US3459308A - Vibrating centrifuges - Google Patents

Description

Aug. 5, 1969 F. H. coucH VIBRATING CENTRIFUGES 4 Sheets-Sheet 1 Filed Sept. 5. 1965 INVENTOR:

Fmwc 15 Coven A rmlm Y 5, 1969 F. H. COUCH 3,459,308

VIBRATING CENTRIFUGES Filed Sept. 5, 1965 4 Sheets-Sheet 2 INVENTOR:

F101 we 1.: ll. Coucn Arro Riv: Ys

F. H. COUCH VIBRATING CENTRIFUGES Aug. 5, .1969

4 Sheets-Sheet 3 Filed Sept. 5, 1965 INVENTORZ FRANeI: H COUCII ArfORlVEY Aug. 5, 1969 F. H. coucH VIBRATING CENTRIFUGES 4 Sheets-Sheet 4 Filed Sept. 5. 1965 INVENTORZ Y #.e u u a W, A VI 8 I a M R F United States Patent us. (:1. 210-370 Claims ABSTRACT OF THE DISCLOSURE The invention resides in a centrifuge having a divergent basket which is vibrated torsionally, i.e. circumferentially, instead of axially as hitherto, whereby to avoid the incidence of cross-loading in the axial direction.

The present invention relates to vibrating centrifuges which incorporate a divergent centrifuge basket to which mixtures of solids and liquids are continuously fed and from which the discharge of the centrifuged constituents is continuous. Hitherto such centrifuge baskets have been vibrated in the axial direction, i.e. in the direction of the axis of rotation of the basket, giving rise to relatively large axially directed thrust loads.

The present invention resides in a vibrating centrifuge in which the vibration is torsional, i.e. circumferential, instead of axial, whereby to avoid the incidence of undue thrust loads in the axial direction.

The torsional vibration being circumferential in character gives rise to the application to the centrifuge of force in a circumferential direction which reverses at the rate of the period of vibration.

Thus a solid element in the centrifuge basket will be subject to a reversing circumferential force tending to displace it back and forth in the circumferential direction. At the same time rotation of the centrifuge will give rise to the application to the solid element of centrifugal force acting radially outwardly and a component of this force acting along the axially divergent surface of the basket will tend to displace the solid element axially towards the discharge end of the basket.

The net result of the two forces will be a tendency for the solid element to move in a zig zag path towards the discharge end of the basket, thus enhancing the rate of discharge of solids from the basket as compared with the rate of discharge that would be achieved as a result of rotation alone. Because the reversing force which results from torsional vibration is circumferential it does not give rise to the relatively large axially directed thrust loads which had resulted from the axial vibration of centrifuge baskets.

A centrifuge according to the present invention may comprise a divergent centrifuge basket mounted on a shaft, a rotating mass angularly fixed to the shaft at a positioned spaced from the basket, means for applying a substantially constant torque to the shaft to rotate the same and means for applying an intermittent or oscillating torque (hereinafter referred to as a vibratory torque) to the shaft to set up torsional vibration.

Furthermore, a centrifuge according to the present invention may comprise a divergent centrifuge basket mounted on a shaft, a rotating mass angularly fixed to the shaft at a position spaced from the basket, means for applying a substantially constant torque to the shaft at one locality thereof and means for applying a vibratory torque to the shaft at another locality thereof adjacent either to the basket or to the rotating mass. The constant and oscillating torques can be applied to the shaft at the same locality provided that there is some resilience in the driving means transmitting the constant torque to the shaft.

The centre of gravity of the rotating mass should of course be substantially coincident with the axis of rotation of the shaft as in the case of an engine flywheel.

Preferably the vibratory torque applied to the shaft i such as to give rise to vibration at a period close to the natural period of torsional vibration of the rotatable assembly.

The vibratory torque may be applied to the shaft by any suitable means, eg, electrical, mechanical, pneumatic or hydraulic. The vibratory torque may be positive tending to drive the shaft, or negative tending to decelerate the shaft or it may be alternately positive and negative.

For applying a vibratory torque to the shaft electrically a rotor comprising an unwound laminated assembly with salient poles may be secured to the shaft and arranged within a wound stator adapted to produce a magnetic field providing one or more localities of maximum intensity so as to apply alternating positive and negative torque to the poles of the rotor as they pass therethrough. The stator may be wound to provide one or more localities of maximum magnetic intensity which may be stationary, as when generated by direct current, or rotating, as when generated by alternating current.

