Abstract: A construction machine is characterized by including: a track structure 10; a swing structure 20 provided on the track structure 10 in a swingable manner; swing motors 25, 27 that drive and swing the swing structure; a boom 31 connected to the swing structure 20; a boom cylinder 32 that moves the boom 31 vertically; a swing operation system 72 that instructs a swing operation of the swing structure 20; a boom operation system 78 that instructs a vertical movement of the boom 31; a detector 74d that detects a bottom pressure of the boom cylinder 32; and a controller 80 that reduces swing speed of the swing structure 20 according to a signal from the detector 74d with respect to a reference swing speed according to a signal of the swing operation, while signals of the swing operation and a boom raising operation are being inputted.

Abstract: Provided is a hybrid-type construction machine including a swing device of the hydraulic-electric combined swing type and by which, in a work for which accurate swing operability is demanded like, for example, a crane work, a swing body is driven alone by the electric motor. The hybrid-type construction machine includes an engine, a hydraulic pump driven by the engine, a swing body, an electric motor for driving the swing body, and a hydraulic motor driven by the hydraulic pump for driving the swing body. The swing body is swung by simultaneous drive by the electric motor and the hydraulic motor. The hybrid-type construction machine includes a control apparatus having a work mode changeover unit by which an operator changes over a mode in response to an aspect of a work and an electric alone swing controlling unit configured to control the swing body to be swung by the electric motor alone.

Abstract: Construction machine capable of incorporating an engine and using an external power source. The construction machine includes an electrical storage device performing a charge with the external power source, uses the electrical storage device to provide assist when the power of the engine is insufficient, uses an electrical charge in the electrical storage device systematically in accordance with work time, and efficiently uses the electrical storage device by controlling its discharge amount in accordance with load status. The construction machine includes the engine, accessory loads connected to the engine, an assist electric motor driven by the engine, electrical power converters for converting an AC current, which is the output current of the assist electric motor, to a DC current, and the electrical storage device connected to the DC side of each electrical power converter. The electrical storage device becomes charged through a charging device from the external power source.

Abstract: To provide a work machine that can suppress a steep fluctuation in engine power.

Abstract: A construction machine including an internal combustion engine controlled based on a torque command, an electric motor mechanically connected to the internal combustion engine, and an electric energy storage device that supplies electric power to the electric motor, the construction machine performing work by driving a hydraulic pressure generator using the internal combustion engine and the electric motor, the construction machine including: a speed control device that controls a speed of the electric motor based on a speed command; and a torque limiter that limits the torque command relative to a torque target, wherein the torque command is limited by the torque limiter in such a manner that a rate of change with time of the torque command is limited to be equal to or less than a predetermined value.

Abstract: A hybrid construction machine is capable of performing satisfactory operations even when trouble occurs that disables the electric motor from outputting torque. The hybrid construction has both a hydraulic motor and an electric motor driving the swing structure and a controller for switching between a hydraulic/electric hybrid swing mode (using both the hydraulic motor and the electric motor) and a hydraulic-alone swing mode (using only the hydraulic motor). The switching is executed while achieving satisfactory operability and performance in each mode. Normally, an energy saving operation is performed in the hydraulic/electric hybrid swing mode. When the electric amount of an electricity storage device has gone out of a prescribed range or an abnormality has occurred in an electric system (e.g., failure of an inverter), the swing mode is switched to the hydraulic-alone swing mode so that driving with normal braking torque is possible by the hydraulic motor alone.

Abstract: To rapidly stop an upperstructure even though relief pressure is lowered due to an abnormality in a hydraulic device included in a swing motor driving circuit while intending to stop the upperstructure when a predetermined delay time has passed since a swing operation tool is brought back to a neutral position, provided are: a first choke for controlling a parking brake to apply a braking force to a swing motor when a predetermined delay time has passed since the tool is brought back to a neutral position in a state where the tool is connected to a pilot pump; and an on-off valve and a second choke for controlling the parking brake to apply a braking force to the motor when a delay time shorter than the predetermined delay time has passed since the tool is brought back to the neutral position and disconnected from the pilot pump.

