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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to an electrical connector assembly of the type
having a pair of mateable cylindrical shells secured together by a
rotatable coupling ring and, more particularly, to an improved decoupling
retardation mechanism for such an assembly which acts to negate
vibrational effects tending to decouple the shells.
There is a continuing need to improve electrical connectors so that they
meet rigid performance standards imposed by severe environmental
requirements established by aerospace applications. During desired mating
and unmating, the electrical connectors should be easily and quickly
coupled and decoupled with the use of reasonable forces. Once mated and in
use, however, electrical connector assemblies must remain connected
despite vibrational and/or other forces which might be applied to the
connector assembly and which might tend to decouple the connectors.
There have been numerous approaches in the past which have addressed the
problem of maintaining an assembled pair of cylindrical electrical
connectors together. One such approach is disclosed in U.S. Pat. No.
4,648,670, which in its specification discusses other patents which
disclose other approaches. For various reasons, it remains a desire in the
industry to provide an approach that achieves the substantial retardation
forces needed to satisfy the present-day strict requirements established
for aerospace applications.
It is therefore an object of the present invention to provide an electrical
connector assembly of simple construction which has an improved decoupling
retardation mechanism which allows desired coupling and decoupling but
resists a substantial torque to prevent unwanted decoupling due to
vibration and the like.
SUMMARY OF THE INVENTION
The foregoing and additional objects are attained in accordance with the
present invention by providing an electrical connector assembly which
comprises an electrical plug connector subassembly including a
substantially cylindrical first shell having one or more first electrical
contacts secured in a dielectric insert therein, and an electrical
receptacle connector subassembly including a substantially cylindrical
second shell having one or more second electrical contacts secured in a
dielectric insert therein and mateable with the first contact in the first
shell. The second shell has an external thread on a forward portion that
is received over the forward portion of the first shell during connector
mating. A coupling ring is rotatably mounted on the first shell and
restrained from axial movement with respect thereto. The coupling ring is
adapted to selectively couple and decouple the first shell and the second
shell, and has an interior wall provided with an internal thread
connectable with the external thread on the second shell for connecting
the first and second shells together and thereby holding the first and
second contacts in mated relationship.
According to this invention, there is provided means for retarding
rotational movement of the coupling ring with respect to the first shell.
The retarding means comprises an annular region extending around the
interior of the coupling ring and having an inner circumferential surface
provided with a plurality of engageable teeth. Each of the teeth has first
and second generally straight sides meeting at an apex. The first side has
a steeper angle than the second side, with the first side leading the
second side when the coupling ring is rotated to decouple the first shell
from the second shell. The retarding means also comprises an annular
channel formed by an inwardly extending wall of the coupling ring and an
outwardly extending wall of the first shell. The channel is so located
that the teeth occupy its outer surface between the walls. The retarding
means also comprises a leaf spring member having a central portion mounted
to the first shell within the channel and a pair of wings extending within
the channel in opposite directions from the central portion each to a
respective distal end disposed against the exterior of the first shell.
Each of the wings has a radially outwardly extending projection having
first and second sides at angles complementary to the first and second
sides of the teeth, that engage the teeth to retard rotational movement of
the coupling ring. Because of the differing steepness of the sides of the
teeth, more torque is required to decouple the shells than to couple the
shells.
In accordance with an aspect of this invention, each of the wings has a
first generally arcuate portion extending from the central portion and
disposed against the exterior of the first shell within the channel, and a
second portion between the first portion and the distal end of each wing
which is raised away from the exterior of the first shell, with the
projection being on the second portion.
In accordance with another aspect of this invention, the exterior of the
first shell within the channel is flatted under the second portion of each
of the wings.
In accordance with a further aspect of this invention, the retarding means
comprises a pair of the leaf spring members disposed on the first shell
diametrically opposite each other.
In accordance with yet another aspect of this invention, the width of the
channel in the axial direction provides slight clearance for the leaf
spring member and prevents the leaf spring from skewing.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing will be more readily apparent upon reading the following
description in conjunction with the drawings in which like elements in
different figures thereof are identified by the same reference numeral and
wherein:
FIG. 1 is a cross sectional view of a partially mated electrical connector
assembly according to the present invention taken along the line 1--1 in
FIG. 2;
FIG. 2 is a cross sectional view taken along the line 2--2 in FIG. 1;
FIGS. 3 and 4 are isometric views taken from different angles of a first
embodiment of a leaf spring member for use in the assembly of FIG. 1;
FIG. 5 is a plan view of a blank for forming a second embodiment of a leaf
spring member for use in the assembly of FIG. 1; and
FIG. 6 is a side view of the second embodiment of the leaf spring member
formed from the blank shown in FIG. 5.
