The present invention relates to improvements in the area of flexible impeller pumps. In particular, the present invention relates to flexible impellers with improved profiles(such as dual sealing lips), which are particularly well-suited to multiple cam pumps. A novel mounting hub configuration for mounting an impeller on a drive shaft is also provided. Pumps comprising such impellers and/or mounting hubs are provided, as are associated methods of installation and removal.

A fluid ring compressor comprises a first single-acting compression stage having a first impeller eccentrically mounted in a housing and a second single-acting compression stage having a second impeller eccentrically mounted in a housing. The first compression stage and the second compression stage are separated from one another by a sealing gap. The sealing gap is arranged between a suction section of the first compression stage and a suction section of the second compression stage.

A posture control unit (contact portion 6f) that controls a posture of a balance weight-equipped slider 5 so that a slider portion 5a of the balance weight-equipped slider 5 maintains the posture parallel to an orbiting bearing 2d is provided at a position corresponding to a central portion in an axial direction of the orbiting bearing 2d between an eccentric direction-side side surface of an eccentric shaft portion 6a of a rotary shaft 6 and an inner wall surface of a slide hole 5aa facing the side surface.

A scroll compressor is disclosed. The scroll compressor includes a rotating shaft coupling portion axially extending from a central portion of an orbiting end plate to radially overlap an orbiting wrap, such that an eccentric portion of a rotating shaft is coupled thereto, and a portion of the orbiting wrap may extend from an end surface of the rotating shaft coupling portion facing a fixed end plate. With the configuration, a distance between bearing reaction force and gas reaction force acting on the orbiting scroll can be reduced, to stabilize a behavior of the orbiting scroll and thus reduce back pressure, thereby decreasing friction loss between scrolls. Simultaneously, compression chambers can be formed even in a central portion of the orbiting scroll, which can increase a compression ratio and improve volumetric efficiency.

A scroll compression mechanism 11 for compressing refrigerant and a driving motor 13 that drives the scroll compression mechanism 11 are accommodated in a casing 3, the scroll compression mechanism 11 is supported in the casing 3 by a main frame 21, the driving shaft 15 is connected to a rotor 39 of the driving motor 13 and supported in the casing 3 by a bearing plate 8, a pickup 45 is connected to an oil supply path 41 extending in an up-and-down direction in the driving shaft 15, and intercommunication paths 38B, 54A through which lubrication oil scraped up by the pickup 45 and supplied to respective lubrication sites is returned to the lower side of the driving motor 13 are provided between the stator 37 and the spacer ring 38 or between the spacer ring 38 and the casing 3.

A rotational element is internally provided with at least one annular cavity which separates a central part from an outer part of the rotational element, wherein the outer part is provided with one or more holes or channels which extend from an outer wall of the outer part to the annular cavity and wherein in the holes or channels fixation means are fixedly mounted which each extend through the corresponding hole or channel and which have a tip which is abutting against the central part.

The present invention relates to improvements in the area of flexible impeller pumps. In particular, the present invention relates to flexible impellers with improved profiles (such as dual sealing lips), which are particularly well-suited to multiple cam pumps. A novel mounting hub configuration for mounting an impeller on a drive shaft is also provided. Pumps comprising such impellers and/or mounting hubs are provided, as are associated methods of installation and removal.

A compressor includes a housing; a first scroll and a second scroll located inside the housing, the first scroll being configured to have a first end plate and a first volute extending from the first end plate towards the second scroll, the second scroll being configured to have a second end plate and a second volute extending from the second end plate towards the first scroll, the first volute and the second volute being configured to engage with each other so as to define a compression chamber therebetween; a motor including a stator and a rotor, which is located on one side of the second scroll away from the first scroll and configured for driving the first scroll to rotate by the rotor so as to drive the second scroll to rotate; a driving mechanism including a receiving hub and a flange configured to extend radially from a first end of the receiving hub and support the second end plate; wherein a second end of the receiving hub is secured to the rotor so as to position the rotor to be spaced from the stator with a certain gap between the rotor and the stator.