The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 01, 2004
Filed:
Dec. 19, 2001
Sead Veletovac, Dübendorf, CH;
Luigi Del Re, Zürich, CH;
Andreas Schrempf, Waidhofen/Ybbs, AT;
Wittur AG, Wiedenzhausen, DE;
Abstract
A control valve unit for a hydraulic elevator includes two control valves wherein the flow of hydraulic oil from a tank to a lifting cylinder driving an elevator cabin and/or from the lifting cylinder to the tank can be controlled. In case of an upward movement of the elevator cabin, hydraulic oil is conveyed by a pump driven by an electromotor from the tank through the control valve unit to the lifting cylinder. In the case of a downward movement of the elevator cabin, the hydraulic oil flows through the control valve unit to the tank without the pump working. The control of the upward movement and the downward movement of the elevator cabin is achieved by one single pilotable control valve, respectively, that are provided to act as a check valve as well as a proportional valve.