Note: Descriptions are shown in the official language in which they were submitted.
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PAKA:010
METHOD AND APPARATUS TO PROMOTE
GAS EXCHANGE FROM A SEALED RECEPTACLE
The present invention relates to a method and
apparatus for modifying the gaseous atmosphere in a
receptacle containing a deteriorative material or a
material of which controlled fluid exposure is desired.
More specifically, the present invention is directed to a
method and apparatus for extracting, modifying, or
exchanging the gases within a closed, sealed receptacle
while inhibiting the structural collapse of the
receptacle. The invention is especially concerned with
treating foods directly in transparent, flexible packages
in which the foods are wrapped or otherwise sealed for
display ana marketing.
The shelf life, both refrigerated and at room
temperature, of many food products can be greatly extended
if the food product is placed in a substantially oxygen
free environment. one way of achieving this oxygen free
environment is to evacuate a package containing the food
product to a very high level of vacuum. However, when
flexible packaging is involved, the use of a high vacuum
can distort, compact and crush the enclosed product as the
vacuum is applied. For example, bakery products can
readily be squeezed or compressed so that they lose their
consumer appeal. Shredded cheeses can be compacted to
such an extent that they require reshredding. Fruit
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products can be bruised with a resultant loss of both
appearance and flavor.
Meat, fruit and vegetable products subjected to
vacuum packing can also undergo liquid purge which
diminishes their appearance and flavor. Additionally,
meat products subjected to vacuum packaging often adopt a
purplish color since no oxymyoglobin is formed due to the
lack of oxygen. This color is sometimes unacceptable for
domestic retail marketing, and hence the product must be
removed from the vacuum package prior to display and
repackaged in a way so as to allow the characteristic red
"bloom" to appear in the meat product.
To overcome the aforedescribed disadvantages, gas
packaging has been used as an alternative to vacuum
packing. Gas packaging entails a modification of the
atmosphere within the receptacle housing the product so as
to introduce a growth inhibiting agent, i.e. an inert gas,
or an oxygenating agent, into the receptacle. As
disclosed in applicant's copending application Serial No.
214,195, it may also be desirable to modify the gas within
the receptacle to include a desired concentration of an
oxidizing agent, e.g. ozone, so as to reduce or eliminate
bacterial concentration within the receptacle.
In instances where gas flush packaging is utilized,
it is often desirable to remove a substantial portion of
the original, resident atmosphere within the receptacle
before introducing a second gas or gas combination. This
is desirable so as to decrease the amount of the secondary
gas necessary to beneficially affect the containerized
product. If evacuation or partial evacuation of the
receptacle is not first undertaken, the secondary gas will
be diluted and will therefore be required in greater
quantities in order to achieve its intended purpose. At
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least partial gas extraction is therefore desirable in
order to remove the resident gas preliminary to the
introduction of a second ~as. This gas extraction,
however, if conducted in a conventional manner, will also
bring about the disadvantages noted above in connection
with vacuum packaging in that the package will undergo, if
only temporarily, distortion or collapse.
A variety of devices have been developed to address
the problems associated with the collapse of a flexible
container or receptacle during gas exchange or extraction.
One such device is seen in U.S. Patent No. 1,591,932 (the
'932 patent) as issued to Young. The '932 patent
discloses a method and apparatus for replacing air in a
filled container with an inert gas. In the '932 patent,
the receptacle is placed within a vacuum chamber and the
pressures inside and outside the receptacle regulated so
as to avoid the deformation or collapse of the walls of
the receptacle. Gas exchange in the '932 patent is
accomplished by withdrawing the resident atmosphere from
the receptacle via a vent hole while maintaining an equal
pressure within the vacuum chamber. When the addition of
the inert gas is desired, pressure equalization is
accomplished via a yoke which is activated by the pressure
of the gas injected into the receptacle.
Disadvantages of the aforedescribed apparatus include
the need to form an aperture in the container in order to
achieve evacuation and repressurization in addition to the
need to utilize a secondary sealing step to maintain the
second atmosphere within the receptacle.
The present invention addresses the aforedescribed
and other disadvantages for modifying the gaseous
atmosphere in a closed receptacle. More specifically, the
present invention addresses the disadvantages associated
4 2080912
with the preservation of perishable products by providing
a method and apparatus to exchange the gases within said
receptacle without inducing distortion or collapse.
