US3832828A

US3832828A - Evacuation and venting system for vacuum packages and vacuum chamber therefor

Info

Publication number: US3832828A
Application number: US00327685A
Authority: US
Inventors: L Martin
Original assignee: Standard Packaging Corp
Current assignee: Standard Packaging Corp
Priority date: 1973-01-29
Filing date: 1973-01-29
Publication date: 1974-09-03
Anticipated expiration: 1991-09-03
Also published as: JPS5513969B2; CH572840A5; DE2357173A1; GB1433188A; JPS49104789A

Abstract

An evacuation and venting system and method for providing vacuum packages utilizing a vacuum chamber having two vacuum channels or ports, located at the side of the vacuum chamber, and a vacuum channel or port, located at the top of the chamber. The side vacuum channels are arranged to provide efficient evacuation of a package disposed in the vacuum chamber to allow the space between the bottom of the package and the top of the package to be evacuated without adversely affecting the sealing bars of the vacuum chamber. The vacuum chamber may be used to vacuum pack liquid-packed foodstuffs by having the top vacuum channel vent or otherwise remove the liquid from the side vacuum channels subsequent to evacuation.

Description

United States Patent [191 Martin Sept. 3, 1974 EVACUATION AND VENTING SYSTEM FOR VACUUM PACKAGES AND VACUUM CHAMBER THEREFOR [75] inventor: Louis F. Martin, Woodridge, NJ.

[73] Assignee: Standard Packaging Corporation,

New York, N.Y.

[22] Filed: Jan. 29, 1973 [21] Appl. No.: 327,685

[52] US. Cl 53/112 A [51] Int. Cl B65b 31/02 [58] Field of Search... 53/22 A, 22 R, 112 A, 112 R [56] 8 References Cited UNITED STATES PATENTS 3,343,332 9/1967 Mahaffy et al 53/112 A X 3,509,686 5/1970 I Ber'gstrom 53/112 A 3,706,174 12/1972 Young et a1. 53/112A X 3,750,362 8/1973 Kishpaugh 53/22 A Primary Examiner-Travis S. McGehee Attorney, Agent, or Firm-Amster & Rothstein 5 7 ABSTRACT An evacuation and venting system and method for providing vacuum packages utilizing a vacuum chamber having two vacuum channels or ports, located at the side of the vacuum chamber, and a vacuum channel or port, located at the top of the chamber. The side vacuum channels are arranged to provide efficient evacuation of a package disposed in the vacuum chamber to allow the space between the bottom of the package and the top of the package to be evacuated without adversely affecting the sealing bars of the vacuum chamber. The vacuum chamber may be used to vacuum pack liquid-packed foodstuffs by having the top vacuum channel vent or otherwise remove the liquid from the side vacuum channels subsequent to evacuation.

13 Claims, 6 Drawing Figures EVACUATION AND VENTING SYSTEM FOR VACUUM PACKAGES AND VACUUM CHAMBER THEREFOR This invention relates generally to vacuum systems and methods and, more particularly, to an evacuation and venting system and method for providing vacuum packages and to a vacuum chamber utilized therewith.

A multitude of prior art machines and methods have been devised for vacuum packaging products including those which form packages from heat-sealable flexible packaging material. Such packages have found wide acceptance in the food packaging field because of the extended shelf life afforded to the packaged product by the use of such materials. For instance, cheeses, nuts, dried fruits, or the like, have particularly benefited from such packaging in that these food products must be protected from oxidizing influences, such as atmospheric oxygen, and must be vacuum sealed for preservation purposes.

Exemplary of prior art apparatus for forming vacuum sealed packages out of heat-sealable flexible packages material is that apparatus which includes various operation stages or stations. For instance, at a first operation station, a plastic material is introduced and is formed to provide the package bottom. The package bottom is transported to a second operation station wherein foodstuff, or other material to be vacuum packed, is loaded into the partially formed package. The loaded package is then transported to a thrid' operation station where plastic material is introduced to provide the top of the package and to the fourth operation station where the top of the package is partially sealed to the package bottom. At the fifth or next operation station, two operations occur. First, the package is introduced into a vacuum chamber whereby the air in the space between the top of the package and the bottom of the package is evacuated through the unsealed portion of the package by a top vacuum chammel or port in the vacuum chamber. Second, sealing bars in the vacuum chamber then seal the unsealed portion of the package in order to maintain the package in its vacuum or evacuated state. The vacuum sealed package may then be cut, etc. or otherwise packaged for shipment.

Although the above-described prior art apparatus works generally satisfactorily, there exists the everpresent need to provide a vacuum packaging system which operates in an improved manner. Specifically, the vacuum chambers utilized in prior art vacuum packaging systems are subject to turbulence as the package (and the rest of the chamber) is evacuated; do not act as efficiently as is desired; and, may provide vacuum sealed packages which are either not fully evacuated or are not fully sealed.

