WO2000077902A1

WO2000077902A1 - Damper for an overhead cable

Info

Publication number: WO2000077902A1
Application number: PCT/CA2000/000637
Authority: WO
Inventors: Pierre Van Dyke; Roger Paquette
Original assignee: Hydro-Quebec
Priority date: 1999-06-11
Filing date: 2000-05-30
Publication date: 2000-12-21
Also published as: AU4907200A; CA2274402A1; US6469246B1

Abstract

A damper (10) for absorbing vibrations in an overhead cable (12) which has a support member (14) attached to the cable (12) and at least one dampening member (30) pivotally connected to an axial member (24) mounted on a support axis (22) extending substantially horizontally under the cable (12). Each dampening member (30) has an arm (32) provided with a weight (34) and having an end (36) effecting the connection to the axial member (24). Both the axial member (24) and the end (36) of the dampening member (30) have cooperating pairs of stops (28a, 28b, 28c, 28d and 40a, 40b, 40c, 40d) limiting the pivotal movement of the dampening member (30) around the support axis (22). Between the corresponding stops (28a, 28b, 28c, 28d and 40a, 40b, 40c, 40d) of the axial member (24) and end of the dampening member (30) are provided resilient cylinders (26a, 26b, 26c and 26d) further limiting the pivoting of the dampening member (30) in a resilient manner.

Description

DAMPER FOR AN OVERHEAD CABLE

FIELD OF THE INVENTION

The present invention relates to a damper for an overhead cable such as cables of electrical transmission lines.

BACKGROUND

Wind blowing across a suspended conductor of a transmission line is a very well known source of damage. It induces vibrations which, under resonant conditions, build up to large amplitudes resulting in destructive forces on the conductor. To alleviate this problem, there is known to install a damping device on the conductor, which absorbs the vibration energy. For example, torsional dampers are devices comprising two ball-shaped weights rigidly connected together and fixed on the side of the conductor. When a vertical vibration is induced in the conductor, it is transferred to the weight which rotates in a plan perpendicular to the conductor, inducing therein a torsional movement which is attenuated much more quickly than the vibrational movement. In dampers of the type known as Stockbridge, two weights are suspended on each side of a length of cable called "messenger" . When the conductor vibrates, it excites the weights generating a flexion in the messenger. The strands in the messenger rub against each other, dissipating the energy. The above described dampers are efficient in reducing wind vibrations, but lack endurance and need to be replaced often, especially in harsh climates. Also known in the art is U.S. patent no. 4, 1 67,646 (MATHIEU) .

Mathieu discloses a vibration damper for overhead conductors, having two weight each connected to a rigid arm, each arm being themselves connected through an elastomer ball to a clamp attached to the conductor. The use of an elastomer joint allows a more solid connection compared to the traditional messenger. However, ball-shaped elastomer joints are relatively difficult and therefore expensive to manufacture and install .

Other related art includes U.S. patents nos. 2,094,899 (D. MaclNTYRE) 2,688,047 (D. MaclNTYRE); 3,314,503 (V.H. NEUBERT); 3,662,08 (SMREKAR) 3,692,919 (ROSTOKER); 3,71 1 ,624 (DULHUNTY); 3,773,967 (STURM) 3,780,207 (CROSBY et al.); 3,904,81 1 (OTS KI et al.); 4,01 1 ,397 (BOUCHE) 4, 1 13,979 (TORR et al.); 4,140,868 (TUTTLE); 4,1 59,393 (DULHUNTY) 4,1 67,646 (MATHIEU); 4,223,1 76 (HAWKINS); 4,259,541 (BOUCHE); 4,278,833 (HAWKINS); 4,523,053 (RAWLINS); 4,525,596 (DIANA); 4,527,009 (HAWKINS) 4,533,785 (RIGANTI); 4,554,402 (HAWKINS); 4,554,403 (HEARNSHAW) 4,620,059 (SHERMAN); 4,620,060 (PERINETTI); 4,680,424 (HAWKINS) 4,714,799 (HAWKINS); 4,777,327 (RICHARDSON, Jr.); 4,808,766 (BUCKNER et al.); and 5,801 ,329 (SCHMIDT). None of these patents disclose a resistant damper for overhead conductors which is relatively easy and inexpensive to manufacture.

