Hitachi Construction Machinery Co., Ltd.

Kcm Corporation

National Institute of Advanced Industrial Science and Technology

Tcm Corporation

Kabushiki Kaisha Kcm

Koji Hyodo

Tetsuji Tanaka

Isamu Aoki

Masaki Yoshikawa

Masaki Nukii

Keigo Kikuchi

Atsushi Shimazu

Yasunori Miyamoto

Nobuhiro Suzuki

Tadayoshi Aoki

Hiroki Nakazono

Katsutaka Hara

Kazuo Chonan

Koji Takano

Yasuo Yamazaki

Chao-Nan Xu

Hirofumi Oouchi

Eiichi Sakai

Koji Shimazaki

Shoroku Kawahara

Masashi Yamashita

Kouji Shimazaki

Genichiro Ishimaru

Ei Takahashi

Kazuo Ishida

Wataru Isaka

Takashi Takeyama

Kazuo Chounan

Nobuyuki Hidaka

Fumihiro Nakao

Yuki Ahiko

Tsuyoshi Takeyama

Tomoo Takahashi

Hironao Suzuki

Kazuhiko Hiraoka

Tomoyuki Miyata

Akitaka Takeuchi

Kazunori Komatsu

Yoshiyuki Yokogawa

Kentaro Itoga

Tetsuya Kameyama

Takashi Yamane

Akira Shimohira

Kazuyuki Ito

Katsuyuki Kirita

Motoyuki Akamatsu

Hiroaki Yada

Satoshi Kan

Seishi Morishita

Seiji Nakagawa

Kentaro Oomae

Jumpei Kamiya

Tatsuo Oouchi

Takehiko Katsuragi

Kohtaroh Uno

Kenji Uezono

Akira Takeshita

Kiyoyasu Hasegawa

Provided is a work vehicle capable of attaining a maximum vehicle speed specification value set in advance for each vehicle body even in the case where a device constituting an HST traveling drive system has deteriorated over time. In a wheel loaderequipped with an HST traveling drive system, a controlleris configured to, in the case where a detection pressure value P is equal to or less than a switching pressure value Ps corresponding to a switching point in the HST motorbetween a maximum displacement volume qmax and a minimum displacement volume qmin, and a detection vehicle speed value V is less than an upper limit vehicle speed specification value Vmaxs, limit the minimum displacement volume qmin of the HST motorto a first minimum displacement volume value qminless than a minimum displacement volume specification value qmins that is associated with the upper limit vehicle speed specification value Vmaxs.

Work vehicle

Provided is a loading work vehicle capable of improving work efficiency even when working on a slippery road surface. An HST-traveling-drive wheel loadercomprises a step-on amount detection sensor, a discharge pressure detection sensor, a mode switch device, and a controller. The controlleris configured to: determine whether a limit mode is selected by the mode switch device; specify an operation state of the wheel loaderwhen determining that the limit mode is selected; limit maximum traction force to a first set value which is set based on a static friction coefficient μ and vehicle weight when specifying that a bucketis pushed into a natural ground; and increase the maximum traction force from the first set value when specifying that excavation of the natural groundis started.

Loading work vehicle

A loading vehicle is capable of improving work efficiency by adjusting engine rotational speed with high accuracy in accordance with an operation state of the working device. An HST traveling driven wheel loader has an electrically controlled HST pump. A controller is configured to control input torque of the HST pumpand solenoid proportional pressure reducing valve is configured to generate control pressure for controlling displacement volume of the pump based on a control signal from the controller. The controller is configured to calculate the displacement volume q of the HST pump based on discharge pressure Pf of a loading hydraulic pump so that maximum input torque Thst of the HST pump decreases as the discharge pressure Pf or input torque of the loading hydraulic pump increases, and output a control signal corresponding to the calculated displacement volume q to the solenoid proportional pressure reducing valve.

