Abstract: An electrically driven construction machine is provided in which, in a case where a plurality of electrically driven construction machines operate simultaneously, it is possible to avoid exceeding the allowable electric power that can be output by the electric power receiving facility of a commercial electric power supply. A controller computes an own demanded power Pd1 for driving the plurality of hydraulic actuators, on the basis of operation signals of the operation devices, computes an allowable power as a power limit value usable by the electric motor on the basis of the own demanded power, the demanded powers of the other electrically driven construction machines received through the communication device, and an allowable electric power of the electric power receiving facility of the commercial electric power supply, and controls the electric motor such that a power consumption of the electric motor does not exceed the allowable power.

Abstract: A controller calculates the ratio between the sum of estimated demanded powers of a plurality of first actuators and the sum of estimated demanded powers of a plurality of second actuators, and calculates, on the basis of the ratio, first and second command values for adjusting allocation between a first allowable torque of a first pump and a second allowable torque of a second pump, and first and second regulators adjust the first and second allowable torques, on the basis of first and second output pressures of first and second torque control valves, such that the first and second allowable torques become values to which a predetermined allowable torque is allocated according to the ratio described above, and control the delivery flow rates of the first and second pumps such that the respective consumed torques of the first and second pumps do not become larger than the first and second allowable torques.

Abstract: An upper revolving structure (4) of a hydraulic excavator (1) includes a revolving frame (7), a counterweight (8), an operator's seat (12), a right front cover (17B) disposed from the right side of the operator's seat (12) toward a front end side of the revolving frame (7), a control valve device (18), and an accumulator (21). An accumulator support device (23) is provided between the operator's seat (12) and the right front cover (17B), the accumulator support device (23) is configured by a box (24) providing the inside thereof for an accommodating space (25) and having an opening (26) and a lid member (28) mounted on the box (24) through a hinge member (29) and opened and closed between an open position at which the side of a free end (28D) opens the opening (26) and a closed position at which the side of the free end (28D) closes the opening (26), and the accumulator (21) is mounted on the lid member (28).

Abstract: A controller calculates the ratio between the sum of estimated demanded powers of a plurality of first actuators and the sum of estimated demanded powers of a plurality of second actuators, and calculates, on the basis of the ratio, first and second command values for adjusting allocation between a first allowable torque of a first pump and a second allowable torque of a second pump, and first and second regulators adjust the first and second allowable torques, on the basis of first and second output pressures of first and second torque control valves, such that the first and second allowable torques become values to which a predetermined allowable torque is allocated according to the ratio described above, and control the delivery flow rates of the first and second pumps such that the respective consumed torques of the first and second pumps do not become larger than the first and second allowable torques.

Abstract: A hydraulic drive system for a work machine including a hydraulic energy recovery device that is configured to perform load sensing control and accumulates hydraulic fluid that returns from a hydraulic cylinder in operation of lowering a front work implement into an accumulator includes, in order to prevent, when operation other than operation of lowering the front work implement is to be performed, hydraulic energy accumulated in the accumulator from being consumed uselessly, a regeneration selector valve in a hydraulic line for regenerating the hydraulic fluid accumulated in the accumulator into a hydraulic fluid supply line of a main pump. The regeneration selector valve is controlled such that, only when saturation occurs with the main pump, flow from the accumulator to the hydraulic fluid supply line is permitted.

Abstract: Even where the differential pressure across a directional control valve associated with each actuator is very small, flow dividing control of the plurality of directional control valves can be performed stable, and even where a demanded flow rate suddenly changes at the time of transition from composite action to single action or the like, a sudden change of the flow rate of hydraulic fluid to be supplied to each actuator is prevented to implement superior combined operability. Further, the meter-in loss of the directional control valves can be reduced to implement a high energy efficiency.

Abstract: A hydraulic drive system for a work machine including a hydraulic energy recovery device that is configured to perform load sensing control and accumulates hydraulic fluid that returns from a hydraulic cylinder in operation of lowering a front work implement into an accumulator includes, in order to prevent, when operation other than operation of lowering the front work implement is to be performed, hydraulic energy accumulated in the accumulator from being consumed uselessly, a regeneration selector valve in a hydraulic line for regenerating the hydraulic fluid accumulated in the accumulator into a hydraulic fluid supply line of a main pump. The regeneration selector valve is controlled such that, only when saturation occurs with the main pump, flow from the accumulator to the hydraulic fluid supply line is permitted.

