JPH0135457B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a temperature switch that detects temperature changes and conducts or cuts off current by opening and closing the switch, and more specifically relates to a temperature switch used for temperature control, temperature alarm, etc. Bimetal is known as such a temperature switch, but bimetal has a large change in the distance between the switch elements that are to be opened and closed over time, and conduction and loss occur with use.
There is a drawback that the temperature at which the shutoff occurs varies. Further, as a conventional temperature switch, a reed switch using ferrite having a low Curie point is known. In this reed switch, a reed piece made of a magnetic material is enclosed in a container, and ferrite whose composition has been adjusted so that the Curie point drops to a low temperature close to room temperature is placed outside the container and adjacent to it. Temperature control or temperature alarm can be performed by applying an external magnetic field generated by the ferrite to the reed piece or causing it to disappear from the reed piece during a temperature change passing through a point, and then opening and closing the reed switch at a predetermined temperature. conduct. However, the combination of ferrite and reed switch has a limitation in current capacity, and ferrite has low saturation magnetization, which limits miniaturization. The present invention improves upon conventional temperature switches by utilizing an entirely new temperature sensing principle. The switch according to the present invention includes a magnetic flux generating part made of a permanent magnet, a first magnetic flux passage part made of a rare earth cobalt alloy material whose axis of easy magnetization changes depending on temperature, and a second magnetic flux passage part made of a soft magnetic material, Each of the above magnetic fluxes is arranged such that the magnetic flux passes through the converter on either a lower temperature side or a higher temperature side than the temperature at which the axis of easy magnetization of the rare earth cobalt alloy changes, and leaks out of the converter on the other side. A temperature switch comprising a temperature/magnetic field converter formed by combining parts, and a current breaker that is opened/closed by magnetic flux leaking outside the converter, the temperature/magnetic field converter forming a core body. a permanent magnet, two soft magnetic materials respectively connected to both magnetic poles of the permanent magnet, and at least the rare earth cobalt alloy in which the axis direction of easy magnetization that persists in the two soft magnetic materials changes with temperature; A first magnetic material installed such that the axis of easy magnetization on the high temperature side is parallel or perpendicular to the magnetization direction of the permanent magnet, and one of the permanent magnets via one of the soft magnetic materials. a second magnetic material made of the rare-earth cobalt alloy whose easy-magnetization axis direction changes with temperature, and which is installed so that the easy-magnetization axis direction connected to the magnetic pole is perpendicular to the easy-magnetization axis direction of the first magnetic material; , the current breaker is connected to a fixed terminal fixed to one end of the second magnetic material, and is attracted to the permanent magnet by a magnetic flux that is arranged opposite to the fixed terminal and leaks out of the converter, and is connected to the fixed terminal. The switch element is characterized in that it includes a movable terminal made of a soft magnetic material. One feature of the temperature switch of the present invention is that a ferromagnetic material whose direction of easy magnetization changes depending on temperature is used as the first material.
It is used in the magnetic flux passage section. It is well known that among ferromagnetic materials, there are materials with large magnetic anisotropy, and there are also materials whose direction of easy magnetization changes with temperature. Typical materials include rare earth cobalt alloys (PrCo ₅ , NdCo ₅ ,
TbCo ₅ , DyCo ₅ , HoCo ₅ , Lu ₂ Co ₁₇ , Tm ₂ (Fe _1-x
Cox ) ₁₇ etc.). In addition, in the present invention, the rare earth cobalt material is represented by the general formula R _{o Con} ,
Using one or more rare earth elements as R,
The main component is cobalt, or cobalt, and some of it may be replaced with iron, copper, vanadium, or other metals. Embodiments of the present invention will be described below with reference to the drawings. In the drawings, Figure 1 shows the crystal structure and easy magnetization direction of the RCo ₅ type rare earth cobalt alloy. However, black circles represent R atoms, white circles represent Co atoms, and Figure 2 shows the RCo ₅ type rare earth cobalt alloy. A graph showing the temperature dependence of the direction of easy magnetization of cobalt alloys.
