WO1998008748A1

WO1998008748A1 - Self venting container lid

Info

Publication number: WO1998008748A1
Application number: PCT/US1997/004580
Authority: WO
Inventors: Debra Grenert
Original assignee: Rubbermaid Incorporated
Priority date: 1996-08-29
Filing date: 1997-03-21
Publication date: 1998-03-05
Also published as: GT199700090A; ID18152A; AU2585997A

Abstract

A container and lid assembly is disclosed which includes a lid having a flexible member (20) secured to a center portion of the lid, the flexible member for selectively allowing vapor to escape the sealed container and lid assembly and the flexible member including a valve (34) to allow for the equalization of pressure between the interior and the exterior of the sealed container and lid assembly.

Description

SELF VENTING CONTAINER LIP

BACKGROUND OF THE INVENTION

Field of the Invention

The subject invention relates in general to container and lid assemblies for

cooking, heating, serving and storing food articles or the like. More particularly, this

invention relates to a container having a lid with a flexible member secured to the lid

which cooperates with the lid to allow controlled venting of the interior container and

includes a valve for establishing an equilibrium pressure between the interior and the

exterior of the container.

The Prior Art

Containers used for cooking or heating food articles in the microwave

typically contain some type of lid or cover which may be used to cover the food

articles while they are being cooked or heated. Covered containers generally help the

food articles retain heat and moisture and may also help in the cooking process. The

container may be covered by transparent polymer film coverings or lids placed on top

of the container to retain moisture. However, upon removal of the film or lid, a great

deal of steam is often expelled in the user's face and this may lead to steam burns or

may even cause the user to drop the container.

Some containers are available with lids containing vents, which allow the

escape of steam and vapor from the container. However, prior art containers such as that disclosed in U.S. Patent Nos. 5,012,061 and 4,795,056 do not allow for the

controlled escape of steam and vapor since the vents are constantly open. The

uncovered vents also allow for the uncontrolled entrance of air within the container

which may affect the food articles.

Other container lids may include vents selectively covered by a cap member,

which therefore, allow for the controlled escape of steam and vapor from the

container. However, these container lids do not allow for any air to enter the

container once the steam and vapor have escaped. Therefore, a vacuum is created

within the sealed container which seals the cap member over the lid vent holes. Thus,

the difference in air pressure between the interior .and the exterior of the sealed

container may subsequently cause the lid to deform, unless the pressure is equalized.

It is important to note that prolonged deformation to the lid will likely decrease the

lifetime and the quality of the container lid. Therefore, it would be advantageous to

provide for a container and lid which allow for the controlled exit of steam and vapor

and the controlled entrance of air into the sealed container to equalize the pressure

between the interior and exterior of the container.

SUMMARY OF THE INVENTION

The present invention overcomes the deficiencies in existing microwave

container and lid assemblies by providing an improved lid. The lid includes a

controlled venting system and a controlled bleeder valve. The venting system is

disposed within the approximate center of the lid and includes at least one vent hole

and in the preferred embodiment a plurality of vent holes disposed within an approximate center of the lid. The vent holes are disposed within a recessed area within the approximate center of the lid. The vent holes are covered by a flexible

member secured to the lid through an aperture disposed within the approximate center

of the vent holes. The flexible member will selectively allow the vent holes to emit

steam or vapor from the container assembly when the pressure within the interior of

the container assembly exceeds the external pressure of the container assembly.

Therefore, the combination of the flexible member and the vent holes allow the

container assembly to be safely vented.

In addition, it is also advantageous for a container assembly to include

automatic means to equalize the pressure inside and outside the container after the

cooking or heating process. If after the cooking or heating process, the pressure

within the interior of the container assembly is lower than the container assembly

exterior, the lid will begin to deform in a generally inwardly direction such that it

becomes generally concave. The only way of preventing this deformation is to

equalize the pressure between the interior and the exterior of the container assembly.

