Abstract: Provided is a work machine which can increase the operation speed of an actuator by a regeneration function while securing the position control accuracy of the actuator. A controller is configured to calculate a regeneration flow rate on the basis of an input amount of an operation lever and a target actuator flow rate, subtract the regeneration flow rate from the target actuator flow rate to calculate a target actuator supply flow rate, calculate a target flow rate control valve opening amount on the basis of the target actuator supply flow rate, calculate a target pump flow rate that is equal to or higher than a total target actuator supply flow rate, control a selector valve on the basis of the input amount of the operation lever, control a flow rate control valve according to the target flow rate control valve opening amount, and control a hydraulic pump according to the target pump flow rate.

Abstract: To provide a work machine that makes it possible to drive actuators faster and more accurately by supplying flows to the actuators accurately at target rates without depending on load variations in a case where the machine body is controlled automatically by command inputs of a controller, while high operability is ensured for manual operation by an operator. In a case where a machine control function is cancelled via a machine control switch, a controller cancels limitation of the flow rate of a hydraulic fluid supplied to a plurality of directional control valves, the limitation being performed by the auxiliary flow rate control devices, and in a case where the machine control function is selected via the machine control switch, the controller causes the auxiliary flow rate control devices to limit the flow rate of the hydraulic fluid supplied to the plurality of directional control valves.

Abstract: There is provided a work machine which can improve accuracy of control of an actuator when a pressure difference between a hydraulic pump and the actuator is large and the demanded flow rate of the actuator is small. An auxiliary flow rate controller is configured such that an opening area of a main valve changes between a maximum opening area and zero according to the opening area of a pilot variable restrictor when the opening area of the pilot variable restrictor is equal to or more than a predetermined opening area and that the opening area of the main valve is zero irrespective of the opening area of the pilot variable restrictor when the opening area of the pilot variable restrictor is less than the predetermined opening area.

Abstract: A work machine that can keep the control accuracy of actuators irrespective of temperature variation of a hydraulic operating fluid that passes through flow rate controllers that control the flow rates of supply to the actuators is provided. For this purpose, the flow rate controllers each have a valve body that is disposed on a main hydraulic line connecting a delivery line of a hydraulic pump and the actuator and that moves according to an operation pressure from a solenoid proportional pressure reducing valve, a sampling hydraulic line that branches from the main hydraulic line, and a temperature sensor set on the sampling hydraulic line. The controller is configured to correct a command electrical signal to the solenoid proportional pressure reducing valve according to a signal from the temperature sensor.

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.

Abstract: A first torque control proportional electromagnetic valve (37) is connected through a first torque control line (41) to a third pressure receiving chamber (32D) in a first torque control regulator (32). A second torque control proportional electromagnetic valve (38) is connected through a second torque control line (42) to a third pressure receiving chamber (35D) in a second torque control regulator (35). The first and second torque control proportional electromagnetic valves (37, 38) are controlled by a controller 47. A switching valve (48) is provided between the first torque control line (41) and the second torque control line (42). The switching valve (48) supplies an output pressure of the first torque control proportional electromagnetic valve (37) to the third pressure receiving chamber (35D) in the second torque control regulator (35) at the time of driving hydraulic motors (2B, 2C) for left side and right side traveling.

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.

Abstract: A construction machine that precisely enables derivation of the operation characteristics of hydraulic actuators in a high-velocity area with less calibration operation is provided. A controller (10) has a calibration mode in which the controller (10) derives operation characteristics (?(xs)) representing a relation among a spool position (xs) of a meter-in valve (8a1), an operation velocity (Va) of a hydraulic actuator (4a), and a differential pressure (?P) across the meter-in valve (8a1), and is configured to, in a case where the spool position (xs) of the meter-in valve (8a1) has changed in a direction to increase the opening area of the meter-in valve (8a1) in the calibration mode, output a command signal to increase the opening area of a bleed-off valve (8b1) to a bleed-off solenoid proportional pressure-reducing valve (8b2) as a command signal to reduce the differential pressure (?P).

Abstract: To provide a construction machine that can highly precisely control branch flows from a hydraulic pump to a plurality of hydraulic actuators without being affected by load conditions. A controller (100) has a meter-out valve control section (140) configured to calculate a target opening area of a second meter-out valve (65a) (65b) according to a pressure difference between a supply pressure and a second meter-in pressure, or calculate a target opening area of a first meter-out valve (55a) (55b) according to a pressure difference between the supply pressure and the first meter-in pressure.

Abstract: A first torque control proportional electromagnetic valve (37) is connected through a first torque control line (41) to a third pressure receiving chamber (32D) in a first torque control regulator (32). A second torque control proportional electromagnetic valve (38) is connected through a second torque control line (42) to a third pressure receiving chamber (35D) in a second torque control regulator (35). The first and second torque control proportional electromagnetic valves (37, 38) are controlled by a controller 47. A switching valve (48) is provided between the first torque control line (41) and the second torque control line (42). The switching valve (48) supplies an output pressure of the first torque control proportional electromagnetic valve (37) to the third pressure receiving chamber (35D) in the second torque control regulator (35) at the time of driving hydraulic motors (2B, 2C) for left side and right side traveling.

Abstract: A work machine capable of driving each actuator more speedily and more accurately by ensuring high operability in a case of operator's manual operation, while accurately supplying a hydraulic fluid at a target flow rate to the actuator without depending on a load fluctuation in a case of automatic control over a machine body in response to a command input from a controller is provided. The controller controls a plurality of auxiliary flow controllers in such a manner that supply flow rates to a plurality of directional control valves from hydraulic pumps either fluctuate in response to load fluctuations of a plurality of hydraulic actuators when an area limiting control function invalidation instruction is issued, or do not fluctuate in response to the load fluctuations of the plurality of hydraulic actuators when an area limiting control function validation instruction is issued.

