EP2190777A2

EP2190777A2 - Dispenser head for connection with an extractor device mounted in a beverage container

Info

Publication number: EP2190777A2
Application number: EP08801361A
Authority: EP
Inventors: Ken Riis
Original assignee: Micro Matic AS
Current assignee: Micro Matic AS
Priority date: 2007-09-20
Filing date: 2008-09-16
Publication date: 2010-06-02
Anticipated expiration: 2028-09-16
Also published as: JP2010538926A; ATE505432T1; RU2010115499A; DE602008006215D1; EP2190777B1; US20100308084A1; WO2009036759A3; KR20110109807A; WO2009036759A2; CN101977838A

Abstract

The dispenser head (1) comprises a pressure medium inlet (7) communicating with a pressure medium passage for supply of a pressure medium to a beverage container. A pressure medium valve (39) is adapted to open and close the beverage passage, and a hollow beverage piston (9) is arranged to be axially displaceable between an open position, in which it may convey beverage from the beverage container to a beverage outlet (8), and a closed position, in which a beverage extractor valve of the beverage container is closed. The dispenser head (1) is adapted to maintain the closed position of the pressure medium valve (39) in the disconnected state of the dispenser head (1) and the beverage container.

Description

Dispenser head for connection with an extractor device mounted in a beverage container

The present invention relates to a dispenser head for connection with an extractor device mounted in a beverage container, such as a beer keg, in which the beverage may be pressurized, the dispenser head comprising a pressure medium inlet communicating with a pressure medium passage for supply of a pressure medium, such as CO₂, to the beverage container, a pressure medium valve being adapted to open and close the beverage passage, a beverage outlet for delivery of beverage from the beverage container to a tapping device, and a hollow beverage piston arranged to, in the connected state of the dispenser head and the extractor device, be axially dis- placeable between an open position, in which it may convey beverage from a down tube of the extractor device to the beverage outlet, and a closed position, in which a beverage extractor valve of the extractor device closes an outlet of the down tube.

WO 93/17954 (Micro Matic A/S) discloses a dispenser head adapted to be coupled to an extractor device mounted in a beer keg. After mounting the dispenser head on the beer keg, a handle of the dispenser head is operated, whereby a hollow beer piston is displaced into the extractor device, thereby opening a beer valve and a CO₂ valve located in the extractor device. Simultaneously, the hollow beer piston opens a CO₂ valve in the dispenser head, so that CO₂ is supplied to the beer keg in order to press beer up through the extractor device to the dispenser head. However, if the handle of the dispenser head is inadvertently operated in the disconnected state of the dispenser head and the extractor device, CO₂ will escape to the surroundings through the CO₂ valve that is opened simultaneously with the operation of the handle. If the mistake is not discovered in time, an entire CO₂ cylinder may be emptied in this way.

The object of the present invention is to provide a more user friendly dispenser head. In view of this object, the dispenser head is adapted to maintain the closed position of the pressure medium valve in the disconnected state of the dispenser head and the extractor device.

By adapting the dispenser head to maintain the closed position of the pressure medium valve in the disconnected state of the dispenser head and the extractor device, it may be avoided that the user unintentionally opens the pressure medium valve in the disconnected state, and thereby unnecessary waste of pressure medium may be avoided.

In an embodiment, the pressure medium valve has a valve element displaceable between an open position and a closed position, the valve element is biased against its closed position, and the valve element is adapted to, at connection of the dispenser head with the extractor device, be displaced to its open position by abutment of the valve element against the extractor device. Thereby, the pressure medium valve may act independently of the operation of the hollow beverage piston, and consequently, operation of the hollow beverage piston in the disconnected state of the dispenser head will not result in leakage of pressure medium.

In an embodiment, the valve element of the pressure medium valve surrounds the hollow beverage piston and has an annular abutment surface adapted to abut the extractor device and an annular sealing surface that, in the closed position of the valve element, abuts an annular seat in the dispenser head. Thereby, a well-balanced operation of the valve element may be achieved, because the valve element in this way may be arranged symmetrically in relation to the beverage and pressure medium coupling between the dispenser head and the extractor device, so that forces at the connection may be evenly distributed.

In an embodiment, the valve element of the pressure medium valve is adapted to be biased towards its closed position at least partly by means of the pressure medium. Thereby, a sufficient force for closing the valve element may be obtained.

