Improved system for heating water for a coffee machine and method of heating water in a coffee machine

Abstract

An espresso coffee machine is described, the machine comprises: a pump (1) configured to receive water at a first pressure (p1) and to emit water at a second pressure (p2); a limescale trap (2) configured to receive, at a limescale trap inlet, water at the second pressure (p2), at a second temperature (t2) and at a second hardness (d2) and to provide, at a limescale trap outlet, a fluid at a third hardness (d3) which is less than the second hardness (d2); and a throughflow heating device (3) configured to receive, at the inlet, the fluid from the limescale trap (2) and to supply, at the outlet, a fluid at a fourth temperature (t4), which is substantially equal to a temperature of use for extracting an espresso coffee or for frothing a beverage by emitting steam, wherein the limescale trap (2) comprises a heating boiler configured to provide, at a heating boiler outlet, a fluid at a third temperature (t3), which is higher than the second temperature (t2).

Description

[0001] Improved system for heating water for a coffee machine and method of heating water in a coffee machine

[0002] TECHNICAL SECTOR

[0003] The present invention relates generally to coffee machines and in particular to espresso coffee machines.

[0004] More particularly, the present invention relates to a novel system for heating the water for a coffee machine and to a method for heating the water in a coffee machine.

[0005] PRIOR ART

[0006] Coffee machines used for the preparation of beverages using ground coffee are known. Also known are coffee machines configured to perform the frothing of milk or alternative products.

[0007] The preparation of beverages with ground coffee requires water at a temperature generally higher than 85°C; the preparation of beverages with frothed milk requires the blowing-in of water vapour at a temperature above 100°C.

[0008] In order to be able to provide water and water vapour at these temperatures, the coffee machines are generally equipped with one or more boilers, containing the water or the stationary two-phase fluid pending removal by the user.

[0009] This system offers the advantage that the fluid needed for the conditions of use is immediately available, even through the quantity which will be actually used is not known beforehand. For example, in a coffee machine, a boiler with hot water or a saturated steam boiler could remain full for a long time if there does not exist the need to dispense a coffee or froth the milk.

[0010] If, instead, the user decides to switch off the machine in order not to waste energy, it is necessary to wait a certain amount of time until the boilers reach the necessary temperature.

[0011] Moreover, once the temperature has been reached, the boilers disperse a significant amount of heat into the external environment, increasing therefore the energy consumption of the machine. US 11 ,439,271 discloses a coffee machine for preparation of a hot beverage.

[0012] EP 3,932,270 discloses a hydraulic system for a hot beverage vending machine.

[0013] US 11 ,147,414 discloses a coffee machine with sensors.

[0014] JP 7,316,848 discloses a hot beverage preparation apparatus comprising a flow heater on which limescale is formed less quickly.

[0015] SUMMARY OF THE INVENTION

[0016] The Applicant has defined the aim of improving the known solutions, mainly in order to reduce the energy consumption of coffee machines and reduce the problems caused by limescale deposition.

[0017] According to the present invention a hybrid system for reaching the desired temperature for the working fluid, whether it be water or steam, is provided. The system comprises a first-stage boiler set to provide a limescale trap. The first-stage boiler is configured to keep a fluid (during normal operation) at a temperature equal to or less than the final temperature of use of the fluid.

[0018] Then, the fluid is heated or kept at the temperature of use by means of a throughflow heating system, only when required by the user.

[0019] Basically, the heating takes place in two stages, a first stage inside the boiler and a second stage when crossing a throughflow heating system.

[0020] According to a first aspect, the present invention provides an espresso coffee machine, comprising: a pump configured to receive water at a first pressure and to emit water at a second pressure; a limescale trap configured to receive, at a limescale trap inlet, water at the second pressure, at a second temperature and at a second hardness and to provide, at a limescale trap outlet, a fluid at a third hardness which is less than the second hardness; and a throughflow heating device configured to receive, at the inlet, the fluid from the limescale trap and to supply, at the outlet, a fluid at a fourth temperature, which is substantially equal to a temperature of use for extracting an espresso coffee or for frothing a beverage by emitting steam, wherein the limescale trap comprises a heating boiler configured to provide, at a heating boiler outlet, a fluid at a third temperature, which is higher than the second temperature.

[0021] According to embodiments, the third temperature at the heating boiler outlet is lower than 99 °C, for instance is higher than 95 °C and lower than 99 °C.

[0022] Advantageously, the boiler promotes the precipitation of the salts and minerals present in the water.

[0023] According to embodiments, the throughflow heating device comprises a heating body and a fluid throughflow tube which is at least partially in contact with the heating body, wherein the fluid throughflow tube comprises an inlet for the fluid at the third temperature and an outlet for the fluid at the fourth temperature.

