Hydraulic elevator with motor controlled hydraulic drive and method for controlling the hydraulic elevator
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United States of America Patent
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Dec 6, 2005
Grant Date -
Apr 22, 2004
app pub date -
Nov 7, 2002
filing date -
Nov 23, 2001
priority date (Note) -
Expired
status (Latency Note)
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Abstract
The invention relates to a hydraulic lift comprising a pressure accumulator (17). Hydraulic fluid can be transported between the pressure accumulator (17) and a hydraulic drive (2) by means of a pump (13), the rotational direction of the pump (13) being variable. According to the invention, there is no valve between the pressure accumulator (17) and the pump (13), and means are provided for preventing the pressure accumulator (17) from being discharged when the lift is at a standstill. In terms of said means, either a screw pump is used as a pump (13), or an electrically controllable leakage stop valve (31) is arranged in a leakage line (30) extending from a leakage port of the pump (13) to the tank (21), said stop valve being closed when the lift is at a standstill. The invention enables a hydraulic lift to be operated in an energy-saving and convenient manner, using a simple hydraulic circuit, and prevents the pressure accumulator (17) from being discharged when the lift is at a standstill.
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