Water cooled solenoid capable of producing magnetic field intensities up to 100 kilogaus

Noble, R. M.

Rust, R.

English

NASA Technical Reports Server

Feb. 29, 1967 JAMES E. WEBB 3,305,810 
ABWllNISTRATOR OF TI-IE NATIONAL AERONAUTICS 
AND SPACE ADMINlSTRATlON 
SOLENOID CONSTRUCTION 
Filed Nov, 24, 1964 2 Sheets-Sheet 1 
https://ntrs.nasa.gov/search.jsp?R=19700032613 2020-03-17T02:16:55+00:00Z
Feb. 21, 1967 JAMES E. WEBB 3,305,810 
ADMlNlSTRATOR O F  T H E  N A T I O N A L  A E R O N A U T I C S  
A N D  SPACE ADMIN ISTRATION 
SOLENOID CONSTRUCTION 
Filed Nov. 24, 1964 2 Sheets-Sheet 2 
R U D O L P H  RUS7- 
R O N A L D  Ad, NOBLE- 
I NVEhlTORS, 
3,305,810 United States Patent Ofice 
,a,en,, Fe, ,,, ,,,, 
3,305,810 
SOLENOID (CONSTRUCTION 
James E. Webb, Administrator of the National Aero- 
nautics and Space Administration, with respect to a n  
invention of Rudolph Rust and Ronald M. Noble 
Filed Nov. 24, 1964, Ser. No. 413,662 
5 Claims. (C1. 335-300) 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to  the provisions of Section 305 of the National 
Aeronautics and Space Act of 1958, Public Law 85-568 
(72 Stat. 435; 42 U.S.C. 2457). 
The present invention relates to an improved solenoid 
or electromagnet and is particularly useful, but not limited 
to the construction of electromagnets capable of pro- 
ducing extremely high magnetic field intensities of, for 
example, 100 kilogauss. 
It  is oftentimes desirable to provide a cooling means 
for the winding of an electromagnet. Such cooling means 
usually involves the passage of a cooling medium such 
as, for example, water throngh conduit means which is 
in heat-conductive relationship to the electromagnet wind- 
ing. Because of other considerations, discussed herein, 
such cooling medium was required to have a very low 
electrical conductivity and for that reason, when water 
was used as the cooling medium, it was required that the 
water be distilled water of the required low conductivity. 
This requirement of low conductivity precluded one from 
using a corrosion inhibitor in the water with the re- 
sult that one could not realize the beneficial results of a 
corrosion inhibitor in the cooling water. 
It is therefore a general object of the present invention 
to provide an improved solenoid or electromagnet struc- 
ture which is particularly useful in the production of 
magnetic field intensities in the 100 kilogauss range. 
A specific object of the present invention is to provide 
such a structure which is efficiently cooled by water hav- 
ing a corrosion inhibitor added thereto. 
Another specific object of the present invention is 
to provide a structure of this character which does not 
require pure distilled water as a cooling medium for rea- 
sonably long life or for high efficiency. 
Another specific object of the present invention is to 
provide a structure of this character in which the cool- 
ing medium may have, for example, a resistivity of the 
order of, for example, 300-600 ohm centimeters pro- 
duced, for example, by adding 500 to 1000 parts per 
million of sodium nitrite to the cooling water for corrosion 
prevention. 
Another specific object of the present invention is to  
provide a structure of this character wherein the cool- 
ing medium flows through passageways which are lo- 
cated within each tnrn of the electromagnet coil in con- 
trast to  prior art arrangements wherein the cooling me- 
dium flows around each tnrn of a coil. 
Another specific object of the present invention is to 
provide a structure of this character wherein the cool- 
ing medium flows throngh zero voltage gradient portions 
of an electromagnet whereby the electrical conductivity 
of the cooling medium is prevented from playing a role 
in establishing power losses determinitive of the elec- 
trical efficiency of the structure. 
Another specific object of the present invention is to 
provide a structure of this character in which a structural 
plastic material may be used between coil turns in such 
a manner that the coil can withstand internal stress and 
strain forces along its longitudinal axis far beyond the 
nlaximum allowable in prior art structures, thereby pro- 
viding a much needed safety factor that precludes the pos- 
sibility of adjacent coil turns shorting together. 
Another specific object of the present invention is to 
provide an improved electromagnet having a sandwiched 
