JPS5856446B2 - Temperature sensitive reed switch - Google Patents

Description

Detailed Description of the Invention This invention is a non-band operating type in which two types of temperature-sensitive magnetic materials with different Curie points are arranged in series to shift the operating temperature or widen the temperature difference between the operating temperature and the return temperature. Regarding temperature-sensitive reed switches.

Conventionally, so-called non-band temperature sensing devices combine a reed switch, a temperature-sensitive magnetic material, and a permanent magnet so that the reed switch turns off (or on) above a certain temperature and turns on (or off) below a certain temperature. In reed switches, it is necessary to select a temperature-sensitive magnetic material whose composition exhibits a change in characteristics in accordance with the operating temperature, and therefore it is necessary to prepare a temperature-sensitive magnetic material with a different composition for each operating temperature.

Therefore, there is a problem in that a temperature-sensitive reed switch having a required operating temperature cannot be produced without the use of an extremely large variety of temperature-sensitive magnetic materials.

In addition, there has not been a temperature-sensitive reed switch that has high accuracy in operating temperature and return temperature and has a wide temperature difference between the operating temperature and return temperature (hereinafter simply referred to as a temperature differential).

Some magnetic materials have a saturation magnetic flux density that changes slowly with respect to temperature even near the Curie point, and if such a temperature-sensitive magnetic material is used, the temperature differential will be widened.

However, in this case, the accuracy of the operating temperature and return temperature will also deteriorate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a temperature-sensitive reed switch that overcomes the drawbacks of the conventional ones as described above.

The present invention will be explained with reference to the drawings.

FIG. 1a shows a conventional normally closed type (the contact is turned off when the operating temperature is exceeded).

) is a cross-sectional view of a reed switch, and the figure shows a magnetic flux flowing through a contact part in the same reed switch (the magnetic flux flowing from left to right on the page is assumed to be 0).

) and temperature to illustrate the operating principle of a temperature-sensitive reed switch.

In Fig. 1a, 6 is a reed switch which has a contact part 5 in the axial center of a long and narrow glass container, and two ferromagnetic wires extending from the contact part 5 in opposite directions in the axial direction and supported by the glass container. It has body leads 3 and 4.

Ia and Ib are permanent magnets having a Curie point sufficiently higher than the operating temperature, and 2 is a temperature-sensitive magnetic material having a Curie point corresponding to the operating temperature, and is disposed opposite to the contact portion 5.

Permanent magnets 1a and 1b are arranged facing the leads 3 and 4 with the temperature-sensitive magnetic body 2 in between, with their magnetization directions being the same in the axial direction of the reed switch, and are fixed to the reed switch.

Considering the case where the temperature increases, the temperature-sensitive magnetic body 2 is ferromagnetic at a temperature below one Curie point of the temperature-sensitive magnetic body 2, and the magnet 1
All the magnetic flux flowing from b to the magnet 1a passes through the temperature-sensitive magnetic material, forms a magnetic circuit flowing through the leads 3 and 4, and the magnetic flux flowing through the contact part 5 attracts the contact against the elastic force of the leads 3 and 4. Gives enough suction to keep it in place.

As the temperature rises, the magnetic flux flowing through the contact portion 5 gradually decreases as shown by the curve 111b.

That is, the saturation magnetic flux density of the temperature-sensitive magnetic body 2 decreases, and the magnetic flux flowing through the temperature-sensitive magnetic body 2 leaks to the contact portion 5.

This leakage magnetic flux is in the opposite direction to the magnetic flux flowing through the contact portion 5 and is canceled out, resulting in a decrease in the magnetic flux flowing through the contact portion.

When the magnetic flux decreases to D.0, the elastic force of the leads 3 and 4 overcomes the remaining attractive force and separates the contacts.

This temperature (denoted OT) is the operating temperature.

On the other hand, if the temperature drops from a temperature higher than the operating temperature, even if it reaches OT, the magnetic flux will not have enough adsorption force to overcome the elastic force of the lead 3. , 4, the magnetic fluxes P and I that obtain sufficient adsorption force to adsorb the contact point flow into the contact portion 5 again.

