A hydrostatic bearing support system is provided which comprises a bearing housing having a polygonally configured outer surface which defines at least three symmetrically disposed working faces and a plurality of pressure plates, each of which is disposed relatively opposite a corresponding working face and spaced therefrom to define a gap therebetween. A hydrostatic support film is created in the gap for supporting the housing in spaced relationship to the pressure plates

Cunningham, R. E.

English

NASA Technical Reports Server

United States Patent [191 
Cunningham 
[ I l l  4,035,037 
[451 July 12, 1977 
HYDROSTATIC BEARING SUPPORT 
Inventor: 
Assignee: 
Robert E. Cunningham, Fairview 
Park, Ohio 
The United States of America as 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
Appl. No.: 663,008 
Filed: Mar. 2, 1976 
Int. CL2 ........................................... F16C 1/24 
U.S. Cl. ................................... 308/5 R; 308/9; 
308/73 
Field of Search ................... 308/5 R, 9, 72, 73 
References Cited 
U.S. PATENT DOCUMENTS 
3,442,560 5/1969 De Gast ............................. 308/5 R 
3,476,447 1 111 969 Boyd ..................................... 30819 
B 391,797 3/1976 Okano ................................... 308/9 
Primary Examiner-Joseph F. Peters, Jr. 
Assistant Examiner-Gene A. Church 
Attorney, Agent, or Firm-N. T. Musial; G. E. Shook; 
John R. Manning 
ABSTRACT [571 
A hydrostatic bearing support system is provided which 
comprises a bearing housing having a polygonally con- 
figured outer surface which defines at least three sym- 
metrically disposed working faces and a plurality of 
pressure plates, each of which is disposed relatively 
opposite a corresponding working face and spaced 
therefrom to define a gap therebetween. A hydrostatic 
support film is created in the gap for supporting the 
housing in spaced relationship to the pressure plates. 
5 Claims, 2 Drawing Figures 
42 
https://ntrs.nasa.gov/search.jsp?R=19770021542 2020-03-20T07:26:24+00:00Z
U.S. Patent July 12, 1977 4,035,037 
-42 
1 
HYDROSTATIC BEARING SUPPORT 
ORIGIN OF THE INVENTION 
The invention described herein was made by an em- 
ployee of the United States Government and may be 
manufactured or used by or for the Government with- 
out the payment of any royalties thereon or therefor. 
FIELD OF THE INVENTION 
4,035,03 7 
The present invention relates in general to bearing 
support systems, and in particular to hydrostatic sup- 
port systems for rotor bearings in high speed turboma- 
chines. 
BACKGROUND OF THE INVENTION 
It is common, particularly in the small, lightweight, 
high speed turbomachines which are increasingly being 
used in a variety of applications, to encounter one or 
more system resonances in accelerating the rotating 
components to design speed. If conventional rigid bear- 
ing supports are used, the rotating components must be 
carefully balanced in order for the machinery to pass 
through the critical speeds with minimum excursion of 
the rotating members. However, with high operating 
speeds of many turbomachines, which speeds may be in 
the range of 36,000 rpm, even relatively small imbal- 
ances in rotating components will produce excessive 
vibration. 
Much attention has been devoted to developing so- 
called “flexible” or “soft” bearing supports, .Le., sup- 
ports which have a stiffness much less than that of the 
bearings. Further, since an undamped flexible support 
system is highly sensitive to external shocks, various 
damping mechanisms have also been developed. 
In order to overcome the disadvantage associated 
with conventional flexible supports such as rubber 0- 
rings, springs, diaphragms, and the like, and with con- 
ventional damping methods such as the use of lubricat- 
ing oils and elastomers (see, e.g., the U.S. Pat. No. 
3,097,167, to Beyerle), hydrostatic bearing systems 
have been developed. Although this listing is not, nor is 
it intended to be, exhaustive, such hydrostatic bearings 
are illustrated in U.S. Pat. Nos. 3,049,383 (Loch); 
3,442,560 (de Gast); and 3,499,691 (Baier). These and 
other conventional hydrostatic bearing systems are 
characterized by their circular geometries. As a conse- 
quence, some means, such as anti-rotation pins, or the 
like, are required to prevent relative rotation between 
the bearings and the bearing supports. Moreover, a 
circular geometry makes it very difficult to vary the 
dynamic damping characteristic of the hydrostatic sup- 
porting film, or to selectively adjust the dynamic stiff- 
ness characteristic of portions or particular areas of the 
supporting film. Conventional hydrostatic bearing sys- 
tems thus have limited effectiveness in controlling the 
various rotor unbalance forces generated at different 
rotor speeds. 
SUMMARY OF THE INVENTION 
These and other disadvantages of the prior art are 
overcome by a hydrostatic support system constructed 
