GB2192860A

GB2192860A - Dispensing carbonated beverages

Info

Publication number: GB2192860A
Application number: GB08716663A
Authority: GB
Inventors: Paul Betteridge; Peter Thomas Foster; William Little
Original assignee: Bass PLC
Current assignee: Bass PLC
Priority date: 1986-07-15
Filing date: 1987-07-15
Publication date: 1988-01-27
Also published as: GB2192860B; GB8617225D0; GB8716663D0

Abstract

Dispensing/metering apparatus comprises a cylinder (13) containing a reciprocatory piston (14). Outlet ducting (18,19,22) leads from the cylinder to a dispense station (24) which includes parallel pathways (25 and 26) controlled by valves (29 and 30) and leading to adjacent nozzles (27 and 28). One pathway (26) contains a constriction (31) which disturbs beer flowing through it and helps create a head on the dispensed beer. During the major part of its movement the piston dispenses undisturbed beer through the pathway (25) but when detected by an initial sensor (33 or 34) the beer is diverted through the pathway (26) and is dispensed in a more disturbed, frothy form. When the piston reaches a final sensor (32 or 35) the valves (29 and 30) at the dispense station close and the piston is brought to a halt by the beer ahead of it. Consequently there is no reduction in the pressure of the beer in the outlet ducting and bubble- formation is thus avoided. The speed of movement of the piston is reduced when disturbed beer is being dispensed, so that it approaches the final sensor slowly and the accuracy of the volume of the dispensed beer is thus increased. <IMAGE>

Description

SPECIFICATION Dispensing carbonated beverages This invention relates to the dispensing of carbonated beverages. It is particularly, though not exclusively, concerned with the dispensing of beer.

It is known to dispense liquids from metering apparatus of a kind comprising a metering cylinder containing a reciprocable piston, liquid being introduced into the interior of the cylinder to one side of the piston and then being discharged from the cylinder by movement of the piston through a predetermined distance along the cylinder. Such apparatus may be single-acting, in which case liquid is dispensed from the cylinder from one side only of the piston, or double-acting, in which case liquid is dispensed from the cylinder from one side of the piston and from the other side of the piston alternatively.

In a known method of dispensing beer, use is made of a meter which measures out a predetermined quantity, usually half a pint (284.1 ml), of beer. One form of meter, which is double-acting, comprises a cylinder containing a reciprocable piston which carries a peripheral seal that engages the bore of the cylinder and prevents the passage of beer past the piston in the cylinder. In use, a first quantity of beer is introduced from a keg or other source of supply into the cylinder from a first end thereof. This causes the piston to move from a first end to a second end of the cylinder. That first end of the cylinder is then connected to outlet ducting leading to a dispense head. A second quantity of liquid is introduced into the cylinder from the second end thereof, causing the piston to return to the first end.

That return movement of the piston causes the first quantity of beer to be discharged from the cylinder into the outlet ducting and thus causes an equal quantity of beer to be dispensed from the dispense head. After the piston has stopped at the first end of the cylinder, the second end of the cylinder is connected to the outlet ducting, while the first end is reconnected to the source of beer. As beer flows into the cylinder at the first end again, the second quantity of beer, which is of the same volume as the first quantity, is discharged into the outlet ducting. The cycle can then be repeated indefinitely.

In order to provide a positive action and to retain the beer under pressure in the outlet ducting, thereby preventing fobbing (i.e. the release of carbon dioxide from solution), there is an electrically controlled dispense valve at the dispense head. The dispense valve is normally closed, but when it is desired to dispense a quantity of beer, a button is pressed which gives rise to gn electrical signal which opens the dispense valve and at the same time initiates the entry of beer from the source into one end of the cylinder. Beer leaves the cylinder from the other end thereof, as described above, and flows into the outlet ducting. A weighted slug, movable in a vertically disposed part of the outlet ducting, is carried to an upper position by the flow of beer, but when flow ceases the slug drops gravitationally to a lower position.The slug contains a magnet which co-operates with a reed switch. When the slug is in its upper position the reed switch is operated and gives rise to an electrical signal which maintains the dispense valve open, but when the slug is in its lower position the reed switch returns to its inoperative state. The resultant electrical signal causes closure of the dispense valve.

