A motor for use in a volatile environment includes a rotor exposed to the volatile environment, electronics for rotating the rotor, an impervious ceramic barrier separating the electronics and the rotor, and a flexible seal for preventing the volatile environment from contacting the electronics and for minimizing vibratory and twisting loads upon the barrier to minimize damage to the barrier

Beringer, Durwood M.

Carra, Michael R.

M'Sadoques, George A.

NASA Technical Reports Server

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(12) United States Patent 	 (lo) Patent No.: 	 US 8,593,024 B2 
M'Sadoques et al. 	 (45) Date of Patent: 	 Nov. 26, 2013 
(54) IMPLEMENTATION OF A NON -METALLIC 
BARRIER IN AN ELECTRIC MOTOR 
(75) Inventors: George A. M'Sadoques, Granby, MA 
(US); Michael R. Carra, Enfield, CT 
(US); Durwood M. Beringer, Suffield, 
CT (US) 
(73) Assignee: Hamilton Sundstrand Space Systems 
International, Inc., Windsor Locks, CT 
(US) 
(*) Notice: 	 Subject to any disclaimer, the term of this 
patent is extended or adjusted under 35 
U.S.C. 154(b) by 409 days. 
(21) Appl. No.: 12/758,353 
(22) Filed: 	 Apr. 12, 2010 
(65) 	 Prior Publication Data 
US 2011/0248586 Al 	 Oct. 13, 2011 
(51) Int. Cl. 
H02K51128 	 (2006.01) 
(52) U.S. Cl. 
USPC ............................................... 310/86; 310/88 
(58) Field of Classification Search 
USPC 	 ...................................................... 310/86,88 
See application file for complete search history. 
(56) 	 References Cited 
U.S. PATENT DOCUMENTS 
	
2,730,636 A * 	 1/1956 Dunn .............................. 310/86 
	
3,031,973 A 	 5/1962 Kramer 
	
3,229,130 A * 	 1/1966 Drouard .......................... 310/54  
	
4,808,087 A 	 2/1989 Tsutsui et al. 
	
5,256,038 A 	 10/1993 Fairman 
5,385,454 A1/1995 Kobayashi et al. 
	
5,601,493 A * 	 2/1997 Nakazono et al . ............ 464/181 
	
5,692,886 A 	 12/1997 Kobayashi et al. 
	
6,417,591 131 * 	 7/2002 Saito et al . .................... 310/104 
	
6,814,549 132 	 11/2004 Kimberlin et al. 
	
6,884,043 132 	 4/2005 Kimberlin et al. 
	
6,948,919 132 * 	 9/2005 Roslund et al . ............ 417/423.7 
2003/0160527 Al 	 8/2003 Kimberlin et al. 
FOREIGN PATENT DOCUMENTS 
JP 	 07-035074 	 2/1995 
JP 	 2001231213 	 8/2001 
JP 	 2002136046 	 5/2002 
JP 	 2002165411 	 6/2002 
OTHER PUBLICATIONS 
http://water.usgs.gov/nawga/vocs/oxybib/index.oxybib.html,  May 
2009.* 
Murakami et al, JP200 1 23 1 2 13 Machine Translation, Aug. 2001.* 
* cited by examiner 
Primary Examiner Burton Mullins 
Assistant Examiner Eric Johnson 
(74) Attorney, Agent, or Firm Carlson, Gaskey & Olds, 
PC 
(57) 	 ABSTRACT 
A motor for use in a volatile environment includes a rotor 
exposed to the volatile environment, electronics for rotating 
the rotor, an impervious ceramic barrier separating the elec-
tronics and the rotor, and a flexible seal for preventing the 
volatile environment from contacting the electronics and for 
minimizing vibratory and twisting loads upon the barrier to 
minimize damage to the barrier. 
19 Claims, 1 Drawing Sheet 
120 
160 	 155 
/155 	 —130— 175 	 165 
100 	 150 
125 	 145'-170— 	 145 
0M VIP4 	 155 
140 	 180 	 140 
150 	 135 
161 	 115 
110 
105 
https://ntrs.nasa.gov/search.jsp?R=20150003158 2019-08-31T11:30:04+00:00Z
U.S. Patent 	 Nov. 26, 2013 	 US 8,593,024 B2 
r20 
30 
10-r 0, 
FIG.1  
Prior Art 
120 
160 	 155 
	
