Imperforate bowl: centrifugal separators – Including sealing means – Comprising seal – or element cooperating therewith – movable...
Patent
1997-04-10
1998-08-11
Cooley, Charles E.
Imperforate bowl: centrifugal separators
Including sealing means
Comprising seal, or element cooperating therewith, movable...
494 70, B04B 114, B04B 118
Patent
active
057920370
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a centrifugal rotor and a slide for such a rotor.
BACKGROUND OF THE INVENTION
A centrifugal separator comprising a rotor body, which is rotatable around a centre axis, often has at least one annular slide which is arranged coaxially with the rotor body and is axially movable relative thereto during rotation of the rotor. A slide of this kind, which is comparatively thick and stiff in order not to be deformed when it is subjected to large both radial and axial forces, is as a rule adapted for opening and closing of certain passages in the rotor body, e.g. outlet passages from a separation chamber or flow passages for a so called operating liquid. As a rule the slide is axially movable in a hydraulic or pneumatic way but can alternatively or additionally be influenced by mechanical springs of one kind or another.
The radial guiding of the slide during its axial movements takes place as a rule in a way such that the radially inner edge portion of the slide with an insignificant play surrounds and is guided by a central cylindrical part of the rotor body. In order to avoid that the slide causes unbalance of the rotor during its rotation it is strived at having a play as small as possible between the slide and said part of the rotor body.
A problem in this connection is that the slide during its axial movement in the rotor is sometimes subjected to forces which tend to cause the slide to be inclined in relation to the centre axis of the rotor body. This leads to abutment between the slide and said central part of the rotor body, so that friction forces come up. These can be so large that they cause damage to the slide and/or the rotor body.
Different solutions to this problem have been proposed in U.S. Pat. No. 4,505,698 in connection with an annular slide that is adapted for opening and closing of peripheral outlets from a separation chamber of a centrifugal rotor. According to a first design proposal presented in U.S. Pat. No. 4,505,698 (FIGS. 1 and 2) the annular slide should be formed in one single piece and have a centre part and a circumferential part. The centre part should be in the form of an axially expandable sleeve, which at one of its ends is axially and radially fixed relative to the centrifugal rotor and at its other end supports said circumferential part of the slide. A separate radial guiding of the circumferential slide part or said other end of the sleeve formed centre part is said not to be necessary, as the sleeve formed centre part should be sufficiently stiff to take up radial forces which may influence the circumferential part of the slide during operation of the centrifugal rotor.
According to a second design proposal presented in U.S. Pat. No. 4,505,698 (FIGS. 3 and 4) the annular slide should be adapted to be centered by a separate member which simultaneously constitutes a spring for axial actuation of the slide.
According to a third design proposal presented in U.S. Pat. No. 4,505,698 (FIG. 5) the annular slide by its radially inner edge portion should be connected with the rotor body through an annular rubber sleeve, which has a relatively small axial spring constant but a relatively large radial spring constant. Hereby, it is said, the slide could be given a required axial movability and a very limited radial movability.
Said first design proposal is believed to be difficult to realize, since weakening of the sleeve formed centre part of the slide in order to enable an axial movement of the circumferential part of the slide is difficult to accomplish without giving the circumferential part of the slide an undesired possibility of also moving radially as a consequence of radial forces coming up due to the imbalance of the rotor during its operation. Such unbalanced forces are normally very large. The same problem in connection with the imbalance of the centrifugal rotor can be forseen in connection with said third design proposal which, like said second design proposal, resides in the use of a separate member for centering of the s
REFERENCES:
patent: 3193194 (1965-07-01), Steinacker
patent: 3765599 (1973-10-01), Hemfort
patent: 4151951 (1979-05-01), Kohlstette
patent: 4505698 (1985-03-01), Broker
patent: 4813923 (1989-03-01), Johansson
Bodelson Berth
Holm Staffan
Klintenstedt Kjell
Ohlson Nils-Gunnar
Salmi Toini
Alfa Laval AB
Cooley Charles E.
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