WO2000056623A1

WO2000056623A1 - Package, lid and vent for pressure equalization

Info

Publication number: WO2000056623A1
Application number: PCT/US2000/007586
Authority: WO
Inventors: James P. Manning; John M. Hess, Iii; Timothy R. Socier
Original assignee: Seaquist Closures Foreign, Inc.
Priority date: 1999-03-23
Filing date: 2000-03-22
Publication date: 2000-09-28
Also published as: AU4019800A; TW450921B

Abstract

A package (15), lid assembly (20), and a vent device (24) are provided for decreasing the difference between the internal pressure within a package (15) and the external ambient air pressure. The vent device (24) is provided for mounting to the wall (26) of a package (15) or other enclosure wherein the wall (26) has an aperture (28) in which the vent device (24) is disposed. The vent device (24) includes a tubular portion (50) having a passage (52) extending therethrough. A valve (80) is disposed within the tubular portion (50) across the passage. The valve (80) includes a sleeve (117) and an occlusion member (82) which has at least two slits (84) extending there through. The slits (84) are closed when there is no pressure differential across the occlusion member (82). The slits (84) open when exposed to a predetermined pressure difference between (1) the ambient atmosphere outside the package (15) or other enclosure, and (2) the gases inside the package (15) or other enclosure.

Description

PACKAGE, LID AND VENT FOR PRESSURE EQUALIZATION

TECHNICAL FIELD The present invention relates to product packaging, and in particular to a package, a lid assembly, and a vent device accommodating equalization of the package internal pressure with the external ambient air pressure. The invention is particularly suitable for incorporation in a system containing a comestible product which is to be cooked or otherwise heated, subsequently cooled, and stored.

BACKGROUND OF THE INVENTION AND

TECHNICAL PROBLEMS POSED BY THE PRIOR ART

In the United States of America, a system has been marketed for cooking or otherwise heating a comestible product in a microwave oven. The system is disclosed in the international patent application PCT/US97/04580 (Publication No. WO 98/08748). The system includes a receptacle or container with a lid assembly. The lid assembly is adapted to be sealingly mounted to, and subsequently removed from, the container in which the food product is placed. The lid assembly includes a lid with a central aperture and a plurality of vent holes spaced apart on a circular locus around the central aperture. A flexible, tube-like member is mounted in the central aperture, and one end of the flexible member includes a flexible, circular flange or disk member which extends radially on the outside of the lid to cover the vent holes. The flexible member in the lid aperture has a hollow bore portion extending through the aperture, and the hollow bore portion terminates below the interior side of the lid in a closed lower end portion defining a slit which is normally closed. The above-described system is used as follows. A comestible product is placed within the container and covered with the lid assembly. The package is exposed to microwave radiation in a microwave oven. The microwave radiation heats the comestible product, and the vapor pressure within the container increases. When the internal vapor pressure has increased sufficiently, the circular disk over the vent holes is deformed or deflected slightly upwardly to permit the vapor (e.g., steam) to be expelled from the container interior. This accommodates a generally controlled release of the vapor during the heating process. When the heating process is terminated, and/or when the generation of vapor within the container otherwise terminates, the circular disk over the vent holes returns to the initial, sealing position over the vent holes. The user can then remove the lid assembly to gain access to the heated or cooked comestible product without the risk that a substantial amount of hot vapor or steam will be released as the lid assembly is removed.

Further, with the above-defined system, the lid assembly can be re-mounted to the container to cover any remaining comestible product for storage. The covered container may be cooled, such as by placing it in a refrigerator. The cooling of the container may result in a decrease in the internal pressure within the container. The slit at the closed lower end of the flexible member in the central aperture opens under a sufficient pressure differential to permit ambient air to flow into the container interior and equalize the pressure. This will tend to minimize the likelihood of the lid deforming inwardly into the container interior. After sufficient ambient air has flowed into the container to equalize the internal and external pressures, the slit closes to minimize uncontrolled ingress of additional air or contaminants which could deleteriously affect the comestible product during storage.

It would be desirable to provide an improved system for accommodating the venting of vapor from an enclosure (such as a food- containing package) during heating and for accommodating venting of air into the enclosure during cooling.

