Acceleration damping of elevator resonant modes and hydraulic elevator pump leakage compensation
US5635689A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 17, 1995 |
| Grant date | Jun 3, 1997 |
| Priority date | — |
| Expiry date | Feb 17, 2015 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66B1/285
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
A speed command signal is applied to a variable voltage, variable frequency controller for driving a three-phase induction motor that operates a positive displacement pump for supplying fluid to a hydraulic elevator drive cylinder. An accelerometer mounted on the car provides an acceleration-related feedback signal to the car speed command input of the motor control, thereby to dampen low frequency resonant modes of the elevator car. A sensor on a check valve between the hydraulic pump and the hydraulic cylinder provides a signal indicative of when the pump pressure is sufficient to support the car load, and the check valve begins to open; the signal is used to memorize ramped-up motor speed at that point, which equals the motor speed necessary to overcome pump leakage in order to support the car. That speed is added into the car speed command at the input of the motor controller to compensate for pump leakage. The acceleration damping of low frequency resonant modes of the elevator car may be utilized in roped elevator systems.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.