OBJECT AND SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a damper for an overhead cable that is resistant, even in harsh climates.

It is another object of the invention to provide such a damper that is relatively easy and inexpensive to manufacture.

Accordingly, the present invention provide a damper for an overhead cable, comprising: a support member having a first end provided with a connecting means for connecting said support member to the overhead cable, and a second end having a support axis extending substantially horizontally when the damper hangs from the overhead cable, the support member further including an axial member mounted along the support axis and rigidly connected to the second end, the axial member being provided with at least one pair of stops; a first dampening member having an arm and a weight connected thereto, the arm having an end pivotally connectable to the support axis, the end of the arm being provided with at least one pair of stops corresponding to and cooperating with the at least one pair of stops of the axial member for limiting a pivotal movement of the first dampening member in both directions; resilient means located between the pairs of stops of the axial member and the corresponding pairs of stops of the arm for limiting in a resilient manner the pivotal movement of the first dampening member around the support axis; and restraining means for restraining a movement of the end of the arm of the first dampening member along the support axis. Other features and advantages of the present invention will be better understood upon reading the following non-restrictive description of embodiments thereof with reference to the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1 A and 1 B are perspective views of dampers installed on an overhead cable in accordance with two embodiments of the invention. Figure 2 is an exploded view of the damper of figure 1 A. Figure 3 is a front view of the end of the arm of the first dampening member of the damper of figure 1 A. Figure 4 is a cross-sectional view along lines IV-IV of figure 3.

Figure 5 is a cross-sectional view along lines V-V of figure 3. DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Referring to figures 1 A, 1 B and 2 to 5, there is shown a damper ( 1 0) for an overhead cable (1 2) according to embodiments of the present invention. The damper (1 0) first includes a support member ( 1 4), which has a first end ( 1 6) and a second end (1 8) . The first end (1 6) is connected to the overhead cable ( 1 2), here by a clamp (20) . Any other appropriate connecting means may of course be used without departing from the scope of the present invention. A support axis (22) is provided at the second end (1 8), extending substantially horizontally when the damper (1 0) hangs from the overhead cable ( 1 2). The support member (1 4) further includes an axial member (24) mounted along the support axis (22), and a connecting mechanism for rigidly connecting the axial member to the second end (1 8) . The connecting mechanism comprises recesses (51 ) formed in the second end (1 8) of the support member (14) and projections (53) of the axial member (24) that cooperate with the recesses (51 ).

The axial member (24) is provided with at least one pair of stops. In the embodiment illustrated in figure 2, the axial member (24) is cross- shaped and has four radial legs (26a, 26b, 26c and 26d), defining four V- shaped inner corners (28a, 28b, 28c and 28d) . Four first pairs of stops are therefore provided on the axial member (24) in this embodiment, defined by the branches of inner corners (28a, 28b, 28c and 28d).

In the embodiment of figure 1 A and 2, the axial member (24) is supported by two parallel arms (52, 54) rigidly fixed to the clamp (20) of the support member (1 4) and projecting downwardly therefrom. The support axis (22) extends from one arm (52) to the other (54) . The axial member (24) is pivotally connected to the support axis (22), and is held in a fixed position with respect to the arms (52, 54) by means of recesses (51 ) which cooperate with projections (53) of the axial member (24) . Referring now to figure 1 B, the arm (54) may also be omitted and simply replaced by a closing plate (56), to limit manufacturing costs.

