Round plug socket provided with an over-spring

A round plug socket including a conductor securing portion and a cylindrical spring arm base portion provided with spring arms connected to the front edge of the spring arm base portion, the spring arms being spaced from one another and being bent inward. A plug ring is provided on the front side of the spring arms. The plug ring is embraced by a ring portion of an over-spring which is slit in a longitudinal direction of the round plug socket. Securing members for unreleasably seating the over-spring ring portion on the round plug socket are provided, which preferably also limit the opening of the over-spring to protect against any over-bending of the spring arms during contact thereof with a male plug inserted into the round plug socket.

This invention relates to a round plug socket formed from a sheet-metal 
stamped part, which is provided with an over-spring likewise being formed 
from a sheet-metal stamped part. 
From German utility model No. 71 33 507, there is known a round plug socket 
which includes a conductor securing portion and a plug portion. The plug 
portion is connected to the conductor securing portion with a 
cylindrically rolled spring arm base which presents abutment edges 
extending in a longitudinal direction, and to which there are connected 
three spring arm contacts extending forward in extension of the cylinder 
wall. The spring arm contacts are arranged "on gap", i.e with a lateral 
spacing from one another. With their front end, the spring arm contacts 
are attached to a cylindrical plug ring likewise presenting abutment edges 
extending in a longitudinal direction. For the formation of the contact 
areas for contacting a fitting round plug, the spring arm contacts are 
bent arcuately toward the interior of the round plug socket. On the plug 
ring, there are connected, moreover, spring arm stops, and namely, being 
in the gaps between the spring arm contacts. The spring arm stops extend 
rearward, being of equal length or shorter than the spring arm contacts, 
and being bent outward. 
This known round plug socket has proved itself very well. Accordingly, an 
object of the present invention is to increase the spring forces of the 
round plug socket when the spring arm contacts are arranged in a lateral 
spacing from one another and, in so doing, also to provide a protection 
against any bending open of the plug ring, especially, however, also a 
protection against any bending open of the spring arm base. 
This object is obtained according to the present invention by an 
over-spring turned inside-out over the round plug socket in the plug 
portion. 
It is a known practice in the prior art to provide an over-spring for a 
round plug socket. The known over-spring includes a cylindrical portion 
which embraces a cylindrical base portion of the round plug socket, in 
which arrangement the abutment edges of the over-spring overlap. On the 
rearward edge of the over-spring, in lateral spacing from one another, 
there are attached arm stops which are bent outward and extend rearwardly. 
On the front edge of the cylindrical portion of the over-spring, there is 
connected a forward-directed arm, which forms a type of spring arm, which 
is connected to a closed ring. The abutment edges of the ring are solidly 
joined with one another. The ring surrounds an annular plug portion of the 
round plug socket, which presents oppositely lying abutment edges, the 
ring being joined by a semi-hollow cylindrical connecting strap to the 
base portion. The spring arm of the over-spring covers the longitudinal 
opening of the connecting strap, in which arrangement an inward-bent 
portion of the spring arm serves as the spring contact-pressure element 
for the contact pin, whereby the contact pin is pressed against the bottom 
of the plug ring and/or of the connecting strap, so that the desired 
contact can be assured. However, this prior art spatial form is not usable 
for a round plug socket provided with spring arms arranged with a lateral 
spacing therebetween. Neither can this prior art form give a hint for the 
arrangement of an over-spring on a round plug socket of the type described 
above as an improvement with respect to the German prior art reference.

Referring now to FIGS. 1-3 of the drawings, the round plug socket 1, being 
a sheet-metal stamped part as shown in FIG. 2, is fitted with an 
over-spring 2, being a steel plate part as shown in FIG. 3. The round plug 
socket 1 includes a conductor securing portion 3, which can correspond to 
any of the usual spatial forms. Instead of the conductor securing portion 
3, there can also be provided a soldering connection part. The conductor 
securing portion 3 extends into a cylindrically rolled spring arm base 
part 4. The longitudinal edges 5 of the base part 4 are arranged opposite 
one another in the blank form shown in FIG. 2, and abut one another when 
formed into the plug socket 1 as shown in FIG. 1. In this arrangement, in 
the transition part of the conductor securing portion 3 to the base part 
4, there can be provided a bulge 13 to limit the amount of insertion of 
the plug socket 1 when being inserted into a conventional housing or 
casing made of insulation material (not shown), such housings and casings 
being well known in the art. 
