GB2265138A

GB2265138A - Liquid dispenser

Info

Publication number: GB2265138A
Application number: GB9206231A
Authority: GB
Inventors: Pius Thomas Merton; Terence Percy Michael Pellowe
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-03-21
Filing date: 1992-03-21
Publication date: 1993-09-22
Also published as: GB9206231D0

Abstract

A dispenser for repeatedly discharging a predetermined volume of liquid such as beer has a closed cylinder 10 in which is mounted a freely-movable piston 12 internally carrying a magnet 14. Reed switches 15 and 16 are mounted at the two ends of the cylinder to detect the presence of the piston at one end or the other of the cylinder. Each end of the cylinder has a respective port 17 leading to a respective two-way valve 13 such that one end of the cylinder may be connected a source of pressurised liquid and the other end of the cylinder to an outlet, and vice versa. The valves 18 are automatically changed over in anti-phase by a controller 24, triggered whenever a predetermined volume is to be dispensed. When triggered, the valves are changed-over, to cause the piston to perform another stroke. <IMAGE>

Description

LIQUID DISPENSER This invention relates to a liquid dispenser and in particular to apparatus arranged to dispense a predetermined quantity of liquid upon operation thereof.

In many industries and trades, it is necessary to be able to dispense a predetermined volume of liquid from time to time. There have been innumerable proposals for apparatus able to perform this function and the selection of appropriate apparatus depends upon the particular liquid which is to be dispensed, the reason for dispensing the liquid, the volume to be dispensed, and so on.

There is a particular problem in the licensing trade, where alcoholic beverages are required by law (in the United Kingdom) to be dispensed in certain fixed volumes. In the case of spirits, these are dispensed in licensed premises through so-called "optics" which pre-fill from an inverted bottle and which, when actuated, dispense the pre-filled volume.

In the case of beers, ales, lager, cider, wine or other relatively low strength beverages (hereinafter referred to simply as "beer"), it is the conventional practice to discharge the beverage into a glass of or marked with a known volume, the glass being used as the measure for the amount dispensed.

There have been proposals for apparatus for use in licensed premises which are arranged to dispense a predetermined volume (and usually half-pint) of beer on demand. Such apparatus employs a pump to force the liquid under pressure through a measuring chamber, the apparatus having a complex control system to actuate the pump when the beer is to be dispensed, as well as various control valves. The control system has to be linked back to the dispensing point (usually a bar counter) which may be some distance from the dispensing apparatus. Such apparatus is thus relatively expensive to install and its reliability may not be particularly good.

It is a principal object of the present invention to provide apparatus which is adapted to dispense on demand a predetermined volume of liquid, which apparatus is particularly - but not exclusively suitable for use in licensed dispensing alcoholic beverages such as beer, lager, cider and the like.

According to the present invention, there is provided apparatus for dispensing a predetermined volume of liquid, comprising an inlet for liquid under pressure, an outlet for dispensed liquid, a closed cylinder having a freely-slidable piston mounted therein, detecting means for the presence of the piston at or adjacent either of the two ends of the cylinder and to provide a respective output consequent thereon, the two ends of the cylinder each having at least one port to permit the flow of liquid into and out of the cylinder, there being an electrically-controlled valve associated with each port, and an electrical controller responsive to the output of the detecting means and controlling the operation of said valves dependent thereon so as alternately to connect the inlet to one end of the cylinder and the outlet to the other end thereof, and vice versa.

It will be appreciated that apparatus of this invention particularly lends itself for use in the licensing trade, in that the liquid inlet may be connected to a keg of beer (as defined hereinbefore) to which is supplied gas under pressure so as to force beer out of that keg (a so-called "top-pressure" system). The outlet for liquid may be connected to the pipeline to the bar tap; there is no need for any other alterations to be made to an existing installation for within the installation. Thus, the apparatus may be made self-contained and requiring merely a power source for the control circuit.

Though the invention will particularly be described hereinafter with reference to its use in dispensing alcoholic beverages such as beer, it will be appreciated that it may be employed for dispensing any liquid in predetermined volumes. All that is necessary is to connect a pressurised source of the liquid to the apparatus inlet, and to connect to a tap to the apparatus outlet; each time the tap is opened, a predetermined quantity will be dispensed unless of course the tap is closed early.

