Rotating machine

Details Rotating machine Rotating machine

1999-01-08

2000-11-21

Ryznic, John E.

Rotary kinetic fluid motors or pumps

With separating means or guard for solid matter in working...

415206, F01D 2500, F03B 1100

Patent

active

06149383&

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a relating machine comprising a casing and a rotor which is rotatable relative to the casing.
There are many examples of rotating machines in which a gap is defined between a rotor and a stator in an arrangement such that material can become jammed in the gap. For example, submersible pumps used to pump waste water generally comprise a rotor in the form of an impeller which is housed within a stator in the form of a casing. A circular aperture is defined in the casing and a tubular portion of the rotor extends into the aperture. If the impeller is turned within the casing when the casing is submerged in a fluid, fluid is drawn into the casing through a helical passageway defined within the impeller. Thus the motion of the impeller relative to the casing establishes a pressure difference between the fluid on the outside of the casing and the fluid within the casing. That pressure differential is also applied across the gap defined in the aperture in the casing by the portion of the impeller which extends into the casing.
In a conventional submersible pump widely used in the wastewater treatment industry, the aperture in the casing is defined by a brass sleeve which is received in a circular opening in the casing. The radially inner surface of the brass sleeve is smooth and faces a radially outer surface of the rotor which is also smooth. It is believed that these surfaces have been made smooth to reduce the likelihood of material becoming jammed between them. In the known pump the spacing between the two facing surfaces is 1.75 mm.
When the known pumps are used in waste water carrying fibrous articles, there is a tendency for fibres from those articles to become wound around the portion of the impeller within the casing apertures. Over time, material can build up in the gap between the two relatively rotating components, the pressure differential that the pump applies across the gap being instrumental in drawing material into the gap. As a result the known pumps are prone to failure. The applicants have monitored the failure rate of the known pumps and have discovered that the maximum time for which a monitored pump has run in waste water without jamming is 670 hours. Each time a pump jams it has to be taken out of service and generally the pump has to be fully refurbished at considerable expense. It would clearly be highly advantageous to be able to increase the service life of the known pumps. Given the relatively wide gap between the relatively moving faces of the impeller and casing, at least before that gap has become clogged with material, a significant flow of fluid occurs through the gap and this adversely affects the pump efficiency. It would be easy to increase pump efficiency by reducing the width of the gap, but presumably this has never been attempted in the past because of real or perceived fears that the already limited service life of the pump would be further reduced.
It is an object of the present invention to obviate or mitigate the problems outlined above.
According to the present invention, there is provided a rotating machine comprising a casing and a rotor which is rotatable relative to the casing, the rotor being positioned relative to an aperture in the casing such that an annular gap is formed adjacent the aperture between a first surface defined by the rotor and a second surface defined by the casing, wherein at least one of the first and second surface has a surface structure which is operative to prevent the accumulation of material within the gap.
The surface structure may be selected so as to progressively eject material from the gap as a result of the relative rotation of the first and second surfaces, or may be selected to progressively disintegrate any material between the surfaces. Preferably the surface structure is defined by a screw thread on one or more of the first and second surfaces. The screw thread may be formed on the first surface which is defined by the rotor and the second surface may be smooth.
The screw thread is preferably f

REFERENCES:
patent: 1697202 (1929-01-01), Nagle
patent: 2409497 (1946-10-01), Kessel
patent: 2658453 (1953-11-01), Walters
patent: 3788762 (1974-01-01), Partos
patent: 4063848 (1977-12-01), Wiggins et al.
patent: 4143993 (1979-03-01), Blum
patent: 4347032 (1982-08-01), Possell
patent: 4386780 (1983-06-01), Dernedde
patent: 4416586 (1983-11-01), Diederich et al.
patent: 4992022 (1991-02-01), Aust et al.
patent: 5709528 (1998-01-01), Hablanian

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