JP5050222B2 - Movable contactor of magnetic contactor - Google Patents

Description

  The present invention relates to a movable contact of an electromagnetic contactor, and more particularly to a structure of an arc horn attached to the movable contact.

  First, FIG. 7 shows the configuration of an electromagnetic contactor that is an object of the present invention. In the figure, 1 is a mold case (frame), 2 is a main circuit terminal, 3 is a fixed core of an electromagnet for operation, 4 is a movable core, 5 is an electromagnetic coil, 6 is a back spring, 7 is a main circuit terminal 2 and 2 A pair of connected fixed contacts, 8 is a bridge-shaped movable contact facing the fixed contacts 7, 7, 9 is a contact holder that holds the movable contact 8 and is connected to the movable core 4, 10 Pressurizing spring of the movable contact 8, 11 is a fixed contact 7, an arc extinguishing grid arranged opposite to the outer side of the movable contact 8, 12 is an arc runner laid on the upper surface of the fixed contact 7, and 13 is a left and right extinguishing An arc commutation plate laid between the arc grids 11 and disposed above the movable contact 8.

  The opening / closing operation of the electromagnetic contactor configured as described above is well known. Here, the arc generated between the contacts of the fixed contact 7 / movable contact 8 accompanying the release operation of the electromagnetic contactor extinguishes and the current is interrupted. Briefly describe the process up to. That is, when the movable contact 8 is separated from the fixed contact 7 by the release operation of the electromagnet in the energized state of the main circuit current, an arc is generated between the fixed / movable contacts. This arc is extended outward by receiving an electromagnetic driving force due to the magnetic flux of the current flowing through the fixed contact 7 and the movable contact 8, and on the fixed contact side, the arc foot (arcing point) moves from the fixed contact to the arc runner 12. It moves toward the arc extinguishing grid 11 after moving to. On the movable contact side, the arc is transferred from the movable contact to the commutation plate 13. Finally, the arc is divided and cooled by the arc extinguishing grid 11 to extinguish the arc, and the current is interrupted.

On the other hand, with respect to the movable contact of the electromagnetic contactor, an iron arc horn is attached to the movable contact, and the arc foot generated when the current is interrupted is quickly moved from the movable contact to the arc horn to keep the consumption of the movable contact low. Thus, the structure which extended the lifetime of the movable contact is known (for example, refer patent document 1), and the conventional structure of the movable contact 8 is shown in FIG.
In FIG. 8, 14 is a strip-shaped copper plate (copper alloy) contact base in which movable contacts (silver alloy) 15 are fixed to both ends by diffusion bonding, brazing or the like, and 16 is brazed to the back of the contact base 14. The arc horn 16 is made of an iron plate and bonded together. The arc horn 16 is bent into an L shape with both ends hanging downward so as to cover the left and right end faces of the contact base 14, and the tip of the arc horn 16 is connected to the movable contact 15. An arc transition portion 16a that is made to approach the side is formed.

According to this movable contactor with an arc horn, the leg of the arc (arcing point) generated at the time of interrupting the current quickly moves from the movable contact 15 to the arc transition portion 16a of the arc horn 16 by the action of the electromagnetic driving force. The consumption of the contact 15 can be kept low. Further, the arc transition portion 16a covers both end faces of the contact base 14, and protects the end of the contact base 14 from being consumed by touching the arc. In this case, the arc energy is consumed by melting and evaporating a part of the arc horn 16, but the arc horn 16 made of iron plate is compared with the contact base (made of copper plate) 14 of the movable contact 8. Thus, the arc resistance is high (iron has a higher melting temperature than copper and less consumption due to arc heat), which improves the electrical durability of the movable contact. Note that the iron plate arc horn 16 also serves as a reinforcing plate that prevents the contact base 15 from being plastically deformed with the repeated opening and closing operation of the electromagnetic contactor.
Japanese Patent Application Laid-Open No. 11-232980

