GB2094269A - Apparatus for dispensing beer or other liquid from a container - Google Patents

Abstract

An apparatus for dispensing beer or other liquid from a container through a dispensing outlet (7) is of the type comprising an electrically driven pump (1) having an inlet (2) arranged to be connected to a container of the liquid, an outlet (3) connected to a closure valve at the dispensing outlet (7) and a non-return valve (4) for maintaining pressure in the liquid generated by the pump (7) when the pump (1) is stopped and the closure valve (7) is closed. Such apparatus is provided with a pressure sensitive means (5, 12) which is actuated in dependence upon the pressure of the liquid between the non- return valve (4) and the closure valve (7) and a pump control circuit to which the pressure sensitive means (5, 12) is connected and which includes a timing device (16). The pressure sensitive means (5, 12) and the pump control circuit are arranged so that the pump (1) and the timing device (16) are started when the pressure of the liquid between the non-return valve (4) and the closure valve (7) falls below a lower predetermined pressure, the timing device (16) stopping the pump (1) if the pressure does not rise above the lower predetermined pressure within a time determined by the timing device (16), and the pressure sensitive means (5, 12) also being arranged to stop the pump (1) upon the rise of the pressure above a higher predetermined pressure which occurs when the closure valve is closed while the pump is running. This apparatus avoids the use of a flow switch in the liquid flow downstream of the pump (1) and yet prevents damage to the pump (1) in the event of the exhaustion of the supply of liquid to it or in the event of it becoming gas locked. <IMAGE>

Description

SPECIFICATION Apparatus for dispensing beer or other liquid from a container Beer and other carbonated liquids, such as carbonated soft drinks, are usually stored in kegs in hotels and public houses and a toppressure of carbon dioxide is aplied to the liquid in the keg. This top-pressure is in some cases sufficient to cause the liquid to flow from the keg to a tap at a bar or to some other dispensing outlet. More generally, however, it is necessary to pump the beer from the keg to the dispensing outlet and for this purpose electrically driven pumps, usually of the centrifugal type are used.

These pumps are usually automatically controlled in such a way that they are started whenever a closure valve is opened at the dispensing outlet and they are stopped again when the dispensing valve is shut. When the closure valve is shut, the pump increases the pressure upsteam of the closure valve and a non-return valve is provided to maintain the pressure after the pump has stopped. This pressure is sensed by a pressure switch which is connected in a control circuit of the pump and keeps the pump out of operation so long as the pressure is above a predetermined value, but as soon as the pressure falls upon opening of the closure valve, the pressure switch causes the pump to be started.

If however while the pump is in operation and the closure valve is open, the flow through the pump ceases, for example if the keg to which the pump inlet is connected is emptied or if a gas lock occurs in the pumps, the pump overspeeds and this may cause damage. To avoid this, it is necessary to provide a further control to stop the pump if the flow from the pump ceases for any reason while the closure valve is open. The conventional form of control for this purpose comprises a flow switch which is connected in a pump control circuit and stops the pump when it detects a lack of flow.

The arrangement works quite satisfactorily, but it may be expensive in that it calls for both a pressure switch and a flow switch together with the other components of the pump control circuit and further, the flow switch, which generally includes a plunger in the beer outlet pipe from the pump, tends to throttle the flow between the pump outlet and the closure valve. This is undesirable.

The aim of the present invention is to provide an improved apparatus for dispensing beer or other liqud from a container through a dispensing outlet, the apparatus being of the type comprising an electrically driven pump having an inlet arranged to be connected to a container of the liquid, an outlet connected to a closure valve at the dispensing outlet and a non-return valve for maintaining pressure in the liquid generated by the pump when the pump is stopped and the closure valve is closed. This improved apparatus avoids the use of a flow switch in the liquid flow downstream of the pump.

According to this invention, such an apparatus is provided with a pressure sensitive means which is actuated in dependence upon the pressure of the liquid between the nonreturn valve and the closure valve and a pump control circuit to which the pressure sensitive means is connected and which includes a timing device, the pressure sensitive means and the pump control circuit being arranged so that the pump and the timing device are started when the pressure of the liquid between the non-return valve and the closure valve falls below a lower predetermined pressure, the timing device stopping the pump if the pressure does not rise above the lower predetermined pressure within a time determined by the timing device, and the pressure sensitive means also being arranged to stop the pump upon the pressure of the liquid between the non-return valve and the closure valve rising above a higher predetermined pressure.

