IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0428203
(2009-04-22)
|
등록번호 |
US-8336443
(2012-12-25)
|
우선권정보 |
JP-2003-005808 (2003-01-14); JP-2003-143632 (2003-05-21) |
발명자
/ 주소 |
- Abe, Toshihiro
- Kajita, Yusuke
- Nakamura, Kazunori
- Ishikawa, Kouji
- Karasawa, Hideo
|
출원인 / 주소 |
- Hitachi Construction Machinery Co., Ltd.
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
3 인용 특허 :
3 |
초록
▼
A hydraulic circuit for a hydraulic working machine is composed of a main pump 21, a boom cylinder 11 arranged for extension or contraction by pressure oil from the main pump 21, a directional control valve 22 for controlling flows of pressure oil to be fed from the main pump 21 to a bottom chamber
A hydraulic circuit for a hydraulic working machine is composed of a main pump 21, a boom cylinder 11 arranged for extension or contraction by pressure oil from the main pump 21, a directional control valve 22 for controlling flows of pressure oil to be fed from the main pump 21 to a bottom chamber 11a and rod chamber 12b of the boom cylinder 11, a control unit 23 for performing a change-over control of the directional control valve 22, a pilot pump 24, a jack-up selector valve 25 for controlling a flow of pressure oil delivered from the pilot pump 24, a flow control valve 26 connected on an upstream side of the directional control valve 22 to a meter-in port of the directional control valve 22 such that the flow control valve 26 can be changed over by the jack-up selector valve 25, and a center bypass selector valve 27 connected on a downstream side of the directional control valve 22 to a center bypass port of the directional control valve 22 such that the center bypass selector valve 27 can be changed over by the jack-up selector valve 25. The hydraulic circuit performs a change-over of the jack-up selector valve 25 in accordance with a bottom pressure on the boom cylinder 11.
대표청구항
▼
1. A hydraulic working machine provided with: a double-acting hydraulic cylinder arranged for extension or contraction by pressure oil, which is delivered from a main pump, to drive a working element,a directional control valve for controlling a flow of pressure oil to be fed from said main pump to
1. A hydraulic working machine provided with: a double-acting hydraulic cylinder arranged for extension or contraction by pressure oil, which is delivered from a main pump, to drive a working element,a directional control valve for controlling a flow of pressure oil to be fed from said main pump to said hydraulic cylinder, anda control unit for performing a change-over control of said directional control valve, characterized in that said hydraulic working machine is provided with:a jack-up selector valve for being changed over in flow-line when a feed pressure to said hydraulic cylinder has reached a predetermined pressure, anda pilot-controlled flow-line changing means for changing a flow-line for pressure oil, which is to be fed from said main pump to a meter-in port of said directional control valve, from an open side to a closed side in response to a change-over control of said jack-up selector valve which generates a pilot hydraulic control signal from said jack-up selector valve to said pilot-controlled flow-line changing means,wherein, when a holding pressure on said hydraulic cylinder is equal to or higher than the predetermined pressure upon lowering said working element, said jack-up selector valve is changed over to a first selected position to change over said flow-line changing means to the closed side such that pressure oil delivered from said main pump is not fed to a non-holding pressure feeding side of said hydraulic cylinder, andwhen the holding pressure on said hydraulic cylinder is lower than the predetermined pressure upon lowering said working element, said jack-up selector valve is changed over to a second selected position to change over said flow-line changing means to the open side such that pressure oil delivered from said main pump is fed to a non-holding pressure side of said hydraulic cylinder via said directional control valve. 2. A hydraulic working machine according to claim 1, wherein as said jack-up selector valve, said hydraulic working machine is provided with a hydraulically-piloted selector valve. 3. A hydraulic working machine provided with a first and second main pumps, a first track unit for being driven by pressure oil delivered from said first main pump, a second track unit for being driven by pressure oil delivered from said second main pump, a first directional control valve for controlling a flow of pressure oil to be fed from said first main pump to said first track unit, a second directional control valve for controlling a flow of pressure oil to be fed from said second main pump to said second track unit, a working element, a double-acting hydraulic cylinder arranged for extension or contraction by pressure oil, which is delivered from said first and second main pumps, to drive said working element, a third directional control valve for controlling flows of pressure oil to be fed from said first main pump to a