An actuation pressure to actuate one or more hydraulic actuators may be determined based on a load on the one or more hydraulic actuators of a robotic device. Based on the determined actuation pressure, a pressure rail from among a set of pressure rails at respective pressures may be selected. One or more valves may connect the selected pressure rail to a metering valve. The hydraulic drive system may operate in a discrete mode in which the metering valve opens such that hydraulic fluid flows from the selected pressure rail through the metering valve to the one or more hydraulic actuators at approximately the supply pressure. Responsive to a control state of the robotic device, the hydraulic drive system may operate in a continuous mode in which the metering valve throttles the hydraulic fluid such that the supply pressure is reduced to the determined actuation pressure.

A shovel includes a lower traveling structure, an upper swing structure swingably mounted on the lower traveling structure, a first hydraulic pump provided on the upper swing structure, an attachment attached to the upper swing structure, a first actuator, a second actuator, a first directional control valve corresponding to the first actuator, a second directional control valve corresponding to the second actuator, a first conduit connecting the first hydraulic pump and the first directional control valve, a second conduit connecting the first conduit and the second directional control valve, a control valve installed in the second conduit, and processing circuitry configured to control the opening area of the control valve according to information on work details.

A hydraulic system includes a first fixed displacement pump having a first pump output and a second fixed displacement pump having a second pump output. A first actuator requires a first required flow rate to perform a first function. A second actuator requires a second required flow rate to perform a second function. A combined flow control valve is controllable between a first state connecting fluid communication between the first fixed displacement pump and the tank so that only the second pump output is directed to the second actuator, and a second state disconnecting fluid communication between the first fixed displacement pump and the tank to combine the first pump output and the second pump output such that the combined first pump output and the second pump output is directed to the first actuator.

A vehicle includes a chassis, an implement coupled to the chassis, a hydraulic actuator configured to move the implement relative to the chassis, a tractive element coupled to the chassis, a hydraulic motor configured to drive the tractive element to propel the vehicle, a drive pump fluidly coupled to the hydraulic motor, a charge pump coupled to the chassis and configured to provide a flow of pressurized fluid, and a valve assembly fluidly coupled to the charge pump. The valve assembly is configured to (a) direct a first portion of the flow of pressurized fluid to the drive pump and (b) selectively direct a second portion of the flow of pressurized fluid to the hydraulic actuator.

A fluid power system comprises a pump with multiple independently variable outlets, each of which is capable of delivering fluid in individually controllable volume units and a plurality of hydraulic loads. A system of switching valves is configured to create fluid connections between the pump outlets and the loads. A control system commands both the pump and the switching valves, so as to create valve state combinations to satisfy load conditions as demanded by an operator. The number of pump outlets connected to one or more of the loads is changeable to satisfy the flow required of the load due to the operator demand, each pump outlet being commanded to produce a flow depending on the status of other outlets connected a load to which the outlet is connected and the operator demand for that load.

A hydraulic drive system includes a hydraulic pump, a boom-dedicated control valve, a turning-dedicated control valve, a boom-dedicated operation unit, a turning-dedicated operation unit, and a driving control unit. If an operating amount of the turning-dedicated operating portion where a concurrent operation is performed and a single operation is performed are the same, the driving control unit adjusts a turning driving command, that an opening area between the hydraulic pump and a turning motor where the concurrent operation is performed is less than the opening area between the hydraulic pump and the turning motor where the single operation is performed, the concurrent operation wherein the turning operation command is outputted from the turning-dedicated operation unit and a boom operation command is outputted from the boom-dedicated operation unit, the single operation wherein the turning operation command is outputted, but the boom operation command is not outputted from the boom-dedicated operation unit.

An excavator includes a plurality of hydraulic actuators, and a setting unit that performs a setting related to operation speeds of the plurality of hydraulic actuators during a combined operation of the hydraulic actuators, so that when the operation speed of one of the actuators increases, the operation speed of another one of the actuators decreases. The setting unit is capable of performing the setting for a plurality of kinds of combined operations.

A hydraulic system having a hydraulic pump, having a plurality of hydraulic loads and having a plurality of load-sensing valves for adjusting the pump performance of the hydraulic pump. An association unit is arranged between the hydraulic pump and the hydraulic loads and in a first switched state defines a first hydraulic path between the hydraulic pump and the hydraulic loads and in a second switched state defines a second hydraulic path between the hydraulic pump and the hydraulic loads. The system comprises a controller, which processes a state value of a hydraulic load as an input variable and which determines a control signal for the switched state of the association unit. The invention also relates to a method for controlling a hydraulic system.

An excavator includes a hydraulic actuator driven by hydraulic oil discharged from a main pump to move a work element; a first control valve disposed in a center bypass pipeline; a second control valve disposed in a parallel pipeline; and a control device for controlling the movement of the second control valve. The first control valve and the second control valve are formed in a valve block of control valves, and the second control valve is disposed upstream of the first control valve.

A work vehicle includes: a hydraulic pump driven by an engine; a hydraulic actuator that is driven by hydraulic oil supplied from the hydraulic pump; a switching valve configured to switch from one to the other of a first state in which the hydraulic oil supplied from the hydraulic pump is supplied to a first channel and a second state in which the hydraulic oil supplied from the hydraulic pump is supplied to a second channel; a restriction operation device configured to generate an operation signal that restricts the drive of the hydraulic actuator; and a controller that controls the switching valve. The controller includes: an operation signal acquisition unit configured to acquire the operation signal; and an instruction output unit configured to output, to the switching valve, a control instruction that restricts the drive of the hydraulic actuator with the engine driving, in response to the operation signal.