JPH01321606A - Heat sensitive absorbent on/off device - Google Patents

Abstract

PURPOSE:To obtain a permanent magnet product which reversely utilizes the defect that the magnetizing force of a rare earth transition metal boron based permanent magnet with low Curie temperature lowers at high temperature, by equipping a permanent magnet and an attraction tool consisting of high permeability material provided opposite to the permanent magnet. CONSTITUTION:By adding external force a little weaker than the attraction to an attraction tool 3 in the opposite direction to the direction of permanent magnet 1 attraction, the attraction tool 3 is attracted by the permanent magnet 1 since the attraction of the permanent magnet 1 surpasses the external force at ordinary temperature. On the other hand, if it becomes high temperature, since the magnetic flux amounts of the permanent magnet 1 decreases, the attraction decreases and the external force surpasses the attraction, therefore the attraction tool 3 separates from the permanent magnet 1. By adjusting the strength of the external force to the decrease rate (demagnetizing factor) of the magnetic flux amounts to the temperature of the permanent magnet 1, it becomes possible to separate the attraction tool 3 from the permanent magnet 1 when it becomes above the specified temperature. Hereby, by reversely utilizing the property that the Curie point is low and it demagnetizes at high temperature, it can be made into a energy saving heat sensitive sensor which operates even if the energy is not added from the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an adsorption tool that utilizes the temperature dependence of the magnetization strength of a permanent magnet.

[Prior art] An adsorption tool that uses the magnetizing force of a permanent magnet is composed of a permanent magnet and an adsorption tool made of a high magnetic permeability material that is attracted to the permanent magnet. Ru. When necessary, the suction device was unfixed and used by applying external force, such as by pulling it by hand. These are used at room temperature, and are often used, for example, in clasps for bags, and clasps for paper products such as memos and posters. Ferrite magnets were often used as permanent magnets for this purpose.

[Problems to be Solved by the Invention] However, in the prior art as described above, ferrite magnets have a weak magnetizing force and a small force to hold the attracting tool, so if a large attracting force is to be obtained, a large permanent magnet is required. be.

On the other hand, if a rare earth permanent magnet with a large magnetizing force is used, not only will the problem of attraction force be solved, but its excellent magnetic performance will also enable miniaturization, but it is expensive. Among them, the rare earth-transition metal-boron system (hereinafter referred to as R-TM) is relatively inexpensive.
-B series) magnets are known, but these magnets have the drawback of demagnetizing at high temperatures.

Permanent magnets have the property that their magnetizing power decreases and their attraction force weakens as the temperature rises, so efforts are being made to raise the Curie temperature of permanent magnets to prevent the magnetizing power from decreasing as much as possible. In particular, R-TM-B magnets have a low Curie temperature, which limits their use as permanent magnets. Therefore, attempts have been made to improve the Curie temperature by adding various additive elements, but the problem has not yet been completely solved.

Therefore, the present invention is intended to solve the above-mentioned drawbacks, and its purpose is to achieve a low Curie temperature of R-
The purpose of the present invention is to provide a permanent magnet product that takes advantage of the drawback of TM-B permanent magnets, which is a decrease in magnetizing power at high temperatures.

[Means for solving the problem] A permanent magnet and an adsorption tool made of a high magnetic permeability material provided opposite to the permanent magnet are provided, and the adsorption tool attracts the permanent magnet in a low temperature range, and when the temperature exceeds a predetermined temperature, The adsorbent separates from the permanent magnet in the high temperature range of .

Further, the permanent magnet is characterized in that its basic components are rare earth elements (including yttrium), transition metals, and boron.

[Operation] Permanent magnets have the property that their magnetizing power decreases as the temperature increases, and the rate of this decrease is determined by the basic composition of the permanent magnet. For example, the Curie temperature of R-TM-B permanent magnet is approximately 310'
The amount of magnetic flux of a C1 permanent magnet is approximately 20% demagnetized when the temperature is raised from room temperature to 160℃ and returned to room temperature (irreversible demagnetization), and proportional to the temperature when lowered from high temperature to room temperature. The demagnetization that returns to its original state (reversible demagnetization) is approximately 0. 1%
/℃, the amount of magnetic flux decreases. By applying an external force that is slightly weaker than the adsorption force to the adsorption tool in the opposite direction to the adsorption direction of the permanent magnet, the adsorption tool will be attracted to the permanent magnet because the adsorption force of the permanent magnet will be stronger than the external force at room temperature. When the magnetic flux of the permanent magnet decreases, the attraction force decreases, and the external force exceeds the attraction force, so the attraction tool separates from the permanent magnet. By adjusting the magnitude of the external force with respect to the rate of decrease in magnetic flux with respect to the temperature of the permanent magnet (demagnetization rate), it becomes possible to separate the adsorbent from the permanent magnet when the temperature reaches a predetermined temperature or higher. Further, if the temperature is lowered from a predetermined temperature or higher, the amount of magnetic flux of the permanent magnet increases and it becomes possible to attract the suction tool again.

External forces are generally thought of as being applied by springs, gravity, etc.

[Example] Hereinafter, the present invention will be explained in detail based on examples.

(Example-1) Fig. 1 is a side view of the heat-sensitive adsorbent of the present invention, in which 1 is a permanent magnet, 2 is an adsorbent in which the back yoke 3 is made of a high magnetic permeability material that is attracted to the permanent magnet, and 4 is a A spring that applies a force in the opposite direction to the attraction force of a permanent magnet. Table 1 shows the composition of the permanent magnet alloy of this example.

Magnets No. 61, No. 2 were obtained by melting the composition shown in Table 1, casting into a mold, cooling, hot rolling at 950° C., and then cutting into a predetermined shape. then 10
It was heat-treated at 00°C for 24 hours and magnetically hardened. Magnet No. 3 is made by melting the composition shown in Table 1, casting it into a mold, cooling it, mechanically grinding it into a powder with an average particle size of 5μ, adding and mixing zinc stearate as a forming aid, and press-molding it into a predetermined shape. I did it. The obtained molded body was
Dewax at 00°C for 2 hours, then at 1050°C for 3 hours.
Obtained by sintering for hours. Table 2 shows the properties of the obtained permanent magnet.

Table 2 Note that the demagnetization rates in Table 2 are values measured at temperatures from room temperature to 150°C.

FIG. 2 is a side view of an electric contact to which the heat-sensitive suction device of the present invention is applied, in which 1 is a permanent magnet, 2 is a back yoke, 3 is an adsorption device, 4 is a spring, and 5a and 5b are electric contacts. At room temperature, the suction tool 3 is attracted to the permanent magnet 1, and the electrical contact 5a
and 5b are in a conductive state. Since the magnetizing force of the permanent magnet 1 decreases in a high temperature state, the attraction tool 3 is separated by the force of the spring 4, and the electrical contacts 5a and 5b become non-conducting. Table 3 shows the relationship between the ratio of the force of the spring to the attractive force of the permanent magnet and the temperature.

The force ratio indicates the ratio of the repulsive force of the spring to the attractive force of the permanent magnet at room temperature. If you want to release the suction tool when the temperature is 90°C, set the spring force to 90% of the permanent magnet's attraction force at room temperature, and at 130°C, set the spring force to 80%. , the suction tool can be attached and detached at each temperature, and the electrical contacts can be opened and closed.

Table 3 lists one embodiment of the present invention, and by adjusting the ratio of force, it is possible to attach and detach at a desired temperature.

(Example-2) Fig. 3 is a side view of a heat-sensitive adsorbent according to the present invention in which an external force is applied by gravity, in which 1 is a permanent magnet, and 2 is a back yoke 3 which is an adsorbent that is attracted to the permanent magnet. .

The composition, manufacturing method, and performance of the permanent magnet 1 are the same as in Example 1. The weight of the suction tool 3 is an external force that acts in the opposite direction to the attraction force of the permanent magnet, and by adjusting the weight, the temperature at which the suction tool 3 is separated from the permanent magnet 1 can be determined. When a predetermined temperature is reached, the suction tool 3 separates from the permanent magnet 1 and falls downward. However, a stopper (not shown) is prepared below the suction tool 3 to catch the suction tool when it falls. By adjusting the gap between the suction tool 3 and the permanent magnet 1, it is also possible to attract the suction tool 3 to the permanent magnet 1 again when the temperature drops. Moreover, if there is no need for re-adsorption, it is sufficient to just let the object fall without preparing a stopper, or to increase the gap between the permanent magnet 1 and the adsorption tool 3.

[Effects of the invention] As described above, according to the present invention, by taking advantage of the characteristic that the Curie point is low and demagnetizes at high temperatures, which has been considered a drawback until now, it is possible to generate magnets without applying external energy. Creates an energy-saving heat-sensitive sensor that works with both. This opens up the uses of R-TM-B magnets that have been limited until now. In addition, permanent magnets can be manufactured through a simple manufacturing process, so they have the advantage of being highly productive and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a side view of the heat-sensitive suction tool, FIG. 2 is a side view of the electrical contacts, and FIG. 3 is a side view of the heat-sensitive suction tool that applies external force by gravity. 1...Permanent magnet 2...Back yoke 3...Adsorption device 4...Spring or more Applicant: Seiko Epson Co., Ltd. Representative Patent attorney Kizobe Suzuki and 1 other person Figure 2

Claims (2)

[Claims] (1) Equipped with a permanent magnet and an adsorption device made of a high magnetic permeability material provided opposite to the permanent magnet, the adsorption device adsorbs to the permanent magnet in a low temperature range, and in a high temperature range above a predetermined temperature. A heat-sensitive adsorption/detachment device that is characterized by its ability to separate from a permanent magnet. (2) The heat-sensitive adsorbent/desorber according to claim 1, wherein the permanent magnet has a rare earth element (including yttrium), a transition metal, and boron as basic components.