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Jan. 19, 1954 j. G. Howard Etal 2,666,657
CORROSION-RESISTING FLEXIBLE CONNECTOR
Filed Feb. 17, 1950
tfbhn G. Howard Raymond H. Thomas
UNITED STATES PATENT OFFICE
John G. Howard and Raymond Harry Thomas,
Chicago, III., assignors to The Pyle-National
Company, Chicago, III., a corporation of New
Application February 17,1950, Serial No. 144,714
3 Claims. (CL 285—206)
This invention relates generally to a flexible electrical connector as is frequently employed between an electrical conduit and an operating mechanism, or between two electrical conduits which must be placed in communication with one another.
More specifically, the present invention relates to a novel corrosion-resisting flexible connector and a process for making such a structure, all of the elements employed in the structure being made of such a material as to effectively resist the deleterious effect of exposure to an environment in which harmful or dangerous corrosion occurs.
Flexible fittings have been provided heretofore which were particularly designed to fulfill the safety requirements attendant upon the use of such fittings in a hazardous location, for example, a location where an explosive mixture is likely to prevail in the atmosphere surrounding the electrical fittings. Such fittings have usually been made out of ordinary metals which are not corrosion-resistant and have been fabricated in a conventional manner by use of ordinary welding or brazing or soldering procedures.
A fitting of this nature, of course, is seriously deficient if it is necessary to employ the flexible electrical fitting in an environment where not only are explosive mixtures likely to be present, but the atmosphere surrounding the fittings is likely to contain corrosive substances which attack the elements of the electrical fitting as well as the welded, brazed or soldered joints connecting the various elements.
According to the general features of the present invention, a corrosion-resistant flexible electrical connection fitting is provided having a novel end fitting structure which permits the fitting to be manufactured according to a unique and efficient process.
A metal bellows-like tube, a flexible braided metal sleeve and a ring-like end fitting are assembled in concentrically disposed array and a metal coupling connector is placed in abutting relationship thereto. All of these elements are made of a suitable corrosion-resistant metal such as stainless steel or the like. An electric-arc welding process is then employed to integrate all of the aforementioned elements. The welded joints are also resistant to attack by corrosive substances. The inner bore of the bellows-like tube is then lined with a tubular loom of flexible electrically non-conductive material and the loom is locked against axial displacement to complete the assembly of the fitting.
It is, therefore, an object of the present in
vention to provide a corrosion-resistant electrical connection fitting which overcomes the deficiencies of flexible fittings heretofore provided.
Another object of the present invention is to 5 provide a process for making a corrosion-resistant flexible electrical connection fitting by which the fitting may be suitably lined with a flexible electrically non-conductive material, but during the assembly of which, the lined material will not 10 be consumed or damaged because of exposure to excessive temperatures.
A further object of the present invention is to provide a flexible electrical connection fitting which will not only offer protection against ex15 plosion hazards, but will, in addition, resist attack by corrosive substances surrounding the fitting.
Another object of the present invention is to
provide an explosion-proof, corrosion-resistant,
20 flexible, electrical, connecting fitting which is
durable in use and which may be economically
Many other features, advantages and additional objects of the present invention will become 25 manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying drawings in which
Figure 1 is an elevational view of an explosionproof, corrosion-resistant electrical connection so fitting according to the present invention;
Figure 2 is a slightly enlarged cross-sectional view, broken in part, of the fitting shown in Figure 1;
Figure 3 is an enlarged cross-sectional exploded .35 view showing additional details of construction and helping to explain the steps of the process of the present invention; and
Figure 4 is a fragmentary cross-sectional view of an alternative embodiment of the present in40 vention.
As shown on the drawings: In providing a flexible electrical connection fitting, it is necessary to employ a body portion which is flexible to a marked degree and which 45 will be expansible without damage in the event the body is exposed to the shock of an explosion. The body must also effect a flame-proof seal of the conductors enclosed thereby to preclude inadvertent ignition of explosive mixtures sur50 rounding the fitting.