DETAILED DESCRIPTION
Referring now to the drawings, FIG. 1 shows an electrical connector
assembly, designated generally by the reference numeral 10, constructed in
accordance with the principles of this invention to include an improved
decoupling retardation mechanism. As its main components, the assembly 10
includes an electrical plug connector subassembly 12, an electrical
receptacle connector subassembly 14, and a coupling ring 16. As is
conventional, the plug subassembly 12 includes a substantially cylindrical
first shell 18 within which is secured at least one electrical contact 20.
The receptacle subassembly 14 includes a substantially cylindrical second
shell 22 having secured therein at least one electrical contact 24
mateable with the contact(s) 20 of the plug subassembly. The shell 22 is
formed at its forward mating end with an external thread 26. The coupling
ring 16 is rotatably mounted on the first shell 18 and is restrained from
axial movement with respect thereto. An interior wall of the coupling ring
16 has an internal thread 28 connectable with the external thread 26 of
the shell 22 for pulling the first and second shells 18, 22 together when
the coupling ring 16 is rotated to thereby hold the contacts 20, 24 in
mated relationship. The contacts 20, 24 are connected to wires formed into
respective plug and receptacle cables which extend from the rear ends of
the plug and receptacle subassemblies, respectively. The foregoing is
conventional and well known in the art.
In accordance with this invention, an improved mechanism for retarding
rotation of the coupling ring 16 with respect to the plug shell 18 is
provided. The retardation mechanism includes an annular region 30
extending around the interior of the coupling ring 16. The annular region
30 has an inner circumferential surface 32 provided with a plurality of
engageable teeth 34. As shown in FIG. 2, each of the teeth 34 has a
generally straight first side 36 and a generally straight second side 38,
with a pair of sides 36, 38 meeting at an apex, or crest, of each tooth
34. When viewed as in FIG. 2, the coupling ring 16 is rotated clockwise
for coupling the first shell 18 to the second shell 22, and is rotated
counterclockwise for decoupling the first shell 18 from the second shell
22. Thus, when the coupling ring 16 is rotated to decouple the shells 18,
22, the first side 36 of each tooth 34 leads the second side 38, and vice
versa. In accordance with this invention, the first side 36 of each tooth
has a steeper angle than the second side 38. This angular difference
results in a greater resistance to decoupling rotation of the coupling
ring 16 than it does to coupling rotation of the coupling ring 16, as will
be described hereinafter.
The first shell 18 and the coupling ring 16 are so configured that when the
coupling ring 16 is installed on the first shell 18, an annular channel is
formed. Thus, as shown in FIG. 1, the coupling ring 16 is formed with an
inwardly extending wall 40 which is immediately axially forward of the
annular region 30 containing the teeth 34. The first shell 18 is formed
with an outwardly extending wall 42 rearwardly spaced from the inwardly
extending wall 40 so as to form the annular channel 44 therebetween. The
outer surface of the channel 44 is thus occupied by the teeth 34.
Disposed within the channel 44 is a pair of leaf spring members 46. The
leaf spring members 46 are identical to each other and are situated in
diametric opposition. The leaf spring members 46 shown in FIGS. 2-4 are
each molded as a unitary piece from plastic, illustratively TORLON
polyamide-imide resin, sold by AMOCO Performance Products, Inc. of
Atlanta, Ga. Each leaf spring member 46 has a central portion 48 fitted
into a cavity 50 formed in the outer periphery of the shell 18 within the
annular channel 44. The leaf spring member 46 further includes a pair of
wings 52, 54 extending within the channel 44 in opposite directions from
the central portion 48, each wing extending to a respective distal end 56,
58 which is disposed against the exterior of the shell 18. Each of the
wings 52, 54 has a generally arcuate first portion 60 of substantially the
same radius as the exterior of the shell 18 within the channel 44 so that
it lies on the exterior of the shell 18 within the channel 44. Between the
arcuate portion 60 and the distal end 56, 58, each of the wings 52, 54 has
a second portion 62 which is raised away from the exterior of the shell 18
so as to form a fixed beam. On each of the raised portions 62, there is a
projection 64 for engaging the teeth 34. Like the teeth 34, each
projection 64 has a generally straight first side 66 and a generally
straight second side 68, with the first side 66 having a steeper angle
than the second side 68. The first side 66 of the projection 64 is adapted
to engage the first side 36 of the teeth 34 and the second side 68 of the
projection 64 is adapted to engage the second side 38 of the teeth 34.
