公开(公告)号：US20210079624A1

公开(公告)日：2021-03-18

申请号：US16979423

申请日：2019-09-26

Applicant: HITACHI CONSTRUCTION MACHINERY CO., LTD.

Inventor： Katsuaki KODAKA ,  Ryohei FUKUCHI ,  Kazuhiko MIZOGUCHI ,  Naoki HAGIWARA

IPC: E02F9/22 ,  E02F9/20 ,  E02F9/12 ,  E02F9/26 ,  E02F9/24 ,  F15B15/26 ,  F15B15/02 ,  F15B15/20

Abstract: To provide a work machine that can stop unexpected operation of actuators faster than it actually occurs even if unintended operation occurs at the time of gate lock lever switching that leads to such unexpected operation. In the work machine, a controller switches a lock valve from a lock position to a release position in a case where a lock operation device is operated from a permission position to a prohibition position; decides, on the basis of a result of detection by a pressure sensor, whether or not a pilot hydraulic fluid has been output from a pilot valve until first time elapses after the lock valve is switched to the release position; keeps the lock valve at the lock position if it is decided that the pilot hydraulic fluid has been output until the first time elapses; and switches the lock valve from the lock position to the release position if it is decided that the pilot hydraulic fluid has not been output until the first time elapses, and second time elapses.

公开(公告)号：US20240150995A1

公开(公告)日：2024-05-09

申请号：US18280718

申请日：2022-08-31

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Ryohei FUKUCHI ,  Shota ISHIDA

IPC: E02F3/43 ,  E02F3/32 ,  E02F3/42

CPC classification number: E02F3/435 ,  E02F3/32 ,  E02F3/425

Abstract: A construction machine including a solenoid valve that reduces a boom lowering pilot pressure for a second directional control valve and a controller that controls the solenoid valve is provided. The controller computes a first opening degree command value in such a manner that a communication area between a boom lowering pressure reducing valve and a pressure receiving chamber of the second directional control valve decreases in association with a bottom pressure of a boom cylinder, computes a second opening degree command value in such a manner that the communication area increases in association with increase in a boom lowering operation amount, decides a minimum opening degree command value as an opening degree command value of the solenoid valve when an elapsed time after boom raising operation is shorter than a set time and decides a minimum selected value of the first and second opening degree command values as the opening degree command value of the solenoid valve when the elapsed time is equal to or longer than the set time, and outputs a command signal according to the decided opening degree command value to the solenoid valve.

公开(公告)号：US20240376691A1

公开(公告)日：2024-11-14

申请号：US18688848

申请日：2023-03-30

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Teruki IGARASHI ,  Hiroaki TANAKA ,  Ryohei FUKUCHI ,  Yusuke SUZUKI

IPC: E02F9/22 ,  E02F9/26 ,  F15B13/044

Abstract: A work machine includes a flow control valve that controls the flow rate of a hydraulic operating fluid supplied from a hydraulic pump to a hydraulic cylinder, a solenoid valve that generates an operation pressure for operating the flow control valve, and a controller. The controller executes learning processing of changing in a stepwise manner the operation pressure generated by the solenoid valve, sensing the pressure of the hydraulic cylinder, and storing the operation pressure when the pressure of the hydraulic cylinder has become a reference value, as a learning result operation pressure. The controller calculates a differential pressure across the flow control valve and computes a target opening area of the flow control valve on the basis of the differential pressure across the flow control valve and a target flow rate of the hydraulic operating fluid that passes through the flow control valve. The controller computes a target value of the operation pressure generated by the solenoid valve, on the basis of an opening characteristic table, the target opening area, and the learning result operation pressure, and controls the solenoid valve on the basis of the target value of the operation pressure.

公开(公告)号：US20240254728A1

公开(公告)日：2024-08-01

申请号：US18282925

申请日：2022-03-11

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Ryohei FUKUCHI ,  Katsuaki KODAKA ,  Mitsuhiko KANEHAMA ,  Teruki IGARASHI

IPC: E02F9/22 ,  E02F3/32

CPC classification number: E02F9/2292 ,  E02F9/2242 ,  E02F3/32

Abstract: A work machine includes: a first pump and a second pump that are driven by an engine; a hydraulic actuator driven by a hydraulic working fluid supplied from the first pump; a control valve that controls a flow of the hydraulic working fluid supplied to the hydraulic actuator; a solenoid valve that reduces a pressure of the second pump to generate a pilot pressure for operating the control valve; a controller that controls the solenoid valve; an engine operating section that enables operation for activating the engine; and a rotation speed sensor that senses a rotation speed of the engine. The controller applies a drive current to the solenoid valve to drive the solenoid valve when a current application condition is established, the current application condition including that it is assessed, on the basis of a sensing result of the rotation speed sensor, that the engine is in a stopped state, and including that ON operation of the engine operating section is performed in a state where activation operation is not performed by the engine operating section.

公开(公告)号：US20240167250A1

公开(公告)日：2024-05-23

申请号：US18279224

申请日：2022-09-08

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Teruki IGARASHI ,  Ryohei FUKUCHI ,  Yusuke SUZUKI ,  Hiroaki TANAKA ,  Mitsuhiko KANEHAMA

IPC: E02F9/22 ,  E02F3/32 ,  F15B19/00

CPC classification number: E02F9/2228 ,  E02F3/32 ,  E02F9/2267 ,  F15B19/005

Abstract: A work machine includes: a work device including a plurality of hydraulic actuators and a plurality of driving target members; a posture sensor that senses posture information of the work device; a control valve unit that controls flows of hydraulic operating fluid supplied from the hydraulic pump to the plurality of hydraulic actuators; a plurality of solenoid valves that generate pilot pressure for driving the control valve unit; and a controller that computes a command value of the pilot pressure to be generated by the solenoid valves, and outputs a control signal corresponding to the command value to the solenoid valves. The controller computes a gravitational direction component of an action direction vector of the driving target members on the basis of the posture information sensed by the posture sensor, corrects the command value of the pilot pressure on the basis of the gravitational direction component of the action direction vector when the command value exceeds a predetermined pressure, and outputs the control signal corresponding to the command value after the correction to the solenoid valves.