A plurality of bearing sectors are mounted in a housing. Each sector functions as a lobed area in the bearing to obtain the required lubricant film geometry

Moore, W. A.

Schuller, F. T.

English

NASA Technical Reports Server

REPLY TO
ATTN OF:
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON, D.C. 20546
SEP I 6 1974
GP
TO: KSI/Scientific & Technical Information Division
Attn: Miss Winnie M. Morgan
FROM: GP/Office of Assistant General
Counsel for Patent Matters
\ SUBJECT: Announcement of NASA-Owned U.S. Patents in STAR
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In accordance with the procedures agreed upon by Code GP
and Code KSI, the attached NASA-owned U.S. Patent is being
forwarded for abstracting and announcement in NASA STAR.
The following information is provided:
U.S. Patent NO.
Government or
Corporate Employee
Supplementary Corporate
Source (if applicable)
NASA patent case No.
3,y30i5S3-
O- Cr~o\ae/v?/vv-evJ:r
?>
*
" O / ^ f c -
NOTE - If this patent covers an invention made by a corporate
employee of a NASA Contractor, the following is applicable:
YES /— 7 NO
Pursuant to Section 305(a) of the National Aeronautics and C
Space- Act, the name of the Administrator of NASA appears on
the first page of the patent; however, the name of the actual
inventor (author) appears at the heading of column No. 1 of
[the Specification, following the words "...with rj|sp^efe>£o
an invention of ..."
Bonnie L. Woerner
Enclosure
&?~¥<?^^
https://ntrs.nasa.gov/search.jsp?R=19740024808 2020-03-19T16:31:07+00:00Z
United States Patent
Schuller et al.
t i i ] 3,830,552
[45] Aug. 20, 1974
[54] JOURNAL BEARINGS
,*. [75] Inventors: Fredrick T. Schuller; Warren A.
^ Moore, both of Cleveland, Ohio
/• [73] Assignee: The United States of America as
A
* represented by the Administrator of
the National Aeronautics and Space
Administration, Washington, D.C.
[22] Filed: Mar. 30, 1973
[21] Appl. No.: 3_4§J83,
Related U.S. Application Data
[62] Division of Ser. No. 238,264, March 27, 1972.
[52] U.S. Cl 308/121
[51] Int. Cl F16c 19/04
[58] Field of Search 308/121, 73
[56]
2,322,004
2,424,028
References Cited
UNITED STATES PATENTS
6/1943
7/1947
Post 308/73
Hoeberlein 308/73
Primary Examiner—Charles J. Myhre
Assistant Examiner—Frank Susko
Attorney, Agent, or Firm—N. T. Musial; G. E. Shook;
J. R. Manning
[57] ABSTRACT
A plurality of bearing sectors are mounted in a hous-
ing. Each sector functions as a lobed area in the bear-
ing to obtain the required lubricant film geometry.
1 Claim, 8 Drawing Figures
80
PAT£NTEO«JS20I974 3,830,552
SHEET 1 OF 3
10
FIG. 2
FIG. i
14
FIG. 3
PATENTEQWJG201974 3,830,552
SHEET 2 OF 3
62
56
PATENTED AUG201974 3,830,552
SHEET 30F 3
80
84
FIG. 8
3,830,552
1
JOURNAL BEARINGS DESCRIPTION OF THE DRAWINGS
RFI ATFn APPI irATTON Referring now to the drawings:KtLA I tlJ AKFLIL A 1 HJIN
 F,G j ;,, & p,an
This application is a division of application Ser. No. 5 constructed in accordance with the present invention;
238,264 which was filed Mar. 27, 1972.
ORIGIN OF THE INVENTION ™™ **"* *** **
The invention described herein was made by employ- ' FIG. 3 is an alternate embodiment of the bearing
ees of Jhe United States Government and may be man- 10 shown in FIG. 1;
ufactured and used by or for the Government for gov- FIG. 4 is an alternate embodiment of the bearing
ernmental purposes without the payment of any royal- shown in FIG. 3;
ties thereon or therefor. FIG. 5 is a perspective view of a sector of the bearing
BACKGROUND OF THE INVENTION ,
 5
 sh
™
 !
 J ™^>ahemate embodiment of the sector
This invention is concerned with the instability of shown in FIG. 5;
zero or lightly loaded shafts when they rotate at high FIG. 7 is another alternate embodiment of the sector
speeds in bearings in low viscosity lubricants. This in- shown in FIG. 5; and
stability refers to a self-excited fractional-frequency FIG. 8 is a cross section view of still another embodi-
whirl or tendency of the shaft center to orbit the bear- ment of a bearing.
ing center at an angular velocity about half that of the nFsrRiPTirw OF THF PRFFFRRFH
shaft around its own center. DESCRIPTION OF THE PREFERRED
This tendency of lightly loaded rotors running at high EMBODIMENT
speeds to orbit or whirl about the bearing center is Referring now to the drawings, there is shown in FIG.
caused by a film force component, acting at right an- 1 a bearing 10 constructed in accordance with the pres-
gles to the line of centers of the journal and bearing, ent invention which produces a converging-diverging
which predominates under light or zero load condi- film geometry. A lightly loaded shaft 12 rotates at high
tions. This self-excited instability produces an outward speed in the bearing 10 in a clockwise direction as indi-
spiraling of the rotor in the direction of shaft rotation j0 cated by the arrow. This shaft may operate stably at
when the speed is increased. Destructive seizure may speeds as high as 9,000 rpm under a very light or zero
result if the rotor contacts the bearing. load, in low viscosity fluids such as water.
The successful operation of a power generation sys- The bearing 10 comprises a housing in the form of a
