Title:
HYDRAULIC DRIVE DEVICE FOR CONSTRUCTION MACHINE
Document Type and Number:
WIPO Patent Application WO/2010/050305
Kind Code:
A1
Abstract:
A main relief valve (13) is provided with an urging force changing device (60). The urging force changing device (60) forms, together with a gate lock valve (23) and a gate lock lever (24), a relief-set-pressure changing means capable of switching, by means of manual operation, the set pressure of the main relief valve (13) between a normal first pressure (25 MPa, for example) and a second pressure (3.0 MPa, for example) which is lower than the first pressure and which enables, together with an unload valve (9), oil discharged from a hydraulic pump (2) to be returned to a tank (T) when the ambient temperature is below the freezing point and actuators (5a, 5b,...) are not driven. The structure reduces a load on the hydraulic pump in a cold start of an engine without sacrificing anti-hunting characteristics of the unload valve, and this allows the engine to be started more easily at low temperatures.
Inventors:
TAKAHASHI, Kiwamu (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
高橋 究 (〒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)
高橋 究 (〒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)
Application Number:
JP2009/065754
Publication Date:
May 06, 2010
Filing Date:
September 09, 2009
Export Citation:
Assignee:
HITACHI CONSTRUCTION MACHINERY CO., LTD. (5-1 Koraku 2-chome, Bunkyo-ku Tokyo, 04, 〒1120004, JP)
日立建機株式会社 (〒04 東京都文京区後楽二丁目５番１号 Tokyo, 〒1120004, JP)
TAKAHASHI, Kiwamu (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
高橋 究 (〒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 (〒04 東京都文京区後楽二丁目５番１号 Tokyo, 〒1120004, JP)
TAKAHASHI, Kiwamu (Tsuchiura Works, Intellectual Property Department, 650, Kandatsumachi, Tsuchiura-sh, Ibaraki 13, 〒3000013, JP)
高橋 究 (〒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:
F15B11/00; E02F9/22; F15B21/04
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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