Systems, methods and devices are described providing a selective hydraulic or electrically powered prime mover that is a bi-directional power unit system, including movement within a device used to compress and/or expand a fluid and provide fluid movement. The use of a hydraulic power unit is involved and comprises at least a pump or other fluid moving device, a first set of selective control valves delivering pressurized fluid to the device(s), and a second set of selective control valves returning unpressurized fluid from the device(s), a reservoir comprising a compensator tank, a port for operation at ambient pressure, and a pressure measuring device measuring ambient pressure allowing for unbalanced flow to and from the device as well as thermal expansion or compression. The use of a multiport and in some cases a swashplate pump that incorporates the features and functions of several valves for the system is also described.

A device for filling a hydraulic circuit of an electro-hydrostatic system provided with a discharge valve and a filling valve includes a vacuum generator designed to be connected to the discharge valve via a first shut-off valve in order to eliminate the air or gases present in the circuit, and a source for supplying pressurised hydraulic fluid, which source is designed to be connected to the filling valve via a second shut-off valve and to the discharge valve and the first shut-off valve via a third shut-off valve in order to fill the hydraulic fluid circuit.

A hydraulic system includes a first electric machine connected to a first hydraulic machine and a second electric machine connected to a second hydraulic machine. An output side of the second hydraulic machine is connected to an input side of the first hydraulic machine. A hydraulic consumer is hydraulically coupled to an output side of the first hydraulic machine via a supply line and is powered by the first hydraulic machine. A return line hydraulically couples the hydraulic consumer to an input side of the first hydraulic machine. The second hydraulic machine provides a flow of hydraulic fluid to the input side of the first hydraulic machine if a requested flow from the first hydraulic machine exceeds a flow of the return line and recuperates energy if the requested flow from the first hydraulic machine is lower than the flow of the return line.

The disclosure relates to a hydraulic control block for controlling a pressure medium supply of a hydraulic cylinder of a hydraulic spindle. The hydraulic control block includes a generic hydraulic switching structure electively configurable in each of a plurality of specific hydraulic switching structures, each of the plurality of specific hydraulic switching structures having a respective hydraulic cylinder with a number of piston areas which differs from a number of piston areas in the respective hydraulic cylinders of each of the other of the plurality of specific hydraulic switching structures.

A fluid system includes a variable-speed and/or a variable-torque pump to pump a fluid, at least one proportional control valve assembly, an actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump and a position of the at least one proportional control valve assembly. The pump includes at least one fluid driver that provides fluid to the actuator, which can be, e.g., a fluid-actuated cylinder, a fluid-driven motor or another type of fluid-driven actuator that controls a load. Each fluid driver includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump.

An electro-hydraulic actuator system includes a fixed-displacement hydraulic pump and a variable speed electric motor configured in combination to constitute an individual electro-hydraulic unit that is coupled to an actuator, and a bypass valve in parallel to the actuator. The system is configured to enable the actuator to be operated at actuation speeds that are higher than a maximum actuation capability of the pump at the maximum flow capability thereof, and at actuation speeds that are lower than a minimum actuation capability of the pump at the minimum flow capability thereof. The actuation velocity of the actuator may be controlled by controlling the speed of the electro-hydraulic unit and a size of an opening of the bypass valve.

To provide a construction machine that has a hydraulic system mounted thereon in which a closed-circuit pump, and an open-circuit pump and a proportional valve are arranged as a pair, and that makes it possible to use an unused open-circuit pump or proportional valve to accelerate the speed of a single rod hydraulic cylinder when the single rod hydraulic cylinder and a hydraulic motor are driven simultaneously. A controller (51) controls a cap-side selector valve (46) and a rod-side selector valve (47) such that a particular open-circuit pump (15) not connected to a single rod hydraulic cylinder (3) is connected to the single rod hydraulic cylinder, and controls an opening area of a particular proportional valve (49) provided on a flow line that connects a delivery port of the particular open-circuit pump to a tank, when the single rod hydraulic cylinder and a hydraulic motor (7) are driven simultaneously.

An electrohydrostatic actuator system comprising: a volume- and/or speed-variable hydraulic machine which is driven by an electric motor, for providing a volumetric flow of a hydraulic fluid; a differential cylinder with a piston side and a ring side; and at least one pretensioning source. The actuator system has a closed hydraulic circuit, wherein, during operation, the hydraulic fluid in the hydraulic circuit is pressurized by means of the hydraulic machine and/or the pretensioning source. Furthermore, according to the invention, the differential cylinder provides a power motion operating mode and a rapid motion operating mode. In order to balance a volume of the hydraulic fluid in the closed hydraulic circuit, according to the invention an expansion reservoir is connected to the piston side of the differential cylinder via a valve.

A cylinder actuator includes a body assembly and a piston assembly. The body assembly includes a first cylinder nested concentrically within a second cylinder. The piston assembly slides linearly within the first and second cylinders. The piston assembly includes a first piston assembly end and a second piston assembly end. The first piston assembly end includes first and second pistons. The first piston moves within the first cylinder. The second piston moves within the second cylinder. The piston assembly includes first and second piston rods. The first piston rod extends from the first piston through a first end of the first cylinder. The second piston rod extends from the second piston through a first end of the second cylinder. The piston rods are joined at the second end of the piston rod assembly located outside of the first and second cylinders.

A fluid system includes a variable-speed and/or a variable-torque pump to pump a fluid, at least one proportional control valve assembly, an actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump and a position of the at least one proportional control valve assembly. The pump includes at least one fluid driver that provides fluid to the actuator, which can be, e.g., a fluid-actuated cylinder, a fluid-driven motor or another type of fluid-driven actuator that controls a load. Each fluid driver includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump.