Through-wall conductor seal

Abstract

A conductor having a plurality of continuous peripheral recesses is received within a tubular member, the internal surface of which member is also provided with a number of recesses. Resilient seals are located in certain, but not all, of the recesses. These seals are of such dimensions as to extend above the surface or outwardly of their associated recesses, as the case may be. An encapsulant or molding material is provided, filling the space between the conductor and the tubular member. The set-up material compresses the resilient seals to form in the area of the seals a firm fluid-tight seal. Also, the material anchors itself to the conductors via the seal-free recesses. In the event that separation of the material from the conductor or tubular member occurs during use, the compressed resilient seals still maintain a hermetic condition.

Description

The present invention relates generally to the sealing of conductors, and, more particularly, to a seal for use with conductors which pass through a wall separating fluids of considerably different pressures.

BACKGROUND OF THE INVENTION

There are many instances in which it is advisable or necessary to pass an electrical conductor such as a wire cable or the like through a wall or partition which separates fluids having considerably different pressures. Not only is it important to maintain electrical isolation of the conductor from the wall or other surrounding members, but it is also necessary to maintain the proper sealing relation between the disparately pressured fluids to prevent leakage.

Of the many approaches taken in the past to solve this problem, the main one adopted has been that of passing the conductor through an oversize hole formed in the wall or partition and embedding the conductor within an electrically insulative encapsulant or molding material. This material secures itself to both the wall through which the conductor passes and to the conductor, and upon hardening would desirably maintain the conductor in a spaced condition from the wall as well as seal both the conductor and wall adjacent the opening against movement of the pressurized fluids therethrough. Materials used for this purpose have in the past conventionally included such things as glass, ceramic, plastic, rubber and epoxy.

None of these molding materials known to applicant when used alone has been entirely successful for this purpose, primarily in view of the problem presented through the difference in temperature coefficients of expansion of the walls, which are usually metal, the conductor which is also metal, and the molding material. That is, on subjecting the entire assembly to a substantial temperature change, the encapsulant will expand (or contract) at a different rate from that of the wall and conductor, causing the insulating material to break loose from either, or both, the wall and conductor, and create a break in the seal.

The most common material for attempting to produce an hermetic seal about a conductor is glass. That is, a glass frit is placed about the conductor in a containing tube and fused to provide the desired electrical insulation and also effect a seal with the conductor to prevent fluid passage. However, the coefficient of expansion for glass differs sufficiently from most metals that on extended range temperature use and pressure cycling there is a tendency for the conductor to pull away from the glass or the glass cracks, in either case breaking the seal.

In still other approaches to hermetically sealing a conductor in a through-wall construction, use has been made of such things as O-rings, which are received about the conductor and compressingly engage the wall surfaces defining the opening when the conductor with O-ring is received therein. This type of seal is satisfactory for relatively low pressure differentials and moderate temperature range applications, however, it is completely unsatisfactory for high temperature or a high pressure differential situation in that the O-ring may be either destroyed through direct contact with the high temperature fluids or forced from engagement with either the conductor or the wall by the direct action of the higher pressure fluid.

OBJECTS OF THE INVENTION

It is, therefore, a primary object of the present invention to provide an improved sealing structure for a conductor passing through a wall which is operative over a broad range of temperature without losing its sealing qualities.

A further object of the invention is the provision of a through-wall conductor seal which is effective even where the coefficients of expansion of the various parts produce separation.

Yet another object of the invention is the provision of a through-wall conductor seal having a molded insulating body maintaining the conductor and walls in a fixed spaced relation and a resilient sealing member separating portions of the conductor from the body and the body from the wall.

Yet another object of the invention is the provision of a through-wall conductor seal as described in the above objects having a resilient sealing member that is maintained in compression by molded insulating material.

SUMMARY OF THE INVENTION

In accordance with the practice of the present invention the conductor (or conductors) to pass through the wall is provided with a plurality of continuous peripheral recesses extending completely thereabout. A tubular member is received within the wall opening and affixed to the wall in conventional manner, e.g., welding, the internal surface of which member is also provided with a plurality of continuous recesses or grooves. The conductor is then located centrally within the tubular member and an elastomer or other resilient, compressible sealing means are located in the recesses of the tubular member and in certain, but not all, of the recesses of the conductors. These resilient sealing means are of such dimensions as to extend above the surface or outwardly of their associated recesses. Next, a quantity of molten encapsulant or insulating material is provided in the space between the conductor and the tubular member, completely filling the space and which on setting up seals itself to both the interior wall of the tube and the exterior surface of the conductor.

The set-up material compresses the resilient sealing means, thereby forming in the area of the sealing means a firm fluid-tight seal. Also, the insulating material anchors itself to the conductors via the recesses not provided with sealing means. In the event that some separation of the insulation material occurs during extended temperature and/or pressurized operation, either between the material and the tubular member of the material and conductor, the compressed resilient sealing means still maintain the required hermetic seal.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pair of conductors and a container modified in accordance with this invention prior to assembly for through-wall use.

FIG. 2 is a longitudinal sectional view of the pair of conductors and container of FIG. 1 shown fully assembled.

FIG. 3 is an enlarged, sectional, fragmentary view taken through a resilient seal in the assembly of FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 of the drawings depicts a pair of electrical conductors 10 and 11 which are to be assembled within a container 12 in a manner described herein for mounting in a wall. That is, in accordance with this invention the conductors 10 and 11 are for establishing electrical connection through the wall and in such manner that a hermetic seal is maintained in the wall region through which the conductors pass that can withstand very high fluid pressure differentials, e.g., 50,000 pounds per square inch.