Referring again to figures 1 A, 1 B and 2 to 5, the damper ( 1 0) also includes a first dampening member (30), having an arm (32) to which is connected a weight (34) . The arm (32) has an end (36) mounted around the axial member (24), the end (36) being provided with at least one pair of stops, corresponding to and cooperating with the at least one pair of stops of the axial member (24) for limiting a pivotal movement of the first dampening member (30) in both directions with respect to the axial member (24) . Preferably, the end (36) of the arm (32) comprises an inner cylindrical wall (38) having four arc-shaped cavities (40a, 40b, 40c and 40d) regularly distributed along its circumference, defining four pairs of stops of the end (36) of the arm (32) which cooperate with the four first pairs of stop of the axial member (24) . The damper (1 0) according to the present invention may include any number of dampening members similar to the first dampening member (30) as may be convenient. Preferably, two dampening members are provided, extending on each side of the axial member (24) . The second dampening member (42) includes the same components as the first dampening member (30), that is an arm (32) having a weight (34) connected thereto and having an end (36) mounted around the axial member (24). Advantageously, the weights (34) of the dampening members may be different, that is one heavier than the other, to provide different resonance frequencies for the vibration of each dampening member. The end (36) of the arm (32) of the second dampening member (42) is also preferably provided with an inner cylindrical wall (38) having four arc-shaped cavities (40a, 40b, 40c and 40d) regularly distributed along its circumference, defining four pairs of stops of the end (36) of the arm (32) . In this embodiment the axial member (24) has four second pairs of stops provided by the branches of inner corners (28a, 28b, 28c and 28d) to cooperate with the four pairs of stops provided by the four arc-shaped cavities (40a, 40b, 40c and 40d) of the second dampening member (42) . The axial member (24) includes four radial separating shoulders (44a, 44b, 44c and 44d) extending respectively in the V-shaped inner corners (28a, 28b, 28c and 28d) . The V-shaped inner corners (28a, 28b, 28c and 28d) in this manner embody on one side of the shoulders (44a, 44b, 44c and 44d) the four first pairs of stops and on the other side of the shoulders the four second pairs of stops.

The damper (1 0) further includes resilient means located between the pairs of stops of the axial member (24) and the corresponding pairs of stops of each arm (32), for limiting in a resilient manner the pivotal movement of the corresponding dampening member around the support axis (22) . The resilient means preferably include four cylindrical-shaped elastomer bodies (46a, 46b, 46c and 46d) per dampening member, partially located in the corresponding arc-shaped cavities (40a, 40b, 40c and 40d) and in the V- shaped inner corners (28a, 28b, 28c and 28d) . The cylindrical-shaped elastomer bodies (46a, 46b, 46c and 46d) extend along axes parallel to the support axis (22) . One end of each cylinder-shaped elastomer bodies (46a, 46b, 46c and 46d) abut on the shoulders (44a, 44b, 44c and 44d), and the opposed end abuts on the second end ( 1 8) of the support member. In this manner, an axial displacement of cylinder-shaped elastomer bodies (46a, 46b, 46c and 46d) along the support axis (22) is prevented.

The damper (1 0) according to the present invention also includes restraining means for restraining a movement of the end of the arm (36) of each dampening member (30, 42) along the support axis (22) . For each dampening member, these restraining means include the corresponding cylinder-shaped elastomer bodies (46a, 46b, 46c and 46d) and face walls extending along each face of the end of the arm (36) . The first face walls (59) partially close two of the arch-shaped cavities (40b, 40d) along the first face (55) of the end of the arm (36). Similarly, the second face walls (61 ) close the remaining two arc-shaped cavities (40a, 40c) along the second face (57) of the end of the arm (36) . These walls cooperate with the cylinder-shaped elastomer bodies (46a, 46b, 46c and 46d), each of which abuts on one of the wall at one of its ends . This prevents an axial movement of the end of the arm (36) with respect to the cylinder-shaped elastomer bodies (46a, 46b, 46c and 46d) . Since these elastomer bodies are themselves prevented from an axial displacement with respect to the support axis (22), the result is that the axial movement of end of the arm (36) with respect to the support axis (22) is resiliently restrained by the restraining means.

