Hitachi Construction Machinery Co., Ltd.

Koji Shimazaki

Isamu Aoki

Koji Hyodo

Tetsuji Tanaka

Atsushi Nakamura

Hironao Suzuki

Masaki Yoshikawa

Takayoshi Murahashi

Tomohiro Ueda

Mototaka Katayama

Takashi Ishii

Masakazu Kaitou

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

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

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 construction machine includes: an engine driving at least one hydraulic pump configured to supply operating oil to a hydraulic actuator; an exhaust adjustment mechanism adjusting a flow rate of exhaust from the engine; and a control device controlling the exhaust adjustment mechanism. The control device determines whether or not a first downhill traveling condition and/or a second downhill traveling condition are/is satisfied. When at least one of the first downhill traveling condition and the second downhill traveling condition is satisfied, the control device controls the exhaust adjustment mechanism such that the exhaust adjustment mechanism executes exhaust brake.

Construction machine

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.

Work vehicle

A work vehicle includes: a main hydraulic pump that supplies pressure oil to a hydraulic cylinder; an accessory pump that supplies pressure oil to an auxiliary machine; and a confluence switching valve that merges pressure oil of the accessory pump with pressure oil of the main hydraulic pump. The work vehicle is provided with a control device that, in case atmospheric pressure or air density of outside air is lower than a predetermined value, executes confluence limitation control of reducing a confluence flow rate at the confluence switching valve compared to the time in case the atmospheric pressure or the air density of the outside air is higher than the predetermined value, and canceling the confluence limitation control in case rotation speed of an engine becomes higher compared to a predetermined rotation speed value during the confluence limitation control, and the rotation speed value is higher as the atmospheric pressure or the air density of the outside air is lower.

Growing community of inventors

Hyogo, Japan

Koji Shimazaki