Loading vehicle

Provided is a working vehicle capable of increasing lifting operation speed of a working device without increasing cost, even when provided with a circuit configuration that prioritizes a steering operation over a working device operation. A wheel loadercomprises a priority valveconfigured to allow hydraulic oil discharged from a hydraulic pumpto flow into a steering drive circuitpreferentially over a working device drive circuit, and further comprises: an electric steering lever; a pair of solenoid control valvesA,B configured to control a steering directional control valve; and a controller. The controlleris configured to control the pair of solenoid control valvesA,B so as to limit operation speed of a steeringwhen determining that an engineis in a low idle state and a lift armis performing a lifting operation.

Working vehicle

A wheel loader configured to reduce the traveling distance required for a raise and run operation, and reduce fuel consumption includes: an engine; a torque converter; a forward and reverse switch; a stepping amount sensor; an operation amount sensor; and a controller. The controllerdetermines whether a specific condition for specifying an operation of the lift armin an upper direction during forward travel of the vehicle body, on the basis of a forward and reverse switching signal, the stepping amount on the accelerator pedal, and a pilot pressure Ti pertaining to the lifting operation amount for the lift arm. When the specific condition is satisfied, the vehicle speed is limited by reducing the maximum rotational speed of the enginein response to increase in the pilot pressure Ti.

Wheel loader

Provided is a work machine capable of notifying that maintenance is necessary due to continuation of clogging in a cooling device or decrease in cooling performance. A wheel loaderincluding a radiatorand an oil coolercomprises a controllerA configured to determine a clogging continuation state of the radiatoror the oil cooler. The controllerA determines whether clogging is occurring in the radiatoror the oil coolerbased on outside air temperature AW and cooling water temperature CW or hydraulic oil temperature HW, determines whether the clogging continues based on a clogging occurrence ratio R, Rwhile an engineis operating, and outputs a notification command signal for providing the alarm buzzerand the user management systemwith a command to notify that maintenance is necessary when it is determined that the clogging continues.

Work machine

A wheel loader is provided that can suppress abrupt change in vehicle speed accompanied by erroneous determination on a lift arm lifting operation. A wheel loader includes: an engine; an HST pump; an HST motor; a forward and reverse switch; a stepping amount sensor; an operation amount sensor; and a controller. The controller determines whether a specific condition for specifying an operation of the lift arm in an upper direction during forward travel of the vehicle body, on the basis of a forward and reverse switching signal, the stepping amount, and a pilot pressure pertaining to the lifting operation for the lift arm. In a case of the specific condition being satisfied, the vehicle speed is limited by controlling the displacement volume of the HST motor in conformity with increase in the pilot pressure.

Provided is a wheel loader capable of moving up a lift arm in a short time during excavation work. A wheel loader comprises a controller configured to control maximum traction force of the wheel loader and input torque of a working device hydraulic pump, and include a specific condition determination section configured to determine whether a specific condition for specifying excavation work is satisfied, an elapsed time measurement section configured to measure an elapsed time from start of the excavation work, and an input torque control section configured to limit the input torque to a first input torque value when the specific condition is satisfied and increase the input torque from the first input torque value when a second set time elapses from the elapse of a first set time.

Provided is a loading vehicle in which a control characteristic of traction force can be easily and finely set and changed while a configuration of a hydraulic circuit is simple. An HST traveling driven wheel loader includes an electronically controlled HST pump and HST motor, including a solenoid proportional pressure reducing valve to control displacement volume of the HST pump based on a control signal output from a controller. The controller stores characteristic tables indicating a correlation between discharge pressure of a loading hydraulic pump or an operation state of an engine and a maximum discharge pressure of the HST pump, and when the vehicle speed corresponds to work requiring traction force, outputs a control signal to the solenoid proportional pressure reducing valve so as to obtain the maximum discharge pressure Pm of the HST pump that corresponds to one of the characteristic tables.

