JPH03192629A - Thermal protector - Google Patents

Abstract

PURPOSE:To prevent conductance between contact points from becoming unstable even under vibration and shocks usually encountered by electric appliances by constantly pressing a thermally responding element plate by a tongue attached to a movable electrode plate. CONSTITUTION:Even with a weak spring force of a movable electrode plate 1, a gap is made between a raised portion 1d and a thermally moved element plate 3 and the area from the end to the approximate center of the plate 3 is constantly pressed with a tongue plate 1d. Since a movable contact point 2 is pressed with the end of the plate 3, the contact force between the movable contact point 2 and a fixed contact point 6 is made high so that unstable conductance due to insufficient contact pressure is prevented. Since the base portion 1e and the claw portion 1a of the tongue plate 1b have some gap between the plate 3, repeated returning actions of the plate 3 is not hindered. This prevents conductance between contact points from becoming unstable even under vibration and shocks usually encountered by electric appliances.

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 protector to prevent burnout of electrical equipment due to abnormal heat generation and overcurrent. , especially regarding small thermal protectors.

Conventional technology FIG. 4(a) shows a conventional thermal protector.

(bl, (C1) is known (Japanese Unexamined Patent Publication No. 189520/1989).

That is, a movable contact 14 is fixed to the tip of a movable electrode plate 13 having spring properties, and a thermally responsive element plate 15 is fixed and integrated to the back surface of the movable electrode plate 13 to form a movable electrode body. This fixation is achieved by inserting the thermally responsive element plate 15 into a portion surrounded by the support parts 13a, 13b, and 13c of the movable electrode plate 13, positioning it on the back surface of the movable electrode plate 13, and caulking the support parts 13a and 13b. carried out by In this case, the thermally responsive element plate 15 is designed to be able to move with a slight margin with respect to the support portions 13a, 13b13c of the movable electrode plate 13 so that the reversal and return operations of the thermally responsive element plate 15 are not hindered. It has become. Further, the welded portion 13d of the movable electrode plate 13 is fixed to the movable lead wire 16 to form a movable electrode body. On the other hand, the fixed contact 17 is fixed to the fixed lead wire 18 to form a fixed electrode body, these electrode bodies are positioned so that the movable contact 14 and the fixed contact 17 face each other, and are integrated with a glass bead 19. Configure the mount body. This mount body is housed in a glass container 20, which is filled with an inert gas such as nitrogen, and the ends of the glass container 20 are heated and sealed.

The thermal protector having such a configuration is attached to a motor or the like, and the thermally responsive element plate 15 performs a reversal return operation in response to an abnormal temperature rise and overcurrent, and the movable electrode plate 13 responds to the abnormal temperature rise and overcurrent. It has the function of opening and closing the movable contact 14 and the fixed contact 17 by operating, thereby preventing burnout of the motor, etc.

Problems to be Solved by the Invention When a thermal protector having such a structure is miniaturized, the volume of the container becomes smaller, and therefore, the structural parts are required to be miniaturized. In particular, if the thermally responsive element plate 15, which is the heart of the thermal protector, is made smaller, the repulsive force of the reverse and return operation of the thermally responsive element plate 15 will also be weakened, and the spring force of the movable electrode plate 13 will inevitably have to be weakened. . As a result, since the contact pressure between the movable contact 14 and the fixed contact 17 becomes low, there is a serious drawback in that even when the electrical equipment is operating normally, normal vibrations and shocks may cause electrical continuity to become unstable.

The present invention was made to solve these problems associated with a compact structure, and provides a high-quality compact thermal protector that does not cause instability in continuity even when used in motors, fluorescent lamp ballasts, etc. It is something to do.

Means for Solving the Problems The thermal protector of the present invention has a movable electrode body having a spring property and having a movable electrode plate having a movable contact fixed to its tip, and a fixed contact that comes into contact with and separates from the movable contact. A mount body in which a fixed electrode body having a fixed electrode plate fixed to the tip thereof is provided facing each other, and a supporting portion of the movable electrode body and the fixed electrode body are integrated with an insulating block is housed in a container, On the claw portion formed by folding the tip of the movable electrode plate to the back side of the movable electrode plate and the tongue piece formed by cutting approximately the center of the movable electrode plate and protruding to the back side of the movable electrode plate. By locking both ends of the thermally responsive element plate, the thermally responsive element plate is provided along the back surface of the movable electrode plate, and the tongue portion extends from the end of the thermally responsive element plate to approximately the center. The part that extends is pressed with a predetermined pressure.

Function: With the miniaturization of thermal protectors, the present invention has developed a tongue protruding from the back side of the movable electrode plate in order to prevent a decrease in the contact pressure between the movable contact and the fixed contact caused by weakening the spring force of the movable electrode plate. A part of the thermally responsive element plate provided along the back surface of the movable electrode plate is always kept in a pressurized state with a predetermined pressure by the piece. As a result, since the tip of the movable electrode plate is constantly pressed through the thermally responsive element plate, the contact pressure between the movable contact and the fixed contact increases, making it possible to stabilize conduction.

