Cable Introduction Seal in the Cable Introduction Area of a Cable Fitting

The invention is directed to a cable introduction seal composed of an annular seal of elastic material and of an introduction opening adapted therefor in the cable introduction area of a cable fitting.

Such cable introduction seals are known, for example from European Letters Patent EP 0 402 653 A2. This discloses a cable introduction seal of deformable material in the form of an annular plug composed of an expanded elastomer that is introduced into a cable introduction opening in the form of a sleeve of a housing.

Further, introduction seals for uncut cables are known in the form of what are referred to as grommets or, respectively, rubber bushings. These, for example, are mounted in pre-drilled, divided seal members, whereby the planes of division of the seal members are sealed with viscoplastic compound. Simple screw-type connections in the manner of standard stuffing boxes are employed for cut cables to be subsequently introduced. Several disadvantages, however, derive given such seal inserts and screw-type seals. Various known techniques use seals having elastic properties and seals of viscoplastic materials, combined. The spring excursion of the pressed rubber parts thus deriving is extremely small, so that low stored spring power or, respectively, hardly any stored spring power is available for the durable or long lasting pressing. This leads to losses of tightness over time, particularly given longer cyclical temperature stressing. The range of cable diameters to be bridged with these seals is comparatively small, so that corresponding matching elements are necessary. A blind plug must be respectively inserted given non-occupation of an introduction opening.

An object of the present invention is to provide a cable introduction seal with which the afore-mentioned disadvantages are largely overcome whereby a relatively great range of cable diameters can be accommodated economically and efficiently, a retightening capability that is effective over time must be established and whereby the seal must be fashioned such that it is releasable and re-employable after disassembly, without damage.

The stated object is achieved with a cable introduction seal in the form of an annular plug of elastomer introduced into a cable introduction opening in the form of a sleeve of a housing in that the cable introduction opening is fashioned conically converging; in that the annular seal has at least its outside matched to the conical course of the cable introduction opening; in that a pressure means acting on the annular seal in axial direction is arranged at the wide end of the cable introduction opening.

The advantages of the invention over the prior art are that elastic, conical annular seals can be employed for the sealing through the cable introductions, these seals being compressed by an axially acting pressure means within the cable introduction openings which are likewise conically fashioned. Especially good force conditions derive due to the conical fashioning, these leading to the fact that a pressing against the respectively introduced cable ensues in a broad range. A relatively great retightening capability that is preserved over time derives due to the axial compression. In addition, this spring effect can also be intensified by separate, annular spring inserts that can be introduced between the annular surface at the wide end of the annular seal and the annularly fashioned pressure means.

The conical annular seal is preferably initially fashioned closed as a cap at the narrow end, so that unoccupied cable introduction openings are initially closed upon insertion of such an annular seal. Additional elements are thus not required and the cap must merely be cut off as needed. As a result of the conical fashioning, a rough matching to the diameter of the cable to be introduced can thereby simultaneously ensue by cutting at an appropriate location. When the conical annular seal is also provided with a longitudinal slot, then it can also be utilized given uncut cables. However, the cable fitting must then also be fashioned cut with a cable introduction parting plane. Due to the axial pressing power with the assistance of the pressure means, the longitudinal slot is in turn closed as a consequence of the compressive pressure. The sealing effect in the parting surfaces is increased when the annular seal is moistened with suitable fats or oils. The friction upon impression is thereby reduced and a better filling of narrow gaps and striations is additionally possible as a consequence of the better glidability.

Such a cable introduction seal of the invention can be employed in any type of sleeve when the required cooperating surfaces are correspondingly conically fashioned. Thus, the cable introduction opening must comprise a conical fashioning matched to the annular seal, so that the latter can be pressed in along this conical surface. Such a fashioning is applicable for both divided as well as undivided cable introduction regions. A combination is also possible, within a cable introduction area, for example, both divided as well as undivided cable introduction openings can be arranged in the end face of a seal member of a sleeve. Cut and uncut cables can be introduced in this way in such an introduction area.

The conical cable introductions are preferably fashioned such that the wide end is located in the inside of the cable fitting and the narrow end points toward the outside, as a result whereof the pressing region in the inside of the sleeve is likewise protected.

The cable introduction openings are expediently fashioned as projecting connecting pieces, namely having such a length that the introduced cables are supported at the free ends of the connecting pieces given bending loads. It is thereby especially the shearing forces that are kept away from the region of the cable introduction seal.

Given divided cable introductions, the problem of sealing between the annular seal and a profiled seal of the parting plane is resolved in that the profiled seal and annular seal, particularly one having a laterally applied rib, are pressed together in a common channel that proceeds parallel to the conical shape.

The half shells of a cable sleeve or of a seal member composed of two halves, as can likewise be employed, are pressed against one another in a known way, whereby the mutual sealing ensues with the profiled seal.

The assembly with a cable introduction seal of the invention ensues in the following steps:

1) Bringing the individual sleeve parts together;

2) Matching the annular seal to the diameter of the cable to be introduced, whereby the inside diameter is approximately the same as the cable diameter;

3) Introduce cables either through the opening of the annular seal or, potentially, through the longitudinal slot of the annular seal;

4) Apply pressure means and screw the pressure means in axial direction for compressing the annular seal;

5) Close sleeve cylinder.

