Steam wand for foaming milk

Abstract

A steam wand for whipping milk or other edible liquids comprises a steam delivery tube (5) having a steam delivery nozzle (6) at one end, where the steam delivery nozzle (6) has a check valve (10) inside.

Description

[0001] The invention relates to a steam wand for whipping milk, which steam wand can be connected to a steam generator, which steam generator is particularly, but not necessarily, incorporated in a coffee machine.

[0002] As is known, in coffee machines, the steam wand for frothing milk has a steam delivery tube with a steam nozzle at one end.

[0003] The steam nozzle is designed to be immersed in milk (or similar plant-based beverages) for heating and frothing.

[0004] When the steam flow stops, due to well-known physical principles, a vacuum is created in the steam retraction circuit which tends to suck the milk out.

[0005] The sucked milk can flow upward through the delivery nozzle and delivery pipe and even flow into the steam generator, thereby causing many problems such as blockage of the supply circuit, the smell of burnt milk and / or unhygienic conditions.

[0006] Even the most experienced operators, in order to avoid this risk, will avoid pulling the delivery nozzle away from the milk during frothing, as the strong steam jet at a distance from the free milk surface would create dangerous splashes of hot milk and would also ruin the quality of the froth by creating large surface bubbles.

[0007] To compensate for this inconvenience, almost all coffee machine manufacturers provide special shut-off devices, such as taps, valves, diverters, solenoid valves, which are located in the steam retraction circuit upstream of the steam wand.

[0008] This effectively protects the steam generator, but some milk still gets sucked into the steam wand and stagnates there for a long time.

[0009] Given the high temperature of the steam circulating in the circuit and considering that in any case the milk drawn in at the end of preparation is generally above 60°C, it should be easily understood that the risk of the milk becoming dirty inside the steam wand and at the point in the steam withdrawal circuit where the shut-off device is located is always high, which, moreover, is sometimes a component inside the coffee machine and is therefore inaccessible.

[0010] As a result, over time, the functionality and hygiene of the steam supply circuit may become problematic.

[0011] In the professional world, a high degree of reliance is placed on the expertise of the bartender, so frequent sanitizing / rinsing cycles and / or special cleaning cycles (using special cleaning agents) are required at the end of preparation to keep the internal parts of the steam retraction circuit clean.

[0012] Such operations often require the supervision of highly trained personnel (bartenders) and do not always achieve the desired results in a repeatable manner.

[0013] The technical task proposed by the present invention is therefore to eliminate the technical drawbacks complained of in the known steam retraction circuits for whipping milk.

[0014] Within the scope of this technical task, one object of the invention is to maintain the hygiene and functionality of a steam supply circuit with a wand equipped with a steam nozzle for whipping milk.

[0015] Another object of the invention is to maintain the hygiene and functionality of such a steam supply circuit in a simple and automatic way and with reproducible results regardless of the skill of the operator.

[0016] The technical task and these and other purposes according to the invention are achieved by realizing a steam wand for whipping milk or other edible liquids, comprising a steam delivery pipe having a steam nozzle at one end thereof, characterized in that the steam nozzle has a non-return valve inside.

[0017] In a preferred embodiment of the present invention, the check valve includes a valve body having a steam channel, the steam channel having an end for a steam inlet from the steam delivery pipe, an end for a steam outlet, and a sealing seat positioned between the steam inlet end and the steam outlet end; a baffle, which is positioned against the sealing seat in a closed position of the steam channel and is movable to open the steam channel by a steam flow from the delivery pipe; and an elastic element, which is used to automatically return the baffle in the closed position of the steam channel.

[0018] In a preferred embodiment of the present invention, the valve body comprises a first component made of a non-sticky polymer-based material, the first component defining a portion of the passage extending from the downstream of the sealing seat to the steam outlet end.

[0019] In a preferred embodiment of the present invention, the valve body comprises a second component of a rubber-based material, the second component defining a portion of the passage including the sealing seat.

[0020] In a preferred embodiment of the present invention, the second rubber-based material component defines a portion of the passage extending upstream of the sealing seat to the steam inlet end.

