JP5230508B2 - Degradation diagnosis method for humidity sensor - Google Patents

Description

  The present invention relates to a humidity sensor degradation diagnosis method for diagnosing degradation of a humidity sensor installed in a measurement environment atmosphere.

  For the humidity sensor, a humidity sensor with a moisture sensitive layer inserted between the upper electrode and lower electrode is used as a humidity sensing element (humidity detection element). There is a capacitance change equation in which the capacitance changes in accordance with the change in.

  When any of these types of humidity sensors is installed at the measurement site, it is directly exposed to the measurement environment and measures the humidity. Therefore, the humidity sensing element depends on the atmosphere of the measurement environment (for example, a gas such as sulfide or organic solvent). Will deteriorate. However, it is generally known that the moisture sensitive element can be recovered from this deterioration by heating the moisture sensitive element (referred to as heat cleaning) and removing components in the atmosphere that cause the moisture sensitive element to deteriorate. It has been. Conventionally, using this knowledge, heating cleaning is performed regularly (see, for example, Patent Document 1), or the degree of deterioration of the humidity sensor is detected to change the heating cleaning conditions (heating temperature and heating time). (For example, see Patent Document 2).

The humidity detection device disclosed in Patent Literature 1 is connected to a humidity detection element having a heater for heating, a heater control circuit for applying power to the heater to keep the humidity detection element at a constant temperature, and the heater control circuit. The heating circuit is periodically provided with a timer circuit that starts heating cleaning at regular intervals and an oscillation circuit that is connected to the humidity detecting element and measures the impedance change of the humidity detecting element.
In addition, the humidity sensor control device disclosed in Patent Document 2 heats the impedance change type moisture sensitive element portion with a heater in the same manner as in Patent Document 1 above, and removes contaminants. When performing, the heating temperature was set to 500 to 1200 ° C. according to the deterioration of the humidity sensor, and the heating time was set to about several seconds to 10 minutes.

Japanese Patent Laid-Open No. 5-172776 JP 2003-166963 A

Since the conventional humidity sensor is configured as described above, regular heat cleaning is performed even when the humidity sensitive element has not deteriorated to the extent that cleaning is necessary, and the opportunity for heat cleaning increases. As a result, the life of the moisture sensitive element was shortened.
In addition, when the component of the atmosphere that causes the moisture-sensitive element to deteriorate is an organic solvent or the like, the component can be removed by heat cleaning. However, in the case of a deliquescent material such as sulfide, the moisture-sensitive element is removed. It is possible to remove more effectively by washing than by heating. However, since heat cleaning has been performed uniformly even on deliquescent substances, there has been a problem that the removal efficiency is lowered and the opportunity for heat cleaning is increased to shorten the life of the moisture sensitive element.

  In addition, the conventional humidity sensor is not configured to determine whether the humidity sensor is caused by an organic solvent or a deliquescent substance, so an analyst visits the site to determine the cause of deterioration. It is necessary to determine using an analytical instrument. Therefore, there is a problem that the work is troublesome.

  The present invention has been made to solve the above-described problems, and the humidity sensor needs to be cleaned by using the humidity sensor, the temperature sensor, and the heating means originally provided in the humidity sensor. The purpose is to make a self-diagnosis of the deterioration.

  The humidity sensor degradation diagnosis method according to the invention of claim 1 is installed in a measurement environment atmosphere, has two humidity sensing elements and two temperature sensing elements, and alternately measures the two humidity sensing elements. Or switch to non-measurement, one humidity sensor and temperature sensor measure relative humidity and temperature during the measurement period, and the other non-measurement humidity sensor and temperature sensor are for one measurement A humidity sensor deterioration diagnosis method comprising a heating means capable of performing heat cleaning during a measurement period of a moisture sensing element and a temperature sensing element, wherein the humidity sensing element for measurement and the relative temperature sensor in the measurement environment atmosphere A first dew point temperature calculating step for obtaining a dew point temperature obtained based on the measured values of humidity and temperature as a first dew point temperature; and in a measurement environment atmosphere of the non-measurement humidity sensing element and the temperature sensing element during heating by the heating means Measured relative humidity and temperature Based on the second dew point temperature calculating step for obtaining the dew point temperature obtained as the second dew point temperature and the difference between the first dew point temperature and the second dew point temperature, the measurement moisture sensitive element needs to be cleaned. A deterioration determination step for determining whether or not the deterioration is occurring.

  According to the second aspect of the present invention, the humidity sensor deterioration diagnosis method compares the first dew point temperature obtained in the first dew point temperature calculating step with the second dew point temperature obtained in the second dew point temperature calculating step. And a comparison step for comparing the relative height difference with the first threshold, and the deterioration determination step includes the second dew point temperature rather than the first dew point temperature. Is higher and the relative height difference is larger than the first threshold value, the organic solvent in the measurement environment atmosphere causes deterioration of the measurement moisture sensitive element that requires cleaning. Judgment is made.

  According to a third aspect of the present invention, there is provided a method for diagnosing a deterioration of a humidity sensor, wherein, in the deterioration determination step, if it is determined that the measurement moisture-sensitive element has deteriorated to a degree that requires cleaning with an organic solvent. The humidity sensitive element is switched to non-measurement and is heated and cleaned by the heating means, and the other non-measurement humidity sensitive element is switched to measurement and a heating cleaning step for continuing measurement is provided.

  According to a fourth aspect of the present invention, the humidity sensor deterioration diagnosis method compares the first dew point temperature obtained in the first dew point temperature calculating step with the second dew point temperature obtained in the second dew point temperature calculating step. And a comparison step for comparing the relative height difference with the second threshold, and the deterioration determination step includes the second dew point temperature rather than the first dew point temperature. Is lower and the relative height difference is larger than the second threshold, the deliquescent substance in the measurement environment atmosphere causes the measurement moisture sensitive element to deteriorate to a degree that requires cleaning. Is determined.

