JP2000149756A - Over-current tripping device for circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an over-current tripping device for a circuit breaker, which is easy in assembly, small in size, and low in cost. SOLUTION: A heater member 20 is formed of a plate-like clad material made by sticking a ferromagnetic material 20a and a good conductor 20b together, and by disposing the good conductor 20b side opposite to an armature 7, the heater member 20 of the plate-like clad material is adapted to act as a heater while the ferromagnetic material 20a to work as a yoke for a magnetic circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overcurrent trip device for a circuit breaker.

[0002]

2. Description of the Related Art FIG. 4 is a sectional side view of a conventional circuit breaker disclosed in, for example, Japanese Utility Model Laid-Open No. 19236/1991. FIG. 5 is an exploded perspective view of the overcurrent tripping device of the circuit breaker shown in FIG. It is. In the drawing, reference numeral 1 denotes an opening / closing mechanism including a well-known toggle link mechanism and a handle spring, and 2 denotes a trip bar for tripping a trigger of the opening / closing mechanism 1. 3
Is an overcurrent tripping device having a thermal tripping means and an electromagnetic tripping means. That is, 4 is a heater made of a resistance conductor, 5
Is a yoke made of a ferromagnetic material having a U-shaped cross section, 6 is a bimetal, 6a is an adjusting screw provided at the tip of the bimetal 6 so as to face the trip bar 2, 7 is an armature made of a ferromagnetic material, Reference numeral 8 denotes a tension spring for urging the armature 7 in a predetermined direction, and these constitute the overcurrent trip device 3.

In the configuration of the overcurrent trip device 3,
The heater 4 and the bimetal 6 are integrally caulked to the U-shaped bottom of the yoke 5 by rivets 9. The amateur 7 is rotatably supported by a fulcrum 7a so that one end can be brought into contact with and separated from the magnetic pole portion 5a of the yoke 5, and a current flowing through the heater 4 forms a magnetic circuit through the yoke 5 and the amateur 7. It has been done. Therefore, the armature 7 is urged in the anti-suction direction by the tension spring 8 and the heater 4
The armature 7 is attracted to the yoke 5 against the urging force of the tension spring 8 by the electromagnetic force when the current flowing through the armature exceeds a predetermined value. 10 is a flexible copper wire 12 conducting to a movable contact 11
Are connected to the relay terminal, and are fixed to the bottom surface of the base 50 by small screws 13 together with one side of the L shape of the heater 4. That is, the overcurrent trip device 3 is fixed, and the heater 7 is conductively connected to the movable contact 11. Reference numeral 14 denotes a load-side terminal, and a flexible copper wire 15 is connected to one end of the heater 4.
Are electrically connected.

In the conventional circuit breaker overcurrent trip device configured as described above, when the current flowing through the overcurrent trip device 3 exceeds the rated current, for example, a current such as a short circuit current of 10 times or more. If it becomes, an instant cutoff is required. This instantaneous interruption is caused by the current flowing through the heater 4.
The armature 7 is attracted to the yoke 5 by the attractive magnetic force of the magnetic circuit formed by the yoke 5 and the armature 7. That is, when the attraction magnetic force exceeds the biasing force of the tension spring 8, the pusher 7b of the amateur 7
Presses the trip bar 2, operates the opening / closing mechanism 1, and the movable contact 11 is separated to cut off the circuit. When the current is less than several times the rated current, the bimetal 6 is bent by Joule heat generated by the heater 4, and the adjusting screw 6 a at the tip presses the trip bar 2. When the trip bar 2 is pressed by a predetermined amount or more, the opening / closing mechanism 1 operates to separate the movable contact 11 and cut off the current. With the current at the operation level due to the bending of the bimetal 6, the urging force of the tension spring 8 is stronger than the electromagnetic attraction force, the armature 7 does not operate, and the thermal cutoff operation is performed for a multiple of the rated current with a predetermined time limit. .

[0005]

In such a conventional overcurrent tripping device for a circuit breaker, the heater, the yoke, and the bimetal are integrally fixed by rivets, so that they are assembled without variation. Assembly work such as was complicated. In addition, since the heater and the yoke are assembled by being overlapped, the yoke and the rivet protrude from the heater, which hinders downsizing of the overcurrent tripping device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is easy to assemble and has little variation.
It is an object of the present invention to obtain a small and inexpensive overcurrent trip device for a circuit breaker.

[0007]

In an overcurrent tripping device for a circuit breaker according to the present invention, a heater member is formed of a plate-shaped clad material in which a ferromagnetic material and a good conductor are bonded.
In addition, by making the surface of the good conductor face the armature, the plate-shaped clad material functions as a heater and the ferromagnetic material surface functions as a yoke.

Further, the magnetic pole is formed by bending a part of both sides of the heater member toward the amateur side so as to improve the function as a yoke.

Further, at least one of the current-carrying connection conductors connected to one end and the other end of the heater member is connected to the ferromagnetic material surface side so as to improve the function as a heater. .

