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Publication numberUS3228597 A
Publication typeGrant
Publication dateJan 11, 1966
Filing dateOct 29, 1963
Priority dateOct 29, 1963
Publication numberUS 3228597 A, US 3228597A, US-A-3228597, US3228597 A, US3228597A
InventorsFlaherty Jr Robert J, Kimball John A, Smith Watt V, Walker Henry P
Original AssigneeFlaherty Jr Robert J, Kimball John A, Smith Watt V, Walker Henry P
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Centrifugal separator with integral motor
US 3228597 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

Jan. 11, 1966 H. P. WALKER ETAL 3,228,597

CENTRIFUGAL SEPARATOR WITH INTEGRAL MOTOR Filed Oct. 29, 1963 INVENTORS H. RWALKER, R J. FLAHERTXJI. J. A. KIMBALL, W. V. SMITH United States Patent 3,228,597 CENTRIFUGAL SEPARATOR WITH INTEGRAL MOTOR Henry P. Walker, 9412 Worth Ave., Silver Spring, Md.; Robert J. Flaherty, Jr., 632 Binstead Road, Glen Burnie, Md.; John A. Kimball, Ferry Point Road, Rte. 3, Box 371, Annapolis, Md.; and Watt V. Smith, 315 Old County Road, Severna Park, Md.

Filed Oct. 29, 1963, Ser. No. 319,897 11 Claims. (Cl. 233--24) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a centrifugal separating device which operates to separate constituents of different densities from a fluid stream which passes through the device and the method of making the centrifugal separator. More specifically this invention is an improvement over the centrifugal separator disclosed in (Navy Case No. 34,502) application Serial No. 253,233 filed January 22, 1963.

Application 253,233 disclosed a novel centrifugal separator incorporating in a single rotating element; a rotor of an induction motor, a pump for fluid power, a cylindrical space in which the fluid was exposed to a centrifugal field whereby the particulate matter was concentrated into a zone near the outer diameter of the space and exit means whereby the clean and dirty fluids were directed into separate channels.

When the fluid stream contains entrained matter, the stream may be said to be contaminated and the entrained matter may be said to be the contaminant. Often, it is desirable to separate the contaminant from the fluid stream to thereby provide a stream of pure or uncontaminated fluid. This separation can be effectuated by putting the fluid stream into rotation about an axis, whereby if the contaminant has a higher specific gravity than the pure fluid, it will tend to move radially outward from the axis of rotation leaving substantially pure fluid in the region immediately surrounding the axis of rotation. If the opposite condition should exist and the contaminant should have a lesser specific gravity than the fluid, thecontaminant would remain in the region immediately surrounding the axis of rotation and the pure fluid would move radially outward. This latter situation, however, is extremely unlikely since, in the vast majority of cases, the contaminant has a higher specific gravity than the fluid stream in which it is entrained.

To put a fluid stream into rotation to accomplish the aforementioned separation, a centrifugal separator is employed. Though there are numerous types of centrifugal separators, the basic principle of all of them is to put the fluid containing portion of the separator into rotation to achieve centrifugal separation of the fluid. A motor is usually used to create this rotation, and the motor is generally external to the fluid containing or rotary portion of the separator. Thus, a shaft, shaft seals, motor and shaft bearings are required to transmit the rotational power to the rotary portion of the separator. These bearings and seals are subject to leakage and other problems such as cleaning, lubricating, replacement and the like. These problems were solved by inventing an electric motor which dispensed with the conventional shaft and shaft bearings, but retained their function. This is accomplished by developing a hydrodynamic fluid of ambient fluid between the rotor and stator elements during operation of the motor. This particular electric motor is the subject matter of patent application Serial No. 225,943, (Navy Case No. 34,086) filed September 24, 1962 in the "ice joint names of two of the present inventors Watt V. Smith and Robert J. Flaherty, Jr.

The present invention utilizes the principles of the electric motor without conventional shaft and bearing and has as one of its objects, a substantial increase in the flow capacity and pressure capability.

Another object of this invention is the elimination of rubbing seals, increased flow of cooling water and better control of the quantity of cooling water by the use of a centrifugal pump discharge.