tern for space vehicles employing liquid metals as the circular plate 14 having a bore 16 extending along the
working fluid depends upon the ability of a journal
 35 bearing axis for receiving the shaft 12. Suitable holes
bearing to inhibit this instability. Tilting pad bearings 18 are provided in the plate 14 for rigidly mounting the
have been proposed for such applications because bearing and maintaining it in a stationary position as
these bearings are exceptionally stable. However, tilt- the shaft 12 rotates.
ing pad bearings are complex in that they contain sev- A plurality of rigid posts 20 extend outward from the
eral parts and may be subject to pivot surface damage. 40 plate 14 along the shaft 12 as shown in FIGS. 1 and 2.
These posts are equally spaced about the bore 16.
<:i IMM ARY r>F THF iMVFNTinM According to the present invention a plurality of sec-SUMMARY OF THE INVENTION
 tQrs 22 are mounted on the ^^ 20 as shown in FIGS.
These problems have been overcome by utilizing 1 and 2. Each sector 22 comprises a pad 24 flexibly
bearings constructed in accordance with the present 45 mounted to a base 26 with a neck .28 having reduced
invention. Each bearing is of fixed geometry and uti- thickness. In this manner the neck 28 forms a pivot for
lizes a plurality of sectors to provide lobed areas which the pad 24 between its leading edge 30 and trailing
function as a pump when the rotor turns. The resulting edge 32.
pressure distribution is similar to that obtained in a hy- The minimum radial clearance between the pad 24
drostatic gas bearing. 50
 and the shaft 12 is at the neck 28. Both the neck and
The geometry of the lubricant film depends on the the minimum radial clearance are located at a point ap-
configuration of the sectors. The film geometry may be proximately sixty percent of the sector arc length mea-
converging, diverging, or a combination thereof. sured from the leading edge 30 of each sector.
It is, therefore, an object of the present invention to All of the sectors 22 for each bearing 10 are prefera-
provide an improved journal bearing which may be 55 bly fabricated from a common cylinder of bearing ma-
constructed without expensive and complicated ma- terial. The inside of this cylinder is rough bored to an
chining procedures. inside diameter which approximates the outside diame-
A further object of the invention is to provide an im- ter of the shaft 12. A plurality of holes 34 are drilled
proved journal bearing having removable lobed sectors and tapped at the location of each mounting base 26.
which are easily replaced in case of damage.
Another object of the invention is to provide an inex- . The outside surface of the cylinder is machined to the
pensive bearing having improved stability and simpli- contour of the attached sectors 22. The neck 28 of
fied damping. each sector 22 is machined to the desired thickness.
These and other objects of the invention will be ap- ,. This thickness is dependent upon the amount of flexi-
parent from the specification which follows and from bility desired. The cylinder is then cut into the desired
the drawings wherein like numerals are used through- number of pieces to make the sectors 22 for the bearing
out to identify like parts. 10.
3,830,552
The base portion 26 of one sector 22 is inserted into
a slot 36 in a post 20. Mounting screws 38 extend
through the post 20 and are tightened into the threaded
holes 34. Taper pin holes 39 are machined, after assem-
bly, through the post 20 and base portion 26. Taper
pins 40 are then inserted through the post 20 and the
base 26 to rigidly secure the sector 22 in the bearing
10.
The surface of the pad 24 is then ground to a radius
greater than that of the shaft 12 with its center offset
a predetermined amount in a direction away from the
neck 28 of the sector 22. Minimum radial clearance at
the neck 28 is achieved by maintaining the axis of the
grinding wheel on a line passing through the center of
the bearing 10 and the base 26. After each sector 22
has been individually finish ground all the sectors are
rigidly mounted in the bearing housing.
DESCRIPTION OF ALTERNATE EMBODIMENTS
Referring now to FIG. 3 there is shown an alternate
embodiment of the invention which is used to produce
a wholly converging film geometry. This embodiment
utilizes a bearing sector 42 comprising a pad 44 rigidly
mounted on a base 46. The sectors 42 are produced in
a manner similar to that used to machine the sectors 22
shown in FIGS. 1 and 2.
The sectors 42 are mounted in the posts 20 in the
same manner as the sectors 22. The base 46 is formed
on the extreme end of the sector 42. No neck of re-
duced thickness is used in this embodiment. The
amount of sector flexibility is dependent on the wall
thickness of the sector 42. The rigid portion of the sec-
tor 42 is located at the trailing edge 50 of the sector.
The minimum radial clearance is at the approximate
trailing edge 50 which is the most rigid portion of the
sector 42. The maximum radial clearance is at the lead-
ing edge 48 which is the most flexible portion of the
sector 42.
The bearing shown in FIG. 4 is similar to the one
shown in FIG. 3 with the exception that the shaft 12 ro-