[0024] According to embodiments, the heating body comprises a cartridge resistance and wherein the fluid throughflow tube is a metal tube, for example made of copper, wrapped around the external surface of the heating body.

[0025] According to embodiments, the heating body comprises a conductive wall and a film resistance, wherein the fluid throughflow tube is mounted on the conductive wall which, in contact with the film resistance, heats up.

[0026] According to embodiments, the heating body comprises a cartridge resistance and wherein the fluid throughflow tube is a metal tube, for example made of copper, wrapped around the external surface of the heating body.

[0027] According to embodiments, the heating body comprises a conductive wall and a film resistance, wherein the fluid throughflow tube is mounted on the conductive wall which, in contact with the film resistance, heats up.

[0028] According to embodiments, the fluid at the fourth temperature is water or water vapour, for example dry steam.

[0029] According to another aspect, the present invention relates to a system for heating a fluid to a temperature of use for dispensing espresso coffee in an espresso coffee machine, comprising a boiler configured to receive, at the inlet, water at a second pressure, at a second temperature and at a second hardness and to provide, at the outlet, a fluid at a third temperature and at a third hardness, higher than the second temperature and less than the second hardness, respectively; and a throughflow heating device configured to receive, at the inlet, the fluid at the third temperature and to supply, at the outlet, a fluid at a fourth temperature, higher than or equal to the third temperature, wherein the fourth temperature is substantially equal to a temperature of use for extracting an espresso coffee or for frothing a beverage by emitting steam.

[0030] According to another aspect, the present invention relates to a method of providing a fluid at a temperature of use for dispensing espresso coffee or for frothing a liquid for the preparation of a beverage, for example a coffeebased beverage, comprising the steps of: receiving water at a first pressure and emitting water at a second pressure; providing a first heating stage for heating the water at the second pressure, at a second temperature and at a second hardness and for supplying, at the outlet, a fluid at a third temperature and at a third hardness, wherein the third temperature is higher than the second temperature and wherein the third hardness is less than the second hardness; and providing a second heating stage configured to receive, at the inlet, the fluid at the third temperature and to supply, at the outlet, a fluid at a fourth temperature, higher than or equal to the third temperature, wherein the fourth temperature is substantially equal to the temperature of use.

[0031] According to another aspect, the present invention relates to a method of providing a fluid at a temperature of use for dispensing espresso coffee or for frothing a liquid for the preparation of a beverage, for example a coffeebased beverage, comprising the steps of: a) trapping limescale from water comprising: i. receiving water at a second pressure, at a second temperature, and at a second hardness; and ii. heating the water to a third temperature, which is higher than the second temperature, thereby causing precipitation of minerals and supplying a fluid at a third hardness which is less than the second hardness; and b) performing a further heating on the fluid heated at step a), said further heating comprising heating the fluid from the third temperature to a fourth temperature, which is substantially equal to a temperature of use for extracting an espresso coffee or for frothing a beverage by emitting steam.

[0032] The further heating stage could comprise heating the fluid from the third temperature to the fourth temperature by a throughflow heating device.

[0033] The third temperature could be lower than 99 °C.

[0034] The third temperature could be higher than 95 °C and lower than 99 °C.

[0035] The throughflow heating device could comprise a fluid throughflow tube and a heating body.

[0036] The heating body could comprise a cartridge resistance or a film resistance.

[0037] The method could comprise receiving water at a first pressure at a pump input and emitting water at a second pressure at a pump output, the water at the pump output being at the second temperature and at the second hardness.

[0038] BRIEF DESCRIPTION OF THE FIGURES

[0039] The present invention will become fully clear from the following detailed description, provided by way of a non-limiting example, to be read with reference to the accompanying drawings, in which:

[0040] Fig. 1 is a block diagram of the heating system according to the present invention;

[0041] Figs. 2 and 2A show an embodiment of the present invention relating to the steam generation;

[0042] Fig. 3 shows an embodiment of the present invention relating to the coffee extraction; and Fig. 4 and Fig. 4A show an alternative to the throughflow heating device according to the embodiment of Figures 2 and 2A.

[0043] DETAILED DESCRIPTION

[0044] As is known, in an espresso coffee machine, hot water under pressure is made to pass through a pressed puck of coffee powder contained inside a filter. The water used is drawn from a tank or is taken directly from the water mains. The water may be treated and / or filtered.

[0045] In order to increase the pressure of the water typically a pump is used. In other coffee machines (lever or piston operated machines), the energy of a spring is used, the spring being for example compressed by the user when operating a lever.

[0046] For extraction, the temperature of the water which crosses the coffee puck must be at a high temperature, typically higher than about 85°C.

[0047] According to the present invention a two-stage system for reaching the desired temperatures for the working fluid, whether it be water or steam, is provided. The first stage comprises trapping limescale. The system comprises a first-stage boiler set to operate at a temperature equal to or lower than the temperature of use of the fluid.

