Switching device with improved tripping action in the event of a short circuit

Abstract

A switching device having an arc quenching chamber, a fixed contact element and a movable contact element movable in a sliding contact between untripped and tripped positions within the chamber. A plurality of centering structures are arranged on the walls of the arc quenching chamber for centered guiding movement of the movable contact element as it moves from its untripped position to its tripped position. The centering structures may be fabricated unitarily with the chamber walls, as of plastic, and are arranged in parallel and spaced apart relation to one another.

Claims

1. A switching device, comprising: an arc quenching chamber having housing walls; a sliding contact disposed entirely within the arc quenching chamber; a movable contact element arranged in the sliding contact for guiding movement of the movable contact element from an untripped position to a tripped position; and a plurality of centering structures arranged on the housing walls of the arc quenching chamber for guiding movement of the movable contact element from the untripped position to the tripped position.

2. The switching device of claim 1, wherein the centering structures are unitarily fabricated as a single piece with the housing walls of the arc quenching chamber.

3. The switching device of claim 1, wherein the centering structures are formed of plastic.

4. The switching device of claim 1, wherein the plural centering structures are arranged in parallel and spaced apart relation to one another.

5. The switching device of claim 1, wherein the plural centering structures comprise a first set of centering structures and a second set of centering structures, and wherein the first set of centering structures is arranged on a first housing wall of the arc quenching chamber and the second set of centering structures is arranged on a second housing wall of the arc quenching chamber that is opposite the first housing wall so that the movable contact element is positioned between the first and second sets of centering structures.

6. The switching device of claim 1, wherein the centering structures are arranged on sides of and adjacent to the sliding contact.

7. The switching device of claim 1, wherein the switching device comprises a power switch.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a cross-sectional view of a switching device in accordance with the invention including an arc quenching chamber and a sliding contact in which a movable contact element is guided;

(3) FIG. 2 is an enlarged sectional view of a section of the switching device of FIG. 1 depicting a sliding contact, a movable contact element and centering structures in accordance with the invention;

(4) FIG. 3 is an enlarged cross-sectional side view of the centering structures and movable contact element shown in FIG. 2;

(5) FIG. 4 is a cross-sectional view of the centering structures of the invention with the movable contact element depicted in the on or untripped position; and

(6) FIG. 5 is a cross-sectional view similar to FIG. 4 of the centering structures of the invention with the movable contact element depicted in the tripped state during a short circuit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) FIG. 1 shows a cross-sectional view of a switching device, in particular of a power switch with an arc quenching chamber 1, constructed in accordance with the invention and in which a sliding contact 2 is arranged and a movable contact element 3 is guided for movement. Arranged on both the left and right sides of, and next to, the movable contact element 3 are arc quenching baffle packages 4 each formed of plural arc quenching baffles disposed in parallel relation above one another. Centering structures 7 of the invention are provided on a housing wall 5 of arc quenching chamber 1 in the region of movable contact element 3.

(8) The centering structures 7 are preferably fabricated as a single piece with housing wall 5 of the arc quenching chamber, which is to say that the centering structures 7 are not formed as an additional part on the housing wall 5 but, rather, are injection-molded together with the housing wall 5 in one process step. The centering structures 7 are accordingly preferably formed of plastic. The centering structures 7 are moreover preferably arranged on housing wall 5 of the arc quenching chamber 1 parallel to one another and at a distance or spacing from one another.

(9) In preferred embodiments of the invention, a second set of centering structures 7 is additionally arranged on a second housing wall of the arc quenching chamber 1 located opposite to the first set of centering structures 7, so that the movable contact element 3 is positioned between the two sets of centering structures.

(10) The centering structures 7 are preferably arranged to the side next to the sliding contact 2, i.e., to the right and to the left of the sliding contact 2.

(11) Depicted in FIG. 2 is the region around sliding contact 2, i.e., the region to the left and to the right of sliding contact 2. The positioning of the centering structures 7, which are arranged to the left and to the right of sliding contact 2, can be seen in FIG. 2.

(12) FIG. 3 shows the two regions of the centering structures 7 as a cross-section from the side. When tripped, the movable contact element 3 is first guidedly accepted by the centering structures 7 and then strikes against the impact dome 8.

(13) The position of the movable contact element when in the switched-on (i.e. untripped) state can be seen in FIG. 4. FIG. 5 depicts the position of movable contact element 3 in the tripped state during a short circuit event.

(14) As a result of the centering structures of the invention, the bridge always meets the impact dome symmetrically, and jamming is avoided. Moreover, the centering structures assure that the bridge is centrally aligned during its movement and, when in its off position, the bridge is maintained at an adequate distance from the chamber walls, thus preventing melting of structures within the switching chamber.