US2669668A - Magnetically driven centrifugal pump - Google Patents

Description

b 16, 1954 G. J. oKULlTcH ET Al.

MAGNETICALLY DRIVEN CENTRIFUGAL PUMP Patented Feb. 16, 1954 MAGNETICALLY lDRIVEN oENrnIFUoAL PUMP lGeorge Joseph Okulitch, Igor 'Vasilivich AZozulin,

Vladimir Joseph .Okulitchrand George :M. Molko", Vancouver, British Columbia, Canada, as- ;signors to Hermag PumpsfLtd., Yanoouver, Bri-tish Columbia, Canada, acorporation of British Columbia Application February V'28, 11949v Serial Nor-78,7112

Claims priority, application `Canada. `February 57, .194,9

3'Claims. l

This invention pertains to centrifugal pumps of a type useful to the chemical and dairy industry.

In both the chemical and dairy industries, there are many installations Where it is desired to pump liquids in which the liquids are either extremely corrosive or easily contaminated by foreign matter. .Such foreign material may be trapped inthe pump or enter from outside sources. Consequently, it is'advantageous to these indusgland.

being pumped.

.chamb er.

4ing chamber.

The'nove1 pumpernbodying the advantages Vset out .above consists of gtwocharnbers, one of which may be hermetically. sealed withjthe exceptionof an inlet and outlet for ythe fluid to vbe pumped, and arotor carrying pumping vanes. The other chamber containsa rotor `dri-ven by an external means of the rotor. .As stated above, there Lis no mechanical couplingbetween :the -tivo rotors and the rotation of thefunctional .or pumping rotor b y the mechanical drivenrotolr :is accom- A wall of non-magnetic ,material tries and to others to utilize a pump in which the plished by magnetic -attractionbetrveen vmagnets functional portion of the pump may be hermetidisposed circumferentially varound the ,face 4of cally sealed to prevent entry of foreign materials each rotor. or, on the other hand leakage of the material forms the dividing 'line between gthe two cham- .from the pump. To accomplish this in the past, it 1.-, bers kand carries stub axles .which act as suphas always been extremely difficult, due to the ports for jthe two rotating Lmembers, which are necessity of providingopenings -in the functional arranged to rotate freely in a, parallel relation-v portion of the pump for the .entrance of the shafts Ship to each other. essential to drive the operating parts. ln order With these and incidental vobjects'n View, the to adequately seal these functional. openings, it g() invention includes certain-novel features of conhas been necessary to resort to packing glands SIUC'UiOn and COmbineiiOn Of paris. the essen-- involving many different structural shapes and iinl elements 0f Which are Sei? OIth in 'the en incorporating materials of .construction of an penied ClaiInS and 2 preferred form and ern-- expandable nature t0 retard leakage through the bOCmSnt 0f Which iS hereinafter 'described With. reference to the drawings which accompany and. Furthermore in the dairy industry in particulfOlin Dari? 0f this SDeCiCeiOn. Yln the .drawingsi lar, where a large quantity of perishable liquids Figure l .iS a Side eievaiin in SCi7i0n ShOWins such as milk must be handled, it has Vbeen exthe inVeniiiOntremely difficult to maintain material handling Figllie 2 iS e SeCiJiOnal view along the liner equipment suiiciently clean in order to avoid 2 2 0f Figure 1- contamination from bacteria. The normal clean- Figure 3 iS an end eleVaiOn ShDWing the dis-- ing operationsV seldom remove all traces of the Charge @Ondniii 'lending from thepllmpmilk from the operating parts .and consequently Figure i is 2L Side elevation in seton of an: there is the constant danger of bacterial growth alternate form of the invention- .occurring in the unc'leaned portion of theequip- Referring 110W .i0 Figure `1 a base 1.0 0f any ment. In addition, the conventional sealing Suitable Size and Shane SUDDOYS the nOVel Dump glands used in pumps must be lubricated which The pump is divided into two main portions, a introduces the possibility of contamination of Compartment Il 011th@ righi/.hand Side ofiieure the milk by the lubricating materials and also 1 'Containing the DOSiiVely driven IQiOl' and e portions of the packing gland which may'beoome functional 01 Operaties C0miernment I2 Shown separated and flow into the milk, .or other liquid 40 0n the left hand Side Cf Figure l The UWG COmpartments VIl and i2 are .separated "by a plate r1She present invention is designed .to .overcome S- The plate i3 iS `.Circular in vSection and is the disadvantages discussed above by providing J'Oned ai iiS periphery'by aflanged ring I4. The a centrifugal pump with a pumping chamber method 0f J'Oinins the Circular .plate L3 on the which may be hermetically sealed to prevent the flange ring i4 iS 110i pertinent .t0 .the ,invention undesired flow of liquid either into or out of the and any Conventions-1 Construction may be fol- Another distinguo@ feature of the lowed and in some cases the plate I3 and the pump of .this invention is the elimination ofl any flange i4 @Ould be made integrally. The plaie mechanica connect-,ion between the pumping 10 i3 should be constructed from a material which tor and the means for rotating the rotor. The 50 Will 110i aci as 'a Shield i0 magnetic flux. For elimination of lany mechanical coupling between this reason iron 01 mild Steel Should ynot be used the operating parts of the pump removes 3,11 the and it is preferable to ruse Anon-ferrous metals or disadvantages encountered inconventional pumps SieinleSSlSieel- In CaSeS Where liquidS are being Where-.a meenenieieivehaii .einen thepnxpphandled which .are corrosive or where .the mond might be contaminated by specific metals 1t aeoaoos would be advisable to use materials which would neither be attacked by the liquid nor be contaminating in nature.