The lower predetermined pressure is below that which is developed upstream of the closure valve when the closure valve is open and the pump is operating correctly and pumping liquid, but it is above the pressure which occurs if liquid flow through the pump ceases.

Accordingly, when the pump is started, it continues to run so long as the closure valve is open, but it stops when the closure valve is closed and it also stops after the time determined by the timing device has elapsed if the pump has ceased to pump liquid because the container to which it is connected is empty or because the pump has become gas locked.

The pressure sensitive means may comprise two separate pressure sensitive switches, one of which is actuated at the lower predetermined pressure and the other and the higher predetermined pressure, but preferably it comprises a device which produces different outputs at the lower predetermined pressure and at the higher predetermined pressure. The pressure sensitive means preferably includes a Hall-effect device which produces an output voltage that is dependent upon the strength of a magnetic field to which it is subjected. In this case, the pressure sensitive means also includes a permanent magnet which is movably mounted and has means by which it is moved towards and away from the Hall-effect device as the pressure in the liquid rises and falls.For this purpose the magnet may be mounted on a spring-loaded cantilever arm which is acted upon by a flexible diaphragm subjected to the liquid pressure with the arm being spring-loaded in such a way that its deflection is directly dependent upon the pressure acting upon the diaphragm.

Preferably the magnet is supported by a helical coil compression spring acted on by a rolling diaphragm subjected to the liquid pressure. This arrangement results in a large degree of movement of the magnet for a particular change in pressure in the liquid and conse quently results in an increase in accuracy of measurement.

The output from the Hall-effect device is fed to two comparator circuits set at different trip levels. The first one of the two comparator circuits trips at the lower predetermined pressure and the second comparator circuit trips at the higher predetermined pressure. The out put from the first comparator circuit is fed to both the timing device and to a larth circuit.

The output of the second comparator is fed to the latch circuit.

The pump control circuit may include a motor speed control unit. The motor speed control unit may be only manually adjustable to set the pump to a required speed to produce a predetermined output pressure from the pump at a predetermined beer flow through the dispensing outlet. However, a single pump commonly supplies more than one dispensing outlet and it is deisrable to be able to increase the output of the pump if more than one outlet is in use at any time. If the pressure sensitive means is upstream of the position of branches to the various dispensing outlets, the liquid pressure subsisting in the pressure sensitive means decreases as a greater number of dispensing outlets are opened.

When the pressure sensitive means includes a Hall-effect device which produces a voltage output dependent upon the pressure, the output signal from the Hall-effect device may be fed directly to the motor speed control unit so that as the pressure varies between the two limits set by the two comparator circuits, the motor speed control unit is automatically adjusted to maintain the pressure at the dispensing outlets at a substantially constant value.

Thus as an increasing number of dispensing outlets are opened and the pressure of the liquid downstream of the pump accordingly decreases, the output signal from the Halleffect device and the motor speed control unit causes the pump speed to be increased to restore the pressure to its normal value. The dispensing pressure at the dispensing outlets is thus maintained regardless of the number of dispensing outlets which are opened up to a maximum which is of course dependent upon the maximum output of the pump.

Two examples of an apparatus in accordance with the invention for dispensing beer will now be described with reference to the accompanying drawings; in which: Figure 1 is a diagram of the first example of the apparatus; Figure 2 is an operation diagram of the apparatus shown in Fig. 1 showing the control operations of the pump which are brought about automatically during the course of dispensing a volume of beer during which the keg to which the inlet of the pump is connected is emptied and the pump inlet is subsequently reconnected to a full keg; and, Figure 3 is a diagram of a second example of the apparatus.

In the first example a pump 1 has its inlet 2 connected to a beer keg (not shown) and its outlet 3 connected through a non-return valve 4 to a pressure transducer 5 of a pressure sensitive device. An outlet 6 of the pressure transducer 5 leads to one or more dispensing outlets 7 each fitted with a closure valve. The pressure transducer 5 comprises a generally cylindrical non-magnetic housing divided into two by a rolling diaphragm 8. A cylindrical piston 9 carrying a permanent magnet 10 is mounted on a helical compression spring 11 and the piston 9 engages the mid portion of the rolling diaphragm 8. The beer is introduced into the housing to contact the face of the rolling diaphragm 8 to form the piston 9.