105 
/155 
10 	
-130- 175 ~ 	
1505 
125 	 145'-170- 	 145 
155 
140 	 180 
	 140 
150 	 135 
161 	 115 
110 
FIG.2 
US 8,593,024 B2 
2 
IMPLEMENTATION OF A NON -METALLIC 
BARRIER IN AN ELECTRIC MOTOR 
This invention was made with government support under 
Contract No. RH6-118203 awarded by NASA. The Govern-
ment has certain rights in this invention. 
BACKGROUND 
Some electric motors are "canned" or sealed using a metal-
lic barrier to prevent an environment in which the motor is 
used from entering into the electrical portion of the motor. 
Such environments may include a fluid like a liquid or a gas. 
In running in volatile environments such as higher concen-
trations of oxygen, the volatile environment must be sealed 
from the electronics to prevent any sparks from interacting 
with the oxygen. 
SUMMARY 
According to an exemplar, a motor for use in a volatile 
environment includes a rotor exposed to the volatile environ-
ment, electronics for rotating the rotor, an impervious 
ceramic barrier separating the electronics and the rotor, and a 
flexible seal for preventing the volatile environment from 
contacting the electronics and for minimizing vibratory and 
twisting loads upon the barrier to minimize damage to the 
barrier. 
A frangible barrier is disposed between a rotor and the 
electronics the rotor being disposed in a volatile atmosphere. 
The frangible barrier is supported by a set of O-rings that also 
act as seals to prevent the environment from reaching the 
motor electronics. 
These and other features of the present invention can be 
best understood from the following specification and draw-
ings, the following of which is a brief description. 
BRIEF DESCRIPTION OF THE DRAWINGS 
FIG. 1 shows a prior art embodiment of a canned electric 
motor. 
FIG. 2 shows an embodiment of an electric motor with a 
non-metallic barrier in a volatile environment. 
DETAILED DESCRIPTION OF THE PREFERRED 
EMBODIMENT 
Referring to FIG. 1, a prior art example of a motor 10 used 
in an oxygen-rich environment 15 is shown. The motor 10 
includes housing 20, having a cylindrical body 25 with an end 
seal 30. The housing 20 holds electronics 35 (such as controls 
and stator windings etc.) in which electricity is used. An 
electrically conductive canning material 40, such a metal, is 
used to create a recess 70 in which a plurality of bearings 45 
hold a rotor 50. The canning material 40 is attached conven-
tionally to the housing 20 at an open end 60 of the cylinder 25 
and to an environment wall 65. An O-ring 55 is disposed 
between the housing 20 and the environmental wall 65 to 
prevent the environment from leaking outside the motor 10. 
The continuous canning material 40 seals the oxygen from 
reaching the electronics 35. Unfortunately this metal canning 
reduces the motor efficiency as its speed is increased. For 
example, higher currents in the motor 10 can induce eddy 
currents in the canning material 40. The eddy currents in the 
canning material 40 may interfere with magnetic flux 
between the rotor 50 and electronics 35, resulting in drag 
forces and heating as electrical current is increased in the 
motor 10. 
Referring now to FIG. 2 a motor 100 is shown in a volatile 
5 environment 105, such as a 100% oxygen environment of a 
space suit, though other volatile fluid mixtures in other loca-
tions are also contemplated herein as volatile environments. A 
housing 110 extends into the environment via a radially out-
board portion 115. The housing 110 also includes a cylindri- 
io cal portion 120 closedoffby endportion 125. The interior 130 
of the cylinder houses electronics 135 (like windings and 
controls) or the like. The housing 110 has a set of four radial 
grooves 140 that hold O-rings 145, which may be made of 
silicone, or the like, as will be discussed herein below. 
15 The motor has a bearing set 150 disposed in races 155 at an 
inboard portion 160, the races 155 disposed within a circular 
flange 161 extending inboard from the end portion 125 (as 
shown in FIG. 2) and a radially outboard portion 165 to hold 
a rotor 170 that is disposed for rotation within the bearing sets 
20 150. A non-metallic barrier 175, which may be frangible, 
thin, non-metallic, non-magnetic, ceramic material shaped 
like a cylinder is disposed within the O-rings 145. Other 
shapes may be contemplated herein. The rotor 170 is config-
ured for exposure to the volatile environment 105, as a gap 
25 180 exists between the rotor 170 and the non-metallic barrier 
175. The barrier 175 is isolated from the housing 20 by the 
o-rings 144. 
By providing a very thin non-metallic bather 175 made of 
an impervious ceramic material, the efficiency of the motor 
30 100 is greatly improved because interference with magnetic 
fluxes between the rotor 170 and electronics 135 is mini-
mized. The ceramic material for the non-metallic barrier 175 
is used because non-metallic materials do not rust or burn in 
an oxygen rich or pure oxygen environment and are anti- 
35 magnetic. Though an embodiment uses stabilized zircona as 
the ceramic material, other morpheus and amorphous glasses 
and crystals such as sapphire, alumina, or the like may also be 
used. 
The non-metallic barrier 175 thickness may be approxi- 
40 mately 0.025 inches (0.635 mm) thick and made of a ceramic 
material like a glass, as stated above, and such glass tends to 
be brittle. Motors for certain applications, like space explo-
ration, may be subject to high vibrational and torquing envi-
ronments. The O-rings 145 act as flexible seals to protect the 
45 ceramic material of the non-metallic barrier 175 from deflec-
tion within the motor 100 due to bending or twisting, or from 
vibration and shocks that may shatter a glass barrier in a 
rigidly mounted configuration. The compliance of the 
O-rings 145 gently constrains the non-metallic barrier 175 
5o and isolates it from the harsh external motor environment. 
The combination of the O-rings 145 and the non-metallic 
barrier 175 isolate the electronics 135 from the volatile envi-
ronment 105 to which the rotor 170 may be exposed. 
While glass is contemplated herein other frangible mate- 
55 rials that do not interfere with the magnetic flux between the 
rotor and the stator of a motor are here also contemplated. 
Although a combination of features is shown in the illus-
trated examples, not all of them need to be combined to 
realize the benefits of various embodiments of this disclosure. 
60 In other words, a system designed according to an embodi-
ment of this disclosure will not necessarily include all of the 
features shown in any one of the Figures or all of the portions 
schematically shown in the Figures. Moreover, selected fea-
tures of one example embodiment may be combined with 
65 selected features of other example embodiments. 
The preceding description is exemplary rather than limit-
ing in nature. Variations and modifications to the disclosed 
US 8,593,024 B2 
3 
examples may become apparent to those skilled in the art that 
do not necessarily depart from the essence of this disclosure. 
The scope of legal protection given to this disclosure can only 
be determined by studying the following claims. 
What is claimed is: 
1. A motor for use in a volatile environment, said motor 
comprising; 
a housing having an inboard end portion and an outboard 
end portion, said outboard end portion extending into 
said volatile environment, 
a rotor configured for exposure to said volatile environ-
ment and disposed in said housing, said rotor supported 
for rotation within said housing in an inboard set of 
bearings supported by said housing at said inboard end 
portion and an outboard set of bearings supported by 
said housing at said outboard end portion, said outboard 
set of bearings disposed within said volatile environ-
ment, 
electronics for rotating said rotor, 
an impervious ceramic barrier separating said electronics 
and said rotor, and 
a first flexible seal, said first flexible seal disposed axially 
outward from said inboard set of bearings and a second 
flexible seal disposed axially inward from said outboard 
set of bearings, said first flexible seal and said second 
flexible seal preventing said volatile environment from 
contacting said electronics and minimizing vibratory 
and twisting loads upon said ceramic barrierto minimize 
damage to said ceramic barrier wherein said ceramic 
