JP2012132782A - Sensitivity coefficient calculation device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately calculate a sensitivity coefficient by a simple method.SOLUTION: An alcohol sensor 24A detects physical quantity corresponding to physical quantity related to a concentration of ethanol gas and physical quantity related to humidity, and outputs a detection value. A humidity sensor 24B detects and outputs the physical quantity related to the humidity. A temperature sensor 24D detects and outputs a temperature. A data storage part 44 stores a plurality of data sets indicating a combination of the detection value of the alcohol sensor 24A, the detection value of the humidity sensor 24B and the detection value of the temperature sensor 24D. A data retrieval part 46 retrieves the latest data sets whose temperature are same and a difference of humidity between them is more than the predetermined value. A sensitivity coefficient calculation part 48 calculates a sensitivity coefficient of the alcohol sensor 24A based on the retrieved data sets.

Description

  The present invention relates to a sensitivity coefficient calculation apparatus and program, and more particularly, to a sensitivity coefficient calculation apparatus and program for calculating a sensitivity coefficient of a gas detection means for detecting a detection target gas such as ethanol contained in human breath.

  Conventionally, in a gas sensor, sensitivity to gas (corresponding to the slope of the calibration curve) and baseline (corresponding to the intercept of the calibration curve) are determined in advance as quantitative coefficients, and the target gas is quantified using these coefficients. If the quantitative coefficient of the sensor changes due to a change in sensor characteristics over time, a quantitative error occurs, and maintenance for recalibration in a certain period is required. How long this period can be made is practically important.

  Therefore, the sensor output when the breath of a non-drinking subject is blown is taken as the normal output, and the average value (initial concentration average value) of the sensor output value is measured and stored in units of 100 measurements. Similarly, there has been proposed an alcohol detection system that obtains an average value every 100 times, compares it with an initial concentration average value, and performs sensitivity correction so that the sensor output value becomes the initial concentration average value (for example, patents). Reference 1).

  In addition, a gas detection device that corrects the gas sensitivity (inclination parameter of a calibration curve) of an alcohol sensor has been proposed (see, for example, Patent Document 2). In this gas detector, the humidity sensitivity of the alcohol sensor is used to calculate the gas sensitivity from the response of the spray sensor when not drinking, and correct the deterioration over time.

JP 2005-157599 A JP 2010-175321 A

  However, in the alcohol detection system of Patent Document 1, the average value of the non-drinking breath at the initial stage and the test is compared, the concentration range considered not to be drunk is unclear, and when not drunk Sensor output for exhalation is affected by environmental humidity and unspecified substances such as food and drink ingested by the subject prior to measurement.Accordingly, even if the sensor sensitivity is corrected with the average value, sufficient accuracy is obtained. There is a problem that it is not possible. Further, since the average values of about 100 times are compared, there is a problem that appropriate correction cannot be made when the sensor characteristics change suddenly.

  Moreover, although the gas detection apparatus of patent document 2 utilizes the humidity response at the time of exhalation, even if it is non-drinking, the influence of the substance derived from food and drink other than water vapor contained in exhalation Therefore, there is a problem that the accuracy of sensitivity correction may deteriorate.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a sensitivity coefficient calculation apparatus capable of calculating a sensitivity coefficient with a simple method with high accuracy.

  In order to achieve the above object, the sensitivity coefficient calculation apparatus of the present invention is sensitive to the detection target gas contained in the detection target gas and the humidity of the detection target gas, and the concentration of the detection target gas. Gas detection means for detecting a physical quantity corresponding to the physical quantity and a physical quantity corresponding to the humidity and outputting a detection value; and a humidity detection means for detecting and outputting a physical quantity related to the humidity of the gas to be detected. A temperature detection means for detecting and outputting the temperature of the gas to be detected; and a data set representing a combination of the detection value of the gas detection means, the detection value of the humidity detection means, and the detection value of the temperature detection means Based on a plurality of storage means and a plurality of data sets corresponding to detection values of the temperature detection means among the plurality of data sets stored in the storage means, the gas detection means It is configured to include the sensitivity coefficient calculating means for calculating a sensitivity coefficient, a.

