JPH0246144A - Apparatus for attaching motor to centrifugal separator - Google Patents

Abstract

PURPOSE: To obtain a high operating speed by using structure wherein moment force applied to fixing equipment is received by the bending of a column, and vertical direction force, side direction force and torsional force are received by the compression and tension of the column. CONSTITUTION: A mount 10 retains a driving motor 12. An inner and an outer fixing part members 42, 44 are provided with a pair of upper and lower slots which cooperate with each other. Each pair of slots in each of the part members so cooperates that a first horizontal direction column and a second vertical direction column are constituted. When the part members 42, 44 are arranged in the nesting state that one is nested in the other, the axial line of each vertical direction column of one part member intersects the axial line of the horizontal direction column which is adjacent to the corresponding radial direction of the other part member. Thereby bending moment is received by the bending of the column, and vertical direction force, side direction force and torsional force are received by the compression and tension of the column.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mounting device, particularly for a motor used in a centrifuge.

In a centrifuge, a rotating member, i.e. a rotor, is
It is part of a system that includes a motor or other source of motive energy, a drive shaft, and a rotor attachment device called a spud located at the top end of the shaft to receive the rotor.

For various reasons, it is advantageous to rotate the rotor with its center of gravity as close as possible to the axis of rotation. Initially, upon startup of a centrifuge, the rotor mass tends to rotate about its geometric center. However, as the rotor speed increases, a shift occurs and the rotor mass rotates about its center of gravity. The speed at which this shift occurs is known as the rotor's critical speed. When this critical speed is reached, W1 motion and vibration are imparted to the rotor and drive. However, once a critical speed is reached, the vibrations are significantly reduced. Typically, the drive includes some kind of compliance mechanism to absorb the forces applied to the system as the rotor approaches and passes its critical speed.

Historically, centrifuges have been developed along two types of paths for use in various rotational speed ranges. So-called low-speed centrifuge devices (ie, those with speeds less than 20,000 revolutions per minute) usually use a rigid shaft that is either directly connected to a drive motor or driven by a belt. Any compliance necessary to stabilize the operation of such centrifuges is achieved by using elastomers.
Obtained using the "Shock" mount. It is difficult to design equipment to operate at higher speeds using such mounts. This is because the dynamic characteristics of the system are affected not only by the rotor mass, but also by the total mass supported by the shock mount.

In higher speed centrifuges, such as those used in the so-called ultra-speed range (i.e., above 20,000 revolutions per minute), compliance issues are often associated with lower dynamic mass at the expense of simplicity, robustness and cost. This problem is solved by utilizing the deflection of a relatively long and sophisticated shaft to which the rotor is attached.

At higher speeds a simple shock mount cannot be used. This is because the lateral and torsional stiffness is lower than the pivot stiffness or moment stiffness. Moment stiffness depends on the compression and extension of the elastic shock mount, while lateral stiffness and torsional stiffness depend on the shear of the elastic mount. For some types of mounting configurations, it is common for the shear agent to be only one-third the compression agent. For this reason, it is difficult to design critical speeds outside the operating speed range from these three vibration modes.

U.S. Pat. No. 4,511,350 (Romanausk
aS) relates to a suspension system for a centrifugal machine. In addition, a flexible pivot system that uses springs to absorb forces is the Bendix Aerospac
It is known that it is marketed by E.

In view of the foregoing, it would be desirable to have a centrifuge with a simpler, more robust, and rigid shaft needle that allows significantly higher operating speeds. It would also be advantageous to have a drive having a motor mount with relatively high lateral, vertical and torsional stiffness relative to moment stiffness.