tates in the opposite direction. In this manner the most
rigid part of the sector is at the leading edge and the
most flexible portion is at the trailing edge.
In this embodiment a plurality of sectors 52 are
mounted in a bore 54 of a cylindrical bearing housing
56. One of the sectors 52 is shown in greater detail in
FIG. 5.
Each sector 52 has a rigid base 58 as shown in FIGS.
4 to 7 inclusive. The base 58 is mounted in a suitable
slot 60 in the housing 56 as shown in FIG. 4. Each sec-
tor 52 is held in place in its slot 60 by a pair of screws
62 which extend through holes 64 in the housing 56.
The screws 62 are received in tapped holes 66 in each
base 58! When the screws 62 are tightened the base 58
of each sector 52 is rigidly mounted in the slot 60.
In this embodiment a pad 68 extends from the base
58 in the direction of rotation of the shaft 12. Each sec-
tor 52 has a thin wall and forms a cantilevered spring
which converges in the direction of shaft rotation
towards the shaft 12. The minimum radial clearance is
at the trailing edge of each pad 68. The pads 68 form
a wholly converging film geometry.
Referring to the embodiment shown in FIG. 6 the
spring action of the cantilevered pad 68 is damped.
This is achieved by bonding a layer 70 of suitable
damping material to the back surface of each sector 52.
A layer of rubber has been satisfactory for this purpose.
A temperature compensating bearing is shown in
FIG. 7. In this embodiment the sector 52 is a bimetal.
5 One metal layer 71 is bonded to the sector 52. As the
ambient temperature changes, the bi-metallic sector
moves away from or towards the shaft 12 depending on
the coefficient of expansion of the two bonded metals.
10 The inside radius of each bearing sector 52 is rough
machined before assembly. The sectors 52 are then as-
sembled individually in the bearing housing 56. The
sectors are finish ground individually on the inside di-
ameter by off-setting the center of the bearing housing
15 56 with that of the grinding wheel a predetermined
amount that will result in a particular internal bearing
geometry desired. After all the sectors 52 have been in-
dividually ground these sectors are assembled into the
axial slots 60.
20 in the embodiment shown in FIG. 8 no internal offset
machining is required. In this embodiment a cylinder
80 of a bearing material is assembled into a bearing
housing 82 without shimming by subcooling the cylin-
der, or heating the housing. The cylinder 80 is ma-
25 chined in place to a predetermined inside diameter. An
identification mark 84 is imprinted on one surface of
the cylinder 80 and the housing 82.
The cylinder 80 is removed from the housing 82 by
subcooling or heating the assembly. Suitable shims 86
3° are placed around the inside diameter of the housing 82
in an equally spaced manner. These shims are secured
to the top of the housing 82 by tack welding or taping
to prevent dislocation during assembly. The thickness
of each shim 86 is dependent in part upon the lobe
•*
5
 height desired.
The cylinder 80 is again assembled in the shimmed
housing 82 by subcooling the cylinder or heating the
housing 82. During the assembly the identification
mark 84 is aligned. When the cylinder 80 and the hous-
ing 82 have reached equilibrium conditions of tempera-
ture, an inside diameter trace can be made of the resul-
tant contour. This will identify accurately the size of
the lobing which has been obtained. The amount of
lobing will depend on the thickness of the shims 86 as
well as the physical properties of the bearing housing
82, the shims 86, and the bearing material 80.
While various embodiments of the invention have
been shown and described it will be appreciated that
other structural modifications may be made without
departing from the spirit of the invention or the scope
of the subjoined claims.
What is claimed is:
1. In combination with a lightly loaded shaft rotating
at high speed having a film of lubricants thereon, an im-
proved bearing comprising
a stationary housing having a bore extending there-
through from oppositely disposed ends thereof for
receiving said shaft, said bore having a substantially
cylindrical surface,
a cylinder of substantially rigid bearing material in-
serted in said bore, said cylinder having an inside
diameter concentric with said bore and an outside
diameter substantially equal to the diameter of said
bore prior to the insertion of said cylinder into said
bore, and
a plurality of spaced shims in said bore between said
cylinder and said housing, said shims being rigidly
40
45
50
,,
60
65
3,830,552
secured to said oppositely disposed ends of said
•housing to prevent movement thereof as said cylin-
der is inserted in said bore by subcooling the cylin-
der or heating the housing, said shims serving to de-
form said cylinder by maintaining selected portions
of the outer surface of said cylinder out of engage-
ment with said bore while other portions of said
outer surface of said cylinder engage said bore
thereby forming lobes for shaping the geometry of
said film.'
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40
45
50
55
60
65


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