In particular, it would be desirable to provide a system which would effect venting into and out of an enclosure at relatively low pressure differentials. It would also be advantageous if such an improved system could be effectively operated with a reliable, but less complex, vent structure.

Further, it would beneficial if such improved system could accommodate venting into a package and venting out of the package in various different locations on the package as may be desirable for a particular comestible product or intended use.

It would also be desirable to provide an improved system which would not have any leakage, or any significant leakage, during the periods when vapor is not being expelled from the package and when ambient atmosphere is not being vented into the package.

It would also be advantageous if such an improved system could accommodate packages that have a variety of shapes and that are constructed from a variety of materials.

Further, it would be desirable if such an improved system could accommodate efficient, high-quality, large volume manufacturing techniques with a reduced product reject rate to produce a system with consistent out-venting and in-venting characteristics.

The present invention provides an improved system which can accommodate designs having the above-discussed benefits and features.

BRIEF SUMMARY OF THE INVENTION The present invention provides a system for venting an enclosure (e.g., package, container, tank, etc.) to minimize the difference between the external pressure the internal pressure during heating (e.g., when a gas or vapor is generated and/or expands inside the package) and during cooling (when the pressure within the package decreases). The system of the present invention is adaptable for use with a variety of packages that can be heated and/or cooled in a variety of ways through a range of temperatures.

The components of the system of the present invention are relatively easy to manufacture, yet the components function well to provide consistent venting characteristics with a reduced leakage potential during the periods of time when the venting system is not operating.

The system of the present invention is especially useful in providing venting into an enclosure and out of an enclosure at relatively low pressure differentials (e.g., 10 inches of water pressure differential or less).

According to one aspect of the present invention, a vent device is provided for an enclosure. The enclosure could, for example, be a microwavable package or other package wherein the package is adapted for containing a comestible product. The enclosure has a wall defining (1) an exterior surface, (2) an interior surface, and (3) an aperture extending between the exterior surface and the interior surface.

The vent device includes a tubular portion. The tubular portion (a) extends through the aperture and forms a seal between the tubular portion and the wall of the aperture, and (b) defines a passage through the aperture.

A valve is disposed within the tubular portion across the passage. The valve includes an occlusion member having at least two cross slits extending therethrough that are closed when there is no pressure differential across the occlusion member, and that opens when exposed to a pressure difference between the ambient atmosphere outside the enclosure and the gases inside the enclosure if the pressure inside the closure exceeds the pressure outside the enclosure by a predetermined amount.

According to another aspect of the invention, a package is provided for a comestible product which can be heated and cooled. The package includes a container for containing a comestible product, and the package has an opening. A lid is provided for engaging the container around the opening. The lid has an exterior surface and an interior surface. The lid defines an aperture extending between the exterior surface and the interior surface. A vent device is mounted to the lid across the aperture. The vent has a tubular portion that (a) extends through the aperture and forms a seal between the tubular portion and the lid at the aperture, and (b) defines a passage through the aperture. A valve is disposed within the tubular portion and extends across the passage. The valve includes an occlusion member having at least two cross slits extending therethrough that are closed when there is no pressure differential across the occlusion member and that opens when exposed to a pressure difference between ambient atmosphere outside the container and the gases inside the container if the pressure inside the container exceeds the pressure outside the container by a predetermined amount.

A further aspect of the invention relates to a lid assembly for covering an opening in a container. The lid assembly includes a lid for engaging the container around the container opening. The lid has an exterior surface and an interior surface. The lid defines an aperture extending between the exterior surface and the interior surface. The lid assembly further includes a vent device which (1) is mounted to the lid across the aperture, and (2) has a tubular portion that (a) extends through the aperture and forms a seal between the tubular portion and the lid at the aperture, and (b) defines a passage through the aperture. The vent device also includes a valve disposed within the tubular portion extending across the passage. The valve includes an occlusion member having at least two cross slits extending therethrough that are closed when there is no pressure differential across the occlusion member, and that opens when the occlusion member is exposed to a pressure difference between the ambient atmosphere outside the container and the gases inside the container if the pressure inside the container exceeds the pressure outside the container by a predetermined amount. Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention, from the claims, and from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings that form part of the specification, and in which like numerals are employed to designate like parts throughout the same, FIG. 1 is a perspective view of a package of the present invention;

