JP2003068177A - Adaptive overcurrent detecting cutout element allowing setting of detection level - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive adaptive overcurrent detecting cutout element allowing an overcurrent detection level to be set arbitrarily from the outside or by a electric potential at both ends of the element. SOLUTION: This adaptive overcurrent detecting cutout element comprises a pair of electromagnetic poles in the magnetic circuit of a permanent magnet, insulating oil and conductive temperature sensing magnetic substance fine powder between the pair of electromagnetic poles, and an electromagnet having a magnetic circuit partly formed of the pair of electromagnetic poles. The conductive temperature sensing magnetic substance fine powder is as small as approx. 0.2 to 0.3 micron meter which is enough not to lose temperature sensing ferrite magnetism. A gold of approx. 100 Å is coated on the surface of the powder. The amount of the conductive temperature sensing magnetic substance fine powder arrested between the pair of electromagnetic poles by the electromagnet is controlled to vary an electric resistance between the pair of electromagnetic poles so as to vary a produced heat quantity in order to change an overcurrent level which leads the temperature to a Curie-point as the result of temperature rising.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overcurrent detection cutoff element, and in particular, it is made to return and conduct after a fixed time after cutoff, and the overcurrent detection level is changed by the presence or absence of a potential across the element. Related to the overcurrent detection cutoff element.

[0002]

2. Description of the Related Art A means for detecting a current flowing through a device and stopping power supply to the device when an overcurrent is detected has been used for a long time and is widely used as a safety measure for the device and its surroundings. In addition, an inexpensive element is also widely known and known as a PCT, in which an overcurrent is detected and interrupted on the assumption that an overcurrent is caused by a temporary overload, and then a return conduction is performed after a certain time. However, the overcurrent detection level of these overcurrent detection interrupting elements cannot be arbitrarily controlled from the outside by setting during designing and manufacturing. Furthermore, there is no inexpensive element that can set the detection level according to the potential state across the overcurrent detection cutoff element.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to realize and provide an inexpensive adaptive overcurrent detection cutoff device in which the overcurrent detection level can be set externally or by the potential across the device.

[0004]

An adaptive overcurrent detection interrupting element according to the present invention comprises an electromagnetic pole pair in a magnetic circuit of a permanent magnet, an insulating oil between the electromagnetic pole pair, and a conductive temperature-sensitive magnetic fine powder. , An electromagnet having the electromagnetic pole pair as a part of a magnetic circuit. The conductive temperature-sensitive magnetic fine powder is small enough not to lose the magnetism of the temperature-sensitive ferrite, and is made to have a thickness of about 0.2-0.3 μm, and the surface is coated with about 100Å of gold.

The permanent magnet captures the conductive temperature-sensitive magnetic substance fine powder as a part of the magnetic circuit between the electromagnetic pole pairs and bridges them to make them electrically conductive. The current flowing between the pair of electromagnetic poles generates heat due to the minute electric resistance between the pair of electromagnetic poles, but if the amount of heat generation is small, the temperature rise is suppressed to a certain level in equilibrium with the amount of heat that escapes to the surroundings. When the current exceeds a predetermined level, the amount of heat generated increases and the temperature rises. When the temperature exceeds the Curie temperature of the conductive thermosensitive magnetic powder, the conductive thermosensitive magnetic powder loses magnetism and is separated from the magnetic flux between the electromagnetic pole pairs. As a result, the electrical resistance between the electromagnetic pole pairs is significantly increased, and the current is cut off. When the temperature falls and becomes equal to or lower than the Curie temperature, the magnetism returns to the conductive temperature-sensitive magnetic substance fine powder, is again captured between the electromagnetic pole pairs, the electric resistance between the electromagnetic pole pairs is reduced, and the current flows.

Since the electromagnet shares the electromagnetic pole pair with the permanent magnet and the conductive temperature-sensitive magnetic fine powder as a part of the magnetic circuit, when the magnetic flux from the electromagnet is current-driven so as to reduce the magnetic flux of the permanent magnet between the electromagnetic pole pairs, It is possible to control the amount or density of the conductive temperature-sensitive magnetic substance fine powder captured between the pole pairs by the electromagnet. Therefore, the electric resistance between the electromagnetic pole pairs changes, so the amount of heat generated changes, and the amount of overcurrent leading to current interruption can be controlled by the electromagnet.

