Patent ID: 9387592
Filing Date: 2016-07-12
CPC Classification: B25J,B66C

Claim Text:
1. A gas-pressure type gravity compensation elevator comprising: an elevating mechanism adapted to grasp and ascend/descend a load object; a grasping-state detection portion adapted to detect a load-object grasping state of the elevating mechanism; a gas cylinder adapted to exert a driving force in a direction of ascent, on the elevating mechanism; a first constant-pressure gas cylinder which is pressed by a first constant-load generating portion and is capable of exhibiting a volume change equal to or more than a volume change in the gas cylinder, such that the gas cylinder maintains a pressure which generates a driving force balanced with a weight of the elevating mechanism and a weight of the load object being grasped by the elevating mechanism; a first connection valve adapted to open and close a connection pipe which connects the first constant-pressure gas cylinder and the gas cylinder to each other; a first volume estimation part adapted to estimate, as an estimated value, a sum of a volume in the gas cylinder and a volume in the first constant-pressure gas cylinder; a second constant-pressure gas cylinder which is pressed by a second constant-load generating portion and is capable of exhibiting a volume change equal to or more than the volume change in the gas cylinder, such that the gas cylinder maintains a pressure which generates a driving force balanced with the weight of the elevating mechanism; a second connection valve adapted to open and close a connection pipe which connects the second constant-pressure gas cylinder and the gas cylinder to each other; a second volume estimation part adapted to estimate, as an estimated value, a sum of the volume in the gas cylinder and a volume in the second constant-pressure gas cylinder; a gas supply portion adapted to supply a gas at a pressure exceeding a pressure in the first constant-pressure gas cylinder; a gas exhaust portion adapted to exhaust a gas within the second constant-pressure gas cylinder; a changeover valve portion adapted to perform a changeover among a state where the gas cylinder is connected to the gas supply portion, a state where the gas cylinder is connected to the gas exhaust portion, and a state where the gas cylinder is interrupted from both the gas supply portion and the gas exhaust portion; and an amount-of-gas control part which is adapted to operate the first connection valve, the second connection valve, and the changeover valve portion for controlling the estimated value from the first volume estimation part such that the estimated value from the first volume estimation part equals to a sum of an average volume of the gas cylinder and an average volume of the first constant-pressure gas cylinder or for controlling the estimated value from the second volume estimation part such that the estimated value from the second volume estimation part equals to a sum of the average volume of the gas cylinder and an average volume of the second constant-pressure gas cylinder, every time the load-object grasping state from the grasping-state detection portion is changed.