JP3079964B2 - Temperature detector - 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 detecting device for detecting an abnormal temperature of an object to be measured.

[0002]

2. Description of the Related Art Conventionally, it has been considered to use an optical fiber as an effective means for detecting the temperature of an object to be measured, particularly in a noisy environment or in a place where there is a risk of explosion. As described in JP-A-355333, a device for automatically detecting a rise in the temperature of an object to be measured has been proposed. This device is a thermochromic element attached to a monitored part from a light source via an optical fiber to an optical fiber. In addition to irradiating the light, the temperature of the monitored part is monitored by receiving the reflected light from the thermochromic element through the optical fiber by the color identification element.

However, in such a configuration, when there are a plurality of points to be monitored or measured, an optical fiber, a light source,
A plurality of color identification elements must be provided, which complicates the overall configuration.

As described in Japanese Patent Application Laid-Open No. 3-92737, a temperature indicator such as a thermal paint is used as a temperature sensor for a portion to be measured. Irradiate and guide the reflected light whose color changes based on the temperature change of the temperature indicating material to the color identification light receiving element via the optical fiber for light reception, and process the identification signal of the color identification light receiving element as color data. An alarm according to an alarm signal is generated by an alarm generation unit,
A sensor having a structure in which a temperature indicating material adhered to a measurement unit is covered with a sensor unit cover housing or a temperature indicating material is adhered to a bottom surface in a sensor head housing has also been proposed.

[0005]

However, in the case of the apparatus described in this publication, a chemical substance that changes its color due to a temperature change, such as thermal paint, is used as the temperature indicating material. When a chemical substance that changes color between colors is used, temperature changes cannot be detected when the light source is red, so there are certain restrictions on the combination of the color of the temperature indicator and the color of the light source, and the light source can be freely selected. Since the temperature sensor cannot be used and there is only one temperature sensor made of a temperature indicating material, it is possible to detect whether the temperature of the object has reached the discoloration temperature of the temperature indicating material. Cannot be detected, and it is impossible to know a minute temperature change of the measured object.

The problem to be solved by the present invention is that an abnormal temperature of an object to be measured can be easily detected with a simple configuration, a light source can be freely selected without restriction, and a minute change in temperature of the object to be measured can be suppressed. Is also to be detectable.

[0007]

According to the first aspect of the present invention,
The light from the light source is guided through an optical fiber to a plurality of temperature sensors installed near the object to be measured. Is filled with a surfactant that changes color to a density that easily changes, and the reflected light from each of the temperature sensors is received by a light receiving element via the optical fiber and the optical branching coupler, and the color of the surfactant is changed. And detecting a temperature rise of the object to be measured by detecting a change in the intensity of the reflected light associated with the measurement.

According to a second aspect of the present invention, there is provided a light source, a light receiving element, a plurality of temperature sensors, and light from the light source connected to the light source, the light receiving element and each of the temperature sensors by an optical fiber. An optical branching coupler that guides the light to each of the temperature sensors and guides the reflected light from each of the temperature sensors to the light receiving element, and an identification circuit that detects a change in the intensity of the reflected light; However, a container having an open end, a waterproof cap which is inserted into the inside of the container from the opening of the container and into which the tip of the optical fiber on the temperature sensor side is introduced through a through hole in the center, and the inside of the container. The space between the waterproof cap and the temperature-sensitive part that is filled with a surfactant and changes its color to a density where light absorption / scattering is easy to change for light of a specific wavelength due to temperature rise To It is a symptom.

Therefore, according to the first and second aspects of the present invention, the reflected light in the container returns to the optical fiber with the change in the coloration of the surfactant in the temperature-sensitive part due to the temperature rise of the object to be measured. Since the temperature rise is detected by this change, the abnormal temperature of the measured object can be easily detected with a simple configuration without complicating the configuration. Because the activator becomes cloudy due to temperature changes,
The temperature change can be detected regardless of the color of the light source, and the selection of the light source can be freely performed without restriction.

At this time, by constructing each temperature sensor as described in claim 2, expensive detection means, a plurality of light sources, color discriminating elements and the like as in the prior art are not required, and the measured object can be measured with a simple configuration. It becomes possible to detect an abnormal temperature of an object.

