Device for producing milk foam

Abstract

A device for processing milk foam for use in an automatic hot and/or cold beverage machine includes a milk pump to pump the milk foam, and a secondary processing device coupled to the milk foam pump to change the consistency of the milk foam. The secondary processing device includes a homogenizer to break up and distribute air bubbles in the milk foam. The homogenizer has a reducing region including a plurality of impact bodies arranged to define a channel labyrinth through which the milk foam is flowable. Additionally, there is provided a process for homogenizing milk foam utilizing the above device, includes steps of a) impacting divided partial flows of the milk foam with the impact surfaces to divide the air bubbles of the milk foam; and b) mixing the divided partial flows with the divided air bubbles together to form new partial flows.

Claims

1. A device for processing milk foam for use in an automatic hot and/or cold beverage machine, comprising: a first mixing chamber having an input for admitting air from a supply of air, an input for admitting milk from a milk supply and an output, the first mixing chamber mixing the air and the milk to produce the milk foam at the output; a milk pump in fluid communication with the first mixing chamber to pump the milk foam; and a secondary processing device in fluid communication with the milk foam pump to change a consistency of the milk foam, the secondary processing device including a flow through direction and a homogenizer to break up and distribute air bubbles in the milk foam, the homogenizer comprising: an inlet region to receive the milk foam and having a shape of a truncated cone that is expanded in the flow-through direction, the truncated cone having a top surface with a circumference and that makes an obtuse angle with a conically shaped side surface of the truncated cone, wherein the milk foam entering the inlet region impacts the top surface and is distributed uniformly around the circumference to the conically shaped side surface; a reducing region adjoining the inlet region and including a plurality of impact bodies arranged to define a channel labyrinth through which the milk foam is flowable in divided partial flows in the flow-through direction of the secondary processing device, the reducing region being tapered in the flow-through direction; and an outlet region adjoining the reducing region in a downstream direction and having a shape of a truncated cone that is further tapered in the flow-through direction relative to the reducing region.

2. The device according to claim 1, wherein the impact bodies respectively include an impact surface which is hit by at least one of the partial flows of the milk foam that flows through the channel labyrinth.

3. The device according claim 1, wherein the impact bodies are respectively arranged in rows, one below the other, in an extension direction of the homogenizer which is the flow-through direction for the milk foam.

4. The device according to claim 3, wherein the impact bodies of adjacent rows are arranged offset relative to each other.

5. The device according to claim 3, wherein the impact bodies of a row are arranged spaced apart from one another.

6. The device according to claim 3, wherein the homogenizer extends concentrically around an axis so that the impact bodies of each row are respectively arranged and distributed uniformly in a circumferential direction around the axis.

7. The device according to claim 1, wherein the impact bodies have lower ends that are tapered in the flow-through direction.

8. The device according to claim 1, wherein the secondary processing device comprises a lower housing part in which the homogenizer is arranged form-locking.

9. An automatic hot and/or cold beverage machine comprising the device for generating milk foam according to claim 1.

10. A process for homogenizing milk foam in a device according to claim 2, comprising: a) impacting the divided partial flows of the milk foam with the impact surfaces to divide the air bubbles of the milk foam; and b) mixing the divided partial flows with the divided air bubbles together to form new partial flows.

11. The process according to claim 10, including mixing respectively adjacent divided partial flows together following the impacting with the impact surfaces.

12. The process according to claim 10, including accelerating the milk foam while flowing through the channel labyrinth.

13. The device according to claim 1, wherein the milk pump has a variable capacity which is adjustable to change a pressure of the milk foam in the homogenizer for adjusting the consistency of the milk foam produced by the homogenizer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described in further detail in the following with the aid of an exemplary embodiment and with reference to the drawing, showing in:

(2) FIG. 1 A schematic in block diagram form representing a device for the foaming of milk according to the invention;

(3) FIGS. 2a-2d A secondary treatment device shown schematically in FIG. 1 for changing the consistency of the milk foam illustrated, respectively in a perspective view in FIG. 2a, a side view in FIG. 2b, a cross section in FIG. 2c and an exploded view in FIG. 2d; and

(4) FIGS. 3a-3c A homogenizer used in the secondary treatment device shown in FIG. 2, illustrated in a detailed side view in FIG. 3a, and respective detail views of FIG. 3a in FIGS. 3b and 3c.

