Closure unit for beer kegs

Abstract

A bush for a valved closure unit of the kind used in beer kegs comprises two-parts and when in a unit engages an opening in the keg. One part of the bush which engages the opening, is in the form of a hot brass stamping or stainless steel or aluminium casting. The other part of the bush is of stainless steel and is held in the first part by an interference fit and/or interfitting ribs and grooves and/or adhesive. The interstices between the parts are sealed by a sealant. A closure unit employing such a bush has a valve seat formed by an internal flange on the second member and a valve is guided as it moves towards and away from the seat.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to valved closure units for containers. Such closure units are widely used in beer kegs and the units are arranged so that the containers may be emptied and filled through the closure units.

Such a closure unit, hereinafter referred to as being of the kind specified comprises a bush arranged to be received in an opening in a container or keg, the bush normally being externally threaded near one end for threaded insertion into an internally threaded neck on the container, a downtube supported by the bush for extending into the container and spring-loaded valve means within the bush and associated with the downtube.

When the unit is used in a beer keg, the valve means are arranged to control the entry of carbon dioxide and the exit of beer from a full keg. Moreover, the valve means can be used to control the entry and exit of washing liquid and/or steam during washing of the keg and the entry of beer during filling of the keg. Normally, the valve means will be one of two types. The valve means will either comprise two concentric valves, one for beer and one for gas, each of the valves being separately spring loaded, or there may be a single valve member controlling separate beer and gas passages.

2. Description of the Prior Art

Heretofore, the bush of a closure unit of the kind specified has been made as a one-piece casting of stainless steel or aluminium or as a hot brass stamping and subsequently machined where necessary, the machining including producing a valve seat on the bush for the valve means and an external screw thread. Where the bush is of brass it has been chrome plated and where it has been of aluminium it has been anodised and epoxy coated. Such bushes of stainless steel are satisfactory but they are expensive and tend to pick-up when threadedly engaged in stainless steel neck fittings. However such bushes have good corrosion resistance. Chromed brass bushes do not pick up but the plating deteriorates and is damaged in use. Anodised and epoxy coated aluminium bushes do not pick up but are more susceptible to damage than chromed brass bushes.

It is one object of the present invention to provide improved forms of bush for such a closure unit.

These improved forms of the bush may have an inturned flange which provides a seat for the valve means or a valve member. While the seat is satisfactory it gives little or no guidance during movement of the valve member towards and away from the seat and misalignment may occur.

Moreover, in some known closure unit constructions, when the keg is being washed with the valve means at the bottom of the keg, the valve means forms pockets for the retention of washing liquid. This is undesirable.

It is another object of the present invention to provide a closure unit which overcomes these two problems.

SUMMARY OF THE INVENTION

According to one aspect of the invention we provide a two-part bush for a closure unit of the kind specified, the bush comprising a first, annular, metal part which has been formed by casting or hot stamping and having, in one end, a counterbore; a second part in the form of a stainless steel tubular member held permanently and firmly in the counterbore; and a sealant filling interstices between the first and second parts, the second part extending outwardly from the counterbore and being formed with support means enabling a spring abutment to be engaged therewith and supported thereon.

Normally the first part will have an external screw thread at the end thereof opposite from the counterbore, this thread enabling a unit including the bush to be received in an internally threaded neck on a container.

The first part may be formed from stainless steel by investment or die casting. If so the bush will be made wholly of stainless steel and will be cheaper than the known one-piece cast bushes. Alternatively the first part may be a hot brass stamping which has been chrome plated or an aluminium casting which has been anodised and epoxy coated. If so, the part of the bush most prone to corrosion, i.e. the second part, will be of stainless steel so that the bush as a whole will have better corrosion-resistance properties than known one-piece brass or aluminium bushes, while in addition having the advantage of known brass or aluminium bushes that they do not pick-up when screwed into stainless steel necks on kegs. Where stainless steel bushes are fitted into stainless steel necks it is usual to wrap the male thread with PTFE tape to avoid the threads picking up.

Internally of the first part and adjacent to the threaded end thereof there may be provided lugs to engage a coupling device which, when the bush is in a unit, opens the normally closed valve means thus to establish communication between the downtube and the interior of the container and the coupling device. Instead of having internal lugs, the first part may have an external flange shaped to allow a coupling device to be engaged therewith. When used with a beer keg, the coupling device will be in the form of a dispense head which can be coupled to the closure unit to open the valve means and thus to allow carbon dioxide to be supplied to the keg and beer to be removed therefrom. Similarly the internal lugs or external flange can be used to engage another coupling device during washing and filling of the container.