Moreover, the present invention enables gas exchange to be
undertaken in an economical and automated fashion which
- may be accomplished at various levels along the wholesale
or retail chain of distribution.
The present invention generally comprises a vacuum
chamber provided with a means to move and align a sealed
receptacle from a position exterior to the chamber to a
desired position within the chamber whereupon the chamber
is automatically closed and sealed. Once the chamber is
closed and sealed, a gas exchange probe is automatically
lS inserted into the receptacle through a resealable valve so
as to establish flow communication between the interior of
the receptacle and the vacuum chamber. The valve is
preferably a septum-type valve capable of being penetrated
by the probe in a self-sealing relation. A vacuum is then
drawn in said chamber thereby evacuating the interior of
the receptacle through the gas exchange probe. In such a
fashion, distortion or collapse of a flexible receptacle
is avoided, since the gas exchange operation does not
cause a pressure differential between the interior and
exterior of the receptacle.
Gas introduction and exchange is accomplished in a
similar manner insofar as the balanced introduction of gas
pressure about both the interior and exterior of the
receptacle. During the gas reintroduction phase, however,
gas introduced into the package is separately valved from
the gas used to repressurize the vacuum chamber. In such
a fashion, the exchange gas flows only into the interior
of the package, while pressure inside the chamber exterior
to the package may be maintained by the introduction of a
third, less expensive gas, or even outside air.
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The present invention has particular application to
the packaging of food products in polystyrene foam or
other plastic trays which are hermetically sealed with
transparent plastic wrap. While many other products may
be sealed and marketed in this manner, food products
require special care in order to preserve both their
quality and appearance.
The present invention has a number of advantages over
the art. One such advantage is the ability to maintain a
minimum pressure differential between the inside and the
outside of the receptacle during gas exchange operations.
In such a fashion, distortion of the package and liquid
purge of the product is minimized.
A second advantage of the invention is the ability to
accommodate automated gas exchange operations without the
need to reseal the receptacle in a second, separate opera-
tion.
Another advantage is the ability to produce a package
having a controlled positive pressure so as to reduce or
avoid liquid purging as well as other physical aesthetic
benefits.
Other objects and advantages of the invention will
become apparent from the following detailed description
made in conjunction with the accompanying drawings.
Fig. 1 illustrates a partial cutaway, perspective
view of one preferred embodiment of the invention.
Fig. 2 illustrates a side, detail view of the door
mechanism illustrated in Fig. 1.
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Fig. 3 illustrates a perspective view of a gas
exchange apparatus of the present invention as it may
relate to a preferred package design.
Fig. 4 illustrates a top, cut away view of the
embodiment illustrated in Fig. 1.
Fig. 5 illustrates a side, detail view of the gas
exchange apparatus and accompanying activation means.
Fig. 6 illustrates a schematic view of the gas
exchange apparatus.
Fig. 7 illustrates a schematic view of the electrical
layout of one embodiment of the invention.
Fig. 1 illustrates a vacuum chamber 6 supported on a
frame 2. Chamber 6 is provided with doors 21 and 2lA
situated on opposite sides thereof so as to allow the
progressive movement of receptacles or containers 100
which are preferably moved along conveyor track 4 into and
through chamber 6 for purposes of gas exchange and
modification as will be further discussed herein.
As illustrated in Fig. 1, conveyor track 4 is
preferably situated such that it abuts chamber 6 on
opposite sides thereof at a height generally compatible
with the operation of internal conveyor assembly 83 as
will be further described. Conveyor track 4 may be
comprised of a series of rollers 17 linearly assembled
along a frame 18 in a generally conventional fashion.
Alternatively, track 4 may be comprised of a conventional
endless track conveyor assembly. Preferably, however,
track 4 should be provided with a means to automatically
regulate and govern the linear movement of articles placed
_7_ 2 08091 2
thereon. In such a fashion, it is preferred that track 4
be automatically rather than manually operated.