[0048] Then, the fluid is heated to the temperature of use by means of a throughflow heating device. Heating to the temperature of use often takes place only at the time when needed by the user.

[0049] Fig. 1 shows in schematic form a hydraulic circuit which employs the concept of the present invention. In particular, in the hydraulic circuit shown in Fig. 1 , the fluid obtained is steam or hot water, for extraction of the coffee or preparation of an infusion, and typically it is used to froth the milk or another similar liquid, for example in order to make a coffee-based beverage. In Fig. 1 the water is obtained from a water tank WT at room temperature, but could also come from the mains supply.

[0050] Unheated water is introduced (IN) at a relatively low pressure p1 (for example 3 bar, or in any case at the pressure of the mains water supply) into a pump 1. The water entering the pump is at a first temperature t1 , which is typically the temperature of the mains water. Said temperature is typically about 14 - 15°C and in any case typically between about 10°C and 20°C. The water entering the pump 1 has a first hardness d1 , typically greater than 10°f. In the present description and claims, the hardness is expressed in French degrees (°f), where one degree represents 10 mg of calcium carbonate (CaCO3) per litre of water.

[0051] Water leaves the pump 1 under pressure (at a pressure p2) and is introduced into a boiler 2. The temperature t2 of the water leaving the pump 1 (and therefore entering the boiler 2) is substantially equal to the temperature of the water t1 entering the pump 1 since it has not been heated. The hardness d2 of the water leaving the pump 1 is substantially equal to the hardness of the water d1 entering the pump 1.

[0052] The boiler 2 is configured to heat the water, namely to increase the temperature of the water t2 to t3 and keep the water substantially at the temperature t3 inside the boiler 2. The temperature t3 is lower than 100°C, for example t3 may be between about 55°C and 99°C. The boiler 2 is configured to promote the precipitation of the salts and minerals present in the water. The hardness of the water d3 leaving the boiler 2 is less than the hardness of the water d2 entering the boiler 2. The hardness of the water d3 leaving the boiler 2 is typically between 0°f and 10°f.

[0053] A throughflow heating device 3 is arranged downstream of the boiler 2. A steam wand 4 may be provided downstream of the throughflow heating device 3 in order to dispense steam into a container containing a liquid to be frothed (for example milk) and prepare a coffee-based beverage.

[0054] A water dispensing unit 6 for extracting espresso coffee or other beverage may be provided downstream of the throughflow heating device 3.

[0055] Therefore, the fluid remains inside the boiler 2 until it is required by the user. When the user requires fluid at the temperature of use, for example requires steam in order to froth milk, the fluid passes from boiler 2 to the throughflow heating device 3, where its temperature increases (from t3) and reaches the temperature of use t4. The fluid increases its temperature as it passes through the throughflow heating device 3 since it comes into contact with a hot body 31 which transfers heat to it. In embodiments, the temperature of the water inside the boiler is substantially equal to the extraction temperature of the coffee or the dispensing temperature of the hot water for preparation of a tea or an infusion. Further heating of the fluid with respect to the temperature of the water inside the boiler could occur only when steam is dispensed in order to froth milk. Fig. 2 shows the throughflow heating device. The device 3 comprises a heating body 31 , for example a metal body, and a coil 32 at least partially making contact with the heating body 31. The throughflow heating device 3 is also shown in the cross-section of Fig. 2A.

[0056] According to embodiments, the heating body 31 is substantially cylindrical, for example has a circular cross-section. It may be made of a metallic material such as aluminium or aluminium alloy. A metal tube 32, for example made of copper, the surface of which is partially in contact with the external surface of the heating body 31 , is wrapped around the external surface of the heating body.

[0057] The fluid leaving the boiler 2 enters into the metal tube 32 wrapped around the heating body 31 at a third temperature t3 and exits the tube 32 at a fourth temperature t4, higher than the third temperature t3. The fourth temperature t4 is substantially the temperature of use, for example the temperature of the fluid needed to froth the milk.

[0058] The heating body 31 is heated by means of an electric current flow, as schematically indicated by the two cables 33 in Fig. 2A. For example, the heating body 31 could comprise a cartridge resistance, which optimizes the heat exchanges, allowing uniform heating. Moreover, a cartridge resistance allows heating of an extremely small mass using a specific amount of power and high temperatures. The hot water flow which is introduced (32-IN) into the tube 32 receives the heat provided by the resistance and undergoes an increase in temperature and a change in state from liquid to steam. In this way, by suitably determining the dimensions of the throughflow crosssections and the power used it is possible to obtain at the outlet (32-OUT) the fluid (for example dry steam) at the desired temperature of use.

[0059] The system according to the present invention reduces the energy consumption levels compared to the conventional solutions.