To the annular edge 6 of the base part 4, there are attached three spring 
arm contacts 7 arranged in a lateral spacing from one another, so that 
gaps or spaces 8 are formed. At the free ends of the spring arm contacts 
7, there are provided cross straps 9 which extend at right angles to the 
longitudinal extent of the spring arm contacts 7. The straps 9 overhang 
the spring arm contacts 7 laterally to form a plug ring 10, the edges 11 
and 12 of the transverse straps 9 being arranged opposite each other for 
abutting on one another as shown in FIG. 1. The spring arm contacts 7 are 
bent inward, as known per se, to form contact portions, so that in the 
interior of the socket 1 there is yielded a constriction of the cross 
section thereof as indicated in FIG. 1. 
The plug ring 10 is embraced by a cylindrical spring ring portion 14 of the 
over-spring 2. The longitudinal edges 15 of the blank shown in FIG. 3 are 
arranged opposite one another for abutting one another when the 
over-spring 2 is formed as shown in FIG. 1. This over-spring ring portion 
14 is provided so that the spring arm contacts 7 cannot bend too far 
radially outward. 
The unreleasable seating of the over-spring ring portion 14, and therefore 
of the over-spring 2, is expediently ensured by cut-out tabs 16 and 
incisions 17 provided in the ring portion 14. The tabs 16 are bent inward 
with the free rest edge 18 of each tab 16 engaging behind a rear edge 19 
of a respective cross strap 9, as shown in FIG. 1. The zone 20, which is 
present on the front edge side of each incision 17, is pressed in as a 
corrugation to form an impact edge 21 which abuts against the front edge 
22 of a respective cross strap 9, as shown in FIG. 1. The vertical spacing 
of the edge 18 to the incision 17 corresponds to the width of the plug 
ring 10, the incision 17 being arranged, as depicted in FIG. 3, in each 
case between two tabs 16. 
The tabs 16 fulfill a further essential function. The side edges 23 or 24 
of the tabs 16, on widening or opening of the plug ring 10, for example in 
the inserting of a plug (not represented) or tilting of a plug, strike 
against a side edge 25 or 26 of the spring arm contacts 7, so that a 
further opening of the over-spring ring portion 14 is no longer possible. 
This limitation presents a very effective protection against any 
over-bending of the spring arm contacts. 
According to the present invention, on the rear edge 27 of the over-spring 
ring portion 14, there are connected two spring arm stops 28 having a 
lateral spacing from one another, the spring arm stops extending rearward 
and being bent outward. It is advantageous, as depicted in FIG. 3, to 
provide three spring arm stops 28, in which arrangement one of the spring 
arm stops can be composed of two parts 28a, and in each case, the edge 15 
is extended in the longitudinal middle between the parts 28a. 
The over-spring 2 is seated on the round plug socket 1 expediently in such 
a way that the spring arm stops 28 are disposed over the gaps 8, so that 
the spring arm contacts 7 extend below the gaps 29 provided between the 
spring arm stops 28. Through this arrangement, it is achieved that the 
spring arm stops 28 can be yielded inwardly freely upon insertion thereof 
into a casing (not represented) intended therefor. The front edge 30 of 
the over-spring 2 overhangs expediently the front edge 22 of the round 
plug socket 1, so that the plug ring 10 is also thus protected by the 
over-spring 2. 
In the modified embodiment according to FIG. 4, the over-spring 2 includes 
other features in comparison to the round plug socket 1 according to FIGS. 
1 to 3. The elements ensuring the unreleasable seating and the 
over-bending protection in this modified form according to FIG. 4 includes 
connecting straps 31, which are attached in the gaps 29 to the rear edge 
27. The straps 31 extend rearward between two spring arm stops 28 and are 
seated in one piece on a cylindrical clamping ring 32. The longitudinal 
edges 33 of the clamping ring 32 are arranged opposite one another for 
abutting on one another as shown in FIG. 4. The unreleasable seating of 
this over-spring and the over-bending protection provided thereby, are 
ensured by having at least one tab 34 cut out from the cylinder wall of 
the clamping ring 32 in a transverse or circumferential direction. The tab 
34 is flanged inward so that in the process thereof, it grips about a 
longitudinal edge 35 of a hole 36 formed in spring arm base part 4, the 
hole 36 corresponding to the form of the tab 34. Preferably, there are 
provided two holes 36 and two associated tabs 34, the tabs 34 being 
flanged in opposite directions. 
Expediently, the tabs 34, as depicted in FIG. 4, are cut out on the rear 
edge 37 of the clamping ring 32, which facilitates the assembling thereof. 
By the flanging of the tabs 34, the radial expansion of the over-spring is 
rendered difficult. In this construction, expediently, the longitudinal 
impact edges of the over-spring 2 should not lie in the zone of the 
longitudinal impact edges of the round plug socket 1, but should lie 
off-set from one another on the circumference, as shown in FIG. 4. 