DETAILED DESCRIPTION

(5) FIG. 1 shows a device for generating milk foam. The terms milk/air mixture and milk foam, as well as air/milk emulsion, are used synonymously in the following. The device advantageously has the following design.

(6) A milk line 3 connects a milk container 1 and a dispensing device 2, wherein this dispensing device 2 is embodied as an outlet. In the following, the terms dispensing device 2 and outlet are used synonymously. The following components are installed in the same sequence in the milk line 3, extending between the milk container 1 and the outlet 2: a shut-off valve 4, a first mixing chamber 5, a milk pump 6, a first backpressure valve 7, a second mixing chamber 8 and a secondary treatment device 9.

(7) A feed line 10 with therein installed second backpressure valve 12 furthermore empties into the first mixing chamber 5, wherein the feed line 10 is divided in front of the backpressure valve 12 into two branch lines 13, 14.

(8) Both branch lines 13, 14 are connected to an air source 15, 16 (an opening to the atmosphere, an air pump, or a pressure container or the like).

(9) A steam feed line 11 furthermore empties into the second mixing chamber 8 though hot steam from a hot-steam source (not shown herein) can be conducted into the milk line 3.

(10) The device functions as follows. With the aid of the milk pump 6, installed in the milk line 3, milk (for example, milk with a fat content of less than 10%, preferably less than 7.5%) is pumped from the milk container 1 to the outlet 2, wherein the milk may be pumped continuously for the duration of the milk foam production.

(11) The shut-off valve 4 in this case is initially switched from the closed position, shown herein, to the flow-through position.

(12) The milk is then pumped from the milk container 1 into and through the first mixing chamber 5. In the first mixing chamber 5, embodied in the simplest form, for example, in the manner of a T-section with a mixing chamber region having a larger diameter (not shown herein), air is supplied to the milk flowing through the milk line 3, such that the milk and inflowing air are mixed into a foam-type milk/air mixture 40 and/or form an air/milk emulsion. The milk/air mixture 40 takes the form of an emulsion, so that air bubbles 41 are occluded in the milk.

(13) Devices such as a shut-off valve, one or several chokes and/or the like may be installed in the branch line 10, so that the supply of air can be defined, started and interrupted. A fixed choke offers the advantage that a precisely defined amount of air can always be fed in. Chokes are known per se to one skilled in the art and are therefore not shown further herein. It is conceivable to alternately switch between two chokes and/or choke arrangements for feeding the air (especially for cold or warm milk products).

(14) A constant amount of air may be suctioned continuously into the milk flowing through the first mixing chamber 5 during the milk foam production, so as to produce a milk/air mixture 40 with uniform properties, if possible.

(15) The milk/air mixture 40 produced in the first mixing chamber 5 is pumped with the milk pump 6 and is condensed or concentrated therein, wherein a milk pump 6 with adjustable pumping capacity may be used.

(16) The condensed milk/air mixture 40, which flows out of the milk pump 6 and continues on, is then pumped through a section containing the second mixing chamber 8. In the second mixing chamber 8, for example embodied as a T-section, hot steam optionally flows from the line 11 into the milk/air mixture 40, so as to increase the temperature of the milk/air mixture and generate heated milk foam 40. The amount of inflowing hot steam remains constant in this case. However, it is also conceivable to change this amount, so that the degree of heating up the milk foam 40 can be adapted.

(17) Adjoining the second mixing chamber 8 is a decompression section for the milk line 3 which empties into the secondary treatment device 9.

(18) The heated milk/air mixture 40, flowing out of the second mixing chamber 8 and the decompression section, could already be released to a container, but that is not the case here. Rather, the mixture is first processed once more in the secondary processing device 9, to purposely change the foam quality.

(19) The secondary processing device 9 preferably comprises a homogenizer 95, designed to homogenize the milk foam 40, so that the air bubbles are broken up and are distributed more uniformly throughout the milk. This secondary treatment initially is realized such that the milk foam 40, as well as the air bubbles 41, impact at least once or repeatedly with impact surfaces 971 (see FIG. 3a-3c).

