EP0337286A2 - Support moteur pour centrifugeuse - Google Patents

Support moteur pour centrifugeuse Download PDF

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Publication number
EP0337286A2
EP0337286A2 EP89106026A EP89106026A EP0337286A2 EP 0337286 A2 EP0337286 A2 EP 0337286A2 EP 89106026 A EP89106026 A EP 89106026A EP 89106026 A EP89106026 A EP 89106026A EP 0337286 A2 EP0337286 A2 EP 0337286A2
Authority
EP
European Patent Office
Prior art keywords
columns
mount
axis
mounting apparatus
accommodated
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP89106026A
Other languages
German (de)
English (en)
Other versions
EP0337286A3 (fr
Inventor
David Michael Carson
William Andrew Romanauskas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EIDP Inc
Original Assignee
EI Du Pont de Nemours and Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Publication of EP0337286A2 publication Critical patent/EP0337286A2/fr
Publication of EP0337286A3 publication Critical patent/EP0337286A3/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B9/00—Drives specially designed for centrifuges; Arrangement or disposition of transmission gearing; Suspending or balancing rotary bowls
    • B04B9/12—Suspending rotary bowls ; Bearings; Packings for bearings

Definitions

  • the present invention relates to a mounting apparatus, and in particular, to a mounting apparatus for a motor used in a centrifuge instrument.
  • the rotating member, or rotor forms part of a system that includes a motor or other source of motive energy, a drive shaft, and a rotor mounting device called a spud disposed at the upper end of the shaft on which the rotor is received.
  • a motor or other source of motive energy e.g., a motor or other source of motive energy
  • a drive shaft e.g., a motor or other source of motive energy
  • a spud disposed at the upper end of the shaft on which the rotor is received.
  • Violent motion and vibration are imparted to the rotor and the drive as reaches the critical speed. However, once the critical speed is reached the vibration is significantly decreased.
  • the drive is provided with some form of compliance mechanism which accommodates the forces imposed on the system as the rotor approaches and passes through its critical speed.
  • centrifuge drives have developed along two distinct paths related to the use of such drives in different centrifuge rotational speed regimes.
  • the drives for so-called lower speed centrifuges i.e., those having a speed less than twenty thousand revolutions per minute
  • the drives for so-called lower speed centrifuges typically use rigid shafts that are either directly coupled to a drive motor or are belt driven. Any compliance required for the stable operation of the instrument achieved by the use of elastomeric "shock" mounts. Design of drives for higher speed instruments using such mounts is difficult since the dynamics of the system is influenced by the entire mass supported by the shock mounts, and not merely the rotor mass.
  • Simple shock mounts cannot be used at higher speeds because of their low lateral and torsional stiffness compared to their pivot or moment stiffness.
  • the moment stiffness is dependent on compression or extension of the elastic shock mount whereas the lateral and torsional stiffness are determined by shear of the elastic mount.
  • the shear stiffness is usually only one third of the compressive stiffness. For this reason it is difficult to design critical speed out of the operating range from these three vibration modes.
  • United States Patent 4,511,350 (Romanauskas) relates to a suspension system for a centrifuge. Additionally, there is known a flexural pivot system sold by Bendix Aerospace in which springs are used to accommodate forces.
  • centrifuge drive that is able to allow significantly higher operating speed with simpler, more rugged, rigid shaft design. It is also believed advantageous to provide a drive having a motor mount that exhibits a relatively high lateral. vertical and torsional stiffness relative to the moment stiffness.
  • the present invention relates to a mounting apparatus preferably for a motor used in a centrifuge instrument.
  • the mount has a relatively high vertical, lateral, and torsional stiffness associated therewith as compared to its pivot or moment stiffness.
  • the mount includes a first and a second mounting member arranged in telescopic relationship with each other.
  • the members are attached to each other at any convenient location, preferably at the ends thereof.
  • Each mounting member is slotted to define a plurality of columns. The axes of some of the columns are parallel to the axis of the mount while the axes of other of the columns extend perpendicularly thereto.
  • each member has a pair of parallel and a pair of perpendicular columns.
  • the members are preferably cylindrical and when telescoped a parallel column of one of the members intersects at its midpoint with a perpendicular column on the other member at its midpoint.
  • Each of the columns is offset ninety degrees from the other about the periphery of the member.
  • the mount includes two members, one of which defines at least one column having an axis parallel to the axis of the mount while the other of the members defines a plurality of columns the axes of which extend perpendicular to the axis of the mount.
  • the columns are arranged such that a moment and a lateral force imposed on the members are accommodated by bending of predetermined ones of the columns while vertical and torsional forces are accommodated by compression or tension in at least predetermined ones of the columns.
  • the inner member takes the form of an elongated pin that is arranged parallel to the axis of the mount while the outer member is generally cylindrical in shape and slotted to define a plurality of columns that lie in a plane that is generally perpendicular to the axis of the mount.
