GB2090919A - Beverage dispensing apparatus - Google Patents

Abstract

An arrangement for preventing overcarbonation of beverages in a dispensing system comprising keg 1, CO2 gas supply 3, volumetric meter 6 and bar tap 7. The arrangement has a gas flow sensor 10, conveniently a PTC thermistor, and gas shut-off valve 9 with a circuit such that valve 9 is opened during dispensing and following dispensing is maintained in this open state by current flow through thermistor 10 which is cooled by the gas. When gas-flow reduces sufficiently or stops the thermistor self-heats to close the valve 9. The arrangement is specifically responsive to gas flow state during repressurisation rather than a fixed time delay. <IMAGE>

Description

SPECIFICATION Beverage dispensing This invention relates to beverage dispensing and more particularly to the dispensing of highly carbonated beverages. In such systems very careful control of the applied carbon dioxide pressure is necessary if fobbing is to be avoided and it is usual to adjust the pressure to be slightly in excess of equilibrium. With such arrangements when the pressurising gas is not cut off during periods when dispensing does not take place, for example overnight, then the beverage absorbs a more than usual quantity of gas and becomes highly over-carbonated, and is then very difficult if not impossible to dispense successfully. This is especially true where volumetric metering apparatus is used between the beverage container and dispense point.

In G.B. 1 538873 there is disclosed a system for preventing over-carbonation which uses a time delay circuit operative following closure of the dispense point tap and serving to close a valve in the gas supply to the beverage container. The gas valve is opened on initiation of the dispense point tap. This arrangement offers a fixed time delay to allow repressurisation. The use of a pressure or flow responsive switch is described also, but this is to determine the cessation of fluid flow to the dispense tap and thereafter initiate the time delay to shut off the gas. The arrangement does not take into account the repressurisation characteristics under certain conditions.

It is an object of this invention to provide an improved arrangement whereby over-carbonation under such circumstances is reduced or avoided and at the same time ensuring proper repressurisation.

According to this invention in an arrangement for dispensing a pressurised beverage including a pressurised gas source connected to a beverage container and serving to force the beverage through a delivery line to a dispense point, there is provided a gas flow sensor located between the gas source and beverage container and a gas flow shut-off valve in the gas line from the gas source to the container, the sensor being responsive to gas flow rate and arranged to close the valve following a reduction in gas flow as the gas demand is satisfied.

Preferably the gas shut-off valve comprises a solenoid valve which is normally opened following initiation of the opening of the dispense point tap whereby pressure from the gas source may flow to the beverage container during dispensing.

Following closure of the dispense point tap the gas flow reduces and the sensor detects this causing the solenoid valve to close, thereby preventing over-carbonation of the beverage within the container. In a preferred embodiment the sensor comprises a thermistor such as a positive temperature co-efficient thermistor in thermal contact with the gas flow and which is connected in series with the solenoid valve. With this arrangement whilst gas is flowing the temperature of the thermistor is held at a reduced value, thereby maintaining the solenoid valve in an open condition. Following reduction of the gas flow upon closure of the dispense point tap, or ending of the metering of the beverage, the gas flow reduces and the thermistor resistance increases as the temperature rises to the point where the current is unsufficient to maintain the solenoid valve open and this then closes.The dispense point valve causes the solenoid valve to re-open at the next dispensing operation whereupon the temperature of the thermistor is again reduced due to the gas flow and at the termination of the dispense operation the thermistor maintains the valve open for a period determined by the time it takes to re-pressurise the container and for the thermistor to again warm up and allow the valve to close.

This arrangement therefore ensures that pressurisation is removed following a period of non-use and in particular over-carbonation during overnight periods of non-use is limited.

An embodiment according to the invention is shown by way of example in the accompanying drawings, wherein: Figure 1 shows a schematic arrangement of beverage dispensing system incorporating the invention, Figure 2 shows a circuit diagram of the solenoid valve and associated components.

Referring firstly to Figure 1, a beverage dispensing system has a beverage containing keg 1 with an associated carbon dioxide supply 2 which serves to pressurise the beverage via line 3.

