Hot beverage preparation device with water heater

Abstract

The invention relates to a hot beverage preparation device, in particular a coffee machine, having a water heater for heating and storing hot water or hot steam for preparing a coffee beverage, the water heater having a cold water inlet, a storage container having a heating device, and a hot water and / or steam outlet, the storage container (11, 11 ') is designed as a pressure container in which hot water is stored at a temperature of more than 110 DEG C during operation, and the hot water outlet is connected to a metering valve (40) for dosing cold water in a metered manner in order to add cold water into the hot water during output in order to output mixed water at a temperature of less than 100 DEG C, the method is used for preparing beverages.

Description

[0001] The present invention relates to a hot beverage preparation device, in particular a coffee machine, which has a water heater for heating and storing hot water or hot steam for preparing hot beverages. The water heater has a cold water inlet, a storage container with a heating device, and a hot water or steam outlet.

[0002] In an automatic coffee machine, a water heater is usually used to store the hot water required for preparing beverages. The water heater stores hot water within a temperature range below 100 °C, usually around approximately 90 °C. Usually, there is even a separate water heater for hot water and steam. The waste heat that necessarily occurs when the water heater generates hot water must be dissipated, so that the device does not overheat internally. Excessively high temperatures inside the automatic coffee machine can lead to temporary failures of components, long-term failures due to premature aging, and fluctuations in product quality. Especially for very compact devices, when there is not enough space to dissipate the waste heat generated to the outside of the device, heat problems may occur. Usually, the automatic coffee machine must be actively cooled by a fan in order to dissipate the waste heat generated during the preparation of hot water.

[0003] A hot beverage preparation device with a water heater is known from US9877608B2. In this hot beverage preparation device, boiling water with a temperature exceeding 100 °C is stored as a heat transfer medium. A heat exchanger extends in the water heater and guides cold water through it. Here, the cold water is heated to approximately 93 °C. Then, cold water can be added to the heated but not yet boiling water in order to adjust the water temperature. Storing hot water as a heat transfer medium at a temperature exceeding 100 °C is very energy-consuming and generates waste heat.

[0004] Therefore, the object of the present invention is to provide a hot beverage preparation device that has improved temperature management and enables a very compact structure.

[0005] This object is achieved by the features of claim 1. Advantageous refinements are given in the dependent claims.

[0006] In a hot beverage preparation device of the type mentioned above, according to the setting of the present invention, hot water with a temperature higher than 110 °C is stored, and during the preparation of the beverage, the hot water is adjusted to a preparation temperature below 100 °C by adding cold water. For this purpose, the storage container of the water heater is designed as a pressure vessel, in which hot water is stored at a temperature higher than 100 °C during operation, and the hot water outlet is connected to a metering valve, which is used to meteredly add cold water so that cold water is added to the hot water during output, thereby outputting mixed water at a temperature below 100 °C for beverage preparation.

[0007] By incorporating cold water, the amount of hot water available for beverage preparation is increased, or the water heater can be made more compact when the amount of hot water for beverage preparation is the same.

[0008] Here, the storage temperature can be selected to be higher than 110 °C, preferably in the range of 110 °C to 180 °C, more preferably in the range of 120 °C to 140 °C.

[0009] In particular, it is provided that the mixed water can be supplied to the brewing group through a brewing valve to prepare freshly brewed coffee beverages.

[0010] Furthermore, the incorporation of cold water is preferably carried out in a regulated manner by designing the metering valve for incorporating cold water as an adjustable valve, in particular a proportional valve, and the beverage preparation device having a temperature sensor for determining the temperature of the mixed water and a controller for adjusting the temperature of the mixed water by controlling the metering valve. Thereby, the output temperature of the hot water can be adjusted to different values according to the desired beverage. For example, less cold water can be incorporated for espresso, and more cold water can be incorporated for preparing green tea.

[0011] A static mixer, in particular a helical mixer, can be provided between the metering valve and the temperature sensor for mixing the cold and hot water streams. This ensures rapid and thorough mixing of the water streams. Thereby, the temperature of the mixed water achieved after mixing can be directly measured as the regulated variable after mixing. This enables a particularly compact structure.

[0012] In a preferred refinement of the invention, it is provided that the storage container is at least partially provided with a vacuum insulation structure or surrounded by a vacuum insulation structure. Due to the higher storage temperature, the waste heat of a conventional water heater increases significantly. However, the vacuum insulation structure significantly reduces the waste heat, so that the device can still be constructed compactly despite the higher storage temperature and the allowable operating temperature inside the device is not exceeded.

