JP4483130B2 - Arc extinguishing mechanism of switchgear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arc extinguishing mechanism of an opening / closing device that opens and closes a DC electric circuit.
[0002]
[Prior art]
FIG. 7 is a schematic cross-sectional view of an electromagnetic contactor which is a type of conventional DC switchgear.
In FIG. 7, 1 is a cross bar, 2 is a spring receiver disposed in the window frame 1a of the cross bar 1, 3 is a protrusion 2a provided on the spring receiver 2, and a spring receiver 2 in the window frame 1a of the cross bar 1. A spring 4 coupled to a protrusion 1b provided at an opposing position is a movable contact 4 held between the spring receiver 2 and the window frame 1a of the cross bar 1 by being pressed by a spring 3, and 4a is a movable contact 4 5 is a fixed contact having a fixed contact 5a facing the movable contact 4a, 6 is an arc horn, 7 is an arc cover that holds the arc horn 6 with screws 8 and forms an outer shell, and 9 is an arc. Permanent magnets 10 held between the cover 7 and the arc horn 6 indicate the housing that holds the stationary contact 5 and forms an outer shell.
[0003]
FIG. 8 is a state diagram showing the operation of the arc extinguishing mechanism of the conventional electromagnetic contactor.
In the arc extinguishing mechanism of the electromagnetic contactor having the conventional structure, the movable contact 4a and the fixed contact 5a shown in FIG. 8a are separated from the state where the movable contact 4a and the fixed contact 5a are in contact with each other to form an electric circuit. In the circuit breaking operation, the arc 101 generated between the movable contact 4a and the fixed contact 5a is driven by the permanent magnet 9 in the direction B opposite to the direction A in which the crossbar 1 is located, and the permanent contact with the movable contact 4 as shown in FIG. It is divided into two arcs 101a and 101b between the magnets 9 and between the arc horn 6 and the stationary contact 5.
Thereafter, the two arcs 101a and 101b are driven in the A direction on the crossbar side and the B direction on the arc horn side opposite to the A direction by the permanent magnets 9 because the current directions are opposite, as shown in FIG. 8c. The arc length increases and continues until the total arc length on the crossbar side and arc horn side corresponds to the circuit voltage condition, when the arc is met, the arc is extinguished.
[0004]
[Problems to be solved by the invention]
In the arc extinguishing mechanism of an electromagnetic contactor having a conventional structure, an arc generated between a movable contact and a permanent magnet is driven by a magnetic field generated by the permanent magnet, and the permanent magnet surface and the movable contact surface are crossbar 1. The arc 101a reaches the crossbar 1.
A shield plate made of an insulating material having a function of covering the crossbar 1 is provided between the crossbar 1 and the surface of the permanent magnet 9 in order to shield the thermal stress caused by the arc, thereby preventing damage. Since the child and the crossbar 1 are movable objects that move up and down during the opening and closing operation of the contacts, they cannot be completely covered, and the crossbar 1 is affected by the heat generated by the arc generated during the opening and closing operation of the magnetic contactor. End up.
Further, in order to reduce the influence of the arc on the crossbar 1 in comparison with the conventional electromagnetic contactor having a configuration including a shielding plate made of an insulating material having a function of covering the crossbar 1 described above, In addition to the configuration, it was possible to cope with the problem by increasing the distance from the permanent magnet 9 to the cross bar 1, but it was difficult to reduce the size of the product with this configuration.
[0005]
Further, in the DC current interruption of the magnetic contactor, the arc heat has a great influence on the insulating parts due to the arc heat, and the arc extinguishing chamber insulating material needs to have high heat resistance. Therefore, conventionally, a material having high heat resistance has been used as the material of the arc cover 7 constituting a part of the arc extinguishing chamber.
However, a material having high heat resistance does not have mechanical elasticity.
For this reason, the conventional arc cover 7 has no mechanical elasticity, and when the arc cover 7 is attached to the housing 10, a fixing part such as a screw is necessary, and the screw is temporarily fixed to the arc cover 7. Tightening man-hours were necessary.
[0006]
Also, in the arc extinguishing mechanism of the electromagnetic contactor having the above structure, as shown in FIGS. 8b and 8c, a screw that becomes the same potential as the main circuit terminal by the arc when the arc is generated outside the arc cover 7 and becomes a charging part. Since 8 is exposed, it is necessary to ensure a certain insulation distance between the arc cover 7 and the door of the control panel.
[0007]
The present invention has been made to solve the above-described problems. A first object of the present invention is to maintain a gap between a permanent magnet and a crossbar and to reduce a size of an arc extinguishing chamber in DC current interruption. It is to be.
[0008]
The second purpose is to hold the arc horn made of a conductive non-magnetic material on the side surface opposite to the cross bar of the permanent magnet, and to transfer the arc generated between the contacts to the arc horn to divide it.
