EP0033814A2

EP0033814A2 - Electrical connector including surge protection for a plurality of circuits and method of making same

Info

Publication number: EP0033814A2
Application number: EP80401536A
Authority: EP
Inventors: Hugh Andrew Kearney; Linnea E. Wilson
Original assignee: Bendix Corp
Current assignee: Bendix Corp
Priority date: 1979-12-17
Filing date: 1980-10-29
Publication date: 1981-08-19
Also published as: EP0033814A3; JPS5697981A

Abstract

Electrical connector including surge protection for a plurality of circuits, this connector (10) having a plurality of electrical contacts (300) extending through a connector shell (100) and mounted by insulating members (210, 220) to the shell (100), the insulating members (210, 220) defining a sealed chamber (500) within an intermediate portion of the shell (100); a ground plane (400) is mounted to the shell (100) within the sealed chamber (500) and includes a plurality of apertures (410), each aperture (410) receiving a contact (300) Therethrough with the contact (300) being smaller than the aperture (410) to provide a spacing (415) between the contact (300) and the ground plane aperture (410), the spacing (415) and the sealed chamber (500) being filled with a low pressure inert gas having a small amount of ionizable gas; in response to an electrical potential surge on the contact (300) (e.g., from lightning), the ionizable gas breaks down and allows a arc to pass between the contact (300) and the ground plane (400) to thereby dissipate electrical energy of said electrical potential surge.

Description

The present invention relates to an electrical connector including surge protection for a plurality of circuits, said connector comprising: a shell; a plurality of contacts extending through the shell; means for sealing the contacts within an intermediate portion of the shell to provide a sealed chamber within said shell; a ground plane mounted to the shell within the sealed chamber and including apertures through which the contacts extend, each of said apertures being larger than the contact passing therethrough to provide a spacing between said contact and the surface of the ground plane aperture; a gaseous ionization medium filling the sealed chamber; and a spark gap arrangement located within the sealed chamber.
Such connectors have been proposed in the prior art, for instance, in U.S. Patent 3,992,652 and have a very similar purpose, with common constructional features. However, this U.S. patent mounts each electrical contact within a ground plane by an individual glass bead. Such a glass bead is very difficult to position and maintain intact during manufacturing of the connector. Furthermore, a surface of the glass bead may accumulate debris during the manufacturing process, with said debris adversely affecting the electrical characteristics. Further, the operation of the surge arrestor according to this U.S. patent contemplates arcing of electrical current in energy-dissipating arcs across the surface of the glass bead. Such arcs tend to deposit a material residue which alters the electrical arc characteristics and adversely affects the electrical characteristics of the surge protection and reduces insulation resistance.
Similar connector arrangements are shown in U.S. Patents 3,790,858; 3,626,237; 3,778,752; 3,702,420 and 3,867,670. These appear similar in construction and operation to the U.S. Patent 3,992,652 and therefor have similar limitations.
The present invention overcomes the disadvantages and limitations of the prior art arrangements by providing an electrical connector including surge protection for a plurality of circuits, said connector comprising: a shell; a plurality of contacts extending through the shell; means for sealing the contacts within an intermediate portion of the shell to provide a sealed chamber within said shell; a ground plane mounted to the shell within the sealed chamber and including apertures through which the contacts extend, each of said apertures being larger than the contact passing therethrough to provide a spacing between said contact and the surface of the ground plane aperture; a gaseous ionization medium filling the sealed chamber; and a spark gap arrangement located within the sealed chamber, said spark gap arrangement being provided by the gaseous ionization medium filling the spacing between each contact and the surface of the respective ground plane aperture, said medium providing a path between the contact and the surface of the respective ground plane aperture for an electrical spark in response to an electrical surge occurring on the contact to dissipate the electrical surge potential.
The electrical connector of the present invention is advantageous in that while it is less expensive to manufacture it presents between the ground plane and the contacts no surface on which may accumulate debris and/or material residue from the arcing process.
One way of carrying out the invention is described in detail below with reference to the drawings which illustrate one specific embodiment, in which:

FIGURE 1 is a cross-sectional view of the electrical connector of the present invention; and
FIGURE 2 is a partial cross-sectional view of a portion of the electrical connector of FIGURE 1, taken along the line II-II thereof looking in the direction of the arrows.