Hydraulic means for applying vibratory torque to the shaft may comprise a hydraulic casing fixed to said rotating mass, at least one vane extending inwardly from the periphery of said casing, a rotor within the casing, means for rotating the rotor, and at least one vane extending outwardly from the rotor so that on relative rotation of the rotor and casing said vanes clear one another by only a small margin.

Vibratory torque may be set up mechanically by an arrangement for repeatedly varying the inertia of the rotating system as for example by means of rotating out of balance weights mounted on said rotating mass.

The invention is further described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 illustrates diagrammatically a centrifuge to which vibrating torque is applied electrically;

FIG. 2 is an end view illustrating schematically an electrical means for applying the vibrating torque;

FIG. 3 is a view similar to FIG. 1 illustrating a centrifuge to which the vibrating torque is applied mechani cally;

FIG. 4 illustrates a part of FIG. 3 in end view;

FIG. 5 is a view similar to FIG. 1 illustrating a centrifuge to which vibrating torque is applied hydraulically; and

FIG. 6 is a sectional view on line VIVI of FIG. 5.

With reference to FIG. 1, a divergent centrifuge basket 10 is mounted on a shaft 11 journalled in bearings 12, 13 which are capable of sustaining end thrust. The centrifuge basket is fed with slurry by means of a pipe 9. A rotating mass or flywheel 14 is secured to the shaft 11 at a position spaced from the centrifuge 10. A substantially constant torque is applied to the shaft 11 to drive the same by means of a motor 16 and a belt and pulley drive 17, 1-8, 19.

Vibratory torque is applied to the shaft by means of a rotor 20 which revolves within the wound stator 23. The

rotor 20 is of laminated construction formed with salient poles 21 and is secured to the right-hand end of the shaft 11 near to the rotating mass 14. The rotor 20 rotates within a wound stator 23. The stator 23 is formed over its whole circumference with slots 24 containing coils as illustrated in one of the slots 24a.

The stator is wound to produce poles of alternative polarity, providing a magnetic field with localities of maximum magnetic intensity. In one form of the invention the stator winding is adapted for direct current to produce a stationary magnetic field. In another form of the invention the stator winding is adapted for alternating current, preferably polyphase, to produce a rotating magnetic field of which the direct axis of reluctance is indicated at 26 in FIG. 2 and the quadrature axis of reluctance is at 27. When the stator is supplied with alternating current it is preferably wound to produce a magnetic field which rotates in a direction opposite to the direction of rotation of the rotor 20.

Rotation of the shaft 11 and the rotor 20 attached thereto will produce relative movement of the rotor with respect to the magnetic field created by the stator 23. This results in forces which cyclically tend to accelerate and decelerate the rotor 20 as it rotates under the influence of the motor 16, thus imparting torsional vibrations in the movement of the shaft 11 and basket 10.

Because the vibration applied to the shaft 11 is torsional the end thrust applied to the bearings 12, 13 as a result of the vibration is virtually nil.

The centrifuge illustrated in FIG. 3 is similar to that of FIG. 1 except that the torsional vibration is applied mechanically. In the arrangement of FIG. 3 a rotating mass 34 has two diametrically opposed planet gears 36 mounted thereon in mesh with a sun wheel 37 mounted on the rotating mass 34 concentrically with the shaft 11.

The planet gears 36 carry out of balance weights 38 whose eccentricities are disposed at 180 to one another. When the shaft 11 is rotating the ring gear carried by the mass 34 will rotate the planet gears 36 and their out of balance weights 38 to result in repeated variation in the inertia of the rotating system and thus to produce torsional vibration.

In the arrangement illustrated in FIG. 3 the sun wheel 37 is provided with a pulley 40 driven by a belt 41. This enables the sun wheel to be independently rotated from a separate variable speed motor to vary the frequency of the torsional vibration which results from rotation of the out of balance weights 38.

The centrifuge of FIGS. and 6 is similar to that of FIG. 1 except that the torsional vibration is applied hydraulically. A hydraulic casing 45 is secured to the right-hand side of a rotating mass 46 fixed to shaft 11 and has vanes 47 extending inwardly from its internal periphery. A rotor 48 is mounted on a shaft 49 which is journalled in a bearing opening in the right-hand end of shaft 11 and in a bearing opening in the casing 45. The rotor 48 has vanes 52 extending outwardly so that on relative rotation of the casing 45 and rotor 48 the vanes 47 and 52 clear one another by only a small margin. As the vanes 47 and 52 are rotated relative to each other, resistance to rotation of the basket and shaft 11 is produced when the vanes become aligned with each other, since at that point the fluid ahead of the vane 52 must pass through the small clearance space between the vanes. A lesser resistance to rotation exists when the vanes 47 and 52 are out of alignment and the fluid has a relatively large passage across the vane 52. This fluctuating resistance to rotation will set up torsional vibration of the rotating mass 46 and thus of the shaft 11 and basket 10. Variations in the frequency of the decelerative force produced by the hydraulic fluid may be achieved by driving the rotor 48 by a belt 50 and pulley 51 connected to shaft 49.