[0009]
The third object is to provide an edge at the tip of the arc horn that holds the permanent magnet, and to promote the transition of the arc generated between the contacts to the arc horn.
[0010]
The fourth purpose is to make the arc cover material thermoplastic, to make it easy to attach and detach the arc cover to the base, and to prevent exposure of metal mounting parts such as screws to the front of the arc cover. It is to improve.
[0011]
[Means for Solving the Problems]
An arc extinguishing mechanism of a switchgear according to the present invention includes a movable contact that is pressed by a spring disposed in a crossbar and is held by the crossbar, a stationary contact that faces the movable contact, and an outer shell. An arc shield made of an insulating material that covers the crossbar side of the surface facing the movable contact of the permanent magnet, and a permanent magnet disposed inside the arc cover. An arc horn made of a conductive nonmagnetic material, provided on the side opposite to the crossbar of the magnet, and provided with an edge portion that opens a part of the surface facing the movable contactor of the permanent magnet. is there.
[0014]
Moreover, an engaging part is formed with respect to an arc cover and an arc shield, and an arc shield is assembled | attached in the state which mounted the permanent magnet.
[0015]
Further, the arc shield is made of a heat resistant material, the arc cover material is made of thermoplastic resin, and the engaging portion of the arc shield and the arc cover is attached by the elastic force of the arc cover so that it can be removed.
[0016]
The range in which the permanent magnet is covered with the arc shield is determined so that the arc length satisfying the interruption condition is obtained by the rated voltage and rated current in the current switching of the electromagnetic switch.
[0017]
Furthermore, of the facing surface of the permanent magnet that faces the contact portion back surface of the movable contact, approximately 1/2 of the crossbar side to the topmost portion in the direction of the movable contact is covered with an arc shield made of a thermosetting resin. is there.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1.
An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic longitudinal sectional view showing an arc extinguishing mechanism of an electromagnetic contactor according to an embodiment of the present invention, and FIG. 2 is a schematic cross section showing an internal structure of the electromagnetic contactor as viewed from the direction A in FIG. FIG.
In the figure, 1 is a cross bar, 2 is a spring receiver disposed in the window frame 1a of the cross bar 1, 3 is a protrusion 2a provided on the spring receiver 2, and the spring receiver 2 in the window frame 1a of the cross bar 1 is opposed. 4 is a movable contact 4 held between the spring receiver 2 and the window frame 1a of the cross bar 1 by being pressed by the spring 3, and 4a is attached to the movable contact 4. The provided movable contact, 5 is a fixed contact having a fixed contact 5a opposite to the movable contact 4a, 6 is an arc horn, 7 is made of a thermoplastic resin, holds the arc horn 6 and forms an outer cover, 9 is a permanent magnet held between the arc cover 7 and the arc horn 6, 10 is made of thermoplastic resin or thermosetting resin, holds the stationary contact 5, and forms a housing, 11 is immediately before extinguishing the arc. Arc 101a and Arc 1 Because 1b to clash, a arc shield made of a heat-resistant material such as a thermosetting resin.
An edge portion 6 a is provided at the tip of the arc horn 6 that faces the movable contact 4.
[0019]
In addition, the material of the arc cover 7, the housing 10, and the arc shield 11 is determined by the magnitude of the thermal influence due to the arc when the electromagnetic contactor is opened / closed.
In particular, in a DC electromagnetic switch, a part that is exposed to an arc for a long time and has a large heat effect needs to be made of a heat-resistant material.
[0020]
FIG. 3 is a state diagram showing a state before the arc shield 11, the arc horn 6 and the permanent magnet 9 are attached to the arc cover 7. FIG. 4 shows each of the arc shield 11, the permanent magnet 9 and the arc horn 6. FIG. 5 is a perspective view showing a state when the arc cover 7 is attached according to one embodiment of the present invention.
In the drawing, the tip 6 b of the arc horn 6 is inserted into the groove 7 b 1 of the arc cover 7, the wall 11 b of the arc shield 11 is inserted into the groove 7 b 2 of the arc cover 7, and the permanent magnet 9 is the dish-shaped part of the arc cover 7. After that, the claw portion 11a of the arc shield 11 is engaged with the concave portion 7a of the arc cover 7.
In the above assembly process, immediately before the claw portion 11a of the arc shield 11 is engaged with the concave portion 7a of the arc cover 7, the peripheral portion of the concave portion 7a of the arc cover 7 is deformed. At this time, the arc cover 7 is deformed without breaking, but this deformation operation is obtained because the material of the arc cover 7 is made of a thermoplastic resin having a high elastic force.
