Hitachi Construction Machinery Co., Ltd.

Mitsuo Aihara

Hideaki Suzuki

Masami Ochiai

Tsutomu Udagawa

Kazuo Takiguchi

Yukihiko Sugiyama

Kozo Nakamura

Kenji Hiraku

Takayuki Uchida

Katsuaki Tanaka

Tomoaki Hiruta

Munetoshi Unuma

Junsuke Fujiwara

Teppei Saitoh

Shinya Yuda

Takashi Yagyu

Hiroshi Ogura

Katsumi Ueno

Takashi Yagyuu

Teruo Nakamura

Nobuyoshi Hirowatari

Jyunsuke Fujiwara

It is an object of the present invention to provide a construction machine having a good engine starting property in a low temperature environment. The construction machine of the present invention includes: an electric pump having a delivery port connected to a line part of a pilot line, the line part connecting a pilot pump with a pilot control valve; a motor that drives the electric pump; and a temperature sensor that measures a temperature of a hydraulic working fluid delivered from the pilot pump. A controller starts driving of the motor in the case where a key switch is operated from a key OFF state to a key ON state and where the temperature of the hydraulic working fluid measured by the temperature sensor is lower than a predetermined temperature.

Construction machine

The maintenance management deviceincludes an error status diagnosis unit, a grace period estimation unit, a maintenance cost estimation unit, and a screen display unit. When the error status diagnosis unithas diagnosed the occurrence of an anomaly, the grace period estimation unitestimates a first grace period leading up to the occurrence of a failure. The maintenance cost estimation unitestimates the cost of corrective maintenance incurred when the failure occurs after the elapse of the first grace period. The screen display unitdisplays a combination of the first grace period and the cost of corrective maintenance. Alternatively, the grace period estimation unitestimates a second grace period over which preventive maintenance may be postponed without a failure.

Maintenance management device for operating machinery

The operation data collection device for work machines includes a plurality of sensors attached to a work machine to receive measurement data as operation data and record the operation data in an operation data storage section. The operation data collection device further includes: a communication processing section that transmits the operation data stored in the operation data storage section to an external server in response to a download request from the external server; an access history management section that manages a download status of the operation data recorded in the operation data storage section, through the download request from the external server and the transmission of the operation data to the external server; and a recorded data change processing section that changes a condition for recording the operation data in the operation data storage section in accordance with the download status of the operation data.

Operation data collection device for work machines

A hydraulic drive system comprises directional flow control valves (-) for selectively supplying a hydraulic fluid from a first hydraulic pump (), inflow control valves (-) disposed respectively in branch lines (A-C) branched from a supply line () for supplying a hydraulic fluid delivered from a second hydraulic pump () to rod pushing-side chambers (A,A,A,A) of hydraulic cylinders, a bypass flow control valve () disposed in a line () connecting the supply line () and a reservoir (), and a controller () for computing control variables corresponding to operation command signals from control levers () and controlling the inflow control valves (-) and the bypass flow control valve () in accordance with the computed control variables. Thus, the number of flow control valves and the length of piping required for their connection can be reduced, and a total pressure loss can be further reduced.

Hydraulic driving system of construction machinery

The control valve apparatus holds a seat valve member in a position seated on a valve seat to thereby prevent a backward flow even if the pressure in the inlet chamber side becomes lower than the pressure in the outlet chamber side. With a pilot control valve member is in a closed state, when the pressure in the inlet chamber is higher, a pressurized medium is introduced to the control pressure chamber via a first valve unit and is cut off from the outlet chamber by a second valve unit. When the pressure in the outlet chamber is higher, the pressurized medium is introduced to the control pressure chamber via the second valve unit and is cut off from the outlet chamber by the first valve unit.

Control valve apparatus and pressure circuit

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Tsuchiura, Japan

Mitsuo Aihara