[0013] By using vacuum insulation, the heat loss of the water heater can be significantly reduced compared to a normally insulated water heater. The lower waste heat has a beneficial effect on the quality, storability and grinding characteristics of fresh coffee beans, which are usually stored at the top of the device and are thus particularly affected by the rising waste heat. Due to the reduced waste heat, active cooling or ventilation of the device can be dispensed with, or at least the cooling power can be significantly reduced. Since the water heater with vacuum insulation has less waste heat, the energy consumption of the device is reduced, thereby improving the energy efficiency and reducing the operating costs and CO2 emissions.

[0014] Although the water heater using vacuum insulation here has particular advantages due to the higher storage temperature, in principle, a conventional water heater insulated in a traditional manner can also be used.

[0015] In the simplest case, the outer wall of the storage container can be designed at least partially as a double wall, so that a vacuum-insulated space is enclosed by the double-wall region of the outer wall. The water heater is thus constructed compactly and has less waste heat.

[0016] Alternatively, in order to implement the vacuum insulation structure, the storage container can be inserted into an outer casing that is at least partially double-walled, and a vacuum-insulated space is enclosed by the double-wall region of the outer casing. Thereby, a conventional water heater can be used, and in case of a malfunction, the conventional water heater can be removed from the vacuum-insulated outer casing for repair or replacement and can be replaced.

[0017] In both cases, the double-walled storage container or the double-walled outer casing can be provided with a non-vacuum-insulated lid, and electrical and / or hydraulic connectors are guided through the lid. Thereby, a conduction part can be realized in a simple manner without having to pass through the vacuum housing complexly. The non-vacuum-insulated lid can be provided in a conventional manner, for example, a heat-insulating structure made of heat-insulating material.

[0018] Within the scope of the present invention, a cooker for providing and storing steam can also be regarded as a water heater. The cooker contains a certain volume of steam under pressure and a certain volume of hot water that has not been evaporated under the existing temperature and pressure conditions during normal operation. Within the scope of the present invention, the water heater can also be used to provide hot water and steam simultaneously, and is provided with both a hot water outlet and a steam outlet.

[0019] The heating device of the water heater is preferably configured as a heating coil arranged inside the storage container. This realizes a particularly compact structure of the water heater. In particular, it can be set that the heating device is configured as a spiral tube heater in such a way that the heating coil extends inside a spiral heating tube, and the heating tube is preferably filled with magnesium oxide powder for electrical insulation of the heating coil.

[0020] Within the scope of the present invention, there is not only one vacuum-insulated water heater, but multiple water heaters. Among these water heaters, for example, one water heater is set for generating steam, another water heater is set for generating hot water, and these two water heaters are respectively provided with a vacuum insulation structure or surrounded by a vacuum insulation structure. It can also be set to use more than two water heaters, for example, in order to realize parallel extraction of two beverages.

[0021] Other advantages and design options of the present invention are obtained from the following description of the embodiments with reference to the accompanying drawings.

[0022] Wherein:

[0023] Figure 1Shows a first embodiment of a vacuum-insulated water heater,

[0024] Figure 2 Shows an embodiment of a water heater enclosed in a vacuum-insulated outer jacket,

[0025] Figure 3 Shows a water circuit diagram of a hot beverage preparation device having two vacuum-insulated water heaters, one for supplying hot water and one for supplying steam,

[0026] Figure 4 The time curve of the hot water temperature inside the water heater is shown by a line graph, and the detection result of the cooling curve is shown to be used for evaluating the quality of the vacuum insulation, and

[0027] Figure 5 Shows a water circuit diagram of a hot beverage preparation device according to another embodiment, in which a static mixer is additionally provided for mixing the cold water supplied via a mixing valve with the hot water extracted from the water heater.

[0028] In Figure 1 A cross-sectional view shows a water heater 10 used in a hot beverage preparation device, such as a coffee machine. The water heater 10 includes a storage container 11, which is designed to have a double wall in the lower region and has an inner outer wall 11a and an outer outer wall 11b. A gap space 12 is provided between the inner outer wall 11a and the outer outer wall 11b, and the gap space 12 is evacuated so that the outer walls 11a, 11b have a vacuum insulation structure. In the upper region, the water heater 10 is provided with a lid 13 designed to be only a single wall, and electrical and hydraulic conduction parts extend through the lid 13. A spiral tube heating element 14 is provided inside the storage container 10. The tube heating element 14 has two electrical connectors 14a, 14b, and the electrical connectors are led outwards through corresponding conduction parts in the lid 13. In addition, the water heater has a plurality of free conduction parts 15, 16, 17. Through these conduction parts, feed lines and discharge lines, as well as measuring instruments, such as a pressure gauge or a thermometer, can be connected. An evacuation valve 18 is provided in the lower region, and the gap space 12 between the inner and outer outer walls 11a, 11b is evacuated through the evacuation valve.

