Hitachi Construction Machinery Co., Ltd.

Jun Ikeda

Kazunori Ishihara

Atsushi Kitaguchi

Takaaki Tanaka

Takeshi Iwaki

Takayuki Satou

Yoshifumi Nabeshima

Yasuki Kita

Tomohiko Yasuda

Masatsugu Arai

Takayuki Sato

Juri Shimizu

Takashi Yagyu

Yutaka Watanabe

Naoki Fukuda

Takashi Sasaki

Ryuji Kouno

Hideaki Iijima

Tsukasa Akiyama

Tatsuya Sugahara

Provided is a dump truck capable of switching a destination of supply of hydraulic oil from a hoist cylinder to a fan motor at an appropriate time. A dump truck comprising: a hydraulic pump for discharging a hydraulic oil by a driving force of the engine; a hoist cylinder for raising and lowering a vessel by the hydraulic oil supplied from the hydraulic pump; a fan motor for driving a fan that supplies a radiator with cooling air by the hydraulic oil supplied from the hydraulic pump; a selector valve capable of being switched between a first position for supplying the hoist cylinder with the hydraulic oil discharged from the hydraulic pump and a second position for supplying the fan motor with the hydraulic oil; and a controller configured to, in a case where the selector valve is in the first position, determine whether an inflow pressure of the hydraulic oil flowing into the selector valve is less than a threshold value, and in a case of determining that the inflow pressure is less than the threshold value, switch the selector valve from the first position to the second position.

Dump truck

Provided is a technique for improving the cooling efficiency of a vehicle heat exchange system configured to cool a cooling liquid discharged from each of a plurality of heat sources. The vehicle heat exchange system comprises a high-temperature side radiator unit and a low-temperature side radiator unit, the high-temperature side radiator including: a first high-temperature side radiator that faces a first fan and is connected to a high-temperature side discharge pipe; a second high-temperature side radiator that faces a second fan and is connected to a high-temperature side supply pipe; and a high-temperature side connection pipe for supplying the cooling liquid from the first high-temperature side radiator to the second high-temperature side radiator, and the low-temperature side radiator unit including: a first low-temperature side radiator that is arranged to face the second high-temperature side radiator on the upstream side of the cooling air flow, and is connected to a low-temperature side discharge pipe; a second low-temperature side radiator that is arranged to face the first high-temperature side radiator on the upstream side of the cooling air flow, and is connected to a low-temperature side supply pipe; and a low-temperature side connection pipe for supplying the cooling liquid from the first low-temperature side radiator to the second low-temperature side radiator.

Vehicle heat exchange system and dump truck

An engine () drives a variable capacity-type hydraulic pump (), discharged hydraulic oil is selectively supplied to a cooling fan () and a hoist cylinder () in accordance with switching of a selection valve (), thereby controlling the same on the basis of each target value. A pump discharge pressure (Pp) of the hydraulic oil discharged from the hydraulic pump () and a motor supply pressure (Pm) of the hydraulic oil supplied to a hydraulic motor () via the selection valve () are detected by sensors () and are compared with pressure determination values stored in advance as a pump discharge pressure (Pp) and an actuator supply pressure (Pm) generated when the target value is achieved. Presence/absence of abnormality in the hydraulic actuator control device () is determined on the basis of a result of the comparison, and when abnormality is determined to have occurred, control is performed to minimize the capacity of the hydraulic pump ().

Hydraulic actuator control device for dump truck

A hydraulic drive fan control device is provided with a variable displacement hydraulic pump, a hydraulic motor, a hydraulic drive fan that is driven by the hydraulic motor, a flow amount control valve, a rotational speed detector that detects a rotational speed of an engine, and a controller. The controller outputs a first valve control signal to the flow amount control valve and outputs a first pump control signal to the hydraulic pump to rotate the hydraulic drive fan at a first rotational speed, and outputs a second valve control signal to the flow amount control valve and outputs a second pump control signal to the hydraulic pump, thereby stopping the rotation of the hydraulic drive fan.

Hydraulic drive fan control device

A dump truck pitching control system that can improve the ride quality of a vehicle body and the drive stability during traveling is provided. The present invention includes: a pitching state amount detection sectionthat detects a state amount of the pitching movement of the vehicle body; a spring characteristics calculation sectionthat calculates spring characteristics of suspension cylinders, based on detection results of stroke sensors, pressure sensors, and temperature sensors; a pitching target amount calculation sectionthat calculates a target amount of the pitching movement of the vehicle body, according to the spring characteristics calculated by the spring characteristics calculation section; and a torque correction value calculation sectionthat calculates a torque correction value required to correct the pitching amount, according to the spring characteristics calculated by the spring characteristics calculation section

Dump truck pitching control system

Stresses are decreased at joints of a support structure disposed on a body of a dump truck. The dump truck includes a body frame (), a body (), a support structure () disposed on the body and supported by the body frame, and load transmission structures configured to transmit a load from the support structure to the body frame and, to transmit a reaction force from the body frame to the support structure. The support structure has a plurality of vertical plates () and a bottom plate (). The vertical plates are arranged along a direction in which the reaction force is received from the body frame, and the bottom plate is maintained in upward contact with these vertical plates. The bottom plate is divided into first areas and a second area. The first areas include areas where the bottom plate is in contact with the vertical plates, and the second area is an area other than the first areas. The load transmission structures are configured to transmit the reaction force from the body frame such that a reaction force to be transmitted to each of the first areas becomes greater than a reaction force to be transmitted to the second area.

Dump truck and load transmission structure for same

A dump truck is provided with a frame, hinge pins and a body (). The body is provided on a lower surface of a floor board () thereof with a rail () along a longitudinal direction of the frame. The rail is a hollow structure member comprised of two side rail plates () and a bottom rail plate (). The two side rail plates () extend downwardly from the lower surface of the floor board () of the body and oppose each other with an interval therebetween in a lateral direction of the frame, and the bottom rail plate () is arranged in contact with respective lower end surfaces (-) of these two side rail plates (). The dump truck () satisfies a relationship of Ts&#x3c;Tb&#x3c;Tf, where Ts is a thickness of the side rail plates, Tb is a thickness of the bottom rail plate, and Tf is a thickness of a top frame plate (-) of the frame.

A brake system in an electric drive dump truck. The electric drive dump truck has a generatordriven by an engineand traveling motorsL,R driven with electric power generated by the generator. Hydraulic brakesL,R,L,R are operated by brake pedal. An oil pressure sensordetects hydraulic fluid pressure produced in accordance with the amount of depression of the brake pedaland a control unitcontrols the traveling motorsL,R so as to operate them as generator-type retarders when the hydraulic fluid pressure P detected by the oil pressure sensoris not smaller than a predetermined value P

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Tsuchiura, Japan

Jun Ikeda