JPS6362057B2 - - 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 electromagnetic relays, if abnormal current such as 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. There was a risk that the equipment would be replaced, the wiring system would be repaired, etc., and there were problems with economic efficiency and safety.

Attempts have also been made to install breakers to prevent these accidents, but the breakers are not suitable 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.

2 and 4 show embodiments of the invention.
In the figure, 1 is a hollow coil frame having flanges 1a and 1b, and the flange 1 on the outer periphery of this coil frame 1 is
A coil 2 is wound between a and 1b, and a plunger 3 is slidably disposed within the hollow portion. Reference numeral 4 denotes a first yoke provided at the upper end of the flange 1a side of the coil frame 1 in the illustrated state, and a permanent magnet 5 is placed in contact with the upper surface of this yoke 4, and the upper surface of the permanent magnet 5 has an L-shaped The inner surface of the bent portion 6a of the second yoke 6 forming the second yoke 6 is placed in contact with the inner surface of the bent portion 6a. Reference numeral 7 denotes a lower yoke disposed opposite to the yoke 6 via the coil 2, coil frame 1, etc., and this yoke 7 and the yoke 6 are connected by a temperature-sensitive magnetic material 8. A bimetal 9 is placed adjacent to and facing the temperature-sensitive magnetic material 8. The base end of the bimetal 9 is fixed on the base 10 together with the base end of a contact spring 11 to be described later, and the free end and the terminal plate 12 which functions as an input or output side terminal are connected by a braided wire 13. has been done. The contact spring 11 is inserted into a slit 14a of an actuator 14 that is integrally provided at the lower end of the plunger 3, and has a movable contact 17 at its tip that can come into contact with and separate from a fixed contact 16 provided on a terminal plate 15. is provided. In addition, 1 in the figure
8 is a cover mounted on the base 10, and 19 is a return spring.

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

Now, as shown in FIG. 2, the plunger 3 is attracted and held by the upper yoke 4 side by the attraction force generated by the excitation of the coil 4, and the contact spring 11 is held at the upper position by the actuator 14 which is integrally interlocked with the plunger 3. Therefore, when the contacts are closed, overcurrent, short-circuit current, etc. may occur in the electrical circuit including the terminal plate 12, the braided wire 13, the heater 9, the contact spring 11, the contacts 17, 16, the terminal plate 15, etc. When the abnormal current flows, the heater 9 is heated, and as the temperature rises, the temperature of the temperature-sensitive magnetic material 8 also rises. As the temperature rises, the magnetic resistance of the temperature-sensitive magnetic material 8 increases, and when it reaches a certain temperature, the magnetic resistance increases rapidly.As shown in FIG. 4, the holding force of the plunger 3 decreases and the plunger 3 returns, the movable contact 17 is separated from the fixed contact 16, and the electrical circuit is interrupted. That is,
Figure 3 shows the relationship between the plunger stroke and the attraction force, where 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 attraction force when an overcurrent occurs, and E is the attraction force in the off state, and when an overcurrent flows, the attraction force acting on the plunger 3 decreases and the plunger 3 returns to its original position, as shown in D.

As described above, according to the present invention, a temperature-sensitive magnetic material is provided in a part of the yoke of a magnetic circuit including a coil, a plunger, a yoke, etc., and a heater is placed close to and facing the temperature-sensitive magnetic material. Since the heater is installed in an electrical circuit that includes an input/output terminal board, contacts, etc., when an abnormal current flows, the attraction and holding force of the plunger decreases and the plunger returns, opening the contacts and cutting off the electrical circuit. Therefore, the cord and load equipment can be reliably protected, and safety can be improved. In addition, since the present invention also has a breaker function, there is no need to provide a separate breaker, making it economical.
It has various effects, such as not having to worry about coordinating with such a breaker.

[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... Yoke, 5... Permanent magnet, 6, 7...
... Yoke, 8 ... Temperature-sensitive magnetic material, 9 ... Heater,
11... Contact spring, 12, 15... Terminal board, 13
... Braided wire, 14 ... Actuator, 19 ...
Spring for return.

Claims (1)

[Claims] 1. A magnetic circuit including a plunger, a coil for attracting and driving the plunger, and a yoke arranged around the coil. A temperature-sensitive magnetic material is provided in a part of the yoke, and the temperature-sensitive magnetic material 1. An electromagnetic relay characterized in that heaters are arranged close to each other so as to face each other, and the heater is provided in an electric circuit including an input/output terminal board, contacts, and the like.