Furthermore, the heater member is made of a plate material obtained by plating a soft iron steel plate with a good conductive material so that the heater member is small and inexpensive.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a side view of an overcurrent trip device according to a first embodiment of the present invention, and FIG. 2 is a perspective view of a heater member according to the first embodiment. In the figure, reference numeral 2 denotes a trip bar for tripping a trigger of an opening / closing mechanism (not shown), which is the same as the trip bar 2 in the above-mentioned conventional apparatus. 6 is a bimetal, 6a is an adjusting screw provided at the tip of the bimetal 6 so as to face the trip bar 2, 7 is an armature made of a ferromagnetic material, 8 is a tension spring for urging the armature 7 in a predetermined direction, These are also the same as those in the above-mentioned conventional apparatus.

Reference numeral 20 denotes a heater member formed of a clad material in which a ferromagnetic plate 20a and a good conductor plate 20b made of, for example, a copper alloy plate are bonded. The heater member 20 has a pair of magnetic poles 2 bent so that the good conductor plate 20b is opposed to the armature 7 and is orthogonal to the direction of energization.
0c is provided. This magnetic pole 20c is an amateur 7
, And at the time of electromagnetic trip described below, the magnetic resistance of the magnetic circuit is reduced to increase the electromagnetic attraction force. Further, a spring hook 20d for supporting the tension spring 8 and a cutting groove 20e for improving the bending accuracy of the magnetic pole 20c during press working are provided. The connection between the heater member 20 and the load-side terminal 14 is performed by welding the connection conductor 21.
1 is welded to the ferromagnetic body 20a side. Bimetal 6
Is fixed to the heater member 20 by the rivet 9 in the same manner as the above-described conventional apparatus.

The overcurrent tripping device 30 is constituted by the bimetal 6, the armature 7, the tension spring 8, the rivet 9, the heater member 20, and the like as described above. In the configuration of the overcurrent trip device 30, the armature 7 has a fulcrum 7 such that one end thereof can be brought into contact with or separated from the magnetic pole 20 c of the heater member 20.
a, and a magnetic circuit is formed through the magnetic pole 20c and the armature 7 by an electric current flowing through the heater member 20 as described later.
Accordingly, the armature 7 is urged in the anti-attraction direction by the pulling spring 8, and the armature 7 is pressed against the magnetic pole 20c against the urging force of the pulling spring 8 by the electromagnetic force when the current flowing through the heater member 20 exceeds a predetermined value. It is sucked. 10 is a movable contact 1
1 is a relay terminal to which a flexible copper wire 12 conducting to 1 is connected, and is fixed to a bottom surface of a base (not shown) by a small screw 13 together with one side of the L shape of the heater 7. That is, the overcurrent trip device 30 is fixed, and the movable contact 11 and the heater 7 are conductively connected. Reference numeral 14 denotes a load terminal, which is conductively connected to one end of the heater member 20 by a connection conductor 21.

In the overcurrent tripping device 30 of the circuit breaker configured as described above, when the current flowing through the overcurrent tripping device 30 exceeds the rated current, for example, a current such as a short circuit current of 10 times or more. The point that instantaneous shutoff is required in the case of is the same as the above-described conventional apparatus. In this case, the current flowing through the heater member 20 is divided at a rate proportional to the conductivity ratio between the ferromagnetic plate 20a and the good conductor plate 20b, and the current passing through the good conductor plate 20b is generally larger. The ferromagnetic plate 20a, the magnetic pole 20c, and the armature 7 are arranged so as to surround the good conductor plate 20b through which the large current flows. Therefore, the current flowing through the heater member 20 causes the ferromagnetic plates 20a,
When a magnetic circuit is formed by the magnetic pole 20c and the armature 7, and the current increases, the armature 7 is attracted to the magnetic pole 20c by the attractive magnetic force of the magnetic circuit. That is, when the attraction magnetic force exceeds the biasing force of the tension spring 8, the pusher 7b of the armature 7 presses the trip bar 2 to operate the opening / closing mechanism (not shown), the movable contact 11 is separated, and the circuit is cut off. You.

At a current at which the attraction operation to the armature 7 is weak, that is, at an energizing current that does not exceed several times the rated current, the bimetal 6 is heated by Joule heat due to the resistance of the heater member 20 itself. In this case, generally, a large amount of current flows to the good conductor plate 20b side, so that heat generation is insufficient. However, in this embodiment, the connection conductor 2
Since 1 is welded to the ferromagnetic plate 20a side, the current flows through the ferromagnetic plate 20a having a high specific resistance to the connection conductor 21, so that heat generation can be secured at this portion. This heat causes the bimetal 6 to bend, and the adjusting screw 6 a at the tip presses the trip bar 2. When the trip bar 2 is pressed by a predetermined amount or more, an opening / closing mechanism (not shown) operates, and the movable contact 1
1 is cut off to cut off the current. With the current of the operation level due to the bending of the bimetal 6, the urging force of the tension spring 8 is stronger than the electromagnetic attraction force, the armature 7 does not operate, and the thermal motion cutoff operation is performed for a multiple of the rated current for a predetermined time period.