In particular, each conductor includes a rodlike body of circular cross-section having a plurality of recesses or undercuts 14 extending completely about the conductor of generally cylindrical shape. The conductor may also include one or more further undercuts 15 extending completely about the conductor periphery and having a curved section. The purpose of these undercuts will be described later.

The ends of the conductors terminate in suitable electrical connection means such as the male jacks 16 or the female connections 17 for effecting interconnection with other electrical equipment or circuitry.

The container 12 is essentially a hollow, metal, openended cylindrical member. The internal surface of the container is formed into continuous recesses or grooves 18 and 19 of curved and rectangular cross-section, respectively. The external container surface has a plurality of pressure grooves 20 formed therein by rolling for example, each such groove being located diametrically opposite a corresponding inner groove 18 and 19 for a purpose to be described.

Turning now to FIG. 2 and the assembly of the conductor through-wall seal, the conductors are initially arranged in predetermined, spaced parallelism by inserting, say, the jack ends into openings 21 of a jig 22. Annular sealing members 23 are fitted onto the conductors and reside in the curved grooves 15. Similarly, other sealing members 24 of rectangular section are received within certain undercuts 14. Each conductor has one or more undercuts 14 and 15 which are left free of either sealing means 23 or 24 as indicated by reference numeral 25 for anchoring as will be more fully described.

Both toroidal shaped sealing means 23 and cylindrical sealing means 24 are described as used. It is to be understood, however, that these are merely representative and that all such sealing means may be optionally toroidal, cylindrical or other shape. An important aspect of these sealing means for satisfactory operation here is that they be of generally annular shape and of such dimensions that they are fittingly received in the undercuts or recesses 14 and 15 or slightly in tension.

Certain of the internal recesses or grooves 18 and 19 of container 12 are fitted with appropriately dimensioned annular sealing means 26 and 27 of circular and rectangular cross-section, respectively. As in the case of the conductors, certain other recesses are left free of sealing means, such as the recess 28, for example. The container is then received onto the outwardly extending conductors and is maintained with its sidewalls spaced from the conductors and its one end abutting against the flat face 29 of jig 22.

A molten, fused or otherwise liquefied encapsulant or insulating molding material 30 is provided through the open container end 31 by pouring or under pressure, filling the space between the conductors and the inner container wall. On setting up, the insulating material secures the conductors within the container both by direct adhesion of the encapsulant to the metal surfaces and the locking or anchoring afforded by the recesses 25 and 28 which do not contain sealing means. In addition, the hardened material compresses the various sealing means 23, 24, 26 and 27 generally flattening them in a plane transversely of the shell long dimension (FIG. 3).

The pressure grooves 20 are formed on the container exterior directly opposite the internal recesses by forcingly gripping the container with a circular crimping tool, for example. As shown, the grooves completely encircle the container, which serves to further compress the sealing means 26 and 27 throughout their full extent.

In use, the completely assembled conductors 10 and 11, secured within the container 12 by the body of hardened insulating material are removed from the jig 22 and emplanted within the wall in any conventional manner, e.g., welding. During normal operation pressurized fluids at either side of the wall are prevented from passing along the surfaces of the conductors or along the container inner wall by insulation adhesion. In the event that the insulation material separates from either the container or the conductors, the compressed sealing means still maintains a hermetic seal. In fact, as seen best in FIG. 3, even a relatively large amount of separation can occur and although the sealing means compression will be relaxed somewhat, there is still a sufficient amount to insure a satisfactory fluid seal.

Although other materials may be found satisfactory for use as a sealing means, best results to date have been obtained by the use of high temperature, flexible elastomers. These materials are not only sufficiently flexible and resilient that they may be compressed for the purposes described herein, but also can withstand temperatures in excess of 500.degree. F. which are encountered in the use of many plastic encapsulants or molding materials.

The embodiment described herein has been particularly set forth as comprising conductors mounted in an insulating body contained wthin a metal container. However, in certain circumstances the container can be eliminated and the conductors provided with the described sealing means and undercuts or recesses and directly sealed within a wall opening via the insulating body. That is, where the wall material is of such construction that its coefficient of thermal expansion is not too dissimilar from that of the molded insulating material so that mutual expansions of the wall and insulating material over the operational temperature range and when subjected to pressure differentials will not break the seal therebetween.

Units consutrcted in accordance with the present invention have been found to provide through-wall connections having hermetic sealing for an extreme differential fluid pressure with leakage on the order of less than 0.01 micron cubic feet/hour. Such units on being subjected to extreme temperature cycling, humidity, pressure, thermal, and physical shocks, saturated steam, vibration and corrosive atmospheres were still found to provide satisfactory hermetic sealing.

Claims

What is claimed is:

1. A sealed insulated electrical connector emplanted within a wall separating fluids of considerably different pressures to provide through-wall connection, comprising:

a hollow metal tube, the inner wall surface of which is formed into a plurality of continuous longitudinally spaced, circumferential grooves;

at least one metallic rod extending along the tube bore, said rod including a plurality of spaced, circumferential grooves;

first resilient annular members received within certain grooves of said metal tube leaving certain other of said grooves free;

second resilient annular members received within certain of said metallic rod grooves leaving certain other of said grooves free; and

a quantity of a rigid, adhesive, insulative material received within said metal tube filling the space between said inner tube wall surfaces and said rod and in continuous adhering contact therewith;

said metal tube with metallic rod and insulative material being secured within a wall opening with the tube ends being exposed to different fluid pressures.

2. A sealed insulated electrical connector as in claim 1, in which the outer surface of the metal tube is deformed inwardly completely thereabout at regions opposite each first resilient annular member after said insulative material is received within said tube.