As described in the third aspect, the material and concentration of the surfactant forming the temperature-sensitive portion of each temperature sensor may be the same. In this case, for example, the same number of objects to be measured as the temperature sensors are used. Temperature rise can be detected.

Further, the concentration of the surfactant forming the temperature-sensitive portion of each temperature sensor may be different, and in this case, the discoloration state of the temperature-sensitive portion of each temperature sensor may be different. By examining the relationship between the reflected light intensity and the light intensity of the reflected light in advance, it is possible to determine from the reflected light intensity which temperature sensor of the temperature sensor has changed color. It is possible to detect at what stage, and it is possible to know a minute temperature change of the object to be measured.

At this time, as described in claim 5, the surfactant forming each temperature-sensitive part is desirably one represented by Chemical Formula 1.

Further, according to a sixth aspect of the present invention, when a light reflector for reflecting light from an optical fiber for guiding each temperature sensor to the optical fiber is provided in each container, the light by the light reflector is provided. The intensity of the light reflected on the fiber decreases due to the light scattering accompanying the discoloration of the temperature-sensitive part. By detecting this decrease, the abnormal temperature of the measured object can be detected.

By providing an air layer in each temperature sensing portion, the volume expansion of the temperature sensing portion due to a rise in temperature can be reduced, and the space between the waterproof cap and the inside of the container can be reduced. As in the case where the thermochromic material is completely filled, it is possible to prevent the thermosensitive part from being damaged due to expansion.

Further, when the tip of the optical fiber introduced into each temperature sensing part is cut obliquely, reflection at the end face of the optical fiber can be suppressed.

Further, according to a ninth aspect of the present invention, in each of the optical fibers, an optical fiber for connecting a light source to any one of the temperature sensors or an optical fiber for connecting a light receiving element to any one of the temperature sensors is one. Even if the end of the remaining optical fiber is welded to the one optical fiber in the optical branching coupler, or as in claim 10,
The optical coupler may be of an optical waveguide type or a beam splitter type.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a schematic view of a first embodiment of the present invention, FIG. 2 is a partial sectional view, and FIG.

The schematic configuration of the entire apparatus will be described.
As shown in FIG. 1, a light source 1 composed of an LED or other monochromatic light source or a white light source and a light receiving element 2 composed of a phototransistor, a photodiode and the like are connected to an optical branching coupler (hereinafter referred to as an optical coupler) 4 by an optical fiber 3. Connected
For example, four first, second, third, fourth
The temperature sensors 6a, 6b, 6c, 6d are connected by optical fibers 7, respectively.

Here, of the optical fibers 3 and 7, the light source 1
And one of the temperature sensors 6a, 6b, 6c, and 6d, or one optical fiber that connects the light receiving element 2 to any of the temperature sensors 6a, 6b, 6c, and 6d. In 4, the end of the remaining optical fiber is welded to this one optical fiber.

When the optical coupler 4 is of an optical waveguide type or a beam splitter type, the above-described optical fibers 3 and 7 are connected via the optical coupler 4. Of course, the optical coupler 4 may be used.

The light from the light source 1 is incident on the incident end of the optical fiber 3 and enters into the optical coupler 4, each of the temperature sensors 6a, 6
b, 6c, and 6d are guided to the respective temperature sensors 6a, 6b, 6c, and 6d via the optical fiber 7, and the reflected light on the bottom surface 14 in the container 9 described later is converted into the respective optical fibers 7, the optical coupler 4, and the light. A change in the intensity of the reflected light received by the light receiving element 2 via the fiber 3 and received by the identification circuit 8 is detected,
The temperature rise of the device under test is detected.

At this time, each of the temperature sensors 6a, 6b, 6
Due to the light scattering accompanying the color change of the below-described temperature sensing portion 12 in c and 6d, the return light to the optical fiber 7 increases, so that the reflected light intensity increases due to the temperature rise as compared to before the temperature rise.