This method can often be used satisfactorily, but problems may arise when using beer containing dissolved nitrogen or when using beer containing a relatively high concentration of carbon dioxide. Nitrogen is relatively insoluble in beer but a small proportion can be dissolved in beer using appropriate techniques.

When beer containing dissolved nitrogen and carbon dioxide is dispensed, much of the nitrogen comes out of solution and in doing so it appears to assist in causing carbon dioxide to come out of solution. The gases assist in the formation of a head on the beer, the presence of the nitrogen tending to give rise to small bubbles, of uniform size, that are relatively long-lasting.

Now when beer containing dissolved nitrogen is dispensed by the method outlined above, there is a tendency for unwanted bubbles to form in the outlet ducting. This phenomenon arises in the following way.

While the piston is moving along the cylinder, it causes beer to be discharged into the outlet ducting, and the entire quantity of beer in the ducting is caused to move relatively rapidly towards the dispense head. Then, when the piston is suddenly brought to a halt, by striking one end of the cylinder or by striking some other stop, the momentum of the volume of beer in the outlet ducting tends to cause that volume of beer to continue to move towards the dispense head, even though the dispense valve has closed. As it is usual for at least part of the outlet ducting to be made of resilient plastics material, there is a slight momentary enlargement of the ducting near the dispense head and a consequent reduction in pressure in that part of the outlet ducting immediately adjacent to the cylinder.

The pressure reduction may well be a sharp one, and the pressure may even fali below atmospheric pressure. That reduction in pressure encourages gas to come out of solution.

If the beer contains no dissolved nitrogen, and contains only a relatively low concentration of carbon dioxide, no bubbles may form.

But even if some bubbles of carbon dioxide do form it is often of no consequence as the restoration of pressure that rapidly occurs when the ducting contracts, and equilibrium is restored, causes most or all of the carbon dioxide to become redissolved. If the beer contains dissolved nitrogen, however, the nitrogen that comes out of solution is not redissolved when the pressure rises again. Moreover, the nitrogen coming out of solution tends to cause an excess of carbon dioxide to come out of solution as well, so that there is less likelihood of this excess carbon dioxide being redissolved when the pressure is restored. It is usual for the meter to be disposed in a cellar, so that the bubbles in the outlet ducting tend to rise and congregate at or near the dispense head. The bubbles are then swept out of the head when the next volume of beer is dispensed.Their discharge from the dispense head often resembles a small explosion, so that it is highly desirable to take steps to avoid the formation and discharge of those bubbles. Even- if the arrangement is such that the bubbles congregate elsewhere in the system, they usually give rise to difficulties.

Similar problems also tend to occur with beverages that contain no dissolved nitrogen but which contain such a relatively high concentra tion -of carbon dioxide that the gas tends to come out of solution to an excessive extent when dispensed with the aid of apparatus of the conventional kind described above. For example, those problems may arise when dispensing a beer containing a volume of carbon dioxide which in its gaseous form is equal to two and a half times the volume of the liquid beer.

The present invention aims to provide apparatus which, in use, prevents or at least reduces the formation of bubbles that become trapped within the apparatus in the manner outlined above. At the same time the apparatus in such that, in use, it causes or improves the formation of a head on the dispensed beverage.

From a first aspect the present invention consists in apparatus for use in dispensing a carbonated beverage comprising a metering cylinder containing a reciprocable piston, a dispense station and outlet ducting leading to the dispense station from a part of the interior of the cylinder that lies to one side of the piston and is bounded by one end of the cylinder so that, in use, as the piston moves along the cylinder towards said one end of the cylinder it can discharge beverage from the interior of the cylinder into the outlet ducting, to be dispensed from the dispense station, the apparatus also including sensing means operative to give rise to an initial signal when the piston reaches a predetermined initial position in the cylinder in the course of its movement towards said one- end of the cylinder, that initial signal initiating increased disturbance of the beverage being discharged from the- dispense station so as to cause or improve the formation of a head on the dispensed beverage, and operative to give rise to a final signal when the piston reaches a.pre- determined final position in the cylinder, which is closer to said one end of the cylinder than is the initial position, that final signal bringing about closure of the outlet ducting at the dispense station so that the flow of beverage from the cylinder into the outlet ducting ceases and the piston is brought to a halt by the beverage as a consequence of that closure.

