Title of Invention

ARE-EXTINGUISHING CHAMBER FOR LOW-VOLTAGE CIRCUIT BREAKERS

Abstract

Arc-extinguishing chamber for low-voltage circuit breakers An arc-extinguishing chamber for low-voltage circuit breakers comprises an extinguishing-chamber housing (1) and an extinguishing-chamber cover (10), which is detachably joined to the extinguishing-chamber housing (1) by means of fastening elements. Opposite a hollow extension (3), the extinguishing-chamber housing (1) has a nose (8) over which a claw-like extension (9) of the extinguishing-chamber cover (10) can grip. A further type of fastening of the extinguishing-chamber cover (10) comprises lateral nose- like webs (14, 15) on the extinguishing-chamber housing (1), and projections (16, 17) on both sides on the extinguishing-chamber cover (10) to grip over the noses (14, 15).

Full Text

Description The invention relates to arc-extinguishing chambers for air-break low-voltage circuit breakers, in particular the reduction of the joining elements needed for their assembly. Air-break low-voltage circuit breakers need an arc-extinguishing chamber for operation, in order to extinguish any switching arcs which occur without impairing the circuit breaker itself and adjacent installation parts or other subassemblies, since otherwise there is the risk that the hot and thus ionized arc gases will cause electric flashovers or other damage. Arc-extinguishing chambers can be produced only as separate units, in particular in the case of large circuit breakers. During their joining to the main body of the circuit breaker and the joining of their individual parts to one another, the object is set of sealing the technically necessary gaps and joints against the passage of ionized arc gases, and of preventing electric flashovers as a result of any gases which nevertheless emerge. To this extent, particular attention also has to be paid to the joining of the extinguishing-chamber cover to the extinguishing-chamber housing. US-A 4 388 506 illustrates an extinguishing chamber which is removably arranged on an air-break circuit breaker. To this end, on the side of the stationary contact the extinguishing chamber is inserted into a groove by means of a hook-like extension and, on the side of the movable switching contact, is fixed with the aid of screws. Even here, however, the extinguishing-chamber cover is fastened to the housing of the extinguishing chamber using four screws. The hook-like extension is used in the case of this switch for fastening the entire extinguishing chamber and in addition primarily for sealing against any emerging ionized arc gases. GR 96 P 4093 - 2 - DE-A 35 41 514 describes an arc-extinguishing chamber having an attachment for the further cooling of the emerging gases. This attachment is fastened to the arc-extinguishing chamber with a total of four screws. These screws pass through holes in the wall of the housing body of the arc-extinguishing chamber, into laterally open pockets which are dimensioned in accordance with the dimensions of nuts inserted therein, in which nuts the screws can engage with their thread. This design not only requires four fastening screws but also a great deal of effort in terms of design and production, for example for the laterally open pockets for the accommodation of the nuts. EP Patent Application 0 225 207 describes an arc-extinguishing chamber in which the arc splitters are housed between two side walls which are provided with ribs and grooves and have integrally moulded half-coverings of the extinguishing chamber with an isolating holder. By means of the latter, the covering halves are fastened with the aid of screws to a bracket which, for its part, is used for fastening to the switch housing, which is carried out with the aid of fastening screws. Apart from the large number of individual parts of the extinguishing chamber per se, a large number of fastening elements are necessary for fastening the extinguishing chamber to the switch, to be precise for each switch pole four screws including washers for fastening the covering halves to the two fastening brackets, these two fastening brackets themselves and two screws with nuts for fixing the fastening brackets to the housing of the switch. In the case of other known switches, for example according to DE 44 10 108 Al, the extinguishing-chaznber cover is fastened to the extinguishing-chamber housing using four screws. The extinguishing-chamber cover in this case covers an extension to the extinguishing-chamber housing, in which a single fastening screw is accommodated in a captive manner, using which screw the complete arc-extinguishing chamber is fastened to the circuit breaker. Arranged in the extinguishing-chamber - 3 - cover