One particular difficulty has been the vacuum packaging of foodstuffs which are packaged in a liquid, i.e., various fruit desserts. Part of the difficulty results from the fact that as the package is evacuated via the top vacuum channel in the vacuum chamber, the liquid is drawn across the vacuum chamber seal bars (which are utilized to finally seal the package). This cools the seal bars which, in turn, results in the fact that the seal bars often do not provide an adequate seal for the package.

Of course, this problem also arises where the package does not include a liquid, i.e., the flow of air across the seal bars alone may cool the seal bars to an undesirable temperature. However, this problem is aggravated when the package is liquid-packed."

Another difficult encountered in liquid-packed" foodstuffs is the fact that the liquid is drawn up in the top vacuum channel and, after the package has been evacuated, this liquid remains in the channel and/or flows back into the vacuum chamber. As a result thereof, undesirable excess liquid is deposited on the top of the package resulting in a package which is sticky to the touch. Additionally, the vacuum chamber often fills up with excess liquid to such an extent as to render the vacuum chamber incapable of properly functioning.

Accordingly, it is a broad object of the present invention to provide a new and improved vacuum chamber for use in a packaging machine.

A more specific object of this invention is to provide a new and improved vacuum chamber which is subject to less turbulence, operates more efficiently (i.e., faster) and enables the seal bars to be maintained at their desired temperature.

Yet another object of this invention is to provide a new and improved vacuum chamber which is free from the difficulties experienced with vacuum chambers of the prior art.

Yet another object of this invention is to provide a vacuum-packaging system and method for vacuum packaging liquid-packed products.

In accordance with an illustrative embodiment demonstrating objects and features according to apparatus aspects of the present invention, there is provided a vacuum chamber adapted to evacuate and seal a package and including a vacuum channel disposed at the top of the chamber and at least one vacuum channel disposed at the side of the chamber. Spring-biased seal bars are provided for completing the seal between the top and the bottom of the package after the package has been evacuated. The side vacuum channel is located such that the seal bars are not adversely cooled when the package is evacuated. The vacuum chamber is adaptedto be utilized in conjunction with an evacuation and venting system for vacuum packaging liquidpackaged products, which system includes means for forming a bottom package member, means for loading liquid-packed material into the bottom package member and means for partially sealing a top package member to the bottom package member. The system also includes means for evacuating the space between the top and bottom package members, through the unsealed portion of the package, and means for sealing the unsealed portion of the package after evacuation to maintain the package in its evacuated or vacuum state. Various control valves are provided for venting the system thereby removing liquid, or other material, drawn up into the vacuum channels during evacuation.

In accordance with an illustrative embodiment demonstrating objects and features according to method aspects of the present invention, a method for vacuum packaging a liquid-packed product includes the steps of forming a bottom package member, depositing liquidpacked material into the bottom package member and partially sealing the bottom package member to a top package member. The partially-sealed package is then evacuated, through the unsealed portion between the top and bottom package members, and the unsealed portion of the package is sealed to maintain the package in its vacuum or evacuated state. Subsequent to evacuation and final seal of the package, the system is vented in order to remove liquid or other material drawn into the vacuum channels during evacuation from the vacuum channels.

The above brief description, as well as further objects, features and advantages of the present invention will be more fully understood by reference to the following detailed description of a presently preferred but nonetheless illustrative embodiment in accordance with the present invention, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic, front elevation view of the apparatus utilized in performing the method of the present invention;

FIG. 2 is a schematic, diagrammatic view showing the system in its evacuation mode; 7

FIG. 3 is a schematic, diagrammatic view showing the system in its venting mode;

FIG. 4 is a side elevation view, partly in section, showing a die and the vacuum chamber according to the present invention;

FIG. 5 is an enlarged view of part of the die and vacuum chamber of FIG.3, showing the system in its evacuation mode; and

FIG. 6 is a top plan view, taken substantially along the line 66 of FIG. 4 and looking in the direction of the arrows.

Referring to the drawings, and particularly to FIG. 1 thereof, a vacuum packaging system, according to the present invention, is generally designated 10. Vacuum packaging system 10 is adapted to vacuum pack foodstuffs or other products, which foodstuffs may be in a liquid or the like. For example, vacuum packaging system 10 may be adapted to vacuum pack fruit or other food in a liquid syrup, both the fruit and the syrup being vacuum-packaged and liquid-packed.

Vacuum packaging system 10 includes a chain conveyor 12 which carries a plurality of conveyor molds or dies 14. Chain conveyor 12 and dies 14 are caused to be moved in a direction, as indicated by the arrow 16, by appropriate motive means (not shown). As the chain conveyor 12 and the dies 14 move in direction 16, the chain conveyor and the dies enter and leave various stages, designated A-G for convenience, wherein various steps in loading and forming the vacuum-sealed package is accomplished, as will be explained hereinafter.