In a structurally advantageous embodiment, the valve element of the pressure medium valve has the form of at least a first annular part of a sealing ring, and the valve element is biased towards its closed position by means of at least a second annular and elastic part of the sealing ring. Thereby, the valve element may be formed integrally with a sealing ring sealing the connection between the dispenser head and the extractor device, and consequently a separate valve element and a separate sealing ring are not needed. In an embodiment, the sealing ring forms a first tubular part and a second tubular part having a greater inner diameter than an inner diameter of the first tubular part, in that the annular abutment surface of the valve element of the pressure medium valve forms a first end face of the second tubular part, in that the annular sealing surface of the valve element of the pressure me- dium valve forms a first end face of the first tubular part, in that the first tubular part has a second end face being opposed to its first end face and abutting an inner surface of the dispenser head, and in that the first end face of the second tubular part is displaced in axial direction away from the first tubular part. Thereby, the first tubular part may bias the valve element, which also forms part of the first tubular part, towards its closed position, and the second tubular part may act to displace the valve element by elastic compression of the first tubular part, when the second tubular part abuts the extractor device.

In an embodiment, the first tubular part has radially extending slots formed in its second end face and communicating with axially extending slots in an inner wall of the first tubular part, the radially and axially extending slots thereby forming part of the pressure medium passage. Thereby, a passageway for the beverage may be formed, and at the same time, the first tubular part may result more flexible at its second end face because of the radially extending slots, so that an even more suitable bias for the valve element may be obtained. The axially extending slots makes it possible to mount the sealing ring on a bushing of the dispenser head and at the same time provide a passageway for beverage at the inner wall of the sealing ring.

In a structurally advantageous embodiment, the first tubular part of the sealing ring is provided with an outer lip adapted to seal against an inner wall of the dispenser device when a pressure medium is supplied to the pressure medium inlet, and the annular abutment surface of the valve element of the pressure medium valve is adapted to, in the connected state of the dispenser head and the extractor device, form a sealing surface against the extractor device. The outer lip may in this way form a self-increasing sealing force, as the sealing force may increase as a result of increasing pressure of the pressure medium. The sealing force of the sealing surface against the extractor device may be self-increasing in the same way, as the pressure medium may contribute to pressing the sealing ring against the extractor device.

In an embodiment, the annular sealing surface of the valve element of the pressure medium valve is provided with a rib or notch fitting a corresponding rib or notch of a bushing of the dispenser head. Thereby, the sealing effect may be improved. In an embodiment, the annular abutment surface of the pressure medium valve is provided with a rib or notch fitting a corresponding rib or notch of the extractor device. Thereby, the sealing effect may be improved.

In an embodiment advantageous in terms of manufacture, the sealing ring is manufactured as an integral part from an elastic material. By producing the sealing ring as a single piece, it is also obtained that replacement of a worn out sealing ring by a new one is facilitated.

In an embodiment, the dispenser head is adapted so that, in the connected state of the dispenser head and the extractor device and the closed position of the hollow beverage piston, the pressure medium inlet communi- cates with the beverage outlet. Thereby, it is possible to empty the beverage line from the dispenser head to the tapping device by positioning the hollow beverage piston is in its closed position, in which the beverage extractor valve of the extractor device closes the beverage supply, and opening the tapping device until the pressure medium has pressed out the beverage remaining in the beverage line. This may be advantageous, for instance in the case of perishable beverages, such as beer, whereby the beverage line may then be emptied before a period during which no beverage is tapped, for instance when a bar closes down.

In a structurally advantageous embodiment, the bushing of the dis- penser head is provided with at least one radially extending slot connecting the pressure medium passage and the hollow beverage piston in the closed position of the hollow beverage piston. Thereby, the communication of the pressure medium inlet with the beverage outlet is facilitated, even in the case that the bushing abuts a sealing ring or other parts of the extractor device in the connected state of the dispenser head and the extractor device.

The present invention further relates to a method of connecting a dispenser head with an extractor device mounted in a beverage container, such as a beer keg, in which the beverage may be pressurized, whereby the dispenser head is connected with the extractor device, a hollow beverage piston is displaced axially from a closed position, in which a beverage extractor valve of the extractor device closes an outlet of a down tube, to an open position, in which the hollow beverage piston may convey beverage from the down tube of the extractor device to a beverage outlet of the dispenser head, and a pressure medium is supplied to the extractor device via a chamber enclosed by the dispenser head and the extractor device. The method according to the invention is characterized by that the pressure medium is supplied to the chamber enclosed by the dispenser head and the extractor device right at the connection of the dispenser head with the extractor device and before the displacement of the hollow beverage piston to its open position. Thereby, the above-mentioned advantages may be obtained.