is an insertion opening for a screwdriver. Here too, the number of fastening elements needed for fastening the extinguishing-chamber cover to the extinguishing chamber and for fastening the extinguishing chamber to the housing of the switch is relatively large. Starting from this, the invention is based on the object of configuring the arc-extinguishing chamber in such a way that, using simple means and a low number of joining elements, it can be joined together from its individual parts in such a way that the requirements on the joining of its individual parts to one another, in particular the sealing of the technically required gaps and joints against the passage of ionized switching gases, and the prevention of electrical flashovers as a result of any gases which nevertheless emerge, are satisfied. According to the invention, this object is achieved in that on the front side of the extinguishing chamber, opposite the extension, a horizontal nose-like projection is arranged on the upper rim of the extinguishing-chamber housing, and in that the extinguishing-chamber cover has a claw-like extension to grip around the nose-like projection on the extinguishing-chamber housing when the extinguishing-chamber cover is placed on to the extinguishing-chamber housing, and has a hole for the insertion of the fastening screw. The fixing of the extinguishing-chamber cover to the extinguishing-chamber housing is carried out with the aid of only one fastening screw, which is passed through a hole in the extinguishing-chamber cover and the hole in the hollow extension of the extinguishing-chamber housing and is screwed into a corresponding thread provided in the circuit breaker. In the case of this embodiment of the extinguishing chamber, it has proven to be particularly advantageous that the housing of the extinguishing chamber and the extinguishing-chamber cover are jointly fastened to the circuit breaker using only a single screw. According to the invention, a further solution of - 4 - the stated object consists in that on the side walls which adjoin this side of the extinguishing-chamber housing, horizontal nose-like projections are arranged on the upper rim of the extinguishing-chamber housing, in that the extinguishing-chamber cover is provided with claw-like extensions in order to grip around these projections when the said cover is pushed on to the extinguishing-chamber housing, in that an upwardly-directed projection is fitted to the upper rim of the front side of the extinguishing chamber in order to limit the push-on travel of the extinguishing-chamber cover, and in that a stop hole is arranged in the extinguishing-chamber cover in such a way that, for the purpose of the horizontal locking of the extinguishing-chamber cover, the head of the fastening screw forms a stop for the wall of this stop hole. In this way, a sliding guide for the extinguishing-chamber cover is formed, by means of which the extinguishing-chamber cover is firmly held on the extinguishing-chamber housing in the event that any gas pressure occurs, and at the same time sealing of the joint between the extinguishing chamber and the extinguishing-chamber cover against the passage of arc gases is achieved. The head of the fastening screw is used for the horizontal locking of the extinguishing-chamber cover, by resting on the wall of a stop hole in the extinguishing-chamber cover. However, it is also possible for this for an additional angular element to be used which is held in the form of a washer by the fastening screw and, instead of the screw head, forms a stop for the wall of the stop hole in the extinguishing-chamber cover. A passage hole for the insertion of a tool for manipulating the fastening screw is advantageously provided in the extinguishing-chamber cover, axially in relation to the stop hole. Furthermore, an insertion opening for the introduction of the fastening screw is expediently arranged in the extension-chamber cover, beside the passage hole. - 5 - The stop hole in the extinguishing-chamber cover can, however, also be designed as a passage hole with a constant diameter. The proposed configurations for fastening the extinguishing-chamber cover not only permit the number of joining and fastening elements needed as a whole for the assembly of the extinguishing chamber (to join the extinguishing-chamber cover to the extinguishing-chamber housing) to be kept low, in that the screw which is provided for fastening the complete extinguishing chamber is simultaneously also used for joining the extinguishing-chamber cover to the extinguishing-chamber housing, but it also ensures the fulfilment of the requirements in relation to the sealing of the technically required gaps and joints against