Insulated cargo container doors
The prevention discloses an insulated door for a cargo container, and in particular, a boxcar. In one implementation, the door is a double plug door, wherein each door has an insulating layer and a skin on the insulating door. Each door also has a projection designed to overlap with a projection on the other door. A sealing member is also included on one of the doors. When the double plug door of the invention is closed, the only contact between the doors in the area of the projections is between the skin of one door and the skin or sealing member of the second door. This improves the thermal efficiency of the doors.
This application claims the benefit of U.S. Provisional Application No. 60/616,621, filed Oct. 8, 2004, by Joseph A. Seiter and titled Door Seal for an Insulated Railroad Car, the disclosure of which is expressly incorporated herein by reference.
II. BACKGROUNDA. Technical Field
The present invention relates to a door and a door seal for an insulated cargo container. In one embodiment, the door and door seal are for an insulated railroad boxcar.
B. Related Art
Currently, many shippers utilize insulated or refrigerated large cargo containers (such as boxcars) to transport items that require the maintenance of specified temperatures during transit. Because these containers are required to maintain certain temperatures, the thermal efficiency of these containers is an important feature. Thermal efficiency is characterized by the thermal conductivity of a particular component or its inverse, its resistance to heat transfer commonly referred to as an R value.
One area of heat loss in these containers is in the area of the door. Cargo container doors come in various types including sliding and plug doors. Sliding doors are opened and closed by sliding the door along tracks. Plug doors are similar to sliding doors, however, they are designed to close with a final inward movement that positions (or “plugs”) the interior of the door flush with the interior of the car. This flush feature increases the uninterrupted wall space of the car, and facilitates the use of insulation in the door. Plug doors typically have a gasket similar to a refrigerator door so that, when closed, the door seal is water and light resistant.
In the past, cargo container doors were typically constructed of a combination of wood and metal members. Because members of this type typically possessed a low R-value, insulation, such as foam insulation, was often installed in these cargo container doors to increase their thermal efficiency. Even with the use of insulation, however, the thermal efficiency of cargo container doors of this type has not been as high as desired by users of these cargo containers.
In addition, in plug doors, the door seal itself affects the thermal efficiency of the door. In the past, the seal has often acted as a thermal short circuit. A thermal short circuit is an area where heat is able to bypass insulation and therefore more easily transfer through the door. This results in a loss of thermal efficiency.
Therefore, there is a need for a cargo container door constructed to improve thermal efficiency and that also removes potential thermal short circuits. The present invention provides a cargo container door that meets these needs.
II. SUMMARY OF THE INVENTIONApparatus consistent with one embodiment of the present invention provide a cargo container comprising an enclosure for transporting cargo, the enclosure comprising an opening to provide access to the enclosure, a first plug door, and a second plug door. The first plug door includes a first insulating layer; a first skin on a face of the first insulating layer; and a first projection. The second plug door includes a second insulating layer; a second skin on a face of the second insulating layer; a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection. When the first plug door and the second plug door are in a closed configuration, the only contact between the first plug door and the second plug door in the area of the first and second projections is between the first skin and the second skin or the sealing member.
Apparatus consistent with another embodiment of the present invention provide a cargo container comprising an enclosure for transporting cargo, the enclosure comprising an opening to provide access to the enclosure, a first plug door, and a second plug door. The first plug door includes a first insulating layer; a first outer skin on an outer surface of the first insulating layer; and a first inner skin on an inner surface of the first insulating layer, wherein the inner skin includes a projection. The second plug door includes a second insulating layer; a second outer skin on an outer surface of the second insulating layer; and a second inner skin on an inner surface of the second insulating layer; wherein the second insulating layer, second outer skin, and second inner skin include a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection. When the first plug door and the second plug door are in a closed configuration, the only contact between the first plug door and the second plug door in the area of the first and second projections is between the first inner skin and the second inner skin of the second plug door or the sealing member.
Apparatus consistent with another embodiment of the present invention provide a cargo container comprising an enclosure for transporting cargo, the enclosure comprising an opening to provide access to the enclosure, the opening having a door jamb on its perimiter, and a plug door. The doorjamb includes a first insulating layer; a first skin on a face of the first insulating layer; and a first projection. The plug door includes a second insulating layer; a second skin on a face of the second insulating layer; a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection. When the plug door is in a closed configuration, the only contact between the plug door and the door jamb in the area of the first and second projections is between the first skin and the second skin or the sealing member.
