A barrier system for a dual mechanical seal, the system comprising means for controlling barrier fluid pressure relative to product pressure. The pressure control means comprises means for monitoring the volume of barrier fluid in the system and for supplying additional fluid to the system to maintain the volume within a desired range. The system further comprises means for maintaining the barrier fluid pressure at a pre-determined pressure above product pressure.

A barrier system for a dual mechanical seal, the system comprising means for controlling barrier fluid pressure relative to product pressure. The pressure control means comprises means for monitoring the volume of barrier fluid in the system and for supplying additional fluid to the system to maintain the volume within a desired range. The system further comprises means for maintaining the barrier fluid pressure at a pre-determined pressure above product pressure.

This method is used to manage a pressure accumulator (1) as a component of an energy storage system, consisting of a work machine (4), a collecting tank (7), a displacement apparatus (6) and a pressure accumulator (1) for storing a pressurised gaseous medium. The pressure accumulator (1) is partially filled with a liquid medium so as to be able to control the gas storage volume therewith. Feeding compressed gas (3) into the pressure accumulator (1) involves removing liquid (2). Removing compressed gas (3) from the pressure accumulator (1) involves feeding in liquid (2) so that the storage pressure is kept under control as necessary, in particular is kept constant. To this end, one pressurised unit of gas (3) is introduced into the pressure accumulator (1) with the removal of one unit of liquid (2) from the pressure accumulator (1) by means of the displacement apparatus (6) and vice versa. The present method and the present arrangement make it possible to fill the pressure accumulator (1) completely with and to empty the pressured storage unit (1) completely of pressurised gas (3) at a controllable pressure, which leads to improved utilisation of the pressure accumulator volume and thus increases the energy density of the energy storage system. The method further makes it possible to operate the energy storage system at a constant operating point, thus increasing the efficiency of the individual components and of the entire system, and minimising the compression and expansion processes in the pressure accumulator (1).

This method is used to manage a pressure accumulator (1) as a component of an energy storage system, consisting of a work machine (4), a collecting tank (7), a displacement apparatus (6) and a pressure accumulator (1) for storing a pressurised gaseous medium. The pressure accumulator (1) is partially filled with a liquid medium so as to be able to control the gas storage volume therewith. Feeding compressed gas (3) into the pressure accumulator (1) involves removing liquid (2). Removing compressed gas (3) from the pressure accumulator (1) involves feeding in liquid (2) so that the storage pressure is kept under control as necessary, in particular is kept constant. To this end, one pressurised unit of gas (3) is introduced into the pressure accumulator (1) with the removal of one unit of liquid (2) from the pressure accumulator (1) by means of the displacement apparatus (6) and vice versa. The present method and the present arrangement make it possible to fill the pressure accumulator (1) completely with and to empty the pressured storage unit (1) completely of pressurised gas (3) at a controllable pressure, which leads to improved utilisation of the pressure accumulator volume and thus increases the energy density of the energy storage system. The method further makes it possible to operate the energy storage system at a constant operating point, thus increasing the efficiency of the individual components and of the entire system, and minimising the compression and expansion processes in the pressure accumulator (1).

A pressure accumulator having an accumulator housing (10) in which a movable separating element (16) separates a gas room (12) filled with a working gas from a fluid room (14) in a fluid-sealed manner, wherein a monitoring device (46) is provided, which, in the event of a fault impairing the sealing effect of the separating element (16), provides an optically discernible indication and which has an inspection window (54), through which an indicator can be observed, which is connected to the gas room (12) and whose optical properties change discernibly when wetted with the fluid, is characterized in that the indicator changing its optical properties is accommodated in a capsule (48), the capsule wall (50) of which is permeable to the passage of the fluid and which is arranged between the inspection window (54) and the separating element (16) in the accumulator housing (10).

A controller (45) is provided with an elapse time measuring section (47A) that measures an elapse time (tx) elapsed since an initial use of an accumulator (29) based upon a reset signal from a reset switch (44), a number-of-operations measuring section (47B) that measures a number of operations of the accumulator (29), that is, a number (N) of boom lowering operations after a reset, based upon a detection signal from an accumulator side pressure sensor (39), a gas permeation amount estimating section (47C) that estimates an estimation gas permeation amount (Qloss) of the accumulator (29), a sealed gas pressure estimating section (47D) that finds an estimation sealed gas pressure (Pgs) of a gas chamber (29B) of the accumulator (29), and an accumulator degradation determining section (47E) that determines a degradation condition of the accumulator (29) and outputs the determination result.

A controller (45) is provided with an elapse time measuring section (47A) that measures an elapse time (tx) elapsed since an initial use of an accumulator (29) based upon a reset signal from a reset switch (44), a number-of-operations measuring section (47B) that measures a number of operations of the accumulator (29), that is, a number (N) of boom lowering operations after a reset, based upon a detection signal from an accumulator side pressure sensor (39), a gas permeation amount estimating section (47C) that estimates an estimation gas permeation amount (Qloss) of the accumulator (29), a sealed gas pressure estimating section (47D) that finds an estimation sealed gas pressure (Pgs) of a gas chamber (29B) of the accumulator (29), and an accumulator degradation determining section (47E) that determines a degradation condition of the accumulator (29) and outputs the determination result.

Disclosed is a landing gear bogie pitch trimmer, comprising a hydraulic actuator for adjusting a pitch of a landing gear bogie, in use, a fluid interface for receiving, from an aircraft hydraulic system external to the landing gear bogie pitch trimmer, hydraulic fluid for use in actuating the hydraulic actuator, and a flow control valve for controlling flow of the hydraulic fluid through the fluid interface in use. Also disclosed is a system, a landing gear controller, a method, and an aircraft.

Disclosed is a landing gear bogie pitch trimmer, comprising a hydraulic actuator for adjusting a pitch of a landing gear bogie, in use, a fluid interface for receiving, from an aircraft hydraulic system external to the landing gear bogie pitch trimmer, hydraulic fluid for use in actuating the hydraulic actuator, and a flow control valve for controlling flow of the hydraulic fluid through the fluid interface in use. Also disclosed is a system, a landing gear controller, a method, and an aircraft.

A landing gear system for an aircraft includes a retractable landing gear assembly, a hydraulic actuator for actuating movement part, for example a bogie of the landing gear assembly, and an accumulator associated with the actuator. The accumulator comprises a volume of pressurised gas separated from hydraulic fluid by a separator piston. Travel of the separator piston beyond a certain position is indicative of a fault. The accumulator includes a snubbing device that acts to slow movement of the separator piston beyond that position. A monitoring system measures the time taken for the movement of the landing gear part effected by the hydraulic actuator. If the measured time is longer than a threshold time, that is indicative of a possible fault in the accumulator, that might, without the snubbing, remain undetected and/or hidden from view.