Double hinged inner spring unit

Claim 1

IN A SPRING UNIT, A PAIR OF END SECTIONS EACH COMPRISING A MULTIPLICITY OF ROWS OF UPRIGHT COIL SPRINGS HAVING IDENTICAL TOP AND BOTTOM END COILS AND A FIRST STIFFENING BORDER WIRE ON EACH FACE OF THE SECTION EXTENDING AROUND ONE END EDGE AND BOTH SIDE EDGES OF THE SECTION AND HAVING TRANSVERSELY EXTENDING ARMS ON THE FOURTH EDGE, AN INTERMEDIATE SECTION IN SPACED RELATION TO AND BETWEEN THE END SECTIONS AND COMPRISING A MULTIPLICITY OF ROWS OF UPRIGHT COIL SPRINGS SIMILAR TO THE FIRST MENTIONED COIL SPRINGS AND A SECOND STIFFENING BORDER WIRE ON EACH FACE OF THE INTERMEDIATE SECTION EXTENDING ALONG EACH SIDE EDGE AND HAVING TRANSVERSELY EXTENDING ARMS PART WAY ALONG THE END EDGES OF THE SECTION, AND MEANS FORMING A DOUBLE HINGE CONNECTING THE END EDGES OF THE INTERMEDIATE SECTION TO THE INNER END EDGE OF THE ADJACENT END SECTION AT BOTH FACES OF THE SECTIONS AND COMPRISING A CONNECTING ROW OF UPRIGHT COIL SPRINGS SIMILAR TO THE AFOREMENTIONED SPRINGS AND A PAIR OF TRANSVERSE HELICALS FOR SAID CONNECTING ROW AT EACH FACE OF THE UNIT, ONE OF THE PAIR OF HELICALS PASSING AROUND THE ARMS OF THE FIRST BORDER WIRE AND AROUND ONE SIDE OF THE END COILS OF THE SPRINGS OF THE CONNECTING ROW AND AROUND THE END COILS OF THE ROW OF SPRINGS ADJACENT SAID ONE SIDE, AND THE OTHER OF THE PAIR OF HELICALS PASSING AROUND THE ARMS OF THE SECOND BORDER WIRE, AROUND THE OPPOSITE SIDE OF THE END COILS OF THE ROW OF SPRINGS OF THE CONNECTING ROW AND AROUND THE END COILS OF THE SPRINGS ADJACENT SAID OPPOSITE SIDE, EACH OF THE FOUR HELICALS BETWEEN EACH END SECTION AND THE INTERMEDIATE SECTION CONSTITUTING A HINGE BETWEEN THE SECTIONS PERMITTING LIMITED RELATIVE MOVEMENT OF SAID SECTIONS.