By the way, in designing and manufacturing the movable contact with the arc horn, it is necessary to consider the following points. That is,
(1) In order to increase the arc resistance of the arc horn 16 and extend the life of the movable contact, the arc transition portion 16a of the arc horn 16 disposed at both ends of the movable contact 8 close to the movable contact 15 The volume is preferably as large as possible. In other words, if the initial volume of the arc transition portion 16a is small and the arc horn does not function sufficiently when the arc horn melts and evaporates early due to arc heat, the arc foot does not function at the tip of the contact base 14. There is a possibility that the contact block is consumed due to the stagnation, and the joint portion of the movable contact 15 fixed to the contact block 14 is peeled off and unexpectedly falls off.
(2) On the other hand, the chattering phenomenon of the movable contact caused by the bounce of the movable contact 8 due to the closing operation of the magnetic contactor (the arc is intermittently generated in the minute gap between the movable contact and the fixed contact) It is known from the bounce vibration analysis that the weight (mass) of the movable contactor 8 should be light.
(3) Further, in order to reduce the manufacturing cost of the movable contact, it is desired that the assembly process including the processing and brazing of parts is as simple as possible.

  From this point of view, the movable contact having the conventional structure disclosed in Patent Document 1 has the following problems. That is, the arc horn 16 is bent at both ends of a strip plate punched out of an iron hoop material by press working to form an L-shaped arc transition portion 16a. In order to increase the volume and increase the arc resistance, it is necessary to use a thick iron plate for the arc horn 16. However, when the plate thickness of the arc horn 16 is increased, the weight of the movable contact 8 is inevitably increased, the contact chattering time during the closing operation is lengthened, and the surface of the movable contact is quickly worn out. .

On the other hand, when the arc horn 16 is formed of a thin steel plate, the volume of the arc transition portion 16a is reduced with the conventional structure, and the arc resistance is reduced. As a result, the arc transition portion is consumed at an early stage, and it becomes impossible to ensure the long life (electrical durability) of the movable contact.
In addition, the above-mentioned Patent Document 1 discloses a structure in which a block arc horn having a large volume is spot welded to both ends of the movable contact (see FIGS. 7 and 8 of Patent Document 1). In this case, the number of parts is increased, and brazing of the movable contact and spot welding of the arc horn are performed in separate processes, which increases the number of assembly steps and increases the cost.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to solve the above-mentioned problems, and to move the magnetic contactor with an improved arc horn structure so that high arc resistance and long life can be secured at low cost. It is to provide a contact.

To achieve the above object, according to the present invention, a copper plate contact base having a pair of movable contacts fixed at both ends, and an iron plate arc horn brazed to the back of the contact base, In the movable contactor of the electromagnetic contactor, wherein the arc horn is bent at both ends of the arc horn, and the arc transition part where the tip approaches the movable contact is formed at both ends of the arc horn,
In the first invention, both ends of the arc horn are folded back in a U-shape to form an arc transition portion, and the arc-shaped transition portion is fitted to an end portion of the contact base , and the arc A concave portion into which a part of the peripheral edge of the movable contact is fitted is formed on the tip side of the transition portion .

The following effects can be obtained by the movable contact configured as described above.
(1) According to the first invention, the arc foot ignited on the surface of the movable contact during the opening operation of the magnetic contactor does not pass through the contact base from the periphery of the movable contact by the action of the electromagnetic driving force. It moves directly to the U-shaped arc transition part that is folded back at the end of the arc horn (made of iron plate). As a result, it is possible to increase the electrical durability of the movable contact by preventing the consumption of the copper plate type contact block and the peeling and dropping of the movable contact fixed to the contact block.
(2) On the other hand, according to the second invention, the arc transition portion is formed by folding the end portion of the arc horn into a plurality of layers, thereby reducing the thickness of the iron plate constituting the arc horn, and the movable contactor. While reducing the weight, it is possible to increase the arc resistance by increasing the volume of the arc transition part. Further, by brazing the folded wall surfaces together and joining them together, the folded wall is not divided apart even if the folded tip portion of the arc transition portion is consumed by arc heat, and the arc horn This makes it possible to extend the life of the movable contact while maintaining the function and volume.