winding capable of withstanding large mechanical forces 
created by an intense magnetic field and by expansion and 
contraction as a result of heat, with such winding being 
so constructed that it provides a conduit means for water 
containing a corrosion inhibitor and without the result- 
ing relatively high conductivity of the coolant playing 
a role in developing useless heat, thereby achieving the 
net result of long, safe service life accompanied by high 
electrical efficiency. 
The features of the present invention which are be- 
lieved to be novel are set forth with particularity in the 
appended claims. This invention itself, both as to its 
organization and manner of operation, together with 
further objects and advantages thereof, may be best nn- 
derstood by reference to the following description taken 
in connection with the accompanying drawings, in which: 
FIG. 1 is a perspective view of a structure embodying 
features of the present invention, with a portion of the 
same broken away for purposes of showing internal con- 
struction. 
FIG. 2 shows, in enlarged form, some of the struc- 
ture disclosed also in FIG. 1, this particular view being 
somewhat schematic in that it is intended to portray a 
projection, in one plane, of complete turns of the coil 
shown in FIG. 1, as indicated by the 360" dimension 
line therein. 
FIG. 3 is generally a top plan view of the coil in the 
assembly shown in FIG. 1 and illustrates the orientation 
o i  bolts and spacers. 
The electromagnet shown in FIG. 1 includes generally 
three major sections, namely: the coolant inlet reservoir 
or manifold section 10; the center coil section 11 which 
includes an outer cylindrical flanged housing member 
13 around the coil structure 14, such coil structure 14 
having electrical terminals in the form of a pair of spaced 
bus bars 16 and 17 capable of conducting electrical cur- 
rents in the order of 10,000 to 100,000 amperes; and an 
upper coolant outlet reservoir or manifold section 18. 
The lower section 10 includes generally a flanged cup- 
shaped member 20 having a pair of coolant conduits 22 
and 23 extending out of its base portion 24 whereby 
coolant may be introduced through a pair of apertnred 
portions, one of which is illustrated at 26 in the base 
portion 24. The bus bar 17 effectively forms the top of 
the reservoir section 10, besides serving, as mentioned 
previously, as one terminal of the electromagnet coil. 
It  is observed that the bus bar 17 has a circular apertnred 
portion 17A through which the coolant may flow in an 
upward direction, as indicated by the arrows 25. It  is 
also observed that the bus bar 17 is sandwiched be- 
tween adjacent flanged portions 20A and 13A of the 
housing members 20 and 13, respectively, so as to pro- 
vide a watertight joint, and for this latter purpose, gasket 
means may be provided in such joint for not only assur- 
ing a fluid-tight joint, but also to electrically insulate the 
coil terminal or (bus bar 1'7 from the housing, particularly 
when the housing elements are of electrically conducting 
material. 
The upper bus bar 16 is sandwiched in like fashion 
between the upper flanged portion 13B of housing mem- 
ber 13 and the adjacent flanged portion 28A of the up- 
per nlanifold member 28 to thereby provide a second 
watertight joint. This member 28 is formed with an 
apertured base portion 28B which is substantially co- 
planar with the web portion 28A and which is joined 
thereto by an annular section 28C of generally inverted 
U-shaped cross-section, as shown in FIG. 1, this section 
28C being formed with a plurality of circumferentially 
spaced support fins 28D and being in comn~unication with 
3,305,810 
3 4 
coolant outlet tubes or conduits 30 extending radially spirals 40, 41 spaced by the spacer means 43 cornprise 
outwardly therefrom. the turns of the coil. Such spacer means 43 extends 
The coil structure 14 is formed in a special manner generally radially in the coil and defines with each of 
now described in connection with FIGS. 2 and 3.  In such turns radial fluid flow passages extending radially 
general, a coil is formed having its turns arranged in a 5 th~ough the coil. Fluid within such radial fluid flow 
spiral along the axis of the electromagnet, such spiral passages is thus in a region wherein there is substantial- 
being actually two copper spirals in parallel with an in- ly zero electrical potential gradient. Thus, the cooling 
