JPH0247046B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a temperature-sensitive switch using a reed switch that opens and closes magnetically.

[Prior Art] Generally, a typical sealed contact reed switch used in a temperature-sensitive switch is made up of a pair of magnetic leads having contacts sealed in a glass container.
Both leads are spaced apart at each free end;
They are enclosed in a glass container in the form of overlapping cantilever springs. When a magnetic field is applied from a magnetic field source, the leads contact and create an electrical path, and when the magnetic field is removed, they spring back to interrupt the electrical path.

As shown in FIG. 1, a sealed contact reed switch used in a conventional temperature-sensitive switch has a contact point in which a pair of magnetic leads 2, 2' have a suitable gap at their free ends. An inert gas 4 is sealed inside the glass container 3. When a magnetic field is applied by an external magnetic field source, opposite magnetic poles are generated at the contact portions of the magnetic leads 2, 2', and the contacts open and close. At this time, if the leads 2 and 2' are connected to an external circuit including a power supply 5 as shown in FIG.
A current flows through 2'. When a current flows through the magnetic leads 2, 2', the magnetic leads 2, 2'
A magnetic field is generated in the circumferential direction of the lead 2, 2', and due to the external magnetic field, the spin magnetic moment oriented in the length direction of the leads 2, 2' is rotated around the leads 2, 2' by the circumferential magnetic field. facing in a spiral direction. as a result,
The magnetic flux density in the length direction of the magnetic leads 2, 2' decreases. When the magnetic flux density in the length direction of the magnetic leads 2, 2' decreases due to the applied current, the following decrease occurs in the reed switch.

(1) The ampere-turn value at which the reed switch contacts meet, that is, the open value, increases in proportion to the magnitude of the energizing current.

(2) When the energizing current exceeds a certain level, when the reed switch contacts open and the energizing current becomes zero, the magnetic flux density of the leads 2 and 2' increases and the magnetic attractive force increases again, causing the contacts to close. . This repetition causes electromagnetic chatter.

For details regarding (1) and (2), please refer to the Institute of Electrical Engineers of Japan Magnetic Application Study Group, Material No. AM-79-63, “A Study on the Opening and Closing of Contacts in Thermal Reed Switches” (1979).
(December 21).

[Problem to be Solved by the Invention] However, from the phenomenon (1) mentioned above, the pressure caused by the magnetic attraction force on the reed switch contact point is
As the applied current increases, it hangs and becomes smaller. As the pressure decreases, the contact resistance of the contact increases,
Heat generation at the contact area increases. As the temperature rises, the damage that occurs during separation becomes more severe. Furthermore, when the applied current is alternating current, if the change in the external magnetic field for opening and closing the reed switch is slower than the alternating current frequency, the contacts open when the applied current reaches its maximum. That is, the contacts open when the alternating current is most severe.

Next, from the phenomenon (2), if long electromagnetic chatter occurs when the contacts open, spot erosion occurs in the contacts, damaging the contacts.

Therefore, conventional reed switches had the disadvantage that the influence of the magnetic field generated by the current flowing through the reeds acted to accelerate the deterioration of the contacts, and as a result, they could not open or close loads larger than a certain level.

In view of the above-mentioned drawbacks, the technical problem of the present invention is to reversely utilize the influence of the magnetic field generated by the current flowing through the lead and the electrostatic attraction force, thereby reducing contact deterioration and making it possible to open and close a large load. To provide a temperature-sensitive switch which can be miniaturized and has a large contact capacity and is composed of a combination of a switch, a temperature-sensitive magnetic material, and a permanent magnet.

[Means for Solving the Problems] According to the present invention, the first drawer is sealed in a cantilever spring type inside an insulating container, is made of a magnetic material and has a first contact at its free end, and has a first drawer outside the container. a first lead 5 connected to the line, and a second contact that is cantilevered on the container near the sealed portion of the first lead 5 and that has a free end in normal contact with the first contact. a second lead 6 connected to a second lead wire outside the container; It has a third lead 7 made of a magnetic material arranged in a cantilevered state so as to face each other with an air gap, so that it is in a conductive state when no magnetic field is applied, and in the presence of an external magnetic field. With the free end of the first lead in contact with the free end of the third lead, the formation of an electrical path from the first lead through the third lead to the second lead wire is blocked. It is characterized by a combination of a reed switch 15 with an electrical insulator 10 interposed in the middle of the path to achieve this, and a permanent magnet 14 and a temperature-sensitive magnetic material 13 provided on the outer periphery of the reed switch 15. A temperature-sensitive switch is obtained.

That is, the structure of the present invention consists of first enclosing a pair of substantially parallel leads having contact points in a glass container. One lead is the main magnetic lead 5, and the other lead is a functionally non-magnetic lead 6.
Each free end has a contact point in the form of a contacting cantilever and is sealed in a glass container in contact with suitable pressure. The main magnetic lead has spring properties, and its stiffness is such that it deflects due to magnetic attraction. Further, an auxiliary magnetic lead is fixed to the glass container or the non-magnetic lead such that the free end of the main magnetic lead faces the surface opposite to the contact point of the non-magnetic lead with a gap therebetween. . The stiffness of the auxiliary magnetic lead is large enough that there is almost no deflection due to the attractive force, and the gap between the free end of the main magnetic lead and the free end of the auxiliary magnetic lead is large enough to generate a magnetic attractive force that provides a magnetic field. .

