Hitachi Construction Machinery Co., Ltd.

Mitsuhiko Kanehama

Tsuyoshi Nakamura

Kensuke Sato

Hiroyuki Azuma

Yasuo Okano

Kouji Ishikawa

Ryohei Fukuchi

Kazunori Nakamura

Hiroaki Tanaka

Katsuaki Kodaka

Yusuke Kajita

Hiroaki Amano

Kento Kumagai

Yusuke Suzuki

Teruki Igarashi

Naoki Hagiwara

Ryousuke Itou

Shota Ishida

Masayuki Hagiwara

Naoya Takagawa

Taro Akita

Provided is a work machine capable of appropriately switching between prevention of the degradation in a ride quality caused by an inertial force generated in braking of a hydraulic actuator and a work using the inertial force. In the work machine, under a condition where an operation device has been operated from an operation position toward a neutral position, in a case where an actual operation speed of the operation device is less than a quick operation threshold (S: Yes), a spool is made moved from a supply and discharge position toward a blocking position at a first speed that is slower than a reference speed corresponding to the operation speed (S, Sto S), and at a second speed that is faster than the first speed (Sto S) in a case where the operation speed is equal to or more than the quick operation threshold (S: No).

Work machine

A controller of a work machine computes a requested velocity of a hydraulic actuator based on an operation signal, computes a first estimated velocity of the hydraulic actuator based on a sensed value of a first sensing device that senses motion information of a driven member, computes a second estimated velocity of the hydraulic actuator based on a sensed value of a second sensing device that senses a flow rate of a directional control valve, computes an arbitrated velocity by arbitrating the first estimated velocity and the second estimated velocity according to a driving state of the hydraulic actuator, and controls the directional control valve based on a deviation between the requested velocity and the arbitrated velocity. The computation of the arbitrated velocity is to perform an arbitration such that a degree of effect on the second estimated velocity is larger than a degree of effect on the first estimated velocity when the hydraulic actuator starts to move, and to perform an arbitration such that the degree of effect on the first estimated velocity is larger than the degree of effect on the second estimated velocity when the driving of the hydraulic actuator is approaching a steady state.

A work machine includes: a work device including a plurality of hydraulic actuators and a plurality of driving target members; a posture sensor that senses posture information of the work device; a control valve unit that controls flows of hydraulic operating fluid supplied from the hydraulic pump to the plurality of hydraulic actuators; a plurality of solenoid valves that generate pilot pressure for driving the control valve unit; and a controller that computes a command value of the pilot pressure to be generated by the solenoid valves, and outputs a control signal corresponding to the command value to the solenoid valves. The controller computes a gravitational direction component of an action direction vector of the driving target members on the basis of the posture information sensed by the posture sensor, corrects the command value of the pilot pressure on the basis of the gravitational direction component of the action direction vector when the command value exceeds a predetermined pressure, and outputs the control signal corresponding to the command value after the correction to the solenoid valves.

A hydraulic drive system includes a swing directional control valveand a third boom directional control valvethat are connected to a third hydraulic pump. Furthermore, the hydraulic drive system includes: a second auxiliary directional control valvethat is connected to the third hydraulic pump, and is connectable with a second special hydraulic actuatorfor driving special attachments; and a first selector valvethat is connected to the third hydraulic pumpupstream of the second auxiliary directional control valve, and is connectable with an additional hydraulic pump. The first selector valveswitches the hydraulic fluid source of the second special hydraulic actuatorconnected to the second auxiliary directional control valveat least between the third hydraulic pumpand the additional hydraulic pump. Operability for combined operation of a special attachment can be improved in the hydraulic drive system equipped in advance with an auxiliary directional control valve that is connectable with an additional hydraulic actuator for driving the special attachment.

Hydraulic drive system for work machine

The purpose of the present invention is to provide a cooling fan control device for a construction machine, whereby the effects of heat caused by warm-up operation can be suppressed. This cooling fan control device is equipped with a control unit () that controls the rotational speed of a cooling fan () in accordance with a main pump discharge pressure (P) detected by a main pump discharge pressure sensor (), an engine cooling water temperature (Tw) detected by an engine cooling water temperature sensor (), a hydraulic oil temperature (To) detected by a hydraulic oil temperature sensor (), and an engine rotational speed (E) detected by an engine rotational speed sensor (). The cooling fan () is rotated at the rotational speed controlled by the control unit (), thereby sending the generated cooling air to an oil cooler () and a control valve ().

Cooling fan control device for construction machine

A hydraulic drive device for a hydraulic excavator, includes: a first hydraulic pump; a first boom directional control valve and a second arm directional control valve which are connected in parallel to the first pump; a second hydraulic pump; and a second boom directional control valve and a first arm directional control valve which are connected in parallel to the second pump; wherein: the hydraulic drive device also includes: a third hydraulic pump; a third boom directional control valve connected to the third pump and controlling the flow of pressure oil supplied to a boom cylinder; and a third arm directional control valve connected in tandem with the third boom directional control valve and controlling the flow of pressure oil supplied to an arm cylinder.

Hydraulic drive device for working machine

A hydraulic drive device for a construction machine includes an engine stopping unit and a discharge rate control unit. The engine stopping unit stops the engine when a predetermined state of the construction machine has continued for a predetermined period of time. The discharge rate control unit controls a discharge rate control pressure being input to the regulator, when an exhaust emission control device performs regeneration control, or performs warm-up control, and the gate lock lever is in the open position.

Hydraulic drive device for construction machine

A prime mover revolution speed control system for a hydraulic construction machine sets the revolution speed of the prime mover in accordance with the operating state invoked by an operating command and as a result of a determination of an excavation state so that that the revolution speed of the engine can be increased for a heavy load (speedup) in the excavation state. When the control lever is fully operated in the direction of arm crowding, the control leveris also operated, and first judgment conditions are all met to conclude that an excavation state has begun. During excavation work, when the control leveris subjected to a half or greater operation in the arm crowding direction, second judgment conditions are all met to conclude that the excavation state persists, and the speedup sequence is continued.

Prime mover revolution speed control system for hydraulic construction machine

Disclosed is a hydraulic drive system for a working machine, which enables to conduct forced regeneration continuously for a sufficient time. Based on an input of a lock detection signal Sfrom a gate lock detection switcha controllerdetects that a gate lock leverfor controlling a gate lock on/off valveis in a locked state, in other words, hydraulic actuators such as an arm cylinderarranged on a hydraulic excavatorare all in non-operated states. Upon an input of a forced regeneration command signal So from a forced regeneration switchin this detected state, control signals Cp,Cf are outputted to a boosting control valveand regulatorto make a forced regeneration means (an arm cylinder control valveand the regulator) conduct forced regeneration.

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Tsuchiura, Japan

Mitsuhiko Kanehama