JP6800072B2 - Deterioration diagnosis method - Google Patents

Description

The present invention relates to a deterioration diagnosis how to diagnose the deterioration of a heating apparatus comprising a heater.

In industrial processes, there are many processes that heat materials. In such a heating process, an electric heater is generally used. In addition, a temperature controller is used to control the operation of the electric heater. The temperature controller uses a temperature sensor such as a thermocouple or a resistance temperature detector to measure the temperature of the processing target (monitoring target) heated by the heater. The measured temperature is numerically displayed on the temperature controller.

Further, in the temperature controller, the control output (MV value) is obtained according to the detected temperature (PV value) and the set temperature (SP value). The obtained control output is output to a heater actuator such as a power regulator. The heater actuator controls the drive current of 100 V from the commercial power source according to the control output and outputs it to the heater. By heating the heater controlled in this way, the temperature of the processing target is controlled. In addition, the temperature controller is equipped with an abnormality detection function, detects abnormal temperatures of the processing target to be monitored, abnormalities of the temperature sensor, etc., and externally outputs the detected abnormal events as event information and displays an alarm. .. For example, an alarm is displayed on a display that numerically displays the temperature.

Further, the temperature controller detects an abnormality of the heater itself such as a disconnection of the heater (see Patent Documents 1 and 2). For example, the current / voltage applied to the heater is measured to obtain the effective value power, the resistance value is further obtained from the relationship between the current and the voltage, and the deterioration of the heater is determined from the change in the obtained resistance value and the difference in the degree of change. Judgment (see Patent Document 1). Further, the heater deterioration is judged by using the data obtained by tabulating the measured measurement points of the control output and the current value (see Patent Document 2).

Japanese Patent No. 2683851 Japanese Patent No. 3988942

However, in the above-mentioned technique, it is first necessary to measure the current flowing through the heater and the voltage applied to the heater. Further, in the above-mentioned technique, calculation of parameters for abnormality diagnosis such as resistance value is complicated. Further, in the above-mentioned technique, there is a problem that it takes time to measure the elapsed time or the like in order to investigate the time change of the resistance value. As described above, in the above-mentioned technique, complicated calculation and measurement are required until the abnormality is determined.

The present invention has been made to solve the above problems, and an object of the present invention is to make it easier and more quickly to determine an abnormality of a heater.

The deterioration diagnosis method according to the present invention includes a first step of preparing a reference line showing the normal characteristics of the heater constituting the heating device to be deteriorated, and a second step of setting an allowable range for the deterioration diagnosis of the heater. The process, the third step of acquiring the control value for controlling the heater, the fourth step of measuring the current supplied to the heater according to the control value acquired in the third step, and acquiring the measured value, and the measurement. It includes a fifth step of determining that the heating device has deteriorated when the value exceeds the permissible range, and in the first step, the heater characteristics showing the relationship between the control value in the normal heater and the corresponding current are approximated. In the second step, a permissible range is set from the upper permissible value and the lower permissible value of the current value with respect to the control value in the reference line.

In the above deterioration diagnosis method, in the first step, set points are set at the minimum value of the control value and the maximum value of the control value in the heater characteristics, an approximation line by a straight line connecting the set setting points is created, and the approximation line is combined with the approximation line. The maximum deviation is calculated in each of the region where the heater characteristic is smaller and the region where the heater characteristic is larger between the curves showing the heater characteristics, and if the two maximum deviations obtained are smaller than the predetermined allowable deviations, an approximation line is used. If one of the maximum deviations is larger than the permissible deviation, a new setting point is set at the location where the two maximum deviations of the heater characteristics are obtained, and the newly set setting point and the already set setting point are set. In the process of creating an approximation line that creates a new approximation line by connecting adjacent set points with a straight line, and the region where the heater characteristic between the new approximation line and the curve showing the heater characteristics is smaller and the heater characteristics The approximate line is used as a reference line by repeating the maximum deviation search step of obtaining a new maximum deviation in each of the larger regions until the obtained new maximum deviation becomes smaller than the allowable deviation.

In the above deterioration diagnosis method, in the first step, the heater current value is actually measured at each control value set by setting a plurality of control values within the minimum / maximum range of the control value in the normal heater, and the actual measurement is performed. Using a plurality of set points based on each control value obtained as a result and each heater current value, a polygonal line is created by connecting adjacent set points with a straight line, and the created polygonal line is used as a reference line that approximates the heater characteristics to the polygonal line.

