Title:
HYDRAULIC DRIVE FOR CONSTRUCTION MACHINE
Document Type and Number:
WIPO Patent Application WO/2011/061988
Kind Code:
A1
Abstract:
Provided is a hydraulic drive for a construction machine which can detect a state wherein a hydraulic cylinder for a boom requires a driving pressure during a boom descent operation and automatically switch the operating characteristics of a boom direction switching valve. The hydraulic drive is provided with a control unit (42) which controls an electromagnetic switching valve (40) so that when the rod-side pressure of a hydraulic cylinder (20) for a boom as detected by a pressure sensor (41) is less than a threshold value, a pilot oil passage (38a) having a pressure relief valve (39)is selected and the limit position of a boom descent-side stroke of a boom direction switching valve (31) is at an intermediate position (L1), and when the rod-side pressure of the hydraulic cylinder (20) for the boom as detected by the pressure sensor (41) is not less than a threshold value, the pilot oil passage (38a) is selected and the limit position of a boom descent-side stroke of the boom direction switching valve (31) is at the maximum position (L2).
Inventors:
TAKEBAYASHI, Yoshifumi (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
竹林 圭文 (〒13 茨城県土浦市神立町６５０番地 日立建機株式会社土浦工場 知的財産部内 Ibaraki, 〒3000013, JP)
TSURUGA, Yasutaka (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
釣賀 靖貴 (〒13 茨城県土浦市神立町６５０番地 日立建機株式会社土浦工場 知的財産部内 Ibaraki, 〒3000013, JP)
竹林 圭文 (〒13 茨城県土浦市神立町６５０番地 日立建機株式会社土浦工場 知的財産部内 Ibaraki, 〒3000013, JP)
TSURUGA, Yasutaka (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
釣賀 靖貴 (〒13 茨城県土浦市神立町６５０番地 日立建機株式会社土浦工場 知的財産部内 Ibaraki, 〒3000013, JP)
Application Number:
JP2010/065872
Publication Date:
May 26, 2011
Filing Date:
September 14, 2010
Export Citation:
Assignee:
HITACHI CONSTRUCTION MACHINERY CO., LTD. (5-1 Koraku 2-chome, Bunkyo-ku Tokyo, 63, 〒1128563, JP)
日立建機株式会社 (〒63 東京都文京区後楽二丁目５番１号 Tokyo, 〒1128563, JP)
TAKEBAYASHI, Yoshifumi (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
竹林 圭文 (〒13 茨城県土浦市神立町６５０番地 日立建機株式会社土浦工場 知的財産部内 Ibaraki, 〒3000013, JP)
TSURUGA, Yasutaka (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
日立建機株式会社 (〒63 東京都文京区後楽二丁目５番１号 Tokyo, 〒1128563, JP)
TAKEBAYASHI, Yoshifumi (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
竹林 圭文 (〒13 茨城県土浦市神立町６５０番地 日立建機株式会社土浦工場 知的財産部内 Ibaraki, 〒3000013, JP)
TSURUGA, Yasutaka (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
International Classes:
F15B11/08; E02F9/22
Attorney, Agent or Firm:
KASUGA, Yuzuru (Torii-nihonbashi Bldg, 4-1 Nihonbashi-honcho 3-chom, Chuo-ku Tokyo 23, 〒1030023, JP)
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