Abstract: A construction machine management system in which a failure analysis or a failure-omen diagnosis of a machine body can be performed with a high degree accuracy and at a low cost is provided. In a machine body group of construction machines including at least one representative machine body having an engine control unit that detects a cumulative stress value of a diesel engine of the construction machine and a crankcase pressure sensor that detects a crankcase pressure, and at least one general machine body that has an engine control unit but does not have a crankcase pressure sensor, a center server performs a diagnosis of an omen of a failure state regarding the crankcase pressure of the general machine body based on correlation information between the cumulative stress value and the crankcase pressure obtained from the representative machine body and the cumulative stress value of the general machine body.

Abstract: Provided are a work machine, a power unit, and a diesel engine of a work machine that make it possible to reduce emitted noxious substances to levels below reference values stipulated by exhaust gas regulations in advanced countries and regions while also omitting or simplifying a post-treatment device. A hydraulic pump is driven by a diesel engine that limits maximum output torque in a low revolution speed region lower than a high revolution speed region including a rated revolution speed in such a manner that the maximum output torque has a characteristic of intermediate torque lower than torque of a maximum output horsepower point at the rated revolution speed, and a hydraulic actuator is driven by hydraulic fluid delivered from the hydraulic pump.

Abstract: The present invention includes a battery controller that calculates an electrical storage remaining amount of a battery, a charging/discharging request calculation part that calculates a charging/discharging request amount for keeping electric power outputted by the battery within a predetermined range based on the electrical storage remaining amount calculated, a target rotational speed calculation part that calculates a target rotational speed command value of a motor generator, and an inverter that controls the motor generator according to the target rotational speed command value calculated, and it is configured that at least one of the battery controller and the inverter calculates the actual charging/discharging amount of the battery, and that the target rotational speed calculation part calculates a target rotational speed correction value from difference between the charging/discharging request amount and the actual charging/discharging amount and corrects the target rotational speed command value.

Abstract: The present invention includes a battery controller that calculates an electrical storage remaining amount of a battery, a charging/discharging request calculation part that calculates a charging/discharging request amount for keeping electric power outputted by the battery within a predetermined range based on the electrical storage remaining amount calculated, a target rotational speed calculation part that calculates a target rotational speed command value of a motor generator, and an inverter that controls the motor generator according to the target rotational speed command value calculated, and it is configured that at least one of the battery controller and the inverter calculates the actual charging/discharging amount of the battery, and that the target rotational speed calculation part calculates a target rotational speed correction value from difference between the charging/discharging request amount and the actual charging/discharging amount and corrects the target rotational speed command value.

Abstract: Provided are a work machine, a power unit, and a diesel engine of a work machine that make it possible to reduce emitted noxious substances to levels below reference values stipulated by exhaust gas regulations in advanced countries and regions while also omitting or simplifying a post-treatment device. A hydraulic pump is driven by a diesel engine that limits maximum output torque in a low revolution speed region lower than a high revolution speed region including a rated revolution speed in such a manner that the maximum output torque has a characteristic of intermediate torque lower than torque of a maximum output horsepower point at the rated revolution speed, and a hydraulic actuator is driven by hydraulic fluid delivered from the hydraulic pump.

Abstract: A construction machine management system in which a failure analysis or a failure-omen diagnosis of a machine body can be performed with a high degree accuracy and at a low cost is provided. In a machine body group of construction machines including at least one representative machine body having an engine control unit that detects a cumulative stress value of a diesel engine of the construction machine and a crankcase pressure sensor that detects a crankcase pressure, and at least one general machine body that has an engine control unit but does not have a crankcase pressure sensor, a center server performs a diagnosis of an omen of a failure state regarding the crankcase pressure of the general machine body based on correlation information between the cumulative stress value and the crankcase pressure obtained from the representative machine body and the cumulative stress value of the general machine body.

Abstract: A construction machine includes an engine, a load estimation unit that estimates a pump power absorption, a regeneration/powering power demand calculation unit that calculates a regeneration/powering power demand according to a state of charge in an electrical storage device, an engine power demand calculation unit that calculates an engine power demand based on the power absorption and regeneration/powering power demand, and a motor generator control unit that performs rotational speed control or torque control. The control unit includes a control switching unit that switches the rotational speed and the torque control according to the engine power demand and the rotational speed of the engine. The control switching unit switches from the torque control to the rotational speed control when during performance of the torque control, the engine power demand increases and the rotational speed of the engine becomes lower than a predetermined rotational speed.

