JP7611042B2 - Temperature sensor abnormality determination device, temperature sensor abnormality determination method, and temperature sensor abnormality determination program - Google Patents

Description

The present invention relates to a temperature sensor anomaly determination device, a temperature sensor anomaly determination method, and a temperature sensor anomaly determination program for determining anomalies in multiple temperature sensors that measure the temperature at approximately the same location on a measurement target.

For example, in a heating furnace as a measurement target, temperature sensors such as thermocouples and resistance thermometers are used to control the heater temperature. In a heating furnace, the temperature inside the furnace is high, and the temperature sensors used to control the heater temperature deteriorate over time, reducing the accuracy of the detection results, making it impossible to accurately grasp the temperature inside the furnace and making it necessary to replace the temperature sensor.

As a method of knowing when to replace a temperature sensor, for example, the techniques disclosed in Patent Documents 1 and 2 below are known. In Patent Document 1, the resistance value is measured from the voltage drop when a current is supplied to the temperature sensor from a current source, and the time to replace the temperature sensor is predicted from the change in the measured resistance value over time, and the time to replace the temperature sensor is notified. In Patent Document 2, the number of excessive temperature events experienced by the temperature sensor, the duration of the excessive temperature events, the temperature between excessive temperature events, etc. are accumulated in the memory of the process variable transmitter or the memory of the temperature sensor, and the temperature sensor is monitored to notify the time to replace the temperature sensor.

Japanese Patent Application Publication No. 10-232170 Special Publication No. 2015-522160

However, as in Patent Document 1, a method that measures resistance values to predict the lifespan of a temperature sensor has the problem of requiring dedicated equipment and parameter management. Also, as in Patent Document 2, a method that counts the number of uses to indicate when the temperature sensor should be replaced has the problem of requiring dedicated parameters to manage the temperature sensor.

Therefore, the present invention has been made in consideration of the above problems, and aims to provide a temperature sensor anomaly judgment device, a temperature sensor anomaly judgment method, and a temperature sensor anomaly judgment program that can predict an abnormality in a pair of temperature sensors using the measurement values of the pair of temperature sensors.

In order to achieve the above object, a temperature sensor anomaly determination device according to a first aspect of the present invention uses two sets of temperature sensors, each of which is an integrated pair of temperature sensors that measure the temperature at approximately the same location in the atmosphere of a heating furnace as a measurement target, and is equipped with a first control loop in which a measurement value and a set value of one of the pair of temperature sensors in one set are input to a first PID controller and a first heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in the other set is input to a second PID controller and a second control loop in which a second heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in the other set, and is a temperature sensor anomaly determination device that determines anomalies in the temperature sensors in a measurement system that controls the heating furnace to a target temperature so that the temperature distribution inside the furnace for each lot of batch processing is approximately uniform,
a data storage device that stores the most recent multiple sample measurements of the pair of temperature sensors for each lot of the batch processing for the two sets of temperature sensors;
a tester for calculating a sum of squares of the sampled measurement difference from the difference between the multiple samples of the pair of temperature sensors stored in the data storage device and an average of the sampled measurement difference, for the two sets of temperature sensors, calculating a variance of the sampled measurement difference based on the calculated sum of squares of the sampled measurement difference and the number of sampled measurement values, calculating a test statistic based on the calculated variance of the sampled measurement difference, the sum of squares of the sampled measurement difference and the number of sampled measurement values, and testing whether the measured values of the pair of temperature sensors are different by comparing the test statistic with a comparison reference value based on the number of sampled measurement values and a significance level;
The present invention is characterized in that it further comprises a sensor warning determiner for determining whether or not the pair of temperature sensors is abnormal based on the inspection result of the inspector for the two sets of temperature sensors .