From a second aspect the present invention consists in apparatus for use in dispensing a carbonated beverage comprising a metering cylinder containing a reciprocable piston and outlet ducting leading to the dispense station from parts of the interior of the cylinder that lie on either side of the piston and are bounded by the opposite ends of the cylinder so that, in use, as the piston moves along the cylinder towards either end thereof it can discharge beverage from the interior of the cylinder into the outlet ducting, to be dispensed from the dispense station, the apparatus also including first sensing means associated with a first end of the cylinder and second sensing means associated with a second end of the cylinder, each such sensing means being operative to give rise to an initial signal when the piston reaches an associated predetermined initial position in the cylinder in the course of its movement towards the associated end of the cylinder, that initial signal initiating increased disturbance of the beverage being dispensed from the dispense station so as to cause or improve the formation of a head on the dispensed beverage, and being operative to give rise to a final signal when the piston reaches an associated predetermined final position in the cylinder, which is closer to the associated end of the cylinder than is the associated initial position, that final signal bringing about closure of the outlet ducting at the dispense station so that the flow of beverage from the cylinder into the outlet ducting ceases and the piston is brought to a halt by the beverage as a consequence of that closure.

In use, when the outlet ducting is closed at the dispense station, the beverage moving in the outlet ducting can momentarily continue to flow very slightly, as described above, but the piston, too, can continue to move very slightly beyond its predetermined final position so that a very sharp reduction of pressure adjacent to the piston is avoided, and the consequent release of dissolved gas is at least largely prevented.

it will be understood that the volume of beverage dispensed on each operation of the apparatus is determined by the distance travelled by the piston during that operation, and that for consistent results to be obtained it is necessary to ensure, among other things, that when the piston carries out a series of operations, in each of which it moves in one direction, the piston finally becomes stationary, at the end of each operation, in a substantially constant position. Somewhat surprisingly it has been found that a degree of consistency can be achieved, with the aid of the present invention, that is often higher than the degree of consistency achieved with conventional apparatus of the kind described above and in which the piston ceases its movement as the result of its striking a stop, such as an end plate of the cylinder.

The arrangement is preferably such that there is a reduction in the rate of flow of beverage when the disturbance of the beverage is increased so that the rate of movement of the piston as it travels from initial to final positions is also correspondingly reduced.

The fact that the piston is moving more slowly when it reaches its predetermined final position on each occasion assists in ensuring a high degree of consistency in the volume of beverage dispensed on each operation of the apparatus.

As in the known types of apparatus, it is preferred to cause movement of the piston by applying to one side of the piston beverage under a substantially constant pressure.

The outlet ducting preferably divides into two valve-controlled pathways, a first of which is such that beverage flowing through it in use is relatively undisturbed, and a second of which is such that beverage flowing through it in use is more highly disturbed, an initial signal causing the flow of beverage to be diverted through said second pathway.

In an alternative arrangement the outlet ducting consists of only a single pathway, the occurrence of the initial signal causing a restrictor to be inserted into the pathway so that beverage passing through the passageway thereafter is more highly disturbed.

The sensing means or each sensing means is preferably adjustable so that the distance between the predetermined initial and final positions of the piston- can be altered.

The sensing means or each sensing means preferably comprises an initial sensor operative to give rise to said jnitial signal and a final sensor operative to rise to said final signal.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing which is a schematic representation of apparatus for use in dispensing beer.

