公开(公告)号：JP2002323002A

公开(公告)日：2002-11-08

申请号：JP2001124180

申请日：2001-04-23

Applicant: NACHI FUJIKOSHI CORP ,  HITACHI CONSTRUCTION MACHINERY

Inventor： HAMAMOTO SATOSHI ,  OKAZAKI KOJI ,  NAGAO KOSHO ,  TSURIGA YASUTAKA ,  KANAI TAKASHI ,  KAWAMOTO JUNYA

IPC: F15B11/05 ,  F15B11/00

Abstract: PROBLEM TO BE SOLVED: To provide a hydraulic drive unit comprising a circuit structure capable of preventing the occurrence of a shock at an actuator that is not stopped while another actuator is stopped, when two or more actuators are simultaneously in operation in a construction machine such as a hydraulic shovel and the like. SOLUTION: A secondary pressure (Pc) equal to the differential pressure between the discharging pressure of an oil pressure pump 10 and the maximum load pressure (Plmax) of a plurality of actuators 4a, 4b is led from a differential pressure reducing valve 34 to every pressure compensation valve 21a, 21b through a pressure differential line 2 including a first throttle 61. The secondary pressure (Pc) from the differential pressure reducing valve 34 is directly introduced to a control valve 12 for controlling a pump tilt angle. A secondary pressure (Pc') to be led to all of the pressure compensation valves 21a, 21b are lowered than the secondary pressure (Pc) from the pressure of the downstream of the first throttle 61 of the differential pressure line 2 by the throttle resistance of the first throttle 61.

公开(公告)号：JP2002206508A

公开(公告)日：2002-07-26

申请号：JP2001000802

申请日：2001-01-05

Applicant: HITACHI CONSTRUCTION MACHINERY

Inventor： TSURIGA YASUTAKA ,  KANAI TAKASHI ,  KAWAMOTO JUNYA

IPC: E02F9/22 ,  F15B11/00 ,  F15B11/05 ,  F15B11/16

Abstract: PROBLEM TO BE SOLVED: To secure fine operation performance by setting an engine speed, allow flow control at favorable responsiveness, and achieve excellent operability in a hydraulic driving device provided with an LS system. SOLUTION: Differential pressure between delivery pressure of a fixed displacement pump 2 and the highest load pressure of plural actuators 3a-3c is maintained at a target differential pressure by an unload valve 5. A set pressure of the unload valve 5 is changed in accordance with the engine speed by introducing front-back differential pressure ΔPp of an aperture 50 provided in a delivery way of a fixed pump 30 to a pressure receiving part 5d.

公开(公告)号：JP2001323901A

公开(公告)日：2001-11-22

申请号：JP2000143278

申请日：2000-05-16

Applicant: HITACHI CONSTRUCTION MACHINERY ,  NACHI FUJIKOSHI CORP

Inventor： TSURIGA YASUTAKA ,  KANAI TAKASHI ,  KAWAMOTO JUNYA ,  HAMAMOTO SATOSHI ,  OKAZAKI KOJI ,  NAGAO KOSHO

IPC: E02F3/43 ,  E02F9/22 ,  F15B11/00

Abstract: PROBLEM TO BE SOLVED: To secure the fine operability when starting to turn while maintaining the flow controllability as a merit of a LP system. SOLUTION: A flow control valve 3 has a communication passage 23 for communicating a driving side load passage 12a provided in the downstream of a meter-in variable throttle part 14 with a return side load passage 12b provided in the upstream of a meter-out variable throttle part 15, and a bleed-off variable throttle part 21 arranged in the communication passage 23 and to be opened and closed with the spool stroke of the flow control valve 3.

公开(公告)号：JPH11336136A

公开(公告)日：1999-12-07

申请号：JP14750598

申请日：1998-05-28

Applicant: HITACHI CONSTRUCTION MACHINERY

Inventor： TSURIGA YASUTAKA ,  NAKATANI KENICHIRO ,  KAWAMOTO JUNYA ,  KANAI TAKASHI

IPC: E02F9/22 ,  F02D29/00 ,  F02D29/04 ,  F04B49/00

Abstract: PROBLEM TO BE SOLVED: To provide an engine revolution number control device for a construction machine capable of realizing auto-idle control and its release in which traveling independence can be secured. SOLUTION: In a hydraulic circuit comprising main pumps 2, 3, 4, a communication conduit 1 to connect input ports of direction control valves 5, 9 for traveling to each other, and a traveling communication valve 16 provided in the communication conduit 15, pilot valves 5a, 9a provided in piping 18 and related to traveling, pilot valves 6a, 7a, 8a, 10a provided in piping 18 and related to a boom, etc., pilot valves 12a, 13a, 14a provided in piping 22 and related to turning, soil discharging, etc., a pressure detecting device 21 to detect pressure in the piping 18, 19, and a pressure detecting device 22 to detect pressure of the piping 22 are provided. An engine control device 24 to execute auto-idle control and its release in accordance with signals of the pressure detecting devices 21, 22, and a signal conduit 26 to introduce a signal to change the traveling communication valve 16 to a communication position based on pressure in the piping 19 are provided.

公开(公告)号：JPH10205501A

公开(公告)日：1998-08-04

申请号：JP33240797

申请日：1997-11-17

Applicant: HITACHI CONSTRUCTION MACHINERY

Inventor： TSURIGA YASUTAKA ,  KANAI TAKASHI ,  KAWAMOTO JUNYA

IPC: F04B49/00 ,  E02F9/22 ,  F04B49/10 ,  F15B11/00

Abstract: PROBLEM TO BE SOLVED: To perform a stable load sensing control without being affected by the number of revolutions of an engine in a hydraulic drive device for a load sensing control. SOLUTION: A differential pressure ΔPLS between the discharge pressure of a hydraulic pump 2 and the maximum load pressure of a plurality of actuators 3a to 3c is kept at an object differential pressure ΔPLSref by a pump capacity controller 5. The object differential pressure ΔPLSref is changed according to the number of revolutions of an engine by introducing to an operation drive part 32 a differential pressure ΔPp across a throttle 50 provided in the discharge passage of a fixed pump 30. An unload valve 80 has the first and second auxiliary control pressure rooms 80e, 80f to which the differential pressure ΔPp across the throttle 50 is introduced and when the object differential pressure ΔPLSref is changed by the operation drive part 32, the object differential pressure ΔPun of the unload valve is also changed.