DE10252741B3 - Contact system for low voltage power switch, has switch piece floating bearing provided by bearing pin located in elongate opening for rotation of switch piece upon abutting stop provided by switch housing - Google Patents

Abstract

The contact system has a switch piece (10) for each pole of the low voltage (LV) switch, supported in the switch housing via a floating bearing and acted on by a contact spring. The switch housing has a first stop cooperating with a first switch piece section at the end of the opening movement and a second stop cooperating with a second section of the switch piece, offset angularly from the first stop. A bearing pin (15) of the switch piece is supported within an elongate opening (27) for providing the floating bearing, the longitudinal direction of the opening extending parallel to the acting direction of the contact spring and allowing a rotation of the switch piece after abutting the second stop about a rotation point provided by the latter.

Description

The invention relates to a contact system for one Low voltage switch, in particular for a circuit breaker.

From the DE 39 01 852 A1 is a tilt-point-mounted contact system for a current-limiting circuit breaker known with a rotatable, movable first contact arm in the event of a short circuit. This first contact arm is acted upon by a compression spring (contact force spring) supported in the housing via a pressure bolt. At the end of the opening movement, after an unstable position in the upper part of the housing has been exceeded, the contact arm runs against a limiting element in order to reach a safe OFF position in this second tilting position. The kinetic energy is primarily absorbed by the limiting element acting as a stop, as a result of which the movement comes to a standstill.

In the US 5 258 733 A describes a contact system in which three one-armed contact arms are acted upon by contact force springs. For the two external contacts there are two limiting elements in the upper part of the housing and for the middle contact there is a limiting element which serves as stops for the contact arm at the end of the opening movement. The housing is especially reinforced to absorb and absorb the kinetic energy when opening the contacts. The limiting elements are made of shock-absorbing material.

The disadvantage of such arrangements is the special effort in reinforcing the housing. The Effort needs - too with regard to the impact-loaded parts of the contact system - are increased, if more powerful Contact systems are to be developed. The load on the selector shaft and their storage at circuit breakers increases with switching capacity particularly critical.

A generic contact system is from the DE 3411275 C2 known. There is a second stop for the contact arm. This stop has a function in connection with an enlarged bearing opening for a pivot pin provided as the axis of rotation of the contact arm. The enlarged bearing opening allows, in particular in the last phase of the closing operation of the contact, a change in the position of the contact arm such that the movable contact carries out a grinding movement on the fixed contact, thereby preventing the burn-in or welding of the contacts. At the in the DE 3411275 C2 given arrangement, it is not possible to absorb kinetic energy from the opening movement or to dissipate it into the housing.

It is therefore the object of the invention to specify an arrangement in which the impact load by the Impact energy at the load points in the contact system and in its housing parts is reduced.

The object is achieved by the characterizing features of the independent claim solved during the dependent claims advantageous developments of the invention can be found.

In a nutshell, the invention consists in that a second stop is formed in the switch housing of the contact system and is assigned to a second section of the switching element for the opening of the second section;
With respect to the opening movement, both stops have such an angular position with respect to one another that the second section meets the second stop after a shorter angular path than the first section;
the floating mounting is carried out in such a way that a bearing pin is arranged on the switching piece, which has play and is at least immovably mounted in an elongated hole during dynamic opening;
the longitudinal extent of the elongated hole is parallel or almost parallel to the direction of action of the contact force spring;
the length of the elongated hole permits rotation of the contact piece about a pivot point lying in the second stop and
During the rotation, the contact force spring does spring work (compression or dilation work, depending on the principle of action of the contact force spring).

So it's a second stop provided that, so to speak, upstream of a single stop is and during the movement of the contact through the electrodynamic opening force after hitting the first stop from the contact force spring kinetic energy are absorbed.

This means that further dissipation and absorption points in the switch housing that lead to a Reducing the impact load on the stress points, in particular that lead the shift shaft.

