Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~W093/0g055 212 2 7 3 7 PCT~GB92/02~
F~AM ~TION s~ DISPERSION OF BVBBLES
3 This invention relates to a device and a method for
4 generation of a foaming dispersion of bubbles within a
beverage or other liquid packaged within a sealed,
6 non-resealable can or other container, and to'a
7 beverage package incorporating a beverage frothing
8 device. This invention is especially although not
9 exclusively suited to use with canned alcoholic
beverages such as beer, ale, porter, stou~ or lager,
11 but may also be used with non-alcoholic "soft" drinks.
12
13 A device and method for the production of a foamy
14 dispersion ~f ~ubbles or "head" is desirable in canned
b~verages such as beer, ale, porter, stout or lager
16 s~nce these beverages tend to have a diminished head
17 when dispensed from a can, in comparison to be~erages
18 dispensed on draught~ Head generation is assisted by
19 the release of gas dissol~ed în the beverage when it is
depressurised whether by ~eing drawn fro~ a keg as with
21 ~raught beYerage, or by the opening o~ a can or bottleO
22 In draught beverages this head generation is enhanced
23 by the pressurisation of the kegs with car~on dioxide
24 (CO~), nitrogen (N2~ or other suitable inert gases,
combined with the use of foaming devices in the
W093/O~SS PCT/GB92~02~
2122 if 37
1 dispense equipment. Thus draught beverages usually
2 release more bubbles during depressurisation caused by
3 dispensing and have more dense, longer lasting heads
4 than beverages dispensed from cans or bottles.
6 Prior art has addressed ~hese pro~lems by ~a~rious
7 methods.
9 Disclosure has been made of various moulded inserts
which are wholly or partially gas-filled and discharge
11 their gas (or gas and beverage) through an oriice in
12 the insert upon depressurisation of the can. The
13 energy released from the insert upon depressurisation
14 may be ~emperature sensitive causing inconsistent head
production at varying temperatures. At room
16 temperature this may result in excessive foaming,
17 spillage and loss of beverage.
18
19 Alternative approaches to the problem include cans
modified to comprise one chamber for beverage and one
21 for gas that mixes with the beverage when the can is
22 ope~ed. This sophisticated design of can leads to high
23 costs and could prove commercially unviable.
24
Various interm~diate systems have been propo~ed wherein
26 gas chambers are incorporated in can lids or bases. In
27 addition chemical methods of inducing a head have been
28 disclosed but it is unclear to what ext~nt these affect
29 the taste of the beveragè.
31 According to a first aspect of the present invention
32 there is provided a device for generating a foaming
33 dispersion of bubbles in a fluid surrounding the
34 exterior of said device, said fluid comprising a liquid
3S having gas dissolved therein, said device comprising an
.. W093/09055 2 1 2 2 7 3 7 PCT/GB92/02~
1 internal chamber provided with valve means adapted to
2 admit some of said fluid surrounding said exterior of
3 said device through said valve means and into said
4 chamber when the pressure of said surrounding fluid
exceeds the internal pressure of said chamber by a
6 first predetermined amount, thereby to esta~ish a
7 reserve of pressurised fluid within said chamber, said
8 valve means being further adapted to release said
9 reserve of pressurised fluid from said cham~er to pass
outwardly via orifice means into said fluid surrounding
11 said exterior of said device when said internal
12 pressure of said chamber exceeds the pressure of said
13 surrounding fluid ~y a second predetermined amount,
14 said orifice means being dimensioned to cause the
outward passage of fluid therethrough to generate a
16 foaming dispersion of buhbles in said surroundin~
17 fluid.
18
19 The generation of said foaming disperæion of bubbles in
said surroundin~ fluid is preferably brought about in
21 use of said device by so dimensioning said orifice
22 means as to depressur.ise said fluid passing outwardly
23 through sai~ orifice means in a manner which causes the
24 gas dissolved in said liquid to come out of solution in
the fo~m of a plurality of foam-generating seed
26 bubbles.
27
28 Said valve means may comprise functionally separate
29 inlet valve means and ou~let valve means respectively
adapted for the admission and release of fluid to and
31 from ~aid chamber.
32
33 Said inlet valve means may comprise a poppet valve or a
34 flap valve, or more preferably a one-way fluid valve as
described in British Patent Specification GBl066508.
