A relief valve includes: a housing; a plunger movable to each of a closed position and an open position; a differential pressure chamber; a spring member; a piston; and a damping chamber. The plunger includes a first damping passage penetrating the plunger and bringing an area outside the plunger and a through passage into communication. The piston includes a second damping passage penetrating the piston and bringing an area inside the piston and the damping chamber into communication. A communication space connected to each of the first damping passage and the second damping passage is formed between the plunger and the piston.

The present invention relates to a check valve unit (1, 100, 200, 300, 400) having a shaft bearing body (10, 110, 210, 310, 410) with an at least substantially cylindrical mounting portion (11) extending along an axial direction (A) and an axially extending valve shaft (20, 120) mounted therein. The latter is displaceable along the axial direction (A). The check valve unit (1, 100, 200, 300, 400) further includes a valve head (25, 125) with a sealing surface (33, 133), wherein the valve head (25, 125) is disposed on a distal end (21) of the valve shaft (20, 120) in the axial direction (A), the distal end (21) facing away from the mounting portion (11). Further, a damping reservoir (50) is provided inside the shaft bearing body (10, 110, 210, 310, 410). A volume of the damping reservoir (50) is changed by axial movement of the valve shaft (20, 120). In order to obtain a well-defined times for opening and closing under given conditions and to make the check valve unit (1, 100, 200, 300, 400) less prone to making noise, at least two channels (46a, 46b) are provided in parallel, each of them constituting a fluid connection between the damping reservoir (50) and an outside (70). The damping reservoir (50) is, apart from the channels (46a, 46b), at least substantially enclosed. Each channel (46a, 46b) has a length being at least ten times a hydraulic diameter of the respective channel (46a, 46b).

A valve closure device for a check valve can include a first valve member configured to rotate from an open position to a closed position; a second valve member configured to rotate from an open position of the second valve member to a closed position of the second valve member; and a hydraulic dampener coupled to each of the first valve member and the second valve member in each of the open position and the closed position of each of the first valve member and the second valve member, the hydraulic dampener configured to resist rotation of the first valve member towards the closed position of the first valve member and the second valve member towards the closed position of the second valve member.

Fluid damped check valves are described herein. A representative check valve includes a piston assembly movably positioned within a housing. The housing can include a flow chamber, a damping chamber containing a damping fluid, and a leak chamber fluidly coupled between the flow chamber and the damping chamber. The piston assembly can include a poppet positioned in the flow chamber, and a flange positioned in the damping chamber. In operation, the piston assembly is movable between (i) a closed position in which the poppet sealingly engages the housing to at least inhibit fluid flow through the flow chamber and (ii) an open position in which the poppet disengages from the housing and permits fluid flow through the flow chamber. When the piston assembly moves between the open and closed positions, the flange moves through the damping fluid in the damping chamber to slow the movement of the poppet.

A fuel nozzle metering valve that includes a spool having an inlet port and an outlet flow port, and a retainer assembled to one end of the spool. A valve liner houses a portion of the spool. The spool is configured to move back and forth within the valve liner. The metering valve is biased in a closed position in which the outlet flow port is disposed entirely within the valve liner. The valve is opened when the spool slides within the valve liner such that some portion of the outlet flow port extends beyond an end of the valve liner. The retainer has a stepped portion configured to abut an end of the retainer at a fuel flow pressure below the expected maximum fuel flow pressure to be used in the fuel nozzle metering valve.

An injection valve including a housing, a fluid channel in the housing, and a check valve disposed in the housing and responsive to fluid pressure in the channel to move the check valve in a direction opposite the direction of fluid flow through the channel. A method for injecting fluid into a volume including pressurizing a fluid to be injected, conveying the pressurized fluid to a space about a check valve between a check valve nose and a stem seal; and moving the check valve in a direction opposite a direction of injection fluid flow. A borehole system including a borehole in a subsurface formation, a string disposed within the borehole, and an injection valve disposed within or as a part of the string.

A damping valve having a damping valve body with at least one flow channel for damping medium. A valve rod is arranged in the flow channel. The valve rod cooperates with a valve disk and a valve seat surface. The valve rod carries a further valve disk that cooperates with a second valve seat surface. The first valve disk together with the first valve seat surface forms a first partial valve having a first permanently open pilot orifice cross section, and the second valve disk together with the second valve seat surface forms a second partial valve having a second pilot orifice cross section, and a shuttle valve is formed which opens one partial valve and closes the other partial valve depending on the flow direction.

Seat valve, with a valve body having a plurality of inlet channels, with a plurality of closing elements arranged movably in a longitudinal direction L, each inlet channel being assigned a closing element for opening and closing the inlet channel, with a closing spring assigned to each closing element. The closing spring applies a prestressing force to the respective closing element to close the inlet channel. Each closing element assigned a braking device which is arranged separately from the closing element and which gradually brakes an opening movement of the closing element when the inlet channel is opened, independently of the closing spring. The braking device having a stop body with a stop surface against which the closing element can be brought to bear after an opening movement when the inlet channel is opened, the stop body being arranged movably and/or yieldingly in the opening direction of the closing element.

The invention relates to a compressor unit (200) for a refrigeration system using a refrigerant. The compressor (200) unit includes a centrifugal compressor (201) for compressing the refrigerant, wherein the compressor (201) has a discharge outlet (204) for discharging the compressed refrigerant, and a check valve (1; 100; 301a). An inlet (83) of the check valve (1; 100; 301a) is in fluid connection with the discharge outlet (204) of the compressor (201). In order to provide a more reliable and more quite compressor unit (200), the check valve (1; 100; 301a) is a nozzle check valve including a damping mechanism (41, 50; 50, 141), wherein a closing parameter of the check valve (1; 100; 301a) is between 50 s/m.sup.2 and 2000 s/m.sup.2, wherein the closing parameter is a closing time of the check valve (1; 100; 301a) divided by a port area of the check valve (1; 100; 301a).

Seat valve, with a valve body having a plurality of inlet channels, with a plurality of closing elements arranged movably in a longitudinal direction L, each inlet channel being assigned a closing element for opening and closing the inlet channel, with a closing spring assigned to each closing element. The closing spring applies a prestressing force to the respective closing element to close the inlet channel. Each closing element assigned a braking device which is arranged separately from the closing element and which gradually brakes an opening movement of the closing element when the inlet channel is opened, independently of the closing spring. The braking device having a stop body with a stop surface against which the closing element can be brought to bear after an opening movement when the inlet channel is opened, the stop body being arranged movably and/or yieldingly in the opening direction of the closing element.