Therefore, in the reed switch used in the temperature-sensitive switch of the present invention, the contacts are closed when no magnetic field is generated from the magnetic field source, and the main magnetic lead and the non-magnetic lead form an electrical path. When a magnetic field is generated, the main magnetic lead and the auxiliary magnetic lead are attracted, the contacts open and the electrical path is interrupted.

Note that in the present invention, since a current path can be provided within the magnetic body, the magnetic flux φ generated by the current passes through the magnetic body, and no demagnetizing field is generated at all. Moreover, the strength of the magnetic field due to the current in the magnetic body and the strength of the magnetic field due to the current become stronger because the distance from the current is short.

[Example] Next, an example of the present invention will be described with reference to the drawings.

3 to 6 show the reed switch used in the temperature-sensitive switch of this embodiment. As a representative example, the operating principle of the embodiment shown in FIG. 3 will be explained. A main magnetic lead 5 and a non-magnetic lead 6 having contacts 9 and 9', respectively, are enclosed in a glass container 8. Both leads 5 and 6 are drawn out of the container so that they can be connected to an external circuit. At this time, the contacts 9 and 9' are in contact with each other with appropriate pressure. The magnetic lead 5 has a spring property, and its stiffness is set to a size such that it can be deflected by the magnetic attraction force. Non-magnetic lead 6
An auxiliary magnetic lead 7 having a gap with the free end of the main magnetic lead 5 is fixed to the glass container 8 on the opposite side. The air gap is large enough to attract both magnetic leads 5 and 7 when a magnetic field is applied. The stiffness of the auxiliary magnetic lead 7 is preferably such that it hardly bends due to the magnetic attraction force. Contacts 9 and 9' are closed when no magnetic field is applied, and when a magnetic field is applied, magnetic lead 5 is attracted to magnetic lead 7, and contacts 9 and 9' open (hereafter closed). The magnitude of the magnetic field at that time is called the closure value.)

Next, when this reed switch is replaced with reed switch 1 in Fig. 2 and connected to an external circuit,
When the external magnetic field is below the closing value, the contacts 9, 9' are closed and current flows through the leads 5, 6. At this time, the hourly density in the longitudinal direction of the main magnetic lead 5 becomes smaller due to the applied current. This is the same as the conventional reed switch 1 shown in FIG. However, in the case of the reed switch of the present invention, the pressing force on the contact point is the spring force of the magnetic lead 5 (compared to the magnetic attraction force in conventional reed switches), and the force for opening the contact point is the magnetic attraction force with the magnetic lead 7. (The conventional reed switch is a spring force of the reeds 1 and 1'.)

Therefore, when the magnetic flux density in the length direction of the magnetic lead decreases due to the applied current, the following can be said about the contacts of the reed switch.

(a) The pressure on contacts 9 and 9' increases in proportion to the applied current.

(b) When the carrying current is alternating current, if the change in the external magnetic field is slow compared to the frequency of the alternating current, the contacts open when the carrying current reaches its minimum.

(c) When the contacts 9 and 9' are opened and the current flowing becomes zero, the magnetic attraction force increases and the opening force becomes stronger, so that no electromagnetic chatter occurs.

As described above, the reed switch used in the temperature-sensitive switch of the present invention has advantages over conventional reed switches, and is superior to non-magnetic switches such as bimetallic mechanical switches. It can be seen that since the current is cut off near zero, it is advantageous in terms of contact deterioration when a large current is disconnected.

The ones in FIGS. 4 to 6 are modified examples, and are basically the same as the one in FIG. 3.

The reed switch shown in FIG. 4a has an auxiliary magnetic lead 7 supported by the lead 6 via an insulator 10, and the reed switch shown in FIG. . Fifth
The reed switch shown in the figure has an auxiliary magnetic lead 7 fixed to a non-magnetic lead 6, and an insulating film attached to the tip of the auxiliary lead inside a glass container on the side facing the main magnetic lead 5.
2 is attached. Although the insulating film 12 is attached to the auxiliary magnetic lead 7 side in the figure, it may be attached to the main magnetic lead 5 side.

In the reed switch shown in FIG. 6, part of the lead 6 is magnetic, and only the part 6' near the contact 9' is non-magnetic, which functionally blocks the magnetic attraction force between the main magnetic lead 5 and the auxiliary magnetic lead 7. The main purpose is to make the magnetic lead 5 and the lead 6 under the same conditions at the location where the container 8 is sealed. For the same purpose, the material near the sealing part of the container 8 of the magnetic lead 5 shown in FIGS. 3 and 4 may be non-magnetic like the lead 6.

Furthermore, when the reed switch in this embodiment is connected to an external circuit having an AC power source, an electrostatic attraction force is generated between the main magnetic lead 5 and the auxiliary magnetic lead 7 due to the AC voltage when the contacts are opened. If this is generated, the contact will close when the electrostatic attractive force is small, that is, when the voltage is small. This reduces damage to the contacts during closing. This can be achieved by making the insulating screen 12 of the reed switch shown in FIG. 5 thinner, or by using dielectric materials for the insulating screen 12 and the insulators 10 and 11 of the reed switch shown in FIG. Of course, the resistance value of the dielectric must be close to that of the insulator. It goes without saying that the container used for the reed switch can be made of an insulating material other than glass.

As described above, the reed switch of this embodiment not only eliminates the drawbacks of conventional reed switches when opening and closing a relatively high current load, but also has a higher contact point than other non-magnetic switches. It can be said that it is a reed switch with excellent characteristics.

As a result, it is possible to provide an excellent switch by combining the advantages of a reed switch which is inherently good in environmental resistance and is a highly reliable switch, and is an industrially useful invention. Furthermore, since the lead wires 5 and 6 are located on one side of the reed switch rather than on both sides, there is no need to route wires connected to the lead wires, making the reed switch easy to handle.

FIG. 7 shows an embodiment of a temperature-sensitive switch using the above-mentioned reed switch 15 according to the embodiment of the present invention and combining a temperature-sensitive magnetic body 13 and a permanent magnet 14.

Figures 8a and 8b particularly show the structure of a center gap type temperature sensitive switch. FIG. 8a shows the case where the temperature-sensitive magnetic body 13 is below the set temperature, and it can be seen that the reed switch is opened. FIG. 8b shows a case where the temperature-sensitive magnetic body 13 is at a temperature higher than the set temperature,
It can be seen that the reed switch is in Heisei era.

It goes without saying that even if a temperature-sensitive switch is configured with a magnetic circuit other than this, a temperature-sensitive switch with similarly good contact characteristics can be obtained. A temperature-sensitive switch incorporating the reed switch of this embodiment is an application in which the advantages of this reed switch are best utilized. This is because temperature changes in temperature-sensitive switches are relatively gradual, so changes in the magnetic field applied to the reed switch are small, and the contact characteristics of temperature-sensitive switches that control large loads must be relatively strong. be. Therefore, the temperature-sensitive switch using the reed switch according to this embodiment has a large contact area, is highly reliable, and has low noise when opening and closing the contacts, and is suitable for home appliances, automobiles, office equipment, etc. It is useful as a temperature-sensitive switch.

[Effects of the Invention] As can be seen from the above description, according to the present invention, the influence of the magnetic field and the electrostatic attraction force generated by the current flowing through the leads are used inversely to reduce contact deterioration and to reduce the load caused by heavy loads. It is possible to provide a temperature-sensitive switch that can be miniaturized and has a large contact capacity, which is composed of a combination of a reed switch that can open and close the switch, a temperature-sensitive magnetic material, and a permanent magnet.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing a conventional reed switch, Fig. 2 is a circuit diagram showing one state of use of the reed switch, and Figs. 3 to 6 show various embodiments of the reed switch according to the present invention. 7a to 7c are side sectional views of a temperature-sensitive switch of the present invention using the reed switches of FIGS. 3 to 6, and FIGS.
FIG. 3b is a conceptual diagram showing the structure of a center gap type temperature-sensitive switch according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Conventional reed switch, 2, 2'... Magnetic lead, 3... Glass container, 4... Filled gas, 5... Main magnetic lead, 6... Lead, 7... Auxiliary magnetic lead, 8
...Glass container, 9,9'...Contact, 10...Insulator,
DESCRIPTION OF SYMBOLS 11...Glass, 12...Insulating film, 13, 13'...Temperature-sensitive magnetic material, 14...Permanent magnet, 15...Reed switch according to the present invention, 16...Magnetic gap, 17...
Power supply, 18...load.

Claims (1)

[Claims] 1 A first lead sealed in a cantilever spring type in an insulating container and made of a magnetic material having a first contact at its free end, and connected to a first lead wire outside the container; The lead 5 is cantilever-supported by the container near the sealed portion, and has a second contact point in normal contact with the first contact point at the free end, and is connected to a second lead wire outside the container. A second lead 6 is disposed in the container in a cantilevered state such that its free end faces with a gap between the free end of the first lead and the second contact on the opposite side. and a third lead 7 made of a magnetic material, which is electrically conductive when no magnetic field is applied, and in the presence of an external magnetic field, the free end of the first lead is connected to the third lead 7. An electrical insulator 10 is provided in the middle of the path in order to block the formation of an electrical path from the first lead to the second lead wire through the third lead while in contact with the free end of the lead. A reed switch 15 with a permanent magnet 14 and a temperature-sensitive magnetic body 13 provided on the outer periphery of the reed switch 15.
A temperature-sensitive switch characterized by consisting of a combination of.