JPH1116476A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To largely ensure the displacement amount capable of adjusting the free end of a bimetal without applying stress to the bimetal of a thermal tripping mechanism and the welding part of the bimetal and a conductor metal fitting by securing the bimetal to the conductor metal fitting, using an adjust screw engaging with the conductor metal fitting, and adjusting the trip operation point of the bimetal by changing a bending angle. SOLUTION: In a conductor metal fitting 25, a current carrying part 25a on one end side is secured to a power source side terminal conductor 23, and a bimetal joining part 25b on the other end side extended and an adjusting screw screwed part 25c are formed so that the bending angle is variable. One end of bimetal 24 is secured to the bimetal joining part 25b by resistant welding or the like. When an adjust screw 26 is screwed, the adjusting screw screwed part 25c is displaced in the P direction around a fulcrum X, the current carrying part 25a and the bimetal 24 are moved around the fulcrum X to produce displacement amount B, and a gap A between a free end 24a and a latch 39 and can be adjusted without producing stress in the bimetal joining part 25b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overcurrent tripping mechanism in a relatively small circuit breaker, and more particularly to a thermal tripping mechanism using a bimetal.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a side sectional view showing the inside of a conventional circuit breaker shown in Japanese Patent Application Publication No. H10-214, partly cut away. FIG. 5 is an enlarged side view showing a main part of a conventional thermal tripping mechanism of a circuit breaker. In the figure, reference numeral 1 denotes an insulating casing formed of a synthetic resin, 1a denotes a base, and 1b denotes a cover. 2 is a power supply side external terminal for connecting an external conductor (not shown), 3 is a power supply side external terminal 2
The power supply terminal conductor 4 connected to the power supply terminal conductor 4 is a bimetal for detecting an overcurrent, and has one end fixed to the power supply terminal conductor 3.
5 is a flexible electric wire connected to the free end 4a of the bimetal 4,
Reference numeral 6 denotes a fixed contact, to which the flexible electric wire 5 connected to the bimetal 4 is connected. Reference numeral 7 denotes a movable contact provided opposite to the fixed contact 6.

An arc runner 9 guides an arc generated between the contacts when an overcurrent is interrupted to an arc extinguishing device (not shown). An adjusting screw 10 for the bimetal 4 is provided. The trip operation point is adjusted by displacing the free end 4a of the bimetal 4 with the portion (weld portion 15) to which is fixed as a fulcrum. Reference numeral 11 denotes an opening / closing mechanism for opening / closing the movable contact 7 with respect to the fixed contact 6, and 12 denotes a large current such as a short-circuit current or the like when pressed by the free end 4a of the bimetal 4 when an overcurrent flows. This is a latch that is pressed by a rod 16 of an electromagnetic tripping mechanism (not shown) to detect and release the engagement of the opening / closing mechanism 11 and trip the circuit breaker. Reference numeral 13 denotes a handle for manually operating the opening / closing mechanism 11, and reference numeral 14 denotes a load-side external terminal connected to the movable contact 7 via an electromagnetic trip mechanism (not shown).

In such a conventional circuit breaker,
Normally, the current flows from the power supply side external terminal 2 to the power supply side terminal conductor 3 →
It flows to the load-side external terminal 14 via an electric path such as a bimetal 4 → a flexible electric wire 5 → a fixed contact 6 → a movable contact 7 → an electromagnetic trip mechanism (not shown).

When an overcurrent flows in the electric circuit, the bimetal 4 detects this and the free end 4a of the bimetal 4 rotates clockwise, pushing the latch 12 to trip the opening / closing mechanism 11, The movable contact 7 is separated from the stator 6 to open the circuit breaker. At this time, when an overcurrent exceeding a predetermined value flows, the circuit breaker must be tripped within a specified time, so that the gap A between the free end 4a of the bimetal 4 and the latch 12 is adjusted to a predetermined value. There is a need to. The adjustment is performed by the adjusting screw 10. However, as shown in FIG. 5, since the gap A varies depending on each rated current of the circuit breaker, the displacement B of the free end 4a of the bimetal 4 also varies depending on each rated current.

[0006]

In the conventional thermal tripping mechanism as described above, the adjusting screw 10 is screwed in so that the bimetal 4 is directly pressed by the tip of the adjusting screw 10 with the power supply terminal conductor 3 as a fulcrum. . Therefore, since stress is applied to the bimetal 4, it is necessary to adjust the displacement within the elastic limit of the bimetal 4, and when the displacement B shown in FIG. 5 is large, the adjustment becomes difficult.
In addition, mechanical strength is required also at the welded portion 15 between the power supply side terminal conductor 3 and the bimetal 4 which is a fulcrum at the time of adjustment, and for example, it must be joined by welding using a brazing material such as silver brazing. However, there is a problem that the welding cost is also increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and the free end of the bimetal can be adjusted without applying stress to the bimetal of the thermal tripping mechanism and the welded portion between the bimetal and the conductor fitting. It is an object of the present invention to obtain a circuit breaker capable of securing a large displacement amount.

