Double skin slat construction for trailers

An improved slat construction (20) for use in a livestock trailer (22) includes a double skin slat (24) connected to upright posts (38) of the trailer (22) with weld connections (68). The slat (24) includes an inner skin (26), an outer skin (28), a plurality of bulkheads (30), and female and male edge connections (32, 34). The inner and outer skins (26, 28) are spaced apart to define a gap (62) therebetween, and the bulkheads (30) are positioned in the gap (62) and connect to the inner and outer skins (26, 28) to divide the gap (62) into internal chambers which inhibit heat transfer by convection. The female connection (32) includes opposed legs (78) defining a groove (80) therebetween, and the male connection (34) includes a tongue (74) inserted into the groove (80) to connect adjacent slats (24).

TECHNICAL FIELD
 This invention relates to trailer structures and, more particularly, to
 livestock trailer sidewall slat constructions.
 BACKGROUND
 Horses, cattle, and other livestock are commonly transported from one
 location to another in specially constructed trailers which include
 sidewalls, roofs, floor decking structures, and loading gates or doors.
 The dimensions and features of these trailers vary widely depending on the
 type of livestock to be transported and the specific end uses for which
 the trailers are designed. For example, horse trailers range from single
 horse, standard hitch trailers, to multi-horse, goose-neck trailers that
 include living quarters for equestrians.
 The sidewall structures of many livestock trailers are formed with panels
 supported by and welded to posts emending upwardly from the floor decking
 structures. However, difficulties have been encountered with even the most
 advanced sidewall panel constructions. The sidewalls are commonly
 assembled by welding a plurality of panels to upright posts. Frequently,
 water seeps into the trailer at the connections between adjacent panels,
 and heat generated while welding heats the panels to the extent that their
 exterior surfaces are discolored by oxidation. Additionally, the panels
 are preferably made from aluminum making it difficult to insulate the
 trailers.
 Another problem is encountered with reliability of the welds between the
 panels and the upright posts. If an insufficient amount of material is
 provided by the panels for the weld connection, the attachment material
 can melt away or insufficient penetration is made into the attachment
 material while trying to keep from melting the attachment material away.
 Further, the livestock being transported in the trailers will kick the
 sidewalls. Unfortunately, the animals are strong enough to dent the panels
 and occasionally break the weld connections between the panels and the
 upright posts. To inhibit damage from kicking, kick plates are sometimes
 attached to the inner side of the sidewalls. However, their attachment is
 undesirably difficult because of the preferred non-planar configuration of
 the panel walls.
 SUMMARY OF THE INVENTION
 Accordingly, one important object of the present invention is to provide an
 improved sidewall construction which inhibits discoloration, has more
 reliable welds, is better insulated, and to which kicking plates and other
 such devices are more easily attached.
 In carrying out the foregoing and other objects, the present invention
 contemplates an improved sidewall slat for use in a trailer. The slat
 includes an outer skin and an inner skin which is spaced apart from the
 outer skin to define an internal gap therebetween. A reinforcing bulkhead
 is positioned in the gap and connects the inner skin and the outer skin.
 In a preferred embodiment, a plurality of bulkheads divide the gap into a
 plurality of internal chambers which are operative to inhibit convection
 between the inner and outer skins, and the gap is filled with an
 insulating material. A weld location line is formed in an exposed surface
 of the inner skin, and the inner skin is substantially flat having
 substantially planar surfaces. The outer skin is preferably scalloped
 having alternating peaks and valleys on both its exterior and interior
 surfaces. Alternatively, the interior surface of the outer skin is
 substantially planar. The inner and outer skins and the bulkhead are
 preferably integrally formed, but in an alternate embodiment, the inner
 and outer skins are formed by separate components which are adhered
 together. In this alternate embodiment, the bulkheads comprise generally
 V-shaped bulkheads which receive the peaks of the interior surface of the
 outer skin.
 The present invention further contemplates incorporating the foregoing slat
 construction into a trailer for transporting livestock. The trailer
 includes a trailer frame with a plurality of upright posts extending
 upwardly from a floor of the trailer. A plurality of sidewall slats as
 described above are attached to the upright posts by weld connections.
 Preferably, the weld connections are centrally positioned between the
 bulkheads at the weld location lines.
 In a preferred embodiment of the trailer, at least one of the sidewall
 slats includes an edge having an elongated tongue, and an adjacent
 sidewall slat includes an edge having opposed legs defining a groove which
 receives the tongue therein. The height of the tongue and the height of
 the legs are preferably greater than the width of the groove between the
 legs to inhibit the penetration of water through the sidewall of the
 trailer.

DETAILED DESCRIPTION
 Referring to the drawings in greater detail, the improved slat construction
 20 shown in FIGS. 1-3 is utilized in a livestock or horse trailer 22. The
 improved slat construction 20 includes a plurality of extruded aluminum
 slats 24 each having an inner skin 26, an outer skin 28, a plural of
 bulkheads 30, a normally upper longitudinal edge 34, and a normally lower
 longitudinal edge 32. The trailer 22 includes a roof 36 and a trailer
 frame which includes a plurality of upright posts 38 extending upwardly
 from a floor structure 40 toward the roof 36. The trailer 22 also includes
 many conventional features such as a hitching mechanism 42 and a plurality
 of ground-engaging wheels 44. The wheels 44 are rotatably mounted on and
 support the trailer frame, and the hitching mechanism 42 is connected to
 the front of the trailer frame for coupling the trailer 22 with a towing
 vehicle (not shown). These conventional features and others of the trailer
 22 are described to the extent necessary for an understanding of the
 invention.
 Referring to FIGS. 2-4, the inner skin 26 is substantially flat and
 includes a substantially planar enclosed surface 46 which faces the outer
 skin 28 and an exposed surface 48 which faces away from the outer skin 28.
 The outer skin 28 is preferably scalloped and includes an exterior surface
 50 having alternating peaks 52 and valleys 54. The outer skin 28 also
 includes an interior surface 56 facing toward the inner skin 26. The
 interior surface 56 is also preferably scalloped having alternating peaks
 58 and valleys 60. The peaks 50 of the exterior surface coincide with the
 valleys 60 of the interior surface 56, and the valleys 54 of the exterior
 surface 50 coincide with the peaks 58 of the interior surface 56. The
 inner skin 26 is spaced apart from the outer skin 28 to define an
 insulating gap 62 between the inner and outer skins.
 The horizontal bulkheads 30 of each slat 24 are positioned in the gap 62 at
 vertically spaced uniform intervals. Each bulkhead 30 preferably extends
 the full length of the slat and is of such a width that it spans the
 distance between the inner and outer skins to divide the gap into a
 plurality of elongated internal chambers, thereby interrupting the
 otherwise open expanse of the gap 62 from one edge 32 to the other edge 34
 and thereby impeding airflow between the edges. This inhibits beat
 transfer by convection between the inner and outer skins. The bulkheads,
 which are connected to the inner and outer skins, are preferably
 positioned at the valleys 54 of the exterior surface 50 of the outer skin
 28 to reinforce the outer wall. Thus, a structurally sound arch is formed
 between the bulkheads 30 thereby inhibiting the formation of dents in the
 exterior surface 50 of the outer skin 28.
 As shown in the embodiment of FIG. 4, the inner and outer skis and
 bulkheads are preferably integrally formed. Further, each slat preferably
 includes two bulkheads bifurcating the gap into three internal cavities.
 The outer skin 28 preferably includes three scallops, so that there are
 three peaks 52 on the exterior surface 50 of the outer skin 28 and two
 valleys 54 separating the peaks 52. The slat is elongated having a forward
 end 53 (FIG. 1) and a rearward end 55 (FIG. 1), and the skins and
 bulkheads are also elongated preferably extending over the entire length
 of the slat.
 To further insulate the slat, the gap 62 is alternatively filled with an
 insulating material 64. The insulating material is introduced into the
 internal air chambers of the gap 62 through insulation fill holes 66 (FIG.
 3) formed through the inner skin 26. With the exception of the alternate
 insulation fill holes 66, the inner skin is substantially continuous.
 Because the inner skin is substantially continuous, weld connections 68,
 which connect the slat 24 to the upright posts 38, can be used anywhere
 along the length of the upright posts. Alternatively, the slats can be
 attached to the posts with an adhesive or mechanical fasteners. Further,
 the substantially continuous inner skin 26 also provides sufficient
 attachment material, so that the weld connections 68 are consistently
 formed with adequate weld penetration into the inner skin and without
 structural damage to the slat 24. The substantially continuous inner skin
 also allows for the simple attachment of devices such as kick plates (not
 shown) which inhibit livestock from denting the slats.
 Though the weld connection 68 can be made at any point along the lengths of
 the upright posts, the weld connections 68 are preferably formed at
 locations away from the bulkheads 30. As shown in the preferred
 embodiment, the weld connections 68 are centrally positioned between the
 bulkheads 30. To substantially guarantee the location of the weld
 connections 68 between the bulkheads 30, the slat 24 is formed with a weld
 location line 70 positioned centrally between the bulkheads 30. The weld
 locations line 70 is formed by a narrow and shallow groove extruded in the
 slat and preferably extends over the entire length of the slat 24 parallel
 to the bulkheads. With the weld connections 68 located between the
 bulkheads 30, there is little, if any, discoloration on the exterior
 surface 50 of the outer skin 28. The heat generated by welding is spread
 throughout the inner skin which acts as a heat sink. Further, there is a
 large surface area from which heat is discharged. Further, because the
 welds are spaced apart from the bulkheads, the heat must travel through
 both the inner skin and bulkhead before it reaches the exterior surface of
 the outer skin thereby inhibiting the conduction of heat to the outer
 skin. Thus, insufficient heat is transferred to the outer skin to cause
 discoloration even though the gap is substantially closed and air cannot
 escape from between the inner and outer skins.
