JP3033269B2 - Bridge contact of electromagnetic contactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a bridging contact incorporated in an electromagnetic contactor.

[0002]

2. Description of the Related Art FIG. 4 shows the structure of an electromagnetic contactor conventionally used and a bridging contact incorporated in the electromagnetic contactor. In the figure, 1 is a case of an electromagnetic contactor, 2 is a fixed iron core 2a, a movable iron core 2b, and an excitation coil 2c.
An electromagnet for driving a contact, comprising: a movable core 2b;
4 is a contact support, and 4 is a return spring of the electromagnet 2,
5 is a pair of left and right fixed contacts mounted on the upper surface of the case 1 and 5a is a fixed contact, 6 is mounted on the upper end of the contact support 3 via a movable shaft 7, a contact spring 8, a leaf spring 9, and the like. Bridging contacts. Here, a bridging contact 6 is formed on a box-shaped reinforcing support frame 10 made of iron (magnetic metal) by brazing opposite ends of the support frame 10 with the fixed contacts 5a at both ends on the bottom side. And a bridging conductor 12 made of copper or a copper alloy, which is overlapped on the bottom surface of the support frame 10 so as to extend between the movable contacts 11. In such a configuration, the bridging conductor 12 is responsible for the passage of current, the iron support 10 mechanically reinforces the bridging contact 6, and the magnetic force of the arc generated between the fixed contact and the movable contact when the current is interrupted. It works to increase the driving force.

FIG. 5 shows the principle of magnetic drive of an arc generated at the time of current interruption in the above-described configuration. In the figure, i indicates a current, and φ indicates the direction of a magnetic flux of a magnetic field generated by the current i. As is apparent from this figure, the arc generated between the fixed contact 5a and the movable contact 11 is driven by the action of the magnetic driving force indicated by the arrow F so as to extend toward the outside of the contact, and the arc is extinguished. Reach.

[0004]

However, the above-mentioned conventional bridging contact structure has the following disadvantages. That is, (1) When a short circuit occurs in a circuit, a short-circuit current flows through the electromagnetic contactor until the circuit breaker, fuse, or the like interrupts the current. In this case, in the conventional contact structure, with respect to the magnetic field generated around the current flowing through the bridging conductor 12, as shown in FIG. Although the magnetic flux passes through in a concentrated manner, the lower magnetic flux is distributed in a space between the fixed contact 5a. On the other hand, the magnetic flux in the same direction as described above passes through the space between the fixed contact 5a and the movable contact 11 by the current flowing through the fixed contact 5 in the direction of the arrow. As a result, the magnetic flux density in the space between the fixed contact and the movable contact increases, and an electromagnetic repulsion is generated between the contacts. As a result, the bridging contact 6 rises above the fixed contact 5 and an arc is generated between the contacts. In addition, the surface of the contacts may be melted by the arc heat, and the contacts may be welded to each other when the contacts are closed next time. Further, even if welding does not occur, the surface of the contact is significantly damaged, and the life of the contact is shortened.

[0005] (2) When the number of times of switching is increased and the contact is worn, when the contact is closed, the fixed contact 5a abuts on the corner of the bridging conductor 12, and the contacts do not normally contact with each other. Decreases capacity and current carrying performance. (3) Each time the contact is opened, the contact support 3 (FIG. 4A)
(See FIG. 3) collides with the conductor 12 of the bridging contact 6, so that the bridging conductor 12 is quickly worn away and adversely affects the current-carrying performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to solve the above-mentioned conventional disadvantages, to reduce the electromagnetic repulsion between fixed and movable contacts during energization, and to reduce the electromagnetic repulsion during current interruption. It is an object of the present invention to provide a bridging contact of an electromagnetic contactor which effectively applies a magnetic driving force to an arc and suppresses premature wear of the contact to extend its life.