  The humidity sensor deterioration diagnosis method according to the invention of claim 5 is the measurement method when it is determined in the deterioration determination step that the measurement moisture-sensitive element has deteriorated to a degree that requires cleaning due to the deliquescent material. In addition to notifying that the moisture sensitive element for use is switched to non-measuring and performing cleaning cleaning, a cleaning notifying step for continuing measurement by switching the other non-measuring moisture sensitive element to be used for measurement is provided.

  A humidity sensor deterioration diagnosis method according to a sixth aspect of the present invention is a measurement moisture-sensitive element and a temperature-sensitive element that are installed in a measurement environment atmosphere and measures relative humidity and temperature, and a measurement moisture-sensitive element and temperature-sensitive element. A heating means for heating and cleaning the measurement moisture-sensitive element during the non-measurement period, and a non-measurement humidity-sensitive element and sensor for measuring the relative humidity and temperature during the non-measurement period of the measurement moisture-sensitive element and the temperature-sensitive element. A method for diagnosing deterioration of a humidity sensor including a temperature element, wherein a dew point temperature obtained based on measured values of relative humidity and temperature in a measurement environment atmosphere of the non-measurement humidity sensor and the temperature sensor is a first dew point temperature. A first dew point temperature calculation step determined as follows, a humidity sensor for measurement during heating by the heating means, and a dew point temperature obtained based on measured values of relative humidity and temperature in the measurement environment atmosphere of the temperature sensor. Second to find as temperature A dew point temperature calculating step and a deterioration determining step for determining whether or not the measurement moisture sensitive element has deteriorated to a degree necessary for cleaning based on a difference between the first dew point temperature and the second dew point temperature. It is.

  According to a seventh aspect of the present invention, the humidity sensor deterioration diagnosis method compares the first dew point temperature obtained in the first dew point temperature calculating step with the second dew point temperature obtained in the second dew point temperature calculating step. And a comparison step for comparing the relative height difference with the first threshold, and the deterioration determination step includes the second dew point temperature rather than the first dew point temperature. Is higher and the relative height difference is larger than the first threshold value, the organic solvent in the measurement environment atmosphere causes deterioration of the measurement moisture sensitive element that requires cleaning. Judgment is made.

  The humidity sensor deterioration diagnosis method according to the invention of claim 8 is a method for determining the deterioration of the humidity sensitive element for measurement by the organic solvent in the deterioration determination step. A heat cleaning step for heat cleaning is provided.

  According to a ninth aspect of the present invention, there is provided a method for diagnosing a deterioration of a humidity sensor by comparing a first dew point temperature obtained in a first dew point temperature calculating step with a second dew point temperature obtained in a second dew point temperature calculating step. And a comparison step for comparing the relative height difference with the second threshold, and the deterioration determination step includes the second dew point temperature rather than the first dew point temperature. Is lower and the relative height difference is larger than the second threshold, the deliquescent substance in the measurement environment atmosphere causes the measurement moisture sensitive element to deteriorate to a degree that requires cleaning. Is determined.

  According to a tenth aspect of the present invention, there is provided a method for diagnosing a deterioration of a humidity sensor. A cleaning notification step for notifying that the operation is performed is provided.

  The humidity sensor deterioration diagnosis method according to the invention of claim 11 is obtained based on the measurement values of the relative humidity and temperature in the measurement environment atmosphere of the measurement moisture sensitive element and the temperature sensitive element instead of the first dew point temperature. Water vapor obtained using water vapor pressure and based on measured values of relative humidity and temperature in the measurement environment atmosphere of the non-measuring moisture sensing element and the temperature sensing element during heating by the heating means, instead of the second dew point temperature Pressure is used.

  The deterioration diagnosis method for a humidity sensor according to the invention of claim 12 can be obtained based on measured values of relative humidity and temperature in the measurement environment atmosphere of the non-measuring humidity sensing element and the temperature sensing element instead of the first dew point temperature. Water vapor pressure obtained, and instead of the second dew point temperature, the moisture sensor for measurement during heating by the heating means and the water vapor obtained based on the measured values of relative humidity and temperature in the measurement environment atmosphere of the temperature sensitive element Pressure is used.

  According to the first and sixth aspects of the present invention, the humidity sensitive element is deteriorated to a degree that requires cleaning based on the difference between the first dew point temperature during normal measurement and the second dew point temperature during heating. You can self-diagnose. In addition, since the self-diagnosis can be performed by using the humidity sensor, the temperature sensor, and the heating means that are originally provided in the humidity sensor, an analyst and other analytical instruments are unnecessary.

  According to the second and seventh aspects of the present invention, when the moisture sensitive element is deteriorated by the organic solvent, the humidity measurement value during heating is shifted to a lower value than during normal measurement, but the moisture sensitive element is heated. Since the influence of the organic solvent is eliminated, the tendency that the second dew point temperature during heating is higher than the first dew point temperature during normal measurement is determined. It can be estimated that it is an organic solvent in the measurement environment atmosphere.

  According to the third and eighth aspects of the invention, when the factor that deteriorates the moisture sensitive element is estimated to be an organic solvent, the heating means is used to perform the heat cleaning. Cleaning can be performed.

  According to the inventions of claim 4 and claim 9, when the moisture sensitive element is deteriorated by the deliquescent substance, the humidity measurement value during heating is shifted to a higher value than during normal measurement, but the moisture sensitive element is heated. As a result, the tendency of the second dew point temperature during heating to be lower than the first dew point temperature during normal measurement is determined. It can be estimated that the deteriorating factor is a deliquescent substance in the measurement environment atmosphere.

  According to the fifth and tenth aspects of the present invention, when it is estimated that the factor that deteriorates the moisture-sensitive element is a deliquescent substance, cleaning cleaning that can recover from deterioration more effectively than heat cleaning is performed. Since notification is made to perform, appropriate cleaning can be performed at an appropriate time.

