Hydraulic drive system for construction machines
US5056312A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 22, 1989 |
| Grant date | Oct 15, 1991 |
| Priority date | — |
| Expiry date | Nov 22, 2009 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF15B2211/78
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A hydraulic system for a construction machine comprising plural hydraulic actuators (23-28) driven by fluid supplied from a pump (22), first and second flow control valves (29-34) for controlling flows of fluid supplied to the first and second actuators, and first and second distribution compensating valves (35-40) for controlling first differential pressure (.DELTA.P v1-.DELTA.P v6) produced between inlets and outlets of the first and second flow control valves. The first and second distribution compensating valves have respective drives (45-50, 35c-40c) for applying control forces (Fc1-Fc2) in accordance with the second differential pressure to the associated distribution compensating valves, to thereby set target values of the first differential pressures. The hydraulic system includes first means (59) for detecting the second differential pressure (.DELTA.P LS) from the discharge pressure (P s) of the pump (22) and the maximum load pressure (P amax) out of the first and second actuators; second means (61) for calculating individual values (Fc1-Fc6), as values of the control forces applied from the drives (45-50, 35C-40C) of the first and second distribution compensating valves …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.