  Hereinafter, embodiments of the present invention will be described based on the examples shown in FIGS. 1 is a structural diagram of the movable contact according to the first invention, FIG. 2 is a diagram schematically showing a transition path of the generated arc according to the configuration of FIG. 1, and FIG. 3 is a diagram of the movable contact according to the second invention. FIG. 4 is an exploded view of FIG. 3, FIG. 5 is an enlarged cross-sectional view of the main part of FIG. 3, and FIG. 6 is an enlarged cross-sectional view showing a state where the arc horn has been consumed. Are given the same reference numerals.

  First, an embodiment corresponding to claims 1 and 2 of the present invention will be described with reference to FIGS. 1 (a) and 1 (b) and FIG. The movable contact 8 according to this embodiment is basically composed of a contact plate 14 made of a copper plate, a pair of movable contacts 15 fixed to both ends of the contact stand 14, and the contact stand 14 as in the conventional structure of FIG. Although it becomes an assembly with the arc horn 16 made of iron plate that is brazed and bonded to the back surface, the arc transition portions 16a formed at both ends of the arc horn 16 are configured in the following shape.

In other words, in the illustrated structure, both ends of the arc horn 16 are folded inward to form an arc transition portion 16a bent in a U shape. Further, a concave portion 16a-2 into which a part of the peripheral edge of the movable contact 15 is fitted is formed at the tip of the U-shaped folded portion 16a-1 of the arc transition portion 16a.
In the assembly process of the movable contact 8, the U-shaped arc transition portion 16 a is fitted to the end of the contact base 14, and the movable contact 15 is fitted and positioned in the concave portion 16 a-2 and held in the assembly jig. After that, the movable contact 8 is assembled by carrying it into a heating furnace and simultaneously performing brazing between the contact base 14 and the arc horn 16 and diffusion bonding of the movable contact 15. The arc horn 16 is formed by punching a thin steel plate in order to reduce the weight of the movable contact 8 and suppress the bounce and chattering phenomenon that occurs during the closing operation.

  According to the above configuration, as can be seen from FIG. 1B, the U-shaped arc transition portion 16 a formed by folding back at the end of the arc horn 16 covers the end of the copper plate contact base 14 from the outside, and The front end of the letter-shaped folded portion 16-1 is directly connected to the periphery of the movable contact 15. As a result, as shown in the schematic diagram of FIG. 2, the arc arc generated between the magnetic contactor and the fixed contact is opened from the surface of the movable contact 15 by the action of the electromagnetic driving force. After moving quickly toward the center, the peripheral edge of the arc horn 16 (made of iron plate) is directly transferred to the arc transition portion 16a to move and extend in the direction of the arrow.

  Therefore, the contact point 14 made of copper plate, which is the conductive base material of the movable contact 8, is not directly consumed by the arc, and the joint of the movable contact 15 fixed to the contact point 14 is protected from the arc. Thus, the life of the movable contact 8 is increased.

  Next, a second embodiment corresponding to claims 3 and 4 of the present invention will be described with reference to FIGS. In this embodiment, both ends of the arc horn 16 are folded outward to bend the arc transition portion 16a having a double structure. The arc horn 16 is bent and folded at both ends of a strip shape punched out from an iron hoop material by pressing to form an arc transition portion 16a. In addition, in order to braze between the overlapping folding walls 16-3 that overlap inward and outward in the brazing process described later and to integrally join them, the inner overlapping folding wall 16-3 is melted as shown in FIG. 4B. A hole 16a-4 through which the brazing material penetrates is drilled in advance.

