Water-Tight Connectors for Electric Cables

It has long been desired to construct water tight plug connectors for electric cables so as to provide a proper seal against access of water when the cable is submerged in deep water. However, serious difficulties have been encountered.

When the connectors are constructed for plugging-in only above the water, it is usual to seal the connector members by elastic gaskets against the entrance of water into the electric contact area in order to avoid grounding and short-circuiting of the contact members by any entering water. These elastic gaskets necessarily are water tight only up to a certain pressure of the surrounding water. They fail when the external water pressure overcomes the mechanical pressure which acts on the sealing gasket. Such plug connectors are therefore useful only down to limited depths of the water.

Other plug connectors are built to allow plugging in under water. Usually the insulating parts of such connectors are constructed in certain shapes and of certain materials so as to disrupt the film of water which otherwise would establish an electrically conductive connection between the surrounding water and the electric contact members. By such constructions, the plugged in connector has sufficient insulative resistance between the surrounding water and any water contained in the contact region of the plug connector. At least one of the insulating parts of such connectors is usually made of an elastic material, the elasticity of which is utilized for disrupting the aforementioned film of water.

It is a disadvantage of connectors of this latter type that continued use of the cable and repeated opening and closing of the plug connections lead to failure by fatigue of the elastic material. The resulting reduction in elastic force of this material makes this material unable to disrupt the water film during and after a new plugging-in process. It has been an additional essential drawback of such connectors, made of elastomeric material, that they could be connected only with cables insulated by elastomeric material, which is not very effective as an electric insulator.

Cable connectors for underwater plugging-in have also been proposed in certain forms designed to displace the water from the contact region during the plugging-in process. These require expensive constructions for the contact carriers with special apertures for escape of water displaced from the contact region. These constructions also require a considerable length of the contact carriers to prevent the entrance of surrounding water after the plugging-in, and they do not provide adequate contact pressure between contact members.

It is an object of the invention to overcome the above-mentioned difficulties.

It is another object to provide a water-tight plug connector for electric cables which allows repeated plugging-in, particularly under water; which can be used in deep water; and which retains the sealing effect, originally provided thereby, after extended use and repeated plugging-in operations.

Another object is to provide a water-tight plug connector of the indicated type particularly for cables insulated by a polyolefin material of high electric resistivity.

The objects have been achieved by providing contact carriers with sealing portions which consist of materials having different elasticities, with annular sealing surfaces engaging each other, and with annular means engaging the sealing portion of greater elasticity for pressing its sealing surface against the other sealing surface.

In one particular embodiment of the invention each of the aligned contact carriers has a plurality of contact members and has a single annular sealing portion surrounding said members. The sealing portions of the combined contact carriers then are pressed together by a single and relatively simple ring.

It is a further particular feature of the invention that the contact carriers are constructed in set-off form, with a support portion of larger diameter and a sealing portion of smaller diameter extending axially from the support portion. The ring or ring means engaging the sealing portion of greater elasticity can then have an outer diameter approximately equal to that of the support portion for the sealing portion of lesser elasticity.

According to one embodiment of the invention one of the contact carriers has a sealing portion consisting of elastic material and a transitional portion, suitably connected with the sealing portion and also with the cable. Particularly when the cable is insulated with polyolefin, the transitional portion can also consist of polyolefin. For connecting the transitional portion with the elastic portion a variety of intermediary members, such as a metal sleeve, can be used.

The various embodiments of the invention provide water-tight sealing for plug connectors usable in water down to great depths. The construction retains its water-tight sealing characteristic for long periods of time, also when the plug connections are opened and closed repeatedly, above the water or under water. At the same time the construction is particularly simple and inexpensive.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

FIG. 1 is a central longitudinal section through a first embodiment of the invention;

FIG. 2 is a similar section through a second embodiment;

FIG. 3 is a similar section through a third embodiment;

FIG. 4 is a similar section through a fourth embodiment; and

FIG. 5 is a similar section through a fifth embodiment.

As shown in FIG. 1, a first cable 10 has a first contact carrier 20 thereon and has a first contact member, particularly a plug 30 molded into the contact carrier 20 with a water-tight seal at 31, against any access of water from around the member 30 into the contact carrier 20. A second and opposite cable 11 has a second contact carrier 40, with a second mating contact member or socket 50 thereon and similarly molded into it. The electrical conductors 24, 25 of cable end portions 10, 11 respectively are suitably welded or soldered or otherwise connected, the one with plug 30 and the other with socket 50.

According to the invention at least sealing portions 21, 41 of contact carriers 20 and 40 respectively, and which respectively surround the contact members 30 and 50, consist of materials of different elasticity. For example in the embodiment of FIG. 1 the entire second contact carrier 40, including its sealing portion 41, consists of material more elastic than the material of the opposite sealing portion 21 and the entire first contact carrier 20. This more elastic portion 41 is formed as a socket, receiving the other contact carrier portion 21.

In further accordance with the invention an annular pressure member 70 engages an outer surface 73 of the more elastic sealing portion 41 so as to press this latter portion radially against the inner sealing portion 21 inserted therein. For this purpose a rigid coupling nut 60 has interior threads 61 in one end portion of the nut engaging exterior threads 22 on an enlarged portion 23 of the first contact carrier 20, while another end portion 62 of coupling nut 60, opposite threads 61, is arranged for sliding contact with an outer surface of the second contact carrier 40. Shoulders 71, 72 are formed coaxially in coupling nut 60 and on the annular pressure member 70, respectively so that when coupling nut 60 is threaded onto the first contact carrier 20 the nut causes sliding of the annular pressure member 70 in one axial direction (as shown, toward left). Mating surface portions 73 in the annular pressure member 70 and on the more elastic sealing portion 41 have frustoconical form so that the axial leftward sliding of annular pressure member 70 presses inner surface portions 74, 75 of the more elastic sealing portion 41 against mating outer surface portions of the less elastic contact carrier portion 21, thereby producing the aforementioned radial pressure. Advantageously, ring 70 consists of synthetic plastic material less elastic than the engaged sealing portion 41, or of substantially rigid material.