Still another object of this invention is the control of concentricity of the rotor and centrifuge tube with the elimination of unbalanced forces.

A further object of this invention is the control of the stator bore and outside diameter concentricity.

A still further object of this invention is the control of the parallelism of the axis of the stator bore with the axis of rotation.

Yet a further object of this invention is the locking of the stator in the housing while maintaining the accuracy of the stator alignment.

Yet a still further object of this invention is a method of securing the motor rotor to the centrifuge tube to insure the concentricity of the rotating components.

Other objects, advantages and salient features of the present invention will become apparent from the following description taken in connection with the accompanying drawings, the sole figure of which illustrates a longitudinal sectional view of a preferred embodiment of a centrifugal separator in accordance with the present invention.

Referring to the drawing, a centrifugal separator unit 50 is provided with an inlet conduit 46 and an outlet 42. The separator is housed within an open ended hollow cylindrical housing 6. The inlet end of the separator is provided with a base plate 35 which conforms generally in size and shape with the inside of the cylindrical housing 6. The base plate 35 is secured to the housing 6 by a plurality of bolts 37 and their associated lugs 36 which are brazed to the housing 6. The lugs 36 are faced square with the inside surface 44 of the housing 6. Gaskets, O-rings or other sealing rings may be provided at the interface between base plate 35 and housing 6 or between the base plate 35 and lugs 36. The inlet base plate 35 is provided with a central inlet aperture which is covered with the inlet conduit 40 which is attached to the base plate 35 by a flange 39 attached by bolts 38.

Right angled support pieces 5 are attached to the interior of the housing 6, preferably by brazing, and bored concentric and square with the housing 6. The right angled pieces 5 support a stator 2 of an electric motor by virtue of strips 4 adjacent to and nestled into the pieces 5. The four strips 4 are fastened to the outer diameter of the iron core 46 of the stator 2 and extend at one end beyond the end of the core 46. Set screws 7 through the housing 6 fix the strips 4 with relation to the right angled piece 5. Strips 4, preferably equally spaced in four places around the core 46, are an inovation to permit the establishment and maintenance of accurate reference surfaces without interference with the circulation of cooling fluid around the stator 2. In a preferred embodiment the strips 4 are corrosion resistant metal welded to the core 46. The strips 4 are concentric with the surface 44 and the ends square.

The stator 2 preferably conforms generally to the shape of the inside of the housing 6 and comprises a laminated core 46 and field windings 48 both of conventional 3 phase induction type motor construction. The stator is provide-d with a central internal cylindrical bore 54 having as its axis the longitudinal axis 56 of the unit. An alternating current three phase power source is supplied to the stator field windings 48 by conductors 43 which extend through a substantially fluid-tight stopper 45. When the windings 48 are energized by the power source, they create a rotating magnetic field in the stator laminations 46 which in turn causes rotation of the rotor 1 by means of induced current in a manner well known in conventional induction motors. The rotation of the rotor 1 causes a corresponding rotation of the centrifuge tube 17 which is affixed to it.

A cylindrical rotor member 1 of the conventional laminated induction type is freely mounted within the stator bore 54. The rotor is provided with a central internal cylindrical opening 58 with both the rotor and its cylindrical opening having as their central axis, the longitudinal axis 56 of the unit and therefore being coaxial with the stator bore 54. The outer surface of the rotor 1 and the inner surface of the stator 2, as defined by the walls of the bore 54, define the complemental working surfaces of the motor. The outer diameter of the rotor 2 is slightly smaller than the diameter of the stator bore 54 to thereby provide an annular clearance region between the stator and the rotor.

