A cryogenic gyroscope housing having gas spin-up means provided in annular discs inserted between housing shells is described. A circumferential recess in the inner edges of the discs at their juncture serves as the gas spin-up channel, and recesses in the discs at their junctures with the shells form suction channels. The discs also have inlet and outlet ports communicating with the spin-up channel and exhaust slots communicating with the suction channels. Mating surfaces of the discs and housing shells are held in position by optical contact at the equational plane of the housing. Suspension electrodes and thin-film readout loops are disposed in shells. A centering band and clamp rings provide for proper alinement and placement of parts in formation of optical contact joints

Angele, W.

English

NASA Technical Reports Server

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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FROM:
OCT . 1 8 W73
KSI/Scientific & Technical Information Division
Attention: Miss Winnie M. Morgan
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Patent Matters
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U.S. Patent No. : J, >
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Source (if applicable)
NASA patent Case No.
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Pursuant to Section 305(a) of the National Aeronautics and
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Enclosure
Copy of patent cited above
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https://ntrs.nasa.gov/search.jsp?R=19740010210 2020-03-17T14:26:20+00:00Z
United States Patent
Angele.
[ i i ] 3,763,708
[45] Oct. 9, 1973
[54] CRYOGENIC GYROSCOPE HOUSING
[75] Inventor: Wilhelm Angele, Huntsville, Ala.
[73] Assignee: The United States of America as
represented by the Administrator of
the National Aeronautics and Space
Administration, Washington, D.C.
[22] Filed: June 13, 1972
[21] Appl. No.: 262,430
[52] U.S. Cl 74/5.7, 308/10
[51] Int. Cl GOlc 19/12
[58] Field of Search 74/5.7, 5 R, 5.6;
308/DIG. 1,9; 308/10
[56] References Cited
UNITED STATES PATENTS
3,252,340 5/1966 Watt 74/5.7 X
3,535,941 10/1970 Fowler et al . 74/5.7 X
3,522,737 8/1970 Brenot 74/5.7
3,043,635 7/1962 Bard 308/DIG. 1
3,194,613 7/1965 Pierry et al 308/9
3,018,142 1/1962 Warnock, Jr.. 308/9
Primary Examiner—Manuel A. Antonakas
Attorney—L. D. Wofford, Jr. et al.
[57] ABSTRACT
A cryogenic gyroscope housing having gas spin-up
means provided in annular discs inserted between
housing shells. A circumferential recess in the inner
edges of the discs at their juncture serves as the gas
spin-up channel, and recesses in the discs at their
junctures with the shells form suction channels. The
discs also have inlet and outlet ports communicating
with the spin-up channel and exhaust slots communi-
cating with the suction channels. Mating surfaces of
the discs and housing shells are held in position by op-
tical contact at the equatorial plane of the housing.
Suspension electrodes and thin-film readout loops are
disposed in the shells. A centering band and clamp
rings provide for proper alinement and placement of
parts in formation of optical contact joints.
10 Claims, 10 Drawing Figures
\
PATEN ICC GUI 9IS73
SHEET 1 Of 4
3,763,708
10
37
II
26'
12T
18
-16
-17
x-161
FIG. I
39
FIG. 2
PATENTEDOCT 91973 3.763.708
SHEET 2 OF 4
23
FIG. 4
30 31 31
FIG. 5
29 19
FIG. 3
PATENTEDocr 919/3 3.763,708
SHEET 3 OF 4
15
36
F I G . 6
-72
FIG.7
FIG.10
PATENTEDOCT 91973 3,763,708
SHEET t» OF 4
FIG. 8
52^
FIG. 9
3,763,708
1 2
"CRYOGENIC GYROSCOPE HOUSING • It is therefore an object of the invention to provide
ORIGIN OF THE INVENTION ' *" impr°Ved h°USing aSSembly f°r Cry°geniC gyr°-scopes.
The invention described herein was made by an em- Another object is to provide a gyroscope housing as-
ployee of the United States Government and may be 5 sembly that is amenable to attainment of close toler-
manufactured and used by or for the Government of ances in manufacturing.
the United States of America for governmental pur- Still another object is to provide a cryogenic gyro-
poses without the payment of any royalties thereon or scope housing wherein gas spin-up means are located
therefor. elsewhere than in electrode-holding hemispherical
10 housing shells.
BACKGROUND OF THE INVENTION
 Other objects and advantages of the invention will be
This invention relates to gyroscopes and more panic- apparent from the following detailed description and
ularly to gyroscope housing assemblies. the appended claims.
