JPH089880Y2 - Switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a switch for protecting an electronic device from excessive current, and particularly to improvement of its reliability.

[Prior Art] A switch is inserted between electronic devices in order to protect them from excessive current. A cross-sectional structure of such a switch is shown in FIG. The terminal 12 is connected to the bimetal plate 4, and the terminal 11 is connected to the movable spring member 6. In the normal state, as shown by the solid line, the movable spring member 6 is in the first fixed state, and electric current is supplied to the electronic device (not shown).

Next, when an excessive current flows, the bimetal plate 4 generates heat,
It begins to warp in the tripping direction P. Along with this, the movable terminal 6c of the bow-shaped snap spring 6b gradually moves upward. When the movable terminal 6c crosses the critical line x of the snap spring 6b, the snap spring 6b reverses to perform a trip operation, whereby the movable contact member 16 is stopped by the second fixed point 15 until the movable spring member is stopped. 6 momentarily moves and reaches a second stable state indicated by a virtual line. Ie bimetal contacts
Lost contact with 14. As a result, the supply of excessive current to the electronic device is stopped, and the electronic device is protected.

[Problems to be Solved by the Invention] However, the conventional switch as described above has the following problems.

When the excessive current is abnormally large due to a short circuit or the like, the warp of the bimetal plate 4 is large and sharp. Therefore, even after the movable spring member 6 performs the trip operation, the bimetal plate 4 tends to warp. Therefore, as shown in FIG. 5, the bimetal contact 14 and the movable contact 16 do not separate even after the trip operation, and an excessive current continues to flow.
In this case, there is a problem that the circuit is not interrupted and the electronic device cannot be protected. Furthermore, the bimetal plate 4 and the like may even catch fire.

An object of the present invention is to solve the above problems and to provide a switch which can surely perform a breaking operation even when an abnormally large current is generated.

[Means for Solving the Problems] The switch according to the present invention has a stopper structure for preventing the bimetal plate from being warped in the trip direction after the trip mechanism is activated by the warping of the bimetal plate when an abnormally large current is generated. The feature is that it is provided.

[Operation] Even when an abnormally large current is generated, the stopper structure prevents the bimetal plate from warping more than necessary.

[Embodiment] A cross section of a switch 1 according to an embodiment of the present invention is shown in FIG. In this embodiment, the tip portion of the base 18 is formed in a convex shape to provide a locking portion 18a, which has a stopper structure. The terminal 12 is connected to the bimetal plate 5, and the terminal 11 is connected to the movable spring member 6. A movable contact 16 is provided at the tip of the movable spring member 6, and a bimetal contact 14 is provided at the tip of the bimetal plate 5. In the normal state, the movable spring member 6 is in the first fixed state,
The 16 and the bimetal contact 14 come into contact with each other, and an electric current is supplied to an electronic device (not shown).

Next, when an abnormally large current flows, the bimetal plate 5 generates heat and starts to warp in the trip direction P. Along with this, the movable terminal 6c of the bow-shaped snap spring 6b gradually moves upward. When the movable terminal 6c crosses the critical line x of the snap spring 6b, the snap spring 6b is inverted and trips. As a result, the movable spring member 6 instantaneously moves until the movable contact 16 is stopped by the second fixed point 15, and reaches the second stable state. That is, the contact with the bimetal contact 14 is cut off as shown in FIG. At this time, the warping of the bimetal plate 5 due to the excessive current is caused by the locking portion 18
Stopped by a. That is, after the movable spring member 6 trips due to the warping of the bimetal plate 5, the tip 5a of the bimetal plate is prevented from warping by the locking portion 18a (see FIG. 2). Therefore, even when an abnormally large excessive current flows due to a short circuit or the like and the bimetal plate 5 largely warps, the bimetal contact 14 and the movable contact 16 can be reliably separated.

After removing the cause of the excessive current, the following operation is performed when the electronic device is energized again. First, the temperature of the bimetal plate 5 is lowered by the separation of the bimetal contact 14 and the movable contact 16, and the bimetal plate 5 naturally returns to the state of FIG. However, the movable spring member 6 remains in the second stable state. Therefore, the push button member 3 is pushed down to return the movable spring member 6 to the first stable point shown in FIG. As a result, the bimetal contact 14 and the movable contact 16 come into contact with each other again, and the power supply to the electronic device is restarted.

In addition, in the above-described embodiment, the locking portion 18a that comes into contact with the tip 5a of the bimetal plate 5 is provided. However, as shown in FIGS. 3A and 3B, the detection unit 30 may be provided on the front side of the bimetal contact 14 to form a stopper structure. Note that FIG. 3b is viewed from the direction of arrow A in FIG. 3a.

In the conventional switch, when an excessive current is generated, which is not an abnormality, if tripping and closing are repeated without removing the cause of the excessive current, as shown in Fig. It may be in the same state as when current flows. However, in this embodiment, the shutoff operation is surely performed even in the above case.

Further, even if the trip mechanism fails, the bimetal contact 14 and the contact 16 do not come into contact with each other.

[Effects of the Invention] The switch according to the present invention is provided with a stopper structure for preventing the bimetal plate from being warped in the tripping direction after the trip mechanism is activated by the warping of the bimetal plate when an abnormally large current is generated. It has a feature. Therefore, it is possible to reliably perform the breaking operation even with an abnormally large excess current, and there is no fear of causing an accident such as ignition.
That is, it is possible to provide a highly reliable switch.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a normal state of a switch according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a state of the switch of FIG. 1 when an abnormal excessive current is generated, FIG. FIG. 3b is a view showing another example of the stopper structure, FIG. 4 is a cross-sectional view for explaining a normal state and a breaking operation in the conventional switch, and FIG. 5 is a cross-sectional view when an abnormal excessive current is generated. It is sectional drawing of the conventional switch. 14 …… bimetal contact 5 …… bimetal plate 16 …… movable contact 6 …… movable spring member 18a …… locking part

Claims (1)

[Scope of utility model registration request] 1. A bimetal plate on which a bimetal contact is formed, a movable member having a movable contact that comes into contact with and separates from the bimetal contact, the bimetal contact and the movable contact are brought into contact with each other in a normal state, and a bimetal is produced when an excessive current is generated. In a switch equipped with a trip mechanism that separates the bimetal contact from the movable contact by the warp in the trip direction due to the heat generated by the plate, the bimetal plate is activated after the trip mechanism operates due to the warp of the bimetal plate when an abnormally large current is generated. A switch which is provided with a stopper structure for preventing the warp of the pull-out method.