Hydraulic drive system for hydraulic working machines
US5421155A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 28, 1994 |
| Grant date | Jun 6, 1995 |
| Priority date | — |
| Expiry date | Mar 28, 2014 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF15B2211/71
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A hydraulic drive system for hydraulic working machines has a variable displacement hydraulic pump, at least one actuator driven by the hydraulic fluid, a directional control valve of center bypass type for controlling the flow of the hydraulic fluid, a center bypass line for connecting the center bypass passage of the control valve to a reservoir and a fixed restrictor disposed in the center bypass line. A first control signal that determines a first target displacement of the hydraulic pump is determined by using the pressure generated by the fixed restrictor. A second control signal is generated for determining a second target displacement of a hydraulic pump. A third control signal, which is the larger one of the first and second control signals, provides a target displacement that is applied to a pump regulator that controls the displacement of the hydraulic pump. A metering characteristic as good as the conventional one can be obtained in the case of a light load, and a satisfactory metering characteristic can be achieved in the case of a heavy load, as a result.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.