Hydraulic drive apparatus
US6192681A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 1, 1998 |
| Grant date | Feb 27, 2001 |
| Priority date | — |
| Expiry date | Jun 1, 2018 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF15B2211/71
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A differential pressure .DELTA.PLS between a delivery pressure of a hydraulic pump 2 and a maximum load pressure among a plurality of actuators 3a-3c is maintained at a target differential pressure .DELTA.PLSref by pump displacement control means 5. The target differential pressure .DELTA.PLSref is modified depending on an engine rotational speed by introducing a differential pressure .DELTA.Pp across a throttle 50 disposed in a delivery line of a fixed pump 30. An unloading valve 80 has first and second auxiliary control pressure chambers 80e, 80f to which the differential pressure p across the throttle 50 is introduced, and a target differential pressure .DELTA.Pun of the unloading valve is also modified in match with change in the target differential pressure .DELTA.PLSref modified by the operation driver 32. Stable load sensing control is thereby achieved without being affected by the engine rotational speed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.