Systems and methods for electrohydraulic valve calibration are provided. In one aspect, a calibration circuit includes a calibration conduit isolated from a supply conduit, a first calibration orifice configured to provide fluid communication between the calibration conduit and a fluid source, and a second calibration orifice arranged in series with the first calibration orifice. The second calibration orifice is on a spool of a electrohydraulic control valve and is configured to selectively provide fluid communication between the calibration conduit and a low pressure source. The calibration circuit further includes a pressure sensor configured to measure a pressure in the calibration conduit between the first calibration orifice and the second calibration orifice. The second calibration orifice is isolated from the at least one workport of the electrohydraulic control valve.

A fluid system for a gas turbine engine includes a first supply line, a hydraulic accessory actuable by a fluid, and a second supply line fluidly connected the hydraulic accessory and to the first supply line upstream of the component. An accumulator is fluidly connected to the second supply line upstream of the hydraulic accessory. The accumulator is operable to fill a reservoir with the fluid from the first supply line via the second supply line, and to deliver the fluid to the hydraulic accessory via the second supply line. The first supply line may be a fuel or lubricant main supply line of the engine. A method of actuating a hydraulic accessory is also disclosed.

Provided is a hydraulic fluid energy regeneration device for a work machine, including: a regeneration hydraulic motor driven by discharged return hydraulic fluid; a first hydraulic pump mechanically connected to the regeneration hydraulic motor; a second hydraulic pump that delivers an hydraulic fluid for driving a first hydraulic actuator and/or a second hydraulic actuator; a junction line that allows the hydraulic fluid delivered by the second hydraulic pump to be joined; a second regulator that regulates the delivery flow rate of the second hydraulic pump; and a first regulator that regulates the flow rate of the hydraulic fluid coming from the first hydraulic pump and flowing through the junction line. A control unit includes: a first computing part that calculates a demanded pump flow rate in accordance with the input target replacement command for the second hydraulic pump, the first computing part further outputting a control command to the first regulator in such a manner that the flow rate of the hydraulic fluid coming from the first hydraulic pump and flowing through the junction line equals to or lower than the demanded pump flow rate; and a second computing part that subtracts from the demanded pump flow rate the flow rate of the hydraulic fluid coming from the first hydraulic pump to obtain a target pump flow rate, the second computing part further outputting a control command to the second regulator in such a manner that the calculated target pump flow rate is attained.

The present invention is a hydraulically operated splitting device with a piston cylinder unit comprising an extending chamber and a retracting chamber in which a piston is supported, displaceable in an extending direction and a retracting direction, allowing the extending chamber and the retracting chamber to be impinged with pressurized hydraulic medium for moving the piston at a displacement speed, a cylinder housing at which a plurality of pressure pads is supported, displaceable perpendicular to the extending direction and the retracting direction, a wedged lance connected to a piston rod of the piston and mobile with said piston, which engages wedge-shaped pressure areas of the pressure pads complementary to the wedged lance, and moves the pressure pads perpendicular to the extending direction and the retracting direction, a lubrication unit by which lubricant can be inserted from a lubricant reservoir to an area between the wedged lance and the pressure pads, with the splitting device comprising a protective unit by which the displacement speed can be reduced depending on the fill level of the lubricant in the lubricant reservoir.

A system for delivering fluid in a machine is provided. The system includes a pump, a first valve disposed downstream of the pump, a check valve disposed downstream of the first valve, at least one accumulator disposed downstream of the check valve, and an auxiliary system disposed upstream of the check valve. The system further includes a control unit configured to receive a signal indicative of a fluid demand from the auxiliary system. The control unit is also configured to selectively control the first valve in a first position to limit flow of the fluid from the pump to the auxiliary system, and in a second position to allow flow of the fluid from the pump to the auxiliary system based, at least in part, on the received signal. The check valve limits flow of a fluid from the at least one accumulator to the auxiliary system.

The invention relates to a pressure-limiting device designed to be installed in a system comprising a first line (11) and a second line (12) that can comprise pressurised oil, as well as comprising a discharge and/or booster line (10). The device also comprises a pressure selector (130, 150) in the form of a cage defining two seats (132, 134) and two pressure relief valves (160, 180). The limiting device is characterised in that it further comprises at least one means (170, 172; 190, 192) for regulating a pressure relief valve, disposed on the outside of an axial end of the pressure selector (150), in the form of a cage that allows the loading of the associated pressure relief valve to be regulated.

A steam turbine valve drive apparatus in an embodiment includes a piston, a cylinder, a bidirectional pump, a servo motor, and a quick closing mechanism. The cylinder houses the piston in an inner space thereof, the inner space being partitioned by the piston into a first hydraulic chamber and a second hydraulic chamber. The quick closing mechanism executes a quick closing operation of closing the steam valve unit more quickly than the closing operation. Here, the quick closing mechanism executes the quick closing operation by feeding the working oil accumulated in an accumulator to the second hydraulic chamber and draining the working oil from the first hydraulic chamber.

A hydraulic pressure supply system of an automatic transmission for a vehicle is provided. The system divides a hydraulic pressure generated from first and second pump chambers of a hydraulic pump into a high-pressure and low-pressure part. The system includes first and second input lines that guide oil of an oil pan to the first and second pump chambers. First and second discharge lines discharge the hydraulic pressure generated from the first and second pump chambers. A high-pressure switch valve selectively supplies or recycles the hydraulic pressure supplied from the first discharge line to the high-pressure hydraulic path into the high-pressure part. A pressure accumulator is disposed on a high-pressure hydraulic path between the high-pressure switch valve and the high-pressure part and a low-pressure switch valve selectively supplies or recycles the hydraulic pressure supplied from the second discharge line to the low pressure hydraulic path into the low-pressure part.

Provided is a hydraulic fluid energy regeneration device for a work machine, including: a regeneration hydraulic motor driven by discharged return hydraulic fluid; a first hydraulic pump mechanically connected to the regeneration hydraulic motor; a second hydraulic pump that delivers an hydraulic fluid for driving a first hydraulic actuator and/or a second hydraulic actuator; a junction line that allows the hydraulic fluid delivered by the second hydraulic pump to be joined; a second regulator that regulates the delivery flow rate of the second hydraulic pump; and a first regulator that regulates the flow rate of the hydraulic fluid coming from the first hydraulic pump and flowing through the junction line. A control unit includes: a first computing part that calculates a demanded pump flow rate in accordance with the input target replacement command for the second hydraulic pump, the first computing part further outputting a control command to the first regulator in such a manner that the flow rate of the hydraulic fluid coming from the first hydraulic pump and flowing through the junction line equals to or lower than the demanded pump flow rate; and a second computing part that subtracts from the demanded pump flow rate the flow rate of the hydraulic fluid coming from the first hydraulic pump to obtain a target pump flow rate, the second computing part further outputting a control command to the second regulator in such a manner that the calculated target pump flow rate is attained.

An open and closed circuit parallel drive system and a control method based on a four-chamber hydraulic cylinder are provided. The system includes: a closed pump-controlled drive unit and an open valve-controlled drive unit. The four-chamber hydraulic cylinder is driven by the open valve-controlled drive unit with a large load power, and the operating velocity and displacement of the four-chamber hydraulic cylinder are controlled by the closed pump-controlled drive unit with a small load power, thereby improving the linearity and stability of the four-chamber hydraulic cylinder control and reducing the system installed power and throttling loss.