The compartment Il is formed on one side by the wall I3 and on the other side by a housing I5 which is of generally hemispherical shape and has a peripheral ange I6. An opening I'I is provided in the housing I5 for the passage of the driving shaft I8 which is supplied with suitable bearings I9.

The compartment I2 shown on the left hand side of Figure 1 is bounded on one side by the wall plate I3 and has two outer housings or casings the internal of which is shown at 20 and an external housing at 2I. The internal housing 20 is of stepped cross section and is circular in nature the peripheral edges contacting the plate I4. A spider of relatively heavy construction shown at 22 is provided with an opening 23 in the centre thereof through which passes a conduit 24 leading through the external and internal casings 2I and 20 of the compartment I2. The function'of the pipe 24 is to lead fluid to be pumped directly into the vortex of the pump.

The spider and pipe 24 function to hold the two casings securely in place and prevent leakage from the compartment I2.

The plate I3 carries two coaxial stub shafts shown at 25 extending normally from approximately the centre of the plate into each compartment. The shafts 25 may be welded or secured by any other conventiona1 means to the Vplate I3. Disposed for rotation on the shafts 25 are a pair of disc-shaped rotors 2B and 2l.

The rotors are mounted for free rotation on the shafts which are of suiicient length to accommodate the rotors.

The rotor 26 is located in the chamber II and is connected by a coupling 28 to a drive shaft I8. The rotor 25 and the coupling are constructed lin such a manner that a certain amount of longithe chamber I2. The rotor 25 has a hub SI and a web portion 32 communicating with a peripheral portion 33 of considerable width. The rotor 2l likewise has a hub 34, a web portion 35 and a peripheral portion 3G. It will be noticed that the rotor 2l is mounted in a reverse manner to the rotor 25, otherwise the construction is similar.

