Preliminary assembly and initial test results of gas bearing gyroscope with high-g and sterilization capabilitie

Bremer, J. M.

English

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THE DESIGN AND BUILD OF A GAS BEARING GYROSCOPE POSSESSING 
HIGH G AND STERILIZATION CAPABILITY AND UTILIZING A LOW 
POWER GAS BEARING SPINMOTOR AND HIGH FREQUENCY PUMP 
Contract  No. 951559 
Sixth Quarter ly  P r o g r e s s  Report  
for  period 
1 Apr i l  1968 - 30 June 1968 
Th i s  work was performed f o r  the Jet Propulsion Laboratory,  
California Institute of Technology, Sponsored by the National 
Aeronautics and Space Agency under Contract NAS7 -100. 
Prepared  by: Approved by: /&&d 
S. J. Korzenowski 
P ro jec t  Engineer 
Engineer 
mw 44 ~- 
R. G. Baldwin 
Section Head 
T. W. Garvey 
Program Adminis t ra tor  
Honeywell Inc. 
A erospac  e Division 
Minneapolis, Minnesota 
https://ntrs.nasa.gov/search.jsp?R=19680021900 2020-03-12T10:13:50+00:00Z
NOTICE 
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This  repor t  was prepared as a n  account of Government-sponsored work. 
Neither the United States, nor the National Aeronautics and Space Admin- 
istration (NASA), nor any person acting on behalf of NASA: 
a. Makes warranty of representation, expressed or implied 
with respec t  to the accuracy, completeness, or  usefulness 
of the information contained in this repor t ,  o r  that the use  
of any information, apparatus , method or  process  disclosed 
in this repor t  may not infringe privately owned rights;  or 
b. Assumed any l iabil i t ies with respec t  to the u s e  of, or  f o r  
damages result ing from the use  of any disclosed in this 
report .  
A s  used above, "person acting on behalf of NASA" includes any employee 
o r  contractor of NASA, o r  employee of such contractor,  to the extent 
that such employees or  contractor of NASA, or employee of such con- 
t rac tor  prepares ,  disseminates,  or provides access to, any information 
pursuant to h is  employment with such contractor.  
Requests for  copies of th i s  repor t  should be r e fe r r ed  to: 
National Aeronautics and Space Administration 
Office of Scientific and Technical Information 
Washington, D. C. 
Attention : AFSS -A 
20660-QR6 
NOTICE 
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This  repor t  was prepared as a n  account of Government-sponsored work. 
Neither the United States, nor the National Aeronautics and Space Admin- 
istration (NASA), nor any person acting on behalf of NASA: 
a. Makes warranty of representation, expressed or  implied 
with respec t  to the accuracy, completeness, or  usefulness 
of the information contained in this repor t ,  o r  that the use  
of any information, apparatus , method or  process  disclosed 
in this repor t  may not infringe privately owned rights;  o r  
b. Assumed any liabilities with respec t  to the u s e  of, or  for  
damages result ing from the use  of any disclosed in this 
repor t .  
I t  A s  used above, 
o r  contractor of NASA, o r  employee of such contractor,  to the extent 
that such employees or  contractor of NASA, or  employee of such con- 
t rac tor  prepares ,  disseminates,  or  provides access to, any information 
pursuant to  his  employment with such contractor.  
person acting on behalf of NASA" includes any employee 
Requests for  copies of this  repor t  should be r e fe r r ed  to: 
National Aeronautics and Space Administration 
Office of Scientific and Technical Information 
Washington, D. C. 
Attention: AFSS -A 
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ABSTRACT 
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The sixth quarter  work on the design, build, and test of a gas bearing 
gyroscope possessing high g and steri l ization capability and utilizing 
a low-power gas bearing spinmotor and high-frequency pump bas pro- 
duced a preliminary gyro assembly and initial gyro test resul ts .  
Steps have been taken to  co r rec t  several  problems noted in the initial 
testing and a partial  assembly of the final device has  been produced. 
Future  work includes the final assembly and testing of the gyroscope. 
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SECTION I 
SECTION I1 
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CONTENTS 
Page  
SUMMARY 
P r o g r e s s  (Sixth Quarter)  
Problems (Sixth Quarter)  
Future  Work (Seventh Quarter)  
DISCUSSION 
Prel iminary Build Tes t  Results 
Stator Canning 
Gimbal Shield 
New Header Design 
Contam ination Investigation 
SUMMARY 
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ILLUSTRATIONS 
F igur e Page 
1 GG 159E Contamination 5 
2 Infrared Spectrum of GG159E Contamination 6 
3 Encased and Standard Motor Stator 7 
4 Field Strength Around Gimbal 9 
5 Field Strength in Gyro Spin Axis-Output Axis Plane 10 
6 Bellows Trave l  ve r sus  Gyro Temperature  1 2  
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SECTION I 
SUMMARY 
The purpose of this  contract  is to  build a gyroscope possessing high g and 
sterilization capability utilizing a low-power gas bearing spinmotor and 
high-frequency pump. 
PROGRESS (SIXTH QUARTER) 
0 Completion of functional tests on the preliminary build unit 
e Build of redesigned stator incorporating windings change 
and m eta1 encasement 
0 Build of spinmotor incorporating new stator  
Final  assembly, incorporating additional magnetic shielding 
e Completion of new header assembly with increased bellows 
capacity 
0 Completion of contamination investigation 
PROBLEMS (SIXTH QUARTER) 
0 Several development problems were  uncovered with the first 
build (bellows capacity, spinmotor reaction torque, and 
marginal spinmotor torque). 
to co r rec t  these deficiencies. 
Design changes were  implemented 
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FUTURE WORK (SEVENTH QUARTER) 
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Completion of final gyro build 
Star t  of gyro test program 
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SECTION PI 
DISCUSSION 
PRELIMINARY BUILD TEST RESULTS 
Although testing at the gimbal level had indicated some variability in s tar t ing 
voltage, it was decided to proceed with gyro build to determine whether any 
problems would resu l t  from integration of the piezo pump to  the gyro. 
The resultant gyro performed well, exhibiting ve ry  low drift  r a t e s ,  fast 
response t ime, and good repeatability. 
ceptably high, indicating a magnetic interaction between the spinmotor mag- 
netics and the torquer magnets. 
vibration, shock, and acceleration environments and continued to perform 
well after each. 
Runup-to-runup stability was unac- 
The unit was subjected to the required 
The  bellows position was such that sufficient t ravel  was not available to  reach  
sterilization temperatures .  A hole was tapped in the gyro header and a smal l  
quantity of flotation fluid allowed to  bleed before the hole was re-sealed.  
This  adjusted the bellows position, but unfortunately some small  amount of 
air was a l so  introduced into the fluid and caused pump malfunction after the 
first sterilization exposure. The l o s s  of the pump precluded measurement  
of gyro performance parameters ,  such as t ransfer  function, drift  parameters ,  
or stops after sterilization. However, visual examination, impedance mea- 
surements ,  and spinmotor testing revealed no damage had been done to  the 
gyro as the resu l t  of the steri l ization exposure. 
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STATOR CANNING 
A s  previously stated in 20660-QR5, the variability in start ing voltage on the 
s ta tor  used in the preliminary gyro build was attributed to either organic 
vapor o r  particulate contamination. A detailed visual examination of the 
gas bearing surfaces  after the unit had been disassembled disclosed that a 
deposit had accumulated to form a n  annular r ing on the thrust  plate near  
the intersection of the thrust  and journal bearings. 
deposits were  noted on the rotor in the same region. 
of this r ing  is presented in Figure 1. 
Similar,  though smaller ,  
A 425X magnification 
The  infrared analysis shown in F igure  2 identified the mater ia l  composing 
this  r ing as MS6293N, a filled epoxy used to impregnate the s ta tor  and 
MS7381A Bond mas te r  which is used to bond the s ta tor  laminations. Small 
particles of these mater ia l s  evidently came loose from the stator and were  
drawn to the motor and deposited the re  by gas flow. 
A new stator has  been incorporated into the final unit, utilizing metal  cans 
which completely enclose the exposed epoxy. The encased s ta tor  is shown 
in Figure 3 .  This  will serve to prevent the loose epoxy par t ic les  discussed 
above and to prevent a reoccurence of variability in s tar t ing voltage. 
The  addition of the slot  bridge necessitated a minor turns  change in the 
s ta tor ,  
tain sync margin,  start margin,  and power consumption. 
level after sterilization, start ing voltages in all orientations on this motor 
were  below 22 volts, and running power was 3. 6 watts. 
This  change r e s t o r e s  the original flux density in the gap to main- 
A t  the gimbal 
206 60 -QR6 
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Figure  1. GG159E Contamination 
