Hitachi Construction Machinery Co., Ltd.

Kcm Corporation

Kentaro Itoga

Kazunori Nakamura

Tsuyoshi Nakamura

Genroku Sugiyama

Toichi Hirata

Koji Hyodo

Katsuaki Kodaka

Kazuhiro Ichimura

Nobuhiro Suzuki

Masaki Yoshikawa

Hiroyuki Azuma

Yasushi Arai

Atsushi Shimazu

Hiroki Nakazono

Kazuo Chonan

Tomoo Takahashi

Motoyuki Yabuuchi

Yoshiyuki Takigawa

A hybrid work machine is configured with an engine, a hydraulic pump, a hydraulic actuator, a generator motorcoupled to the engine, an electric storage devicethat transmits and receives electric power to and from the generator motor, an engine controllerthat controls the enginebased on a target engine revolution speed, a power controllerthat controls action of the generator motor, a controllerthat controls the engine controllerand the power controller, and a target engine revolution speed change instructing device that give instructions on a change in the target engine revolution speed. The controllercontrols the engine controllerand the power controllerto act the generator motoras a generator until an actual revolution speed of the engineis reduced to a revolution speed corresponding to a target engine revolution speed after change if the target engine revolution speed has been changed to be lower while the engineis in an unloaded state. It is thereby possible to suppress noise of the engine in the case where the target engine revolution speed has been changed to be lower while the engine is in an unloaded state.

Hybrid work machine

An object is to reduce a load acting on an engine upon starting up the engine such that the engine can be quickly started up to reliably feed pressure oil from a hydraulic pump to an accumulator. A hydraulic control system is provided with first accumulators () connected to a hydraulic pump () via a first line () and second accumulators () connected to a second line () branching from the first line (), an on/off valve () arranged in the second line and interposed between the first line () and the second accumulators (), an operation detection device () for detecting whether or not a starter () is in an operation state, a rotational frequency detection device (a rotary encoder () and rotational frequency calculation device ()) for detecting a rotational frequency of an engine (), and a valve control device for, upon detection of the operation state of the starter () by the operation detection device (), controlling a valve position of the on/off valve () at a closed position until the rotational frequency reaches an idling rotational frequency set beforehand but then controlling the valve position of the on/off valve () at a closed position.

Hydraulic control device of wheeled industrial vehicle

An exhaust gas treatment apparatus for a working machine is provided to reliably prevent a specific process that raises the exhaust temperature of an exhaust gas treatment section from being carried out during switching operation of a directional control valve. The apparatus includes: a directional control valve that controls the flow of pressure oil supplied to an actuator; a pilot pump that supplies pressure oil to an operating device operated to switch the directional control valve; an open/close valve arranged downstream of the directional control valve; a control valve that controls the open/close valve; a lock valve arranged between the pilot pump and the operating device; a detecting section that detects when a specific process that raises the exhaust temperature of an exhaust gas treatment section becomes necessary, and outputs the corresponding detection signal; a controller that controls the control valve; and a pipe for performing a process of setting the open/close valve to an open position in accordance with the pilot pressure oil supplied from the pilot pump.

Exhaust gas treatment apparatus for working machine

There are provided: a pedal operation amount detection unitthat detects an operation amount s of the accelerator pedal; a speed ratio detection unitthat detects a speed ratio e of an input shaft and an output shaft of the torque converter; a load pressure detection unitthat detects a load pressure P of the hydraulic pump; a speed stage detection unitthat detects a low speed stage of a transmissioncapable of varying a speed stage between a low speed stage and a high speed stage; and a speed limiting unitthat limits a maximum speed of the engineto a lower speed upon satisfaction of following speed limitation conditions: at least a pedal operation amount s is equal to or greater than a predetermined value s, a speed ratio e is equal to or less than a predetermined value ea, a load pressure P is equal to or greater than a predetermined value Pa, and the low speed stage of the transmission has been detected.

Engine control device for working vehicle

To provide a steering system for a construction vehicle, which is suited not only for traveling on general roadways but also for work at construction sites and can perform high-reliability steering control. A steering system for a construction vehicle is provided with a directional control valvefor controlling a flow of pressure oil to body-articulating hydraulic cylindersthat perform steering and also with a steering-wheel-operated signal generation meansfor outputting by operation of a steering wheela pilot signal to the directional control valvefor switching the valve. The steering system is also provided with a lever-operated signal generation means for producing by operation of a levera pilot signal to switch the directional control valve, said lever-operated signal generation means including pressure-proportional solenoid valvesor the like, selector valvesswitchable to permit selectively outputting the pilot signal from one of the signal generation means to the directional control valve, and an automated switching means for switching the selector valvessuch that upon operation of the steering wheel, the pilot signal from the steering-wheel-operated signal generation meanscan be preferentially outputted to the directional control valve

Steering device for construction vehicle

A traveling working vehicle maintains fuel economy while ensuring a sufficient work rate in heavy-load work. A torque control regulatorcontrols the absorption torque of a hydraulic pumpto ensure that it does not exceed a preset maximum absorption torque, and an accelerator pedalcommands a target revolution speed of an engine. Revolution speed deviation computing sectionsand, a modification torque computing section, a modification revolution speed computing section, speed ratio computing sectionsand, traveling state determining sectionsand, and working state determining sectionsanddetermine an operating state of the traveling working vehicle. Both the pump base torque of the hydraulic pumpand the target revolution speed of the engineare modified depending on the determination result of the state determining sections.

Control system for traveling working vehicle

The invention provides a control system for a working vehicle, which can realize higher work performance and better fuel economy in a compatible way. A controllerincludes tableand tablesfor deciding maximum pump absorption torques and engine output torques based on an engine revolution speed, and selectorsfor switching over the decided maximum pump absorption torques and engine output torques depending on a work performance mode or a fuel economy mode is selected. A pump absorption torque characteristic for the fuel economy mode is set so as to provide a relative small maximum pump absorption torques TB in a high revolution range, and an engine output characteristic for the fuel economy mode is set so as to provide a relatively small engine output torque in the high revolution range.

Control device for working vehicle

A modification torque &#x394;T and a torque converter speed ratio e is computed from input and output revolution speeds of a torque converter. A first determination coefficient &#x3b1; corresponding to the speed ratio e, and a second determination coefficient &#x3b2; corresponding to a pump pressure are computed. A selectorselects the smaller one of these coefficients as a determination coefficient &#x3b3;, and the modification torque &#x394;T is multiplied by &#x3b3; to provide a modification torque &#x394;TA. An adderadds the modification torque &#x394;TA (negative value) to a pump base torque TR to provide a modified pump base torque TRA, whereby a maximum pump absorption torque TRA is controlled so as to become TRA. The maximum pump torque reducing control can then be performed while accurately confirming a work situation during the combined operation of travel and a working actuator.

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Tsuchiura, Japan

Kentaro Itoga