[0021]
Further, the claw portion 7 c of the arc cover 7 is engaged with the concave portion 10 c of the housing 10, and the claw portion 7 d of the arc cover 7 is engaged with the concave portion 10 d of the housing 10. (See Fig. 1 and Fig. 2)
The arc cover 7 is attached to the housing 10 through the process of FIGS. 5a to 5b, and the state shown in FIGS. 1 and 2 is reached. However, in the course of the process of FIGS. 1) and 7d part (FIG. 2) and its periphery are deformed.
At this time, the arc cover 7 is deformed without breaking, but this deformation operation is obtained because the material of the arc cover 7 is made of a thermoplastic resin having a high elastic force.
[0022]
FIG. 6 is a state diagram showing the operation of the arc extinguishing mechanism of the magnetic contactor according to the embodiment of the present invention.
Next, an operation of the arc extinguishing mechanism of the magnetic contactor configured as described above will be described. When the movable contact 4a and the fixed contact 5a are brought into contact with each other to form an electric circuit, the movable contact 4a and the fixed contact 5a are separated from each other as shown in FIG. An arc 101 is generated between them.
The arc 101 is driven by the permanent magnet 9 and moves from the position of FIG. 6a to the position of FIG. 6b.
Then, the arc 101 is transferred to the arc horn 6 while obtaining an urging force due to electric field concentration of the edge portion 6a of the arc horn 6, and is divided into 101a and 101b by the arc horn 6 to be in the state of FIG. 6c.
Thereafter, the permanent magnet 9 applies a driving force to the arc 101a in the direction A in FIG. 6c and to the arc 101b in the direction B in FIG. 6c.
[0023]
At this time, since the arc is generated between the conductive portions of the permanent magnet and the movable contact, there is no insulator that prevents movement in the traveling direction A with respect to the end of the movable contact 4 of the arc 101a, but the permanent magnet 9 of the arc 101a. The arc shield 11 is prevented from moving as an insulator in the traveling direction A with respect to the side terminal.
For this reason, although the arc 101a is given a driving force in the direction A, it cannot move and remains stationary in the state shown in FIG. 6d.
[0024]
As described above, approximately 1/2 of the permanent magnet 9 from the crossbar 1 side to the topmost portion in the direction of the movable contact 4 out of the facing surface 9a of the contact of the movable contact 4 with the back surface of the movable contact 4 is made of a thermosetting resin. The arc shield 11 is covered, and the portion opposite to the cross bar 1 is covered with the arc horn 6. (FIGS. 3 and 6a)
The range in which the permanent magnet 9 is covered with the arc shield 11 needs to be determined so that the arc length satisfying the interruption condition is obtained by the rated voltage and rated current in the current switching of the electromagnetic switch.
For example, in the case of rated voltage DC220V and rated current 20A, it is determined to be 5 mm.
[0025]
Thus, by covering a part of the surface 9a facing the movable contact 4 of the permanent magnet 9 with a heat-resistant material, the distance from the surface of the cross bar 1 to the center of the permanent magnet 9 is reduced to an electromagnetic switch according to the prior art. On the other hand, it is reduced in the electromagnetic switch of the present application.
Further, there is no insulator that obstructs movement in the traveling direction B with respect to both ends of the arc 101b, and the arc 101b is driven in the B direction while moving on the arc horn 6 and extends to the state shown in FIG. 6d.
At this time, since the arc horn 6 is a non-magnetic material, the magnetic flux generated by the permanent magnet is not concentrated on the cross section of the arc horn 6, and the supply of the magnetic flux to the air arc portion is ensured. As a result, the necessary arc driving force is obtained. Secured. Moreover, since the arc horn 6 is highly conductive, the arc 101b is promptly moved.
In this way, the total arc voltage of arc 101a and arc 101b in FIG. 6d exceeds the insulation recovery voltage, and the arc is extinguished.
[0026]
According to the present embodiment, the generated arc 101a is constrained to the exposed surface of the conductive portion of the permanent magnet, and the arc 101a is prevented from moving in the A direction. 7 (from the surface of the crossbar 1 to the inner surface of the arc box 10), the arc extinguishing chamber dimension Y (from the surface of the crossbar 1 in FIG. 1 to the inner surface of the arc shield 11) of the electromagnetic switch according to the present embodiment is about It is reduced by 25%, the arc extinguishing structure can be miniaturized, and the product can be miniaturized. Note that unlike the conventional technology, the object covered by the insulating material is different from the crossbar or permanent magnet. The function of the cover protects the crossbar from the heat of the arc or restricts the movement of the arc in the crossbar direction of the permanent magnet surface. Is different.
In the process of shifting from the state shown in FIG. 6b to the state shown in FIG. 6c, the arc 101b commutated to the arc horn 6 made of a conductive material moves on the arc horn 6 and promotes the extension of the arc 101b.
Since the arc horn 6 is made of a nonmagnetic material, it does not affect the path of the magnetic flux excited by the permanent magnet 6 in the arc generation region.
