Title:
作業機の油圧回路
Document Type and Number:
Japanese Patent JP4209705
Kind Code:
B2
Abstract:
A joining directional control valve 13 is disposed to supply, to an arm cylinder 4, not only a hydraulic fluid delivered from a first hydraulic pump 1, but also a hydraulic fluid delivered from a second hydraulic pump 2 when an arm directional control valve 14 is driven. Respective delivery pressures of the hydraulic pumps 1, 2 are detected by pressure sensors 101, 102, and the opening area of a recovery control valve 6 is controlled depending on a lower one of the detected pressures from the pressure sensors 101, 102 such that, even in the combined operation of the arm cylinder 4 and another actuator 3, 4, the hydraulic fluid can be recovered for return to the arm cylinder 4 when the load pressure of the arm cylinder 4 is low. Thus, by supplying the hydraulic fluids from the two hydraulic pumps to the particular actuator for which the hydraulic fluid is to be recovered, a recovery flow rate is ensured when the load of the particular actuator is low in the combined operation.
Inventors:
Tsuyoshi Nakamura
Genroku Sugiyama
Tsukasa Toyooka
Koji Ishikawa
Genroku Sugiyama
Tsukasa Toyooka
Koji Ishikawa
Application Number:
JP2003071332A
Publication Date:
January 14, 2009
Filing Date:
March 17, 2003
Export Citation:
Assignee:
Hitachi Construction Machinery Co., Ltd.
International Classes:
F15B21/14; E02F9/22; F15B11/02; F15B11/024; F15B11/17; F15B21/08
Domestic Patent References:
| JP8219121A | ||||
| JP63083808A | ||||
| JP2001355603A | ||||
| JP6117411A | ||||
| JP9210006A | ||||
| JP6264471A | ||||
| JP60179504A |
Foreign References:
| WO1994013959A1 | ||||
| US3994133 |
Attorney, Agent or Firm:
Kasuga Toshiaki