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:
Sep. 07, 1993
Filed:
Oct. 15, 1991
Masao Tomisawa, Amagasaki, JP;
Takehiko Kubota, Inazawa, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
An apparatus for controlling a car of a hydraulic elevator by variable-speed-driving an electric motor directly coupled to a hydraulic pump so as to adjust the rate at which oil is supplied from the hydraulic pump to a hydraulic jack system, the apparatus having a speed controller for variable-speed-driving the electric motor, a first detector for detecting the speed of the car, a second detector for detecting the rotational speed of the electric motor, a third detector for detecting a pressure in the hydraulic jack system, a feedback circuit for returning a control signal for limiting vibration of the car as a feedback signal to the speed controller. The feedback circuit forms the control signal from a differential signal representing the difference between a car speed value converted from the rotational speed of the electric motor detected by the second detector and the car speed detected by the first detector and a pressure signal representing the pressure detected by the third detector.