System and Method for Producing Foamed Sealing for Wiring

A cable exit cover for sealing a portion of a cable includes a first cover member and a second cover member matable with the first cover member to define a housing having an inlet receiving the cable. The inlet has a sealing seat accommodating the cable. The sealing seat has a plurality of gripping devices uniformly distributing a dispensed sealing material along the sealing seat to seal a gap between the sealing seat and the cable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date under 35 U.S.C. § 119(a)-(d) of Italian Patent Application No. 102021000005159, filed on Mar. 5, 2021.

FIELD OF THE INVENTION

The present invention relates to a seal and, more particularly, to a seal for a wire.

BACKGROUND

Electrical cables are generally sealed against the environment to prevent damage to the cable conductors and to the connectors joining them, for example they are sealed against penetration of water and/or dust into the electrical wires. Gel materials such as silicone gels, polyurethane gels, polyurea gels or thermoplastic gels may be used to seal the electrical cables.

For example, document EP 0 575 520 B1 discloses a gel-filled enclosure for a cable butt splice or an elongate substrate such as a telecommunication cable splice, coaxial cable splice and the like. The cable splice enclosure comprises two symmetrical halves, which are fitted together to form an enclosure around a portion of two coaxial cables and to connect them together. The cable splice is contained within the central portion of the enclosure and surrounded by a suitable gel material, such as silicones, thermoplastic materials, polyurethanes, polyureas, and polyisobutylenes.

Standard techniques of dispensing the gel materials on the inner surface of predefined grooves on the two cable covers do not assure a uniform distribution of the dispensed materials. In fact, the dispensed material is typically injected into the predefined grooves of the two cable covers by using a robotic application that is configured to move on a plane, parallel to the plane where each of the two cable covers is laying. During injection, the dispensed material tends to flow towards the bottom of the groove because of gravity and tends to accumulate there, thus leaving the portion of the groove proximate to the splitting line of the cable cover with a reduced amount of dispensed material. In this way, when the cover is formed by combining the two mating halves, the portion of the cable close to the splitting line of the cover is not adequately protected and sealed against the environment, because the radial thickness of the dispensed material thereon is lower with respect to the radial thickness of the dispensed material at the bottom of the groove. It might even occur that gaps in the sealing material are formed in correspondence of the splitting line of the cable cover.

An alternative method for forming a protective layer on a cable consists in constantly rotating the cable during dispensation of the protective material. For instance, document US 2005/0074553 A1 describes a method for impregnating and curing an electric coil with a layer of polyurethane. The method includes a preliminary heating step, wherein an article having a coil is heated to a preliminary heating temperature at which the viscosity of a polyurethane varnish decreases and is above a drying temperature. The method also includes a varnish application step, wherein the polyurethane varnish is continuously applied to the coil while rotating the heated article at a constant speed. The method further includes a high-temperature rotary drying step in which the polyurethane varnish is dried while heating the polyurethane varnish at a drying temperature that is higher than the varnish temperature during the varnish application step. This method has the disadvantage that a complex apparatus, comprising a rotating device, is required for forming the protective layer on the electrical coils.

SUMMARY

A cable exit cover for sealing a portion of a cable includes a first cover member and a second cover member matable with the first cover member to define a housing having an inlet receiving the cable. The inlet has a sealing seat accommodating the cable. The sealing seat has a plurality of gripping devices uniformly distributing a dispensed sealing material along the sealing seat to seal a gap between the sealing seat and the cable.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following, the present invention is described with reference to particular embodiments as shown in the drawings. Nevertheless, the present invention is not limited to the particular embodiments described in the following detailed description and shown in the figures, but, instead, the embodiments described simply exemplify several aspects of the present invention, the scope of which is defined by the appended claims. Further modifications and variations of the present invention will be clear for the person skilled in the art. Therefore, the present description should be considered as including all the modifications and/or variations of the present invention, the scope of which is defined by the appended claims.

For simplicity, identical or corresponding components are indicated in the figures with the same reference numbers. For simplicity, the components according to the present invention are indicated with plain reference numbers, and the corresponding components according to prior art are indicated with primed reference numbers.

A cable exit cover100for sealing a portion of one of more cables200,201,202,203, which can be realized according to the present invention, is schematically illustrated inFIG. 1. The cable exit cover100ofFIG. 1accommodates four electrical cables200,201,202,203. However, any number of electrical cables may be accommodated in the cable exit cover100of the present invention, for instance one, two, three, five or more electrical cables.

The cable exit cover100comprises a first cover member120and a second cover member130, configured to mate with the first cover member120to define four inlets111into which a portion of four corresponding cables200,201,202,203, can be inserted. The first cover member120and the second cover member130may alternatively be referred to as mating elements or mating parts. Each inlet111, in the shown embodiment, has two sealing seats112for accommodating a portion of the corresponding cables200,201,202,203. A section of one of the two mating parts forming the sealing seat112is schematically illustrated in the enlarged view inFIG. 1. However, each inlet111according to the present invention may comprise any number of sealing seats112, for instance one, three, four or more sealing seats.

The gap between the sealing seat112and the corresponding cable200,201,202,203is filled with a dispensed sealing material300. As can be seen in detail in the enlarged view ofFIG. 1, the inner surface of the sealing seat112is provided with gripping devices110, which are configured so as to provide a uniform distribution of the dispensed sealing material300upon application. As will be described in the more detail below, in fact, the dispensed sealing material300naturally tends to flow towards the bottom of each of the two mating parts forming the sealing seat112, when it is applied, and to thin in the area of the sealing seat112proximate to the splitting line of the cable exit cover100, where the first cover member120meets the second cover member130. Without the gripping devices110, the distribution of the dispensed sealing material300around the cable200,201,202,203is not uniform and, in particular, the cable200,201,202,203is not protected in the region close to the splitting line of the cable exit cover100. The gripping devices110are configured so as to obstruct the flowing of the dispensed sealing material300along the inner walls of the sealing seat112, because they are configured so as to protrude from the inner surface of the sealing seat112and to increase the inner surface travelled by the flowing dispensed sealing material300. In an embodiment, the gripping devices110are uniformly distributed along the inner walls of each sealing seat112.

The first cover member120and the second cover member130may be formed in polyamide, polyamide PA-GF30 or any other material having high resistance to high temperatures, for instance temperatures between −40° C. and 130° C. For example, polyurethane and silicone may be used as dispensed sealing materials300.

As shown inFIG. 2, each of the two cover members120and130is provided with a recess, respectively a first recess122and a second recess133. When the two cover members120,130are combined together, they form a closed housing140for accommodating electrical components and the two recesses122and133are mated to form four inlets111, where corresponding cables can be inserted. In the present application, the word “housing” is used to indicate an inner portion of the cable exit cover100, wherein the corresponding cable200can be accommodated. The portion of the housing where the cables are inserted is referred to as “inlet”.

The part of each inlet111where the dispensed sealing material is applied forms a sealing seat112. InFIG. 2, only a single cover member120or130is represented, therefore only half of each sealing seat112is visible. A complete sealing seat112is in fact formed when the first recess122of the first cover member120and the second recess133of the second cover member130are combined. Each sealing seat112has a circular section for accommodating a corresponding cable200,201,202,203with a circular section. As will be detailed in the following, the inner surface of each sealing seat112is provided with gripping devices110, configured to obstruct the flow of the dispensed sealing material300because of gravity.

In this application, when reference is made to the “circular section of each sealing seat”, it has to be understood that each sealing seat112is configured as a ring, formed by the two mating recesses122,133of the first cover member120and of the second cover member130for accommodating a portion of a cable200and of a dispensed sealing material300. Therefore, the section of the inner surface of each sealing seat112is circular. The gripping devices110are formed on the curved, inner surface of each sealing seat112and they locally change the profile of the sealing seat112having a main circular section.

