Komatsu Corporation

Yoshitaka Onodera

Eiji Ishibashi

Shinji Kaneko

Shigeru Yamamoto

Masaaki Imaizumi

Katsuhiro Ikegami

Jun Hashimoto

Takao Ishihara

Masayuki Mukaino

Hideyuki Hiraiwa

Taishi Oiwa

Kazunori Nishimura

Yoshifumi Shitara

Yuji Kikuyama

Yutaka Sugimoto

Toshihiko Fukasawa

Hidehiro Hashimoto

Yasuo Harada

Yoshiyuki Hirosawa

Yoshiaki Nagashima

Hiroyuki Kijima

A work vehicle has a running motor and includes a first controller generating a speed command value to control the motor and adding an actual running speed of the work vehicle to a relationship between a torque command value for a torque in the motor and a running speed of the work vehicle to generate a first torque command value and a second controller generating a second torque command value based on the speed command value and the actual running speed, controls the motor using a smaller one of the first and second torque command values when the work vehicle moves forward, and controls the motor using a greater one of them when the work vehicle moves backward. The first controller determines the speed command value based on an accelerator opening used to regulate the running speed, the actual running speed, and an actual movement direction of the work vehicle.

Work vehicle

A work vehicle includes an accelerator operation amount generator receiving an actual accelerator operation amount of an accelerator operator to generate a control accelerator operation amount; an engine controller controlling the engine according to the control accelerator operation amount; and a storage storing a table in which an increasing speed for the control accelerator operation amount is set, wherein the accelerator operation amount generator obtains a difference between a converted accelerator operation amount of the accelerator operator converted from a rotating speed of the engine in a current control cycle and a control accelerator operation amount obtained in the last control cycle, determines an increasing speed of the control accelerator operation amount from the difference by referring to the table, and changes the control accelerator operation amount to an actual operation amount in the current control cycle with the determined increasing speed.

Work vehicle, and control method for work vehicle

A work vehicle includes a variable displacement hydraulic pump driven by an engine, a hydraulic motor forming a closed circuit with the pump and driven by hydraulic fluid discharged from the pump, wheels driven by the motor to allow the work vehicle to travel, a selector detecting an operating state of a switch switching the traveling of the work vehicle between forward and backward, and a controller. When the selector detects a reversal operation of the switch to reverse the traveling direction when the work vehicle travels, the controller sets relationship between the vehicle speed of the work vehicle and the upper limit of the rotational speed of the engine such that the upper limit increases as the absolute value of the vehicle speed approaches zero. The controller obtains an upper limit of the rotational speed from the relationship and a vehicle speed of the work vehicle.

Work vehicle and method of controlling work vehicle

A control device controls a hydrostatic transmission vehicle having a hydrostatic transmission including a variable displacement pump and a variable displacement hydraulic motor. The control device is configured to set a set vehicle speed based on a forward/rearward travel command and a gear stage command instructed by an operator, to set a torque limit usable for the hydrostatic transmission based on an engine speed, to set a vehicle speed limit based on a pressure in the hydraulic circuit and the torque limit, to select a lower one of the set vehicle speed and the vehicle speed limit, and to control respective displacements of the variable displacement pump and the variable displacement hydraulic motor based on the selected vehicle speed.

Control device for hydrostatic transmission vehicle

A work vehicle is provided with a traveling motor, and includes a first control unit generating a speed command value for controlling the motor and changing the speed command value according to passage of time when an opening of an accelerator that adjusts a traveling speed is larger than 0, and assigning an actual traveling speed of the work vehicle to a relationship between a torque command value that is a command value of torque to be generated by the motor and the traveling speed of the work vehicle to generate a first torque command value; and a second control unit generating a second torque command value based on the speed command value generated by the first control unit and the actual traveling speed, and controlling the motor based on the first torque command value or the second torque command value.

An engine control device for a forklift that suppresses an increase in fuel consumption amount and noise by limiting an engine rotation speed when the forklift is driven without the need to increase the engine speed according to the accelerator operation even when the accelerator is depressed hard. Determining means in a controller determines whether all of the following conditions are satisfied: a neutral position of the traveling direction instructing means; a lift raising switch and first, second and third attachment switches are turned off. When all of the above conditions are satisfied, it is determined whether the forklift is driven in any of a plurality of states. An engine control means generates and outputs a control command to obtain the engine speed based on the accelerator pedal depression with the upper limit value of the engine speed set as an upper limit value of the engine speed.

Forklift engine control device

In an engine-overrun-preventing control device, if an engine speed exceeds a maximum speed, a minimum value of an inching rate is set such that higher the actual engine speed results in a higher minimum value of an inching rate. The hydraulic pump displacement is adjusted to obtain a higher inching rate between the minimum value of the inching rate and an inching rate set based on a brake stroke. If the engine speed exceeds a commanded speed and a pressure time-rate-of-change at the pump intake exceeds a prescribed value, the minimum value of the inching rate is set such that the higher the pressure time-rate-of-change, the higher the minimum value of the inching rate. The pump displacement is adjusted to obtain a higher inching rate between the minimum value of the inching rate set based on the pressure time-rate-of-change and the inching rate set based on the brake stroke.

Engine overrun-preventing control device for work vehicle

Control device for hydraulic transmission vehicle

A control device controls a hydrostatic transmission vehicle having a hydrostatic transmission with a variable displacement pump and a variable displacement hydraulic motor. The control device is configured to set a set vehicle speed based on a forward/rearward travel command and a gear stage command instructed by an operator, to set an upper limit of the engine speed with respect to the set vehicle speed for limiting the upper limit of the engine speed to a predetermined partial engine speed set to be lower than a high idle engine speed when the set vehicle speed is in a preliminarily set low and intermediate speed range, and to control respective displacements of the variable displacement pump and the variable displacement hydraulic motor based on the set vehicle speed for allowing a vehicle speed to reach the set vehicle speed even when the engine is rotated at the partial engine speed.

A control device of a forklift engine that secures operability by keeping down fuel consumption when the accelerator pedal is floored in an unloaded or lightly loaded state, and once a heavy cargo is loaded, by lifting the cargo at a maximum lifting speed and traveling with maximum travel performance without acceleration problems. At least two maximum torque curves of different magnitudes are set in advance on a torque curve diagram. Then, the weight the cargo loaded on an attachment is measured. A threshold value for selecting at least two maximum torque curves is determined. If the measured weight is less than the threshold value, the maximum torque curve with a smaller maximum torque value is selected. If the measured weight is not less than the threshold value, the maximum torque curve with a larger maximum torque value is selected. The engine is controlled using the selected maximum torque curve.

A traveling control device and a traveling control program for a work vehicle in which a change in a control quantity due to an effect of vehicle body vibrations is small, fixing the desired control quantity is possible, and the control quantity can be matched with the operator's feel. A travel control program in which a first line on which the speed ratio reduces corresponding to a change in the operation stroke, a second line having hysteresis with respect to the first line and on which the speed ratio increases corresponding to a change in the operation stroke, and third lines on which the speed ratio changes corresponding to the change in the operation stroke and the change in speed ratio with respect to the change in the operation stroke is smaller than that of the first and the second line are set is installed in the control device.

Growing community of inventors

Hiratsuka, Japan

Yoshitaka Onodera