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 center biased actuator having an outer cylinder, a slave cylinder linearly transposed within the outer cylinder, a rod assembly with a piston linearly transposed within the slave cylinder and a rod extending from the outer cylinder, one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder, one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder, and a gas chamber comprising a sealed expandable chamber containing gas. The expandable chamber is arranged to act on hydraulic fluid within the center biased actuator to bias the center biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition.

A pressure accumulator includes an accumulator housing having first and second ports for receiving first and second pressure mediums, respectively, a movable separating element subdividing an interior of the accumulator housing into at least first and second working spaces, the first working space accommodating the first pressure medium and the second working space accommodating the second pressure medium, wherein the first port is in fluid communication with the first working space and the second port in fluid communication with the second working space. At least one sensor is operatively coupled to the first working space for measuring at least one characteristic of the first working space, and a gas generator is operative to generate a gas from ambient air, the gas generator including an outlet for outputting the generated gas, the outlet in fluid communication with the first port. A controller is operatively coupled to the at least one sensor and the gas generator, the controller configured to calculate an amount of gas in the first working space based on the at least one characteristic and upon the calculated amount of gas in the first working space being below a first threshold level, generate a command to introduce gas from the gas generator into the first working space.

A hydraulic accumulator, in particular in the form of a piston accumulator, comprising an accumulator housing (10) and a separating element (20) arranged therein, in particular in the form of a piston, which separates a fluid side (22) from a gas side (24), is characterized in that at least the gas side (24) can be inspected, at least in part, by means of at least one sight glass (34, 36) which is fixed in the accumulator housing (10).

The present disclosure provides a gas-liquid coupling type fluid pulsation attenuator, which comprises: substrate, which is hollow and with an opening at one end; bladder, which is located at the hollow part of the substrate, and a first chamber is formed between the bladder and the inner wall of the substrate; and lining, which is located inside the bladder. The gas-liquid coupling type fluid pulsation attenuator of the present disclosure makes the fluid in the main pipe enter the first chamber through the opening of the substrate, and the bladder is filled with gas. Therefore, under the action of the pressure difference between the fluid pressure in the first chamber and the air pressure in the bladder, the bladder deforms, so as to absorb the flow pulsation through the expansion and contraction of the bladder, to make the oil flow in the hydraulic energy system more stable.

Fluid equipment includes a container configured for having first and second fluids therein, a first fluid outlet/inlet path provided for outflow and inflow of the first fluid, a second fluid outlet/inlet path for outflow and inflow of the second fluid, and a member configured for moving in the container in response to pressure of the first fluid, the fluid equipment transmitting energy from the first to the second fluid. A first bellows is configured such that one end is closed in a sealed state by the moving member, the other end is fixed to an inner surface part of the container in a sealed state, and the inside of the first bellows communicates with the first fluid outlet/outlet path.

An exemplary method generally includes charging hydraulic fluid into or out of a cavity of an accumulator at a controlled flowrate, detecting movement of a machine component from a first position toward a second position, determining an idle time spanning from a start of the charging to detection of the movement of the machine component, and determining a pre-charge of the accumulator based upon the idle time and a flowrate value of the controlled flowrate.

An accumulator is provided with a communication passage which allows communication between a space inside a gas filling opening and a gas filled chamber in a state where a diaphragm contacts an opening peripheral edge of the gas filling opening and which is formed by, for example, uneven shapes provided in either or both of the diaphragm or/and the opening peripheral edge of the gas filling opening.

A center biased actuator having an outer cylinder, a slave cylinder linearly transposed within the outer cylinder, a rod assembly with a piston linearly transposed within the slave cylinder and a rod extending from the outer cylinder, one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder, one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder, and a gas chamber comprising a sealed expandable chamber containing gas. The expandable chamber is arranged to act on hydraulic fluid within the center biased actuator to bias the center biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition.

A hydraulic propulsion system converts heat or thermal energy into hydraulic energy, and such hydraulic energy into mechanical work. The hydraulic propulsion system includes a thermal unit, a hydraulic cylinder with pistons and springs mounted therein, one or more hydraulic motors, one or more hydraulic accumulators, and one or more electrical energy generators, as well as a plurality of flow control valves to control the flow of hydraulic fluid between the various components. The hydraulic propulsion system may be enhanced by an energy transmission unit including a wave generator.