Abstract: To increase frequency of use of auto idle, an engine is accelerated even more quickly than before and work involving a heavy load can be performed within a short period of time when an operator resumes work and recovers a speed of the engine. When an operation lever device is operated and the speed is low because of auto idle control, a pilot pump is unloaded to thereby reduce load torque on the engine. Operation of a compressor is also suspended while an air conditioner is operating. Furthermore, for a target speed of the engine, a speed at which work can be performed is set and the engine is accelerated. When the engine thereafter reaches a predetermined speed or a predetermined period of time thereafter elapses, the pilot pump is loaded and the operation of the compressor for the air conditioner is resumed.

Abstract: Provided is a work machine hydraulic control system capable of detecting abnormality in a pump output power switching device independently of the abnormality state of the pump output power switching device. A hydraulic control system of a hydraulic excavator is equipped with an accumulator 21 connected to a hydraulic line 25A between a pilot pump 17 and a pilot valve 20, an unloading valve 27 that is a pump output power switching device, a pressure sensor 29 detecting the pressure of the hydraulic fluid supplied to the pilot valve 20, and a controller 30 having a pump output power control section 31 switching the unloading valve 27 in accordance with the pressure detected by the pressure sensor 29. The controller 30 further has an abnormality determination section 32 that computes a command continuation time in a state in which a command output to the unloading valve 27 is not changed.

Abstract: The first engine speed or a work machine is higher than the minimum engine speed, and the second engine speed is higher than the first engine speed and lower than the maximum engine speed. The ratio of the change in the target engine speed to the change in the operation amount of the engine speed instructing device when the operation amount of the engine speed instructing device is changed from the operation amount for instructing the minimum speed to the operation amount for instructing the first engine speed is larger than the ratio of the change in the target engine speed to the change in the operation amount of the engine speed instructing device when the operation amount of the engine speed instructing device is changed from the operation amount for instructing the second engine speed to the operation amount for instructing the maximum speed.

Abstract: A hydraulic circuit (11) of a hydraulic excavator (1) is provided with a main hydraulic circuit (11A) including a boom cylinder (5D), a pilot hydraulic circuit (11B) for operating the boom cylinder (5D) and a recovery hydraulic circuit (11C) including an accumulator (29). In this case, the recovery hydraulic circuit (11C) is provided with a recovery control valve (31) that recovers pressurized oil discharged from the boom cylinder (5D) to the accumulator (29), a main supply control valve (34) for supplying pressurized oil accumulated in the accumulator (29) to the main hydraulic circuit (11A) and a pilot supply control valve (37) for supplying pressurized oil accumulated in the accumulator (29) to the pilot hydraulic circuit (11B).

Abstract: A control apparatus for a hybrid construction machine includes an engine, a motor generator driven by the engine and capable of generating electric power, a hydraulic pump driven by total torque of the engine and the motor generator, a power storage device, an inverter, a filter that collects a particulate material in exhaust gas of the engine, and a control section outputting a command signal for controlling powering operation or regeneration operation of the motor generator. The control apparatus further includes a powering operation limitation section that inputs thereto an ordinary torque command calculated by a torque command value calculation section and a demand signal for regeneration of the filter decided by a filter regeneration decision section and calculates the command signal in response to the input signals. When a filter regeneration demand signal is available, a command signal for limiting the powering operation of the motor generator is calculated.

Abstract: An object of the present invention is to provide a working machine and a working machine monitoring system using the same which is capable of improving the accuracy in determining fuel property. The working machine is provided with an engine operation parameter acquisition module (1041) that acquires an engine operation parameter representing the operation state of an engine mounted on the working machine; a refueling time acquisition module (1011) that acquires a refueling time when the working machine is supplied with fuel; and a fuel property determination module (1014) that determines the property of the fuel based on a comparison result of the time when the engine operation parameter changes, with the refueling time.

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: The invention provides a construction machine in which the load torque at the time of engine start-up can be reduced even when the engine stops against the will of the operator. A hydraulic excavator includes a control device (35) having a pump displacement control section (37) and an unload control section (38). The pump displacement control section (37) makes the displacement of a hydraulic pump (16) variable to a minimum displacement by controlling a regulator device (20) when the speed of an engine (14) detected by a speed sensor (41) becomes equal to or less than a preset low speed N3 at the time of driving of the engine (14). The unload control section (40) controls an unloading valve (24) to the open position at the time of start-up of the engine (14).