A temperature sensor anomaly determination method according to claim 2 of the present invention uses two sets of temperature sensors, each of which is an integrated pair of temperature sensors that measure temperatures at approximately the same location in the atmosphere of a heating furnace as a measurement target , and includes a first control loop in which a measurement value and a set value of one of the pair of temperature sensors in one set are input to a first PID controller and a first heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in one set, and a second control loop in which a measurement value and a set value of one of the pair of temperature sensors in the other set are input to a second PID controller and a second heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in the other set, and a temperature sensor anomaly determination method using a temperature sensor anomaly determination device that determines anomalies in the temperature sensors in a measurement system that controls the heating furnace to a target temperature so that the temperature distribution inside the furnace for each lot of batch processing is approximately uniform ,
A step of storing the latest measured values of a plurality of samples of the pair of temperature sensors for each lot of the batch processing by a data storage device provided in the temperature sensor abnormality determination device for the two sets of temperature sensors ;
a step of calculating, by a verification device provided in the temperature sensor anomaly determination device for the two sets of temperature sensors , a sum of squares of the sampled measurement value differences from the difference between the measurement values of the multiple samples of the pair of temperature sensors stored in the data storage device and an average of the sampled measurement value differences, calculating a variance of the sampled measurement value differences based on the calculated sum of squares of the sampled measurement value differences and the number of sampled measurement values, calculating a test statistic based on the calculated variance of the sampled measurement value differences, the sum of squares of the sampled measurement value differences and the number of sampled measurement values, and verifying whether the measurement values of the pair of temperature sensors are different by comparing the test statistic with a comparison reference value based on the number of sampled measurement values and a significance level;
The method further includes a step of determining whether or not the pair of temperature sensors is abnormal based on the inspection result of the inspection device by a sensor warning determination device provided in the temperature sensor abnormality determination device.

A temperature sensor anomaly determination program according to claim 3 of the present invention uses two sets of temperature sensors, each of which is an integrated pair of temperature sensors that measure temperatures at approximately the same location in the atmosphere of a heating furnace as a measurement target , and includes a first control loop in which a measurement value and a set value of one of the pair of temperature sensors in one set are input to a first PID controller and a first heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in one set is input to a second PID controller and a second control loop in which a measurement value and a set value of one of the pair of temperature sensors in the other set is input to a second PID controller and a second heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in the other set, and a temperature sensor anomaly determination program for determining anomalies in the temperature sensors in a measurement system that controls the heating furnace to a target temperature so that the temperature distribution inside the furnace is approximately uniform for each lot of batch processing,
Computer,
a data storage device that stores the most recent multiple sample measurements of the pair of temperature sensors for each lot of the batch processing for the two sets of temperature sensors;
a tester for calculating a sum of squares of the sampled measurement difference from the difference between the multiple samples of the pair of temperature sensors stored in the data storage device and an average of the sampled measurement difference, for the two sets of temperature sensors, calculating a variance of the sampled measurement difference based on the calculated sum of squares of the sampled measurement difference and the number of sampled measurement values, calculating a test statistic based on the calculated variance of the sampled measurement difference, the sum of squares of the sampled measurement difference and the number of sampled measurement values, and testing whether the measured values of the pair of temperature sensors are different by comparing the test statistic with a comparison reference value based on the number of sampled measurement values and a significance level;
The two sets of temperature sensors are caused to function as a sensor warning determiner that determines whether or not the pair of temperature sensors is abnormal based on the inspection result of the inspector.

According to the present invention, it is possible to predict an abnormality in a pair of temperature sensors using the most recent measured values of the pair of temperature sensors, without requiring a dedicated device or parameter management as in the conventional art.

1 is a block diagram of a temperature sensor abnormality determination device according to the present invention; 1 is a diagram showing an example of a measurement system in which a temperature sensor abnormality determination device according to the present invention is adopted;

The following describes in detail the embodiment of the present invention with reference to the attached drawings.

First, the measurement system in which the present invention is adopted will be described with reference to FIG. 2. As shown in FIG. 2, the measurement system 11 consists of a vacuum heat treatment furnace (heating furnace) 12 as the measurement target and two control loops 13.

The inside of the vacuum heat treatment furnace 12 is kept in a vacuum state by a vacuum pump 14, and heaters 15 (15A, 15B) are located at the top and bottom of the furnace.

Further, a pair of temperature sensors A1, A2 and a pair of temperature sensors B1, B2 are arranged near each heater 15 (15A, 15B). In the example of Fig. 2, a pair of temperature sensors A1, A2 are arranged near the heater 15A in the upper part of the furnace. The pair of temperature sensors A1, A2 are configured as two temperature sensors inserted into one tube and integrated. Further, a pair of temperature sensors B1, B2 are arranged near the heater 15B in the lower part of the furnace. The pair of temperature sensors B1, B2 are configured as two temperature sensors inserted into one tube and integrated, similar to the pair of temperature sensors A1, A2.

In this embodiment, the pair of temperature sensors A1, A2 and the pair of temperature sensors B1, B2 are, for example, thermocouples in which the electromotive force increases with fluctuations in the internal resistance value, but the present invention is not limited to this and, for example, resistance temperature detectors or the like can also be used.

The two control loops 13 consist of an upper control loop 13A and a lower control loop 13B.

The upper control loop 13A and the lower control loop 13B are each configured with a PID controller 13a and an SCR (thyristor) 13b to control the temperature inside the vacuum heat treatment furnace 12 to a target temperature so that the temperature distribution inside the furnace for each lot of batch processing is approximately uniform, for example.

In the upper control loop 13A, the measurement value (temperature data) of one of the pair of temperature sensors A1, A2 and the upper furnace temperature set value are input to a PID controller 13a, and the PID controller 13a outputs an operation amount (0 to 100%) corresponding to the difference between the two to an SCR 13b for drive control, and the SCR 13b controls the on/off of a heater 15A.

Similarly, in the lower control loop 13B, the measurement value of one of the pair of temperature sensors B1, B2 and the lower furnace temperature set value are input to a PID controller 13a, and the PID controller 13a outputs an operation amount (0 to 100%) corresponding to the difference between the two to an SCR 13b for drive control, and the SCR 13b controls the on/off of a heater 15B.

The temperature sensor anomaly determination device of this embodiment has the function of determining an anomaly in a pair of temperature sensors A1, A2 ( a pair of temperature sensors B1, B2) by examining the difference in the averages (testing the difference between paired data) of the pair of temperature sensors A1, A2 ( a pair of temperature sensors B1, B2) in the measurement system 11 described above, and alerting the operator.

As shown in FIG. 1, the temperature sensor anomaly determination device 1 is configured with a data accumulator 2, a verification device 3, and a sensor warning determiner 4 to realize the above functions.

The data accumulator 2 is composed of a memory for storing data, and constantly accumulates the most recent 10 sample measurement values (temperature data) from each pair of temperature sensors A1, A2 and each pair of temperature sensors B1, B2 as reference samples, and stores them for each pair of temperature sensors A1, A2 and B1, B2.

The measured values stored in the data accumulator 2 are the measured values for each lot (predetermined time) of the batch processing of the pair of temperature sensors A1 and A2, and the measured values for each lot (predetermined time) of the batch processing of the pair of temperature sensors B1 and B2. The number of reference samples stored in the data accumulator 2 is not limited to the measured values of 10 samples, and can be changed as appropriate.

The verification device 3 verifies the difference between the average values of the differences in the measured values of a pair of temperature sensors A1, A2 ( a pair of temperature sensors B1, B2) (which will be the same if normal) in order to verify the difference between the corresponding data, following the steps 1 to 4 below. Note that the following explanation will be given taking the pair of temperature sensors A1, A2 and the pair of temperature sensors B1, B2 as examples.

Step 1: Setting the null hypothesis _H0 and alternative hypothesis _H1 The null hypothesis is _H0 : δ=0.
The alternative hypothesis is set as follows depending on the value of the variable iTestMode.
iTestMode=0...H ₁ :δ≠0
iTestMode=1...H ₁ :δ>0
iTestMode=2...H ₁ :δ<0

Here, δ is the difference between the pair of temperature sensors A1 and A2 or the difference between the pair of temperature sensors B1 and B2.

The significance level α is as follows, depending on the value of the variable iILevel:
iILevel=0...α=0.05
iILevel=1...α=0.10
iIL Level=2...α=0.20

Step 2: Calculate the test statistic _t0
When the average value of the samples of δ and the variance of the samples of δ are calculated from the difference between a pair of temperature sensors A1 and A2 or a pair of temperature sensors B1 and B2 using the following formulas (1) and (2), the test statistic _t0 is expressed by the following formula (3). Here, the number of samples n is set to 10.

Step 3: Testing Test the null hypothesis H ₀ using the test statistic t ₀ for the t-test, where t(n-1, α) is the comparison standard value obtained from the t-test table, and α is the significance level (generally 0.05).

In the case of H ₁ : δ≠0, if |t ₀ |≧t(n−1,α), it is significant and H ₀ is rejected. In other words, H ₁ is judged to be correct.
In the case of H ₁ : δ>0, if t ₀ ≧t(n−1, 2α), it is significant and H ₀ is rejected. In other words, H ₁ is judged to be correct.
H ₁ : In the case of δ<0, if t ₀ ≦t(n−1, 2α), it is significant and H ₀ is rejected. In other words, H ₁ is judged to be correct.

In any case, when _H0 is rejected, it means that there is a difference within the pair of temperature sensors A1, A2 or within the pair of temperature sensors B1, B2, and it is determined that the pair of temperature sensors A1, A2 or the pair of temperature sensors B1, B2 is faulty.

The rejection region based on the number of groups k is as shown in Table 1 below.

