JPH0536737U - Circuit breaker - Google Patents

Abstract

(57) [Abstract] [Purpose] A terminal board that constitutes a trip device of a circuit breaker,
To simplify the joining of the heating resistor and the bimetal. [Structure] The heating resistor 15 and the bimetal 17 are surface-welded by spot welding at the first joint surface of the heating resistor 15 and the lower end of the bimetal 17. Also, the terminal board 1
4 and the heating resistor 15 are surface-joined by spot welding on the second joining surface formed on the lower end of the heating resistor 15 and the lower end of the terminal plate 14. In this case, a small electric current and a small pressurizing force are sufficient for spot welding.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a circuit breaker having an improved joint structure of a terminal plate, a heating resistor and a bimetal.

[0002]

[Prior Art]

 In the circuit breaker, as shown in FIG. 3, one terminal plate 1 and the opening / closing contact are connected via a heating resistor 2, and a bimetal 3 is attached to this heating resistor 2 to connect it to the main circuit. There is a device in which when the overcurrent flows, the bimetal 3 is bent and displaced due to the heat generation of the heating resistor 2, so that the opening / closing contact is tripped.

As shown in the figure, in this device, a bimetal 3 is sandwiched between a terminal plate 1 and a heating resistor 2, and these three members are integrally formed by spot welding, for example, with their lower ends aligned. I am trying to join. The terminal plate 1 is bent in a substantially L shape, and the bimetal 3 and the heating resistor 2 are disposed on the right side of the lower end portion of the terminal plate 1 by penetrating the through holes 1a formed in the terminal plate 1. It is supposed to be done. At this time, the through hole 1a is formed in a long hole shape extending to the lower part so as not to hinder the bending operation of the bimetal 3.

[0004]

[Problems to be solved by the device]

 However, in the above configuration, since the terminal plate 1, the heating resistor 2 and the bimetal 3 are joined in a three-layer superposed state, a relatively large current is required and a large load is required when performing spot welding work. Pressure is needed. As a result, the equipment for spot welding becomes large in size, and the terminal plate 1 and the heating resistor 2 may be deformed or melted. In addition, since the area of the joint surface of the terminal board 1 is reduced by the through hole 1a provided to allow the bending operation of the bimetal 3, the stability and reliability of the joint are deteriorated.

In addition to spot welding, for example, brazing may be performed, but in this case, workability is poorer than in spot welding, and workability is poor.

The present invention has been made in consideration of the above circumstances, and an object thereof is to provide a circuit breaker capable of simplifying the joining of a terminal plate, a heating resistor and a bimetal.

[0007]

[Means for Solving the Problems]

 The circuit breaker of the present invention comprises a heating resistor connected between the main circuit conductor and the terminal board, and a bimetal that bends according to the amount of heat generated by the heating resistor. The opening and closing contacts in the main circuit are tripped by the curved displacement of the bimetal when flowing, and the heating resistor and the terminal plate are joined at their respective ends, and the bimetal and It has a characteristic when it is joined to the heating resistor.

[0008]

[Action]

 According to the above means, the heating resistor and the terminal plate are joined at their respective ends to electrically connect the two. Then, by joining the bimetal and the heating resistor, they are thermally connected.

In this case, since the heating resistor and the terminal plate are connected in a so-called two-layer structure, the gap between the electrodes becomes narrower in spot welding than in the case of the three-layer structure. Therefore, a comparatively small current is sufficient and the pressing force is also small. Further, since the bimetal is not directly joined to the terminal board, but the bimetal and the heating resistor are also joined in a two-layer structure, the spot is applied with a small current and a small pressing force. Welding can be performed.

Therefore, it is possible to join the terminal plate, the heating resistor and the bimetal by spot welding without the need for large-scale equipment and without the risk of deformation and melting. As a result, the three members can be easily joined. Can be planned.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. First, the overall configuration of the circuit breaker according to this embodiment will be briefly described. Although not shown in detail, the main body 11 of the circuit breaker includes a rectangular box-shaped case 12 made of an insulating material, and an opening / closing contact composed of a fixed contact and a movable contact, an opening / closing mechanism for opening / closing the opening / closing contact, It comprises a tripping device 13 (see FIG. 1) for forcibly tripping the switching contacts when an overcurrent flows in the main circuit, an arc extinguishing device, and the like.

Terminal plates 14 (only one of which is shown) are provided at both ends of the case 12, respectively, so that the main body 11 is arranged in series in the energizing path of the load by these terminal plates 14. Is becoming Of these, one (not shown) terminal plate (power supply side) is connected to the fixed contact, and the other (load side) terminal plate 14 has a heating resistor 15 and a main circuit conductor 16 described later. And is connected to the movable contact via, thereby forming a main circuit.

Now, the trip device 13 will be described. As shown in FIG. 1, the trip device 13 includes a heating resistor 15 connected to the terminal plate 14, a bimetal 17 attached to the heating resistor 15, and a trip actuation plate for operating the opening / closing mechanism. It is composed of 18 etc.

As shown in FIG. 2, the terminal plate 14 projects rightward from the wall surface of the case 12 and has a connecting portion 14a to which a load line is connected, and extends from the left end of the connecting portion 14a at a substantially right angle downward. It integrally has a hanging portion 14b, and is in the form of a side L-shaped plate. A rectangular through hole 19 is formed in the terminal plate 14 from the connecting portion 14a to the hanging portion 14b. A screw hole 20 for mounting a terminal screw (not shown) for connecting the load wire is formed in a substantially central portion of the connecting portion 14a.