[0007]

In order to solve the above-mentioned problems, a bridging contact of the present invention mounts a bridging conductor on a bottom plate of a support frame and has at least both ends along a longitudinal direction of the bridging conductor. Extruded steps are formed at the ends of the bridging conductor.
The convex step is fitted into a similar hole opened in the bottom plate of the support frame to expose its end face to the back side of the support frame, and the convex step is formed on the end face of the convex step. The movable contact is formed by brazing.

Further, in the above structure, arc horns projecting toward the movable contact are provided at both ends of the support frame.

[0009]

According to the above construction, the magnetic field generated around the current flowing through the bridge conductor with the contacts closed is concentrated in the support frame of the magnetic material. As the magnetic flux density in the space decreases, the electromagnetic repulsion that acts to separate the contacts decreases. As a result, the floating of the contacts due to the overcurrent at the time of short circuit is suppressed, and the welding of the contacts can be prevented well. In addition, since the protruding step of the bridging contact extends across both ends of the bridging conductor across the movable contact brazed here, particularly the protruding step of the bridging conductor and the moving contact The magnetic field generated by the current flowing in the portion between the magnetic contact frame and the surrounding magnetic support frame has an elliptical loop path through which the magnetic flux passes.As a result, the current flowing through the movable contact receives a magnetic driving force. The current distribution is concentrated on both ends of the bridge conductor. Therefore, the point of the arc generated between the fixed contact and the fixed contact at the time of release of the contact rapidly moves toward both ends of the bridging contact, and further shifts to an arc horn provided at both ends of the support frame. Thus, high current interruption performance can be ensured while minimizing wear due to the arc of the contact.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In the figures, parts corresponding to FIGS. 4 and 5 are denoted by the same reference numerals. First, in FIG. 1, a supporting frame 10 of a bridging contact 6 is an iron frame having a U-shaped cross section, and a bridging conductor 12 made of copper or a copper alloy is brazed on a bottom plate thereof. Here, the bridging conductor 12 has a strip-shaped convex step portion 1 protruding to the lower surface over substantially the entire length region along the longitudinal direction.
2a is extruded and the convex step 12
a is fitted into a hole having a similar shape to the cross-sectional shape of the convex step portion opened in the bottom plate of the support frame 10 and its end face is exposed on the lower surface side of the bottom plate, and the movable contact 11 is provided on the end face of this convex step portion. Be brazed. Further, movable contacts 11 are provided at both ends of the support frame 10.
An arc horn 10a projecting toward the outer edge of the horn is cut and raised.

With this configuration, as shown in FIGS. 3A to 3C, in the energized state with the contacts closed, the magnetic flux φ generated by the current i flowing through the bridging conductor 12 is applied to the lower surface side of the bridging conductor 12. The magnetic flux density in the space between the fixed contact 5a and the movable contact 11 is lower than that in FIG. As a result, the bridging contact 6
The electromagnetic repulsive force acting between the contact and the fixed contact 5 is weakened, so that even when a short-circuit current flows, unnecessary lifting of the bridging contact 6 is suppressed.

In addition, the current flows around the current flowing from the end face of the convex step portion 12a of the bridging contact 12 toward the movable contact 11 in the energized state (flows so as to penetrate the paper surface in FIG. 3C). The magnetic flux path of the magnetic field forms an elliptical loop through the support frame 10 made of a magnetic material as shown in the figure. In this state, the magnetic drive force F acts on the current i so that the magnetic flux φ forms the shortest loop, so that the current i flows intensively on the end side of the convex step 12a. Thereby, the fixed contact 5a and the movable contact 1
3 is in contact with the center of the contact, FIG.
As shown in the above, the current i flows from the bridging conductor 12 to the movable contact 11 by bypassing outward as shown in the figure. Therefore, when the bridging contact 6 is opened, the arc radiating point generated between the fixed contact 5a and the movable contact 11 is determined as shown in FIG.
As shown by (d), the current i quickly moves from the center of the contact to the end so as to pass through the shortest path, and moves from the periphery to the arc horn 10a . As a result, the wear of the contacts due to the arc is suppressed, and current interruption performance comparable to that of FIG. 5 is secured. Further, since the bridging conductor 12 is mounted on the upper surface side of the support frame 10, there is no possibility that the fixed contact 5a and the bridging conductor 12 will interfere with each other even if the movable contact 11 wears out. Contact support 3
Even if the bridging contact 6 (see FIG. 4A) collides, the bridging conductor 12 made of copper (soft material) is not worn.

