MXPA97005851A - Seal device - Google Patents

Abstract

The present invention relates to a device for sealing the end of an elongated cable, comprising: 1) a housing of generally tubular shape having: a) a first open end and a second closed end, b) a longitudinal upper portion with an inner surface and an outer surface, c) a longitudinal lower portion with an inner surface and an outer surface, and 2) an insert that is disposed within the housing and is free to move in an axial direction within the housing and in a vertical direction within the housing. of the housing, which a) is in the form of a clip provided with a first open end and a second closed end b) comprises a first upper arm with an internal surface and an external surface and a second lower arm with an internal surface and an outer surface, said first and second arms extending from the closed end of the insert; c) a plurality of first securing members; which are associated with the inner surface of the first arm, and d) a plurality of second holding members that are associated with the inner surface of the second bra

Description

SELLAPOR DEVICE FIELD OF THE INVENTION The present invention relates to senator devices, and, more particularly, to senators devices for heating cables.

INTRODUCTION TO THE INVENTION It is often necessary to seal the end of an elongated cable, such as a power supply cable or a heating cable in order to provide electrical isolation, environmental protection and / or mechanical shielding. There are several methods to provide such seal, including tubes, end caps or thermo-recoverable covers; molded covers filled with adhesive; boxes provided with seals or boards, and rolled tapes. Many of these methods require craftsmanship, are difficult to install, require special tools or are limited to cables of particular size or shape. In addition, some of these techniques require multiple pieces that are difficult to manufacture and install. Elongated heating cables are a type of cable that often requires an end seal. Such heating cables are used to protect against freezing and for temperature maintenance in pipes. Particularly useful heating cables comprise (a) elongated first and second electrodes, (b) a plurality of resistive heating elements connected in parallel between said electrodes, for example, a continuous strip of conductive polymer in which the electrodes are embedded or which is wound around the electrodes, and (c) an insulating sheath surrounding the electrodes and heating elements. In addition, the heating cable often comprises a metal grounding layer in the form of a braided jacket or a tape surrounding the insulating sheath and serving to electrically ground the heating cable and provide resistance to abrasion. The heating cable can be cut to the appropriate length to be used in each application and the ends must then be protected. e known end caps and senators to protect the cut ends. These sensing devices not only seal the ends but prevent them from being exposed to moisture and hold the heating cable in order to prevent it from being detached from the sealing device during use. The device described in US Pat. No. 4,751,350 (Eaton) comprises a cap having a plurality of elastic projections disposed at specific angles and allowing an electric cable to be held. The cap provides a particularly effective seal when it is filled with a gel or other conformable material that makes effective contact with the inserted cable. The device described in US Pat. No. 4,877,943 (Oívva) comprises a cap which is used graduated length projections, arranged at specific angles are used to hold both the insulating sheath and the braided metal jacket e a heating cable in order to preventing the braided jacket from slipping with respect to the insulating sheath which would reduce the tensile strength, ie the force required to remove the heating cable from the sealing device. One problem with the conventional senator devices described in U.S. Patent Nos. 4,751,350 and 4,877,943 is that a relatively high force, eg, 3.6 to 4.5 Kg. Is required to insert the cable into the device. . This is because it is necessary to flex the inner projections of the device enough to trap the cable. In addition, a material, usually a plastic, that allows such deflection will often not be stubborn enough to provide the required impact resistance. Accordingly, if the device is to be economically manufactured, for example, by molding, a compromise must be made between the materials used for the cap and for the projections. During impact tests, the resulting sealing device may experience bending and deformation of the protrusions which decreases the resistance to extraction. In addition, although fastener devices with graduated length projections are known, it is often necessary to have devices of different sizes in order to accommodate and maintain adequate pull-out resistances for cables of different thicknesses and / or widths.

