A construction machine including a variable displacement pump, and a boom cylinder including a rod operable to extend and retract to move a boom of the construction machine. A first chamber of the boom cylinder is configured to be supplied with fluid from the pump during rod extension while fluid is removed from a second chamber of the boom cylinder. The second chamber of the boom cylinder is configured to be supplied with fluid from the pump during rod retraction while fluid is removed from the first chamber of the boom cylinder. The construction machine has an active ride control mode in which a valve between the boom cylinder and the pump remains open, and the pump is configured to actively damp pressure fluctuations in the boom cylinder by variation of a displacement setting.

A hydraulic system includes: an arm hydraulic cylinder; a first hydraulic pump and a second hydraulic pump; an arm first direction switching valve; an arm second direction switching valve; and a controller that controls an operation of the arm second direction switching valve when the arm hydraulic cylinder is extended and operated. Further, the arm first direction switching valve incorporates an arm regeneration passage capable of supplying oil when the arm hydraulic cylinder is extended and operated, and the controller monitors a pressure state of the arm hydraulic cylinder, and when determining that oil flow through the arm regeneration passage is possible, the controller blocks oil flow between the arm hydraulic cylinder and the arm second direction switching valve, and otherwise, the controller operates the arm second direction switching valve so that oil can be supplied from the second hydraulic pump to the bottom chamber.

A hydraulic system for a working machine, the hydraulic system includes: a hydraulic fluid reservoir; a boom actuator having an ascending chamber and a descending chamber; a first pump; a first directional control valve comprising a first ascending state configured for moving the boom in the ascending direction, a descending state configured for moving the boom actuator in the descending direction, and a first neutral state; a second pump; a second directional control valve comprising a second ascending state configured for moving the boom actuator in the ascending direction, and a second neutral state; wherein the second directional control valve further comprises a float state configured to connect at least one of the ascending and descending chambers to the hydraulic reservoir for permitting the boom to move freely in the descending and/or descending directions.

Provided is a work vehicle capable of satisfying a user's demand to brake performance in a flexible manner. A wheel loader 1 comprises a controller 5 storing a plurality of control characteristics each of which is set such that a brake valve control pressure Pi of a solenoid proportional valve 45 increases as a pedal angle θ of a brake pedal 43 increases, and under the condition where a pedal angle θ is equal to or less than a predetermined pedal angle θ, an increase rate of the brake valve control pressure Pi with respect to the pedal angle θ varies. In a case where the pedal angle θ detected by a potentiometer 33 is equal to or less than the predetermined pedal angle θth, the controller 5, calculates the brake valve control pressure Pi based on the selected one control characteristic.

Provided is a work machine which can increase the operation speed of an actuator by a regeneration function while securing the position control accuracy of the actuator. A controller is configured to calculate a regeneration flow rate on the basis of an input amount of an operation lever and a target actuator flow rate, subtract the regeneration flow rate from the target actuator flow rate to calculate a target actuator supply flow rate, calculate a target flow rate control valve opening amount on the basis of the target actuator supply flow rate, calculate a target pump flow rate that is equal to or higher than a total target actuator supply flow rate, control a selector valve on the basis of the input amount of the operation lever, control a flow rate control valve according to the target flow rate control valve opening amount, and control a hydraulic pump according to the target pump flow rate.

An object of the present invention is to provide a construction machine that can use the return oil from a hydraulic actuator effectively. For this purpose, a controller computes a flow rate of the return oil from a first hydraulic actuator on the basis of an operation signal from a first operation device, computes a flow rate of oil to be supplied to a second hydraulic actuator on the basis of an operation signal from a second operation device, sets smaller one of the flow rate of the return oil and the flow rate of the oil to be supplied, as a regeneration flow rate that is a flow rate of oil to be regenerated in the second hydraulic actuator, sets a flow rate obtained by subtracting the regeneration flow rate from the flow rate of the return oil, as a recovery flow rate that is a flow rate of oil to be recovered to a pressure accumulating device, adjusts an opening degree of a first control valve 2 such that a flow rate of oil supplied from the first hydraulic actuator to the pressure accumulating device coincides with the recovery flow rate, and adjusts an opening degree of a second control valve such that a flow rate of oil supplied from the first hydraulic actuator to the second hydraulic actuator coincides with the regeneration flow rate.

The present disclosure relates to a hydraulic-electric coupling driven multi-actuator system and control method, and belongs to technical fields of hydraulic transmission and electro-mechanical transmission. The hydraulic-electric coupling driven multi-actuator system comprises one or more hydraulic-electric hybrid driven actuators, first inverters, control valves, centralized hydraulic units and control units, wherein the number of the first inverters and the number of the control valves are the same as that of the hydraulic-electric hybrid driven actuators; each hydraulic-electric hybrid driven actuator is correspondingly connected with one first inverter and one control valve; the centralized hydraulic units are connected with the control valves and configured to supply oil for the hydraulic-electric hybrid driven actuators and to perform power compensation; and the control units are respectively connected with the hydraulic-electric hybrid driven actuators, and each control unit is configured to control output torque of a first motor of the corresponding hydraulic-electric hybrid driven actuator based on pressure information of the hydraulic-electric hybrid driven actuator, such that pressure of driving cavities of the hydraulic-electric hybrid driven actuators is equal, which greatly reduces throttling loss caused by the load differences of the actuators.

A transmission system includes a transmission assembly having clutches to transmit power from an input shaft to an output shaft at a plurality of gear ratios. A traction motor drives the input shaft and propels the work vehicle, while a controller controls operation of the transmission assembly and the traction motor. A hydraulic circuit controls actuation of the clutches responsive to commands from the controller. The hydraulic circuit includes a hydraulic pump driven by the traction motor, an accumulator connected to the hydraulic pump and that holds hydraulic fluid therein under pressure, and an unloading valve positioned in a secondary fluid path running from an outlet of the hydraulic pump to a sump. The unloading valve operates in a closed state to direct hydraulic fluid from the hydraulic pump to the accumulator and operates in an open state to direct hydraulic fluid from the hydraulic pump to the sump.

A hydrostatic drive includes at least one hydrostatic pump configured to supply at least one hydrostatic consumer and an apparatus for an energy recovery procedure of at least a part of the energy that is output by the consumer. An electronic control unit or at least one software component is further included, with which the energy recovery procedure is controlled in a variable manner and depends upon detected influencing variables.

A hydraulic system for a machine includes an implement pump, a valve, and an implement valve subsystem. The implement pump includes a load sensing control, and the valve controls the flow of hydraulic fluid to the implement pump. The implement valve subsystem includes one or more implement control subsystems to control movement of an implement. The valve is an electrohydraulic proportional relief valve and includes a solenoid configured to adjust the pressure of hydraulic fluid delivered to the implement pump proportionally to a current delivered through the solenoid.