  In the assembly process of the movable contact 8, as shown in FIG. 4 (a), the arc horn 16 is superimposed on the contact base 14 with the movable contact 15 and the sheet-like brazing material (silver brazing) 18 sandwiched between them. The temporary assembly is carried into a heating furnace, and brazing of the arc horn 16 and diffusion bonding of the movable contact 15 are performed simultaneously to assemble the movable contact 8. In the figure, 14a is a protrusion formed at both ends of the contact base 14 for positioning the movable contact 15, and this protrusion may be omitted.

Next, FIG. 5 shows the main structure of the movable contact 8 after assembly. As shown in the figure, the brazing material heated and melted in the assembly process penetrates into the arc transition portion 16a of the fold-fold structure through the hole 16a-4 by the capillary phenomenon, and the overlapping surface of the inner and outer double fold wall 16a-3. Are joined together. Reference numeral 17a represents a bonding layer of brazing material.
According to this embodiment, the arc transition portion 16a of the arc horn 16 is double-folded and folded, so that the arc horn 16 is made of an iron plate having a thinner plate thickness than the movable contact 8 having the conventional structure shown in FIG. The weight of the movable contactor 8 is reduced by using (effective for suppressing bounce and chattering phenomenon), and the arc transition part 16a adopts a lap folding structure to increase its volume and ensure high arc resistance. it can. Moreover, as described above, by repeatedly brazing between the inner and outer folded walls 16a-3 forming the arc transition portion 16a and integrally joining them, as shown in FIG. Consumption of the arc transition portion 16a due to the arc heat proceeds from the tip side with the operation, and even if the folded tip portion is melted and evaporated (represented by a chain line), the outer wall may be divided and fall off. The function and volume of the arc horn can be maintained over a long period of time and the life of the movable contact can be ensured.

  In the illustrated example, both ends of the arc horn 16 are overlapped and folded outward to form a double-structured arc transition portion 16a. It is also possible to further increase the volume of the arc transition part by overfolding as described above. Also in these structures, by drilling a hole through which the molten brazing material permeates in the same manner as in FIG. 5, it is possible to integrally braze between the wall surfaces overlapping inside and outside.

  In addition, as an applied embodiment, the arc horn 16 is composed of short parts divided into left and right parts (in the illustrated embodiment, composed of a single iron plate), and this divided arc horn is brazed to the back of the left and right ends of the contact base 14. It is also possible to assemble the movable contact.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural diagram of a movable contact according to a first embodiment of the present invention. A diagram schematically showing the transition path of the arc generated by the movable contact shown in FIG. FIG. 4 is a structural diagram of a movable contact according to a second embodiment of the present invention, wherein (a) and (b) are a side view and a bottom view, respectively FIG. 4 is an assembly explanatory view of the movable contact shown in FIG. 3, (a) is an exploded view, and (b) is an enlarged perspective view of an A portion in FIG. 3 is an enlarged cross-sectional view of the main part in FIG. Sectional drawing showing the state where a part of arc horn was consumed with the structure of FIG. Cross-sectional view of a configuration of an electromagnetic contactor that is an object of the present invention FIG. 8 is a conventional structural view of the movable contact in FIG. 7, (a) and (b) are a side view and a bottom view, respectively.

Explanation of symbols

8 Movable contact 14 Contact base 15 Movable contact 16 Arc horn 16a Arc transition part 16a-1 U-shaped folded part 16a-2 Recessed part 16a-3 Overlapping wall 17 Brazing material (silver brazing sheet)

Claims (1)

It is an assembly of a copper plate contact base with a pair of movable contacts fixed at both ends, and an iron plate arc horn brazed to the back of the contact base, and at both ends of the arc horn In the movable contactor of the electromagnetic contactor that is formed by bending the arc transition portion that covers the end surface of the contact base and the tip approaches the movable contact point,
An arc transition portion is formed by folding both ends of the arc horn inward to form an arc transition portion, and the U-shaped arc transition portion is fitted to an end portion of the contact base, and on the tip side of the arc transition portion. A movable contact for an electromagnetic contactor, wherein a concave portion into which a part of the periphery of the movable contact is fitted is formed .

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