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AssigneeAlstom T&D SA
InventorVon Allmen Peter
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A spring-loaded operating mechanism for a high-voltage circuit-breaker comprises, between a motor and a trigger shaft, a freewheel-type coupling device which comprises first and second friction members (5, 6) coaxially mounted on a secondary shaft (1). The first friction member (5) is screwed onto the secondary shaft (1) and the second friction member can freewheel about the secondary shaft (1) while being disposed between the first member and an axial abutment (8). The two members (5, 6) are substantially in abutment one against the other along the secondary shaft (1), and the first member is screwed or is unscrewed along the secondary shaft depending on whether it is rotated by the shaft or by the second member. The device does not require any greasing; it operates without maintenance. In addition, the forces exerted by one friction member on the other are low, thereby improving the reliability of the operating mechanism.
1/ Operating mechanism for a high-voltage circuit-breaker comprising a coupling device (A) of the freewheel type disposed between a trigger shaft (AC) of the operating mechanism and an electrical motor (M), the coupling device comprising a first friction member (5) linked in motion with the trigger shaft and a second friction member (6) linked in motion with the electrical motor, said friction members being coaxially mounted on a secondary shaft (1) so that when said secondary shaft rotates in a predetermined direction (D) when a spring-loaded mechanism that acts on the device relaxes, it being possible for the second friction member (6) to freewheel about said secondary shaft (1) in said predetermined direction (D) at a speed of rotation that is lower than the speed of rotation of the secondary shaft (1), it also being possible for said second friction member (6) to be rotated by the motor in said predetermined direction, and to become constrained to rotate with the first friction member (5) so as to recock said spring-loaded mechanism, characterized in that said first friction member (5) has an outer surface (5′) of conical shape and comprises a central bore screwed onto said secondary shaft (1), in that the second friction member (6) comprises a peripheral set of teeth (12) mashing with the motor drive shaft and a central bore with an inner conical surface (6′) which substantially surrounds the outer conical surface (5′) of said first friction member, said first and second friction members being designed so that said first friction member is suitable for being moved over a short axial stroke along the secondary shaft either by being screwed when it becomes constrained to rotate with the second member (6) or by being unscrewed when said member freewheels about said secondary shaft (1), in that said first and second friction members (5, 6) remain continuously substantially in abutment one against the other along said secondary shaft (1), in that said first friction member (5) is suitable for acting when it is screwed to exert a pressure on said second friction member (6), and in that said second member (6) is suitable for acting under the effect of said pressure to press against an axial abutment (8) on the secondary shaft (1) so as to stop said first friction member (5) moving by being screwed, and so as to rotate said secondary shaft by constraining it to rotate with said first friction member (5).
2/ Operating mechanism according to claim 1, in which said first friction member (5) is held substantially in abutment against said second friction member (6) by a spring (10).
3/ Operating mechanism according to claim 2, in which said first friction member is screwed onto a thread (F) formed on the shaft (1), said thread being reversible.
4/ Operating mechanism according to any one of claims 1 to 3, in which said axial abutment is a ball-bearing abutment (7).
5/ Operating mechanism according to any one of claims 1 to 4, in which said first friction member (5) is provided with a peripheral set of teeth (12) meshed with said trigger shaft.
6/ Operating mechanism according to any one of claims 1 to 5, in which a conical ring (13) is disposed between the two conical surfaces of said friction members (5,6).
7/ Operating mechanism according to any one of claims 1 to 6, in which the first member (5) has an outer conical surface (5′) which is provided with peripheral grooves (5″) serving to absorb dust.
8/ Operating mechanism according to claim 6, in which the conical ring (13) is made with polyamide reinforced with glass fiber.
9/ Operating mechanism according to claim 3, in which the thread (F) has four starts with a pitch of about 20 mm per turn, and the secondary shaft has a diameter of about 24 mm.