JP3158804B2 - Temperature sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature sensor used for detecting abnormal overheating of a conductor in a current-carrying portion of a power device or the like.

[0002]

2. Description of the Related Art Since a high voltage is applied to a conductor in a current-carrying part of a power device and a large current flows, the conductor may overheat. For this reason, a thermo label is attached to the conductor to observe a change in color from a distance to detect abnormal overheating, or to detect an abnormal overheating state of the conductor using a thermo camera. In addition, there are a thermocouple, a thermometer, a thermistor, and the like for measuring the temperature of the conductor.

[0003]

In order to detect abnormal overheating of a conductor of a power device as described above, first, a thermo label,
Secondly, there is a thermo camera. Although a thermo label is inexpensive, there is a problem that it cannot be constantly monitored unless a method for detecting a change in color is considered, and there is also a problem that its durability is poor.

On the other hand, although a thermo camera is expensive, there is a problem in long-term stability of a sensor portion. In addition, thermocouples, thermometers and thermistors have the problem that they need to be electrically insulated and cannot be directly attached to conductors. Each of these temperature sensors measures the temperature transmitted to a gas or insulator. There is a problem of low sensitivity and the influence of other heat sources is great.

Accordingly, an object of the present invention is to solve such a problem and to provide a temperature sensor which is durable, can be directly attached to a conductor, and has high sensitivity.

[0006]

In order to achieve the above object, the present invention has a columnar structure having first and second ends on both end surfaces.
Temperature-sensitive magnetic material having a concave portion and changing from a ferromagnetic state to a paramagnetic state with an increase in temperature, a first permanent magnet fitted into the first concave portion, and an axial direction in the second concave portion. A second permanent magnet that is movably disposed in such a manner that magnetic poles opposed to the first permanent magnet have the same magnetic pole; and a second permanent magnet that is coupled to an anti-first permanent magnet side of the second permanent magnet. And a heating display member projecting from the second recess when the second permanent magnet moves from the second recess toward the side opposite to the first recess when the temperature-sensitive magnetic material becomes higher than the operating temperature. A first hole for communicating the first and second recesses in the axial direction, and a second hole for communicating with the first hole are formed in the first permanent magnet, A rod for confirming the operation of the second permanent magnet is inserted into the first and second holes, and the second permanent magnet is inserted. And it is characterized in that so as to move the heating display member.

[0007]

When the temperature-sensitive magnetic material is lower than the operating temperature, the temperature-sensitive magnetic material enters a ferromagnetic state and does not affect the magnetic forces of the first and second permanent magnets. For this reason, the second permanent magnet does not move and the overheat display member fixed to the second permanent magnet does not move to the second permanent magnet.
Does not protrude from the recess. However, when the temperature-sensitive magnetic material becomes higher than the operating temperature and becomes a paramagnetic material, the magnetic forces of the first and second permanent magnets mutually affect each other, and
Receives the repulsive force of the first permanent magnet, moves in a direction away from the first permanent magnet, and the overheat display member protrudes from the second recess.

Further, in order to confirm whether the second permanent magnet operates reliably, a rod for operation confirmation is inserted into the first and second holes, and the second permanent magnet is pushed. If there is no problem, the second permanent magnet moves and the overheat indicating member connected to the second permanent magnet projects from the second recess.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 10 denotes a temperature sensor, and the temperature sensor 10 is configured as follows.
11 first across a cylindrical temperature-sensitive magnetic substance in which the second recess 12, 13 has been drilled, M _n -Z _n type soft ferrite of the temperature-sensitive magnetic substance 11 have a corrosion resistance It is composed of A columnar first permanent magnet 14 is fitted and adhered to the first concave portion 12 of the temperature-sensitive magnetic body 11, for example, in the direction of the illustrated magnetic pole. Reference numeral 15 denotes a temperature-sensitive magnetic bottom cover adhered to the bottom surface of the temperature-sensitive magnetic body 11.