The second part will have holes in the tubular wall thereof between the free ends of the second part and the open end of the counterbore. The support means are preferably provided by inwardly deformed portions of the wall of the second part adjacent to the free end thereof. These inwardly deformed portions may be such as to enable an appropriately shaped abutment to be engaged therewith by way of a bayonet-type connection.

In one arrangement of the bush the parts are held together by the second part having been forced into the counterbore so as to be held firmly therein by interference between the inner and outer surfaces of the counterbore and the second part respectively. The interference between the first and second parts must be such as to withstand the spring force and must also be such as to withstand vibration to which the unit is exposed in use, particularly during transport.

The said parts of the bush may be held positively against axial separation by interfitting formations which may be a circumferential groove in one part engaged by a circumferential rib on the other part.

Preferably there is a groove and rib on each part engaging respectively a rib and groove on the other part. Preferably, the circumferential rib on the second part is adjacent to the end thereof which is within the counterbore in the first part, and is externally chamfered to give a lead as the second part is entered into the counterbore in the first part. If desired an interference fit can be provided between the first and second parts which prevents relative rotation between the parts. Preferably the interference fit takes place between the base of the groove in the second part and the interfitting rib on the first part. Alternatively relative rotation between the parts is prevented by an adhesive between the parts or by mechanical means such as an axial ridge on one part engaging in an axial trough in the other part.

Preferably the second part is of a material sufficiently resilient, or having sufficient memory for shape, for said rib on the second part to be resiliently deflected inwardly as the second part is entered into the counterbore of the first part and then to enter the interfitting groove in the first part; the parts thus "snap" together. If an interference fit is required then the first part may be contracted, after the second part has been inserted in the counterbore, by a contracting tool applied to the exterior of the first part. Alternatively, the rib on said end of the second part can be forced outwardly into the groove in the first part while the latter is held against radial expansion.

In another arrangement the second part is held in the first part by an adhesive and means such as a co-operating axial ridge and trough may be provided on the parts to prevent relative rotation thereof.

In some embodiments of the invention the first part is provided with an internal valve seat with which the valve means co-operates. This internal valve seat may be convergent and may be frusto-conical or part-spherical.

In some arrangements the end portion of the second part within the counterbore provides a seat for the valve means. Such seat may be provided by an internal flange on said end portion. The flange may be supported by a shoulder on the first part. The first part may have an inwardly extending flange overlying the internal flange on said end portion, the flange on the first part providing an upper surface against which part of the dispense head seals when the unit is in service in a beer keg. The two flanges together resist the downward sealing force of the dispense head.

In a further arrangement the valve seat is provided by a length of the second part whose wall thickness increases progressively in a direction towards the inner end of the counterbore so as to provide said length with a frusto-conical or part-spherical inner surface.

The immediately foregoing construction provides a valve seat whose dimension, considered axially of the bush, is appreciably greater than that which can be provided if the seat is formed by an internal flange on the second part as described above. This enables the valve seat to provide guidance for the valve means as it moves towards and away from the valve seat and makes the provision of separate guidance means unnecessary.

According to another aspect of the invention we provide a closure unit of the kind specified wherein the bush comprises a first, annular, metal part which has been formed by casting or hot stamping and has, in one end, a counterbore and a second part in the form of a stainless steel tubular member held permanently and firmly in the counterbore and extending outwardly therefrom, wherein the valve means comprises a member of resilient material mounted adjacent to one end of the downtube and having a convergent sealing surface for engagement with a seat on the bus; and wherein said seat is provided by the inner periphery of an internal flange on the second bush part so as to provide substantially a line seal between the flange and said member, the surface of the flange between said inner periphery thereof and the part of the bore of the second bush part which surrounds the downtube being so shaped that when said one end of the downtube is the lower end the flange and bore provide no pockets for the retention of liquid within the bush when said member is disengaged from said seat: the unit also including a guide member movable with the valve member relative to the bush and dimensioned with respect to the bore of the bush so as to move freely therein parallel to the longitudinal axis of the downtube so as to guide the valve member when the latter is moving towards and away from its seat to prevent misalignment of the valve member and the seat, said guide member being shaped or apertured so as to permit passage of fluid past the guide member between the downtube and the bush.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a section through a bush and closure unit constituting a first embodiment of the invention;

FIG. 2 is a section through a bush and closure unit constituting a second embodiment of the invention;

FIG. 3 is a detailed view of the spring abutment washer of the unit of FIG. 2;

FIG. 4 is a section through a bush and closure unit constituting a third embodiment of the invention;

FIG. 5 is a detail section of a modification of the embodiment shown in FIG. 4;

FIG. 6 is a section through a bush and closure unit constituting a fifth embodiment of the invention;

FIG. 7 is a section through a bush constituting a sixth embodiment of the invention;

FIG. 8 is a section through a closure unit constituting a seventh embodiment of the invention;

FIG. 9 is a section through a closure unit constituting an eight embodiment of the invention; and

FIG. 10 is a section through a closure unit constituting a ninth embodiment of the invention.

Referring now to FIG. 1, the closure unit comprises a downtube 10 having an upper portion 11 of larger diameter than a lower portion 12. The portion 11 provides a chamber 13 in which is mounted a beer valve 16. The valve 16 engages a seat 15 on a gas valve 14 which is received within the portion 11 of the downtube. The valve 16 is urged upwardly by a spring 17 which engages on a ring 19 forming part of a spider 18 which has three equiangularly spaced legs 20 which engage with a shoulder 21 between the parts 11 and 12 of the downtube.

The valve 14 has bonded thereto a rubber ring 30 which engages a valve seat 28a on a bush 25. The valve 14 fits within the upper end of the part 11 of the downtube against a flange 32 and a spring 31 engages the flange 32 and also a washer 26 which rests on inwardly deformed portions 34 on the bush formed as will be described below. The washer 26 has three recesses 37 which can clear the portions 34, the recesses 37 being formed in three circumferentially spaced portions 36 which are interposed between three circumferentially spaced portions 35, the portions 35 and 36 being at different levels. In use the unit is received in an internally threaded neck 33 secured to a container, not shown.

The bush 25 comprises a first part 40 which has been formed by casting or hot stamping and a second part 41 which is a stainless steel tube. The part 40 may be formed as a stainless steel investment casting or aluminium die casting or as a hot brass stamping. After casting or stamping the part will be machined as required and if made of brass will be chrome plated and if made of aluminium will be anodised and epoxy coated. The part 40 is of annular form and is provided with an internal annular shoulder 29 which is machined to produce the valve seat 28a which is frusto-conical or may be part-spherical. The part 40 is provided with an external screw thread 42 which can engage with the internal thread on the neck 33. The part 40 is also provided with two diametrically spaced internal lugs, one of which is shown at 43. These lugs are arranged to engage a dispense head or other coupling means which can be engaged with the part 40 to open valves 14 and 16.

The first part 40 is provided with a counterbore 44 in which is received one end of the second part 41. This part 41 is made from commercially available stainless steel tube and is provided with three equiangularly spaced apertures 28 arranged just below the bottom of the neck 33 so that when the container is inverted during washing it can drain completely through the unit. The three inwardly deformed portions 34 are provided by slitting the tube at 34a and then bending the parts inwardly. The washer 26 can be engaged in the lower end of the part 41 by arranging the recesses 37 opposite to the inwardly deformed portions 34 then pushing the washer through into the bore 45 of the part 41 and then turning the washer so that the inwardly deformed portions 34 engage the parts 35. The washer 26 provides an abutment for the spring 31 and is supported on the inwardly deformed portions 34.

The length of tube 41 forming the second part of the bush is, during manufacture of the bush, forced into the counterbore 44. The interference between the counterbore and the tube is sufficient to resist the spring force and vibration when the unit is in use and we have found that an interference of between 0.3 and 0.5mm on a diameter of about 44mm is satisfactory. The upper end of the tubular part 41 may be slightly chamfered to give the tube a lead into the counterbore 44. After the tube has been forced into the counterbore, the bush is treated with resin to seal the interstices of the joint between the parts 40 and 41.

After casting or stamping the first part 40 is machined as required to provide the valve seat 28a and any other important surfaces. If the first part is made of a hot brass stamping it is then chrome plated. The stainless steel tube 41 is then forced into the counterbore 44. The assembled bush is then cleaned by a known method of electropolishing which involves an electrolytic step which etches the surfaces of the parts.

The cleaned bush is then placed in a vacuum chamber, the pressure in the chamber is reduced to a low level and the chamber is then filled with resin. The resin migrates to the interstices between the first and second parts (40 and 41) of the bush and lodges therein. The bush is then removed from the resin and washed to remove all the resin from the external surfaces. The bush is then heated in hot air to a temperature of between 130.degree. and 140.degree. C. for at least four hours. The resin which is used is a non-toxic polyester or epoxy resin suitable for metal sealing, for example the epoxy resin sold under the designation V15 and formulated by Industrial Impregnations Limited, and this hot air treatment cures the resin in the interstices between the first and second parts of the bush and thus prevents such interstices becoming a bacterial trap. Finally, the bush is wet blasted to remove any traces of resin on the surface which were not removed by the washing.

The embodiment so far described has two concentric valves 14 and 16. FIG. 2 shows a second embodiment having a single valve member which controls both the gas and beer passages.

Referring to FIGS. 2 and 3 the bush is indicated at 50 and comprises a first part 51 which is made either as a casting or stamping as described for the part 40. The part 51 is provided with a counterbore 52 in which is received a stainless steel tube 43. The tube has been forced into the counterbore as described above in relation to the embodiment of FIG. 1. The lower end of the tube 53 has support means 54 which is similar to the means 34 described and shown in FIG. 1.

The part 51 is provided with an internal flange 55 which provides a seat for a valve member 56. The valve member is slidable upon a central tube 57 forming the upper end of a downtube and which is internally threaded at 58 to receive the lower portion 59 of the downtube. The central tube 57 has a collar 60 which fits closely within the tube 53. The collar is provided with three slots, one of which is shown at 61 in FIG. 3, to pass the support means 54 and with three locking recesses 62 to receive the support means 54 once the collar has been inserted in the tube 53 with the support means 54 aligned with the slots 61 and then turned to enable the support means 54 to be received in the recesses 62. The central tube 57 has ports 63 at its upper end which is closed at 64. The collar 60 has drain slots 60a.

The valve member 56 comprises a Z-shaped metal reinforcing member which is embedded in a rubber ring 66. The rubber ring 66 carries an external metal washer 67 which is engaged by the upper end of the spring 68 whose lower end engages spring support means provided by the collar 60. The rubber ring 66 seals on the seating 55 at 69 and on the central tube 57 at 70.

The part 51 is provided with an external screw thread 71 which is received in a neck 72 secured to a container, not shown. The part 51 is sealed to the neck 72 by means of a rubber ring 73 and is provided with a flange 74 which is of circular shape with a number of flats thereon so that it may be engaged by a collar carried by a dispense head. Alternatively the part 51 may be sealed in the neck 72 by an O-ring 74 at the bottom of the part 51.

The bush 50 is made in the same manner as described in relation to FIG. 1 and the interstices between the first and second parts thereof are filled with resin to avoid bacteria traps. The closure unit is shown in its closed position in FIG. 2 but is opened by engaging the valve member 56 and moving it downwardly which simultaneously opens the ports 63 and also the passage between the central tube 57 and the bush.

Referring now to FIG. 4 this shows a third embodiment of the invention in which the two part bush comprises a first part 110 which is a casting or stamping made as described for the part 40 and a second part 111 which is a stainless steel tubular member either formed of tube or made by deep drawing as described below. The part 111 has an inturned flange 111a which provides a valve seat 112. The parts 110 and 111 are interfitted by ribs and grooves. The upper end of the part 111 has a rib 113 and a groove 114. The rib 113 has a chamfered surface 115 and the groove 114 has a base 116 and side walls 117. The lower end of the first part 110 has a groove 118 and a rib 119 adjacent thereto. The rib 113 is received in the groove 118 and the rib 119 is received in the groove 114. Since the rib 113 overlies the rib 119 the parts 110 and 111 are positively located against axial separation. There is also an interference fit between the base 116 of the groove 114 and the rib 119. This interference fit may be obtained by contracting the part 110 around the part 111 (which is internally supported) either by a segmental contracting tool or a tool having a tapering bore.

The bush is assembled by entering the upper end of the part 111 into the counterbore 120 in the lower end of the first part 110. The chamfered surface 115 engages the lower corner of the rib 119 so that the upper end of the part 111 is deflected inwardly as it is pushed into the first part. Once the rib 113 is clear of the rib 119 it springs back to the position shown in FIG. 4 overlying the rib 119 and thus providing a positive location against axial separation of the parts. Contraction of the part 110 is then effected.

In an alternative method of assembly the upper end of the tube 111 is entered into the counterbore 120 with the rib 113 deflected inwardly clear of the rib 119 and then the upper part of the tube is expanded to cause the rib 113 to enter the groove 118 while supporting the exterior of the first part 110 to prevent radial expansion thereof during this forming operation.

The bush once assembled is cleaned and the interstices filled with resin as described above.

The flange 111a is supported on a shoulder 121 in the first part and provides the valve seat 112. The upper surface 112a of the flange 112 provides a sealing surface for part of a dispense head when the unit is in use. FIG. 5 shows a modification in which the flange 112 engages the underside of an internal flange 110a formed on the first part 110 and in this modification the upper surface of the flange 110a provides the sealing surface for the dispense head. The combined strength of the flanges 110a and 112 withstands the sealing pressure and prevents deformation of the flange 112 which may happen if the flange 110a is not present and the sealing pressure is increased beyond that normally encountered due, for example, to misuse of the dispense head.