In the above deterioration diagnosis method, in the second step, the larger the control value, the wider the allowable range may be set.

The deterioration diagnosis device according to the present invention is configured to acquire a reference storage unit that stores an allowable range for deterioration diagnosis of the heater constituting the heating device to be deteriorated, and a control value for controlling the heater. The control value acquisition unit, the current measurement unit configured to measure the current supplied to the heater according to the control value acquired by the control value acquisition unit, and the current measurement unit acquired the measured value. It is equipped with a deterioration determination unit configured to determine that the heating device has deteriorated when the measured value exceeds the allowable range, and the allowable range is the current value with respect to the control value on the reference line indicating the normal characteristics of the heater. It is set from the upper permissible value and the lower permissible value, and the reference line is an approximation of the heater characteristics showing the relationship between the control value in the normal heater and the corresponding current.

In the deterioration diagnosis device, the permissible range may be set wider as the control value becomes larger.

In the deterioration diagnosis device, the reference line, the allowable range, and the measurement point based on the control value acquired by the control value acquisition unit and the measurement value acquired by the current measurement unit are two-dimensional with the control value and the measurement value as the axis. A display unit configured to display a graph arranged on the coordinates of the plane may be provided.

From the above description, according to the present invention, it is possible to obtain an excellent effect that the abnormality of the heater can be determined more easily and quickly.

FIG. 1 is a configuration diagram showing a configuration of a deterioration diagnosis device according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating a deterioration diagnosis method according to the embodiment of the present invention. FIG. 3 is a flowchart for explaining the preparation of the reference line. FIG. 4 is an explanatory diagram showing a state in which the heater characteristics are shown by curves on the coordinates of the two-dimensional plane centered on the control value and the measured value. FIG. 5 is an explanatory diagram showing a reference line and an allowable width with respect to the heater characteristics shown on the coordinates of the two-dimensional plane centered on the control value and the measured value. FIG. 6 is an explanatory diagram showing a reference line and an allowable width by two setting points for the heater characteristics shown on the coordinates of the two-dimensional plane about the control value and the measured value. FIG. 7 is an explanatory diagram showing a reference line and an allowable width by two setting points for the heater characteristics shown on the coordinates of the two-dimensional plane about the control value and the measured value. FIG. 8 is an explanatory diagram showing a reference line and an allowable width with four set points for the heater characteristics shown on the coordinates of the two-dimensional plane about the control value and the measured value.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a configuration of a deterioration diagnosis device 100 according to an embodiment of the present invention. The deterioration diagnosis device 100 includes a reference storage unit 101, a control value acquisition unit 102, a current measurement unit 103, and a deterioration determination unit 104. The deterioration diagnosis device 100 diagnoses deterioration of the heating device including the heater 111 and the operation unit 112.

The reference storage unit 101 stores an allowable range (normal range) for diagnosing deterioration of the heater 111 and the operation unit 112. The permissible range is set based on a reference line showing the normal characteristics of the heater 111 constituting the heating device to be diagnosed for deterioration. This reference line is also stored in the reference storage unit 101.

The control value acquisition unit 102 acquires a control value for controlling the heater 111 (heating device) output by the control unit 113. The control value is calculated by the control unit 113 from the measured value measured by the temperature measuring unit 114 and the set value set, and is output to the operation unit 112. The control unit 113 is, for example, a temperature controller. The operation unit 112 is composed of, for example, a well-known power regulator. The operation unit 112 controls the drive current of 100 V obtained from a commercial power source by the above control value, and controls the heating operation by the heater 111. By this control, the value of the current flowing through the heater 111 is determined. The control value acquisition unit 102 is a functional unit that acquires the above-mentioned control value output from the control unit 113 (see Patent Document 1).

The current measuring unit 103 measures the current supplied to the heater 111. For example, the current measuring unit 103 acquires an effective current value as a measured value. The current measuring unit 103 is composed of, for example, a well-known current transformer. In the embodiment, the current measuring unit 103 is used for alarm output in the control unit 113 which is a temperature controller. In this case, the current measuring unit 103 detects the drive current value to the heater 111 and outputs it to the control unit 113, the control unit 113 compares the preset alarm level with the detected value, and the detected value is the alarm level. When it exceeds, an alarm signal indicating an abnormality in the heating temperature is output. The measured value may be an average current value.

When the measured value acquired by the current measuring unit 103 exceeds the permissible range, the deterioration determining unit 104 determines that the heater 111 or the operating unit 112 (heating device) has deteriorated. For example, the deterioration determination unit 104 operates the heater 111 because the measured value exceeds the range of the lower permissible value and the upper permissible value in the control value acquired by the control value acquisition unit 102 when the measured value is acquired. Judgment of deterioration of unit 112. When the permissible range is exceeded, not only the deterioration of the heater 111 but also the deterioration or failure of the operation unit 112 can be determined. Even if there is no abnormality in the heater 111, the current supplied to the heater 111 may become abnormal even if the operation unit 112 malfunctions.

Further, the reference line, the permissible range, and the measurement point based on the control value acquired by the control value acquisition unit 102 and the measurement value acquired by the current measurement unit 103 are on the two-dimensional plane centered on the control value and the measurement value. The graph arranged on the coordinates is displayed on the display unit 105.

Here, the reference line is an approximate line of the heater characteristics indicating the relationship between the control value output by the control unit 113 and the current in the heater 111 in the normal state corresponding to this control value. The reference line is composed of one or more line segments (linear equations) on the coordinates of the two-dimensional plane centered on the control value and the measured value.

For example, the heater characteristics of the heater 111 in the normal state may be measured, and the reference line may be obtained by approximating the polygonal line from the measured heater characteristics. A predetermined number of set points (break points) may be provided on the obtained curve of the heater characteristics under predetermined conditions, and the provided set points may be connected by a straight line (line segment) to serve as a reference line. In addition, the current value (heater current value) is obtained by measuring (actually measuring) the current with respect to the control value in the heater 111 at the normal time at a predetermined number of measurement points, and the set point based on the predetermined number of control values and the current value is set. It may be set and used as a reference line by connecting adjacent setting points with a straight line.

The permissible range is set (composed) from the upper permissible value and the lower permissible value of the current value with respect to the control value on the reference line. The range between the upper allowable value line based on the upper allowable value of the current value with respect to the control value on the reference line and the lower allowable value line based on the lower allowable value of the current value with respect to the control value on the reference line is the heater 111 or the operation unit. This is an acceptable range in which 112 can be regarded as normal.

Next, an operation example (deterioration diagnosis method) of the deterioration diagnosis device 100 according to the embodiment of the present invention will be described with reference to the flowchart of FIG.

First, in step S201, a reference line is created (prepared) by approximating the relationship (heater characteristic) between the control value in the heater 111 in the normal state and the corresponding current (heater characteristic), and stored in the reference storage unit 101 [first step]. ]. Next, in step S202, an allowable range for diagnosing heater deterioration is set and stored in the reference storage unit 101 [second step]. The permissible range is set from the upper permissible value and the lower permissible value of the current value with respect to the control value in the reference line. The permissible range may be appropriately set according to the heater to be determined and the operation unit (heating device). Here, the larger the control value, the wider the allowable range should be set. Generally, the smaller the control value, the smaller the range in which the current value can be taken. Therefore, in the range where the control value is small, the width for determining an abnormality should be narrowed, and in the range where the control value is large, the width for determining an abnormality should be widened.

Next, in step S203, the deterioration determination unit 104 determines the start of determination. For example, the judgment is made by accepting the input of the instruction to carry out the judgment. Further, for example, the determination cycle time may be set, and the determination may be started when the determination cycle time elapses.

When the start of the determination is determined (yes in step S203), in step S204, the control value acquisition unit 102 acquires the control value for controlling the heater 111 from the control unit 113 [third step]. Next, in step S205, the current measuring unit 103 measures the current supplied to the heater 111 according to the control value acquired by the control value acquiring unit 102, and acquires the measured value [fourth step].

Next, in step S206, the deterioration determination unit 104 determines whether or not the measured value acquired by the current measurement unit 103 exceeds the allowable range. If the measured value exceeds the permissible range, the deterioration determination unit 104 determines that the heater 111 has deteriorated.