To permit the centrifugal separator to operate without sealing off the motor portion from the fluid stream, the rotor and stator members are protected from the deleterious effects of the liquid. The rotor 1 is coated on the external surfaces with an insulating and corrosion preventing material preferably in the following fashion. The external and internal cylindrical surfaces of the rotor are accurately machined or ground concentric. The surfaces are then roughened to the necessary degree to provide anchorage for the coating and cleaned by normal chemical methods. The exterior surface is coated with the interior cylindrical surface protected from being coated. The exterior surface is then finished to the required dimension using the interior cylindrical surface to maintain .concentricity. The interior surface of the rotor is then coated with the exterior finished surface protected. The interior cylindrical surface is finished using the exterior finished surface as a reference surface to maintain concentricity. The stator unit of the motor is finished and completely encapsulated in an epoxy resin or other similar material in the following manner to render it impervious and inert to the deleterious effects of the liquid. Strips 4- are welded to the exterior of the stator core 46 and then machined concentric with the bore 54 and the ends machined square. The exterior of strips 4 is protected while the stator core 46 is coated and the bore finished. Electrical windings are installed and the stator encapsulated. The stator bore is then machined and polished to provide a clearance between the stator bore 54 and rotor 1 equivalent to that normally utilized in a normal journal bearing, which is 0.0005 to 0.003 inch of clearance per inch of rotor diameter.

The cylindrical opening 58 of the rotor 1 is fitted with a centrifuge tube 17 whereby rotation of the rotor causes a corresponding rotation of the tube. The tube 17 is attached to the rotor in the following manner: a stop ring 18, brazed to tube 17, abuts against one side of the rotor 1. A sleeve 25 abuts against the other side of the rotor 1. Stop ring 18 and sleeve 25 are held in tight contact with the rotor by thrust bearings 26, 33, separated by a separator sleeve 27, and a clamping nut 34 screwed to the end of the tube 17.

The cylindrical tube 17 carries at its upper end a subassembly composed of a clean fluid impeller 12, a distance piece 13, a contaminated fluid impeller 14, and a bore ring 15. The parts of the subassembly are bonded together and fastened to the tube 17 by a threaded connection in the bore ring 15. A clean fluid inlet tube 16 is threaded into distance piece 13 and extends down into the undisturbed region in the centrifuge tube 17. The diameter of the clean fluid tube is substantially less than the diameter of the centrifuge tube 17.

The rotor 1, clean fluid impeller 12, distance piece 13, contaminated fluid impeller 14, bore ring 15, clean fluid tube 16, centrifuge tube 17, ring piece 18, sleeves 25 and 27, thrust runners 26 and 33 and nut 34 rotate together as a unit and form the moving portion of the assembly.

Surrounding the distance piece 13 and clean fluid impeller 12 is a ring 11 nestled on its inner end into a plate 23. Parallel to plate 23 is another plate 24 that terminates just short of bore ring 15 thus leaving a small space between the plate 24 and bore ring 15. The plates 23 and 24 and an exit plate 8, which conforms generally in size and shape with the inside of the housing 6, are secured together by bolts 19 and the assembly attached to the housing 6 by screws 22. The plates are separated by spacers 20 between plates 8 and 23 and a combination spacer tube 21 between plates 23 and 24. Sealing means such as gaskets or O-rings 60 can be provided at the interface between the housing 6 and the plates 8, 23 and 24.

A diffusor 10 is held in contact with the ring 11 by a spacer ring 9 supported by plate 8. Radial passages 49 in the spacer ring 9 allow fluids to flow radially outward.

The device is subject to a certain amount of endwise or axial thiust, particularly upon deenergization of the motor. The rotor 1, centrifuge tube 17 and all of pieces connected thereto can move axially because of the free suspension of the moving parts. However, to limit the amount of such axial movement, it is necessary to provide a thrust bearing means. The thrust bearing means includes the thrust runners 26 and 33 and a thrust bearing 28 having a pair of substantially planar surfaces which mate in spaced relation with the bearing surfaces of the thrust runners 26 and 33. The thrust bearing 28 has a central aperture 47 slightly larger diametrically than the sleeve 27. Since the thrust bearing 28 is of the double acting type in that it can absorb thrust in either axial direction, it is necessary that means be provided to insure proper orientation of the bearing at all times. To this end, a gimbal mounting means is provided which includes a gimbal ring 29 having screws 31 which support the thrust bearing 28 and a gimbal support 30 which supports the gimbal ring 29 by screws rotated degrees from the screws 31 shown. The gimbal support 30 is fastened to the base plate 35 by bolts 38. Passages 32 in the thrust bearing 28 allows clean fluid within the thrust bearing.

