Hitachi Construction Machinery Co., Ltd.

Hitachi, Ltd.

Takamasa Kai

Juri Shimizu

Kenji Hiraku

Hiromasa Takahashi

Teppei Saitoh

Teppei Saitou

Hiroyuki Yamada

To provide a construction machine that has a hydraulic system mounted thereon in which a closed-circuit pump, and an open-circuit pump and a proportional valve are arranged as a pair, and that makes it possible to use an unused open-circuit pump or proportional valve to accelerate the speed of a single rod hydraulic cylinder when the single rod hydraulic cylinder and a hydraulic motor are driven simultaneously. A controller () controls a cap-side selector valve () and a rod-side selector valve () such that a particular open-circuit pump () not connected to a single rod hydraulic cylinder () is connected to the single rod hydraulic cylinder, and controls an opening area of a particular proportional valve () provided on a flow line that connects a delivery port of the particular open-circuit pump to a tank, when the single rod hydraulic cylinder and a hydraulic motor () are driven simultaneously.

Construction machine

A construction machine incorporates a hydraulic closed circuit system capable of suppressing, even where a selector valve is stuck in an open state by a failure of the selector valve or a control system therefor, unintended operation of a hydraulic actuator and continuing operation of a machine body. The construction machine includes first sensors that detect open-closed states of a plurality of switching valves, first compulsory valve closing devices that change over the plurality of switching valves to a closed position irrespective of open-close control by a machine body controller, and a valve device controller that controls, when it is detected based on the open-closed states of the plurality of selector values detected by the first sensors that one of the plurality of selector values is stuck in an open state, the first compulsory valve closing device such that other selector valve connected to one of the plurality of closed circuit pumps to which the one selector valve is connected is closed.

Provided is a work machine which makes it possible, in a hydraulic closed-circuit system, to prevent occurrence of cavitation when reverse lever operation which is an instruction for a swing in a direction opposite to a swing direction is performed during swing deceleration. A controller is configured to perform control such that a rate of a flow supplied from a bidirectionally tiltable hydraulic pump to a swing motor becomes lower than a pump flow rate according to an operation amount of the swing operation lever when a swing direction corresponding to a swing velocity sensed at a velocity sensor is different from a swing direction corresponding to operation of a swing operation lever.

Work machine

A construction machine includes a bidirectionally tiltable type hydraulic pump, a hydraulic cylinderhaving a cap chamberand a rod chamber, a first flow pathconnecting the hydraulic pumpand the cap chamber, a second flow pathconnecting the hydraulic pumpand the rod chamber, a discharge flow pathbranched from the first flow path, a discharge valvethat is disposed in the discharge flow pathand controls a discharge rate of hydraulic working oil from the cap chamberto the discharge flow path, an operation devicethat instructs an action of the hydraulic cylinder, and a controller. The controllercontrols the hydraulic pumpand the discharge valvesuch that at least a part of hydraulic working oil discharged from the cap chamberis discharged to the discharge flow pathwhen an operation amount of the operation devicelies within a fine operation region during a pulling action of the hydraulic cylinderin a state that a load is applied in a contraction direction. Accordingly, operability improves during fine operation of the pulling action of the hydraulic cylinder in the state that the load is applied in the contraction direction.

Provided is a remote control system which controls a work machine from a remote place in order to improve safety and workability and to reduce fatigue of an operator. In the remote control system which controls the work machine from a remote place, a seat where the operator sits is driven to be inclined in conjunction with the machine, so that inclination information of the machine at the time of traveling is provided to the operator to be sensible and the safety and the workability are improved. On the other hand, a large inclined vibration caused by the work of the machine is not transferred to the operator since an inclination amount of the seat is kept when the machine is not traveling, so that the fatigue of the operator is reduced.

Growing community of inventors

Tokyo, Japan

Takamasa Kai