公开(公告)号：US20200173145A1

公开(公告)日：2020-06-04

申请号：US16082748

申请日：2017-03-27

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Yuichi OGAWA ,  Seiji HIJIKATA ,  Masatoshi HOSHINO

IPC: E02F9/22 ,  F15B21/14 ,  F15B11/08

Abstract: Provided is a work machine hydraulic control system capable of detecting abnormality in a pump output power switching device independently of the abnormality state of the pump output power switching device.A hydraulic control system of a hydraulic excavator is equipped with an accumulator 21 connected to a hydraulic line 25A between a pilot pump 17 and a pilot valve 20, an unloading valve 27 that is a pump output power switching device, a pressure sensor 29 detecting the pressure of the hydraulic fluid supplied to the pilot valve 20, and a controller 30 having a pump output power control section 31 switching the unloading valve 27 in accordance with the pressure detected by the pressure sensor 29. The controller 30 further has an abnormality determination section 32 that computes a command continuation time in a state in which a command output to the unloading valve 27 is not changed. In the case where this command continuation time is not less than a predetermined value, it determines that the unloading valve 27 is abnormal, and outputs the determination result.

公开(公告)号：US20190186106A1

公开(公告)日：2019-06-20

申请号：US16327928

申请日：2017-03-29

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Yuichi OGAWA ,  Seiji HIJIKATA ,  Masatoshi HOSHINO ,  Kiwamu TAKAHASHI ,  Kouji ISHIKAWA

IPC: E02F9/22 ,  E02F3/32 ,  E02F9/20 ,  E02F3/42 ,  E02F3/43 ,  F15B11/10 ,  F15B1/02 ,  F15B1/033

Abstract: A work machine including: a hydraulic cylinder 20 configured to drive a work implement 3; a control valve 22 configured to connect a delivery line of a hydraulic pump 21 switchingly to a bottom fluid chamber and a rod fluid chamber of the hydraulic cylinder 20 and a tank; a pilot pump 23 configured to output a pilot pressure to drive the control valve 22; an engine 24 configured to drive the hydraulic pump 21 and the pilot pump 23; and an accumulator 26 configured to accumulate a return hydraulic fluid from the hydraulic cylinder 20 is provided with: a bypass line 41 configured to connect the bottom fluid chamber of the hydraulic cylinder 20 and a delivery line 21a of the hydraulic pump 21 by bypassing the control valve 22 and be provided with the accumulator 26 thereon; a pressure-accumulation control valve 27 provided between the bottom fluid chamber of the hydraulic cylinder 20 and the accumulator 26; a release control valve 28 provided between the accumulator 26 and the delivery line 21a; and a hydraulic system controller 30 configured to open the release control valve 28 if an engine revolution speed N becomes lower than a set value Ns.

公开(公告)号：US20210332562A1

公开(公告)日：2021-10-28

申请号：US17273959

申请日：2019-11-26

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Yuichi OGAWA ,  Shinya IMURA

IPC: E02F9/22

Abstract: There is provided a work machine that is capable of realizing operability and energy saving ability that are equivalent to those of work machines that have a joint line to be used during swinging/boom raising operation, without incorporating a joint line for supplying a pressurized fluid from a second pump to a bottom-side chamber of a boom cylinder. The controller is configured to compute a hypothetical flow rate representing a flow rate in a hypothetical joint line, compute a first pump provisional target flow rate on the basis of an operation amount of a boom operation device, compute a second pump provisional target flow rate on the basis of an operation amount of a swing operation device, compute a first pump final target flow rate by adding the hypothetical flow rate to the first pump provisional target flow rate, and compute a second pump final target flow rate by subtracting the hypothetical flow rate from the second pump provisional target flow rate.

公开(公告)号：US20210131452A1

公开(公告)日：2021-05-06

申请号：US16492368

申请日：2018-05-18

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Kiwamu TAKAHASHI ,  Seiji HIJIKATA ,  Masatoshi HOSHINO ,  Yuichi OGAWA ,  Kouji ISHIKAWA

IPC: F15B1/08 ,  F15B21/14 ,  E02F9/22

Abstract: A controller (45) is provided with an elapse time measuring section (47A) that measures an elapse time (tx) elapsed since an initial use of an accumulator (29) based upon a reset signal from a reset switch (44), a number-of-operations measuring section (47B) that measures a number of operations of the accumulator (29), that is, a number (N) of boom lowering operations after a reset, based upon a detection signal from an accumulator side pressure sensor (39), a gas permeation amount estimating section (47C) that estimates an estimation gas permeation amount (Qloss) of the accumulator (29), a sealed gas pressure estimating section (47D) that finds an estimation sealed gas pressure (Pgs) of a gas chamber (29B) of the accumulator (29), and an accumulator degradation determining section (47E) that determines a degradation condition of the accumulator (29) and outputs the determination result.

公开(公告)号：US20200040547A1

公开(公告)日：2020-02-06

申请号：US16492433

申请日：2017-12-26

Applicant: Hitachi Construction Machinery Co., Ltd.

Inventor： Yuichi OGAWA ,  Shinya IMURA

IPC: E02F3/42 ,  E02F3/32 ,  E02F9/22 ,  E02F3/43 ,  E02F9/26 ,  E02F9/20 ,  F15B9/03 ,  F15B9/04 ,  F15B11/024

Abstract: It is made possible to suppress variations of the speed of an actuator into which a regeneration flow rate flows, regardless of variations of the regeneration flow rate caused by posture changes of the front part and to enhance the operability when the front part moves in the free fall direction, and hydraulic fluid discharged from an actuator driving the front part is regenerated. Accordingly, a controller 19 of a hydraulic system is provided with a regeneration control calculation section 19b, and a pump flow rate control calculation section 19c, and when the regeneration control calculation section controls a regeneration valve 12 to perform regeneration, the pump flow rate control calculation section controls a pump flow rate regulation device 20 to increase the delivery flow rate of a hydraulic pump 1 as the angle of an arm 16 approaches the vertically downward direction based on posture information about the arm 16 acquired by an inertial measurement unit 31.

公开(公告)号：US20250163678A1

公开(公告)日：2025-05-22

申请号：US18842448

申请日：2022-03-30

Applicant: HITACHI CONSTRUCTION MACHINERY CO., LTD.

Inventor： Masamichi ITO ,  Shinjiro YAMAMOTO ,  Yuichi OGAWA

IPC: E02F9/20

Abstract: Provided is an automated control system for a work machine capable of suppressing deterioration of the workability in automated work caused by instability of the ground for the work machine. An automated traveling control section 703 performs automated traveling of the work machine; an automated work control section (automated excavation control section 704) performs automated work of the work machine; and a stability determination section 702 determines stability of ground for the work machine. When execution of automated traveling control by the automated traveling control section 703 is to be followed by execution of automated work control by the automated work control section (automated excavation control section 704), stability determination by the stability determination section 702 is executed before executing the automated work control, and automated control of the work machine is executed on the basis of a determination result obtained by the stability determination section 702.