At one side of vacuum packaging system 10, there is provided a roll 18 which supplies a heat-sealable plastic packaging material 20 which is utilized to form the bottom of the vacuum-sealed package. Roll 18 may be mounted on an appropriate play-out roller 22 which is controlled by means (not shown) for supplying heatsealable plastic packaging material 20 from roll 18 at a predetermined rate. Idler rollers'24a, 24b may also be provided for controlling the tension of heat-scalable plastic packaging material 20.

Similarly, roll 26, mounted on play-out roller 28, is disposed at the other side of vacuum packaging system 10 for supplying a heat-scalable plastic packaging material 30. Appropriate means (not shown) may be included for controlling the rate or supply of heatsealable plastic packaging material 30. A tensioning mechanism, generally designated 32, is provided for controlling the tension of heat-sealable plastic packaging material 30 as this material is supplied from roll 26 rollers 36, etc. Idler roller 38, disposed near the top of the flow path for dies 14, is provided to change the direction of heat-sealable plastic packaging material 30 as this material exits tensioning mechanism 32. Thus, heat-scalable plastic packaging material 30 is caused to travel in a horizontal direction by idler rollers 38. As will be explained hereinafter, heat-sealable plastic packaging material 30 supplied from roll 26 is utilized to form the top of the vacuum-sealed package.

By way of general description, package bottom 40 (see FIGS. 4 and 5) is formed at stage A by forming element 42, and also at stage B and C. At stage D, loading element 44 deposits, as indicated by arrow 46, foodstuff 48 or other products to be packaged into the formed package bottom 40. By way of example, foodstuff 48 may be liquid-packed in a syrup or other liquid 50 (see FIG. 5). Heat-scalable plastic packaging material 30, provided from roll 26, is introduced at stage E and directed, by idler roller 38, to lie on top of the dies, thereby forming a package top 52 (see FIG. 5) for the package. A sealing element 54, located at stage E, partially seals the package top 52 to package bottom 40. At stage F, a vacuum chamber 56,'according to the present invention, which is connected to a control 58 by an appropriate conduit 60, performs several functions. First, and as will be explained hereinafter, vacuum chamber 56 vacuum packs the package by evacuating the air between package bottom 40 and package top 52 through the unsealed portion of the package. After evacuation has been completed, sealing bars or elements, to be described hereinafter, seal the unsealed portion of the package thereby maintaining the package in its vacuum or evacuated state. Lastly, control 58 operates in conjunction with vacuum chamber 56 to vent the vacuum chamber thereby clearing the chamber and the vacuum lines from liquid or other material which may have been drawn into the lines during the evacuation of the package. The package then travels to stage G where knife elements (not shown) I cut individual packages from the plurality of packages which may have been formed in a single die 14.

Referring now to FIGS. 4 and 5, the construction details of conveyor mold or die 14 and vacuum chamber 56 are shown. Die 14 includes a main body 62 which defines die cavities 64. Two such die cavities 64 are provided, although it is to be understood that a different number of die cavities may be provided, if so desired. Die cavity 64 may include spacer elements (not shown) having a shape which conforms to the die cavity and which allows the die cavity to form packages of various sizes, the size depending on the shape of the spacer element inserted into the die cavity. Die body 62 also defines a plurality of bottom vacuum channels 66a 66d which are connected, via a common bottom vacuum channel 66e, to a fitting 70 and a hose 72. As will be explained hereinafter, hose 72 is adapted to be connected to a source of vacuum such that bottom vacuum channels 66a 66d exert a vacuum force on the bottom of cavity 64 thereby maintaining package bottom 40 at the bottom of the cavity during the various stages in vacuum packaging system 10.

Die 14 includes top clamps 74, disposed at the top of the die, for clamping package bottom 40 to the top of the die (see FIG. 5). Top clamps 74 are associated with top clamp release mechansims (not shown) which operate to release the top clamps after the package has been evacuated, vacuum sealed and vented. Die 14 may also include a rubber cushion or gasket 76 which insures that a proper seal will be obtained as vacuum chamber 56 engages die 14 to evacuate and vacuum seal the package. Gasket 76 also functions to insure that a proper seal is provided between vacuum chamber 56 and die 14 during the venting mode of vacuum packaging system 10. Another rubber cushion or gasket 78 insures that an adequate seal is made between package top 52 and package bottom 40 as sealing bars or elements, to be described in more detail hereinafter, carried by vacuum chamber 56 move down to cooperate wth dic 14.

Vacuum chamber 56 includes a housing 80 which is adapted to be moved downwardly, by appropriate motive means (not shown) to engage die 14 (compare FIGS. 4 and 5 Housing 80 defines a top vacuum channel or port 82, located at the top of housing 80, which channel is adapted to receive a fitting 84 and hose 80. Housing 80 includes a top wall 81 and side walls 83. As will be explained hereinafter, although hose 86 is adapted to be connected to a vacuum source, the primary function of top vacuum channel 82 is to enable air, or the like, to be introduced into vacuum chamber 56 during the venting mode of the system thereby enabling fluid or other excess material to be vented out, of vacuum chamber 56 and the vacuum lines associated therewith.