the passage of ionized arc gases, in that positively closing elements, which support the extinguishing-chamber cover against the gas pressure when switching, counteract the passage of these gases. This design permits both simpler handling and better sealing at the joining point. The invention is explained in more detail below using two preferred exemplary embodiments illustrated in the figures. Fig. 1 shows in schematic form a section through an extinguishing chamber according to the invention, according to a first variant. Fig. 2 shows in schematic form a section along the line A-B in Fig. 3 through an extinguishing chamber according to the invention, according to a second variant. Fig. 3 shows a section of the extinguishing chamber according to Fig. 2 from the side at which it is fastened to the circuit breaker. The extinguishing-chamber housing 1 which is illustrated in Fig. 1 by way of example has, on the side 2 on which it is fastened to the circuit breaker, a hollow extension 3, in which there is a hole 4 for the accommodation of the fastening screw 5. On the opposite front side 6, a horizontal nose-like projection 8 is - 6 - arranged at the upper rim 7 of the extinguishing-chamber housing 1 in such a way that a claw-like extension 9 of the extinguishing-chamber cover 10 grips around the latter when the extinguishing-chamber cover 10 is placed on to the extinguishing-chamber housing 1 and displaced along the rim 7. The fixing of the extinguishing-chamber cover 10 on the extinguishing-chamber housing 1 in the position displaced to the right is carried out with the aid of only a single fastening screw 5, which is led through a corresponding hole 11 in the extinguishing-chamber cover 10 and the hole 4 in extinguishing-chamber housing 1, and is screwed into a thread (not shown) which is appropriately provided in the circuit breaker. In a variant which is illustrated by way of example in Fig. 2, the extinguishing-chamber housing 1 likewise has, on the side 2 at which it is fastened to the circuit breaker, a hollow extension 3 in which there is a hole 4 for the accommodation of the fastening screw 5. However, on the side walls 12, 13 which adjoin this wall 2 of the extinguishing chamber 1, horizontal nose-like projections 14, 15 are arranged on the upper rim 7 of the extinguishing-chamber housing 1 in such a way that they work together with claw-like extensions 16, 17 of the extinguishing-chamber cover 10* These extensions 16, 17 grip around the nose-like projections when the extinguishing-chamber cover is pushed on to the extinguishing-chamber housing 1 from the side 2 for fastening to the circuit breaker. A sliding guide is formed in such a way that the extinguishing-chamber 10 is firmly held on the extinguishing-chamber housing in the event of gas pressure arising as a result of arc gases, and at the same time sealing of the joint between the extinguishing-chamber housing 1 and extinguishing-chamber cover 10 against the passage of arc gases is achieved. An upwardly directly stop 18 on the upper rim 7 of the front side 6 of the extinguishing chamber 1 forms a limitation to the push-on travel and is used at the same time for improved sealing of the joint between the extinguishing-chamber housing 1 and extinguishing-chamber cover 10 against the - 7 - passage of arc gases. The fixing of the extinguishing-chamber cover 10 on the extinguishing-chamber housing 1 is performed with the aid of only one fastening screw 5, which is led through the hole 4 in the extinguishing-chamber housing 1 and screwed into a thread (not shown) which is appropriately provided in the circuit breaker. The head 20 of this fastening screw 5 is used, in a stop hole 22, for the horizontal locking of the extinguishing-chamber cover 10. To this end, an additional angular element 19 is provided, which is held in the form of a washer by the fastening screw 5 and, instead of the screw head 20, forms a stop for the wall 21a in the stop hole 22 in the hollow extension 3 of the extinguishing-chamber cover. If the screw head 20 itself is intended to form the stop, then the extinguishing-chamber housing 1 receives a wall 21 which is indicated with a dash-dotted line in Figure 2. A passage hole 23 for the insertion of a tool for manipulating the fastening screw is provided in the extinguishing-chamber cover 10, axially in relation to the stop hole. The advantages of the configurations according to the invention of the fastening of the extinguishing-chamber cover consist not only in the low number of joining and fastening elements needed as a whole for the assembly of the extinguishing chamber (to join the extinguishing-chamber cover to the extinguishing-chamber housing), in that the screw provided for fastening the complete extinguishing chamber is simultaneously also used for joining the extinguishing-chamber cover to the extinguishing-chamber housing, but also in fulfilling the requirements in relation to the sealing of the technically required gaps and joints against the passage of ionized arc gases, in that positively closing elements support the extinguishing-chamber cover against the gas pressure during switching and counteract the passage of these gases. 