FIG. 2 is an enlarged, fragmentary, exploded perspective view of the central portion of the lid and vent device of the package of the present invention; FIG. 3 is a top plan view of the vent device;

FIG. 4 is a side elevational view of the vent device; FIG. 5 is a bottom plan view of the vent device; FIG. 6 is an enlarged, cross-sectional view taken generally along the plane 6-6 in FIG. 3; FIG. 7 is a top plan view of the lid assembly employed in the package shown in FIG. 1;

FIG. 8 is a cross-sectional view taken generally along the plane 8-8 in FIG. 7;

FIG. 9 is a greatly enlarged, fragmentary, cross-sectional view taken generally along the plane 9-9 in FIG. 7;

FIG. 10 is a view similar to FIG. 9, but more greatly enlarged, and FIG. 10 shows a moved position of a part of the vent device with solid lines and shows the unstressed, normal position of that portion of the vent device in phantom with dashed lines; FIG. 11 is a view similar to FIG. 10, but FIG. 11 shows a later stage in the operation of the vent device as it opens outwardly to permit internal vapor to be expelled through the vent device; and

FIG. 12 is a view similar to FIG. 11, but FIG. 12 shows the operation of the vent device as it opens inwardly to accommodate the venting of ambient atmosphere through the vent device and into the container.

DETAILED DESCRIPTION While this invention is susceptible of embodiment in many different forms, this specification and the accompanying drawings disclose some specific forms as examples of the invention. The invention is not intended to be limited to the embodiments so described, however. The scope of the invention is pointed out in the appended claims. For ease of description, the system of this invention is described in a normal (upright) operating position, and terms such as upper, lower, horizontal, etc., are used with reference to this position. It will be understood, however, that the system of this invention may be manufactured, stored, transported, used, and sold in an orientation other than the exact, upright position described herein.

FIG. 1 illustrates a package 15 in which a comestible product (e.g., food, water, etc.) can be heated and subsequently cooled. The package 15 may be provided to the consumer with a comestible product contained therewithin. Alternatively, the package 15 may be provided to the consumer as an initially empty package, and the consumer may place a comestible product inside the package 15.

The package 15 includes a container or receptacle 18 (FIGS. 1 and 8) which has an open, upper end. The package 15 further includes a lid assembly 20 (FIGS. 1 and 8) adapted to be mounted to the upper end of the container 18 over the container opening to form a leak-tight peripheral seal around the opening. The lid assembly 20 includes a lid 22 and a vent device 24 which is mounted in the center of the lid 22. The lid 22 has a central wall or wall portion 26 (FIGS. 2, 8, and 9) which defines an aperture 28 (FIGS. 2 and 9) in which a portion of the vent device 24 is disposed. The package 15 need not include a lid 22 per se. In a contemplated alternate embodiment of the package 15 (not illustrated), the package 15 may include a receptacle having a substantially closed configuration of unitary construction defining a wall with an aperture for receiving the vent device. Such a unitary, enclosure would also have an access opening, separate from the aperture for the vent device, and such an access opening would be sealingly closed with a removable cap. This would permit, for example, comestible material to be fed through the opening into the package and to be removed from the package through the opening. Such a removable cap could be substantially smaller than the lid 22 illustrated for the preferred embodiment in FIGS. 1 and 8. Further, the access opening could be provided in a sidewall portion of a container or receptacle, or even in a bottom floor portion of such a container or receptacle. While such an access opening for accommodating the loading or removal of material (e.g., food) in the package or other enclosure may be located in a sidewall or bottom floor of the package or other enclosure, both the vent device and the aperture for receiving the vent device, would preferably be located in an upper portion of the package or other enclosure. Most preferably, such a vent device would be located in a top wall, ceiling portion, or roof portion of such a package or other enclosure. In the preferred embodiment of the package 18 illustrated in

FIGS. 1 and 8, the lid 22 includes an annular skirt 30 for being received on the exterior upper periphery of the container 18. An upper, interior region of the skirt 30 may be provided with a suitable sealing configuration, such as an interior lip, flange, or groove (not illustrated) for receiving the upper edge of the container 18. In a presently preferred embodiment, both the container 18 and the lid 22 are molded from thermoplastic material, such as polyethylene, and both have some flexibility, with the lid skirt 30 being generally slightly more flexible than the upper peripheral edge of the container 18 so as to accommodate placement and removal of the lid 22.