The evacuation of the package, i.e., the air between package bottom 40 and package top 52, is provided through side vacuum channels or ports 88. Specifically, vacuum chamber 56 includes side vacuum channels or ports 88, disposed along side wall 83 of the vacuum chamber, which side vacuum channels each define a plurality of side channel portions 90 (see FIG. 5 and FIG. 6), each of which are adapted to cooperate with corresponding side channel portions 92 defined in housing 80 (see FIG. 5). Side channel portions 90 open into a common side chamber 94 which is adapted to receive a fitting 96 and a hose 98 (see FIG. 6). As will be explained hereinafter, hose 98 is connected to a vacuum source and, accordingly, it will be appreciated that the vacuum source-provides the necessary vacuum for evacuating the space between package bottom 40 and package top 52, the air being withdrawn through the various side channel portions 90 and the side chamber 92 of side vacuum channels 88.

Vacuum chamber 56 also includes sealing bars 100 which are adapted to move downwardly from the position indicated in FIG. 5 such that sealing projections 102, subsequent to evacuation of the package, seal the unsealed space between package bottom 40 and package top 52. Specifically, sealing bars 100 are springbiased and are adapted to move against spring elements 104 connected, at one end thereof, by rivets 106 to housing 80, to enable sealing projections 102 to cooperate with gasket 78, thereby completing the seal between package bottom 40 and package top 52 to thus maintain the evacuated or vacuum-sealed state of the package.

Sealing bars 100 include heating elements 108, such a wire filaments or the like, which heating elements are adapted to be connected to an appropriate heating source in order to heat sealing projections 102 to the necessary temperature required for the sealing projections to melt heat-scalable

plastic packaging materials

20 and 30, thereby sealing the package top and bottom. It is apparent that if sealing projections 102 are not maintained at this requisite temperature, package top 52 will not be fully sealed to package bottom 40 resulting in a faulty package lacking the desired vacuum-seal. As will be indicated hereinafter, one advantage of vacuum chamber 56 is that the package is evacuated through the side vacuum channels 88 thereby providing a path which does not adversely cool sealing projections 102. Sealing bars include arms 110 which are adapted to move the sealing bars in the vertical direction by appropriate motive means (not shown) sufficient to overcome biasing spring 104. The motive means may move sealing bars 100 in the downward direction only, the bars returning to their raised position, illustrated in FIGS. 4 and 5, by the action of the biasing spring or, in the alternative, the motive means may move the sealing bars upwardly as well as downwardly.

As indicated hereinbefore, vacuum chamber 56 is adapted to be controlled by control mechanism 58, the operation of which is schematically indicated in FIGS. 2 and 3. Specifically, control mechanism 58 includes a vacuum source, such as a vacuum pump 112, which is adapted to be controlled by a cam-operated valve 114. Cam-operated valve 114, which is controlled by a cam 116 and cam-follower 118, also controls an inlet port 120. When vacuum packaging system 10 is in the evacuation mode (FIG. 2), valve 114 functions to enable vacuum pump 112 to evacuate vacuum chamber 56. On the other hand, when vacuum packaging system 10 is in the vent mode (FIG. 3), valve 114 operates to enable air to flow into chamber 56 from an inlet port 120, as will be explained hereinafter.

Hose or line 72, connected to bottom vacuum channels 66a 66c, hose or line 86, connected to top vacuum channel 82, and hoses or lines 98, connected to side vacuum channels 88, are coupled to a manifold 122 which is connected to cam-operated valve 114. A plurality of pressure-actuated

valves

124, 126, 128 are located, respectively, in

hoses

86, 72 and 98 for controlling the flow of air through the hoses. By way of example, valve 128 may include a valve member 128a, which is spring-biased by a spring element 28b, to close a valve head 128C. Accordingly, valve 128 functions to prevent the flow of air, for example, from inlet port back to pressure chamber 56, i.e., this valve P events air flow from left to right in hose 98 as viewed in FIG. 3. On the other hand, valve 128 allows the flow of air from right to left in hose 98 such as flow of air from pressure chamber 56 caused by vacuum pump 112, since air flow in this direction is sufficient to overcome the bias of spring element 128b to open valve head 1280.

