Switch

Details Switch Switch

1984-07-02

1987-02-10

Macon, Robert S.

Electricity: circuit makers and breakers

Liquid contact

Time delay

200147R, H01H 3308

Patent

active

046424296

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to switches for interrupting or allowing an electric current to flow, and more particularly to arc extinguishing mechanisms for such switches.


TECHNICAL BACKGROUND

Switches to which the present invention is applicable include electromagnetic contactors and wiring interrupters.
First, one example of a conventional electromagnetic contactor will be described with reference to FIG. 1. In FIG. 1, (1) is a mount bed molded of a plastic material, (2) is a stationary iron core having silicon steel laminations disposed on the mount bed, (3) is a movable core disposed in a facing-relationship with the stationary core (2) and made of silicon stel laminations, (4) is an operating coil for providing a driving force which attracts the movable core (3) to the stationary core (2) against the force of a trip spring (not shown), and (5) is a cross bar made of a plastic material and having a rectangular window, the bottom end of the crossbar (5) has attached thereto the movable core (3). (6) is a movable contact inserted within the rectangular window of the cross bar (5) and held under pressure by a compression spring (7), (6A) is a movable contact element disposed on the movable contact, (8) is a stationary contact facingly disposed with respect to the movable contact (6) for conducting a current (8A) is a stationary contact element disposed on the stationary contact (8), and (8C) is a terminal portion for the stationary contact (8).
Also, (9) is a terminal screw for connecting the electromagnetic contactor main body to an external circuit, (10) is a base for mounting the stationary contact (8), and (11)is a cover for covering the upper portion of the electromagnetic contactor.
Since the conventional electromagnetic contactor has the above-described structure, when the operating coil (4) is de-energized, an unillustrated trip spring causes the movable core (3) to separate from the stationary core (2) and the cross bar (5) occupies the position shown in FIG. 1, and the movable contact element (6A) and the stationary contact element (8A) are separated to generate an electric arc (12), the arc (12) being extinguished at the zero current point to interrupt the electric current.
In the conventional electromagnetic contactor, as shown in FIG. 2, the arc (12) is subjected to a driving force F.sub.2 due to a magnetic field formed by a current I flowing through the movable contact (6) and a driving force F.sub.1 due to a magnetic field formed by a current I flowing through the stationary contact (8). Since the driving forces F.sub.1 and F.sub.2 are substantially equal in intensity and opposite in direction, the arc (12) stays on the movable contact element (6A) and the stationary contact element (8A). Thus, since the arc (12) is not forcedly driven, the legs of the arc do not move outside of the contact elements and a thereby resulting in the disadvantage that a large contact element wear occurs;


DISCLOSURE OF THE INVENTION

With the above points in view, the present invention has as its main object to provide an arc extinguishing mechanism for promoting the arc extinction by a quick transfer of the arc, thereby to reduce the contact element wear and to improve the interrupting capability, and the invention is characterized by a stationary contact element jointed on a stationary contact, a movable contact element jointed on a movable contact and disposed in a facing relationship with the stationary contact element, a first metallic arc extinguishing plate comprised of a U-shaped vertical wall, the wall being disposed to surround the stationary contact element with an open side faced toward a tip of the stationary contact, and a second metallic plate disposed in parallel to and at a side of the first metallic arc extinguishing plate remote from each of the contact elements, the first and second metallic arc extinguishing plates being positioned with a predetermined gap therebetween and from the stationary contact.
According to the present invention, an advantage of significantly improving

REFERENCES:
patent: 4258345 (1981-03-01), Malick
patent: 4266210 (1981-05-01), Mrenna et al.

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