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.

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 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.

An example valve assembly includes a first workport fluidly coupled to a first actuator; a second workport fluidly coupled to the first actuator; a third workport fluidly coupled to a second actuator, wherein the third workport is fluidly coupled to the first workport via a first fluid passage; a fourth workport fluidly coupled to the second actuator, wherein the fourth workport is fluidly coupled to the second workport via a second fluid passage; and a spool axially movable in a bore within the valve assembly, wherein when the spool is shifted axially in a first axial direction, pressurized fluid is provided to the first workport and to the third workport via the first fluid passage, and when the spool is shifted axially in a second axial direction opposite the first axial direction, pressurized fluid is provided to the second workport and to the fourth workport via the second fluid passage.

An example valve assembly includes a first workport fluidly coupled to a first actuator; a second workport fluidly coupled to the first actuator; a third workport fluidly coupled to a second actuator, wherein the third workport is fluidly coupled to the first workport via a first fluid passage; a fourth workport fluidly coupled to the second actuator, wherein the fourth workport is fluidly coupled to the second workport via a second fluid passage; and a spool axially movable in a bore within the valve assembly, wherein when the spool is shifted axially in a first axial direction, pressurized fluid is provided to the first workport and to the third workport via the first fluid passage, and when the spool is shifted axially in a second axial direction opposite the first axial direction, pressurized fluid is provided to the second workport and to the fourth workport via the second fluid passage.

Provided is a hydraulic machine. A pump pressurizes fluid using power provided by a power source. An actuator works using the pressurized fluid from the pump. A recovery part recovers energy from fluid discharged from the actuator. A first operator input device receives a desired input from an operator to select an eco-mode or a boost mode. The recovery part includes an accumulator storing hydraulic energy by receiving the fluid discharged from the actuator and an assist unit assisting the power source using the hydraulic energy stored in the accumulator. The controller controls the pump such that output power of the pump does not exceed Plmax when the eco-mode is selected or the assist unit does not assist the power source and that the output power does not exceed P2max when the boost mode is selected and the assist unit assists the power source, where Plmax < P2max.

A control system includes a closing unit including a tank including a usable volume of the control system, at least one primary pump configured to pump hydraulic fluid from the usable volume of the tank, a plurality of valves, and a first pressure transducer disposed between the at least one primary pump and at least one valve of the plurality of valves. The at least one primary pump, the pressure transducer, and the at least one valve of the plurality of valves are hydraulically connected with the tank. The first pressure transducer manages a start-stop operation of the at least one primary pump. Hydraulic fluid within the control system has a predetermined static pressure. The at least one pump is powered by an electric energy source.

Device for recovering hydraulic energy in a machine comprising at least a first differential cylinder-piston assembly having a differential cylinder with a separate rod and base side, at least a second differential cylinder-piston assembly having a differential cylinder with a separate rod and base side, and at least one hydraulic accumulator that can be hydraulically connected to at least one of the differential cylinder-piston assemblies, wherein the differential cylinder-piston assemblies are mechanically coupled to one another, and wherein the potential energy of at least one of the differential cylinder-piston assemblies retracting under a compressive load can at least partially be stored in the hydraulic accumulator.

An apparatus for recuperating hydraulic energy in a working machine includes at least one first differential cylinder piston device with a differential cylinder and separate rod and bottom sides, and at least one hydraulic accumulator which is hydraulically connectable with the differential cylinder piston device. The potential energy of the differential cylinder piston device retracting under pressing load is at least partly storable in the hydraulic accumulator. The rod and bottom sides are connectable with each other via at least one brake valve for recirculating hydraulic fluid from the bottom side into the rod side.

An apparatus for recuperating hydraulic energy in a working machine includes at least one first differential cylinder piston device with a differential cylinder and separate rod and bottom sides, and at least one hydraulic accumulator which is hydraulically connectable with the differential cylinder piston device. The potential energy of the differential cylinder piston device retracting under pressing load is at least partly storable in the hydraulic accumulator. The rod and bottom sides are connectable with each other via at least one brake valve for recirculating hydraulic fluid from the bottom side into the rod side.