COMPENDIUM OF THE INVENTION We have now found that it is possible to manufacture a sealing device that requires a relatively low insertion force, is suitable for a wide variety of sizes and shapes of cables, has a resistance to proper extraction and impact and is easily manufactured and assembled. This is accomplished by using within the housing, a separate insert that is designed to be flexible. The insert can be made in different sizes depending on the requirements of the cable, but due to the flexibility and shape of the insert, a single insert is suitable for use with a variety of cables. As a result of this design, the different functions of the sealing device, ie isolating, providing mechanical protection, providing stress relief and sealing, are separated and optimized. Thus, in a first aspect, the present invention provides a device for sealing the end of an elongated cable, comprising: (1) a housing of generally tubular shape having: (a) a first open end and a second end closed; (b) a longitudinal upper portion with an inner surface and an outer surface; c) a longitudinal lower portion with an internal surface and an external surface; and (2) an insert that is disposed within the housing and is free to move in an axial direction within the housing and in a vertical direction within the housing, which (a) has the shape of a clip provided with a first open end and a closed second end; (b) comprises a first upper arm with an inner surface and an outer surface and a second lower arm with an inner surface and an outer surface, said first and second arms extending from the closed end of the insert, c) a plurality of first members of clamping that are associated with the inner surface of the first arm, and (d) a plurality of second clamping members that are associated with the internal surface of the second arm. In a second aspect, the present invention provides an assembly comprising: (A) an apparatus according to the first aspect of the invention in which the insert further comprises: (e) at least a first pre-clamping member which is associated with the inner surface of the first arm, and (f) at least a second pre-grip member that is associated with the inner surface of the second arm; and said apparatus further comprising (3) a gel component; and (B) one end of an elongated cable that is inserted through the open end of the insert and that is in direct contact with the gripping end of at least one first clamping member, a second clamping member, a first member of pre-grip and a second pre-grip member.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a longitudinal section of an apparatus according to the invention; Figure 2 is a longitudinal section of an insert that is part of the device; Figure 3 is a section of a pre-grip member that is part of the device; and Figures 4a and 4b are schematic sections of an assembly according to the invention.

