The present invention relates to railroad freight cars and in particular to one or more thermal insulating members for railway boxcars and a method for retrofitting a boxcar to be thermally insulated.
Existing boxcars typically include opposed side walls, opposed end walls, a floor, a roof, and at least one doorway together defining a cargo-carrying enclosure that is mounted upon a supporting undercarriage with a wheel assembly for movement upon a railroad track. Though early railway boxcars comprised simple wooden structures mounted on a platform, modern railway boxcars are built from materials that are both more sturdy and more durable so that they may carry loads far more heavy than what an early wooden boxcar could carry. For example, a typical modern boxcar will include a supporting undercarriage having a longitudinal center sill, body bolsters, side sills, cross bearers, and cross ties that are each made of iron, steel, or other rigid metal. This undercarriage may then support the side walls, end walls, and roof, which are also typically of metal construction.
Though the modern boxcar construction just described is adequate to transport heavy loads, such boxcars are often insufficient to transport over large distances perishable cargo or other cargo that must be maintained at a low temperature. One existing solution is to construct an insulated boxcar that is capable of maintaining the interior temperature of the boxcar enclosure at a desired level by preventing heat from entering the enclosure. Various types of insulated railway boxcars are presently manufactured and used. A typical insulated railway boxcar includes an enclosed structure having an outer surface, typically of metal or fiber-reinforced composite material, one or more layers of foam or fiber insulation, and an interior surface of fiber-reinforced composite material.
One problem with these existing insulated boxcars is that the floor of the insulated enclosure must be able to withstand without deformation, significant loading both from the cargo carried by the boxcar and the concentrated weight of forklifts or other machinery used to load and unload cargo from the boxcar. Additionally, the sides of the boxcar enclosure must have sufficient strength to withstand the impacts of loads shifting during transport and thereby battering the interior surface of the boxcar enclosure. The fiber reinforced composite material, however, does not have the strength of steel, and thus insulated boxcar enclosures are typically fabricated with thicker floors, end walls, and side walls to better withstand the forces encountered during transport of cargo. Because the exterior dimensions of the boxcar must fit within the assorted plate requirements of the American Association of Railroads (AAR), however, this extra thickness reduces the interior dimensions of the cargo-carrying enclosure of the boxcar, hence decreases the load-carrying capacity of the boxcar.
An alternative to an insulated boxcar is a refrigerated boxcar that uses a refrigeration unit to maintain the interior of the cargo-carrying enclosure at a desired temperature. These refrigeration units are costly to install, and unless used in combination with an existing insulated boxcar with the aforementioned disadvantages, are costly to operate due to the transfer of heat into the interior of the cargo-carrying enclosure.
What is desired, therefore, is an improved structure for insulating the interior of a boxcar cargo-carrying enclosure.
The aforementioned disadvantages of existing boxcars are addressed by a boxcar having at least one insulative panel on the exterior of the boxcar. An existing, non-insulated boxcar may be converted to an insulated boxcar by attaching at least one insulative panel to its exterior.
A first embodiment of the disclosed invention may include an insulated boxcar having a side wall with an outwardly directed surface. At least one thermally insulating member is positioned proximate the outwardly directed surface. In one aspect of this embodiment, a side post may stand proud of the side wall and the thermally insulating member may define a recessed portion that engages with the side post. The thermally insulating member may also include an outer skin spaced apart from the inner skin, and insulating material such as insulating foam may occupy the intervening space between the inner and outer skins of the thermally insulating member.
The thermally insulating member may be affixed to the outwardly directed surface of the side wall or end wall in any convenient manner, such as with an adhesive, a bolt, stud, or other fastener. If further insulation is desired, panels may be positioned proximate the roof of the rail car and/or foam insulation may be affixed to the undercarriage of the boxcar.
A second embodiment of the disclosed invention includes an insulative panel attachable to the exterior surface of a boxcar. When the boxcar includes a side post standing proud of the exterior surface, the panel may define a recessed portion engageable with the side post. The panel may comprise inner and outer skins of rigid material, spaced apart from each other with insulating material positioned in the intervening gap.
A third embodiment of the disclosed invention is a method of retrofitting an existing non-insulated boxcar to convert it into an insulated boxcar. The disclosed method includes the step of affixing a thermally insulative panel to an outwardly directed surface of the boxcar.
The side walls 14, end walls 16, and roof 20 of the exemplary boxcar 10 may define an exterior, outwardly facing surface 13 of the boxcar 10 through which a great deal of heat would normally enter during transport of cargo. To insulate the exemplary boxcar 10, and thereby reduce the amount of heat passing through the surface 13, thermally insulative panels 12 may be positioned proximate the exterior, outwardly facing surface 13. The panels 12 may be of a relatively thin construction that does not significantly add to the cross sectional profile of boxcar 10 as it travels over a railroad track.