The present invention relates to a preferred mounting arrangement for motors used in centrifuges. This attachment device has relatively high vertical, lateral and torsional stiffness compared to pivot or moment stiffness. In a first embodiment, the attachment devices include first, first and second
A second attachment member is included. These attachment members are attached to each other at any convenient location, preferably at their ends. Each mounting member has a slot formed therein to define a plurality of columns. The axes of some of these columns are parallel to the axis of the attachment device, and the axes of other columns run at right angles to the axis of the attachment device. These columns are such that moment forces applied to the first and second attachment members are accommodated by bending of some of the columns, and vertical, lateral and torsional forces are absorbed by at least a given of the columns. accepted by compression or tension at. In a preferred embodiment, each mounting member has a pair of parallel columns and a pair of perpendicular columns. These attachment members are preferably circular, cylindrical, and when nested, one parallel column of one of the attachment members is at its midpoint and the midpoint of one right-angled column of the other attachment member is intersect. Each column is separated by 9 points from the other columns around the circumference of the mounting member.
It is offset by 0 degrees. In a second embodiment, the attachment device includes two members, one of which constitutes at least one column having an axis parallel to the axis of the attachment device, and the other of which constitutes at least one column having an axis parallel to the axis of the attachment device. A plurality of columns are formed with axes extending perpendicular to the axis. These columns allow moments and lateral forces applied to the members to be absorbed by bending of certain of the columns, and vertical and torsional forces to be accommodated by compression or tension in at least certain of the columns. In a preferred embodiment, the inner member takes the form of an elongated pin arranged parallel to the axis of the attachment device, and the outer member is generally cylindrical and provided with a slot to align the axis of the attachment device. It constitutes a plurality of columns located in a plane substantially perpendicular to the plane.

The moment force is taken up by the bending of both the pin and the column of the outer member. Lateral forces are primarily absorbed by the bending of the columns on the outer member.

The invention will be better understood from the following detailed description taken in conjunction with the accompanying drawings, which form a part of this application.

Throughout the following detailed description, like reference numerals indicate like elements in all figures of the drawings.

A typical centrifuge has a drive motor attached to its superstructure, two shafts extending from the drive motor into the centrifuge chamber, and a rotor mounting device, also known as a "spud," located at the top of the shaft. and a rotor attached to the spud. The centrifuge operates with a force in the vertical direction 2, a force in the lateral (shear) direction r, a force in the torsional direction θ, and a force in the moment (i.e., pivot) direction α. Here, these various directions are as shown in the coordinate system shown in FIG. Vertical forces act on the centrifuge along the Z axis, lateral forces act along any axis r located in the plane P perpendicular to the Z axis, and torsional forces θ are applied around the two axes. Acting angularly, the moment force α acts angularly about an arbitrary axis r.

For such a system, the force equation can be written as: That is, F, =m″z+C,z+, z=0 (1
) F r = m r + C, r + K, r =
O(2)F6=mθ+c, θ+# θ=O(3)F
, 4 = m”a+Cg a+K< a=o (4
) where the letter "C" indicates the damping coefficient in the respective subscript direction and the letter rKJ indicates the stiffness coefficient in the respective subscript direction.

As shown in Figure 2, the natural frequencies ω2, ω of the centrifugal separator
, and ωθ occur outside the normal operating speed range of the centrifuge primarily due to the respective stiffness coefficients (K) in the z, r, and θ directions, and at the same time, the natural frequency ω of the centrifuge primarily It may be desirable to configure the centrifuge so that the coefficient K (by which the centrifuge #! or the energy level at which the natural frequency occurs or the centrifugal fraction am
This occurs at the initial stage of operation, which is insufficient to cause any vibration.

To achieve this objective, a motor mount lO according to a first embodiment of the present invention is configured such that vertical forces (2), lateral forces (r>
A motor mount 10' according to another embodiment of the present invention is configured such that torsional forces (θ) are received by column compression or tension and moment forces (α) are received by column bending. In , vertical forces (Z) and torsional forces (θ) are taken by placing the column in compression or tension, and lateral forces (r) are taken by placing the column in bending, creating a relatively high moment of inertia. The moment force (α) is taken by placing the column in a state that produces a relatively low moment of inertia in bending. In either embodiment, the stiffness coefficient is relatively smaller than the stiffness coefficients occurring in other directions.

Referring to FIG. 3, a mount, shown generally at 10, is for supporting a drive motor 12 in an operating position within the centrifuge. This mount 1
0 has an axis 10A extending through the center, which axis is aligned along the Z axis of the coordinate system of FIG. The centrifuge includes a structural plate 16 forming part of the superstructure of its housing. bowl, i.e. chamber 1
8 is supported above plate 16 by standoff links 20.

The bowl 18 may be cooled as shown by a coil 24 attached to its substructure. The shaft 12S of the motor 12 protrudes into the interior of the bowl 1, and the mounting spud 26
It ends with The spud 26 is configured to receive a rotating element or rotor 28 in a manner known to those skilled in the art.

The area around the upper end of the motor 12 is closed off by an insulating shield 32 having a flexible elastomeric boot 34. Shield 32 is supported by a collar 36 having an enlarged abutment 36A attached to plate 16 with screws 38. gasket 4
0 surrounds the upper end bell of the motor 12 in a sealed state with the abutting portion 36A. Gasket 40 can also provide damping to the system.

