GB2029129A - High-voltage electrical connector - Google Patents

Abstract

In a two part high-voltage electrical connector, a first contract pin 30, in the plug assembly 12, is encased by a first dielectric sleeve 32 of relatively non-resilient material, and a second dielectric sleeve 34 of resilient material, is installed in the receptacle assembly 10 and is dimensioned to provide a continuous dielectric seal between the first dielectric sleeve 32 and the body 14 of the receptacle assembly 10, which is also of a dielectric material. The connector is coupled by inserting the first dielectric sleeve 32 of the plug assembly 12 into the second dielectric sleeve 34 of the receptacle assembly 10, thereby completing the continuous dielectric seal, but avoiding abrasive contact with the receptacle body 14 and minimizing the axial force needed to effect coupling and uncoupling. <IMAGE>

Description

SPECIFICATION High-voltage electrical connector BACKGROUND OF THE INVENTION This invention relates generally to high-voltage electrical connectors, and, more particularly, to high-voltage connectors having dielectric seals around their electrically connectable contact pins. High-voltage connectors are used in a variety of devices. For example, in coupling a high-voltage power supply to a travellingwave tube, a connector rated as high as 20kv may be required. Such a connector may, for example, effect connection of a single highvoltage conductor and a surrounding ground conductor, but in other types of connectors, multiple pins may be involved.

In the design of high-voltage connectors of this general type, electrical arcing and corona discharge must be eliminated, or at least minimized. One technique for achieving this goal is to surround the connector contact pins with a dielectric material, thereby isolating the connector from the surrounding atmosphere.

Unfortunately, however, the use of dielectric materials, such as natural or synthetic rubber, usually results in significant difficulty in coupling and uncoupling the constituent parts of the connector.

Typically, a high-voltage connector comprises a receptacle assembly and a plug assembly. The recptacle assembly has an insulated body, usually of a ceramic material, and includes a male contact pin recessed relatively deeply inside a cylindrical bore within the insulated body. The plug assembly includes a female contact pin with a bore in its end sized to receive and retain the male contact pin of the receptacle assembly.

In a typical connector of the prior art, a dielectric seal, of rubber or similar material, encases the contact pin on the plug assembly, except for an end hole in which the male pin of the receptacle assembly is inserted. When the connector is assembled, the contact pin in the plug assembly, including the surrounding rubber dielectric seal, is crammed inside the ceramic insulated body of the receptacle assembly, and a lock nut is engaged to retain the two halves of the connector in an assembled relationship.

Unfortunately, however, this type of connector structure has a number of significant disadvantages. Most importantly, connectors of this type simply do not have good performance characteristics at low temperatures and low pressures, such as might be encountered at high altitude in some applications. It has been theorized that some corona discharge still occurs in air gaps around the contact pins. Another disadvantage is that the ceramic material usually used for the insulated receptacle body is an abrasive material, and this results in significant wear on the rubber dielectric seal. In some instances, as few as ten or twelve matings of the connector can have a significant effect on its performance.

In addition, the inner ceramic surface of the receptacle assembly can become soiled by repeated matings with the rubber dielectric seal, and this may also have a detrimental effect on the operation of the connector. Also significant from a wear standpoint, is the abrasive action of a threaded portion of the ceramic insulated body, as it engages the threads of the lock nut.

Another important consideration is that the coupling action requires a relatively large axial force to be applied between the plug and receptacle assemblies, and damage may result to the connections between the conductors and the contact pins of the connector. Such damage can also result from the uncoupling action.

Many of these disadvantages are aggravated when the connector is subjected to low temperatures, and the rubber dielectric material becomes less resilient, more brittle, and more susceptible to wear. Coupling the plug and receptacle assemblies together at low temperatures is particularly difficult and often results in damage to the dielectric material.

It will be appreciated from the foregoing that there is a significant need for an improved high-voltage electrical connector that avoids the aforementioned disadvantages of the prior art, and that provides a connector operable even at low temperatures and pressures, and capable of being coupled several hundred times without significant wear. The present invention fulfills this need.