In the illustrated embodiment, the surface portion 74 has frustoconical form similar to the outer surface 73 of the more elastic sealing portion 41, while surface portion 75 is cylindrical and is disposed in the endmost part of the elastic member 41, to engage a cylindrical part of the less elastic member 21 disposed between the end of the latter member and its enlarged portion 23.

Advantageously the sealing portion 21 is offset from the enlarged contact carrier portion 23 to such extent that the resulting shoulder 76, facing the annular pressure member 70, provides sufficient room for that member in an approximately cylindrical portion 77 of the coupling nut 60 coaxial with threads 61 and having a slightly smaller inner diameter than these threads. As also shown, shoulders 78 are formed on member 70 and in portion 77 of coupling nut 60 and are arranged so that when this nut is unthreaded from the first contact carrier 20 the annular pressure member 70 is thereby displaced (as shown toward the right), to relieve the aforementioned radial pressure between the sealing portions 21, 41 of different elasticity.

When connectors 20 and 40 are disconnected under water, the contact members 30 and 50 are in contact with the water. When these members are then re-connected under water, by inserting plug 30 into socket 50, water is displaced thereby from the space in the socket and around the plug, along the surface portions 74 and 75 which at this time are not in hermetically sealing contact with one another because of the relatively elastic nature of the outer sealing portion 41. The displaced water escapes readily between threads 22 and 61.

The coupling nut 60 is then threaded onto the first contact carrier 20; for this purpose ribs 63, 64 may be formed on the coupling nut and contact carrier respectively. The threading-on of the coupling nut 60 does not cause further displacement of water from the space between plug 30 and the surrounding parts, particularly in the illustrated preferred embodiment wherein a shoulder 79 is formed in the second contact carrier 40, opposite the end of the first sealing portion 21, so that this portion 21 can first be manually inserted in the second contact carrier 40 all the way to shoulder 79. However, importantly, the threading-on and tightening of coupling nut 60 causes leftward sliding of annular pressure member 70 and thereby establishes high and distributed radial pressure between the sealing portions 41, 21, in such a way that the more elastic portion 41 fully adapts itself to the outer surface of the less elastic portion 21 and hermetically seals the space within these portions from the surrounding water, thereby safely electrically insulating the inter-engaged contact members 30 and 50 from the surrounding water.

The dimensions of the sealing portions 21 and 41, existing in the absence of pressure applied to the more elastic portion 41 by ring 70, can be such that the more elastic portion 41 is not subjected to tension by the mere insertion of the less elastic portion 21. The entire sealing pressure between the sealing portions 21, 41 is then established by pressing the pressure ring 70 onto the more elastic portion 41, that is, by threading-on and tightening the coupling nut 60. However, it is also possible to so dimension the sealing portions 21, 41 as to cause elastic deformation of the latter incident to the initial plugging-in. In this event the resulting initial tension of the elastic material of portion 41 contributes to the ultimate sealing pressure.

Referring now to FIG. 2: In this embodiment the second contact carrier 40a again has a sealing portion 41a of relatively high elasticity but also has a transitional portion 42a consisting of a material which facilitates water-tight bonding of inside surfaces of this portion to outside insulator surfaces of cable 11, these surface portions being indicated at 42a'. Advantageously the insulating material of the cable is a polyolefin and the material of transitional portion 42a (as well as the material of the first contact carrier 20) also is a polyolefin or a copolymer thereof, which can be bonded with the cable insulation in water-tight manner. In addition, water-tight bonding is advantageously provided between the relatively elastic sealing portion 41a and the transitional portion 42a, for example along a surface 41a' .

Another embodiment particularly suitable for cables with polyolefin insulation is shown in FIG. 3. Here the relatively elastic sealing portion 41b of the second contact carrier 40b, as well as the transitional portion 42b, may be made of polyolefins or of polyolefin copolymers, for water-tight bonding to the insulation of cable 11. These portions 41b, 42b are interconnected with the aid of an intermediate member 43, shown as a metal sleeve. Jet molding procedures known to the art may be used for bonding contact carrier portion 42b to cable 11.

In the embodiment shown in FIG. 4 the first and second contact carriers 20c, 40c have a plurality of contact members, again shown respectively as plugs 30 and sockets 50. The contact carriers 20c, 40c have a plurality of sealing portions 21c, 41c respectively, each surrounding one of the contact members and each projecting from a larger part of the corresponding contact carrier. In this embodiment the annular pressure member 70c desirably has a plurality of circular apertures therein.

Referring finally to FIG. 5: This last embodiment, like that of FIG. 4, provides a plurality or set of contact plugs 30 and contact sockets 50 respectively on the first and second contact carriers 20d, 40d, but each set, not each individual plug and socket, is surrounded by a sealing portion 21d, 41d common to these several contact members. A common annular pressure member 70d, with a single coaxial circular aperture, is provided in this case.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of cable connectors differing from the types described above.

While the invention has been illustrated and described as embodied in water-tight connectors for electric cables, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.