JPH07198500A - Surface temperature measuring method - Google Patents

Abstract

PURPOSE:To provide a surface temperature measuring method which removes the cause of an error in a surface temperature and in which the accuracy to be pursued of a surface-temperature calibration system as a standard instrument can be displayed to the full. CONSTITUTION:A surface temperature calibration instrument which is composed of a block body 1 for calibration, of a heating source 3 and of a heat-insulating member 4 which houses them is prepared. An inside temperature is measured by a first temperature sensor 6 which measures the inside temperature of the block body 1 and which has been calibrated on the basis of a criterion temperature sensor 5. In addition, a temperature near the surface is measured from the outside lay a second temperature sensor 2 whose thermoelectric characteristic is equal to that of the first temperature sensor 6. On the basis of measured values by the first temperature sensor 6 and the second temperature sensor 2, the surface temperature of the block body 1 is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface temperature measuring method using a surface temperature calibrator (surface temperature standard), which is almost affected by disturbances such as the ambient temperature of a calibration block and the contact state of a temperature sensor. However, the present invention relates to a surface temperature measuring method for determining an extremely accurate surface temperature.

[0002]

2. Description of the Related Art In a conventional surface temperature measuring method using a surface temperature calibrator, when measuring the surface temperature of a calibration block body, a contact surface temperature sensor is mounted on a circular surface of a cylindrical calibration block. It was a method of measuring the temperature distribution on the surface by contacting several pieces at regular intervals on the center line of the circle. However, according to this measuring method, several surface temperature sensors are required and the thermocouple characteristics of each sensor must be uniform. Further, a surface temperature error occurs due to problems such as surface roughness, contact error, thermal conductivity, and heat capacity that occur between the contact piece joined to the temperature-sensitive part of the sensor and the calibration block body.

For example, when the temperature of a copper block surface of a surface temperature calibration system using a thermoelectric contact type temperature sensor is measured, the temperature sensor itself exerts a thermal influence on the copper block, and as a result, the temperature of the block body is increased. This causes a change in the true surface temperature, making accurate surface temperature measurement difficult. Referring to the drawings, when the room temperature (ambient temperature) is different as shown in FIG. 2, the true surface temperature is compared with the measured value by the temperature sensor 11,
It has been found that the error depends on the difference between the ambient temperature and the temperature of the block body 12. As shown in the figure, when the surface temperature of the block body 12 set to the same temperature (for example, 100 ° C) is measured for different ambient temperatures, when the ambient temperature is 25 ° C (a) In addition, since the temperature difference between the block body 12 is large and the heat flow, that is, the movement of heat is actively performed between the block body 12 and the temperature sensor 11, it causes a heat dissipation phenomenon and is measured from a theoretical surface temperature. The value decreases and a large temperature error occurs.

On the other hand, in the case of (b) in which the ambient temperature is 50 ° C., the influence of the heat flow is less than that in (a), but there is no change in that a temperature error occurs due to the same cause. On the other hand, when the ambient temperature is 95 ° C. (c), the ambient temperature and the temperature of the block body 12 are almost equal to each other, and a heat flow hardly occurs, so that the temperature error is relatively small. That is, the closer the two temperatures are to the thermal equilibrium state, the smaller the measurement error of the surface temperature.

Further, the shape and contact state of the temperature sensor 11 may cause a surface temperature error. For example, when the contact area of the thermoelectric contact type temperature sensor 11 is different as shown in FIG. 3, when the contact area is large as shown in (a), the contact area is medium as shown in (b). Than
A large amount of heat is radiated from the copper block body 12 (hereinafter referred to as the temperature-measured body) to the temperature sensor 11, (c)
As shown in, the smaller the contact area, the smaller the amount of heat radiated. Therefore, the larger the contact area of the temperature sensor 11 is, the more heat of the temperature-measurable body 12 is taken away, and the error from the true surface temperature becomes larger.

Further, as shown in FIGS. 4A to 4C, when the thickness of the contact piece 13 interposed between the temperature sensing part of the temperature sensor and the temperature-measuring body 12 is changed, As the thickness becomes thicker, the distance from the surface temperature measuring point to the temperature sensing portion (for example, thermocouple) becomes longer, the heat is dispersed in the contact piece 13, and the amount of heat transferred to the temperature sensing portion actually decreases. In addition, the fact that the thickness is thick means that the volume of the contact piece 13 is increased, which means that the heat capacity of the contact piece 13 is increased. As a result, a condition for easily radiating heat to the temperature sensor is created, and the temperature of the temperature-measurable body 12 is liable to be thermally influenced, which makes it difficult to measure the true surface temperature.
In addition, a contact error with the temperature-measurable body 12 may cause a surface temperature measurement error.