Incidentally, each of the temperature sensors 6a, 6b, 6
As shown in FIG. 2, each of c and 6d has a container 9 having a concavely curved bottom surface 14 and an open end, and a through hole 10 in the center.
And a waterproof cap 11 made of rubber or the like inserted into the inside of the container 9 through an opening thereof, and a waterproof cap 1 inside the container 9
A temperature-sensitive portion 12 which is filled with a surfactant represented by Chemical Formula 1 in a space between the temperature-sensitive portion 12 and a color change to a density at which light absorption / scattering is easily changed with respect to light of a specific wavelength due to a temperature rise; It consists of.

As the surfactant to be used here, in addition to those represented by Chemical formula 1, for example, JP-A-1-113
Nonionic surfactants described in JP-A-627, ionic surfactants described in JP-A-54-123589, and the like may be used.

The tip of the optical fiber 7 inserted into the container 9 from the opening side of the container 9 is introduced in a liquid-tight state to the temperature sensing part 12 through the through hole 10 of the waterproof cap 11. The first to fourth temperature sensors 6a, 6b, 6c,
6d is disposed near the object to be measured if it is a solid,
If it is a fluid, it is placed in it, and when the temperature of the object to be measured rises abnormally, the color depth of the surfactant of each of the temperature sensors 6a, 6b, 6c, 6d changes, and light is received before and after the color change. Since the degree of light scattering of a specific wavelength received by the element 2 changes, the intensity of the reflected light returning to the optical fiber 7 changes as described above, and the temperature of the device under test rises based on the change in the intensity of the reflected light. Is detected.

The temperature sensors 6a, 6b, 6c, 6d
The tip of the optical fiber 7 introduced into the temperature sensing part 12 is cut obliquely, so that the reflection at the end face of the optical fiber 7 can be suppressed.

By the way, a light source 1 is a light having a wavelength of 700 nm, and a hot air of about 90 ° C. is applied to a temperature sensing portion 12 formed by filling a 5% concentration aqueous solution of a surfactant represented by the following formula (1). When the intensity of the received light was measured by a power meter instead of the element 2, the intensity of the returned light to the optical fiber 7 increased due to the rise in temperature, and the change in the intensity of the light before and after the hot air was applied was about 4 dB. Here, after the natural cooling, the light receiving intensity of the power meter returns to the original level, and the temperature sensing portion 12 made of a surfactant is used.
Was confirmed to have reversibility.

The relationship between the concentration of the surfactant represented by Chemical Formula 1 (= 100.x / (x + y); x is a surfactant, y is water) and the amount of change in color (attenuation) is shown below. As a result of the examination, the results are as shown in FIG. 3, and it was found that the higher the concentration of the surfactant, the larger the amount of change.

Further, it is assumed that the branch connection state of the optical fibers 3 and 7 in the optical coupler 4 is, for example, as shown in FIG. 4 (however, solid arrows in the figure indicate transmitted light, and broken arrows indicate reflected light). Shown), each of the temperature sensors 6a, 6b, 6c,
When the concentration of the surfactant in the temperature-sensitive portion 12 of 6d is changed, the temperature sensors 6a, 6b, and 6c are obtained from the results of FIG.
Since the change amount (attenuation amount) of each coloration is different, the correspondence between the change amount (dB) of the light intensity received by the light receiving element 2 and the temperature sensor that detected the temperature is as shown in Table 1, for example. Assuming that the change in the light intensity received by the element 2 is 1.2 (dB), it is understood that the temperature has been detected only by the first temperature sensor 6a, and the change in the light intensity received by the light receiving element 2 is 3 (dB). .4 (dB), it is understood that the temperature has been detected by the first, second, and third temperature sensors 6a, 6b, 6c, and similarly, the amount of change in the intensity of the light received by the light receiving element 2 is 2. If it is 5 (dB), it can be understood that the temperature has been detected by the second and third temperature sensors 6b and 6c. However, at this time, the branch ratio of one branch portion in the optical coupler 4 is 1: 0.8, and the loss is 0.7 dB.

