Hitachi Construction Machinery Co., Ltd.

Hitachi, Ltd.

Takashi Yagyu

Yasuo Tanaka

Yutaka Watanabe

Tomohiko Yasuda

Yukihiko Sugiyama

Yoshinori Furuno

Michio Fushiki

Satoru Kaneko

Masami Ochiai

Toshikazu Minoshima

Yasuhiro Kiyofuji

Kazuhiro Imaie

Keizo Shimada

Sotaro Tanaka

Naoshi Sugawara

Takeshi Yamaguchi

Yasuo Sakaki

Kichio Nakajima

Tsutomu Udagawa

Akira Hashimoto

Takanobu Ikari

Takao Kurosawa

Jun Ikeda

Yoshifumi Nabeshima

Takashi Sasaki

Takayoshi Murahashi

Kazuo Takiguchi

Katsumi Ueno

Mitsuo Aihara

Yudai Itai

Yohei Nakate

Hironori Uozu

Hajimu Kozawa

Kimio Katsuki

Soutarou Tanaka

Takashi Tateyama

Shintarou Oku

A body hoisting state display device to be mounted on a dump truck includes: an angle detection unit that detects a rotation angle of the body with respect to the frame; a seating detection unit that detects whether or not the body is seated on the frame; a calculation unit that causes an inclination angle of the body at which the body is rotated with respect to the frame from a seated state of the body to be calculated, based on the rotation angle detected by the angle detection unit, as a ratio to an angle of a rotatable range that is defined between the seated state and a state in which the hydraulic cylinder is stopped at the position short of the position at which the hydraulic cylinder is extended to the maximal extent; and a display control unit that causes the ratio of the inclination angle of the body that is calculated by the calculation unit to be displayed on a display screen.

Dump truck body hoisting state display device

A control valve device () controls supply and discharge of pressurized oil to and from a hoist cylinder () which tilts a vessel (). A throttle (C) that limits a flow rate of hydraulic oil which is discharged from a hydraulic pump () and flows in a return line () through a pump line (), a first directional control valve () and a center bypass oil passage () is provided in the floating position (F) of the first directional control valve (). When the first directional control valve () is in the floating position (F), the upstream side of the throttle (C) is connected to the pump line (), and the downstream side of the throttle (C) is connected to the return line (). In addition, a rod-side actuator line () communicated with rod-side oil chambers (E,F) in the hoist cylinder () is connected to the pump line ().

Transport vehicle

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

Brake system in electric drive dump truck

A drive system of an electrically driven dump truck is capable of achieving an operational feeling in which the operation amount of the accelerator pedal is well balanced with the output horsepower of the electric motors, particularly at the time of slow traveling. To achieve this, the target motor output horsepower Pmcorresponding to the operation amount of an accelerator pedalis calculated. The target motor torque TrR, TrL is calculated on the basis of the target motor output horsepower Pmand the rotational speed &#x3c9;R, &#x3c9;L of electric motorsR,L respectively. The acceleration torque limit values of the electric motorsR,L corresponding to the operation amount of the accelerator pedalare calculated, respectively. Then, smaller values are selected, as motor torque instruction values TrR, TrL, between the acceleration torque limit value and the target motor torque TrR, TrL to control invertersR,L, respectively.

Drive system for electrically driven dump truck

Engine driving characteristics are achieved for driving a hydraulic system during non-traveling and traveling in an electrically driven dump truck. When a shift leveris located at a neutral position, the target revolution speed Nrcorresponding to the operation amount (p) of an accelerator pedalis calculated on the basis of first target revolution speed characteristics (Nr()) which are suitable for driving of a hydraulic pump for working so that an electronic governoris controlled on the basis of this target revolution speed. When the shift leveris located at a forward position, the target revolution speed Nrcorresponding to the operation amount of the accelerator pedalis calculated on the basis of second target revolution speed characteristics (Nr()) which are suitable for driving of electric motorsR,L so that the electronic governoris controlled on the basis of this target revolution speed.

