EP1302960B1 - Contact arrangement for current limiting circuit breaker - Google Patents

Description

The invention relates to a contact arrangement for current-limiting circuit breakers in the low-voltage range, in particular for current-limiting circuit breakers, according to the preamble of claim 1.

From the publication EP 0314540 B1 is such a contact arrangement for a low-voltage multipole circuit breaker with Isolierstoffgehäuse known having a means incorporated in the housing slide bearing about a fixed transverse axis rotatable switching shaft, wherein the axis is perpendicular to the longitudinal center plane of each pole. Each pole comprises two fixed contacts connected to connecting rails, a rotary contact bridge which extends along the median plane in a play-bearing recording of the switching shaft and having opposing contacts, which interact in closed position with the fixed contacts, and two mounted inside the shift shaft tension springs, the acting on the contact bridge and thus ensure a specified contact pressure of the contact pieces on the fixed contacts, wherein one of the ends of each tension spring cooperates with a driver element of the switching shaft. The two springs are mounted in the receptacle for the contact bridge, with the other end of each spring attached to a fastener of the contact bridge. The two fasteners or driver elements of the two springs are diametrically opposite with respect to an imaginary axis of rotation of the contact bridge or the fixed transverse axis of the switching shaft. This arrangement of the springs ensures a free displacement of the imaginary axis of rotation of the contact bridge with respect to the fixed transverse axis of the switching shaft and simultaneously allows a moment of force for uniform distribution of the contact pressure and elastic positioning of the contact bridge with two translational degrees of freedom, wherein the contact bridge by the self-centering effect of Feathers on the midplane is held in an equilibrium position. The connecting rails with the fixed contacts are loop-shaped, so that when they are traversed by a short-circuit current, they generate a contact bridge against the force of the tension springs in the direction of a repelling back-repelling, electrodynamic forces. In such a contact arrangement, there is the danger that the centrifugal contact caused by short-circuit due to electrodynamic forces damages its stop or recovers too quickly, which is the case can lead to unwanted reignifications of arcing and / or contact welding.

From the publication EP 0560697B1 is a low-voltage circuit breaker with a contact arrangement per pole is known, which is equipped on both sides of the contact bridge, which extends in the median plane of the pole, with two symmetrically arranged pairs of tension springs. The springs are arranged symmetrically on both sides of the axis of rotation of the contact bridge and each have an end mounted on the contact bridge. For braking and optionally holding the electrodynamically repelled from the fixed contacts contact bridge an opposite end of said springs on the ends of a slidably mounted in a notch of the shift shaft, mounted as a transverse axis rod and has the contact bridge symmetrical to its axis of rotation a pair of cams which are designed so that they cooperate in the end portion of the repulsion stroke of the contact bridge with one of the rods, in order to brake the movement of the contact bridge. The rods are mounted displaceably limited in the notches, wherein the diametrically opposed notches extend approximately along the line of action of the associated springs. The springs ensure an elastic positioning of the contact bridge in the recess of the switching shaft and thereby define a fictitious axis of rotation of the contact bridge with respect to the switching shaft. The profile of the opposite to the movable contact pieces arranged cams causes a displacement of the rods in the notch and a pivotal movement of the contact bridge in the direction of the repelling position corresponding continuous tension of the springs with a storage of energy in the springs. The profile of the cams can be designed so that the contact bridge locked in the repelling position; wherein the rotatably mounted switching shaft is actuated by an actuating mechanism of the circuit breaker and the opening stroke of the contact bridge is limited so that the rotation of the switching shaft during the turn-off movement causes a lifting of the rods of the control cams. During the pivoting movement of the contact bridge in the direction of the repelling position, the line of action of each spring shifts and thereby shortens the lever arm, whereby the restoring force moment exerted by the springs on the contact bridge is reduced. A disadvantage of this contact arrangement, the additional requirement of the movable rods to be stored and the insufficient braking effect at high repulsive forces due to the low friction surfaces and Friction coefficient between the steel bars and the copper contact bridge.