Referring now to FIGURE 1 there is shown an electrical connector 10 including a shell 100, first and second glass members 210,220, a plurality of electrical contacts 300 (only one of which is shown in this view), a grounding plate 400 (also referred to in the art as a ground plane), and a sealed internal chamber 500.
The shell 100 is shown in one exemplary form, although many others could be used. In this form, the shell 100 includes a passage 110 extending through the shell. The shell 100 includes a first shell half 102, a second shell half 104, a first ring member 106, a second ring member 108 and a welded joint 109 which joins the ground plane 400 and the two ring members 106,108.
The first and second glass members 210,220 are mounted within the passage 110 and include a plurality of contact-receiving apertures 216,226. With the contacts 300 mounted in each of the contact-receiving apertures 216,226 of the glass members 210,220, the shell halves 102,104 and the rings 106,108 sealed together and the glass members appropriately seated within the passage 110 of the shell 100, the chamber 500 is effectively sealed from the environment outside the connector shell 100. Advantageously, outside the glass members 210 and 220 there are respectively provided a main joint gasket 212 and an interfacial seal 214.
The shell 100 includes a port 120 through which the chamber 500 may be first evacuated, then filled with an appropriate ionization-medium. In its preferred embodiment, the chamber 500 is filled with a low pressure inert gas(Argon) which is provided with a trace of tritium (H₃) which serves as an ionization prompting medium. In the presence of a sufficiently-high electrical potential across the ionization medium, the tritium gas tends to break down and provide an arcing path. The inert gas and ionization prompting gas together provide a gaseous mixture used to fill the chamber 500 of the connector. Advantageously, the gas fill is maintained at a relatively low pressure of approximately 12 Tor, compared to a normal sea level atmospheric pressure of 760 Tor.
The ground plane 400 includes a plurality of apertures 410 through which the electrical contacts 300 are mounted. The passages 410 are located generally concentric with the contacts 300 passing therethrough with each passage 410 being larger than the diameter of the contact portion mounting therein, providing a gap 415 between the passage wall and the contact 300. In the presence of an electrical surge on the contact 300, the increased voltage of the surge is dissipated in an arc between the contact 300 and the ground plane 400.
In the present design, there is no provision of a _r spacing material between the contacts 300 and the ground plane 400. This unfilled gap provides a spacing, which combines with the presence of the gas fill in the chamber 500 and allows the gas fill to surround the contact 300 and fill the space between the contact 300 and the passage wall of the ground plane 400. This gas fill provides a current path around the perimeter of the contact and also along the length of the ground plane. This is a substantially greater area for a potential arc than is shown in the above mentioned U.S. Patent 3,992,652 where the space between each contact and the ground plane is filled with a glass bead serving as an insulator. In such a case, the arc path between the contact and the ground plane is limited to front and rear faces of the glass bead mounting the contact to the ground plane.
The contact 300 includes a first pin member 310, a second pin member 320 and a connection 330 between the first pin member and the second pin member. The connection is preferably a solder cup 332 receiving a rear end 334 of the pin 310. Therein, the connection 330 between the solder cup 332 and the rear pin end 334 is preferably accomplished by solder or tin plating the pin end 334 and/or the solder cup 332 to have a interference fit, then accomplishing "blind soldering" with a hot oil bath flowing over the solder to melt it, forming an electrical coupling when the solder cools and solidifies.
FIGURE 2 illustrates a portion of the ground plane 400, with the contact 300 passing through the aperture 410 in the ground plane. The spark gap region 510 is between the contact 300 and the ground plane 400 and is also filled with the low pressure gas mixture (including the ionization _. prompter).
A method of making the connector of the present invention is also disclosed in which the connector and each contact are made in two halves which are positioned by a fixture. Each contact passes through and is centered within a ground plane aperture larger than the contact. Once the positioning is achieved by the fixture, the connector and contact halves are disassembled and the fixture removed, connector and contact halves reassembled and contact halves connected by soldering, then the connector halves are welded together to form a sealed internal chamber. The chamber is then evacuated and filled with a low pressure gaseous ionization mixture which fills the space between the contact and the ground plane and provides a spark discharge arcing medium.
Of course, the present invention is capable of many modifications and substitutions which may vary the structure on appearance of the present invention without departing from the spirit of the invention. For instance, other configurations of contacts and shells are possible and known in the trade. The contact could be made of three pieces, including two solder cups, for example, or with filters. The gas filling the chamber could be a single type of gas, provided it had appropriate breakdown (ionization) characteristics, for which a radioactive-type gas is believed desirable. Alternatively to the disclosed Argon, other inert gases (or mixtures thereof) could be used, with a suitable ionization- prompter.

Claims

1. Electrical connector including surge protection for a plurality of circuits, said connector (10) comprising:

a shell (100); a plurality of contacts (300) extending through the shell (100); means (210,220) for sealing the contacts (300) within an intermediate portion of the shell (100) to provide a sealed chamber (500) within said shell (100); a ground plane (400) mounted to the shell (100) within the sealed chamber (500) and including apertures (410) through which the contacts (300) extend, each of said apertures (410) being larger than the contact (300) passing therethrough to provide a spacing between said contact (300) and the surface of the ground plane aperture(410); a gaseous ionization medium filling the sealed chamber (500); and a spark gap arrangement located within the sealed chamber (500); characterized in that said spark gap arrangement is provided by the gaseous ionization medium filling the spacing (415) between each contact (300) and the surface of the respective ground plane aperture (410), said medium providing a path between the contact (300) and the surface of the respective ground plane aperture (410) for an electrical spark in response to an electrical surge occurring on the contact (300) to dissipate the electrical surge potential.

2. Method of making an electrical connector including surge protection for a plurality of circuits, characterized in that it comprises the steps of: mounting a plurality of contact portions (310,320) in a spaced relationship within two connector halves (102,104) in respective sealing members (210,220), the contact portions (310) in one connector half (102) being mateable with the respective contact portions (320) in the other connector half (104) to form contacts (300); assembling the connector halves (102,104) with the contacts (300) extending through contact-receiving apertures (410) in a ground plane (400); positioning the contacts(300) within the ground plane apertures (410); coupling the cooperative contact portions (310,320) together; sealing the connector halves (102, 104) together to form a sealed chamber (500); and filling the sealed chamber (500) with an ionizable gas, with said gas in addition surrounding each contact (300) between it and the surface of the respective ground plane aperture (410) to provide a spark arc path.