A first communication groove (38) extending from a start point of a discharge port (36) in a direction opposite to rotation direction of vanes (22) is formed. A first end portion (38E) of this groove is connected to the start point of the discharge port (36). When a front-side vane in a rotation direction of a driving shaft (11) is positioned at the start point of the discharge port (36), a second end portion (38S) of the groove is positioned at a rear side in the rotation direction with respect to a rear-side vane coming immediately after the front-side vane, and communicates with a suction port (35). A part of working fluid in a front-side pump chamber (27-1) can therefore be introduced into a rear-side pump chamber (27-2) that communicates with the suction port (35), thereby lessening excessive pressure increase of the front-side pump chamber (27-1) and suppressing pulsation phenomenon.

A suction side end part of a suction guide passage and a discharge side end part of a discharge guide passage are opposed to each other with a gap therebetween. At a deviation angle at which contraction of a pump chamber starts, an outer peripheral part of the discharge side end part is formed along an inner tooth, and an inner peripheral part of the discharge side end part is formed along an outer tooth. A working tool that rotates and cuts circularly is moved around on a pump housing in a single continuous line to form an outline of the discharge guide passage, thereby forming the discharge guide passage. The working tool is moved around on the pump housing in a single continuous line to form an outline of the suction guide passage, thereby forming the suction guide passage.

A stacked gerotor pump is provided. The stacked gerotor pump includes a first gerotor pump defining a first inlet section and a first outlet section, a second gerotor pump defining a second inlet section and a second outlet section and a plate. The plate is interposed between the first and second gerotor pumps and defines upstream cavities respectively communicative with the first and second inlet sections, downstream cavities respectively communicative with the first and second outlet sections and a pre-pressurization hole by which the second outlet section is communicative with the first inlet section.

An improved screw-spindle pump, particularly for cooling systems, includes a first screw, a second screw and a pump housing, inside which the first screw and the second screw are rotatably housed between the first screw, the second screw and the pump housing, being defined pumping chambers adapted to move, as a consequence of the rotation of the first screw and the second screw, a fluid from a suction area to a delivery area of the pump.

The pump housing housing the first screw and the second screw is made in one piece.

A fluid pressure unit is provided with an inverter (17), a motor (10) controlled by the inverter, a pump (11) driven by the motor to discharge a fluid, a detector (16) configured to detect a pressure of the fluid, a flow rate of the fluid, or both, a controller (20) configured to control the inverter such that a pressure of the pump, a flow rate of the pump, or both becomes a predetermined value based on a detected value by the detector, and a suppressor (33) configured to suppress a change of an output of the inverter caused by a pulsation frequency component of the fluid included in the detected value.

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.

The invention relates to a vane pump for conveying liquids, in particular viscous oils, which vane pump includes: a rotor having sliding slots in which movable vanes are held and can be countersunk in relation to a rotor radius (r); a pump housing including a pump chamber, which encloses the rotor; and an inlet and an outlet, which open into the pump chamber at at least one end face of the rotor; radial elevations protruding, with respect to the sliding slots, over the circumference of the rotor, which elevations form a rotor radius (r) on either side of the vanes that can be countersunk, and radial pockets being recessed, relative to the rotor radius (r), between the radial elevations. Within the radial elevations, recesses are formed on the at least one end face of the rotor at which the inlet and the outlet open, which recesses provide rotating anticipatory control geometry for reducing pressure spikes in the vane cells.

A rotary pump includes: a housing featuring a housing inlet and a low-pressure space on a low-pressure side of the pump and featuring a housing outlet and a high-pressure space on a high-pressure side of the pump; a delivery chamber; a delivery rotor in the delivery chamber; a setting structure which can be moved in a first setting direction and, counter to the first setting direction, in a second setting direction in order to perform a setting movement which adjusts the specific delivery volume of the rotary pump; and at least a first setting chamber for charging the setting structure with a setting pressure which acts in the second setting direction, wherein the fluid pressure in the high-pressure space acts on a pressure equalization surface on the outer circumference of the setting structure resulting in an external additional force which acts on the setting structure in the first setting direction.

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.

The disclosure provides a pump device capable of suppressing hydraulic amplitude and reducing noise or vibration associated with hydraulic amplitude while simplifying the structure. The pump device includes: a housing which defines a suction port, a discharge port, and an accommodation chamber; and a pump unit which is arranged in the accommodation chamber and which defines a pump chamber that expands and contracts to exert a pumping action including a suction stroke and a pressurization and discharge stroke on a fluid. The housing includes an air introduction hole that is opened to introduce air into the pump chamber at a predetermined opening timing immediately before the suction stroke is completed.