It is preferred for the closed cylinder to have at least its cylindrical wall made of a transparent material such as glass, so that the operation of the apparatus may be observed, and in particular the proper filling of the cylinder to each side of the piston, upon operation of the apparatus. Though a separate inlet port and outlet port may be provided at each end of the cylinder, it is preferred for there to be a single port at each end, and for each such port to be fitted with a two-way electrically operated valve whereby either the liquid inlet or the liquid outlet is connected alternatively to the port depending upon the setting of the electrically-controlled valve for the time being. Conveniently, each such a valve comprises a solenoid valve.

The volume dispensed on each operation of the apparatus may be varied by changing the axial thickness of the piston, or the diameter of the cylinder (and piston). Of course, both possibilities may be employed to give the required predetermined volume for dispensing.

The detection of the piston at or adjacent each end of the cylinder could be performed in a variety of ways. For example, in the case of a transparent cylinder, an optical or infra-red detector may be provided. Preferably however there is a magnet mounted on the piston, and at or adjacent each end of the cylinder, there is an element such as a reed switch which responds to the magnetic lines of force emanating from the magnet on the piston.

The controller is advantageously arranged to cause operation of the valves to reverse the liquid connections to the cylinder only after a pre-set delay following the detection of the presence of the piston at or adjacent an end of the cylinder. Provided that the pre-set delay is sufficiently long, this will ensure that the piston may move fully to the end of its stroke, should the detection of the piston occur before the piston reaches the end of its stroke. Preferably, however, the delay is set significantly longer than that, so that the apparatus does not re-set to dispense a second predetermined volume immediately after dispensing a first volume.This then gives the operator a chance to close the tap controlling flow of liquid from the outlet if only a single predetermined volume is to be dispensed; if however the tap is left open, then after the pre-set delay the apparatus will dispense a second predetermined volume, following which there is a further delay before a third predetermined volume following which there will be a further delay before a third predetermined volume is to be dispensed, and so on. Typically, a suitable delay for this purpose might be in the range of from 2 to 10 seconds.

The controller may include a counter, in order to count the number of predetermined volumes of liquid dispensed by the apparatus. In this way, accurate stock records may be maintained.

Changing over from one keg to another may simply be achieved with apparatus of this invention, by providing a further two-way valve on the liquid inlet, whereby that liquid inlet may be connected selectively to either of two separate kegs. Such a valve may also be electrically controlled, and in this case the control of that valve may be performed by the controller, monitoring the movement of the piston under liquid pressure. In the event that neither piston detector detects the presence of the piston at either end of the cylinder after some pre-set time interval, then the two-way valve could automatically be operated to connect the inlet to a second, fresh keg.

Alternatively, automatic change-over could be performed by monitoring the count of the number of predetermined volumes dispensed since the last change-over, coupled with the knowledge of the number of volumes which should be dispensed from a fresh keg.

Yet another automatic method of detecting the need to effect a change-over from one keg to another would be to provide in the inlet pipeline a float chamber and through which the beer passes before entering the cylinder of the dispensing apparatus. By providing a float within that chamber and monitoring the position of that float, an output can be obtained to cause the change-over valve to operate. The float chamber and float may be similar to the dispensing cylinder and piston except that the float should be loose fit within the float chamber, and the axis of the float chamber must be essentially vertical, whereas the axis of the dispensing cylinder need not be vertical - for example, it could be horizontal.

By way of example only, one specific embodiment of apparatus for dispensing predetermined volumes of beer and constructed and arranged in accordance with the present invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 diagrammatically shows the apparatus; and Figure 2 is a block diagram of the dispenser controller.

The embodiment of dispensing apparatus shown in the drawings is intended to be fitted in a pipeline from a beer cellar wherein are stored kegs of beer supplied with top pressure to drive the beer along the pipeline to a bar, where the beer is served.

The apparatus comprises a glass cylinder 10 fitted with end caps 11, and having a piston 12 slidably mounted therewithin. Two O-rings 13 are fitted into grooves in the piston, so as to effect a seal between the piston and the inner wall of the cylinder 10.

Mounted within the piston 12 is a magnet 14, and there is provided on the cylinder 10 a pair of reed limit switches 15 and 16, one disposed at each end of the cylinder, respectively. The cylinder should be capable of being sealed by local authorities, to certify the dispensing volume.

Each end cap 11 has a respective port 17, to which is connected a two-way valve 18, operated by a solenoid 19. In one setting, valve 18 connects port 17 to an inlet pipe 20 and in the other setting to an outlet pipe 21. The two inlet pipes 20 are coupled together to a common inlet 22, and the two outlet pipes 21 are coupled together to a common outlet 23.