Abstract: Even where the differential pressure across a directional control valve associated with each actuator is very small, flow dividing control of the plurality of directional control valves can be performed stable, and even where a demanded flow rate suddenly changes at the time of transition from composite action to single action or the like, a sudden change of the flow rate of hydraulic fluid to be supplied to each actuator is prevented to implement superior combined operability. Further, the meter-in loss of the directional control valves can be reduced to implement a high energy efficiency.

Abstract: To provide a small hydraulic excavator, which even may have an upperstructure formed such that at least its rear end swings within a body width range and having a limited installation space for devices, that allows an accumulator to be disposed and allows the accumulator to be protected from external force generated during work. The present invention relates to a rear small-swing type mini excavator that includes an accumulator 30 accommodating and recovering potential energy and hydraulic energy used by at least one of drives of an undercarriage 1, an upperstructure 2 formed such that its rear end swings within the body width range of the undercarriage 1, and a working device 3.

Abstract: When a swing motor and a boom cylinder are driven simultaneously, a hydraulic drive system appropriately adjusts a distribution of torques between hydraulic pumps and feeds back a torque actually consumed by the hydraulic pump for actuating the swing motor accurately to the hydraulic pump for actuating the boom cylinder. To that end, when boom raising and swinging are performed simultaneously, the hydraulic drive system corrects an allowable torque of a hydraulic pump 302 that supplies a hydraulic fluid to a swing motor 3c so as to be lowered by a certain ratio, reducing allowable torques of hydraulic pumps 102 and 202 that supply a hydraulic fluid to a boom cylinder 3a by torques consumed by the hydraulic pumps 102 and 202 that supply a hydraulic fluid to the swing motor 3c.

Abstract: When a swing motor and a boom cylinder are driven simultaneously, a hydraulic drive system appropriately adjusts a distribution of torques between hydraulic pumps and feeds back a torque actually consumed by the hydraulic pump for actuating the swing motor accurately to the hydraulic pump for actuating the boom cylinder. To that end, when boom raising and swinging are performed simultaneously, the hydraulic drive system corrects an allowable torque of a hydraulic pump 302 that supplies a hydraulic fluid to a swing motor 3c so as to be lowered by a certain ratio, reducing allowable torques of hydraulic pumps 102 and 202 that supply a hydraulic fluid to a boom cylinder 3a by torques consumed by the hydraulic pumps 102 and 202 that supply a hydraulic fluid to the swing motor 3c.

Abstract: Flow control over a hydraulic pump and flow dividing control of a plurality of directional control valves associated with actuators can stably be exercised even in a case in which differential pressures across the directional control valves are quite low, an abrupt change in a flow rate of the hydraulic fluid supplied to each actuator is prevented and excellent combined operability is realized even in an abrupt change in a demanded flow rate at a time of transition from a combined operation to a sole operation, and realizing excellent combined operability, and a meter-in loss in each directional control valve is reduced to realize high energy efficiency.

Abstract: In a hydraulic drive system for an electrically driven hydraulic work machine that executes flow rate control of a hydraulic pump by controlling a rotation speed of an electric motor to drive a hydraulic pump to supply a hydraulic fluid to a plurality of actuators, and power consumed by the electric motor reliably limited within a range of preset maximum allowable power without unnecessary degradation of responsiveness of the electric motor. To this end, a controller includes a maximum angular acceleration limitation section (allowable rate computation section and rate limitation section), computes hydraulic power consumed by a main pump, computes a maximum angular acceleration allowed for an electric motor on the basis of a magnitude of the hydraulic power and a preset maximum allowable power consumable by the electric motor, and limits an angular acceleration of the electric motor not to exceed the maximum angular acceleration.

