U.S. patent number 3,617,614 [Application Number 05/002,839] was granted by the patent office on 1971-11-02 for explosion-proof electrical connector and cable assembly.
This patent grant is currently assigned to William M. Wilson's Sons, Inc.. Invention is credited to William J. Henry.
United States Patent |
3,617,614 |
Henry |
November 2, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
EXPLOSION-PROOF ELECTRICAL CONNECTOR AND CABLE ASSEMBLY
Abstract
A greatly simplified explosion-proof fitting for use
particularly in the petroleum industry comprises a minimal number
of parts including a conductor passing through a housing, a sealer
and a strain relief member. The housing is crimped about the strain
relief member to retain the conductor in position.
Inventors: |
Henry; William J. (Doylestown,
PA) |
Assignee: |
William M. Wilson's Sons, Inc.
(Lansdale, PA)
|
Family
ID: |
21702771 |
Appl.
No.: |
05/002,839 |
Filed: |
January 14, 1970 |
Current U.S.
Class: |
174/77R; 174/652;
439/452 |
Current CPC
Class: |
H01B
17/306 (20130101); H02G 3/0616 (20130101) |
Current International
Class: |
H01B
17/26 (20060101); H01B 17/30 (20060101); H02G
3/06 (20060101); H02G 3/02 (20060101); H02g
015/04 () |
Field of
Search: |
;174/65,65.1,74,75,75.2,76,77 ;339/89,89C,101,102,103,177C
;310/71,87,88 ;29/629,630 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Askin; Laramie E.
Claims
What is claimed is:
1. A connector and cable assembly comprising: an electrical cable;
a connector having an elongated body with a threaded portion at one
end, having a substantially cylindrical hole passing therethrough,
a centrally located portion providing a means for engagement with a
tool whereby said body can be secured in threaded engagement in a
hole in its intended environment, and an elongated thin-walled
substantially cylindrical portion at the other end having a
substantially cylindrical hole passing therethrough, said hole
being of a greater diameter than said last-mentioned hole, said
holes terminating in a common plane providing an annular shoulder
in said body, said holes being in axial communication with one
another; said cable passing through said holes in said connector; a
fiber washer disposed against said shoulder; at least a portion of
said cable engaging said washer; a resilient strain relief member
disposed about said cable within said hole passing through said
thin-walled portion of said body; said thin-walled portion being
crimped to engage said strain relief member and force it against
said cable to hold said connector in longitudinal position on said
cable; and a sealing material disposed in the hole on the threaded
portion of said body to provide a vaportight seal between said
connector and said cable.
Description
BACKGROUND OF THE INVENTION
This invention pertains to electrical fittings for use particularly
in holding a cable in position on the frames of motors. More
particularly this invention concerns an explosion-proof fitting,
that is, a fitting for use on explosion-proof motors such as the
type used for installations in volatile gaseous environmental
conditions.
Fittings of this type have been known for many years and normally
consist of a great number of parts which are accurately machined
and require careful assembling all of which makes them rather
expensive.
The following prior art patents are representative of the state of
the art:
---------------------------------------------------------------------------
U.S. Pat. No. Inventor Issued
__________________________________________________________________________
2,604,315 Hargett July 29, 1952 2,684,398 Strunk July 20, 1954
2,759,989 Anderson Aug. 21, 1956 2,881,241 Stecher Apr. 7, 1959
2,939,906 Harwood June 7, 1960 3,055,972 Peterson Sept. 25, 1962
3,072,415 Lombard et al. Jan. 8, 1963 3,163,703 McLoad Dec. 29,
1964 3,314,030 Mallett et al. Apr. 11, 1967 3,371,150 Bachman Feb.
27, 1968.
As can be seen from these patents the structure is generally rather
complicated and it is therefore most desirable particularly from an
economic standpoint that a simplified device be provided which will
perform satisfactorily in the intended environment.
SUMMARY OF THE INVENTION
I have provided a simple and relatively inexpensive fitting for use
in explosive environments comprising a connector through which an
electrical cable is passed, said connector being retained on the
cable. At one end of the connector the cable is sealed by a sealing
compound and at the other end of the connector a strain relief
member is disposed around the cable between the cable and the
connector body and the body is crimped over to retain the connector
in place. It is preferable to provide a washer between the end of
the cable insulation and an inner annular shoulder in the connector
body.
Accordingly, it is an object of this invention to provide a new and
improved explosion-proof fitting of the type described which
includes a minimal number of parts and yet performs satisfactorily
in its intended environment.
This and other objects of my invention will become apparent from
the following description with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of the parts of the fitting
and the cable which goes through the fitting shown prior to being
assembled;
FIG. 2 is a section of the parts shown in FIG. 1 shown after they
have been assembled; and
FIG. 3 is a section taken along the lines and arrows 3--3 in FIG.
