Compensation device for compensating the length of tensioned cables

Abstract

A compensation device (1) for compensating the length of tensioned cables, which comprises at least one variable-radius pulley (2) which is associated with a supporting structure (4), so that it can rotate about its axis of rotation (3), and is provided, at a radially external portion thereof, with coupling means (5) for coupling with a tensioned cable (6). The supporting structure (4) can be associated with an anchoring element and a contrast element is provided between said supporting structure and the variable-radius pulley (2) that is adapted to deform elastically as a result of the rotation of the variable-radius pulley (2) about the supporting structure (4) in a loading direction of rotation (8) which matches the pull of the tensioned cable (6) so as to convert the elastic reaction to the deformation of the contrast element into a substantially constant pull applied to the tensioned cable (6) independently of its lengthwise extent and within a preset interval of length variation. The peculiarity of the invention consists in that it comprises an emergency brake (9) adapted to stop sudden rotations of the variable-radius pulley (2) with respect to the supporting structure (4) in the opposite direction to that of the loading direction of rotation (8), for example as a consequence of the breakage of the tensioned cable (6).

Description

[0001] COMPENSATION DEVICE FOR COMPENSATING THE LENGTH OF TENSIONED CABLES

[0002] The present invention relates to a compensation device for compensating the length of tensioned cables.

[0003] As is known, aerial electricity lines, for the transmission and distribution of energy or for powering railway locomotives, are installed with a well-defined pull value that takes into consideration the resistance to breakage by traction of the cables, the strength of the supporting structures, and the requirements in terms of maximum sag at the center of the curve.

[0004] In order to maintain the pull value, while compensating the variations of length, as a result of variations in temperature of the electricity line, conventional devices include a compensation device for compensating variations in length of tensioned cables, with substantially constant pull, which is the subject matter of EP2066523.

[0005] Such device comprises a contrast element which is adapted to be interposed between one end of the tensioned cable and an anchoring element and which is adapted to develop an elastic reaction which is variable as a function of the variation in length of the cable.

[0006] The device comprises means for connecting the contrast element to the cable, and such connecting means are adapted to convert the elastic reaction of the contrast element into a substantially constant pull applied to the cable, independently of its lengthwise extent, within a preset interval of length variation.

[0007] The contrast element is constituted by at least one coil spring and the connecting means are preferably constituted by at least one variable-radius pulley connected to the coil spring and provided with at least one trough for winding the cable to be tensioned or for a wire-like element connected to the cable to be tensioned.

[0008] Thanks to this device, it is possible therefore to compensate for variations in the length of tensioned cables, while maintaining a substantially constant pull on the cable.

[0009] This conventional compensation device is not devoid of drawbacks, which include the fact that, in the event of accidental breakage of the tensioned cable, the return of the coil spring can be such as to violently rewind the portion of the cable that is fixed to the pulley, making it collide disastrously with anything, object or person, that is present in the vicinity of the device.

[0010] This can undoubtedly cause damage to property and injure, possibly seriously, any operators at work, for example, on maintenance nearby or at the pole to which the device is fixed.

[0011] The aim of the present invention consists in providing a compensation device that maintains the advantages of the conventional device, but which at the same time overcomes the drawback complained of above.

[0012] Within this aim, an object of the present invention consists in providing a compensation device that is capable of ensuring the safety of property and persons from possible “whiplash” of tensioned cables as a consequence of their breakage.

[0013] Another object of the present invention is to provide a compensation device that is capable of intervening promptly to ensure the safety of property or persons.

[0014] Another object of the present invention consists in providing a safety device that is capable of offering the widest guarantees of reliability, efficiency, operation and rapid return to service.

[0015] This aim and these and other objects which will become better evident hereinafter are achieved by a compensation device for compensating the length of tensioned cables, which comprises at least one variable-radius pulley which is associated, so that it can rotate about its axis of rotation, with a supporting structure and is provided, at a radially external portion thereof, with coupling means for coupling with a tensioned cable, said supporting structure being associable with an anchoring element and between said supporting structure and said variable-radius pulley there being a contrast element adapted to deform elastically as a result of the rotation of said variable-radius pulley about said supporting structure in a loading direction of rotation which matches the pull of said tensioned cable so as to convert the elastic reaction to the deformation of said contrast element into a pull applied to said tensioned cable; characterized in that it comprises an emergency brake adapted to stop sudden rotations of said variable-radius pulley with respect to said supporting structure in the opposite direction to that of said loading direction of rotation.

[0016] Further characteristics and advantages of the invention will become more apparent from the detailed description of a preferred, but not exclusive, embodiment of a compensation device for compensating the length of tensioned cables, illustrated by way of non-limiting example with the aid of the accompanying drawings wherein:

[0017] Figure 1 is a perspective view of a compensation device according to the invention;

[0018] Figure 2 is a side view of the compensation device shown in Figure 1;

[0019] Figure 3 is a side view of the compensation device shown in the preceding figures, highlighting the emergency brake during the normal operation of the compensation device;

[0020] Figure 4 is a side view of the compensation device shown in the preceding figures, highlighting the emergency brake during emergency locking of the compensation device.

