Patent ID: 6435310
Filing Date: 2002-08-20
Classification: B66B

Abstract:
A hydraulic elevator system comprising:an elevator car vertically movable in a hoist way of a building; a hydraulic cylinder connected to the elevator car for lifting/lowering the elevator car; a hydraulic pump for supplying pressed oil to the hydraulic cylinder; a motor for driving the hydraulic pump; a reverse check valve disposed at a first oil path between the hydraulic cylinder and the hydraulic pump, wherein said reverse check valve is opened to allow pressed oil to be supplied from the hydraulic pump to the hydraulic cylinder when the elevator car is lifted, closed by pilot oil from the hydraulic cylinder to prevent an oil back current from the hydraulic cylinder to the hydraulic pump when the elevator car stops, and opened by pressed oil from the hydraulic pump when the elevator car is lowered, in order to allow the elevator car to be lowered; and a pilot hydraulic cylinder unit disposed at a second oil path in parallel with the first oil path, and between the hydraulic cylinder and the reverse check valve for applying an additional force to the reverse check valve in a closing direction of the reverse check valve by the pilot oil from the hydraulic cylinder.