Hitachi Construction Machinery Co., Ltd.

Kcm Corporation

Kabushiki Kaisha Kcm

Isamu Aoki

Tetsuji Tanaka

Koji Hyodo

Masaki Yoshikawa

Keigo Kikuchi

Masaki Nukii

Koji Shimazaki

Kouji Shimazaki

Yasunori Miyamoto

Masashi Yamashita

Atsushi Shimazu

Katsutaka Hara

Kazuyuki Ito

Yuki Ahiko

Kentaro Oomae

Hironao Suzuki

Kazuhiko Hiraoka

Tomoyuki Miyata

Kazuo Ishida

Wataru Isaka

Takashi Takeyama

Takayoshi Murahashi

Hiroki Nakazono

Tadayoshi Aoki

Shoroku Kawahara

Katsuyuki Kirita

Keisuke Naitou

Nobuyuki Hidaka

Kazuya Takeda

Hiroaki Yada

Tomohiro Ueda

Satoshi Kan

Seiji Nakagawa

Jumpei Kamiya

Takashi Ishii

Takuya Shimomura

Masakazu Kaitou

Tatsuo Oouchi

Provided is a work vehicle capable of reducing the fuel consumption while maintaining the working efficiency. A wheel loadercomprising a vehicle body controllerA for controlling an engine, wherein the vehicle body controllerA limits an upper limit rotational speed of the enginebased on an accelerator pedal step-on amount α, a brake pedal step-on amount β, a torque converter speed ratio e which is a ratio of a rotational speed of a torque converter, a discharge pressure Pof a loading hydraulic pump, and a stroke amount Sof lift arm cylindersor a stroke amount Sof a bucket cylinder

Work 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.

In an unloaded state of the bucket (), a control device () calculates an unloaded moment (M) around a hinge pin G from the pressure of the lift arm cylinder that is detected by pressure sensors (), the angle of a lift arm that is detected by a lift arm angle sensor, and dimension data extracted from a vehicle body information database (). In a loaded state of the bucket, the control device calculates a loaded moment (M) around the hinge pin G from the pressure of the lift arm cylinder, the angle of the lift arm, and the dimension data extracted from the vehicle body information database. The control device calculates the load (W) on the bucket by dividing the difference between the unloaded moment and the loaded moment by the horizontal distance (L) between the hinge pin and the gravity center position of the bucket.

Wheel loader and bucket load calculation method

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

Loading vehicle

The work vehicle includes: a clutch device including a forward-travel clutch and a backward-travel clutch configured to cause, when being in an engagement state, the work vehicle to travel in a forward travel direction and a backward travel direction; a forward-backward travel instruction device configured to instruct the work vehicle to travel in the forward travel direction or the backward travel direction; a clutch state detection device configured to detect whether the forward-travel clutch and the backward-travel clutch are each in the engagement state; and a torque restriction section configured to restrict a maximum absorbing torque of the hydraulic pump to be low when a restriction condition holds, the restriction condition including a condition that a traveling direction of the work vehicle, which corresponds to an engagement state of the clutch device, and a traveling direction of the work vehicle, which is instructed by the forward-backward travel instruction device are opposite to each other.

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.

The work vehicle includes an engine, a radiator; a hydraulic pump; a cooling fan that blows a cooling air to the radiator; a hydraulic motor which is driven by a pressure oil delivered from the hydraulic pump, and rotates the cooling fan; a directional control valve that switches a flow direction of the pressure oil from the hydraulic pump to rotate the hydraulic motor in forward and reverse directions; and a controller that controls the directional control valve so as to cause the repetitive operation of the forward and reverse rotation of the cooling fan to be performed at predetermined time intervals, in which the controller reduces the time intervals more than a normal time initially set when a relationship between the outside air temperature detected by the outside air temperature sensor and the refrigerant temperature detected by the refrigerant temperature sensor satisfies a predetermined condition.

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Tsukuba, Japan

Isamu Aoki