Further, in the process of shifting from the state shown in FIG. 6 b to the state shown in FIG. 6 c, the edge portion 6 a of the arc horn 6 promotes electric field concentration and promotes the movement of the arc to the arc horn 6. Further, since the arc cover 7 and the housing 10 can be coupled without using additional parts such as screws, the material cost and the installation cost are low, and the attachment and detachment are easy.
It should be noted that the metal parts for coupling such as screws can be prevented from being exposed to the outside of the arc cover 7, and it is not necessary to secure an insulation distance from the outer surface of the arc cover 7 to the door of the control panel. Can be miniaturized.
[0027]
【The invention's effect】
As described above, according to the present invention, the crossbar can be protected from arc heat by limiting the movement of the arc generated between the movable contact and the permanent magnet in the crossbar direction by the arc shield. .
[0028]
Further, the arc commutated to the arc horn made of a conductive material moves on the arc horn, promotes the elongation of the arc, and can be divided.
[0029]
Moreover, the edge part of an arc horn promotes electric field concentration, promotes the movement of the arc to the arc horn, and can be divided.
[0030]
Further, since the arc cover and the housing can be connected without using additional parts such as screws, the material cost and the installation cost are low, and the attachment and detachment are easy.
In addition, the metal parts for coupling such as screws can be prevented from being exposed to the outside of the arc cover, and it is not necessary to secure an insulation distance from the outer surface of the arc cover to the door of the control panel. Can be
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing an arc extinguishing mechanism of an electromagnetic contactor according to an embodiment of the present invention.
2 is a schematic longitudinal sectional view showing the internal structure of the magnetic contactor as viewed from the direction A in FIG. 1. FIG.
FIG. 3 is a state diagram showing a state before the arc shield 11, the arc horn 6 and the permanent magnet 9 are attached to the arc cover 7 in the arc extinguishing mechanism of the magnetic contactor.
FIG. 4 is a perspective view of components of an arc shield, a permanent magnet, and an arc horn in an arc extinguishing mechanism of an electromagnetic contactor.
FIG. 5 is a perspective view showing an external appearance of an electromagnetic contactor.
FIG. 6 is a schematic longitudinal sectional view showing an arc extinguishing mechanism of the magnetic contactor of the present invention.
FIG. 7 is a schematic longitudinal sectional view showing a conventional arc extinguishing mechanism of an electromagnetic contactor.
FIG. 8 is a schematic longitudinal sectional view showing an arc extinguishing mechanism of a conventional electromagnetic contactor.
[Explanation of symbols]
1 crossbar, 2 spring support, 3 spring, 4 movable contact, 4a movable contact, 5 fixed contact, 5a fixed contact, 6 arc horn, 6a edge of arc horn, 6b insertion of arc horn into arc cover groove , 7 arc cover, 7a arc cover holding claw part of the arc cover, 7b1 arc horn gripping part of the arc cover, 7b2 arc shield gripping part of the arc cover, 7b3 permanent magnet contact part of the arc cover, 7c arc cover housing Claw part for fixing to the housing, 7d Claw part for fixing the arc cover to the housing, 8 screws, 9 permanent magnets, 9a Arc, 101b Arc after cutting.

Claims (5)

A movable contact that is pressurized by a spring disposed in the crossbar and held by the crossbar, a stationary contact that faces the movable contact, an arc cover that forms an outer shell, and an arc cover that is disposed inside the arc cover In a switchgear provided with a permanent magnet
An arc shield made of an insulating material that covers the crossbar side of the surface facing the movable contact of the permanent magnet ;
An arc horn made of a conductive non-magnetic material, provided on the anti-crossbar side of the permanent magnet, and provided with an edge portion that opens a part of the facing surface of the permanent magnet to the back surface of the movable contact;
An arc extinguishing mechanism characterized by comprising: The arc extinguishing mechanism of the switchgear according to claim 1 , wherein an engaging portion is formed with respect to the arc cover and the arc shield, and the arc shield is assembled in a state where the permanent magnet is placed. The arc shield is formed by heat-resistant material, the arc cover material and the thermoplastic resin, attached by the elastic force of the arc cover engaging portion of the arc shield and the arc cover or claim 1, characterized in that the removable The arc extinguishing mechanism of the switchgear according to 2 .   2. The range in which the permanent magnet is covered with an arc shield is determined so as to satisfy an arc length that satisfies a breaking condition by a rated voltage and a rated current in current switching of an electromagnetic switch. An arc extinguishing mechanism for the switchgear according to claim 1. Of the surface of the permanent magnet facing the contact part back surface of the movable contact, approximately 1/2 from the crossbar side to the topmost part in the direction of the movable contact is covered with an arc shield made of a thermosetting resin. The arc-extinguishing mechanism of the switchgear according to claim 4 .

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