In addition to the bush, the closure unit of FIG. 4 includes a downtube 122 having a lower portion 123 of smaller diameter and an upper portion 124 of larger diameter. Fitting within the upper end of the portion 124 is a gas valve 125 and this carries a rubber seating 126 which engages with the seat 112 on the flange 111a. The gas valve is sealed to the portion 124 of the downtube by means of an O-ring 127. The gas valve has an internal seat 128 which is engaged by a rubber seating 129 on a beer valve 130. The beer valve is urged upwardly by a spring 131 into engagement with the seat 128, the spring engaging a spider 132 which engages a shoulder 133 between the parts 123 and 124 of the downtube 122.

The gas valve 125 is urged into engagement with the seat 112 by a spring 134 which engages a washer 135 which in turn is supported on parts 136 inset from the lower edge of the part 111 as described in relation to FIG. 1. The spring 134 also acts against a washer 137 which in turn engages under a flange 138 at the top of the downtube. The washer 137 moves freely within the cylindrical part of the tubular member 111, the radial clearance between the washer and the tubular member being no more than required for free movement so that the washer can guide the valve 125 onto its seat as the valve closes. The washer 137 is provided with a plurality of cutouts such as 139 to enable gas to flow past the washer.

FIG. 6 shows another embodiment of the invention. There is a two-part bush comprising a flanged upper part 150 (made as a casting or stamping as described for the part 40) which is threadedly engaged in a container neck 151. A lower tubular part 152 is engaged with a snap-in and interference fit in the bush part 151. Thus the part 150 has a groove 150a and a rib 150b which interfit with a rib 152a and a groove 152b on the part 152. There is an interference fit between the rib 150b and the groove 152b. The upper part 153 of the downtube 154 has a flange 154a which fits closely with a bayonet connection into the lower tubular part 152 and rests on inset parts 152c at the lower end of the part. The lower part of the downtube is indicated at 155 and is received in a counterbore 156 in the part 154. The upper part 153 of the downtube is closed at 157 at its upper end and is provided with ports 158 therein. The ports 158 are located in an external annular recess 158a formed in the downtube, the recess having smoothly rounded edges 258b. Ports 159 are also provided in the flange 154a.

A valve member 160 is slidable about the downtube and comprises a member of rubber or similar resilient material 161 which is carried by a washer 162 of generally Z-shape in section. The washer has a central flange 163, a cylinder portion 164 and a flat portion 165. The rubber member 161 encapsulates the washer 162 and a part of the rubber member 161 has a conical or convergent surface 167 which engages with substantially line contact a seat 168 formed on a flange 168a of the tubular member 152. The flat part 165 of the washer has cut-outs 169 around its periphery to enable gas and beer to flow between the downtube and the bush. The internal periphery 170 of the valve member 160 engages the downtube part 153 with substantially line contact, above the ports 158 when the unit is closed and below the ports 158 when the unit is open. The rounded edges 158b prevent cutting of the resilient material of the valve member as it moves over the recess 158.

The closure unit is shown in its closed position; to open it, the valve member 160 is depressed thus moving the valve member against a spring 170 (which biases the valve member to a closed position and engages the flange 154a) so that the ports 158 are exposed and an opening is provided between the seat 168 and the valve member. The interior of the cylinder member is placed in communication with the interior of the downtube 154 through the ports 158 and fluid can flow around the cylindrical member and between the seat 168 and the valve member 160 and through the cut-outs 169. Because the seat 168 is formed by an inturned flange it gives little guidance to the valve member but this is guided by engagement of the periphery of the flat part 165 of the washer with the bore of the tubular member 152.

FIG. 7 shows a bush which comprises a first part 210 in the form of a hot brass stamping which has been chromium plated or an aluminium die casting which has been anodised and epoxy coated and a second part 211 which is a tubular member cast in stainless steel.

The part 211 has a thickened end portion 212 whose inner surface 213 is of frusto-conical form. This surface acts as a valve seat for a valve (not shown) similar to, for example, the valve 14 or 125 of FIGS. 1 or 4. The surface 213 could be part-spherical if desired. The outer surface 214 of the end portion 212 provides a rib of frusto-conical form and is received within a groove 215 in the first part 210. A groove 216 in the outer surface of the tubular member 211 also receives an internal rib 217 on the first part 210.

The interlock between the groove 214 and the rib 212 and the groove 216 and the rib 217 prevents the separation of the first part 210 and the tubular member 211 in a manner similar to that described in relation to FIGS. 4 and 6. Any interstices formed between the mating surfaces of the first part 210 and the tubular member 211 are filled by sealant material as described above. The free end of the tubular member 211 is provided with circumferentially spaced inset parts 218 for supporting a washer such as 26 or 135.

