The present invention provides a construction machine equipped with a pressure accumulation device that accumulates return oil from an actuator, and that can implement both improvement in fuel efficiency with enhancement in workability. To achieve the foregoing, a controller sets an actuator upper limit output power that is an upper limit for an output power of the actuator according to a work mode selected by a work mode selection device, and controls a first control valve and a second control valve such that a sum of an output power of a hydraulic pump and an output power of the pressure accumulation device does not exceed the actuator upper limit output power.

In a hydraulic system for a working machine, a controller is configured or programmed to increase an output-port pressure of one activation valve for one hydraulic device and an output-port pressure of another activation valve for another hydraulic device to a normal pressure higher than a preloading pressure from a state where the output-port pressure of the one activation valve is equal to the preloading pressure and the output-port pressure of the other activation valve is lower than the preloading pressure, by causing the output-port pressure of the one activation valve to be lower than the preloading pressure and increasing the output-port pressure of the other activation valve to the normal pressure.

It is made possible to perform power reduction control during non-operation of control levers, suppress a return to a normal power state when a control lever is accidentally moved, and make a smooth transition to an operation desired to be performed when a return is made to the normal power state. To this end, in a power reduction state, when a first cancellation condition in which two or more control levers are inclined simultaneously is satisfied or when a second cancellation condition in which one lever continues to be inclined is satisfied, a controller 50 determines that an operator “has an intention of canceling power reduction” and cancels power reduction control.

A power machine can include an engine control module configured to determine a target operational speed of the power machine and control the engine based on the target operational speed. A drive controller can be configured to control operation of a hydraulic drive pump or other work element to decrease engine speed toward a target stabilization speed that is lower than the target operational speed.

A control system is provided for a diesel particulate filter (DPF) system of a diesel engine configured for operation in an off-highway vehicle. The control system includes a controller configured to receive a signal corresponding to a fill state of the DPF being at or above a first threshold. The controller is configured to selectively induce a parasitic load on the diesel engine to increase an operating temperature of the engine in response to receiving the signal.

A hydraulic control system for use with a work machine. The work machine has a platform which supports an operator. When the operator is not on the platform, the platform moves into a first position, causing a signal generator to send a signal to a controller. The controller is configured to limit the hydraulic flow to the ground drive motor when the platform is in the first position. The controller may directly reduce operation of the engine, or may adjust a valve which diverts a portion of hydraulic flow. The limitation may be overridden when desired by the operator.

A hydraulic excavator as an electric work machine includes a lower traveling body, an upper swivel body located above the lower traveling body and provided to be swivelable with respect to the lower traveling body, an electric motor arranged in the upper swivel body, a hydraulic pump arranged in the upper swivel body and driven by the electric motor, a battery unit arranged in the upper swivel body and storing electric power to drive the electric motor, and a hydraulic actuator driven by hydraulic oil supplied from the hydraulic pump. The upper swivel body has a swivel frame at a bottom portion thereof. The battery unit is arranged on the swivel frame. The electric motor and the hydraulic pump are arranged on the swivel frame, side by side in a left-right direction of the upper swivel body.

In a working machine, a traveling pump is driven by a prime mover to rotate a traveling motor by fluid therefrom. The traveling motor has a rotation speed shiftable between a lower first speed and a higher second speed. A traveling change-over valve is shiftable between a first state where the rotation speed of the traveling motor is set to the first speed and a second state where the rotation speed of the traveling motor is set to the second speed. A controller performs a shock-mitigation for reducing a rotation speed of the prime mover when the traveling change-over valve is shifted from the second state to the first state. The controller determines a reduction amount of rotation speed of the prime mover reduced by the shock mitigation based on a difference between a target rotation speed of the prime mover and an actual rotation speed of the prime mover.

The disclosure concerns an electronic control unit for a hydraulic system, the hydraulic system comprising a pump drivingly coupled to a motor, the pump configured to provide a supply pressure in a supply line of the hydraulic system. The electronic control unit is configured to receive a load sensing signal corresponding to a sensed load measure of the hydraulic system; determine, based on the load sensing signal and a predetermined pump margin, a target torque parameter for the motor; and adjust the motor based on the target torque parameter. The disclosure further concerns a hydraulic system and a method for controlling a hydraulic system.

A work machine includes an engine, a travel drive system, a work implement, an apparatus drive system with a hydraulic pump, an accelerator operating member, a work implement operating member, and a controller. The controller controls the apparatus drive system in accordance with an operating amount of the work implement operating member. The controller determines a target tractive force of the travel drive system based on an operating amount of the accelerator operating member. The controller determines an allowable acceleration of the work machine. The controller determines an upper limit of tractive force of the travel drive system based on the allowable acceleration. The controller corrects the target tractive force so as to be equal to or less than the upper limit when the target tractive force is greater than the upper limit. The controller controls the travel drive system based on the corrected target tractive force.