JPH03127422A - Thermal protector - Google Patents

Abstract

PURPOSE:To prevent sparking and improve safety by forming a constructed part having a function of electric fuse in at least a part of a movable and a fixed electrode plates of a mount body housed in a container and burying the constructed part in an insulating block. CONSTITUTION:A thermal protector consists of a snap-action-type heat sensitive element composed of a contrarotating-type trimetal 3 to which a movable con tact 2 is welded in the tip part, placed in opposition to a movable electrode welded to one end part 12a of a movable electrode plate 12 in which a constrict ed part 12c having fuse function is formed in the center, and a fixed electrode body prepared by welding a contact plate 7, to the front end of which a fixed contact 6 is welded to one end part 5a of a fixed electrode plate 5. The constrict ed part 12c is buried in an insulating block 9. This mount body is housed in a container 10 and its open mouth is sealed. When large current flows, the constricted part 12c is melted and cut so that arc generation is prevented. Since the constricted part 12c is sealed in the block 9, sparking is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used in various electrical equipment, such as motors or fluorescent lamp ballasts, and is used as a thermal protection device to prevent burnout of electrical equipment due to abnormal heat generation and excessive current. The present invention relates to a protector, particularly a small thermal protector.

Conventional technology A conventional small thermal protector is shown in Fig. 2(a).

It has a configuration as shown in tb+. That is, a movable electrode body is formed by welding an inverted trimetal 3 with a movable contact 2 welded to its tip to one end 1a of a movable electrode plate 1, and a fixed electrode plate includes a contact plate 7 with a fixed contact 6 welded to its tip. A fixed electrode body welded to one end 5a of the movable electrode plate 1 and the fixed electrode plate 5 is provided facing each other so that the movable contact 2 and the fixed contact 6 are in contact with each other with a predetermined contact pressure, and a fixed electrode body is welded to one end portion 5a of the movable electrode plate 1 and the fixed electrode plate 5. The movable covered lead wire 4 is welded to the other end 1b of the movable electrode plate 1, and the fixed covered lead wire 4 is welded to the other end 5b of the fixed electrode plate 5. The wire 8 is welded to form a mount body. Then, this mount body is stored in a container IO made of resin having an opening at one end.
The movable covered lead wire 4 and the fixed covered lead wire 8 are led out from the opening of the container 10, and the opening of the container 10 is sealed with a filler 11 made of resin.

The thermal protector having such a configuration is attached to a motor, etc., and in response to an abnormal temperature rise and excessive current, the reversible trimetal 3 performs an inverting return operation.
It has the function of opening and closing the movable contact 2 and fixed contact 6 to prevent burnout of the motor, etc.

Problems to be Solved by the Invention This type of thermal protector must be able to withstand large currents, especially when used in motors, fluorescent lamp ballasts, and the like. However, when this structure is miniaturized, the volume of the container becomes smaller, and as a result, the internal pressure of the container increases due to the arc heat caused by the intense arc between the contacts when energizing at a large current, causing the container to break and cause the container to leak out. A serious drawback was that it was impossible to prevent the fire from igniting.

The present invention was made to solve these problems associated with a compact structure, and provides a highly safe compact thermal protector that will not cause a fire when used in motors, fluorescent lamp ballasts, etc. This is what we provide.

Means for Solving the Problems The thermal protector of the present invention is provided with a movable electrode body having a movable electrode plate and a fixed electrode body having a fixed electrode plate facing each other, and wherein the movable electrode plate and the fixed electrode A mount body in which the plate is integrated with an insulating block is housed in a container, and at least one of the movable electrode plate and the fixed electrode plate is formed with a constriction having a current fuse function. is embedded in the insulating block.

Effect of the Invention In the present invention, when a large current flows through the thermal protector, the constricted portion having a current fuse function is fused, so that it is possible to prevent the occurrence of intense arcing between the contacts. However, when the constriction is fused, an explosive arc is generated between both ends of the electrode plate where the constriction is formed. However, this arc is contained by an insulating block. As a result, ignition outside the container can be prevented.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in Figure 1+a) and (bl), the thermal protector according to the embodiment of the present invention has a snap-axle thermally responsive element made of an inverted trimetal 3 with a movable contact 2 welded to its tip, and a fuse in the center. A movable electrode body is welded to one end 12a of a movable electrode plate 12 provided with a functional constriction IC, and a contact plate 7, which has a fixed contact 6 welded to its tip, is welded to one end 5a of the fixed electrode plate 5. The movable contact 2 and the fixed electrode body 6 are provided facing each other so that the movable contact 2 and the fixed contact 6 are in contact with each other with a predetermined contact pressure.

Approximately central portions of the movable electrode plate 12 and the fixed electrode plate 5 are embedded and integrated in an insulating block 9 made of resin. In this case, a constricted portion 12c having a current fuse function is provided at the center of the movable electrode plate 12, and this constricted portion is embedded within the resin block 9 so as to be located at the central portion. The movable covered lead wire 4 is welded to the other end 12b of the movable electrode plate 12, and the fixed covered lead wire 8 is welded to the other end 5b of the fixed electrode plate 5. The mount body is constructed as described above. This mount body is made of resin with an opening at one end, and has a length of 16.4 mm+ and a width of 6 mm. It is stored in a container 10 with an OM thickness of 3.1 mm, the movable covered lead wire 4 and the fixed covered lead wire 8 are led out from the opening of the container 10, and the opening of the container 10 is filled with epoxy resin or the like. It is sealed with agent 11.

In such a thermal protector, for example, 200A
When a large current of , because it is embedded in the insulating block 9, the arc generated between the one end 12a and the other end 12b when the constricted part 12c is fused can be contained in the insulating block 9, thereby preventing ignition to the outside of the container 10. can be avoided. Furthermore, this thermal protector does not require the addition of new parts and does not require any change in the assembly process, so it can be obtained at low cost.

Hmm, in the above embodiment, the case was explained in which the movable electrode plate was provided with a constriction having a current fuse function.
Of course, the constricted portion may be provided on the fixed electrode plate, or may be provided on both plates.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention provides a movable electrode body having a movable electrode plate and a fixed electrode body having a fixed electrode plate facing each other, and wherein the movable electrode plate and the fixed electrode plate A mount body that is integrated with an insulating block is housed in a container, and at least one of the movable electrode plate and the fixed electrode plate is formed with a constriction having a current fuse function, and this constriction is connected to the Since it is embedded in an insulating block, it is possible to prevent the occurrence of arc between the contacts by melting the constriction of the electrode plate under normal conditions at large currents, and also prevent the occurrence of arc between the ends of the electrode plate when the constriction is fused. Since the arc can be pierced with an insulating block, it is possible to provide an extremely safe and compact thermal protector that can avoid ignition outside the container at a low cost.

[Brief explanation of the drawing]

Fig. 1 fal, (b) is a partially cutaway front view and side view of a thermal protector which is an embodiment of the present invention, Fig. 2
Figures fat and fbl are a partially cutaway front view and a side view of a conventional thermal protector. 2...Movable contact, 2...Trimetal,
5...Fixed electrode plate, 6...Fixed contact, 9...Insulation block, 10...
Container, 12...Movable electrode plate, 12c...
...constriction.

Claims (1)

[Claims] A mount body in which a movable electrode body having a movable electrode plate and a fixed electrode body having a fixed electrode plate are provided facing each other, and the movable electrode plate and the fixed electrode plate are integrated with an insulating block is placed in a container. A thermal protector, characterized in that a constricted portion having a current fuse function is formed in a part of at least one of the movable electrode plate and the fixed electrode plate, and the constricted portion is embedded in the insulating block.