W093/09055 PCT/GB92/02~
2122737 4
1 Said inlet valve means may alternatively comprise a
2 diaphragm having at least one slit therein, said
3 diaphraqm partly bounding said chamber and being
4 substantially closed to the outward passage of fluid
therethrough, said diaphragm being inwardly ~eforma~le
6 by external pressure to open said at leas~ one slit for
7 the passage therethrough of fluid into said chamber.
9 Said outlet valve means may comprise a poppet valve or
io a flap valve, or more preferably a differential val~e
11 which may have the form of an outer passage normally
12 closed by a plug having a chamber-facing inner area
13 acted upon by the internal pressure of said chamber,
14 said plug further having an exterior-facing outer area
acted upon by the pressure of said fluid surroundîng
16 the exterior of said device, said outer area being
17 greater than said inner area by an extent which
18 maintains said outlet passage plugged until said
19 int~rnal pressure of said chamber exceeds the pressure
of said surrounding fluid by said second predetermined
21 amount thereupon to cause or allow said outlet passage
22 to come unplugged to release said reserve of
23 pressurised fluid from said chamber. Said differential
24 valve is preferably such that upon said outlet passage
becoming unplugged, said outlet passage remains
26 unplugged and does not become replugged by subsequent
27 pressure changes.
28
29 According to a second aspect of the present invention
there is provided a m~thod of generating a foaming
31 dispersion of bubbles in a fluid, said fluid comprising
32 a liquid having gas dissolved herein, said method
33 comprising the steps of providing a device according to
34 the first aspect o~ the present invention, submerging
said device in said fluid to surround the exterior of
W093~09055 2 1 2 2 7 ~ 7 PCT/GB92/02~
1 said device with said flui~, pressurising said
: 2 surrounding fluid above the internal pressure of said
3 chamber in said device by at least said first
4 predetermined amount thereby cause some of said
surrounding fluid to be admitted through said.valve
- 6 means of said device and into said chambe~ to establish
7 a reserve of pressurised fluid within said chamber,
8 maintaining said device submerged in said fluid and
; g maintaining the pressurisation of said fluid
surrounding the exterior of said device above the
11 initial pressure ~hereof by an amount that
12 substantially obviates premature discharge of a
13 substantial proportion of said reserve o~ pressurised
14 fluid from ~aid device, said pressurisation of said
surrounding fluid being maintained until the generation
16 of a foaming dispersion of bubbles is required and
17 thereupon depressurising the fluid surrounding the
.,;
:: 18 exterior of said device to a pressure below the
19 internal pressure o~ said chamber by at least said
predetermined second amount to cause the ou~ward
`' 21 passage of .aid reserve of fluid through said orifice
`~ 22 means whereby to generate a foaming dispersion of
t'' 23 bubbles in said surrounding fluid.
:: 24
.~, 25 According to a third aspect of the present invention
i 26 there is provided a method of packaging a beverage in a
. 27 sealed container for the subsequent generation of a
!~' 28 foaming dispersion of bubbles in said beverage upon
~, 29 ~aid container being unsealed, said beverage comprising
;i 30 a liquid having gas dissolved therein, said method
31 comprising the steps of providing a sealable container
q 32 which is initially open, unsealed and empty of liguid;
`', 33 providing a device according to the first aspect of the
34 present invention; emplacing said device in said open
container; prior or subsequent to the emplacement of
W093/0905~ PCT/GB92/020~
2122~37 6
1 said device in said open con~ainer, adding a quantity
2 of said bevera~e to said open con~ainer sufficient to
3 submerge said device when emplaced in said container
4 and to surround the exterior of s~id device with said
beverage; closing and sealing said container ~ith said
6 quantity of beverage and said submerged de~ice therein;
7 and temporarily elevating the temperature of at least
8 the contents of said closed and sealed container by an
9 amount to cause a concomitant increase in the pressure
of said beverage surrounding said device ~ufficient to
11 cause some of said beverage to be admitted through the
12 valve means of said device and into the internal
13 chamber of said device to establish a reserYe of
14 pressurised beverage within said chamber, whereby when
said container is subsequently unsealed and opened,
16 said beverage surrounding the exterior of said device
17 emplaced in said container depressurises towards
18 ambient atmospheric pressure and the pressure of this
lg beverage falls by at least said second predetermined
amount below the internal pressure in said chamber of
21 said device due to the beverage reserved therein
22 thereby to initiate the discharge of said reserved
23 beverage from said internal chamber of said device
24 outwardly through said orifice means of said devi~e and
into said surrounding beverage to generate a foaming
26 dispersion of bubbles in said surrounding beverage to
27 tend to form a head on said beverage.
