Sealed pump

The present application relates to liquid pumps and in particular to one having the moving parts thereof sealed against leakage.

Certain industries, such as nuclear energy, require purified liquids or gases to be pumped through tubing that is totally sealed against leakage. To create such a sealed system, the pump itself must be totally sealed. Pumps have moving parts, and where the parts are moved by a shaft extending through the wall of a pump housing, leakage can occur around the portion of the shaft extending through the aperture. As a practical matter, such apertures cannot be totally sealed against leakage and therefore where it is desirable to have a totally enclosed system, the pump must have moving parts that are driven without requiring an aperture through which a shaft extends.

Presently, pumps driven without an aperture in the pump wall have ferrous portions connected to the pump drive that are magnetically conductive. The magnetically conductive portions of the pump rotate within a non-ferrous housing, and surrounding the housing is a drive consisting of one or more magnets that are rotated around the circumference of the non-magnetic housing. The magnets of the drive attract the ferrous portions of the pump and cause the blades of the pump to be rotated with the rotating magnets of the drive, thereby transferring the energy from exterior of the enclosed system to the rotating portions therein. Such drive assemblies can be large and bulky, and it would be desirable to provide an alternative drive which can be constructed so as to be more compact.

Briefly, the present invention is embodied in a pump for pumping a liquid or a gas in a sealed environment. For the purposes of this discussion, the pump will be described as pumping a “liquid” where the term “liquid” is intended to include any substance in either a liquid or gaseous state. The key to the invention is that the pump is driven by a brushless rotor mounted on a shaft on which is also mounted a drive for urging liquid within the pump from an input end to an output end. The rotor, the drive, and the two ends of the shaft are all enclosed within a sealed chamber having only an input opening through which liquid enters the chamber and an output opening toward which liquid is urged by the drive.

The pump is surrounded by a housing, a portion of which may include a cylindrical outer shell of a stator for driving the rotor. The stator has a plurality of wire windings in the form of lobes that extend radially inward from the inner surface of the shell, with a central opening extending axially through the inner ends of the lobes through which the rotor extends.

In one embodiment, a channel extends along the outer surface of the rotor and through the central opening of the stator such that liquid is forced by the drive through the central opening of the stator as it moves from the input end to the output end. In this embodiment, the channel may be positioned between the spaced apart lobes of the windings of the stator.

In a second embodiment, an inner enclosure is configured to have a cylindrical portion extend through the central opening of the stator with the interior of the cylindrical portion occupied solely by the rotor. In this embodiment, the inner enclosure has an input opening and an output opening and the drive moves liquid from the input opening to the output opening without requiring the liquid to pass through the central opening of the stator.

Referring to FIG. 1, a sealed pump 10 in accordance with the invention has a sealed housing 12 that includes as a central portion the outer surface of a tubular shell 15 for a stator 16 for rotating a brushless rotor as is further described below.