Workpiece transportation system comprising automated transport vehicles and workpiece carriers

A workpiece transportation system comprising a plurality of workpiece carriers designed to transport workpieces loaded thereon, automated transport vehicles designed to cause the workpiece carrier to travel with it and put and detach the workpiece carrier in a predetermined position on a route, and a guideway for the automated transport vehicle, said guideway including a supply-side line provided for loading of workpieces onto the workpiece carrier in a supply area and traveling of the workpiece-loaded workpiece carrier, a consumption-side line provided for introduction of the workpiece-loaded workpiece carrier and traveling and sending-out of the workpiece carrier that has been emptied by unloading the workpieces in a consumption area, and a buffer line which continuously connects the supply-side line and the consumption side-line, wherein

• the buffer line includes an outward line section onto which workpiece-loaded workpiece earners come from the supply-side line and form a row, and a homeward line section onto which workpiece carriers that have been emptied by unloading workpieces in the consumption area come from the consumption-side line and form a row, where the outward line section and the homeward line section are almost parallel and the disposition of the entry and exit of the outward line section is opposite to the disposition of the entry and exit of the homeward line section so that the outward line section and the homeward line section form a continuous route connected with the supply-side line and the consumption-side line,
• said automated transport vehicles include an automated transport vehicle provided to cause a workpiece carrier that has been loaded with workpieces in the supply area to travel with it along the supply-side line, and when the workpiece-loaded workpiece carrier passes through the entry of the outward line section of the buffer line and moves forward on the outward line section up to a fixed position, leave the workpiece-loaded workpiece carrier in that position, move backward, exit the outward line section, move toward the homeward line section, enter the homeward line section through the exit thereof, and then cause an empty workpiece carrier first encountered on the homeward line section to travel with it back onto the supply-side line, and
• an automated transport vehicle provided to cause a workpiece carrier that has been emptied by unloading workpieces in the consumption area to travel with it along the consumption-side line, and when the empty workpiece carrier passes through the entry of the homeward line section of the buffer line and moves forward on the homeward line section up to a fixed position, leave the empty workpiece carrier in that position, move backward, exit the homeward line section, move toward the outward line section, enter the outward line section through the exit thereof, and then cause a workpiece-loaded workpiece carrier first encountered on the outward line section to travel with it back onto the consumption supply-side line, thereby delivering the workpieces for consumption.