In the present application, the force of gravity defines a direction and that the top and bottom parts of the cable exit cover100, the first cover member120, and the second cover member130are defined in accordance with it; in particular, an object subjected to the gravity force will naturally flow from the top to the bottom part. Accordingly, the bottom of a recess122,133and/or of the sealing seat112is defined as the portion of the inlet111and/or the sealing seat112where dispensed material naturally accumulates after flowing along the inner walls of the sealing seat112because of gravity.

As shown inFIG. 2, each sealing seat112has a substantially annular shape, having a circular section and having a width W smaller than the length of the portion of the cable that is inserted into the cable exit cover100. InFIG. 2, two sealing seats112for each inlet111are illustrated. It is clear that, even if two sealing seats112for each inlet111are illustrated, any number of sealing seats112may be provided for each inlet111of the cable exit cover110, according to the specific needs, for instance one, three, four or more sealing seats may be provided. If two or more sealing seats112are provided for accommodating the same cable200, they are configured so as to be parallel to each other and to be placed one after the other along the insertion direction of each cable200, so that a first portion of a cable200is accommodated on a first sealing seat112and a second portion of that cable200is accommodated on a second sealing seat112.

Each of the first cover member120and the second cover member130is further provided with a groove121and131, which extends along the entire perimeter of its inner surface. The inner surface of each cover member120,130is the surface oriented towards the cable.

As shown inFIG. 3, the recesses122,133forming the two sealing seats112and the inner groove121,131of the first and second cover member120,130are filled with the dispensed sealing material300; the sealing material300is applied in each cover member120,130when it is disposed on a support surface. In this way, the entire inner surface of the one or more sealing seats112is sealed with the dispensed material300to provide a continuous sealing for the cables200.

The cable exit cover100protects the inserted cables200,201,202,203against the environment, not only in proximity of the inlet portion where the cable is inserted, but also on the lateral portions of the cable exit cover100. After the dispensed sealing material300has been dispensed on the sealing parts, the electric cables200,201,202,203are inserted and accommodated into the corresponding inlets111. The cable exit cover100may be used, for instance, for covering a portion of electric wires used in high voltage applications. As is clear fromFIG. 3, the dimensions of the cables200,201,202,203do not need to be the same, but it is possible to use cables200,201,202,203of different diameters within a certain tolerance range. For instance, cables200,201,202,203having sections of 6 mm2, 25 mm2, 50 mm2or 95 mm2, can be employed.

The gripping devices110according to the present invention are represented in detail inFIG. 4. Each sealing seat112has a circular section with a curvature radius R. The gripping devices110comprise protruding elements formed on the inner surface115of each sealing seat112. The inner surface115of each sealing seat is the surface comprising all the points placed at a distance R from the center of the sealing seat112; in other words, the inner surface115is the smooth surface of the sealing seat112not comprising the gripping devices110. The gripping devices110prevent the accumulation of the dispensed sealing material300towards the bottom of each recess122,133of the sealing seats112, during application of the dispensed sealing material300, because the edges114of the gripping devices110retain the dispensed sealing material300in the upper part of the recess122,133, after dispensing of the dispensed material300.

The gripping devices110could be described as “steps” formed on the inner surface115of the sealing seat112and extending along the whole width of the sealing seat112. Each sealing seat112has a predefined width for accommodating a portion of the corresponding cable200and the sealing material300. The steps of the gripping devices110have an edge114which is placed at a height H with respect to the curved inner surface115of the sealing seat112, as shown inFIG. 4. In an embodiment, the height H is constant or uniform along the whole width W. The two surfaces of each step converge at the edge114and form an acute angle, therefore the steps do not have an orthogonal section in the shown embodiment. The gripping devices110are formed on both the first recess122of the first cover member120and on the second recess133of the second cover member130, so that the sealing seat112comprises gripping devices110symmetrically distributed around the cable200,201,202,203. However, the gripping devices110are not uniformly distributed on the sealing seat112and they are not present in the bottom part113of each recess122,133.

The gripping devices110may be configured so that each of the two surfaces converging at the edge114has a curvature radius r, shown inFIG. 4, which is smaller than the curvature radius R of the sealing seat112. Therefore, the curvature of the inner surface115of the sealing seat112is locally reduced.