The invention shall now be set forth in greater detail with reference to six Figures.

FIG. 1 is a perspective view of a divided seal member having an introduced cable introduction seal.

FIG. 2 is a sectional view of the cable introduction seal taken generally along line II--II of FIG. 1, in the parting plane of the seal member.

FIG. 3 is a right side view of the annular seal shown in FIG. 2.

FIG. 4 is a perspective view showing the use of an annular seal of the invention in a cable introduction connecting piece of a cable sleeve.

FIG. 5 is a sectional view taken generally along line V--V of FIG. 4, through the cable introduction opening of the exemplary embodiment of FIG. 4.

FIG. 6 is a partial sectional view of a modification for a pressure means of the cable introduction seal.

As an exemplary embodiment of a cable introduction area, FIG. 1 shows a seal member 1 that can be employed at the face side of a socket pipe. This seal member 1 is longitudinally divided in a parting plane P, so that it can also be employed given the introduction of uncut cables. A cable introduction opening 5 is applied in this parting plane P, whereby this cable introduction opening projects from the front side of the seal member 1 into a connecting piece. The conical annular seal 7 that is still closed at its front side can be seen in this connector-shaped cable introduction opening 5. The halves 2 of the seal member are pressed together with the assistance of applied flanges 3 and 4 and with clamping screws in the bores 9. It is also indicated that cable introduction openings 6 through which only cut cables can be introduced, can be additionally arranged in this seal member 1 since these openings are not longitudinally divided. The ring seals 7 introduced can also be seen here. It is also possible that a plurality of cable introductions are provided in the parting plane 4. A socket pipe is clamped over the seal member 1, whereby a seal insert is placed into the sealing channel 8 for sealing.

FIG. 2 then illustrates the arrangement of the conical annular seal 7 that is introduced in a divided, conically fashioned cable introduction opening 5. The flanges 3 or, respectively, 4 may be seen in the parting plane shown here, whereby the profiled seal 10 and the annular seal 7, preferably with an applied rib 12, are tightly pressed against one another in a common sealing channel 11 that proceeds parallel to the conical shape of the annular seal 7 as well. The annular seal 7 is still shown here as a cap-shaped, closed shaped part, whereby the cut ensues at the location corresponding to the cable diameter as needed in accord with the diameter of the cable to be introduced. Threads 21 are cut, for example, at the wide end of the conical fashioning of the introduction opening, the pressure means being screwed into the threads 21, for example in the form of a ring nut 14. A compression spring insert 15 is introduced in addition to the annular seal 7 and the ring nut 14, this compression spring insert 15 serving the purpose of maintaining a defined pressing power. By screwing the ring nut 14 in, the annular seal 7 is axially pressed against the conical annular surface of the cable introduction opening, the sealing ensuing as a result thereof. When a cable is introduced, the annular seal 7 is also simultaneously pressed against the introduced cable, the sealing being assured as a result thereof. For a longitudinal slot in the annular seal, pressing is likewise carried out such that the necessary sealing ensues along the longitudinal slot.

FIG. 3 shows a front view of a conically fashioned annular seal 7, whereby lateral ribs 12 are additionally applied, these serving the purpose of sealing vis-a-vis the profiled seals of the longitudinal seal of the cable sleeve or, respectively, of the seal member. It may also be seen that the annular seal 7 comprises a longitudinal slot 16, so that this annular seal 7 can also be utilized given uncut cables.

FIG. 4 shows that an annular seal 7 of the invention can also be utilized given uncut introduction areas of a cable sleeve 17, whereby this corresponds to the cable introductions 6 already described in FIG. 1. This cable introduction is fashioned as a connecting piece 18 here, this having such a length that an introduced cable can support itself against the outermost end of the ring given bending loads. The bending loads are thereby kept away from the seal region.

In a cross-section, FIG. 5 now shows the embodiments of FIG. 4, whereby the conditions that have already been described can again be seen therein. The annular seal 7 fashioned conically and cap-shaped is pressed in the conical cable introduction opening 22 with the assistance of an annular forcing nut 14. It is also indicated that a storing of the spring power of the material in the region 20 is possible as a result of the impression. The line 19 indicates that the annular seal 7 can be cut off up to this point; this corresponds to the maximally introducible cable diameter.

In FIG. 6, finally, it is shown that other pressure means can also be utilized, thus, for example, a pressure plate 23 that can be divided and that can be pressed in against the annular seal 7 with screws 25. A projection 24 thereby enables a better guidance within the cable introduction opening. Compression spring inserts can also be utilized here, as were already set forth above. This example is intended to illustrate that other exemplary embodiments are also conceivable with which the same functioning can be achieved.

Given introductions in divided introduction areas, it is not only the annular seal but also the pressure means that must be divided in longitudinal direction so that they can be put in place on an uncut cable. After being put in place, the annular seal and the pressure means must again be annularly closed. Thus, an annular pressure screw can, for example, be composed of two-half parts that are connected to one another via a film hinge, catch or guide cams.

Although the present invention has been described with reference to a specific embodiment, those of skill in the art will recognize that changes may be made thereto without departing from the scope and spirit of the invention as set forth in the appended claims.