In an embodiment, the hollow beverage piston opens out into the chamber enclosed by the dispenser head and the extractor device in the closed position of the hollow beverage piston. Thereby, it is possible to empty the beverage line from the dispenser head to the tapping device, as discussed above.

The invention will now be explained in more detail below by means of examples of embodiments with reference to the schematic drawing, in which Fig. 1 is a cross-sectional view of a dispenser head according to the invention,

Fig. 2 is a partly cross-sectional view of the dispenser head in Fig. 1 and a beverage container with an extractor device, before connection of these, whereby the beverage container is shown only in part, Fig. 3 is a perspective view of the dispenser head in Fig. 1 ,

Fig. 4 is a cross-sectional view on a larger scale of part of the dispenser head in Fig. 1 , before connection with the extractor device, Fig. 5 is a cross-sectional view on a larger scale of part of the dispenser head and extractor device in Fig. 2, after connection of these, in the closed position of the hollow beverage piston,

Fig. 6 is a cross-sectional view of the dispenser head and extractor de- vice corresponding to that of Fig. 5, in the open position of the hollow beverage piston,

Fig. 7 is a cross-sectional view of a housing and bushing of the dispenser head in Fig. 1 ,

Fig. 8 is a top view of a sealing ring of the dispenser head in Fig. 1 , and

Fig. 9 is an axial section along the line IX-IX of the sealing ring in Fig. 8.

Fig. 1 shows a dispenser head 1 according to the invention for connection with an extractor device 2 mounted in a beverage container 3; see Fig. 2. The extractor device 2 may, as shown, for instance, be threaded into the beverage container 3. The beverage container 3 shown is a beer keg, in which beer may be pressurized; however, the invention is just as well applicable to a dispenser head suitable for dispensing other kinds of pressurized beverages, such as soft drinks or the like. The dispenser head 1 comprises a housing 4 having a threaded male coupling part 5 for insertion into a threaded female coupling part 6 of the extractor device 2. Other suitable kinds of couplings may also be employed. The housing 4 further comprises a pressure medium inlet 7 for connection with a not shown source of a pressure medium, such as a CO₂ cylinder, in order to pressurize the beverage container. A hollow bev- erage piston 9 is arranged axially displaceably in the housing 4 and has, at a first end, a beverage outlet 8 for connection with a not shown tapping device, comprising a tapping cock, in order to dispense beverage from the beverage container by means of the tapping device. The beverage outlet 8 may be connected with the tapping device by means of a not shown beverage line. In the connected state of the dispenser head and the extractor device, the hollow beverage piston 9 is displaceable between an open position, in which it may convey beverage from a down tube 10 of the extractor device 2 to the beverage outlet 8, and a closed position, in which a beverage extractor valve

11 of the extractor device closes an outlet 12 of the down tube.

The hollow beverage piston 9 is displaceable by operation of a lever arm 13 by means of a handle 14 arranged at a first end 15 of the lever arm 13. At a second end 16, the lever arm 13 is pivotally joumalled in a bearing 17 of the housing 4, and a central part 18 of the lever arm 13 is engaged with a recess 19 in an outer wall of the hollow beverage piston 9, so that the piston is displaced when the lever arm is swung. The handle 14 may be locked in its lower position, whereby the hollow beverage piston 9 is in its open position, as shown in Fig. 6, by engagement of a locking tap 20 of the lever arm 13 with a recess 21 of the housing 4. The locking tap 20 is arranged axially displaceable in the lever arm 13 and biased by means of a spring 22 towards a position shown in Fig. 1. When the tap 20 is engaged in the recess 21 , it may be disengaged by displacement against the spring force by operation of a button 23 arranged pivotally in the handle 14 about an axis 24, see Fig. 3, and cooperating with the locking tap 20 in any suitable manner evident to the skilled person.