If the verifier 3 determines, through the above-mentioned test, that the averages of the measurement values of the pair of temperature sensors A1, A2 or the pair of temperature sensors B1, B2 are identical, it outputs a test result signal of "0." If the verifier 3 determines that the averages of the measurement values of the pair of temperature sensors A1, A2 or the pair of temperature sensors B1, B2 are different, it outputs a test result signal of "1."

When the test result signal "1" is input from the tester 3, the sensor warning determiner 4 determines that the measurement values of the pair of temperature sensors A1, A2 or the pair of temperature sensors B1, B2 are different and abnormal, and prompts the operator to be warned, for example, by sound or display.

Next, a description will be given of an example of a test based on specific measured values of the pair of temperature sensors A1, A2 and the pair of temperature sensors B1, B2.

It is now assumed that the measured values of a pair of temperature sensors A1, A2 and a pair of temperature sensors B1, B2 for each lot are obtained as shown in Table 2 below.

First, the pair of temperature sensors A1 and A2 is inspected.

The difference between the pair of temperature sensors A1 and A2 is calculated as shown in Table 3 below.

When the average value is calculated from the difference between the pair of temperature sensors A1 and A2, the variance is calculated from equation (1), and the test statistic _t0 is calculated from equation (3), the following equations (4), (5), (6), and (7) are obtained.

Moreover, t ₀ =4.621>t(9,0.05)=2.262, which is significant, indicates that the measurement values of the pair of temperature sensors A1, A2 are different, that is, it can be determined that either temperature sensor A1 or temperature sensor A2 is abnormal.

Similarly, the pair of temperature sensors B1 and B2 are inspected.

The difference between the pair of temperature sensors B1 and B2 is calculated as shown in Table 4 below.

When the average value is calculated from the difference between the pair of temperature sensors B1 and B2, the variance is calculated from equation (1), and the test statistic _t0 is calculated from equation (3), the following equations (8), (9), (10), and (11) are obtained.

Since t ₀ =0.753<t(9,0.05)=2.262, the result is not significant, and it cannot be said that the measurement values of the pair of temperature sensors B1, B2 are different. In other words, it can be determined that neither of the temperature sensors B1, B2 is abnormal.

In the above-described embodiment, the internal temperature of the vacuum heat treatment furnace 12 in the measurement system 11 is detected by a pair of temperature sensors A1, A2 and a pair of temperature sensors B1, B2. However, the number of measurement systems and pairs of temperature sensors is not limited.

In addition, in the above-described embodiment, the components of the temperature sensor anomaly determination device 1 (data accumulator 2, verification device 3, and sensor warning determination device 4) may be configured as a computer equipped with an arithmetic processing device, a storage device, etc., and the processing of each component may be executed by a program.

In this way, according to the above-described embodiment, it is possible to predict abnormalities in a temperature sensor using the most recent measurement value output by the temperature sensor itself, without the need for dedicated devices or parameter management as in the conventional technology.

The above describes the best mode of the temperature sensor anomaly determination device, temperature sensor anomaly determination method, and temperature sensor anomaly determination program according to the present invention, but the present invention is not limited to the description and drawings of this mode. In other words, it goes without saying that all other modes, examples, and operational techniques made by those skilled in the art based on this mode are included in the scope of the present invention.

REFERENCE SIGNS LIST 1 Temperature sensor abnormality determination device 2 Data accumulator 3 Verifier 4 Sensor warning determination device 11 Measurement system 12 Vacuum heat treatment furnace 13 Control loop 13A First zone upper control loop 13B Second zone upper control loop 13a PID controller 13b SCR (thyristor)
14 Vacuum pump 15 (15A, 15B) Heater A1, A2, B1, B2 Pair of temperature sensors

Claims (3)

