JPH052344U - Circuit breaker - Google Patents

Abstract

(57) [Abstract] [Purpose] To suppress the reflection of the pressure wave generated by the arc and to make the circuit breaker compact. [Arrangement] The arc-extinguishing chamber 25 is provided at the terminal side of the fixed contact 42.
Of the U-shaped portion 42b and the rear wall 45 of the arc extinguishing chamber 25 are defined as a pressure buffer chamber 46. Then, a plurality of holes 48 are formed in the rear wall 45 of the arc extinguishing chamber 25, and the pressure wave generated by the arc escapes from each hole 48 into the pressure buffer chamber 46 and is attenuated.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a circuit breaker having means for suppressing reflection of a pressure wave generated by a breaking arc.

[0002]

[Prior Art]

 In the conventional circuit breaker, as shown in FIG. 4, when an overcurrent such as a short-circuit current flows in the main circuit 1, a trip device (not shown) is activated and the movable contactor 2 moves to the fixed contactor 3 And the main circuit 1 is cut off. At this time, the arc generated between the contacts 2a, 3a is extinguished by the arc extinguishing device 5 provided in the arc extinguishing chamber 4, but once the arc is generated, the high heat of the arc causes the arc extinguishing chamber 4 to be extinguished. Since the internal pressure rises sharply, a pressure relief hole 6 is formed in the upper part of the rear wall of the arc extinguishing chamber 4, and the pressure is released from this pressure relief hole 6.

By the way, in the above-described conventional configuration, after the pressure wave generated by the arc travels in the direction of arrow A along the deer ion grit 7 of the arc extinguishing device 5, the rear wall 4a of the arc extinguishing chamber 4 is formed. There is a phenomenon in which it collides with, is reflected, and flows backward to both contact points 2a, 3a. Due to this phenomenon, there is a problem that high-temperature air having a high electron density flows backward between the contact points 2a and 3a and re-ignition occurs.

Therefore, in order to solve this problem, in Japanese Patent Laid-Open No. 63-21195, a pressure buffer chamber 8 is formed by molding the rear wall of the arc extinguishing chamber 4 so as to project rearward as shown in FIG. The pressure buffering chamber 8 and the arc extinguishing chamber 4 are partitioned by a metal plate 10 having a plurality of holes 9, and the pressure buffering chamber 8 suppresses the reflection of the pressure wave generated by the arc. ..

[0005]

[Problems to be solved by the device]

 In the structure described in the above publication, the rear wall of the arc extinguishing chamber 4 is projected rearward to form the pressure buffer chamber 8, so that a space for disposing the power supply terminal (not shown) connected to the fixed contactor 3 is provided. In comparison with that of the conventional structure (FIG. 4), there is no choice but to shift the pressure buffer chamber 8 backward by the space. Therefore, there is a problem that the circuit breaker becomes larger than the conventional structure by the space of the pressure buffer chamber 8.

The present invention has been made in consideration of the above circumstances. Therefore, an object of the present invention is to suppress reflection of a pressure wave generated by an arc, reliably prevent re-ignition, and achieve compactness. It is to provide a circuit breaker.

[0007]

[Means for Solving the Problems]

 The circuit breaker according to the present invention includes a fixed contact provided in a main circuit, a movable contact that comes in contact with and separates from the fixed contact, and the fixed contact that fixes the movable contact when an overcurrent flows in the main circuit. A trip device that operates to separate from the contact, and an arc extinguishing chamber that extinguishes an arc generated between the contacts when the movable contact separates from the fixed contact. A space extending between the terminal side of the fixed contact member and the rear wall of the arc extinguishing chamber by extending rearward of the arc extinguishing chamber and bending the part in a substantially U shape. And a hole for letting the pressure wave generated by the arc escape from the arc extinguishing chamber into the pressure buffer chamber.

[0008]

[Action]

 When an overcurrent such as a short-circuit current flows in the main circuit, the trip device operates and separates the movable contact from the fixed contact to shut off the main circuit. At the time of this interruption, an arc is generated between the contact points of the movable contact and the fixed contact, and this arc generates a pressure wave in the arc extinguishing chamber, which is formed on the rear wall of the arc extinguishing chamber. Since it escapes to the pressure buffer chamber through the hole formed, the reflection of the pressure wave on the rear wall of the arc extinguishing chamber is suppressed and the backflow of high temperature and high electron density air between both contacts is prevented. Re-ignition is prevented.