Abstract: The hybrid constructions machine has an engine rotation speed sensor 11A to detect a rotation speed NE of an engine 11, an engine state determination unit 20B to determine the state of output torque TE of the engine 11, a load torque estimation unit 20C to calculate load torque TP of a hydraulic pump 13, and an engine assistance limiting unit 20E to, when the rotation speed NE detected with the engine rotation speed sensor 11A is equal to or greater than a rotation speed N0, and the engine state determination unit 20B determines that the output torque TE of the engine 11 has not become minimum torque Tmin, or the load torque TP calculated with the load torque estimation unit 20C is lower than torque T1, limit motive-power assistance with the motor generator 12 to the engine 11.

Abstract: A construction machine includes an engine, a load estimation unit that estimates a pump power absorption, a regeneration/powering power demand calculation unit that calculates a regeneration/powering power demand according to a state of charge in an electrical storage device, an engine power demand calculation unit that calculates an engine power demand based on the power absorption and regeneration/powering power demand, and a motor generator control unit that performs rotational speed control or torque control. The control unit includes a control switching unit that switches the rotational speed and the torque control according to the engine power demand and the rotational speed of the engine. The control switching unit switches from the torque control to the rotational speed control when during performance of the torque control, the engine power demand increases and the rotational speed of the engine becomes lower than a predetermined rotational speed.

Abstract: The hybrid constructions machine has an engine rotation speed sensor 11A to detect a rotation speed NE of an engine 11, an engine state determination unit 20B to determine the state of output torque TE of the engine 11, a load torque estimation unit 20C to calculate load torque TP of a hydraulic pump 13, and an engine assistance limiting unit 20E to, when the rotation speed NE detected with the engine rotation speed sensor 11A is equal to or greater than a rotation speed N0, and the engine state determination unit 20B determines that the output torque TE of the engine 11 has not become minimum torque Tmin, or the load torque TP calculated with the load torque estimation unit 20C is lower than torque T1, limit motive-power assistance with the motor generator 12 to the engine 11.

Abstract: A priority valve 7 is disposed between a hydraulic pump 2 and a steering valve 4 and is used to supply priority steering cylinders 103a and 103b with pressurized oil discharged from the hydraulic pump 2 by controlling the differential pressure across a meter-in hydraulic line of the steering valve 4 such that the differential pressure is kept at a target value. A pressure sensor 31 for detecting the load pressures of the steering cylinders 103a and 103b is provided. On the basis of the detected load pressures, the target value set for the priority valve 7 is modified by devices including a controller 32, a solenoid valve 33, a pilot hydraulic line 29, and a pressure receiving unit 24c of the priority valve 7. The above configuration enables suppression of a shock occurring at the start of turning of the steering wheel.

Abstract: In a cooling fan drive system for a travel type working machine, the rotational speed of a cooling fan is controlled to the optimum rotational speed in accordance with temperature increase of the temperature of an engine cooling water, and the engine rotational speed is smoothly increased when the engine rotational speed is increased under travel acceleration. A fourth fan target rotational speed calculator 35e and a minimum value selector 35f are provided, and under non-operation, the fan target rotational speed is set to a low rotational speed irrespective of the temperature. When an acceleration pedal 12 is depressed to increase the rotational speed of the engine under travel acceleration, the increase of the drive pressure of a hydraulic motor 23 due to increase of the rotation of the cooling fan 9 is suppressed, and the load on the engine 1 is reduced.

Abstract: A priority valve 7 is disposed between a hydraulic pump 2 and a steering valve 4 and is used to supply priority steering cylinders 103a and 103b with pressurized oil discharged from the hydraulic pump 2 by controlling the differential pressure across a meter-in hydraulic line of the steering valve 4 such that the differential pressure is kept at a target value. A pressure sensor 31 for detecting the load pressures of the steering cylinders 103a and 103b is provided. On the basis of the detected load pressures, the target value set for the priority valve 7 is modified by devices including a controller 32, a solenoid valve 33, a pilot hydraulic line 29, and a pressure receiving unit 24c of the priority valve 7. The above configuration enables suppression of a shock occurring at the start of turning of the steering wheel.

Abstract: In a cooling fan drive system for a travel type working machine, the rotational speed of a cooling fan is controlled to the optimum rotational speed in accordance with temperature increase of the temperature of an engine cooling water, and the engine rotational speed is smoothly increased when the engine rotational speed is increased under travel acceleration. A fourth fan target rotational speed calculator 35e and a minimum value selector 35f are provided, and under non-operation, the fan target rotational speed is set to a low rotational speed irrespective of the temperature. When an acceleration pedal 12 is depressed to increase the rotational speed of the engine under travel acceleration, the increase of the drive pressure of a hydraulic motor 23 due to increase of the rotation of the cooling fan 9 is suppressed, and the load on the engine 1 is reduced.