An upper cross beamfor supporting a rear side of a cabfrom below is formed as a separate member from a base frame. This upper cross beamis separably mounted on left and right column portionsE of the base frameby using bolts. Namely, when an engineis mounted to the base frame, the upper cross beamis separated in advance from the base frame. Consequently, at the time of the operation of carrying in the engine, it merely suffices to vertically hoist or lower the engineby use of a crane. It is thereby possible to carry in the enginebetween the column portionsE of the base framewithout being hampered by the upper cross beam

Transporter vehicle

Detection signals from lever sensor (), sit-down sensor () and vehicle speed sensor () are read into a controller (). A control signal is produced by the controller () to switch a directional control valve () of a control valve unit () instantly from a floating position (c) to a neutral position (a) and to switch another directional control valve () from a neutral position (a) to a lowering position (d) when a dump truck () is in travel with the directional control valve () of the control valve unit () is switched in the floating position (c). Whereupon, a hoist cylinder () is contracted by a hydraulic pressure force to hold a vessel () in a sit-down position on a vehicle body (), thereby preventing the vessel () from shaking movements like floating up while the dump truck () is in travel.

A drive system for an electrically driven dump truck is capable of enabling electric motors for traveling to make full use of the output horsepower of the prime mover up to an output limit of the prime mover. A target motor horsepower corresponding to an operation amount of an accelerator pedal is calculated and an available maximum horsepower for the electric motors out of the maximum output horsepower of the prime mover is calculated in response to the actual revolution speed of the prime mover. The horsepower coefficient corresponding to the instantaneous revolution speed deviation is calculated. The available maximum horsepower for the electric motors is modified by the horsepower coefficient to determine a second target motor horsepower. The target motor horsepower is limited to not exceed the second target motor horsepower so as to control the torque of the electric motors.

In an electric drive system for a vehicle, an alternator is driven by an engine to generate electric power which is used to drive a motor to generate a driving force. During a retardation of the vehicle, the motor is operated as an alternator to convert kinetic energy to electric energy which is used to retard the vehicle. A retard resistor is provided for absorbing electric energy generated during the retardation state. The retard resistor is cooled down by an AC blower.

Electric drive system for vehicle, electric control system for vehicle, electric drive method for vehicle

A hydraulic drive system is provided with a generatorfor outputting electricity corresponding to a rotation speed of an engine, an electric motordrivable responsive to the electricity from the generator, hydraulic pumpsdrivable by the electric motor, truck-body elevating cylindersfor pivoting a truck bodyin an up-and-down direction, and a stroke detectorfor detecting a stroke of the control apparatus of the truck-body elevating cylinders, and is also provided with a controllerfor performing control of engine rotation speed. The controllerincludes a motor electric-power computing meansfor determining electric power for the electric motor, which corresponds to the stroke detected by the stroke detector, and a discrimination meansfor discriminating whether or not the electricity from the generatorhas become greater than the thus-determined electric power for the electric motor

Hydraulic drive device for dump truck

In a hydraulic drive device for vertical pivoting movement of a load carrying platform, a first directional control valve has only three switchover positions, including a neutral position relating to operation of stopping and holding a load carrying platform, a switching position relating to operation of lifting the load carrying platform, and a switch over position relating to operation of forced lowering of the load carrying platform. A second directional control valve has only three switchover positions, including a neutral position, a switching position, and a switchover position relating to operation of allowing the load carrying platform to fall by its own weight. The device includes a first on-off valve, a second on-off valve, and a third on-off valve that are proportional control solenoid valves for switching an appropriate one of the first and second directional control valves.

Hydraulic drive device for vertical pivoting movement of load carrying platform

A motor is driven with variable frequency AC power converted from DC power, and an AC output power from the motor is converted to DC. In the conversion, an electromotive force regenerated by the motor is consumed by a plurality of resistors. When the consumption of the electromotive force is impeded in any of systems including any of the plurality of resistors, the electromotive force is consumed by the systems including the remaining resistors. Even if a system including any of the plurality of resistors fails, the electromotive force can by consumed by the other systems including the remaining resistors, thus providing a reliable rheostatic brake.

AC drive apparatus, vehicle control apparatus, and power conversion method and vehicle control method

The control valve apparatus holds a seat valve member in a position seated on a valve seat to thereby prevent a backward flow even if the pressure in the inlet chamber side becomes lower than the pressure in the outlet chamber side. With a pilot control valve member is in a closed state, when the pressure in the inlet chamber is higher, a pressurized medium is introduced to the control pressure chamber via a first valve unit and is cut off from the outlet chamber by a second valve unit. When the pressure in the outlet chamber is higher, the pressurized medium is introduced to the control pressure chamber via the second valve unit and is cut off from the outlet chamber by the first valve unit.

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Ushiku, Japan

Takashi Yagyu