Certain space applications require gyroscopes having
 BRI£F DESCRIPTION OF THE DRAWINGS
a capability for making extremely precise measure- '->
ments, for example, in experiments to determine rela- I" tne drawings:
tivistic precession by means of gyroscopes in an orbit- FIG * « an elevation view of a gyroscope housing as-
ing satellite, measurements on the order of only 0.05 sembly embodying the invention;
arc-seconds per year are required. Such precision far FIG- 2 is a vertical sectional view of the housing as-
exceeds the capability of conventional gyroscopes in sembly of FIG. 1;
which errors due to factors including bearing friction, FIG- 3 is Plan view showing a spin-up disc with the
gravitational effects and temperature are orders of inlet and outlet groove side upward;
magnitude higher than the value sought to be mea- FIG 4 is a Plan view showing a spin-up disc with the
sured exhaust side upward;
Cryogenic gyroscopes avoid most sources of error of 25 ™G 5 is a vertical sectional view taken along line
conventional gyroscopes by use of a superconducting * ' °* F'G- 3;
rotor and electrical field suspension, the rotor being FIG- 6 is an enlar8ed sectional view of the encircled
spun and maintained at constant temperature by pas- area in FIG' 2 showin*the inner ed«e of the maJor Se8'
sage of a cryogen vapor. Operation of this type gyro-
 30
 mej" %a Spln'up du* ... , . .
scope is based on the magnetic moment generated by 3° FIG'7 1S an enlar8ed sectlonal Vlew of *e inner edge
rotation of a superconducting body ("London mo- a'ea °f the, m'no/ """L*111 °f a spm-up dlsc' taken
ment.1') By measuring magnetic flux through loops along line 7-7 of HO. 3,
. . . . • «.u . . . r FIG. 8 is an interior view, taken in the upward direc-
around the rotor, precession of the rotor spin axis can . , . . . ' „ . v. _,_ .
. . . . . .. .. . .. tion, of the upper housing she member of FIG. 2;be determined with high precision. •>* ' „ . v" . " . . . . . ...
...... . . . . . j .
 r • FIG. 9 is an interior view, taken in the downward di-While theoretical advantages of cryogenic gyro- . , , , . . . „ . - _.,, -
. r • i -• • rection, of the lower housing shell member of FIG. 2;
scopes are apparent, construction of a practical device .
has proven difficult, primarily because of the close tol- anpIG 1Q fa a schematic vi taken ^  h the .
erances required to be met m manufacture of housing ^
 Q{ g h(jusi embodiment wherein four
parts. In previous approaches to design of housings for 40
 electrodes are located in each shell.
cryogenic gyroscopes, gas spin-up channels and suction
grooves for rotation of the superconducting ball have DESCRIPTION OF THE PREFERRED
been located in hermispherical shell members, along EMBODIMENT
with suspension electrodes and readout loops. Forma- Referring to FIG. 1 and FIG. 2 of the drawings, the
tion of shell halves to exact hemispherical cavity di- 45
 gyroscope housing assembly 10 includes upper housing
mensions has been a formidable problem, and attain-
 shel, Ui lower housing sheii 12 and annular discs 13,
ment of tolerances in gas spin-up channels and suction
 13. inserted between the shells, the shells and inner
grooves in arcuate surfaces of the shells has also pres-
 edges of the discs defining a generally spherical cavity
ented difficulty. A simpler design, more amenable to 14
 for rotatjon therein of a superconducting ball IS.high-precision manufacturing, is needed to realize the 50
 Upper damp fing 16 and lower c,amp ring 16, dis
benefits of cryogenic gyroscopes.
 posed in annular recesses 42,43 in the outer surface of
SUMMARY OF THE INVENTION shells 1! and 12' and centerin« band 17> disposed
around the circumference of the housing at its equato-
In the present invention a cryogenic gyroscope hous-
 T-ia\ zone> provide for precise alinement in bringing
ing is made up of two shells and two annular discs in- 55
 mating surfaces of the shells and discs into optical con-
serted between the shells, the discs being recessed to
 tact during assembly. Clamp rings 16 and 16' are se-
provide a gas spin-up channel and suction channels for cured together against edges of the centering band by
rotation of a superconducting ball. The discs also have means such as bolts 18. Except for bolts and electrical
inlet and outlet ports communicating with the spin-up
 6Q parts to be described below, the entire assembly is pref-
channel and auxiliary exhaust slots communicating erably made of quartz owing to its low thermal expan-
with the suction channels. Suspension electrodes and sion and capability for being formed into parts having
readout loops are disposed within the housing shells, close tolerances and surfaces adapted for optical con-
but gas spin-up means are located entirely in the discs. tact. Other materials having a near-zero thermal expan-
The difficulties encountered previously in preparation sion can also be used.