Referring to FIGS. 3-6, the motor mount 10 itself according to a first embodiment of the present invention includes a first inner mounting member 42 and a second outer mounting member 44. Referring to FIGS. Each attachment member 42,44 is generally cylindrical. Outer member 44 has a closed end, shown at 44E, and a radially flared flange 44F at the opposite end.

Inner member 42 has an enlarged collar 42C at one end.

The opposite end has an outwardly expanding flange 42F. Conveniently, these members 42, 44 are interconnected by any suitable arrangement. In FIGS. 4-6, the inner member 42 has bolts 46.4
It is connected to the outer member 44 by a row of eight. Bolts 46 pass generally axially through flange 42F of inner member 42 and extend into flange 44F of outer member 44. Bolt 48 extends around the periphery of closed end 44E of outer member 44 and into collar 42C of inner member 42.

The mount lO itself is centrifuged by bolt 50 #i
These bolts 50 are attached to the outer member 4.
4 through flange 44F, and extends through plate 16, where it is retained by the flange 44F. Motor 12 is attached to mount 10 by a central bolt 54, which is attached to closed end 44E of member 44.
and extends into the lower end bell of the motor 12. This situation can be reversed if desired, with the motor attached to the outer member and the inner member received in the centrifuge.

As can be seen in the unfolded state shown in Figures 4 and 5, the inside
Both outer mounting members 42,44 are provided with cooperating pairs of upper and lower slots extending through the walls of each member. In the case of the inner member 42 (FIG. 4),
The upper pair of slots are designated by reference numerals 56A, 56B. The outer member 44 (FIG. 5) has a similar configuration. The upper pair of slots are designated by reference numerals 62A, 62B;
The lower pair of slots are designated by reference numerals 64A, 64B.

Each pair of slots in each member can cooperate to define at least a first horizontal column and a second vertical column. For example, as seen in FIG. 4, the upper pair of slots 56A, 56B cooperate to define a horizontal column 68 and a vertical column 70 in the material of member 42. Similarly, a lower pair of slots 58A,
58B are arranged to form a horizontal column 72 and a vertical column 74. Horizontal column 68.72
are angularly separated by 9.0 degrees and vertical column 7
0.74 are also angularly separated by the same amount as they go around the circumference of the inner member 42. Vertical column 70.74
are each spaced 90 degrees from each adjacent horizontal column 72,68, as seen in FIG.

A similar relationship holds for the outer member 44. As seen in FIG. 5, the upper pair of slots 62A, 62B are provided in the material of member 44 with horizontal column 78 and vertical column 8.
0.Similarly, the lower pair of slots 64A, 64B are arranged to form horizontal columns 82, vertical columns 84.Horizontal columns 78, 82 are angularly separated by 90 degrees, and the vertical columns 80.84 are also angularly separated by this amount as they progress around the circumference of outer member 44. As with member 42, vertical columns 80. .84, each adjacent horizontal column 8, as shown in FIG.
2.90 degrees apart from 78.

As used throughout this application, the term "vertical" means that the axis of the column is parallel to the axis of the mount, and the term "horizontal" means that the axis of the column is perpendicular to the axis of the mount. It means that. Thus, the axes 68A, 72A, 78A, 82A of each horizontal column 68.72.78.82 are each located in a plane perpendicular to the axis 10A of the mount 10 (ie, plane P). Vertical column 70.74 respectively
．． 8σ゛, 84 respective axes 70A, 72A, 80A, 8
4A is parallel to the axis 10A of the mount 10.

As can be seen in FIG. 6, when one member 42,44 is arranged nested one within the other, the axes of each vertical column of one member are aligned with the corresponding radially adjacent 9 of the other member. intersects the axis of the horizontal column. These intersections are designated by reference numerals 86A, 86B, 86C186D.

The intersection 86 of the column axes preferably occurs at their midpoint, in which case the intersection 86 lies in a common plane perpendicular to the axis 10A. Mount the member 42.44
When assembled nested together, the vertical columns 70.
74 (on member 42) and vertical columns 80.84
(on members 44) must be arranged symmetrically (in a plane parallel to plane P) about the axis 10A of the mount so that unnecessary bending moments are not created in them; preferably horizontal columns 68.72.78
．． 82 is also arranged symmetrically about the axis fit OA. Lines 88A, 88B (FIG. 3) connecting intersecting points 86A, 86C and 86B, 86D are themselves axis 10.
It intersects at one point 90 on A. This point 90 is the pivot point for the mount 10 in the deployed state. here,
Note that line 88B appears coincident with point 90 in FIG.