according to the present invention. The system of the 
present invention comprises a bearing housing in which 
the bearings are disposed, and a plurality of associated 
pressure plates. The bearing housing has a substantially 
polygonal outer surface configuration as viewed in 
transverse cross-section perpendicular to the axis of 
5 
10 
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20 
25 
30 
35 
40 
45 
50 
55 
60 
65 
Y 
rotation of the rotating member being supported, and 
the outer surface of the housing forms at least three 
symmetrically disposed working faces. A pressure plate 
is disposed relatively opposite each of the working 
faces of the housing and is spaced from the correspond- 
ing working face such that a gap is defined between 
each associated working face and pressure plate when 
the housing is centered with respect to the pressure 
plates. Means are also provided for introducing fluid 
under pressure into @e gaps to form supporting hydro- 
static films between Qe working faces and the pressure 
plates such that the housing may be suspended between 
the pressure plates in spaced relationship thereto. 
Advantageously, at least one of the pressure plates is 
movable to provide adjustment of the thickness of the 
gaps and thereby to vary the damping characteristic of 
the supporting film. Additionally, or alternatively, the 
means for introducing fluid under pressure is controlla- 
ble to adjust the pressure of the supporting film and 
thereby vary its stiffness. In addition, the gap-facing 
surface of each pressure plate preferably includes at 
least two recessed pockets may comprise rows of ori- 
fice restrictors. 
In accordance with the invention, a hydrostatic bear- 
ing system is thus provided which enables one to 
readily adjust the thickness of the supporting hydro- 
static films and hence to adjust the dynamic damping 
characteristics of the supporting fdms. In addition, the 
bearing system enables one selectively to vary the pres- 
sure and thus the stiffness of the film in a particular 
area of the bearing support. Further, the dynamic char- 
acteristics of the supporting film may be “tuned” with- 
out interrupting the operation of the rotating equip- 
ment, allowing adjustment of the bearing support sys- 
tem to varying operating conditions. As a result, both 
the threshold and amplitude of non-synchronous, self- 
excited, rotor precession and synchronous, externally 
exited rotor precession can be controlled. Further, the 
polygonal geometry eliminates the need for additional 
rotation-controlling structure. 
Other features and advantages of the invention will 
be set forth in, or apparent from, the detailed descrip- 
tion of a preferred embodiment found hereinbelow. 
BRIEF DESCRIPTION OF THE FIGURES 
FIG. 1 is a simplified diagrammatic, transverse cross- 
sectional view of a first embodiment of the present 
invention taken perpendicular to the axis of rotation of 
the rotating member being supported. 
FIG. 2 is a simplified diagrammatic transverse cross- 
sectional view of a second embodiment of the present 
invention taken perpendicular to the axis of rotation of 
the rotating member being supported. 
DETAILED DESCRIPTION OF THE PREFERRED 
EMBODIMENTS 
Referring to FIG. 1, an embodiment of a hydrostatic 
bearing support system constructed according to the 
present invention is illustrated. The support system, 
generally denoted 10, basically comprises a bearing 
housing 20 and a plurality of pressure plates 40. 
Housing 20 is adapted to receive a rotor 50 and a 
conventional bearing assembly 60. A journal bearing is 
depicted, but a roller-element bearing, or any other 
type of fluid film bearing, may also be used. The outer 
surface configuration of housing 20, as viewed in trans- 
verse cross-section perpencicular to the axis of rotation 
of rotor 50 is non-circular and preferably polygonal, In 
3 
4,03 5,03 7 
4 
the embodiment shown in FIG. 1, the outer surface of consequence, the dynamic characteristics of System 10 
housing 20 is shaped such that there are three planar, may be “tuned” to minimize the amplitudes of either 
outwardly facing, working faces 22 symmetrically dis- synchronous or non-synchronous rotor vibrations with- 
posed with respect to the longitudinal axis of housing out stopping rotation of rotor 50. 
20. The outer surface of housing 20 may also be pro- 5 It will also be appreciated that the hydrostatic bear- 
vided with connecting faces 24, as shown. It is to be ing support system of the present invention may be 
noted that the number of working faces 22 is not lim- used with appropriate conventional instrumentation to 
ited to three, nor are connecting faces 24 required. An determine the dynamic stiffness and damping proper- 
embodiment of support system 10 having a square ties of particular gas films. To do this, the dynamic 
