WO2007078970A2

WO2007078970A2 - Sanitary door seal

Info

Publication number: WO2007078970A2
Application number: PCT/US2006/048688
Authority: WO
Inventors: Gary Dee Lang; Steven M. Mccarty
Original assignee: Praxair Technology, Inc.
Priority date: 2005-12-29
Filing date: 2006-12-20
Publication date: 2007-07-12
Also published as: US20070164043A1; WO2007078970A3; CA2634243A1

Abstract

A compressible gasket is mounted on retainers in the space between the surfaces of first and second structures such as an apparatus and a door. The gasket can move axially on the retainers and can pivot transversely on the retainers, thereby affording access to the spaces around and behind the gasket for easy cleaning and inspection.

Description

SANITARY DOOR SEAL

Field of the Invention

The present invention relates to apparatus for impeding the unwanted flow of gas between two surfaces such as a door and the structure to which the door is attached.

Background of the Invention In equipment that contains one or more openings between the interior and exterior of the equipment, it is frequently desired to provide doors or equivalent structure for removably covering the openings. It is also frequently desired to provide that when the door or. other structure is closed, the passage of gas is impeded in both directions between the interior and the exterior of the equipment . The gas whose passage is to be impeded (that is, completely prevented or at least retarded) can be the ambient atmosphere outside the equipment , or an atmosphere within the equipment that has a property different from the ambient atmosphere, such as a cold environment inside a refrigeration or freezing unit, a heated environment inside a heater or oven, and the like. Since the door or equivalent structure is usually impervious to gas flow through it, the attention to impeding gas flow is directed to the space between adjoining surfaces of the equipment and of the door. Familiar structures for impeding gas flow between such surfaces include weatherstripping for doors of buildings, flexible magnetically sealing gaskets around the doors of household refrigerators, and the like. A particularly sensitive need exists for providing satisfactory seals of this type in equipment that is used in the food industry, such as freezing and refrigeration equipment . The sealing must be capable of retaining as much as possible the cold atmosphere that is established inside such equipment, by impeding the escape of cryogenic refrigerant (such as cold nitrogen or carbon dioxide vapor) and impeding the infiltration of ambient air into the equipment . In addition, however, the apparatus that is to provide the desired sealing for equipment in the food industry should also permit direct, easy access to the sealing device and to the spaces and surfaces around it, for purposes of cleaning those spaces and surfaces and for purposes of inspection of the cleanliness of those spaces and surfaces . Devices that form enclosed regions or that present close clearances or corners and niches can trap material and resist cleaning and inspection, and should be avoided. Therefore a need remains in this field for closure systems that provide satisfactory sealing, that is, they impede passage of gas between the unit and the door, while also providing adequate access to all spaces and surfaces for purposes of cleaning and inspection.

BRIEF SUMMARY OF THE INVENTION

The present invention provides these and other features. It comprises a closure system comprising: (A) first structure comprising a first surface and second structure comprising a second surface, wherein said structures are movable with respect to

- o - each other between an open position and a closed position in which said first and second surfaces define a space therebetween through which passage of gas is to be impeded; (B) a gasket comprising first and second sections and being resiliently compressible, along an axis thereof between said sections, from a first position into and out of a compressed position in which said sections are closer to each other than when in said first position, there being at least one opening through said gasket ;

(C) at least one retainer attached to said first structure or to said second structure, provided that if there are two or more retainers then they are all attached to said first structure or all attached to said second structure, each retainer comprising a body portion which is attached at its base to said structure and which extends from its base through an opening through the gasket to a head large enough that it cannot pass through the opening, wherein the body portions are long enough and the openings are large enough that when the first and second structures are in an open position the gasket can move axially along the body portions and transversely with respect to the body portions, thereby permitting access to the space between the gasket and the surfaces of the structure to which the retainers are attached; and wherein said gasket is dimensioned and positioned such that when said structures are in said closed position, said first and second surfaces contact the first and second sections respectively of said gasket and compress said gasket, whereby passage of gas through said space between said surfaces is impeded.

In a preferred embodiment, the first structure has an opening therethrough and said first surface extends completely around said opening, and second structure comprising a second surface, such that when the first and second structures are in a closed position the respective first and second surfaces define a space therebetween extending completely around said opening and through which passage of gas is to be impeded.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a front view of equipment comprising one embodiment of the present invention. Figure 2 is a top cross-sectional view of the embodiment of Figure 1.