FIG. 3 is a graph similar to FIG. 2 for the R ₂ Co ₁₇ type alloy. FIG. 1 shows a hexagonal RCo ₅ type rare earth cobalt crystal having a CaCu ₅ type crystal structure. In materials used as permanent magnet materials, the magnetic anisotropy generally has an extremely large magnetic anisotropy constant with the C-axis (abbreviation of A-axis) of the crystal as the easy axis of magnetization, and the direction of the hard axis of magnetization is several
There are some materials whose magnetization does not saturate unless a magnetic field of 100 KOe is applied. However, depending on the type of R and the type and amount of elements substituted for Co, the axis of easy magnetization may be placed on the basal plane (abbreviation of P-Plane) or on the conical plane (C-Plane) depending on the temperature.
(abbreviation for Cone). R ₂ Co ₁₇ type rare earth cobalt has a hexagonal or rhombohedral crystal depending on the composition and temperature, but the magnetic anisotropy is temperature dependent with the easy axis of magnetization being either the C axis, basal plane, or conical plane of the crystal. Show your gender. Figures 2 and 3 show RCo ₅ type and
Changes in the easy axis of magnetization of R ₂ Co ₁₇ type rare earth cobalt due to absolute temperature are shown using the above symbols A (C axis direction), C (conical surface) and P (bottom surface) (Japan Institute of Metals Bulletin No. Volume 16, No. 2 (1977, page 79). Note that the dotted line in the same figure means undecided or speculation. In the case of RCo type ₅ rare earth cobalt, the axis of easy magnetization shows temperature dependence when the rare earth element is Pr, Nd, Tb, Dy, or Ho. In the case of R ₂ Co ₁₇ type rare earth cobalt material, the axis of easy magnetization shows temperature dependence when the rare earth element is Lu. The temperature at which the axis of easy magnetization changes can be adjusted depending on the type of rare earth element. The easy magnetization direction of the R ₂ Co ₁₇ type material shown in Figure 3 can be adjusted by adding additive elements such as copper, iron, vanadium, etc. to the R ₂ Co ₁₇ type material. Can be done.
It is clear from the following table that when cobalt in the R ₂ Co ₁₇ type rare earth cobalt material is replaced with iron, the direction of easy magnetization of the material at room temperature changes.

[Table] In the present invention, a material whose easy magnetization direction changes depending on temperature, such as the above-mentioned rare earth cobalt alloy, is used as a magnetic flux passage means, and the easy magnetization direction changes from the base surface to the C-axis direction or vice versa. This fact is used to switch the direction of magnetic flux within the temperature/magnetic field converter. Specifically, 2 made of rare earth cobalt alloy
When using more than one metal piece and either the C-axis or the base surface is in the direction of easy magnetization, the magnetic flux of the permanent magnet will flow along either the C-axis or the base surface of any of these metal pieces. The metal pieces may be arranged so that the magnetic flux escapes to the outside of the temperature/magnetic field converter, and so that the magnetic flux does not escape to the outside at a temperature where either the C-axis or the basal plane is in the direction of easy magnetization. In the present invention, a soft magnetic material whose direction of easy magnetization does not change with temperature is also used as a magnetic flux path generation means, and the magnetic flux path made of the soft magnetic material forms a closed loop of magnetic flux with a piece of rare earth cobalt metal, and the magnetic flux is completely controlled by the temperature.・Confined within the magnetic field converter. On the other hand, if the closed loop is composed only of rare earth cobalt materials and permanent magnets, the magnetic flux will change depending on the temperature.
A small amount leaks outside the magnetic field converter, reducing the sensitivity of temperature change detection. Next, a specific example of the temperature/magnetic field converter will be explained based on the drawings. In FIG. 4, 1, 1' and 2 are first magnetic materials 1, 1' and second magnetic materials 2, respectively, such as rare earth cobalt alloys whose easy magnetization direction changes with temperature, and whose C-axis The direction is → mark and ◎
It is shown in The C-axis direction of the first magnetic materials 1, 1' is perpendicular to the plane of the paper, and the C-axis direction of the second magnetic material 2 is parallel to the plane of the paper and faces upward. 3 and 3' are two soft magnetic materials such as permalloy, which are in contact with both poles of the permanent magnet 4. The first magnetic material 1, 1' is composed of two soft magnetic materials 3,
3'. The second magnetic material 2 is connected to one magnetic pole N of the permanent magnet via a soft magnetic material 3'. In FIG. 5A, at a temperature where the base surfaces of the magnetic materials 1, 1', and 2 are in the direction of easy magnetization, the permanent magnet 4
The magnetic flux between the north and south poles of soft magnetic materials 3, 3'
and the first magnetic materials 1 and 1', forming a closed loop, and does not leak to the outside of the temperature-magnetic field converter 10. On the other hand, when the temperature reaches such a point that the C-axis is in the direction of easy magnetization, magnetic flux does not pass through the first magnetic materials 1 and 1', and the magnetic flux flows outward from the second magnetic material 2. A switch made of a magnetic material is placed at a position where leakage magnetic flux is detected, and the switch is configured so that the switch is closed by the leakage magnetic flux. Figures 6A and 6B show that the first magnetic materials 1, 1', 2 and the soft magnetic materials 3, 3' are arranged differently from those in Figure 4, and the magnetic flux is transferred to the outside at a temperature where the base surface is in the direction of easy magnetization. This is an example of a temperature/magnetic field converter 10 that is configured to leak. Various arrangements are possible for rare earth cobalt materials and soft magnetic materials, not limited to the specific examples shown in FIGS. 4 and 5, but the point is that both magnetic poles N and S of the permanent magnet 4
two soft magnetic materials 3, 3' respectively connected to;
At least the first magnetic material 1, 1' whose axis of easy magnetization changes with temperature is connected to the two soft magnetic materials 3, 3', and the permanent magnet 4 via either the soft magnetic material 3, 3'. A temperature magnetic field converter may be constituted by a second magnetic material 2 connected to one of the magnetic poles, whose easy axis direction is orthogonal to the first magnetic materials 1, 1', and whose easy axis of magnetization changes with temperature. FIG. 7 is a drawing showing a specific example of the present invention in which a temperature switch is constructed using the temperature/magnetic field converter 10 of FIG. 4. One fixed terminal 11a of the switch element is fixed to one end of the second magnetic material 2, and is opposed to the other movable terminal 11b. The movable terminal 11b of the switch element is made of a soft magnetic material such as permalloy. As shown in the figure, when the C-axis direction becomes the direction of easy magnetization and the magnetic flux of the permanent magnet 4 leaks out from the second magnetic material 2, the permanent magnet 4 overcomes the spring force of the element 11b and fixes it. terminal 1
1a and the switch element is connected via contacts 12, such as W-Ag alloy. As a result,
A current is passed through an electrical circuit including power source 13, lead wire 14, and load 15. Next, when the rare earth base plane becomes easy to magnetize, the movable terminal 1 of the switch element
1b returns to the switch open (OFF) position due to its elasticity. The movable terminal 11b of the switch element is not limited to the one shown in FIG. 7, but may be any terminal made by attaching a soft magnetic material to a leaf spring or the like by adhesive or crimping, as long as it can be closed (ON) by leakage magnetic flux. It's good to be warm. Incidentally, rare earth cobalt alloys used as permanent magnets, such as SmCo ₅ , have an easy magnetization direction in the C-axis direction at room temperature or below. By pressing a material whose C axis is the axis of easy magnetization below room temperature in a magnetic field near room temperature, a material with large magnetic anisotropy and stable magnetic properties near room temperature can be obtained. The easy magnetization directions of substantially all the alloys constituting the permanent magnet are aligned. On the other hand, in order to switch the temperature switch at a temperature higher than room temperature, when compacting fine powder in a magnetic field, the powder in the compact must be heated above the temperature at which the direction of easy magnetization changes from the basal plane to the C axis. It is necessary to perform powder compaction in a magnetic field. By doing so, the magnetization directions can be easily aligned. According to the present invention, since the switch is opened and closed by utilizing the temperature change in the direction of easy magnetization, which is a unique physical property value of the rare earth cobalt alloy, there is an advantage that there is no change in the opening/closing temperature over time. Furthermore, since rare earth cobalt alloy is used as the magnetic flux path,
The temperature switch is made smaller. Furthermore, if a rare earth cobalt alloy (naturally, the direction of easy magnetization does not change) is used as the permanent magnet 4, the saturation magnetization of this alloy is high, which increases the switching force of the switch, making it possible to switch and close large currents. There is also the advantage of being Example A SmCo ₅ type magnet was used as a permanent magnet, and NdCo _5.2 was used as the first and second magnetic materials whose easy magnetization direction changes with temperature. Moreover, soft iron was used as the soft magnetic material. Add these materials to the fourth
Arrange as shown in Figures 7 and 7, and make the overall dimensions 5 x 5 x 10.
(mm). A temperature range of -20°C to 0°C, where the direction of easy magnetization of NdCo _5.2 changes from the basal plane to the C-axis direction, was passed over 50,000 times, and a current of 10 A was repeatedly turned on and off. No change in switch temperature over time was observed during repeated testing.

[Brief explanation of drawings]

Figure 1 is a diagram showing the crystal structure and easy magnetization direction of RCo ₅ type rare earth cobalt alloy. However, the black circles are R
Atoms, white circles represent Co atoms, and Figure 2 shows
A graph showing the temperature dependence of the easy magnetization direction of the RCo ₅ type rare earth cobalt alloy. Figure 3 is a graph similar to Figure 2 for the R ₂ Co ₁₇ type rare earth cobalt alloy. Figure 4 shows the temperature dependence of the temperature sensor of the present invention. A cross-sectional view showing a specific example of a magnetic field converter, Figure 5 A and B are conceptual diagrams explaining changes in magnetic flux in the converter in Figure 4, and Figure 6 A and B show different temperatures and magnetic fields from those in Figure 4. A drawing similar to FIG. 5 A and B regarding the converter, and FIG.
FIG. 2 is a conceptual diagram of a temperature switch according to one specific example. 1, 2... First and second magnetic materials made of rare earth cobalt alloy, 3... Soft magnetic material, 4...
...Permanent magnet, 10...Temperature/magnetic field converter, 13...
...power supply, 15...load.

Claims (1)

[Scope of Claims] 1. A magnetic flux generating part made of a permanent magnet, a first magnetic flux passage part made of a rare earth cobalt alloy material whose axis of easy magnetization changes with temperature, and a second magnetic flux passage part made of a soft magnetic material, Each of the above magnetic fluxes is arranged such that the magnetic flux passes through the converter on either a lower temperature side or a higher temperature side than the temperature at which the axis of easy magnetization of the rare earth cobalt alloy changes, and leaks out of the converter on the other side. Temperature formed by combining parts
A temperature switch equipped with a magnetic field converter and a current breaker that is opened and closed by magnetic flux leaking outside the converter, wherein the temperature/magnetic field converter 10 includes a permanent magnet 4 forming a core, and a permanent magnet 4 forming a core body. two soft magnetic materials 3, 3' respectively connected to both magnetic poles of 4; and at least the rare earth cobalt alloy connected to the two soft magnetic materials 3, 3' whose axis of easy magnetization changes with temperature. a first magnetic material 1, 1' installed such that the axis of easy magnetization on either the side or the high temperature side is parallel or perpendicular to the magnetization direction of the permanent magnet 4; and the soft magnetic material 3, 3'. Depending on the temperature, the easy axis direction of magnetization, which is set perpendicularly to the easy axis direction of magnetization of the first magnetic material 1, 1', is connected to one magnetic pole of the permanent magnet 4 through either A second magnetic material 2 made of the rare earth cobalt alloy that changes
Therefore, the current breaker is connected to the permanent magnet 4 by the fixed terminal 11a fixed to one end of the second magnetic material 2 and the magnetic flux leaking out of the converter 10 disposed opposite to the fixed terminal. A temperature switch characterized in that it is a switch element including a movable terminal 11b made of a soft magnetic material that is attracted and connected to the fixed terminal 11a.