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

As shown in FIG. 1(a), Tbl, FIG. 2, and FIG. The movable contact 2 is fixed by welding, and a snap-action thermally responsive element plate 3 made of bimetal is provided along the back surface of the movable electrode plate 1. In this case, both ends 3 of the thermally responsive element plate are connected to the movable electrode plate 1
It is locked by a claw part 1a formed by folding the tip of the movable electrode plate 1 back to the back side thereof, and a tongue part 1b formed by cutting into the approximate center of the movable electrode plate 1 and protruding to the back side thereof. Further, the movable electrode plate 1 is provided with a dowel portion 1d in the center, and a fixed portion 1c at the other end of the dowel portion is bent at an appropriate angle in the opposite direction to the tongue portion 1b.

The fixed part 1c of the movable electrode plate 1 is welded to the tip of the movable electrode substrate 4, and the fixed contact 6 made of silver is fixed by welding to the tip of the fixed electrode plate 7 facing the fixed part 1c. The other end is welded to the tip of the fixed electrode substrate 8, and the movable electrode substrate 4 and the fixed electrode substrate 8 are welded to each other approximately in the center so that the movable contact 2 and the fixed contact 6 come into contact with each other with a predetermined pressure. The supporting portion is integrated with an insulating block 10 made of PBT resin or the like. Further, a movable covered lead wire 5 is welded to the other end of the movable electrode substrate 4, and a fixed covered lead wire 9 is welded to the other end of the fixed electrode substrate 8 to form a mount body.

This mount body is made of PBT with an opening at one end.
Approximately 18 mm long, approximately 7 mm wide, and approximately 4 mm thick, made of resin etc.
The movable covered lead wire 5 and the fixed covered lead wire 9 are led out from the opening of the container 11, and the opening of the container 11 is filled with a pair 12 made of epoxy resin or the like. It is sealed.

In the small thermal protector having such a structure, even if the spring force of the movable electrode plate 1 is weakened, there is still a gap between the dowel portion 1d and the thermally responsive element plate 3, and the tongue portion 1b provides a gap between the dowel portion 1d and the thermally responsive element plate 3. Since the area from the end of the thermally responsive element plate 3 to approximately the center is constantly pressurized with a predetermined pressure, the tip of the thermally responsive element plate 3 pushes the movable contact 2. The contact pressure of the fixed contact 6 can be increased, and unstable conduction due to insufficient contact pressure can be prevented. In addition, the root portion 1e of the tongue portion 1b and the claw portion 1a,
A slight margin is provided for the thermally responsive element plate 3,
This is done so that there is no problem in the reversal and return operation of the thermally responsive element plate 3.

On the other hand, in the event of an abnormality in electrical equipment such as a motor, the thermally responsive element plate 3 is inverted as shown in FIG.
comes into contact with three points of the movable electrode plate 1: the claw portion la, the dowel portion 1d, and the base portion 1e, and the movable electrode plate 1 moves in accordance with the reversal movement of the thermally responsive element plate 30, and is movable from the fixed contact 6. Contact point 2 will be opened. At this time, the tongue portion 1b does not press the thermally responsive element plate 3 and remains a free tongue.

Since this thermal protector does not require the addition of new parts, it is possible to obtain the same quality and performance as conventional ones, despite being inexpensive and small.

As described in detail, the present invention allows even if the thermal protector becomes smaller, by always pressurizing the thermally responsive element plate with the tongue piece provided on the movable electrode plate, the movable contact and the fixed contact can be indirectly connected. To provide a low-cost, high-quality, compact thermal protector that can increase contact pressure and prevent unstable conduction of contacts even when normal vibrations and shocks occur during normal operation of electrical equipment. It is possible.

[Brief explanation of drawings]

FIG. 1 (al, (bl) is a partially cutaway front view and side view of a thermal protector according to an embodiment of the present invention, and FIG.
The figure is a perspective view of the movable electrode plate of the present invention, FIG. 3 is a partially cutaway side view of a thermally responsive element of a thermal protector according to an embodiment of the present invention during reversal operation, and FIG.
b), (C1 is a partially cutaway front view, a side view thereof, and a perspective view of a movable electrode plate of a conventional thermal protector. 1...Movable electrode plate, 1a...Claw portion , 1b...tongue part, 1d...dowel part, 2...movable contact, 3...thermally responsive element plate, 6...・Fixed contact, 10... Insulation block, 11... Container.

Claims (1)

[Claims] A movable electrode body having a spring property and having a movable electrode plate having a movable contact fixed to its tip, and a fixed electrode body having a fixed electrode plate having a fixed contact fixed to its tip that moves toward and away from the movable contact. A mount body that is provided facing each other and that integrates the supporting parts of the movable electrode body and the fixed electrode body with an insulating block is housed in a container, and the tip of the movable electrode plate is folded back to the back side of the movable electrode plate. By locking both ends of the thermally-responsive element plate with the claw portion formed by the above-described method and the tongue portion formed by cutting into the approximate center of the movable electrode plate and protruding toward the back side of the movable electrode plate, the above-mentioned The thermally responsive element plate is provided along the back surface of the movable electrode plate, and the tongue portion presses a portion of the thermally responsive element plate from the end to approximately the center with a predetermined pressure. Thermal protector.