The hollow beverage piston 9 is, at a centre portion, sealed against the housing by means of an O-ring 25, and, at a second end, it is guided in a bushing 26 that is fixedly mounted in the housing 4 by means of a thread connection 27 and that is sealed against the housing by means of an O-ring 28. An end of the bushing 26 projects from the housing 4 centrally in the threaded male coupling part 5 and is provided with a radially outwards projecting shoulder 29 holding a sealing ring 30 in place in an annular recess 31 that is formed in the housing 4 so that it surrounds the bushing 26. The annular recess 31 communicates with the pressure medium inlet 7 by means of a channel 36.

The sealing ring 30 is composed by a first tubular part 32 and a second tubular part 33 having a greater inner diameter than an inner diameter of the first tubular part; see Figs. 8 and 9. The first tubular part 32 of the sealing ring 30 is provided with an outer lip 34 adapted to be pressed radially outwards and seal against an inner wall 35 of the annular recess 31 in the housing 4, when the pressure medium is supplied to the annular recess 31 from the pressure medium inlet; see Fig. 4. A first end face of the first tubular part 32 of the sealing ring forms an annular sealing surface 37 of a valve element 38 of a pressure medium valve 39. In a closed position of the valve element 38 shown in Fig. 4, the annular sealing surface 37 abuts an annular seat 40 on the radially outwards projecting shoulder 29 of the bushing 26 of the dispenser head 1. The annular sealing surface 37 is provided with a rib 41 sealing against the annular seat 40, and a not shown notch corresponding to the rib 41 may be provided on the annular seat 40. The sealing ring 30 may be supported by a metal ring 42 or the like located in a recess 43 formed be- tween the first tubular part 32 and a second tubular part 33.

The valve element 38 of the pressure medium valve 39 has the form of a first annular part of the sealing ring 30 and it is biased towards its closed position by means of a second annular and elastic part 44 of the sealing ring. This is achieved in that the first tubular part 32 of the sealing ring comprises the second annular and elastic part 44 and has a second end face 45 being opposed to its first end face and abutting an inner surface 46 of the annular recess 31. The valve element 38 is furthermore biased towards its closed position by means of the pressure medium loading the sealing ring 30 in the annular recess 31. Because the first tubular part 32 has radially extending slots 47 formed in its second end face 45 and communicating with axially extending slots 48 in an inner wall 49 of the first tubular part, the radially and axially extending slots form part of a pressure medium passage communicating with the pressure medium inlet 7 via the channel 36. In Fig. 4, showing the dispenser head 1 before connection with the extractor device 2, it is indicated by means of a fat, broken line that pressure medium is supplied through the pressure medium passage to the pressure medium valve 39 that is closed.

An annular abutment surface 50 of the valve element 38 of the pressure medium valve 39 forms a first end face of the second tubular part 33 of the sealing ring, and said first end face is positioned displaced in axial direc- tion away from the first tubular part 32. The annular abutment surface 50 is adapted to, in the connected state of the dispenser head 1 and the extractor device 2 shown in Fig. 5, form a sealing surface against the extractor device, whereby the sealing ring 30 seals the dispenser head 1 against the extractor device 2. The annular abutment surface 50 is provided with a rib 51 sealing against the extractor device 2, and a not shown notch corresponding to the rib 51 may be provided on the extractor device 2. At the connection of the dispenser head 1 and the extractor device 2, the annular abutment surface 50 of the valve element 38 is pressed against a face of the extractor device 2, whereby the sealing ring 30 is compressed in the direction of the annular recess 31 of the housing 4 that it is located in. Especially the second annular and elastic part 44 of the sealing ring is compressed, whereby the annular sealing surface 37 of the valve element 38 is displaced away from the annular seat 40 on the radially outwards projecting shoulder 29 of the bushing 26 of the dispenser head 1 , so that the pressure medium valve 39 is opened.