2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Although specific forms of the invention have been selected for
illustration in the drawings, and the following description is
drawn in specific terms for the purpose of describing these forms
of the invention, this description is not intended to limit the
scope of the invention which is defined in the appended claims.
FIG. 1 shows the unassembled parts of the connector together with a
portion of a cable upon which the connector is to be mounted. The
cable 10 is a standard three-wire cable having three separate wires
11, 12 and 13 therein, each of which has its own insulation as
shown. The wires pass through an outer insulation 15.
The explosion-proof fitting comprises a connector designated
generally 16 having a threaded portion 17 at one end for insertion
into a mating threaded hole in a motor housing, a centrally
disposed enlarged hexagonal portion 18 which provides a means for
permitting the fitting to be gripped by a wrench or similar device
so that the threaded portion can be tightened into the housing as
aforesaid, and an elongated thin-walled tubular portion 19 at the
other end which is preferably cylindrical in its condition prior to
being assembled and fixed to the cable 10.
The threaded portion 17 has a standard external tapered thread 20
thereon and a cylindrical hole 22 passing therethrough. The hole 20
terminates within the central hexagonal portion 18 of the connector
16 in an outwardly extending annular shoulder 24. This shoulder is
located at one end of the cylindrical hole 26 in FIG. 1 which
passes through the thin-walled tubular portion 19. After complete
assembly this hole 26 is no longer cylindrical and therefore has
been designated 126 in FIGS. 2 and 3.
Prior to assembling the cable with the connector, the cable is
first stripped of a portion of its outer covering 15 so then enough
of the insulated conductors 11, 12 and 13 extend from the cable to
pass through the connector and extend beyond it for the ultimate
purpose of being connected to the electric fittings in the
machinery. In stripping the outer insulation covering 15 from the
cable there is provided a shoulder 30.
When this shoulder is fully inserted into the fitting it rests
against the fiber washer 32 in FIG. 2. This washer is designed to
fit within the confines of the overall diameter of the hole 26 and
rest against the shoulder 24 of the fitting and at the same time
provide a clearance hole for the insulated conductors 11, 12 and
13. The washer 32 provides a dam for the sealer 60, as will be more
fully described hereinafter.
The parts can be assembled by first placing the fiber washer 32
against the shoulder 24 of the fitting. Next the cable strain
relief member 34, which is made of resilient material such as
buna-N or neoprene hose of the type commonly known in the trade
being resistant to gasoline and oil, is placed about the insulation
covering 15 of the cable. The conductors are then inserted through
the hole in the center of the fiber washer 32 and the cable is fed
through the fitting until the shoulder 30 of the insulated covering
of the cable engages the washer 32. The cable strain relief member
is also pushed up against the washer 32. The diameter of this
member is less than the diameter of the hole 26 in FIG. 1.
With the parts thus assembled the cylindrical portion 19 of the
fitting is crimped, preferably in three places, so that its
external appearance in section is that shown in FIG. 3. That is,
the cylindrical walls are deformed inwardly along three major arcs,
and portions of the metal are forced outwardly as at 40, 42 and 44.
This has the effect of deforming the strain relief member 34; such
deformation being shown at 50 in FIG. 2. The crimping must be
sufficient to firmly grip the strain relief member and compress it
against the insulation 15 of the cable thereby restraining the
cable from longitudinal movement with respect to the fitting.
As a final step, a sealing compound 60 is forced into the open end
of the fitting around the conductors completely filling the hole 22
and packing against the washer 32 and the cable. The sealing
compound may be of any type as is known in the art and must be free
of voids and provide a tight fit in the connector all around the
insulated conductors to provide a vaportight seal.
To provide those skilled in the art with a typical set of
dimensions in order that they may appreciate the extent of the
crimping operation, I will now deliniate very specifically the
dimensions in inches used on one cable and connector assembly made
in accordance with my invention. The cylindrical portion 19 of the
fitting was 1-inch long and had an outside diameter of 0.906 .+-.
0.005 and an inside diameter of
The cable strain relief member had an outside diameter of 0.765
.+-. 0.005 and an inside diameter of
The washer 32 had an outside diameter of
and an inside diameter of 0.375.+-. 0.005. The cable used was a
neoprene covered three conductor 14 AWG stranded wire 600-volt
rating. After assembly the portion 19 was crimped securely in three
places to secure a vaportight seal as shown and described above.
After crimping, the outside diameter of the arcuate portions was
approximately in the range of 0.815 to 0.830 inch.
It will be understood that various changes in the details,
materials and arrangement of parts which have been described and
illustrated in order to explain the nature of this invention, may
be made by those skilled in the art within the principle and scope
of the invention as expressed in the following claims.
It will further be understood that the "Abstract of the Disclosure"
set forth above is intended to provide a nonlegal technical
statement of the contents of the disclosure in compliance with the
Rules of Practice of the U.S. Pat. Office, and is not intended to
limit the scope of the invention described and claimed herein.
* * * * *