The rotor 25 is coupled to the shaft I8 and is rotated by the application of force transmitted through the shafting I8 from any outside agency, suchv as an electric motor. For convenience in describing the operation of the pump, the rotor 26 will hereinafter be called the driving rotor. The other rotor 21 which carries the vanes 3e is not mechanically connected to the driving rotor but is rotated by magnetic attraction with the first mentioned or driving rotor. Hereinafter, the rotor 2l will be referred to as the driven rotor. Mounted inthe peripheral portions 33 and 35 of the driving and driven rotors, are a series of horseshoe or U-shaped magnets arranged as in the form of an annulus as at 3l. These magnets are tted into pockets or openings 38 in the peripheral portions and secured in place by any con- Vventional means 4such as studs and bolts shown generally at 39 in Figure 1. Both the driving and driven rotors are made of non-magnetic and preferably corrosion resistant materials, and the permanent magnets are arranged symmetrically around the peripheral portions. The spacing between adjacent magnets is made approximately equal to the spacing between the poles of a single magnet. The magnets are arranged in such a manner that the north pole of one magnet is adjacent to the south pole of the magnet lying beside it and similarly around the peripheral portion. The arrangement of the magnets in both rotors is identical. Consequently the two rotors being mounted parallel to each other with the poles of the magnets in each rotor facing each other, the attractive forces between the north pole of a magnet in one rotor and the south pole of the magnet in the other rotor will be extremely high and positive rotation of one rotor will therefore cause rotation of the other. The mutual magnetic attraction of the magnets is at its maximum when the north poles of one rotor are in juxtaposition to the south poles of the other rotor. Should a displacement occur, so that for example the north pole of one rotor is beginning to approach the north pole of the other rotor, a repulsion will develop between the like poles which will tend to push the pole bacx to its original advantageous position opposite the south pole. This is obviously the natural position which the two rotors will assume, unless forcibly held in a different position. Therefore, not only the mutual magnetic attraction between opposite poles of the magnet is utilized in this device, but the repulsion between like poles is used as well. This arrangement of the magnets considerably increases the effectiveness of the couplings.

Thevanes 3d being secured to the driven rotor will rotate with the rotor and fluid entering through the conduits 2d into the centre vortex created by the rotating varies, will be increased in velocity and pressure and leaves the compartment through the conduit `lill which extends through the outer casingZI and the inner casing 2G of the compartment I2.

It will be obvious from the foregoing description that by means1 of this apparatus, fluid may be conveniently pumped without danger from corrosive action from the fluid or contamination of the fiuid due to dirt entering the pumping chamber. The pumping chamber I2 is, for practical purposes, hermetically sealed, but may be easily disasssembled for cleaning.

If for any reason the rotor of the driven rotor meets temporarily with excessive resistance, and a complete stoppage of the driven rotor or a relative slipping between the two magnet assemblies occur, then the time average of the force of attraction between the driven and the driving rotors will diminish. When this condition occurs, it is desirable to slow down or stop the rotation of the driving rotor until the most advantageous, natural position between the magnet assemblies is reestablished. In the present device, the diminution of the time average of the force of attraction is utilized to automatically stop the rotation of the driving rotor until such time as the attractive force will :again increase and the rotation of both rotors will again be in step.

As previously described, the driving rotor 26 is loosely mounted on the step shaft for longitudinal movement with the coupling 23 along the driving shaft I 8. As the magnetic coupling is lost, a spring III mounted upon the plate I3 tends to overcome the diminished magnetic attraction and forces the driving rotor 26 outwardly along the shaft. A ilange l2 on the coupling 28 engages spring arm :is co-operating with a micro-switch 44. Consequently when the magnetic attraction decreases and the driving rotor tends to move longitudinally on the shaft Is as a result of the action of the spring 4i, the micro-switch 44 is actuated and disconnects the source of power turning the shaft i8. Immediately that the magnetic attraction between the driving and driven rotors is resumed and the magnetic attraction is suiiicient to overcome the eifect of the spring 4I, the driving rotor moves inwardly and the microswitch again makes contact with the source of energy turning the shaft I8 and the normal mechanical force is again applied to the driving rotor. This device is suitable for overload conditions which might cause damage to the machine.

An alternative construction is illustrated in Figure 4 which provides greater rigidity o1" the stub shafts and thus makes the pump more suitable for larger capacity and by permitting the use of a thinner separating wall or membrane considerably increases the mutual magnetic attraction of the magnets in the driving rotors which results in greater mechanical efficiency of the driven rotor.