Further, as another error factor, as shown in FIG. 5, theoretically, it is optimal that the temperature is measured in a posture in which it is in close contact with the temperature-measuring body 12 as shown in FIG. As shown in (b), due to problems such as contact attitude and surface roughness, the contact piece 13
It is difficult to completely align the surface of the temperature-measured body 12 with the surface 12, and an air layer 14 is formed between the surface temperature measurement point and the contact piece 13, resulting in a decrease in thermal conductivity. Temperature measurement object
The heat from 12 is not accurately transmitted to the temperature sensing part of the temperature sensor,
There is a problem that a surface temperature measurement error occurs.

[0008]

As described above, the conventional surface temperature measuring method has various problems, and in reality, the influence of disturbance cannot be completely eliminated and the true surface temperature can be determined. Therefore, there is a problem in that the accuracy of the surface temperature calibrator as a reference device cannot be maximized.

In view of the above problems, the present invention eliminates the aforementioned surface temperature error factor in the surface temperature measuring method of the surface temperature calibration system using a thermoelectric temperature sensor,
It is an object of the present invention to provide a surface temperature measuring method capable of maximizing the accuracy to be pursued as a standard device.

[0010]

The surface temperature measuring method of the present invention for achieving the above object comprises a calibration block body,
A reference temperature sensor for measuring the internal temperature of the block body by preparing a surface temperature calibrator composed of a heat source attached to the block body and a heat insulating member accommodating these and having one surface of the block body as an opening The internal temperature of the block body is measured by the first temperature sensor calibrated based on the above, and the second temperature sensor having thermoelectric characteristics equivalent to the first temperature sensor is used to measure the surface from the outside of the block body. Measure the temperature in the vicinity and
It is a method of determining the surface temperature of the block body based on the measured values of the temperature sensor of No. 2 and the second temperature sensor.

That is, according to the surface temperature measuring method of the present invention, the internal temperature Ta of the calibration block body and the surface (strictly, near the surface) temperature Tb of the calibration block body are measured by a thermoelectric temperature sensor and used for calibration. True surface temperature Tc of block
Is always located between Ta and Tb. That is, the true surface temperature is determined based on the theoretical formula Ta ≦ Tc ≦ Tb ....

The greatest difference between the surface temperature measuring method of the present invention and the conventional method is not only dependent on the thermoelectric temperature sensor for measuring the surface temperature, but rather more accurate by measuring the internal temperature of the block body. It is possible to measure the surface temperature. Originally, the temperature of the block body should theoretically be in a uniform temperature state after a lapse of a certain time after the start of heating. However, actual measurement has revealed that the surface temperature of the block is lower than the internal temperature.

Therefore, in the present invention, the surface temperature in the original sense of comprehensively capturing the block body, that is, the true surface temperature measurement is made possible by also considering the internal temperature of the block body. Is the biggest feature.

[0014]

[Operation] In the surface temperature measuring method of the present invention, in addition to the temperature sensor for measuring the surface temperature of the block body, the temperature sensor for measuring the internal temperature of the block body is also used.
The former can determine the minimum value of the range where the true surface temperature exists, and the latter can determine the maximum value of the range where the true surface temperature exists.

Further, the thermoelectric characteristics of both the temperature sensors are equal, and since one of them is calibrated by the reference temperature sensor, the accuracy of the measured value is high, and the contact area of the temperature sensor and the thickness of the contact portion are high. Even if there are error factors such as difference in contact and contact error, the true surface temperature can be measured by the temperature gradient from the measured internal temperature to the surface of the block and the temperature near the surface of the block by the thermoelectric temperature sensor. Since it can be performed, it always enables reliable and reliable surface temperature measurement.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to the drawings. In the embodiment shown in FIG. 1, it is a view conceptually showing a main part of an apparatus used for measuring a surface temperature of a metal under a certain condition. This apparatus includes a calibration block body 1 which is an object of surface temperature measurement, and a second temperature sensor (thermoelectric type) for measuring the temperature near the surface of the block body 1 (in the strict sense, not near the surface). Temperature sensor)
2, a heating source 3 for the block body 1, a heat insulating member 4 provided for equalizing the temperature of the block body 1, a reference located near the center of the block body 1 and defined from the surface The first temperature sensor (thermoelectric temperature sensor) located at the same height as the temperature sensor (resistance temperature detector) 5 and the reference temperature sensor 5 and in the same lot as the second temperature sensor 2, that is, having the same thermocouple characteristics. ) 6.

The resistance temperature detector which is the reference temperature sensor 5 is
This is a temperature sensor with traceability and guaranteed extremely high accuracy. Based on this reference temperature sensor 5, the first temperature sensor 6 provided at the same position is calibrated to obtain a temperature difference ΔT from the reference temperature sensor 5. By confirming, the first temperature sensor 6 is guaranteed as a highly reliable temperature sensor. That is, the traceability of the reference temperature sensor 5 is given to the first temperature sensor 6.