Operation Contaminated fluid enters the centrifuge tube 17 through the entrance 40 and passes up the tube under pump suction. Due to the rotation of the centrifuge tube 17 the fluid within the tube is set into rotation resulting in a radial centrifugal force being exerted. If it is assumed that a particle of mass m is rotating with an angular velocity w at a distance r away from the axis of rotation 56, the radial centrifugal force F acting on the particle is: F =mw r When the fluid stream contaminant is in the form of particulate matter having greater density than that of the stream, a particle of contaminant will have a mass greater than a particle of pure fluid and thus the radial centrifugal force for the particle of contaminant will exceed that for the particle of fluid. Thus, the contaminant will be forced through the fluid and toward the walls of the tube 17 by the centrifugal forces exerted. The total effect is to create a separated fluid stream with the contaminated portion immediately adjacent the walls of the tube 17 and the pure or uncontaminated portion in the central axial region adjacent the axis of rotation 56. The contaminated fluid impeller 14 takes its suction along the outside wall of the tube 17 and discharges it into the space between the two plates 23 and 24 from which it is discharged through the opening 41. The clean fluid impeller 12 takes its suction from the center of the tube 17 and discharges through the ditfusor 10 to the outlet 42. Ten percent of the clean fluid flows through the passages 49 to the space between plates 8 and 23 and thence is directed back to the motor space via the hollow spacer tube 21. The pure fluid thus directed to the motor housing forms a hydrodynamic film between the rotor and stator elements due to their relative rotation. The film radially supports and positions the rotor 1 and renders it completely out of contact with the stator 2 as the two rotate relative to each other. Clean fluid is also supplied to the thrust bearing 28 through the passages 32. The fluid introduced into the motor housing also acts as a coolant and cools the stator by flowing around the outside of it between the housing 6 and the core 46 and windings 48. The clean fluid exits through the space between bore ring and plate 24 and through the space between the base plate and flange 35 and 39 respectively and the nut 34.

It can be seen that the present device provides a compact, eflicient separator unit wherein only pure fluid circulates around the motor and the thrust bearing and wherein the separation is effected without the use of screens or filters which create clogging problems.

The present device can readily separate two immiscible liquids such as oil and water or a liquid from its entrained particulate matter, such as water and dirt. Consequently, the separator is particularly adaptable to marine applications. For example, the outboard water lubricated bearings of ships main propeller shafts are subject to heavy abrasive wear because the lubricating water is usually heavily contaminated. The present invention can be used to remedy such problems by attaching the separator unit 50 to the bearing housing with its outlet end 42 providing clean lubricating water.

It will be understood that various changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

What is claimed is:

1. A centrifugal separator unit comprising:

a housing means having an inlet and an outlet axially aligned along the central axis of the housing;

motor means mounted within said housing means and including a stationary stator member and a movable rotor member;

said stator member being affixed to the interior of said housing and having a central cylindrical bore generated about the central axis of the housing which defines an axis of rotation;

said rotor member having a cylindrical outer surface and a cylindrical central bore, both coaxial with the axis of rotation, said rotor outer surface being diametrically slightly smaller than said stator central bore and thus defining a small clearance region between said rotor and stator members;

a first hollow elongated cylindrical tube located within said rotor bore and aflixed to said rotor whereby rotor rotation also causes rotation of said first tube;

said first tube having its inlet end extending to said housing inlet and its discharge end terminating short of said housing outlet;

a second hollow elongated cylindrical tube coaxial with and diametrically smaller than said first tube and having its inlet end extending partially within the discharge end of said first tube and having its discharge end attached to means for increasing the quantity of fluid subjected to centrifugal action per unit time;

said first and second tubes being interconnected for rotation in unison;

electrical means for energizing said stator member to set up a rotating magnetic field therein which in turn causes said rotor member and the interconnected first and second tubes to rotate about the axis of rotation;

said rotor and tube rotation creating a centrifugal force 6 which acts upon the fluid stream within said first tube to centrifugally separate it by causing the contaminated higher density portion of the fluid to move radially outward from the axis of rotation toward the walls of said first tube while the pure lower density portion of the fluid remains at the central axial portion of said first tube, whereby the pure separated fluid enters and flows through the second tube; and

means for directing and distributing part of the pure fluid from the second hollow elongated cylindrical tube to the housing interior and clearance region between said rotor and stator members wherein said fluid forms a hydrodynamic film which totally supports said rotor member and maintains it spaced completely out of contact with said stator member while said rotor member is rotating.