Since the resistance value of the heater member 20 needs to correspond to the rated current, the resistance value is adjusted by a means for appropriately setting the size of the kerf 20e or a means for notching the good conductor plate 20b. It can be adjusted appropriately. Further, according to the configuration of FIG. 1, the connection of the relay terminal 10 to the heater member 20 is made on the surface of the ferromagnetic plate 20a, but as shown in FIG. The resistance value can also be adjusted by configuring so as to be performed on the surface 20b.

Embodiment 2 FIG. In the first embodiment, an overcurrent tripping device having a rated current of 50 amperes was tried using the heater member 20 composed of a clad material composed of a ferromagnetic plate 20a and a good conductor plate 20b made of copper. In addition, it is difficult to obtain appropriate operation characteristics due to insufficient heat generation. That is, the heater member 20 is used to obtain the heat generation.
In some cases, the heater member 20 may be easily blown with a current several times the rated current due to a configuration such as reducing the width of the groove or increasing the cut groove 20e.

On the basis of these experimental results, in search of a material that is hard to be melted by increasing the specific resistance of the heater member, a ferromagnetic soft steel plate (for example, JIS G31)
A heater member in which only a cold-rolled steel sheet indicated by reference numeral 41) was subjected to copper plating was prototyped. According to the results of this prototype, when the rated current is 125 amperes or less, the heater member can be electromagnetically tripped according to the heater member that has been subjected to electroplating of a good conductive material on a soft iron steel plate. Was possible. Regarding the thermal dynamic cutoff characteristics and the electromagnetic cutoff characteristics, satisfactory characteristics could be obtained by appropriately selecting the plate pressure, the width dimension, and the like of the heater member made of a mild steel sheet.

According to this embodiment, a more inexpensive overcurrent tripping device can be obtained by using a soft iron steel plate which is less expensive than the clad material for the heater member.

[0020]

Since the present invention is configured as described above, it has the following effects.

The heater member is formed of a plate-shaped clad material in which a ferromagnetic material and a good conductor are bonded, and this is configured so as to act as a heater and the ferromagnetic material surface side as a yoke. A small and inexpensive overcurrent tripping device that is easy to assemble, has little variation, and can be obtained.

Further, a part in which both sides of the heater member are bent toward the amateur side to form a magnetic pole has a good function as a yoke.

Further, of the connecting conductors for current supply connected to one end and the other end of the heater member, those in which at least one of the connecting conductors is connected to the ferromagnetic material surface side can improve the function as a heater.

Further, by forming the heater member from a plate material obtained by electroplating a soft iron steel plate with a good conductive material, a small and inexpensive overcurrent trip device can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view of an overcurrent trip device according to Embodiment 1 of the present invention.

FIG. 2 is a perspective view of a heater member according to the first embodiment.

FIG. 3 is a side view of an overcurrent trip device according to another embodiment.

FIG. 4 is a side sectional view of a conventional circuit breaker.

FIG. 5 is an exploded perspective view of the overcurrent trip device of the circuit breaker of FIG.

[Explanation of symbols]

Reference Signs List 1 opening / closing mechanism, 2 trip bar, 30 overcurrent trip device, 6 bimetal, 6a adjusting screw, 7 amateur, 8 pulling spring, 10 relay terminal, 11 movable contact, 15 connection conductor, 20 heater member, 20a ferromagnetic material Plate, 20b good conductor plate, 20c magnetic pole, 20e
Notches, 21 connecting conductors.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeki Yukimoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Kazumasa Watanabe 2-3-2 Marunouchi, Chiyoda-ku, Tokyo No. Mitsubishi Electric Corporation F-term (reference) 5G030 AA09 FC11 XX08

Claims (4)

[Claims] 1. A heating / discharging means which operates when a heater member generates heat by an energizing current and the bimetal is bent by a predetermined amount due to the heat generation, and an electromagnetic device when the energizing current exceeds a predetermined value. An overcurrent tripping device for a circuit breaker having an electromagnetic tripping means adapted to be operated by attracting an armature by a force, wherein the heater member is a plate-shaped clad in which a ferromagnetic material and a good conductor are bonded. An overcurrent tripping device for a circuit breaker, characterized in that the overcurrent tripping device is formed of a material and has a structure in which a surface of a good conductor faces the above-mentioned amateur. 2. The overcurrent trip device for a circuit breaker according to claim 1, wherein the heater member is provided with a magnetic pole formed by bending a part of both sides to the amateur side. 3. The heating member according to claim 1, wherein at least one of the current-carrying connection conductors connected to one end and the other end of the heater member is connected to the ferromagnetic body surface side. An overcurrent trip device for a circuit breaker according to the above. 4. A thermal tripping means which operates when a heating member generates heat by an energizing current and the bimetal is bent by a predetermined amount due to the heat generation, and an electromagnetic device when the energizing current exceeds a predetermined value. In an overcurrent trip device of a circuit breaker having an electromagnetic trip means adapted to be operated by attracting an armature by a force, the heater member is made of a plate made of a mild steel plate plated with a good conductive material. An overcurrent trip device for a circuit breaker, comprising: