US3056505A

US3056505A - Centrifuges

Info

Publication number: US3056505A
Application number: US847541A
Authority: US
Inventors: Andersson Nils Vilhelm
Original assignee: Landsverk AB
Current assignee: Landsverk AB
Priority date: 1959-07-24
Filing date: 1959-10-20
Publication date: 1962-10-02
Anticipated expiration: 1979-10-02
Also published as: DE1151221B; GB864596A; NL250317A; NL123103C; FR1247363A

Description

Oct. 2, 1962 N. v. ANDERSSON 3,056,505

CENTRIFUGES Filed Oct. 20, 1959 4 Sheets-Sheet 1 Fig.1

l/WEIVTOR NILS VILHELM ANDERSSON 1962 N. v. ANDERSSON 3,

CENTRIFUGES Filed Oct. 20, 1959 4 Sheets-Sheet 2 Fig. 2

lA/VE/VTOR NILS VILHELM ANDERSSON Oct. 2, 1962 N. v. ANDERSSON CENTRIFUGES 4 Sheets-Sheet 3 Filed Oct. 20, 1959 INVENTOR NILS VILHELM .ANDERSSON Oct. 2, 1962 N. v. ANDERSSON CENTRIFUGE'S 4 Sheets-Sheet 4 Filed 001;. 20, 1959 l/VVE/VTOR NILS VILHELM ANDERSSON United States Patent Ofifice 3,056,505 Patented Oct. 2, 1962 3,056,505 CENTRIFUGES Nils Vilhelm Andersson, Landskrona, Sweden, assignor to Aktiebolaget Landsverk, Landskrona, Sweden, a corporation of Sweden Filed Oct. 20, 1959, Ser. No. 847,541 Claims priority, application Sweden July 24, 1959 Claims. (Cl. 210-369) The present invention relates generally to discontinuously operating centrifuges and particularly relates to a cut-off valve for a central outlet opening at the bottom of the centrifugal drum, through which the material, such as sugar crystals, subjected to centrifugal treatment may be discharged from the centrifugal drum. Valves for opening and closing the discharge opening of a cen trifuge are known. They frequently consist of a conical funnel placed upside down above the outlet opening or openings. The funnel is secured to a sleeve, which may be displaced manually or by means of a pneumatic operating contrivance along the spindle carrying the drum. When the funnel is in its lowermost position, the bottom openings of the drum are closed, so that the filling mass or pulp which is to be subjected to centrifugal treatment may be supplied, without the liquid in the filling mass discharging down through the bottom openings. When the funnel is then raised to its upper position upon the termination of the centrifugal treatment, the material subjected to the treatment may be scraped off by means of an excavator of known type, and allowed to fall down through the outlet opening in the bottom of the drum, so that another charge of the material may be treated. It has been found that in treating baking material, that is to say vault-building material, such as sugar of a high degree of purity, the material forms vaults from the covering tunnel to the inner surface of the drum or to the material remaining in the drum, so that the material cannot be scraped off by means of the excavator and be removed through the bottom openings.

These difiiculties are avoided according to the invention by making the cut-off valve member comprising a deformable, preferably flexible and elastic body, that is a diaphragm, which is secured to a sleeve and adapted axially displaceable on the drum driving spindle to be deformed by the displacement of thesleeve along the spindle of the drum in a manner such as to cover the bottom opening in its entirety, when the sleeve assumes its lower position. Whereas when the sleeve assumes its upper position, the valve body has so small a diameter that the material may pass between the valve body and the inner surface of the drum or the material remaining in the drum without building any vaults.

According to one embodiment of the cut-off valve, a sprayer screen is arranged on the sleeve above the diaphragm' The screen is adapted, in the filling of the drum with material, to throw a portion at least of the filling mass directly out against the inner surface of the drum, Without the filling material first touching the diaphragm.

The invention will be described in more detail with reference to the accompanying drawings, which illustrate a centrifugal drum provided with a cut-off valve according to the invention and in which:

FIG. 1, is a vertical view of a centrifuge partly in section provided with a valve according to the invention;

FIG. 2, is a fragmentary view on an enlarged scale of a vertical view of the valve of the invention;

FIG. 3, is a plan view of the valve;

FIG. 4, is a fragmentary section through a portion of the diaphragm and its supporting plates in an expanded position of the diaphragm;

FIG. 5, is a fragmentary section of the diaphragm, illustrating its folded position; and

FIG. 6, is an axial section through a modified construction of the diaphragm.

According to the drawing a centrifuge provided with the invention comprises a centrifugal drum or bowl I mounted with a driving spindle 2 extending axially into the bowl and a driving motor 3 for driving the spindle mounted on a frame consisting substantially of a girder system 5 arranged on feet 4. The cylindrical surface of the drum is perforated and provided on the inside thereof with a strainer cloth 6. It is covered by a cover 7 underneath of which an excavator-not shown in the drawing-is arranged for digging out the material gathered on a strainer drum in the form of a cylinder 8. At the bottom 9 of the bowl 1 are provided central outlet openings 10, through which the excavated material may fall downwardly and be discharged from the bowl. These openings are adapted to be closed by means of a cut-off valve in the form of a diaphragm 14, which is carried by a sleeve 11 rotatable with the driving spindle 2. The sleeve is provided at the top with a flange 12 and at the bottom with a cone 13 secured to the sleeve 11 and in which the diaphragm 14 is inserted. The sleeve 11 is axially slidable on the spindle and is carried by a roller 16 supporting the flange 12. The roller is arranged on an arm 15, which may have a vertical movement imparted thereto by a pneumatic cylinder 17, so that the sleeve 11 with the cone 13 is raised in a direction away from the opening into the position indicated by dotted or broken lines in FIG. 1.