DETAILED DESCRIPTION OF THE INVENTION The sealing device of the invention can be used to seal the end of any elongated cable, including electrical heating cables such as self-limiting heating strips or mineral insulated heating cables, power supply cables or grounded conductors. Electric heating cables particularly suitable for use with this sealing device are those comprising first and second elongate electrodes, a plurality of resistive heating elements connected in parallel between the electrodes and at least one insulating sheath surrounding the electrodes and the heating elements. . The insulating sheath is usually polymeric, in the form of a continuous polymeric layer, although a polymeric braid or a polymeric tape can be used. For some applications, an insulating polymeric sheath is surrounded by a second layer, for example a second insulating polymeric layer such as a polyester tape, or a metallized tape such as aluminized polyester. The heating cable often comprises an optional braided metallic earth jacket that surrounds the insulating sheath and the optional second layer. The braided metallic earthing jacket serves to electrically connect the heating cable to earth and also provides mechanical and abrasion resistance. When a metal grounding jacket is provided, it is generally in the form of braided metal wires, although in applications where flexibility is not critical, it is possible to use another type of metal layer, for example, a metal sleeve or tape. In this description, the expression "braided metal jacket of ground connection" should be interpreted as including non-braided metal layers. In some applications, the braided earthing jacket is surrounded by an external insulating sheath to provide electrical and environmental insulation to the heating cable. Particularly suitable heating cables are self-regulating heating strips in which the electrodes are elongated conductors and the heating elements comprise a conductive polymer composition. Heaters of this type are described in U.S. Patent Nos. 3,858,144 (Bedard et al.), 3,861,029 (Smith Johannsen et al.), 4,017,715 (Whitney et al.), 4,242,573 (Batliwalla), 4,334,148. (Kampe), 4,334,351 (Sopory), 4,426,339 (Kamath et al.), 4,459,473 (Kamath), 4,574,188 (Midgley et al.) And 5,111,034 (Batliwalla et al.). The heating cable generally has an approximately rectangular cross section with two generally parallel faces, although other configurations, eg, oval or elliptical can also be effectively sealed by the sealing device of the present invention. The housing of the device of the invention can be of any shape, for example, generally tubular or rectangular in so far as it includes a first open end of a shape suitable for the insertion of the cable, and a second closed end. In addition, the interior shape of the housing must be adequate to accept an insert. The housing can be in one piece that has been molded around the insert in the proper manner, or can be assembled in a permanent configuration from a number of pieces, or can comprise first and second housing members capable of adopting a configuration unpaired and a paired configuration. In the unpaired configuration, the housing members may be separate pieces or they may be connected, for example, by hinges, bands or an elastic interference fit. When paired, the two housing members are in mutual contact either directly or through a stamp member, eg, a board, and in such a paired configuration, the two housing members form a housing having an opening. It is particularly preferred that the housing be formed of two identical parts that are permanently attached, for example, by ultrasonic welding or adhesive. The use of identical housing members allows to decrease the number of different components required for the device. The housing can be physically or virtually separated in an upper longitudinal portion and a lower longitudinal portion, the terms "upper" and "lower" being defined with respect to the geometrical axis of the housing that coincides with the axis of the opening. The upper and lower portions both comprise an internal surface that is adjacent and parallel to the opening and an outer surface that is generally the exterior of the housing. Although the thickness of the wall of the housing is preferably constant, for some applications it is preferred that there are internal ribs or ribs to provide mechanical strength. On one or both of the inner surfaces of the upper and lower portions, there may also be teeth or locking grooves which serve to bind and lock with a locking mechanism present in the insert. The cable is clamped by means of an insert that is arranged inside the housing. In order to accommodate a variety of sizes and shapes of cable and to require a relatively low insertion force, it is important that prior to insertion of the cable, the insert is free to move in the axial direction within the housing and also in the vertical direction within of the housing, that is to say perpendicularly to the axis of the housing. The insert has the shape of a clip having a first open end and a closed second end. The closed end is rounded, that is, it has a semicircular shape on its inner surface, that is, the surface facing the opening of the housing. Extending from the closed end of the insert there is a first upper arm and a second lower arm, each of which has an internal surface facing the inserted cable and an external surface facing the internal surfaces of the upper and lower portions of the housing. To facilitate the insertion of the cable, it is preferred that at least part of the inner surface of the first and second arms closest to the open end be chamfered, i.e. the thickness of the arms be tuned towards the opening, and it is particularly preferred that the internal surface of the upper and lower portions of the housing has a complementary inclination to that of the external surface of the arms. The contact and clamping of the inserted cable is achieved by a plurality of first clamping members that are associated with the internal surface of the first arm and a plurality of second clamping members that are associated with the internal surface of the second arm. The clamping members are spaced longitudinally from the open end to the closed end of the housing at regular or graduated intervals. The first and second clamping members are preferably arranged directly opposite each other, instead of being interposed in order to facilitate the insertion of the cable and avoid the need to force the cable into a serpentine configuration. The clamping members generally cover the total circumference of the opening. They are preferably of uniform length measured from the base of the clamping member, on the inner surface of the arm, to the end or crest of the clamping member. In order to achieve a sufficiently high pull strength, it is preferred that in addition to the first and second clamping members, the insert also includes a first pre-clamping member associated with the inner surface of the first arm and at least one second pre-clamping member associated with the inner surface of the second arm. The pre-clamping members are disposed near the closed end of the insert, between the closed end and the clamping members. Preferably, the first and second pre-clamping members are arranged in directly opposite manner.

