Boiler for coffee machine and coffee machine

Abstract

A boiler for a coffee machine is described, said boiler comprising: a first hollow cylindrical body comprising an inlet end and an outlet end, configured to receive water at the inlet end and discharge water at the outlet end; a second hollow cylindrical body arranged radially external with respect to the first hollow cylindrical body, configured to receive water from the first hollow cylindrical body in proximity of its closed bottom and to discharge water at an open outlet end, wherein said closed bottom comprises a flow-diverting surface for directing the water flow between the external surface of the first hollow cylindrical body and the internal surface of the second hollow cylindrical body.

Description

[0001] Boiler for coffee machine and coffee machine

[0002] * * * * * * * * * * * * *

[0003] FIELD OF INVENTION

[0004] The present invention relates generally to the sector of coffee machines and in particular to the sector of espresso coffee machines.

[0005] More particularly, it relates to the mixing of water inside a boiler where the water is heated to a certain temperature close to or substantially corresponding to the temperature of use.

[0006] The present invention is preferably applicable to coffee machines intended for professional use, but may also be applied to machines for semi- professional or home use.

[0007] PRIOR ART

[0008] As is known, a machine for preparing and dispensing coffee typically receives water from a storage tank or from the mains supply or from a preheating system. Water from the mains supply is typically at a temperature of between about 10°C and about 20°C. In an espresso coffee machine, the water received is treated by a pump which introduces it into a boiler where it is heated.

[0009] The process for heating water inside the boilers for coffee machines typically is performed by means of conduction by a heat source which is placed directly in contact with the water. The heat source may be entirely immersed in the water or may be arranged so as to touch the water on one or more surfaces.

[0010] The pressurised hot water which flows out from the boiler is used for the preparation of an espresso coffee or a hot beverage, for example tea. It may also be used to generate steam for foaming milk or another similar beverage.

[0011] Once the reserve of water at the desired temperature has been partially or completely used up, the coffee machine must proceed to replenish the initial volume of water. The fresh water introduced into the boiler is normally supplied from a storage tank or from the water mains at temperatures different from any water remaining inside the boiler. In some known machines, the introduction of fresh water may be performed at the same time as the outflow of the water used for the preparation of beverages.

[0012] In order to ensure that the total amount of the water present inside the boiler reaches the temperature suitable for dispensing, it is therefore advantageous to mix the remaining water with the incoming water.

[0013] The increase in the contact area between the water which has been mixed or is being mixed and the heat source is another aspect which favours the reaching of the target temperature as rapidly as possible, avoiding also the stratification of the temperature.

[0014] The convective movements which are generated inside the closed containers are often advantageously used in order to mix the water inside the boiler. These movements, however, by their very nature are highly inefficient.

[0015] Also known are advanced systems which, for example, have a body rotating about its axis, which creates a swirling movement of the water and favours mixing thereof. These systems, however, require the use electrical energy for operation thereof, hydraulic sealing systems, a resistance to high water temperatures and periodic maintenance in order to avoid limescale deposition and consequent breakage / wear.

[0016] Also known are alternative systems comprising nozzles for introducing fresh water at a suitable pressure, said systems, by means of their speed, direction and position for introduction of the water, improving the mixing and ensuring a more uniform temperature.

[0017] CN1844777 A, CN103759406 A, CN105402894 A disclose boilers for coffee machines.

[0018] SUMMARY OF THE INVENTION

[0019] The Applicant has examined the known solutions configured to favour the mixing of water inside a boiler of a machine for preparing espresso coffee, in particular for favouring the mixing together of the hot water already present inside the boiler and the colder water obtained from the mains supply or from a storage tank or from a preheating system.

[0020] The Applicant has defined the object of providing a novel solution, which is efficient, but without increasing the use of electrical energy (for example in order to heat a greater surface area of water). According to the Applicant, the mixing of the water inside a boiler may be improved by providing a water flow path around concentric tubes.