[0031]

[Table 1]

Therefore, the amount of reflected light returning to the optical fiber 7 in the container 9 changes with the change in the color of the surfactant in each temperature sensing part 12 due to the rise in the temperature of the object to be measured. Since the abnormal temperature of the object can be easily detected, and the surfactant of the temperature sensing part 12 becomes cloudy due to the temperature change,
Temperature change can be detected irrespective of the color of the light source, the selection of the light source can be freely performed without restriction, and expensive conventional detecting means, a plurality of light sources, a color identification element, and the like are not required. An abnormal temperature of an object to be measured can be detected by the configuration.

Each of the temperature sensors 6a, 6b, 6c, 6
If the concentration of the surfactant forming the temperature-sensitive portion 12 of d is changed, in this case, the relationship between the discoloration state of the temperature-sensitive portion of each temperature sensor and the light intensity of the reflected light is checked in advance. Since it is known from the reflected light intensity which temperature sensor 12 of the temperature sensor has changed color, it is possible to detect the stage of the temperature of the device under test by specifying the temperature sensor that has changed color, and to determine the fineness of the device under test. It becomes possible to know a great temperature change.

Further, since the container 9 has a shape having the concave curved bottom surface 14, the reflected light can be condensed on the distal end surface of the optical fiber 7.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
It is a sectional view of a part of embodiment.

FIG. 5 shows a first embodiment of the present invention.
The same reference sign indicates the same or corresponding one,
The difference from FIG. 1 is that the glass, plastic,
The light reflector 15 is provided at a position facing the distal end surface of the optical fiber 7 inside the container 9 made of metal such as copper or aluminum.

At this time, the temperature sensors 6a, 6b, 6
The light that has been effectively reflected by the light reflector 15 to the optical fiber 7 before the color change of the temperature-sensitive portion 12 of c and 6d is scattered due to the color change of the temperature-sensitive portion 12 due to the temperature rise.
Since the return light to the light source decreases before the color change, the reflected light intensity decreases due to the temperature rise as compared to before the temperature rise.

Therefore, according to the second embodiment, an effect equivalent to that of the first embodiment shown in FIG. 1 can be obtained.

As another embodiment, the optical fiber branched from the optical coupler 4 is returned to the light receiving element 2 side.
The light passing through this optical fiber may be taken as reference light by another identification circuit, the light intensity may be monitored, and the reflected light intensity may be corrected by comparing the intensity of the reference light with the reflected light. Thus, stable temperature detection can be performed even when the light emission intensity of the light source 1 varies.

The number of temperature sensors to be provided is not limited to four as described above, but may be two, three, or five or more. What is necessary is just to fill an agent.

Further, each of the temperature sensors 6a, 6b, 6c,
An air layer may be provided in the temperature-sensitive section 12 of 6d, and the air layer can reduce the volume expansion of the temperature-sensitive section due to a temperature rise. As in the case where the surfactant is completely filled, it is possible to prevent the temperature-sensitive portion 12 from being damaged due to expansion.

The container 9 may be made of metal such as copper or aluminum, glass, plastic, or the like. Any material that does not chemically react and satisfies the condition that it can be used within the detection temperature range may be used.For example, when glass is used, the thermal conductivity is lower than that of metal, so that a gradual response to a temperature rise is achieved. Suitable when needed.

Further, if the container 9 is transparent, the temperature sensing part 1
The color change of the surfactant 2 can be visually observed from the outside. On the other hand, if the container 9 is opaque, disturbance light from the outside can be blocked, so that the detection accuracy can be improved.

[0044]

As described above, according to the first and second aspects of the present invention, the color change (white turbidity) of the surfactant in the temperature-sensitive part due to a rise in the temperature of the measurement object causes The return of the reflected light to the optical fiber changes, and this change detects the temperature rise, so that the abnormal temperature of the object to be measured can be detected with a simple configuration without causing the configuration to be complicated as in the related art. In addition, the temperature change can be detected regardless of the color of the light source, the selection of the light source can be freely performed without restriction, and the abnormal temperature of the measured object can be detected easily and accurately.

By using the same material and concentration of the surfactant forming the temperature sensing part of each temperature sensor, the temperature rise of the same number of objects to be measured as the temperature sensors can be detected. can do.