The particular detailed structure of the lid skirt 30 and container edge for facilitating the mounting of the lid 22 to the container 18, and for effecting a leak-tight sealing engagement between the two components, forms no part of the present invention. Conventional designs for such lid and container leak-tight sealing engagements are well known to those of ordinary skill in the art.

If desired, the lid 22 may include one or more outwardly extending ledges or handles 32 for facilitating placement and removal of the lid 22 and/or for facilitating carrying of the package 15 when the lid 22 is securely mounted to the container 18.

In the presently preferred embodiment, the lid aperture 28 is generally circular, and the lid wall 26 is a generally annular, flat region around the aperture 28. Preferably, the wall 26 is recessed somewhat below the surrounding area of the lid 22. To this end, the lid 22 includes an oval, dished region 36 (FIGS. 2 and 8) which extends from the outer periphery of the wall 26 to an elevated, generally flat, annular, intermediate surface 40 in the lid 22. The outer periphery of the intermediate surface 40 merges with an annular, crowned or convex region 42, and the skirt 30 depends from the outer periphery of the crowned region 42. The inner surface of the skirt 30 preferably includes a plurality of circumferentially spaced-apart ribs 33 (FIG. 8) for engaging exterior surface portions of the upper portion of the container 18.

As best illustrated in FIGS. 3-6, the vent device 24, in the preferred form, is a unitary molded structure which is preferably molded from liquid silicone rubber of the type manufactured under the trademark

SILASTIC LSR or DC-595 by Dow Corning Corporation, United States of America. The vent device 24 is adapted to be press-fit into the aperture 28 to form a snap-fit engagement with the lid 22. With reference to FIG. 9, the lid 22 includes an exterior surface 21 and an interior surface 23. The aperture 28 extends between the exterior surface 21 and the interior surface 23. The vent device 24 has a number of specific features, as described hereinafter, which aid in assembly and which effect engagement between the device 24 and the lid 22.

With reference to FIG. 6, the vent device 24 has a central, tubular portion 50, and the tubular portion 50 extends through the lid aperture 28 (FIG. 9) and forms a seal between the tubular portion 50 and the lid 22 at the aperture 28. The tubular portion 50 defines an internal passage 52 (FIG. 6). Preferably, the tubular portion 50 has a cross section which is uniform at all locations around the central longitudinal axis 60 (FIG. 6). Thus, the passage 52 is generally concentrically located within the lid aperture 28 (FIG. 9).

The upper end of the tubular portion 50 terminates in a flange 62 as shown in FIGS. 2-6. The flange 62 is generally annular, is of generally uniform thickness, and is slightly convex configuration (prior to installation on the lid 22) when viewed from the upper side of the vent device 24. When the vent device 24 is installed on the lid 22, the flange 62 becomes deformed upwardly to a generally horizontal, flat configuration where it remains in a slightly stressed state.

Between the upper end of the tubular portion 50 and the lower end of the tubular portion 50, the tubular portion 50 has a shoulder 66 which is generally annular and defines an undercut region 68 (FIG. 6) for receiving an edge of an inner peripheral margin of the lid 22 around the aperture 28 as shown in FIG. 9.

The lower end of the tubular portion 50 defines a frustoconical, tapered head or lead-in surface 70 (FIG. 6). The vent device 24 is inserted into the lid 22 by pushing the frustoconical, lead-in surface 70 against the inner peripheral edge of the lid 22 at the aperture 28. The tubular portion 50 is squeezed radially inwardly and deformed sufficiently to accommodate passage of the lead-in surface 70 through the aperture 28 until the surface of the shoulder 66 passes below the lid interior surface 23 and then snaps outwardly into place against the lid interior surface 23 as shown in FIG. 9 so as to clamp the inner periphery of the lid 22 between the shoulder 66 and the flange 62. Further, the tubular portion 50 between the shoulder 66 and the flange 62 has a sufficiently large diameter that a leak- tight sealing engagement is formed along the edge of the aperture 28.