In operation, the first motor mount according to the invention
The embodiment takes advantage of the well-known fact that columns are inherently more useful in compression or tension than in bending. In the direction where you want the stiffness coefficient to be relatively high,
Forces on the mounts are accommodated by placing certain of the columns in tension or compression.

In directions where a relatively low stiffness coefficient is desired, the forces applied to the mount are accommodated by the bending of the column.

Thus, in the previously described assembled state of the motor mount 10 shown in FIGS. 3-6, the vertical forces are primarily exerted by placing the vertical columns 70.74.80.84 in tension or compression. I can accept it. Torsional forces ('e) and lateral forces (r) are primarily accommodated by placing all of the horizontal columns 68.72.78.82 in either compression or tension. However, the moment force (α) can be taken by placing all the columns in bending. In another embodiment of the invention, for example, the vertical and horizontal columns of each member can be・It should be understood that it is possible to consider arranging the bars in a manner opposite to the situation shown in the drawings where they are adjacent to each other. Additionally, a configuration in which all of the vertical columns are located on the outer member and all of the horizontal columns are located on the inner member (or vice versa) is contemplated and is within the contemplated scope of the present invention. Examples thereof are disclosed in the remaining figures.

Referring to FIGS. 7-9, another embodiment of a motor mount is shown at 10'. This mount 10
′ includes a first central member 94 and a second outer member 96 . The central member 94 is an elongated pin-shaped member, and has an integrated head 941, a main body 94B, a shoulder 94S, and a foot 94T.The head 948 and the foot 94T are threaded. The head 94H is screwed into a boss 12B provided on the lower end bell of the motor 12.The outer surface of the boss 12B is also threaded.The foot 94T is attached to the support plate 16, and this support The plate is located below the centrifuge motor 12 in this embodiment at the tail 94.
Nut 9.7 is screwed into the protruding threaded part of T.
The main body portion 94B has a substantially circular cross-sectional shape and constitutes the main structural portion of the inner member 94. This inner member 94 has an axis 94A that is aligned with the mount axis 10A (and with the Z-axis).

The outer member 96 is hollow, generally cylindrical, and has a flange 96F extending outwardly from one end thereof and a lip 96L extending inwardly from the member 96 at the same end. The inner surface of the opposite end of the member 96 is provided with a thread 96T that engages with a thread on the outer surface of the boss 12B. Shoulder 96S of inner member 94 presses against lip 96L of outer member 96 to secure it to plate 16'.

As best seen in the exploded view of FIG.
has cooperating pairs of upper and lower slots extending through the wall of the member. The upper pair of slots are designated by the minimum numerals 98A, 98B, and the lower pair of slots are designated by the reference numerals 102A, 102B. The upper and lower slots cooperate with each other to form horizontal (horizontal as previously defined) semicircular columns 104A, 104B, 104C1.
104D. The columns 104 are evenly spaced and their axes lie in a plane perpendicular to the axis 10A of the mount 10''. Each column 104 has a generally rectangular cross section and has a width dimension b (axis of member 96 The width dimension h (measured along the radial direction of the member 96) and the depth dimension h (measured along the radial direction of the member 96) are relatively small compared to the depth dimension.

The axes of the semicircular columns lie in a common plane perpendicular to the axis of the mount. This plane intersects axis 94A of member 94 at the midpoint of body portion 94B and defines a pivot point 106 to which mount 10' is pivoted.

In operation, the motor mount 10' according to the invention
The second embodiment of the invention is such that the column is inherently stiffer when in compression or tension than when in bending, and also allows the column to be loaded along the narrower dimension without being loaded along the wider dimension. It takes advantage of the fact that columns with a rectangular cross section have greater stiffness in bending when subjected to bending.

Therefore, in the direction in which you want to have a relatively high stiffness coefficient, the forces applied to the mount will either place one or more of the columns in tension or compression, or the load will be applied to a narrow, high moment of inertia surface. It is attached by positioning the column so that it is already received. In directions where a relatively low stiffness coefficient is desired, forces on the mount are accommodated by bending the column about a wider, lower moment of inertia surface.