Both the clamping members and the clamping members are of generally rectangular cross-section, although other shapes may be used. The clamping and pre-clamping members are preferably arranged perpendicular to the respective internal surfaces of the embrasures of the insert. Due to the flexibility of the insert, there is no need to position the clamping or pre-clamping members at an angle in order to obtain an adequate grip of the cable. Although the gripping surface of the clamping and pre-clamping members may be flat and perpendicular to the base, it is preferred that the clamping and pre-clamping members have a gripping end that is at an angle A with respect to the axis of the clamping member. accommodation, from 35 to 60 degrees, particularly, 40 to 55 degrees, especially around 45 degrees. For the pre-grip members it is preferred that the grip end have an angle A of 15 to 40 degrees, particularly 20 to 35 degrees, especially around 30 degrees. The angle A opens towards the open end of the housing so that when a pulling force is applied to the cable, the holding members will hold the cable more firmly. For some applications, the grip end can be serrated. The dimensions of the clamping and pre-clamping members depend on the size and shape of the cable to be inserted. For cables with a thickness of 2.5 to 6.4 mm, the clamping and pre-clamping members will often have a base with a thickness of 0.25 to 0.76 mm, for example, 038 mm and a thickness of grip end 0.025 to 0.25 mm, for example, 0.076 mm. To facilitate installation, it is necessary that the fastening members that are close to the open end be much shorter than the pre-fastening members that are close to the closed end. Generally, the pre-clamping members have a length that is at least two times, preferably at least three times, particularly at least four voices, for example, 5 to 7 times, the length of the clamping members. The clamping members generally have a length of 0.25 to 1.8 mm, preferably 0.38 to 1.65 mm, particularly 0.51 to 1.5 mm, especially 0.64 to 1.0 mm, while Pre-clamping members generally have a length of 1.3 to 7.6 mm, preferably 1.9 to 6.4 mm, particularly 2.5 to 5.1 mm. In order to improve the resistance to extraction it is desirable to provide a locking mechanism on the outer surface of at least one of the arms of the insert. The locking mechanism can be of any type, but a finely tuned "wing" projecting from the outer surface of the arm and being able to be linked with locking teeth disposed on the inner surface of the housing is preferred. In order to provide the greatest resistance to removal, it is preferred that there be a locking mechanism in both arms and that there are locking teeth on the inner surface of the upper longitudinal position and the lower longitudinal portion of the housing. By inserting the cable into the housing so that the cut end of the cable contacts the closed end of the insert, the pre-clamping members, which are substantially longer than the clamping members, make initial contact with the cable and the cable. The closed end of the insert flexes opening. When the cable is pulled out, the insert is closed causing the clamping members to penetrate the outermost layer of the cable, ie the insulating sheath of the heating cable, or the braided jacket if present. This closing of the insert also causes the locking mechanism to act by preventing the forward movement of the insert or the cable. If there is no gel component in the housing, there will be an audible indication, that is, a "click", when the insert and lock are complete. It is important that the cable is held in position with sufficient force so that it can not be easily removed from the sealing device. Generally, an "extraction force" of at least 1 1 is required, 4 Kg., Preferably at least 13.6 Kg., Particularly at least 15.9 Kg. for routine uses. (The extraction force can be measured with an Instron tensile tester (MR) The installed cable is held by one clamp of the test apparatus and the sealing device by the other clamp The force required to extract the cable is measured 3.2 mm outside the sealing device when the clamp that holds the sealing device is fixed and the clamp that holds the cable is moved). In order to achieve such an extraction force, each of the clamping members penetrates the surface of the cable with which it is in contact, for example, the insulating sheath, the braided jacket or the external coating at least 0.25 mm, preferably at least 0.38 mm, particularly at least 0.51 mm, especially at least 0.64 mm. The housing and the insert may comprise an insulated metal or a ceramic but preferably comprise a polymer having an impact strength of at least 68 cm.Kg. (5 ft. Lbs.) When given the final conformation of the sealing device, measured by tests such as UL746C. Preferred polymers include polycarbonate, nylon, polyester, polyphenylene sulfide, polyphenylene oxide and other plastics used in engineering. Appropriate fillers and stabilizers can be used. For some applications it is preferred that the housing be made of a transparent polymer in order to facilitate the determination of the proper location of the inserted cable. The polymer used for the housing and the insert may be the same, but it is preferred