[0021] In a preferred mode of embodiment of the invention, the second component is a tubular element extending into the axial cavity of the first component.

[0022] In a preferred embodiment of the present invention, the second component has at least one peripheral rib, and the at least one peripheral rib is tightly engaged with the inner peripheral surface of the first component.

[0023] In a preferred embodiment of the present invention, the dispensing nozzle comprises a housing for accommodating the valve body.

[0024] In a preferred embodiment of the present invention, the second component has at least one peripheral rib, and the at least one peripheral rib is tightly engaged with the inner peripheral surface of the outer shell.

[0025] In a preferred mode of embodiment of the invention, the nozzle has a connection connection to the steam delivery pipe.

[0026] In a preferred embodiment of the invention, the connection joint comprises a joint for mechanically connecting the housing to the steam delivery pipe.

[0027] In a preferred embodiment of the present invention, the conveying pipe comprises an outer pipe and a thermally insulating inner pipe separated by an air gap, and the inner pipe engages the steam channel upstream of the sealing seat.

[0028] Due to the insulating inner tube, the steam wand in use is relatively cool to the touch, thereby avoiding the risk of scalding for the user and at the same time avoiding burns / scalds from milk coming into contact with the outer surface, even if some of its components are made of heat-conducting materials.

[0029] A steam wand for whipping milk can be connected to the steam supply circuit of the coffee machine.

[0030] Thus, the method for whipping milk comprises generating steam with a steam generator in a coffee machine and delivering said steam flow with a pressure at least sufficient to exert a force on the baffle to open the channel, which force is greater than a predetermined elastic closing force exerted by the elastic element to the channel.

[0031] Advantageously, therefore, the dispensing nozzle has a non-return valve, the interior of which prevents the milk from rising when the dispensing nozzle is immersed in the milk and keeps the entire steam supply circuit upstream of the baffle clean.

[0032] In order to avoid any type of contamination, the valve body (even the part that may accidentally get wet with milk) is made of a special polymer material, such as a thermoplastic polymer with anti-stick properties.

[0033] Furthermore, the check valve generates a back pressure that stabilizes the transport steam flow by calibrating the elastic force of the open passage.

[0034] The quality of milk frothing is guaranteed even when the wand is combined with a home coffee machine, which usually has an instant steam generator.

[0035] In particular, the normally closed check valve allows the steam wand to be introduced into the liquid to be whipped, thanks to the push of the elastic element, thereby preventing the liquid from rising above the check valve itself, despite the low pressure existing in the steam inner withdrawal path, which remains completely clean.

[0036] When the steam channel is activated, the pressure upstream of the damper increases until it exceeds the opening value, allowing steam to flow from the nozzle.

[0037] Throughout the heating and frothing phase, the non-return valve remains open, thus ensuring a defined back pressure and a constant flow rate, regardless of the amount of milk and, within certain limits, the configuration of the steam output from the delivery nozzle.

[0038] When the steam flow is interrupted at the end of the whipping process, the reduction in steam pressure causes the non-return valve to close automatically and prevents the hot milk from flowing back into the steam supply circuit.

[0039] Furthermore, the dispensing nozzle can be removed from the steam delivery pipe in order to be cleaned and inspected by the operator or technician, which is the perfect guarantee for correct operation under absolutely hygienic conditions.

[0040] Other features and advantages of the invention will become more apparent from the description of a preferred but not exclusive form of implementation of a steam wand for whipping milk and other edible liquids according to the invention, which is illustrated in an exemplary and non-limiting manner in the accompanying drawings, in which

[0041] Figure 1 A schematic diagram showing a coffee machine incorporating a steam wand;

[0042] Figure 2 A view showing the end of a steam wand;

[0043] Figure 3a shows a longitudinal section of the end of the steam wand with the check valve closed due to the non-binding action of the resilient element;

[0044] Figure 3b A longitudinal section of the end of the steam wand is shown, wherein the non-return valve is open due to the opening force exerted by the steam flow on the flapper, which overcomes the closing force exerted by the elastic element on the flapper.

[0045] With reference to the above-mentioned figures, there is shown a steam wand for whipping milk or other edible liquids, which is indicated as a whole by the reference numeral 1 .