  • a moment force is accommodated by bending of both the pin and the columns in the outer member. Lateral forces are accommodated primarily by bending of the columns in the outer member.
  • a typical centrifuge system includes a drive motor mounted to the superstructure of the instrument, a shaft extending from the drive motor into the chamber of the instrument, a rotor mounting device, also known as a "spud,” disposed at the upper end of the shaft, and a rotor mounted to the spud.
  • the system is acted upon by forces in the vertical direction z, lateral (or shear) direction r, the torsion direction ⁇ and the moment (or pivot) direction ⁇ , where these various directions are as indicated on the coordinate system shown in Figure 1.
  • the vertical forces act on the system along the z axis, the lateral forces act along any axis r lying in a plane P perpendicular to the z axis, the torsional forces ⁇ act angularly about the z axis, and the moment forces ⁇ act angularly about any axis r.
  • the motor mount 10 in accordance with a first embodiment of the present invention is structured such that the vertical (z), lateral (r) and torsional ⁇ forces are accommodated by compression or tension of columns, while the moment force ( ⁇ ) is accommodated by column bending.
  • a motor mount 10′ in accordance with an alternate embodiment of the present invention the vertical (z) and torsional ( ⁇ ) forces are accommodated by placing columns in compression or tension
  • lateral (r) force is accommodated by placing columns with a relatively high moment of inertia in bending
  • moment force ( ⁇ ) is accommodated by placing columns with a relatively low moment of inertia in bending.
  • the stiffness coefficient K ⁇ relatively much less than the stiffness coefficient associated with the other directions.
  • a mount generally indicated by the reference character 10 for supporting a drive motor 12 in an operational position on the interior of a centrifuge instrument.
  • the mount 10 has an axis 10A extending centrally therethrough which conveniently aligns along the z axis of the coordinate system of Figure 1.
  • the centrifuge instrument includes a structural plate 16 that forms part of the superstructure of the instrument housing.
  • a bowl, or chamber 18 is supported above the plate 16 by a stand-off ring 20.
  • the bowl 18 may be refrigerated, as indicated by the coils 24 affixed to the undersurface of the bowl 18.
  • the shaft 12S of the motor 12 projects into the interior of the bowl 18 and terminates in a mounting spud 26.
  • the spud 26 is conf igured to accept a rotating element, or rotor, 28 in a manner appreciated by those with skill in the art.
  • the area about the upper end of the motor 12 is closed by a thermally insulating heat shield 32 that has a flexible elastomeric boot 34 thereon.
  • the shield 32 is supported by a collar 36 having an IS enlarged abutment portion 36A which is secured to the plate 16 by screws 38.
  • a gasket 40 surrounds the upper end bell of the motor 12 in sealing relationship with the abutment 36A. The gasket 40 may also impart damping to the system.
  • the motor mount 10 in accordance with a first embodiment of the invention itself comprises a first, inner, and a second, outer, mounting member 42 and 44, respectively.
  • Each of the members 42 and 44 is substantially cylindrical in shape.
  • the outer member 44 has a closed end, as shown at 44E, and a radially flaring flange 44F at the opposite end thereof.
  • the inner member 42 is configured to exhibit an enlarged collar 42C at one end thereof and an outwardly flaring flange 42F at the opposite end.
  • the members 42 and 44 are conveniently joined together by any suitable arrangement.
  • the inner member 42 is connected to the outer member 44 by arrays of bolts 46 and 48.
  • the bolts 46 pass in a generally axial direction relative to the member 42 through the flange 42F of the inner member 42 into the flange 44F of the outer member 44.
  • the bolts 48 extend through the periphery of the closed end 44E of the outer member 44 into the collar 42C of the inner member 42.
  • the mount 10 is itself secured to the instrument by bolts 50 that extend through the flange 44F of the outer member 44 and through the plate 16 where they are held by nuts 52.
  • the motor 12 is attached to the mount 10 by a central bolt 54 that extends through the closed end 44E of the member 44 into the lower end bell of the motor 12. The situation could be reversed, if desired, and the motor attached to the outer member and the inner member received to the instrument.
  • both the inner mounting member 42 and the outer mounting member 44 are provided with cooperating pairs of upper and lower slots that extend through the walls of each member.
  • the upper pair of slots is indicated by the reference characters 56A and 56B.
  • the lower pair of slots is indicated by the characters 58A and 58B.
  • the outer member 44 ( Figure 5) is similarly configured.
  • the upper pair of slots is indicated by the characters 62A and 62B, while the lower pair of slots is indicated by the characters 64A and 64B.
  • Each pair of slots in each member is cooperable to define therein at least a first, horizontal, column and a second. vertical, column.
  • the upper pair of slots 56A and 56B cooperates to define a horizontal column 68 and a vertical column 70 in the material of the member 42.
  • the lower pair of slots 58A, 58B is arranged to define a horizontal column 72 and a vertical column 74.
  • the horizontal columns 68 and 72 are angularly spaced ninety degrees while the vertical columns 70 and 74 are also angularly spaced by the same amount as one proceeds about the periphery of the inner member 42.
  • the vertical columns 70, 74 are each spaced ninety degrees from the respective adjacent horizontal column 72, 68, as seen in Figure 4.
  • the upper pair of slots 62A and 62B cooperate to define a horizontal column 78 and a vertical column 80 in the material of the member 44.
  • the lower pair of slots 64A and 64B is arranged to define a horizontal column 82 and a vertical column 84.
  • the horizontal columns 78 and 82 are angularly spaced ninety degrees while the vertical columns 80 and 84 are also angularly spaced by this amount as one proceeds about the periphery of the outer member 44.
  • the vertical columns 80, 84 are each spaced ninety degrees from the respective adjacent horizontal column 82, 78, as illustrated in Figure 5.
  • the axis of the column is parallel to the axis of the mount while the term “horizontal” is meant to indicate that the axis of the column is perpendicular to the axis of the mount.
  • the axis 68A, 72A, 78A and 82A of each of the horizontal columns 68, 72, 78, and 82. respectively lies in a plane (i.e., the plane P) perpendicular to the axis 10A of the mount 10.
  • the axis 70A, 74A, 80A and 84A of each of the respective vertical columns 70, 74, 80, and 84 is parallel to the axis 10A of the mount 10.
  • the vertical columns 70, 74 (on the member 42) and the vertical columns 80, 84 (on the member 44) should be symetrically arranged (in a plane parallel to the plane P) about the axis 10A of the mount to avoid unnecessary bending moments on the vertical columns.
  • the horizontal columns 68, 72, 78, and 82 should also be symmetrically disposed about the axis 10A.
  • Lines 88A, 88B ( Figure 3) joining opposed intersection points 86A, 86C and 86B, 86D themselves intersect at a point 90 on the axis 10A.
  • the point 90 is, as will be developed, the pivot point for the mount 10. Note that in Figure 3 line 88B appears coincident with the point 90.
  • the first embodiment of the motor mount in accordance with the present invention makes use of the well-known fact that columns in either compression or tension are inherently stiffer than the same column would be in bending. in directions where it is desired to exhibit a relatively high stiffness coefficient the forces imposed on the mount in these directions are accommodated by placing predetermined ones of the columns in either tension or compression. In directions where a relatively lower stiffness coefficient is desired forces imposed on the mount in those directions are accommodated by the bending of the columns.
  • the mount 10′ includes a first, central, member 94 and a second, outer, member 96.
  • the central member 94 is an elongated, pin-like member having an integral head portion 94H, a body portion 94B, a shoulder 94S and a tail portion 94T. Both the head 94H and the tail 94T are threaded.
  • the head 94H is threadedly secured to a boss 12B located on the lower end bell of the motor 12.
  • the exterior of the boss 12B is also threaded.
  • the tail 94T is secured to the support plate 16 which in this instance is disposed below the motor 12 of the centrifuge.
  • a nut 97 engages the protruded threaded portion of the tail 94T.
  • the body 94B exhibits a generally circular cross section and defines the main structural portion of the inner member 94.
  • the member 94 has an axis 94A therethrough that aligns with the axis 10A of the mount (and with the z axis).
  • the outer member 96 is a hollow and generally cylindrical in shape.
  • a flange 96F flares outwardly from one end of the member 96 and a lip 96L extends inwardly of the member 96 at the same end thereof.
  • the interior surface at the opposite end of the member 96 is provided with threads 96T which engage the threads on the exterior of the boss 12B.
  • the shoulder 96S of the inner member 94 clamps against the lip 96L of the outer member 96 to secure the same against the plate 16′.
  • the outer member 96 is provided with cooperating pairs of upper and lower slots that extend through the walls of the member.
  • the upper pair of slots is indicated by reference characters 98A and 98B and the lower pair of slots is indicated by the characters 102A and 102B.
  • the upper and lower slots cooperate to define horizontal (as defined above), semicircular columns 104A, 104B, 104C, and 104D therebetween.
  • the columns 104 are equiangularly spaced with the axes of the columns lying in a plane perpendicular to the axis 10A of the mount 10′.
  • Each of the columns 104 is generally rectangular in cross section and has a width dimension b (measured along the axis of the member 96) and a depth dimension h (measured radially of the member 96).
  • the width dimension b is relatively small when compared to the depth dimension h.
  • the axes of the semicircular columns lie on a common plane perpendicular to the axis of the mount. This plane intersects the axis 94A of the member 94 at the midpoint of the body portion 94B to define a pivot point 106 about which the mount 10′ pivots.
  • the second embodiment of the motor mount 10′ in accordance with the present invention makes use of the well-known facts that a column in either compression or tension is inherently stiffer than the same column would be if loaded in bending and that a column with a rectangular cross section loaded in bending is stiffer when the load is imposed along its narrow dimension b as opposed to loading along the wider dimension h.
  • the vertical column defined by the body portion 94B of the inner member 94 accommodates forces in the vertical (z) direction by being placed in either tension or compression.
  • Torsional ( ⁇ ) forces are accommodated by placing all of the horizontal columns 104A through 104D in the outer member 96 in compression.
  • Lateral (r) forces are imposed upon the columns 104A through 104D along the narrow faces b thereof.
  • moment ( ⁇ ) forces are imposed on the columns along the relatively wider face h.
  • either embodiment of the present invention will accommodate any moment by pivoting about the pivot point 90, 106 (as the case may be) and as such will act as the kinematic equivalent of a ball joint.
  • the above-described embodiments of the invention are set forth in the context of a mount of a motor for a centrifuge instrument it should be understood that the mounting apparatus in accordance with the present invention may be used in any other environment.