An overheat indicator 16 made of a nonmagnetic material is loosely fitted in the second recess 13 of the temperature-sensitive magnetic body 11. The overheat indicator 16 has a bottomed cylindrical shape and a cylindrical display portion 16a is integrally formed. A second permanent magnet 17 is fitted and adhered inside the overheat indicator 16, and the lower magnetic pole of the second permanent magnet 17 is
The first permanent magnet 14 is set to have the same magnetism as the upper magnetic pole. The reason why the second permanent magnet 17 is covered with the non-magnetic material is to make the second permanent magnet 17 slip easily with the temperature-sensitive magnetic body 11 in the second concave portion 13. This is to prevent slippage due to the effect of residual magnetic flux when the permanent magnet is brought into direct contact with the temperature-sensitive magnetic body, thereby preventing this. Here, a ferrite-based permanent magnet having high corrosion resistance is used as the permanent magnet.
Reference numeral 18 denotes a nonmagnetic upper lid adhered to the upper end surface of the temperature-sensitive magnetic body 11, and the upper lid 18 has an insertion hole 18a for inserting the display unit 16a.

The second permanent magnet 17 does not move from the position shown in FIG. 2 since it shows a ferromagnetic state when the temperature-sensitive magnetic material 11 is lower than the Curie temperature (operating temperature). Since the magnetic body 11 is in a paramagnetic state, the first and second permanent magnets 14 and 17 are magnetically repulsive, and the second permanent magnet 17 moves upward in the drawing to be in contact with the second permanent magnet 17. An integral display 16a projects above the upper lid 18.

FIG. 3 shows the action on the second permanent magnet 17 at the position where the second permanent magnet 17 is in contact with the bottom surface of the second recess 13 in the temperature-sensitive magnetic body 11 (when the stroke X = 0). a characteristic diagram showing how the force varies with temperature, in FIG. 3, the resultant force F is F _S (suction force component: the force acting between the second permanent magnets 17 and the temperature-sensitive magnetic substance 11) F _R
(Repulsive force component: the force of the magnetic force of the first permanent magnet 14 acting on the second permanent magnet 17). The change of the acting force at the Curie temperature (operating temperature) of the temperature-sensitive magnetic body 11 is larger than that at the time of only F _S (or F _R ). FIG. 4 is a measured data characteristic diagram showing a change in the resultant force F with respect to temperature. This indicates that the repulsion force becomes larger than the suction force as the temperature increases.

FIGS. 5A and 5B and FIGS.
(B) shows the first and second permanent magnets 1 when the temperature-sensitive magnetic body 11 changes from a ferromagnetic state to a paramagnetic state depending on temperature.
FIG. 5 (a) shows the state of the lines of magnetic force from lines 4 and 17.
6 shows the state of the magnetic field lines when the temperature-sensitive magnetic body 11 is lower than the Curie temperature, and FIG. 6A shows the state of the magnetic field lines when the temperature-sensitive magnetic body 11 is higher than the Curie temperature. FIG.
From (a), it can be seen that when the temperature is equal to or higher than the Curie temperature, the lines of magnetic force spread and the repulsive force increases as shown in the figure.
FIGS. 5B and 6B are characteristic diagrams showing the relationship between the combined force F acting on the second permanent magnet 17, the repulsive force F _R , and the attraction force F _S.

FIG. 7 is a characteristic diagram showing a force relationship between the temperature-sensitive magnetic material and the second permanent magnet. FIG. 7 shows the relationship between the temperature-sensitive magnetic material at room temperature, about 90 ° C., and 100 ° C. It is data obtained by actually measuring what kind of force acts on the second permanent magnet at a temperature of ° C. For this measurement, a temperature-sensitive magnetic body 11a and first and second permanent magnets 14a and 17a as shown in FIG. 8 were used. In FIG. 8, the second permanent magnet 17a is buried in the second recess 13 depending on the operating temperature of the temperature-sensitive magnetic body 11,
Some protrude.

