Sealed Coaxial Cable Connector

Abstract

An improved coaxial cable connector having a pin and socket connection for the inner conductor and a bayonet connection between tubular shells for the shielding conductor in which insulating sleeves are disposed between the inner and shielding conducting elements with air spaces therebetween as well. Sealing means of high dielectric, resilient, insulating material and provided to hermetically seal the air spaces against entrance of outside air and also to interpose the insulating material in the air path between the interior and shielding conducting elements.

Description

BACKGROUND OF THE INVENTION

This invention is in the field of connectors for coaxial electrical cables.

In many electrical installations, connections between various pieces of equipment are made through coaxial cables to prevent spurious electrical signals being picked up or radiated by the interconnecting lines. The connection between the cable and the piece of equipment is usually made with a coaxial cable connector so that the cable may be selectively coupled and uncoupled from the piece of equipment.

The principal requirement of such a coaxial cable connector is a good electrical connection through the connector for both the inner and outer shielding conductors of the cable. Customarily, the inner conductor of the coaxial cable is coupled through the connector by a pin and socket contact assembly surrounded by overlapping coaxial insulating sleeves. The outer shielding conductor of the cable is coupled through the connector by tubular conducting shells concentrically surrounding the insulating sleeves. While the insulating sleeves within the connector can be constructed to fit fairly closely, for practical manufacturing tolerances air spaces are normally left between the metallic elements of the inner contact assembly and the outer tubular shells of the connector.

At low voltages, the air spaces between the inner contact assembly and the outer shells of the connector have little effect on the proper functioning of the connector. However, at relatively higher voltages, the dielectric qualities of the air spaces become increasingly important to the proper insulation of the connector. The dielectric qualities of the air spaces are affected by changes in the environment in which the connector is used. Thus, depending on atmospheric conditions, such as humidity and air pressure, the breakdown potential of the air in the air spaces may be lower than the potential between the inner and outer conductors of the connector, resulting in arcing. This problem is particularly troublesome in aircraft in that altitude changes greatly vary the air pressure and humidity of the ambient air surrounding the connector. The connector of this invention excludes the ambient air to maintain the dielectric properties of the connector air spaces and further interposes insulating seals in the breakdown paths through the air spaces.

SUMMARY OF THE INVENTION

The coaxial cable connector according to the present invention includes sealing members positioned within the connector so as to not only hermetically seal the air spaces within connectors, but also interpose electrical insulation in the air paths between the inner and outer conductors to prevent voltage breakdown therethrough. The voltage breakdown point of the coaxial connector is thereby substantially increased both by maintaining constant dielectric properties and increasing the resistance of the paths through the connector air spaces.

In one presently preferred embodiment of the invention, the connector is made of mating sections, both of which have outer conducting tubular shells with insulating sleeves therein which overlap about the pin and socket contact of the inner conductor. A bore through an insulating sleeve which is to receive the insulated inner conductor of the cable communicates with a recess in which a pair of O-rings are mounted. In the absence of the inner conductor, the O-rings are dimensioned to extend radially into the bore. A seal is formed thereat when the insulated inner conductor of the coaxial cable is inserted into the bore and the insulation around the conductor resiliently deforms the O-rings outwardly into the recess. Thus, a seal is relatively permanently and simply formed between the outer surface of the conductor insulation and the surrounding insulating sleeve during the attachment of the coaxial cable to this connector section.

A second and spring loaded sealing member is positioned between axially facing shoulders on the insulating sleeves within the outer tubular shells of the connector sections.

A bore through the insulating sleeve of the other connector sections has a conductor therein leading to the pin and socket contact and a third O-ring seal is provided between this conductor and the bore surface.

The air spaces within the connector between the conducting elements of the inner conductor and outer shield are thereby hermetically sealed against entrance of outside ambient air to maintain the dielectric properties and also the insulating O-ring members are interposed in the air paths between the elements to increase the resistance to breakdown therethrough.

Other objects and features of the invention will be apparent from the detailed description and the appended drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a longitudinal sectional view through a coaxial cable connector embodying the present invention, a receptacle section being connected to a coaxial cable and a plug section being mounted on a panel or the like;

FIG. 2 is a longitudinal sectional view through the receptacle section of the cable connector shown in FIG. 1 with the coaxial cable removed; and

FIG. 3 is an end elevational view of the receptacle section, shown on a reduced scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the illustrated embodiment, a coaxial cable 22 is shown connected to a female receptacle section 14 of a connector 10 according to the present invention, which is, in turn, coupled to a male plug section 16 mounted on a panel plate 18.

It should be noted that such a coaxial connector 10 may be adapted for use in many varied applications so that the roles of the plug section 16 and receptacle section 14 may be reversed so that the plug is connected to the cable 12 and the receptacle 14 to the panel 18. Additionally, both the plug and receptacle sections may be adapted for connection to the ends of coaxial cables. In the particular illustrated embodiment, the plug section 16 includes a radially extending flange 20 which overlaps a hole 22 in the panel 18 which may be the wall of an electrical chassis. A portion of the plug section is threaded at 24 and the plug section is held in place on the panel 18 by means of a nut 26 and lockwasher 28 to insure a good electrical connection between the flange 20 and the panel 18.

While the plug section 16 and receptacle section 14 can be coupled together by any of a number of conventional methods, the coupling arrangement for the illustrated cable connector 10 is of the bayonet type in which a bayonet sleeve 30 is axially slidable against spring bias, over an outer conducting shell 34 of the receptacle section 14 toward the plug section 16 of the connector. The spring bias is provided by a compression spring 36 concentrically mounted around the receptacle shell 34 between the shell and bayonet sleeve 30. The spring 36 is compressed between a shoulder 38 extending radially outwardly of the shell 34 and a retaining ring 40 rigidly mounted on the bayonet sleeve 30.

The bayonet sleeve 30 has a pair of substantially L-shaped slots in its inner end, with an axial slot 42 leading first from the inner edge of the sleeve and then a circumferential slot 44 leading a short distance around the sleeve. To couple the plug section 16 and the receptacle section 14, the axial slots 42 are first slid axially past a pair of pins 46 extending radially outwardly of the outer shell 32. The bayonet sleeve 30 is then rotated so that the pins travel into the circumferential slots 44. The pins 46 are then engaged, under spring bias, by slight detents 48 in the forward edges of the circumferential slots 44 to maintain the plug section 16 in physical and electrical contact with the receptacle section 14.

In the coupled position, the tubular shell 34 of the receptacle section 14 contacts the tubular shell 32 of the plug section 16 at an interface region 50 which affords good electrical contact. The coupled tubular shells 32, 34 electrically connect a braid or outer conductor 52 of the coaxial cable 12 through the connector 10 to the panel 18. As noted above, for other applications the outer shell 32 of the plug section 16 could be connected to the braid of another coaxial cable.

The diameter of the tubular shell 34 is reduced at its rearward end to form a sleeve 52 and the braid, or outer conductor 54, of the coaxial cable 12 is slid over this sleeve and securely fastened by crimping or soldering, as shown in FIG. 1. An inner conductor 56 and surrounding insulation 57 of the coaxial cable 12 is led through the sleeve 52 into a central bore 58 in a coaxial insulating sleeve 60 within the tubular shell 34. The insulation 57 is removed from the forward end of the conductor 56 and the conductor is electrically connected, as by soldering, to a slotted-sleeve, socket contact 64. The contact 64 is housed in a bore 66 in a reduced diameter, forward portion 68 of the insulating sleeve 60 which extends beyond the end of the contact 64. The forward portion 68 serves not only to support the contact 64 but prevents accidental touching of the contact when the receptacle section 14 and plug section 16 are uncoupled.

The plug section 16 of the cable connector 10 has an inner conductor in the form of a solid rod 69 extending through a central bore bore 71 in an insulating sleeve 72 retained at the back of the shell 32, as by a spun-over edge thereof. In the illustrated embodiment, the inner conductor or rod 69 of the plug section 16 terminates in a contact pin 76 within an enlarged bore 70 in the insulating sleeve 72. The bore 70 is slightly larger in diameter than the forward portion 68 of the insulating sleeve 60 to receive it in telescoping, overlapping relation, and the respective lengths of the bore and forward portion are such that the contact pin 76 will be inserted into and be engaged by the slotted-sleeve contact socket 64 when the plug section 16 and receptacle section 14 are coupled.

Between the bores 70 and 71 is a coaxial sealing bore 78 into which an O-ring 80 of resilient insulating material, such as silicone rubber, is inserted around the conducting rod 69 to effect a seal thereat. The O-ring 80 is held in place, and support is provided for the contact pin 76, by a cap 81 which fits into the sealing bore 78 with a flange 82 on the cap abutting a shoulder 84 at the end of the bore 70. The O-ring 80 both seals against outside atmosphere and provides a high dielectric interruption to the path between inner and outer conductors.

In a presently preferred embodiment of the present invention the insulating sleeves 60, 72 are constructed so that a space is left between their facing outside edges 87, 88, respectively, when the plug section 16 and receptacle section 14 are coupled. An interface sealing member 89, made of electrically insulating material is placed between the facing edges 87, 88 and not only seals against entrance thereat of the outside atmosphere, but also provides interruption of the air space between the inner contacts 64, 76 and the outer tubular shells 32, 34.