The heating resistor 15 has a vertically long rectangular plate shape as a whole, and a lower end portion thereof is bent into a shape having two steps in the left direction in the drawing. As a result, as shown in FIG. 2, a first joint surface 15a protruding leftward in the drawing is formed at a portion of the heating resistor 15 near the lower end thereof, and the first joining surface 15a is formed at the lower end of the heating resistor 15. A second joint surface 15b is formed further protruding leftward from the joint surface 15a. Then, as will be described later in detail, the lower end portion of the bimetal 17 is joined to the first joint surface 15a, and is joined to the terminal board 14 at the second joint surface 15b. Is becoming The main circuit conductor 16 is connected to the upper end of the heating resistor 15.

The bimetal 17 has a vertically long plate shape, and an adjusting screw 21 and a nut 22 are provided at an upper end portion thereof, and a tip end portion of the adjusting screw 21 faces the trip operating plate 18. .. As a result, when an overcurrent flows in the main circuit, the bimetal 17 is bent and deformed to the left in the figure due to the heat generation of the heating resistor 15, and the adjusting screw 21 presses the trip operating plate 18, whereby the opening / closing mechanism is opened. Is operated to trip the switching contact.

Next, a procedure for joining the terminal board 14, the heating resistor 15 and the bimetal 17 will be described. First, the heat generating resistor 15 and the bimetal 17 are surface-welded by spot welding at the first joint surface 15 a of the heat generating resistor 15 and the lower end portion of the bimetal 17. As a result, the two are thermally connected. Then, the terminal plate 14 and the heating resistor 15 are surface-joined by spot welding at the second joint surface 15b and the lower end portion of the hanging portion 14b of the terminal plate 14 with their lower ends aligned.

At this time, the heating resistor 15 and the bimetal 17 are arranged on the right side of the hanging portion 14b of the terminal plate 14 so as to penetrate the through hole 19 in the vertical direction. The bimetal 17 is arranged in a gap portion formed by a step between the first joint surface 15a and the second joint surface 15b of the heat generating resistor 15, and is curved and deformed leftward by the through hole 19. Is allowed.

According to the above configuration, since the terminal plate 14 and the heating resistor 15 are connected in a so-called two-layer structure, the spot welding is performed between the electrodes as compared with the case of the three-layer structure. The intervals are narrowed, so a relatively small current is required and the applied pressure is also small. Further, the bimetal 17 is not directly joined to the terminal board 14, but the bimetal 17 and the heating resistor 15 are also joined in a two-layer structure, so that a small current and a small pressurizing force are applied. Spot welding can be performed with.

Therefore, unlike the conventional equipment that requires large-scale equipment and is likely to be deformed and melted, a small-scale equipment can be used and there is no fear of deformation and melting, and the terminal board 14 The heat generating resistor 15 and the bimetal 17 can be easily joined by spot welding, and as a result, the three members can be easily joined.

Further, particularly in this embodiment, since the bimetal 17 is bonded to the first bonding surface 15a of the heating resistor 15 which is located above the second bonding surface 15b, the bimetal 17 is bent. It is not necessary to form the through hole 19 of the terminal plate 14 for allowing the deformation to extend to the lower end portion of the hanging portion 14b. As a result, the joint surface between the terminal plate 14 and the heating resistor 15 can be made large, and the stability and reliability of the joint between the terminal plate 14 and the heating resistor 15 can be improved as compared with the conventional case.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, a structure in which a protrusion is formed on the first joint surface 15a and the second joint surface 15b of the heating resistor 15 and a recess is formed on the terminal plate 14 and the bimetal 17 corresponding to the protrusion. If so, the bonding strength can be improved and the positioning in the bonding work becomes easy.

Further, the lower end portion of the heating resistor 15 is merely bent into a shape having a step difference, and instead, the lower end portion of the terminal plate 14 has a step difference with the rightward direction. The terminal plate 14 and the heat generating resistor 15 may be bent to be surface-bonded at their lower end portions.

[0024]

[Effect of the device]

 As is clear from the above description, in the circuit breaker of the present invention, since the bimetal and the terminal plate are joined to the heating resistor in different configurations, each joining portion has a two-layer structure. The terminal plate, heating resistor, and bimetal can be easily joined by spot welding, which has the excellent effect of simplifying the joining of the three.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a trip device portion of a circuit breaker showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a bimetal, a heating resistor, and a terminal plate.

FIG. 3 is a view corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

13 is a tripping device, 14 is a terminal plate, 14a is a connecting portion, 1
4b is a hanging portion, 15 is a heating resistor, 15a is a first joint surface, 15b is a second joint surface, 16 is a main circuit conductor, 17 is a bimetal, and 19 is a through hole.

Claims (1)

[Scope of utility model registration request] 1. A heat generating resistor connected between a main circuit conductor and a terminal plate, and a bimetal curved according to the amount of heat generated by the heat generating resistor. When an overcurrent flows in the main circuit. In which the opening / closing contacts in the main circuit are tripped by the curved displacement of the bimetal, the heating resistor and the terminal plate are joined at their respective end portions, and the bimetal and the heating resistor are joined together. A circuit breaker, which is characterized in that