Further, the first temperature sensor 6 and the second temperature sensor 2 provided near the surface of the calibration block body 1
And the temperature difference ΔT ₁ with If the temperature measured value by the second temperature sensor 2 provided near the surface is T ₂ , the temperature measured value by the reference temperature sensor 5 is T ₃ , and the true surface temperature that is about to be measured is Ts, The following theoretical formula holds between the temperatures of.

T ₂ ≤Ts ≤T ₃ ... Then, the temperature T _{4 of} the first temperature sensor 6 having an error of ΔT with respect to the reference temperature sensor 5 is determined. On the other hand, the following formula is established. T ₄ = T ₃ + ΔT Further, the temperature near the surface can be determined by the temperature difference ΔT ₁ between the first temperature sensor 6 and the second temperature sensor 2 located near the surface temperature. As a result, highly reliable and highly accurate temperature measurement can be performed for each temperature sensor.

Further, the first temperature sensor 6 provided at the same position as the reference temperature sensor 5 whose position from the surface is regulated is brought as close as possible to the vicinity of the surface (the distance d is made as small as possible) to obtain ΔT. The error of ₁ is also extremely small, and the range in which the true surface temperature Ts exists is infinitely small. Moreover, it is possible to measure the surface temperature in the true sense without any thermal influence on the surface of the calibration block body 1.

In the surface temperature measuring method according to this embodiment, 1
Two thermoelectric temperature sensors of the same lot can be organized into highly reliable and highly accurate ones based on the reference temperature sensors 5 that can be guaranteed with extremely high accuracy, and near the surface of the calibration block body 1. With the surface temperature sensor provided in and the internal temperature sensor provided inside, the range in which the true surface temperature exists can be made extremely small, so that highly accurate surface temperature measurement can be performed.

[0022]

The surface temperature measuring method according to the present invention comprises a calibration block body, a heating source attached to the block body,
A first temperature sensor that accommodates these and prepares a surface temperature calibrator including a heat insulating member having an opening on one surface of the block body, and calibrates it based on a reference temperature sensor that measures the internal temperature of the block body. The internal temperature of the block body is measured by the second temperature sensor having the same thermoelectric characteristic as the first temperature sensor, and the temperature near the surface is measured from the outside of the block body by the first temperature sensor. Since the surface temperature of this block body is determined based on the measured values of the temperature sensor of 1 and the second temperature sensor, the following effects can be obtained.

In addition to the temperature sensor for measuring the surface temperature of the block body, the temperature sensor for measuring the internal temperature of the block body is also used. Therefore, the former determines the minimum value of the range where the true surface temperature exists, The latter makes it possible to determine the maximum value of the range in which the true surface temperature exists.
Further, the thermoelectric characteristics of both the temperature sensors are equal, and since one of them is calibrated by a reference temperature sensor, the accuracy of the measured value is high, and the contact area of the temperature sensor, the contact pressure, the thickness of the contact portion Even if an error factor such as a contact error occurs, the true surface temperature can be measured by the temperature gradient from the measured internal temperature to the surface of the block and the temperature near the surface of the block by the thermoelectric temperature sensor. This enables reliable and reliable surface temperature measurement at all times.

Therefore, it is possible to maximize the accuracy of the surface temperature calibrator as a standard without being affected by the surface temperature error factor.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a surface temperature calibrator used in a surface temperature measuring method according to an embodiment of the present invention.

FIG. 2 is a sectional view for illustrating an error factor (ambient temperature) by a conventional surface temperature measuring method.

FIG. 3 is a cross-sectional view for illustrating an error factor (contact area) by a conventional surface temperature measuring method.

FIG. 4 is a cross-sectional view for illustrating an error factor (contact portion thickness) in a conventional surface temperature measuring method.

FIG. 5 is a cross-sectional view for illustrating an error factor (contact error between a contact portion and a calibration block) due to a conventional surface temperature measuring method.

[Explanation of symbols]

1 block body 2 second temperature sensor 3 heating source 4 heat insulating member 5 reference temperature sensor 6 first temperature sensor

Claims (1)

[Claims] 1. A surface temperature calibrator comprising a calibration block body, a heating source provided in parallel with the block body, and a heat insulating member for accommodating the heat source and having one surface of the block body as an opening, A first temperature sensor calibrated on the basis of a reference temperature sensor that measures the internal temperature of the block body measures the internal temperature of the block body, and a second temperature sensor having thermoelectric characteristics equivalent to that of the first temperature sensor. A surface temperature measuring method of measuring the temperature of the vicinity of the surface from the outside of the block body by a temperature sensor and determining the surface temperature of the block body based on the measured values of the first temperature sensor and the second temperature sensor. .