JPS6362058B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic relay having a function of protecting against abnormal current.

Figure 1 shows the structure of a conventional self-holding electromagnetic relay. In the figure, 21 is a base, 22 is a coil, 23 is a coil frame, 24 is a plunger, 2
5 is a yoke, 26 is a permanent magnet, 27 is a magnetic plate, 2
8 is the actuator, 29 is the return coil spring, 3
0 is a contact spring, 31 is a movable contact, 32 is a fixed contact, 33 is a terminal, and 34 is a cover, which operates when voltage is applied to the coil 22, causing the plunger 24 to move.
operates, and the contact spring 30 is activated accordingly, so that the contacts 31 and 32 are turned on. Even if the excitation of the coil 22 is released, the plunger 24 is held by the magnetic flux of the permanent magnet 26, and the on state continues. To turn off contacts 31 and 32,
When a voltage in the opposite direction to that during operation is applied to the coil 22, the plunger 24 returns and the contacts 31 and 32 are turned off.

However, in such an electromagnetic relay, if an abnormal current such as an overcurrent or short circuit current flows through the contacts 31 and 32, the contacts 31 and 32 may become welded, or the cord, load equipment, or relay itself may be damaged or burnt out. This caused problems with economic efficiency and stability, such as equipment replacement and wiring system repairs.

Attempts have also been made to install breakers to prevent these accidents, but the breakers are not appropriate or there is no breaker that can coordinate with the electromagnetic relay, resulting in insufficient protection.

The present invention has been proposed in view of the above points, and its purpose is to reliably detect abnormal current flowing in an electric circuit, return the plunger, and quickly open the contact. According to the electric circuit,
An object of the present invention is to provide an electromagnetic relay having an abnormal current protection function that protects load equipment and the relay itself from damage, burnout, etc.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention. In the figure, 1 is a hollow coil frame having flanges 1a and 1b, and a coil 2 is wound between the flanges 1a and 1b of this coil frame 1. A plunger 3 is slidably disposed within the hollow portion, and a stepped portion 1a' that comes into contact with an end surface of a permanent magnet 5, which will be described later, is provided at the end of the flange 1a. 4 is the upper end of the coil frame 1, that is, the flange 1 in the illustrated state.
This yoke 4 is the first yoke provided on the a side.
A permanent magnet 5 is slidably provided on the upper surface. Further, the inner surface of the bent portion 6a of the second yoke 6 having a U-shape is placed in contact with the upper surface of the permanent magnet 5, and the permanent magnet 5 is arranged between the first yoke 4 and the second yoke 6.
It is slidably disposed between the yokes 6 of the. Reference numeral 7 denotes an L-shaped member whose base end is fixed to one end outside the permanent magnet 5, and an L-shaped bent portion 7 of this member
A bimetal 9 whose base end is fixed to a terminal plate 8 functioning as an input or output terminal is disposed on the inside of the terminal a, facing each other with a slight distance so that they can come into contact with each other. Reference numeral 10 denotes a contact spring whose base end is fixed to a base 11. This contact spring 10 and the bimetal 9 are electrically connected by a braided wire 12, and a terminal plate 13 is attached to the free end of the contact spring 10. A movable contact 15 that can be brought into and out of contact with a fixed contact 14 provided at the front is provided.

Thus, a part of the plunger 3 is projected to the outside through a hole formed in the bent portion 6b of the yoke 6,
An actuator 16 is integrally provided on this protrusion. A slit 16a is formed in the actuator 16, and the contact spring 10 is inserted through the slit 16a so that the contact spring 10 is driven by the actuator 16 which follows the plunger 3 to turn the contact on and off.

In the figure, 17 is a plunger return spring provided between the outer surface of the bent portion 6b of the yoke 6 and the opposing outer surface of the shoulder portion of the actuator 16, and 18 is a cover mounted on the base 11.

Next, the operation of the present invention will be explained.

Now, as shown in FIG. 2, the plunger 3 is moved to the first
When the contact spring 10 is held in the upper position by the actuator 16 which is attracted to and held by the yoke 4 side and is integrally interlocked with the plunger 3, so that the contact is closed, the terminal plate 8, the bimetal 9, and the braided Wire 12, contact spring 10, contacts 15, 14
When an abnormal current such as an overcurrent or a short-circuit current flows through the electrical circuit including the terminal plate 13 and the like, the bimetal 9 is heated and bent outward, that is, to the left in the figure. Therefore, the tip of the bimetal 9 comes into contact with the bent portion 7a of the L-shaped member 7 and presses the L-shaped member 7, so that the permanent magnet 5
is slid outward and pulled out, as shown in FIG. For this reason, the magnetic flux passing through the plunger 3 decreases, and the attraction and holding force of the plunger 3 decreases, so the plunger 3 detaches from the yoke 4 and returns to its original state due to the spring force of the spring 17, and the contacts open and the electric path is closed. will be cut off. In other words, Figure 4 shows the relationship between plunger stroke and suction force.
A is the attraction force when turned on, B is the attraction force of the permanent magnet only,
C is the spring load force, D is the attractive force when the bimetal is activated, and E is the attractive force when the bimetal is turned off.If an abnormal current flows and the permanent magnet 5 is pulled out and its relative position with the yokes 4 and 6 shifts, D As shown in , the suction force acting on the plunger 3 is reduced and the plunger 3 returns to its original position.

As described above, according to the present invention, a bimetal is provided in the electric circuit including the input/output terminal board, contacts, etc., and the permanent magnet placed between the first and second yokes can be slid by the displacement of the bimetal. Therefore, when an abnormal current flows, the suction and holding force of the plunger decreases and the plunger returns, opening the contacts and cutting off the electrical circuit, thereby reliably protecting the cord and load equipment. This has the effect of improving safety. In addition, since the present invention has a breaker function, there is no need to provide a separate breaker, which is economical, and there is no need to worry about coordinating with such a breaker.
It has various effects.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional self-holding electromagnetic relay, FIG. 2 is a sectional view showing an embodiment of the electromagnetic relay according to the present invention, and FIGS. 3 and 4 are explanatory views of the same operation. 1... Coil frame, 2... Coil, 3... Plunger, 4... First yoke, 5... Permanent magnet, 6
... Second yoke, 7 ... L-shaped member, 8, 13
... Terminal board, 9 ... Bimetal, 10 ... Contact spring, 11 ... Base, 12 ... Braided wire, 14 ...
Fixed contact, 15... Movable contact, 16... Actuator, 17... Return spring.

Claims (1)

[Claims] 1 A bimetal is provided in an electric circuit including an input/output terminal board and contacts, and a permanent magnet is made slidable by displacement of the bimetal, and the permanent magnet is connected to a first yoke disposed above the plunger and the plunger. 1. An electromagnetic relay characterized in that the relay is slidably disposed in a hollow part and is disposed between a substantially U-shaped second yoke having a coil wound around the outer periphery of the coil inside the yoke.