Since the contact piece is floating, causes the excess energy still present Further rotation of the contact around the pivot point of the hit. The switching piece performs one translational movement in the elongated hole, combined with the compression the compression spring, including the selector shaft and its bearing deformation energy take up. Then it comes to touch and to hit the other arm section on the other stop in the housing or in a housing part, a last remnant of kinetic energy is consumed.

At the end of the opening movement, both stops are reached one after the other. The additional Lich introduced stop is preferably in relation to the angular path before a commonly used single stop or as in the US 5,258,733 used double stop.

• – Kontaktsystem wirkverbunden mit einem Schaltschloss, womit ein Unterbrechen des Stromflusses erfolgt, so dass auch nach Wieder-Schließen des Kontakts infolge der sinkenden Stromstärke kein erneuter Öffnungsvorgang eingeleitet wird.
• – Kontaktsystem mit einem Kippsprungwerk, wobei das Schaltstück kipp-punkt-gelagert ist. Die Kontaktkrafffeder greift derart am Schaltstück an, dass sie infolge der durch hohe Überströme erzeugten elektrodynamischen Kraft den Kippsprung vermittelt; sie stellt beim Überschreiten des Kipp-Punkts die Öffnungsstellung sicher. Die vorzugsweise druckbeanspruchte Kontaktkrafffeder greift zwischen Gehäuse und Schaltstück an, wobei sich die Drehachse des Schaltstücks bei einer instabilen Zwischenstellung des Schaltstücks in gerader Linie mit der Wirkrichtung der Kontaktkraftfeder befindet.

Further configurations are proposed:

• - Contact system operatively connected to a key switch, which interrupts the flow of current, so that no opening operation is initiated even after the contact is closed again due to the falling current.
• - Contact system with a tilting spring mechanism, the switching element being tilt-point-mounted. The contact force spring acts on the contact piece in such a way that it conveys the tipping jump as a result of the electrodynamic force generated by high overcurrents; it ensures the opening position when the tipping point is exceeded. The preferably pressure-loaded contact force spring engages between the housing and the contact piece, the axis of rotation of the contact piece being in a straight line with the direction of action of the contact force spring when the contact piece is unstable.

The annihilation of kinetic energy of the contact piece takes place in the proposed arrangement in a variety of Parts (switching piece self; Contact force spring, spring bearing, both stops, selector shaft and bearings of the control shaft), bearing tolerances also play a role play because these are inherent and over the life of the Bring a rest of the vagueness brought by the switch constructively cannot be taken into account in advance.

The two arm sections should if possible not punctual be trained. The areas of the two arm sections can however be chosen small. The dimension of the contact (especially its thickness) does not have to be changed or be adjusted; it can in the invention on widening and extending the surfaces of the two stops and the two arm sections can be dispensed with.

The material selection for the stop should preferably be aimed specifically at impact-resistant plastics suitable, commercially available materials are available to the person skilled in the art. The housing can preferably be formed from several chambers, one upper chamber the first stop and a lower chamber the second Stop contains. The chambers are designed so that they with the other parts of the contact system and the housing a modularity form that to simplify manufacture and assembly contribute and extensions to contact system with other service areas allow in a simple way.

The contact piece can be one-armed or two-armed be trained. In each case one of these two training courses can the point of application and the direction of application of the contact force spring for the special case. The contact force spring can be used as a or act as a compression spring.

Preferably each of the two Switching piece portions be arranged on the contact bearing arm of the contact piece. In this case becomes a one-armed contact used.

The contact piece can also have two arms be, then on each arm of the contact piece a contact piece section is arranged. Here, preferably the contact pad contact arm carrying arm longer be formed as the non-contact arm of the contact piece.

More details and advantages The invention will become apparent from the following, based on figures explained Embodiment. It show in detail

1 : the position of the contact system (in section) when hitting the second stop during the opening movement,

2 : the position of the contact system when it hits the first stop and 3 : an exploded view of the contact arrangement.

In 1 is the contact system of a low-voltage circuit breaker with a two-armed switching element with a tilt-point bearing when it hits the second stop 34 shown during the opening movement. In 2 is hitting the first stop 24 and the remaining contact on the second stop 34 to recognize.

The 3 shows three contact systems arranged in parallel, which are connected via the selector shaft. This is a preferred embodiment in which the contact piece is mounted eccentrically in or on the selector shaft. As an alternative, it is claimed, but not shown in the figures, that the contact piece is mounted via an elongated hole in the housing or in a housing part. The dynamic relationships addressed in the invention are the same in both arrangements. The essential point is that the elongated hole remains stationary during the opening movement of the contact.

The contact's current path is not shown. The current path is opened and closed by the simply interrupting contact (as a rotary contact). The switching piece 10 is rotatable about the axis of rotation between its closed and open positions. The contact piece has a longer 18 and a shorter arm 20 , The longer arm 18 carries a contact pad, not shown, for contacting the fixed contact. On the shorter arm 20 is a section 32 (a stop lug) formed with a stop 34 corresponds in the housing.

When the switch is in the on position, the nominal current flows through the current path, whereby it enters through a busbar, flows through the contact, the contact piece and the fixed contact and leaves the housing via a second busbar with connection lug. By rotation B1 of the contact 10 the contact pair is separated clockwise. The busbars are designed as a current loop in order to achieve a quick switch opening with the electrodynamic effect. With reference numbers 70 an extinguishing chamber is indicated.

The actuation and triggering of the Switch drives are as usual executed. However, neither is shown here.

The storage of the contact piece 10 takes place in an elongated hole 27 floating over a bearing pin 15 , which has coaxially directed to the side of the contact piece. The bearing pin forms the axis of rotation during the opening movement. Bearing pin and selector shaft are parallel to each other. The contact piece according to the 1 is tipped point. Depending on the rotational position with respect to the dead center of the bearing, the contact piece jumps into the open or closed position, supported by the force of the contact force spring. Holding and guiding the contact 10 happens through the contact force spring 40 , The contact force spring 40 is with one end on a counter bearing 52 in the housing 100 fixed. The contact force spring loads via a spring plunger 42 the switching piece 10 at a depository 17 towards the bearing point in the housing. The bearing point is a semicircular groove 17 educated.

In known arrangements with a conventional design on such circuit breakers, the contact piece section strikes 22 on the long lever arm 18 at the end of the opening movement to only one stop, which in the figures is approximately the stop with reference numerals 24 equivalent. The impact is associated with the special dynamic loading of the switch elements (in particular the bearing and housing parts).

According to the invention are in the lower part of the housing 100 - here in a partial housing chamber 104 - a second stop 34 and on the short lever arm 20 an assigned section 32 educated. The section 32 strikes after opening the contact system before any other contact of the switching arm with housing parts at the second stop 34 on. The touch of the first section 22 with the first stop 24 takes place later. Both sections are preferably flat and not punctiform. In the embodiment shown in the drawing, the contact surface is the first section 22 and the associated surface of the stop 24 larger than the contact surface and stop surface 34 of the second section 32 ,

In the position of the contact according to 2 there is the greatest stress on the parts of the housing and the contact system. At the end of the opening process - i.e. in its rest position - the contact system has the position as in again 1 , The contact piece has been moved a short way back by the compression spring. In this end position, not shown, the second arm section lies against the second stop, but the first arm section no longer lies against the first stop.

The floating mounting of the contact and the longitudinal extension of the elongated hole 27 in the contact piece is such that the longitudinal extension of the elongated hole lies parallel to the main component of the movement B2 of the contact piece, while the fulcrum is in the stop that met first in time 34 located. The contact piece can move translationally in the slot, the contact force spring 40 undergoes further compression (and thus spring work).

With reference numbers 36 is a first mechanical load zone of the contact, the selector shaft and its bearing marked. The mechanical load occurs due to the rotary movement B2 by the second stop 34 given pivot point. The rotation B2 is unobstructed until the bearing pin 15 at the end 36 ' of the slot if the length of the slot is selected to be short. During the rotation, the contact force spring 40 and their counter camp 52 loaded, whereby kinetic energy is consumed in the contact force spring and in the bearing.