Abstract: A work machine including: a hydraulic cylinder 20 configured to drive a work implement 3; a control valve 22 configured to connect a delivery line of a hydraulic pump 21 switchingly to a bottom fluid chamber and a rod fluid chamber of the hydraulic cylinder 20 and a tank; a pilot pump 23 configured to output a pilot pressure to drive the control valve 22; an engine 24 configured to drive the hydraulic pump 21 and the pilot pump 23; and an accumulator 26 configured to accumulate a return hydraulic fluid from the hydraulic cylinder 20 is provided with: a bypass line 41 configured to connect the bottom fluid chamber of the hydraulic cylinder 20 and a delivery line 21a of the hydraulic pump 21 by bypassing the control valve 22 and be provided with the accumulator 26 thereon; a pressure-accumulation control valve 27 provided between the bottom fluid chamber of the hydraulic cylinder 20 and the accumulator 26; a release control valve 28 provided between the accumulator 26 and the delivery line 21a; and a hydraulic

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 construction machine includes: a control valve that switchingly supplies hydraulic fluid from a hydraulic pump to a hydraulic actuator; a control valve drive device that supplies pilot secondary hydraulic fluid to the control valve in accordance with an operation of an operation lever device; a pilot hydraulic pump that supplies pilot primary hydraulic fluid to the control valve drive device; a pressure accumulation device that recovers return hydraulic fluid returned from the hydraulic actuator. The construction machine further includes: a check valve provided in a line between the pilot hydraulic pump and the control valve drive device; a pressure reducing valve that supplied the hydraulic fluid accumulated in the pressure accumulation device; a flow rate reduction device; and a controller that controls the flow rate reduction device in accordance with the pressure in the line between the check valve and the control valve drive device.

Abstract: An object of the present invention is to provide a working machine and a working machine monitoring system using the same which is capable of improving the accuracy in determining fuel property. The working machine is provided with an engine operation parameter acquisition module (1041) that acquires an engine operation parameter representing the operation state of an engine mounted on the working machine; a refueling time acquisition module (1011) that acquires a refueling time when the working machine is supplied with fuel; and a fuel property determination module (1014) that determines the property of the fuel based on a comparison result of the time when the engine operation parameter changes, with the refueling time.

Abstract: A hybrid work machine includes: an engine controller (14) that controls rotational speed of an engine (7) in accordance with a target rotational speed input from an EC dial (31); an assist motor (10) that generates electricity using power of the engine (7); a hydraulic pump (6) operated using power of the engine and/or of the assist motor; and a vehicle body controller (11) that estimates power (Pe) the engine is required to output when a request to generate electricity is sent to the assist motor and permits the assist motor to generate electricity only when the engine power requirement is not greater than an electricity generation threshold value (Eth1). The electricity generation threshold value (Eth1) is determined based on the power and characteristics of energy loss of the engine (7).

Abstract: The first engine speed or a work machine is higher than the minimum engine speed, and the second engine speed is higher than the first engine speed and lower than the maximum engine speed. The ratio of the change in the target engine speed to the change in the operation amount of the engine speed instructing device when the operation amount of the engine speed instructing device is changed from the operation amount for instructing the minimum speed to the operation amount for instructing the first engine speed is larger than the ratio of the change in the target engine speed to the change in the operation amount of the engine speed instructing device when the operation amount of the engine speed instructing device is changed from the operation amount for instructing the second engine speed to the operation amount for instructing the maximum speed.

Abstract: The invention provides a construction machine in which the load torque at the time of engine start-up can be reduced even when the engine stops against the will of the operator. A hydraulic excavator includes a control device (35) having a pump displacement control section (37) and an unload control section (38). The pump displacement control section (37) makes the displacement of a hydraulic pump (16) variable to a minimum displacement by controlling a regulator device (20) when the speed of an engine (14) detected by a speed sensor (41) becomes equal to or less than a preset low speed N3 at the time of driving of the engine (14). The unload control section (40) controls an unloading valve (24) to the open position at the time of start-up of the engine (14).

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: To provide construction machinery capable of more efficiently utilizing the energy of return hydraulic oil from a hydraulic actuator.

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: To provide a construction machine that appropriately sets the magnitude of an engine output for each work mode. A construction machine according to the present invention includes: an engine (22); a generator-motor (23) configured to generate electric power by the engine; a hydraulic pump (41) configured to be driven by the engine and the generator-motor; a hydraulic actuator (32, 34, 36) that drives and operates a working device (30) with the power of the hydraulic pump; an electric storage device (24) for supplying electric power to drive the generator-motor and charging the electric power generated by the generator-motor; a work-mode selecting device (45, 46) that selects a work mode corresponding to operation of an operator; and an engine-output setting unit (403, 405, 407) that sets the magnitude of the output of the engine corresponding to the work mode selected by the work-mode selecting device.