The gripping devices110increase the surface of the internal walls of each sealing seat112and increase the number of edges114on those internal walls. In this way, the flowing of the dispensed sealing material300is driven by the edged internal walls and the accumulation of the dispensed material300at the bottom of the recesses122,133forming the sealing seat112is avoided. The dispensed sealing material300, after injection, flows along the inner walls of each of the two mating parts120,130forming the sealing seat112and flows along a longer route or trajectory with respect to the configuration of the sealing seat112without the gripping devices110. In this way, the flowing of the dispensed sealing material300towards the bottom of each of the two mating parts120,130of the sealing seat112is obstructed because of the increased friction that it experiences and the thinning of the dispensed sealing material300in critical areas proximate to the splitting line of the cable exit cover100is avoided. Moreover, the presence of the gripping devices110avoids formation of critical areas, that is the formation of areas close to the splitting portion between the two cover members120,130where the dispensed sealing material300has thinned and hence gaps are formed in the seal.

The advantage of the present invention with respect to prior art will be apparent by comparingFIG. 5andFIG. 6.

FIG. 5represents a dispensed sealing material300provided around a cable200,201,202,203, according to the present invention. Because the gripping devices110inhibit the flowing of the dispensed material300towards the bottom of each recess122,133of the sealing seat112, when the two recesses122,133are combined to form the sealing seat112, the dispensed sealing material300is uniformly distributed along the inner walls of the sealing seat112and around the cable200,201,202,203. In this way, the radial reaction and the radial pressure of the gasket on the cable200,201,202,203is symmetrical and sealing is assured along the whole perimeter of the circular section of the cable200,201,202,203. In particular, the radial thickness of the dispensed sealing material300on the portions of the sealing seat112proximate to the splitting line of the cable exit cover100is equal to the radial thickness of the dispensed sealing material300at the top and at the bottom of the sealing seat112.

The dispensed sealing material300is applied on each sealing seat112and is not distributed along the entire length of the cable200, which is inserted into the cable exit cover100. In this way, the amount of dispensed sealing material300used to provide the sealing is reduced, thus also reducing the production costs. However, a secure and reliable sealing against water and dust is assured.

To the contrary, according to prior art, as shown inFIG. 6, the first cover member120′ and the second cover member130′ are not provided with gripping devices110and the dispensed sealing material300tends to thin down at the corners of the recesses122′,133′ and to thicken at the bottom of the recesses122′,133′ of the sealing seat112′. Therefore, in prior art configurations, the radial thickness of the dispensed sealing material300in the area301′ proximate to the splitting line of the cable exit cover100is smaller than the radial thickness of the dispensed sealing material300in the bottom portion and in the top portion of the sealing seat112′ (which correspond, respectively, to the bottom portions of the first recess122′ and of the second recess133′). In this way, the dispensed sealing material300is not well distributed and the radial reaction of the gasket is not symmetrical around the cable200,201,202,203.

The presence of the gripping devices100of the present invention is crucial for assuring a uniform radial distribution of the dispensed sealing material300around the cable200,201,202,203. In fact, the dispensed sealing material300is first applied on both covers120and130and later the two covers120and130are mated together, to ensure the sealing of the system. If each cover member120,130does not have a uniform distribution of the dispensing sealing material300, when the two covers are mated with each other, the regions301around the cable do not contain a sufficient amount of dispensing sealing material300, therefore, gaps in the sealing are formed.

FIG. 7schematically shows that the cable exit cover100, according to the present invention, may be used for cables200,201,202,203of different dimensions and diameters, while still providing an efficient and reliable sealing. The first cover member120, represented inFIG. 7, is characterized by recesses122having different curvature radii. Each sealing seat112is provided with gripping devices110for assuring a uniform distribution of the dispensed sealing material300. The dimensions, for example height H, width W and local curvature radius r, of the gripping devices100are adapted to the dimensions of the corresponding cable200,201,202,203and accordingly of the corresponding sealing seat112. In this way, the portion301in correspondence to the splitting line on the cable exit cover100has a thickness of the dispensed sealing material300, which is equal to the thickness of the dispensed sealing material300at the bottom of each recess122, for all the cables dimensions.