(20) The type and intensity of the secondary treatment in this case depends in particular on the pumping capacity and/or the speed of the milk pump 6, meaning on the pressure of the milk pump 6 for pumping the milk foam 40 into the secondary treatment device 9. The properties of the milk foam can thus be influenced substantially via the pumping capacity of the milk pump 6 in order to generate different foam qualities (for example relating to the bubble size) which are particularly suitable for different specialty coffees, such as cappuccino or milk coffee or the like.

(21) From the secondary treatment device 9, the homogenized milk foam 40 is then discharged through outlet or dispenser 2 into a container (not shown), for example into a cup.

(22) Milk foam 40 which is produced continuously, so-to-speak, during the operation has an adjustable foam consistency. Milk foams having different consistencies can thus be produced according to the invention, ranging from very fine (with extremely small air bubbles 41) to rough (with large air bubbles 41 by comparison) and further ranging from fluffy to creamy to solid.

(23) FIGS. 2a-2d provide various views of the secondary treatment device 9. FIG. 2 (a) shows a perspective view; FIG. 2(b) shows a view from the side; FIG. 2(c) shows a section A-A through the representation in FIG. 2(b); and FIG. 2(d) contains an enlarged, exploded view.

(24) The secondary treatment device 9 comprises a housing which extends concentrically around an axis 32 and is formed with an upper housing part 91 and a lower housing part 92, wherein the homogenizer 95 is arranged in the lower housing part 92. A top section 94 with a nozzle 941 is provided in the upper housing part 91. The upper housing part 91 and the top section 94 contain a through bore (not given a reference), wherein a connecting insert 93 is provided in the top part 94 which functions as inlet opening 20 for the milk/air mixture 40. The milk/air mixture 40 flows through the inlet opening 20 and the nozzle 941 to the homogenizer 95.

(25) Owing to the pressure exerted by the milk/air mixture 40 onto the homogenizer 95, the homogenizer is pressed against an inside wall 921 of the lower housing part 92. The homogenizer 95 has a conical shape that is tapered in extension direction 30. It has an outside wall 957 with an angle α of approximately 1°-5°, preferably 2°, relative to the axis 32, thereby achieving a good sealing effect. In addition, the milk/air mixture 40 is accelerated while flowing through the homogenizer 95.

(26) The lower housing part 92 and its inside wall 921 are furthermore embodied to match the shape of the homogenizer 95, meaning they are also conically shaped. As a result, the homogenizer 95 is centered by the pressure exerted by the milk/air mixture 40 and is pressed against the housing inside wall 921, so that it fits form-locking against it. The milk/air mixture 40 therefore cannot flow between the housing inside wall 921 and the outside wall of the homogenizer 957.

(27) The outside wall 957 of the homogenizer 95 is interspersed with a channel labyrinth 98 (see FIGS. 3a-3c) through which the milk/air mixture is pushed. In the process, it is homogenized, meaning the air bubbles in the milk/air mixture 40 are broken up and distributed uniformly in the milk/air mixture 40.

(28) Once the homogenized milk/air mixture 40 has flown through the homogenizer 95 it is discharged from the secondary treatment device 9 through an outlet 21 in a connecting insert 93′ that is arranged in a through bore (not given a reference) in the lower housing part 92 as shown in FIGS. 2c and 2d.

(29) The connecting insert 93 on the inlet side is sealed against the upper part 94, the upper part 94 is sealed against the lower housing part 92, and the outlet side connecting insert 93′ is sealed against the lower housing part 92 with sealing rings 96, so that the milk/air mixture 40 cannot escape into the intermediate spaces (not given a reference) of the secondary treatment device 9.

(30) FIGS. 3a-3c show in 3a a detailed view from the side of the homogenizer and in 3b and 3c respective details of the homogenizer according to FIG. 3a.