Further, by changing the concentration of the surfactant forming the temperature-sensitive portion of each temperature sensor, the discoloration state of the temperature-sensitive portion of each temperature sensor and the reflected light can be reduced. By examining the relationship with the light intensity in advance, it is possible to know from the reflected light intensity which temperature sensor of the temperature sensor has changed color, and to identify the temperature sensor at which the color change has occurred, and to what stage the temperature of the object to be measured is. It is possible to detect, and it is possible to know a minute temperature change of the measured object.

Further, as described in claim 6, a light reflector for reflecting light from an optical fiber for guiding each temperature sensor to the optical fiber is provided in each container, so that the light reflector can be used. The intensity of the light reflected on the optical fiber decreases due to the light scattering accompanying the discoloration of the temperature-sensitive portion. By detecting this decrease, the abnormal temperature of the measured object can be detected.

By providing an air layer in each temperature sensing portion, the volume expansion of the temperature sensing portion due to temperature rise can be reduced, and the space between the temperature sensing portion and the waterproof cap inside the container can be reduced. As in the case where the thermosensitive color changing material is completely filled, it is possible to prevent the thermosensitive part from being damaged due to expansion.

Further, as described in claim 8, by cutting the tip of the optical fiber introduced into each temperature sensing portion obliquely, reflection at the end face of the optical fiber can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the first embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 5 is a partial sectional view of a second embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 light source 2 light receiving element 3, 7 optical fiber 4 optical coupler (optical branching coupler) 6a, 6b, 6c, 6d first, second, third, fourth temperature sensor 8 identification circuit 9 container 10 through hole 11 waterproof cap 12 Temperature sensing part 15 Light reflector

Continued on the front page (51) Int.Cl. ⁷ Identification code FI G02B 6/00 G02B 6/00 B 6/02 6/02 A 6/10 6/10 D

Claims (10)

(57) [Claims] 1. A light from a light source is guided through an optical fiber to a plurality of temperature sensors installed near an object to be measured. On the other hand, filled with a surfactant that discolors to a density where light absorption / scattering is likely to change, and receives reflected light from each of the temperature sensors by a light receiving element via the optical fiber and an optical branching coupler. A temperature detecting device, wherein the temperature change of the object to be measured is detected by detecting a change in the intensity of the reflected light accompanying the color change of the surfactant. 2. A light source, a light receiving element, a plurality of temperature sensors, and each of the light source, the light receiving element, and each of the temperature sensors are connected by an optical fiber to guide light from the light source to each of the temperature sensors. An optical branching coupler that guides the reflected light from each of the temperature sensors to the light receiving element, and an identification circuit that detects a change in the intensity of the reflected light, wherein each of the temperature sensors has a container having an open end. A space between the waterproof cap in which the tip of the optical fiber on the temperature sensor side is introduced through a through hole in the center and inserted into the container through the opening of the container, and the waterproof cap inside the container. And a temperature-sensitive part which changes its color to a density in which light absorption and scattering easily change with respect to light of a specific wavelength due to a rise in temperature. 3. The temperature detecting device according to claim 1, wherein the material and the concentration of the surfactant forming each of the temperature sensing portions are the same. 4. The method according to claim 1, wherein the concentrations of the surfactants forming the respective temperature-sensitive portions are different from each other.
The temperature detection device as described in the above. 5. The surfactant forming each of the temperature-sensitive parts,
4. The method according to claim 1, wherein
Or the temperature detection device according to 4. Embedded image 6. A light reflector for reflecting light from the optical fiber for guiding each of the temperature sensors to the optical fiber is provided in each of the containers. , 3, 4 or 5. 7. The temperature detecting device according to claim 2, wherein an air layer is provided in each of the temperature sensing sections. 8. The temperature detecting device according to claim 2, wherein a tip of said optical fiber introduced into each of said temperature sensing portions is cut obliquely. 9. An optical fiber for connecting the light source and any one of the temperature sensors, or an optical fiber for connecting the light receiving element and any of the temperature sensors, among the optical fibers. 4. An optical fiber according to claim 1, wherein said one optical fiber is welded to an end of the remaining optical fiber in said optical branching coupler.
9. The temperature detecting device according to 6, 7, or 8. 10. The temperature detecting device according to claim 2, wherein said optical branching coupler is of an optical waveguide type or a beam splitter type.