28
29 At least the internal cha~ber of ~aid de~ice is
preferably purged of oxidising gases prior to
31 emplacement thereof in said container, for example by
32 displacing air initially present in said device with a
33 suitable non-oxidising gas which may be nitrogen,
34 carbon dioxide, or a mixture of these gases. Said
container is preferably likewise purged of oxidising
~W093/09055
21 2 2 7 3 7 PCT/GB92/02Q48
1 gases before the addition thereto of said quantity of
2 beverage.
. 3
4 Said temporary elevation of the temperature of at least
the contents of said sealed container is pre~erably
6 su~sumed within a conventional pasteurisa~ion procedure
7 for newly sealed con~ainers of beverage, conveniently
8 by conjointly heating the sealed container and its
g contents.
io
11 According to a fourth aspect of thc present invention,
12 there îs provided a packaged beverage comprising a
13 closed and sealed container containing a quantity of
14 beverage and a device according to the first aspect of
lS the present invention, said beverage having been
16 packaged in said container by the method according to
17 the third aspect of the present invention.
18
19 Said beverage may be an alcoholic beverage which is
preferably a fermented beverage containing dissolved
21 carbon dioxide as a product of fermentation, but the
22 beverage may additionally or alternatively comprise
23 ersatz carbonation, for example an injected gas
24 comprising carbon dioxide andJor nitrogen.. (Ersatz
carbonation is likely to be employed where the beverage
26 is unfermented as in the cases of non-alcoholic "soft"
27 drinks and cocktails of soft drink mixed with distilled
28 alcohol).
29
Said container is preferably a can which may have a
31 one-piece body of deep-drawn aluminium or steel closed
32 by an initially separate top end disc (preferably also
33 of aluminium or steel) incorporating an integral
34 closure tab defined by coining of the top end disc and
attached to a manually operable pull ring for partial
W093/0905~ PCT/GB92/020~
2122737 8
1 or total separation of the tab from the top end disc to
2 unseal and open the filled can, the can being closed
3 and sealed by seaming of the top end disc to the ri.m of
4 the body.
6 Embodiments of the present invention will now be
7 described, by way of example, with reference to the
8 accompanying drawings, in which:
.9
Fig. l is a longitudinal section through a first
11 embodiment of a device for the generation of a
12 foaming dispersion of bubbles in a fluid;
13
14 ~ig. 2 is a longitudinal section to a reduced
scale through an end cap of the device of Fig.
16 l;
17
18 Fig. 3 is a longitudinal section to a reduced
19 scale through the body of the device of Fig. 1;
20 `
21 Fig. 4 is an end elevation of the device of
22 Fig. 3;
23
24 Fig. S is a longitudinal section to a reduced
scale through an inlet valve and spacer bar
26 assembly in the device Fig. l;
27
28 Fig. 6 is a longitudinal section through the
29 plug of an outlet valve of the device of Fig.
1;
31
32 Fi~ 7 is a longitudinal section through a
33 partially assembled second embodiment of a
34 device for the generation of a foaming
dispersion of bu~bles in a beverage;
~ . .. . . . . . .
WO93J0905~ ~12 2 7 3 7 PCT/GB92/02~
2 Fig~ 8 is a side view of a piston assembly of
3 the device of Fig. 7;
S Fig. 9 is a side view ~o an enlarged scale, of an
6 end of the piston assembly shown in F~g. 8,
7 rotated by 90 around its longitudinal axis;
9 Fig. 10 is a longitudinal section through a
third embodiment of a device for the generation
11 of a foaming dispersion of bubbles in a
12 beverage,
13
14 Fig. 11 is a cross section through a
cylindrical end portion of the device of Fig.