Abstract: A hydraulic excavator includes: a multijoint type front implement that is configured by coupling a plurality of driven members including a bucket; inertial measurement units that detect posture information about the plurality of driven members; and a calibration value computing section that computes calibration parameters used in calibration of detection results of the inertial measurement units; and a work position computing section that computes a relative position of the bucket to the machine body on the basis of the detection results of the inertial measurement units and the computation result of the calibration value computing section, and the calibration value computing section computes the calibration parameters on the basis of the detection results of the inertial measurement units in a plurality of postures of the front implement in which a reference point set on any of the plurality of driven members in advance matches a reference position.

Abstract: A construction machine that precisely enables derivation of the operation characteristics of hydraulic actuators in a high-velocity area with less calibration operation is provided. A controller (10) has a calibration mode in which the controller (10) derives operation characteristics (?(xs)) representing a relation among a spool position (xs) of a meter-in valve (8a1), an operation velocity (Va) of a hydraulic actuator (4a), and a differential pressure (?P) across the meter-in valve (8a1), and is configured to, in a case where the spool position (xs) of the meter-in valve (8a1) has changed in a direction to increase the opening area of the meter-in valve (8a1) in the calibration mode, output a command signal to increase the opening area of a bleed-off valve (8b1) to a bleed-off solenoid proportional pressure-reducing valve (8b2) as a command signal to reduce the differential pressure (?P).

Abstract: A hydraulic oil resupply device (40) is provided between first accumulators (15F, 15R) in a manual braking operation circuit (11) and a second accumulator (25) in an automatic brake circuit (24). The hydraulic oil resupply device (40) resupplies hydraulic oil accumulated in the second accumulator (25) to the first accumulators (15F, 15R) at the operating of a manual braking operation by an operator. This configuration can suppress a rising speed of a brake pressure at the manual operation braking from being slow. Accordingly, in a vehicular brake system, it is possible to enhance a braking capability by the manual braking operation and improve the reliability.

Abstract: To provide a construction machine that can highly precisely control branch flows from a hydraulic pump to a plurality of hydraulic actuators without being affected by load conditions. A controller (100) has a meter-out valve control section (140) configured to calculate a target opening area of a second meter-out valve (65a) (65b) according to a pressure difference between a supply pressure and a second meter-in pressure, or calculate a target opening area of a first meter-out valve (55a) (55b) according to a pressure difference between the supply pressure and the first meter-in pressure.

Abstract: A work machine capable of driving each actuator more speedily and more accurately by ensuring high operability in a case of operator's manual operation, while accurately supplying a hydraulic fluid at a target flow rate to the actuator without depending on a load fluctuation in a case of automatic control over a machine body in response to a command input from a controller is provided.

Abstract: A hydraulic circuit (11) of a hydraulic excavator (1) is provided with a main hydraulic circuit (11A) including a boom cylinder (5D), a pilot hydraulic circuit (11B) for operating the boom cylinder (5D) and a recovery hydraulic circuit (11C) including an accumulator (29). In this case, the recovery hydraulic circuit (11C) is provided with a recovery control valve (31) that recovers pressurized oil discharged from the boom cylinder (5D) to the accumulator (29), a main supply control valve (34) for supplying pressurized oil accumulated in the accumulator (29) to the main hydraulic circuit (11A) and a pilot supply control valve (37) for supplying pressurized oil accumulated in the accumulator (29) to the pilot hydraulic circuit (11B).

Abstract: It is an object of the present invention to provide a hydraulic drive system that effectively utilizes a hydraulic fluid accumulated in an accumulator to make it possible to achieve a substantial improvement in terms of efficiency for a work machine as a whole. A hydraulic drive system includes: a first hydraulic pump; a first hydraulic actuator driven by being supplied with a hydraulic fluid from the first hydraulic pump; a first line for supplying the hydraulic fluid from the first hydraulic pump to the first hydraulic actuator; a first pump flow adjustment device installed in the first line, the first pump flow adjustment device being configured to adjust; a first hydraulic accumulator for accumulating the hydraulic fluid delivered from the first hydraulic pump; and a first accumulation flow adjustment device configured to adjust the flow of the hydraulic fluid from the first hydraulic pump to the first hydraulic accumulator.

Abstract: To provide a work machine that makes it possible to drive actuators faster and more accurately by supplying flows to the actuators accurately at target rates without depending on load variations in a case where the machine body is controlled automatically by command inputs of a controller, while high operability is ensured for manual operation by an operator. In a case where a machine control function is cancelled via a machine control switch, a controller cancels limitation of the flow rate of a hydraulic fluid supplied to a plurality of directional control valves, the limitation being performed by the auxiliary flow rate control devices, and in a case where the machine control function is selected via the machine control switch, the controller causes the auxiliary flow rate control devices to limit the flow rate of the hydraulic fluid supplied to the plurality of directional control valves.

Abstract: It is an object of the present invention to provide a hydraulic drive system that effectively utilizes a hydraulic fluid accumulated in an accumulator to make it possible to achieve a substantial improvement in terms of efficiency for a work machine as a whole. A hydraulic drive system includes: a first hydraulic pump; a first hydraulic actuator driven by being supplied with a hydraulic fluid from the first hydraulic pump; a first line for supplying the hydraulic fluid from the first hydraulic pump to the first hydraulic actuator; a first pump flow adjustment device installed in the first line, the first pump flow adjustment device being configured to adjust; a first hydraulic accumulator for accumulating the hydraulic fluid delivered from the first hydraulic pump; and a first accumulation flow adjustment device configured to adjust the flow of the hydraulic fluid from the first hydraulic pump to the first hydraulic accumulator.