It will be readily apparent, however,s that
the body must also be so substantial and so strong
that should an arcing occur within the body of
the fitting, there must be no danger of burning
55 through the body wall.
In meeting these difficulties, flexible fittings
have heretofore been provided which include a
flexible bellows-like tube surrounded by a flexible
metal braid to comprise the body portion of the
fitting. A tubular loom of flexible electrically
non-conductive material has been used to line 5
the inside of the'tube to prevent burn-through
of the tube walls.
In constructing a corrosion-resistant fitting;
additional problems are presented. Ordinary
joints provided by electric weldirig,'>gas'''we'Id-ffigV"t}6
brazing, or soldering are all susceptible to 8e-
struction when subjected to the attack of cor-
rosive substances. Thus, even" if "a- substi'tufipri
of materials were made so that* ffie flexible braid-.
may be employed to integrate the coupling connectors IS and 17, the rings 13 and 14, the bellows-like tube 11 and the flexible braided sleeve 12, thereby producing a pair of welded joints indicated generally by the reference numeral 19, 19'..(Fig. 2). , . • .
After all of the aforementioned elements have begn placed in firm assembly with one another by welding, the inside bore of the bellows-like tube I i'isline d- with a flexible tubular loom preferably made-of an electrically non-conductive material indicated generally; by the reference numeral 20. .After the loom- 20:has been positioned within ttie-littin'g, it-is locked against axial displace
ed sleeve and the bellows-like tube were made of 15 ment. As shown••'lit"the embodiment of Figures
corrosive-resistant material, the fitting would 2 and. 3, the female^ coupling connector 16 is
be deficient because the joints1 would'bV-subjebt' provided with an annular ring-seating groove to deterioration and hence, the fitting would not fulfill the safety requirements necessary for em
16e and'a!pair of resilient snap rings 2i, 21 are seated in the seating groove 16c of the female
ployment in a hazardous location. 20 coupling connector 16,-as welt as in the seating
"On the other hand, if special'"techniques"are groove 176 of the ring J7 in substantial abutting erilployed in
producing a corrosion-resistant joint, for example, the technique of stainless steel welding, the heat produced during the course of the welding procedure is so excessive as 25 to consume or seriously damage the tubular loom lining the inside of the bellows-like tube. In such circumstances, the fitting is also deficient since for safety purposes, the tubular loom should
relationship to the ends of the loom 20, thereby precluding axial displacement of the loom 20 relative to the other elements of the fitting 10.
In the alternative embodiment of Figure 4, no intermediate element corresponding to the ring 17 is provided and a male coupling connector 22 having a smooth bore 22a and an externally threaded portion 226 is-integrated 'directly with
present an unbroken tubular bore for'the elec- 30 a bellows-like tube II', a flexible braided sleeve
trical conductors which are passed through the fitting.
The process arid the structure of the present invention completely avoid all of the difficulties outlined.
As-may be seen upon inaking reference to the drawings, the present invention contemplates the provision of an explbsion-proof corrosionresistant flexible electrical connection fitting
12' and a ring i4' by means of a welded joint 19'. After the tube I!' is lined: with a loom 20', the loom 20' is locked in axial displacement by press fitting a taushing-23 into the:bore-22a" of.the" male coupling connector 22 into'abutting relationship with the loom 20'.
As a further alternative in the process of making the fitting of the present invention, the bushing 23 and the bore 22a of the male coupling con
which is indicated generally by the reference 40 nector 22 can be dimensionally related so that the
numeral 10. A bellows-like tube II made of a corrosion-resistant metal such as stainless steel or the like is provided and a flexible metal braided sleeve 12, also made of a cofrosiofi-resist'arit
bushing 23 may be placed in-firm-assembly within the male coupling connector 22 with a shrink fit.