A hall-effect device 1 2 such as a model no UGN 3510M manufactured by SPRAGUE, is mounted on the outside of the housing in axial alignment with the permanent magnet 10 and this is connected to a first comparator circuit 1 3 and a second comparator circuit 14. The first comparator circuit 1 3 is connected to a timer 1 5 and to a latch circuit 1 6.

The timer 1 5 also has a direct connection to the latch circuit 1 6. The latch circuit 1 6 is in turn connected to the electric motor 17 which drives the pump 1.

As the pressure in the outlet from the pump 1 increases, the piston 9 and he diaphragm 8 are deflected further and further against the force exerted upon it by the spring 10 and in consequence as the pressure increases, the magnet 11 moves further away from the Halleffect device 1 2 and as the pressure decreases, the magnet 11 moves closer towards the Hall-effect device 1 2.

The fist comparator circuit 1 3 is set to trip at a signal output from the Hall-effect device 1 2 which, in this example, corresponds to a pressure in the transducer 5 of 30 p.s.i. (2 bar). The second comparator circuit 14 is set to trip at a signal level which, in this example, corresponds to a pressure of 70 p.s.i. (4.6 bar). These pressures may of course be varied in dependence, for example, upon the carbon dioxide top pressure applied to the beer in the keg and upon performance characteristics of the pump.

When the pump 1 is running and the closure valves of all of the dispensing outlets 7 are closed, the pressure in the transducer 5 rises to 70 p.s.i. and this trips the comparator circuit 14 which transmits a stop signal to the latch circuit 1 6 so that the motor 1 7 is stopped. As soon as one or more of the closure valves at the dispensing outlets 7 are opened, the pressure in the transducer 5 falls below 30 p.s.i. and this triggers the first comparator circuit 1 3 which produces a signal which starts the timer 1 5 and causes the latch circuit 1 6 to start the motor 1 7 of the pump 1.

Provided that the pump 1 is operating correctly and pumping liquid, the pressure at the transducer 5 very quickly rises to above 30 p.s.i. and provided that this happens before the timer 1 5 has timed out, the latch 1 6 maintains the motor 1 7 and the pump 1 in operation. One or more beer dispensing operations can then take place with the pump 1 remaining in operation until all of the closure valves at the dispensing outlets 7 are closed.

As soon as these valves are all closed, the presure in the transducer 5 rises to 70 p.s.i.

and this triggers the comparator circuit 14 to cause the latch 1 6 to stop the motor 1 7.

If however, flow through the pump 1 is not established, before the timer 1 5 has timed out, the timer 1 5 causes the latch 1 6 to stop the motor 1 7. If flow through the pump 1 has ceased because the keg to which it is connected is empty, as soon as the keg has been replaced by a full keg, a manual reset on the timer 1 6 is operated and this causes the pump 1 to be restarted. With a full keg connected to the pump 1, the pressure at the transducer 5 rises above 30 p.s.i. before the rest timer 1 6 times out and accordingly a dispensing operation can take place.

Similar automatic operations take place if at any time during dispensing the pressure in the transducer 5 falls below 30 p.s.i. thus causing the comparator circuit 1 3 to set the timer 1 5 in operation. Unless the pressure has been restored before the timer times out, the timer 1 5 operates the latch 1 6 to stop the motor 1 7. This may occur because the keg is empty or because there is a gas lock in the pump 1. When either of these occurrences have been rectified, the timer is again reset manually.

The cycle of operations which occur in dependence upon the pressure in the pressure transducer 5 are illustrated in Fig. 2 in the case where initially the pump 1 is operating correctly and establishes an outlet pressure greater than 30 p.s.i., but during the course of operation the keg to which the pump 1 is connected is emptied and is replced by a new full keg.