16 10;
17
18 Fig. 12 is a longitudinal section through part
19 of a fourth embodiment of a device for the
generation of a foaming dispersion of bubbles
21 in a beverage;
22
23 Fig. 13 is an end view of the valve of ~ig. 12;
24
Fig. 14 is a longitudinal section through an
26 inlet valve of the device of Fig. 12;
27
28 Fig. lS is a longitudinal se~tion, to an
29 enlarged scale, through a body of the device of
Fig. 12;
31
32 Fig. 16 and 17 are respectively an end view and~
33 .a longitudinal section of a piston forming part
34 of the device of Fig. 12;
W093/090s5 PCT/GB92/020~
2122~37 1~
1 Fig. 1~ is a longitudinal section through an
2 inlet valve intended to form part of a fifth
3 embodiment of a device for the generation of a
4 foaming dispersion of bubbles in a beverage;
6 Fig. 19 is a longitudinal section thr~u~h thè
7 valve of Fig. 18 , shown here assembled into
8 the fifth embodiment while the device is in
9 pressure equilibrium prior to being charged;
i0
11 Fig. 20 is a longitudinal section through the valve
12 of Fig. 18, shown here assembled into the fifth
13 embodiment while the device is charging;
14
Fig. 21 is a longitudinal section through the
16 valve of Fig. 18, shown here assembled into the
17 fifth embodiment while the device is in a
18 charged state;
19
Fig. 22 and 23 respectively show an end view
21 and a half-sectional side view of the valve of
22 Fig. 18;
23
24 Fig. 24 is a sectional elevation of an assembly
of a modified form of the body and piston of
26 Fig.s lS-17; and
27
28 Fig. 25 is a fragmentary section, to an enlarged
29 scale, of part of Fi`g. 24 with the piston displaced
i along the body relative to the positions shown in
31 Fig. 24.
32
33 Refarring now to the drawings, Fig. 1 shows, in
34 longitudinal section , a fully assembled device
according to a first embodiment of the invention. This
._W093~0~55 2 1 2 2 ~ 3 7 PCT/GB92/02~
1 first embodiment is a re-usable device particularly
2 intended to demonstrate the operational principles of
3 the present invention (as distinct from the other
4 embodiments which are single-use.devices intended to be
disposed of along with the singe-use dispos~le
6 beverage cans in which they are incorporatéd). The
7 device as shown in Fig. 1 has an end cap (see also Fig.
2) having an axial inlet aperture S countersunk at 7 to
9 act as the valve seat of a poppet inlet valve assembly
3. The end cap 1 is threaded on an internal surface 10
11 to co-operate with a corresponding external thread on a
12 wall 13 of a reservoir or internal chamber 9 of the
13 device (see also Fig.s 3 and 4). A male part 20 of the
14 inlet valve assembly 3 (see also Fig. 5) is provided as
the movable closure element thereof. One end 22 of the
16 part 20 is conically shaped to be complementary to the
17 valve seat 7 of the valve assembly 3 and normally co-
18 operates with the valve seat 7 to close the inlet
19 aperture 5. The other end of the male part or closure
element 20 has a cavity 25 adapted to receive a spring
i 21 27 and one end 30 of a spacer bar 35. The end 30 of
22 the spacer bar 35 comprises an axial bore 38 which co-
23 operates with the cavity 25 in the closure element 20
24 to enclose the spring 27 which biases.the closure
element 20 firmly against the valve seat 7 of the inlet
26 valve assembly 3, thus closing the valve's inlet
27 aperture 5.
28
29 The other end 40 of the spacer bar 35 comprises a
second axial bore 45 (Fig. 5), of shorter length than
31 the bore 38, and which accommodates one end 50 of a
32 piston extension 55 of a piston assembly 51 (Fig~. l
33 and 6). The other end 65 of the piston extension 55
34 has an annular groove 70 and extends from a piston 75
3S into which is cut a second annular groove 80. The
W093/0~05S PCT/GB92/02~
2 1~2 '7~7 12
1 piston 75 is of a larger diameter than the piston
2 extension 55 and hence the ou ward-facing area A2 of
3 the piston 75 (see Fig. 6) substantially exceeds the
4 inward-facing area A1 of the piston ex~ension 55. (The
functional significance of this area ratio w,lll be
6 explained below).
8 The device of Fig. 1 is assembled as follows:
The piston extension 55 is inserted into the reservoir
11 9 through the aperture 1~ such that the piston 75 fits
12 into a cylindrical end wall portion 17 of the device.