[0060] The operating temperature of the boiler 2 is lower than or equal to the temperature which would be obtained in the conventional system. This allows the consumption levels to be reduced during two working stages, i.e. the heating stage and the temperature maintenance stage.

[0061] Moreover, the reliability of the heating system is increased compared to the conventional throughflow heating solutions. In fact, the first stage boiler 2 allows the salts and minerals dissolved in the water to precipitate. If the boiler were not present, the salts and minerals would precipitate directly in the heat exchange zone, thus resulting in the entire machine becoming unusable within a very short period of time.

[0062] Figs. 4 and 4A show an alternative embodiment of the throughflow heating device 3 shown in Figs. 2 and 2A and Fig. 3. This embodiment comprises a conductive wall 34 (for example a metal plate) and a film resistance 35. In this embodiment, the fluid throughflow tube 32 is mounted on the conductive wall 34 which, making contact with the film resistance 35, heats up. In this way transfer of energy to the fluid which passes inside the tube 32 is obtained, providing always the steam as indicated in the first embodiment.

[0063] A single throughflow heating device or also a plurality of throughflow heating devices may be provided downstream of the first heating stage inside the boiler.

Claims

CLAIMS1 . An espresso coffee machine comprising: a pump (1 ) configured to receive water at a first pressure (p1 ) and to emit water at a second pressure (p2); a limescale trap (2) configured to receive, at a limescale trap inlet, water at the second pressure (p2), at a second temperature (t2) and at a second hardness (d2) and to provide, at a limescale trap outlet, a fluid at a third hardness (d3) which is less than the second hardness (d2); and a throughflow heating device (3) configured to receive, at the inlet, the fluid from the limescale trap (2) and to supply, at the outlet, a fluid at a fourth temperature (t4), which is substantially equal to a temperature of use for extracting an espresso coffee or for frothing a beverage by emitting steam, wherein the limescale trap (2) comprises a heating boiler (2) configured to provide, at a heating boiler outlet, a fluid at a third temperature (t3), which is higher than the second temperature (t2).

2. The espresso coffee machine according to claim 1 , wherein the third temperature (t3) at the heating boiler outlet is lower than 99 °C.

3. The espresso coffee machine according to claim 1 or 2, wherein the third temperature (t3) at the heating boiler outlet is higher than 95 °C and lower than 99 °C.

4. The espresso machine according to claim 1 or 2, wherein the throughflow heating device (3) comprises a heating body (31 , 35) and a fluid throughflow tube (32) which is at least partially in contact with the heating body (31 , 35), wherein the fluid throughflow tube (32) comprises an inlet (32- IN) for the fluid at the third temperature (t3) and an outlet (32-OUT) for the fluid at the fourth temperature (t4).

5. The espresso coffee machine according to claim 4, wherein the heating body comprises a cartridge resistance (31 ) and wherein the fluid throughflow tube (32) is a metal tube, for example made of copper, wrapped around the external surface of the heating body.

6. The espresso coffee machine according to claim 4, wherein the heating body comprises a conductive wall (34) and a film resistance (35),wherein the fluid throughflow tube (32) is mounted on the conductive wall which, in contact with the film resistance, heats up.

7. The espresso coffee machine according to any one of the preceding claims, wherein the fluid at the fourth temperature (t4) is water or water vapour, for example dry steam.

8. A method of providing a fluid at a temperature of use for dispensing espresso coffee or for frothing a liquid for the preparation of a beverage, for example a coffee-based beverage, comprising the steps of: a) trapping limescale from water comprising: i. receiving water at a second pressure (p2), at a second temperature(t2), and at a second hardness (d2); and ii. heating the water to a third temperature (t3), which is higher than the second temperature (t2), thereby causing precipitation of minerals and supplying a fluid at a third hardness (d3) which is less than the second hardness (d2); and b) performing a further heating on the fluid heated at step a), said further heating comprising heating the fluid from the third temperature (t3) to a fourth temperature (t4), which is substantially equal to a temperature of use for extracting an espresso coffee or for frothing a beverage by emitting steam.

9. The method according to claim 8, wherein the further heating stage comprises heating the fluid from the third temperature (t3) to the fourth temperature (t4) by a throughflow heating device (3).

10. The method according to claim 8 or 9, wherein the third temperature (t3) is lower than 99 °C.

11. The method according to claim 8, 9 or 10, wherein the third temperature (t3) is higher than 95 °C and lower than 99 °C.

12. The method according to claim 9, 10 or 11 , wherein the throughflow heating device (3) comprises a fluid throughflow tube (32) and a heating body (31 , 35).

13. The method according to claim 12, wherein the heating body comprises a cartridge resistance (31 ) or a film resistance (35).

14. The method according to any of claims 8-13, comprising receiving water at a first pressure (p1 ) at a pump input and emitting water at a second pressure (p2) at a pump output, the water at the pump output being at the second temperature (t2) and at the second hardness (d2).

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