In Fig. 5, the hollow beverage piston 9 is in its closed position, in which the beverage extractor valve 11 of the extractor device is closed so that no beverage is supplied to the hollow beverage piston 9, and as indicated by means of a fat, broken line, the pressure medium is now supplied through the pressure medium valve 39 and through the hollow beverage piston 9 to the beverage outlet 8. If the tapping cock of the tapping device is opened, the tapping line may be emptied by the pressure medium blowing through it. It is noted that in this state, the radially outwards projecting shoulder 29 of the bushing 26 abuts a pressure medium valve element 52 of the extractor device, but nevertheless, the pressure medium is able to pass between these two elements through radially extending channels 53 formed in the radially outwards projecting shoulder 29; see Fig. 3. Furthermore, the pressure medium passes between a sealing ring 54 mounted at a second end of the hol- low beverage piston 9 and the pressure medium valve element 52 of the extractor device, as the sealing ring 54 is positioned at a distance from the pressure medium valve element 52. An end face 61 of the hollow beverage piston 9 is located at the second end of the piston and abuts, in the state shown in Fig. 5, a valve element 55 of the beverage extractor valve 11 of the extractor device. However, the pressure medium passes between through the hollow beverage piston 9, because there are provided two opposed, radially open openings 56 in said end face 61 of the piston. In order to prevent beverage from leaking from the dispenser head after disconnection from the extrac- tor device, a ball 60 is supported inside the hollow beverage piston 9 at the second end of the piston, thereby forming a non-return valve.

The valve element 55 of the beverage extractor valve 11 is biased against the pressure medium valve element 52 by means of a spring 57, thereby closing the beverage extractor valve 11 in the state shown in Fig. 5, so that no beverage may exit from the down tube 10. Furthermore, the pressure medium valve element 52 is biased against a valve seat 58 of the outlet 12 of the down tube by means of a spring 59.

In Fig. 6, the hollow beverage piston 9 has been displaced to its open position by operation of the handle 14. Thereby, the sealing ring 54 of the hollow beverage piston 9 has reached abutment against the pressure medium valve element 52 and thereby displaced the latter against its springload to its open position, in which the pressure medium may pass from the dispenser head to the beverage container, as indicated by means of the fat, broken line. The passage of pressure medium between the sealing ring 54 and the pressure medium valve element 52 has at the same time been closed, so that the pressure medium will press the beverage up through the down tube 10. As the valve element 55 of the beverage extractor valve 11 has been displaced to its open position by means of the hollow beverage piston 9, the beverage is allowed to exit from the down tube 10 and enter the hollow beverage piston 9 through the radially open openings 56 of the piston, and subsequently flow through the piston to the beverage outlet 8 and further on therefrom to the tapping device.

It should be noted that the valve element of the pressure medium valve may be composed of more parts, for instance a sealing ring and an intermediate actuation element adapted to abut the extractor device and thereby displace the sealing ring. In fact, the valve element does not have to be concentric with the hollow beverage piston 9, and it may have the form of any element suitable for opening and closing the passage of pressure medium through the dispenser head. Furthermore, according to the invention, the dispenser head may be adapted to maintain the closed position of the pressure medium valve in the disconnected state of the dispenser head and the extractor device in a different way than explained above. For instance, the pressure medium valve may be actuated by displacement of the hollow beverage piston, whereby the dispenser head may be so designed that it cannot be disconnected from the extractor device before the hollow beverage piston is displaced to its closed position, and whereby a locking element may be provided that locks the hollow beverage piston in its closed position when the dispenser head is disconnected from the extractor device. Upon displacement of the hollow beverage piston to its open position, such a force may be exerted on the coupling parts 5, 6 that they cannot be disconnected, and said locking element may be adapted to abut the extractor device in the connected state of the dispenser head and the extractor device.

Claims

1. A dispenser head (1) for connection with an extractor device (2) mounted in a beverage container (3), such as a beer keg, in which the beverage may be pressurized, the dispenser head comprising a pressure medium inlet (7) communicating with a pressure medium passage for supply of a pressure medium, such as CO₂, to the beverage container, a pressure medium valve (39) being adapted to open and close the beverage passage, a beverage outlet (8) for delivery of beverage from the beverage container (3) to a tapping device, and a hollow beverage piston (9) arranged to, in the connected state of the dispenser head (1) and the extractor device (2), be axially displaceable between an open position, in which it may convey beverage from a down tube (10) of the extractor device (2) to the beverage outlet (8), and a closed position, in which a beverage extractor valve (11) of the extractor device (2) closes an outlet (12) of the down tube (10), the dispenser head (1) is adapted to maintain the closed position of the pressure medium valve (39) in the disconnected state of the dispenser head (1) and the extractor device (2) characterized in that the pressure medium valve (39) has a valve element (38) displaceable between an open position and a closed position, in that the valve element (38) is biased against its closed position, and in that the valve element (38) is adapted to, at connection of the dispenser head (1) with the extractor device (2), be displaced to its open position by abutment of the valve element (38) against the extractor device

(2).

