EP0353104A1

EP0353104A1 - An improved changeover valve system

Info

Publication number: EP0353104A1
Application number: EP89307739A
Authority: EP
Inventors: John Whitford
Original assignee: Penryn Building Co a partnership of Jenkin David William Chinn Marylin
Current assignee: Penryn Building Co a partnership of Jenkin David William Chinn Marylin
Priority date: 1988-07-29
Filing date: 1989-07-31
Publication date: 1990-01-31
Also published as: GB8818131D0

Abstract

A changeover valve system has at least two inlets (54, 55) connectable to respective liquid sources, a single outlet (105) and valve shutter means (100), for selectively interconnecting one of the inlets (54, 55) with the outlet (105), and means (36, 37) for detecting when a liquid source (11, 12) is or is about to become exhausted for directing fluid under pressure to commute the valve shutter (100) so as to interconnect the other of the two inlets (54, 55) with the outlet (105); the pressure fluid circuit is a closed circuit having absorbers (90) for the pressure fluid displaced by the valve shutter (100) upon commutation.

Description

The present invention relates to a changeover valve system, and particularly, although not exclusively, to a changeover valve system suitable for controlling the flow of fluid from a plurality of sources thereof, such as beer kegs, to a single delivery outlet.
One of the problems encountered in the distribution and delivery of beer derives from the necessity for handling the beer in convenient containers which can be manipulated by hand and delivered to the large number of individual public houses from which it is to be dispensed. In establishments where a large quantity of beer is consumed it is frequently necessary to connect a new keg of beer to the delivery pipe work which leads from the cellar where the kegs are housed to the dispensing outlet. Although reference will be made hereinafter to the particular application of the present invention to the dispensing of beer, it will be appreciated that the generality thereof is not compromised thereby and changeover valve systems formed in accordance with the principles of the present invention may be made and adapted for many other different applications.
In an earlier European Patent application No 86.307472.0 filed by the same applicant, and which claims priority from an earlier UK Patent application No 85.23969 a valve for a liquid delivery system is described in which at least two inlets are connectable to respective liquid sources and to a single outlet, with valve shutter means being provided for selectively interconnecting one of the two inlets with the outlet and there further being provided means for detecting when a liquid source becomes exhausted and for commuting the valve shutter means so as to interconnect the other of the two inlets with the outlet. This earlier system makes it possible for a keg automatically to be exchanged when exhausted for a fresh keg without any supervision. The above system incorporated a spool valve for controlling the liquid flow by means of pistons at each of two opposite ends, the movements of the pistons being effected by a pressure differential exerted by gas pressure drawn from a gas pressure source such as a carbon dioxide cylinder, and directed by a sensor arrangement incorporating a plurality of diaphragms and valves operable to detect when an imbalance occured upon exhaustion of a keg from which delivery was being taken.
A modified valve arrangement which overcomes some of the problems experienced in practical application of the valve system described in European Patent application No 86.307472.0 referred to above are discussed in a further British Patent application No 87.23541 which incorporates a modified valve which does not rely on pressure differentials across a diaphragm and which, consequently, is not subjected to the problem of unwanted commutation when a plurality of delivery valves are simultaneously opened to cause a reduction in the pressure in the delivery line. The modified valve acts to detect the level of liquid in a float or sensor chamber and to cause commutation of the spool valve when the liquid is detected to fall below a certain critical threshold value which indicates that the liquid source is about to become exhausted.
The present invention provides further improvements over the original system by providing a changeover valve circuit for a liquid delivery system, of the type having at least two inlets connectible to respective liquid sources, a single outlet and valve shutter means for selectively interconnecting one of the said two inlets with the said outlet, means for detecting when a liquid source is or is about to become exhausted for directing fluid under pressure to commute the valve shutter means so as to interconnect the other of the said two inlets with the said outlet, in which the pressure fluid circuit is a closed circuit having at least one absorber for the pressure fluid displaced by the valve shutter upon commutation.
The means for detecting the exhaustion of the liquid source is preferably sensitive to a liquid/gas interface at a point upstream of the valve shutter means.
In a preferred embodiment of the invention the liquid path through the valve is controlled by a spool valve having at least one control piston and the position controlling pressure fluid is a gas under pressure directed into a piston chamber by gas valves sensitive to the liquid level in a float chamber.
The simplest embodiment is one adapted to exchange between two sources of liquid so that, whilst one is connected to the delivery outlet the other may be exchanged for a fresh, full container. In this case there are preferably provided two pistons one at each end of a spool valve spindle, each piston being housed in a respective piston chamber to which gas under pressure can be directed by one of two sets of primary and secondary gas valves, a first set of which is provided to control the flow of gas from a gas pressure source to a first of the piston chambers, and the second set of which is provided to control the flow of gas from the gas pressure source to the second piston chamber.
In such an arrangement each liquid inlet preferably has an associated float valve operable to allow the flow of liquid into the valve, but to close the associated inlet from a pressurised supply source against the flow of gas into the associated inlet. The float valve associated with at least one inlet may have a transparent body whereby the position of a buoyant body within the float valve is visible from the outside. The float valve or valves may have gas discharge ports with manually operable control valves allowing the selective exhaust of gas through the float valve upon operation of the manually operably discharge valve.
In order to ensure complete gas tightness of the system so that it is entirely self-contained, the pistons in the spool valve are preferably provided with rolling diaphragm seals between the piston and the housing. In this case the pistons are not a close sliding fit in a bore as it conventional, but rather may be significantly smaller in diameter than the cylinder to allow room for the rolling diaphragm seal.
Further, in order to accommodate displacements of gas under pressure within the system the gas controlling float valve preferably has a secondary absorber chamber with a resiliently biased plunger or piston therein.
The preferred embodiment of the invention also includes a manifold having a gas primary input from the pressurised gas source and primary outlets leading to the said float valves, float valve outlets being connected to respective secondary gas inlets in communication with respective secondary gas outlets, two uni-directional valves interconnecting respective primary gas outlets and respective secondary gas inlets.
One embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic circuit diagram of the delivery system as a whole;
Figure 2 is an axial section through the spool valve of the embodiment of Figure 1;
Figure 3 is a section through one of the float valves of the circuit of Figure 1; and
Figure 4 is a section through the manifold of the circuit of Figure 1.