Valve 126 is of substantially similar construction and includes a valve member 126a, a spring element 126b and a valve head 126c which are arranged to allow the fiow of air from vacuum chamber 56, i.e., from right to left in hose 72, but which functions to close valve head 1260 to prevent substantial flow of air back into the vacuum chamber, i.e., from left to right in hose 72. However, valve 126 is slightly modified to include a small opening or aperture 126d defined in valve head 126C. Thus, a small amount of air (indicated by the dashed arrows in FIG. 3) may flow back to vacuum chamber 56, i.e., from left to right in hose 72, notwithstanding the fact that this valve is closed Valve 124 is of identical construction to valve 126 and includes a valve member 124a, a spring element l24b and a valve head 124a having a valve opening or aperture 124d defined therein. Valve 124 is disposed in hose 86 in a manner to allow opposite flow as compared to valve 126; that is, valve 124 allows air flow to vacuum chamber 56, as indicated by the solid arrows going from left to right in FIG. 3, but allows only a small flow of air, indicated by the dashed arrows going from right to left in FIG. 2, in the opposite direction.

Hoses 98 (one connected to each side of channel 88), also include bleed valves 130 and a liquid trap 132, disposed between the bleed valves and valve 128, which is adapted to act as a reservoir for storing any liquid or syrup 50 which is drawn into hoses 98 during the evacuation mode.

The operation of vacuum packaging system 10 may be understood by considering the travel of a typical'die 14 from stage A to stage G, it beingunderstood, however, that all operations of vacuum packaging system 10 take place simultaneously, so that while one package may be at loading station D, another package may be at evacuation, final seal and venting stage F, etc.

Heat-scalable plastic packaging material 20, supplied from roll 18, is placed on die 14 with top clamps 74, at

the top of die 14, holding the heat-scalable plastic packaging material in place. At stage A, a conventional heating element 42 heats the heat-scalable plastic packaging material causing the material to become malleable in shape. The die proceeds to stage B where suction is applied, for example, via hose 72, causing material 40 to be drawn into die cavities 64 (two packages may be formed in die 14 since this die includes two die cavities; however, it is readily apparent that other numbers of die cavities may be chosen to be formed in die 14). Die 14 proceeds to stage C where material 20 is allowed to cool within the die cavity thereby forming package bottom 40.

At stage D, a predetermined amount of foodstuff 48, which may be in liquid or syrup 50, is deposited or loaded into the formed package bottom by a loader 44.

Die 14 continues to move to stage E where heatsealable plastic packaging material 30, supplied from roll 26, is placed on die 14. Material is advantageously chosen to be of a width sufficient for this material to rest on the inner ends of top clamps 74 as the material is placed on die 14 (see FIGS. 5 and 6). Sealing element 54 then partially seals heat-sealable material 20 to heat-scalable material 30. In other words, and as indicated in FIG. 6, sealing element 54 seals package top 52 to package bottom 40, at the top of die 14, thereby forming a package lip or edge 134a along three sides and part of a fourth side of the package. However, it should be noted that although the sealed portion 134a extends substantially around the top or lip of the package, package top 52 and package bottom 40 remain unsealed, as indicated at 134b, which unsealed portion of the package is adjacent top clamp 74. As will be explained in more detail hereinafter, vacuum chamber 56 evacuates the package throughv this unsealed package portion.

Die 14 is then transported to stage F such that the die is positioned beneath vacuum chamber 56, as illustrated in FIG. 4. As will now be explained, evacuation, final sealing and, for the case where the foodstuff is packaged in a liquid,.venting, is accomplished at stage P.

As indicated hereinbefore, the air between package bottom 40 and package top 52 is evacuated through the unsealed portion 134b of the package. Specifically, and referring to FIGS. 2, 5 and 6, vacuum chamber 56 is moved downwardly, by appropriate motive means (not shown), from the position illustrated in FIG. 4 to the position illustrated in FIG. 5 such that housing engages die 14 at gasket or sea] 76 thereby providing an airtight seal between the vacuum chamber and the die. Note that with vacuum chamber 56 in this position, sealing bars 100 have not moved relative to housing 80 and, therefore, the sealing bars remain in their inoperative position relative to die 14.

With vacuum chamber 56 in its evacuation mode position (illustrated in FIG. 5), the vacuum chamber is evacuated. Specifically, cam 116 controls camoperated valve 114 to enable vacuum pump 112 to withdraw airfrom the vacuum chamber. Thus, a strong vacuum is applied to hoses 98 such that the air between package bottom 40 and package top 52 is withdrawn through the unsealed portion 134b of the package. The majority of this air (as well as the majority of the air in vacuum chamber 56, that is, the air between the top of the die 14 and housing 80) is withdrawn, via the side vacuum channels 88. This is indicated by the solid arrows adjacent hoses 98 in FIG. 2 as well as the arrows indicating evacuation in FIGS. 5 and 6. I With vacuum chamber 56 in the evacuation mode, air is also withdrawn from hose 72 (see FIG. 2), such that package bottom 40 is maintained contiguous with cavity 64. Thus, the vacuum applied to hose 72 insures that package bottom 40 will not flex or buckle as the space between the package top 52 and the package bottom 40 is evacuated.

With vacuum chamber 56 in this state, a small amount of air is also withdrawn from chamber 56 via I hose 86 connected to the top of the vacuum chamber.

Specifically, and referring to FIG. 2, although valve 124 is nominally closed when the vacuum pump is operative, a small amount of air (indicated by the dashed-arrows in FIG. 2) is allowed to pass through aperture 124d in the valve. By way of example, 90 or percent of the air within vacuum chamber 56 is withdrawn through side vacuum channels 88, while only 5 or 10 percent of the air is withdrawn through top vacuum channel 82.

The advantages provided by vacuum chamber 56 over prior art vacuum chambers may be readily appreciated by reference to FIG. 5. As indicated by the arrows in FIG. 5, during the evacuation mode of vacuum chamber 56, the air between package bottom 40 and package top 52 is evacuated, through the unsealed portion 134b of the package, and is drawn through side vacuum channels 88 to hoses 98. Hoses 98 also withdraw much of the air in the rest of the vacuum chamber, i.e., the air between housing 80 and the die top. Since the unsealed portion l34b of the package is in close proximity to the side vacuum channels, the air between package bottom 40 and package top 52 may be evacuated quickly and efficiently.

In addition to the evacuation of air from the package, vacuum pump 112 also pulls out liquid 50 through the unsealed portion 134b of the package. In addition to clogging the hoses (a problem which is alleviated during the venting mode which will be discussed hereinafter), the flow of liquid in prior art vacuum chambers (that is, chambers where the evacuation of the package is via a top channel similar to port 82) is around the sealing bars and this, in turn, cools the temperature of the sealing bars often to a temperature wherein the sealing bars do not function properly to provide a final seal for the package. However, according to the present invention and as indicated in FIG. 5, any liquid withdrawn through the unsealed portion 134!) of the package, does not flow around the sealing bars 102, but rather, is directed by package top 52, spring 104 and top clamp 74 to the side channels 88. Thus, the sealing bars in vacuum chamber 56 are not cooled to an extent comparable to existing vacuum chambers-It sbould be noted that the problem of cooled sealing bars (remedied by chamber 56) is a problem even in those cases where only air is drawn over the sealing bars. This problem is aggravated, however, when the product is liquid-packed, i.e., liquid is drawn across the bars. Not only does this cool the sealing bars, but it renders them sticky, etc.

Relatively no liquid is withdrawn via hose 86 since top channel 82 is relatively far removed from the unsealed portion of the package and since little vacuum pressure is applied to the top channel as a result of valve 124 which is nominally closed. However, the S or 10 percent vacuum applied to this port does, as indicated in FIG. 5, withdraw some air from the space between package top 52 and housing 80 of the vacuum chamber. As a result thereof, turbulence is greatly reduced in vacuum chamber 56 during the evacuation mode.

After the package has been evacuated, but with housing 80 still in the position illustrated in FIG. 5, sealing bars 100 move downwardly, relative to the housing, against the action of spring 104 such that sealing projections 102 seal the unsealed portion 134b of the package. Sealing bars 100 operate in an efficient manner to provide an edequate seal since the bars have not been cooled, by the flow of liquid (or air) around projections 102, in a manner existing in prior art vacuum chambers. Thus, package top 52 is now completely sealed to package bottom 40 thereby maintaining the package in its vacuum-packed or evacuated state. After the package has been fully sealed, sealing bars 100 move upwardly, relative to stationary housing 80, to resume the position illustrated in FIG. 5.

As indicated hereinbefore, particular problems arise when foodstuffs 48 are liquid-packed. Specifically, aside from the cooling of the sealing bars, it is apparent that when conventional vacuum chambers, having merely a top vacuum channel or port (comparable to top vacuum channel or port 82) is utilized, liquid 50 is withdrawn through this channel into hose 86. As a result thereof, when the vacuum source is rendered inoperative, much of this liquid rushes back into the vacuum chamber and, particularly, much of this liquid is deposited on the sealed package top. Not only will accumulation of liquid in the vacuum chamber render'the vacuum chamber inoperative, but even a small amount of liquid deposited on the top of the package renders the package sticky or otherwise unattractive to the consumer. Accordingly, stage F of vacuum system 10 includes a venting mode which enables the vacuum packaging system to overcome the disadvantages experienced in systems according to the prior art.

The venting mode of vacuum packaging system 10 is illustrated in FIG. 3. Specifically, after the package has been evacuated at stage F and fully sealed at stage F, housing of the vacuum chamber and sealing bars remian in the position illustrated in FIG. 5. With these components of vacuum chamber 56 in this position, cam-operated valve 114 is controlled, for example, by cam 1 16, to disconnect vacuum pump 112 from manifold 122 and to connect inlet port to the manifold. 'Since the inside of vacuum chamber 56 is at less than atmospheric pressure (along with

hoses

72, 86 and 98 associated therewith), air starts to rush into the hoses towards the vacuum chamber. The rush of air to the hoses is controlled by the

various pressure valves

124, 126 and 128 as will now be explained.

