Hitachi Construction Machinery Co., Ltd.

Hitachi Construction Machinery Tierra Co., Ltd.

Yuichi Ogawa

Kiwamu Takahashi

Takeshi Ishii

Masatoshi Hoshino

Seiji Hijikata

Seiichi Kihara

Shinya Imura

Kouji Ishikawa

Taihei Maehara

In a hydraulic drive system used for an electrically driven hydraulic work machine that drives a hydraulic pump by an electric motor and supplies a hydraulic fluid to plural actuators to carry out work, the power consumption of the hydraulic pump is kept from exceeding a value decided in advance. For this purpose, a controller calculates target power to be consumed by the hydraulic pump on the basis of the capacity of the hydraulic pump, the delivery pressure of the hydraulic pump sensed by a pressure sensor, and a target revolution speed of the electric motor, and limits the target revolution speed of the electric motor in such a manner that the target power falls within a range of the maximum allowable power.

Electrically driven hydraulic work machine

It is made possible to perform power reduction control during non-operation of control levers, and suppress power consumption of a power source when a control lever is moved by an erroneous operation, and thus reduce energy consumption. Accordingly, a controllerperforms the power reduction control when a non-operation time exceeds a set time after a transition is made from a state in which at least one control lever is operated to a non-operation state in which none of the control levers is operated, and the controllercancels the power reduction control when at least one control lever is operated in a state in which the power reduction control is performed. In addition, the set time is set as a first set time Tthwhen an operation time until at least one of leversandmakes a transition to the non-operation state is longer than a monitoring time Tth, and the set time is set as a second set time Tthshorter than the first set time Tthwhen the operation time until the at least one control lever makes a transition to the non-operation state is shorter than the monitoring time Tth

Construction machine

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. Thus, the present invention efficiently performs torque allocation between the first and second pumps (a plurality of hydraulic pumps) to thereby enable effective utilization of the torque generated by the prime mover without wasting the torque.

Hydraulic drive system for construction machine

To reduce an increase in the electric power consumption of an electric motor according to the state of an electric power source at the start of driving of an actuator, and make it possible to use devices in an appropriate state in an electrically driven hydraulic construction machine including a driving system that drives a hydraulic pump by using the electric motor. For this purpose, a controllersets a target relief pressure of a relief valveto a normal relief pressure Pn (first relief pressure) when an operation lever deviceis not being operated and a storage amount SOC(t) of a battery(the state quantity of an electric power source) is equal to or larger than a threshold S, and sets the target relief pressure to a reduced relief pressure Pr(t) (second relief pressure) lower than the normal relief pressure Pn (first relief pressure) when the operation lever deviceis not being operated, and the storage amount SOC(t) of the battery(the state quantity of the electric power source) is smaller than the threshold S

Electrically driven hydraulic construction machine

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.

Work machine

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

Hydraulic energy recovery apparatus for working machine

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 controllerof a hydraulic system is provided with a regeneration control calculation section, and a pump flow rate control calculation section, and when the regeneration control calculation section controls a regeneration valveto perform regeneration, the pump flow rate control calculation section controls a pump flow rate regulation deviceto increase the delivery flow rate of a hydraulic pumpas the angle of an armapproaches the vertically downward direction based on posture information about the armacquired by an inertial measurement unit

A work machine including: a hydraulic cylinderconfigured to drive a work implement; a control valveconfigured to connect a delivery line of a hydraulic pumpswitchingly to a bottom fluid chamber and a rod fluid chamber of the hydraulic cylinderand a tank; a pilot pumpconfigured to output a pilot pressure to drive the control valve; an engineconfigured to drive the hydraulic pumpand the pilot pump; and an accumulatorconfigured to accumulate a return hydraulic fluid from the hydraulic cylinderis provided with: a bypass lineconfigured to connect the bottom fluid chamber of the hydraulic cylinderand a delivery lineof the hydraulic pumpby bypassing the control valveand be provided with the accumulatorthereon; a pressure-accumulation control valveprovided between the bottom fluid chamber of the hydraulic cylinderand the accumulator; a release control valveprovided between the accumulatorand the delivery line; and a hydraulic system controllerconfigured to open the release control valveif an engine revolution speed N becomes lower than a set value Ns.

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 accumulatorconnected to a hydraulic lineA between a pilot pumpand a pilot valve, an unloading valvethat is a pump output power switching device, a pressure sensordetecting the pressure of the hydraulic fluid supplied to the pilot valve, and a controllerhaving a pump output power control sectionswitching the unloading valvein accordance with the pressure detected by the pressure sensor. The controllerfurther has an abnormality determination sectionthat computes a command continuation time in a state in which a command output to the unloading valveis not changed. In the case where this command continuation time is not less than a predetermined value, it determines that the unloading valveis abnormal, and outputs the determination result.

Growing community of inventors

Tsuchiura, Japan

Yuichi Ogawa