In this case, the terminal side portion of the fixed contact is bent in a U-shape, and the space surrounded by this U-shaped portion and the rear wall of the arc extinguishing chamber is a pressure buffer chamber. Since the U-shaped part on the terminal side also serves as the chamber wall of the pressure buffer chamber, the space on the terminal side of the fixed contact is effectively used, and the circuit breaker can be made compact.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. 2 and 3 showing the overall structure, a main body case 24 is composed of an upper case 21 made of an insulating material, a lower case 22 and a back cover 23 attached to the bottom surface of the lower case 22. An arc extinguishing chamber 25 is provided in the body case 24, and an operating handle 27 for manual opening and closing supported by a pin 26, a trip device 28 and a link mechanism that operate when an overcurrent is detected. 29 and the like are incorporated.

The link mechanism 29 includes a first link 30 and a second link 31. These links 30, 31 are connected to each other via a pin 32, and the upper end portion of the first link 30 is connected. Is connected to the operation handle 27 via a pin 33. On the other hand, the right end portion of the second link 31 in the figure is locked by a catch pin 36 below the catch 35 that is rotatably supported via a pin 34, and the lower end portion of the second link 31 has a movable insulation. The table 37 is pressed from above. The movable insulating base 37 is supported so that it can slide upward as the second link 31 rotates when overcurrent is detected.

An L-shaped movable iron piece 38 is provided in the vicinity of the trip device 28. When the overcurrent is detected, the movable iron piece 38 is attracted to the trip device 28 against the spring 39, The catch 35 is rotated counterclockwise in the drawing so that the catch pin 36 is removed from the second link 31 to perform a blocking operation described later.

On the other hand, an arc extinguishing device 41 having a plurality of deer ion grids 40 is arranged in the arc extinguishing chamber 25, and a fixed contact 42 is provided below the arc extinguishing device 41. The fixed contact 42 is bent in the arc extinguishing chamber 25 so that the fixed contact 42a is directed obliquely upward. A movable contactor 43 having a movable contact 43a is provided corresponding to the fixed contact 42a. This movable contactor 43 is maintained in a state of being urged upward by the opening / closing spring 44 and pressed against the lower part of the movable insulating base 37, and when the circuit is closed, the movable contact 43a becomes the fixed contact 42a in this state. Maintained in contact. On the other hand, when the overcurrent is detected, the movable contact 43a is separated from the fixed contact 42a while pushing up the movable insulating base 37 by the elastic force of the opening spring 44 as the second link 34 rotates. Break the circuit.

A pressure buffer chamber 46 is provided adjacent to the rear wall 45 of the arc extinguishing chamber 25 as follows. That is, as shown in FIG. 1, the terminal side portion of the fixed contact 42 is extended to the rear (left side in the drawing) of the arc extinguishing chamber 25, and the portion is bent into a U-shape, and the U-shaped portion 42b and A space surrounded by the rear wall 45 of the arc extinguishing chamber 25 is used as a pressure buffer chamber 46. An exhaust port 47 is formed in the upper portion of the rear wall 45 of the arc extinguishing chamber 25 for letting the arc gas escape to the outside, and the portion of the rear wall 45 facing the pressure buffer chamber 46 has an arc. A plurality of holes 48 for letting the pressure wave generated by the above into the pressure buffer chamber 46 escape is formed. In this case, a power terminal (not shown) is connected to the upper portion of the U-shaped portion 42b of the fixed contact 42. The pressure buffer chamber 46 of each phase is partitioned by a protruding wall 22a formed in the lower case 22 as shown in FIG.

Next, the operation of the above configuration will be described. When the current flowing through the main circuit is in the normal state, the fixed contact 42a and the movable contact 43a are in contact with each other, and the main circuit is in the closed state. After that, when an overcurrent such as a short-circuit current flows in the main circuit, the magnetic attraction force of the trip device 28 becomes larger than the tension force of the spring 39, and the movable iron piece 38 is attracted to the trip device 28. As a result, the catch 35 rotates counterclockwise in the figure, so that the second link 31 is detached from the catch pin 36. As a result, the downward pressing force of the second link 31 against the movable insulating base 37 is released, so that the movable insulating base 37 and the movable contactor 43 are moved by the elastic force of the opening / closing spring 44. They are pushed up together as one. As a result, the movable contact 43a of the movable contactor 43 is separated upward from the fixed contact 42a, and the main circuit is cut off.

At the time of this interruption, an arc is generated between the contacts 42a and 43a due to the inertia of the current. This arc is extinguished by being extended and divided by the magnetic drive of the deer ion grid 40 in the arc extinguishing device 41.