In the embodiment illustrated in Fig. 1, doors 21 and
2lA are pivotally attached to chamber 6 about hinges 7
such that they open in an upward fashion as illustrated in
Fig. 2. (See arrow B). When in a closed position such as
that illustrated in Fig. 1, doors 21 and 21A maintain an
airtight seal with the body of chamber 6. To accomplish
this airtight seal, doors 21 are preferably provided with
a sealing gasket or the like (not shown) to allow a vacuum
to be drawn in chamber 6. Alternately, an appropriate
sealing material may be provided on the contact face of
chamber 6 receptive to doors 21 when they are situated in
a closed position. Doors 21 and 21a are also preferably
provided with a locking mechanism of general conventional
design to allow for the pressurization of chamber 6.
In the illustrated embodiment, the operation of doors
21 and 21A is independently controlled by motors 24 and
24A, respectively. Motors 24 and 24A are secured to the
top exterior 5 of chamber 6 and are operatively coupled to
cam 26 which is rotatably coupled to control arm 22.
Control arm 22 is in turn rotatably coupled to door
bracket 20, which itself is partially connected to the
exterior of chamber 6 as a bracket assembly 9 at one end
and to the door at its bottommost extent. In such a
fashion, operation of motors 24 and 24A in a "forward"
direction results in the upward pivot of doors 21 to an
"open" position. Reversal of motors 24 and 24A results in
the movement of doors 21 and 21A to a "closed" and locked
position. In a preferred embodiment, motors 24 and 24A
are electrically coupled to a central control system 39
such as a Toshiba Ex-20 control device in a manner
illustrated in Fig. 7. In such a fashion, the operation
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-8- 2080912
of doors 21 and 21A may be automatically controlled as
will be further discussed herein.
While one preferred embodiment of the invention is
illustrated in Fig. 1, other structural configurations of
the present invention are also envisioned in accordance
with the spirit of the present invention. For example,
the door pivoting arrangement illustrated in Figs. 1-2 may
be replaced with a sliding door mechanism or the like.
Similarly, the overall configuration of chamber 6 may also
be modified so as to allow for the introduction of a
plurality of receptacles 100 of varying sizes.
Alternatively, the operation of the doors may be
controlled by a single motor in either an independent or
dependent fashion. In all embodiments, however, it is
desirable that chamber 6 be fashioned of or provided with
a transparent panel or "window" so as to allow for visual
inspection of the gas exchange operation.
The gas exchange system of the present invention may
be seen by reference to Figs. 1, 4, 5, and 7. Fig. 4
illustrates a top, cutaway view of the interior of chamber
6 revealing a receptacle 100 positioned on an endless
track conveyer assembly 83. As illustrated, assembly 83
is comprised of two or more drive rollers 84 and a
supporting belt 82. In a preferred embodiment, belt 82
may be made of neoprene or other elastic material, while
rollers 84 may be driven by a Dayton Electric 50 RPM, 115
V motor or other comparable equipment. Other conveyance
systems are also envisioned and will become obvious to one
skilled in the art. It is desirable that any conveyance
mechanism be either sealably containable within chamber 6
or otherwise allow for the creation of a vacuum in the
chamber.
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-9- 20809 1 2
The gas exchange apparatus of the present invention is
designed to be used in association with a presealed receptacle
100 such as that described in applicant's Canadian copending
application File No. 2,080,912 filed April 19, 1991. As
illustrated in Fig. 3, receptacle 100 generally includes a
sidewall 19 and a top 21, the combination forming a sealable,
pressurizable unit. In a preferred embodiment, the sidewalls 19
of receptacle 100 are provided with a resealable valve 102 which
may be integrated into the sidewall itself or may be affixed to
the surface of the package exterior. In the receptacle 100
illustrated in Fig. 3, valve 102 is disposed in a corner of
sidewall 19 so as to be compatible with the gas exchange
mechanism in the illustrated embodiment of the present invention.
To provide for gas exchange, receptacle 100 is preferably
aligned on assembly 83 so as to rest flush against a retaining
rail 29 and stop 127. Lateral positioning of receptacle 100
along assembly 83 may be accomplished via a flexible alignment
arm 80. As illustrated in Fig. 4, arm 80 is situated in chamber
6 so as to be capable of flexure in a plane generally coplanar
with that described by assembly 83 and in a lateral direction
such as to urge receptacle 80 against retaining rail 29. When
compelled by the forward movement of assembly 83 (whose direction
of movement is indicted by arrow A) and the lateral force exerted
by alignment arm 80, receptacle 100 is moved into an abutting
relation with stop 125 and rail 29 as previously described. In
this fashion, package valve 102 is positioned immediately
proximate gas exchange assembly 120.