13 O-ring seals 85 and 90 are fitted contiguously with
14 annular grooves 70 and 80 and with the walls of the
aperture 15 and the cylindrical portion 17 respectively
1~ to provide sliding seals therebetween. The piston
17 assembly Sl, the aperture 15 and the cylindrical port
18 17 toge~her define an outlet valve assembly 60 for the
19 device of Fig. 1. The piston extension S5 is then
slotted into the spacer bar axial bore ~5. The spring
21 27 is located in the cylinder formed between axial bore
22 38 in the spacer bar 35 and cavity 25 on the closure
23 element 20 of the poppet valve. The end cap 1 is then
24 screwed on to the wall of the reservoir 13 until a
right fit is achieved by sufficient pressure on an O-
26 ring seal 95 such that the closure element 20 of the
27 inlet valve assembly 3 engages with the valve seat 7
28 and is held against it by the force of the spring 27
29 thus closing the inlet aperture 5. tOperation of the
device of Fig. 1 will be described subsequently).
31
32 Referring now to Figs. 7, 8 and 9, these illustrate a
33 second em~odiment of the invention which differs from
34 the first embodiment (described above with reference to
Figs. 1-6) in respect of certain details o~ its
W093/09055 2 1 2 2 7 3 7 PCT/GR92/02
1 construction. (Parts of the second embodiment which
2 are not significantly different from the first
3 embodiment are given the same reference numerals).
In the second embodiment an end cap 1 is welded
6 ultrasonically-onto the device body 13 an~ lncludes a
7 pliable circumferential ring 2 which presses both ends
8 of the device against the side wall of a beverage can
9 120 thereby holding the device firmly in position
within the can 120.
11
12 A piston assembly 100 of the second embodiment is
13 moulded in a single piece instead of being assembled
14 separately from the separately formed pi~ton 75, spacer
bar 35, spring 27 and closure element 20 of the first
16 embodiment. In the second embodiment, the closure
17 element of the inlet valve assembly 3 is proYided by a
18 hemispherical protrusion lQ2 from a hinged plastic
19 spring 103 which provides the force to hold the
hemispherical protrusion 102 against the valve seat 7
21 of the inlet valve assembly 3 thereby closing the inlet
22 aperture 5. The 0-ring seals 8~ and 90 of the first
23 embodiment are replaced in the second embodiment by
24 mouldad seals 105 and 110 respectively (Fig. 8), these
seals 105 and 110 being formed during the moulding
26 process employed to form the components of the second
27 embodiment to be continuous with the piston assembly
28 100. Assembly of the second embodiment is analogous to
29 that of t~e first embodiment, and op ration of the
second e~bodiment will be described below along with
31 that of the first embodiment.
32
33 Referring now to Figs. 10 and 11, these illustrate a
34 third embodiment which differs from the first and
second embodiments described above in that the inlet
W093/0~55 PCT/GB92/02~
21~737 14
1 valve assembly 3 of the previous embodiments is
2 replaced by a one-way inlet valve 130 as describe in
3 GB1066508 and sometimes known as a "Woodford valve").
4 The one-way inlet valve 130 comprises a pliable plastic
tube 135 intregal with the end cap 1 and open at each
6 of its ends 135a and 135~. One end ~35a of~e tube7 135 has a circular opening 137 therein which presents
8 negligible resistanc~ to the passage of beverage
9 therethrough. The oth~r end 135b of the tube 135
io comprises a flattened portion 138 of reduced diameter
11 (in comparison to that of 135a) having an opening 139
12 which consists of a slit in the end 135b of the tube
13 135, the slit opening 139 being perpendicular to the
14 longitudinal axis of, and in the same plane as the
flattened portion 138.
16
17 In addition, the third embodiment has a modified outlet
18 ~alve piston assembly 140 lacking any physical contact
19 with the inl~t valve 130 and the single orifice 61 in
the wall 13 of the previous embodiments of ~he device
21 is replaced by four longitudinal exhaust grooves 145
22 (Fig. 11) on the inner surface of the cylindrical end
23 wall portion 17.