As described above, it is possible to change the overcurrent detection level by controlling the movement of the conductive temperature-sensitive magnetic substance fine powder between the electromagnetic pole pairs by the electromagnet, but the conductive temperature-sensitive magnetic substance fine powder moved by the electromagnet drives the electromagnet. The overcurrent detection level can be maintained for a certain period of time if it is configured such that it does not immediately return to the original state even after changing the condition and gradually returns after a certain period of time. The adaptive overcurrent detecting element of the present invention is realized by moving the fine particles of the conductive magnetic material by the electromagnet between the areas where the openings are restricted or where the fibrous material is present. The electromagnet is configured to be driven by a current flowing from both ends of the element to a common potential, and the overcurrent detection level is set depending on the presence / absence of the potential across the element, and the overcurrent detection level is maintained for a certain period of time. An overcurrent detection cutoff element has been realized.

[Operation] As described above, the conductive temperature-sensitive magnetic substance fine powder is enclosed between the electromagnetic pole pairs in the magnetic circuit of the permanent magnet, and the conductive temperature-sensitive magnetic substance fine powder between the electromagnetic pole pairs can be controlled by the electromagnet. The overcurrent detection level can be set arbitrarily. Also, by giving a time constant to the movement of the conductive temperature-sensitive magnetic substance fine powder, the overcurrent detection level can be maintained for a certain period of time, and the overcurrent detection level can be changed depending on the presence or absence of the potential across the element. Realized the element.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments and principles of the adaptive overcurrent detection interrupting device according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment according to the present invention, in which (a) is a sectional view, and (b) and (c) are perspective views around the electromagnetic pole pair. Electromagnetic pole pairs 11 and 12 face each other with a gap, and insulating oil and conductive temperature-sensitive magnetic fine powder 31 are placed between them.
And the permanent magnet 21, the electromagnetic pole pairs 11 and 12, and the conductive temperature-sensitive magnetic substance fine powder 31 form a magnetic circuit. The number 22 indicates the magnetization direction of the permanent magnet 21, and the number 23 indicates the magnetic flux leaking from the permanent magnet 21. The conductive temperature-sensitive magnetic substance fine powder 31 is trapped by the magnetic field between the electromagnetic pole pairs 11 and 12, and bridges and conducts the two. The electromagnet has a core 24 and a coil 25.
And a magnetic field is applied to the electromagnetic pole pairs 11 and 12 by the drive current applied to the lead wire 26. Shows a cross section (a)
Although not clear in the figure, the electromagnet is arranged so as to apply a magnetic field to the front side of the electromagnetic pole pairs 11 and 12 shown in FIG. The conductive temperature-sensitive magnetic substance fine powder 31 is made of a temperature-sensitive ferrite which is small enough not to lose its magnetism, and has a thickness of about 0.2 to 0.3 μm and is formed by coating the surface with about 100 Å of gold. Numbers 41 and 42 are electromagnet and electromagnetic pole pair 1, respectively.
The resin in which 1 and 12 are sealed and fixed is shown.

In such a structure, the conductive temperature-sensitive magnetic substance fine powder 31 conducts between the electromagnetic pole pairs 11 and 12, but has a small resistance to heat up. If the calorific value is small, the heat is dissipated to the surroundings, and the temperature rise is minute and balanced. However,
When an excessive current flows, the amount of heat generated increases and the temperature rises rapidly.
When the temperature exceeds the Curie temperature of the conductive temperature-sensitive magnetic substance fine powder 31, the conductive temperature-sensitive magnetic substance fine powder 31 loses its magnetism, and the conductive temperature-sensitive magnetic substance fine powder 31 was bridging between the electromagnetic pole pairs 11 and 12.
Is separated into pieces and floats in the insulating oil, and the conduction between the electromagnetic pole pairs 11 and 12 is lost. When the temperature of the conductive temperature-sensitive magnetic substance fine powder 31 becomes less than the Curie temperature with the passage of time, the magnetism is regained and the electromagnetic pole pairs 11, 12 are bridged,
Make it conductive.