The beer to be dispensed is stored in a keg 1 and contains nitrogen in solution in addition to carbon dioxide. Carbon dioxide under pressure is fed from a cylinder 2 through a head 3 into the top space of the keg in the conventional manner. The head 3 carries a spear (not shown) which extends to a location near the bottom of the keg. Beer can leave the keg through the spear and through the head 3 and can pass into ducting 4 which leads to an electrically-operated pump 5 and a non-return valve 6. It can pass thence into inlet ducting 7 which divides at 8 into alternative inlet ducts 9 and 10 under the control of electrically controlled on/off valves 11 and 12 respectively.

The inlet ducts lead to inlet ports in opposite end plates of a cylinder 13 which is made of a transparent plastics material and which contains a piston 14 reciprocable in the cylinder.

The periphery of the piston carries an annular seal 15 which engages the bore of the cylinder and prevents beer passing from one side of the piston to the other. Stainless steel discs 18 and 17 are secured to the ends of the piston, the peripheral edges of the discs being polished so as to be reflective.

An outlet port is also formed in each of the end plates of the cylinder. The outlet ports lead to outlet ducting comprising outlet ducts 18 and 19 containing electrically controlled on/off valves 20 and 21 respectively. The ducts 18 and 19 join at 22 and lead to a common duct 23 made of a flexible and resilient plastics material. The apparatus described thus far is situated in a cellar. The duct 23 extends upwards from the cellar to a dispense station 24 in a bar above the cellar.

At the dispense station 24 the duct 23 divides to form two pathways 25 and 26 leading to dispense nozzles 27 and 28 respectively, which are closely adjacent to each other. The pathways contain electrically operated on/off valves 29 and 30 respectively.

The pathway 25 is such that when the valve 29 is open beer can flow through the pathway and be discharged from the nozzle 27 in an undisturbed state. The pathway 26, however, contains a constriction 31 so that, when the valve 30 is open, beer flowing through the pathway and discharged from the nozzle 28 being relatively highly disturbed.

Adjacent to the cylinder 13 are mounted two sensing means, one comprising an initial sensor 33 and a final sensor 32 and the other comprising an initial sensor 34 and a final sensor 35. Each sensor comprises an infra-red transmitter and a receiver. The arrangement is such that in normal circumstances radiation from the transmitter is directed into the cylinder and does not fall on the receiver, but when either of the discs 16 and 17 is close to the sensor radiation from the transmitter is reflected from the edge of the disc onto the receiver and an electrical signal is generated.

The apparatus operates in the following manner. It is assumed that at the start all the valves are closed, that beer under pressure occupies all the ducts and the interior of the cylinder and that the piston is at one end of its travel, as illustrated.

When it is desired to dispense a quantity of beer a switch (not shown) is operated by the depression of a button at the dispense station 24. This causes the pump 5 to start operation and also opens the valves 12, 20 and 29.

Beer is therefore pumped through the inlet duct into the cylinder from its right hand end, and the piston moves to the left, causing beer previously in the cylinder to be discharged through the outlet duct 18, the passageway 25 and the nozzle 27. The piston moves under the influence of a substantially constant pressure of beer applied to it by the pump 5.

When the piston reaches a position (a predetermined initial position) in which the disc 16 is aligned with the sensor 33, that sensor generates an initial signal which opens the valve 30 and closes the valve 29. The remaining beer is thus discharged through the pathway 26, the constrictor 31 and the nozzle 28. Being more highly disturbed the- beer tends to form a head. When the piston reaches a predetermined final position in which the disc 16 is aligned with the sensor 32, that sensor generates a final signal which closes the valve 30 and thus brings the piston to rest before it has reached the adjacent end of the cylinder, with the- advantages described above. Very shortly afterwards, when pressure equilibrium has been restored, the valves 12 and 20 are closed, and the pump is switched off.Beer downstream of the non-return valve 6 remains under sufficient pressure to maintain the dissolved gases in solution. When the button is next depressed a similar sequence of events occurs, but the valves 11 and 21 open instead of the valves 10 and-20 so that the piston moves to the right. The piston, reaching an initial position in which the disc 17 is in alignment with the sensor 34, causes the generation of an initial signal that brings about the closure of the valve 29 and the opening of the valve 30, and its reaching a final position, in which the disc 17 is in alignment with the sensor 35, causes the generation of a final signal that brings about the closure of the valve 30. The apparatus is finally in the same state as that in which it started and is thus ready for a repetition of the operating cycle.

