An object of the present invention is to provide a work machine that can increase the operation speed of an actuator by a regenerating function while ensuring accuracy of position control of the actuator. For this purpose, a controller computes a target actuator supply flow rate by subtracting a regeneration flow rate from a target actuator flow rate, computes a target flow control valve opening amount on the basis of the target actuator supply flow rate, computes a target pump flow rate equal to or more than the sum of a plurality of the target actuator supply flow rates, controls flow control valves according to the target flow control valve opening amount, and controls a hydraulic pump according to the target pump flow rate.

A shovel enabled to set an engine revolution speed to revolution speeds including a revolution speed for a running operation and a revolution speed for an idling running operation that is lower than the revolution speed for the running operation includes an engine provided as a driving source of the shovel, an operating part configured to be driven by a driving force of the engine, an operation component configured to operate the operating part, a detecting device configured to detect a position of a movable portion of an operator and a position of the operation component, an operation determining part configured to determine a positional relationship between the movable portion and the operation component, and a control part configured to set the engine revolution speed of the engine based on the positional relationship between the movable portion and the operation component that is determined by the operation determining part.

A prime mover and hydraulic actuators, a hydraulic machine having a rotatable shaft engaged with the prime mover and having a plurality of working chambers, a hydraulic circuit extending between a group of working chambers of the hydraulic machine and the hydraulic actuators, each working chamber of the hydraulic machine having a low-pressure and a high-pressure valve regulating the flow of hydraulic fluid between the working chamber and a corresponding low-pressure manifold and a high-pressure manifold. The hydraulic machine controlling the low-pressure valves of the group of working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the group of working chambers, responsive to a demand signal, the apparatus further having a controller calculating the demand signal responsive to a measured property of the hydraulic circuit or an actuator.

A prime mover and a plurality of hydraulic actuators, a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising working chambers, a hydraulic circuit between working chambers of the hydraulic machine and the hydraulic actuators, each working chamber of the hydraulic machine comprising a low-pressure and high-pressure valves regulating the flow of hydraulic fluid between the working chamber and a corresponding low-pressure manifold and a high-pressure manifold. The hydraulic machine being configured to actively control the low-pressure valves of the working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the working chambers, responsive to a demand signal, wherein the apparatus further comprises a controller configured to calculate the demand signal in response to a measured property of the hydraulic circuit or actuators.

An energy recovery system for a machine having a movable work tool, a swing motor to swing the work tool about a vertical axis, a pump providing pressurized fluid to the swing motor, a power source outputting power to drive the pump, and a controller. The energy recovery system may include a first accumulator, a swing charge valve selectively connecting the swing motor to the first accumulator, an assist motor operatively connected to the power source, and a discharge selectively connecting the first accumulator to the assist motor. The swing charge valve may fluidly connect the swing motor to the first accumulator when fluid pressure from the swing motor is greater than a charge set pressure. The controller may cause the discharge valve to fluidly connect the first accumulator with the assist motor when the power demand on the power source is greater than a minimum assisted power demand.

A system for controlling hydraulic fluid flow within a work vehicle includes a flow control valve fluidly coupled to a fluid supply conduit upstream of a hydraulic actuator such that the flow control valve is configured to control the flow rate of hydraulic fluid to the hydraulic actuator. Furthermore, the system includes a computing system configured to receive an input associated with a selected flow rate of the hydraulic fluid being supplied to the hydraulic actuator. Moreover, the computing system is configured to control an operation of the flow control valve such that flow control valve is at a maximum flow position at which an adjustable orifice defined by the valve has a maximum cross-sectional area. Additionally, the computing system is configured to control an operation of a pump such that the pump supplies the hydraulic fluid to the hydraulic actuator through the adjustable orifice at the selected flow rate.

A method of operating a variable displacement pump in a pressurized fluid supply system for an agricultural vehicle, including maintaining a constant displacement of the pump as rotational speed of the input drive to the pump increases to a first value of 1500 rpm and thereafter adjusting the displacement of the pump to maintain a constant output fluid flow 230 L/min or reduced flow as rotational speed of the input drive to the pump increases beyond the first value to a maximum value of 2100 rpm.

A hydraulic system includes: hydraulic actuators; a control valve for controlling the hydraulic actuators; a tank for storing a hydraulic operation fluid; a variable displacement pump for supplying the hydraulic operation fluid to the hydraulic actuators; a regulator for controlling the variable displacement pump; a pilot pump for discharging a hydraulic pilot fluid; a load sensing system for maintaining a differential pressure to be a constant pressure, the differential pressure being obtained by subtracting a second signal pressure from a first signal pressure that is the discharge pressure of the variable displacement pump, the second signal pressure being the maximum one of the load pressures generated in the hydraulic actuators; a signal tube for sending the second signal pressure to the regulator; a throttle provided on the signal tube; and a warm-up circuit for supplying the hydraulic pilot fluid to a downstream side of the throttle.

A control system for a machine is disclosed. The control system may have a bypass passage situated to allow fluid to bypass an actuator, and a warmup valve disposed within the bypass passage that is movable between flow-passing and-blocking positions. A controller is configured to move the warmup valve to the flow-passing position, fix a displacement position of the pump, compare the pressure of the fluid of the actuator with a threshold, and move the warmup valve to the flow-blocking position and reduce a pump outlet pressure when the pressure of the fluid is greater than the threshold. The controller may be configured to move the warmup valve to the flow-passing position, fix a displacement position of the pump, and adjust an input speed of the pump in response to the signal.

Provided is a construction machine on which a hydraulic closed circuit for driving a single rod-type hydraulic cylinder and a swing hydraulic motor is mounted and that has good swing deceleration responsiveness. In this construction machine that drives each of a single rod-type hydraulic cylinder and a swing hydraulic motor in a closed circuit, a minimum passage area from a second flushing valve to a tank in a case the second flushing valve is fully open is smaller than a minimum passage area from a first flushing valve to the tank in a case the first flushing valve is fully open.