[0021] According to a first aspect, the present invention provides a boiler for a coffee machine, for example espresso coffee machine, comprising: a first hollow cylindrical body comprising an inlet end and an outlet end, configured to receive water at the inlet end and discharge water at the outlet end; a second hollow cylindrical body arranged radially external with respect to the first hollow cylindrical body, configured to receive water from the first hollow cylindrical body in proximity of its closed bottom and to discharge water at an open outlet end, wherein said closed bottom comprises a flow-diverting surface for directing the water flow between the external surface of the first hollow cylindrical body and the internal surface of the second hollow cylindrical body.

[0022] According to embodiments, the flow-diverting surface has a substantially conical, truncated-conical, pyramidal or truncated-pyramidal shape.

[0023] According to embodiments, the open outlet end of the second hollow cylindrical body is in an intermediate position between the inlet end and the outlet end of the first hollow cylindrical body.

[0024] According to embodiments, the boiler further comprises a third hollow cylindrical body arranged radially external with respect to the second hollow cylindrical body, configured to receive water from the second hollow cylindrical body.

[0025] According to another aspect, the present invention provides a coffee machine, comprising a boiler of the aforementioned type:

[0026] BRIEF DESCRIPTION OF THE FIGURES

[0027] A detailed description of the present invention now follows, being provided purely by way of a non-limiting example, to be read with reference to attached figures in which:

[0028] Fig. 1 is an axonometric view of an example of an espresso coffee machine in which the present invention may be incorporated;

[0029] Fig. 2 is an embodiment of a hydraulic circuit arrangement of an espresso coffee machine according to the present invention;

[0030] Fig. 3 is a schematic view of a boiler according to an embodiment of the invention;

[0031] Fig. 3A is a cross-section through the boiler of Fig. 3; and

[0032] Fig. 4 is a schematic view of the water flow inside the boiler of Fig. 3.

[0033] DETAILED DESCRIPTION

[0034] The description below, solely for convenience, refers in particular to an espresso coffee machine, but the present invention is not limited to such machines and is applicable to machines for dispensing other beverages. For example, barley powder or another cereal powder may be used instead of coffee powder. Therefore, the expression "espresso coffee machine" must be understood as comprising also machines for preparing other beverages, provided they use forced percolation (pressurized water). Similarly, the expression "espresso coffee" must be understood as having a wider meaning corresponding to the product (coffee, barley or other cereal) used for the preparation of the beverage, again by means forced percolation (using pressurized water).

[0035] The machine to which the present invention is applicable may also be a machine of the lever or piston type.

[0036] Figure 1 shows, purely by way of example, an espresso coffee machine, denoted overall by the reference number 1000. The machine 1000 comprises a substantially closed machine body 1001 which houses inside it the main components of the machine, some of which will be described below. At the top, preferably, the machine 1000 comprises a surface 1002 for resting the coffee cups. An electric resistance (not shown) or other heating system for heating the cups on the surface 1002 may also be provided.

[0037] The machine 1000 comprises at least one dispensing group 1003 for dispensing espresso coffee. Preferably, the machine 1000 comprises several dispensing groups 1003, for example three dispensing groups, such as the machine shown by way of example in Fig. 1. There could also be two, four or more dispensing groups. A drip tray 1004, which is preferably partially closed at the top by a grille 1005, is preferably arranged underneath the dispensing groups 1003. Typically, the coffee cups are placed on the grille 1005 during dispensing of the espresso coffee.

[0038] A portafilter for supporting a filter for a puck of coffee powder can be removably connected to each dispensing group 1003.

[0039] The machine 1000 may comprise one or more displays 1010 and pushbuttons, for example for switching the machine on / off and / or for starting / stopping the dispensing operation.

[0040] The machine 1000 shown in Fig. 1 also comprises, for each dispensing group 1003, a lever 1012 (or pushbutton or other similar device) for starting / stopping the dispensing of the espresso coffee and / or for modifying the dispensing pressure during dispensing of the espresso coffee.