housing 20 without connecting faces is illustrated in 10 displacement of housing 20 relative to each of the pres- 
FIG. 2. Other polygonal geometries may be used as sure plates 40 is measured for predetermined speeds of 
well. rotor 50, along with the phase angle between the forces 
Referring again to FIG. 1, pressure plates 40 are produced by rotor unbalance and the associated dis- 
disposed relatively opposite the corresponding working placement of housing 20. 
faces 22 and are spaced therefrom such that gaps 42 15 It will be appreciated by those skilled in the art that 
are defined therebetween when housing 20 is centered although the invention has been described relative to 
with respect to pressure plates 40. At least one pressure exemplary embodiments thereof, modifications and 
plate 40 is movable, as indicated by the doubleheaded variations can be effected in these embodiments with- 
arrow A, to adjust the thickness of gaps 42 during oper- out departing from the scope or spirit of the invention. 
ation of support system 10, as will be explained in more 20 I claim: 
detail hereinbelow. An embodiment of support system 1. A hydrostatic support system having improved 
10 wherein a plurality of pressure plates 40 are mov- dynamic damping characteristics for bearings used to 
able is illustrated in FIG. 2. support a rotating member, said support system com- 
With further reference to FIG. 1, the gap defining prising a bearing housing in which the bearings are 
faces of pressure plates 40 are provided with at least 25 disposed, said bearing housing having a substantially 
two recessed pockets. 44 communicating through ori- polygonal outer surface configuration as viewed in 
fice 46 with a supply chamber 48 of high pressure fluid, transverse cross-section perpendicular to the axis of 
indicated by P,. Orifices 46 act as flow restrictors and rotation of the rotating member, and the outer surface 
provide each pocket 44 with a pressure above the am- of said housing forming at least three symmetrically 
bient, indicated by Po. A hydrostatic film is thus formed 30 disposed working faces; a pressure plate disposed rela- 
between the working faces 22 and pressure plates 40 tively opposite each of said working faces and spaced 
which serves to support or suspend housing 20 in therefrom such that a gap is defined between each 
spaced relationship between pressure plates 40. In an working face and corresponding pressure plate when 
alternative embodiment, pocket 44 may comprise rows said housing is centered with respect to said pressure 
of orifice restrictors (not shown). 35 plates; and means for introducing fluid under pressure 
Conventional feedback control means (not shown), into said gaps to form supporting hydrostatic films 
incorporating sensing elements such as non-contacting between said working faces and said pressure plates 
displacement probes, force transducers, accelerome- such that said housing may be suspended between said 
ters, and the like, may be provided to adjust pressure Po pressure plates in spaced relationship thereto. 
and the thickness of gaps 42. 2. The hydrostatic support system of claim 1 wherein 
In operation, when eccentricities in rotor 50 cause at least one of said pressure plates is movable to adjust 
rotor 50 to orbit about the center of bearing 60, hous- the thickness of said gaps to thereby vary the damping 
ing 20 will tend to follow. The motion of housing 90 is characteristic of said supporting films. 
resisted by the forces of the hydrostatic supporting 3. The hydrostatic support system or claim 1 wherein 
films resulting from the non-circular geometry of hous- 45 said means for introducing fluid under pressure com- 
ing 50 and the multiple pressure plates 40. Further prises at least two recessed pockets formed in each of 
stabilization of housing 50 is provided by pockets 44. said pressure plates in the surface thereof facing said 
The slight oscillatory motion produced in housing 20 as gap. 
rotor 50 begins to rotate produces a squeeze film 4. The hydrostatic support system of claim 1 wherein 
damping force which tends to damp out rotor oscilla- 50 said means for introducing fluid under pressure in- 
tions. By adjusting the pressure plate(s) 40 which is cludes means for selectively adjusting the pressure of at 
(are) movable, the thickness of gaps 42, and thus of the least one of said supporting films to thereby vary the 
hydrostatic supporting films, may be varied. The fea- stiffness characteristic thereof. 
ture of providing an adjustable film thickness allows the 5. The hydrostatic support system of claim 4 wherein 
damping coefficient of the supporting film to be con- 55 said recessed pockets comprise rows of orifice restric- 
trolled. Further, by adjusting film pressure Po, the stiff- 
ness of the supporting film may also be varied. As a 
40 
tors. * * * * *  
60 
65 


Hydrostatic bearing support

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