Field of application

The present invention relates to an electric insulator comprising a component having a cross-section the same as a cross-section of a rail and intended to be arranged between two sections of a rail, in order to interrupt an electric current between them.

In particular, the present invention relates to an electric insulator of the aforementioned type which allows transit of a train along the rail sections to be detected or signalled by means of interruption of the current,

The invention also relates to a method for applying an electric insulator for rails sections.

Prior Art

An electric insulator for rails sections is known.

The electric insulator has a component which has a cross-section the same as a cross-section of a rail and is intended to be arranged between two sections of a rail, in order to interrupt an electric current between them. The function of the insulator is to allow, by means of current interruption, detection and/ or signalling in a train control station or in the train driver's cab that the train is engaged with the rail sections.

More particularly, two different models of electric insulators are known.

A first model, which is diagrammatically shown in Figure A, is available as a kit comprising:

- a component 100 made of plastic and intended to be arranged between the rail sections (only one section 1000 is shown in Figure A);

- two side-pieces 101 which can be applied to opposite sides of the rail sections and are also made of plastic; - two metal bars 102 which can be inserted inside the side-pieces 101;

- a plurality of cylindrical bushes 103 which can be inserted inside through-holes 105 in the rail, in the side-piece 101 and in the metal bars 102, and

- fixing means, for example pins 104 which can be inserted inside the holes 105 on one side of the rail section and tightened to bolts 106 on the opposite side.

The kit includes an adhesive product 108 for fixing the component 100 to the end 107 of the rail sections and the side-pieces 101 to the sides and for fixing the bushes 103, which are also made of plastic, inside the holes 105.

The installation of this first insulator model is fairly complicated and laborious.

First of all it is required to clean all the surfaces of the rail sections onto which the adhesive 108 is applied; this operation is particularly long since a previous electric insulator must be removed, along with the adhesive used. Generally sand-blasting methods are used to clean the rail sections and these involve the installation and movement of machinery along the rails.

Once the surfaces are cleaned, the adhesive 108 is applied, not without further difficulty; it is necessary to respect rigorously the times required for preparation of the adhesive in situ and for pre-diying thereof on the surfaces concerned, i.e. before joining the plastic components to the rail.

Finally, the step of installation of the various components involves further difficulties, especially with regard to positioning the plastic components 100, 101 and centring the holes 105 present on the metal bars 102 and on the side-pieces 101 with the holes 105 present on the rail sections, something which is complicated by the presence of adhesive on the surfaces.

A second electric insulator model, which is diagrammatically shown in Figure B, comprises again a component 201 to be installed as an insulator between the rail sections 1000, 1001, but is characterized in that the metal bars 202 are incorporated within a plastic lining 210; the metal bars 202 and associated plastic linings 210 are indicated overall by 215 in Figure B.

The installation is partially facilitated because, compared to the insulator shown in Figure A, the side-pieces and the metal bars do not have to be applied separately. However, these insulators also have significant drawbacks, including the difficulty of applying the component 201 correctly on the end of the rail sections, the need to clean the surfaces of the rail sections for proper adhesion of the component 201 on the ends and for proper adhesion of the lined bars 215 on the rails, and the difficulty of fixing the lined bars 215. In this connection, this second insulator model is provided with plates 203 having holes, to be arranged between the lined bars 215 and fixing means 204, such as pins and bolts. The bolts are passed inside through-holes in the rail 1000 and inside corresponding holes in the lined bars 215 and in the plates 203 and screwed to the bolts on the opposite side of the rail. However, the alignment of the holes in the rails 1000 with the holes in the plates 203 and in the lined bars 21, on both sides of the rail sections 1000, 1001, is not simple and immediate and results substantially in the same drawbacks already mentioned for the first electric insulator model.

The technical problem at the basis of the invention is that of devising an electric insulator for rail sections which can be applied in a particularly simple and immediate manner, which does not require thorough cleaning of the rail surfaces while ensuring perfect adhesion thereto, and which ensures precise positioning on the end and on the side- pieces of the rails sections and correspondingly efficient electric insulation, thus overcoming all the drawbacks which affect the insulators according to the prior art.