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28 24 20 18 16 14 
WAVE NUMBER (cm- l  x 100) 
2, 
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Figure  2. Infrared Spectrum of GG159E Contamination 
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Figure 3 .  Encased and Standard Motor Stator 
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GIMBAL SHIELD 
A mu-metal shield has  been incorporated into the gimbal at the snout end 
to reduce the interaction between the motor and torque generator magnetics. 
This  shield will se rvo  to improve the runup-to-runup stability which had 
proved to be unacceptable in the test resu l t s  on the preliminary gyro build. 
The 800-cycle flux density, at the outside surface of the gimbal in the 
plane of the spin axis ,  was measured for th ree  different stator configura- 
tions: 
1) A 
2) A 
3) A 
The resu l t  
stator without end cans 
s ta tor  with inconel end cans 
stator with mu-metal end cans 
of these measurements  is shown in F igure  4. Note that the 
greatest flux density occurs  in the plane of the rotor  hysteresis  r ing due 
to leakage through the ring. 
mater ia l ,  its permeability is low. 
reduce the end turn flux but do not affect the flux leakage through the H-ring. 
Since the H-ring is a permanent magnet 
Note a l so  that the mu-metal end cans 
Flux density measurements  were  made on the torquer end of the gimbal as 
shown in F igure  5. Three  configurations were  a l so  mapped. 
1) Without either the external or internal shield 
2) 
3) 
With the regular  external shield in place 
With both the external shield and the 0.005-inch-thick 
internal shield 
20660-QR6 
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20660-QR6 
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Figure  5. Field Strength in Gyro Spin Axis-Output 
Axis Plane 
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Since the external shield has  a l a rge  center hole to  clear the gimbal snout, 
it is not effective in shielding the flux leakage from the spinmotor. 
internal shield attenuated the leakage flux by a factor of 5. 5. 
The 
The nonsymmetry apparent in both F igures  4 and 5 is due to the stator 
being slightly off center with respec t  to  the center l ine of the gimbal. 
NEW HEADER DESIGN 
Tes t  resu l t s  on the preliminary gyro build showed that additional bellows 
t rave l  was necessary to withstand the temperature  ranges demanded of this 
gyro. The bellows was redesigned 
with additional displacement capability and has  been incorporated in the 
final gyro assembly. 
The test resu l t s  a re  shown in F igure  6.  
CON TAMINAT ION INVEST IGAT ION 
The investigation to determine the sources  of' contamination which contri- 
bute to spinmotor lockup has  been completed, the sources  identified, and 
appropriate design changes made. Specific identification of the contamina- 
tion in the GG159E preliminary build and the resultant design change, can- 
ning of the s ta tor ,  have been discussed above. Other resu l t s  are  as follows: 
0 The lockup of specific gas  bearing motors  was due to 
organic particulate contam ination and not vapor - condensed 
mater ia l s  . 
The contamination is associated with bonding and encapsu- 
lating mater ia l s  in the motor s ta tor ,  
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Gas analysis of a sample filled gimbal showed the gas f i l l  
procedure used on the product l ine to be  satisfactory. 
o Materials  presently used in spinmotor fabrication compare 
favorably with al ternate  mater ia l s  tested either as used o r  
with some additional processing. 
are anticipated. 
No mater ia l  changes 
o W a t e r  vapor and organic outgassing tests verified the original 
assumption that these  phenomena would be much m o r e  preva- 
lant at steri l ization temperature.  A s  a resul t ,  special vacuum- 
bake p r  oc e s s e s have b een initiated s 
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SECTION 111 
SUMMARY 
The final gyro build wil l  be accomplished by 8 July 1968. 
be tested and shipped in September 1968. 
The gyro will 
20660-QR6 


The design and build of a gas bearing gyroscope possessing high G and sterilization capability and utilizing a low power gas bearing spinmotor and high frequency pump  Quarterly progress report, 1 Apr. - 30 Jun. 1968

The design and build of a gas bearing gyroscope possessing high G and sterilization capability and utilizing a low power gas bearing spinmotor and high frequency pump Quarterly progress report, 1 Apr. - 30 Jun. 1968

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