Hitachi Construction Machinery Co., Ltd.

Hideo Karasawa

Kouji Ishikawa

Kazunori Nakamura

Genroku Sugiyama

Hiroshi Watanabe

Hiroyuki Adachi

Yusuke Kajita

Koichi Shibata

Nobuei Ariga

Osamu Tomikawa

Kiyoshi Ono

Toichi Hirata

Tsuyoshi Nakamura

Yoichi Kowatari

Toshihiro Abe

Hiroshi Ogura

Yasuo Okano

Yasushi Arai

Hiroshi Onoue

Akihiro Narazaki

Katsuaki Kodaka

Youichi Kowatari

Yuuki Gotou

Koji Ishikawa

Shuichi Miura

Motoyuki Yabuuchi

Yasushi Ochiai

Yoshiyuki Umeno

Yusuke Hitachi ConstMachCo Ltd Kajita

Yusuke Hitachi Construction Machinery Co Kajita

A controller according to the present invention has: a storage section that stores a first relationship between manipulated variables of an operating lever preset for each vehicle-body weight and target delivery pressures of a hydraulic pump; a target delivery pressure computation section that applies the vehicle-body weight inputted through an input device and the manipulated variable of the operating lever corresponding to a pilot pressure detected by pilot pressure sensors, to a first relationship stored in the storage section in order to calculate a target delivery pressure of the hydraulic pump; and a feedback control section that performs feedback control on the center bypass selector valve such that the delivery pressure of the hydraulic pump detected by the delivery pressure sensor agrees with the target delivery pressure of the hydraulic pump calculated by the target delivery pressure computation section.

Construction machine

A target speed setting section sets a target speed of an engine to an idle speed that is lower than an input speed with an engine control dial when no operating signal is output from a control lever over a predetermined period of time. A speed control section controls the speed of the engine based on the target speed set by the target speed setting section, which includes an idle speed setting section that corrects the idle speed according to values detected by sensors so that reduction in an output of the engine due to a change in a state quantity associated with an environment under which the engine is placed can be inhibited. This allows a good operating condition to be achieved during a reset from an auto idle state even with an engine output has been reduced according to a change in environment.

Control unit for construction machine

A hydraulic working machine, typically a hydraulic excavator has a travel speed control unit and a boost control unit. The travel speed control unit includes a traveling, hydraulic pressure oil feed unit capable of feeding pressure oil to actuate traveling tilt-angle control devices. The boost control unit includes a boosting, hydraulic pressure oil feed unit capable of feeding pressure oil to actuate an adjustable relief valve. A single hydraulic pressure oil feed unit is commonly usable as the traveling, hydraulic pressure oil feed unit and the boosting, hydraulic pressure oil feed unit, and includes lines communicating with both of the traveling tilt-angle control devices and the adjustable relief valve, a solenoid valve for opening or closing these lines, and a controller for outputting a control signal to control the solenoid valve.

Hydraulic work machine

A pump torque control system is capable of preventing hunting due to interference between speed sensing control and control of an engine speed of a prime mover when the temperature of a hydraulic fluid is low. A maximum absorption torque is set in a regulatorthat controls displacement volumes of hydraulic pumpsandbased on a deviation between target and actual engine speeds of a prime mover. A second modification factor calculating sectionand a control gain modifying section, which are included in a controllerthat performs speed sensing control to ensure that the maximum absorption torque of the hydraulic pumpsandis reduced, change a control gain of the speed sensing control based on a value detected by the hydraulic temperature sensorto ensure that the control gain is reduced as the temperature of the hydraulic fluid is reduced.

Pump torque control system for hydraulic construction machine

A hydraulic circuit for a hydraulic working machine is composed of a main pump, a boom cylinderarranged for extension or contraction by pressure oil from the main pump, a directional control valvefor controlling flows of pressure oil to be fed from the main pumpto a bottom chamberand rod chamberof the boom cylinder, a control unitfor performing a change-over control of the directional control valve, a pilot pump, a jack-up selector valvefor controlling a flow of pressure oil delivered from the pilot pump, a flow control valveconnected on an upstream side of the directional control valveto a meter-in port of the directional control valvesuch that the flow control valvecan be changed over by the jack-up selector valve, and a center bypass selector valveconnected on a downstream side of the directional control valveto a center bypass port of the directional control valvesuch that the center bypass selector valvecan be changed over by the jack-up selector valve. The hydraulic circuit performs a change-over of the jack-up selector valvein accordance with a bottom pressure on the boom cylinder

Hydraulic working machine

An engine lag down control system for construction machinery has a machinery body controller having first, second and third torque control units and a solenoid valve. The first torque control unit controls a torque control valve to a minimum pump torque corresponding to a target number of engine revolutions when a non-operated state of a control device has continued beyond a monitoring time. The second torque control unit controls the torque control valve such that the above-described minimum pump torque is held for a predetermined holding time subsequent to the operation of the control device from the non-operated state. The third torque control unit controls the torque control valve such that from a time point of a lapse of the predetermined holding time, the pump torque is gradually increased on a basis of a predetermined torque increment rate.