2. A dispenser head according to claim 1 , characterized in that the valve element (38) of the pressure medium (39) valve surrounds the hollow beverage piston (9) and has an annular abutment surface (50) adapted to abut the extractor device (2) and an annular sealing surface (37) that, in the closed position of the valve element (38), abuts an annular seat (40) in the dispenser head (1).

3. A dispenser head according to claim 2, characterized in that the valve element (38) of the pressure medium valve (39) is adapted to be biased towards its closed position at least partly by means of the pressure medium.

4. A dispenser head according to claim 2 or 3, characterized in that the valve element (38) of the pressure medium valve (39) has the form of at least a first annular part of a sealing ring (30), and in that the valve element (38) is biased towards its closed position by means of at least a second annular and elastic part (44) of the sealing ring (30).

5. A dispenser head according to claim 4, characterized in that the sealing ring (30) forms a first tubular part (32) and a second tubular part (33) having a greater inner diameter than an inner diameter of the first tubular part (32), in that the annular abutment surface (50) of the valve element (38) of the pressure medium valve (39) forms a first end face of the second tubular part (33), in that the annular sealing surface (37) of the valve element (38) of the pressure medium valve (39) forms a first end face of the first tubular part (32), in that the first tubular part (32) has a second end face (45) being opposed to its first end face and abutting an inner surface (46) of the dispenser head (1), and in that the first end face of the second tubular (33) part is displaced in axial direction away from the first tubular part (32).

6. A dispenser head according to claim 5, characterized in that the first tubular part (32) has radially extending slots (47) formed in its second end face (45) and communicating with axially extending slots (48) in an inner wall (49) of the first tubular part (32), the radially and axially extending slots thereby forming part of the pressure medium passage.

7. A dispenser head according to claim 5 or 6, characterized in that the first tubular part (32) of the sealing ring (30) is provided with an outer lip (34) adapted to seal against an inner wall (35) of the dispenser device (1) when a pressure medium is supplied to the pressure medium inlet (7), and in that the annular abutment surface (50) of the valve element (38) of the pressure medium valve (39) is adapted to, in the connected state of the dispenser head (1) and the extractor device (2), form a sealing surface against the extractor device (2).

8. A dispenser head according to any one of the claims 2 to 7, characterized in that the annular sealing surface (37) of the valve element (38) of the pressure medium valve (39) is provided with a rib (41) or notch fitting a corresponding rib or notch of a bushing (26) of the dispenser head

(1)-

9. A dispenser head according to any one of the claims 2 to 8, characterized in that the annular abutment surface (50) of the pressure medium valve (39) is provided with a rib (51) or notch fitting a corresponding rib or notch of the extractor device (2).

10. A dispenser head according to any one of the preceding claims, characterized in that the sealing ring (30) is manufactured as an integral part from an elastic material.

11. A dispenser head according to any one of the preceding claims, characterized in that the dispenser head (1) is adapted so that, in the connected state of the dispenser head (1) and the extractor device (2) and the closed position of the hollow beverage piston (9) , the pressure medium inlet (7) communicates with the beverage outlet (8).

12. A dispenser head according to any one of the claims 8 to 10, characterized in that the bushing (26) of the dispenser head (1) is provided with at least one radially extending slot (53) connecting the pressure medium passage and the hollow beverage piston (9) in the closed position of the hollow beverage piston.

13. A method of connecting a dispenser head (1) with an extractor device (2) mounted in a beverage container (3), such as a beer keg, in which the beverage may be pressurized, whereby the dispenser head (1) is connected with the extractor device (2), a hollow beverage piston (9) is displaced axially from a closed position, in which a beverage extractor valve (11) of the extractor device (2) closes an outlet (12) of a down tube (10), to an open position, in which the hollow beverage piston (9) may convey beverage from the down tube (10) of the extractor device (2) to a beverage outlet (8) of the dispenser head (1), and a pressure medium is supplied to the extractor device (2) via a chamber enclosed by the dispenser head (1) and the extractor device (2), characterized by that the pressure medium is supplied to the chamber enclosed by the dispenser head (1) and the extractor device (2) right at the connection of the dispenser head (1) with the extractor device (2) and before the displacement of the hollow beverage piston (9) to its open position.

14. A method according to claim 13, characterized by that the hollow beverage piston (9) opens out into the chamber enclosed by the dispenser head (1) and the extractor device (2) in the closed position of the hollow beverage piston (9).