Apparatus consistent with another embodiment of the present invention provide a cargo container comprising an enclosure for transporting cargo, the enclosure comprising an opening to provide access to the enclosure, the opening having a door jamb on its perimiter, and a plug door. The doorjamb includes a first insulating layer; a first outer skin on an outer surface of the first insulating layer; and a first inner skin on an inner surface of the first insulating layer, wherein the inner skin includes a projection. The plug door includes a second insulating layer; a second outer skin on an outer surface of the second insulating layer; and a second inner skin on an inner surface of the second insulating layer; wherein the second insulating layer, second outer skin, and second inner skin include a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection. When the plug door is in the closed configuration, the only contact between the plug door and the door jamb in the area of the first and second projections is between the first inner skin and the second inner skin of the second plug door or the sealing member.
Apparatus consistent with another embodiment of the present invention provide a double plug door for a cargo container. The double plug door includes a first plug door and a second plug door. The first plug door includes a first insulating layer; a first skin on a face of the first insulating layer; and a first projection; and a second plug door comprising: a second insulating layer; a second skin on a face of the second insulating layer; a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection. When the first and second projections overlap, the only contact between the first plug door and the second plug door in the area of the first and second projections is between the first skin and the second skin or the sealing member.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.
III. BRIEF DESCRIPTION OF THE DRAWINGS
A. Introduction
As described below, apparatus consistent with the present invention will now be described with respect to one embodiment of an insulated door for a cargo container: an insulated double plug door for a boxcar. The invention as claimed, however, is broader than insulated double plug doors for boxcars and extends to other plug doors for boxcars, such as single plug doors for boxcars. In addition, the invention as claimed is broader than insulated doors for boxcars and extends to insulated doors for other large insulated cargo containers, such as, shipping containers used on seagoing container vessels, truck trailers, straight trucks, refrigerated buildings, or the like.
B. Apparatus
Doors 24 and 25 may be constructed entirely of metal, or a combination of metal and composites. Composites are materials made up of a combination of different materials, typically some combination of metals, plastics, and/or ceramics. In one implementation, doors 24 and 25 are constructed of an outer skin 33 and an inner skin 26 (not shown in
Outer skin 33 and inner skin 26 are constructed of sheet metal, such as galvanized steel, aluminum, stainless steel, coated sheet metal, or fiber-reinforced plastics, or some combination of these materials. In addition, outer skin 33 and inner skin 26 may be constructed to be dent resistant, corrosion resistant, or puncture resistant using the materials described above, as is well known in the art. Also, outer skin 33 and inner skin 26 need not be constructed of the same materials and may have differing mechanical properties. For example, in one implementation, inner skin 26 will be constructed of fiber reinforced plastics, while outer skin 33 will be constructed of galvanized steel. These implementations are merely exemplary, and other implementations may also be used.
Insulating layer 28 may be constructed from any insulating material that will increase the thermal efficiency of doors 24 and 25. In one implementation, insulating layer 28 comprises a closed-cell polymer foam, such as urethane. In another implementation, insulating layer 28 comprises a vacuum insulated panel. Vacuum insulated panels are constructed of an intermediate film or laminate providing a barrier to passage of air into an interior porous insulating material that has been evacuated to increase its insulating value. In one implementation, the interior porous insulating material comprises a micro-cellular open-cell foam core material. In one implementation, the diameter of the cells is on the order of 10−6 in. A one inch thick sheet of such a material may have a R-value (evacuated) of approximately 28. A micro-cellular, open-cell polystyrene foam, such as Instill™ available from Dow Chemicals may be used in such an implementation. In yet another implementation, the porous insulating material is a fine fiberglass web core material. In one implementation, each fine fiberglass strand will have a diameter of approximately 0.001 in. A one inch thick sheet of such a material may have a R-value (evacuated) of approximately 40. A fine fiberglass web core material such as Threshold™ available from Thermal Visions may be used in such an implementation. In another implementation, insulating layer 28 comprises a combination of foam and vacuum insulated panels. These implementations are merely exemplary, and other implementations may be used.
As described above, doors 24 and 25 are closed by first sliding the doors towards one another. Doors 24 and 25 are then fully closed by a final inward movement. In the case of double plug doors, such as doors 24 and 25, the doors typically include a joint at the point where the doors intersect with one another when closed. Typically, the joint is designed to create a seal when the doors are closed. In the present invention, the joint of doors 24 and 25 is designed to improve the thermal efficiency of doors 24 and 25.