2. A centrifugal separator unit as defined in claim 1 wherein strips affixed to the stator are nestled with right angle pieces for aflixing the stator to the interior of the said housing.

3. A centrifugal separating device comprising:

housing means having an inlet, an outlet, and a central axis which defines an axis of rotation;

motor means located within said housing and including relatively rotatable rotor and stator means having a narrow clearance region therebetween;

thrust bearing means including relatively rotatable thrust runner means and thrust shoe means;

a first tube coaxial with the axis of rotation and extending through and affixed to said rotor member for rotation therewith;

said first tube having one end extending to said housing inlet and its other end afiixed to a bore ring adjacent a discharge passage;

a second tube coaxial with the axis of rotation, smaller in diameter than said first tube, having one end extending partially within said first tube, and the other end fastened to an impeller means;

said first tube being attached to said thrust runner means and thus being rotatable therewith;

means at the inlet end of said first tube for a fluid stream to axially enter into said tube;

power means for energizing said motor to rotate said rotor member about the axis of rotation;

said rotor rotation causing a corresponding rotation of said first and second tubes and said thrust runner means, and also causing a centrifugal force to be exerted upon the fluid stream within said first tube to radially move the contaminated portion of the stream outward from the axis of rotation toward the walls of said tube thus leaving pure uncontaminated fluid in the axial region of the tube, said pure uncontaminated fluid subsequently entering said second tube while said contaminated fluid flows around the outside of said second tube;

means for diverting under pressure a portion of the pure fluid to said housing means where, due to the relative rotation between said rotor and stator memher, a hydrodynamic film is created which totally supports said rotor and provides the necessary radial positioning forces; and

where, due to the relative rotation between said thrust runner means and said thrust shoe means, a hydro dynamic film is created which absorbs axial thrust.

4. A centrifugal separating device as defined in claim 3 wherein said means for diverting fluid to said housing comprises a diflusor and passages through both a ring located between the ditfusor outlet and housing interior and plates defining the contaminated fluid discharge passage.

5. A centrifugal separator for separating constituents of diflerent densities in a fluid stream which passes through said separator, and for discharging said separated constituents from distinct point, said separator comprising, in combination:

a hollow housing member having closed end portions each provided with a central aperture one of which serves as an inlet and the other of which serves as an outlet, said inlet and outlet being axially aligned along the central axis of the housing member which also serves as the axis of rotation for the separator;

dividing means within said housing member having a central aperture in axial alignment with said inlet and outlet and dividing said housing into two separate chambers, the chamber between said inlet and said dividing means comprising a motor and thrust bearing housing and the said dividing means defining a fluid discharge passage for discharging fluid constituents;

motor means located Within said motor and thrust bearing housing and including rotor and stator means concentrically arranged about said axis of rotation with a smaller annular space between the rotor and stator mating surface;

a separating tube affixed to and extending through said rotor means with the axis of said tube being coaxial with said axis of rotation, the inlet end of said separating tube extending to said housing inlet and the discharge end of said separating tube terminating at the central aperture in said dividing means;

a discharge tube coaxial with and diametrically smaller than said separating tube, having its inlet end extending within the discharge end of said separating tube, and having its discharge end extending through the central aperture in said dividing means;

a pair of spaced thrust runners located within said motor and thrust bearing housing and aifixed to said discharge tube whereby rotor rotation causes said separating tube, said discharge tube, and said thrust runners to rotate in unison therewith;

a thrust shoe located in said housing and thrust bearing housing between said spaced thrust runners and mounted in nonrotatable mounting means whereby relative rotation can occur between said thrust shoe and said thrust runners, said thrust shoe and thrust runners defining a thrust bearing;