of exact half-spherical cavities and in formation of pre- Annular discs 13, 13' comprise flat washers having
cise channels and grooves in arcuate shell surfaces are portions of their faces and inner edges removed to pro-
avoided by this means. vide channels or passageways for cryogen vapor em-
3
3,763,708
ployed to spin the superconducting rotor. Discs 13 and
13' are identical to one another, each disc having one
face 19 as shown in FIG. 3 with two radially extending
recesses 21 and 22 .and an opposite face 23 as shown
in FIG. 4 with a plurality of radially extending grooves 5
24 and elevated portions 25 spaced apart around the
entire face. The discs are adapted to be assembled with
faces 19 in mating relation so that recesses 21 and 22
of the two discs are in alinement, forming inlet port 26
and outlet port 27. Recesses 21 and 22 are separated 10
by a small segment 28 of face 19, the major flat seg-
ment 29 between the recesses extending around most
of the circumference of the housing at the equatorial
zone of the rotor. The inner edges of discs 13,13' have,
coextensive with major segment 29 a recess 30 extend- 15
ing from face 19 to a projecting shoulder 31 located ad-
jacent face 23. Shoulders 31,31'define a spin-up chan-
nel 32 which extends around most of the circumference
of the housing and communicates with inlet port 26 and
outlet port 27. As shown in FIG. 6, shoulder 31 extends 20
slightly into the spherical housing cavity, and its inner
edge 33 is rounded to provide an arcuate surface equi-
distant to rotor 15. The gap between the rotor and the
housing is thus reduced at edge 33 in order to restrict
the flow of cryogen vapor into the space between the 25
rotor and housing shells and thus avoid electrical be-
tween the rotor and suspension electrodes. Coextensive
with segment 28 between inlet port 26 and outlet port
27, the inner edges of discs 13, 13' have a smooth sur-
face 34, as shown in FIG. 7, recesses 30, 30' at these 30
segments being terminated in order to avoid back flow
of cryogen vapor.
As shown in FIG. 4 and FIG 5, face 23 of disc 13 has
coplanar elevated portions 25 extending from the outer
edge to a location corresponding to a circle concentric 35
with and slightly larger than the inner edge; the re-
cessed portions 35 inside the tips of elevated portions
25 defining a suction channel 36 extending around the
circumference of the housing and communicating with
the housing, exterior through grooves 24 and apertures 40
37 in centering band 17. Any cryogen vapor that es-
capes between inner edge 33 of the spin-up channel
and the rotor will be vented to external vacuum by this
means, thus preventing buildup of pressure between
the rotor and housing shells.
In the embodiment shown the assembled housing is
maintained in position by means of optical contact
joints between mating surfaces of the discs and housing
shells. Optical contact, characterized by very strong
surface adhesion based on Van Der Waals molecular
forces, requires a high degree of flatness and smooth-
ness in the.mating surfaces. For the preferred material,
quartz, a surface flatness of X/30 or better and parallel
to one light band, which can be obtained by grinding
and polishing, provides a surface condition suitable for
optical contact. Vertical dimensions of the outside sur-
faces of the shells and discs should also be highly uni-
form, within a tolerance of about 10 micro-inches, to
enable precise alinement within the centering band .,_
during assembly.
Suspension electrodes 38, in the form of generally tri-
angular deposits of a thin film of conductive metal such
as titanum or gold, are provided on the inner surface of
housing shells 11 and 12. The electrodes are connected ,,
to a suitable servo control network (not shown) by
means of wire conductors 39 disposed in apertures 40
which penetrate the housing shell. In the embodiment
45
50
shown in FIGS. 2 through 9, housing shells 11 and"12
each carry three electrodes arranged so that their three
axes intersect one another at an angle of 90°.
Additional electrodes or other spacing arrangements
can be used.
Readout signals for determination of gyroscope pre-
cession in three-dimensions are obtained from three
readout loops encircling the rotor in the housing. The
loops may take the form of a thin, narrow deposit of a
superconducting metal such as nobium. One loop 41 is
situated near the equatorial zone of the housing at the
base of suction channel 36 on disc 13. The remaining
two loops are made up of segments carried by the hous-
ing shells as shown in FIGS. 8 and 9 and jumper wires
connecting ends of these segments. One of the latter
two loops is made up segment 44 in housing shell 11
and segments 47 and 48 in housing 12, with segment
terminals 50 and 52 and 51 and 53, respectively, being
connected across discs 13, 13' by jumper wires (not
shown). The other loop includes segments 45 and 46 in
housing shell 11 and segment 49 in housing shell 12,
along with jumper wires for connecting of terminal 54
to 56 and 55 to 57. Electrical isolation of the loops
from one another is provided by interruption of one
loop at its intersection with the other, with the resulting
segment ends being connected by jumper or by-pass
means. Thus teminals 58 and 59 in housing shell 11 are
connected to one another by a jumper wire (not
shown) and terminals 60 and 61 in housing shell 12 are
similarly connected. Isolation can also be provided by
depositing one loop segment to pass over the other,
after depositing an intervening thin layer of insulating
material such as silicon dioxide by sputtering. External
connections to readout loops may take the form of
metal spring contacts disposed within vacant spaces in
inlet and outlet parts or exhaust grooves in the spin-up
discs. Spring contacts 62 and 63 for loop 41 are shown
in FIG. 2, extensions of loop 41 being disposed radially
at the base of grooves 24 so as to be present surfaces
for making electrical connection with the contacts. The
remaining two loops are similarly connected to con-
tacts disposed in exhaust grooves.