8 We Claim 1 An arc extinguishing chamber for a low voltage circuit breakers composing an extinguishing chamber housing (1) having a hollow extension (3) on a side (2) for attaching to the circuit breaker, the hollow extension (3) having a hole (4)for receiving a fastening screw (5), and an extinguishing chamber cover (10) attached to said extinguishing chamber housing (1), the extinguishing chamber housing (1) having at least one horizontal nose-like projection (8, 14, 15) on a upper rim (9) of at least one wall (2, 12,13) of the extinguishing chamber housing (1) for attaching said extinguishing chamber cover (10) to the extinguishing chamber housing (1), the extinguishing chamber cover (10) having at least one claw like extension (9, 16,17) for gripping said at least one honzontal nose-like projection (8,14,15) and a hole (1 l))aligned with said hole (4) in said hollow extension (3) of said extinguishing chamber housing (1), the fastening screw (5) extending through said aligned holes (4, 11) and into a matching thread of said circuit breaker 2 The arc extinguishing chamber as claimed in claim 1, wherein said at least one horizontal nose like projection (8, 14, 15) is arranged on a upper nm (7) of a front side (6) of said extinguishing chamber housing (1) opposite said hollow extension (3), and wherein said at least one claw type extension ( 9, 16,17) is arranged opposite said extinguishing chamber cover (10) so that the at least one claw -like extension (9,16,17) grips the at least one nose-like projection (8, 1 4, 15) when the extinguishing chamber cover (10) is placed on the extinguishing chamber housing (1) 9 3 The arc extinguishing chamber as claimed in claim 1, wherein at least one of said at least one nose-like projections (8, 14, 15) is provided on said upper rim (7) of said each side wall (6) of the extinguishing chamber housing (1) adjacent said side (2) for attaching to the circuit breaker, the at least one claw like extension (9, 16, 17) being positioned to grip the at least one of said at least one nose-like projections (8, 14, 15) when said extinguishing chamber cover (10) is placed on the extinguishing chamber housing (1) , wherein said upper rim (7) of a front side(2) of the extinguishing chamber comprises a projection (18) pointing upward to limit a displacement path of the extinguishing chamber cover (10), and wherein said extinguishing chamber cover (10), has a stop hole (22) so that a head (30) of said fastening screw (5) forms a stop for a wall (21) of the stop hole (22) for horizontal securing of the extinguishing chamber cover (10) 4 The arc extinguishing chamber as claimed in claim 2, wherein said extinguishing chamber cover (10) has a passage hole (23) arranged axially with a stop hole (22) for insertion of a tool to manipulate said fastening screw (5) 5 The arc extinguishing chamber as claimed in claim 2, wherein said extinguishing chamber cover (10) has an insertion opening for insertion of a tool to manipulate said fastening screw (5) 6 The arc extinguishing chamber as claimed in claim 2, wherein said stop hole (22) is a through hole with a constant diameter Arc-extinguishing chamber for low-voltage circuit breakers An arc-extinguishing chamber for low-voltage circuit breakers comprises an extinguishing-chamber housing (1) and an extinguishing-chamber cover (10), which is detachably joined to the extinguishing-chamber housing (1) by means of fastening elements. Opposite a hollow extension (3), the extinguishing-chamber housing (1) has a nose (8) over which a claw-like extension (9) of the extinguishing-chamber cover (10) can grip. A further type of fastening of the extinguishing-chamber cover (10) comprises lateral nose- like webs (14, 15) on the extinguishing-chamber housing (1), and projections (16, 17) on both sides on the extinguishing-chamber cover (10) to grip over the noses (14, 15).

Documents:

01333-cal-1997-abstract.pdf

01333-cal-1997-claims.pdf

01333-cal-1997-correspondence.pdf

01333-cal-1997-description(complete).pdf

01333-cal-1997-drawings.pdf

01333-cal-1997-form-1.pdf

01333-cal-1997-form-2.pdf

01333-cal-1997-form-3.pdf

01333-cal-1997-form-5.pdf

01333-cal-1997-general power of attorney.pdf

01333-cal-1997-other document.pdf

01333-cal-1997-priority document.pdf