impeller means mounted at the discharge end of said discharge tube to increase the capacity and pressure of said centrifugal separator;

power supply means to energize said motor means to rotate said rotor about the axis of rotation;

said rotor rotation causing a centrifugal force to be exerted upon the fluid contained Within said separating tube to separate said fluid with the portion of the fluid having the greater density moving away from the axis of rotation and toward the walls of said separating tube and the portion of the fluid having the lesser density remaining in the axial region of said separating tube and subsequently flowing to said discharge tube;

means for supplying fluid from the discharge tube to the motor and thrust bearing housing wherein due to relative rotation between said rotor and stator, the fluid creates a hydrodynamic film which totally radially supports said rotor means during rotation thereof; and

wherein due to relative rotation between said thrust runners and said thrust shoe, the fluid creates a hydrodynamic film which absorbs axial thrust developed by said separator.

6. A centrifugal separator as defined in claim 5 wherein said thrust shoe mounting means is a gimbal-type mount permitting angular movement of said thrust shoe about the axis of rotation.

7. A centrifugal separator as defined in claim 5 wherein said means for supplying fluid to the motor and thrust bearing housing comprises passages through a ring between the housing and outlet and a passage through the said dividing means defining a fluid discharge.

8. A centrifugal separator as defined in claim 7 but further characterized by the said impeller means emptying into diffuser means from which the major portion of clean fluid passes out the outlet and a minor portion of clean fluid is diverted back to the motor and thrust bearing housing.

9. A centrifugal separator as defined in claim 5 but further characterized by strips fastened to said stator, said strips being nestled into right angled support pieces,

wherein the stator is affixed and accurately aligned within the housing. 10. A centrifugal separator as defined in claim 5 where- References Cited by the Examiner UNITED STATES PATENTS 1,534,604 4/1925 Terrneer 23347 2,467,742 4/1949 Hanno 233-47 X 2,519,971 8/1950 Le Clair 23346 X 2,688,437 9/1954 Monnet 233-46 X 3,080,106 3/1963 Ayling 31087 X 3,135,211 6/1964 PezZillo 31087 X 3,135,213 6/1964 Smith et al 31090 X M. CARY NELSON, Primary Examiner.

H. KLINKSIEK, Assistant Examiner.

Patent Citations
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6120261 *Aug 25, 1998Sep 19, 2000Saudi Arabian Oil CompanyElectric submersible pump with hollow drive shaft
US6213929 *Jul 12, 1999Apr 10, 2001Analytical Engineering, Inc.Motor driven centrifugal filter
US6261455Oct 18, 1999Jul 17, 2001Baldwin Filters, Inc.Centrifuge cartridge for removing soot from oil in vehicle engine applications
US6296765Oct 18, 1999Oct 2, 2001Baldwin Filters, Inc.Centrifuge housing for receiving centrifuge cartridge and method for removing soot from engine oil
US6428700Sep 6, 2000Aug 6, 2002Baldwin Filters, Inc.Disposable centrifuge cartridge backed up by reusable cartridge casing in a centrifugal filter for removing soot from engine oil
US6517475Sep 6, 2000Feb 11, 2003Baldwin Filters, Inc.Centrifugal filter for removing soot from engine oil
US6520902Sep 6, 2000Feb 18, 2003Baldwin Filters, Inc.Centrifuge cartridge for removing soot from engine oil
US6579218Sep 6, 2000Jun 17, 2003Analytical Engineering, Inc.Centrifugal filter utilizing a partial vacuum condition to effect reduced air drag on the centrifuge rotor
US6906440 *Jun 13, 2000Jun 14, 2005General Electric Canada, Inc.Bracket assembly having a plurality of plates for a dynamoelectric machine
US20080253907 *Sep 13, 2006Oct 16, 2008Lind Finance & Development AbCooling of Stator for Compressor
Classifications
U.S. Classification494/14, 494/35, 310/87, 494/60, 310/90, 494/38, 494/84, 494/83
International ClassificationB04B5/12, B04B5/00, H02K7/16
Cooperative ClassificationH02K7/16, B04B5/12
European ClassificationB04B5/12, H02K7/16