An exemplary boxcar 10 insulated by the panels 12 has several advantages over existing insulated boxcars. First, because the panels 12 may be of a relatively thin construction, the cargo-carrying capacity of the boxcar enclosure is not reduced, as is true with existing insulated boxcars which rely upon necessarily thick insulated side walls, end walls, roof, etc. to provide the desired insulation. Second, the load-bearing structure of the exemplary boxcar 10 may be of any desired construction, hence a manufacturer need not significantly change its production process to make an insulated boxcar in accordance with the present disclosure.
Also, as can easily be appreciated, the panels 12 provide a simple, cost effective method of retrofitting an existing, non-insulated boxcar into an insulated boxcar by fastening the panels 12 to the exterior surfaces of the side walls 14, end walls 18, and roof 20 of the existing, non-insulated boxcar. For purposes of this disclosure, the exemplary boxcar 10 will be described as such a retrofitted boxcar, although it should be understood that the boxcar 10 could be initially constructed as the disclosed insulated boxcar 10 by including the disclosed panels 12 proximate the outwardly facing surface 13.
Conceivably, each of the panels 12 could be of a size and shape that conforms to that of an entire section of the boxcar 10; i.e., a panel 12 could have outer dimensions that match those of the roof 20, or a end wall 18, or a side wall 14 with an opening sized to match a doorway 21. Preferably, however, each panel 12 is quite a bit smaller than each of the roof 20, the end walls 18, and the side walls 14. Panels 12 of such a relatively small size will facilitate the easy placement of each panel 12 on the outwardly directed surface 13 of the boxcar. Thus each of the panels 12 placed over the side walls 14 of the exemplary box car 10 may have a length that extends approximately from one end of the boxcar 12 to the doorway 21 and a width that extends approximately one fourth of the height of a respective side wall 14. The panels 12 placed over the end walls 18 and the roof 20 may have a length that conforms to the width of a respective end wall 18 and the roof 20, and a width that also extends approximately one fourth of the height of a respective side wall 14. If the height of the boxcar 10 is not an integer multiple of the width of a panel 12, as shown in
Each panel 12 is preferably a thermally insulating member placed proximate a respective portion of the outwardly facing surface 13 of the boxcar 10. The composition and structure of each panel 12 is preferably chosen to achieve a desired amount of thermal insulation. For example, referring to
The boxcar 10 may include a four-inch thick piece of polyurethane foam insulation as the insulative material 28 positioned between the inner skin 24 and the outer skin 26. Alternatively, the insulative material 28 may be any other desired material such as a resin-impregnated foam core matrix or even air. Further, the panels 12 may either comprise an outer rigid skin that retains the insulative material in a position proximate or adjacent the outer surface 13 of the boxcar 10, avoiding the need for an inner skin 24, or may simply comprise a thermally insulating layer of fiber-reinforced composite material or any other desired insulating material of a chosen thickness.
Typically, boxcars will include a number of side posts 22 that support, and usually stand proud of the exterior of, the side walls 14. Accordingly, and in order to insulate as much of the exterior of the boxcar 10 as feasible, the first skin 24 of the panel 12 may define a recessed portion 30 shaped to engage a side post 22 standing proud of a side wall 14. That is to say, where a boxcar 10 includes a side post 22 that extends outwardly from a side wall such that the side post has a lateral surface 23 extending substantially normal to the side wall 14, a panel 12 may preferably include an inner skin 24 shaped to define a recessed portion 30 with a surface that is proximate to the lateral surface 23 of the post when the panel 12 is positioned over the side post 22.
Each of the panels 12, if desired, may also be securely fastened to the exterior of the boxcar 10 by attachment of the panel 12 to the side post 22. For example, a threaded stud 34 may be welded to a chosen side post 22. A panel 12 to be secured to the post 22 may define a mating opening 34a by which the panel 12 may fit over the stud 34 to a position proximate the post 22. A nut 36 may then be engaged with the stud 34, thereby securing the panel 12 to the exterior of the box car 10. A washer 35 or other similar member may be used to distribute the force that the nut 36 exerts on the panel 12 over a larger area. To facilitate attachment of a panel 12 to a side post 22 with the stud 34 and the nut 36, the second skin 26 may also define a cavity 32 into which the nut 36 may be recessed, and the cavity 32 optionally covered with a removable plug 37. Alternatively, the panels 12 may be secured directly to the side walls 14 and/or the posts 22 with a desired adhesive material.
The panels 12 of the exemplary boxcar 10 shown in
Referring to
Referring again to
Once the panels 12 have been secured to the side walls 14, the roof 20, and the end walls 18, angled corner closures 74 may be placed over the corners defined by the respective adjacent panels 12 of the end walls 18 and the side walls 14. Similarly, doorway closures 76 and roof closures 78 may be placed over the corners defined by the adjacent panels 12 of the doorways 21 and side walls 14, and by the roof 20 and the sidewalls 14, respectively. The corner closures 74, the doorway closures 76, and the roof closures 78 may be of steel sheet or other suitable construction.