[0029] In Figure 2A second embodiment of the vacuum-insulated water heater 10 is also shown in partial cross-section. The water heater 10 here includes a storage container 11', which is designed in a conventional manner as a single-walled one. A helical tubular heating element 14 is provided in the storage container. The tubular heating element has two electrical connectors 14a, 14b, which are led outwards through a conduction part provided in the upper region of the storage container 11'. Other conduction parts are used to connect the feed line and the discharge line and, if necessary, also measuring instruments. In these other conduction parts, only one conduction part 15 can be seen in Figure 2 In

[0030] The storage container 11' is located inside a vacuum-insulated outer casing 20, the lower region of which is designed as a double-walled one with an inner outer wall 21a and an outer outer wall 21b. There is a gap space 22 between the inner outer wall 21a and the outer outer wall 21b, and the gap space 22 has been evacuated through an evacuation valve 28. In the upper region, the outer casing 20 is closed by means of a non-vacuum-insulated lid 23, and electrical and hydraulic conduction parts extend through the lid 23. The lid 23 can be insulated in a conventional manner with heat-insulating materials (such as needle felt made of artificial fibers, silicone foam, glass wool or similar materials). The lid 23 can be opened for installing or removing the water heater 10 or for repairing the water heater 10, so that the water heater 10 can be maintained and replaced without the vacuum-insulated outer casing 20.

[0031] In Figure 3 A so-called water circuit diagram of a coffee machine with two water heaters 10a, 10b is shown. The two water heaters are provided with or surrounded by a vacuum-insulated structure as described above. The water heater 10a is used to prepare and store hot water for preparing beverages, and the water heater 10b is used to prepare and store steam for milk frothing, and includes a water volume and a steam volume, and the water volume and the steam volume are in thermal equilibrium.

[0032] One input side of the water inlet is connected to the interface of a water supply device or a water container. At this water inlet, there is a component 30, which has a water filter 31, a shut-off valve 32, two check valves 33 in series, a water pump 34 and a temperature sensor 35. Cold water reaches the inlet of the water heater 10a from the water pump 34 via a flow meter 36 and another check valve 37.

[0033] Heat water in the water heater 10a to a storage temperature of 120°C to 140°C. The temperature in the water heater 10a can be determined by the temperature sensor 39, and the temperature can be adjusted by controlling the heating device 14 of the water heater 10a. The overpressure valve 38 at the water heater inlet guides water from the water heater 10a to the discharge outlet in case of overpressure. The hot water outlet of the water heater 10a leads to two valve groups 41, 42. A proportional valve 40 is provided between the inlet and outlet of the water heater 10a, and cold water can be mixed into the hot water from the water heater 10a by using the proportional valve. The water temperature of the mixed water can be measured by the temperature sensor 44, and the water temperature of the mixed water can be adjusted by correspondingly controlling the proportional valve 40.

[0034] The mixing of hot water and cold water supplied via the proportional valve 40 can be carried out in the hose line after the cold water and hot water converge. In order to achieve the mixing of these two water flows as quickly as possible, a static mixer 42, such as a spiral mixer, can be additionally provided, and the mixer mixes these two water flows sufficiently. This is schematically shown in Figure 5 A spiral mixer is a type of static mixer in which a plurality of 180° helices are arranged in sequence, each being offset by 90° from the previous one, in a tubular housing. In addition, the successive helices have opposite rotational directions. Each helix divides the flowing liquid stream into two sub-streams. The sub-streams are again divided into two sub-streams at each transition to the corresponding subsequent helix and respectively converge with the sub-streams from the previous helix. In this way, sufficient mixing of the liquid stream is achieved.

[0035] The hot water outlet of the water heater 10a is connected to two valve groups 41, 42. Hot water for making tea can be output through the valve 41a, and the water heater 10b for making steam can be filled through the valve 41b. The valve 41c is not used in this embodiment and is available for other optional functions. The inlet of the valve 41d is connected to the outlet of the valve 41b and also leads to the hot water outlet, so that hot water and steam can be output simultaneously. Hot water that can be used for instant beverages or for mixing into coffee beverages, for example, can be output at the beverage outlet head 45 through the valve 42a. In addition, the outlet line from the brewing group 52 to the outlet head 45 can be flushed through the valve 42a. The valve 42b is not used in this embodiment and can be used for, for example, the "instant beverage" option.

