An apparatus for damping pressure pulsation for a compressor of a gaseous fluid in a refrigerant circuit including a housing with an inlet opening and at least one first outlet opening and a piston element movable in an axial direction within a volume enclosed by the housing and supported on the housing in a beared manner via a spring element, wherein the piston element respectively controls a flow cross section of the inlet opening and the first outlet opening, wherein the piston element and the housing have at least one first sealing surface and a second sealing surface. The first sealing surfaces form a first seat and the second sealing surfaces form a second seat, wherein between the seats, one chamber enclosed by the housing and the piston element for expanding the fluid when flowing into the chamber and/or at least one second outlet opening in the housing is formed.

The present invention relates to a device (1, 30) for the recirculation of an at least partially gaseous composition containing hydrogen, wherein the device (1, 30) is a dry rotary pump comprising a first rotating shaft (13) and a second rotating shaft (14) driving respectively a first piston with claws (8) and a second piston with claws (9) in rotation in a pumping chamber (2) comprising an inlet orifice (11) and an outlet orifice (10) for the gaseous composition, the first rotating shaft (13) and the second rotating shaft (14) being configured to be driven in rotation by a drive system (17,18) situated in a gear chamber (4), wherein the device (1, 30) comprises a first pair of seals (19) and a second pair of seals (20), each comprising a first shaft seal (19a, 20a) and a second shaft seal (19b, 20b), the first pair of seals (19) being provided around the first rotating shaft (13) and the second pair of seals (20) being provided around the second rotating shaft (14) between the pumping chamber (2) and the gear chamber (4), wherein the device (1, 30) comprises a pressure equalization chamber (25) which is in fluid connection with a gap (24) present between the first shaft seal (19a, 20a) and the second shaft seal (19b, 20b) of the first and of the second pair of seals (19, 20) to regulate the pressure in the gap (24), wherein the gear chamber (4) is in fluid connection with the gap (24), and wherein the pumping chamber (2) is in fluid connection with the first shaft seal (19a) of the first pair of seals (19) and with the first shaft seal (20a) of the second pair of seals (20) by means of a pulsation attenuation chamber (22). The present invention also relates to a fuel cell system (40, 50, 60, 70, 80, 90) comprising a device for recirculation according to the present invention.

A fluid working system such as a pump for displacing a working fluid such as hydraulic fluid or a motor using a working fluid is provided. The system may have a positive displacement machine which includes one or more working chamber with displacement means such as a cylinder with a reciprocating piston. There are also two or more fluid ports to allow the working fluid to flow into and out of the working chamber. The working fluid flows from one fluid port means to another either being forced to do so when pumped or moving the piston when functioning as an engine. The fluid working system has associated therewith a non-dead compliance volume of a material such as syntactic foam. This compliance volume acts to smooth any pressure fluctuations within the working fluid system.

A shunt-enhanced decompression and pulsation trap (SEDAPT) for a screw compressor assists internal compression (IC), reduces gas pulsation and NVH (Noise, Vibration & Harshness), and improves off-design efficiency, without using a slide valve and/or a serial pulsation dampener. The SEDAPT includes an inner casing, e.g., an integral part of the compressor chamber, and an outer casing, e.g., surrounding part of the inner casing near the compressor discharge port, forming at least one diffusing chamber with an outflow orifice or nozzle equipped with an ODV (one-direction valve) at the outflow exit and a feedback region that provides a feedback outflow loop between the compressor chamber and the compressor discharge port. The SEDAPT automatically bleeds or compensates cavity pressure to meet different outlet pressures, eliminates or reduces energy waste, gas pulsations and NVH associated with any over-compression and under-compression before the discharge port opens.

A fluid working system such as a pump for displacing a working fluid such as hydraulic fluid or a motor using a working fluid is provided. The system may have a positive displacement machine which includes one or more working chamber with displacement means such as a cylinder with a reciprocating piston. There are also two or more fluid ports to allow the working fluid to flow into and out of the working chamber. The working fluid flows from one fluid port means to another either being forced to do so when pumped or moving the piston when functioning as an engine. The fluid working system has associated therewith a non-dead compliance volume of a material such as syntactic foam. This compliance volume acts to smooth any pressure fluctuations within the working fluid system.

A discharge chamber, into which refrigerant compressed by a compression mechanism, is discharged, is formed in an inside of a housing. A resonator is connected to an intermediate portion of a communication passage, which communicates between the discharge chamber and a discharge port of the housing. The resonator includes a resonance chamber and an inlet passage. The inlet passage has one end portion, which is connected to the intermediate portion of the communication passage, and another end portion, which is connected to the resonance chamber.

In a gear pump, a gear chamber is defined in a housing hole of a housing. A pair of gears is housed in the gear chamber. The gears are rotatably supported at support holes of a pair of side plates via support shafts. As viewed in an axial direction of the support shafts during rotation of the gears, addendum circles of the gears displaced under a differential pressure between a low-pressure chamber and a high-pressure chamber form first contact points with respect to an inner peripheral surface that defines a housing hole. As viewed in the axial direction of the support shafts during rotation of the gears, the first contact points are covered with the side plates displaced under the differential pressure.

A compression mechanism portion housed in a closed case is provided with a partition plate located between a first cylinder and a second cylinder. The compression mechanism includes a first bearing discharge port formed to a first bearing and a first partition plate discharge port formed to the partition plate as discharge ports for discharging working fluid compressed in a first cylinder chamber, and also includes, as discharge port for discharging working fluid compressed in a second cylinder chamber, a second bearing discharge port formed to a second bearing and a second partition plate discharge port formed to the partition plate. A cross-sectional area of the first partition plate discharge port is formed to be smaller than a cross-sectional area of the first bearing discharge port, and a cross-sectional area of the second partition plate discharge port is formed to be smaller than a cross-sectional area of the second bearing discharge port.

A shunt pulsation trap for a positive-displacement gas-transfer machine having a gas transfer chamber with an intake port and a discharge port and having at least one positive-displacement drive device (such as two cooperating rotors) defining a compression region of the transfer chamber. The trap includes a pulsation-trap chamber arranged for parallel fluid flow with the machine transfer chamber. The trap has a first (e.g., inlet) port in communication with the compression region of the transfer chamber (e.g., at least one lobe span away or totally isolated from the transfer-chamber intake port), a second (e.g., discharge) port in communication with the discharge port of the transfer chamber, and at least one pulsation dampener in the pulsation-trap chamber. In this way, the shunt pulsation trap traps and attenuates gas pulsations before discharge from the machinery transfer chamber, thereby reducing induced NVH and improving machinery efficiency.

A dual-cylinder two-stage variable capacity compressor is provided, including: a first cylinder, having an exhaust port connected to a first exhaust channel: a second cylinder, wherein the second cylinder is provided with a ventilating slider, and the ventilating slider is provided with a first gas transit channel and a second gas transit channel; wherein, when the ventilating slider is at a first connecting position, the first exhaust channel is connected to a suction channel in a second cylinder when the ventilating slider is at a second connecting position, the first exhaust channel is connected to a second exhaust channel. The compressor of the present disclosure can vary its own capacity, that is, the variation of the compressor's capacity can be realized by arranging a ventilating slider, which will meet the requirements of variation loads of the compressor in different seasons.