24
In use of the first or s~cond embodiment of the
26 in~ention (Figs. 1 6; Figs. 7-9), the device is placed
27 across a diameter of an unmodified beverage can prior
28 to filling, sealing and pasteurisation such that the
29 side w211 120 of the can 119 (Fig. 1; Fig . 7 ) is in
contact with the end cap 1 at one end of the device and
31 in contact with the cylindrical portion 17 at the other
32 end. Thus the de~ice is held in position by the force
33 exerted by the pliable circumferential ring (second
34 em~odiment only). The device is disposed at the bottom
of the can 119 throughout the charging and discharging
.. .... . .
~W093/OgO55
~ 7 PCT/GB92/02
1 of the device. The inlet valve assembly 3 requires a
2 pressure differential o~ approxinately one bar to open.
3 Ther~fore, upon pas~eurisation, when he pressure rise
4 in the can 119 (due to the heating of the
pasteurisation process) exceeds 1 bar, the inlet valve
6 assembly 3 opens and beverage flows into t~e reservoir
7 9 until the pressure therein increases to a level
8 greater than the pressure in the can minus 1 bar (to
9 account for the bias of the sprin~ 27 or 103) at which
point the inlet valve assembly 3 closes.
11
12 The outlet valve assembly 60 has a high external/low
13 internal area ratio that causes it to remain closed at
14 high internal/low external pressure differentials. The
value of this differential is dependent on the area
16 ratio such that P~A~ < P~2 where P1 and A, are the
17 internal pressure and area respectively and P, and A2
18 are the external pressure and area respectively.
19 Therefore, increases in the pre~sure differential above
the given value result in outward movement of the
21 piston assembly 51 or 100 until the ori~ice 61 is
22 exposed allowing efflux of beverage therethrough. This
23 efflux continues until the pressure differential is
24 eliminated. Thus a generally constant pressure
differential is maintained wi~hin the reservoir g, the
26 value of which can be selected by varying the
27 internal/external area ratio of the outlet valve
28 assembly 60.
2g
Upon depressurisation o~ the can 119 by opening, the
31 pressure of the beverage in the can 119 decreases very
32 rapidly and this alters the force balance across the
33 outlet valve assembly 60. ~he pressure in the
34 reservoir 9 then causes outward movement of the piston
asse~bly 51 or 100 and exposure of the orifice 61. The
W093J09055 PCT/GB92/02~.
21227~7 16
1 outward movement of the piston assembly 51 or lOo is
2 restrained by the wall 120 o~ the can 119 such that the
3 escape of the beverage/gas mixture is through the
4 orifice 61 or the small annular gap in the outlet valve
assembly 60 between the chamfered rim 18 of the
6 cylindrical portion 17 and the chamfered rYm-~82 of the
7 piston assembly S1 or lOo. This provides the seed
8 bubbles necessary for head generation in the beverage.
io In use of the third embodiment of the invention (~igs.
11 10 and 11), the device is placed in a can 119 as
12 described for the first and second embodiments. As ~he
13 pressure in the can 119 rises due to pasteurisation,
14 beverage flows into the reservoir 9 through the inlet
valve 130 until the pressure in the reservoir 9
16 increases to a level at which the pressure therein
17 equals the pressure in the can minus the small amount
18 of pressure required to open the inlet valve 130, at
19 which point the inflow of beverage stops. Increases in
the pressure in the reservoir 9 above the pressure in
21 the can cause the walls of the flattened portion 138 to
22 be compressed together thus closing the opening 139 and
23 preventing efflux of beverage through the inlet valve
24 130.
26 Increases in the internal/external pressure
27 differential above a given value determined by the
28 internal/external area ratio of the outlet valve
29 assembly 150 as de~cribed above result in outward
movement of the piston assembly 140 until the seal 110
31 passes the opening 144 of the groo~es 145 allowing the
32 excess pressure within the reservoir 9 to escape
33 there~hrough.
34
Upon depressurisation of the can 119 by opening, the
_ W093/O90SS 2 1 2 2 7 3 7 PCT/GB92/02~
1 pressure of the beverage in the can 119 decreases very
2 rapidly, upsetting the force balance across the outlet
3 valve assembly 150. The pressure in the reservoir 9
4 then causes outward movement of the piston assembly 140
and allows escape of beverage/gas mixture from the
6 reservoir 9 through the grooves 145. The ~utward
7 movement of the piston assembly 140 is restrained by
8 the wall 120 of the can 119 such that the escaping
9 beverage/gas mixture is forced through the grooves 145
and this initiates the seed bubbles necessary for head
11 generation in the beverage held in the can 119.