The further modified embodiment, according to FIG. 5, resembles the 
modified form according to FIG. 4, except for the elimination of the bulge 
13 on the round plug socket 1. Instead of the bulge 13, there is provided 
a bulge 38, preferably, on a portion of the rear edge 37 of the clamping 
ring 32 of the over-spring 2. The bulge 38 also limits the amount of 
insertion of the plug socket 1 into a conventional housing or casing, 
however this latter formation simplifies the shaping of the round plug 
socket 1 and does not complicate the shaping of the over-spring 2. In 
connection with the bulge 38, it is expediently provided that the tabs 34 
in the shell surface are arranged, as depicted in FIG. 5, in front of the 
bulge 38 in the clamping ring 32. 
With the present invention, it is possible to simplify the form of the plug 
ring 10 of the spring arm contacts 7, and through the connection of the 
spring arm stops 28 to the over-spring ring portion 14, it is possible to 
shorten the structural length of the round plug socket 1 quite 
considerably when provided with the over-spring 2. Moreover, the 
assembling of the over-spring 2 of the present invention is substantially 
simpler than the prior art over-springs. Furthermore, there is achieved an 
over-bending protection with the present invention without it being 
necessary to provide a closed ring for this purpose as required in the 
prior art. 
Another special modified form of the present invention is depicted in FIGS. 
6 and 7, it being a variant of the form represented in FIG. 5. 
Correspondingly, the round plug socket 1 is constructed cylindrically in 
the zone of the spring arm base part 4, and provides at least one hole 36 
in the cylindrical shell thereof. From the spring arm base part 4, 
however, only two adjacent spring arm contacts 7 extend foward arranged in 
a lateral spacing from one another, so that there is formed a gap or 
spacing 8 between the spring arm contacts 7. At the front end, the spring 
arm contacts 7 are connected to a plug ring 10, which preferably forms a 
closed ring. The plug ring 10 includes only two impact edges seated one on 
another, which extend in the longitudinal direction of the socket. With 
respect to the third spring arm contact, the middle portion thereof is cut 
out, so that there still remain only a tab 39 joined to the spring arm 
base part 4, and a tab 40 connected to the plug ring 10. The tabs 39 and 
40 are, as depicted in FIG. 6, bent inward, i.e., toward the interior of 
the socket. The function of the inward-bent tabs 39 and 40 is explained 
further below. 
On the socket 1, there is seated an over-spring 2 with at least one 
connecting strap 31. Preferably, however, two connecting straps 31 are 
arranged adjacent each other with a gap 29 therebetween. The straps 31 are 
joined to the rear edge 27 of the over-spring ring portion 14, and then 
extend rearward to be seated on the clamping ring 32. The unreleasable 
seating of the over-spring of this embodiment resembles the form of 
unreleasable seating according to FIG. 5, being ensured by at least one 
tab 34 cut out of the cylinder wall of the clamping ring 32, which tab 34 
is flanged inward. In the process thereof, the tab 34 extends through the 
hole 36 and grips around one edge of the hole 36. Preferably, also in this 
case, two holes 36 and two associated tabs 34 are provided, the tabs 34 
being oppositely flanged. Provided with the bulge 38, the over-spring 2 
ends at the rearward edge thereof. 
Between the connecting straps 31, as in the other forms of the present 
invention, there are arranged spring arm stops 28 on the over-spring 2. 
According to the present invention, a third connecting strap is provided, 
extending from the clamping ring 33 but separated from the over-spring 
ring portion 14, being bent inward to provide a contact spring tongue 41. 
The tongue 41 grips into the longitudinal space between the two socket 
tabs 39 and 40. In the front end portion, the tongue is provided with a 
bow 42 which is bent outward, so that there is provided a convexly formed 
contact area 43. 
The plugged contact pin (not represented), in the modified form according 
to FIGS. 6 and 7, is pressed by the spring force of the contact spring 
tongue 41 against the preferably inward-bent spring arm contacts 7, 
whereby there is ensured a very good contact therebetween. The tabs 39 and 
40, likewise bent inward, prevent an over-bending of the contact spring 
tongue 41, because they support the inserted contact pin in a radial 
direction, so that the pin can press back the tongue 41 only as far as an 
intended connecting line drawn between the ends of the tabs 39 and 40. 
Numerous alterations of the structure herein disclosed will suggest 
themselves to those skilled in the art. However, it is to be understood 
that the present disclosure relates to preferred embodiments of the 
invention which are for purposes of illustration only and are not to be 
construed as a limitation of the invention.