Accordingly, the angles of the sides 66, 68 substantially match the angles
of the sides 36, 38.
Under each of the raised portions 62 of the leaf spring members 46, the
exterior of the shell 18 within the channel 44 is flatted, as shown at 70.
Thus, when the coupling ring 16 is rotated and the raised fixed beam
portion 62 of the leaf spring members 46 is forced inwardly, the flats 70
provide clearance for such movement.
FIGS. 5 and 6 disclose a leaf spring member 72 in accordance with a second
embodiment of this invention. The leaf spring member 72 is stamped and
formed from metal, illustratively stainless steel, as a unitary piece. The
stamped blank is shown in FIG. 5 with oppositely extending and centrally
located tabs 74. During the forming process, the tabs 74 are bent to form
the central portion of the leaf spring member 72 which is mounted in the
cavity 50. Extending outwardly in opposite directions from the tabs 74 are
a pair of wings 76 having distal ends 78. Each of the wings 76 has a
generally arcuate portion 80 and a raised portion 82. Formed as part of
the raised portion 82 is a projection 84 for engaging the teeth 34.
As is clear from FIG. 1, the coupling ring 16 may be assembled to, and
disassembled from, the forward mating end of the plug shell 18.
Accordingly, the coupling ring 16 does not have to pass over the entire
length of cable connected to the plug subassembly 12. When the coupling
ring 16 is assembled to the plug shell 18, the inwardly extending wall 40
cannot pass the abutment 90. The coupling ring 16 is kept in place by a
spiral ring retainer 86, which fits into an internal groove 88 in the
coupling ring 16 immediately rearward of the outwardly extending wall 42
of the shell 18, to thereby prevent subsequent forward axial movement of
the coupling ring 16 with respect to the shell 18.
Since the first side 36 of each tooth 34 and the first side 66 of the
projection 64 is steeper than the second side 38 of each tooth 34 and the
second side 68 of the projection 64, more torque is required to rotate the
coupling ring 16 in the counterclockwise direction, as viewed in FIG. 2,
which corresponds to decoupling the shells 18, 20, than is required to
rotate the coupling ring 16 in the clockwise direction. Therefore, once
the shells 18, 22 have been coupled, expected vibrational forces are
insufficient to decouple the shells.
A particular application of the disclosed connector assembly 10 must meet
strict military specifications. The following Table I is illustrative of
such a specification.
TABLE I
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Coupling/Decoupling Torque
Maximum Engagement
Minimum
and Disengagement
Disengagement
Shell Size Newton Meters Newton Meters
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8 0.9 0.2
9 0.9 0.2
10 1.4 0.2
11 1.4 0.2
12 1.8 0.2
13 1.8 0.2
14 2.3 0.4
15 2.3 0.3
16 2.7 0.4
17 2.7 0.3
18 3.2 0.6
19 3.2 0.3
20 3.6 0.7
21 3.6 0.6
22 4.1 0.8
23 4.1 0.6
24 4.1 0.8
25 4.6 0.6
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A feature of the aforedescribed design not known to be present in previous
designs is that the width of the channel 44 is only slightly greater than
the width of the leaf spring member 46 or 72. This provides clearance for
the leaf spring member 46, 72 to be fitted within the channel 44 while at
the same time preventing the leaf spring member 46, 72 from skewing. If
the leaf spring member 46, 72 were to skew, its interaction with the teeth
34 would be affected, thereby impacting the effectiveness of the
retardation mechanism.
An additional feature of the disclosed design is that the leaf spring
member 46, 72 has a fixed beam at both its ends. Thus, both ends of the
raised portion 62, 82 ride on the exterior of the shell 18 within the
channel 44. This results in more control of the loading forces than in the
situation where the leaf spring member is a simple beam fixed only at one
end.
Accordingly, there has been disclosed an improved decoupling retardation
mechanism for an electrical connector assembly. While illustrative
embodiments of the present invention have been disclosed herein, it is
understood that various modifications and adaptations to the disclosed
embodiments will be apparent to those of ordinary skill in the art and it
is intended that this invention be limited only by the scope of the
appended claims.
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