Short description

The idea underlying the present invention is that of providing an electric insulator comprising an end plastic profile, having a cross-section the same as the front end cross-section of a rail, and one or more side- pieces joined together with the end profile and intended to cover the sides of the rail. The application of the end profile to the end of the rail section allows simultaneously one or more side-pieces to be applied to the sides of the rail section or sections, ensuring correct positioning of the side-pieces on the sides of the rails and therefore avoiding the operator having to try to centre the side-pieces on the holes in the rails or achieve correct positioning of the end profile on the end of the rails. In this latter connection, in fact, the application of the side-piece(s) on the side of the rail(s) ensures correct positioning of the end profile on the end of the rail. In particular, the profile and the side-pieces are made of a semi-rigid and elastic plastic material which allows the side- piece(s) to be splayed out from the end profile during application to the rail section(s) and which recalls the side-piece(s) and the end profile so that they adhere perfectly onto the rail(s) as soon as the insulator has been fitted onto the end of the rail(s). Therefore, during application the insulator is initially deformed (splayed) so as to be aligned on the rail end and may then be slid so as to engage with the rail, ensuring perfect alignment between the holes in the rail and the holes in the profile.

The abovementioned technical problem is solved by an electric insulator according to Claim 1. The technical problem is also solved by particularly advantageous embodiments of the electric insulator according to the dependent claims.

In particular, the electric insulator for two rail sections comprises a plastic end profile with a cross-section the same as a cross-section of the rails, intended to be applied onto the end of the rail sections to be insulated, and four plastic side-pieces, intended to be applied onto the opposite sides of the rail sections to be insulated, and is characterized in that at least one of the side-pieces is joined together with the plastic end profile. During application, the side-piece engages on the side of the rail and the end profile joined to it ensures correct positioning thereof along the rail.

In one embodiment of the invention, the two side-pieces intended to be applied onto the opposite sides of a rail section are joined together with the plastic profile. In this case, during application, the opposite side- pieces engage on the sides of a rail section simultaneously and the end profile joined to them ensures correct positioning thereof along the rail, simplifying and speeding up installation,

In another embodiment, the side-pieces intended to be applied onto a same side of the two rail sections are joined together with the plastic profile. In this embodiment, during application, the side-pieces engage on the same side of two rail sections simultaneously and the end profile joined to them ensures correct positioning thereof along the two sections, simplifying and speeding up installation.

In a further embodiment, the side-pieces not joined together with the plastic profile are joined to each other. Advantageously, according to this embodiment, opposite side-pieces also engage on the sides of a rail section simultaneously, the plastic material from which they are made allowing the side-pieces to adhere immediately against the rail; correct positioning along it is simply obtained by sliding the side-pieces joined together as far as the end of the rail.

In this connection, in all the embodiments, the side-pieces comprise one or more holes intended to be aligned with through-holes in the rails. The position of said holes on the rails is predefined (standard).

In particular, the side-pieces comprise at least one hole and a corresponding collar which is incorporated in the side-piece and extends from one surface intended to come into contact with the side of the rail section, the collar being able to be inserted into a through-hole passing from one side to the other of the rail section, and the collars of the side-pieces intended to be applied to the opposite sides of the rails sections can be inserted inside each other, According to this first aspect of the invention, the application of the insulator is further simplified because the collars engage with each other when the insulator is in the correct position on the rail, therefore avoiding the need for the operator to achieve correct centring, separately on the four sides of the rail sections.

A bar, which is preferably made of iron and is intended to be applied on an outer surface of the side-pieces, on the same side of the rail sections, is provided with holes opposite the collars and can be arranged against the rail sections by means of fixing means applied onto opposite sides of each rail section, as will become dear from the figures and from the description below, The fixing means comprise for example a threaded nut and a screw, and the nut and the screw are configured to prevent unscrewing after tightening.

According to one aspect of the invention, a side-piece comprises an extension which can be inserted into an undercut formed in another side-piece intended to be applied on the same side of the two rail sections. The extensions and the undercuts in the side-pieces ensure perfect electrical insulation also at the joining points of the side-pieces without the separate application of any insulating adhesive or component.

The plastic material of the end profile and the side-pieces is preferably rigid and elastic.

The surfaces of the side-pieces intended to come into contact with the side of the rail section comprise channels or recesses intended to increase the adhesion of the side-pieces to the rail section. In particular, the channels or recesses form, between the rail section and the surfaces of the insulant, pockets of air intended to be eliminated during fixing and to create a suction effect holding the side-piece against the rail section, therefore increasing the adhesion and insulation.

Further characteristic features and advantages of the electric insulator according to the present invention are described below by way of a non- limiting example with reference to the accompanying drawings.

Brief description of the drawings

Figure A: shows an electric insulator for rail sections according to the prior art.

Figure B: shows another electric insulator for rail sections according to the prior art.

Figure 1: shows a perspective view of an electric insulator according to the present invention, during an operating step where it is applied to two rail sections.

