公开(公告)号：US20220154741A1

公开(公告)日：2022-05-19

申请号：US17435602

申请日：2020-05-20

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Hiroki ISHII ,  Shinjiro YAMAMOTO ,  Masamichi ITOU ,  Yasutaka TSURUGA ,  Shinya IMURA

IPC: F15B15/20

Abstract: There is provided a work machine that can limit operation of a work device by MC, and improves the responsiveness of a hydraulic actuator to operation of an operation device by an operator, and ensures operability equivalent to that of a work machine that does not have MC functions, and allows the hydraulic actuator for which the operation device is not being operated to automatically operate in either direction of the operation directions thereof. For this purpose, a drive system includes a selector valve 203a disposed between a secondary port 134a of an operation device 45a and a flow control valve 15a and between a proportional solenoid valve 54a and the flow control valve 15a and a selector valve 203b disposed between a secondary port 134b of the operation device 45a and the flow control valve 15a and between a proportional solenoid valve 54b and the flow control valve 15a. A controller 40 switches the selector valves 203a and 203b to either one of a first position and a second position on the basis of signals from pressure sensors 70a and 70b and pressure sensors 200a and 200b and target operation set in advance regarding the selector valves 203a and 203b.

公开(公告)号：US20220186459A1

公开(公告)日：2022-06-16

申请号：US17437484

申请日：2020-06-18

Applicant: HITACHI CONSTRUCTION MACHINERY CO., LTD.

Inventor： Teruki IGARASHI ,  Akihiro NARAZAKI ,  Masamichi ITOU

IPC: E02F3/43 ,  E02F3/42 ,  E02F9/22 ,  E02F9/26

Abstract: A hydraulic actuator includes a control valve unit that controls a flow of a hydraulic fluid supplied from a hydraulic pump to a plurality of hydraulic actuators, a plurality of control lever devices that output a pilot pressure actuating the control valve unit, with use of a discharged pressure from a pilot pump as a source pressure, a solenoid valve unit including a plurality of solenoid pressure reducing valves connected between the plurality of control lever devices and the control valve unit, and a controller configured to calculate velocity limits for the plurality of hydraulic actuators on the basis of signals from a plurality of posture sensors and control openings of the solenoid pressure reducing valves, in which the controller is configured to control the openings of the solenoid pressure reducing valves for arm crowding and arm dumping to be larger than an opening based on the velocity limits while a boom raising operation signal is being output from the control lever devices.