In a contact arrangement according to document EP-0978858-A2 engage four responsible for the contact pressure springs between notches on the rotary contact bridge and hinged to the switching shafts tabs that can pivot in such a way that the electrodynamically centrifuged contact bridge can not fall back independently in the closed position. In a contact arrangement according to document WO-9962092-A1 engage four contact springs between four rods for contact pressure. Two of the rods are mounted in shafts of the selector shaft and engage directly on the rotary contact bridge. The other two rods are slidably guided in slots of the shift shaft and engage in hingedly connected to the contact bridge tabs, which also cause the electrodynamically spun contact bridge can not automatically fall back into the closed position. A disadvantage of these two solutions is that on the one hand costs and production-consuming with the switching shaft to be connected tabs are required and that on the other hand by the forced detention of the contact bridge in the spin-coated position equipped with such contact arrangements circuit breaker is not suitable for selective switch arrangements.

EP 0 560 697 discloses the closest prior art.

The object of the invention is therefore in a simplified contact arrangement with improved delay behavior of the electrodynamically spin-coated rotary contact bridge.

Starting from a contact arrangement of the type mentioned, the object is achieved by the characterizing features of the independent claim, while the dependent claims advantageous developments of the invention can be found.

Due to the frictional operative connection between a connecting piece at the first ends of the respective one, designed as a U-shaped double tension spring Zugfederpaares and extensions of resilient elements, the electrodynamically repelled contact bridge is braked or inhibited in their movement. By decelerating the accelerated contact bridge, a total delay is achieved in such a way that a relapse of the contact bridge in the closed position in time before the final opening of the contact arrangement by triggering protective devices is prevented. The inhibiting function can be influenced by constructive design and / or dimensioning of the extensions and / or connecting elements in the sense that it influences the falling back into the closed position more than the transition into the repelling position. When falling back of the electrodynamically repelled contact bridge in the direction of closed position, the above-described non-positive connection between the connectors and the extensions acts inhibiting on the repelled by the end stop and accelerated by the spring force contact bridge. The proposed contact arrangement needed to effect the said braking or inhibiting effect no technologically complex to produce and fastened parts. Circuit breakers equipped with such contact arrangements are advantageously suitable for current-limiting circuit breakers which either switch off themselves when an excessively high current, in particular a short-circuit current, occurs in connection with triggering protective devices or within a switch arrangement with respect to their short-circuit current carrying capacity selectively staggered circuit breakers by another circuit breaker be separated from the short-circuit current.

An advantageous inhibiting behavior for the contact bridge is obtained if by means of constructive design and / or dimensioning of the extensions and / or the connecting pieces between a closed position and repelling position or in the reverse direction to be overcome maximum force is present. An advantageous for achieving an alternating force curve development is the step-like design of the extensions. The step-like design can be further developed into a latching connection at the end of the repulsion movement between the connectors and the extensions, whereby the spin-on contact bridge is held after reaching its repelling position until it is released at the final opening of the contact arrangement by triggering protective devices of the circuit breaker from this detent position.

Advantageously, the tension springs bear with the connecting pieces formed in the contact bridge first notches.

An advantageous development of the invention is that the tension spring pairs are equipped at their second, free ends with the extensions and are preferably mounted by a steel pin in the switching shaft.

An alternative development of the invention is that the extensions are formed on additional springs, which are preferably mounted in a U-shaped configuration together with the second ends of the Zugfederpaare about ösenartige training by steel pins in the shift shaft.

Preferably, the extension pieces grip from the transverse axis as seen under the connectors, but also the reverse arrangement is possible.

To ensure safe movement of the contact bridge this is provided with a slot through which a running in the transverse axis of the shift shaft fixed bearing axis is guided. Due to the polweise composition of the switching shafts from polweise associated switching shaft segments, the contact arrangement is suitable for modular circuit breaker.

Fig. 1:

eine perspektivisch dargestellte Ausführungsform der erfindungsgemäßen Kontaktanordnung in Einschaltstellung;

Fig. 2 bis 3:

die beweglichen Teile der Kontaktanordnung gemäß Fig. 1 in Einschaltstellung, und zwar Fig. 2 von vorn, demgegenüber Fig. 3 von links und Fig. 4 im Schnitt A-A;

Fig. 5 bis 7:

die beweglichen Teile der Kontaktanordnung gemäß Fig. 1 im Verlauf der elektrodynamischen Abstoßung, und zwar Fig. 5 von vorn, demgegenüber Fig. 6 von links und Fig. 7 im Schnitt B-B;

Fig. 8 bis 10:

die beweglichen Teile der Kontaktanordnung gemäß Fig. 1 am Ende der elektrodynamischen Abstoßung, und zwar Fig. 8 von vorn, demgegenüber Fig. 9 von links und Fig. 10 im Schnitt C-C;

Fig. 11 bis 14:

verschiedene Ausführungen von Zugfederpaaren in unterschiedlichen Darstellungen;

Fig. 15, 16:

eine Ausführungsform einer Zusatzfeder in unterschiedlichen Darstellungen.