It may also be noted that the ring-17 and'the metal such as stainless steel or the like,'is place'd. 45 male coupling connector (8 shown in the emin surrounding relationship to the tube'I. I', bodiment of Figures 1, 2 and 3 may be integrated'
At each end of this sub-assembly and in con- with one another by-press fitting-or shrink fitcentric relationship thereto is placed a' metal end ting as desired.
fitting preferably made of a corrosion-resistant It will be evident that the process of making
metal such as stainless steel or the like. As shown 50 a flexible fitting as described completely elimiin this particular embodiment, the end fittings nates the necessity of exposing the looms 20 or include'a ring 13 and a ring 14: 20' to the excessive temperatures developed dur
A metal coupling connector made of a cor- ing a welding process. Moreover, it will be evirosion-resistant metal stich as stainless steel is dent that all of the elements embodied in the then placed in abutting relationship to the pre-.55 fitting of this invention which are exposed to viously assembled elements. As showri'iri this atmospheric conditions including 'the welded
particular embodiment, a female coupling connector (6: is provided on one :end which defines an'internal bore partially' threaded as at' f Giz arid smooth portion as at 16&.
A ring 17 is situated on the opposite 'end of the fitting and defines an external surface suitable for reception in a male coupling connector 18 having a cOunterbOre portion IBa arid a
joints 19 and 19',-are made of corrosion-resistant metal and are, therefore, capable of withstanding attack by corrosive substances. Thus, 60 we have described a fitting which will successfully operate in-a corrosive atmosphere without danger of decreasing the explosion-proof characteristics thereof. It is contemplated that various persons 'skilled
smooth bore 18'b with an externality threaded <65 in tne ar* might suggest minor modifications to
portion i'8£ The ring 17 defines a smooth bore the preferred embodiment herein shown and de
I7a with an annular ring-seating .groove I7b scribed in detail for the sake of clarity, however,
formed adjacent one end thereof. Jt should be understood that we wish to embody
it may be noted that the bore 16b of'the female within the scope of this patent all such ernbodi
coupling connector and the bore I7a of the ring 70 merits as come within the scope of our contri
17 are approximately eqUal in-diameter to the tautibn to the art.
diameter of the innermost undulations defined We elaim as our invention:
by the'bellows-like tube II. 1- A corrosion-resistant-flexible electrical'con
An"eie'ctric-arc'weldiiig process,.preferably ac- duit comprising, inner; outer, -and"-intermediate
cording to a stainless steel welding technique,- 75 concentric sleeves consisting of a flexible cor2,666,687
rosion resistant metal braided sleeve, a flexible tubular loom of electrically non-conductive, heat consumable material, and a flexible bellows-like corrosion-resistant metal tube, respectively, a female coupling connector having a bore extend- 5 ing therethrough of larger diameter than said loom but of smaller diameter than said tube, a protective ring surrounding the end of said concentric sleeves adjacent said coupling connector, an annular welded joint of corrosion-resistant 10 metal integrating by high temperature thermal fusion said coupling connector, said ring, said braided sleeve, and said tube, and a retainer member inserted in said bore of said coupling connector and in firm assembly therewith and being 15 of smaller diameter than said loom, said loom being inserted through said bore of said coupling connector only after said welded joint is sufficiently cooled to preclude consumption of said loom, and said retainer being inserted in said 20 bore to retain said loom in said conduit.
2. A corrosion-resistant flexible electrical conduit as defined in claim 1 wherein said retainer
member comprises a bushing fitted in firm assembly within said bore of said coupling connector.
3. A corrosion-resistant flexible electrical conduit as defined in claim 1, said bore having an annular recess formed therein, and said retainer member more specifically comprising a snap ring seated in said annular recess for abutting said tubular loom.
JOHN G. HOWARD.
RAYMOND HARRY THOMAS.
References Cited in the file of this patent UNITED STATES PATENTS
Number Name Date
1,993,984 Wulle et al. Mar. 12, 1935
2,025,545 Muff Dec. 24, 1935
2,360,608 Kauffman Oct. 17, 1944
2,449,356 Wikoff Sept. 14, 1948
2,451,438 Hartman Oct. 12, 1948
2,452,057 Kehoe Oct. 26, 1948
2,516,631 Jacobson July 25, 1950