12
13 Referring now to Figs. 12 to 17 inclusive, a fourth
14 embodiment of the foam-generating device of the present
invention has an inlet valve 152 of elastomeric
16 material such as rubber. The inlet valve 152 is fitted
17 onto one end 15S of the reservoir wall 13. A return
18 lip 160 seals the inlet valve 152 onto the wall 13 and
19 this seal is enhanced by the compression applied to the
device by the can wall 120. The compliance of the
21 valve 152 due to the elastomeric material allows up to
22 a 1% change in the can diameter during the~mal cycling
23 without affecting the valve 152. The compressive force
24 on the valve 152 is increased by the charge forces on
the device causing it to expand. Thus the compliance
26 of the valve 152 allows the device to overcome the
27 mechanical changes occurring in charging of the device,
28 and in handling and storage of the filled cans.
29
Three reliefs 165 in the face of the inlet valve 152
31 allow liguid to pass between thè valve 152 and the can
32 wall 120.
33
34 Circumferential ribs 170 on the valve 152 are provided
to increase resistance to collapse of the valve 152
W093/ogO~S PCT/GB92/02 ~
2122737 18 `
1 under pressure when the device is charged.
3 Beverage (or other gas-containing liquid) enters the
4 inlet valve 152 through the open end 175 and passes
through an orifice in the other end of the v~lve 152.
6 The orifice comprises a slit 180 between t~o walls of
7 elastomeric material 183,185. The slit 180 opens
8 against the compressive force between walls 183 and 185
9 in response to increase in pressure outside the device
and allows influx of fluid. When the external/internal
11 pressure differential across the valve 152 is
12 insufficient to open the slit 1~0, the wall ~85 is
13 pressed against wall 183 and the slit 180 is closed.
14 Thus the valve 180 admits fluid when the
external/internal pressure differential across the
16 valve is sufficient to overcome the compressive force
17 of wall 185 against wall 183. Fluid thus admitted
18 cannot escape back through the slit 180 since pressure
increases in the device increase the compressive force
of wall 185 against wall 183, enhancing the seal on the
21 slit 180.
22
23 The device body 190 (Fig. 15) has an annular groove 192
24 in the outer surface for assembly, handling.and
insertion purposes and also for isolating the seal from
26 the flexure of the body 190 when under pressure. The
27 body 190 has three longitudinal exhaust grooves 195 in
28 one end 197 for exhaust of pressurised fluid from the
29 device.
31 The fourth embodiment has an outlet valve assembly
32 comprising a differential piston 200 (Figs. 16 and 17)
33 having pressure-energised inner and outer seals 205,
34 207 which can expand to accommodate the full range of
moulding tolerance. Inner seal 205 has a cup form
,.... . . ~.,~., . . . , ~ . .. ... . .. . . .
~ W093/09055 2 1 2 2 7 ~ 7 PCT/GB92/020~
1 whereby fluid pressure on the inner face of the piston
2 200 will produce a force reaction. Part of the force
3 produced by the internal pressure acts radially to
4 expand the seal 205 and part acts axially to push the
piston 200 out of the bore when the device discharges.
6 As the pressure in the device rises, the ~adial
7 component will increase to form a sealing force which
8 balances the pressure.
g
io On the outer seal 207 (which also has a cup form), a
11 lower sealing force is used than in the inner seal 205
12 to reduce friction and a small chamfer 210 at the rim
13 of the seal 207 is provided to obviate mechanical
14 jamming of the piston 200.
16 A protrusion 21S acts as a stroke-limiting end stop for
17 the piston 200 and also provides a convenient pick up
18 point when handling the component thereby reducing
19 handling damage to the seals 205, 207.
21 Prior to assembly of the fourth embodiment, the body
22 190 and the piston 200 are handled by the slot 192 and
23 the protrusion 215 respectively. The components are
24 purged with nitrogen and the piston ~00 is then
inserted into the body 190, followed by the inlet valve
26 152. This seals both ends and displaces a proportion
27 of the volume of the device, thereby establishing a
28 positive pressure in the nitrogen. This prevents
29 oxygen ingress and increases the pressure of stored gas
ito be released in discharge upon the can being opened,
31 thereby enhancing foam-generating performance.
