GB2180218A - Pump control system for beer dispensing - Google Patents

Abstract

A system for controlling a pump for dispensing beer through a supply line of which the pump forms part. The system comprises a pressure detector responsive to the pressure in the supply line, a flow detector responsive to fluid flow through the supply line, a timing circuit, an output circuit controlling the energisation of the pump, and electronic switching means connected to the output circuit and controlled by the flow detector. The switching means causes the output circuit to energise the pump for a predetermined period determined by the timing circuit when the detected pressure falls below a predetermined level e.g. on opening a dispense tap, and the switching means causes the output circuit to maintain the energisation of the pump for the duration of any period in which the detected pressure is below the said predetermined level and the said predetermined flow is detected.

Description

SPECIFICATION A system for controlling pumps This invention relates to a system for controlling pumps used especially but not exclusively in dispensing beer and other consumable liquids.

One known system for controlling such pumps involves the use of mechanical pressure switches but this system is subject to a number of disadvantages, namely contact wear due to high switching current of inductive loads, interference resulting from mains switching of contacts, mechanical failure of, inter alia, contacts, springs and bellows, there is no shutdown facility when liquid runs out, and due to the mechanical pressure switch not being disposed in the line of liquid flow it tends to be "a germ trap".

Asecond known control system known as "Pumpmaster" has the disadvantages that it is not suitable for dual voltage use, electrical component failure can result from the action mains voltages on passive components, and itis pronetotimerfailuresothat the pump does notshut down when there is a cessa- tion of liquid supply.

It is an object of the present invention to provide a control system four a pump used, for exam ple, in dispensing consumable liquids (hereinafter for con- venience simply referred to as "beer") which obviates or mitigates the aforesaid disadvantages.

According to the present invention there is provided a system for controlling a pump for dispensing beerthrough a supply line of which the pump forms part, the system comprising a pressure detector re- sponsivetothe pressure inthesupply line, aflow detector responsiveto fluid flow th rough thesupply line, a timing circuit, an output circuit controlling the energisation ofthe pump, and electronic switching means connected to the output circuit and controlled by the flow detector, the switching means causing the output circuit to energise the pump for a predetermined period determined by the timing circuit when the detected pressure falls below a predetermined level, and the switching means causing the output circu it to maintain the energisation ofthe pumpforthe duration of any period in which the detected pressure is below the said predetermined level and the said predetermined flow is detected.

The switching means may com prise a fi rst set of contacts which connect an input ofthe timing circuit to a switch controlled by the pressure detector ifthe said predetermined flow is not detected, whereby timing of said predetermined period is initiated when the pressure detector switch indicates that the pressure is below said predetermined level, and a second set of contacts which connect the output ci rcuit to an output of the timing circuit if the said predetermined flow is not detected and which connects the output circuit to the pressure detector switch when the said predetermined flow is detected.The output circuit may comprise a first portion electrically connected to the switching means, and a second portion electrically connected to a solid state switch controlling energisation ofthe pump, and first and second portions being optically coupled so as to be electrically isolated.

Preferably the system comprises a power circuit in cl ud ing a tra nsformer adapted to transform mains voltage from, say, 240 volts or 110 volts down to 12 volts. A fuse may be provided in the power circuit and associated with an indicator lightto achieve overload protection and indication.

Preferably, L.E.D.'s are provided to signal a "flow" condition (yellow L.E.D. for example) and a "timed out" condition (red L.E.D. for example).

An example ofthe present invention will now be described with reference to the accompanying drawings, in which Figure lisa circuit diagram ofthe pump control system according to the present invention; and Figure2 is an operation sequence diagram.

The controller of the present invention is connected to a beer dispensing pump (not shown) and the electricity mains supply. As the controller is dual voltage it has a voltage selector switch which is actuated to either 110 volts or 240 volts depending on the mains supply and the pump.

The controlleris installed in the beersupplyline vertically and directly after the pump and the usual non-return valve provided in such line.

The controller comprises a transformer 10 with full wave rectifier 11 serving to transform the selected mains voltage of 12 volts.

The power circuit of the controller includes a printed circuit board relay RLA which controls, interalia switches RLA1 and RLA2, which relay RLA is controlled by a flow sensor to switch power to a programmabletimer 12. The latter is operativelycon necked to an optotriac 1C2 (optical isolator) which normaily isolates the power circuit of the controller from the mains supply. Initiation ofthetimer 12 actuates the optotriac IC2 to cause an electronic switch l3tofireand effectpumpoperation.

The controller includes a pressure switch 14and a flow switch 15.

To set up the beer supply system incorporating the controller according to the present invention, the pump is bled and the controller is switched on at mains supply. The pump will run and prime the beer supply lines to the barvalvesfrom which beer is to be dispensed.