FIG. 9 is a sectional view showing another embodiment of the present invention. In this embodiment, the first and second concave portions 1 of the temperature-sensitive magnetic body 11 are shown.
A first hole 21 communicating the first and second magnets 2 and 13 in the axial direction; a second hole 22 formed in the first permanent magnet 14 in the axial direction to be in communication with the first hole 21; It is formed in the axial direction of the bottom cover 15 of the body, and includes a third hole 23 which is in communication with the second hole 22. As described above,
By providing the third holes 21 to 23, a thin push rod 24 is inserted into the holes 21 to 23 from below in the figure, and the push rod 24 is inserted.
To push up the second permanent magnet 17. As a result, the display section 16a of the overheat indicator 16 projects upward from the upper lid 18 with the rise of the second permanent magnet 17, so that the operation of the temperature sensor can be confirmed.

[0016]

As described above, according to the first aspect of the present invention, another external magnetic field acts on the second permanent magnet so that the operating temperature does not fluctuate. The magnet can be moved only by the second concave portion of the temperature-sensitive magnetic body, so that other external magnetic fields are less likely to act on the second permanent magnet so as not to affect the operating temperature. Because one permanent magnet is surrounded by a temperature-sensitive magnetic material,
The change of the repulsive force due to the temperature can be increased, whereby the change in the force acting on the second permanent magnet near the operating temperature (Curie temperature) of the temperature-sensitive magnetic material increases, and the operation of the overheat display member becomes stable. It has advantages such as durability, and can be directly attached to a conductor.

According to the second aspect of the invention, the first and the second
The movement of the second permanent magnet can be easily confirmed only by inserting the rod body.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing one embodiment of a temperature sensor according to the present invention.

FIG. 2 is a cross-sectional view of a temperature sensor according to the present invention.

FIG. 3 is a characteristic diagram showing a relationship between a temperature and a force acting on a second permanent magnet.

FIG. 4 is a change characteristic diagram showing a relationship between a temperature and a force acting on a second permanent magnet.

5A is an explanatory diagram showing a distribution state of magnetic force lines generated in the first and second permanent magnets when the temperature is equal to or lower than the Curie temperature, and FIG. 5B is a characteristic diagram of a resultant force.

FIG. 6A is an explanatory diagram showing a distribution state of magnetic lines of force generated in the first and second permanent magnets when the temperature is equal to or higher than the Curie temperature, and FIG. 6B is a characteristic diagram of a resultant force.

FIG. 7 is a characteristic diagram showing a relationship between a temperature, a distance from a temperature-sensitive magnetic body, and a force acting on a second permanent magnet.

FIG. 8 is an explanatory diagram used for measuring the data of FIG. 7;

FIG. 9 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Temperature-sensitive magnetic body 12 ... 1st recessed part 13 ... 2nd recessed part 14 ... 1st permanent magnet 16 ... Non-magnetic overheating indicator 17 ... 2nd permanent magnet 18 ... Non-magnetic top cover

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-34583 (JP, A) JP-A-50-103382 (JP, A) JP-A-5-223654 (JP, A) 168568 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01K 7/36

Claims (2)

(57) [Claims] 1. A temperature-sensitive magnetic body having a columnar shape and having first and second concave portions on both end surfaces and changing from a ferromagnetic state to a paramagnetic state with an increase in temperature, A first permanent magnet fitted therein, a second permanent magnet disposed in the second concave portion so as to be movable in the axial direction, and magnetic poles opposed to the first permanent magnet having the same magnetic pole; The second permanent magnet is coupled to the anti-first permanent magnet side of the second permanent magnet, and the temperature-sensitive magnetic body becomes higher than the operating temperature, and the second permanent magnet moves from the second concave part toward the anti-first concave part side. And a heating display member protruding from the second recess. 2. A first hole for communicating the first and second recesses in the axial direction and a second hole for communicating with the first hole are formed in the first permanent magnet. The temperature sensor according to claim 1, wherein a rod for confirming the operation of the second permanent magnet is inserted into the second hole to move the second permanent magnet and the heating display member.