Here, due to the characteristics of the heater 111, a delay with respect to control occurs at the start of operation of the heater 111. Therefore, in a state where such a response delay occurs, the measured value may exceed the permissible range. In addition, the measured value may exceed the permissible range due to momentary noise or the like. Therefore, when the third step and the fourth step are repeated a plurality of times and the state in which the measured value exceeds the permissible range is resolved within a predetermined delay time (for example, 30 ms), it is considered that the permissible range is not exceeded. It is good to judge.

When the deterioration determination unit 104 determines that the heater 111 has deteriorated (yes in step S206), the deterioration determination unit 104 notifies this state in step S207. For example, by displaying an alarm on the display unit 105, the user is notified of the deterioration determination of the heater 111.

Next, the preparation (creation) of the reference line in step S201 will be described with reference to the flowchart of FIG. First, in step S211, the heater characteristics are acquired by measuring the current supplied to the heater 111 with respect to the different control values given to the heater 111 in the normal state. As this heater characteristic, for example, as shown in FIG. 4, a curve 401 shown on a two-dimensional plane centered on a control value and a measured value is acquired.

Next, in step S212, set points are set at regular intervals on the obtained curve of the heater characteristics. The setting points other than the setting points at both ends are the polygonal points in the approximate polygonal line. For example, as shown in FIG. 5, nine setting points indicated by black circles are set on the curve 401 in the coordinates of the two-dimensional plane centered on the control value and the measured value. At least, set points are set for the minimum value of the control value and the maximum value of the control value. Next, a reference line is created by connecting two adjacent set points with each other with a straight line. For example, as shown in FIG. 5, nine setting points are connected in order to create a reference line 501. The reference line 501 is composed of eight line segments.

The upper allowable value line 502 and the lower allowable value line 503 are set for the reference line 501 created as described above, and the region sandwiched by the upper allowable value line 502 and the lower allowable value line 503 is set as the allowable range. .. The upper allowable value line 502 and the lower allowable value line 503 are also composed of a plurality of straight lines (line segments).

The deterioration diagnosis device 100 is a computer device including a CPU (Central Processing Unit), a main storage device, an external storage device, a network connection device, and the like. The deterioration diagnosis device 100, which is a computer device, realizes each of the above-mentioned functions by operating the CPU by a program developed in the main storage device. Further, each function may be distributed to a plurality of computer devices.

By the way, the setting points for creating the reference line may be set as shown below. First, as shown in FIG. 6, in the coordinates of the two-dimensional plane centered on the control value and the measured value, the set points are arranged corresponding to the minimum value and the maximum value of the control value on the curve 401 showing the heater characteristics. An approximation line 601 connecting these is set. Further, a predetermined upper allowable value line 602 and a lower allowable value line 603 are set with respect to the approximate line 601. The region sandwiched between the upper allowable value line 602 and the lower allowable value line 603 is a candidate for the allowable range.

As described above, the approximation line 601 is determined by the two setting points, the candidate of the allowable range is set, the curve 401 falls within the candidate of the allowable range, and the maximum deviation between the approximate line 601 and the curve 401 is set in advance. Judge that it is smaller than the set tolerance. If the curve 401 falls within the permissible range and the maximum deviation is smaller than the permissible deviation, the approximation line 601 is used as the reference line. In the example shown in FIG. 6, a region where the curve 401 exceeds the permissible range is generated. Therefore, in this case, as shown in FIG. 7, the curve 401 and the deviation are maximum in the negative direction of the measured value 611, and the curve 401 and the deviation are maximum in the direction of controlling the measured value with respect to the approximate line 601. [Maximum deviation search step] for obtaining the value 612.

Next, new setting points are added on the curve 401 at the obtained location 611 and on the curve 401 at the location 612. Next, as shown in FIG. 8, a new approximation line 601a for connecting the four control points due to the addition is set [approximate line creation step]. Further, a predetermined upper allowable value line 602a and a lower allowable value line 603a are set with respect to the new approximate line 601a.

It is confirmed that the curve 401 falls within the allowable range of the upper allowable value line 602a and the lower allowable value line 603a obtained in this manner, and the maximum deviation between the approximate line 601a and the curve 401 is smaller than the allowable deviation. .. In the state shown in FIG. 8, the curve 401 falls within the permissible range, and the maximum deviation between the approximate line 601a and the curve 401 is smaller than the permissible deviation. Therefore, the approximate line 601a is used as the reference line.