The two limit switches 15 and 16 are connected to a controller 24, which also supplies drive current for the two solenoids 19. Figure 2 shows the block diagram of the controller 24 and it can be seen that this includes a timer 25 operating a driver circuit 26 which supplies the drive current for the solenoid 19. A counter 27 is also provided, which is incremented each time the driver circuit 26 is triggered by the timer 25. The valves 18 are arranged so that only one is actuated by its solenoid 19 at any one time; in this way, when one valve 18 connects inlet pipe 20 to port 17, the other valve 18 connects port 17 to an outlet pipe 21, and visa versa.

As mentioned above, the apparatus is installed in an existing pipeline from a keg (not shown) to a bar dispenser 30 including a simple tap 31. Apart from providing a source of electrical power for the controller 24, no other change need be made to an existing conventional top pressure beer dispensing arrangement. On first supplying power to the controller 24, one solenoid is energised so that on subsequently opening the tap 31, the beer under pressure and supplied to the common inlet 22 will drive the piston to one end of the cylinder 10; thereafter, the apparatus is ready to commence dispensing predetermined volumes of beer - typically in half pint measures.On opening the tap 31, the release of pressure on the outlet 23 will permit the piston 12 to move under applied beer pressure from the keg to the other end of its stroke, so driving beer out of the cylinder from the other side of th piston. As the piston approaches it limiting position, switch 15 (or 16, depending upon the direction of piston movement) will be operated so triggering the timer 25. After a pre-set delay, the driver circuit 26 is operated to change over the settings of the two valves 18. Thus, the common inlet 22 is connected to the port 17 at the end of the cylinder whereat is located the piston, and the common outlet 23 to the other port 17. The piston may then once more be driven to move along the cylinder 10 and dispense a second predetermined volume. If however the tap 31 had been closed during the period timed by timer 25, no further dispensing will take place until the tap 31 is opened once more. The timer may therefore conveniently be set to time an interval in the range of from 2 to 10 seconds, to give sufficient time for an operator to recognise the dispensing of a first predetermined volume has been completed, and close the tap 31 if a second volume is not required.

Claims

1. Apparatus for dispensing a predetermined volume of liquid, comprising an inlet for liquid under pressure, an outlet for dispensed liquid, a closed cylinder having a freely-slidable piston mounted therein, detecting means for the presence of the piston at or adjacent either of the two ends of the cylinder and to provide a respective output consequent thereon, the two ends of the cylinder each having at least one port to permit the flow of liquid into and out of the cylinder, there being an electrically-controlled valve associated with each port, and an electrical controller responsive to the output of the detecting means and controlling the operation of said valves dependent thereon so as alternately to connect the inlet to one end of the cylinder and the outlet to the other end thereof, and vice versa.

2. Apparatus according to Claim 1, wherein there is a single port at each end of the cylinder and each port has a two-way electrically-operated valve associated therewith whereby, in each case, either the inlet or the outlet is connected alternatively to the port.

3. Apparatus according to Claim 1 or Claim 2, wherein each electrically-operated valve comprises a solenoid valve.

4. Apparatus according to any of the preceding Claims, wherein the detecting means comprises, at or adjacent each end of the cylinder, a proximity detector for the piston.

5. Apparatus according to Claim 4, wherein the proximity detector includes a magnet mounted on the piston and, at or adjacent each end of the cylinder, an element responsive the magnetic lines of force emanating from the magnet on the piston.

6. Apparatus according to Claim 5, wherein each said element comprises a reed switch.

7. Apparatus according to any of the preceding Claims, wherein the controller causes operation the valves to reverse the liquid connections to the cylinder only after a preset delay following detection of the presence of the piston at or adjacent an end of the cylinder.

8. Apparatus according to Claim 7, wherein said preset delay is adjustable.

9. Apparatus according to any of the preceding Claims, wherein the controller is arranged to operate the valves to cause the piston to move to one end of the cylinder on first powering the controller and the valves.

10. Apparatus according to any of the preceding claims, wherein the inlet for liquid under pressure includes a two-way valve arranged to permit the connection of either one of two liquid sources to the liquid inlet.

11. Apparatus according to Claim 10, wherein there is provided a float chamber between the two-way valve and the dispensing cylinder, in which float chamber is mounted a float the position of which is monitored, the output of such monitoring being used to control the operation of the two-way valve.

12. Apparatus for dispensing a predetermined volume of liquid substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

13. Alcoholic beverage dispensing apparatus comprising a connector for a keg of beverage, an outlet tap, in combination with apparatus according to any one of Claims 1 to 12, wherein the connector is coupled to the liquid inlet and the outlet tap is coupled to the liquid outlet.