans, namely the circulating air fan 24 and the cooling air fan 30, and also the Peltier element 32 and the connector 34.

[0031] The following describes the functioning of the cooking device according to the invention, based on the present embodiment and the Fig. 1 explained in more detail.

[0032] According to the invention, it is possible, for example, to place food (not shown) in the cooking chamber 6 of the cooking appliance 2 for a considerable time before the cooking process begins. The food can then be cooled in the cooking chamber 6 by means of the cooling device 10 until the start of the aforementioned cooking process. The cooking process can be started, for example, manually via an app or the like from an external device, such as a smartphone (not shown), or automatically via a timer on the cooking appliance 2.

[0033] Operating the cooking appliance 2 in its heating mode, in which the cooking chamber 6 of the cooking appliance 2 is heated, for example, by means of the heating device 8 designed as a radiant heating element and the circulating fan 24 in a so-called circulating air operation, corresponds to the state of the art and will not be explained further here.

[0034] The cooling of the cooking chamber 6 by means of the cooling device 10 in the cooling mode of the cooking appliance 2, for example in the application mentioned above as an example, is carried out as follows: In the present embodiment, the heat pipe 12 is used to cool the cooking chamber 6 to a temperature of approximately 5°C. Water 38, for example, is filled into the heat pipe 12. For the heat pipe 12 to function, the temperature in the condenser section 16, where the water 38 condenses, must be correspondingly lower. However, the temperature should be higher than 0°C to prevent the water 38 from freezing. If the water 38 freezes, the return flow from the condenser section 16 down to the evaporator section 14 no longer functions. Therefore, in the following example, the temperature in the condenser section 16 is set to 1°C. This corresponds to a holding phase once the cooking chamber 6 has already been cooled.During the start-up phase, temperatures are higher, typically 20°C to 25°C, i.e., room temperature. In a warm summer, perhaps even 40°C. For the sake of simplicity, a safety margin of 50°C is used here. Even under these conditions, a minimal residue of liquid water 38 should still be present in the lower section of the heat pipe 12, i.e., in the evaporator section 14.

[0035] The previously described design of the heat pipe 12, with its vertically arranged tube closed at both ends and the small amount of liquid, preferably water 38, leads to the following operating conditions. The pressure in the tube is reduced because the heat pipe 12 contains neither air nor other gases, but only vapor, namely water vapor, corresponding to the vapor pressure of the liquid, namely water 38. If the upper section, i.e., the condenser section 16, is colder than the lower section, i.e., the evaporator section 14, water vapor condenses to water 38 at the top and transfers the heat of condensation at the evaporator section 14 via the connector 34, the Peltier element 32, and the surface 36 to the condenser cooling element 28 on the one hand and to the Peltier element 32 on the other. Since this reduces the pressure in the heat pipe 12, water 38 can evaporate. The heat of vaporization is extracted from the water 38.This is a continuous process, as the condensed water 38 flows back downwards. The relatively high heat of vaporization of water 38 is transported, so the heat transfer via the heat pipe 12 is quite high.

[0036] The heat pipe 12 is connected at the top to the condenser cooling element 28, which is in operative communication with the cooling fan 30 and the Peltier element 32, by means of the connector 34, so that the heat of condensation can be dissipated to maintain, for example, a temperature of 1°C at the condenser section 16. Then, at the evaporator section 14 below, the water 38 can evaporate, for example, at 5°C. The pressure in the heat pipe, i.e., in the heat pipe 12, is then 8.7 mbar.

[0037] The 20 cm long heat pipe 12, for example, has a free internal cross-section of 1 cm². Accordingly, the heat pipe 12 has a volume of 20 cm³ or 0.02 l. At 50°C, the water 38 has a vapor pressure of 123 mbar and a density of 0.083 g / l. With a volume of 0.02 l, the amount of water in the heat pipe 12 is 1.66 mg. The heat pipe 12 with this amount of water contains water 38 at the evaporator section 14 and water vapor at the condenser section 16 at temperatures below 50°C and functions as a heat pipe, i.e. as heat pipe 12, when the temperature at the condenser section 16 becomes colder than 50°C due to the cooling of the condenser section 16 explained above and the water vapor condenses there, flows downwards and evaporates again in the evaporator section 14, as long as it is warmer in the evaporator section 14 than in the condenser section 16.At temperatures above 50°C at the evaporator section 14, this heat pipe 12 no longer functions, as there is no longer any liquid water 38 in the heat pipe 12.

[0038] The following section briefly explains some considerations regarding the normal operation of the oven and a possible pyrolysis operation.