Operation of the pump 5 is conveniently controlled by a pressure switch responsive to the pressure of the peer on the downstream side of the pump, the arrangement being such that the pump operates until the pressure has increased to a predetermined value.

It will be obvious that the actual quantity of beer dispensed on each depression of the button is determined by the spacing between the sensors 32 and 35 and by the distance between the discs 16 and 17. In order to prevent an operator attempting to vary the quantity of beer dispensed, steps would normally be taken to prevent-the spacing between the sensors 32 and 35 being altered by an unauthorised person. On the other hand, the positions of the sensors 33 and 34 may be adjustable so as to enable the proportion of beer that is disturbed to be varied;

Claims

1. Apparatus for use in dispensing a carbonated beverage comprising a metering cylinder containing a reciprocable piston, a dispense station and outlet ducting leading to the dispense station from a part of the interior of the cylinder that lies to one side of the piston and is bounded by one end of the cylinder so that, in use, as the piston moves along the cylinder towards said one end of the cylinder it can discharge beverage from the interior of the cylinder into the outlet ducting, to be dispensed from the dispense station, the apparatus also including sensing means operative to give rise to an initial signal when the piston reaches a predetermined initial position in the cylinder in the course of its movement towards said one end of the cylinder, that initial signal initiating disturbance of the beverage being discharged from the dispense station so as to cause or improve the formation of a head on the dispensed beverage, and operative to give rise to a final signal when the piston reaches a predetermined final position in the cylinder, which is closer to said one end of the cylinder than is the initial position, that final signal bringing about closure of the outlet ducting at the dispense station so that the flow of beverage from the cylinder into the outlet ducting ceases and the piston is brought to a halt by the beverage as a consequence of that closure.

2. Apparatus for use in dispensing a carbonated beverage comprising a metering cylinder containing a reciprocable piston and outlet ducting leading to the dispense station from parts of the interior of the cylinder that lie on either side of the piston and are bounded by the opposite ends of the cylinder so that, in use, as the piston moves along the cylinder towards either end thereof it can discharge beverage from the interior of the cylinder into the outlet ducting, to be dispensed from the dispense station, the apparatus also including first sensing means associated with a first end of the cylinder and second sensing means associated with a second end of the cylinder, each such sensing means being operative to give rise to an initial signal when the piston reaches an associated predetermined initial position in the cylinder in the course of its movement towards the associated end of the cylinder, that initial signal initiating increased disturbance of the beverage being dispensed from the dispense station so as to cause or improve the formation of a head on the dispensed beverage, and being operative to give rise to a final signal when the piston reaches an associated predetermined final position in the cylinder, which is closer to the associated end of the cylinder than is the associated initial position, that final signal bringing about closure of the outlet ducting at the dispense station so that the flow of beverage from the cylinder into the outlet ducting ceases and the piston is brought to a halt by the beverage as a consequence of that closure.

3. Apparatus according to either of claims 1 and 2 in which the arrangement is such that there is a reduction in the rate of flow of beverage when the disturbance of the beverage is increased so that the rate of movement of the piston as it travels from initial to final positions is also correspondingly reduced.

4. Apparatus according to any one of the preceding claims in which the outlet ducting divides into two valve-controlled pathways, a first of which is such that beverage flowing through it in use is relatively undisturbed, and a second of which is such that beverage flowing through it in use is more highly disturbed, an initial signal causing the flow of beverage to be diverted through said second pathway.

5. Apparatus according to any one of the preceding claims in which the sensing means or each sensing means is adjustable so that the distance between the predetermined initial and final positions of the piston can be altered.

6. Apparatus according to any one of the preceding claims in which the sensing means or each sensing means comprises an initial sensor operative to give rise to said initial signal and a final sensor operative to rise to said final signal.

7. Apparatus for use in dispensing a carbonated beverage substantially as hereinbefore described with reference to the accompanying drawing.