  According to the invention of Claim 11 and Claim 12, even if it uses a water vapor pressure instead of a dew point temperature, deterioration of a moisture sensitive element can be determined.

It is a block diagram which shows the structure of the humidity measuring apparatus which concerns on Embodiment 1 of this invention. FIGS. 2A and 2B are plan views of the entire humidity measuring device, and FIG. 2C is a side view of the humidity sensor. FIG. 3 is a block diagram illustrating a configuration of a deterioration diagnosis processing unit according to the first embodiment. 6 is an explanatory diagram for explaining deterioration diagnosis processing by a deterioration diagnosis processing unit according to Embodiment 1; FIG. 3 is a flowchart illustrating an operation of a deterioration diagnosis processing unit according to the first embodiment. It is explanatory drawing explaining the deterioration determination process of the humidity measuring device which concerns on Embodiment 2 of this invention. 6 is a flowchart showing the operation of the deterioration diagnosis processing unit of the second embodiment, which is a subroutine of step ST7 shown in FIG.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a humidity measuring apparatus according to Embodiment 1 of the present invention. The humidity measuring apparatus shown in FIG. 1 includes humidity sensors 1a and 1b that are installed in a measurement environment atmosphere and measure relative humidity, and perform deterioration diagnosis of the humidity sensors 1a and 1b. 2A and 2B are plan views showing a specific configuration example of the humidity measuring device. Even if the humidity measuring apparatus is configured to include the humidity sensors 1a and 1b integrally with the apparatus main body as shown in FIG. 2A, the apparatus main body and the humidity sensors 1a and 1b as shown in FIG. May be connected by a cable line. Note that. In FIGS. 2A and 2B, the humidity sensors 1a and 1b are covered with a cover.

  The humidity sensors 1a and 1b heat-clean the humidity elements (humidity sensing elements) 2a and 2b that measure relative humidity, the temperature elements (temperature sensing elements) 3a and 3b that measure temperature, and the humidity elements 2a and 2b. Heaters (heating means) 4a and 4b. FIG. 2C is a side view showing an example of the humidity sensor 1a. In the humidity sensor 1a shown in FIG. 2C, the temperature element 3a and the heater 4a are integrally configured using a platinum resistance element or the like, but may be separate. The temperature element 3a and the heater 4a are fixed to the surface opposite to the moisture sensitive surface 31 of the humidity element 2a with an adhesive or the like. The humidity element 2a is connected to the humidity input converter 5 via a lead wire 32 and outputs a humidity detection signal. Further, the temperature element 3a and the heater 4a are connected to the temperature input conversion unit 6 and the heater driving unit 11 by lead wires 33 to output a temperature detection signal and receive a control signal for driving the heater. Although illustration is omitted, the humidity sensor 1b has the same configuration as the humidity sensor 1a.

  The humidity input conversion unit 5 converts the humidity detection signals output from the humidity elements 2a and 2b into voltage signals, and the temperature input conversion unit 6 converts the temperature detection signals output from the temperature elements 3a and 3b into voltage signals, The input switching unit 7 selectively outputs any voltage signal to the A / D conversion unit 8. The A / D conversion unit 8 converts a voltage signal that is an analog signal into a digital signal and outputs the digital signal to the control unit 9. The control unit 9 performs predetermined conversion using digital signals of humidity and temperature to obtain a humidity measurement value (hereinafter, simply referred to as humidity indicates relative humidity) and a temperature measurement value. In the present embodiment, the A / D conversion unit 8 is configured to switch the input by the input switching unit 7 in order to share the humidity input signal and the temperature input signal. You may comprise so that a / D conversion part may be provided.

  The control unit 9 includes a memory that stores a program describing the contents of humidity measurement and deterioration diagnosis of the humidity measuring device, and a CPU that reads the program from the memory and executes the program. The control unit 9 displays the humidity measurement value and the temperature measurement value input from the A / D conversion unit 8 on the display unit 12 and outputs data from the output unit 13. In addition, the control unit 9 starts and ends humidity measurement, performs heat cleaning, performs deterioration diagnosis, for example, according to setting conditions set by a user operating a setting input unit 14 configured by a switch or the like. Or carry out.

  The timer unit 10 drives the heater driving unit 11 to heat the heater 4 for a predetermined time instructed by the control unit 9.

Next, the deterioration diagnosis process of the humidity measuring device according to the first embodiment will be described. In the following description, when it is not necessary to distinguish between the humidity sensors 1a and 1b, they are referred to as humidity sensors 1. Similarly, humidity elements 2a and 2b are referred to as humidity element 2, temperature elements 3a and 3b are referred to as temperature element 3, and heaters 4a and 4b are referred to as heater 4.
FIG. 3 is a block diagram illustrating a configuration of the deterioration diagnosis processing unit 20 of the humidity measuring apparatus according to the first embodiment. The deterioration diagnosis processing unit 20 according to the first embodiment includes a first dew point calculation unit 21, a second dew point calculation unit 22, and a deterioration determination unit 23, and does not include the heating control unit 24 and the cleaning notification unit 25. To do. Details of the heating control unit 24 and the cleaning notification unit 25 will be described in a second embodiment to be described later. The deterioration diagnosis processing unit 20 corresponds to the control unit 9 shown in FIG. 1, and functions as each part inside the deterioration diagnosis processing unit 20 when the CPU executes a program describing the processing contents of deterioration diagnosis described later.