32
33 In us~, the fourth embodiment is placed across a
34 diameter of the can 119 and is held in place by the
force reaction of the elastomeric inlet valve 152. The
W093/O90SS PCT/GB92/02~
2122737 20
1 de~ice admits fluid through the inlet valve 152 when
2 the pressure outside the device is sufficient to open
3 the slit 180 against the force of the wall 185 and the
4 pressure inside the device.
6 Beverage (or other gas-containing liquid) ~s thus
7 admitted into the device and the pressure inside the
8 device increases to a level determined by the
9 internal/external area ratio of the differential piston
200 of the outlet valve as described for previous
11 embodiments.
12
13 Upon opening of the can, the fourth embodiment of
14 device initiates seed bubbles in accordance with a
lS mechanism similar to that described for the third
16 embodiment.
17
18 Referring now to Figs. 18 to 23 inclusive, the fifth
19 embodiment of device shown is similar to the fourth
embodiment, but with an alternative inlet valve 220.
21 ~he inlet valve 220 is constructed from an elastomeric
22 material such as rubber and comprises a diaphragm 225
23 stretched across one end of the device body 190, the
24 valve 220 having a cross-shaped slit 230 in the centre
of the diaphragm 225, a return lip 160, and three
26 inlets 165 as previously described. The device is
27 inserted across a diameter of the can and the physical
28 compression of the elastomeric material at the valve
29 220 creates a force which retains the device in
position.
31
32 At pressure equilibrium ths diaphragm 225 is distended
33 against the can wall 120 thereby closing and sealing
34 the slit 230 until the pressure outside the device
rises due to the pasteurisation process. When the
Wo93/osn55 21~ 2 7 3 7 PCT/GB92/02~
21
1 external/internal pressure differential increases
2 beyond a predetermined level, the diaphragm 225
3 deflects and fluid is admitted through the slit 230,
4 thereby compressîng the gas in the reservoir 9.
6 When peak pasteurisation pressure in the c~n is
7 reached, inflow of beverage to the device stops. With
8 the establishment of this pressure balance, the elastic
9 energy in the diaphragm 225 causes it to distend
against the wall 120 of the can and the slit 230 is
11 sealed. Thus, the slit 230 remains sealed at high
12 internal~low external pressure differentials across the
13 valve 220 and increasing pressure differentials force
14 the diaphragm harder against the wall 120 of the can,
thereby enhancing the seal of the slit 230.
16
17 The process of discharge of the fifth embodiment of
18 device upon the can being opened is similar to that
19 described for the fourth embodiment.
21 Since all the embodiments described above employ an
22 outlet valve (or outlet valve assembly) which maintains
23 the pressure stored in the device reservoir at a
24 generally constant level, the operation of the device
is generally independent of temperature; thus the
26 device mitigates the problems of temperature-dependent
27 energy r~lease shown by prior art pressure accumulating
28 devices.
29
Referring!now to Figs. 24 and 25, thes~ respectively
31 show a modified version of the outlet valve assembly
32 shown in Figs. 15-17, in its 'closed' configuration,
33 and an enlarged fragmentary view of the valve assembly
34 in its 'open' configuration. In Figs. 24 and 25 those
parts of the modified outlet valve assembly which
.;.. . ~ -
W093/09055 PCT/GB92/02~
212~737 22
1 correspond to parts of the outlet valve assembly of
2 Figs. 15-17 are given the same reference numerals.
4 The essential difference in the modified assembly of
Figs. 24 and 25 with respect to the assemb~y.of Figs.
6 15-17 consists of the provision of an inturned lip 801
7 at the discharge end 197 of the devicé to prevent total
8 e~ection of the differential piston 200 from the
9 discharge end 197 of the device body 190 upon opening
io of the beverage can (not shown in Figs. 24 and 25) in
ll which the device is emplaced. To enhance the piston-
12 retentive properties of the lip modification 801, the
13 chamfer 210 in the unmodified piston 200 (Fig. 17) may
14 be omitted as particularly illustrated in Fig. 25.
While certain modifications and variations have been
16 described above, the inve~tion is not restricted
17 thereto, and other modifications and variations can be
18 adopted without departing from the scope of the
19 invention as defined in the appended claims.