According to the above-described reference line creating method, by appropriately setting the maximum deviation, it is possible to set the permissible range in which practical deterioration determination is possible without unnecessarily increasing the set points. In addition, depending on the setting condition of the permissible deviation, the approximate curve can be determined only by comparing with the maximum deviation with the permissible deviation without comparing with the permissible range.

Further, a reference line may be created as shown below. First, in the normal heater, a plurality of control values are set within the minimum and maximum range of the control values, and the heater current value is measured at each set control value. For example, the control value is changed in the range of 0 to 100% in a range of 10%, and the heater current value is measured at each control value. A plurality of set points based on each control value and each heater current value obtained as a result of this measurement are used, and a polygonal line connecting adjacent set points with a straight line is used as a reference line that approximates the heater characteristics to the polygonal line.

As described above, the present invention first creates a reference line by approximating the heater characteristics indicating the relationship between the control value in the normal heater and the corresponding current by a polygonal line. Next, the permissible range is set from the upper permissible value and the lower permissible value of the current value with respect to the control value in the reference line. Using the permissible range created in this way, if the measured value exceeds the permissible range, it is determined that the heater has deteriorated. As a result, according to the present invention, it becomes possible to more easily and quickly determine the abnormality of the heater without increasing the scale of the device such as requiring a large storage unit.

According to the above invention, since the permissible range is set using the reference line approximated by the polygonal line, the amount of data held as the permissible range can be very small. Since the reference line is composed of a combination of straight lines (linear expression), the allowable range is also composed of a combination of straight lines (linear expression), and the amount of data is very small. Further, since the permissible range based on the reference line approximated by the polygonal line is used, the permissible range becomes a continuous determination standard within the range that the control value can take. Therefore, according to the present invention, unlike the case of table reference or the like, it is not necessary to perform interpolation or the like at the time of deterioration determination. Further, since the current value flowing through the heater may be measured, it is not necessary to measure the voltage and it is not necessary to bother to obtain the resistance value.

Further, the abnormality may be determined by using the instantaneous value of the heater current value acquired periodically, and it is not necessary to obtain the tendency of the temporal change for the determination, and the determination can be performed quickly.

By the way, the determination may be made as shown below. For example, by expanding the setting of the permissible range, it may be determined that an abnormality occurs only when a large abnormality occurs. Further, the setting of the allowable range (difference from the reference line) may be determined in a plurality of stages. For example, it is determined that there is a possibility of deterioration in the first stage. In the second stage, it is judged that the deterioration may have progressed. In the third stage, it is judged that the deterioration is certain. Any more than this is judged to be a failure or disconnection.

In addition, if the heater current measurement value is always almost 0 for any control value, it can be judged as a disconnection of the heater (or a failure of the power regulator or other complete failure of the device related to heating). Good.

Further, when the delay time is set for the determination, it may be determined that the deterioration is certain only when the abnormality of the instantaneous value occurs continuously for a certain number of times or more. Alternatively, if the measured value is close to 0, it may be determined that the wire is broken. As a result, accurate judgment is possible even if the allowable range is narrowed. In addition, the degree of progress of the abnormality can be determined by the width outside the normal range.

Further, in the case of time proportional output or on / off control, the output of the control unit is either on or off. In this case, if only the current value at the time of turning on is measured, the possibility of deterioration of the heater, abnormality of the device, or short circuit may be determined when the measured value drops or rises from the permissible range. ..

Further, the control value by PID control is a continuous value of 0 to 100%, but in the case of time-proportional output, the operation amount (control value) is expressed by the time ratio of on and off, so only the current at the time of on is used. Be measured. Therefore, in this case, if an intermediate current value is generated, it can be determined that the product has deteriorated or failed depending on the degree of difference from the normal value. Further, in the case of on / off control, since there are only on and off as the output, it can be handled in the same manner as in the case of time proportional output. In the on / off control, a transient state occurs. Therefore, the determination may not be performed for a certain period of time after the on / off switching so that the transient state is not erroneously determined as an abnormality.

On the other hand, when the on and off time is short, the measurement is not performed even if it is an abnormal value, and even if it is measured, if a delay is set for the judgment, before the delay time elapses. On / off is switched, and as a result, it becomes impossible to judge.

On the other hand, for example, when the abnormality in the on state is continuous, even if the on / off is switched, the elapsed time measured for determining the delay is integrated without being initialized. Only when a normal value appears, the measured elapsed time need to be reset.

In addition, the heater current value is measured and judged, but the measured value may exceed the permissible range due to a decrease in the supplied power or a malfunction of the power regulator (operation unit) on the instrumentation. Therefore, if the determination of abnormality is not resolved even if the heater is replaced with a normal product after it is determined to be abnormal, it can be seen that there is a problem in a part other than the heater. As described above, the present invention can be used as a so-called loop diagnosis.

Further, a reference value generation unit may be provided to automatically generate a reference line. First, the reference value generation unit changes the control value within the set control value range and outputs it from the control unit. For example, the control price range may be 10%. Further, the reference value generation unit acquires the heater current value corresponding to each control value output, and sets a plurality of set points based on each control value and each heater current value. Next, the reference value generation unit sets a polygonal line connecting adjacent set points with a straight line as a reference line whose heater characteristics are approximated to the polygonal line. The reference value generation unit receives an instruction input by the user, for example, by pressing an instruction button provided on the device, and starts the above-mentioned operation to generate a reference line. The permissible range may be set based on the reference line generated in this way.

As a characteristic of the heater current value, the linearity may be extremely low in the characteristic near the control value of 0%. As a countermeasure, when setting the measurement point between 0% and 100%, the data is acquired by changing it in 1% increments, and only the part where the current value rises from 0% is in 2% increments. The set point data may be used, and the portion of 10% or more may be set point data in increments of 15% of the control value. Further, when the measurement is acquired in 1% increments and set as the set point data, the number of set points may be manually set so as to minimize the calculation error.

The present invention is not limited to the embodiments described above, and many modifications and combinations can be carried out by a person having ordinary knowledge in the art within the technical idea of the present invention. That is clear.

101 ... Reference storage unit, 102 ... Control value acquisition unit, 103 ... Current measurement unit, 104 ... Deterioration determination unit, 105 ... Display unit, 111 ... Heater, 112 ... Operation unit, 113 ... Control unit, 114 ... Temperature measurement unit.

Claims (2)

The first step of preparing a reference line showing the normal characteristics of the heaters that make up the heating device to be diagnosed for deterioration, and
The second step of setting the allowable range for the deterioration diagnosis of the heater, and
The third step of acquiring the control value for controlling the heater, and
The fourth step of measuring the current supplied to the heater according to the control value acquired in the third step and acquiring the measured value, and
A fifth step of determining that the heating device has deteriorated when the measured value exceeds the permissible range is provided.
In the first step, the reference line is created by approximating the heater characteristics showing the relationship between the control value in the heater in the normal state and the corresponding current.
In the second step, the allowable range is set from the upper allowable value and the lower allowable value of the current value with respect to the control value on the reference line .
In the first step, set points are set at the minimum value of the control value and the maximum value of the control value in the heater characteristics, and an approximate line formed by a straight line connecting the set set points is created.
The maximum deviation is obtained in each of the region where the heater characteristic is smaller and the region where the heater characteristic is larger between the approximation line and the curve showing the heater characteristic.
When the two maximum deviations obtained are smaller than the predetermined allowable deviations, the approximate line is used as the reference line.
If either maximum deviation is greater than the permissible deviation
A new set point is set at the location where the two maximum deviations of the heater characteristics are obtained, and a new approximation in which adjacent set points are connected by a straight line at the newly set set point and the already set set point. A new maximum deviation between the approximate line creation step of creating a line and the region where the heater characteristic is smaller and the region where the heater characteristic is larger between the new approximate line and the curve showing the heater characteristic. A deterioration diagnosis method characterized in that the approximate line is set as the reference line by repeating the step of searching for the maximum deviation for obtaining the above value until the new maximum deviation obtained is smaller than the permissible deviation . In degradation diagnosis method of claim 1 Symbol placement,
In the second step, the deterioration diagnosis method is characterized in that the larger the control value is, the wider the allowable range is set.