The dispensation of the sealing material300is carried out always in the same way, regardless of the dimensions of the cables accommodated into the cable exit cover100. In an embodiment, the dispensed seal300has a width of 6 mm and a height of 6.5 mm. In other embodiments, the dimensions of the dispensed seal300may vary according to the needs of the product.

The present invention also refers to a method for assembling a cable exit cover100for sealing a portion of one or more cables200against the entrance of water and/or dust.

The method comprises providing a first cover member120having a first recess122and a first groove121and a symmetrical second cover member130having a second recess133and a second groove131, like the ones represented inFIG. 2. The recesses122,133of the first cover member120and of the second cover member130may be provided with gripping devices110, in order to assure a uniform distribution of the dispensed sealing material300on the sealing seat112formed by the two mating recesses.

The dispensed sealing material300is dispensed on both recesses122and133and grooves121and131, respectively, of the first cover member120and on the second cover member130. In an embodiment, these operations are carried out simultaneously. In an embodiment, these operations are carried out by using robotic application device310, for instance a nozzle, for dispensing the dispensed sealing material300, as schematically illustrated inFIG. 8. The robotic application device310may operate at a constant speed along the grooves121,131. The speed may be reduced or increased according to the application.

During application of the dispensed material, the first cover member120and the second cover member130are placed on a support surface and they are oriented so that their inner surface comprising the groove121,131is oriented towards the robotic application device310. In this way, not only the part of the cable exit cover100where the cables200are inserted is sealed and protected, but also the other lateral parts of the cable exit cover100are protected and sealed against the external environment.

After filling the grooves121and131and the recesses122and133, the cables200,201,202,203are inserted into the corresponding inlets111and sealing seats112of the first cover member120. The first cover member120and the second member130are symmetrical and the cables200,201,202,203may be inserted also in the corresponding seats of the second cover member130.

The second cover member130is then combined with the first cover member120in order to accommodate and cover or encapsulate a portion of the cable200,201,202,203. For example, the first cover member120and the second cover member130may be fixed to each other by using screws. In this way, a cable exit cover100providing a reliable sealing for the cables200,201,202,203is obtained.

In another embodiment, the cable exit cover100is used for a cable exit configuration set at 90°. This configuration has the advantage that a stable and reliable sealing is provided for cable exit configurations wherein the cables200are placed and connected at 90°. Moreover, this configuration allows to automatize, to simplify and to speed up the assembly process of the cable exit cover100. The cable exit configuration set at 90° indicates a configuration wherein one end of one or more cables200is crimped to a corresponding terminal, is inserted inside the housing140of the cable exit cover100along a first direction perpendicular to the surface of the first cover120, before assembly of the cover, and is then bent at 90° so that the cable is placed inside a first recess of the first cover120. It is clear that a cable exit configuration set at 90°, wherein the crimped end of the cable200is initially placed inside a second recess of the second cover130is also possible.

The cable exit cover100is provided with a simple and reliable sealing system and the assembly is realized with a reduced number of components, thus guaranteeing the possibility of an easy automated process.

While the invention has been described with respect to physical embodiments constructed in accordance therewith, it will be apparent to those skilled in the art that various modifications, variations and improvements of the present invention may be made in light of the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention. For instance, it is clear that, even if the method of dispensing the dispensed sealing material300in a uniform way along the inner walls of the sealing seat112has been described in reference to the cable exit cover100, the same method could be used for any other device where a viscous material needs to be dispensed. For instance, the gripping devices110according to the present invention may be provided on the inner surface of the moldings for forming multi-layer cables provided with insulating and protecting layers.

In addition, those areas in which it is believed that those of ordinary skill in the art are familiar, have not been described herein in order not to unnecessarily obscure the invention described. Accordingly, it has to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims.