JP3156505B2 - 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 for monitoring, for example, overheating of a heating device or detecting abnormal overheating of a current-carrying conductor of an electric device by ultrasonic waves.

[0002]

2. Description of the Related Art For example, when a high voltage is applied to a current-carrying conductor of a power device and a large current flows, the conductor may be abnormally overheated. For this reason, a means is employed to detect abnormal overheating by attaching a thermo label to the conductor and observing a change in color from a distance, or to detect an abnormal overheating state of the conductor using a thermo camera. In addition, a thermocouple, a thermometer, and a thermistor may be used to measure the temperature of the conductor.

[0003]

As described above, in order to detect the abnormal overheating of the conductor of the power equipment as described above, the first is a thermo label and the second is a thermo camera, but the first thermo label is inexpensive. However, unless a method for detecting a color change is considered, there is a problem that monitoring cannot be performed at all times and also a problem that durability is poor.

Although the second thermo camera is expensive, it has a problem in long-term stability of the sensor portion. In addition, thermocouples, thermometers and thermistors have the problem that they cannot be directly attached to conductors due to their electrical insulation.These temperature sensors measure the temperature transmitted to gas and insulators, and therefore have low sensitivity. There is a problem, and the influence of other heat sources is great.

[0005] In addition to the above, in recent years, vibration using a permanent magnet made of a temperature-sensitive magnetic material (having a property that a ferromagnetic material changes to a paramagnetic material when the Curie temperature or higher) is used as a current-carrying conductor of a power device. When the ambient temperature of the temperature-sensitive magnetic body (temperature rise of the current-carrying conductor) rises and becomes equal to or higher than the Curie temperature of the magnetic body, a permanent magnet is generated by an AC magnetic field generated by a current flowing through the conductor. Means for detecting abnormal overheating of conductors by utilizing the fact that they become vibrated have been developed. Since the permanent magnet used in this means is made of ferrite material, if it is vibrated for a long time, the permanent magnet and the metal part in contact with it become fine powder and stay inside, and finally become permanent. There is a problem that the magnet cannot vibrate. The reason for this is that when the surface of the magnet in which the powder material is sintered is enlarged, the surface of the magnet is sponge-shaped, and the magnet itself becomes powder while shaving the metal surface by this surface.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a temperature sensor which is durable and which can obtain a magnet which does not wear metal which is in contact with the temperature sensor.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a bolt made of a non-magnetic material and a hollow portion of the bolt portion until it reaches a part of its head. first across the axial direction together with the fitted, a second recess is formed in the axial direction, and the temperature-sensitive magnetic substance that changes from a ferromagnetic state to a paramagnetic state in response to temperature change, the temperature-sensitive magnetic substance A first permanent magnet fitted and adhered to the first recess of the temperature-sensitive magnetic body, and a first permanent magnet fitted in the second recess of the temperature-sensitive magnetic body in the axial direction, and provided between the second recess and the hollow hole. And a second permanent magnet provided so that a magnetic pole facing the first permanent magnet becomes the same magnetic pole while moving toward the head side of the bolt . The second permanent magnet is extruded and polished manganese aluminum It is characterized in that it has constructed using carbon magnet.

[0008]

When the temperature-sensitive magnetic material is below the Curie temperature, it is in a ferromagnetic state, so that the magnetic lines of force of the first and second permanent magnets only pass through the temperature-sensitive magnetic material, and the magnetic lines of force affect each other's magnets. Absent. Thus, the second permanent magnet does not move. However, when the temperature-sensitive magnetic material becomes equal to or higher than the Curie temperature, the magnetic lines of force of the first and second permanent magnets are not affected by the temperature-sensitive magnetic material, and the two magnets influence each other, so that the second permanent magnet is affected. The magnet moves by receiving the repulsive force of the first permanent magnet, and is also affected by the surrounding AC magnetic field. The second permanent magnet vibrates by the AC magnetic field and collides with the inside of the bolt. At this time, since the second permanent magnet uses extruded and polished manganese-aluminum-carbon magnets, the surface of the magnets becomes smooth, and the metal parts on the inner wall surfaces of the bolts must be abraded to powder. There is no.
In addition, since the magnet itself does not become powder and does not cause the magnet to vibrate, a long-time vibration can be generated.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. 1, 2 (a), (b) and 3, reference numeral 1 denotes a hexagonal bolt, and a hole 2 is formed in a shaft portion 2 of the hexagonal bolt 1 from a lower portion to an upper portion in the figure.
A part of the hollow 3 reaches the position of the head 4 of the hexagon bolt 1. Reference numeral 9 denotes a thread portion of the hexagon bolt 1.

Reference numeral 10 denotes a temperature sensor main body, which is configured as follows. Reference numeral 11 denotes a columnar temperature-sensitive magnetic body having first and second concave portions 12 and 13 formed in the axial direction from both ends.
It is made of Zn-based soft ferrite. A columnar first permanent magnet 14 is fitted into and bonded 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 bottom cover made of a non-magnetic material and attached to the hollow 3 of the hexagon bolt 1.

