Patent ID: 6347515
Filing Date: 2002-02-19
Classification: B66B,Y02B

Abstract:
A drive device for a hydraulic type elevator, the device comprising an actuator cylinder (1) in which a piston (10) is slidably mounted and having a pressure chamber (1a) connected via a hydraulic circuit to a pump (11) driven by a motor (12) and connected to a source of fluid,the device being characterized by the fact that the source of fluid is constituted by a pressure accumulator (4) and by the fact that the hydraulic circuit comprises: a down duct (15) connecting the pressure chamber (1a) to the inlet of the pump (11) and in which there are connected in series a first electrically controlled valve (2) and a first check valve (3); an up duct (16) connecting the outlet of the pump (11) to the pressure chamber (1a), and in which there are connected in series a second electrically controlled valve (6) and a second check valve (5); a first parallel duct (15a) connecting the pressure accumulator (4) to the down duct (15) at a point situated between the first check valve (3) and the inlet to the pump (11), and in which a third electrically controlled valve (6a) is connected; and a second parallel duct (16a) connecting the pressure accumulator (4) to the up duct (16) at a point situated between the second electrically controlled valve (6) and the outlet from the pump (11), and in which a fourth electrically controlled valve (2a) is connected; by the fact that the first electrically controlled valve (2) and the third electrically controlled valve (2a) are open while the elevator is moving downwards, the second electrically controlled valve (6) and the fourth electrically controlled valve (6a) then being closed; and by the fact that the second electrically controlled valve (6) and the fourth electrically controlled valve (6a) are open while the elevator is moving upwards, the first electrically controlled valve (2) and the third electrically controlled valve (2a) then being closed.