To curb temperature rises in a control device for a supercharger and extend the life of the control device for the supercharger, a work vehicle includes a variable geometry supercharger with variable boost pressure, and a working device driven by pressure oil discharged from a working hydraulic pump, the work vehicle further including: a supercharger control device adapted to control the supercharger; a temperature detection device adapted to detect temperature of the supercharger control device; and a main control device adapted to limit at least one of maximum rotational speed of an engine and maximum vehicle speed of the work vehicle in case the temperature of the supercharger control device is above a predetermined temperature as compared to case the temperature of the supercharger control device is below the predetermined temperature.

A wheel loader configured to reduce a sudden change in vehicle speed caused by an erroneous determination of a raising operation of a lift arm is provided. A wheel loaderincludes an engine, a variable displacement type HST pump, a variable displacement type HST motorcoupled to the HST pumpin a closed circuit, a hydraulic pump for working device, a forward/reverse selector switchfor switching a forward movement and a backward movement of a vehicle body, a depression amount sensorthat detects a depression amount of an accelerator pedal, a pressure sensorthat detects a discharge pressure Pa of the hydraulic pump for working device, and a controller. The controllerdetermines whether a specific condition to identify an upward movement of a lift armduring a forward travel of the vehicle body based on a forward/reverse switching signal, the depression amount of the accelerator pedal, and the discharge pressure Pa detected by the pressure sensor. When the specific condition is satisfied, the controllercontrols a displacement volume of the HST motoraccording to an increase of the discharge pressure Pa, so as to limit the vehicle speed.

A work vehicle is provided. The work vehicle is capable of notifying an operator of a state close to overheating of a temperature of a cooling oil that cools a brake device before the temperature overheats. A controller () in a work vehicle () compares each detection value detected from a brake pressure sensor () and a vehicle speed sensor () to each threshold (V, P, R) predetermined corresponding to each sensor. The controller () outputs a warning command that a temperature of a cooling oil is likely to overheat to a notification device () when a state that at least one detection value is equal to or more than the threshold and when a state that at least one detection value is equal to or more than the threshold continues for a first duration (t) or more.

Provided is a working vehicle capable of, while reducing fuel consumption, improving traveling performance only when high traveling performance is required. A wheel loadercomprises: an engine; a variable displacement HST pump; a variable displacement HST motorconnected to the HST pumpthrough a closed circuit; pressure sensorsA,B configured to load pressure of the HST motor; and a controller, wherein the controlleris configured to, in a case of determining that a load pressure detection value P is included in a predetermined pressure range of greater than load pressure P&#x3b1; corresponding to flat ground traveling and smaller than load pressure P&#x3b3; corresponding to an excavation operation, increase maximum rotational speed of the engineonly within the predetermined pressure range.

Provide is a loading vehicle capable of quickly operating an object handling device in the upward direction while traveling forward. A wheel loadercomprises an engine, an HST pump, an HST motor, a forward/reverse changeover switch, a step-on amount sensor, a pressure sensor, and a controller. In a case where a specific condition for specifying lifting operation of a lift armduring forward traveling of the vehicle body is satisfied, the controllerincreases maximum rotational speed of the engine to a predetermined value Nmaxwhich is greater than maximum engine rotational speed Nmaxduring traveling on the flat ground, and limit maximum vehicle speed to a predetermined value Vmaxwhich is smaller than maximum vehicle speed Vmaxprior to the lifting operation of the lift arm

The present invention relates to a work vehicle including an engine, a hydraulic pump, a hydraulic motor to drive wheels, an HST circuit in which the hydraulic pump and the hydraulic motor are connected to each other in the form of a closed circuit, a reducing agent sensor that detects the state of a reducing agent used to clean exhaust gas from the engine, and an engine restrictor that restricts the rotational speed of the engine based on the output from the reducing agent sensor, and the work vehicle further includes a control unit that changes the tilting angle of the hydraulic pump or the hydraulic motor independently of the rotational speed of the engine to a tilting angle associated with minimum travel drive force necessary for self-travel of the work vehicle when the control unit determines that the engine restrictor has restricted the rotational speed of the engine.

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Kasumigaura, Japan

Koji Hyodo