Since the gap between the electromagnetic pole pairs becomes larger toward the right side as shown in FIG. 3B, the conductive temperature-sensitive magnetic substance fine powder 31 is concentrated in the narrow gap portion on the left side. The electromagnet is arranged so as to apply a magnetic field to the left side of the electromagnetic pole pairs 11 and 12, and when a magnetic field in the opposite direction to the permanent magnet 21 is applied to reduce the amount of magnetic flux between the left half electromagnetic pole pairs 11 and 12. , The conductive temperature-sensitive magnetic substance fine powder is displaced to the right where the magnetic flux density becomes large, as indicated by reference numeral 32 in FIG. However, since the gap between the right halves of the electromagnetic pole pairs 11 and 12 is set to be large, the electric resistance is large, and even a small amount of current can easily heat and raise the temperature. That is, it is possible to control the detection level of the overcurrent which is interrupted by the amount of the drive current flowing through the coil 26 of the electromagnet.

FIG. 2 shows a second embodiment of the present invention,
The figure (a) shows a cross-sectional view, and the figures (b) and (c) show plan views around the electromagnetic pole pair. In the second embodiment, a part of the magnetic circuit of the permanent magnet 21 shares the conductive temperature-sensitive magnetic substance fine powder 31 and the insulating oil in the gap as shown in FIG. Pole pair 11,13, second electromagnetic pole pair 13,1
4 and the second pair of electromagnetic poles 13 and 14 and an electromagnet whose gap is a part of a magnetic circuit. A fibrous material layer 44 is arranged between the first electromagnetic pole pair 11 and 13 and the second electromagnetic pole pair 13 and 14 to form a movement resistance of the conductive temperature-sensitive magnetic substance fine powder 31.

The first and second electromagnetic pole pairs are one electromagnetic pole 1
3 is common. As shown in Figure (b), the gap between the electromagnetic pole pairs is configured so that the center is small and both ends are large, so no current is passed through the electromagnet. The conductive temperature-sensitive magnetic substance fine powder 31 concentrates on the surface of the first magnetic pole pair 11 and bridges the first electromagnetic pole pair 11 and 13 to make them conductive.

When a current is applied to the coil 25 of the electromagnet in FIG. 3C and a magnetic flux in the same direction as the permanent magnet 21 is driven so as to pass between the second electromagnetic pole pairs 13 and 14, the second electromagnetic pole pair 13 and Since the amount of magnetic flux between 14 is large, the conductive thermosensitive magnetic substance fine powder gathers between the second electromagnetic pole pairs 13 and 14 through the fibrous material 44 as indicated by numeral 33. As a result, the electric resistance between the first electromagnetic pole pair 11 and 13 becomes large, heat is easily generated, and the overcurrent detection level is lowered.

Since the fibrous material layer 44 is located between the first and second electromagnetic pole pairs, it takes time to move the fine particles of the conductive temperature-sensitive magnetic substance, and it takes a certain period of time even after the driving condition of the electromagnet changes. Maintains the previous overcurrent detection level. If two electromagnet coils are provided and a current flows from both ends of the element to a common potential in each of them, there is a potential at both ends of the element, there is a potential at only one side of the element, and there is no potential at both ends of the element. Different overcurrent detection levels can be set according to the conditions, and can be maintained for a certain period of time. The fibrous material layer 44 can also be composed of a wall provided with slits or minute holes.