[0039] For simplicity, we assume that the entire heating tube 12 is at oven temperature, i.e., the temperature in the cooking chamber 6 of the cooking appliance 2. Within the closed volume of the heating tube 12, here 0.02 l, the pressure of the water vapor increases proportionally to the absolute temperature. At 50°C or 323 K, we have a pressure of 123 mbar; at 160°C or 433 K, the pressure would rise to 165 mbar; and during pyrolysis operation at 430°C or 703 K, it would rise to 268 mbar. This is the absolute pressure inside the heating tube 12; the outside pressure is atmospheric pressure of approximately 1000 mbar. Therefore, there is no problem with overpressure that the heating tube 12 would have to withstand.

[0040] The situation would be different if the heat pipe 12 were completely filled with water 38. Then, at 160°C, the pressure would already be 5 bar, and at 350°C, it would be 165 bar. Therefore, for example, in a compressor, the liquid-filled parts must not get too hot, even when the compressor is not running.

[0041] The invention is not limited to the present embodiment. For example, the cooking appliance according to the invention can be designed as an oven, a steam cooker, a microwave oven, or a combination appliance with a plurality of different heating methods. Furthermore, the cooking appliance according to the invention can be designed as a household appliance or a commercial appliance, i.e., a cooking appliance for professional use.

[0042] In particular, the invention is not limited to the design and manufacturing details of the exemplary embodiment. Accordingly, the cooling device and the cooking appliance according to the invention equipped with it can be freely selected within wide suitable limits. For example, instead of a vertical arrangement of the heat pipe in its installation position, i.e., as in the Fig. 1 As shown, an inclined arrangement of the heat pipe is also conceivable. The cooling elements of the cooling device, for example the evaporator cooling element and the condenser cooling element according to the present embodiment, can be freely selected within wide suitable limits with regard to type, function, material, dimensions, and arrangement. The person skilled in the art will design them according to the requirements of the individual case, for example, taking into account the respective installation conditions and available space.

Claims

1. Cooking appliance (2) comprising a housing (4), a cooking chamber (6) arranged in the housing (4), a heating device (8) for heating the cooking chamber (6) in a heating mode of the cooking appliance (2), and a cooling device (10) for cooling the cooking chamber (6) in a cooling mode of the cooking appliance (2), characterised in that the cooling device (10) has a heat pipe (12), there being arranged in the housing (4) an evaporator portion (14) of the heat pipe (12) facing the cooking chamber (6) and a condenser portion (16) of the heat pipe (12) facing away from the cooking chamber (6), the condenser portion (16) being thermally conductively connected to a condenser cooling element (28) of the cooling device (10).

2. Cooking appliance (2) according to claim 1, characterised in that thermal insulation (18) surrounding the heat pipe (12) is arranged in the housing (4), between the evaporator portion (14) and the condenser portion (16).

3. Cooking appliance (2) according to claim 1 or 2, characterised in that a cooking chamber rear wall (20) is arranged in the housing (4), the cooking chamber rear wall (20) separating the cooking chamber (6) from an intermediate chamber (22), and the evaporator portion (14) being arranged in the intermediate chamber (22).

4. Cooking appliance (2) according to any of claims 1 to 3, characterised in that the evaporator portion (14) is thermally conductively connected to an evaporator cooling element (26) of the cooling device (10), preferably in that the evaporator cooling element (26) substantially completely surrounds the evaporator portion (14), and / or in that the evaporator cooling element (26) is arranged in a flow path (27), connected to the cooking chamber (6) in a flow-conducting manner, of a circulating fan (24).

5. Cooking appliance (2) according to any of claims 1 to 4, characterised in that the condenser cooling element substantially completely surrounds the condenser portion, and / or in that the condenser cooling element (28) is arranged in a flow path (31) of a cooling fan (30) of the cooking appliance (2).

6. Cooking appliance (2) according to any of claims 1 to 5, characterised in that the cooling device (10) has a Peltier element (32), the Peltier element (32) being thermally conductively connected to the condenser portion (16), preferably in that the Peltier element (32) is thermally conductively connected to the condenser cooling element (28).

7. Cooking appliance (2) according to any of claims 1 to 6, characterised in that in a usage position of the cooking appliance (2) the evaporator portion (14) of the heat pipe (12) projects from above into the cooking chamber or into the intermediate chamber (22) arranged behind the cooking chamber rear wall (20).

8. Cooking appliance (2) according to any of claims 1 to 7, characterised in that the cooling device (10) has a thermally conductive connector (34) for thermally conductively connecting the heat pipe (12) and the condenser cooling element (28), the connector (34) being thermally conductively connected to the heat pipe (12) substantially throughout the entire condenser portion (16), preferably in that the connector (34) is designed and arranged in such a way that heat is able to be conducted from the heat pipe (12) to substantially an entire surface (36) of the condenser cooling element (28) facing the heat pipe (12).

9. Cooking appliance (2) according to claim 8, characterised in that the connector (34) is in the form of a copper cone with a circular cylindrical opening corresponding to the heat pipe (12) in which the heat pipe (12) is thermally conductively received.

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