[0046] The steam wand 1 may be connected to a steam internal withdrawal circuit 2 which is usually, but not necessarily, incorporated in a domestic or professional coffee machine 3 .

[0047] The steam supply circuit 2 may comprise an accumulator steam generator 4 , in particular if the coffee machine is intended for professional use, or an instantaneous steam generator, in particular if the coffee machine is intended for domestic use.

[0048] The steam wand 1 comprises a steam delivery tube 5 having a steam nozzle 6 at one end 7 , while the other end 8 of the steam delivery tube 5 is connected to the steam supply circuit 2 .

[0049] The delivery tube 5 of the steam wand 1 can be connected to the steam supply circuit 2 via a fixed or preferably articulated joint 9, so that the steam wand 1 can also be oriented during steam supply.

[0050] The delivery pipe 5 comprises an outer pipe 5 ′ and an inner pipe 5 ″ separated by an air gap 5 ′″.

[0051] The inner tube 5" is preferably made of a thermally insulating material suitable for the food industry, such as a polytetrafluoroethylene (PTFE) base.

[0052] The gold outer tube 5' is usually made of stainless steel.

[0053] Advantageously, the steam nozzle 6 has a non-return valve 10 inside.

[0054] The check valve 10 includes a valve body 11 and a baffle 12 .

[0055] The valve body 11 has a passage 13 for the steam from the delivery pipe 5 to pass through.

[0056] The steam passage 13 has a steam inlet end 13a, a steam outlet end 13b, and a sealing seat 13c located between the steam inlet end 13a and the steam outlet end 13b.

[0057] The steam outlet end 13 b is formed by one or more calibrated steam outlet holes 15 .

[0058] In the closed position of the steam passage 13 , the baffle 12 is positioned against the sealing seat 13 c and can be moved by the action of the steam flow F from the delivery pipe 5 to open the steam passage 13 .

[0059] The check valve 10 has an elastic element 14 for automatically returning the baffle plate 12 to a closing position of the steam passage 13 .

[0060] In the case shown, the flap 12 is a sphere and the elastic element 14 is a helical spring.

[0061] The baffle 12 is made of a food-compatible material, such as polytetrafluoroethylene thermoplastic polymer (PTFE), polyetheretherketone (PEEK), polysulfone (PPS), polyphthalamide (PPA), or polyamide with glass particles (PA+GF).

[0062] The elastic element 14 is always made of a food-compatible material, such as stainless steel.

[0063] The valve body 11 comprises a first part 11a made of a non-stick and essentially thermally insulating polymer-based material suitable for use in the food industry, defining a portion of the steam passage 13 extending from downstream of the sealing seat 13c to the steam outlet end 13b.

[0064] The polymer-based material may preferably comprise the thermoplastic polyetheretherketone (PEEK) or the thermoplastic polymer polysulfone (PPS), or polyphthalamide (PPA) or glass particle filled polyamide (PA+GF).

[0065] The term “downstream” is to be understood relative to the direction of the flow F of steam.

[0066] The valve body 11 further comprises a second part 11 b of a rubber-based material, also suitable for use in the food industry, which defines a portion of the steam channel 13 including a sealing seat 13 c.

[0067] The second part 11 b of rubber-based material also defines a portion of the steam passage 13 extending from upstream of the sealing seat 13 c to the steam inlet end 13 a .

[0068] The term “upstream” is to be understood relative to the direction of the flow F of steam.

[0069] The rubber used is preferably silicone rubber or fluorinated elastomeric rubber (FKM).

[0070] More precisely, the second part 11 b is a tubular element extending into the axial cavity of the first part 11 a .

[0071] The second component 11 b has at least one peripheral rib 16 that is closely engaged with the inner peripheral surface of the first component 11 a .

[0072] The first component 11 a accommodates the baffle 12 and the elastic element 14 in its axial cavity defining the steam passage 13 .

[0073] The elastic element 14 is inserted axially between the baffle 12 and the front wall 11 ′ a of the first part 11 a pierced by the dispenser orifice 15 .

