A liquid-ring vacuum pump comprises a pump casing and a shaft eccentrically mounted in the pump casing. An impeller and a rotor of a drive motor are connected to the shaft. A disk cam is arranged parallel to the impeller. A first main bearing for the shaft is arranged between the impeller and the rotor of the drive motor, on the plane of the disk cam. The impeller is arranged between the first main bearing and a second main bearing. The arrangement of the bearings prevents the shaft from bending, thus allowing the leakage gap between the impeller and the disk cam to be kept small.

A positive displacement fluid pump is provided. The fluid pump includes a housing defining an internal cavity. A motor having a drive shaft that rotates about an axis is housed within the internal cavity of the housing. An internal plate is adjacent the motor and includes a central bore through which the drive shaft extends. The fluid pump further includes an external plate including an inlet in fluid communication with a suction port and an outlet in fluid communication with a delivery port. A pumping ring is sandwiched between the internal and external plates, and a pumping arrangement is located within the pumping ring and axially between the internal plate and the external plate. The pumping arrangement is rotatably coupled to the drive shaft such that rotation of the pumping arrangement by the drive shaft causes fluid to be pumped from the suction port to the delivery port.

A positive displacement fluid pump is provided. The fluid pump includes a housing defining an internal cavity. A motor having a drive shaft that rotates about an axis is housed within the internal cavity of the housing. An internal plate is adjacent the motor and includes a central bore through which the drive shaft extends. The fluid pump further includes an external plate including an inlet in fluid communication with a suction port and an outlet in fluid communication with a delivery port. A pumping ring is sandwiched between the internal and external plates, and a pumping arrangement is located within the pumping ring and axially between the internal plate and the external plate. The pumping arrangement is rotatably coupled to the drive shaft such that rotation of the pumping arrangement by the drive shaft causes fluid to be pumped from the suction port to the delivery port.

A liquid-ring, rotating-casing compressor comprises a shaft carrying an impeller having a core and a plurality of radially extending vanes rotatably coupled to the shaft for rotation around a first axis, and a tubular casing mounted for rotation relative to the impeller around a second axis that is parallel to and offset from the first axis. The casing and impeller define a compression zone wherein edges of the vanes rotate in increasing proximity to an inner surface of the casing and an expansion zone wherein edges of the vanes rotate in increasing spaced-apart relationship along an inner surface of the casing. An inlet port communicates with the expansion zone, an outlet port communicates with the compression zone, and a drive imparts rotating motion to the casing. The eccentricity ecr of the casing relative to the impeller is between about (1c)/4 and (1c)/9, preferably less than half (1c)/3.

A liquid-ring, rotating-casing compressor comprises a shaft carrying an impeller having a core and a plurality of radially extending vanes rotatably coupled to the shaft for rotation around a first axis, and a tubular casing mounted for rotation relative to the impeller around a second axis that is parallel to and offset from the first axis. The casing and impeller define a compression zone wherein edges of the vanes rotate in increasing proximity to an inner surface of the casing and an expansion zone wherein edges of the vanes rotate in increasing spaced-apart relationship along an inner surface of the casing. An inlet port communicates with the expansion zone, an outlet port communicates with the compression zone, and a drive imparts rotating motion to the casing. The eccentricity ecr of the casing relative to the impeller is between about (1c)/4 and (1c)/9, preferably less than half (1c)/3.

The invention relates to a two-stage pump for pumping at least one medium, wherein the pump has a liquid ring stage (1), a side channel stage (2), and two medium accesses (3), wherein the liquid ring stage (1) has a medium chamber (12) and two medium openings (13, 14), wherein the two medium openings (13, 14) of the liquid ring stage (1) open onto the medium chamber (12) of the liquid ring stage (1), wherein the side channel stage (2) has a medium chamber (22) and two medium openings (23, 24), wherein the two medium openings (23, 24) of the side channel stage (2) open onto the medium chamber (22) of the side channel stage (2), and wherein one medium opening (23) of the two medium openings (23, 24) of the side channel stage (2) and one medium opening (13) of the two medium openings (13, 14) of the liquid ring stage (1) merge to form a common overflow opening (4).

The invention relates to a two-stage pump for pumping at least one medium, wherein the pump has a liquid ring stage (1), a side channel stage (2), and two medium accesses (3), wherein the liquid ring stage (1) has a medium chamber (12) and two medium openings (13, 14), wherein the two medium openings (13, 14) of the liquid ring stage (1) open onto the medium chamber (12) of the liquid ring stage (1), wherein the side channel stage (2) has a medium chamber (22) and two medium openings (23, 24), wherein the two medium openings (23, 24) of the side channel stage (2) open onto the medium chamber (22) of the side channel stage (2), and wherein one medium opening (23) of the two medium openings (23, 24) of the side channel stage (2) and one medium opening (13) of the two medium openings (13, 14) of the liquid ring stage (1) merge to form a common overflow opening (4).