A pressure vessel arrangement includes a pressure vessel and an optical sensor arrangement. The pressure vessel includes: a cylinder construction having a cylinder wall extending from a cylinder wall first end to a cylinder wall second end, and having an internal surface forming an interior region; a first end cap closing the cylinder wall first end and having an optical window located therein to permit passage of light therethough and into the interior region; a second end cap closing the cylinder wall second end; and a piston constructed to slide within the cylinder construction interior region along a direction between the cylinder all first end and the cylinder wall second end and along the cylinder construction internal surface to separate the interior region into a first end interior region and a second end interior region. The pressure vessel is constructed to withstand a fatigue test of one million cycles at 5,000 psi without failure. The optical sensor arrangement is located outside of the optical window and includes an emitter for emitting light through the optical window and into the interior region and receiving for receiving light reflected from the piston. Also included is a method for providing a piston position feedback in a pressure vessel.

A self-contained pressure compensation system and a control method thereof are provided, wherein the self-contained pressure compensation system comprises an oil supply device, a pressure compensation device, a power unit associated with the pressure compensation device, and a switch control device, the pressure compensation device supplies oil to the power unit and detects a change in a chamber pressure of itself in real time, the switch control device triggers the oil supply device to supply oil to the pressure compensation device if the chamber pressure is less than a predetermined first threshold and triggers the oil supply device to stop supplying oil to the pressure compensation device if the chamber pressure is greater than a predetermined second threshold. The invention can detect a chamber pressure of the pressure compensation device in real-time and can achieve automatic oil refilling, and can provide pressure compensation for the power unit effectively.

A system for determining the location of a movable element within a container is provided in which a linear variable differential transformer (LVDT) is formed with the container and the movable element therein. The LVDT includes a coil assembly including a primary or excitation winding, a secondary or output winding, and a movable element or core that is magnetically permeable. Measurement of an output signals allows for precise determination of the movable element location relative to the container. The system can be utilized to determine fluid volumes in accumulators used for controlling subsea equipment by monitoring the location of a movable element, e.g., a piston, within a hydraulic fluid accumulator.

An ultrasonic displacement measurement system for hydraulic accumulators (3) has a movable separating element (5) separating two media chambers (9, 11) from each other in a media-tight manner within a housing (7). One media chamber (9) holds a compressible fluid or an incompressible fluid. The other media chamber (11) holds a compressible working gas. The particular position of the movable separating element (5) within the housing (7) can be detected by an ultrasonic sensor (13) that performs the position detection of the separating element (5) on the side of the media chamber (11) having the compressible fluid. A method for ultrasonic displacement measurement uses that system.

A hydropneumatic piston accumulator, with an accumulator housing (1), which comprises a cylindrical tube (3) defining a longitudinal axis (11), wherein the cylindrical tube (3) is closed at both ends by a housing cover (5, 7) at each end and wherein a piston (9) is longitudinally movable in the cylindrical tube (3) and, in the housing, separates a working chamber (13) for a compressible medium, such as a working gas, from a working chamber for an incompressible medium, such as hydraulic fluid, and with a displacement measuring device for determining the position of the piston (9) in the housing in a contact-free manner. The invention is characterised in that the displacement measuring device comprises a non-magnetic measuring tube (29), which extends along the longitudinal axis (11) from one housing cover (5) to the other housing cover (7) through a passage (31) formed in the piston (9) and is sealed against the interior of the housing (1), and in that in the tube (29) a position sensor (57) is movably guided and follows the piston movements in the measuring tube (29) using a magnetic force acting between the piston sensor (57) and the piston (9), and in that a transmitter/receiver (65) for the displacement measuring device is positioned on one of the housing covers (5, 7) and emits a measurement beam through the open end (25, 26) of the measuring tube (29) to the position sensor (57) and receives reflected radiation from same.

A laser piston position sensor for determining the position of a piston within an accumulator, the laser piston position sensor configured to attach to an end of the accumulator, and the accumulator having an aperture in the end thereof exposing the piston within the accumulator to the laser piston position sensor. The laser piston position sensor including a sensor housing enclosing a cavity containing a low pressure gas, and defining an opening from the cavity toward the accumulator, a laser sensor positioned within the cavity for emitting a laser toward the piston of the accumulator via the opening in the sensor housing and the aperture in the accumulator, and a transparent lens positioned between the laser sensor and the accumulator to allow passage of the laser from the laser sensor to the piston, and to separate gases in the accumulator from gases in the cavity of the sensor housing.

A fluidic control system (1) for controlling a vehicle, which includes a controller (2) and a closed fluidic circuit. The circuit includes a pump (3) for pressurizing fluid in the circuit, valve means (40, 50, 60), an actuator (4, 5, 6) and a precharge accumulator (7). The valve means (40, 50, 60) is fluidly connected to the inlet and outlet of the pump (3) and the actuator (4, 6) is fluidly connected to the valve means (40, 50, 60) for selectively receiving pressurized fluid therefrom. The precharge accumulator (7) includes a movable member (73, FIG. 2) that describes a variable volume (71) fluidly connected to the circuit between the valve means (40, 50, 60) and the inlet of the pump (3). The system (1) also includes a sensor (70) for determining the position of the movable member (73) for estimating the quantity of fluid and/or detecting an abnormal pressure variation within the circuit.

A method includes detecting at least one position measurement of a separator piston of a pitch trim actuator. The method includes detecting at least one pressure measurement of an oil. The method includes detecting at least one temperature measurement of the oil. The method includes storing at least one position value based on the at least one position measurement of the separator piston, at least one pressure value based on the at least one pressure measurement of the oil and at least one temperature value based on the at least one temperature measurement of the oil. The method includes determining whether the pitch trim actuator requires servicing based on the at least one position value, the at least one pressure value, and the at least one temperature value.

A device for maintaining a hydraulic supply of a utility vehicle includes a hydraulic pump, which is adjustable in terms of its delivery volume via a pressure control inlet, for feeding hydraulic fluid to a hydraulic circuit, a pressure accumulator that can be charged from the hydraulic circuit via a check valve, a pressure connection between the hydraulic circuit and the pressure control inlet of the hydraulic pump being producible via a sensor line by means of a charging valve, and a supply connection between the pressure accumulator and the hydraulic circuit being producible by means of a discharging valve, by virtue of the check valve being bypassed.

A rolling assembly, including at least one roll pair with two cooperating rolls and a safety device. The safety device includes a hydraulic accumulator and a measuring device. The hydraulic accumulator includes an accumulator with a first and second accumulator chamber. A hydraulic fluid is disposed within the first accumulator chamber. A compressible gas is disposed within the second accumulator chamber. The hydraulic accumulator includes a moveably arranged separating member separating the first accumulator chamber from the second accumulator chamber. The roll pair has a working position and a safety position. A radial distance between the rolls is larger in the safety position than in the working position. The hydraulic accumulator is configured to move the roll pair from the working position to the safety position. The measuring device is configured to continuously detect a position of the separating member within the hydraulic accumulator.