Considering first the flow of air in hose 86, air from inlet 120 causes valve 124 to open by forcing valve member 1240 against spring element 124b. As a result thereof, a relatively large amount of air flows into chamber 56 via top channel 82. Thus, the flow of air through hose 86 during the venting mode is greater than (and in the reverse direction from) the flow of air through this hose during the evacuation mode (compare the arrows in FIGS. 2 and 3). This flow or rush into the vacuum chamber vents the liquid (or other material) inside hoses 98.

Specifically, and considering the flow of air in hose I 98, although air starts to flow from inlet 120 into the hose, i.e., from left to right in FIG. 3, valve 128 is rendered closed during the venting mode (compare the position of this valve in FIGS. 2 and 3) and, since this valve does not include a small opening or aperture in valve'head 128e, the valve prevents the air from inlet 120 from flowing into the vacuum chamber. However, as air .rushes into the vacuum chamber from top channel 82, the pressure differential between the inside of the vacuum chamber (now at or near atmospheric pressure) and the pressure in hoses 98 (near vacuum) causes the air, as indicated by the arrows in FIG. 3, to rush into hoses 98. It should be noted that the flow of air in hoses 98 during the venting mode is in the same direction as the flow of air through this hose during the evacuation mode (compare FIGS. 2 and 3). As a result thereof, any remaining liquid in hoses 98, that is, liquid which has not been collected by trap 132 during the evacuation mode, is forced to trap 132 and collected therein. Thus, the air introduced to vacuum chamber 56 at top channel 82 acts to vent or remove the liquid remaining in hoses 98 during the venting mode. It will be appreciated, however, that as air is introduced from hose 86 into the vacuum chamber, no liquid is deposited from this hose onto the top of the package since no liquid (or relatively no liquid) is drawn into hose 86 during the evacuation of package substantially all liquid is drawn into hoses 98.

Lastly, considering the flow of air in hose 72, although valve 126 is in its nominally closed position during the venting mode, this valve'does allow a relatively small amount of air (indicated by the dashed-arrows in FIG. 3), to flow from inlet 120 to the bottom of die 14. Specifically, this small amount of air removes the vacuum in hose 72 and, consequently, the sealed package may be easily removed from die 14, for example, after the package is cut to stage G. If hose 72 continued to apply a vacuum to package bottom 40, difficulty would be encountered in removing the package. On the other hand, if a large amount of air is free to flow to the bottom of the package, the package may well be jarred from cavity 64 which may result in improper cutting of the package at'stage G. I

In order to provide a more complete understanding of the present invention, a typical operational sequence will now be described. A I

Package bottom 40 is formed at stages A, B and C of vacuum-packaging system by heating heatscalable plastic packaging material 20 at stage A, drawing the material into cavity 64 at stage 8 (for example, by applying suction to hose 72) and by allowing the material to cool at stage C. I

At stage D, a predetermined amount of material to be packaged is loaded into the formed package bottom, that is, into the material receiving cavity formed by the package bottom. By way of example, this material may be foodstuff desired to be liquid-packed, i.e., packed in a liquid.

At stage E, heat-scalable plastic packaging material 30 is introduced and caused to cover the filled package, thereby providing a package top. Additionally, package top 52 is partially sealed to package bottom40 at stage The die is then transportedto stage F wherein evacuation, final sealing and optional venting occurf Specifically, vacuum chamber 56 moves downwardly to cooperate with die 14, thereby providing an airtight chamber. Control mechanism 58 functions to connect vacuum pump 112 to the vacuum chamber. As a result of the

pressure valves

124, 126 and 128, vacuum is applied to the bottom of the cavity (via hose 72) thereby maintaining the package in place in the cavity; the air in the space between package top 52 and package bottom is evacuated through the unsealed portion 134b of the package with this air, the majority of the air in the rest of the vacuum chamber, i.e., the air between package top 52 and housing or body 80, and some liquid in the package being withdrawn through side channels 88 by the application of vacuum to hoses 98. A relatively small amount of air, primarily from the vacuum chamber (and not from the package) is withdrawn through top channel 82 by the application of a lesser force of vacuum to hose 86. It will be appreciated that this small amount of airwithdrawn via channel 82 lessens turbulence in the vacuum chamber. It will also be appreciated that both the air and the liquid drawn from the package is directed to side channels-88, which are in close proximity to the unsealed portion of the package; As a result thereof, not only is the package evacuated quickly and efficiently, but the withdrawn liquid does not cool the sealing bars or otherwise render them sticky or inoperative. Much'of the liquid drawn into hoses 98 during the evacuation mode is collected in trap 132.

After the package has been evacuated, station F provides a final sealing mode in which sealing bars 100 move. downwardly to seal the unsealed portion of the package thereby maintaining the package in its vacuum" state.