[0074] The same front wall 11 ′ a of the first component 11 a serves as a supporting base for the elastic element 14 from its inner side.

[0075] In the case shown where the elastic element 14 is a helical spring, the latter is coaxially positioned in the axial cavity of the first component 11 a .

[0076] The dispensing nozzle 6 comprises a housing 17 which accommodates the valve body 11 .

[0077] The housing 17 may be made of, for example, stainless steel or a thermoplastic polymer suitable for food contact, such as polyetheretherketone (PEEK) or polysulfone (PPS), or polyphthalamide (PPA) or glass-filled polyamide (PA+GF).

[0078] The second member 11 b has at least one peripheral rib 18 that is closely engaged with the inner peripheral surface of the housing 17 .

[0079] The distributor nozzle 6 has a connection connection 19 to the steam supply pipe 5 .

[0080] The connection nipple 19 may be made of, for example, stainless steel or glass-filled polyamide (PA+GF).

[0081] The connection joint 19 comprises a joint 20 which mechanically connects the housing 17 to the steam transport pipe 5 .

[0082] In the illustrated construction of the dispensing nozzle 6, the second part 11b is clamped between the first part 11a and the joint 20, which in particular has a front male threaded connector 21 engaged in a female threaded connector 22 obtained from the rear extension 23 of the housing 17, and a rear male threaded connector 24 engaged in a female threaded connector 25 obtained from the front end of the steam delivery duct 5.

[0083] More precisely, the rear male threaded joint 24 of the joint 20 engages in a female threaded joint 25 formed in the outer pipe 5 ′ of the steam-carrying pipe 5 .

[0084] The joint 20 also has an intermediate flange 27 which serves as a threaded connection end for the rear extension 23 of the housing 17 .

[0085] Because the first component 11a and the housing 17 are integral, in particular because they are made by a common molding process, at this threaded connection end position of the rear extension 23 of the housing 17, the rear end of the first component 11a is axially clamped on the outer shoulder 28 of the second component 11b, and the rear end of the second component is axially clamped on the front male threaded connector 21 of the joint 20.

[0086] This sealing can be accomplished by suitable gaskets 29, 30 inserted between the joint 20 and the rear extension 23 of the housing 17 and respectively between the joint 20 and the steam conveying pipe 5, in particular the outer pipe 5'.

[0087] Advantageously, the inner pipe 5 ″ of the steam conveying pipe 5 extends axially beyond the outer pipe 5 ′ and engages in the inner channel of the connecting nipple 19 and in the channel 13 , in particular in the part of the channel 13 formed in the second part 11 b upstream of the sealing seat 13 .

[0088] The portion of the passage 13 formed in the second member 11 b upstream of the sealing seat 13 has at least one inner peripheral rib 31 which is in close engagement with the outer peripheral surface of the inner tube 5 ″.

[0089] Advantageously, the inner tube 5″ of the tube 5 extends inside the valve body 11, where it seals against the second portion 11b of the valve body 11, not only limiting the temperature of the wand and the nozzle felt by the operator when touched, but also preventing any milk residue from rising from the channel 13 and contaminating the inner surfaces of the housing 17 and the connecting nipple 19, thus preventing foul-smelling scale from forming on them.

[0090] As mentioned above, the steam wand is preferably connected to a coffee machine.

[0091] In order to froth the milk, steam must be generated by a steam generator in the coffee machine, and the steam flow F must be delivered along the inner tube 5 ″ of the delivery tube 5, with a pressure at least sufficient to exert an opening force of the steam channel 13 on the baffle 12, which is greater than the predetermined elastic closing force of the steam channel 13 exerted by the elastic element 14.

[0092] Therefore, the opening thrust exerted by the steam flow F causes the baffle 12 resisted by the elastic element 14 to move forward and disengage from the sealing seat 13 c.

[0093] Once the steam flow F is interrupted, its thrust on the baffle 12 is also automatically interrupted, so that the elastic element 14 can automatically return the baffle 12 to the closed position of the steam channel 13 .