As shown in FIG. 6, a valve 80 is disposed within the tubular portion 50 and extends across the passage 52. The valve 80 includes an occlusion member 82. The occlusion member has at least two cross slits 84, preferably two mutually perpendicular, cross slits 84 (FIG. 3) which extend through the occlusion member 82. The cross slits 84 are self-sealing in a closed configuration when there is no pressure differential across the occlusion member 82. The cross slits 84 define four flaps 86 (FIG. 3) which each defines a sector of a circle of equal size and shape. In some contemplated embodiments, there may be three or more slits 84.

The flaps 86 are closed when there is no pressure differential across the occlusion member 80 (FIG. 6), and the flaps 86 deflect to an open configuration so that the slits 84 open when the occlusion member 80 is exposed to a pressure difference between the ambient atmosphere outside the package 15 and the gases inside the package 15. When the slits 84 open, the difference between the pressure inside the package 15 and the pressure outside the package 15 is substantially eliminated or at least decreased or minimized owing to flow through the open valve slits 84.

As shown in FIGS. 6 and 9, the valve 80 includes a short annular sleeve 117 which projects inwardly from the inner surface of the tubular wall portion 50. The inner margin of the sleeve 117 merges with the outer periphery of the valve occlusion member 82. The illustrated occlusion member 82 (FIG. 6) of the valve 80 has a circular plan shape, and a generally tapered construction which is thicker at the radially outer portion thereof, and thinner at the radially inner portion thereof. This tapered construction assists in achieving a snap open/snap close action of the valve 80.

More specifically, as shown in FIG. 6, the valve occlusion member 82 has an exterior side or surface 138 which has an arcuately shaped, concave side elevational configuration which curves outwardly toward the exterior of the package 15 and is defined by a first, predetermined radius. Valve head exterior surface 138 extends continuously from the connector sleeve 117. As shown in FIG. 9, the occlusion member 82 also includes an interior side or surface 139 (FIG. 6) which has a marginal portion 140 with an arcuately shaped, convex side elevational configuration which curves inwardly, toward the interior of the package 15, and is defined by a second predetermined radius. The radius of the marginal portion 140 on interior surface 139 is larger than the radius of the exterior surface 138, such that the two surfaces 138 and 139 converge toward the center of occlusion member 82 and provide the above-noted tapered construction of the occlusion member 82.

The interior surface 139 of occlusion member 82 also includes a center portion 141, which has a circular plan shape, with a substantially planar or flat side elevational configuration, oriented generally perpendicular to valve longitudinal axis 60. The center portion 141 of occlusion member 82 assists in improving the opening and closing characteristic of valve flaps 86 defined by the slits 84, as set forth below. The radially outer perimeter of the lower portion of the occlusion member 82 is defined by a circular marginal edge 142 (FIG. 6) which begins at the interior surface 139 and extends therefrom toward the sleeve 117 with a slight outward taper, ultimately merging into the sleeve 117. The peripheral margin of the occlusion member 82 is thus thicker than the inner end of the sleeve 117 which is connected to the occlusion member

82. As can be seen in FIG. 10, the intersection of the occlusion member marginal portion 140 and the occlusion member center portion 141 defines a circular edge 144.

The connector sleeve 117 flares in a radially inwardly direction from the tubular portion 150, and also protrudes upwardly toward the exterior of the vent device 24. The marginal attachment of the inner end of connector sleeve 117 to the occlusion member 82, as well as its associated geometry, increases the effectiveness of torque forces which assist in urging the valve flaps 86 open.