Next, an applied embodiment of the present invention is shown in FIG. In this embodiment, the protruding step 12a of the bridging conductor 12 is formed by extruding the conductor into two ends, and has a triangular shape tapering toward both ends of the conductor.
The convex step 12a fits into a triangular hole similar to the convex step opened in the support frame 10, and the movable contact 11 is brazed to the end face exposed on the lower surface side of the support frame 10. I have.

The operation and effect of this configuration are the same as those of the embodiment of FIG. 1. In particular, the convex step 12a is formed into a tapered triangular shape, so that the magnetic material support frame fitted with the convex step is formed. Since the shape of the ten holes has a V-shaped groove similar to that of the well-known de-ion grid type arc extinguishing plate, the magnetic driving force acts more effectively on the energizing current.

[0015]

Since the bridging contact of the present invention is constructed as described above, it has the following effects. (1) In the energized state with the contacts closed, the electromagnetic repulsion acting between the fixed contact and the movable contact is suppressed to a low level to prevent the bridging contact from floating from the fixed contact when a short-circuit current flows. The welding resistance of the contacts can be greatly improved.

(2) When current is interrupted, a magnetic driving force is effectively applied to the arc generated between the contacts, so that a high current interrupting performance comparable to the conventional one can be secured. By providing the arc horn in the portion, the wear of the contact can be suppressed and the life can be prolonged. (3) Further, by incorporating the bridging conductor on the upper surface side of the support frame, undesired interference between the bridging conductor and the fixed contact, and bridging conductor due to collision between the bridging contact and the contact support supporting the bridging contact. Wear can be prevented.

[Brief description of the drawings]

FIG. 1 shows the structure of a bridging contact according to an embodiment of the present invention, wherein (a) is a plan view, (b) is a longitudinal sectional view,
(C) is a cross-sectional view in the width direction.

FIG. 2 is a plan view of a bridging contact showing an application example of the present invention.

3A and 3B are explanatory diagrams of magnetic driving of a current and an arc according to the embodiment of FIG. 1; FIG. 3A is a diagram showing a relationship between a current and a magnetic field in an energized state with contacts closed; FIG. Front view of (c)
(A) is a plan view, and (d) is a diagram showing a driving principle of an arc when a contact is opened.

4A and 4B show the structure of a conventional electromagnetic contactor and a bridging contact, wherein FIG. 4A is a cross-sectional view of the entire electromagnetic contactor, and FIG. 4B is a perspective external view of the bridging contact in FIG. Figure,
(C) is a sectional view of (b).

FIG. 5 is a diagram showing the principle of the magnetic arc drive at the time of current interruption according to FIG. 4;

[Explanation of symbols]

 2 Electromagnet for driving 5 Fixed contact 6 Bridge contact 10 Support frame 11 Movable contact 12 Bridge conductor 12a Convex step

Claims (2)

(57) [Claims] A bridging contact of an electromagnetic contactor that opens and closes between a pair of fixed contacts in accordance with the operation of a driving electromagnet, wherein a pair of movable contacts and a pair of movable contacts are mounted on a magnetic metal support frame. In those that incorporate a bridging conductor that spans,
The bridging conductor is mounted on the bottom plate of the support frame, and a convex step formed by extruding at least both end regions along the longitudinal direction of the bridging conductor is tapered toward both ends of the bridging conductor.
The convex step is fitted into a similar hole opened in the bottom plate of the support frame to expose the end face to the back side of the support frame, and a movable contact is brazed to the end face of the convex step. A bridging contact for an electromagnetic contactor, characterized in that it is constructed as follows. 2. The bridging contact of an electromagnetic contactor according to claim 1, wherein arc horns projecting toward movable contacts are provided at both ends of the support frame.