Figure 2: shows a perspective view of some components of the electric insulator according to Figure 1 applied, during assembly, to two rail sections.

Figure 3: shows a front cross-sectional view of the electric insulator and the rail according to Figure 1, in exploded form. Figure 4: shows a view, from above, of the electric insulator and the rail according to Figure 1, in exploded form.

Figure 5: shows a front view of the electric insulator and the rail according to Figure 1, with assembled parts.

Figure 6: shows a perspective view of the components of the electric insulator according to Figure 2.

Figure 7 shows a cross-section through the insulator according to Figure 5.

Figure 8 shows a transparent view of Figure 1 in which the components of the electric insulator applied on both the sides of the rail sections are visible.

Figures 8a and 8b: show larger-scale details of Figure 8.

Figures 9a and 9b: show perspective views of a first component (2) of the electric insulator, according to the present invention,

Figure 10: shows a perspective view of a second component (6) of the electric insulator, according to an embodiment of the present invention.

Figure 11: shows a perspective view of a third component (3) of the electric insulator, according to an embodiment of the present invention.

Figures 12a and 12b: show a perspective view of a fourth component (2) of the electric insulator, according to an embodiment of the present invention.

Figures 13a and 13b: show two perspective views, rotated through 180°, of the components of Figures 8a- 12b, assembled.

Figures 14a- 14c: show details of the assembled components according to Figures 13a and 13b.

Detaied description

With reference to Figure 1, this shows in diagrammatic form an electric insulator 1 which has a cross-section the same as the cross-section of a rail and is intended to be arranged between two sections 30, 31 of a rail, in order to interrupt an electric current between the two sections. By interrupting the current, the electric insulator 1 allows detection and/ or signalling in a train control station or in the train driver's cab that the train is engaged with the rail sections. Still with reference to Figure 1, two side-pieces 2, 3 of the electric insulator 1 are visible, these being arranged between the side 30b, 31b of the two rail sections 30, 31 and a metal bar 4.

Other two side-pieces and a respective bar are applied on the opposite side of the rails sections 30, 31; the four side-pieces and the two bars are held tightly together by means of fixing means 8, for example by means of pins which pass inside through-holes in the side-pieces, the bars and the rail sections, and are screwed onto bolts. Said pins and bolts, after being tightened with a predefined force, may be slackened only by means of a suitable tool or piece of equipment. In other words, there is no vibration or stress acting on the joint of the rail section formed by means of the electric insulator according to the present invention which is able to accidentally slacken or unscrew the fixing means. Advantageously such an electric insulator forms together with the metal bars and with the fixing means a joint between the rails sections which is extremely secure and reliable.

Figure 2 shows the two rail sections and the side-pieces without the ^' metal bar 4. The through-holes 32 in the side-pieces and in the rail sections may be seen; it is also possible to see a peripheral portion of the end profile 2a arranged between the two rail sections.

The electric insulator 1 is shown in exploded form in Figure 3 (front cross-section) and Figure 4 (view from top). In particular, Figure 3 shows the side-pieces 5 and 6 and the opposite side-pieces 2 and 3. The side-piece 2 is joined together with the end profile 2a. The four side-pieces are shown in a top plan view in Figure 4; one of them, the side-piece 2 comprises the end profile 2a intended to be arranged between the ends of the two sections 30 and 31 of the rail. Each through-hole 42-46 in the side-pieces is associated with a collar 52-56 and the collars of the side-pieces intended to be applied on the opposite sides of the rail can be inserted inside each other, for example by means of snap-engagement. Obviously, in the figures the side-pieces are shown with two holes per side-piece, but it is possible for one hole or more holes to be used, depending on the requirements or the structure of the rail to be insulated.

Application of the components shown in Figure 4 therefore envisages that the side-piece 2 with the end profile 2a is applied first of all, with predefined positioning on the rail section 31, i.e. with the collars 42 which enter immediately inside the holes of the rail 31 owing to the fact that the interaxial distance between the holes on the profiled part corresponds to the interaxial distance between the holes on the rail and owing to the fact that the distance between the end profile 2a and the hole adjacent to it corresponds to the distance between the end of the rail and the hole adjacent to it. Then the other side-pieces may be inserted, for example firstly the side-piece 6, together with the collars 56 which snap-engage inside the collars 52 of the side-piece 2, and then the side-pieces 3 and 5 with respective snap-engaging insertion of the collars, Peripheral portions 22, 33 of the side-pieces may be inserted inside one another or straddling the end profile, so as to ensure electrical insulation along the joining lines.