  FIG. 4 is an explanatory diagram for explaining the deterioration diagnosis process of the deterioration diagnosis processing unit 20 according to the first embodiment. In the air diagram shown in FIG. 4, the vertical axis indicates the water vapor pressure, the horizontal axis indicates the temperature, and the relative humidity is 5%, 7.9%, 10%, 50% and 100% in the air diagram. A water vapor pressure curve is shown. Dew point temperature (also referred to as dew point as appropriate) can be obtained from relative humidity and temperature. If humidification and dehumidification are not performed in an environment where there is no pressure change, the dew point is constant even if the relative humidity or temperature changes. This is well known. For example, at point A before heating at a relative humidity of 50% and a temperature of 25 ° C. in FIG. 4, the dew point is 13.9 ° C. In this state, it is assumed that the humidity element 2 is heated by the heater 4 and the temperature of the humidity element 2 is increased to 60 ° C. At this time, the humidity measurement value measured by the humidity element 2 is 7.9%, and the dew point calculation value should be the same value as 13.9 ° C. before humidifying the humidity element 2 (heating point B1) . This is because the dew point does not change before and after heating the humidity element 2 (that is, the amount of moisture in the air does not change).

In general, the humidity element 2 is easily deteriorated under the influence of the environment, and the humidity measurement value shifts particularly due to adhesion of an organic solvent and a deliquescent material (for example, sulfide). Therefore, the humidity element 2 is more likely to deteriorate than the temperature element 3. From this, when the value of the dew point changes before and after heating, it can be estimated that the cause is not the deterioration of the temperature element 3 but the deterioration of the humidity element 2.
When the humidity element 2 is deteriorated by chemicals or the like and the output is shifted higher, the dew points before and after heating do not match, and the dew point during heating becomes higher than the dew point before heating. For example, when the temperature of the humidity element 2 is increased from 25 ° C. of the pre-heating point A to 60 ° C., the humidity measurement value is shifted to 10% higher than 7.9% due to deterioration. Compared to the dew point, the dew point at point B2 during heating is higher.
Similarly, when the humidity element 2 is deteriorated by chemicals or the like and the output is shifted higher, the dew points before and after heating do not match, and the dew point during heating becomes lower than the dew point before heating. For example, when the temperature of the humidity element 2 is increased from 25 ° C. of the point A before heating to 60 ° C., the humidity measurement value is shifted to 5% lower than 7.9% due to deterioration. Compared to the dew point, the dew point at the point B3 during heating is lowered.

  Thus, by comparing the dew point before heating with the dew point during heating, it can be seen whether the humidity measurement value of the humidity element 2 is high or low, and the deterioration of the humidity element 2 can be determined. In the present embodiment, the pre-heating point A and the heating point B1 (or B2, B3) are simultaneously measured by the humidity sensors 1a and 1b. Then, the first dew point calculating unit 21 calculates the first dew point temperature corresponding to the dew point of the pre-heating point A, and the second dew point temperature corresponding to the dew points of the heating points B1, B2, B3 is set to the second dew point temperature. The dew point calculation unit 22 calculates. Then, the deterioration determining unit 23 compares the first dew point temperature and the second dew point temperature to determine whether the humidity element 2 has deteriorated. Note that the heating in the deterioration diagnosis process is lower in temperature than the heating for the heat cleaning, and therefore the humidity element 2 is not deteriorated as much as the heat cleaning.

  Next, the operation of the deterioration diagnosis processing unit 20 will be described. FIG. 5 is a flowchart showing the operation of the deterioration diagnosis processing unit 20. The deterioration diagnosis process may be started when the control unit 9 receives a start instruction from the user, or may be started periodically by the control unit 9. When the deterioration diagnosis process is started, first, the first dew point calculation unit 21 calculates the humidity measurement value and the temperature measurement value in the measurement atmosphere measured by the humidity sensor 1a (the measurement moisture sensitive element and the temperature sensitive element). Obtain (step ST1). Further, the control unit 9 heats the humidity element 2b to a predetermined temperature (for example, 60 ° C.) by the heater 4b, and the second dew point calculation unit 22 measures the humidity sensor 1b (a non-measurement humidity sensor and a temperature sensor). A humidity measurement value and a temperature measurement value are acquired (step ST2). Either step ST1 or step ST2 may be performed first, or the humidity measuring device includes a humidity input conversion unit 5, a temperature input conversion unit 6, an input switching unit 7 and an A / D conversion unit 8 for each of the humidity sensors 1a and 1b. If so, step ST1 and step ST2 may be performed simultaneously.

  Subsequently, the first dew point calculation unit 21 calculates a first dew point temperature from the humidity measurement value and the temperature measurement value of the humidity sensor 1a acquired in step ST1 (step ST4, first dew point temperature calculation step), The second dew point calculation unit 22 calculates the second dew point temperature from the humidity measurement value and the temperature measurement value of the heating humidity sensor 1b acquired in step ST3 (step ST5, second dew point temperature calculation step). Subsequently, the deterioration determination unit 23 compares the first dew point temperature and the second dew point temperature (step ST6, deterioration determination step). If there is no difference (step ST6 “Yes”), the humidity element 2 is deteriorated. It is determined that the deterioration diagnosis process is not performed. Note that the first dew point temperature and the second dew point temperature may be substantially the same as well as the case where they completely match.

  On the other hand, if there is a difference between the first dew point temperature and the second dew point temperature (step ST6 “No”), the deterioration determination unit 23 indicates that the humidity element 2 has deteriorated in the deterioration determination process of step ST7. The determination result is output to the display unit 12 or the output unit 13. Since the humidity sensors 1a and 1b are placed in the same measurement environment atmosphere, the measured values of the humidity sensors 1a and 1b change in the same way even if the relative humidity and temperature change. The dew point temperature of 2 should be the same. However, when the humidity element 2a is deteriorated by a component in the atmosphere, the required first dew point temperature deviates from a true value. On the other hand, the humidity element 2b has recovered its deterioration state by heating, so that the required second dew point temperature is close to the true value, and the difference between the first dew point temperature and the second dew point temperature is the heating value. This indicates the degree of deterioration of the humidity element 2a that has not been performed. Therefore, it is possible to self-diagnose whether the humidity element 2a that has not been heated has deteriorated to a degree that requires cleaning.

  In the deterioration determination process in step ST7, the deterioration determination unit 23 may determine whether the humidity measurement value of the humidity element 2 is shifted to a high value or a low value, and may be included in the determination result. . Alternatively, the control unit 9 may control the timer unit 10 and the heater driving unit 11 to cause the heater 4 to perform heat cleaning in response to the deterioration determination result.

  If the humidity element to be heated is switched from the humidity element 2b to the humidity element 2a and a series of deterioration diagnosis processes are performed, it is possible to self-diagnose whether the humidity element 2a has deteriorated. Even if the normal measurement of one of the humidity sensors is interrupted and heated for deterioration diagnosis processing, the other humidity sensor can continue normal measurement, so it is continuous without interruption. It is possible to measure humidity.

  As described above, according to the first embodiment, the humidity element 2a, 2b and the temperature element 3a, 3b are installed in the measurement atmosphere, and the two humidity elements 2a, 2b are alternately used for measurement. Or, switching to non-measurement, one measurement humidity element and temperature element measure relative humidity and temperature during the measurement period, and the other non-measurement humidity element and temperature element are the one measurement humidity element and A method for diagnosing deterioration of a humidity sensor including heaters 4a and 4b capable of performing heat cleaning during a temperature element measurement period, in which a first dew point calculation unit 21 of a humidity measurement device includes a measurement humidity element and a temperature A first dew point temperature obtained as a first dew point temperature based on measured values of relative humidity and temperature in the measurement environment atmosphere of the element A dew point obtained by the dew point temperature calculating step and the second dew point calculating unit 22 based on measured values of relative humidity and temperature in the measurement environment atmosphere of the non-measuring humidity element and the temperature element being heated by the heater 4a or the heater 4b. The second dew point temperature calculating step for obtaining the temperature as the second dew point temperature and the deterioration determining unit 23 needs to clean the humidity element for measurement based on the difference between the first dew point temperature and the second dew point temperature. A deterioration determining step for determining whether or not a certain degree of deterioration has occurred is configured. Since the two humidity elements 2 are placed in the same measurement environment atmosphere, the dew point temperature should be the same even if the relative humidity and temperature change, but the measurement humidity element 2 is deteriorated by the components in the atmosphere. While the required first dew point temperature deviates from the true value, the non-measuring humidity element 2 is restored to the degraded state by heating, so the required second dew point temperature becomes the true value. Since the difference between the first dew point temperature and the second dew point temperature indicates the degree of deterioration of the humidity element 2 for measurement, the measurement humidity element 2 has deteriorated to a degree that requires cleaning. Can self-diagnose. Further, it is possible to perform self-degradation diagnosis using the humidity element 2, the temperature element 3 and the heater 4 which are members originally provided in the humidity sensor 1, and an analyzer and other analytical instruments are not required. .

Embodiment 2. FIG.
Also in the present embodiment, a method for diagnosing the deterioration of the humidity sensors 1a and 1b by the humidity measuring device will be described with reference to FIGS. Also in the following description, as in the first embodiment, when it is not necessary to distinguish between the humidity sensors 1a and 1b, the humidity sensors 1 are referred to, and the same applies to each part in the humidity sensor 1.
As described in the first embodiment, the humidity element 2 is easily deteriorated due to the influence of the measurement environment atmosphere, and the humidity measurement value is particularly shifted due to adhesion of an organic solvent and a deliquescent substance. Therefore, in the second embodiment, the nature of this shift is used to determine whether the cause of deterioration of the humidity element 2 is an organic solvent or a deliquescent substance.

When the dew point during heating is higher than the dew point before heating, that is, when the pre-heating point A shown in FIG. Either it was measured low before or it was measured low during heating. Since the relative humidity usually decreases when heated, the relative humidity measurement during heating is performed on the lower humidity side than before heating. Therefore, FIG. 6 shows a graph in which the horizontal axis represents the relative reference humidity and the vertical axis represents the shift amount of the humidity measurement value before and after heating. The tendency of the shift C shown in FIG. 6, that is, the shift amount on the low-humidity side to be larger than that on the high-humidity side, is seen due to deterioration by the organic solvent.
Similarly, when the dew point during heating is lower than the dew point before heating, that is, when the point A3 before heating shown in FIG. The value was either measured high before heating or measured low during heating. The shift D shown in FIG. 6, that is, the tendency for the shift amount on the low-humidity side to be smaller than that on the high-humidity side is seen due to deterioration due to adhesion of deliquescent substances.

  When the organic solvent is a cause of deterioration, the humidity element 2 can be recovered by heat cleaning. On the other hand, when the deliquescent substance is the cause, the humidity element 2 cannot be completely recovered even if heat cleaning is performed, and cleaning and cleaning are necessary to fully recover.

Thus, when the humidity element 2 deteriorates due to the organic solvent in the measurement environment atmosphere, the humidity measurement value shifts to a lower value. However, the humidity element 2 is heated to calculate the second dew point temperature, so that the organic solvent No effect. Accordingly, the second dew point temperature calculated from the humidity measurement value and the temperature measurement value during heating is higher than the first dew point temperature calculated from the humidity measurement value and the temperature measurement value before heating. Therefore, in the second embodiment, the deterioration determining unit 23 of the deterioration diagnosis processing unit 20 estimates the deterioration factor in this case as an organic solvent.
On the other hand, when the humidity element 2 deteriorates due to the deliquescent substance in the measurement environment atmosphere, the humidity measurement value shifts to a high value. However, since the humidity element 2 is heated, this shift is suppressed to some extent, so that the first dew point The second dew point temperature is lower than the temperature. Therefore, the degradation determination unit 23 estimates the degradation factor in this case as a deliquescent material.

  In addition to the first dew point calculation unit 21, the second dew point calculation unit 22, and the deterioration determination unit 23, the deterioration diagnosis processing unit 20 newly includes a heating control unit 24 and a cleaning notification unit 25 illustrated in FIG. The configuration. The heating control unit 24 controls the timer unit 10 and the heater driving unit 11 according to the determination result output from the deterioration determination unit 23 to heat-clean the humidity element 2 that is determined to have deteriorated in the heater 4. To implement. In addition, the cleaning notification unit 25 needs to perform cleaning cleaning of the humidity element 2 determined to have deteriorated on the display unit 12 or the output unit 13 in accordance with the determination result output by the deterioration determination unit 23. Display or output.

  Next, the operation of the deterioration diagnosis processing unit 20 will be described. FIG. 7 is a flowchart showing the operation of the deterioration diagnosis processing unit 20 of the second embodiment, and is a subroutine of step ST7 in FIG. The humidity measuring apparatus performs the operation up to step ST6 in the same manner as in the first embodiment, and in step ST6, the deterioration determination unit 23 compares the first dew point temperature with the second dew point temperature to obtain the first dew point temperature. When it is determined that there is a difference in the second dew point temperature and deterioration has occurred, the deterioration determination of step ST7-1 to step ST7-8 shown in FIG. 7 is performed.

  The deterioration determination unit 23 compares the first dew point temperature and the second dew point temperature to obtain a relative height difference (step ST7-1, height difference calculation step). Subsequently, when the second dew point temperature is higher than the first dew point temperature, the deterioration determination unit 23 determines that the deterioration is caused by the organic solvent (step ST7-2 “Yes”), and this deterioration is determined by the heat cleaning. Is compared with the first threshold value (step ST7-3, comparison step). The deterioration determining unit 23 performs normal measurement when the second dew point temperature is higher than the first dew point temperature and the relative height difference is larger than the first threshold value. It is determined that the humidity element 2 is deteriorated to the extent that cleaning is necessary due to the organic solvent in the measurement environment atmosphere, and an organic solvent deterioration sign is output to the heating control unit 24 (step ST7-4, deterioration determination step). ).

Assume that during the deterioration diagnosis process, the humidity element 2a performs normal measurement and the humidity element 2b is being heated. In that case, when the heating control unit 24 receives the organic solvent deterioration sign, the heating control unit 24 switches to normal measurement after the heating of the humidity element 2b is finished and the heat is radiated. Subsequently, the heating control unit 24 switches the humidity element 2a performing normal measurement to non-measurement, and controls the timer unit 10 and the heater driving unit 11 to perform heating cleaning (step ST7-5, heating cleaning). Step). By switching the humidity element, it is possible to perform deterioration diagnosis processing and heat cleaning while continuously performing normal measurement.
If the relative height difference is less than the first threshold value in step ST7-3, the deterioration determination unit 23 determines that the deterioration is not necessary to be heat-cleaned, and a series of deterioration diagnosis processes are performed. finish.

  On the other hand, when the second dew point temperature is lower than the first dew point temperature, it is determined that the deterioration is caused by the deliquescent substance (“No” in step ST7-3), and the deterioration determination unit 23 continues this deterioration. In order to determine whether or not cleaning / cleaning is necessary, the relative height difference is compared with the second threshold value (step ST7-6, comparison step). The deterioration determining unit 23 determines that the humidity element 2 is in the measurement environment when the second dew point temperature is lower than the first dew point temperature and the relative height difference is larger than the second threshold value. It is determined that the deliquescent material in the atmosphere has deteriorated to the extent that cleaning is necessary, and a deliquescent material deterioration sign is output to the cleaning notification unit 25 (step ST7-7, deterioration determination step).

During the deterioration diagnosis process, it is assumed that the humidity element 2a performs normal measurement and the humidity element 2b is being heated as described above. In that case, when receiving the deliquescent substance deterioration sign, the cleaning notification unit 25 displays on the display unit 12 that cleaning cleaning is performed, or causes the output unit 13 to output data indicating cleaning cleaning. The necessity of cleaning for the humidity element 2a performing normal measurement is notified (step ST7-8, cleaning notification step). At this time, the cleaning notification unit 25 switches to normal measurement after the heating of the humidity element 2b is finished and radiates heat, and after switching the humidity element 2a performing normal measurement to non-measurement, The necessity of cleaning for the humidity element 2a may be notified. By switching the humidity element, it is possible to perform deterioration diagnosis processing and cleaning / cleaning while continuously performing normal measurement.
If the relative height difference is less than the second threshold value in step ST7-6, the deterioration determination unit 23 determines that the deterioration is not necessary to be cleaned and a series of deterioration diagnosis processes are performed. finish.

  As described above, according to the second embodiment, when the humidity element 2 is deteriorated by the organic solvent in the measurement environment atmosphere, the humidity measurement value is shifted to a lower value, but the humidity element 2 is heated by the heater 4. Since the influence of the organic solvent is eliminated, the second dew point temperature during heating calculated by the second dew point calculation unit 22 is more than the first dew point temperature during normal measurement calculated by the first dew point calculation unit 21. Get higher. Utilizing this, the deterioration determining unit 23 determines that the second dew point temperature is higher than the first dew point temperature, and the relative value of the first dew point temperature and the second dew point temperature is higher than the first threshold value. When the target height difference is larger, it is determined that the organic solvent in the measurement environment atmosphere determines that the humidity element 2 during normal measurement has deteriorated to a degree that requires cleaning. For this reason, it can be estimated that the factor that degrades the humidity element 2 of the humidity sensor 1 is the organic solvent in the measurement environment atmosphere.

  In addition, after the deterioration determination unit 23 determines that the humidity element 2 of the humidity sensor 1 during normal measurement has deteriorated to the extent that cleaning is required due to the organic solvent in the measurement environment atmosphere, the heating control unit 24 Since the humidity sensor heated for the deterioration diagnosis is switched to normal measurement and the humidity sensor in the normal measurement determined to have deteriorated is heated and cleaned by the heater 4, an appropriate time Suitable cleaning can be performed.

  In addition, when the humidity element 2 deteriorates due to a deliquescent substance in the measurement environment atmosphere, the humidity measurement value shifts to a higher value, but the influence of the deliquescent substance is suppressed to some extent by heating the humidity element 2 to the heater 4. The second dew point temperature during heating calculated by the second dew point calculation unit 22 is lower than the first dew point temperature during normal measurement calculated by the first dew point calculation unit 21. By utilizing this, the degradation determination unit 23 determines whether the relative height difference between the first dew point temperature and the second dew point temperature is larger than the second threshold value by deliquescent substances in the measurement environment atmosphere. The humidity element 2 is determined to have a degree of deterioration that requires cleaning. For this reason, it can be estimated that the factor which degrades the humidity element 2 of the humidity sensor 1 is a deliquescent substance in the measurement environment atmosphere.

  In addition, after the deterioration determination unit 23 determines that the humidity element 2 of the humidity sensor 1 during normal measurement has deteriorated to the extent that cleaning is required due to the deliquescent material in the measurement environment atmosphere, the cleaning notification unit 25 However, the humidity sensor that has been heated for deterioration diagnosis is switched to normal measurement, and the humidity sensor that has been determined to have deteriorated is recovered from deterioration more effectively than heat cleaning. Since it is informed to perform cleaning cleaning that can be performed, appropriate cleaning can be performed at an appropriate time.

In the first and second embodiments, the humidity sensor 1a and the humidity sensor 1b are switched between normal measurement and deterioration diagnosis heating (non-measurement), but either one of the humidity sensors is dedicated to normal measurement ( It may be configured for measurement), and the other may be configured exclusively for deterioration diagnosis (for non-measurement). For example, when the humidity sensor 1a is dedicated to normal measurement, the humidity sensor 1a is configured to include the humidity element 2a, the temperature element 3a, and the heater 4a, and the other humidity sensor 1b dedicated to deterioration diagnosis includes the humidity element 2b and the temperature. Only the element 3b is provided, and the heater 4b is not necessary.
When the humidity measurement device starts the deterioration diagnosis process, the humidity sensor 1a dedicated for normal measurement interrupts the normal measurement and heats the heater 4a, and the second dew point temperature is calculated from the measured relative humidity and the measured temperature. Is calculated. The humidity measuring device also acquires the measured value of the humidity sensor 1b dedicated to the deterioration diagnosis at substantially the same time as acquiring the measured value of the humidity sensor 1a during heating, and calculates the first dew point temperature from the measured value of the humidity sensor 1b. If the first dew point temperature and the second dew point temperature do not match, the humidity sensor 1b dedicated for deterioration diagnosis that is not heated is deviated from the true value. Accordingly, the humidity sensor 1a dedicated for normal measurement in the same environmental atmosphere as the humidity sensor 1b is also heated for the deterioration diagnosis, so that it is estimated that the same deterioration has occurred even though some deterioration has been recovered. it can. For this reason, the deterioration diagnosis of the humidity sensor 1a dedicated to normal measurement can be performed by the same method as in the first and second embodiments. In addition, if the cause of deterioration is an organic solvent, the humidity sensor 1a is cleaned by heating the humidity sensor 1a dedicated to normal measurement. If the cause of deterioration is a deliquescent substance, the humidity sensor 1a dedicated to normal measurement needs to be cleaned. You may comprise so that it may notify.

  In the first and second embodiments, the first and second dew point temperatures are compared to determine the deterioration. However, instead of the dew point temperature, the first and second water vapor pressures are calculated and compared. By doing so, the deterioration determination may be performed. This is because the dew point temperature and the water vapor pressure are in a one-to-one relationship. Even in this configuration, the same effects as those of the first and second embodiments can be obtained.

1a, 1b Humidity sensor 2a, 2b Humidity element (humidity sensitive element)
3a, 3b Temperature element (temperature sensor)
4a, 4b Heater (heating means)
DESCRIPTION OF SYMBOLS 5 Humidity input conversion part 6 Temperature input conversion part 7 Input switching part 8 A / D conversion part 9 Control part 10 Timer part 11 Heater drive part 12 Display part 13 Output part 14 Setting input part 20 Degradation diagnostic process part 21 1st dew point Calculation unit 22 Second dew point calculation unit 23 Degradation determination unit 24 Heating control unit 25 Cleaning notification unit 31 Moisture sensitive layer 32 Lead wire 33 Lead wire A Pre-heating point B1, B2, B3 Heating point C, D shift

Claims (12)