The pressurised beverage flows out of keg 1, through line 4, a pump unit 5 and into a volumetric metering device 6. The dispense point 7 includes a tap valve which when actuated causes a pre-determined volume of beverage to be dispensed as determined by the meter unit 6. A relay unit 8 serves to control the pump 5 when the metering unit 6 operates, and in addition the relay 8 operates a solenoid valve 9 connected in the line 3 and arranged so that energization thereof opens the valve. The solenoid valve 9 is operated by the relay 8 and in addition by a separate circuit which incorporates a positive temperature co-efficient thermistor 10 or other suitable temperature sensing or gas flow sensing means.

Assuming the system to be in a state of rest, operation of the dispense point tap 7 actuates the meter unit 6 and, through the relay 8, pump 5 and solenoid valve 9 are actuated whereby the meter unit 6 is caused to dispense a measured volumetric quantity of beverage. The valve 9 being thus open allows the container 1 to be pressurised from the gas source 2. Following dispensing of the measured quantity of beverage, relay 8 shuts down pump 5 and the energising current to the solenoid 9 from relay 8 is shut off. However, due to the flow of gas, sensor 10 is reduced in temperature and this allows a maintaining current to be fed to the solenoid 9 thereby holding the valve open. Gas may thus continue to flow into the container 1, but after a short time keg 1 is repressurised and the gas flow reduces significantly.When the sensor 10 comprises a positive temperature co-efficient thermistor this is warmed up by current flow therethrough and the temperature increases to the point where insufficient current is available to maintain the solenoid valve 9 open. This valve then closes and further gas supply and pressurisation of container 1 is prevented. By suitable adjustment of the various parameters the delay to allow repressurisation can be set to that required, and typically the solenoid valve will close when the thermistor heats up to about 800C where there is a significant change to a high value of resistance.

The arrangement therefore allows the valve 9 to remain open thereby ensuring pressurisation during active dispensing, but causes the valve to shut following a period of non-use.

Figure 2 shows the circuit associated with the solenoid valve wherein the valve coil 20 is supplied through a bridge rectifier 21 from a switched electrical A.C. supply such as from the relay 8. As soon as the relay 8 is energised then the solenoid valve 20 is open. However, on removal of the energising current 8 and by virtue of a continuous supply 22 passing through rectifier diode 23, energisation of the coil 20 is maintained assuming that thermistor T passes sufficient current to cause current flow through zener diode Z. As long as carbon dioxide is flowing over the thermistor T the temperature will be sufficiently reduced to ensure that its resistance causes current flow to operate coil 20. Following a period of non-use the gas flow reduces and selfinduced heating causes the temperature of thermistor T to rise to about 800C, until a point is reached where zener diode Z no longer conducts in a reverse direction and coil 20 is not then energised thus closing the valve. In order to provide for pressurisation of the container without dispensing the beverage the priming button S is provided in parallel with the thermistor T.

A further advantage of this arrangement is that it does not depend upon a defined time delay for operation, in that the closing of the solenoid valve 9 is dependent upon predetermined reduction in the gas flow rather than a predefined time limit which has no relationship to the pressurising gas which might still be flowing into the container 1.

Thus the solenoid valve will remain open for as long as sufficient gas flows into the container.

Claims (8)

1. An arrangement for dispensing a pressurised beverage including a pressurised gas source connected to a beverage container and serving to force the beverage through a delivery line to a dispense point, wherein there is provided a gas flow sensor located between the gas source and beverage container and a gas flow shut-off valve in the gas line from the gas source to the container, the sensor being responsive to gas flow rate and arranged to close the valve following a reduction in gas flow as the gas demand is satisfied.

2. An arrangement in accordance with Claim 1, wherein the gas shut-off valve is opened when a tap at the dispense point is operated to draw off beverage.

3. An arrangement in accordance with Claim 2, wherein the shut-off valve is electrically operated, the valve being held open by a maintaining current following operation of the tap, and closed by cessation of the current in response to a signal derived from the sensor.

4. An arrangement in accordance with any preceding Claim, wherein the sensor comprises a thermistor in thermal contact with the gas flow.

5. An arrangement in accordance with Claim 4, wherein the thermistor has a positive temperature coefficient.

6. An arrangement in accordance with Claim 5, wherein the thermistor is electrically in series with an operating solenoid of the gas shut-off valve and supplies a current sufficient to maintain the valve open whilst gas flows to maintain the thermistor temperature below a critical value.

7. An arrangement in accordance with Claim 6, wherein the solenoid is supplied additionally with an operating current during dispensing of the beverage.

8. An arrangement for preventing overcarbonation of beverages as described herein and as shown in Figure 1 or Figure 2 of the drawings.