Apparatus for improving the performance of a motor-controlled hydraulic elevator
US5014823A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 29, 1989 |
| Grant date | May 14, 1991 |
| Priority date | — |
| Expiry date | Aug 29, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66B9/04
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
The invention concerns an apparatus for improving the performance of a motor-controlled hydraulic elevator, in which oil is pumped using an hydraulic pump controlled by an electric motor from a container via a main supply duct into a lifting cylinder to move the elevator upwards, and returned in a controlled manner through the pump into the container to move the elevator downwards. In order to improve the loading conditions of the motor during down-travel, the oil pressure in the main duct is reduced to a substantially predetermined constant level by means of a check valve or lowering valve which, to provide compensation for the pressure in the pump, has a feedback connection to the main duct via a pressure compensation valve which controls the volume of flow through the check valve or lowering valve.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.