Advantageously, it is not required that the surface of the rail sections should be treated, for example sandblasted or cleaned, before application of the electric insulator, In fact, optimum adhesion of the insulator on the rail is ensured by the elastic material, by the engagement of the collars and by the peripheral portions which are further tightened together following application of the metal bars, as shown in the front view of Figure 5. The perfect adhesion and the elastic material have the further advantage that they reduce the vibrations in the region of the joint of the rail sections, not only improving the comfort for the persons travelling, but also preventing the vibrations from slackening the grip of the insulator on the rail sections.

Figure 6 shows the side-pieces 2, 3, 5, 6 and the end profile 2a separately from the rail and the bars. It is evident that various and advantageous embodiments may be provided, while remaining within the scope of protection of the invention. In particular, the side pieces 2 and 6 may be joined together with the end profile 2a, or the side pieces 2 and 3 or the side pieces 5 and 6 or the side pieces 3, 5, 6 or the side pieces 6, 2, S may be joined together therewith. The elasticity of the plastic material allows the joined bars to be splayed or spaced from each other and more than one side-piece to be applied very rapidly to one or both the rail sections.

A number of knurls or recesses 55 are visible in Figure 6, Said recesses have the function of increasing the adhesion of the insulator on the rail sections and allow a suction effect holding the insulator against the rail to be obtained, following tightening of the fixing means 8. In fact, the recesses form air pockets or channels which are emptied by the compression of the elastic surface of the insulator against the rail, creating a vacuum in the pockets. The form of the pockets or the channels is not limited to that shown in the figures; for example, in one embodiment, the pockets are formed as circular recesses around the holes 42-46, preferably on the surface facing the collars.

Figure 7 shows a cross-section of the profile applied to the rail, where it is possible to see the means for snap-engaging together the collars 52- 56. A larger-diameter collar 52 intended to receive a smaller-diameter collar 56 has a tooth 52P which can be inserted inside a recess 56R of the small-diameter collar. Obviously, it is quite possible for the position of the tooth or the recess on the collars to be reversed or for other snap- engaging or quick-coupling means to be used.

Figures 8a and 8b show a detail of the peripheral portions 22, 23 in the region of the end profile 2a. A portion 23 of the side-piece 3 applied to the rail 31 extends towards the rail 30 and is positioned on top of a peripheral portion 22 of the side-piece 2, increasing the electrical insulation at the joining line of the side-pieces and also the joining line of the end profile 2a with the side-pieces.

Figures 9a- 14a show the side-pieces in exploded form (Fig. 9a-9b, 10, 11, 12a- 12b), the side-pieces with parts assembled (13a, 13b) and a number of details (14a- 14c) .

The method for applying the electrical insulator is briefly described hereinbelow.

The plastic end profile of the insulator is applied to an end of the rail sections and at least one plastic side-piece is applied to the side of rail section. The method is characterized in that the side-piece is joined together with the plastic profile and application of the side-piece on the side of the rail section and application of the end profile on the end of the rail section is simultaneous and results in predefined positioning of the side-piece and the profile on the rail section.

According to various embodiments, the simultaneous application may involve two side-pieces joined together with the end profile on one side or on opposite sides.

According to an embodiment, at least one side-piece is separate from the plastic profile and is applied on the opposite side to or on the same side of the rail section with respect to the side where the joined side- piece is applied.

The application step comprises the insertion of at least one collar, situated around a hole in the side-piece, inside at least one corresponding through-hole in the rail section.

The collar of one side-piece, which is applied on one side of the rail section, is inserted into the collar of a side-piece which is applied onto an opposite side of the rail section. Preferably, insertion of the collars is performed by means of snap-engagement.

A peripheral portion of one side-piece is inserted in the peripheral portion of another side-piece, so as to ensure perfect electrical insulation also along the joining lines between the side-pieces or between the end profile and the side-pieces.

Advantageously, the electric insulator and the application method according to the present invention are able to achieve significant advantages.

Firstly the whole arrangement simplifies assembly since the side-pieces are automatically centred on the holes of the rail sections and the end profile is positioned precisely on the end of the rails.

Assembly is further simplified because plastic bushes are not used as separate components in order to insulate the holes in the rails, the bushes being instead incorporated in the side-pieces as collars which automatically snap-engage inside each other.

Application of the electric insulator is significantly speeded up because it does not require thorough cleaning of the rail, since the plastic material, the configuration of the insulator and the recesses on the surfaces of the side-pieces increase considerably the adhesion and the insulation, also without the use of adhesives.