Engine lag down suppressing device of construction machinery

A hydraulic drive system is mounted on a hydraulic excavator, and is provided with a directional control valvefor a boom, a directional control valvefor an arm, a boom control devicefor selectively controlling the directional control valvefor the boom, and an arm control devicefor selectively controlling the directional control valvefor the arm. The directional control valvescontrol a boom cylinderand an arm cylinder, respectively, which are driven by pressure oil delivered from a main hydraulic pump. The hydraulic drive system is provided with a communication control unit for communicating a rod chamberof the boom cylinderand a bottom chamberof the arm cylinderwith each other when a stroke of the arm control devicehas become a predetermined amount S or greater.

Hydraulic drive apparatus

A computing section computes a reference revolution-speed decrease modification amount DNLR; and multiplies an engine revolution speed modification gain KNL by a reference revolution-speed decrease modification amount DNL and then DNLR, to thereby compute an engine revolution-speed decrease modification amount DND based on input change of an operation pilot pressure, which is modified in accordance with DNLR. At the time when a lever operation input from an operation command unit is changed from full stroke to half stroke, if a pump delivery pressure is in a pressure range of a pump absorption torque control region Y where the pump delivery pressure is lower than that in a region X, the reference revolution-speed decrease modification amount computing sectioncomputes the modification amount DNLR to be 0, and therefore lowering of a target engine revolution speed with auto-acceleration control is not caused.

Control system for hydraulic construction machine

Assessment information needed to calculate a used vehicle assessment value of a hydraulic excavatoris input to a portable telephoneand is then transmitted from the portable telephone. The transmitted assessment information is received at a manufacturer's base stationat a remote location. The used vehicle assessment value of the hydraulic excavatoris calculated based upon the received assessment information, and history information and operation information on the hydraulic excavatorread out from an operation information databaseand a history databasein correspondence to an ID number assigned to the hydraulic excavator which is included in the assessment information.

Construction machine management apparatus and construction machines management system

To permit using hold-side pressure oil in a first hydraulic cylinder for the acceleration of a second hydraulic cylinder upon performing a combined operation of the first and second hydraulic cylinders, a hydraulic drive system is provided with a main hydraulic pump, a boom cylinderand an arm cylinder, a directional control valvefor a boom and a directional control valvefor an arm, and a boom control deviceand an arm control device. The hydraulic drive system is also provided with a pressure oil feed means for feeding pressure oil in a rod chamberof the boom cylinderto an upstream side of the directional control valvefor the arm when a bottom pressure of the arm cylinderhas increased to a high pressure equal to or higher than a predetermined pressure. This pressure oil feed means includes a flow combiner valvearranged in a reservoir linewhich can communicate to the rod chamberof the boom cylinder. When the bottom pressure of the arm cylinderis the predetermined pressure or higher, the flow combiner valvemaintains a communication line, which communicates the reservoir lineand the upstream side of the directional control valvefor the arm with each other, in a state that pressure oil can be fed to the upstream side of the directional control valvefor the arm.

Hydraulic drive device

An engine control system includes pressure sensors (), position sensors (), pressure sensors (), a target revolution speed modification value computing unit (), and a modification value adder (). A target revolution speed NRfor use in control is computed based on changes of status variables such that the target revolution speed NRincreases from the target revolution speed NRapplied from an input unit (), and then moderately returns to the target revolution speed NR. In accordance with the computed target revolution speed NRfor use in control, a target fuel injection amount FNis computed and a fuel injection amount is controlled. As a result, a drop of an engine revolution speed attributable to an abrupt increase of an engine load can be suppressed without sacrificing the work efficiency, and lowering of durability caused by an excessive increase of the engine revolution speed can be prevented.

Engine control system for construction machine

A working machine maintenance system having a plurality of working machines. A center server is provided that manages maintenance on the plurality of working machines by engaging in data exchange through bidirectional communication with each of the plurality of working machines via a communication line. The working machines each include an operation data storage device, an operation device operated to enter a maintenance work completion, a data transmission device, a data reception device, and a display device at which the maintenance information is displayed. The center server includes a data reception device that receives the operation data, the maintenance work completion data, and the maintenance data that have been transmitted, an operation database in which the operation data are stored, a maintenance database, a calculation device that calculates maintenance timing. and a data transmission device that transmits data related to the maintenance information.

Working machine, failure diagnosis system for work machine and maintenance system for work machines

A working machine failure diagnosis method for performing a failure diagnosis by transmitting and receiving signals through communication devices provided at a working machine and at an information management center, according to the present invention, includes: a first step in which a first signal related to a failure of the working machine is generated at the working machine and the first signal is transmitted to the information management center from the working machine via the communication devices; a second step in which, after the first signal is transmitted, the information management center generates a second signal for identifying a location of the failure based upon the first signal and the second signal is then transmitted from the information management center to the working machine via the communication devices; and a third step in which failure information corresponding to the first signal and the second signal is provided to an operator.

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Tsuchiura, Japan

Hideo Karasawa