FIG. 10 shows an alternate embodiment for place-
ment of suspension electrodes and readout loops. In
this embodiment each housing shell 64 carries four sus-
pension electrodes 65 deposited in quadrants of the
shell surface so that two open band 66 intersect at the
polar regions. Readout loops are disposed symmetri-
cally within the open bands, one loop 67 extending
across the pole and the other loop 68 being interrupted
at terminals 69 and 70, joined by a jumper wire (not
shown) so as to be electrically isolated from loop 67.
A third loop in this arrangement is located in the suc-
tion channel of a spin-up disc as in the embodiment dis-
cussed above. Loop terminals are connected electri-
cally to external wires 71 by means of spring contacts
72 located in exhaust spaces of the spinup discs. Loop
terminals of the housing shell shown are also connected
across the spinup discs to corresponding terminals of
the other housing shell of the assembly (not shown) by
means of suitable jumper wires (not shown). The four-
electrode arrangement provides for symmetrical dispo-
sition of loops in each plane.
For operation under zero-gravity conditions in space,
a solid rotor of quartz or other near zero expansion,
non-magnetic material can be employed in combina-
tion with the housing described above. The space envi-
3,763,708
ronment «!so provides the external vacuum required
for gyroscope operation. Within the earth's atmosphere
and under the influence of normal gravity certain modi-
fications and additional features may be needed. In
order to facilitate electrical field suspension develop- 5
ment, a hollow, lightweight rotor is preferred for use
where the gyroscope is subject to the earth's gravita-
tional field, and provision of an external vacuum is nec-
essary for atmospheric operation.
It will be apparent to one skilled in the an that vari- 10
ous other changes and modifications to the embodi-
ments described above can be made without departing
from the invention.
What is claimed is:
1. A gyroscope housing assembly comprising a pair is
of housing shells and a pair of recessed annular discs
adapted to be inserted in face-to-face relation between
said shells, the inner surfaces of said shells and the
inner edges of said discs forming a generally spherical
cavity and having a super-conducting ball rotatably 20
mounted therein, each of said discs having in its inner
edge at its juncture with the other of said discs a recess
extending round a major segment thereof and coexten-
sive therewith a projecting shoulder extending slightly
into said spherical cavity, said recesses and shoulders 25
defining a gas spin-up channel extending around most
of the circumference of said ball, gas inlet and outlet
ports communicating with said spin-up channel and ex-
haust means communicating the space in said cavity
outside of said spin up channel with an external vac- 30
uum.
2. The housing assembly of claim 1 including in the
faces of said discs opposite to the faces in contact with
one another a circumferential recess at the juncture
thereof with said housing shells and a plurality of radi-
ally extending grooves communicating said circumfer-
ential recess with the exterior of said assembly.
3. The housing assembly of claim 2 wherein said inlet
and outlet ports comprise a pair of mating, radially ex-
tending grooves spaced in close proximity in the faces
of said discs that are in contact with one another.
4. The housing assembly of claim 3 including in the
minor segment of the inner edges of said discs between
the inlet and outlet grooves an unrecessed portion
spaced close to said ball and adapted to prevent back
flow of spin-up gas.
5. The housing assembly of claim 4 including a plu-
rality of thin film suspension electrodes disposed on the
inner surfaces of said shells.
6. The housing assembly of claim 5 including at least
one thin film conductive metal readout loop carried by
said assembly and encircling the circumfeence of said
ball.
7. The housing assembly of claim 6 wherein a metal
readout loop is disposed in the circumferential recesses
of one of said discs.
8. The housing assembly of claim 1 wherein said
housing shells and discs are made of quartz.
9. The housing assembly of claim 8 wherein mating
surfaces of said housing shells and discs are maintained
in position by means of optical contact joints.
10. The housing assembly of claim 9 wherein mating
surfaces of said housing shells and discs have a surface
flatness of A/30 or better and parallel to one light band.
35
40
45
50
55
60
65


Cryogenic gyroscope housing

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