 The opposed first and second edges 32, 34 preferably comprise a female edge
 connection and a male edge connection, respectively, to connect adjacent
 slats. The male edge connection 34 comprises a first end wall 72 and an
 elongated tongue 74. The female edge connection 32 comprises a second end
 wall 76 and a pair of elongated opposed legs 78 defining a groove 80
 therebetween. The end walls 72, 76 are adjacent to the edges and extend
 over the length of the slat between and connect to the inner and outer
 skins 26, 28 to close the internal gap 62 at the edges of the slat. The
 tongue 74 is matingly inserted into the groove 80 of an adjacent slat. To
 provide continuity between the surfaces 46, 48, 50, 56 of the slats, the
 tongue 74 and legs 78 preferably extend over the length of the slat and
 have approximately the same heights. To inhibit water from seeping into
 the trailer 22 along the edges of the adjacent slats, the heights of the
 tongue 74 and legs 78 are preferably greater than the width of groove 80
 between the legs 78.
 Referring to the alternate embodiment shown in FIG. 5, the alternate
 embodiment is, in many ways, similar to the previously described
 embodiment and similar elements will be identified with similar reference
 numerals distinguished by the suffix A. The alternate slat 24A also
 includes an inner skin 26A, an outer skin 28A, and a plurality of
 bulkheads 30A which are preferably integrally formed. In this embodiment
 the outer skin 28A is further strengthened by adding material to its
 interior surface 82.
 Preferably, the interior surface 82 is substantially planar, so that the
 outer skin has a thickness which gradually increases as the distance from
 the bulkheads increases. Thus, the embodiment of FIG. 5 provides increased
 resistance to the formation of dents in the outer skin 28A at the
 locations between the reinforcing bulkheads 30A.
 Referring to the alternate embodiment shown in FIG. 6, the alternate
 embodiment is, in many ways, similar to the previously described
 embodiment and similar elements will be identified with similar reference
 numerals distinguished by the suffix "B". The alternate slat 24B also
 includes an inner skin 26B, an outer skin 28B, and a plurality of
 bulkheads 30B. However, the inner skin 26B is separately extruded from the
 outer skin 28B, and the bulkheads 30B are integrally formed with a
 selected one of the inner and outer skins. As shown in FIG. 6, it is
 preferred that the bulkheads are integral with the inner skin.
 The outer skin 28B is scalloped and includes an overlapping tab 84 along
 one edge. The opposite edge 86 from the overlapping tab 84 has a portion
 thereof removed, so that the removed portion of one slat 24B is configured
 to mate with an overlapping tab from an outer skin of an adjacent slat.
 The inner skin includes abutment edges 88 which abut each other when the
 slats are welded to the upright posts 38. As illustrated, the overlapping
 tabs 84 overlap the inner skins 26B adjacent to the abutment edges 88.
 The bulkheads 30B are generally V-shaped to present a pair of diverging
 legs 90, 92. The shallow V-shape of each bulkhead 30B enables it to
 complementally mate with the peaks 58B of the interior surface 56B of the
 outer skin 28B. The legs 90, 92 of the bulkheads 30B are spaced away from
 the inner skin 26B by narrow converging gaps 94. An adhesive 96 is applied
 between the V-shaped bulkheads and the peaks 58B to bond the inner and
 outer skins together.
 Thus, an improved slat construction is provided which inhibits
 discoloration during welding, increases the reliability of weld
 connections, provides additional insulating capacity, inhibits the
 formation of dents in the slats, and inhibits water from seeping into the
 trailer between the adjacent slats.
 Although preferred forms of the invention have been described above, it is
 to be recognized that such disclosure is by way of illustration only, and
 should not be utilized in a limiting sense in interpreting the scope of
 the present invention. Modifications to the exemplary embodiments, as
 herein above set forth, could be readily made by those skilled in the art
 without departing from the spirit of the appended claims.
 The inventor(s) hereby state their intent to rely on the Doctrine of
 Equivalents to determine and assess the reasonably fair scope of their
 invention as pertains to any apparatus or method not materially departing
 from but outside the literal scope of the invention as set out in the
 following claims.