When this arc occurs, the high heat of the arc causes an excessive pressure rise between the contacts 42a and 43a, and a pressure wave is generated. The pressure wave travels along the Der ion grid 40 in the arc extinguishing device 41 toward the rear wall 45 of the arc extinguishing chamber 25, but the rear wall 45 of the arc extinguishing chamber 25 has a plurality of holes 48. Since the holes 48 are formed and communicate with the pressure buffer chamber 46, the pressure wave traveling in the direction of the rear wall 45 is released into the pressure buffer chamber 46 from the plurality of holes 48 of the rear wall 45. Therefore, it is attenuated without scattering outward, and the reflection of the pressure wave on the rear wall 45 of the arc extinguishing chamber 25 is suppressed.

Therefore, the pressure that pushes the arc extended along the deer ion grid 40 by magnetic drive from the inside of the deer ion grid 40 to between the contacts 42a and 43a is greatly reduced. Since the arc stops inside the deion grid 40, the arc is quickly extinguished without re-ignition, and the breaking performance is greatly improved.

Moreover, the terminal side portion of the fixed contact 42 is bent in a U shape, and the space surrounded by the U shape portion 42b and the rear wall 45 of the arc extinguishing chamber 25 is used as a pressure buffer chamber 46. Therefore, the U-shaped portion on the terminal side of the fixed contact 42 also serves as the chamber wall of the pressure buffer chamber 46. Therefore, the terminal side portion of the fixed contact 42 and the chamber wall of the pressure buffer chamber 46 are separately provided. Since it is not necessary to dispose, the space on the terminal side of the fixed contact 42 can be effectively utilized, and the circuit breaker can be made compact.

Further, in the above embodiment, since the exhaust port 47 is formed in the upper part of the rear wall 45 of the arc extinguishing chamber 25, the arc gas filled in the arc extinguishing chamber 25 is discharged to the outside from this exhaust port 47. There is an advantage that the pressure rise in the arc extinguishing chamber 25 can be suppressed.

The present invention is not limited to the above embodiment, but the size and number of the holes 48 formed in the rear wall 45 of the arc extinguishing chamber 25 are changed to adjust the pressure wave reflection suppressing effect at the time of arc generation. Alternatively, a metal filter member (not shown) may be attached to the exhaust port 47 above the rear wall 45 of the arc extinguishing chamber 25, and the exhaust gas may be cooled by this metal filter member. Various modifications are possible.

[0022]

[Effect of the device]

 As is apparent from the above description, the present invention is such that the terminal side portion of the fixed contact is bent in a substantially U shape, and the space surrounded by the U shape portion and the rear wall of the arc extinguishing chamber is a pressure buffer chamber. In addition, a hole was formed in the rear wall of the arc extinguishing chamber to allow the pressure wave generated by the arc to escape from the arc extinguishing chamber into the pressure relaxation chamber. In this way, the arc can be suppressed rapidly, the arc can be extinguished quickly without re-ignition, and the interruption performance can be greatly improved.

Moreover, since the space surrounded by the U-shaped portion of the fixed contact on the terminal side and the rear wall of the arc extinguishing chamber is used as a pressure buffer chamber, the space on the terminal side of the fixed contact can be effectively used. The circuit breaker can be made compact.

[Brief description of drawings]

FIG. 1 is an enlarged vertical side view of an essential part showing an embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing the overall configuration of the circuit breaker.

FIG. 3 is a rear view of the circuit breaker.

FIG. 4 is a vertical sectional side view showing a conventional arc extinguishing chamber.

FIG. 5 is a vertical sectional side view showing a conventional improved arc-extinguishing chamber.

[Explanation of symbols]

25 is an arc extinguishing chamber, 28 is a trip device, 41 is an arc extinguishing device, 4
2 is a fixed contact, 42a is a fixed contact, 42b is a U-shaped portion, 43 is a movable contact, 43a is a movable contact, 45 is a rear wall, 46 is a pressure buffer chamber, and 48 is a hole.

Claims (1)

[Claims for utility model registration] Claims: 1. A fixed contact provided in the main circuit, a movable contact coming in and out of the fixed contact, and the movable contact when an overcurrent flows in the main circuit. A tripping device that operates to open the contact from the fixed contact, and an arc extinguishing chamber that extinguishes the arc generated between the contacts when the movable contact opens from the fixed contact. In a circuit breaker equipped with, the terminal side portion of the fixed contact extends rearward of the arc extinguishing chamber and is bent in a substantially U-shape, and the U-shaped portion and the arc extinguishing chamber The space surrounded by the rear wall of the arc extinguishing chamber is used as a pressure buffer chamber, and the rear wall of the arc extinguishing chamber is formed with a hole for allowing pressure waves generated by the arc to escape from the arc extinguishing chamber into the pressure buffering chamber. And circuit breaker.