[0094] As far as the working range of the elastic element 14 is concerned, it is found to be convenient to set the back pressure range between 0.02 bar and 0.150 bar, where the minimum pressure corresponds to the fully closed position of the damper 12, i.e. no steam flow F, and the maximum pressure corresponds to the fully open position of the damper 12, i.e. maximum steam flow F.

[0095] An operator can conveniently inspect the steam wand before or after use, and clean the steam wand by disconnecting the nozzle 6 from the steam delivery pipe 5 .

[0096] The stick for whipping milk or another edible liquid thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; moreover, all the details may be replaced by technically equivalent elements.

[0097] In the implementation process, the materials used as well as the dimensions can be any according to the requirements and the state of the art.

Claims

1. A steam wand (1) for whipping milk or other edible liquids, the steam wand comprising a steam delivery tube (5) having a steam distribution nozzle (6) at one end, characterized in that: The steam distribution nozzle (6) has a check valve (10) inside.

2. The steam wand (1) for whipping milk according to claim 1, characterized in that The check valve comprises a valve body (11) having a steam passage (13), wherein the steam passage has an end (13a) for a steam inlet from the steam delivery pipe (5), an end (13b) for a steam outlet, and a sealing seat (13c) positioned between the steam inlet end (13a) and the steam outlet end (13b); a baffle (12) which is positioned against the sealing seat (13c) in a closed position of the steam passage (13) and is movable to open the steam passage (13) by a steam flow (F) from the delivery pipe (5); and an elastic element (14) which is used to automatically return the baffle (12) to the closed position of the steam passage (13).

3. A steam wand (1) for whipping milk according to any one of the preceding claims, characterised in that The valve body (11) comprises a first part (11a) made of a non-sticky, heat-insulating polymer-based material, which defines a portion of the passage (13) extending downstream of the sealing seat (13c) to the steam outlet end (13b).

4. Steam wand (1) for whipping milk according to the preceding claim, characterised in that The valve body (11) comprises a second part (11b) of a rubber-based material, which defines a portion of the passage (13) including the sealing seat (13c).

5. Steam wand (1) for whipping milk according to the preceding claim, characterised in that The second part (11b) defines a portion of the passage (13) extending upstream of the sealing seat (13c) to the steam inlet end (13a).

6. The steam wand (1) for whipping milk according to any one of claims 4 and 5, characterized in that The second component (11b) is a tubular element extending into the axial cavity of the first component (11a).

7. A steam wand (1) for whipping milk according to any one of the preceding claims, characterised in that The second component (11b) has at least one peripheral rib (16) which is in close contact with the inner peripheral surface of the first component (11a).

8. A steam wand (1) for whipping milk according to any preceding claim, characterised in that The baffle (12) is a sphere, and the spring element (14) is a helical spring.

9. A steam wand (1) for whipping milk according to any preceding claim, characterised in that The dispensing nozzle (6) comprises a housing (17) for accommodating the valve body (11).

10. A steam wand (1) for whipping milk according to any one of the preceding claims, characterised in that The second component (11b) has at least one peripheral rib (18) which is in close contact with the inner peripheral surface of the housing (17).

11. A steam wand (1) for whipping milk according to any preceding claim, characterised in that The dispensing nozzle (6) has a connection connection (19) to the delivery tube (5).

12. Steam wand (1) for whipping milk according to the preceding claim, characterised in that The connection joint comprises a joint (20) for mechanically connecting the housing (17) to the steam delivery pipe (5).

13. The steam wand for whipping milk according to any one of claims 11 and 12, characterized in that The delivery pipe (5) comprises an outer pipe (5') and an inner pipe (5") separated by an air gap (5"), and the inner pipe is sealingly engaged in the steam channel (13) upstream of the sealing seat (13c).

14. Coffee machine (3) having a steam wand (1) for frothing milk according to any preceding claim.

15. A method for whipping milk using a coffee machine (3) according to the preceding claim, characterized in that Steam is generated by a steam generator (4) present in the coffee machine (3), and a steam flow (F) is delivered along the delivery pipe (5), the steam flow having a pressure at least sufficient to exert an opening force of the channel (13) on the baffle (12), the opening force being greater than a predetermined elastic force exerted by the elastic element (14) to close the channel (13).

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