The on/off state of the reed switch contact is determined by whether a certain amount of magnetic flux is flowing through the contact, and the operating temperature is a temperature just below the Curie point of the temperature-sensitive magnetic material.
Furthermore, the present invention is intended to actively utilize the property that it is influenced by the characteristics of the reed switch.

FIGS. 2a and 2b show a cross-sectional view and a magnetic flux-temperature curve of the first embodiment of the present invention.

In place of the temperature-sensitive magnetic body 2 shown in FIG. 1, two types of temperature-sensitive magnetic bodies 2C1 and 2C2 whose Curie points are slightly shifted from each other are used.

In FIG. 2bVcX, curve A indicates the case where the temperature-sensitive magnetic material 2C1 is used alone and the operating temperature is OT1, and the curve end indicates the case where only 2C2 is used and the operating temperature is OT2.

The broken line 11 is the case of this embodiment, and the operating temperatures are OTl and OT2.
OT is a certain temperature between .

That is, the operating temperature can be changed.

The temperature-sensitive magnetic body 2C1 is already paramagnetic at the temperature directly above the OT1, and the leaked magnetic flux flows to the contact portion 5. However, the amount of leaked magnetic flux is smaller than when the temperature-sensitive magnetic body 2C1 is used alone, and the leakage magnetic flux flows to the contact portion 5.
The magnetic flux flowing through can counter the elastic force and keep the contacts still in the attracted position.

That is, the operating temperature is a temperature of 071 or higher.

At a temperature directly below the OT2, the magnetic flux flowing through the contact portion 5 is reduced more than in the case of the temperature-sensitive magnetic body 2C2 alone, and the contact cannot be maintained in the attracted state.

That is, the operating temperature is a certain temperature below OT2.

The transition width of the operating temperature can be determined experimentally by changing the Curie point difference between the two temperature-sensitive magnetic materials, the composition ratio, etc.

FIG. 3 shows the second normally open temperature-sensitive reed switch according to the present invention.
This is an example.

A magnetic gap 1 is provided between the temperature-sensitive magnetic bodies 2C and 2C2, and the appearance of the magnetic flux flowing to the contact portion 5 due to the magnetic flux leaking from the magnetic gap at a temperature lower than one Curie point of both temperature-sensitive magnetic bodies is increased. This is a normally open temperature-sensitive reed switch that opens the contact (by canceling out the flow of magnetic flux in the positive direction by leakage magnetic flux).

FIG. 4 shows a third embodiment of a normally closed temperature-sensitive reed switch with a wide temperature differential according to the present invention, in which a is a cross-sectional view and b is a magnetic flux-temperature curve.

The configuration is the same as that of the first embodiment shown in FIG. 2, except that the temperature-sensitive magnetic bodies 2C1 and 2C2 have one Curie point corresponding to the required return temperature and operating temperature, respectively.

It is assumed that the temperature-sensitive magnetic material 2C1 has a single Curie point lower than that of the temperature-sensitive magnetic material 2C2.

T for one cucumber of each. 1. 'Ic2(Tc1< Te
3).

At temperatures lower than T'ct, the temperature-sensitive magnetic material 2°1 t
2C2 are both ferromagnetic, and a large amount of magnetic flux flows through the contact portion 5, giving the contact a stronger attraction force than the elastic force of the leads 3 and 40, resulting in an on state.

The temperature is T. When the value exceeds 1, the temperature-sensitive magnetic body 2C1 becomes paramagnetic, and the magnetic flux flowing through the contact portion reaches a certain level, but the contact remains in the on state.

This state continues even if the temperature rises.

The temperature further rises and the temperature-sensitive magnetic material 2C2 reaches one point TC.
When the saturation magnetic flux density near 2 reaches a temperature where it suddenly decreases, the magnetic flux decreases and decreases to a value of 0, turning the contact off.

That is, the operating temperature OT is a temperature just below the Curie point TC2.

If we follow the course of the temperature drop, the temperature-sensitive magnetic body 2C2 first returns to ferromagnetism at a temperature near TC2.

Although the magnetic flux flowing through the contact portion 5 increases, it is still not possible to apply sufficient attraction force to the contact, and the off state continues even if the temperature further drops.

As the temperature approaches T'ct, the magnetic flux increases further and P,
When the I value is reached, sufficient suction force is applied to the contact to shift the contact to the suction state.

The return temperature RT is a certain temperature near the Curie point TCI.

The operating temperature OT and the return temperature RT are determined by the magnetic flux as shown in Figure 4.

It can be seen that even if there is some variation in the O, P, and I values, they can be accurately reproduced.

According to this embodiment, the temperature differential is wide and the operating temperature is low.

A temperature-sensitive reed switch with excellent return temperature accuracy is provided.

In FIG. 4, when the length dimensions of the temperature-sensitive magnetic bodies 2゜1 and 2C2 become large and the distance between the permanent magnets 1a and 1b becomes wide, the contact portion 5 at the Curie point TCI of the temperature-sensitive magnetic body 2゜1
The magnetic flux flowing through the temperature-sensitive magnetic body 2C1 decreases to nearly zero below the DO value, causing the contact to switch from on to off.The temperature further rises, and at the Curie point TC2 of the temperature-sensitive magnetic body 2C1, the magnetic flux flows in the opposite direction to the contact portion 5. The flowing magnetic flux becomes dominant and reaches above the DO← value, causing the contact to switch from off to on.In other words, the contact remains off within a certain temperature range, making it a temperature-sensitive reed switch. Magnetic material 2
The length of C122C2 must be shorter than the dimensions of this band operating type.

This upper limit size varies depending on the thickness of the reed switch tube; the position of the contact, the length of the reed in the tube, and the characteristic dimensions of the permanent magnet.

This can be easily determined by experiment.

FIGS. 5a and 5b are a sectional view of a fourth embodiment of a normally open type with a wide temperature differential and a relationship between magnetic flux and temperature.

7 is a magnetic gap. FIG. 6 is a perspective view of a normally closed temperature-sensitive reed switch with a wide differential in which a permanent magnet and a temperature-sensitive magnetic body are linked in the configuration shown in FIG.

FIG. 7 shows a wide normally open differential that operates on the same principle as FIG. FIG. 2 is a perspective view of a temperature-sensitive reed switch in which magnetic gaps T are provided at two locations between the two.

In both drawings, the temperature-sensitive magnetic body 2C1.

Although the dimensions are nearly half that of the 2C2 structure, it is easy to understand that the drawings are non-limiting and that there are combinations of materials, dimensions, etc. that correspond to desired characteristics.

The temperature-sensitive reed switch according to the present invention, which uses two types of temperature-sensitive magnetic materials with a single point of difference, eliminates the need for temperature-sensitive magnetic materials of appropriate materials for each operating temperature, and facilitates material management, material saving, and manufacturing. It is important that it contributes to alleviating conditions.

In addition, a completely new type of temperature-sensitive reed switch with good accuracy and a wide temperature differential is extremely useful for temperature monitoring in a wide range of fields, and is expected to have a wide range of applications.

In addition, in this invention, since two types of temperature-sensitive magnetic materials are arranged in series, the thermal response of the temperature-sensitive reed switch is better than when the temperature-sensitive magnetic materials are arranged in parallel. The outer diameter of the warm reed switch can be made smaller.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view and magnetic flux-temperature curve diagram showing the conventional example, and Figure 2 shows the conventional example.
4 and 5 respectively illustrate the first embodiment according to the present invention. Third. A cross-sectional view of the fourth embodiment and a magnetic flux-temperature relationship diagram, FIG. 3 is a cross-sectional view of the second embodiment according to the present invention, and FIGS. 6 and 7 are
FIG. 6 is a perspective view of a 5th and 6th embodiment of the present invention, respectively; 1... Permanent magnet, 2... Temperature-sensitive magnetic material, 3, 4...
Lead, 5...Contact part, 6...Reed switch, T
...Magnetic air gap.

Claims (1)

[Claims] 1. A reed switch having leads extending in opposite directions in the axial direction from a contact portion, a temperature-sensitive magnetic body disposed in close contact with the outer periphery of the reed switch near the contact portion, and both sides of the temperature-sensitive magnetic body. A temperature-sensitive reed switch including a permanent magnet disposed in close contact with the temperature-sensitive magnetic body, wherein two types of temperature-sensitive magnetic bodies having different Curie points are connected in series, and the temperature-sensitive reed switch is capable of non-band operation. A temperature-sensitive reed switch characterized by being arranged in an oval shape.