bottom chamber and rod chamber of said hydraulic cylinder, a fourth directional control valve for controlling flows of pressure oil to be fed from said second main pump to said bottom chamber and rod chamber of said hydraulic cylinder, a first control unit for performing change-over controls of said first and second directional control valves, and a second control unit for performing change-over controls of said third and fourth directional control valves, characterized in that said hydraulic working machine is provided with: a jack-up selector valve for being changed over when a bottom pressure on said hydraulic cylinder has reached a predetermined pressure, anda flow-line changing means for changing a flow-line for pressure oil, which is to be fed from said first main pump to a meter-in port of said third directional control valve, from an open side to a closed side in response to a change-over control of said jack-up selector valve,wherein, when the bottom pressure on said hydraulic cylinder is equal to or higher than the predetermined pressure upon lowering said working element, said jack-up selector valve is changed over to a first selected position to change over said flow-line changing means to the closed side such that pressure oil delivered from said first and second main pumps is not fed to said rod chamber of said hydraulic cylinder, andwhen the bottom pressure on said hydraulic cylinder is lower than the predetermined pressure upon lowering said working element, said jack-up selector valve is changed over to a second selected position to change over said flow-line changing means to the open side such that pressure oil delivered from said first and second main pumps is fed to said rod chamber of said hydraulic cylinder via said third and fourth directional control valves. 4. A hydraulic working machine provided with a first and second variable displacement hydraulic pumps as main pumps, a first and second swash angle control means for independently controlling displacements of said first and second variable displacement hydraulic pumps, respectively, a first track unit for being driven by pressure oil delivered from said first variable displacement hydraulic pump, a second track unit for being driven by pressure oil delivered from said second variable displacement hydraulic pump, a first directional control valve for controlling a flow of pressure oil to be fed from said first variable displacement hydraulic pump to said first track unit, a second directional control valve for controlling a flow of pressure oil to be fed from said second variable displacement hydraulic pump to said second track unit, at least one working element, at least one actuator arranged for extension or contraction by pressure oil, which is delivered from said first and second variable displacement hydraulic pumps, to drive said working element, a third directional control valve for controlling a flow of pressure oil to be fed from said first variable displacement hydraulic pump to said actuator, a fourth directional control valve for controlling a flow of pressure oil to be fed from said second variable displacement hydraulic pump to said actuator, a pilot control unit for performing change-over controls of said first and second directional control valves, and a swash angle instruction means for outputting a swash angle control signal to said swash angle control means in response to a signal from said pilot control unit, characterized in that said hydraulic working machine is provided with: a jack-up selector valve for being changed over when a holding pressure on said actuator has reached a predetermined pressure, anda flow-line changing means for changing a flow-line for pressure oil, which is to be fed from said first variable displacement hydraulic pump to a meter-in port of said third directional control valve, from an open side to a closed side in response to a change-over control of said jack-up selector valve,wherein, when the holding pressure on said actuator is equal to or higher than the predetermined pressure upon lowering said working element, said jack-up selector valve is changed over to a first selected position to change over said flow-line changing means to the closed side such that pressure oil to be fed from said first and second variable displacement hydraulic pumps to said actuator is cut off and the displacements of said first and second variable displacement hydraulic pumps are decreasingly controlled, andwhen the holding pressure on said actuator is lower than the predetermined pressure upon lowering said working element, said jack-up selector valve is changed over to a second selected position to change over said flow-line changing means to the open side such that pressure oil delivered from said first and second variable displacement hydraulic pumps is fed to said actuator via said third and fourth directional control valves and the displacements of said first and second variable displacement hydraulic pumps are increasingly controlled by said swash angle instruction means.
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