The slits 84 are preferably formed by slicing through the center portion 141 of occlusion member 82, without removing any substantial amount of material therefrom, to create opposite side faces 158 and 159 on each flap 86 shown in FIG. 11 so that the opposite side faces 158 and 159 of two adjacent flaps 86 can seal against one another when the flaps 86 are in the normal, fully closed position. The side faces 158 and 159 of each valve flap 86 intersect at their free ends to define an end edge

160. The length and location of the slits 84 can be adjusted to vary the predetermined opening and closing pressures of valve flaps 86, as well as other dispensing characteristics of the vent device 24.

According to other aspects of the invention, it is to be understood that the slits 84 and flaps 86 may have different shapes, sizes and/or configurations in accordance with the characteristics desired. For example, there may be three or more slits 84. Three or more slits 84 may also be employed. Other forms of openings may also be incorporated into valve 80. The illustrated self-sealing valve 80 is preferably especially configured for use in conjunction with a particular container 18, and a specific type of fluid product (e.g., generated vapor), so as to achieve the exact venting characteristics desired. The rigidity and durometer of the valve material, and size and shape of both the occlusion member 82 and connector sleeve 117 are also important in achieving the desired venting characteristics. One specific vent device configuration has been found to be particularly effective. With reference to FIG. 6, the diameter D, is 11.43 mm (0.45 inch), the diameter D₂ is 10.54 mm (0.415 inch), the diameter D₃ is 5.97mm (0.235 inch), the diameter D₄ is 34.29 mm (1.350 inches), the diameter D₅ is 12.97 mm (0.511 inch), the diameter D₆ is 16.61 mm (0.654 inch), the diameter D₇ is 14.12 mm (0.556 inch), and the diameter D_g is 11.43 mm (0.45 inch). The thickness T, is 0.51 mm (0.020 inch), the thickness T₂ is 0.3 mm (0.012 inch), the thickness T₃ is 0.38 mm (0.015 inch), the dimension T₄ is 0.13 mm (0.005 inch), the thickness T₅ is 1.31 mm (0.051 inch), the thickness T₆ is 7.63 mm (0.300 inch), the thickness T₇ is 3.15 mm (0.124 inch), and the thickness T₈ is 1.02 mm (0.040 inch). The angle A, is 40°, the angle A₂ is 5°, the angle A₃ is 30°, the angle A₄ is 4°, and the angle A₅ is 4°. The radius R, is 12.95 mm (0.510 inch), the radius R₂ is 4.75 mm (0.187 inch), the radius R₃ is the spherical radius of the flange upper surface and is 130.50 mm (5.138 inches), the radius R, is

0.38 mm (0.015 inch), the radius R₅ is 0.38 mm (0.015 inch), and convex radius Rg is 0.64 mm (0.025 inch). Slits 84 each have a length of about 5.97 mm (0.235 inch), and are centered in valve center portion 141. The valve 80 is molded as a unitary structure with the entire vent device 24 from a liquid silicone rubber of the type manufactured under the trademark

DC-595 by Dow Corning Corporation.

Experimental tests conducted on vent devices having the above-identified specific dimensions and characteristics revealed the following operational characteristics. When the lower, convex side 139 of the closed valve 80 was subjected to an internal pressure greater than the ambient external pressure by a predetermined amount of about 10 inches of water, the valve opened outwardly to vent out some of the internal gases.

When the pressure differential across the outwardly open valve 80 decreased sufficiently below 10 inches of water, the valve 80 automatically closed. When the lower, convex side 139 of the closed valve 80 was subjected to an internal pressure less than the ambient external pressure so that the pressure outside the container exceeded the pressure inside the container by a predetermined amount of about 6 inches of water, the valve opened inwardly to vent in some of the external atmospheric air.

When the pressure differential across the inwardly open valve 80 decreased sufficiently below 6 inches of water, the valve 80 automatically closed.

In a contemplated modification of the valve operating characteristics, the predetermined differential pressure at which the valve 80 opens outwardly (e.g., 10 inches of water) and the predetermined differential pressure at which the valve 80 opens inwardly (e.g., 6 inches of water) could be substantially identical. Alternatively, the predetermined differential pressure required to open the valve outwardly could be less than the predetermined differential pressure required to open the valve inwardly.