In a preferred embodiment, package sensor or control stop
127 is electrically coupled to the central control system 39 as
previously described in a manner illustrated in Fig. 7.
p~
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Actuation of control stop 127 results in the transmission of an
electrical signal to control system 39. In a preferred
embodiment, stop 127 is pressure activated and thus transmits an
electrical signal to control system 39 when contacted by package
100. Preferably, the activation mechanism 51 for conveyor
assembly 83 is likewise coupled to control system 39. In such a
fashion, when receptacle 100 is moved into contact with stop 127,
conveyor assembly 83 is disengaged. Solenoids 121, 94, 91 and 92
are likewise coupled to control system 39 in a manner illustrated
in Fig. 7.
The aforedescribed operations have been described as
occurring essentially simultaneously. It is envisioned, however,
that it may be desirable to provide a programmed or timed delay
in the operational sequence of the apparatus.
A preferred embodiment of the gas exchange assembly 120 may
be seen by reference to Figs. 4 - 5. Gas exchange assembly 120
generally comprises an injector probe 122 mounted on a plunger
123 which is slidably disposed in a housing 129. Probe 122 may
be comprised of a fine hollow tube or needle such as a number 20
hypodermic needle manufactured by Becton, Dickinson and Company.
Plunger 123 is itself fixedly mounted on the frontal extremity of
solenoid 121 as illustrated. Such a solenoid is conventional in
design, such as that manufactured by Dayton Electric. Upon
activation, solenoid 121 moves injector probe 122 through
resealable valve 102 and into communication with the gases sealed
within receptacle 100.
Gas exchange assembly 120 is coupled to a three-way
valve union 83 via a gas conduit 88. Referring to Figs. 1,
3, 4, union 83 allows for the routing of gas flow
from and into the interior of receptacle 100. Union 83
is coupled to an evacuation valve 95 via a secondary gas
~p
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conduit 9o. Union 83 is also coupled to a second solenoid
92, such as ASC0 Model ~26014, via conduit 84. Solenoid
92 is in turn coupled to a gas supply source 40 via
conduit 41.
The operation of evacuation valve assembly 95 is con-
trolled by a solenoid 94 such as a Dayton Electric
Speedair 2A242. Valve assembly 95 includes a gas inlet 96
which communicates with the interior of chamber 6.
Solenoid 94 is electrically coupled to control system 39
and thus may be automatically controlled. When solenoid
94 is activated to an "open" position, gas communication
is established between the interior of receptacle 100 and
the interior of vacuum chamber 6. When deactivated,
solenoid 94 moves to a "closed" position, thereby closing
valve 95 and thus preventing the escape or introduction of
gas between receptacle 100 and chamber 6. Evacuation of
package 100 thus takes place when solenoid 94 is urged to
an "open" position. Repressurization of package 100 takes
place when solenoid 94 is situated in a "closed" position.
Chamber 6 is provided with a valving means 101 which
enables the removal or addition of gases thereto.
Referring to Figs. 1 and 4, valving means 100 comprises a
conduit 99 which is disposed in the sidewall of chamber 6
so as to establish fluid communication therethrough.
Conduit 99 is open at its remote end and is coupled to a T
97 at its proximal end. T 97 is also coupled to a
solenoid valve 91 and a conduit 98. Solenoid 91, when in
an "open" position, enables pressurization between the
interior and exterior of chamber 6 through nozzle 103.
When in a "closed" position, solenoid 91 enables a vacuum
to be drawn in chamber 6 through conduit 98 which is
coupled to vacuum pump 43.
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It may sometimes be desirable to remove the atmosphere
within container 100 independently of atmosphere removal of
chamber 6. This may be necessary when receptacle 100 contains a
strong oxidizer, e.g. chlorine or bromine. In such a case, gas
removal of receptacle 100 may be conducted via a separate vacuum
pump (not shown) coupled, for example, to conduit 84 as indicated
by dashed lines 84A. In such a setup, solenoid 94 would be
maintained in a "closed" position during the evacuation
procedure. Alternatively, structures 94, 95, 96 and coupling 90
would be altogether eliminated.
In cases when receptacle 100 contains a high oxygen content,
e.g. > 35~, separate gas removal may be carried out via a venturi
pump. In such a fashion, the opportunity for explosion or fire
is minimized. Evacuation of chamber 6 may be carried out via a
faster, conventional vacuum pump as earlier described in
reference to the general embodiment.