After the venting and final sealing mode, an optional venting mode may be provided at stage F. Specifically, control mechanism 58 functions to allow air to rush into

hoses

72, 86 and 98. However, valvesl24, 126 and 128 function to control the flow of this air. Specifically, the flow of air in hose 86 is increased and reversed in direction as compared to the flow of air in hose during the evacuation mode thereby allowing the air to rush into vacuum chamber 56 via top channel 82. On the other hand, valve 128 functions to close hoses 98 thereby enabling the air rushing into the vacuum chamber to continue flowing in hoses 98 in the same direction as the flow of air in these hoses in the evacuation modepln other words, the flow of air into vacuum chamber 56 vents any remaining liquid in hoses 98, which liquid is collected at trap 132. The venting mode also provides a small amount of air which is introduced, via hose 72, to the bottom of the cavity. This enables the packages to be quickly removed.

The package may be cut from the mold at stageG.

Obviously, other modifications of the present invention are possible in light of the above teachings. For example, vacuum chamber 56 may be utilized with other systems since the vacuum chamber, in and of itself, operates efiiciently and with less turbulence then vacuum chambers heretofore available in the prior art. Similarly, this system may include additional air pumps, for example, to aid in the introduction of the air into the vacuum chamber during the venting mode. Still further, although the embodiment disclosed has been explained with reference to a liquid-packed foodstuff, it will be appreciated that the invention has application to other types of packaged materials. For example, if the package is granular in nature, it is the material itself which is drawn up during the evacuation mode; and this material may be vented from the lines during the venting mode. Additionally, this system may be utilized with otherstages, for example, a detectable gas or the like may be introduced into the package prior to the final seal thereof in order to detect leaks or the like in the package. It is to be understood, therefore, that the embodiment described is merely an example of the principles of the invention. Additional embodiments may be devised by those skilled in the art without departing from the spirit or scope of the present invention.

What is claimed is:

1. An apparatus for packaging a material comprising means for providing a first package member defining a material-receiving cavity, means for depositing said material in said material-receiving cavity, means for providing a second package member, means for partially sealing said first package member to said second package member and for defining an unsealed package portion, means including a first conduit for evacuating said package through said unsealed package portion, means for sealing said unsealed package portion thereby maintaining said package in its evacuated state, and means including a second conduit for venting said first conduit by introducing air into said second conduit.

2. The invention according to claim 1 wherein said means for evacuating said package further includes a vacuum chamber adapted to be connected to a source of vacuum for withdrawing at least the air between said first package member and said second package member.

3. The invention according to claim 2 wherein said vacuum chamber includes at least two channels adapted to be connected to said first conduit and said second conduit, respectively.

4. The invention according to claim 3 wherein said secondconduit includes valve means for limiting flow of air from said vacuum chamber to said source of vacuum and for permitting flow of air to said vacuum chamber, said first conduit including valve means for permitting flow of air from said vacuum chamber to said source of vacuum and for limiting flow of air to said vacuum chamber.

5. The invention according to claim 3 wherein said means for venting said vacuum chamber includes means for providing a source of air and said first and second conduits define a venting path from said source of air to said second conduit to said vacuum chamber and from said vacuum chamber to said first conduit.

6. The invention according to claim 5 wherein said means for evacuating said package includes means for withdrawing air from said vacuum chamber into said first conduit in a first predetermined direction.

7. The invention according to claim 6 wherein said venting means includes means for introducing air into said vacuum chamber and for causing said air to flow from said vacuum chamber through said first conduit in the same direction as the flow of air in said first conduit during evacuation of said package.

8. The invention according to claim 7 wherein said first conduit includes means for trapping material withdrawn from said vacuum chamber.

9. The invention according to claim 8 wherein said means for venting said vacuum chamber includes means for causing the material remaining in said first conduit subsequent to evacuation of said package to move toward said trap means.

10. The invention according to claim 1 further comprising means for maintaining said package in proper position relative to said vacuum chamber.

11. The invention according to claim 10 wherein said means for keeping said package in proper position includes means for applying a vacuum to said package.

12. The invention according to claim 1 1 further comprising means for removing said package.

13. The invention according to claim 12 wherein said means for removing said package includes means for applying air pressure against said package.

Claims

1. An apparatus for packaging a material comprising means for providing a first package member defining a material-receiving cavity, means for depositing said material in said materialreceiving cavity, means for providing a second package member, means for partially sealing said first package member to said second package member and for defining an unsealed package portion, means including a first conduit for evacuating said package through said unsealed package portion, means for sealing said unsealed package portion thereby maintaining said package in its evacuated state, and means including a second conduit for venting said first conduit by introducing air into said second conduit.

4. The invention according to claim 3 wherein said second conduit includes valve means for limiting flow of air from said vacuum chamber to said source of vacuum and for permitting flow of air to said vacuum chamber, said first conduit including valve means for permitting flow of air from said vacuum chamber to said source of vacuum and for limiting flow of air to said vacuum chamber.

12. The invention according to claim 11 further comprising means for removing said package.