As noted above during the cooking or heating process the equalization of pressure is

at least partially controlled by the flexible member when steam or vapor is emitted

from the container assembly. However, upon the completion of the cooking or

heating process, little if any additional steam or vapor will be emitted from the

container assembly. In addition, the flexible member is essentially disposed adjacent

to said lid such that liquid can not even escape from the lid of the container assembly.

However, if the pressure is not equalized between the interior and exterior of the

sealed container assembly, the lid will begin to deform in a generally inwardly

direction such that it becomes generally concave. Therefore, in addition to the

flexible member and vent holes the lid also includes automatic equalizing means such as a valve which allows for the intake of additional air to equalize the pressure

between the interior .and exterior of the container assembly, such that the lid will not

deform.

Accordingly, it is an objective of the present invention to provide a container

assembly having an improved venting system.

A further objective of the present invention is to provide a container assembly

for cooking and heating within the microwave oven.

A still further objective of the present invention is to provide a container

assembly having controlled venting which allows for the controlled venting of the

container interior when necessary, and shuts off automatically when the venting of the

container interior is no longer necessary.

Still a further objective is to provide an improved container assembly having a

venting valve which is capable of mounting to a container lid without attachment

hardware.

Another objective is to provide an improved container assembly having an

improved venting valve which is economically and readily produced and assembled.

A still further objective is to provided a container assembly having an

improved venting valve which allows for equalization of pressure between the interior

and exterior of the container assembly by allowing the escape and intake of air to the

container assembly.

These and other objectives, which will be apparent to those skilled in the art,

are achieved by a preferred embodiment which is described in detail below and which

is illustrated by the accompanying drawings. DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Fig. 1 is perspective view of the container assembly.

Fig. 2 is an exploded perspective view of the lid of the container assembly.

Fig. 3 is a top plan view of the lid of the container assembly and the flexible

member secured thereto.

Fig. 4 is a cross sectional view taken along line 4-4 of Fig. 3.

Fig. 5 is a cross sectional view taken along line 5-5 of Fig. 3.

Fig. 6 is a cross sectional view taken along line 6-6 of Fig. 3 illustrating the

slit opening in an open position.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the figures, Fig. 1 depicts a container assembly, namely a

container base 10 and a lid 12 and the lid 12 sealingly engaged to the container base

10. The lid 12 is molded of semi-rigid plastic such as linear low density polyethylene,

or other suitable plastic. As more clearly illustrated in Figs. 2-6, the lid 12 has an

exterior center wall 14 and an interior center wall 15. Fig. 2 illustrates an aperture 16

disposed within the approximate center of the lid 12 and extending therethrough. The

diameter of the aperture 16 may vary between 1/8 and 1 inch, however, in the

preferred embodiment the diameter of the aperture 16 is approximately 7/8 inches.

Vent holes 18 are oriented symmetrically around the lid aperture 16. The lid 12 may

contain any number of vent holes 18 however, the preferred embodiment of the lid 12

contains eight vent holes 18. The vent holes 18 may be of a variety of diameters, however, in the preferred embodiment the diameter of each of the vent holes 18 is

approximately 1/16 to 1/4 inches, and in the preferred embodiment 1/8 inch. The aperture 16 and vent holes 18 are generally confined within a recess 19, disposed

within the approximate center portion of the lid exterior wall 14, as illustrated in Fig.

2. In the preferred embodiment the diameter of the recess is approximately 1 to 2

inches, and in the preferred embodiment it is approximately 1 1/2 inches. The recess

19 is depressed approximately 1/16 to 1/4 inches within the lid 12, and in the

preferred embodiment the recess 19 is depressed approximately 1/8 inch within the lid

12, however, again the diameter of the recess 19 can vary depending upon the

diameter of the aperture 16 and the vent holes 18.