Abstract: A fuel-efficient hydraulic fluid has a lower viscosity than a standard hydraulic fluid, a pressure loss decreases, and thus, when control based on a standard model is exercised, the speeds of various actuators increase. However, the speeds need not be increased beyond the speeds of the standard model. Instead, it is preferred that fuel efficiency be improved. As a result, an engine revolution speed decreases by 50 rpm and a pump torque decreases by 5%. This reduces an engine output. Therefore, when a hydraulic fluid is changed from the standard hydraulic fluid to the fuel-efficient hydraulic fluid, the fuel efficiency can be improved while maintaining operability equivalent to that of the standard model. Hence, the fuel efficiency can be improved while maintaining the operability when an item affecting the fuel consumption is replaced. In addition, the settings can be changed with ease by a service technician.

Abstract: A hydraulic drive system designed so that while maintaining intact a structure of a relief valve having a shockless function, the drive unit hydraulic drive system facilitates changing a driving pressure or braking pressure of a hydraulic swing motor and hence, changing a maximum driving torque or braking torque of the hydraulic swing motor. Inside a swing motor unit is arranged a first swinging relief valve provided with a shockless function to limit a driving pressure or braking pressure of the hydraulic swing motor in order to prevent the pressure from exceeding a first setting pressure. Also, a second swinging relief valve is provided for limiting the driving pressure or braking pressure of the hydraulic swing motor in order to prevent the pressure from exceeding a second setting pressure that is lower than the first setting pressure.

Abstract: A work machine is adapted for reduced fuel consumption in regions where swinging by a hydraulic motor is prone to deterioration in efficiency, such as when the operating stroke of the swinging is small. The work machine includes an engine, a hydraulic pump, a swing structure, an electric motor for driving the swing structure, and a hydraulic motor for driving the swing structure, the hydraulic motor being driven by the hydraulic pump, and includes a swing control lever device that commands the swing structure to be driven. A control device operates in either an electric swing mode in which the swing structure is driven mainly by torque of the electric motor or a hydraulic swing mode in which the swing structure is driven mainly by torque of the hydraulic motor, depending on an operating stroke of the control lever device and/or a swing speed of the swing structure.

Abstract: A construction machine, comprising a hydraulic pump, a swing hydraulic motor, a swing electric motor, a delivery capacity regulating device, and a control unit which controls the driving/braking of the swing structure, is configured to comprise an operation amount detection device for detecting the operation amount of the swing control lever and a speed detection device for detecting the speed of the swing electric motor. The control unit includes a hydraulic pump output reduction control unit which takes in an operation amount signal representing the operation amount of the swing control lever detected by the operation amount detection device and a speed signal representing the speed of the swing electric motor detected by the speed detection device and controls the delivery capacity regulating device by calculating a reduction rate of the output of the hydraulic pump based on the detection signals.

Abstract: A work machine prevents a fault in a swing electric motor if an uneven coil temperature increase occurs in the swing electric motor during swing press and related operations. An electricity storage device is connected to the electric motor. An inverter drives the electric motor and a swing control lever issues a command to drive the swing structure. A rotational speed detecting device detects swing speed of the swing structure and a controller controls torque of the electric motor. The controller reads the swing speed of the swing structure detected by the rotational speed detecting device to control such that, when the swing speed is zero, the torque of the electric motor is smaller than a maximum torque value and, when the swing speed is a first rotational speed higher than zero, the torque of the electric motor is the maximum torque value.

Abstract: There is provided a hydraulic excavator including a hydraulic pump (6) driven by an engine (7), a boom cylinder (3a) driven by hydraulic fluid delivered from the hydraulic pump (6), a swing motor (16) driven electrically, an operating device (4A) for operating the boom cylinder (3a), an operating device (4B) for operating the swing motor (16), and a vehicle body controller (11) which limits the power of the swing motor (16) in accordance with the operation amount of the operating device (4A) when the two operating devices (4A, 4B) are operated in combination. The power limit value of the swing motor (16) varies depending on the output of the engine (7). This allows a good operational feeling to be retained in combined operation regardless of the operating state of the engine.

Abstract: The hydraulic fluid energy recovery apparatus includes a fluid communication line for holding a bottom-side hydraulic fluid chamber and a rod-side hydraulic fluid chamber of a hydraulic cylinder in fluid communication with each other, a fluid communication valve connected to the fluid communication line for adjusting the pressure and/or flow rate of a hydraulic fluid passing through the fluid communication line in a manner that allows for adjustment of a degree of opening of the fluid communication valve, first pressure detecting means for detecting a signal indicative of pressure at the bottom-side hydraulic fluid chamber of the hydraulic cylinder, an amount-of-operation detecting means for detecting an amount of operation of the operating means, and a control device for capturing the signal of pressure at the bottom-side hydraulic fluid chamber of the hydraulic cylinder detected by the first pressure detecting means.