Further details and advantages of the invention will become apparent from the following, explained with reference to figures embodiment. Show it

Fig. 1:

a perspective illustrated embodiment of the contact arrangement according to the invention in closed position;

2 to 3:

the moving parts of the contact arrangement according to Fig. 1 in closed position, and indeed Fig. 2 from the front, in contrast Fig. 3 from the left and Fig. 4 on average AA;

5 to 7:

the moving parts of the contact arrangement according to Fig. 1 in the course of the electrodynamic repulsion, namely Fig. 5 from the front, in contrast Fig. 6 from the left and Fig. 7 in section BB;

8 to 10:

the moving parts of the contact arrangement according to Fig. 1 at the end of electrodynamic repulsion, and indeed Fig. 8 from the front, in contrast Fig. 9 from the left and Fig. 10 on average CC;

11 to 14:

various designs of tension spring pairs in different representations;

Fig. 15, 16:

an embodiment of an additional spring in different representations.

The contact arrangement 2 according to the invention Fig. 1 is intended for a pole of a multi-pole circuit breaker, not shown. The circuit breaker conventionally comprises an insulating material housing, one actuatable by a drive Switch lock, supply and outgoing connection elements as well as tripping devices for overload and short circuit. In the housing a switching shaft 6 is rotatably mounted about a fixed transverse axis z, wherein the transverse axis z is perpendicular to the median plane xy of the pole. The switching shaft 6 is composed of polweise associated switching shaft segments. A rotary contact bridge 10 extends along the center plane xy in a play-loaded receptacle 12 of the switching shaft 6 and has opposing contact pieces 14, which cooperate in closed position with fixed contacts 16. The contact bridge 10 has a slot 11 (see, eg Fig. 4 ), with which it is mounted on a fixed, in the transverse axis z of the switching shaft 6 extending bearing axis 7. In the receptacle 12 xy two tension springs 18 are arranged on both sides of the contact bridge 10 and the median plane, which apply the required contact force between the contact pieces 14 and the fixed contacts 16.

The tension springs 18 have a first end 19 mounted on the contact bridge 10 and a second end 21 mounted on the control shaft 6. On each side of the contact bridge 10 are the first ends 19 with respect to the axis of rotation of the contact bridge 10 and the second ends 21 of the respective tension springs 18 with respect to the transverse axis z of the shift shaft 6 diametrically opposite. The tension springs 18 are arranged symmetrically with respect to the median plane xy. Two each located on opposite sides of the median plane xy first ends 19 are integrally connected via transverse connecting pieces 20, and two each on opposite sides of the median plane xy located second ends 21 are suspended in transverse steel pins 23. The connecting pieces 20 form with the associated pairs of tension springs 18 U-shaped double tension springs and are frictionally in the first notches 25 of the contact bridge 10. The steel pins 23 are in corresponding second notches 27 of the switching shaft 6. With each of the two fixed contacts 16 is a loop-shaped Connecting rail 24 connected. This loop shape causes the flow of a short-circuit current, the contact bridge 10 by electrodynamic forces against the force of the tension springs 18 of the closed position according to Fig. 1 to 4 in the direction of a repelling position according to Fig. 8 to 10 is pushed back.

The contact arrangement 2 according to the invention further provided with resiliently mounted in the switching shaft 6 elements, which in the embodiment according to Fig. 1 to 10 are identical to the second ends 21 of the tension springs 18 and each with a simple Winding and an adjoining free-running extension 28 are equipped. By the two loop-shaped ends 21 of each two with respect to the median plane xy opposite tension springs 18 each one of the steel pins 23 extends. The two extensions 28 each have a double tension spring to the connector 20 of the other double tension spring and engage under the respective connector 20. In elektrodynamisch effected repulsion the contact bridge 10 according to Fig. 5 to 10 the connecting pieces 20 and the extensions 29 rub against each other with increasing repulsion. This friction only partially destroys the kinetic energy of the contact bridge 10 which has been accelerated by the electrodynamic repulsion, so that its transition from the contact bridge 10 in FIG Fig. 1 to 4 shown switch on the in Fig. 5 to 7 shown transition position to the in Fig. 8 to 10 shown end position with a slight delay takes place. After a short stay of the contact bridge 10 in the end position, this falls back only with considerable delay. The increasingly acting on the contact bridge 10 return force with progressive repulsion movement is essentially determined by the rotation of the spring body of the tension springs 18 to the bearing axis 7 and simultaneously limits the rotation of the spring body. The repelling movement of the contact bridge 10 causes an increase in the distance between the spring ends 19 and 21. After striking the insulating housing of the circuit breaker and a reverse acceleration toward switch-on the contact bridge 10 is further slowed down and falls due to the frictional interaction of the extension pieces 28 with the connecting pieces 20 back with considerable delay. The bearing shaft 7 limits the rotation and also prevents a surface collision of the spring body of the tension springs 18 and allows a relatively soft increase in force with a high energy storage to hit the contact bridge 10th

In FIGS. 11 and 12 is the pair of symmetrically located on both sides of the median plane xy tension springs 18 according to Fig. 1 to 10 shown in detail. The two springs 18 are brought together at their first ends 19 via the connecting piece 20 U-shaped to the double tension spring and have at their loop-shaped wound second ends 21, the extensions 28. The extensions 28 are provided with respect to the longitudinal axis of the tension springs 18 with a turning angle, which is dimensioned in such a way that with increasing electrodynamic repulsion of the contact bridge 10, the power requirement from the electrodynamic acceleration and the fallback acceleration to overcome the force between the connecting piece 20 of a tension spring pair and the extensions 28 of the other tension spring pair increases.

In FIGS. 13 and 14 a slightly different designed pair of tension springs 18 is shown. This tension spring pair, which is likewise formed as a U-shaped double tension spring, differs from the tension spring pair described above essentially by the configuration of its extensions 29 provided with a step 33 and by the arcuate design of its second ends 22. The steps 33 of the step-like section extending parallel to the median plane xy Extensions 29 of a pair of Zugfederpaares can cause two things in the interaction of the connecting piece 20 of the other Zugfederpaares in the course of electrodynamic repulsion of the contact bridge 10: First, by the design of the turn angle and the gradation 33, the initially increasing counterforce at the end of the repulsion movement by the gradation 33rd be noticeably attenuated, so that due to the declining braking effect a slightly extended residence time in the end region of the repulsion occurs. On the other hand, as in the in Fig. 13 illustrated case, the gradation 33 are dimensioned such that in the end position of the repelled contact bridge 10, the connecting piece 20 of each spring pair with the extensions 29 of the other pair of springs in the region of gradation 33 engages a latching connection, the only conscious return of the contact bridge 10 this end position permitted. Each Zugfederpaar superimposed under the influence of the tensile force of the tension springs 18 with the second ends 22 arcuately on each one of in Fig. 1 illustrated steel pins 23rd

In FIGS. 15 and 16 It is shown that, as an alternative to the embodiments described above, two extensions 28 are each part of an element other than. Each designed as a U-shaped torsion spring auxiliary spring 30 is to be stored with its winding outer legs on one of the steel pins 23 between the second ends 21 of the tension springs 18 of the respective one Zugfederpaares. For this purpose, the outer legs are each equipped with an extension 28. In this alternative, of course, eliminates the extensions in the tension springs 18. The extended central portion 31 of the auxiliary spring 30 is supported in the switching shaft 6 in such a way that the extensions 28 rests with spring force against the connecting piece 20 of the other pair of tension springs.

The present invention is not limited to the embodiments described above, but also includes all the same in the context of the invention embodiments. The invention can be carried out, for example, in such a way that the extensions 28 or 29 engage with a component of the spring force directed toward the transverse axis z via the associated connection pieces 20. Also, the tension springs 18 can be replaced within the scope of the inventive concept by compression springs or torsion springs, which are arranged in a suitable manner between the contact bridge 10 and the switching shaft 6.

Claims (14)

1. A contact assembly for an at least single-pole, current-limiting circuit breaker in the low-voltage range with a housing made of insulating material, including

   - a switching shaft (6) mounted pivotingly about a fixed transverse axis (z) in the insulating housing, the transverse axis (z) running perpendicular to the central plane (xy) of the pole,

   - a rotary contact bridge (10), which extends along the central plane (xy) in a clearance receptacle (12) of the switching shaft (6) and has diametrically opposed contact pieces (14), which cooperate with fixed contact (16) in the switched-on position,

   - contact force tension springs (18) located inside the switching shaft (6), each having a first end (19) positioned at the contact bridge (10) and a second end (21; 22) positioned at the switching shaft (6), the first ends (19) oppose one another with respect to the rotation axis of the contact bridge (10) and the second ends (21; 22) oppose one another with respect to the transverse axis (z), and

   - two connection bars (24), each connected with one of the fixed contacts (16), which, when very high currents flow, generate electrodynamic forces in cooperation with the contact bridge (10), opposite to the forces exerted by the tension springs (18), pushing back the contact bridge (10) toward a repelled position,

   the tension springs (18) being arranged in pairs symmetrically to either side of the central plane (xy) and said pairs of tension springs (18) in turn being positioned symmetrically with respect to the rotation axis of the contact bridge (10),
   characterized in that
   the first ends (19) of any one of said pairs of tension springs (18) are interconnected as a single unit through transversely running connecting pieces (20) and that elements (18; 30) mounted elastically in the switching shaft (6) are equipped with extensions (28; 29), which extend to the connecting pieces (20) and are so configured and positioned that additional forces to be overcome occur between them and the connecting pieces (20) during transition of the contact bridge (10) from the switched-on position to the repelled position and vice versa.
2. The contact assembly according to one of the foregoing claims, characterized in that a maximum force must be overcome by the contract bridge (10) between the switched-on setting and the repelled setting, and vice versa.
3. The contact assembly according to the foregoing claim, characterized in that the extensions (29) have a stepped configuration.
4. The contact assembly according to the foregoing claim, characterized in that, after reaching the repelled position, the connecting pieces (20) enter into a force-dependent, releasable snap-lock connection with the associated extensions (29).
5. The contact assembly according to one of the foregoing claims, characterized in that the connecting pieces (20) are mounted in first notches (25) formed in the contact bridge (10).
6. The contact assembly according to one of Claims 1 through 5, characterized in that the extensions (28; 29), which extend to the connecting piece (20) of the other respective pair of tension springs (18), are connected to the second ends (21; 22) of said pairs of tension springs (18),
7. The contact assembly according to Claim 6, characterized in that the second ends (21) of said pairs of tension springs (18) are each mounted wound in the form of a loop about a steel rod (23), which in turn is mounted in second notches (27) of the switching shaft (6).
8. The contact assembly according to Claim 6, characterized in that the second ends (22) are each mounted in a bow on one steel rod (23), which in turn is mounted in second notches (27) of the switching shaft (6).
9. The contact assembly according to one of Claims 1 through 5, characterized in that the extensions (28) are formed on supplementary springs (30).
10. The contact assembly according to the foregoing claims, characterized in that the second ends (21; 22) of said pairs of tension springs (18) each wound around or each bent on a steel rod (23), which in turn is mounted in second notches (27) of the switching shaft (6), and that one each of the supplementary springs (30) configured as U-shaped torsion spring is mounted wound the steel rod (23) in a loop at its outer legs, the outer legs each being equipped with an extension (28) and the also extended middle portion (31) of the supplementary springs (30) is supported in the switching shaft (6).
11. The contact assembly according to one of Claims 1 through 10, characterized in that the extensions (28; 29) engage under the connecting pieces (20) with a spring force component oriented away from the transverse axis (z).
12. The contact assembly according to one of Claims 1 through 10, characterized in that the extensions (28; 29) engage above the connecting pieces (20) with a spring force component oriented toward the transverse axis (z).
13. The contact assembly according to one of the foregoing claims, characterized in that the contact bridge (10) is mounted with a longitudinal hole (11) on a fixed pivot axis (7) running in the longitudinal axis (z) of the switching shaft (6).
14. The contact assembly according to one of the foregoing claims, characterized in that the switching shaft (6) consists of switching shaft segments assigned to poles.

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