The preferred operation of the present invention may be
described in sequential fashion as follows. At the completion of
the previous gas exchange operation, door 21A is moved to an
"open" position via the activation of motor 24A. Conveyor
assembly 83 is likewise activated, thus moving the previous
receptacle out of chamber 6. Conveyor track 4, which has
likewise been activated, moves the receptacle downstream for
packaging or further processing. During this operation, a new
receptacle 100 is simultaneously moved into chamber 6 through
door 21 which has also been moved to an ~open~ position. Once
package 100 is moved into an abutting relationship with stop 127,
door 21A is then moved to a sealed and ~closed~ position. In a
preferred embodiment, movement of receptacle 100 may be
automatically controlled as earlier described. Alternatively,
..~ .
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the operation of the various separate mechanisms may be conducted
via a timed program. Once receptacle has been moved partway into
chamber 6, the forward movement of receptacle 100 is completed
via the movement of conveyor assembly 83. The operation of
assembly 83 moves receptacle 100 into contact with alignment arm
80 which exerts a lateral force on said receptacle. This lateral
force, in combination with the forward movement of assembly 83,
moves receptacle 100 into contact with retaining rail 19 and stop
127. When contacted by receptacle 100, stop 127 carries an
electrical impulse to controller 39 which activates motor 24
which in turn moves door 21 into a closed, sealing position. By
a subsequent signal from controller 39, conveyor assembly 83 is
then deactivated.
To avoid any problems of contamination which might occur in
the event receptacle 100 is damaged or punctured at any time
during the gas exchange operation, it is desirable to create a
positive pressure inside receptacle 100 prior to the initiation
of the gas exchange operation. Accordingly, it is preferred that
a partial vacuum be created in chamber 6 prior to gas exchange.
Subsequently, therefore, vacuum pump 43 is next engaged and
solenoid 91 moved to a "closed" position so as to enable the
exhaustion of gas through gas lines 99 and 98. The creation of a
vacuum or partial vacuum is created immediately prior to the
insertion of probe 122 in container 100. Once a vacuum or
partial vacuum has been achieved, solenoid 121 is activated,
thereby driving probe 122 into receptacle 100 through valve 102
as earlier described. Solenoid 94 is also activated to an ~open"
position.
The penetration of container 100 by needle 122
enables gas flow through conduit 88 through gas outlet
96 as container 100 is exhausted. Simultaneously, gases
within chamber 6 are continuing to be evacuated through
. ,~ .
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-14-
inlet 99 via pump 43. In such a fashion, evacuation of
chamber 6 results in a simultaneous evacuation of the
interior of receptacle lOo, thus avoiding any resultant
modification in the shape of said receptacle. When a
vacuum has been drawn in the interior chamber 6, pump 43
is deactivated, and solenoid 94 is moved to a "closed"
position. Actuation of pump 43 and solenoid 94 may be
accomplished by vacuum sensors which are activated when a
satisfactory vacuum is achieved in chamber 6, or may
alternatively be accomplished via the operation of a timer
(both not shown).
The present invention has particular application to
processes where gas withdrawal and exchange is
contemplated. In the event the introduction of a second
gas mixture into the receptacle 100 is desired, solenoid
94 is activated to a "closed" position, while solenoid 92
is moved to an "open" position. Gas flow from gas supply
40 may now commence into container 100. Very shortly
thereafter, solenoid 91 is activated to an "open" position
so as to allow gas flow communication between the interior
and exterior of chamber 6. In such a fashion, pressure
equalization is thereby maintained between the interior
and the exterior of the package 100, thereby eliminating
or substantially reducing any collapse. In an alternate
embodiment, repressurization of container 100 may be
accomplished via a secondary solenoid valve 107 and a pump
192 (see Fig. 6). In such a fashion, more precise
pressure regulation may be achieved.
Upon completion of the gas exchange operation, probe
122 is automatically withdrawn from receptacle 100
whereupon assembly 83 is reactivated to move receptacle
100 forward. Concurrently, motor 24A is activated, thus
moving door 21A to an "open" position. Receptacle 100 is
then moved forward until it establishes contact with track
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4, which automatically moves receptacle 100 downstream for
further processing or packaging.