I claim:

1. A vibrating centrifuge comprising a divergent centrifuge basket, a shaft supporting said basket, means for applying a substantially constant torque to the shaft to rotate the same, a rotating mass angularly fixed to the shaft with its centre of gravity substantially coincident with the axis of rotation of the shaft, a hydraulic casing fixed to said rotating mass, at least one vane extending inwardly from the periphery of said casing, a rotor within the casing, means for rotating the rotor, and at least one vane extending outwardly from the rotor so that on relative rotation of the rotor and casing said vanes clear one another by only a small margin.

2. In a vibrating centrifuge, a divergent centrifuge basket, means for rotating the basket, and means for vibrating the basket torsionally instead of in the direction of the axis of rotation, said two means being effective to rotate and vibrate the basket concurrently.

3. In a vibrating centrifuge, a rotatable assembly including a divergent centrifuge basket, a rotatable shaft supporting the basket, means for rotating the basket, and means for applying a vibratory torque to the rotatable assembly at a period close to its natural period of torsional vibration, said two means being effective to rotate and vibrate the basket concurrently.

4. A vibrating centrifuge comprising a divergent centrifuge basket, a shaft supporting said basket, a rotating mass angularly fixed to the shaft at a position spaced from the basket with its center of gravity substantially coincident with the axis of rotation of the shaft, means for applying a substantially constant torque to the shaft at one locality thereof and means for applying a vibratory torque to the shaft at another locality thereof adjacent to one of the basket and the rotating mass, said two means being effective to rotate and vibrate the basket concurrently.

5. A vibrating centrifuge comprising a divergent centrifuge basket, a shaft supporting said basket, a rotating mass angularly fixed to the shaft at a position spaced from the basket with its center of gravity substantially coincident with the axis of rotation of the shaft, means for applying a substantially constant torque to the shaft to rotate the same and means for applying a vibratory torque to the shaft to set up torsional vibration, said two means being effective to rotate and vibrate the basket concurrently.

6. A vibrating centrifuge according to claim 5 comprising a rotor secured to the shaft and formed as a laminated assembly with salient poles, and a wound stator surrounding said rotor, the winding of the stator being adapted to produce a magnetic field providing at least one locality of maximum intensity to apply alternating positive and negative torque to the poles of the rotor as they pass therethrough.

7. A vibrating centrifuge comprising a divergent centrifuge basket, a shaft supporting said basket, means for applying a substantially constant torque to the shaft to rotate same and hydraulic means for applying vibratory torque to the shaft, said two means being effective to rotate and vibrate the basket concurrently.

8. In a vibrating centrifuge, means for rotating a rotatable assembly in a given direction; said rotatable assembly including a divergent centrifuge basket, a rotatable shaft supporting the basket and means for vibrating the rotatable assembly torsionally by varying its moment of inertia during rotation thereof.

9. A vibrating centrifuge comprising a divergent centrifuge basket, a shaft supporting said basket, a rotating mass angularly fixed to the shaft at a position spaced from the basket with its centre of gravity substantially coincident with the axis of rotation of the shaft, means for applying a substantially constant torque to the shaft to rotate the same, out of balance weights rotatably mounted on said rotating mass and means for causing rotation of said out of balance weights during rotation of said rotating mass, thereby varying the moment of inertia of the rotating elements and imparting torsional vibrations thereto.

5 6 10. A vibrating centrifuge according to claim 9 com- 3,256,993 6/1966 Siepe et a1 210-370 prising a sun wheel mounted on the rotating mass con- 1,480,646 1/1924 Waller 68-174 X centrically With the shaft, and planet gears mounted on 2,104,283 1/ 1938 Webster 259-75 X the rotating mass and meshing With the sun wheel and angularly fixed relatively to said out of balance Weights. OTHER REFERENCES 5 German Printed Application No. 1,075,049, February References Cited 1960.

UNITED STATES PATENTS REUBEN FRIEDMAN, Primary Examiner 1,395,193 10/1921 Lindfinberg 3 J. L. DE CESARE, Assistant Examiner 2,861,691 11/1958 Linke et a1. 2l0-385 X 10 3,872,045 2/1959 Wirth et a1. 210-370 US. Cl. X.R.

3,069,016 12/1962 Kiesskalt et a1. 210-370 68173; 210-384

Images