Title:
HYDRAULIC SYSTEM OF CONSTRUCTION MACHINE
Document Type and Number:
Japanese Patent JP2019148318
Kind Code:
A
Abstract:
To provide a hydraulic system of a construction machine capable of achieving the electric control of the unload flow quantity at a normal time and the fail-safe with inexpensive configuration.SOLUTION: The hydraulic system of a construction machine, comprises: a pump supplying hydraulic fluid to a hydraulic actuator; a control valve which is disposed on a center bypass line extending from the pump to a tank and has a bypass passage; an unloader valve provided on the center bypass line on the downstream of the control valve; and a control device controlling the unloader valve. The control valve is configured in such a manner that the opening area of the bypass passage is larger than the opening area of the unloader valve during a period while an operation signal output from a handling device increases from a predetermined value to a first set value, and that the opening area of the bypass passage becomes 1/4 or less than the maximum opening area of the bypass passage when the operation signal becomes a second set value larger than the first set value.SELECTED DRAWING: Figure 1
Inventors:
KONDO TETSUHIRO
HATA NAOKI
HATA NAOKI
Application Number:
JP2018034521A
Publication Date:
September 05, 2019
Filing Date:
February 28, 2018
Export Citation:
Assignee:
KAWASAKI HEAVY IND LTD
International Classes:
E02F9/20; F15B11/00; F15B11/08
Attorney, Agent or Firm:
Patent business corporation Yuko patent office