(31) The homogenizer 95 has an inlet region 951, which is embodied as a truncated cone and is therefore conically expanded in the extension direction 30. On the inlet side, the milk/air mixture during intake impacts an entrance surface 956 which makes an obtuse angle with a ramp 99 formed by the conical shape (FIGS. 3a, 3b). The milk/air mixture 40 is then distributed uniformly in the circumferential direction 31 around the ramp 99 formed by the conical shape.

(32) A reduction region 953 adjoins the inlet region 951. The reduction region 953 comprises the outside wall 957 which is interspersed with the channel labyrinth 98 and is also shaped conically, but is tapered in extension direction 30.

(33) The reduction region 953 is followed by an outlet region 952 where the homogenizer 95 has a truncated cone shape and is tapered further in extension direction 30.

(34) In the reduction region 953, impact bodies 97 are provided between which the channel labyrinth 98 extends. The individual impact bodies 97 have impact surfaces 971 with which the partial flows 42 of the milk foam 40 impact while flowing through the channel labyrinth 98. On a side located opposite the impact surface 971, meaning the lower side of the impact bodies 97 in extension direction 30, the impact bodies are respectively tapered. In the embodiment shown herein, the impact bodies 97 have a triangular shape.

(35) Several impact bodies 97 are respectively arranged side-by-side in rows 972.sub.1, 972.sub.2-972.sub.i, distributed evenly in the circumferential direction 31. Several lower rows 972.sub.1, 972.sub.2-972.sub.i with impact bodies 97, arranged one below the other, are furthermore also provided in the extension direction 30. The impact bodies 97 of same rows 972.sub.1, 972.sub.2-972.sub.i are respectively spaced apart, so that a channel 982 is formed between them. In addition, the impact bodies 97 of the rows 972.sub.1, 972.sub.2-972.sub.i are respectively offset relative to each other in the center, wherein this offset is indicated by double arrow 17. As a result, the impact surface 971 of an impact body 97 is always arranged below a channel 982.

(36) An approximately triangle-shaped impact region 981 is furthermore formed in this way above each impact body 97 which connects the channel 982 above the impact surface 971 of the impact body 97 with the two channels 982 that adjoin the impact body 97 on the side.

(37) The channel labyrinth 98 comprises therefore a plurality of impact regions 981 which are connected by the channels 982.

(38) A milk/air mixture 40 that flows through the secondary processing device 9, enters the channel labyrinth 98 on the inlet end 954 of the reduction region 953 through the upper row 972.sub.1 of the impact bodies 97 in the extension direction 30. In the process, the milk/air mixture is divided into approximately equally large partial flows 42 which flow through respectively one of the channels 982 of the upper row 972.sub.1.

(39) The partial flows 42 respectively impact with the lower impact surface 971 that is arranged below the channel 982, wherein not only the partial flows 42 are divided but also the air bubbles 41. The divided partial flows 42 then respectively flow through the channels 982, arranged on the side of the impact bodies 97 with which they impact. In the process, they are mixed with the respectively adjacent divided partial flows 42, to form a new partial flow 42 that flows through the channel 982. Subsequently, this partial flow impacts with the following impact surface 971 of the row 972.sub.1, 972.sub.2-972.sub.i that follows in extension direction 30 and is divided, wherein the air bubbles 41 are divided once more. This operation is repeated until the milk/air mixture 40 has flown through the last, lower row 972.sub.i of the homogenizer 95 at its lower, outlet-side end 955.

(40) In the outlet region 952 and when flowing out through the opening 21, the homogenized partial flows 42 converge once more.

(41) The partial flows 42 are pushed at high pressure through the channel labyrinth 98. The pressure depends on the pumping capacity of the milk pump 6 and can be adjusted via this pump. The air bubbles 41 hit the impact surface 971 with a high enough energy so that they divided upon impact. Owing to the conical shape of the homogenizer 95, the surface ratios are reduced and the partial flows 42 are accelerated. As a result, the impact energy is sufficiently high, even at the lower end 955 in extension direction 30, to break up small air bubbles 41 during impact.

(42) When flowing through the homogenizer 95, the milk/air mixture 40 is therefore homogenized since the air bubbles 41 continue to be reduced, so that the individual bubble sizes conform to each other and the milk/air mixture 40 continues to be mixed.

(43) The invention has been described in detail with respect to various embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.