Figs. 1 & 2, illustrate the lid handles 21 for allowing the user to easily remove

the lid 12 from the container base 10. The container base 10 may also include handles

23 for allowing the user to easily carry the container base. The lid 12 and the

container base 10 may be of a variety of shapes or sizes, but they are sized to sealingly

engage with each other, such that the opening (not shown) of the container base 10

may be closed by the lid 12.

Figs. 1 & 2 also illustrate a flexible member 20, comprised of an elastic

material, the purpose of which is to selectively cover the aperture 16 and vent holes 18. Specifically, the flexible member 20 will allow vapor or steam to be emitted

through the vent holes 18 as the pressure within the interior of the sealed container

base 10 and lid 12 increases. The flexible member 20 consists of a circular disc

member 22 having a hollow bore member 24 extending in a generally downwardly

direction from approximately the center of the circular disc member 22. As illustrated

in Figs. 1, 3-6 the hollow bore member 24 may extend through the lid aperture 16 to

secure together the flexible member 20 and the lid 12, such that the circular disc

member 22 is at least partially confined within the recess 19. Generally, the circular disc member 22 will extend outward of the lid exterior wall 14 approximately 1/64 to

1/16 inches, .and in the preferred embodiment approximately 1/32 inches.

Figs. 4 & 5 illustrate the bore member 24 having a cylindrical portion 26

which has a relatively smaller diameter communicating with the lid interior sidewalls

27. The cylindrical portion 26 is itself defined by vertical side walls 28. The bore

member 24 also contains a lower end portion 30 which comprises a semi-spherical

outer surface which intersect in inwardly stepped shoulder 32. The shoulder 32 is

constructed to lie in a horizontal plane, approximately parallel to the lid interior wall

15. The shoulder 32 assists in retaining and securing the flexible member 20 within

the lid aperture 16.

The dimensions of the aperture 16 are slightly smaller than the corresponding

outer dimensions of the bore member 24 of the flexible member 20, such that the bore

member 24 can be pressure fitted through the aperture 16 and placed in a compressive

state. Once the flexible member 20 is received by the aperture 16 it is not possible for

the flexible member 20 to be unintentionally separated, as the shoulder 32 has a larger

diameter than the aperture 16 and therefore prevents the unintentional separation of

the lid 12 and the flexible member 20. The cylindrical portion vertical side walls 28 are tightly pressed against the interior lid sidewalls 27, and a liquid tight seal is

established between the surfaces 27 and 28.

A transverse slit 34 is formed to extend into the semi-spherical outer surface of

the lower end portion 30. In the normal position, the slit 34 is occupying the closed position as illustrated in Figs. 4 & 5. The slit 34 can also occupy an open position as

illustrated in Fig. 6. The slit 34 can selectively open depending upon the pressure

differential between the interior and the exterior of the sealed container base 10 and lid 12. Therefore, air can selectively pass downwardly through the hollow bore

member 24 and exit out of the slit 34 into the interior of the sealed container base 10

and lid 12, when the slit 34 is selectively open. If there is no pressure differential

between the interior and the exterior of the container base 10 and lid 12, the slit 34

will be selectively closed and air will not be allowed to enter the sealed container base

10 and lid 12.

It will be appreciated that the flexible member 20 may be comprised of a

variety of materials, but in the preferred embodiment it is comprised of silicone. The

flexible member 20 acts to establish a liquid tight seal with the lid exterior wall 14.

When there is no pressure differential between the interior and the exterior of the

sealed container base 10 and lid 12, the slit 34 is selectively closed such that air cannot pass through the bore member 24 and slit 34 into the sealed container base 10.

In addition, as mentioned previously the friction fit between the cylindrical portion

vertical side walls 28 and the interior lid sidewalls 27 prevents either liquid or air

from escaping or entering the sealed container base 10 and lid 12, along the outside of

the bore member. Thus, a liquid and air tight condition exists when the sealed

container base 10 and lid 12 are occupying a storage configuration.