Various modifications may be made to the bush as described in detail. In a first modification a mechanical interlock to prevent axial separation of the parts 110 and 111 or 150 and 152 by means of the ribs and grooves will be provided but there will be no interference fit between the rib 119 or 150b and the groove 114 or 152b. Means will be provided for preventing relative rotation between the parts 110 and 111 or 150 and 152. Such means may be an adhesive between the parts or there may be a longitudinal ridge on the part engaging a longitudinal trough in the other to prevent relative rotation.

In another modification the part 41 or 53 may be inserted into a counterbore in the part 40 or 50 with clearance and the parts held together by a suitable adhesive. There may be an axial ridge on one part and an axial trough on the other part which interengage to prevent relative rotation between the parts.

The part 111 or 152 may be made from stainless steel tube. Alternatively, the part may be made by deep drawing so as to form a cup with cylindrical walls and a circular base. This base is then pierced to provide e.g. the flange 111a, 168a and the flange at the other end of the tubular member which will have been formed during drawing will be clipped and the drawing then continued to wipe in the edge portion of the tubular member.

Referring now to FIG. 8, the closure unit comprises a bush 310, a downtube 311, an outer valve member 312 and an inner valve member 313. The bush is of the construction described in relation to FIG. 4. Briefly, the bush comprises a first part 314 which has been formed as a casting of stainless steel or aluminium or as a hot brass stamping. In one end, the first part has a counterbore 315 in which is received the upper end of a second part 316. The second part 316 is a stainless steel tubular member which is provided with an external groove 317 in which is received a rib 318 on the first part 314. Sealant fills interstices between the first and second parts as described above.

The upper end of the second part is provided with an internal flange 319 part of whose inner periphery provides a seat 320 for the outer valve member 312. The lower end of the second part 316 is provided with three inwardly-deformed portions 321 formed by slitting and bending the wall of the second part and engaged on the deformed portions, with a bayonet connection, is a washer 322 forming a guide member for the downtube 311. The washer 322 is provided with three recesses which can be aligned with the deformed portions 321 so that the washer can be entered into the lower end of the bush and then turned so that the portions 321 engage the washer and provide an abutment therefor.

The downtube 11 has a first upper part 23 providing a first bore 323a, an intermediate part 324 providing a second bore 324a and a third lower part 325. The upper part 323 is of greater diameter than the intermediate part 324 and an external shoulder 326 is formed on the downtube at the transition between the parts 323 and 324. The lower part 325 is of lesser diameter than the intermediate part 324 and an internal shoulder 327 is formed at the transition between the parts 324 and 325.

The outer valve member 312 comprises a mass of resilient material, e.g. natural or synthetic rubber, which is provided with a central aperture 328, an internal, spherical seat 329 and a spigot 330 which fits sealingly within the bore 323a. In its unconstrained state the spigot 330 tapers downwardly and is a wedge fit in the parallel-sided bore 323a. The valve member 312 is reinforced by a first annular reinforcement 331 of generally L-shaped in cross-section. The reinforcement has a vertical limb 332 which extends into the spigot and a horizontal limp 333 which extends from the body of the valve and provides a guide member. The horizontal limb 333 is shown as provided with a thin covering of the resilient material of the valve member but this covering is not essential. The outer peripheral part of the limb 333 is scalloped at 333a to provide cut-outs, whereby fluid can pass between the outer valve member and the wall of the bore 334 of the part 316. The limb 333 is dimensioned, with respect to the bore wall 334, so as to move freely therein in a vertical direction but so as to guide the valve member 312 when it is moving towards and away from its seat 320 and prevent misalignment of the valve member and its seat. The valve member has a convergent sealing surface 335, which is shown as being generally spherical. The downtube 311 is urged upwardly by a spring 336 engaged between the washer 322 and the shoulder 326 and the downtube is provided with a flange 337 at its upper end which engages the outer valve member and thus urges it onto its seat 320. There is substantially line contact between the surface 335 and the seat 320.

The inner valve member 313 is generally tubular and has a closed end 338 which is provided with a spherical edge portion 339 to engage the internal seat 329 on the outer valve member 312. The tubular wall of the valve member 313 is slotted so as to provide three legs, two of which are shown at 340 and 341, each adjacent pair of legs being separated by a slot 342 which extends to the lower end of the valve member. The lower ends of the legs are inturned as indicated at 343 and engage the upper end of a spring 344 whose lower end engages the internal shoulder 327. The spring 344 thus urges the inner valve member 313 onto its seat 329. It will be noted that the upper part of the inner valve member 314 is of smaller diameter than the lower part and that the lower parts 340a and 341a of the legs are guided in the bore 324a of the downtube 311. When the inner valve member is opened fluid can flow between the lower part of the downtube 325, through the spring 344, through the slots 342 into the upper part 323 of the downtube and then between the inner valve member and its seat 329.