FIG. 3 shows a third embodiment of the present invention,
(A), (b) figure is sectional drawing of the 2nd and 3rd electromagnetic pole pair periphery, and (c) figure shows the planar arrangement of the 1st and 3rd electromagnetic pole pair. In the figure, the first electromagnetic pole pair 15, 16 and the second electromagnetic pole pair 17, 18 arranged in the magnetic circuit of the permanent magnet 21 are electrically independent, and the conductive temperature-sensitive magnetic substance fine powder is present in the gap. 35 and 34 respectively. Second electromagnetic pole pair 1
7, 18 and the third electromagnetic pole pair 19, 20 are the fibrous material layer 4
7 are adjacent to each other and share the conductive temperature-sensitive magnetic substance fine powder and the insulating oil. The electromagnet including the core 24 and the coil 25 is configured such that the third electromagnetic pole pair 19, 20 is arranged in the magnetic circuit. Furthermore, the first electromagnetic pole pair 15,1
6 and the third electromagnetic pole pair 19, 20 are electrically connected in parallel.

As such a structure, the first electromagnetic pole pair 1
The magnetic flux of the permanent magnet always passes through the gaps 5 and 16, and the conductive magnetic fine powder 35 conducts a bridge. Second electromagnetic pole pair 17,1
8, and the conductive temperature-sensitive magnetic substance fine powder 34 between the third electromagnetic pole pair 19 and 20 is shared, so that it moves between them due to the magnetic flux of the electromagnet. In the figure (a), the electromagnet is not driven, and in the figure (b), the electromagnet is driven, and a part of the conductive temperature-sensitive magnetic substance fine powder 34 is moved between the third electromagnetic pole pairs 19 and 20. Show the situation. The number 27 indicates the magnetic flux generated by the electromagnet.

FIG. 3C is a plan view showing the arrangement of the first electromagnetic pole pairs 15 and 16 and the third electromagnetic pole pairs 19 and 20 as viewed from above. The conductive temperature-sensitive magnetic substance fine powder 36 is a part of the conductive temperature-sensitive magnetic substance fine powder 34.

Since the first and third electromagnetic pole pairs are electrically connected in parallel, the electric resistance is small when the electromagnet is driven as shown in (b) and the electromagnet as shown in (a). Has a high electric resistance when is not driven. Therefore, as in the first and second embodiments, the overcurrent detection level can be arbitrarily set depending on whether or not the electromagnet is driven. Since the fibrous material layer 47 provides the movement resistance of the conductive temperature-sensitive magnetic substance fine particles 34, the overcurrent detection level can be maintained for a certain period of time as in the second embodiment. The major difference between the second and third embodiments is the difference in the moving cross-sectional area of the conductive temperature-sensitive magnetic substance fine powder.
The third embodiment is suitable for moving many conductive fine particles of the temperature-sensitive magnetic substance. Further, as in the second embodiment, two electromagnet coils 25 are provided, and if they are connected so as to be driven by a current from both ends of the element to a common potential, overcurrent detection in three stages depending on the presence or absence of a potential at both ends of the element. You can set the level.

[0020]

As described above with reference to the embodiments, according to the adaptive overcurrent detection cutoff element of the present invention, the overcurrent detection cutoff element can arbitrarily set the overcurrent detection level by the drive current of the electromagnet. Can be configured. In addition, the overcurrent detection level can be maintained for a certain period of time even if the electromagnet drive conditions are changed. Further, the electromagnet is driven by the current from both ends of the element to the common potential, and the overcurrent detection level can be set by the presence or absence of the potential across the element. An adaptive overcurrent detection cutoff element can be realized.
It is suitable for fields where it is necessary to set the overcurrent detection level depending on the situation, such as power supply wiring.

[Brief description of drawings]

FIG. 1 shows a structure of a first embodiment, FIG. 1A is a sectional view of a structure including an electromagnetic pole pair, and FIGS. 1B and 1C are perspective views around the electromagnetic pole pair.

2A and 2B show a structure of a second embodiment, FIG. 2A is a cross-sectional view of a structure including an electromagnetic pole pair, and FIGS. 2B and 2C are plan views around the electromagnetic pole pair.

FIG. 3 shows a structure of a third embodiment, (a), (b)
The figure shows a cross-sectional structure, and the figure (c) shows a plan view including an electromagnetic pole pair.

[Explanation of symbols]

11, 12, 13, 14, 15, 16, 17, 18, 1
9, 20, ... Electromagnetic pole, 21 ... Permanent magnet,
22 ... Magnetization direction, 23 ... Magnetic flux from permanent magnet, 24 ... Core, 25 ... Coil,
26 ... Lead wire of coil,
27 ... Magnetic flux from electromagnet, 31, 32, 33, 3
4,35,36 ... Electroconductive magnetic fine powder, 41, 42, 4
5,46 .. Casing, 44, 47 .. Fibrous material layer

Claims (9)

[Claims] 1. A permanent magnet, an electromagnetic pole pair facing each other, a conductive temperature-sensitive magnetic substance fine powder and an insulating liquid in a gap between the permanent magnet, an electromagnet, and an electromagnetic pole pair, a conductive temperature-sensitive magnetic substance. Fine powder, insulating liquid, etc. form a part of the magnetic circuit of the permanent magnet, and the electric resistance between the electromagnetic pole pairs is increased by increasing or decreasing the amount of conductive temperature-sensitive magnetic substance fine powder that bridges conduction between the electromagnetic pole pairs with the electromagnet. In addition, the overcurrent detection cutoff level is controlled by changing the amount of heat generated by the current flowing between the electromagnetic poles and changing the current value level at which the temperature of the temperature-sensitive magnetic fine particles rises and the current is cut off due to loss of magnetism. Adaptive overcurrent detection cutoff element 2. The adaptive overcurrent detection interrupting element according to claim 1, wherein the conductive temperature-sensitive magnetic fine powder is formed by coating the surface of the magnetic fine powder which loses magnetism at a certain temperature or higher with a conductive material. Overcurrent detection interrupting device characterized by 3. The adaptive overcurrent detection interrupting element according to claim 2, wherein the conductive material coating the surface of the temperature-sensitive magnetic fine powder is a material suitable for electrical contact materials such as gold, platinum, palladium, etc. Adaptive overcurrent detection interrupting device characterized by 4. The adaptive overcurrent detection interrupting device according to claim 1, wherein the electromagnetic pole pair is an electrically independent first and second electromagnetic pole pair sharing a conductive temperature-sensitive magnetic substance fine powder. And the electric resistance between the first electromagnetic pole pair is changed by changing the amount of magnetic flux between the first and second electromagnetic pole pairs by the electromagnet, and the overcurrent detection level of the current flowing between the first electromagnetic pole pair is changed. Type overcurrent detection cutoff device characterized by controlling 5. The adaptive overcurrent detection interrupting element according to claim 4, wherein a fibrous material, a shielding plate having small holes or slits, etc. is provided between the first and second electromagnetic pole pairs. Adaptive overcurrent detection interrupting device characterized by forming a movement resistance of conductive temperature-sensitive magnetic fine particles and giving a time constant to change of overcurrent detection level 6. The adaptive overcurrent detection interrupting element according to claim 5, wherein the current flowing through the electromagnet is a current flowing between both ends of the element and a common potential. Breaking element 7. The adaptive overcurrent detection interrupting element according to claim 1, wherein the electromagnetic pole pairs are electrically independent first and second electromagnetic pole pairs each having conductive temperature-sensitive magnetic fine particles. age,
Furthermore, a third electromagnetic pole pair, which shares a conductive temperature-sensitive magnetic substance fine powder with the second electromagnetic pole pair and is magnetically independent, is adjacent to the second electromagnetic pole pair, and the third electromagnetic pole pair is connected by the electromagnet. The electric resistance between the third electromagnetic pole pair is changed by changing the magnetic flux intensity between them, and the overcurrent detection level of the current flowing between the first and third electromagnetic poles connected in parallel is controlled. Adaptive overcurrent detection cutoff element 8. The adaptive overcurrent detection interrupting element according to claim 7, wherein a fibrous material is provided between the second and third electromagnetic pole pairs so as to provide a movement resistance of the conductive temperature-sensitive magnetic substance fine powder. An adaptive overcurrent detection interrupting element characterized by providing a shield plate having small holes or slits and providing a time constant for changes in overcurrent detection level 9. The adaptive overcurrent detection interrupting element according to claim 8, wherein the current flowing through the electromagnet is a current flowing between both ends of the element and a common potential. Breaking element