SUMMARY OF THE INVENTION The present invention resides in a highvoltage connector in which the contact pins are dielectrically sealed in such a manner as to effectively isolate them from the atmosphere, while at the same time providing for convenient and non-abrasive coupling and uncoupling actions. Basically, and in general terms, the improved connector of the invention includes a first dielectric sleeve of relatively non-resilient material, permanently installed over the plug contact pin, and a second dielectric sleeve of resilient material installed in the insulated body of the receptacle assembly, the two dielectric sleeves being dimensioned such that the resilient dielectric sleeve forms a continuous dielectric seal between the first dielectric sleeve and the insulated body of the receptacle.

The first dielectric sleeve is of a relatively smooth and hard-wearing material, and slides tightly but easily inside the second dielectric sleeve, compressing it against the insulated body of the receptacle. For more perfect sealing, the second dielectric sleeve has one or more integral raised annular portions on its outer surface, its inner surface, or both. The second dielectric sleeve may also have an integral annular flange around its outer surface, to be received in a corresponding annular groove formed inside the insulated body of the receptacle. The flange and groove act to prevent inadvertent removal of the second dielectric sleeve.The first dielectric sleeve has a small central aperture in its end, for receiving the male connector pin installed in the receptacle assembly of the connector, and the second dielectric sleeve has a similar opening in its end wall for the same purpose.

It will be appreciated from the foregoing that the invention allows convenient connection and disconnection of a high-voltage conductor, and that it does so without significant wear to the connector parts, since the sliding contact during connection and disconnection is between the relatively smooth first dielectric sleeve and the inner surface of the second dielectric sleeve. Furthermore, the contact pins of the connector are essentially perfectly sealed by surrounding dielectric elements.

Other aspects and advantages of the invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a longitudinal cross-sectional view of the connector shown in an assembled condition; Figure 2 is a perspective view of the connector of Fig. 1, shown with the plug and receptacle assemblies disconnected, and at a reduced scale compared with that of Fig. 1; and Figure 3 is a perspective view, partly in section, of the resilient dielectric sleeve used in the connector of the invention.

DESCRIPTION OF THE PREFERRED EMBODI MENT As shown in the drawings, the present invention relates to a high-voltage electrical connector. Basically, a connector of the type with which the present invention is concerned comprises a receptacle assembly, generally indicated by reference numeral 10, and a plug assembly 1 2. The receptacle and plug assemblies include equal numbers of electrically conductive contact pins, corresponding ones of which are coupled together when the receptacle and plug assemblies are connected.

In the embodiment illustrated, only a single pair of such contact pins is shown, as will now be described in more detail, but it will be appreciated that the invention is equally applicable to multipin connectors as well.

The receptacle assembly 10 of the connector comprises a generally cylindrical insulated body 14, usually of a ceramic material, the insulated body having a metal insert 1 6 securely installed at one end of the body, and adapted to support a male contact pin 1 8 in such a manner that the pin extends axially toward the other end of the body.An electrical cable 20 has an insulated conductor 22 that iS soldered or otherwise electrically connected to the contact pin 1 8. The plug assembly 1 2 includes an elongated female contact pin 30 taking the form of a sleeve at its end, the sleeve being designed to receive and make electrical contact with the male contact pin 1 8 of the receptacle assembly 1 0. The contact pin 30 is appropriately connected, by soldering or other means to an insulated electrical cable 20', so that when the contact pins 1 8 and 30 are coupled together, electrical connection is established between the cables 20 and 20', through the connector.

For operation of the connector at high voltages, up to approximately 20 kv, it is important not only to establish good electrical connection between the contact pins 1 8 and 30 of the connector, but also to isolate, as far as possible, the connector from exposure to atmospheric air, to eliminate, or at least minimize, sparking and corona discharges from the electrically conductive element. Such isolation is usually effected by surrounding the conductive elements with a dielectric material, and this becomes even more important in conditions of reduced atmospheric pressure and reduced temperature. Previous attempts to address these problems have required that the female contact pin 30 be surrounded with a resilient dielectric material, which is then forced into the interior of the insulated body 14, to minimize air gaps around the pin 30.

In accordance with the present invention, the space between the female contact pin 30 and the insulated body 14 of the receptacle assembly 10 is filled by two closely adjacent dielectric sleeves. A first dielectric sleeve 32 is permanently installed over the female contact pin 30, and is of relatively non-resilient and smooth material. A second dielectric sleeve 34 is installed inside the insulated body 14, and is made of a resilient material, such as a silicone rubber. When the pin 30 and its outer dielectric covering 32 are together inserted in the receptacle assembly 10, the second dielectric sleeve 34 is radially compressed within the insulated body 14, and forms a practically perfect seal between the first dielectric sleeve 32 and the dielectric material of the insulated body 14. As a result, practically all atmospheric air is excluded from contact with the female contact pin 30.

In the connector of the invention, the plug assembly 1 2 can be inserted in the receptacle assembly 10 relatively easily, thus minimizing the problems of abrasion and wear that would otherwise result from contact with the ceramic insulated body 14. The sliding contact between the mating elements, during coupling and uncoupling of the connector, is between the first dielectric sleeve 32 and the second dielectric sleeve 34. The first dielectric sleeve 32 is preferably a hard-wearing plastic material with a relatively low coefficient of friction, such as diallyl phthalate, to minimize wear from the coupling and uncoupling operations.

It will be best appreciated from Fig. 3 that the resilient dielectric sleeve 34 of the preferred embodiment includes an annular flange 40, which is received in a corresponding annular notch 42 in the insulated body 14, to prevent inadvertent removal of the resilient sleeve 34. The resilient sleeve 34 of the preferred embodiment also includes a plurality of raised annular portions 44 spaced along its length, both on the inside and outside surfaces of the sleeve. When the plug assembly 1 2 is inserted in the receptacle assembly 10, these raised annular portions 44 are compressed between the first dielectric sleeve 32 and the inner surface of the insulated body 14, to provide a more perfect seal.

The resilient seeve 34 is, or course, open at one end to receive the female contact pin 30 and the first dielectric sleeve 32 of the plug assembly 12, and has its other end closed by an integral end wall 46, having a central circular opening 48 through which the male contact pin 1 8 is inserted in the coupling action. The male pin 18 also extends through a corresponding opening 50 in the end of the first dielectric sleeve 32.

In the embodiment illustrated, a shielded grounding path is also provided in the connector. The insulated body 14 of the receptacle assembly 10 has affixed to it an externally threaded metallic bushing 60. The bushing 60 forms the exterior of the leading portion of the receptacle assembly 10, and has an integral flange 62 to which a shielded ground conductor (not shown) is electrically connected.

The plug assembly 1 2 also includes, in addition to the female contact pin 30 and the first dielectric sleeve 32, other elements for housing these elements and for retaining the plug and receptacle assemblies 10 and 12 in connection. The female contact pin 30 terminates at its root end in an enlarged-diameter portion 70, at which electrical connection is made with the cable 20'. The non-resilient dielectric sleeve 32 is dimensioned to surround the pin 30 closely, including the enlarged-diameter portion 70. The non-resilient dielectric sleeve 32 has its internal diameter further enlarged, as shown at 74, to surround an end portion of the cable 20', but leaving an annular gap between itself and the cable.

This gap is filled by a resilient seal 76, preferably of a silicone rubber material, and having raised annular portions 78 on its exterior surface. The seal 76 has an integral, outwardly extending end flange 80, which overlaps the end of the first dielectric sleeve 32, at its enlarged-diameter portion 74. The dielectric sleeve 32 also has two external diameter changes, a first enlargement in diameter forming an external shoulder 82 near the root of the female contact pin 30, and a second diameter enlargement forming another external shoulder 84 to the rear of the first external shoulder 82.