Referring now to the drawings, the circuit is adapted to draw liquid from one of two containers, in this example beer kegs, 11, 12 and deliver it along a delivery line 13 to a beer dispensing tap 14. As is known, the kegs 11, 12 would normally be maintained in a cellar some considerable distance from the delivery tap.
Delivery of liquid from the kegs 11, 12 is urged by a compressed gas from a source in the form of a carbon dioxide cylinder 15 delivering compressed gas via a pressure reduction valve 16 to a gas delivery line 17 leading to a preliminary manifold 18 from which lead three outlet lines, a first 19 to the keg 11, a second 20 to the keg 12 and a third 21 leading to a manually operable interception valve 22 mounted on a fluid control spool valve 23 the details of which will be described hereinbelow.
From the interception valve 22 the gas pressure is delivered via a line 24 to a central manifold 25 which, as can be seen with reference to Figure 4, has a primary input 26 which communicates with a central manifold chamber 27 closed by two uni-directional ball valves 28, 29 from internal gas passages 30, 31 and communicating with two primary gas outlets 32, 33 which lead via gas delivery lines 34, 35 to respective float controlled gas valves 36, 37 the detail of which will be described in relation to Figure 3. Each of the float controlled gas valves 36, 37 has a respective gas inlet 38, 39 and a respective gas outlet 40, 41 which lead via gas return lines 42, 43 to respective secondary gas inlet ports 44, 45 of the central manifold 25. The secondary gas inlets 44, 45 communicate with the internal gas passages 30, 31 closed by the uni-directional valves 28, 29 and communicate directly with secondary gas outlets 46, 47 which are connected to valve control lines 48, 49 leading to respective control inputs 50, 51 of the spool valve 23.
Beer from the kegs 11, 12 is delivered via respective beer distribution lines 52, 53 leading to respective beer inlet ports 54, 55 of the control valve 23 via respective float controlled gas valves 36, 37.
Turning now to Figure 3 the float controlled gas valve 37 is illustrated in more detail it being appreciated that the float controlled gas valve 36 is identical in all respects, but coupled in an opposite configuration as illustrated in Figure 1.
In the float controlled gas valve of Figure 3 the beer inlet which is connected to the distribution line 53 is identified with the reference numeral 56 and the beer outlet from the float valve is identified with the reference numeral 57. The inlet and outlet 56, 57 are formed in a beer manifold 58 to one side of which is connected an upright generally cylindrical float chamber 59 and the other side of which is connected a gas valve body 60 for the gas valve 37.
The float chamber 59 is surmounted by a float chamber closure body 61 having a radial outlet passage 62 communicating with an axial passage 63 which houses a manually controllable interception valve 64 mounted on an elongate central axial rod 65 connected at its upper end to a knob 66 and at its lower end to an enlarged float-engaging body 67. A float 68 is located within the float chamber 59 and slidably engaged on the central rod 65. At its lower end the float 68 carries a keeper plate 69 of ferromagnetic material the function of which will be described in more detail below.
The gas valve body 60 has a central valve chamber 70 housing a valve body constituted by a magnet 71 secured to a valve shutter 72 having on its lower face a resilient shutter pad 73 which engages over the hollow upper opening of a conical nozzle 74 located in a gas transfer passage 75 within the valve body 60. The gas transfer passage 75 communicates via a gas transfer inlet passage 76 with the gas inlet 39.
Extending radially from the central valve chamber 70 is a gas outlet transfer passage 77 which communicates with the gas outlet 41 and also with an axial gas transfer passage 78 extending axially of the body 60, offset from its centre line, and which communicates with a gas absorber chamber 79 formed as an open ended cavity in the lower end of the valve body 60.
Surrounding the cavity 79 is a radial flange 80 by which a cup-shape closure body 81 is secured to the gas absorber chamber 79 to form a closed cavity. Between the flange 80 and a corresponding flange 82 of the cap 81 is trapped a diaphragm 83 having a U-section annular channel surrounding a central clamped region 84 secured between opposite plunger members 85, 86 which are secured together by a central bolt 87. The two plunger members 85, 86 are respectively resiliently biased to a central position by respective coil springs 88, 89 and the internal space 90 enclosed between the diaphragm 83 and the cap 81 is vented to atmosphere through a passage 91.
When the float 68 in the float chamber 59 is at its lowermost position as illustrated in Figure 3 the keeper plate 69 magnetically attracts the magnet body 71 causing this to rise within the central valve chamber 70 lifting the resilient shutter pad 73 from the nozzle 74 and allowing communication from the gas inlet 39 via the gas transfer inlet passage 76, the gas transfer passage 75 to the gas outlet transfer passage 77 to the gas outlet 41 and, via the axial passage 78 to the absorber chamber 79. In order to ensure that the central valve chamber 70 is gas tight the junction between the valve body 60 and the manifold 58 is made with the interposition of a membrane 92 which, however, does not prevent the magnetic interaction between the magnet 71 and the keeper 69. When the float 68 rises within the float chamber 59, on the other hand, the weight of the magnet 71, in the absence of the keeper 69, holds the valve shutter pad 73 against the nozzle 74 closing communication between the gas inlet 39 and the gas outlet 41.