According to this embodiment of the invention, when in the assembled condition of FIGS. 7-9, the vertical column constituted by the body portion 94B of the inner member 94 is verticalized by being placed in tension or compression. Accepts force in direction (z). The torsional force (θ) is applied to the horizontal column 10 of the outer member 96.
4A-104D are all accommodated by placing them in compression. Lateral force (r) is column 104A-10
Added to 4D along its narrow face. However, the moment force (α) is applied to the column along a relatively wide radius.

As is clear from the foregoing, both embodiments of the invention take up any moments by pivoting about the pivot point 90.106, acting as the kinematic equivalent of a ball joint. Although the above embodiments of the invention have been described in connection with mounting a centrifuge motor, it should be understood that the mounting device according to the invention can be used in any other context.

Numerous variations can be implemented by those skilled in the art in accordance with the teachings of the present invention. These variations can be constructed within the scope of the invention as defined in the claims.

Although the present invention has been described in detail above, the present invention can be further summarized by the following embodiments.

1) an attachment device having a penetrating axis, the attachment device having a first axis;
, a plurality of columns including a second attachment member, the attachment members cooperating with each other to accommodate an axis parallel to the axis of the attachment device, and an axis extending perpendicular to the axis of the attachment device. a plurality of columns having a structure in which moment forces applied to the attachment device are absorbed by bending of at least some of the columns and vertical, lateral and torsional forces applied to the attachment device are absorbed by bending of at least some of the columns; A mounting device characterized in that the columns are arranged to absorb compression or tension in at least some of the columns.

2) The attachment device of item 1, wherein the first and second members are both cylindrical and each includes a row of cooperating slots to form a column.

3) A mounting device according to item 2 above, characterized in that columns of one member parallel to the axis intersect columns of the other member extending perpendicular to the axis.

4) a mounting device for a motor having an axis passing through the motor, further comprising first and second mounting members, the first and second mounting members cooperating with each other; at least one column having an axis parallel to the axis of the attachment device and a plurality of columns having axes extending perpendicular to the axis of the attachment device;
, moment forces and lateral forces applied to the second attachment member are absorbed by bending of a given one of said columns, and vertical and torsional forces are absorbed by compression or lateral forces in at least a given one of said columns. An attachment device characterized in that it is absorbed by tension.

5) The first member is an elongated pin, and the second member is generally cylindrical and has a row of slots formed therein, the slots cooperating to form a column. Attachment device according to paragraph 4.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a coordinate system for explaining the operation of a motor mount according to the present invention. FIG. 2 is a graph showing the relationship between centrifuge operating speed and critical speed, which is primarily controlled by various stiffness constants. FIG. 3 is a side cross-sectional view of a motor mount according to the present invention used in an operating environment to support a centrifuge drive motor. 4 and 5 are exploded views of mounting members used in the motor mount according to the present invention. FIG. 6 is a developed view similar to FIGS. 4 and 5, and is a diagram showing the relationship between the mounting members. FIG. 7 is a side sectional view of another embodiment of the invention. FIG. 8 is a developed view of the outer attachment member of the embodiment shown in FIG. 7. FIG. 9 is a front view of the inner mounting member of the embodiment shown in FIG. 7. In the drawings, 10... motor mount, 12...
- Drive motor, 16... Structural plate, 18... Bowl, 26... Mounting spud, 28... Rotor, 32... Heat insulation shield, 40... Gasket. 42.44--Attachment member, 56A, 56B. 58A, 58B, 62A, 62B, 64A, 64 B-
...Slot, 68.72.78.82--Horizontal column, 70.74.80.84...Vertical column.

Claims (1)

[Scope of Claims] 1) An attachment device having a penetrating axis, the attachment device including a first
, including a second attachment member which cooperate with each other to form a plurality of columns having axes parallel to the axis of the attachment device and an axis extending perpendicular to the axis of the attachment device. a plurality of columns having a plurality of columns, wherein moment forces applied to the attachment device are counteracted by bending of at least some of the columns and vertical, lateral and torsional forces applied to the attachment device are accommodated by the bending of at least some of the columns; Mounting device characterized in that said columns are arranged to be received by compression or tension in at least some of them. 2) a mounting device for a motor having an axis therethrough and further including first and second mounting members, the first and second mounting members cooperating with each other; at least one column having an axis parallel to the axis of the attachment device and a plurality of columns having axes extending perpendicular to the axis of the attachment device;
, moment forces and lateral forces applied to the second attachment member are absorbed by bending of certain ones of said columns, and vertical forces and torsional forces are absorbed by compression or tension in at least certain ones of said columns. An attachment device characterized in that it is received by.