The first dielectric sleeve 32 is installed in a metallic cylindrical housing 86, having essentially the same diameter internally as the external diameter of the enlarged portion 74 of the first dielectric sleeve 32. The metallic housing 86 has an integral end flange 88 at its forward or leading end, extending inwardly over the external shoulder 84 of the dielectric sleeve 32, and also extending outwardly for a short distance. The housing 86 is internally threaded at its rearward end to receive a correspondingly threaded plug 90, which functions to retain the non-resilient dielectrical sleeve 32 in position by urging it against the inwardly projecting portion of the housing flange 88. The seal 76 is also held in position by the plug 90 as it bears down on the flange 80 of the seal. An annular spacer 92 may be included between the plug 90 and the flange 80 of the seal 76.

Finally, the connector includes a lock nut 96 having an internally threaded forward end 98, and an internally flanged rear end portion 100, which is reatined between the housing flange 88 and a snap ring 102 installed around the housing 86. The lock nut 96 engages the threaded portion of the bushing 60 on the receptacle assembly 10, and retains the plug assembly 1 2 in connection with the receptacle assembly. A resilient annular seal 104 is installed between the leading edge of the insulated body 14 and the external shoulder 82 of the first dielectric sleeve 32, to complete sealing of the connector.

It will be appreciated from the foregoing that the present invention represents a significant improvement in high-voltage electrical cbnnectors. In particular, the invention provides a connector from which atmospheric air is essentially excluded by an arrangement of dielectric seals that also allows for convenient coupling and uncoupling without excessive wear. It will also be appreciated that the invention is equally applicable to multi-pin connectors, and to both shielded and unshielded connectors, and that various other modifications may be made without departing from the spirit and scope of the invention.

Accordingly, the invention is not to be limited except as by the appended claims.

Claims (9)

1. A high-voltage electrical connector, comprising: a receptacle assembly having a generally cylindrical insulated body, at least one contact pin of a first type supported in said body, and a resilient dielectric sleeve fitted in said body, and a plug assembly having at least one plug contact pin of a second type sized to couple with said contact pin of the first type, and a relatively nonresilient dielectric sleeve encasing said contact pin of the second type, said non-resilient dielectric sleeve of said plug assembly fitting tightly but easily into said resilient dielectric sleeve to form a complete dielectric seal between said contact pins and said insulated body of said receptacle assembly.

2. The high-voltage electrical connector as claimed in Claim 1, further comprising means for releasbly maintaining said receptacle and plug assemblies in a coupled relationship.

3. The high-voltage electrical connector as claimed in Claim 1, wherein: said relatively non-resilient dielectric sleeve encases the contact pin of the second type entirely except for an end opening to provide access for the contact pin of the first type; and said resilient dielectric sleeve has an open end to permit entry of said relatively non-resilient dielectric sleeve and a closed end with an opening therein to receive said contact pin of the first type.

4. The high-voltage electrical connector as claimed in Claim 1, wherein said resilient dielectric sleeve has a plurality of raised annular portions to provide an improved dielectric seal between said relatively non-resilient dielectric sleeve and said insulated body.

5. The high-voltage electrical connector as claimed in Claim 1, wherein said resilient dielectric sleeve has an integral flange to inhibit its inadvertent removal from said receptacle assembly.

6. The high-voltage electrical connector as claimed in Claim 2, wherein said means for releasably maintaining said receptacle and plug assemblies in a coupled relationship includes: a first coupling element secured to said insulated body of said receptacle assembly; and a second coupling element secured to said plug body; and wherein said first and second coupling elements also serve to provide a grounded electrical connection.

7. The high-voltage electrical connector as claimed in Claim 6, wherein: said first coupling element is a metallic bushing with an external thread and said second coupling means is a lock nut.

8. The high-voltage electrical connector as claimed in Claim 1, wherein: said non-resilient sleeve extends over a portion of an electrical conductor to which said contact pin of the second type is connected and said plug assembly further includes a third dielectric sleeve, positioned between the conductor and said non-resilient sleeve, said third dielectric sleeve also being of resilient material which is compressed during assembly to complete the seal.

9. A high-voltage electrical connector constructed and arranged substantially as herein described with reference to and as illustrated in the accompanying drawings.