a temperature sensor anomaly detection device for detecting an anomaly of the temperature sensor in a measurement system that controls the heating furnace to a target temperature so that the temperature distribution in the furnace for each lot of batch processing is approximately uniform , the temperature sensor anomaly detection device comprising: two sets of temperature sensors, each set consisting of two integrated temperature sensors that measure temperatures at approximately the same location in the atmosphere of a heating furnace as a measurement target; a first control loop in which a measurement value and a set value of one of the pair of temperature sensors in one set are input to a first PID controller and a first heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in one set, and a second control loop in which a measurement value and a set value of one of the pair of temperature sensors in the other set are input to a second PID controller and a second heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in the other set, the temperature sensor anomaly detection device detecting an anomaly of the temperature sensor in a measurement system that controls the heating furnace to a target temperature so that the temperature distribution in the furnace for each lot of batch processing is approximately uniform , the temperature sensor anomaly detection device comprising:
a data storage device that stores the most recent multiple sample measurements of the pair of temperature sensors for each lot of the batch processing for the two sets of temperature sensors;
a tester for calculating a sum of squares of the sampled measurement difference from the difference between the multiple samples of the pair of temperature sensors stored in the data storage device and an average of the sampled measurement difference, for the two sets of temperature sensors, calculating a variance of the sampled measurement difference based on the calculated sum of squares of the sampled measurement difference and the number of sampled measurement values, calculating a test statistic based on the calculated variance of the sampled measurement difference, the sum of squares of the sampled measurement difference and the number of sampled measurement values, and testing whether the measured values of the pair of temperature sensors are different by comparing the test statistic with a comparison reference value based on the number of sampled measurement values and a significance level;
a sensor warning determiner for determining whether or not the pair of temperature sensors is abnormal based on the inspection result of the inspector for the two sets of temperature sensors . a temperature sensor anomaly detection method using a temperature sensor anomaly detection device that detects anomalies in the temperature sensors in a measurement system that controls the heating furnace to a target temperature so that the temperature distribution in the furnace for each lot in a batch process is approximately uniform, the method comprising: using two sets of temperature sensors, each set of temperature sensors being an integrated pair of temperature sensors that measure temperatures at approximately the same location in the atmosphere of a heating furnace as a measurement target; a first control loop in which a measurement value and a set value of one of the pair of temperature sensors in one set are input to a first PID controller and a first heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in one set, and a second control loop in which a measurement value and a set value of one of the pair of temperature sensors in the other set are input to a second PID controller and a second heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in the other set ,
A step of storing the latest measured values of a plurality of samples of the pair of temperature sensors for each lot of the batch processing by a data storage device provided in the temperature sensor abnormality determination device for the two sets of temperature sensors ;
a step of calculating, by a verification device provided in the temperature sensor anomaly determination device for the two sets of temperature sensors , a sum of squares of the sampled measurement value differences from the difference between the measurement values of the multiple samples of the pair of temperature sensors stored in the data storage device and an average of the sampled measurement value differences, calculating a variance of the sampled measurement value differences based on the calculated sum of squares of the sampled measurement value differences and the number of sampled measurement values, calculating a test statistic based on the calculated variance of the sampled measurement value differences, the sum of squares of the sampled measurement value differences and the number of sampled measurement values, and verifying whether the measurement values of the pair of temperature sensors are different by comparing the test statistic with a comparison reference value based on the number of sampled measurement values and a significance level;
A temperature sensor abnormality determination method comprising: a step of determining whether or not the pair of temperature sensors is abnormal based on the inspection results of the inspection device using a sensor warning determiner provided in the temperature sensor abnormality determination device. a temperature sensor anomaly determination program for determining an anomaly of the temperature sensor in a measurement system that controls the heating furnace to a target temperature so that the temperature distribution in the furnace for each lot of batch processing is approximately uniform , the temperature sensor anomaly determination program comprising: two sets of temperature sensors, each set of temperature sensors being an integrated pair of temperature sensors that measure temperatures at approximately the same location in the atmosphere of a heating furnace as a measurement target; a first control loop in which a measurement value and a set value of one of the pair of temperature sensors in one set are input to a first PID controller and a first heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in one set, and a second control loop in which a measurement value and a set value of one of the pair of temperature sensors in the other set are input to a second PID controller and a second heater is controlled on/off based on an operation amount corresponding to the difference between the measurement value and set value of one of the pair of temperature sensors in the other set ,
Computer,
a data storage unit that stores the latest multiple sample measurements of the pair of temperature sensors for each lot of the batch processing for the two sets of temperature sensors;
a tester for calculating a sum of squares of the sampled measurement difference from the difference between the multiple samples of the pair of temperature sensors stored in the data storage device and an average of the sampled measurement difference, for the two sets of temperature sensors, calculating a variance of the sampled measurement difference based on the calculated sum of squares of the sampled measurement difference and the number of sampled measurement values, calculating a test statistic based on the calculated variance of the sampled measurement difference, the sum of squares of the sampled measurement difference and the number of sampled measurement values, and testing whether the measured values of the pair of temperature sensors are different by comparing the test statistic with a comparison reference value based on the number of sampled measurement values and a significance level;
a temperature sensor abnormality determination program for causing the two sets of temperature sensors to function as a sensor warning determiner that determines whether or not the pair of temperature sensors is abnormal based on the inspection result of the inspector.

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