As will appear from FIGS. 25, the diaphragm 14 consists of a circular disk of a flexible material, preferably rubber, which is braced by a number of radial struts 19, which are pivotally connected at one end with the cone 13, as at 18, and at the other end with levers or links 20 pivotally secured to the spindle 2. These links radially expand the diaphragm in response to downward travel of said :sleeve 11 and radially contract it inwardly in response to upward travel of said sleeve as hereafter described. The links 20 have one end thereof connected to a ring 24 movable axially on the lower large diameter portion of the spindle. When the sleeve moves upwardly the upward travel of the ring is limited by a stop 25 so the diaphragm is collapsed radially inwardly as shown in FIG. 2. In addition, the diaphragm is stiffened by means of rigidifying members comprising sector shaped supporting plates 21 radially arranged on the upper side thereof. These plates are riveted to the respective struts 19 and have a curved configuration with a concave lower side and form rigidified sectors on the diaphragm as illustrated in FIG. 3.

In the position shown in solid lines in FIG. 2, the diaphragm has a slightly conical shape with an apex portion circumferentially of said sleeve and a base portion thereof has so large a diameter that a peripheral marginal edge portion seats on a circular valve seat formed by the bottom 9 coaxial with the bottom opening or openings to cover the outlet openings :10 in their entirety. When the sleeve 11 is raised selectively in a direction away from its seat for opening the valve, the diaphragm is contracted radially inwardly so that the

parts

19, 20 and 21 will take the positions indicated by broken lines. The portions of the diaphragm lying between the sectors formed by the supporting plates 21 will thus be folded in the manner shown in FIG. 5. The concavity of the supporting plates imparts to the intermediate portions a tendency to flex inwardly. In its collapsed position, the diaphragm has a diameter small enough to permit the centrifuged material to pass out thrciugh the openings 10 without any risk of forming vau ts.

Another construction of the diaphragm and associated parts is shown in FIG. 6. In this construction the outer part of the diaphragm 22 is double-folded and stiffened by means of resilient insets of steel wires, for example, so as to bear with a resilient pressure in its closed position on the inner edge portion of the bottom 9 and to seat thereagainst, while in the open position it assumes the position indicated by broken lines in the figure.

As shown in FIG. 1, the valve device may be provided with a sprayer screen 23 secured to the sleeve 11. This screen is adapted, in the filling of the centrifuge, to throw at least a portion of the filling material out against the inner side of the centrifugal bowl during filling of the centrifuge. Consequently, the filling material does not hit the diaphragm 14. This arrangement is of particular advantage in connection with filling materials which are otherwise difiicult to distribute along the inner surface of the bowl 1.

What is claimed is:

1. In a centrifuge having a driven bowl having a bottom provided with a central discharge opening and circular valve seat coaxially with said central opening in said bottom, a driving spindle extending axially into said bowl, a sleeve axially slidable on said spindle, a valve member comprising a collapsible conical diaphragm having an apex portion mounted circumferentially of said sleeve for axial travel therewith and a base portion comprising a peripheral marginal edge portion movable radially outwardly of said sleeve selectively into a position seated on said circular valve seat, means for selectively axially displacing said sleeve axially on said spindle, means responsive to said axial displacement of said sleeve for contracting the diaphragm radially inwardly to uncover said discharge opening when the sleeve is moved in a direction away from said seat and for expanding the diaphragm and causing said edge portion to seat on said valve seat thereby to close said opening when the sleeve is moved axially in the opposite direction on said spindle, and said means responsive to said sleeve displacement being arranged internally of said conical diaphragm.

2. In a centrifuge having a driven bowl having a bottom provided with a central discharge opening and circular valve seat coaxially with said central opening in said bottom, a driving spindle extending axially into said bowl, a sleeve axially slidable on said spindle, a valve member comprising a collapsible conical diaphragm having an apex portion mounted circumferentially of said sleeve for axial travel therewith and a base portion comprising a peripheral marginal inner edge portion movable radially outwardly of said sleeve selectively into a position seated on said circular valve seat, means for selectively axially displacing said sleeve axially on said spindle, means responsive to said axial displacement of said sleeve for contracting the diaphragm radially inwardly to uncover said discharge opening when the sleeve is moved in a direction away from said seat and for expanding the diaphragm and causing said edge portion to seat on said valve seat thereby to close said opening when the sleeve is moved axially in the opposite direction on said spindle, said means responsive to said sleeve displacement being arranged internally of said conical diaphragm, and angularly spaced rigidifying members fixed angularly spaced on said diaphragm forming rigidified sectors thereon corresponding to said members.

3. In a centrifuge according to claim 2, including means pivotally connecting said rigidifying members to said sleeve.

4. In a centrifuge according to claim 2, in which said rigidifying members are arcuate in cross-section to assist in forming radially extending folds in said conical diaphragm when said valve member is moved radially inwardly toward said sleeve.

5. In a centrifuge according to claim 2, in which means responsive to said axial displacement of said sleeve comprises a plurality of angularly spaced links disposed extending radially inwardly toward said spindle, means pivotally connecting one end of each link to the diaphragm and means pivotally connecting the opposite end of each link to a point adjacent the periphery of said spindle, and means allowing the last-mentioned pivot means to travel axially a relatively lesser extent than said sleeve travels when displaced and in response and correspondence in time and direction with said sleeve displacement.

References Cited in the file of this patent UNITED STATES PATENTS 706,441 McLaughlin Aug. 5, 1902 2,037,655 Roberts Apr. 14, 1936 2,890,716 Werder June 16, 1959