JPH0580090B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a temperature switch, and more particularly to a temperature switch that uses a permanent magnet and a temperature-sensitive magnetic material to obtain a large contact capacity.

[Prior Art] As is well known, a reed switch is constructed by enclosing a pair of magnetic leads, which are opposed to each other with a gap in between and serve as contact portions, in a glass container. In this switch, when a required magnetic field is applied and the magnetic flux flowing in the length direction of the magnetic leads reaches a certain value at the contact portion, the magnetic leads come into contact due to magnetic attraction force and close the electrical path. Then, when the magnetic field is removed, the magnetic leads bounce back due to their elasticity, opening an electrical path.

Incidentally, a magnetic field generated by a current flowing through a magnetic lead on which a magnetic attraction force is applied has a function of lowering the magnetic flux density in the length direction of the magnetic lead. Therefore, a phenomenon occurs in which the ampere-turn value for separating the magnetic leads increases in proportion to the magnitude of the applied current. In addition, when the current flowing exceeds a certain level, when the magnetic lead is separated and the current flowing becomes zero, the magnetic flux density of the magnetic lead increases by the amount that had been reduced by the current flowing, and the magnetic attraction force increases again. and the magnetic leads come into contact. This repetition causes electromagnetic chatter. In this way, creating an electrical path due to magnetic attraction is disadvantageous in terms of contact deterioration, and conventional reed switches have the disadvantage that they cannot have a contact capacity above a certain level. Therefore, a temperature switch in which a reed switch is combined with a permanent magnet and a temperature-sensitive magnetic material has not yet had a large contact capacity.

[Purpose of the invention]

An object of the present invention is to provide a temperature switch which is not affected by the magnetic field generated by a current through the use of a permanent magnet and a temperature-sensitive magnetic material, has no contact deterioration, and has a large contact capacity. purpose.

[Structure of the invention]

The present invention comprises an insulating substrate provided with a pair of terminals on one surface, and two terminals provided at intervals on the other surface of the substrate and magnetized in directions perpendicular to the board surface and opposite to each other. a pair of magnetic pieces that are cantilever-supported near the center of each of the magnets and extend between the two magnets at their free ends so as not to overlap each other; and one of the magnetic pieces. a conductive spring plate that is cantilever-supported by the terminal, is connected to one of the terminals, and has a movable contact at its free end;
A movable magnetic piece provided on the spring plate to face the other magnetic piece, a fixed contact provided at a position facing the movable contact and connected to the other terminal, and a side opposite to the substrate. This temperature switch is characterized by comprising a temperature-sensitive magnetic plate having a predetermined Kyrie point and installed over the magnetic pole faces of the two magnets.

〔Example〕

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

FIGS. 1 and 2 are sectional views showing an embodiment of the present invention in a low temperature range (before operation) and a high temperature range (after operation).

In the figure, reference numeral 1 denotes an insulating substrate having an arbitrary shape, for example, a rectangular shape, and a pair of terminals 2 and 2' for connecting an external circuit are attached to the lower surface of the insulating substrate. This substrate 1 is fixed to one end side of a cylindrical case 10 by caulking or the like. 3 and 3' are ferrite columnar permanent magnets magnetized in the length direction and having almost equal magnetic force, and are placed on the substrate 1 with the magnetization direction perpendicular to the surface of the substrate and in opposite directions, and spaced apart from each other. It is installed at Magnetic pieces 4 and 5 are cantilever-supported at different positions near the center of the magnets 3 and 3', and extend in a portion between the magnets 3 and 3' so as not to overlap with each other. A conductive spring plate 6 is attached to the lower surface of the free end of the magnetic piece 4 so as to extend toward the magnetic piece 5 side. The spring plate 6 is electrically connected to one terminal 2 by a conductor 7, and a movable contact 8 is provided on the lower surface of the free end. Further, a movable magnetic piece 9 is fixed to the upper surface of the spring plate 6 such that one end faces a part of the free end of the magnetic piece 5 with a gap in between, and the other end is close to the end face of the magnetic piece 4. There is. A fixed contact 1 is connected by a conductor 11 to a position opposite to the movable contact 8.
2 is provided and electrically connected to the terminal 2'. Reference numeral 13 denotes a rectangular temperature-sensitive magnetic plate having a Curie point corresponding to the operating temperature.
It is fixed by caulking or other methods. This temperature switch is usually installed on the detected part so that the upper surface of the temperature-sensitive magnetic plate 13 serves as a heat-receiving surface.

Next, the effect will be explained. When the temperature of the temperature-sensitive magnetic plate 13 is below its Curie point, the magnets 3, 3' are magnetically short-circuited by the temperature-sensitive magnetic plate 13. Therefore,
The magnetic flux of the magnets 3 and 3' flows to the magnetic piece 4, the movable magnetic piece 9 and the magnetic piece 5, and
A magnetic attraction force is generated between the two. By setting this attractive force to be superior to the elastic force of the spring plate 6, when the temperature of the temperature-sensitive magnetic plate 13 is below its Curie point, the movable magnetic piece 9
is attracted to the magnetic piece 5, and the movable contact 8 is attached to the fixed contact 12.
It is separated from

When the temperature of the temperature-sensitive magnetic plate 13 reaches its Curie point, its magnetism disappears, so that the magnetic short circuit between the magnets 3 and 3' disappears. The magnetic fluxes from the magnets 3 and 3' cancel each other out to maintain balance, and no magnetic flux flows through the magnetic piece 4, the movable magnetic piece 9, and the magnetic piece 5. Therefore, the magnetic attraction force disappears, the movable magnetic piece 9 separates from the magnetic piece 5 due to the elastic force of the spring plate 6, and the movable contact 8 comes into contact with the fixed contact 12.
When the temperature of the temperature-sensitive magnetic plate 13 falls below its Curie point again, the state shown in FIG. 1 is automatically returned. This temperature switch is of the normally open type.

