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Title:
HYDRAULIC CONTROL DEVICE FOR WORKING MACHINE
Document Type and Number:
WIPO Patent Application WO/2018/179574
Kind Code:
A1
Abstract:
This hydraulic control device comprises a pilot pressure control device (21) that variably controls pilot pressure supplied to a hydraulic pilot part of a directional control valve (14). The pilot pressure control device (21) includes first solenoid valves (22, 23) that selectively connect first output ports (22C, 23C) to first pump ports (22A, 23A) or first tank ports (22B, 23B) and perform switching control for the directional control valve (14) in accordance with an electric signal from a controller (30), a second solenoid valve (25) that selectively connects a second output port (25C) to a second pump port (25A) or a second tank port (25B) in accordance with the electric signal, a pilot pressure supply pipeline (26), and a tank pipeline (27). The second solenoid valve (25) causes pressure oil flowing from the second pump port (25A) to the second output port (25C) to flow back to the tank pipeline (27, 60), and warms up the pilot pressure control device (21).

Inventors:
IKEDO Yuki (Hitachi Construction Machinery Co. Ltd., 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
KANEZAWA Hiroshi (Hitachi Construction Machinery Co. Ltd., 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
ITO Hideaki (Hitachi Construction Machinery Co. Ltd., 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
NISHIHATA Jun (Hitachi Construction Machinery Co. Ltd., 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
Application Number:
JP2017/041316
Publication Date:
October 04, 2018
Filing Date:
November 16, 2017
Export Citation:
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Assignee:
HITACHI CONSTRUCTION MACHINERY CO., LTD. (16-1, Higashiueno 2-chome Taito-k, Tokyo 15, 〒1100015, JP)
International Classes:
F15B21/04; E02F9/20; E02F9/22; F15B11/00; F15B11/08
Foreign References:
JP2000220768A2000-08-08
JPS62246606A1987-10-27
Attorney, Agent or Firm:
HIROWA PATENT FIRM (4F. Nishishinjuku Koide Bldg, 1-3 Nishishinjuku 3-chome, Shinjuku-k, Tokyo 23, 〒1600023, JP)
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