The electrical insulating qualities of the sealing member 89 are considerably better than those of air and may be comparable to the dielectric qualities of the material used for the insulators 60, 72. Thus, the breakdown voltage between the contacts 64, 76 and the tubular shells 32, 34 is not limited by the breakdown voltage of the air in the remaining air space. It has been found that a sealing member 89 of silicone rubber affords both good sealing qualities and good electrical insulating qualities, but it will be appreciated that many other materials may be employed, depending on particular applications.

The interface sealing member 89 may take many configurations well known in the sealing art and may be attached either to the plug section 16 or the receptacle section 14. In the illustrated embodiment, the sealing member 89 is made with a flat surface attached to the edge 87 of the insulating sleeve 60 and a small shoulder 90 on the forward end of the tubular shell 34. The forward surface of the sealing member 89 is rounded and its sealing action is much like that of an O-ring, being resiliently deformed into sealing engagement with the facing outer edge 88 of the insulating sleeve 72.

A further seal is formed in a bore 92 in the end of the insulating sleeve 60 which normally abuts a substantially radially extending transition shoulder 94 connecting the tubular shell 34 and the sleeve 52. A shoulder 96 of the bore 92 and the transition shoulder 94 define an annular recess 97 into which a pair of oversized O-rings 98, also made of silicone rubber, are inserted so that the inside diameters of the O-rings naturally extend into the main bore 58 of the insulating sleeve 60 when the insulated conductor 46 of the cable 12 is removed, as shown in FIG. 2.

The seal at the O-rings 98 is formed by inserting the insulated inner conductor 46 of the coaxial cable 12 through the sleeve 52 and into the main bore 58 of the insulating sleeve 60 so that the insulation 57 of the conductor resiliently deforms the O-rings 98 outwardly into the recess 97 to establish a seal thereat. As shown in FIG. 1, the seal thus established completes the hermetical sealing of the interior of the connection and interposes good dielectric insulation in the air path thereat.

The cable connector 10 of the present invention is substantially unaffected by changes in atmospheric conditions because it is hermetically sealed and the breakdown voltage of the connector is increased by the introduction of the high dielectric seals in the air paths between the inner and outer conducting elements.

It should be understood that many variations are possible in the present invention and that the illustrated connector is only a preferred embodiment for a particular type of cable connector. Thus the invention is not intended to be limited except by the following claims.

Claims

1. In a cable connector having plug and receptacle sections, each including an outer shell and a contained insulating sleeve, said sections being adapted to be coupled together to thereby electrically interconnect, by means of engaging contact elements attached to at least one pair of conductors disposed through said insulating sleeves with at least one of said pair of conductors being an insulated conductor having independent surrounding insulation, said insulated conductor being receivable within a bore through its respective insulating sleeve, said bore having a first portion receiving said contact element, and a second portion of increased diameter receiving said surrounding insulation of said insulated conductor, said insulating sleeves having coupling sealing means between opposing faces thereof for sealing said insulating sleeves when said sections are coupled, a seal construction for said insulated conductor comprising:

an annular recess around said second portion having a diameter greater than that of said second portion; and

at least one insulating O-ring mounted in said recess, said O-ring having an inside diameter less than that of said second portion of said bore whereby said O-ring naturally tends to extend into said bore, prior to insertion of said insulated conductor into said bore, said O-ring being resiliently deformed into sealing engagement with said surrounding insulation of said insulated conductor and said annular recess as said

2. A cable connector as defined in claim 1, wherein:

3. A coaxial cable connector comprising:

plug and receptacle sections each having an outer conducting shell and an insulating sleeve therein;

an inner conductor terminating in an attached contact element disposed through each of said insulating sleeves, at least one of said inner conductors being an insulated conductor having independent surrounding insulation;

a seal between each of said inner conductors and its respective insulating sleeve with the seal between said insulated conductor and its respective insulating sleeve including a bore through said insulating sleeve having

a first portion receiving said contact element,

a second portion of increased diameter receiving said insulated conductor,

an annular recess around said second portion having a diameter greater than that of said second portion,

and said seal further including at least one O-ring in said recess having an inside diameter less than that of said second portion of said bore whereby said O-ring naturally tends to extend into said second portion of said bore prior to insertion of said insulated conductor into said bore, said seal being formed as said insulated conductor and attached contact element are inserted into said bore, said O-ring being resiliently deformed into sealing engagement with said surrounding insulation of said insulated conductor and said recess;

means for coupling said plug and receptacle sections together so that said insulating sleeves present coaxially opposed faces and said contact elements are engaged; and

coupling sealing means between said opposed faces on said insulating sleeves for substantially hermetically sealing air spaces within said connector between said inner conductors and said outer shells against the

4. A coaxial cable connector as defined in claim 3 wherein:

said annular recess is formed between an enlargement of said bore at an end of said insulating sleeve, said enlargement having a diameter greater than that of said second portion, and a transition shoulder of said outer shell

5. A coaxial cable connector as defined in claim 3 wherein said seal is made of silicone rubber.