A pipe-shaped second permanent magnet 16 made of a material described later is fitted into the second recess 13 of the temperature-sensitive magnetic body 11. At this time, the lower magnetic pole of the second permanent magnet 16 is fitted so as to have the same polarity as the upper magnetic pole of the first permanent magnet 14 as shown in the figure. Reference numeral 17 denotes a guide rod made of a non-magnetic material. The guide rod 17 is inserted through the hollow portion of the second permanent magnet 16. One end of the guide rod 17 is connected to the first recess 1.
2 is fitted into a hole 18 that connects the second concave portion 13 with the second concave portion 13,
The other end is fitted into the head 4 of the hexagon bolt 1.

The second permanent magnet 16 is a manganese aluminum carbon magnet employing an atomized powder alloy,
The main raw material consists of manganese, aluminum, and carbon, and is a magnet manufactured through the steps of compounding, dissolving, atomizing, forming warm extrusion, cutting rough cylindrical processing, and cylindrical body polishing. This magnet has excellent mechanical strength and does not break due to collision or the like.

Next, the hexagonal bolt 1 having the temperature sensor main body 10 constructed as described above is screwed in to measure the overheated state of the conductor 41a of the conductor connection portion housed in the tank 45 shown in FIG. . At this time, manganese, aluminum,
The second permanent magnet 16 made of a carbon magnet does not move from the position shown in FIG. 2B because it shows a ferromagnetic state when the temperature-sensitive magnetic material 11 is lower than the Curie temperature (operating temperature). Then, since the temperature-sensitive magnetic body 11 becomes paramagnetic, the first and second permanent magnets 14 and 16 are magnetically repulsive, and the second permanent magnet 16 moves upward in the drawing, as shown in FIG. Oscillation is caused by an alternating magnetic field H generated by a current I flowing through the conductor 41a as shown by a symbol V in FIG. This vibration is a thickness t ₁ shown in FIG. 3 of the head 4 of the hexagon bolt 1 is formed thin, from here, the tank 45
Ultrasonic waves are generated in the gas inside. The ultrasound is detected by the receiver ultrasonic sensor 46 shown in FIG. 4, after being amplified by the amplifier 47, level alarm to be the predetermined value or more is emitted is detected by detector 48 at a level determiner 49. This makes it possible to detect an overheated state of the conductor in the tank. Further, as shown in FIG. 4, since the second permanent magnet 16 is formed of a manganese-aluminum-carbon magnet, the surface of the magnet is smooth. In addition, since the magnet itself does not turn into powder, there is an advantage that powder does not stay in the bolt and a long-time vibration can be generated even in the measurement of the overheated state of the conductor.

In the above embodiment, the hollow 3 is shown in FIG.
As shown in (b), it is formed eccentric. This is because the vibration of the second permanent magnet 16 hits the vicinity of the center to increase the ultrasonic wave generated in the tank. At this time, the resonance frequency fr ₁ of the thickness t ₁ portion is the thickness t ₁ of the vibrating portion.
₁ , the diameter D ₁ , and the Young's modulus E _1, are substantially determined by the following equation.

[0015]

(Equation 1)

Here, ρ is a density, σ is a Poisson's ratio, and K ₀ is a constant.

In FIG. 4, 41a and 41b are conductors, 42a and 42b are contacts, 43 is a contact, 44
Is a ring spring, and 50 is a gas seal connector.

[0018]

As described above, according to the present invention,
Since the second permanent magnet is formed of a manganese-aluminum-carbon magnet, the surface of the magnet can be smoothed, and the metal that collides with the magnet does not wear out to powder, and the magnet itself does not become powder. The advantage that long-term vibration can be generated is obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing one embodiment of the present invention.

FIG. 2 (a) is a cross-sectional view of the head of a hexagon bolt, and FIG.
FIG. 2 is a vertical sectional view of the embodiment of FIG. 1 when assembled.

FIG. 3 is a partially enlarged view of FIG. 2 (b).

FIG. 4 is a configuration explanatory view when a temperature sensor is attached to a conductor that is a measurement object.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hex bolt 2 ... Shaft part 3 ... Bored hole 4 ... Head 10 ... Temperature sensor main body 11 ... Temperature sensitive magnetic body 12 ... 1st recess 13 ... 2nd recess 14 ... 1st permanent magnet 16 ... 2nd Permanent magnet 17: guide rods 41a, 41b: conductor 46: ultrasonic sensor 47: amplifier 49: level determiner

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-122123 (JP, A) JP-A-5-99975 (JP, A) JP-A-5-223655 (JP, A) JP-A-5-123655 306959 (JP, A) JP-A-7-43223 (JP, A) JP-A-7-120519 (JP, A) JP-A-7-120520 (JP, A) (58) Fields investigated (Int. Cl. ^7, DB name) G01R 31/00 G01K 7/36 G01R 31/08

Claims (1)

(57) [Claims] 1. A bolt made of a non-magnetic material, and a shaft portion of the bolt is hollowed out to reach a part of a head portion thereof.
A temperature-sensitive magnetic body in which a second recess is formed in the axial direction and changes from a ferromagnetic state to a paramagnetic state according to a temperature change;
A first permanent magnet fitted and adhered to the first recess of the temperature-sensitive magnetic body, and a second permanent recess fitted in the second recess of the temperature-sensitive magnetic body in the axial direction, and cut out of the second recess; In a temperature sensor comprising a second permanent magnet which moves in the axial direction between the holes and moves to the head side of the bolt, and a magnetic pole opposed to the first permanent magnet has the same magnetic pole. A temperature sensor, wherein the second permanent magnet is formed using a manganese aluminum carbon magnet extruded and polished.