Preferably, the end (36) of the arm (32) of the first dampening member (30) comprises an outward stop (48) projecting toward the second dampening member (42) . Similarly, the end (36) of the arm (32) of the second dampening member (42) comprises an outward stop (50) projecting toward the first dampening member (30) . The outward stops (48, 50) cooperate together to prevent the pivotal movement of the dampening members past a predetermined pivoting angle. In the preferred embodiment, two outward stops (48, 50) are provided on each dampening member (30, 42). Of course, numerous modifications could be made to the preferred embodiments disclosed hereinabove without departing from the scope of the invention as defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1 . A damper (1 0) for an overhead cable (1 2), comprising: a support member (1 4) having a first end (1 6) provided with a connecting means for connecting said support member (1 4) to the overhead cable ( 1 2); and a first dampening member (30) having an arm (32) and a weight (34) connected thereto, characterized in that: the support member ( 1 4) has a second end (1 8) having a support axis (22) extending substantially horizontally when the damper ( 1 0) hangs from the overhead cable (1 2), said support member further including an axial member (24) mounted along the support axis (22), and a connecting means for rigidly connecting the axial member (24) to the second end (1 8), the axial member (24) being provided with at least one pair of stops (28a, 28b, 28c or 28d); the arm (32) of the first dampening member (30) has an end (36) mounted around the axial member (24), the end (36) of the arm (32) being provided with at least one pair of stops (40a, 40b, 40c or 40d) corresponding to and cooperating with the at least one pair of stops (28a, 28b, 28c or 28d) of the axial member (24) for limiting a pivotal movement of the first dampening member (30) in both directions; and the damper (1 0) further comprises: resilient means located between the pairs of stops of the axial member (24) and the corresponding pairs of stops of the arm (32) for limiting in a resilient manner the pivotal movement of the first dampening member (30) around the support axis (22); and restraining means for restraining a movement of the end (36) of the arm (32) of the first dampening member (30) along the support axis (22) .

2. A damper (1 0) according to claim 1 , characterized in that the axial member (24) comprises four first pairs of stops (28a, 28b, 28c and 28d), and the end (36) of the arm (32) of the first dampening member (30) comprises four corresponding pairs of stops (40a, 40b, 40c and 40d) .

3. A damper (1 0) according to claim 2, characterized in that: the axial member (24) is cross-shaped and has four radial legs (26a, 26b, 26c and 26d) defining four V-shaped inner corners (28a, 28b, 28c and 28d) that embody the four pairs of stops of the axial member (24); the end (36) of the arm (32) comprises an inner cylindrical wall (38) regularly provided with four arc-shaped cavities (40a, 40b, 40c and 40d) that embody the four pairs of stops of the end (36) of the arm (32); and the resilient means comprise four cylindrical-shaped elastomer bodies (46a, 46b, 46c and 46d) partially located in the arc-shaped cavities (40a, 40b, 40c and 40d) and in the V-shaped inner corners (28a, 28b, 28c and 28d), the cylindrical-shaped elastomer bodies (46a, 46b, 46c and 46d) extending along axes parallel to the support axis (22) .

4. A damper (10) according to claim 3, characterized in that the end (36) of the arm (32) of the first dampening member (30) has a first face (55) and a second face (57) opposite the first face (55), and the restraining means comprise: said cylindrical-shaped elastomer bodies (46a, 46b, 46c and 46d); first face walls (59) partially closing two of the arc-shaped cavities (40b, 40d) along the first face (55) of the end 26 of the arm (32); and second face walls (61 ) partially closing remaining two arc-shaped cavities (40a, 40c) along the second face (57) of the end (36) of the arm (32), the cylindrical-shaped elastomer bodies (46a, 46b, 46c and 46d) cooperating with the first face and second face walls (59, 61 ) for restraining in a resilient manner the movement of the end (36) of the arm (32) of the first dampening member (30) along the support axis (22) .

5. A damper (1 0) according to claim 2, characterized in that: the axial member (24) comprises four second pairs of stops (28a,

28b, 28c and 28d), and said damper ( 1 0) further comprises: a second dampening member (42) having an arm (32) and a weight (34) connected thereto, the arm (32) of the second dampening member (42) having an end (36) pivotally mounted around the axial member (24), the end (36) of the arm (32) of the second dampening member (30) being provided with four pairs of stops (40a, 40b, 40c and 40d) corresponding to and cooperating with the second pairs of stops (28a, 28b, 28c and 28d) of the axial member (24) for limiting a pivotal movement of the second dampening member (42) in both directions with respect to the axial member (24); additional resilient means located between the second pairs of stops of the axial member (28a, 28b, 28c and 28d) and the corresponding pairs of stops (40a, 40b, 40c and 40d) of the end (36) of the arm (32) of the second dampening member (42) for limiting in a resilient manner the pivotal movement of the second dampening member (42); and additional restraining means for restraining a movement of the end

(36) of the arm (32) of the second dampening member (42) along the support axis (22).