Referring to Figs. 4-6, the operation of the container assembly in use will be

explained. The container assembly containing a food product may be placed into a

microwave oven. When a food product is positioned within the sealed container base

10 and lid 12 and exposed to microwave radiation within a microwave, liquid is

extracted from the food product and a vapor pressure is produced within the sealed

container base 10 and lid 12. As the sealed container base 10 and lid 12 continue to

be heated in the microwave oven, the pressure within the sealed container base 10 and lid 12 becomes greater than the atmosphere. As the pressure increases within the

sealed container base 10 and lid 12, the flexible member 20 will deform slightly

permitting steam or vapor from within the interior of the sealed container base 10 and

lid 12 to be emitted through one or more of the vent holes 18 as illustrated in Fig. 4.

The amount of steam and vapor which is released from the sealed container base 10

and lid 12 is determined by a variety of factors including: thickness and composition

of the flexible member 20; thermal expansion of the lid resin; and amount of steam

and vapor produced in the sealed container at a given time.

When the microwave oven is turned off, a semi-vacuum may be created within

the sealed container base 10 and lid 12 due to the differential in air pressure between

the interior and exterior of the sealed container base 10 and lid 12. The semi-vacuum

must be eliminated to prevent the lid 12 from deforming such that it is generally

concave in shape. Fig. 6 illustrates the slit 34, in reaction to the vacuum within the

sealed container base 10 and lid 12, opening a width "x", approximately 1/32 inches, a

sufficient opening to quickly admit air and equalize the air pressure. As the slit 34

widens, the sides of the lower portion 30 are pressed upward and compress against the

lid internal wall 15 which forces the slit 34 closed. The opening of the slit 34 occurs

automatically as air forces itself into the sealed container body 10 and lid 12 to

equalize the internal and external air pressures. It will be appreciated that the

compression of the shoulder 32 against the lid internal wall 15 stores the energy

necessary to bias the slit 34 closed again when the internal and external pressure is

equalized. Thus, the lower portion 30 of the bore member 24 acts as an automatic

shut off valve which opens automatically under appropriate conditions to admit air, and closes automatically when that condition has been eliminated. The valve works

by the inherent resiliency of the material of the flexible member 20.

With the slit 34 in the open condition, the air passing therethrough and into the

sealed container base 10 and lid 12 prevents any leakage of liquid through the slit 34.

The bore member 24 is compressed by the interior sidewalls 27 of the lid 12 such that

liquid cannot escape around the bore member 24. When the lower portion 30 relaxes,

the slit 34 closes to a gap sufficiently narrow to inhibit any liquid from making its

escape therethrough.

As noted in Fig. 6, the preferred radius "r" of the lower portion 30 is

approximately 3/16 to 7/16 inches. Also, it should be noted that the upper ends of the

slit 34 are located below the shoulder 32, by a distance of approximately 1/16 to 1/4

inches to allow the slot to open a width of approximately 1/16 to 1/64 inches and in

the preferred embodiment approximately 1/32 inches.

While the above describes the preferred embodiment of the subject invention,

the present invention is not intended to be so limited. Other embodiments, which will

be apparent to those skilled in the art and which utilize the teaching herein set forth

are intended to be within the scope and spirit of the subject invention.

Claims

CLAIMS:

1. A lid for enclosing an opening of a container body, said lid comprising: a center portion having at least one venting hole; a first member engaging said lid center portion for selectively covering said venting hole and selectively allowing vapor to escape said container body sealingly engaged with said lid, said first member further having valve means for selectively allowing air to enter said container body to equalize the air pressure between the inside and outside of said container body sealingly engaged with said lid.

2. A lid according to claim 1, wherein said center portion is slightly recessed and said first member is at least partially confined within said recess.

3. A lid according to claim 1, wherein said valve means is adapted to mount through an aperture in said lid center portion, said valve means having an upper portion adapted to extend through said lid aperture and a lower portion of substantially semi-spherical convex shape adapted to reside within said container body; a slit opening extending into said lower portion, said slit opening operating subject to the differential pressure between the inside and the outside of the container, said slit opening widening into an open condition when the differential is negative to admit air into said container body and said slit opening narrowing into a closed condition when the differential is positive, wherein said slit having a width sufficiently narrow to prevent the escape of liquid therethrough.

4. A lid according to claim 3, wherein said lower portion further comprising an annular shoulder positioned to engage against an internal surface portion of said lid forming a liquid tight seal.

5. A container assembly for use in a microwave oven comprising: a container body for containing a material to be heated, said container body having a side wall, a bottom portion .and an upper opening portion; a lid covering said upper opening portion, said lid further having at least one vent hole disposed within the approximate center of said lid; a flexible member secured to said lid for selectively allowing the escape of steam through said vent hole; said flexible member also having equalizing means, operating subject to the differential pressure between the interior and the exterior of said container assembly, for equalizing the air pressure inside and outside said container assembly.

6. A container assembly according to claim 5, wherein said equalizing means comprises a hollow bore member extending in a generally downwardly direction from said flexible member, said bore member including an upper portion retained within a lid aperture and a lower portion having a slit opening communicating with said upper portion.

7. A container assembly according to claim 5, wherein said flexible member is generally circular in shape.

8. A valve assembly for a lid for selectively controlling the pressure in a microwave container assembly, comprising: a generally circular shaped first member conforming to an exterior surface of said lid of said container assembly and a hollow bore member extending in a generally downwardly direction from an approximate center of said first member, said bore member adapted to mount through an aperture in said lid of said microwave container assembly; said first member for selectively allowing steam or vapor to escape said microwave container assembly through at least one vent hole in said lid; said bore member having an upper cylindrical smaller diameter portion and a semispherical lower portion, said semispherical lower portion having a slit opening operating subject to the differential pressure between the interior and the exterior of said container assembly.

9. A valve assembly according to claim 8, wherein said bore lower portion is further comprising a shoulder positioned to engage against an internal surface of said lid forming a liquid tight seal.

10. A valve assembly according to claim 9, wherein said shoulder is pressed against said lid internal surface by the opening of said slit, and which reacts to influence said slit closed upon elimination of air pressure differential between the interior and exterior of said container assembly.

11. A valve assembly for a lid for venting a microwave container assembly comprising: an upper portion adapted to conform to an external wall of said lid of said container assembly and adapted to selectively cover vent holes disposed in said lid; a lower portion integrally molded to said upper portion; said lower portion further comprising an intermediate portion adapted to extend through an aperture in said lid and a valve body containing a slit opening, said lower portion extending into an interior portion of said container assembly; said slit opening operating subject to the differential pressure between the inside and outside of the container, widening into an open condition when the differential is negative to admit air and the slit opening narrowing into a closed condition when the differential is positive, wherein said slit having a width sufficiently narrow to prevent escape of liquid therethrough.

12. A container assembly for use in heating food in a microwave oven, comprising: a container base having a food receiving cavity; a lid for sealingly engaging said container base; said lid having vapor escape passage means for causing vapor generated within food receiving cavity to be vented to the exterior of said lid; said lid further having pressure equalizing means for equalizing pressure between the interior and the exterior of said container assembly.

13. A container assembly for use in heating food in a microwave oven according to claim 12, wherein said vapor escape passage means further comprising at least one vent hole disposed within an approximate center of said lid and a valve member secured to said lid for selectively allowing the escape of vapor through said vent hole.

14. A container assembly for use in heating food in a microwave oven according to claim 13, said pressure equalizing means further comprising a slit disposed in said valve member for allowing air to enter said container assembly.

15. A container assembly for use in heating food in a microwave oven according to claim 13, said valve member further comprising both said vapor escape passage means and said pressure equalizing means.