The second example is generally similar to the first example with the addition of a motor speed control unit 1 8 which is connected in series between the latch circuit 1 6 and the motor 1 7 and is also connected to the output of the Hall-effect device 12 by a line 1 9. The set pressure at which normal dispensing takes place, which is aproximately 50 p.s.i. (30 bar) is determined by the manual setting of the speed control unit 1 8.

While the pump 1 is in operation at a speed determined by manual setting of the speed control unit 18, the closure valves at further beer dispensing outlets 7 are opened, the pressure in the transducer 5 falls and as it falls, the changing voltage output from the Hall-effect device 1 2 which is fed directly to the motor speed control unit 1 8 through the line 1 9 causes the motor speed control unit 1 8 to increase the speed of the motor 1 7 and thus restore the pressure in the pressure transducer 5 to its previous value, typically 50 p.s.i. Correspondingly, an increase of pressure in the transducer 5 produces a decrease in the pump speed to cause the pressure at the transducer 5 to fall again.It is of course essential that the automatic speed control should not be such that upon closing of the valves at all of the dispensing outlets 7 the pressure at the transducer 5 is prevented from rising to a pressure sufficient to trip the second comparator circuit 14 as otherwise the pump would not be stopped when all the outlets 7 were closed. Thus the manual set speed governs the minimum speed of the motor 17.

When the set pressure at which dispensing takes place is altered by adjusting the speed control unit 18, it may be desirable also to alter the pressure at which the comparator circuit 14 is tripped. This alteration may be made manually by an operator, but alternatively there may be a connection between the speed control unit 1 8 and the comparator circuit 14 by which the speed control 1 8 transmits a signal to the comparator circuit to vary the pressure at which the circuit 1 4 is tripped in dependence upon the set pressure at which dispensing takes place. The comparator circuit 1 4 may in this way be adjusted to be tripped a pressure which is a predetermined amount, for example 10 ps.i. (0.6 bar), above the set dispensing pressure.

Claims (9)

1. An apparatus for dispensing beer or other liquid from a container through a dispensing outlet, the apparatus comprising an electrically driven pump having an inlet arranged to be connected to a container of the liquid, an outlet connected to a closure valve at the dispensing outlet, a non-return valve downstream from the pump and upstream of the closure valve, a pressure sensitive means which is actuated in dependence upon the pressure of the liquid between the non-return valve and the closure valve, and a pump control circuit to which the pressure sensitive means is connected and which includes a timing device, the pressure sensitive means and the pump control circuit being arranged so that the pump and the timing device are started when the pressure of the liquid between the non-return valve and the closure valve falls below a lower predetermined pressure, the timing device stopping the pump if the pressure does not rise above the lower predetermined pressure within a time determined by the timing device, and the pressure sensitive means also being arranged to stop the pump upon the pressure of the liquid between the non-return valve and the closure valve rising above a higher predetermined pressure.

2. An apparatus according to claim 1, in which the pressure sensitive means includes a Hall-effect device which produces an output voltage which is dependent upon the strength of a magnetic field to which it is subjected.

3. An apparatus according to claim 2, in which the pressure sensitive means also includes a permanent magnet which is movably mounted and has means by which it is moved towards and away from the Hall-effect device as the pressure in the liquid rises and falls.

4. An apparatus according to claim 3, in which the magnet is supported by a helical compression spring acted on by a rolling diaphragm subjected to the pressure of the liquid between the non-return valve and the closure valve.

5. An apparatus according to claims 2, 3 or 4 in which the pressure sensitive means also includes two comparator circuits set at different trip levels with the output from the Hall-effect device being fed to the two comparators, the first one of the two comparator circuits tripping at the lower predetermined pressure and the second comparator circuit tripping at the higher predetermined pressure.

6. An apparatus according to claim 5, in which the pump motor control circuit includes a latch circuit in which the output from the first comparator circuit is fed to the timing device and to the latch circuit and in which th output of the second comparator is fed to the latch circuit.

7. An apparatus according to any one of the preceding claims, in which the pump motor control circuit also includes a motor speed control unit.

8. An apparatus according to claim 7 when dependent upon claim 2 or any other claim when dependent upon claim 2, in which the motor speed control unit is fed with the output from the Hall-efect device and is ar ranged to provide a substantially constant output pressure from the pump.

9. An apparatus according to claim 1, constructed substantially as described with reference to the accompanying drawings.