barrier is isolated from said housing. 
2. The motor of claim 1 wherein said volatile environment 
is oxygen. 
3. The motor of claim 1 wherein said ceramic barrier is a 
glass. 
4. The motor of claim 3 wherein said glass is made from 
one of zirconia or alumina. 
5. The motor of claim 1 wherein said ceramic barrier is 
impervious to said volatile environment. 
6. The motor of claim 1 wherein said ceramic barrier is 
non-magnetic. 
7. The motor of claim 6 wherein said ceramic barrier is 
non-metallic. 
8. The motor of claim 1 wherein said inboard set of bear-
ings is disposed within a circular flange extending axially 
outward from said inboard end of said housing. 
9. The apparatus of claim 1 wherein said ceramic barrier is 
frangible. 
10. The motor of claim 1 wherein both the first and second 
flexible seals are axially inward from said second outboard set 
of bearings. 
11. The motor of claim 10 wherein both the first and second 
flexible seals are axially outward from said first inboard set of 
bearings. 
12. An apparatus for use in a volatile environment, said 
apparatus comprising; 
a housing having an inboard end portion and an outboard 
end portion, said outboard end portion extending into 
said volatile environment, 
4 
a rotor configured for exposure to said volatile environ-
ment and disposed in said housing, said rotor supported 
for rotation within said housing in an inboard set of 
bearings supported by said housing at said inboard end 
5 portion and an outboard set of bearings supported by 
said housing at said outboard end portion, said outboard 
set of bearings disposed within said volatile environ-
ment, 
electronics for rotating said rotor, 
10 	
an impervious ceramic barrier separating said electronics 
and said rotor, and 
a pair of flexible seals, a first flexible seal disposed axially 
outward from said inboard set of bearings and a second 
flexible seal disposed axially inward from said outboard 
set of bearings, said first flexible seal and said second 
15 flexible seal preventing said volatile environment from 
contacting said electronics and minimizing vibratory 
and twisting loads upon said ceramic barrierto minimize 
damage to said ceramic barrier andwherein said ceramic 
barrier does not contact said housing. 
20 	 13. The apparatus of claim 12 wherein said volatile envi- 
ronment is oxygen. 
14. The apparatus of claim 12 wherein said ceramic barrier 
is a glass. 
15. The apparatus of claim 14 wherein said glass is made 
25 from one of zirconia or alumina. 
16. The apparatus of claim 12 wherein said ceramic barrier 
is impervious to said volatile environment. 
17. The apparatus of claim 12 wherein said ceramic barrier 
is non-magnetic. 
30 	 18. The apparatus of claim 17 wherein said ceramic barrier 
is non-metallic. 
19. A motor for use in a volatile environment, said motor 
comprising; 
a housing having an inboard end portion and an outboard 
35 end portion, said outboard end portion extending into 
said volatile environment, 
a rotor configured for exposure to said volatile environ-
ment and disposed in said housing, said rotor supported 
for rotation within said housing in an inboard set of 
40 bearings supported by said housing at said inboard end 
portion and an outboard set of bearings supported by 
said housing at said outboard end portion, said outboard 
set of bearings disposed within said volatile environ-
ment, 
45 	 electronics for rotating said rotor, 
an impervious ceramic barrier separating said electronics 
and said rotor wherein said ceramic barrier is made of a 
glass ceramic that is approximately 0.635 mm thick, 
and, 
50 	 a first flexible seal, said first flexible seal disposed axially 
outward from said inboard set of bearings and a second 
flexible seal disposed axially inward from said outboard 
set of bearings, said first flexible seal and said second 
flexible seal preventing said volatile environment from 
55 contacting said electronics and minimizing vibratory 
and twisting loads upon said ceramic barrierto minimize 
damage to said ceramic barrier. 


Implementation of a Non-Metallic Barrier in an Electric Motor

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