Now, when a large load is connected to terminals 2 and 2' and contacts 8 and 12 are in the closed state (Fig. 2), if a large current flows from terminal 2' to terminal 2, the current is flowing. The magnetic field generated by this is generated in the circumferential direction around the spring plate 6, as shown by the arrows in FIG. This magnetic field changes the magnetization direction of the magnetic piece 4 and the movable magnetic piece 9, and the magnetization component in the length direction of the magnetic piece becomes smaller. As a result, the magnetic attraction force between the magnetic piece 5 and the movable magnetic piece 9 acts to decrease, and the contact force between the contacts 8 and 12 increases accordingly. Furthermore, when the contacts 8 and 12 are opened, the current flow stops and the magnetic density of the movable magnetic piece 9 increases (returns to its original value). Therefore, the magnetic attraction force between the magnetic piece 5 and the movable magnetic piece 9 increases, and the contact separation force increases. In this way, the electromagnetic snapping action caused by the applied current is added to the magnetic snapping action caused by the elastic force of the spring and the magnetic attractive force, making it possible to interrupt a large current without damaging the contacts. In addition, the atmosphere of the contact part is the same as that of case 1.
Although it is conceivable to seal the inside of the 0 with an inert gas, by using AgCdO or the like as a contact material, the atmosphere can also be used.

FIG. 3 shows another embodiment of the invention. The difference from the embodiment shown in FIG. 1 is that the substrate 1 and the magnets 3, 3'
A rectangular magnetic plate 14 having a Curie point sufficiently higher than the Curie point of the temperature-sensitive magnetic plate 13 between the magnetic pole surface of
This is because we have established the following. When the magnetic plate 14 is made of a conductive material, it goes without saying that it is insulated from the terminals 2 and 2'.

This temperature switch is normally closed. That is,
In a low temperature range where the temperature of the temperature-sensitive magnetic plate 13 is below its Curie point, the magnets 3, 3' are short-circuited by both the temperature-sensitive magnetic plate 13 and the magnetic plate 14, forming a completely closed magnetic path. As a result, there is no magnetic flux flowing through the magnetic piece 4 and the movable magnetic piece 9 to the magnetic piece 5, and as shown in FIG. 3, the contacts 8 and 12 are closed by the pressing force of the spring plate 6 and become energized. .

In a high temperature range, that is, when the temperature of the temperature-sensitive magnetic plate 13 is above its Curie point, the magnets 3 and 3' are short-circuited by the magnetic plate 14, and the magnetic piece 5 and the movable magnetic piece are connected in the same manner as described with reference to FIG. The magnetic attraction force generated between the contacts 8 and 12 opens the contacts 8 and 12, cutting off current flow.

In this embodiment as well, since the electromagnetic snapping action caused by the applied current is added to the snapping action caused by the magnetic attractive force, the contact capacity can be increased.

〔Effect of the invention〕

As explained above, the temperature switch according to the present invention utilizes magnetism created by a combination of a permanent magnet and a temperature-sensitive magnetic material, but it does not use a reed switch as a contact point and has a structure in which the magnetic piece is directly attached to the permanent magnet. I'm taking it. Therefore, the area of the magnetic piece can be made larger than when using a reed switch.
The magnetic attraction force between the magnetic piece and the movable magnetic piece can be increased. Furthermore, since the magnetic gap can be increased, a large capacity contact can be achieved. Furthermore, it is easy to create a structure in which the magnetic attractive force of the magnetic piece and the movable magnetic piece acts on the contact opening force, and the spring force acts on the contact closing force, so the magnetic influence of the current is applied to the contact. It is possible to provide a temperature switch that can be used in an advantageous manner and has excellent characteristics.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing the state before and after operation of one embodiment of the present invention, respectively, and FIG. 3 is a cross-sectional view showing another embodiment of the present invention. 1: Insulating board, 2, 2': External circuit connection terminal, 3, 3': Permanent magnet, 4, 5: Magnetic piece, 6:
Conductive spring plate, 8: Movable contact, 9: Movable magnetic piece,
10: Case, 12: Fixed contact, 13: Temperature-sensitive magnetic plate, 14: Magnetic plate.

Claims (1)

[Claims] 1. An insulating substrate provided with a pair of terminals on one surface, and an insulating substrate provided at a distance on the other surface of the substrate, with magnetization directions perpendicular to the board surface and opposite to each other. two permanent magnets, each of which is cantilevered near the center of the magnet, and a pair of magnetic pieces extending between the two magnets so that their free ends do not overlap; a conductive spring plate that is cantilever supported on one of the pieces, is connected to one of the terminals, and has a movable contact at its free end, and is provided on the spring plate so as to face the other magnetic piece. a movable magnetic piece, a fixed contact provided at a position facing the movable contact and connected to the other terminal, and a required Curie point constructed on the magnetic pole faces of the two magnets on the opposite side to the substrate. A temperature switch characterized by comprising a temperature-sensitive magnetic plate having a temperature-sensitive magnetic plate. 2. The temperature switch according to claim 1, wherein a magnetic plate having a Curie point sufficiently higher than the Curie point of the temperature-sensitive magnetic plate is installed between the substrate and the magnetic pole faces of the two magnets.