[0041] The various reference numbers used, together with a short description of the single complement, are listed here below:

[0042] I COFFEE BOILER

[0043] 10 PUMP

[0044] I I EXPANSION VALVE

[0045] 12 CHECK VALVE

[0046] 13 PREHEATER MIXING VALVE

[0047] 14 STEAM BOILER

[0048] 15 DECOMPRESSION VALVE

[0049] 16 FLOWMETER (VOLUMETRIC METER)

[0050] 18 BALL VALVE

[0051] 19 STEAM SOLENOID VALVE

[0052] 20 STEAM WAND

[0053] 21 HOT WATER MIXING VALVE

[0054] 22 STEAM BOILER FILLING SOLENOID VALVE

[0055] 23 HOT WATER WAND

[0056] 24 PRESSURE SENSOR

[0057] 25 STEAM BOILER PRESSURE GAUGE

[0058] 26 DISCHARGE WELL

[0059] 27 GEAR PUMP 28 SAFETY VALVE

[0060] The flowmeter 16 may be positioned along the hydraulic circuit which connects the pump 10 to the dispensing group 1003, so as to provide a measurement of the water volume supplied to the dispensing group 1003.

[0061] The pressure sensor 24 may be positioned at the dispensing group 1003 so as to provide a measurement of the beverage dispensing pressure of the dispensing group 1003.

[0062] In Fig. 2 the symbol system has been adopted whereby the cold water flow is indicated graphically by means of a “long dash - single short dash - short dash” line; the hot water flow is indicated graphically by means of a continuous line, the steam vapour is indicated graphically by means of a broken line and, finally, the discharge water flow is indicated graphically by means of a “long dash - short double dash - long dash” line.

[0063] Briefly, in the example of the arrangement shown in Fig. 2, the cold water from the mains water supply (or from any other source) is supplied to the pump 10. The pump 10 supplies the water to the steam boiler 14, preferably passing through the check valve 12 and the preheater mixing valve 13.

[0064] Preferably, the steam wand 20 is connected to the steam boiler 14 so as to dispense steam, for example in order to foam milk for making a cappuccino.

[0065] Preferably, the steam boiler 14 is connected by a fluid flow path to the hot water wand 23 so as to dispense hot water for the preparation of infusions (teas or herbal infusions, for example).

[0066] The water from the coffee boiler 1 may be conveyed to the dispensing group 1003 via an infusion solenoid valve 9 and an infusion water pipe 6. In particular, the water from the pipe 6 preferably reaches a shower screen 4 where it is distributed substantially uniformly over a puck of coffee powder contained inside a filter 7 supported by the portafilter 8. The puck of coffee powder comprises ground coffee which is pressed by the barista before engaging the portafilter together with the bottom part of the dispensing group 1003.

[0067] An embodiment of a boiler 100 according to the present invention is shown in Fig. 3 and Fig. 4. According to the embodiment shown in Figures 3 and 4, the boiler 100 comprises a first hollow cylindrical body 110, a second hollow cylindrical body 120 and a third hollow cylindrical body 130. According to embodiments, the three hollow cylindrical bodies 110, 120, 130 are substantially coaxial. According to embodiments, one or more of the hollow cylindrical bodies has a circular cross-section. Advantageously, all three hollow cylindrical bodies 110, 120, 130 have a circular cross-section.

[0068] The first hollow cylindrical body 110 has a first diameter 111 , the second hollow cylindrical body 120 has a second diameter 121 and the third hollow cylindrical body 130 has a third diameter 131 . The first diameter 111 is smaller than the second diameter 121. The second diameter 121 is smaller than the third diameter 131.

[0069] The first hollow cylindrical body 110 has a first length 112, the second hollow cylindrical body 120 has a second length 122 and the third hollow cylindrical body 130 has a third length 132. The third length 132 is greater than the second length 122. The third length 132 is also greater than the first length 112.

