A mining machine including a bi-directional electrical bus, a power source coupled to the bi-directional electrical bus, a motor coupled to the bi-directional electrical bus, the motor powered by energy available on the bi-directional electrical bus, a kinetic energy storage system coupled to the bi-directional electrical bus and a controller. The controller is configured to communicate with the kinetic energy storage system and the power source. Wherein the controller is configured to operate the kinetic energy storage system as a primary power source for the bi-directional electrical bus and to operate the power source as a secondary power source for the bi-directional electrical bus when the kinetic energy storage system cannot satisfy an energy demand on the bi-directional electrical bus.

The lifetime of an electrical storage device is prolonged by reducing a speed of at least relevant one of hydraulic actuators for a specific operation to be performed by a work machine. This hybrid work machine includes a limit control section. When at least one specific operation defined as predetermined one or more among a plurality of work operations performed by the hybrid work machine is performed under condition of a degree of tendency to deterioration of the electrical storage device becoming higher, the limit control section reduces a speed of at least relevant one of the hydraulic actuators at a rate preset for the specific operation depending on the degree of tendency to deterioration of the electrical storage device.

Disclosed is a hydraulic drive system capable of improving the fuel efficiency of a work machine by reducing the pressure loss and drag loss of a hydraulic pump. There are provided an electric motor M; a third pump P3 driven by the electric motor; a third pump hydraulic line L3 to which the delivered hydraulic fluid from the third pump is supplied; a third directional control valve V4 provided in the third pump hydraulic line, switch-operated by an arm operation device 19, and controlling the flow rate of the hydraulic fluid supplied to the arm cylinder 8 from the third hydraulic pump; and a controller 18 drive-controlling the electric motor, wherein the controller drives the third pump by the electric motor when a swing/arm combined operation is detected by pilot pressure sensors S6, S7, S10, S11.

An HCU (37) includes a battery low temperature reducing output calculating section (71A) that determines, when it is determined that an electricity storage device (31) is in a low temperature state by a battery temperature Tb, a battery low temperature reducing output PbL that is made to a larger value as the battery temperature Tb is lower, a hydraulic oil low temperature reducing output calculating section (71B) that determines, when it is determined that hydraulic oil is in a low temperature state by a hydraulic oil temperature To, a hydraulic oil low temperature reducing output PoL that is made to a larger value as the hydraulic oil temperature To is lower, and an output command calculating section (80) that controls a vehicle body operation based upon a sum of the battery low temperature reducing output PbL and the hydraulic oil low temperature reducing output PoL.

A hydraulic drive system for an electrically-driven hydraulic work machine makes it possible to make a rated voltage of various electric equipment such as power storage devices common to one of an electrically-driven hydraulic work machine that is capable of being operated with lower horsepower and to prevent that only a power storage situation of one of the plurality of power storage devices significantly degrades together with operation of the electrically-driven hydraulic work machine and besides, to extend a time period within which each of actuators of the electrically-driven hydraulic work machine can obtain a predetermined speed. Accordingly, a controller 50 includes a virtual limitation torque calculation section 51 and electric motor rotational speed control sections 52 and 53. Variable horsepower control tables 52r and 53r are provided in the electric motor rotational speed control sections 52 and 53, and limit values q1*limit and q2*limit for a virtual displacement of the variable horsepower control tables 52r and 53r are changed such that a charge state of a power storage device 170 and a charge state of another power storage device 270 become equal to each other.

An output command calculating section (40) of an HCU (36) restricts a battery discharge power from an electricity storage device (31) based upon a battery electricity storage rate (SOC) and a current square integrating rate (Risc) of the electricity storage device (31). Thereby, the HCU (36) transfers from a normal mode (NMODE) to a low speed mode (LSMODE) to lower a movement speed of a hydraulic actuator. A monitor display amount calculating section (50) of the HCU (36) calculates a maximum speed reduction rate (DRs) based upon a battery discharge power limit value (Plim0) and an engine output upper limit value (Pemax) from the output command calculating section (40). A monitor device (39) displays a reduction rate of the movement speed of the hydraulic actuator in the low speed mode (LSMODE) based on the maximum speed reduction rate (DRs).

Provided is a hybrid work machine in which a hybrid system and a downsized engine are used. The hybrid work machine performs rapid charging of a power storage device while preventing decreases in the output power of a hydraulic pump. A vehicle body controller performs engine revolution speed decreasing control in which, if the charge rate of a battery becomes equal to or less than a minimum charge rate, the target revolution speed of an engine is reduced. The vehicle body controller also performs torque reducing control in which the maximum absorption torque of a hydraulic pump is reduced. By performing these control operations, the vehicle body controller coercively generates surplus torque for the engine and operates a generator-motor as a generator.

A system for preventing an engine included in a work machine from restarting, after the work machine is tipped over. A sensor included in the work machine is configured to detect a tipping incident. If a tipping incident is detected, the sensor sends out a signal configured to shut down the engine and a tilt signal configured to prevent the engine from restarting. The engine is only restarted if certain steps are undertaken by an operator and a reset switch is activated.

An intelligent work vehicle preheating system includes an electric drive subsystem containing a battery pack, a hydraulic subsystem containing a first hydraulic fluid (HF) heating device, and a first HF temperature sensor. A memory stores a first minimum target temperature at or above which a first hydraulic fluid body contained in the hydraulic subsystem is desirably maintained. A controller architecture selectively places the intelligent work vehicle preheating system in an off-duty preheat mode when the electric drive subsystem is connected to an external power supply utilized to charge the battery pack. The controller architecture further controls the HF heating device to heat the first hydraulic fluid body when (i) the intelligent work vehicle preheating system is placed in the off-duty preheat mode, and (ii) the current temperature of the first hydraulic fluid body is less than the first minimum target temperature.

A power system may include a high-speed flywheel connected to an engine of a machine; a battery; a motor-generator unit (MGU) connected to the engine and the battery; and a turbocharger connected to the engine. One or more of the high-speed flywheel, the battery and the MGU, or the turbocharger may be configured to provide supplemental power to power provided by the engine to operate the machine, or provide replacement power when no power is provided by the engine to operate the machine.