High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Air-current blowout
Reexamination Certificate
2000-06-24
2001-08-07
Barrera, Ramon M. (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Air-current blowout
C218S048000, C218S078000
Reexamination Certificate
active
06271494
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to high-voltage circuit breakers and provides the structural design of the drive mechanism that moves the auxiliary contacts, used for arc quenching, in opposite directions.
BACKGROUND INFORMATION
In circuit breakers, the two coaxially opposite auxiliary contacts, frequently referred to as arcing contacts, are coaxially surrounded by two permanent-current contacts, one of which is stationary and the other designed to move in an axial direction. Circuit breakers of this type usually work with a gaseous quenching agent that flows through the area separating the contacts during switching and whose flow can be influenced by special compression chambers and nozzles. Among other things, an insulating nozzle that is located within the permanent-current contacts, surrounds the arcing contacts, and can be permanently connected to both the drivable permanent-current contact and the driven arcing contact, is used for this purpose.
In a conventional circuit breaker of this type, as described in, for example, European Patent No. 0 313 813, a driving element is attached to the insulating nozzle, which transmits the driving movement of the driven permanent-current contact to the second arcing contact via corner gears in such a way that the two arcing contacts are driven in opposite directions. For this purpose, the second arcing contact is inserted into a sliding contact. In the known corner gears, the driving element is designed as a gear rack that acts upon the second arcing contact, which is also designed as a gear rack, via a gear wheel. The driving movement of the insulating nozzle is transmitted linearly onto the second arcing contact being driven in the opposite direction. Alternatively, the corner gears can also be a locking mechanism having a ratchet gear that is moved by the driven contacts and a clamping part equipped with a compression spring, with the clamping part driving the arcing contact moving in the opposite direction in a pulsating manner after a ratchet clears the ratchet gear.
In another conventional circuit breaker of this type, a crank can also be used as the corner gear, with its rotating part being formed by the gear wheel that is driven by the gear rack connected to the insulating nozzle, as described in, for example, European Patent No. 0 696 040. The linear movement of the gear rack is transmitted sinusoidally to the second arcing contact.
In conventional corner gears, the second arcing contact driven in the opposite direction is coupled with the complete travel of the first driven arcing contact either permanently or only temporarily using a low-precision ratchet gear.
SUMMARY
An object of the present invention is to design the corner gears so that, when the first driving arcing contact engages positively with the second arcing contact driven in the opposite direction, the second arcing contact is driven only along part of the contact travel, allowing the second arcing contact driven in the opposite direction to pass a defined maximum speed at a predetermined point during this driving phase.
According to the present invention, this object is achieved by designing the rod-like driving element as a coupling rod having a journal positioned transversely to the direction of thrust, and providing the corner gears with a two-arm control lever having two stable end positions, with one of its two ends being designed in the shape of a fork for connecting-link type guidance of the journal, and the other end being pivoted on the second arcing contact via a reciprocating element. This reciprocating element can be a connecting rod or a journal that engages with a slot in the second arcing contact.
A corner gear embodiment of this type is characterized by fewer, simpler, and lighter-weight components so that the corner gears have a low mass and form a self-contained unit that can have a flat design, therefore not hindering the flow of insulating gas (waste gas) that is produced in the stationary permanent-current contact during switching. The corner gears also have a transmission ratio that varies during actuation, is designed in the form of a sinusoidal half wave and its maximum can exceed 1:1, i.e., the second arcing contact being driven in the opposite direction can be moved at a higher speed than the first arcing contact during the decisive phase of contact opening (phase of contact separation and increasing distance between contacts). To achieve this, the corner gears are suitably designed so that the coupling rod is inserted into a guideway fastened to the stationary permanent-current contact. The fulcrum of the two-armed control lever is located between the thrust connecting rod and the axis of the second arcing contact and is also connected to the stationary permanent-current contact. The two-armed control lever is also positioned at an angle to the thrust rod and to the axis of the second arcing contact when in its stable end positions. The fork-shaped end of the control lever is additionally provided with a longitudinal, open-ended cut-out between the two tines. The further journal located on the other end of the control lever is also positioned transversely to the direction of coupling rod travel, with the slot with which this journal engages being located in a head piece provided on the second arcing contact. The head piece, in turn, is guided in an axial direction along with the stationary portion of the journal bearing connected to the sliding contact. The fork-like design of the one end of the control lever can provide an open-ended cut-out that is designed so that the inward and outward axial movement into and out of the second arcing contact takes place without impact. To ensure secure guiding of the control lever in its three positions (open, moving, and closed) in a compact design, the thrust rod, according to a further embodiment of the present invention, has a guideway that is provided with a cut-out that clears the rotational range of the fork-shaped end of the control lever, and the two tines of the forkshaped end of the control lever are provided with flattened areas on their outer surfaces, allowing the control lever to rest against the bottom of the thrust rod when the control lever is in either of the two end positions. To stabilize these two end positions, two stops are also attached to the stationary portion of the journal bearing, with one of the flattened areas on the control lever coming to rest against these stops. This prevents control lever overshooting at the end of the engagement between the journal and the fork-shaped end of the control lever.
REFERENCES:
patent: 4973806 (1990-11-01), Kirchesch et al.
patent: 5578806 (1996-11-01), Hofbauer et al.
patent: 479 155 (1969-09-01), None
patent: 0 313 813 (1989-05-01), None
patent: 0 696 040 (1996-02-01), None
patent: 2 491 675 (1982-04-01), None
patent: WO 98/32142 (1998-07-01), None
Dienemann Hold
Lehmann Volker
Marin Heiner
Barrera Ramon M.
Kenyon & Kenyon
Siemens Aktiengesellschaft
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