Figure 3 is the top cross-sectional view of the embodiment of Figure 2 but in which the door that is open in Figure 2 is closed. Figure 4 is a perspective view of a gasket and retainers useful in the present invention.

Figure 5 is a view of a retainer useful in the present invention.

Figure 6 is a top cross-sectional view of a portion of the embodiment of Figure 2.

Figure 7 is a top cross-sectional view of a portion of the embodiment of Figure 2.

DETAILED DESCRIPTION OF THE INVENTION The present invention is useful with any apparatus of the type that has two structural components, movable with respect to each other into and out of a relatively closed position such that when the components are considered to be closed, a surface of one of the structural components is in close proximity to a surface of the other structural component and the passage of gaseous atmosphere through the space between such two surfaces is to be impeded. A preferred example of such a situation is a refrigeration unit, in which a cold atmosphere is maintained inside the unit so as to cool or freeze products inside the apparatus. Such equipment will usually include one or more openings which are to be kept closed during operation, but which need to be opened from time to time to permit access to the interior of the unit . As indicated above, it is highly desirable to minimize or prevent the passage ambient air from the exterior into the interior of such units, and to minimize or prevent the passage of cold vapor from the interior of the unit to the exterior surroundings .

The accompanying drawings illustrate the applicability of the present invention to one type of apparatus, which can be thought of as being such a refrigeration or freezing unit. However, the exemplary description herein is not intended to limit that which is considered to be the closure system of the present invention.

Referring first to Figure 1, a portion of the exterior of a unit 1 is shown. Opening 2 through unit 1 permits access from the exterior of unit 1 into the interior of unit 1. Door 3 is provided which can be moved between an open position, shown in Figures 1 and 2, and a closed position shown in Figure 3. Door 3 is preferably attached to unit 1 by hinges 9. However, the benefits of the present invention can be realized in apparatus wherein the two structures represented here by unit 1 and door 3 are not necessarily attached to each other such as through a set of hinges. The invention is also useful with equipment in which a door, plug or hatch can be completely detached from a unit when not in the closed position.

In the terminology employed in this application, the unit 1 can be said to comprise the first structure, in which case door 3 comprises the second structure.

In a preferred embodiment, unit 1 is a refrigerator or freezer whose interior atmosphere is colder that the atmosphere outside door 3 when door 3 is closed.

In the apparatus illustrated in Figures 1, 2 and 3, there can be seen sets of adjoining surfaces between which the passage of gas is to be impeded when door 3 is in the closed position. For instance, when door 3 is closed, surface 4 of unit 1 and surface 5 of door 3, or at least those portions of surface 5 which are closer to the edges of the inside overall surface of door 3, define such a space. Likewise, surfaces 6 of unit 1 and edge 7 of door 3 define such a space when door 3 is closed.

Referring again to Figurel, two gaskets 11 are shown. The lengths of these gaskets 11 that are depicted are shorter than would be the case in preferred actual practice, in order to permit additional details of the structure depicted in Figure 1 to be shown more clearly. In preferred actual practice, as much as possible of the space through which the passage of gas is to be impeded should be occupied by a gasket 11. That is, in preferred actual practice, the vertical section of gasket 11 shown in Figure 1 should instead extend along the entire distance between the bottom surface 6 and top surface 6 along the vertical side of opening 2. Likewise, instead of the one short horizontal section of gasket 11 shown in Figure 1, it is preferred that gaskets 11 extend the entire horizontal extent along the top edge and the bottom edge of opening 2. In a typical preferred situation, when the said first and second surfaces of the first and second structures are in a closed position they define therebetween a space extending all the way around an opening in the first structure (such as the opening depicted in unit 1) , and a gasket as described here occupies all of that space all the way around the opening. In such a situation, there can be a gasket which is a single unitary piece, or there can be two or more gaskets which taken together occupy all of that space and better impede passage of gas through the space . Reference is now made to Figure 2, which is a cross-sectional view from above of the embodiment of Figure 1 taken along the line 2' -2" of Figure 1. Gaskets 11 are held by retainers 12 which in turn are attached to surfaces 6. Thus, it can be seen that in the embodiments of Figures 1-3, the gaskets 11 are employed to impede the flow of gas through the space that would be defined between surfaces 4 and 5 when door 3 is closed, as is seen in Figure 3.

