Title:
CONSTRUCTION MACHINERY
Document Type and Number:
WIPO Patent Application WO/2018/180512
Kind Code:
A1
Abstract:
Provided is construction machinery in which, when the rotational speed of a motor is set to be lower than a rated rotational speed and the discharge flow rate of a hydraulic pump is reduced, the operational range of a lever for varying the supply flow rate to a hydraulic actuator is kept wide, whereby deterioration of the operability in a very slow operation work can be prevented. A center bypass control valve (2) is disposed downstream from a plurality of direction flow rate control valves (1, 20, 21) of a center bypass line (12). When an engine speed (N) detected by a rotational speed sensor (19) is lower than a rated rotational speed (Nmax), a controller (10) calculates, on the basis of operation pilot pressures (Pp1, Pp3-Pp6) detected by pressure sensors (7, 25, 26, 28, 29), a combined opening area which is obtained by combining the opening areas of the plurality of direction flow rate control valves of the center bypass line, and controls the center bypass control valve such that the opening area of the center bypass control valve is smaller than the combined opening area.
Inventors:
OGURA KOUHEI (JP)
KODAKA KATSUAKI (JP)
KODAKA KATSUAKI (JP)
Application Number:
PCT/JP2018/010085
Publication Date:
October 04, 2018
Filing Date:
March 14, 2018
Export Citation:
Assignee:
HITACHI CONSTRUCTION MACH CO (JP)
International Classes:
F15B11/02; E02F9/22; F15B11/08
Domestic Patent References:
| WO2017014324A1 | 2017-01-26 |
Foreign References:
| JPH05106606A | 1993-04-27 | |||
| JP2017057925A | 2017-03-23 | |||
| JP2001039672A | 2001-02-13 |
Other References:
See also references of EP 3492754A4
Attorney, Agent or Firm:
KAICHI IP (JP)
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