Turning now to Figure 2 beer from the beer outlet 57 is delivered, as can be seen from Figure l, along the beer delivery line 53 to an inlet port 55, illustrated schematically in Figure 2. The inlet port 55 leads to a right hand beer inlet chamber 93 of a cylindrical valve housing 94 having respective plunger housings 95, 96 at opposite ends for receiving respective plungers 97, 98 carried at opposite ends of a spool 99 having a central seal 100 sealing within two coaxial partitions 101, 102 which separate the interior of the spool valve into three chambers, namely the right hand beer inlet chamber 93, a left hand beer inlet chamber 103 and an outlet chamber 104 having an outlet port 105 which leads to the beer delivery ]ine 13.
Over the spool valve body 94 is fitted a gas manifold 106 having inlet ports 50, 51 from the valve control lines 48, 49 which communicate via transfer passages 107, 108 with respective plunger chambers 109, 110 within the enlarged plunger housings 95, 96. The manifold 106 also carries the on/off switch 22 which in this embodiment is constituted by a slide 111 having respective sealing rings 112, 113, 114 for closing passages (not shown) between the gas outlet line 21 and the gas line 24 of Figure 1.
The apparatus described above operates as follows. Assuming, initially, that the circuit is operating to dispense beer from the keg 12 so that the float controlled gas valve 37 is closed and the spool valve is positioned, as illustrated in Figure 2, with the spool 99 displaced to the left so that the seal 100 opens communication between the beer inlet port 55 and the outlet port 105. In this configuration the float 68 would be at the upper end of the rod 65 remote from the magnet body 71 so that the resilient shutter pad 73 is pressed by the weight of the magnet onto the conical nozzle 74. The beer circuit is completed from the keg 12 through the beer distribution line 53, the inlet valve 56, the float chamber 59, the outlet port 57, the beer distribution line 53 from the outlet port 57 to the beer inlet port 55 to the spool valve, the outlet port 105 from the spool valve and the beer delivery line 13 to the tap 14. As the keg 12 becomes exhausted no more beer is drawn from the beer distribution line 53 so that the level in the float chamber 59 starts to fall as beer is dispensed from the tap 14. Before the level in the float chamber 59 reaches a value such that gas or air would be drawn through the outlet port 57, however, the float 68 reaches the bottom of the chamber so that the keeper 69 attracts the magnet 71 causing the valve shutter pad 73 to be raised from the conical nozzle 74 allowing communication for gas under pressure from the gas inlet 39 through the valve to the gas outlet 41 which, passing along the line 43, through the manifold 25 to the valve control line 49 enters the gas inlet 51 and is transferred to the plunger chamber 110 via the transfer passage 108 causing the plunger 98 to move to the right drawing with it the spool 99 and the plunger 97 in the opposite plunger chamber 109. This causes the central seal 100 to be displaced from its position in the partition wall 101 to a corresponding position in the partition wall 102 allowing communication between the beer inlet port 54 of the opposite chamber and the beer outlet port 105. Communication is now established from the keg 11 through the other float controlled gas valve 36 and the spool valve 23 to the beer delivery line 13 without there having been any but the briefest of interruptions as the central seal 100 passes through a mid position where it closed both inlets 54, 55 from the outlet 105 before re-establishing communication between the inlet port 54 and the outlet port 105. This, at the same time, ensures that there is no possible backflow of beer from the right hand beer inlet chamber 93 to the left hand beer inlet chamber 103. The keg 11 can thus serve as the source of beer for the tap 14 until such time as it is desired to exchange the keg 12 for a new keg, at which point the on/off valve 22 is switched off thereby cutting off gas supply to the manifold 25 without requiring any further operations on the compressed gas source 15, and the keg 12 can then be exchanged in the conventional way. Once this has been done the operator re-closes the valve 37 by lifting the knob 66 which, at the same time, opens the exhaust valve 64 allowing trapped gas and froth from the fresh barrel to exhaust through the outlet port 62 which, as shown in Figure 1, can flow via a bleed pipe 115 into a collection vessel 116. The initial conditions are then re-established with the exception that the spool valve is positioned at its right hand end position and delivery takes place from the keg 11, and it requires only that the on/off switch 22 be turned on to allow automatic exchange of kegs to take place when the keg 11 becomes exhausted.

