Hitachi Construction Machinery Co., Ltd.

Shouhei Sugiki

Kenji Hiraku

Hiromasa Takahashi

Juri Shimizu

Teppei Saitoh

Teppei Saitou

An object of the present invention is to provide a construction machine capable of suppressing lugging down of an engine irrespective of contents of operation of an operator and the load state of a hydraulic actuator. A controllerincludes: a demanded torque estimating sectionconfigured to estimate demanded torque as torque demanded from an engineby the first hydraulic pump on the basis of a demanded velocity of a first hydraulic actuatorand a load pressure on the first hydraulic actuator; a demanded velocity limiting sectionconfigured to, in a case in which a demanded torque change rate as a change rate of the demanded torque exceeds a predetermined change rate, limit the demanded velocity such that the demanded torque change rate becomes equal to or lower than the predetermined change rate; and a command calculating sectionconfigured to calculate a delivery flow rate of the first hydraulic pump on the basis of the demanded velocity of the first hydraulic actuator, the demanded velocity being limited by the demanded velocity limiting section.

Construction machine

Provided is a construction machine capable of detecting a stuck-open state of a surplus flow control valve in real time during operation without involving a reduction in the operational speed. The construction machine is equipped with: a surplus flow control valve control section configured to output a closing command to a first surplus flow control valve at the operation start when an operation amount signal of an operation lever device is detected; a pump delivery control section configured to output a delivery flow rate command to an adjustment section of an open circuit pump; an assist valve control section configured to continue to output a closing command from before to an assist valve; a sticking detection determination section configured to compare a pressure signal with a previously set threshold value and determining that the surplus flow control valve is in a stuck-open state when the pressure signal is less than the threshold value and determining that the surplus flow control valve is normal when the pressure signal exceeds the threshold value; and a stop signal generating section configured to input therein a sticking determination signal, output in the case of a stuck-open state a control signal maintaining a closed state of the assist valve to the assist valve control section, and output in the case of a normal state a control signal causing the assist valve to perform an opening operation to the assist valve control section.

Growing community of inventors

Tsuchiura, Japan

Shouhei Sugiki