Abstract: This invention provides a hybrid construction machine including a swing structure, a hydraulic pump, a hydraulic swing motor driving the swing structure using hydraulic fluid from the hydraulic pump, an electric swing motor driving the swing structure in conjunction with the hydraulic swing motor, a boom cylinder operated simultaneously with the swing structure at times and driven by the hydraulic fluid from the hydraulic pump, a first directional control valve controlling flow of the hydraulic fluid supplied from the hydraulic pump to the hydraulic swing motor, a second directional control valve controlling the flow of the hydraulic fluid returning from the hydraulic swing motor, and a controller and solenoid pressure reducing valves which prevent operation of the second directional control valve when the boom cylinder is operated simultaneously with the swing structure.

Abstract: The energy efficiency is increased by reducing the throttle/relief loss in the delivery flow of the hydraulic pump caused by the bleed-off control, while also making it possible to control the delivery pressure of the hydraulic pump according to the operation amount of the control lever unit and improving the operational performance. A controller 6 includes a target pump pressure setting unit 32 which calculates a target pump delivery pressure which increases with the increase in an operation amount signal from an operation amount detector 20A/20B based on the operation amount signal and a pump flow rate upper limit setting unit 33 which calculates a pump flow rate upper limit which increases with the increase in the operation amount signal based on the operation amount signal.

Abstract: The present invention provides an information management system suitable for a construction machine, which drives a solenoid valve separately from normal control to thereby make it possible to perform failure diagnosis for the solenoid valve and each sensor easily and with satisfactory accuracy. A controller has a failure diagnosis mode selected by a control panel of a display device. When the failure diagnosis mode is selected by the control panel and instructions for failure diagnosis related to a specific solenoid valve of a plurality of solenoid valves are given, the controller outputs a failure diagnosis drive signal to the specific solenoid valve, inputs an output value from a sensor related to the specific solenoid valve among a plurality of sensors, and displays, based on the output value from the specific sensor, information as to whether the specific solenoid valve and the specific sensor are normal on a display device.

Abstract: Provided is a work machine including: a variable-displacement pump 2; an actuator 5 driven by a hydraulic fluid delivered from the pump 2; a flow control valve 4 of an open-center type that controls a flow rate of the hydraulic fluid supplied to the actuator 5; a bleed-off line 8a connecting the actuator flow control valve 4 to a tank 6; a bleed-off flow control valve 8 disposed in the bleed-off line 8a; an operating device 3 that specifies operation of the actuator 5; a bleed-off control device 14 that controls a degree of opening of the bleed-off flow control valve 8 in accordance with an amount of manipulation of the operating device 3; and a pump control device 15 that controls, in accordance with the degree of opening of the bleed-off flow control valve 8, a pump flow rate by correcting a reference pump flow rate that is based on the amount of manipulation of the operating device 3.

Abstract: Provided is construction machinery that is capable of greatly reducing the amount of fuel consumption by making effective use of recovered energy. The construction machinery has a first hydraulic pump 3 for discharging hydraulic oil for driving an actuator 6, a second hydraulic pump 9, a second prime mover 7 for driving the second hydraulic pump 9, energy storage device 8 for storing energy for driving the second prime mover 7, and a hydraulic oil supply circuit 10 including a hydraulic oil switching section 11c that accepts the hydraulic oil discharged from the first hydraulic pump and the hydraulic oil discharged from the second hydraulic pump and supplies either the mixture of the accepted hydraulic oils or a selected one of the accepted hydraulic oils to the actuator 6.

Abstract: A construction machine includes: a swing structure (50); a hydraulic pump (1); a hydraulic motor (3) for driving the swing structure (50) using hydraulic fluid from the hydraulic pump (1); an electric motor (14) for driving the swing structure (50) with or without the aid of the hydraulic motor (3); and a hydraulic actuator (16) driven by the hydraulic fluid from the hydraulic pump 1, the hydraulic actuator can be operated together with the swing structure (50). When the swing structure (50) is operated together with the hydraulic actuator (16), only the electric motor (14) is used to swing the swing structure (50).