[0021] With reference to the figures, the compensation device for compensating the length of tensioned cables, generally designated by the reference numeral 1 , comprises at least one variable-radius pulley 2 which is associated, so that it can rotate about its axis of rotation 3, with a supporting structure 4 and is provided, at a radially external portion thereof, with coupling means 5 for coupling with a tensioned cable 6.

[0022] Advantageously, the supporting structure 4 can be associated with an anchoring element and between said supporting structure and the variableradius pulley 2 there is a contrast element, contained in a cover 7, which is adapted to deform elastically as a result of the rotation of the variable-radius pulley 2 about the supporting structure 4 in a loading direction of rotation 8 which matches the pull of the tensioned cable 6 so as to convert the elastic reaction to the deformation of the contrast element into a substantially constant pull applied to the tensioned cable 6 independently of its lengthwise extent and within a preset interval of length variation.

[0023] In more detail, the contrast element comprises at least one coil spring (in the illustrated embodiment two coil springs are provided) which is connected, with one of its ends, to the variable-radius pulley 2 in such a manner as to contrast its rotation in the direction opposite to the loading direction of rotation 8 and, with its other end, to the supporting structure 4.

[0024] The expression “substantially constant” is used to indicate that the tension maintained on the tensioned cable 6 is always kept at the constant value that is adapted to prevent the admissible maximum sag from being exceeded, even if huge variations, such as temperature, occur in operating conditions.

[0025] According to the invention, an emergency brake 9 is provided which is adapted to stop sudden rotations of the variable-radius pulley 2 with respect to the supporting structure 4 in the opposite direction to that of the loading direction of rotation 8, for example as a consequence of the breakage of the tensioned cable 6.

[0026] More specifically, in the illustrated embodiment, the emergency brake 9 comprises a plurality of pawl-like jaws 10, for example four in number, which are arranged substantially circumferentially, with respect to each other, about the rotation axis 3 and are each hinged about first pivots 11 which are integral in rotation with the variable-radius pulley 2.

[0027] As shown respectively in Figures 3 and 4, these pawl-like jaws 10 can move on a plane that is substantially perpendicular to the axis of rotation 3 with respect to the variable-radius pulley 2 between a gathered position, in which the jaws are mutually aligned along the circumferential direction by means of the return action of elastic means 12, and a locked position, in which the jaws have an orientation that substantially exits radially with respect to the circumferential direction for their engagement with second pivots 13 which are integral with the supporting structure 4 as a result of an angular acceleration of the variable-radius pulley 2 which is opposite to the loading direction of rotation 8 and is such as to impart to the pawl-like jaws 10 an inertia that is greater than the elastic return of the elastic means 12.

[0028] In the illustrated embodiment, the pawl-like jaws 10 have, on their radially external surface, a recess 14 adapted to engage with one of the second pivots 13 in the locked position and, at the same time, the pawl-like jaws 10 have a radially external surface which is profiled and blended to disengage from the second pivots 13 during the rotation of the variableradius pulley 2 along the loading direction of rotation 8.

[0029] Mechanically, each pawl-like jaw 10 defines a first-class lever in which its fulcrum is defined by its pivoting with the respective first pivot 11, its resistance force is defined by the action of the elastic means 12, and its effort force is defined by the force of inertia due to the acceleration of the variable-radius pulley 2.

[0030] In the illustrated embodiment, the elastic means 12 comprise, for each pawl-like jaw 10, a helical torsion spring, i.e. a spring in which the stressed cross-section is twisted when subjected to a compression stress, interposed between a first portion 16 of the pawl-like jaw 10, defining the resistance arm of the first-class lever, and a resting surface which is radially internal with respect to the first pivots 11 and is integral in rotation with the variable-radius pulley 2.

[0031] Moreover, again in the illustrated embodiment, the center of gravity of each pawl-like jaw 10 is defined within a second portion 15 thereof, which defines the effort arm of the first-class lever. Conveniently, the distal portion of each second portion 15 ends with an abutment surface 17 designed to rest against the distal portion of the first portion 16 of the consecutive pawl-like jaw 10 in a direction which is opposite to the loading direction of rotation 8.

[0032] Advantageously, the pawl-like jaws 10 are contoured so as to prevent unwanted sticking in their action to engage with and disengage from the pivots 11, 13.

[0033] The operation of the compensation device 1 according to the present invention will be clear from the foregoing description.

[0034] In particular, during its normal operation the coil spring of the contrast element keeps the cable 6 under tension, adjusting to its variations in length.

[0035] According to what is described above, any controlled (i.e. slow) rotations of the variable-radius pulley 2 will not lead to the intervention of the emergency brake 9 as shown in Figure 3.