tervening space therebetween through which the coolant fluid flowing through such passages may have a high 
can flow in a general radially and outwardly direction. electrical conductivity without substantially an electrical 
Thus, as shown in FIG. 2, the coil is formed using two energy being produced therein. This feature thus allows 
interleaved spiral conductors 40 and 41 with radially one to use an additive to the cooling medium such as, 
extending and spaced spacers $3 defining radial coolant for example, a corrosion inhibitor which, when added, 
passageways 45. Rings 47 of insulating material, i.e., results in the cooling medium having substantial electrical 
of structural plastic capable of withstanding large com- conductivity. Thus, the solenoid may be operated with 
pressive forces, and of substantially the same thickness 15 a corrosion inhibitor in the cooling medium for long life 
as the thickness of spacers 43 serve to insulate adjacent and yet with high electrical efficiency. 
turns of the coil. The spacers 43 may be and preferably While the particular embodiments of the present in- 
are of good electrical conducting material since their vention have been shown and described, it will be obvious 
purpose is to separate those portions of the spirals ~$0  to those skilled in the art that changes and n~odifications 
and 41 which are of the same electrical potential. 20 may be made without departing from this invention in 
In other words, the spacers 43 and those portions of its broader aspects and, therefore, the aim in the appended 
the interleaved spiral windings 40 and 41 contacted by claims is to cover all such changes and nlodifications as 
the same comprise the coil windings, the turns of which fall within the true spirit and scope of this invention. 
are insulated by the ring-shaped spacers 47. We claim: 
Suitable electrical connections are made at the ends 23 1. In a solenoid construction, a coil; said coil includ- 
of the coil thus formed to its terminals, i.e., the bus bars ing two interleaved spaced spirals of generally flat con- 
16 and 17, and in some cases this may be accomplished ducting material with the planes of the flat material of 
simply by clamping the bus bars 16 and 17 against the said spirals extending generally parallel; insulating ma- 
ends of the coil, and in some cases such bus bars may terial between a first series of alternate spacings between 
be bonded to the coil ends as, for example, by welding, 30 adjacent convolutions of said spirals; spacer means be- 
brazing, silver soldering, or the like. tween a second series of alternate spacings between ad- 
The assembly may be releasably secured together using jacent convolutions of said spirals; the last mentioned 
the following described construction. In FIG. 3, a series ~ o n ~ ~ l u t i o n s  spaced by spacer means comprising the 
of circumferentially spaced clamping bolts 50 extend turns of said coil; said spacer means extending generally 
longitudinally through oversized aligned holes in the 33 radially of said coil and defining with each of said turns 
spiral convolutions and between spacers $3 and are elec- a radial fluid flow passage extending radially of the coil, 
trically insulated also from the coil ends using for that said spacer means comprising a series of radially extend- 
purpose insulating washers 52 of ceramic material. ing metallic bars contacting said adjacent convolutions 
The housing is releasably secured together using the which define a turn of said coil. 
construction sholvn in FIG. 1 wherein a bolt 60 suit- 40 2. In a solenoid ~0nstr~~ti011,  a coil; said coil incl~ld- 
ably secured at its lower end to the manifold member in:: two interleaved spaced spirals of generally flat con- 
20 extends upwardly through the assenlbly and has its ducting material with the planes of the flat material of 
upper end threaded to receive a flanged nut 62 engai,"e- said spirals extending generally parallel; insulating ma- 
able with the top side of the manifold base 2$B, the terial )between a first series of alternate spacings between 
lower side of the base 28B engaging a spacer ring 44 4j adjacent ~ 0 n ~ 0 l u t i 0 n ~  of said spirals; spacer means be- 
which may be of insulating material and of tween a second series of alternate spacings between ad- 
the same thickness as the thickness of the bus bar 16. jacent ~onvolLIti0n~ of said spirals; the last mentioned 