6. A damper (1 0) according to claim 5, characterized in that: the axial member (24) is cross-shaped and has four radial legs (26a,

26b, 26c and 26d) defining four V-shaped inner corners (28a, 28b, 28c and 28d), the axial member (24) further comprising four radial separating shoulders (44a, 44b, 44c and 44d) extending respectively in the V-shaped inner corners (28a, 28b, 28c and 28d) so that said V-shaped inner corners (28a, 28b, 28c and 28d) embody on one side of the shoulders (44a, 44b, 44c and 44d) the four first pairs of stops and on the other side of the shoulders (44a, 44b, 44c and 44d) the four second pairs of stops, the restraining means of the first and second dampening members (30, 42) abutting on said shoulders (44a, 44b, 44c and 44d) to prevent a displacement thereof along the support axis (22), each end (36) of the arms (32) of the first and second dampening members (30, 42) comprises an inner cylindrical wall (38) regularly provided with four arc-shaped cavities (40a, 40b, 40c and 40d) that embody its four pairs of stops; and each of the resilient means and the additional resilient means comprises four cylindrical-shaped elastomer bodies partially (46a, 46b, 46c and 46d) located in the four arc-shaped cavities (40a, 40b, 40c and 40d) of the end (36) of the corresponding arm (32), and in the four corresponding V-shaped inner corners (28a, 28b, 28c and 28d) of the axial member (24), each of the cylindrical-shaped elastomer bodies (46a, 46b, 46c and 46d) extending along an axis parallel to the support axis (22) and abutting at one end on a corresponding one of the radial separating shoulders (44a, 44b, 44c and 44d) to prevent an axial displacement of each of the cylindrical- shaped elastomer bodies (46a, 46b, 46c and 46d).

7. A damper (1 0) according to claim 6, characterized in that the end (36) of the arm (32) of each of the first and the second dampening member (30, 42) has a first face (55) and a second face (57) opposite the first face (55), and each of the restraining means and the additional restraining means comprise: said cylindrical-shaped elastomer bodies (46a, 46b, 46c and 46d) of corresponding ones of the resilient means and the additional resilient means; first face walls (59) partially closing two of the arc-shaped cavities (40b, 40d) along the first face (55) of the end (36) of the arm (32); and second face walls (61 ) partially closing remaining two arc-shaped cavities (40a, 40c) along the second face (57) of the end (36) of the arm (32), the cylindrical bodies (46a, 46b, 46c and 46d) cooperating with the first face and second face walls (59, 61 ) for restraining in a resilient manner the movement of the end (36) of the arm (32) of the corresponding dampening member (30, 42) along the support axis (22) .

8. A damper (10) according to claim 6, characterized in that the end (36) of the arm (32) of the first dampening member (30) comprises an outward stop (48) projecting toward the second dampening member (42), and the end (36) of the arm (32) of the second dampening member (42) comprises an outward stop (50) projecting toward the first dampening member (30), said outward stops (48, 50) of the first and second dampening members (30, 42) cooperating together to prevent the pivotal movement of the dampening members (30, 42) past a predetermined pivoting angle.

9. A damper (10) according to claim 5, characterized in that the weight (34) of the second dampening member (42) is heavier than the weight (34) of the first dampening member (30) .

10. A damper (1 0) according to claim 1 , characterized in that the connecting means of the support member (1 4) comprises a clamp (20) for clamping the damper (1 0) to the overhead cable (1 2).

1 1 . A damper (1 0) according to claim 1 , characterized in that the support member (1 4) comprises two parallel arms (52, 54) connecting the first end (1 6) to the second end (1 8) thereof, the support axis (22) extending between said two parallel arms (52, 54) .

12. A damper (10) according to claim 11, characterized in that the support member (14) is mounted between the two parallel arms (52, 54) by means of a screw (22).

13. A damper (10) according to claim 1, characterized in that the support member (14) comprises a support arm (54) connecting the first end (16) to the second end (18) thereof, the support axis (22) projecting generally perpendicularly from said support arm (54).

14. A damper (10) according to claim 13, characterized in that the support member (14) further comprises a closing plate (56), the support member (14) being mounted along the support axis (22) by means of a screw (22) extending between the support arm (54) and said closing plate (56).

15. A damper (10) according to claim 1, charactertized in that the connecting means for rigidly connecting the axial member (24) to the second end (18) of the support member (14) comprise recesses (51) formed in the second end (18), and projections (53) of the axial member (24) that cooperate with said recesses (51).