Abstract: Flow control over a hydraulic pump and flow dividing control of a plurality of directional control valves associated with actuators can stably be exercised even in a case in which differential pressures across the directional control valves are quite low, an abrupt change in a flow rate of the hydraulic fluid supplied to each actuator is prevented and excellent combined operability is realized even in an abrupt change in a demanded flow rate at a time of transition from a combined operation to a sole operation, and realizing excellent combined operability, and a meter-in loss in each directional control valve is reduced to realize high energy efficiency.

Abstract: An electrically driven construction machine is provided in which, in a case where a plurality of electrically driven construction machines operate simultaneously, it is possible to avoid exceeding the allowable electric power that can be output by the electric power receiving facility of a commercial electric power supply as an external electric power supply while distributing supplied electric power without a work imbalance between different machine bodies according to the respective demanded powers of the plurality of electrically driven construction machines thereby make it possible to perform work efficiently within an allowable electric power of the electric power receiving facility.

Abstract: An upper revolving structure (4) of a hydraulic excavator (1) includes a revolving frame (7), a counterweight (8), an operator's seat (12), a right front cover (17B) disposed from the right side of the operator's seat (12) toward a front end side of the revolving frame (7), a control valve device (18), and an accumulator (21). An accumulator support device (23) is provided between the operator's seat (12) and the right front cover (17B), the accumulator support device (23) is configured by a box (24) providing the inside thereof for an accommodating space (25) and having an opening (26) and a lid member (28) mounted on the box (24) through a hinge member (29) and opened and closed between an open position at which the side of a free end (28D) opens the opening (26) and a closed position at which the side of the free end (28D) closes the opening (26), and the accumulator (21) is mounted on the lid member (28).

Abstract: In a hydraulic drive system for an electrically driven hydraulic work machine that executes flow rate control of a hydraulic pump by controlling a rotation speed of an electric motor to drive a hydraulic pump to supply a hydraulic fluid to a plurality of actuators, and power consumed by the electric motor reliably limited within a range of preset maximum allowable power without unnecessary degradation of responsiveness of the electric motor. To this end, a controller includes a maximum angular acceleration limitation section (allowable rate computation section and rate limitation section), computes hydraulic power consumed by a main pump, computes a maximum angular acceleration allowed for an electric motor on the basis of a magnitude of the hydraulic power and a preset maximum allowable power consumable by the electric motor, and limits an angular acceleration of the electric motor not to exceed the maximum angular acceleration.

Abstract: A hydraulic drive system for an electrically-driven hydraulic work machine makes it possible to make a rated voltage of various electric equipment such as power storage devices common to one of an electrically-driven hydraulic work machine that is capable of being operated with lower horsepower and to prevent that only a power storage situation of one of the plurality of power storage devices significantly degrades together with operation of the electrically-driven hydraulic work machine and besides, to extend a time period within which each of actuators of the electrically-driven hydraulic work machine can obtain a predetermined speed. Accordingly, a controller 50 includes a virtual limitation torque calculation section 51 and electric motor rotational speed control sections 52 and 53.

Abstract: In a hydraulic drive system of a work machine which drives a plurality of actuators using three or more pumps, for an operation not including traveling, a highly efficient combined operation in a front implement and excellent combined operability of a swing and the front implement are enabled, while for an operation including traveling, a highly efficient traveling operation and a highly efficient combined operation of traveling and the front implement are enabled, and a sufficient operation speed of the front implement is achieved. To this end, each of the flow rates of the first, second, and third pumps (101, 201, 301) can be controlled independently by performing the load sensing control, and in a combined operation for driving a boom (511) and an arm (512), ether one of them is driven by the first pump while the other one is driven by the second pump, and the swing is driven by the third pump.

Abstract: To provide a small hydraulic excavator, which even may have an upperstructure formed such that at least its rear end swings within a body width range and having a limited installation space for devices, that allows an accumulator to be disposed and allows the accumulator to be protected from external force generated during work. The present invention relates to a rear small-swing type mini excavator that includes an accumulator 30 accommodating and recovering potential energy and hydraulic energy used by at least one of drives of an undercarriage 1, an upperstructure 2 formed such that its rear end swings within the body width range of the undercarriage 1, and a working device 3.