For sake of clearness in description, Figure 4 illustrates only the essential features of the invention. It will be observed that the plate I3 is secured and functions in a similar manner to that disclosed in the previous embodiment of the invention. rlhe rotors 26 and 21 are also constructed in a practically similar manner to the previously described rotors. The principal difference between this embodiment and that previously described, is that the driving rotor 26 which is supported on the stub shaft 25 is rotated by a longitudinal shaft 45 operating through a set of gears of suitable design 46 rather than by attachment to the prolongation of the central longitudinal axis. The stub shaft 25 is extended and is supported by a thrust bearing 41 and adjusting means 46. The adjusting means 48 are provided in order to provide for longitudinal adjustment of the stub shaft 25. Discs 49 are aiixed rigidly to plate I3 and stub shafts 25 are in turn secured to the discs 49. The stub shaft 25 and the discs may be constructed as a unit and xed rigidly to the plate I3.

Although the pump has been described without reference to any speciiic capacity, it will be obvious to those skilled in the art that it is merely a matter of arrangement of structural dimensions to produce any desired capacity.

The most outstanding advantage accruing from the operation of the pump described above is that the operating chamber may be made from corrosive resistant materials or materials which will not contaminate the uid and may be easily cleaned. In addition, of course, to the structural materials which may be employed in the pump, the fact that there is no mechanical shaft extending into the pumping chamber itself is of material advantage. All packing glands are eliminated and any contamination which might occur through the entry of oil or packing material into the fluid is avoided. In addition of course, the quite common problem in pumping 6 corrosive fluids is avoided where the fluid attacks the packing gland and causes leakage.

We claim;

1. A magnetic coupling comprising a wall of non-magnetic material, rotors disposed on each side of said wall in substantially xed spaced relationship and each mounted for free coaxial rotation about a stationary stub shaft extending normally from the dividing wall and integral therewith, an annulus or" permanent magnets disposed on the adjacent faces of each rotor at equal distances from the axis of rotation, means to rotate positively one of the rotors, magnetic attraction between the rotors causing synchronous rotation of the other rotor by said positively driven rotor, said magnets having axially extending, radially aligned poles and alternate magnets being oppositely directed.

2. In the device disclosed in claim 1 wherein the permanent magnets are U-shaped and are spaced apart a distance equal to the distance between the poles.

3. A magnetic coupling comprising a wall of non-magnetic material, a centrally disposed shaft integral with and extending from both sides of said wall, disc-shaped rotors in substantially ixed spaced relationship on each side of said wall and mounted for coaxial rotational motion on said shaft, an annulus of permanent magnets located on adjacent faces of said rotors near the peripheral edges thereof at equal distances from the shaft axis, means to positively rotate one of said rotors, magnetic attraction between the rotors causing synchronous rotation of the other rotor, and means responsive to asynchronism between said rotors to control the driving means so as to maintain the rotors in synchronous rotation, said means comprising a spring normally urging one of said rotors away from the other, the magnetic attraction between the two discs preventing the spring from moving the one rotor away from the other but allowing the spring to move one rotor away from the other when the magnetic attraction is disturbed, said motion opening a switch in an electric circuit to stop the means supplying power to positively rotate said one rotor.

GEORGE JOSEPH OKULITCH. IGOR V ASILIVCH ZOZULIN. VLADIMIR JOSEPH OKULITC-i. GEORGE M. VOLKOFF.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,300,778 Cornwell Nov. 3, 1942 2,422,040 Rader June 10, 1947 2,452,945 McCabe Nov. 2, 1948 2,460,015 Jones Jan. 25, 1949 2,471,753 Johnston May 31, 1949 2,481,172 Staggs ept. 6, 1949 2,506,798 Lilja May 9, 1950 2,506,886 Okulitch May 9, 1950 2,568,348 McCauley Sept. 18, 1951 FOREIGN PATENTS Number Country Date 142,140 Great Britain Dec. 16, 1920 192,618 Great Britain Feb. 8, 1923

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