The present disclosure relates to a miniature pressure compensating device (10), for balancing pressure fluctuations in a hydraulic system, comprising at least one shell (12), at least one hollow hydraulic cylinder (16), at least one reciprocating piston (26) and at least one non-return valve (NRV) (28). The hydraulic cylinder (16) comprises at least one dual charging valve port (22) for facilitating charging of both said compressible and incompressible fluid and at least one built-in two-tier sealing mechanism (24) comprising at least one metal-to-metal seal (24a) and at least one secondary seal (24b) to achieve effective isolation of the incompressible and compressible fluids. The present miniature pressure compensating device (10) has a volume below 13 cc.

An example valve assembly includes a housing having an accumulator fluid passage configured to be fluidly coupled to an accumulator, a supply fluid cavity configured to be fluidly coupled to a source of fluid, a reservoir fluid cavity configured to be fluidly coupled to a reservoir of fluid, a head fluid cavity configured to be fluidly coupled to a head-side chamber of a hydraulic actuator, and a rod fluid cavity configured to be fluidly coupled to a rod-side chamber of the hydraulic actuator; a main spool that is axially-movable within the housing; and a balancing spool that is axially-movable within the housing based on an axial position of the main spool.

An accumulator a housing having a sealing face and a fluid inlet/outlet passage; a bellows fixed at least one end to the housing such that an inner space of the housing such that an inner space of the housing is hermetically partitioned by the bellows into an interior and an exterior of the bellows, the bellows including a bellows main body capable of expanding and contracting and a bellows cap including an annular seal holder, and a sealing member formed by covering a disc-shaped substrate with an elastic body that is opposed to and capable of being closely attached to the sealing face of the housing. At least a center part of a surface of the substrate opposing the sealing face is a curved surface having an arc shape in a sectional view.

Some of the present systems include a hydraulic power storage system having an accumulator configured to supply pressurized hydraulic fluid to a hydraulically actuated device to actuate the hydraulically actuated device and a drain in fluid communication with the accumulator and including a valve that is actuatable to drain hydraulic fluid from the hydraulic power storage system such that an internal pressure of the accumulator is reduced and a flow restrictor configured to reduce a flow rate of hydraulic fluid through the valve, a hydraulic pump configured to pressurize the accumulator, a pressure sensor configured to capture data indicative of the internal pressure of the accumulator, and a processor configured to actuate the hydraulic pump to increase the internal pressure of the accumulator if the internal pressure of the accumulator, as indicated in data captured by the pressure sensor, falls below a threshold pressure.

This disclosure includes systems and methods for actuating hydraulically-actuated devices.

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.

A system and method for providing redundancy in hydraulic circuits in multi-cycle hydraulic tools is described. The problems of dysfunctional hydraulic tool due to the failure of electromechanical actuators are addressed by providing redundant actuators and associated circuitry design.

An apparatus includes a bootstrap accumulator having multiple fluid expansion volumes each configured to receive fluid. The bootstrap accumulator also includes a piston assembly configured to move within the fluid expansion volumes based on pressures within the fluid expansion volumes. The piston assembly includes (i) a fluid pathway that couples the fluid expansion volumes and (ii) a bypass valve configured to selectively open or block the fluid pathway. The piston assembly could also include multiple pistons and a connecting rod coupling the pistons. The fluid pathway could include a narrower path through a first portion of the connecting rod and a wider path through a second portion of the connecting rod. The bypass valve could include a ball and a spring configured to push the ball to block the narrower path through the first portion of the connecting rod.

An accumulator includes a housing having a sealing face and a fluid inlet/outlet passage, a bellows fixed at least one end to the housing such that an inner space of the housing is hermetically partitioned by the bellows into an interior and an exterior of the bellows, the bellows including a bellows main body capable of expanding and contracting and a bellows cap including an annular seal holder, and a sealing member formed by covering a disc-shaped substrate with an elastic body that is opposed to and capable of being closely attached to the sealing face of the housing, the sealing member is held by a holding portion of the annular seal holder on an inner diameter side of the annular seal holder, the fluid inlet/outlet passage of the housing being closed upon a close attachment of the elastic body to the sealing face.

A bootstrap hydraulic reservoir includes a bootstrap chamber to hold hydraulic fluid, a piston chamber fluidly connected to a pressure line of the hydraulic fluid system, a piston having a bootstrap end portion held within the bootstrap chamber and a pressure end portion held within the piston chamber, and a hydraulic accumulator fluidly connected to the pressure line of the hydraulic fluid system. The hydraulic accumulator accumulates pressurized hydraulic fluid from the pressure line. The bootstrap hydraulic reservoir also includes a valve fluidly connected to the pressure line of the hydraulic fluid system between the hydraulic accumulator and an outlet of a pump of the hydraulic fluid system. The valve includes an actuator selectively moves the valve to an open position when the pressure line of the hydraulic fluid system is de-pressurized.