Other features present in Figures 2 and 3 can also be seen in Figure 4, in which a gasket 11 is shown. Gasket 11 comprises a first section 16 and a second section 17 between which lies axis 18 along which gasket 11 is resiliently compressible. By "resiliently compressible" is meant that gasket 11 can be compressed from a first position {whether at rest, or already partially compressed) so that sections 16 and 17 are forced toward each other, and when such compressing force is removed then sections 16 and 17 rebound on their own to retake their first relative position. Gasket 11 should be made of any material which can be put through hundreds of cycles of such repeated compression and relief of compression without losing its ability to resiliently retake its uncompressed or less compressed position. The material of construction must also be capable of withstanding any conditions of temperature (and any corrosive environment if present) to which the gasket would be exposed when it is in place. For instance, if the environment on one side or the other of unit 1 is very hot or very cold, the preferred material of construction is a stainless steel sheet metal strip or a strip of other metal . The preferred material of construction is spring steel, more preferably spring stainless steel. High strength polymeric plastic may be suitable for some applications, but would likely not last as long as metal in applications that would expose the gasket regularly to temperatures above 100 F or below 32 F.

At least two openings 14 extend through each gasket 11 which is employed. If a given gasket is to be held in place by more than two retainers 12, each passing through its own opening 14, then the openings 14 should lie along one straight line so that the desired freedom of movement of gasket 11 can be maintained.

- a - Referring to Figures 4 and 5, each retainer 12 includes a base 16, which is affixed (such as by- welding) to one of the structures of the apparatus with which the closure system of the present invention is employed. Retainer 12 further includes a body portion 13, extending from the base 16 through an associated opening 14 to the other side of gasket 11 from the side that faces the surface where base 16 is attached. Retainer 12 further comprises a head 15 which is large enough so that it cannot pass through its associated opening 14. The retainers 12 , which can be seen in enlarged form in Figure 5, are preferably made of durable metal to facilitate their permanent attachment to a structure, to withstand the conditions to which the gasket 11 is to be exposed, and to permit the retainer to withstand repeated abutting and sliding contact with adjacent edges of the opening 14 in gasket 11.

Assembling the gasket 11 into its desired location with respect to the first and second structures as those terms are used herein begins with determining the appropriate location so that the gasket will be situated in the space through which the passage of gas is to be impeded when the first and second structures are closed. Then, a retainer 12 is passed through its associated opening 14 (one retainer for each opening) so that head 15 of retainer 12 is on one side of gasket 11 and body portion 13 extends through to the other side of gasket 11. Base 16 is then affixed to its desired location on the first or second structure.

Referring again to Figures 2 and 3, it can be seen that retainers 12 are affixed to respective surfaces 6,

- Q - so that the two gaskets 11 shown in Figures 2 and 3 are to impede the flow of gas through the space between surface 4 of unit 1 and surface 5 of door 3 when door 3 is in the closed position depicted in Figure 3. Thus, the point at which the bases 16 of retainers 12 are attached to surfaces 6 should be selected so that the second structure, in this case door 3, can close as desired without engaging retainer 12. Furthermore, the point of attachment and the dimensions of gasket 11 should be sufficient to provide that when door 3 is closed, section 16 of gasket 11 is compressed against surface 4 and section 17 of gasket 11 is compressed against surface 5. When these respective pairs of surfaces are in contact, the passage of gas through the space between surfaces 6 and 5 is impeded. Then, when door 3 is opened toward the position shown in Figure 2, the sections 16 and 17 of each gasket 11 are relieved from being so compressed. Optionally, additional seal- enhancing material 19, such as a strip of flexible polymeric foam or a bead of caulk, adhered to section 16 and/or 17 at the surface that is to contact the surfaces of the first and second structures when said structures are in said closed position (i.e. at the edges of sections 16 and/or 17) but not adherent to the surfaces of those structures, can be provided to enhance the impeding of the passage of gas between the gasket and the first and second structures. Alternatively, seal-enhancing material 19 can be adhered to the first and/or second surface of the first and/or second structures, at the locations to be contacted by the first and/or second sections of the gasket when the first and second structures are in said closed position, without being adherent to the gasket.

The closure system of the present invention, however, provides far more advantages than simply the ability to impede the passage of gas as indicated. The ability of the gasket to move with respect to its retainers enables the gasket to maintain the desired gas passage-impeding contact with the first and second structures even if the gasket moves for other reasons such as thermal expansion and contraction.

Another significant advantage is that when the system is in the open position, the gaskets and the spaces around them can easily be cleaned and can readily be inspected to confirm the cleanliness of the respective spaces and surfaces.