[0070] The third hollow cylindrical body 130 contains the first hollow cylindrical body 110 and the second hollow cylindrical body 120. The second hollow cylindrical body 120 contains, at least partially, the first hollow cylindrical body 110.

[0071] The first hollow cylindrical body 110 is open at both its ends. The inflowing water, which is at a temperature lower than that of the outflowing water, enters into the first hollow cylindrical body 110 at the inlet end 113 and flows out at the outlet end 14.

[0072] The second hollow cylindrical body 120 comprises a closed bottom 123, in the proximity of the outlet end 114 of the first hollow cylindrical body 110. The closed bottom of the second hollow cylindrical body 120 comprises a surface 125 configured to deviate the water flow flowing out from the first hollow cylindrical body 110. For example, it may have a pyramidal, truncated- pyramidal, spherical, conical or truncated-conical surface. According to the embodiment shown in Figures 3 and 4, the flow-diverting surface 125 is conical. The vertex of the cone is situated, preferably, at a non-zero distance from the outlet end 114 of the first hollow cylinder 110.

[0073] The end 124 of the second hollow cylindrical body 120, which is opposite to the closed bottom 123, is at least partially open. According to embodiments, as shown in sequence in Figures 3 and 4, the open end 124 of the second hollow cylinder 120 is situated a non-zero distance from the inlet end 113 of the first hollow cylindrical body 110. Namely, the end 124 is situated between the two ends 113 and 114 of the first hollow cylindrical body 110.

[0074] The walls of the conical closed bottom 125 direct the water flowing out from the first hollow cylindrical body 110 towards the walls of the second hollow cylindrical body 120. The water thus comes into contact with the external wall of the first cylindrical body 110 and with the internal wall of the second hollow cylindrical body 120 and then flows into the third, outermost, hollow cylindrical body 130. In Fig. 4 the flow path of the water is indicated by means of the arrows A, B, C, D and E. The boiler could be configured so as to have a water outlet (OUT) at any point on the surface of the third hollow cylindrical body 130. Merely for illustrative purposes, the water outlet OUT has been indicated in Figures 3 and 4.

[0075] The water flow, which is directed so as to pass over the walls of the three hollow cylindrical bodies of the boiler, favours mixing of the water at different temperatures and allows more efficient heating thereof should the heat sources be situated inside the boiler.

[0076] Advantageously, the mixing inside the boiler is performed without the presence of moving bodies and therefore without energy consumption. Also the problem of the resistance to high temperatures is avoided and the maintenance of the boiler is significantly reduced compared to the known solutions.

Claims

CLAIMS1. A boiler (100) for a coffee machine (1000), comprising: a first hollow cylindrical body (110) comprising an inlet end (113) and an outlet end (114), configured to receive water at the inlet end (113) and discharge water at the outlet end (114); a second hollow cylindrical body (120) arranged radially external with respect to the first hollow cylindrical body (110), configured to receive water from the first hollow cylindrical body (110) in proximity of its closed bottom (123) and to discharge water at an open outlet end (124), wherein said closed bottom (123) comprises a flow-diverting surface (125) for directing the water flow between the external surface of the first hollow cylindrical body (110) and the internal surface of the second hollow cylindrical body (120), wherein the flow-diverting surface (125) has a substantially conical, truncated-conical, pyramidal or truncated-pyramidal shape.

2. The boiler (100) of claim 1 , wherein the open outlet end (124) of the second hollow cylindrical body is in an intermediate position between the inlet end (113) and the outlet end (114) of the first hollow cylindrical body (110).

3. The boiler (100) according to claim 1 or 2, further comprising a third hollow cylindrical body (130) arranged radially external with respect to the second hollow cylindrical body (120), configured to receive water from the second hollow cylindrical body (120).

4. A coffee machine (1000) comprising a boiler (100) according to any one of claims 1 -3.

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