In yet another contemplated embodiment, the valve could be employed to only vent outwardly, but not inwardly under the particular pressure differentials to be encountered during use.

It is to be understood that according to the present invention, the specific configuration and size of the vent device 24 may vary, depending on the desired predetermined inwardly and outwardly opening differential pressures and subsequent closing differential pressures.

The vent device 24 functions in the following manner in the package 15 when the lid 22 is mounted to the container 18 which contains a comestible product to be heated and subsequently cooled. The valve 80 initially assumes the inwardly protruding or concave orientation illustrated in FIG. 9, wherein the sleeve 117 and occlusion member 82 initially have their original molded shapes without deformation.

When the package 15 is heated, vapor may be generated from the comestible product, and/or existing gases in the container are heated, so that the internal pressure increases above the ambient external atmospheric pressure to establish a differential pressure across the occlusion member 82. This causes the center portion 141 of the occlusion member 82 to move outwardly somewhat, as shown in solid lines in FIG. 10, toward the exterior of package 15. The configuration of connector sleeve 117 and of occlusion member marginal portion 140 assists in permitting the axial shifting of the occlusion member center portion 141. The elastic deformation of valve 80 from its original molded shape generates a complex pattern of stresses within valve 80 which tend to resiliently resist the outward axial movement of the center portion 141, and these stresses, while not overcoming the force imposed on the valve 80 by the increased internal pressure, include an outwardly directed torque applied by connector sleeve 117 to occlusion member 82. This torque tends to resiliently urge flaps 86 toward the open position.

When the pressure in the package 15 increases further (e.g., 10 inches of water greater than the external ambient atmospheric pressure), the occlusion member 82 continues to shift outwardly by further longitudinal stretching of occlusion member 82, and the flaps 86 open to the fully open position illustrated in FIG. 11. A torque is applied to occlusion member 82 as the same shifts axially outwardly which tends to open the flaps 86. The sleeve 117 assists in effectively defining these opening forces. At least some of the gases, such as hot steam or vapor, are expelled through the open valve 80.

When the pressure within the interior of the package 15 is reduced, the pressure differential between the interior of the package 15 and the ambient exterior pressure is reduced. When the pressure differential falls below a predetermined amount (e.g., less than 10 inches of water pressure differential), forces developed in the sleeve 117 and in the occlusion member 82 through elastic deformation move the occlusion member 82 inwardly, back into its original concave orientation shown in FIG. 9. This positively and securely closes the valve 80. The user may then open the lid 22 to remove some or all of the comestible material. Later, the lid may be repositioned over the opening of the container 18 to cover any remaining comestible product within the container. The re-closed package 15 may then be cooled, as by placing it in a refrigerator or freezer. As the gasses within the package 15 cool, the pressure decreases below the exterior ambient atmospheric pressure. This creates a pressure differential across the valve occlusion member 82. Eventually, if the pressure differential exceeds a predetermined amount (e.g., 6 inches of water differential pressure), then the valve 80 will open inwardly to permit venting into the container 18 so as to minimize the difference between the pressure in the container 18 with the pressure outside of the container 18, and this prevents the lid 22 from bending or deforming inwardly.

In particular, as shown in FIG. 12, the occlusion member 82 begins to shift axially inwardly toward the interior of the package 15. The connector sleeve 117 assists in this process. The elastic deformation of the occlusion member 82 from its originally molded shape (FIG. 9) generates a complex pattern of stresses within the valve 80 which tend to resiliently resist the inward axial movement of the occlusion member 82 (but do not overcome the force imposed on the valve 80 by the greater exterior pressure). These stresses include a torque applied to the occlusion member marginal portion 140, and this torque tends to resiliently urge the occlusion member flaps toward their inwardly open positions (FIG. 12).