that the insert be made of a softer material than the housing so that the insert has flexibility and the housing has impact resistance. It is preferred that the housing have an impact strength of at least 136 cm.Kg. (10 ft. Lbs.) The clamping and presucking members may be made of a polymer different from that of the housing and / or insert although it is preferred that the polymer be the same as that of the insert to facilitate its manufacture. For some applications, it is desirable that part or all of the sealant device be filled with a viscous sealant material in order to provide a good environmental seal at the end of the cable. Suitable materials include greases, adhesives, mastics, gels and other materials that, under compression tend to conform to the surface of the cable to provide a seal. Gels, for example, silicone gels, such as those described in U.S. Patent Nos. 4,600,261 (Debbaut), 4,690,831 (Uken et al.), 4,716,183 (Gamarra et al. others), 4,777,063 (Dubrow et al.), 4,864,725 (Debbaut et al.), 4,865,905 (Uken et al.), 5,079,300 (Dubrow et al.), 5,104,930 (Rende et al.) and 5,149. 736 (Gamarra) and in International Patent Publications Nos. WO86 / 01634 (Toy et al.), WO88 / 00603 (Francis et al.), WO90 / 05166 (Sutherland), WO91 / 05014 (Sutherland), and W093 / 23472 ( Hammond and others). The gel component is preferably placed in the housing before use. If the housing members are used the gel component can be placed in one or both. When the housing members are in the paired configuration, the gel component is displaced over the end of the cable and the insulating sheath, and over the braided jacket that could be inside the housing. The presence of the gel component minimizes moisture ingress from the outside of the housing, from the cable and from any braided jacket that may be present. The sealing device of the invention can be used as part of an assembly that includes a cable and a gel component. In the assembly, the gel component deforms and seals around the cut end of the cable and the outer surface of the cable. In general it is preferred that the braided jacket and any other external insulating coating be removed before inserting the cable into the housing so that it is the insulating sheath that is bitten by the fastening members. Nevertheless, if the clamping members are long enough, they will act to hold the braided shirt and provide sufficient pull strength. If it is necessary to fasten the braided jacket and also the outer insulating coating, it is preferred that the insert has a longer length from its closed end to its open end and / or that there are more fastening members than for an insert intended only to hold the insert. insulating sheath. The invention is illustrated by the accompanying drawings in which Figure 1 is a section of the sealing device 1. The device comprises a housing that is formed of an upper longitudinal portion 5 having an inner surface 7 and an outer surface 9, and a lower longitudinal portion 1 1 having an inner surface 13 and an outer surface 15. The upper portions 5 and lower 1 1 together form the open end 17 and the closed end 19. On the internal surfaces 7, 13 there are locking teeth 21. An insert 23 having long arms and holding members for holding both the braided metal jacket and the insulating sheath of a heating cable is disposed within the housing 3. The line ll represents the axis of the housing 3 through the open end 17 A gel component, not illustrated, fills the interior of the housing 3 and surrounds the insert 23. Figure 2 illustrates a longitudinal section of the insert 23 designed to hold the insulating sheath of a cable. The insert 23 is in the form of a clip with an open end 25 and a closed end 27. The inner surface 28 of the closed end 27 is rounded. A first upper arm 29 has an inner surface 31 and an outer surface 33. From the inner surface 31 project first fastening members 41 and first pre-fastening members 45. A second lower arm 35 has an internal surface 37 and an outer surface 39. Second clamping members 43 and second pre-clamping members 47 protrude from the internal surface 37. The end 30 of the upper arm 29 and the end 34 of the lower arm 35 are refined and have an inclined surface that opens towards the opening. . A locking mechanism 49 is present on the external surface 33 and on the external surface 39 of the arms of the insert. Figure 3 is a section of a second presumption member 47 projecting from the inner surface 37 of the lower arm 35. The clamping surface 51 of the clamping end 53 is inclined at an angle A with respect to the axis of the insert and housing . Figure 4a illustrates, in section, a heating cable 55 after its insertion in the insert 23. The braided sleeve 57 has been removed from the section of the heating cable 55 that contacts the insert 23 to ensure that the insulating sheath 59 is gripped by the clamping members 41, 43. As illustrated in Figure 4b, after the heating cable 55 has been locked into place by the application of an inal length force between the device 1 and the heating cable 55, the locking mechanism 49 is linked with the locking teeth 21 and the insert 23 is closed. As a result, the insert 23 has moved away from the interior of the closed end 19 of the housing.