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Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
Claims
1. A cargo container comprising:
- an enclosure for transporting cargo, the enclosure comprising an opening to provide access to the enclosure;
- a first plug door comprising: a first insulating layer; a first skin on a face of the first insulating layer; and a first projection; and
- a second plug door comprising: a second insulating layer; a second skin on a face of the second insulating layer; a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection;
- wherein when the first plug door and the second plug door are in a closed configuration, the only contact between the first plug door and the second plug door in the area of the first and second projections is between the first skin and the second skin or the sealing member.
2. The cargo container of claim 1, wherein the first and second skins comprise fiber-reinforced plastics.
3. The cargo container of claim 1, wherein the first and second insulating layers comprise urethane foam.
4. The cargo container of claim 1, wherein the the first and second insulating layers comprise a vacuum insulated panel.
5. A cargo container comprising:
- an enclosure for transporting cargo, the enclosure comprising an opening to provide access to the enclosure;
- a first plug door comprising: a first insulating layer; a first outer skin on an outer surface of the first insulating layer; and a first inner skin on an inner surface of the first insulating layer, wherein the inner skin includes a projection; and
- a second plug door comprising: a second insulating layer; a second outer skin on an outer surface of the second insulating layer; and a second inner skin on an inner surface of the second insulating layer; wherein the second insulating layer, second outer skin, and second inner skin include a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection;
- wherein when the first plug door and the second plug door are in a closed configuration, the only contact between the first plug door and the second plug door in the area of the first and second projections is between the first inner skin and the second inner skin of the second plug door or the sealing member.
6. The cargo container of claim 5, wherein the first and second inner skins comprise fiber-reinforced plastics.
7. The cargo container of claim 5, wherein the first and second insulating layers comprise urethane foam.
8. The cargo container of claim 5, wherein the the first and second insulating layers comprise a vacuum insulated panel.
9. A cargo container comprising:
- an enclosure for transporting cargo, the enclosure comprising an opening to provide access to the enclosure, the opening having a doorjamb on its perimiter, wherein the doorjamb includes: a first insulating layer; a first skin on a face of the first insulating layer; and a first projection; and
- a plug door comprising: a second insulating layer; a second skin on a face of the second insulating layer; a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection;
- wherein when the plug door is in a closed configuration, the only contact between the plug door and the door jamb in the area of the first and second projections is between the first skin and the second skin or the sealing member.
10. The cargo container of claim 9, wherein the first and second skins comprise fiber-reinforced plastics.
11. The cargo container of claim 9, wherein the first and second insulating layers comprise urethane foam.
12. The cargo container of claim 9, wherein the the first and second insulating layers comprise a vacuum insulated panel.
13. A cargo container comprising:
- an enclosure for transporting cargo, the enclosure comprising an opening to provide access to the enclosure, the opening having a doorjamb on its perimiter, wherein the doorjamb includes: a first insulating layer; a first outer skin on an outer surface of the first insulating layer; and a first inner skin on an inner surface of the first insulating layer, wherein the inner skin includes a projection; and
- a plug door comprising: a second insulating layer; a second outer skin on an outer surface of the second insulating layer; and a second inner skin on an inner surface of the second insulating layer; wherein the second insulating layer, second outer skin, and second inner skin include a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection;
- wherein when the plug door is in the closed configuration, the only contact between the plug door and the door jamb in the area of the first and second projections is between the first inner skin and the second inner skin of the second plug door or the sealing member.
14. The cargo container of claim 13, wherein the first and second inner skins comprise fiber-reinforced plastics.
15. The cargo container of claim 13, wherein the first and second insulating layers comprise urethane foam.
16. The cargo container of claim 13, wherein the the first and second insulating layers comprise a vacuum insulated panel.
17. A double plug door for a cargo container comprising:
- a first plug door comprising: a first insulating layer; a first skin on a face of the first insulating layer; and a first projection; and
- a second plug door comprising: a second insulating layer; a second skin on a face of the second insulating layer; a second projection designed to overlap with the first projection; and a sealing member disposed on the second projection;
- wherein when the first and second projections overlap, the only contact between the first plug door and the second plug door in the area of the first and second projections is between the first skin and the second skin or the sealing member.
18. The cargo container of claim 17, wherein the first and second skins comprise fiber-reinforced plastics.
19. The cargo container of claim 17, wherein the first and second insulating layers comprise urethane foam.
20. The cargo container of claim 17, wherein the the first and second insulating layers comprise a vacuum insulated panel.
Type: Application
Filed: Oct 11, 2005
Publication Date: May 25, 2006
Inventor: Joseph Seiter (Raleigh, NC)
Application Number: 11/246,221
International Classification: B65D 88/00 (20060101);