One humidity sensing element for measurement, which is installed in a measurement environment atmosphere, has two moisture sensing elements and two temperature sensing elements, and alternately switches the two moisture sensing elements for measurement or non-measurement. And the temperature sensing element measures relative humidity and temperature during the measurement period, and the other non-measurement humidity sensing element and temperature sensing element are heated and cleaned during the measurement period of the one measurement moisture sensing element and temperature sensing element. A method for diagnosing deterioration of a humidity sensor comprising a heating means capable of performing
A first dew point temperature calculating step for obtaining, as a first dew point temperature, a dew point temperature obtained based on measured values of relative humidity and temperature in the measurement environment atmosphere of the measurement moisture sensitive element and the temperature sensitive element;
A second dew point temperature obtained as a second dew point temperature is a dew point temperature obtained based on measured values of relative humidity and temperature in the measurement environment atmosphere of the non-measuring moisture sensing element and the temperature sensing element during heating by the heating means. A calculation step;
Deterioration of the humidity sensor comprising a deterioration determination step for determining whether or not the measurement moisture sensitive element has deteriorated to a degree that requires cleaning based on the difference between the first dew point temperature and the second dew point temperature. Diagnosis method. In the degradation diagnosis method of the humidity sensor according to claim 1,
A height difference calculating step for comparing the first dew point temperature obtained in the first dew point temperature calculating step and the second dew point temperature obtained in the second dew point temperature calculating step to obtain a relative height difference;
A comparison step of comparing the relative height difference with a first threshold,
In the deterioration determination step, when the second dew point temperature is higher than the first dew point temperature and the relative height difference is larger than the first threshold value, A method for diagnosing deterioration of a humidity sensor, characterized in that it is determined that the organic moisture has deteriorated to a degree that requires cleaning of the measurement moisture sensitive element. In the humidity sensor deterioration diagnosis method according to claim 2,
If it is determined in the deterioration determination step that the measurement moisture-sensitive element has deteriorated to a degree that requires cleaning with an organic solvent, the measurement moisture-sensitive element is switched to non-measurement and heated by the heating means. And a heating and cleaning step of continuing the measurement by switching the other non-measuring moisture-sensitive element for measurement, and a method for diagnosing deterioration of a humidity sensor. In the degradation diagnosis method of the humidity sensor according to claim 1,
A height difference calculating step for comparing the first dew point temperature obtained in the first dew point temperature calculating step and the second dew point temperature obtained in the second dew point temperature calculating step to obtain a relative height difference;
A comparison step of comparing the relative height difference with a second threshold,
In the deterioration determination step, when the second dew point temperature is lower than the first dew point temperature and the relative height difference is larger than the second threshold value, A method for diagnosing deterioration of a humidity sensor, characterized in that it is determined that a dehumidifying element for measurement has deteriorated to a degree that requires cleaning. In the humidity sensor degradation diagnosis method according to claim 4,
When it is determined in the deterioration determination step that the measurement moisture sensitive element has deteriorated to the extent that it needs cleaning due to deliquescent substances, the measurement moisture sensitive element is switched to non-measurement and cleaning is performed. A method for diagnosing deterioration of a humidity sensor, comprising: a cleaning notification step that performs notification by switching the other non-measurement moisture-sensitive element for measurement and continuing measurement. Installed in the measurement environment atmosphere,
A humidity sensing element and a temperature sensing element for measuring relative humidity and temperature;
Heating means for performing heating cleaning of the measurement moisture sensitive element during a non-measurement period of the measurement moisture sensitive element and the temperature sensitive element;
A humidity sensor deterioration diagnosis method comprising a non-measurement humidity sensor and a temperature sensor for measuring relative humidity and temperature during a non-measurement period of the measurement moisture sensor and the temperature sensor,
A first dew point temperature calculating step for obtaining a dew point temperature obtained as a first dew point temperature based on measured values of relative humidity and temperature in the measurement environment atmosphere of the non-measuring moisture sensing element and the temperature sensing element;
A second dew point temperature calculation that obtains a dew point temperature obtained as a second dew point temperature based on measured values of relative humidity and temperature in the measurement environment atmosphere of the measurement moisture sensing element and the temperature sensing element during heating by the heating means. Steps,
Deterioration of the humidity sensor comprising a deterioration determination step for determining whether or not the measurement moisture sensitive element has deteriorated to a degree that requires cleaning based on the difference between the first dew point temperature and the second dew point temperature. Diagnosis method. In the degradation diagnosis method of the humidity sensor according to claim 6,
A height difference calculating step for comparing the first dew point temperature obtained in the first dew point temperature calculating step and the second dew point temperature obtained in the second dew point temperature calculating step to obtain a relative height difference;
A comparison step of comparing the relative height difference with a first threshold,
In the deterioration determination step, when the second dew point temperature is higher than the first dew point temperature and the relative height difference is larger than the first threshold value, A method for diagnosing deterioration of a humidity sensor, characterized in that it is determined that the organic moisture has deteriorated to a degree that requires cleaning of the measurement moisture sensitive element. In the humidity sensor degradation diagnosis method according to claim 7,
A humidity sensor comprising a heating cleaning step for heating and cleaning by a heating means when it is determined in the deterioration determining step that the measuring moisture-sensitive element has deteriorated to an extent necessary for cleaning with an organic solvent. Deterioration diagnosis method of In the degradation diagnosis method of the humidity sensor according to claim 6,
A height difference calculating step for comparing the first dew point temperature obtained in the first dew point temperature calculating step and the second dew point temperature obtained in the second dew point temperature calculating step to obtain a relative height difference;
A comparison step of comparing the relative height difference with a second threshold,
In the deterioration determination step, when the second dew point temperature is lower than the first dew point temperature and the relative height difference is larger than the second threshold value, A method for diagnosing deterioration of a humidity sensor, characterized in that it is determined that a dehumidifying element for measurement has deteriorated to a degree that requires cleaning. The deterioration diagnosis method for a humidity sensor according to claim 9,
In the deterioration determination step, when it is determined that the measurement moisture-sensitive element has deteriorated to a degree that requires cleaning due to a deliquescent substance, the cleaning notification step is provided to notify that cleaning cleaning is performed. Deterioration diagnosis method for humidity sensor. The method for diagnosing deterioration of a humidity sensor according to any one of claims 1 to 5,
Instead of the first dew point temperature, the moisture pressure for measurement and the water vapor pressure obtained based on the measured values of the relative humidity and temperature in the measurement environment atmosphere of the temperature sensitive element are used, and instead of the second dew point temperature. A humidity sensor deterioration diagnosis method characterized by using a moisture pressure for non-measurement during heating by a heating means and a water vapor pressure obtained based on measured values of relative humidity and temperature in a measurement environment atmosphere of the temperature sensitive element. The humidity sensor deterioration diagnosis method according to any one of claims 6 to 10,
In place of the first dew point temperature, the moisture pressure obtained based on the measured values of the relative humidity and temperature in the measurement environment atmosphere of the non-measuring moisture sensing element and the temperature sensing element is used, and instead of the second dew point temperature. In addition, a humidity sensor deterioration diagnosis method using a humidity sensor for measurement during heating by a heating means and a water vapor pressure obtained based on measured values of relative humidity and temperature in a measurement environment atmosphere of the temperature sensitive element.

Images