[0008]

A circuit breaker according to the present invention has an opening / closing mechanism for driving a movable contact to open / close with respect to a fixed contact, a bimetal bent by a circuit current, and a circuit current having a predetermined value. Circuit breaker with a thermal trip mechanism that trips the opening / closing mechanism when the pressure exceeds the limit, a terminal fitting for supplying circuit current, and an insulating housing in which both the above mechanism and the terminal fitting are disposed. In the vessel,
A bimetal is fixed to a conductor fitting that is fixed to the terminal fitting and that can change the bending angle, and the bending angle of the bimetal is changed by changing the bending angle of the conductor fitting using an adjusting screw that engages with the conductor fitting. The trip operating point is adjusted.

The adjusting screw has a head held on a wall surface of the insulating housing so that the adjusting screw can be adjusted from an outer surface of the insulating housing, and a screw portion is screwed into a conductor fitting.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a side sectional view showing a circuit breaker according to an embodiment of the present invention, with a part cut away to show the inside. 2 and 3 are enlarged perspective views showing the thermal trip mechanism of the circuit breaker of the present invention. FIG. 2 shows a state before the displacement adjustment of the bimetal, and FIG. 3 shows a state after the displacement adjustment of the bimetal. .

In FIG. 1, reference numeral 21 denotes an insulating case formed of a synthetic resin, 21a denotes a base, and 21b denotes a cover. Reference numeral 22 denotes a power-supply-side external terminal for connecting an external conductor (not shown), and reference numeral 23 denotes a power-supply-side terminal conductor connected to the power-supply-side external terminal 22. Reference numeral 24 denotes a bimetal for detecting an overcurrent flowing in the electric circuit. Reference numeral 25 denotes a conductor fitting in which a current-carrying portion 25a at one end is fixed to the power-supply-side terminal conductor 23 for supplying a circuit current, and a bimetal joint 25b at the other end extended as shown in FIG. The portion (flat portion) of the screw engagement portion 25c is formed so that the bending angle can be changed. That is, as shown in FIG.
It is formed to be curved when a force is applied in the direction. A part of the conductor fitting 25 is extended so as to pass below the base 21a as shown in the figure, and an arc guiding portion 25d is formed. This arc guiding part 25d
Is for guiding an arc generated between the contacts, which will be described later, when the overcurrent is interrupted, toward an arc extinguishing device (not shown). One end of the bimetal 24 is fixed to the bimetal joint 25b of the conductor fitting 25 by resistance welding or the like.

Numeral 26 denotes an adjusting screw whose head 26a is held by a partition 21c of the insulating casing 21 and whose screw portion 26b is screwed into a screw hole provided in the adjusting screw screwing portion 25c of the conductor fitting 25. ing. A thermal trip mechanism 27 is provided by a conductor fitting 25, a bimetal 24, an adjusting screw 26, and the like.
Are formed. Reference numeral 28 denotes a flexible electric wire that electrically connects the bimetal 24 and a movable contact 30 described later, 29 denotes a fixed contact, and 30 denotes a movable contact provided to face the fixed contact 29. Reference numeral 31 denotes an arm that integrally supports the movable contact 30. Reference numeral 32 denotes a support shaft that is a rotation center of the arm 31 and the movable contact 30, and is installed on the base 21a. A load-side external terminal 33 is electrically connected to the fixed contact 29 via an electromagnetic trip mechanism 34.

A main spring 35 biases the movable contact 30 in a direction to always separate the movable contact 30 from the fixed contact 29.
A handle for manual operation of N and OFF, 37 is a reset spring for urging the handle 36 in a counterclockwise rotation direction, 38 is an operation link formed of a round bar material in a U shape, and one end is connected to the handle 36. The other end is formed so as to be engaged with a link engagement groove 39a of a latch 39 described later.

A latch 39 is pivotally supported by the support shaft 32. The latch 39 is engaged with the other end of the operation link 38.
a, a trigger piece 39b that receives the pressing force of the rod 34a of the electromagnetic trip device 34, and a force that releases the engagement between the operation link 38 and the link engaging groove 39a by the pressing force due to the bending of the bimetal 24. A trigger piece 39c is formed. The arm 31 and the main spring 35
, A handle 36, a reset spring 37, an operation link 38, a latch 39, and the like, form an opening / closing mechanism 40.

In the circuit breaker thus configured, the current is normally supplied from the power supply side external terminal 22 to the power supply side terminal conductor 23 → the conducting portion 25a of the conductor fitting 25 → the bimetal 24.
→ flexible electric wire 28 → movable contact 30 → fixed contact 29 → flows to load side external terminal 33 via electromagnetic trip device 34 and the like. If an overcurrent flows through this circuit, the bimetal 2
4 detects this, the free end 24a of the bimetal 24 bends clockwise, presses the trigger piece 39c of the latch 39, trips the opening / closing mechanism 40, and separates the movable contact 30 from the fixed contact 29. To open the circuit breaker.