The inner valve member 313 can be made as a sheet metal pressing and will normally be made of stainless steel. Preferably the part of the outer valve member which provides the seat 329 is reinforced with a conical metal reinforcement 345 which fits within the vertical limb 332 of the reinforcement 331 and is a force fit therein. In some circumstances, the reinforcement 345 may be omitted.

In use, the closure unit is received in a neck 346 of a container. The upper end of the first part 314 is provided with an externally-threaded portion 347 which engages in an internal thread in the neck. The lower end of the neck has a flange 348 and between this flange and the lower end of the first part 314 is inserted a sealing ring 349. The first part 314 is provided with lugs 350 to engage a device, such as a dispense head, for opening the valves and the first part is also provided with a conical seating 351 for said device or dispense head.

When a suitable device is engaged with the lugs 350, both of the valves are opened. If the closure unit is in a full beer keg, for example, carbon dioxide can be passed between the seat 320 and the outer valve member 312 and between the downtube and the second part 316 of the bush while beer will be forced up the downtube and will pass from the closure unit between the seat 329 and the inner valve member 313. During their movements towards and away from their seats the inner and outer valve members will be guided, the outer valve member by the horizontal limb 333 of the reinforcement and by the washer 322 guiding the downtube and the inner valve member by the lower parts 340a and 341a moving within the bore 324a.

When a container is washed it will be inverted so that the closure unit will be in an inverted position from that shown in FIG. 8. The valves are open and at the end of the washing step it is very desirable that there will be no washing liquid left in the keg to mix with the contents thereof. It will be noted that the formation of the flange 319 of the second part 316 of the bush and the spherical surface 335 of the outer valve member 312 are such that in an inverted position of the closure unit there is no pocket between the bush and the outer valve member to retain liquid so that all washing liquid can flow away. This is an important advantage of the closure unit.

Referring now to FIG. 9, the closure unit shown in that figure differs from the closure unit of FIG. 8 in that the guidance for the outer valve member is provided by a flange at the top of the downtube rather than by the limb 333 of the reinforcement in the valve member.

Parts in FIG. 9 which are identical with parts in FIG. 8 are shown by the same reference numerals with the substitution of the prefix 4 for the prefix 3.

The only parts which are different from those shown in FIG. 8 are the downtube and the outer valve member. The outer valve member 412 has an L-shaped reinforcement 431 as before but the horizontal limb 433 thereof does not extend out of the main mass of material of the valve member. However, the flange 437 at the upper end of the downtube extends radially outward so as to co-operate with the bore 434 of the bush part 416. The flange 437 is shaped or scalloped to allow the passage of fluid between the downtube and the bush part 416. The outer valve 412 is therefore guided during its vertical movement by the flange 437 and also by the downtube being guided in the washer 422.

Referring now to FIG. 10, the closure unit thereshown comprises a bush indicated generally at 560 and having a first part 561 which is in the form of a hot stamping or casting and a second part 562 which is a tubular member of stainless steel as described in detail in relation to FIG. 4. The part 562 has an internal flange 563 part of whose inner periphery provides a valve seat 564.

The closure unit includes a downtube 565 having a lower portion 566 of smaller diameter, an intermediate portion 567, and an upper portion 568 of larger diameter than the portions 566 and 567. Fitting within a bore 569 in the portion 568 is a gas valve 570 which is made of a member of resilient material, e.g. rubber, and which has a convergent sealing surface 571 to engage with the seat 564 on the flange 563 with substantially line contact. The gas valve is an interference fit in the bore 569. The gas valve has an internal seat 571 which is engaged by a convergent seat 572 on a beer valve 573. The beer valve is urged upwardly by means of a spring 574 into engagement with the seat 571, the spring engaging a spider 575 which engages a shoulder 576 between the parts 566 and 567 of the downtube.

The gas valve 570 is urged into engagement with the seat 564 by means of a spring 577 which engages a washer 578 which is supported on parts 579 inset from the lower edge of the part 562. The washer acts as a guide member for the downtube. The spring 577 acts against a washer 580 which engages an external shoulder 581 between the parts 567 and 568 of the downtube. The washer 562 is provided with a plurality of cut-outs such as 582 to enable fluid to flow past the washer.

The operation of the closure unit is as described in relation to FIG. 1 but in FIG. 3 the valve is guided by the washers or guide members 78 and 80.

The invention provides a bush in which the second part is made of stainless steel. This is the part which we have found to be the most subject to damage and corrosion when made of chromed brass or coated aluminium. A bush embodying the invention in which the first part is made of chromed brass or coated aluminium and the second part of stainless steel therefore gives a much better service performance than the previously used, one-piece chromed brass or coated aluminium bushes. Moreover the chromed brass or aluminium first part can be screwed into a stainless steel neck without the risk of the threads of the neck and the bush picking up.

A bush in which the first part is made of stainless steel by casting and the second part of stainless steel tube (or by deep drawing) gives a performance comparable to the one-piece stainless steel bushes heretofore used but at less cost.

The invention also provides a closure unit of the kind specified incorporating a two-part bush and in which the valve member or valve means is guided during movement and no traps are provided for washing liquid.

Claims

1. A closure unit for a container, the closure unit comprising:

a bush for reception in an opening in the container, the bush comprising a first, annular, metal part which has, in one end, a counterbore;

a second part in the form of a stainless steel tubular member held permanently and firmly in the counterbore and extending outwardly therefrom;

a valve seat on the bush;

a downtube supported by the bush for extending into the container;

spring-loaded valve means within the bush and associated with the downtube and said valve seat; and

the valve means comprising a member of resilient material mounted adjacent to one end of the downtube and having a convergent sealing surface for engagement with said valve seat on the bush; and wherein said seat is provided by the inner periphery of an internal flange on the second bush part so as to provide substantially a line seal between the flange and said member of resilient material, the surface of the flange between said inner periphery thereof and the part of the bore of the second bush part which surrounds the downtube being so shaped that when said one end of the downtube is the lower end, the flange and bore being shaped so that retention of liquid within the bush is avoided when said member is disengaged from said seat, the unit also including a guide member movable with the valve member relative to the bush and dimensioned with respect to the bore of the bush so as to move freely therein parallel to the longitudinal axis of the downtube so as to guide the valve member when the latter is moving towards and away from its seat to prevent misalignment of the valve member and the seat, said guide member permitting passage of fluid past the guide member between the downtube and the bush.

2. A closure unit according to claim 1 wherein the valve means is integral with the guide member and comprises a mass of resilient material having an annular reinforcement therein having a flange which forms at least part of the guide member.

3. A closure unit according to claim 1 wherein the valve means comprises concentric inner and outer valve members each of which is separately spring-loaded, the outer valve member being mounted on the downtube adjacent to said one end and being the valve member which cooperates with said seat on the bush, a seat on the outer valve member with which the inner valve member cooperates and wherein a second guide member is supported on the second bush part and through which the downtube passes.

4. A closure unit according to claim 3 wherein the outer valve member comprises a mass of resilient material having an annular reinforcement therein having a flange which forms at least part of the guide member, the outer valve member also having a spigot received sealingly in a bore in one end of the downtube and wherein the reinforcement is of L-shape in cross-section, one limb of the L being received in the spigot of the outer valve member and the other limb of the L forming at least part of said guide member.

5. A closure unit according to claim 4 wherein the outer valve member comprises a second, generally conical reinforcement, which extends into that part of the outer valve member which provides the seat for the inner valve member.

6. A closure unit according to claim 5 wherein said reinforcements are force-fitted into one another.

7. A closure unit according to claim 3 wherein the first-mentioned guide member is formed as a flange integral with said one end of the downtube.

8. A closure unit according to claim 3 wherein the first mentioned guide member is a washer which is separate from and surrounds the downtube.

9. A closure unit according to claim 8 wherein the spring loading for the outer valve member acts on the valve member via the washer and the downtube.

10. A closure unit according to claim 3 wherein the spigot of the outer valve member is tapered so as to be a wedge-fit into said first mentioned bore at the one end of the downtube which is parallel-sided.

11. A closure unit according to claim 3 wherein the inner valve member is tubular and is guided for movement in a second bore in the downtube of smaller diameter than the first-mentioned bore and spaced from said one end, the inner valve member having a closed end which co-operates with the seat on the outer valve member and apertures in its tubular wall at least in that part of the inner valve member which is located within said first bore.

12. A closure unit according to claim 11 wherein said apertures are in the form of slots in the wall of the inner valve member and extend to its other end.

13. A closure unit according to claim 1 wherein the downtube is closed at said one end and the valve member surrounds the downtube and co-operates with said seat on the bush and ports in the downtube adjacent to said one end.

14. A closure unit according to claim 13 wherein the valve member makes line sealing contact with the downtube.

15. A closure member according to claim 13 wherein the valve member comprises a mass of resilient material having an annular reinforcement therein having a flange which forms at least part of the guide member, said reinforcement comprising a washer of Z-shape in radial cross section embedded in said mass of material and providing said guide member, and the outer periphery of the washer cooperating with the bore of the bush to guide the valve member.

16. A closure member according to claim 13 wherein the ports in the downtube are located in an annular recess in the outer surface of the downtube, the recess having smoothly curved edges.