Wall construction for refrigerated vehicles

Claim 1

A THERMALLY INSULATIVE WALL STRUCTURE COMPRISING AT LEAST TWO MODULAR PANELS, EACH PANEL BEING CONSTITUTED BY: AN OUTER SKIN SHEET AND A SUBSTANTIALLY IDENTICAL INNER SKIN SHEET, SAID SHEETS ENGAGING EACH OTHER ONLY ALONG THEIR EDGES IN A MANNER TO BE DESCRIBED AND DEFINING AND INTERNAL CAVITY BETWEEN THEM, AND A FOAMED PLASTIC CORE IN SAID CAVITY, EACH SAID SKIN SHEET COMPRISING, A SHEET OF SUBSTANTIALLY UNIFORM THICKNESS HAVING A SERIES OF PARALLEL RIBS FORMED IN IT, EACH PAIR OF SAID RIBS BEING SPACED BY A DEPRESSION BETWEEN THEM, THE PEAKS OF SAID RIBS BEING COPLANAR AND THE BOTTOMS OF SAID DEPRESSIONS BEING COPLANAR, THE WIDTHS OF SAID RIBS AND DEPRESSIONS ALL BEING SUBSTANTIALLY EQUAL, A FIRST FLAT MARGINAL AREA ADJOINING A RIB ALONG ONE SIDE OF THE SHEET, THE EDGE OF SAID AREA DEFINING THE EDGE OF SAID SHEET, SAID AREA BEING COPLANAR WITH SAID DEPRESSIONS, AN ABUTMENT SURFACE SPACED FROM SAID MARGINAL AREA BY SAID RIBS AND DEPRESSIONS, SAID ABUTMENT SURFACE BEING ADJACENT TO A RIB AND RESIDING IN A PLANE PARALLEL TO BUT INSET FROM THE PLANE OF SAID DEPRESSIONS AND MARGINAL AREA BY ABOUT TWICE THE THICKNESS OF THE SHEET, SAID FIRST FLAT MARGINAL AREA BEING LOCATED ALONG THE OPPOSITE SIDE OF SAID SHEET FROM SAID ABUTMENT SURFACE,