As the pressure differential increases further, the occlusion member 82 continues to shift axially inwardly and the stresses built up within the valve 80 cause the valve marginal portion 140 to deform from its original curved configuration to a configuration in which there is an inflection region of curvature. Further, the valve flaps 86 are caused to move inwardly to the fully opened condition illustrated in FIG. 12. The opening of the flaps 86 into the inwardly open, in-venting position is caused, at least in part, by the torque exerted on the valve 80. When the differential pressure is sufficiently reduced, owing to the in-venting ambient atmosphere, a closing differential pressure is reached (e.g., less than 6 inches of water). The valve flaps 86 thus close (FIG. 9). In particular, the force developed in the valve 80 through elastic deformation from its original molded shape tends to pull the valve 80 back into the original configuration (FIG. 9). The closing motion of the valve 80 serves to close the flaps 86 quickly and completely so as to sharply cut off the gas flow.

It will be appreciated that the valve 80 may also function to permit the user to create a slight vacuum in the covered container. In particular, when the user places the lid on the container, the user may depress the lid slightly to temporarily increase the pressure within the container. The increased pressure will open the valve 80 and exhaust some of the interior air or other gases. When the user stops pushing downwardly on the container lid, the valve 80 will close, and the lid will flex upwardly

(owing to its resiliency) to its substantially initial position on the container. This will increase the volume in the container and create a decrease in pressure within the container. However, if the pressure decrease is not sufficiently great, the valve 80 will not open inwardly to vent in, and as a result, the container will remain with the interior atmosphere at a slightly reduced pressure, and with the valve 80 closed. Thus, as a result of the removal of some of the air, the product within the container will be less susceptible to oxygen-induced spoilage or degradation.

It will be readily apparent from the foregoing detailed description of the invention and from the illustrations thereof that numerous variations and modifications may be effected without departing from the true spirit and scope of the novel concepts or principles of this invention.

Claims

WHAT IS CLAIMED IS:

1. A vent device for an enclosure, said enclosure having a wall defining (1) an exterior surface, (2) an interior surface, and (3) an aperture extending between said exterior surface and said interior surface, said vent device comprising:

(1) a tubular portion that

(a) extends through said aperture and forms a seal between said tubular portion and said wall at said aperture, and (b) defines a passage through said aperture; and

(2) a valve disposed within said tubular portion extending across said passage, said valve including an occlusion member having at least two cross slits extending therethrough that are closed when there is no pressure differential across said occlusion member, and that open when said occlusion member is exposed to a pressure difference between ambient atmosphere outside the enclosure and the gases inside the enclosure if the pressure inside the enclosure exceeds the pressure outside the enclosure by a predetermined amount.

2. The vent device as described in claim 1, in which said valve also opens when said occlusion member is exposed to a pressure difference between ambient atmosphere outside the enclosure and the gases inside the enclosure if the pressure outside the enclosure exceeds the pressure inside the enclosure by a predetermined amount.

3. The vent device as described in claim 1, wherein said occlusion member has an outer surface portion which faces outwardly and which is concave as viewed from said exterior surface side of said enclosure wall; and said occlusion member has an inner surface portion which faces inwardly and which is generally convex when viewed from the interior surface side of said enclosure wall.

4. The vent device as described in claim 1, wherein said occlusion member is recessed within said tubular portion of said vent device.

5. The vent device as described in claim 1, wherein said valve includes an annular sleeve that (1) extends from said tubular portion within said passage, and (2) is joined in a unitary construction to the periphery of said occlusion member.

6. The vent device as described in claim 1, wherein said occlusion member has a pair of intersecting slits extending therethrough defining four flaps substantially equal in size that form a closed configuration when there is no pressure differential across said occlusion member, and deflect to an open configuration when said occlusion member is exposed to a predetermined pressure difference between ambient atmosphere outside the enclosure and the gases inside the enclosure.

7. The vent device as described in claim 6, wherein said flaps have a decreased cross-sectional thickness such that the cross-sectional thickness of the flaps are the greatest in an outermost radial portion thereof.

8. The vent device as described in claim 1, wherein said vent device is constructed of silicone.

9. The vent device as described in claim 1, wherein

(1) an end of said tubular portion terminates in a shoulder for engaging said interior surface of said wall; and (2) said tubular portion has a flange extending generally radially outwardly beyond said aperture adjacent a portion of said wall to engage said exterior surface of said wall.

10. The vent device as described in claim 1 in combination with a lid for covering an opening in a container wherein said wall is part of said lid.