Hitachi Construction Machinery Co., Ltd.

Masamichi Itou

Shinya Imura

Yasutaka Tsuruga

Akihiro Narazaki

Teruki Igarashi

Shinjiro Yamamoto

Hiroki Ishii

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.

Hydraulic excavator

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 valvedisposed between a secondary portof an operation deviceand a flow control valveand between a proportional solenoid valveand the flow control valveand a selector valvedisposed between a secondary portof the operation deviceand the flow control valveand between a proportional solenoid valveand the flow control valve. A controllerswitches the selector valvesandto either one of a first position and a second position on the basis of signals from pressure sensorsandand pressure sensorsandand target operation set in advance regarding the selector valvesand

Work machine

Growing community of inventors

Toride, Japan

Masamichi Itou