Landscapes

  • Centrifugal Separators (AREA)
  • Motor Or Generator Frames (AREA)
EP19890106026 1988-04-11 1989-04-06 Support moteur pour centrifugeuse Withdrawn EP0337286A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US17979688A 1988-04-11 1988-04-11
US179796 1988-04-11

Related Child Applications (2)

Application Number Title Priority Date Filing Date
EP92112616.5 Division-Into 1989-04-06
EP19920112616 Division EP0510733A3 (en) 1988-04-11 1989-04-06 Motor mount for a centrifuge

Publications (2)

Publication Number Publication Date
EP0337286A2 true EP0337286A2 (fr) 1989-10-18
EP0337286A3 EP0337286A3 (fr) 1990-10-31

Family

ID=22658039

Family Applications (2)

Application Number Title Priority Date Filing Date
EP19920112616 Withdrawn EP0510733A3 (en) 1988-04-11 1989-04-06 Motor mount for a centrifuge
EP19890106026 Withdrawn EP0337286A3 (fr) 1988-04-11 1989-04-06 Support moteur pour centrifugeuse

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP19920112616 Withdrawn EP0510733A3 (en) 1988-04-11 1989-04-06 Motor mount for a centrifuge

Country Status (2)

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EP (2) EP0510733A3 (fr)
JP (1) JPH0246144A (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE532905C2 (sv) * 2008-09-22 2010-05-04 Alfa Laval Corp Ab Centrifugalseparator

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE198574C (fr) *
FR1090004A (fr) * 1953-07-22 1955-03-25 Ressort
GB1397172A (en) * 1973-05-19 1975-06-11 V Ni In K I Khim Mash Resilient rotor support for centrifugal machines
FR2347570A1 (fr) * 1976-04-05 1977-11-04 Litton Industries Inc Accouplement elastique et son procede de fabrication

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1156346B (it) * 1982-11-29 1987-02-04 Pirelli Dispositivo ammortizzatore

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE198574C (fr) *
FR1090004A (fr) * 1953-07-22 1955-03-25 Ressort
GB1397172A (en) * 1973-05-19 1975-06-11 V Ni In K I Khim Mash Resilient rotor support for centrifugal machines
FR2347570A1 (fr) * 1976-04-05 1977-11-04 Litton Industries Inc Accouplement elastique et son procede de fabrication

Also Published As

Publication number Publication date
EP0337286A3 (fr) 1990-10-31
JPH0246144A (ja) 1990-02-15
EP0510733A3 (en) 1993-03-10
EP0510733A2 (fr) 1992-10-28

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