Next, a method of adjusting the gap A between the free end 24a of the bimetal 24 and the latch 39 will be described with reference to FIG. When the adjusting screw 26 whose head 26a is held is screwed into the partition 21c of the base 21a, the adjusting screw threaded portion 25c of the conductor fitting 25 is rotated about the fulcrum X of the conducting portion 25a.
Displaced in the direction of arrow P. For this reason, the conducting portion 25a and the bimetal 24 of the conductor fitting 25 move clockwise from the position indicated by the two-dot chain line around the fulcrum X to the position indicated by the solid line, and a displacement amount B is generated, thereby causing the free end 24a of the bimetal 24 to move.
The gap A between the latch and the latch 39 can be adjusted.

Further, as shown in FIG. 3, when adjusting the gap A, no stress is generated in the bimetal 24 and the joint 25b between the bimetal 24 and the conductor fitting 25. Therefore, it is necessary to consider the elastic limit of the bimetal 24. Not
As for the strength of the joining portion 25b, there is no need to use brazing using a brazing material in consideration of mechanical strength, so that welding cost can be reduced.

Further, at the fulcrum X of the conductor fitting 25, it is possible to secure a sufficient distance between the fulcrum X of the conductor fitting 25 and the adjusting screw threaded portion 25c into which the adjusting screw 26 is screwed. Large displacement amount B can be secured without applying stress to the substrate. Therefore, even when the rated current is applied such that the gap A between the bimetal 24 and the trigger piece 39c of the latch 39 is small and thus the displacement B is large, the time limit can be easily adjusted. Note that this adjustment
The bending angle of the conductor fitting 25 is changed by pulling the adjustment screw threaded portion 25c in the direction of the arrow P. The free end 24a of the bimetal 24 is displaced by this bending angle. However, the adjustment in the direction opposite to the direction of the arrow P is performed within the range of the elastic limit of the conductor fitting 25.

Embodiment 2 In the first embodiment, the direct heat type thermal trip mechanism has been described. However, the present invention can be implemented in an indirectly heated thermal trip mechanism. In addition, depending on the configuration of the adjustment screw 26, adjustment in the direction opposite to the direction of the arrow P can be performed. Further, the arc guide portion 25d is formed in a part of the conductor fitting 25, but the arc guide portion 25d is formed by the conductor fitting 2d.
5 may be separated.

[0020]

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

Since no stress is applied to the joint between the bimetal or the bimetal and the conductor fitting, there is no need to consider the elastic limit of the bimetal, and the welding at the joint using brazing material considering the mechanical strength is also required. It is not necessary to perform welding, and general resistance welding that does not require brazing material can be performed, so that welding cost can be reduced.

In addition, since the distance between the fulcrum of the conductor fitting and the adjusting screw threaded portion of the conductor fitting to which the adjusting screw is screwed can be sufficiently secured, a large displacement can be secured without applying a large stress to the fulcrum. Therefore, the time limit can be easily adjusted even when the rated current is applied, in which the gap between the bimetal and the latch is small and the displacement is large.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a circuit breaker according to Embodiment 1 of the present invention.

FIG. 2 is an enlarged perspective view showing a thermal trip mechanism according to the first embodiment of the present invention.

FIG. 3 is an enlarged perspective view showing the thermal trip mechanism according to the first embodiment of the present invention.

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

FIG. 5 is an enlarged side view showing a conventional thermal trip device.

[Explanation of symbols]

21 Insulated housing, 21a base, 21b cover, 2
3 power supply side terminal conductor, 24 bimetal, 24a free end, 25 conductor fitting, 26 adjustment screw, 26a head,
26b Screw part, 27 Thermal release mechanism, 29 Fixed contact, 30 Movable contact, 31 Arm, 40 Opening / closing mechanism.

Claims (2)

[Claims] An opening / closing mechanism for opening / closing a movable contact with respect to a fixed contact, and a thermodynamic device having a bimetal bent by a circuit current and tripping the opening / closing mechanism when the circuit current exceeds a predetermined value. A circuit breaker having a tripping mechanism, a terminal fitting for supplying the circuit current, and an insulating housing in which the two mechanisms and the terminal fittings are disposed. The trip operating point of the bimetal is fixed by fixing the bimetal to the conductor fitting formed so that the bending angle can be changed, and changing the bending angle of the conductor fitting using an adjusting screw that engages with the conductor fitting. A circuit breaker characterized by adjusting. 2. The adjusting screw has a head held on a wall surface of the insulating housing so that the adjusting screw can be adjusted from an outer surface of the insulating housing, and a screw portion is screwed to the conductor fitting. The circuit breaker according to claim 1, wherein