After hitting the end of the elongated hole, the selector shaft and its bearing are loaded; Energy is dissipated in the control shaft and in its bearing. The resulting second mechanical load zone is indicated by the reference symbol 36 ' characterized.

The 3 shows three contact systems, with bearing housing 52 for the contact force spring 40 and the selector shaft 60 , Above the contact piece 10 is the bearing pin 15 recognizable, the two ends of which form the pivot. The contact piece is eccentric to the shift shaft axis in the shift shaft via the bearing pin 60 stored. The bearing in the middle block 64 consists of an elongated hole not visible in the figure.

Claims (12)

Contact system for a low-voltage switch, in particular circuit breakers, with electrodynamically induced opening force, with one for each pole in a switch housing ( 100 ) floating contact piece ( 10 ) with a contact pad and a fixed contact with the associated fixed contact pad, with a contact force spring acting on the contact piece ( 40 ), with one in the switch housing ( 100 ) arranged first stop ( 24 ) for the impact of a first switching section ( 22 ) at the end of the opening movement (B1) of the switching element ( 10 ), in the switch housing ( 100 ) of the contact system a second stop ( 34 ) is formed, which has a second section ( 32 ) of the contact piece ( 10 ) to serve the second section ( 32 ) is assigned, the second stop ( 34 ) compared to the first stop ( 24 ) has such an angular position that the second section ( 32 ) after a shorter angular path in the opening movement to the second stop ( 34 ) hits as the first section ( 22 ) at the first stop ( 24 ); that the floating mounting is carried out in such a way that the 10 ) a bearing pin ( 15 ) is arranged, which has play and at least during dynamic opening cannot be displaced in an elongated hole ( 27 ) is mounted, characterized in that - the longitudinal extension of the elongated hole ( 27 ) parallel or almost parallel to the direction of action of the contact force spring ( 40 ), the longitudinal extension of the elongated hole ( 27 ) a rotation (B2) of the contact ( 10 ) after hitting the second stop ( 34 ) by one in the second stop ( 34 ) allows the pivot point and - that during the rotation (B2) the contact force spring ( 40 ) Feather work. Contact system according to one of the preceding claims, characterized in that the length of the elongated hole ( 27 ) is dimensioned such that during the rotation (B2) of the switching element ( 10 ) after hitting the second stop ( 34 ) the bearing pin ( 15 ) before the first section hits ( 22 ) at the first stop ( 24 ) the end ( 36 ' ) of the elongated hole ( 27 ) reached, with the selector shaft and its lean deformation energy. Contact system according to one of claims 1 or 2, characterized in that the bearing pin ( 15 ) on both sides of the contact in a slot ( 27 ) takes effect. Contact system according to one of the preceding claims, characterized in that the elongated hole bearing ( 27 ) is arranged in the housing or in a housing part. Contact system according to one of claims 1, 2 or 3, characterized in that the elongated hole bearing ( 27 ) is arranged eccentrically on the switching shaft of the contact system. Contact system according to one of the preceding claims, characterized in that both contact piece sections ( 22 . 32 ) on the contact arm supporting the contact pad ( 10 ) are arranged. Contact system according to one of the preceding claims, characterized in that the switching piece ( 10 ) designed with two arms and that on each arm of the contact piece ( 10 ) a contact piece section ( 22 . 32 ) is arranged. Contact system according to claim 7, characterized in that the arm supporting the contact support ( 18 ) of the contact piece ( 10 ) is longer; than the non-contact arm ( 20 ) of the contact piece ( 10 ). Contact system according to one of the preceding claims, characterized in that at least one stop ( 24 . 34 ) in one housing subchamber ( 102 . 104 ) is made of impact-resistant plastic. Contact system according to one of the preceding claims, characterized in that the point of application of the contact force spring ( 40 ) as a recess ( 17 ) in the contact piece ( 10 ) is trained. Contact system according to one of the preceding claims, characterized characterized in that the contact system is operatively connected to a key switch is. Contact system according to one of the preceding claims, characterized in that the switching piece ( 10 ) is tilt-point mounted and the contact force spring ( 40 ) on the switching piece ( 10 ) attacks that it mediates a jump.