To assure rigid clamping of all of the elements when c~nv~lu t ions  spaced by spacer means comprising the 
the nut 62 is tightened and to assure a good watertight turns of said coil; said spacer means extending generally 
joint between flange 2$A and the bus bar 16, a resilient 50 radially of said coil and defining with each of said turns 
gasket member may be interposed between the two latter a radial fluid flow Passage extending radially of the 
elements; likewise, resilient gasket means may be suit- coil, a cylindrical housing having flanged end portions 
ably interposed for the same purposes, as indicated sur"unding and spaced from said coil and defining an 
previously, at the lower manifold joint. annular fluid flow passage therewith in communication 
It  will be observed that a coolant may be pumped 55 with said radial fluid flow Passage; a first generally cup- 
through the assembly, with the coolant taking the follow- shaped manifold having a flanged portion; a second gen- 
ing general path, namely: from the inlet tubes 22 and erally cup-shaped manifold having a flanged portion; 
23, through openings 26 (only one of which is shown) a first bus bar sandwiched between one of said housing 
into the manifold member 20, through the apertmed flanges and said flanged portion of said first manifold 
portion 17A and then radially outwardly through the 60 and connected to one end of said coil to provide a first 
twelve radial channels $5 (FIG. 2)  into the annular space terminal therefor; a second bus bar sandwiched between 
70 between the coil structure 14 and the housing mem- the other of said housing flanges and said flanges Par- 
her 13, through the circumfeleniially spaced apeltured tion of said second manifold and connected to the other 
portions 16A in the bus bar 16, into the manifold mem- end of said coil to provide a second terminal therefor; 
ber 28 and then outwardly through the outlet tubes 36). 63 said first bus bar being centrally a~ertured to provide 
Thus, the present invention involves a solelloid con- a flow opening communicating said first manifold with 
struction in which its coil includes two interleaved spaced the central portion of said coil; said second bus bar 
spirals 40, 41 of @nerally flat conducting material and being apertured to intercommunicate said annular flow 
with the planes of the flat material of such spirals extend- Passage with said second manifold; and conduit means 
ing generally parallel. Insulating nlaterial 47 in tl-ie 70 extending from each of said first and second manifolds, 
form of an apertured disc is disposed between a first 3. A construction as set forth in claim 2, in whicl~ 
series of alternate spacings between adjacent convolu- fastening means extends longitudinally through said coil 
tions of such spirals, with spacer means 43 between a and interconnects said manifolds. 
second series of alternate spacings between adjacent 4. A construction as set forth in claim 3, in which 
convolutions of such spirals. Those convolutions of 76 said fastening means is threaded at one of its ends and 
3,305,810 
5 6 
mates with a nut element for releasably clamping said said spacer means comprising a series of radially extend- 
terminals between said cylindrical housing and a cor- ing bars contacting said adjacent convolutions which de- 
responding one of said manifolds. fine a turn of said coil. 
5. In  a solenoid construction, a coil; said coil includ- 
ing two interleaved spaced spirals of generally flat con- References Cited by the Examiner 
ducting material with the planes of the flat material 
of said spirals extending generally parallel; insulating UNITED STATES PATENTS 
material between a first series of alternate spacings be- 964,167 11/1910 Mayer ------------- 336-185 
tween adjacent convolutions of said spirals; spacer means 199129903 Long ----------- ----- 336--60 
between a second series of alternate spacings between ad- , _ 33086,184 4'1963 ------------- 336-60 
- - jacent convolutions of raid spirals; the last mentioned '" BERNARD A, GILH,mNY, Examir,er. 
convolutions spaced by spacer means comprising the 
turns of said coil; said spacer means extending generally 
radial'ly of said coil and defining with each of said turns G. HAlRRIS, Assistant Examiner. 
a radial fluid flow passage extending radially of the coil, 


Solenoid construction Patent

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