To prevent increase/decrease in pump flow rate due to load variation with change in the posture of a work attachment and improve the operability in arm pushing operation. A hydraulic excavator 1 with a front mechanism including an arm 33 driven by a hydraulic actuator 43 through operation of an operating lever 50 includes: first and second angle sensors 37 and 38 which detect the posture of the arm 33; and a controller 49 which, when the posture of the arm 33 is at a remoter side from an upperstructure 20 than a preset position and the position of a bucket 35 is adjusted from a maximum or nearly maximum preset operation amount of the operating lever 50 in arm pushing operation by the operating lever 50, changes the flow rate characteristic of pressure oil in relation to discharge pressure of a hydraulic pump 41 for supplying pressure oil to the hydraulic actuator 43, to characteristic PTS with a higher flow rate than flow rate characteristic PT at the time of operation with an operation amount other than the above operation amount, to drive the hydraulic pump 41.

Provided are an energy regeneration device which can regenerate energy of a working fluid discharged from an actuator while controlling a flow rate of the working fluid, and a work machine including the foregoing device. The regeneration device (100) includes a boom cylinder (20), an inertial fluid container (102), an oil tank (110), an accumulator (105), a low-pressure-side opening/closing device (103), and a high-pressure-side opening/closing device (104). A calculation unit (151) calculates a duty ratio for opening/closing the low-pressure-side opening/closing device (103) and the high-pressure-side opening/closing device (104) in accordance with a desired flow rate of a working fluid discharged from the boom cylinder (20). A regeneration control unit (153) selects alternately the low-pressure-side opening/closing device (103) and the high-pressure-side opening/closing device (104) as a destination with which the inertial fluid container (102) communicates in accordance with the calculated duty ratio, and supplies a discharged working fluid to an accumulator (105).

A hydraulic system includes a hydraulic mechanism that includes a first and a second chamber. The hydraulic system includes a control valve fluidly connected to the first chamber and a pressure sensor that is configured to measure the fluid pressure in the first chamber. The hydraulic system includes a processing unit connected to the control valve. The processing unit is configured to control a hydraulic fluid flow rate to and from the first chamber of the hydraulic mechanism via the control valve to provide a shock absorption response. The hydraulic fluid flow rate is based at least in part on a pressure measurement received from the pressure sensor. The shock absorption response is based on a simulated hydraulic accumulator.

A control method controls a movable member of an excavator including a movable member holding a load, an actuator with electric motor and static brake, a control unit and a motion sensor unit. The static brake and electric motor generate respectively an upper threshold brake force and an upper threshold motor force. An immobilization operation provides that the static brake generates the upper threshold brake force and the electric motor is stopped. A slippage detection operation provides that the control unit detects whether an electric actuator is moving despite the static brake. If the electric actuator is moving, a motor energizing operation provides that the electric motor generates a motor force equal or superior to upper threshold brake force in a direction opposite to the slippage direction. After energizing the motor, a brake release operation provides that the control unit releases the static brake.

The construction machine includes: a work implement driven by a first hydraulic actuator and a second hydraulic actuator; a first directional control valve controlling a flow rate and a direction of a hydraulic fluid supplied to the first hydraulic actuator; a first speed-up directional control valve provided in a second pump line and controlling a flow rate and a direction of a hydraulic fluid supplied to the first hydraulic actuator; a second directional control valve controlling a flow rate and a direction of a hydraulic fluid supplied to the second hydraulic actuator; an excavation load sensor that detects an excavation load imposed on the work implement; and a first speed-up control section that drives the first speed-up directional control valve, and the first speed-up control section is configured to control a driving amount of the first speed-up directional control valve in response to the excavation load.

A hydraulic system of construction machinery includes: a boom cylinder divided; a first boom hydraulic line serving to supply a hydraulic oil to the boom cylinder during an ascending operation of a boom; a second boom hydraulic line serving to supply the hydraulic oil to the boom cylinder during a descending operation of the boom; a regeneration line serving so that the hydraulic oil discharged from the head side of the boom cylinder flows during the descending operation of the boom; a circulation line connected to the second boom hydraulic line; an accumulator connected to the regeneration line and serving to accumulate the hydraulic oil discharged from the boom cylinder; a boom regeneration valve including a first regeneration spool and a second regeneration spool; and a control unit serving to adjust opening areas of the first regeneration spool and the second regeneration spool during the descending operation of the boom.

A shovel that corrects the movement of an attachment regardless of the operating state of the attachment by an operator is provided. The shovel includes a traveling body, a turning body turnably mounted on the traveling body, an attachment attached to the turning body, a hydraulic actuator configured to drive the attachment, and a controller. The controller is configured to control the hydraulic actuator to minimize a change in orientation of the traveling body or of the turning body, in response to a change in moment caused by an aerial movement of the attachment.

A variable displacement pump supplies hydraulic oil to turning motor via a turning control valve; pair of supply/discharge lines connect turning motor and turning control valve; a pair of make-up lines connect pair of supply/discharge lines to tank, each line having check valve; turning operation device including operating lever and outputting operation signal corresponding to inclination angle of operating lever; a flow rate adjuster adjusts tilting angle of pump; and controller controls flow rate adjuster, such that tilting angle of pump increases in accordance with increase in operation signal outputted from turning operation device. Controller: turning acceleration and at time of constant speed turning, controls flow rate adjuster such that discharge flow rate of pump changes on first regulation line; turning deceleration, controls flow rate adjuster such that discharge flow rate of pump changes on second regulation line, second regulation line having slope less than slope of first regulation line.

An attachment monitoring system according to an embodiment includes a working machine, attachments, a measurement unit, a terminal device, and a server device. The working machine includes a working arm. Each of the attachments is attached to a leading end part of the working arm so as to be driven by a fluid pressure. The measurement unit is provided to measure at least one of a vibration and the fluid pressure when each of the attachments identified on the basis of individual identifying information is driven. The terminal device is provided in the working machine to acquire measured results of the measurement unit. The server device collects the measured results of the respective attachments from the terminal device, and analyzes operation states of the respective attachments on the basis of the collected measured results.

A work machine includes a plurality of actuators that drive a work device; a posture sensor that senses postural data about the work device; and a controller having a degree-of-proximity calculating section that computes a degree of proximity that is an index value indicating proximity between an intrusion prohibition region and the work device on the basis of positional data about the intrusion prohibition region and the postural data. A command section executes, when the proximity specified by the degree of proximity is closer than proximity specified by a degree-of-proximity threshold, operating area limiting control to decelerate at least one of the plurality of actuators such that an intrusion of the work device into the intrusion prohibition region is prevented. History of the data about the degree of proximity calculated at the degree-of-proximity calculating section is stored and the degree-of-proximity threshold is altered on the basis of the history data.