GB2089767A - Liquid dispensing apparatus - Google Patents

Abstract

In a liquid dispensing apparatus, liquid passes in either direction through a cylinder (24) by means of valves (20, 16 or 22, 18). As movement of a piston (26) approaches an end of the cylinder (24) to register a discrete quantity of the fluid, a coil externally of the cylinder (24) senses the position of the piston (26) and effects change-over of the valve paths prior to the piston (26) reaching the end of the cylinder (24). This enables opening of the valves in the other valve path before the differential pressure across the other valves becomes significantly large. Dispensing of a fluid is continuous and when dispensing has stopped, a memory device remembers the direction in which the piston (26) was travelling such that the piston can continue in the same direction when dispensing is resumed. The number of complete strokes of the piston (26) can be counted to record over a period of time the amount of liquid which has been dispensed to a very high degree of accuracy. <IMAGE>

Description

SPECIFICATION Fluid dispensing apparatus This invention reiates to fluid dispensing apparatus, and particularly apparatus enabling positive displacement measurement of free flow dispense.

In the well known and widely used positive displacement method of metering drinks, a metering device provides a method of accurately dispensing liquids in discrete quantities, usually half pints or multiples thereof, and the device is so designed that liquid may not be dispensed in any other quantity than integral numbers of half pints. This is achieved by an interlock which ensures that once the metering device is initiated, dispense can not be terminated until a piston of the device has completed a full stroke, thereby measuring out the desired quantity.

There is, however, a need for a system which will accurately measure the quantity of liquid dispensed, but without the need to dispense solely in multiples of, say half pints. This requirement relates specifically to stock control of beer in licenced premises where the preferred method of dispense is by free flow.

According to the present invention there is provided fluid dispensing apparatus comprising a fluid dispense line, means in the line for dispensing a discrete quantity of the fluid to a dispense outlet, and means enabling the dispensing means to operate continuously while the dispense outlet is open, providing a constant flow of fluid at the dispense outlet.

Preferably the dispensing means comprises a piston displacing the discrete quantity of the fluid from a cylinder. Preferably also the cylinder is operatively connected with a valve arrangement, the latter defining alternative paths for the fluid through the cylinder in opposite directions.

The valve arrangement may be controlled by means which senses the position of the piston in the cylinder and the sensing means may be activated when the piston is closely adjacent to, but spaced from the end of its stroke.

Thus the proposed stock control system utilises the well proven principle of a piston travelling inside a cylinder, which may be glass, as used in a conventional meter, but the controlling system, instead of dispensing in multiples of strokes only, allows the beer to be drawn on demand from the outlet of the system.

An embodiment of the present invention will now be described by way of example only with reference to the single figure of the accompany drawing, which shows a schematic arrangement of a fluid dispensing apparatus.

Referring to the drawing, a stock control system senses the demand for beer either by the drop in pressure caused by opening of one of a plurality of dispense outlets 10, which allows a pressure switch 12 in the dispense line to operate, or alternatively contacts may be closed at the dispense outlet to indicate a demand for flow.

The pressure switch 12 or contact closure causes a pump 14 to be energised and an opposed two of an arrangement of four valves 16 - 22 to be opened, say valves 16 and 20. This allows liquid to flow from the pump 14 in one direction through a cylinder assembly 24 to the dispense outlets. A piston 26 in the cylinder will clearly be forced to move to enable this flow to take place, and this will continue until the piston 26 reaches the end of its stroke. At this time the valves 16 and 20 are closed and the valves 18 and 22 are opened, hence allowing flow to continue.

The position of the piston 26 may be sensed in several ways. The conventional beer meter uses a flow switch to sense the end of a stroke but this would result in a slight pause while flow stopped which is clearly undesirable. Another problem with a conventional flow switch is that a large pressure differential would exist across the inlet valve which would need to be opened in order to continue flow with the piston moving in the opposite direction, and this means that valve design is complex. Yet another problem with this solution is that the flow switch would cause the piston to change direction every time that the dispense outlets are closed, and accuracy would be spoiled.

For the above reasons, the position of the piston 26 is sensed for example electrically by means of a coil mounted outside the cylinder, the coil sensing the position of a metal part within the piston 26. This is arranged so that the valves are changed over when the piston 26 is a very small distance from the end of the stroke. This eliminates the above problems, and is particular allows valves with very large orifices to be used, because the differential pressure across these valves is always low, and hence allows large flow rates.