Claims (10)

1. A device for sealing the end of an elongated cable, comprising: (1) a housing of generally tubular shape having: (a) a first open end and a second closed end; . (b) a longitudinal upper portion with an inner surface and an outer surface; c) a longitudinal lower portion with an internal surface and an external surface; and (2) an insert that is disposed within the housing and is free to move in an axial direction within the housing and in a vertical direction within the housing, which (a) has the shape of a clip provided with a first open end and a closed second end; (b) comprises a first upper arm with an inner surface and an outer surface and a second lower arm with an inner surface and an outer surface, said first and second arms extending from the closed end of the insert; c) a plurality of first clamping members that are associated with the internal surface of the first arm, and (d) a plurality of second clamping members that are associated with the internal surface of the second arm.

A device according to claim 1, characterized in that the insert further comprises (e) at least a first pre-suction member that is associated with the inner surface of the first arm, and (f) at least one second pre-clamping member that is associated with the inner surface of the second arm.

A device according to claim 1 or 2, characterized in that the housing comprises two housing members which may be in (a) an unpaired configuration or (b) a paired configuration in which the clamping members are in contact mutual and form a housing, the two members being identical.

A device according to any one of the preceding claims, characterized in that the internal surface of the upper longitudinal portion and the inner surface of the lower longitudinal portion comprise locking teeth and that at least one of the outer surfaces of the first arm and the second arm comprise a locking mechanism capable of connecting with the locking teeth.

5. A device according to any of the preceding claims characterized in that the housing is made of a transparent polymer.

A device according to claim 2, characterized in that: (1) each of the first clamping members and the first pre-clamping members comprise a base associated with the internal surface of the first arm, (2) each one of the second clamping members and the second pre-clamping members comprise a base associated with the internal surface of the second arm, and (3) each of the first clamping members, the second clamping members, the first clamping members, and pre-clamping and the second pre-clamping members comprises a gripping end which (a) is inclined at an angle A with respect to the geometry of the housing and (b) is capable of penetrating an insulating sheath or a braided jacket of a cable .

7. An apparatus according to claim 6, characterized in that the gripping end has an angle A of 15 to 60 degrees, with the angle A of the gripping end of the first gripping members and of the second gripping members being 35 to 60 degrees and the angle A of the gripping end of the first gripping members and the second gripping members being. Pre-clamping members from 1, to 40 degrees.

8. A device according to any of the preceding claims, characterized in that it comprises a gel component.

9. An assembly comprising (A) an apparatus according to claim 2 and (B) an end of a cable that is inserted through the open end of the insert and that makes direct contact with the grip end of at least one a first clamping member, a second clamping member, a first clamping member and a second clamping member.

10. An assembly according to claim 9, characterized in that the cable is an electrical heating cable comprising (a) first and second elongated electrodes, (b) a plurality of resistive heating elements connected in parallel between said electrodes, (c) an insulating sheath surrounding said electrodes and heating elements, and (d) an optional metallic braided earthing sleeve surrounding said insulating sheath in which the grip end of at least a first clamping member, a second clamping member, clamping, a first pre-clamping member and a second pre-clamping member makes direct contact wthe insulating sheath or the optional braided sleeve RESU MEN An apparatus (19) for sealing the end of an elongated cable (55) such as an electric heating cable, which comprises a clip-like insert (23) placed inside a tubular-shaped housing (3). The clamping members (41, 43) and pre-clamping members (45, 47) project from the internal surfaces (31, 37) of the arms of the insert and act to hold a cable (55) when it is inserted into the body. the device. A locking mechanism (49) on the insert (23) engages locking teeth (21) on the housing and serves to hold the insert in place. A conformable gel component may be present. The device provides the traction force as well as an environmental seal for cables such as electric heating cables or power supply cables.