That is, referring first to Figure 4, each opening 14 and the body portions 13 of each retainer 12 should be dimensioned so that the gasket 11 can easily move axially, that is, up and down along body 13 in the orientation as shown in Figure 4. Thus, the open space of opening 14 around body portion 13 can be anywhere from 1% to 100% of the thickness of body portion 13 itself, so long as head 15 remains larger than opening 14 so that the gasket remains retained by retainers 12 and cannot slip off the far end of retainers 12.

Preferably, the length of body portion 13 along which the gasket 11 can move axially should be greater than the thickness of gasket 11 itself at opening 14, preferably anywhere from 1.5 to 100 times the thickness of gasket 11.

Referring next to Figures 6 and 7, a representative gasket 11 and retainer 12 are depicted

- n - along with the space 20 that is between gasket 11 and the structure (in this case, the body of unit 1) to which retainer 12 is attached. It can be seen that gasket 11 is movable transversely with respect to retainer 12, that is, retainer 11 can pivot through an arc about the head 15 as indicated by the arrows in Figure 6. Moving gasket 11 transversely in this manner permits easier access to space 20, even that portion of space 20 that occupies the indicated corner shown in Figures 6 and 7.

Attaining the desired ability for gasket 11 to move transversely with respect to retainer 12 requires only making each opening 14 sufficiently larger than the body portion 13 of the retainer 12 that the gasket 11 can be moved without the opening 14 pinching or binding on retainer 12, and by attaching retainer 12 to the associated structure on a surface not so close to a corner that full range of motion of gasket 11 is prevented. The area or gap within opening 14 around body portion 13 has an additional advantage, besides permitting movement of gasket 11 axially and transversely with the respect to retainer 12. That gap and the resulting loose fit of opening 14 around retainer 12 also facilitates cleaning and inspection of opening 14 itself to ensure that no food material or other undesired substance becomes trapped in that opening .

Thus, it can be seen that the advantageous features of sealing against the undesired passage of gas, combined with easy cleanability and ease of inspection, can be provided very easily and

- i 2 - economically. The system requires only inexpensive materials of construction (namely, the stainless steel strip or equivalent material, and the small metal tabs that can be employed as the retainers) . The system can be installed easily in the manufacture of new equipment and can be attached easily onto existing equipment with minimal effort, minimal cost and minimal downtime of operation of the associated equipment.

_ T -5 _

Claims

WHAT IS CLAIMED IS:

1. A closure system comprising:

(A) first structure comprising a first surface and second structure comprising a second surface, wherein said structures are movable with respect to each other between an open position and a closed position in which said first and second surfaces define a space therebetween through which passage of gas is to be impeded;

(B) a gasket comprising first and second sections and being resiliently compressible, along an axis thereof between said sections, from a first position into and out of a compressed position in which said sections are closer to each other than when in said first position, there being at least one opening through said gasket ;

(C) at least one retainer attached to said first structure or to said second structure, provided that if there are two or more retainers then they are all attached to said first structure or all attached to said second structure, each retainer comprising a body portion which is attached at its base to said structure and which extends from its base through an opening through the gasket to a head large enough that it cannot pass through the opening, wherein the body portions are long enough and the openings are large enough that when the first and second structures are in an open position the gasket can move axially along the body portions and transversely with respect to the body portions, thereby permitting access to the space between the gasket and the surfaces of the structure to which the retainers are attached; and wherein said gasket is dimensioned and positioned such that when said structures are in said closed position, said first and second surfaces contact the first and second sections respectively of said gasket and compress said gasket , whereby passage of gas through said space between said surfaces is impeded.

2. A closure system according to claim 1 wherein the gasket is made of spring steel .

3. A closure system according to claim 1 wherein the gasket is made of spring stainless steel .

4. A closure system according to claim 1 wherein said gasket has two or more retainers passing therethrough.

5. A closure system according to claim 1 further comprising seal-enhancing material adhered to the first, second, or both sections of said gasket that contacts, but is not adherent to, said first or second structure when said structures are in said closed position.

6. A closure system according to claim 1 further comprising seal-enhancing material adhered to said first or second structure that contacts, but is not adherent to, said first, second, or both sections of said gasket when said structures are in said closed position.

7. A closure system according to claim 1 wherein the first structure includes an opening therethrough and the first surface extends completely around said opening such that in the closed position, the first and second surfaces define a space therebetween extending completely around said opening and through which passage of gas is to be impeded.

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