Hydraulic elevator control
US5082091A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 28, 1990 |
| Grant date | Jan 21, 1992 |
| Priority date | — |
| Expiry date | Sep 28, 2010 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66B1/24
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
The flow of hydraulic fluid to and from an hydraulic elevator piston is controlled by a motor-actuated spool valve operated by a microprocessor. To lower the elevator, a main check valve is opened by a down piston using hydraulic fluid from the system. Pressure is equalized on both sides of the main check valve just before the latter is opened thereby allowing the use of a smaller down piston which uses less hydraulic fluid. This results in smoother car motion during descent of the car. The addition of a valve bleed passage to equalize pressure on both sides of the check valve also prevents rapid descent of the elevator car in the event that the spool valve were to be open at the time descent commences.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.