The dispense continues, therefore, with the piston 26 travelling first one way, then the other until the demand for flow is removed, either by the opening of contacts at the dispense outlet, or by the closure of the tap at the dispense outlet, the consequent rise in pressure causing the pressure switch to operate.

At this time all valves are de-energised and the motor is switched off. In this state, an electronic or mechanical device will remember which direction the piston 26 was travelling, and then, when dispensing is resumed, the piston 26 will continue in the direction it was moving at the time the previous dispense was terminated, hence completing the stroke.

For stock control and accounting purposes the number of complete strokes are counted, either electrically or mechanically, disregarding any stops and starts the piston 26 may have made. Therefore, over a period of time the amount of liquid which has been dispensed may be recorded to a very high degree of accuracy.

Several improvement may be made to this system. For example the arrangement for changing over the valve pairs may be enhanced by the use of a further valve on the outlet which will be closed just before the end of the stroke is reached and will cause the system to be pressurised at the instant of changeover, hence allowing the use of even larger valve orifices due to low differential pressure across these valve. Other electrical or mechanical methods may be used to sense piston position and other porameters, such as optoelectronic methods.

The invention may be applied to other than dispensing of drinks such as beer.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to whether or not particular emphasis has been placed thereon.

CLAIMS (Filed on 17 1981) 1. Fluid dispensing apparatus comprising a fluid dispense line, means in the line for registering discrete quantities of the fluid passing therethrough, and means enabling the dispensing of more than one of said discrete quantities continuously at a dispense outlet while the latter is open.

2. Apparatus according to claim 1, wherein the registering means comprises a piston for displacing the discrete quantities of the fluid from a cylinder.

3. Apparatus according to claim 2, wherein the cylinder is operatively connected with a valve arrangement which defines alternative paths for the fluid through the cylinder in opposite directions.

4. Apparatus according to claim 3, wherein the means enabling continuous dispensing senses the position of the piston in the cylinder and controls the valve arrangement.

5. Apparatus according to claim 4, wherein the sensing means is activated when the piston is closely adjacent to, but spaced from the end of its stroke in the cylinder.

6. Apparatus according to claim 4 or 5, wherein the sensing means comprises a coil located external iy of the cylinder and connectible to an electrical supply whereby movement of a metal part of the piston past the coil can be sensed.

7. Apparatus according to any of claims 4 to 6, wherein a further valve is provided at the dispense outlet and is adapted to be operated by the sensing means, whereby the fluid in the path, other than the path through which dispense is being effected at any one time, is maintained under pressure at the outlet side of the valve arrangement at the instant of change-over of the fluid paths.

8. Apparatus according to any of claims 2 to 7, wherein means is provided for registering the direction of movement of the piston immediately before dispensing is terminated, whereby the piston can continue to move in the same direction when dispensing is re-commenced.

9. Fluid dispensing apparatus substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. The invention may be applied to other than dispensing of drinks such as beer. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to whether or not particular emphasis has been placed thereon. CLAIMS (Filed on 17 1981)

1. Fluid dispensing apparatus comprising a fluid dispense line, means in the line for registering discrete quantities of the fluid passing therethrough, and means enabling the dispensing of more than one of said discrete quantities continuously at a dispense outlet while the latter is open.

2. Apparatus according to claim 1, wherein the registering means comprises a piston for displacing the discrete quantities of the fluid from a cylinder.

3. Apparatus according to claim 2, wherein the cylinder is operatively connected with a valve arrangement which defines alternative paths for the fluid through the cylinder in opposite directions.

4. Apparatus according to claim 3, wherein the means enabling continuous dispensing senses the position of the piston in the cylinder and controls the valve arrangement.

5. Apparatus according to claim 4, wherein the sensing means is activated when the piston is closely adjacent to, but spaced from the end of its stroke in the cylinder.

6. Apparatus according to claim 4 or 5, wherein the sensing means comprises a coil located external iy of the cylinder and connectible to an electrical supply whereby movement of a metal part of the piston past the coil can be sensed.

7. Apparatus according to any of claims 4 to 6, wherein a further valve is provided at the dispense outlet and is adapted to be operated by the sensing means, whereby the fluid in the path, other than the path through which dispense is being effected at any one time, is maintained under pressure at the outlet side of the valve arrangement at the instant of change-over of the fluid paths.

8. Apparatus according to any of claims 2 to 7, wherein means is provided for registering the direction of movement of the piston immediately before dispensing is terminated, whereby the piston can continue to move in the same direction when dispensing is re-commenced.

9. Fluid dispensing apparatus substantially as hereinbefore described with reference to the accompanying drawing.