The controller has a red L.E.D. 16which isto signal on the controller a "timed out" condition. If this il luminatesthe pump will stop. If there is a long pipe run between the pump and the dispensing barvalves the pump may required repriming. The controller can be reprimed by pressing a manual reset switch 18 thereon.

When the pump and supply lines are primed the controller is ready for use.

When the controller is at its "rest" or ready for use state, the pressure switch 14 is open and the flow switch 15 is open, there is no supply to the pro grammabletimer 12 orto the optical isolator IC2, and consequently the electronic switch 13 is not fire and there is not output to the pump, i.e. the pump is nonoperational.

When a bar valve is opened the pressure switch 14 senses a drop in pressure and closes, whereby power is supplied via RLA, RLA1 to the programmabletimer 12which starts timing. When the beer begins to flow the timer 12 will stop and resetto zero and a yellow L.E.D. 17 on the controller will illuminateto indicate "flow".

More specifically, initiation of the timer 12 actuates, via RLA2, the optical isolator IC2 to connect the controller powercircuitto the mains supply thus firing the electronicswitch to operatethe pumpto give the aforesaid "flow".

When the bar vale is closed the pressure switch 14 senses an increase in pressure and the controller switches the pump off.

Again more specifically, when the timer 12 attains its settime period the output on pin "8" ofthetimer dropsto lowthuscutting offthe powersupplyand rendering the pump non-operational. Atthisstage L.E.D. ("timed out") is illuminated. If the timer reaches its set time period before the pressure switch 14 opens the timer 12 will reset.

When the flow switch 15 closes this closes RLA1 which disconnects the voltage supply to the timer 12 and connects the optical isolator IC2to pressure switch 14which causes the pump to run continuously untiltheflowswitch 15 opens. When this is effected the controller is again ready for normal use.

If during the delivery to the bar valve the beer supplyto the pump is cut offthe controllerwill sense thislackofflow(theyellowL.E.D. 1 7 will go out thus signalling this condition to the bar person) and the timer 12 will startto time. When the "time out" period of the timer 12 has elapsed the pump will stop and the red L.E.D. l6will signal thatthe controller has "timed out".

When the beer supply is restored the controller is reprimed by pressing the manual reset switch 18.

The sequence of operations is set out diagrammatically in Figure 2 which is considered selfexplanatory.

Afuse 19 is provided to protect the circuitry against overload. In the event of an overload the fuse will rupture, thus rendering the system inoperative. An indication of fuse rupture is given by neon lamp 20.

The controller according to this invention has the following advantages over known controllers: 1. it is dual voltage; 2. it has an accurate shut-down period (for example one second to ten hours); 3. it has solid state switching ofthe pump thus there is no contact wear; 4. it is suppressed against interference; 5. there is automatic shut-down if liquid supply ceases; 6. all control circuitry is optically isolated from the electricity supply mains.

Claims (5)

1. Asystemforcontrolling a pumpfordispensing beerthrough a supply line ofwhich the pump formes part, the system comprising a pressure detector re- sponsive to the pressure in the supply line, a flow detector responsive to fluid flow through the supply line,atiming circuit, an output circuit controlling the energisation of the pump, and electronic switching means connected to the output circuit and controlled bytheflow detector, the switching means causing the outputcircuitto energisethe pumpfora pred etermined period determined by the timing circuit when the detected pressure falls below a pred etermined level, and the switching means causing the output circuit to maintain the energisation ofthe pumpforthe duration ofany period in which thedet- ected pressure is belowthesaid predetermined level and the said predetermined flow is detected.

2. Asystem according to claim 1,whereinthe switching means comprises a first set of contacts which connect an input of the timing circuitto a switch controlled by the pressure detector if the said predetermined flow is not detected, wherebytiming ofthe said predetermined period is initiated when the pressure detector switch indicates that the pressure is below said predetermined level, and a second set of contacts which connect the output circuit to an output ofthe timing circuit if the said predetermined flow is not detected and which connects the output circuit to the pressure detector switch when the said predetermined flow is detected.

3. Asystem according to claim 1 or2,whereinthe output circuit comprises a first portion electrically connected to the switching means, and a second portion electrically connected to a solid state switch controlling energisation ofthe pump, the first and second portions being optically coupled so asto be electrically isolated.

4. Asystem according to claim 3, comprising a transformeran input of which is connected two a mains supply also connected to the solid state switch and a rectified output of which provides a low vol- tage DC supply to the pressure and flow detectors.

5. A system according to claim 4, wherein the transformer is switchable to transform different mains voltage to a predetermined DC supply voltage.