[0036] Differently, following for example the breakage of the tensioned cable 6, the coil spring returns the variable-radius pulley 2 by imparting a sudden acceleration on it in the opposite direction to the loading direction of rotation 8, which leads to the opening of the pawl-like jaws 10, the recesses 14 of which engage with the second pivots 13, effectively locking the compensation device 1.

[0037] When the emergency is over, by rotating the variable radius pulley 2 in the loading direction of rotation 8, the pawl-like jaws 10 disengage from the second pivots 13, and return to their gathered position by means of the action of the elastic means 12. This return movement is further facilitated by the shape structure of the profiled and blended radially external surfaces of the pawl-like jaws 10 slipping on the second pivots 13.

[0038] In practice it has been found that the compensation device according to the present invention achieves the set aim and objects.

[0039] The compensation device, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

[0040] Moreover, all the details may be substituted by other, technically equivalent elements. In practice the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.

[0041] The disclosures in Italian Patent Application No. 102023000025248 from which this application claims priority are incorporated herein by reference.

[0042] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

CLAIMS1. A compensation device (1) for compensating the length of tensioned cables, which comprises at least one variable-radius pulley (2) which is associated, so that it can rotate about its axis of rotation (3), with a supporting structure (4) and is provided, at a radially external portion thereof, with coupling means (5) for coupling with a tensioned cable (6), said supporting structure (4) being associable with an anchoring element and between said supporting structure (4) and said variable-radius pulley (2) there being a contrast element adapted to deform elastically as a result of the rotation of said variable-radius pulley (2) about said supporting structure (4) in a loading direction of rotation (8) which matches the pull of said tensioned cable (6) so as to convert the elastic reaction to the deformation of said contrast element into a pull applied to said tensioned cable (6); characterized in that it comprises an emergency brake (9) adapted to stop sudden rotations of said variable-radius pulley (2) with respect to said supporting structure (4) in the opposite direction to that of said loading direction of rotation (8).

2. The compensation device (1) according to claim 1, characterized in that said emergency brake (9) comprises a plurality of pawl-like jaws (10) which are arranged substantially circumferentially, with respect to each other, around said axis of rotation (3) and are each hinged about first pivots (11) which are integral in rotation with said variable-radius pulley (2); said pawl-like jaws (10) being movable on a plane substantially perpendicular to said axis of rotation (3) with respect to said variable-radius pulley (2) between a gathered position, in which said pawl-like jaws (10) are mutually aligned along said circumferential direction by means of the return action of elastic means (12), and a locked position, in which said pawl-like jaws (10) have an orientation that substantially exits radially with respect to said circumferential direction for their engagement with second pivots (13) which are integral with said supporting structure (4) as a result of an angularacceleration of said variable-radius pulley (2) which is opposite to said loading direction of rotation (8) and is such as to impart to said pawl-like jaws (10) an inertia that is greater than the elastic return of said elastic means (12).

3. The compensation device (1) according to claim 1 or 2, characterized in that said pawl-like jaws (10) have, on their radially external surface, a recess (14) designed to engage one of said second pivots (13) in said locked position.

4. The compensation device (1) according to one or more of the preceding claims, characterized in that said pawl-like jaws (10) have a radially external surface which is profiled and blended to disengage from said second pivots (13) during the rotation of said variable-radius pulley (2) along said loading direction of rotation (8).

5. The compensation device (1) according to one or more of the preceding claims, characterized in that each of said pawl-like jaws (10) defines a first-class lever in which its fulcrum is defined by its pivoting with the respective one of said first pivots (11), its resistance force is defined by the action of said elastic means (12), and its effort force is defined by the force of inertia due to the acceleration of said variable-radius pulley (2).

6. The compensation device (1) according to one or more of the preceding claims, characterized in that said elastic means comprise, for each one of said pawl-like jaws (10), a helical torsion spring interposed between a first portion (16) of said pawl-like jaw (9), defining the resistance arm of said first-class lever, and a resting surface which is radially internal with respect to said first pivots (11) and is integral in rotation with said variableradius pulley (2).

7. The compensation device (1) according to one or more of the preceding claims, characterized in that the center of gravity of each one of said pawl-like jaws (10) is defined within a second portion (15) of said pawl-like jaw (9), which defines the effort arm of said first-class lever.

8. The compensation device (1) according to one or more of the preceding claims, characterized in that the distal portion of each one of said second portions (15) of said pawl-like jaws (10) ends with an abutment surface (17) designed to rest against the distal portion of said first portion (16) of the consecutive one of said pawl-like jaws (10) in a direction which is opposite to said loading direction of rotation (8).

9. The compensation device (1) according to one or more of the preceding claims, characterized in that said contrast element comprises at least one coil spring connected, with one end thereof, to said variable-radius pulley (2) in such a manner as to contrast its rotation in the direction which is opposite to said loading direction of rotation (8) and, with the other end thereof, to said supporting structure (4).

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