JP2943460B2 - 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, for example, abnormal overheating of a current-carrying conductor of a power device or the like.

[0002]

2. Description of the Related Art Since 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, there are a thermocouple, a thermometer, and a thermistor for measuring 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.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a temperature sensor which can be constantly monitored, has excellent durability, has little change with time, and can directly detect a temperature change of a conductor. And

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a cylindrical thermosensitive magnetic body which changes from a ferromagnetic state to a paramagnetic state in response to a temperature change. The magnets are adhered so that they become magnetic poles that attract each other, magnetic powder is placed inside a cylindrical temperature-sensitive magnetic body and a permanent magnet, and both ends of the permanent magnet are closed with optically transparent members. At a temperature lower than the operating temperature of the body, the light passes through the temperature-sensitive magnetic material and the permanent magnet, and at a temperature higher than the operating temperature, the light is cut off by the magnetic powder.

[0007]

The temperature-sensitive magnetic material is in a ferromagnetic state below the operating temperature. Therefore, the magnetic powder is adsorbed on the inner wall surfaces of the permanent magnet and the temperature-sensitive magnetic material. This allows the light beam to pass through the cylindrical shape of the permanent magnet and the temperature-sensitive magnetic material. However, when the temperature-sensitive magnetic material becomes higher than the operating temperature, it enters a paramagnetic state, so that the magnetic powder is attracted to the permanent magnets at both ends and cuts off light rays from the transparent member.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B, reference numeral 10 denotes a temperature sensor, and the temperature sensor 10 is configured as follows. Reference numeral 11 denotes, for example, a cylindrical temperature-sensitive magnetic material.
It is an n-Zn soft ferrite and has temperature characteristics as described below. First and second cylindrical permanent magnets 12 and 13 are attached to both ends of the temperature-sensitive magnetic body 11 by arranging them at magnetic poles as shown in FIG. Thereafter, the temperature-sensitive magnetic body 11 and the first and second permanent magnets 1
The magnetic powder 14 is put in the insides 2 and 13. After the magnetic powder 14 has been charged, both ends of the permanent magnets 12 and 13 are closed with optically transparent members (for example, transparent glass) 15 and 16.

The temperature-sensitive magnetic material 11 has a temperature characteristic of the initial magnetic permeability as shown in FIGS. 3A to 3H. The temperature-sensitive magnetic material 11 shows a ferromagnetic state below the Curie temperature (operating temperature). It has the property of becoming magnetic.
Therefore, the temperature-sensitive magnetic body 11 is in a ferromagnetic state below the operating temperature, and the magnetic paths of the first and second permanent magnets 12 and 13 are as shown by arrows in FIG. 2A. Thereby, the magnetic powder 14 is adsorbed on the inner wall surfaces of the temperature-sensitive magnetic body 11 and the first and second permanent magnets 12 and 13 as shown in FIG. 1A. As a result, the light beam entering from the optically transparent member 16 passes through the temperature sensor 10 and exits from the transparent member 15.

However, when the temperature-sensitive magnetic material 11 becomes higher than the operating temperature, it becomes paramagnetic, so that the magnetic paths of the first and second permanent magnets 12 and 13 are as shown by arrows in FIG. 2B. As a result, the magnetic powder 14 is attracted to the first and second permanent magnets 12 and 13 as shown in FIG. 1B and covers the light passing surfaces of the optically transparent members 15 and 16. As a result,
Light rays cannot pass through the temperature sensor 10. That is, the light beam is cut off. The temperature-sensitive magnetic material 11
Is reduced to the operating temperature or less, the light beam can pass through the temperature sensor 10 again.

FIG. 4 and FIG. 5 show that the temperature sensor 10 is mounted, for example, in a through hole 22 formed in a current-carrying conductor 21 of a power device.
FIG. 4 is a diagram for detecting abnormal overheating of the conductor 21.
Is an example in which optical fibers 23 and 24 are directly attached to the temperature sensor 10. In FIG. 4, reference numeral 25 denotes an amplifier of a photoelectric switch. When the temperature sensor 10 cuts off the light beam from the optical fiber 23, an output is sent from the amplifier 25 to notify that the conductor 21 has abnormally overheated.

FIG. 5 shows an optical fiber 2 connected to the temperature sensor 10.
The light from the optical fiber 23 is radiated to the temperature sensor 10 without directly attaching 3 and 24. When this irradiation light beam passes through the temperature sensor 10 and the optical fiber 24 receives it, it is determined that the conductor 21 is not abnormally heated. However, the optical fiber 24 cannot receive the light beam. That is, when the conductor 21 is overheated, the temperature sensor 10 does not allow the light beam to pass. Then, the amplifier 25 of the photoelectric switch operates to notify that the conductor 21 is abnormally overheated.

When the temperature sensor 10 is mounted on the conductor 21 as described above, the temperature sensor does not receive a malfunction due to electromagnetic field noise, and the effect of the magnetic field acting on the conductor 21 can be eliminated.

[0014]

As described above, according to the present invention,
It has excellent durability, is stable with little change over time, and opens and closes the optical path in response to temperature changes, so it can be operated repeatedly.Moreover, it can directly detect temperature changes in conductors, so it has high sensitivity and accuracy. Therefore, there is an advantage that a stable operation can be obtained. Also, by selecting a temperature-sensitive magnetic material,
It can be sufficiently applied to use in a wide temperature range.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which A is a cross-sectional view showing a state of a magnetic powder before operation of a temperature-sensitive magnetic body, B is a cross-sectional view showing a state of magnetic powder after operation,

FIG. 2A is an explanatory diagram illustrating a state of a magnetic path before operation of a temperature-sensitive magnetic body, FIG. 2B is an explanatory diagram illustrating a state of a magnetic path after operation,

FIG. 3 is a temperature characteristic diagram of initial magnetic permeability of a temperature-sensitive magnetic material,

FIG. 4 is a configuration diagram showing an example in which the temperature sensor of the present invention is attached to a conductor;

FIG. 5 is a configuration diagram showing an example in which the temperature sensor of the present invention is attached to a conductor.

[Explanation of symbols]

Reference numeral 10: temperature sensor, 11: temperature-sensitive magnetic body, 12, 13: first and second permanent magnets, 14: magnetic powder, 15, 16: optically transparent member

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01K 7/36 G01R 31/08

Claims (1)

(57) [Claims] 1. A cylindrical permanent magnet, which changes from a ferromagnetic state to a paramagnetic state in accordance with a temperature change, is bonded to both ends of a cylindrical permanent magnet so as to form magnetic poles for attracting each other. Put the magnetic powder inside the temperature-sensitive magnetic material and the permanent magnet, close both ends of the permanent magnet with optically transparent members, and when the temperature is below the operating temperature of the temperature-sensitive magnetic material, light rays A temperature sensor that passes through the inside and cuts off the light beam with a magnetic powder above the operating temperature.