[0036] Furthermore, a pipeline leads from the hot water outlet of the water heater 10a to the brewing valve 51 in the brewing unit 50. The brewing unit 50 includes a brewing group 52 having a movable brewing piston that closes a cylindrical brewing chamber. The brewing chamber can be automatically filled with freshly ground coffee powder by two separate grinding mechanisms 53a, 53b for different coffee types. When the brewing valve 51 is opened, hot water from the water heater 10a can flow through the brewing group 52 under the pressure of the water pump 34. An adjustable backpressure valve 54 is provided at the outlet of the brewing group 52, and the flow rate of the freshly brewed coffee beverage can be adjusted through the backpressure valve. The freshly brewed coffee flows from here to the output head 45 of the coffee machine.

[0037] Steam for heating and, if necessary, milk frothing is provided by the water heater 10b. The steam pipeline 61 leading to the steam lance 62 can be released through a valve group 60 having two parallel valves 60a, 60b. Air for milk frothing can be added by an air pump 63 and a check valve 64 when steam is output. In addition, a temperature sensor 65 can be provided on the steam lance 62 for measuring the temperature of the milk heated or frothed by the steam.

[0038] Furthermore, an overpressure valve 66, a pressure gauge 67, and a temperature sensor 68 are provided at the steam outlet of the water heater 10b. The temperature inside the water heater 10b can be monitored by the temperature sensor 69 and adjusted by correspondingly controlling the heating device 14.

[0039] A significant reduction in the waste heat of the heating device is achieved through the vacuum insulation structure of the water heaters 10a, 10b, so that the device can be constructed particularly compactly without thermal problems occurring. In addition, the vacuum insulation structure enables hot water to be stored at a higher storage temperature, so that a larger volume of water can be provided by mixing in cold water at the time of output. Thereby, the water heater 10a can be designed to be more compact, or a larger quantity of hot beverages can be prepared before the hot water has to be reheated.

[0040] The vacuum in the double-wall region of the vacuum insulation structure is typically, for example, below one millibar, preferably even below one microbar, and more preferably even below 0.1 μbar. In addition, in order to maintain the long-term stability of the vacuum, a so-called getter material can even be introduced into the vacuum to absorb gas in the presence of minimal leak-tightness and when gas is evolved from the material. A getter or gas absorber is a chemically reactive material that is used to maintain the vacuum for as long as possible. On the surface of the getter, gas molecules form compounds (oxidation) with the atoms of the getter material or the gas molecules are fixed by adsorption. In this way, the gas molecules are "trapped". Some metals, such as barium alloys, aluminum alloys or magnesium alloys, are suitable for use as getters, and if necessary, the metal can be heated after evacuation to evaporate the getter metal.

[0041] In addition, a reflective film can be introduced into the evacuated gap spaces 12, 22, which further reduces the waste heat of the water heaters 10, 10'.

[0042] As already explained, the vacuum insulation structure is part of the water heater and is mechanically connected to the water heater or forms a unit therewith, or the vacuum insulation structure can be designed as a separate component and the water heater can be enclosed in the component.

[0043] In Figure 4 the plotted lines shown show the test results of the cooling curve that can be used to evaluate the quality of the vacuum insulation structure, and the plotted lines show the time curve of the hot water temperature inside the water heater.

[0044] For this purpose, additional software functions can also be implemented by a controller for simultaneously controlling the heating device 14 and adjusting the hot water temperature in the water heaters 10, 10'. The software functions determine the insulation quality based on the cooling curve of the water heaters 10, 10', which can be measured by means of temperature sensors 39, 69. Thereby, the vacuum insulation can be checked. When it is confirmed that the cooling is too fast, it can be concluded that the vacuum of the vacuum insulation structure is defective and a corresponding error message is generated to replace or repair the vacuum insulation structure. This information can be queried either on the device itself or through remote maintenance.

