Method and device for controlling a hydraulic lift
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United States of America Patent
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-
Nov 7, 2000
Grant Date -
N/A
app pub date -
Feb 10, 1999
filing date -
Feb 6, 1997
priority date (Note) -
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Abstract
The invention relates to a method and an apparatus for controlling a hydraulic elevator, in which a car (2) is movable up and down in an elevator shaft (1). The car (2) is connected to a reciprocating piston. The car (2) is driven by an oil pump (40), with which pressurized oil is pumped between a tank (41) and a reciprocating cylinder (3). The oil pump (40) is driven by a motor (39), which is supplied by a controllable power supply part (28). The speed of the car (2) is detected by a sensor (13). A control and governing unit (10) controls and regulates the devices that affect the motion of the car (2), namely the motor (39) and a valve unit (43). In upward motion, the speed of the car (2) is controlled by regulation the motor (39). According to the invention, in downward motion, closed- or open-loop control is exerted on the valve unit (43). At low speeds upon startup and in braking of the car (2), the speed regulation is effected by actuating the valve unit (43), while at higher speeds and in upward motion it is effected by regulating the motor (39).
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