An internal-gear pump has a housing which has a first fluid port and a second fluid port. An inner rotor is mounted in the housing so as to be rotatable about an inner rotor axis and has an external toothing. An outer rotor is rotatable in the housing about an outer rotor axis and has an internal toothing which, to generate a pump action, engages with the external toothing of the inner rotor. The internal-gear pump furthermore has a ring element which is mounted movably in the housing so as to be pivotable between a first position and a second position. At least a third fluid port is formed on the housing. The third fluid port is arranged relative to the ring element such that, in the first position of the ring element, the third fluid port is connected to the second fluid port. In the second position, said third fluid port is separated from the second fluid port.

An internal-gear pump has a housing which has a first fluid port and a second fluid port. An inner rotor is mounted in the housing so as to be rotatable about an inner rotor axis and has an external toothing. An outer rotor is rotatable in the housing about an outer rotor axis and has an internal toothing which, to generate a pump action, engages with the external toothing of the inner rotor. The internal-gear pump furthermore has a ring element which is mounted movably in the housing so as to be pivotable between a first position and a second position. At least a third fluid port is formed on the housing. The third fluid port is arranged relative to the ring element such that, in the first position of the ring element, the third fluid port is connected to the second fluid port. In the second position, said third fluid port is separated from the second fluid port.

A method of operating a rolling piston compressor includes determining a pressure difference (?P) between a discharge pressure (P.sub.d) within a compression volume and a suction pressure (P.sub.s) within a suction volume; determining a pressure ratio (r.sub.p) equal to the discharge pressure (P.sub.d) over the suction pressure (P.sub.s); estimating a discharge pressure (P.sub.d) based at least in part on the pressure difference (?P) and the pressure ratio (r.sub.p); determining that the discharge pressure (P.sub.d) is greater than a predetermined pressure limit (P.sub.d-limit); and lowering a target speed (?.sub.target) of the rolling piston compressor.

A rotary compressor, including a cylinder, an inner peripheral surface of which is defines a compression space, provided with a suction port configured to communicate with the compression space to suction and provide refrigerant to the compression space; a roller rotatably provided in the compression space of the cylinder, and including with a plurality of vane slots at predetermined intervals along an outer peripheral surface, the plurality of vanes each providing a back pressure at one side thereinside; a plurality of vanes slidably inserted into the plurality of vane slots, respectively, to rotate together with the roller, front end surfaces of the plurality of vanes coming into contact with an inner periphery of the cylinder due to the back pressure to partition the compression space into a plurality of compression chambers; and a main bearing and a sub bearing provided at both ends of the cylinder, respectively.

A rotary compressor, including a cylinder, an inner peripheral surface of which is defines a compression space, provided with a suction port configured to communicate with the compression space to suction and provide refrigerant to the compression space; a roller rotatably provided in the compression space of the cylinder, and including with a plurality of vane slots at predetermined intervals along an outer peripheral surface, the plurality of vanes each providing a back pressure at one side thereinside; a plurality of vanes slidably inserted into the plurality of vane slots, respectively, to rotate together with the roller, front end surfaces of the plurality of vanes coming into contact with an inner periphery of the cylinder due to the back pressure to partition the compression space into a plurality of compression chambers; and a main bearing and a sub bearing provided at both ends of the cylinder, respectively.

A fuel supply system includes a gear pump, and a minimum pressurizing check valve including a cylinder and a piston that partitions the internal space of the cylinder into a first chamber that communicates with the metering section and a second chamber that communicates with a system inlet, the piston is spring-biased in a direction toward the first chamber, a side wall of the cylinder is provided with an outflow port having an opening degree adjusted as the piston moves back and forth, the minimum pressurizing check valve keeps a differential pressure between the system inlet and the outlet of the metering section constant when the rotation speed of the gear pump is equal to or more than a lower threshold and is equal to or less than an intermediate threshold.

A fuel supply system includes a gear pump, and a minimum pressurizing check valve including a cylinder and a piston that partitions the internal space of the cylinder into a first chamber that communicates with the metering section and a second chamber that communicates with a system inlet, the piston is spring-biased in a direction toward the first chamber, a side wall of the cylinder is provided with an outflow port having an opening degree adjusted as the piston moves back and forth, the minimum pressurizing check valve keeps a differential pressure between the system inlet and the outlet of the metering section constant when the rotation speed of the gear pump is equal to or more than a lower threshold and is equal to or less than an intermediate threshold.

A compressor may include first and second scroll members having first and second scroll wraps, respectively. The scroll members define a suction inlet, a discharge outlet, and fluid pockets moving therebetween. The second scroll member may include a port, and a passage. The port may be in fluid communication with at least one of the pockets. The passage may extend through a portion of the second end plate and may be in fluid communication with the port. A valve assembly may be disposed in the passage and may include a valve member displaceable between open and closed positions. A recompression volume may be disposed between the valve member and the at least one of the pockets. The recompression volume may be less than or equal to approximately one percent of a volume of one of the pockets at a suction seal-off position.

A fuel supply system includes a gear pump, and a minimum pressurizing check valve including a cylinder and a piston that partitions the internal space of the cylinder into a first chamber that communicates with the metering section and a second chamber that communicates with a system inlet, the piston is spring-biased in a direction toward the first chamber, a side wall of the cylinder is provided with an outflow port having an opening degree adjusted as the piston moves back and forth, the minimum pressurizing check valve keeps a differential pressure between the system inlet and the outlet of the metering section constant when the rotation speed of the gear pump is equal to or more than a lower threshold and is equal to or less than an intermediate threshold.

A fuel supply system includes a gear pump, and a minimum pressurizing check valve including a cylinder and a piston that partitions the internal space of the cylinder into a first chamber that communicates with the metering section and a second chamber that communicates with a system inlet, the piston is spring-biased in a direction toward the first chamber, a side wall of the cylinder is provided with an outflow port having an opening degree adjusted as the piston moves back and forth, the minimum pressurizing check valve keeps a differential pressure between the system inlet and the outlet of the metering section constant when the rotation speed of the gear pump is equal to or more than a lower threshold and is equal to or less than an intermediate threshold.