Hitachi Construction Machinery Co., Ltd.

Hitachi Construction Machinery Tierra Co., Ltd.

Kenichiro Nakatani

Yasutaka Tsuruga

Junya Kawamoto

Takashi Kanai

Shinya Imura

Kiwamu Takahashi

Yasuharu Okazaki

Satoshi Hamamoto

Yukiaki Nagao

Daisuke Yamamoto

In a hydraulic excavator including a track structure, a swing structure swingably disposed on an upper portion of the track structure, a work implement coupled to the swing structure, an earth removal device including a blade coupled to the track structure and a lift cylinder configured to raise and lower the blade, an operation sensor configured to detect an operation of a travelling lever, a height sensor configured to measure a height of the blade with respect to the track structure, an antenna for a satellite positioning system, the antenna being mounted on the swing structure, and a controller configured to calculate positional data regarding the blade, the controller is configured to determine a travelling operation on the basis of a signal of the operation sensor, calculate a travelling direction of straight forward travelling of the track structure as an orientation of the track structure when the straight forward travelling of the track structure is detected from a trajectory of the antenna with a state in which no turn travelling operation is being performed as a precondition, calculate horizontal coordinates of the blade on the basis of the orientation of the track structure, and calculate the height of the blade on the basis of a position of the antenna and a measured value of the height sensor.

Hydraulic excavator

To provide a work machine having a blade provided to a track structure, and a swing structure provided swingably on the upper side of the track structure, which work machine allows for computation of the horizontal coordinates of the blade. The work machine includes: a swing-structure-position acquiring device that acquires a horizontal coordinate and an orientation of the swing structure; a swing sensor that senses a swing of the swing structure; a travel sensor that senses travelling of the track structure; and a controller that computes an orientation of the track structure, and a horizontal coordinate of the blade. The controller computes the orientation of the track structure by using a locus of the horizontal coordinate of the swing structure acquired by the swing-structure-position acquiring device in a case where a swing of the swing structure is not sensed, and travelling of the track structure is sensed; and computes the horizontal coordinate of the blade on a basis of the computed orientation of the track structure, and the horizontal coordinate and the orientation of the swing structure acquired by the swing-structure-position acquiring device.

Work machine

Differential pressures across flow control valves and are controlled by pressure compensating valves and to be held at the same value, i.e., a differential pressure &Dgr;PLS, and the differential pressure &Dgr;PLS is maintained at a target differential pressure &Dgr;PLSref by a pump displacement control unit . For changing the target differential pressure depending on change in revolution speed of an engine , a flow detecting valve is disposed in a delivery line of a fixed displacement hydraulic pump , and a differential pressure &Dgr;Pp across a variable throttle portion of the flow detecting valve is introduced to a setting controller . A selector valve operable to shift between a fully closed position and a throttle position is disposed in parallel to the flow detecting valve and is shifted by a control lever

Hydraulic drive device

An actuator lock switching valve is provided which communicates a drain line and a pilot line with each other when the valve is in a position C, and which communicates pilot lines with each other when it is shifted to a position D. The pilot line is connected to a delivery line of a hydraulic pump , and the pilot line is connected to pressure receiving sections provided at ends of the pressure compensating valves on the side acting in the closing direction. The actuator lock switching valve has a pressure receiving section connected to the output side of a pilot lock switching valve , and is switched over in interlock with shifting of the switching valve . In a hydraulic drive system including pressure compensating valves controlled by an LS system, an actuator can be locked with a simple construction and can be prevented from malfunctioning in an inoperative condition while an engine is being driven, even when the system includes a mechanically shifted directional control valve, or even when a mechanically shifted directional control valve is retrofitted to the system.

Hydraulic driving device

A hydraulic drive system includes a pump control unit for controlling a pump delivery rate such that a pump delivery pressure is held at a predetermined value higher than a maximum load pressure among actuators . Pressure compensating valves are each constructed to set, as a target compensation differential pressure, a differential pressure between the delivery pressure of a hydraulic pump and the maximum load pressure among the actuators . The pressure compensating valve is given such a load dependent characteristic that the target compensation differential pressure is reduced when a load pressure rises. A lower limit setting spring for limiting the target compensation differential pressure from becoming smaller than a predetermined value is provided in the pressure compensating valve for the swing section.

Hydraulic driving unit

An engine speed control system for a construction machine is arranged in association with its hydraulic circuit, which has main pumps, a communication line through which input ports of travel-controlling directional control valves are connected with each other, and a travel-controlling communication valve arranged in the communication line. The engine speed control system is provided with pilot valves arranged in a pilot line to control traveling, pilot valves arranged in a pilot line to control booms and the like, pilot valves arranged in a pilot line to control revolving, earth moving and the like, a pressure sensor for detecting pressures in the pilot lines, another pressure sensor for detecting a pressure in the pilot line, an engine controller for performing automatic idling control or its cancellation in accordance with signals from the pressure sensors, and a signal line for changing over the travel-controlling communication line into a communicating position in response to a pressure in the pilot valve.

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Shiga, Japan

Kenichiro Nakatani