SYSTEMS AND METHODS FOR CONTROLLING WORKING FLUID IN HYDRAULIC ELEVATORS
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United States of America Patent
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Issued Date -
Aug 20, 2020
app pub date -
Feb 18, 2019
filing date -
Feb 18, 2019
priority date (Note) -
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Abstract
A hydraulic elevator may comprise a bidirectional pump that controls up and down motion of an elevator car. A VVVF drive may cause the bidirectional pump to provide working fluid in a controlled manner to a hydraulic jack that supports the elevator car. A control valve may be disposed between the bidirectional pump and the hydraulic jack so that the control valve can be closed when the elevator car needs to be held in place. To avoid pressure waves that propagate when the control valve is opened with disparate pressures on the pump and jack sides of the control valve, the bidirectional pump may adjust the pressure on the pump side of the closed control valve to the pressure on the jack side of the control valve before the control valve is opened.
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