[0045] In Figure 4In it, the temperature curve measured by the water heater 10b or the temperature sensors 39 or 69 of the 10b is plotted against time t. After the heating device is turned off, the temperature slowly decreases all the way to the lower regulation threshold. If this lower regulation threshold is reached, the heating device 14 is switched on for a heating period H. Thereby, the temperature rises again all the way to the upper regulation threshold or the desired temperature in the water heater. Now, wait for a predefined period of 60 seconds until the heating device 14 has released all the heating energy to the hot water. Now measure the following time period Δt, during which the temperature has decreased by a predefined temperature difference ΔT which is 1 °C in this embodiment. This cooling time is a measure of the quality of the heat insulation characteristics of the vacuum insulation structure. If the 1° cooling time drops below the minimum value representing the integrity of the vacuum insulation structure, an error message is generated and reported to the monitoring center via the data connection, that is, there may be a defect in the vacuum insulation structure of the water heater 10a or 10b and it must be inspected. Thereby, the vacuum insulation can be judged and confirmed in a simple manner whether there is a defect in the vacuum. Of course, it is also possible to detect the time period between the two heating periods H as the cooling time, that is, the time until the temperature drops to the lower regulation threshold and the heating device 14 is reactivated.

Claims

1. Hot beverage preparation device, said hot beverage preparation device having at least one water heater (10, 10a, 10b) for heating and storing hot water for preparing hot beverages, said water heater (10, 10a, 10b) having a cold water inlet, a storage container (11, 11') with a heating device (14), and a hot water outlet. It is characterized in that said storage container (11, 11') is designed as a pressure vessel, in the course of operation, hot water is stored in said pressure vessel at a temperature above 110 °C, and said hot water outlet is connected to a metering valve (40), said metering valve (40) being used to meteredly incorporate cold water, so as to incorporate cold water into the hot water with a temperature above 110 °C during output, thereby outputting mixed water at a temperature below 100 °C for preparing beverages.

2. The hot beverage preparation device according to claim 1, wherein, said storage container (11, 11') is configured to store hot water in the range of 110 °C to 180 °C, especially in the range of 120 °C to 140 °C, during operation.

3. The hot beverage preparation device according to any one of claims 1 or 2, wherein, Said mixed water can be supplied to a brewing group (52) through a brewing valve (51) to prepare freshly brewed coffee beverages.

4. The hot beverage preparation device according to any one of the preceding claims, wherein, Said metering valve (40) for incorporating cold water is designed as an adjustable valve, especially a proportional valve, and said hot beverage preparation device has a temperature sensor (44) for determining the temperature of the mixed water and a controller for adjusting the temperature of the mixed water by controlling said metering valve (40).

5. The hot beverage preparation device according to any one of the preceding claims, wherein, A static mixer, especially a helical mixer, is provided between said metering valve (40) and said temperature sensor (44) for mixing cold and hot water flows.

6. The hot beverage preparation device according to any one of the preceding claims, wherein, Said storage container (11, 11') is at least partially provided with a vacuum insulation structure (12, 22) or surrounded by a vacuum insulation structure (11, 22).

7. The hot beverage preparation device according to claim 6, wherein, In order to implement said vacuum insulation structure, the outer shell (11a, 11b) of said storage container is at least partially designed as a double wall, and the double wall area of said outer shell encloses a vacuum evacuation space (12).

8. The hot beverage preparation device according to claim 6, wherein, In order to implement said vacuum insulation structure, said storage container (11') is installed in an outer jacket (20) that is at least partially double walled, and the double wall area (21a, 21b) of said outer jacket encloses a vacuum evacuation space (22).

9. The hot beverage preparation device according to claim 7 or 8, wherein, Said double walled storage container (20) or said double walled outer jacket (11a, 11b) has a non-vacuum insulated lid (13, 23), and electrical and / or hydraulic connectors (14a, 14b, 15, 16, 17) are led through said lid.

10. The hot beverage preparation device according to any one of the preceding claims, wherein, Said heating device (14) is configured as a heating coil provided inside said storage container (11, 11').

11. The hot beverage preparation device according to claim 10, wherein, Said heating coil extends inside a helical heating tube (14), preferably, said heating tube (14) is filled with magnesium oxide powder for electrical insulation of the heating coil.

12. The hot beverage preparation device according to any one of the above claims, the hot beverage preparation device having a first water heater set to generate hot water and a second water heater (10a, 10b) set to generate steam, both the first and second water heaters being provided with a vacuum insulation structure (12, 22) or surrounded by the vacuum insulation structure (12, 22).

13. The hot beverage preparation device according to claim 7 or 8, wherein, Introduce a getter material into the evacuated space (12, 22).

14. The hot beverage preparation device according to claim 7 or 8, wherein, Introduce a reflective film into the evacuated space (12, 22).

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