Claims

1. A changeover valve system of the type having at least two inlets connectable to respective liquid sources, a single outlet and valve shutter means for selectively interconnecting one of the said two inlets with the said outlet means for detecting when a liquid source is or is about to become exhausted for directing fluid under pressure to commute the valve shutter means so as to interconnect the other of the said two inlets with the said outlet, in which the pressure fluid circuit is a closed circuit having absorbers for the pressure fluid displaced by the valve shutter upon commutation.

2. A changeover valve system according to Claim 1, characterised in that the said means for detecting the exhaustion of the liquid source is sensitive to a liquid/gas interface at a point upstream of the valve shutter means.

3. A changeover valve system according to Claim 1 or Claim 2, characterised in that the liquid path through the valve is controlled by a spool valve having at least one control piston and the position controlling pressure fluid is a gas under pressure directed into a piston chamber by gas valves sensitive to the liquid level in a float chamber.

4. A changeover valve system according to any of Claims 1 to 3, characterised in that there are provided two pistons, one at each end of a spool valve spindle, each piston being housed in a respective piston chamber to which gas under pressure can be directed by one of two sets of primary and secondary gas valves, a first set of which is provided to control the flow of gas from a gas pressure source to a first of the piston chambers, and a second set of which is provided to control the flow of gas from the gas pressure source to the second piston chamber.

5. A changeover valve system according to any preceding Claim, characterised in that each liquid inlet has an associated float valve operable to allow the flow of liquid into the valve, but to close the associated inlet from a pressurised supply source against the flow of gas into the associated inlet.

6. A changeover valve system according to Claims 5, characterised in that the float valve associated with at least one inlet has a transparent body whereby the position of a buoyant body within the float valve is visible from the outside.

7. A changeover valve system according to Claim 5 or Claim 6, in which the float valve or valves have gas discharge ports with manually operable control valves allowing the selective exhaust of gas through the float valve upon operation of the manually operable discharge valve.

8. A changeover valve system as claimed in any preceding Claim, characterised in that the pistons in the spool valves are provided with rolling diaphragm seals between the piston and the housings.

9. A changeover valve system as claimed in any preceding Claim, characterised in that the gas controlling float valve has a secondary absorber chamber with a resiliently biased plunger or piston therein.

10. A changeover valve system as claimed in any preceding Claim, further including a manifold having a gas primary input from the pressurised gas source and primary outlets leading to the said float valves, float valve outlets being connected to respective secondary gas inlets in communication with respective secondary gas outlets, two unidirectional valves interconnecting respective primary gas outlets and respective gas inlets.