To provide thermal insulation to the boxcar 10 beyond that provided by the panels 12, it may often be desirable to insulate the undercarriage 15 of the boxcar 10. The boxcar 10 may have an undercarriage 15 of any desired load-bearing construction capable of supporting and carrying heavy loads across large distances, but preferably includes a load-supporting structure of steel, iron, or other such high-strength material. Referring to
If it desired to insulate the undercarriage 15 of the boxcar 10, insulative foam, the boundaries of which are shown by the dashed line 67 in
Once the mold is in place, liquid foam such as polyurethane foam may be blown in to cure in place beneath and adhere to the undercarriage approximately to the outermost longitudinal stringers 64. At that point, panel extensions 82, of 16 gauge steel for example, may be secured to the outer skin 26 of the lowermost panels 12 on the side walls 14 that each extend downwardly and around the undercarriage. As seen in
The boxcar 10 may include a doorway 21 within which a plug-type door (not shown) may fit. Typically, these doors are manufactured with insulative material inside them, hence the disclosed exemplary boxcar 10 need not include any panels 12 on either the interior or exterior of the plug-type door. In some instances, however, it may be appropriate to place the panels 12 over the outside of the door, assuming there is sufficient clearance within the appropriate plate requirements of the AAR. Alternatively, such panels 12 may be placed on the inside of the plug-type door assuming that the panels 12 are sufficiently thin to allow the door to clear the doorway and adjacent panels 12 when opened and then slide along the door track 21a shown in
An exemplary boxcar 10 will typically include a number of safety appliances, such as the ladder 38 and the brake operation hand wheel 40, attached to the exterior of the boxcar 10. When retrofitting an existing boxcar to become an insulated boxcar, as described in this disclosure, it may be difficult to remove the safety appliances, attach the panels 12 to the outwardly facing surface 13, and reattach the safety appliances. Therefore, it may be appropriate to divide the affected panels 12 into two pieces, inserting them separately around the safety appliances. Referring to
Referring to
The present inventors discovered that an undesirable amount of heat may pass through the doorway header 100 of the insulated boxcar 10. Furthermore, because of the narrow width dimension of the doorway header 100, it is impractical to cover the exterior of the doorway header 100 with a disclosed insulative panel 12. Accordingly, if it is desired to further reduce the flow of heat into or out of the boxcar 10, a thermally insulative backer 110 may be preferably positioned behind the doorway header 100, providing additional insulation for the boxcar 10 beyond that provided by the insulative panels 12. Preferably the insulative backer 110 has a thickness less than two inches, and more preferably a thickness of one and a half inches.
In a preferred embodiment, the insulative backer 110 comprises a rigid block of hardened polyurethane foam cut to appropriate dimensions that correspond to those of the doorway header 100. The rear portion of the insulative backer 110 optionally may be reinforced by a cover plate 112 and secured to the doorway header 100 with a stud 114 that extends from the cover plate 114 to the doorway header 100. If used, the cover plate 114 may be welded or secured by other means to the top chord 108 and/or the doorway reinforcement 106. In alternative embodiments, the insulative backer 110 may either comprise a fiber-reinforced composite material, foam insulation blown into the space between the insulative backer 110 and the cover plate 114 or other such member, or any other desired insulative material.
During transport, it is frequently desirable to restrain cargo in a boxcar to prevent the cargo from shifting or toppling as the boxcar moves. Typically, ropes, cables, or other such tension members are used for this purpose, where the ends of the tension member terminate in a specially shaped adapter, or floor anchor, that each fit within a one of a plurality of matching apertures spaced at intervals along the outer sides of the floor of the boxcar. The present inventors, however, realized that the apertures in the floor may allow water or other moisture to drain into the undercarriage of the boxcar when, for example, the interior of the boxcar is washed. The water then undesirably soaks the insulation in the undercarriage, diminishing its effectiveness and durability.
Referring to
Preferably, the apertures 122 are shaped to matingly receive and retain a chain inserted into the aperture. For example, tension in a chain inserted into either of the apertures 122 shown in
Although the anchor apertures 122 shown in
In a preferred embodiment, each side wall of the boxcar 10 includes at least one aperture 122 such that the boxcar 110 has at least one aligned pair of apertures laterally opposed to each other to facilitate securing a chain or other tension member to either side of cargo carried within the boxcar 110. Where a boxcar 10 includes more than one such pair, such laterally aligned pairs may be vertically stacked in a column, one side of which is as shown in
Referring to
Although the disclosure herein, except where otherwise noted, describes an example of retrofitting an existing, non-insulated boxcar 10 into an insulated boxcar, configurations identical to those disclosed, and the variations thereof, may be easily incorporated into the production design of an insulated boxcar. It should be further understood that, given the wide variety of existing boxcar structures, the foregoing disclosure of the structure of the exemplary boxcar 10 is given solely for the purpose of understanding the disclosed invention, and the structural configuration of the exemplary boxcar 10 is not intended as a limitation on the disclosed invention.
The terms and expressions that have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only the claims that follow.
The present application claims the benefit, under 35 U.S.C. § 119(e), of prior provisional application No. 60/613,342 filed Sep. 27, 2004 and prior provisional application No. 60/651,296 filed Feb. 9, 2005.
Number | Date | Country | |
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60613342 | Sep 2004 | US | |
60651296 | Feb 2005 | US |