  The program according to the present invention is sensitive to the detection target gas contained in the detection target gas and the humidity of the detection target gas, and is related to the physical quantity related to the concentration of the detection target gas and the humidity. A detection value of a gas detection means that detects a physical quantity corresponding to the physical quantity and outputs a detection value; a detection value of a humidity detection means that detects and outputs a physical quantity related to the humidity of the gas to be detected; and A computer including storage means storing a plurality of data sets representing combinations of detection values of temperature detection means for detecting and outputting the temperature of the gas, the temperature detection among the plurality of data sets stored in the storage means A program for functioning as a sensitivity coefficient calculating means for calculating a sensitivity coefficient of the gas detecting means based on a plurality of data sets corresponding to the detected values of the means A.

  According to the present invention, the gas detection means detects a physical quantity associated with the concentration of the detection target gas and a physical quantity associated with the humidity, and outputs a detection value. A physical quantity related to the humidity of the gas to be detected is detected and output by the humidity detecting means. The temperature detection means detects and outputs the temperature of the gas to be detected. A plurality of data sets representing combinations of detection values of the gas detection means, detection values of the humidity detection means, and detection values of the temperature detection means are stored in the storage means.

  Then, the sensitivity coefficient calculation unit calculates the sensitivity coefficient of the gas detection unit based on a plurality of data sets corresponding to the detection values of the temperature detection unit among the plurality of data sets stored in the storage unit. To do.

  Thus, among the plurality of data sets representing the combination of the detection value of the gas detection means, the detection value of the humidity detection means, and the detection value of the temperature detection means, the plurality of data sets corresponding to the detection values of the temperature detection means Based on the calculation of the sensitivity coefficient of the gas detection means, the sensitivity coefficient can be accurately calculated by a simple method.

  The sensitivity coefficient calculation unit according to the present invention includes a plurality of pieces of data corresponding to detection values of the temperature detection unit and different detection values of the humidity detection unit among the plurality of data sets stored in the storage unit. Based on the set, the sensitivity coefficient of the gas detection means can be calculated. Thereby, the sensitivity coefficient of the gas detection means can be calculated with higher accuracy using a plurality of data sets having different detection values of the humidity detection means.

  Further, the sensitivity coefficient calculating means according to the present invention is such that the detected value of the temperature detecting means corresponds to the difference between the detected values of the humidity detecting means among the plurality of data sets stored in the storing means. The sensitivity coefficient of the gas detection means can be calculated based on a plurality of data sets that are equal to or greater than a predetermined value. As a result, the sensitivity coefficient of the gas detection means can be calculated with higher accuracy by using a plurality of data sets in which the difference between the detection values of the humidity detection means is a predetermined value or more.

  The sensitivity coefficient calculation means according to the present invention can calculate the sensitivity coefficient of the gas detection means every predetermined period. Thereby, the sensitivity coefficient of the gas detection means can be calculated corresponding to the deterioration with time.

  The gas detection unit according to the present invention is installed in a room, the humidity detection unit is installed in the room, the temperature detection unit is installed in the room, and the storage unit is free of a person in the room. It is possible to store a plurality of data sets representing combinations of the detected value of the gas detecting means, the detected value of the humidity detecting means, and the detected value of the temperature detecting means. Thereby, the sensitivity coefficient of the gas detection means provided in the room can be calculated with high accuracy.

  In addition, the above-described room can be a vehicle interior, and the person can be a passenger. Thereby, the sensitivity coefficient of the gas detection means provided in the passenger compartment can be calculated with high accuracy.

  The sensitivity coefficient calculation means according to the present invention is a plurality of data sets stored in the storage means, the detection values of the temperature detection means corresponding to the data sets detected within a predetermined period. Based on this, the sensitivity coefficient of the gas detection means can be calculated. Thereby, the sensitivity coefficient of the gas detection means can be calculated with higher accuracy using a plurality of data sets detected within a predetermined period.

  The sensitivity coefficient calculation means according to the present invention calculates the sensitivity coefficient by the following equation (I) based on the first data set and the second data set corresponding to the detection values of the temperature detection means. Can do.

α = (ln (G ₁ ) −ln (G ₂ )) / b · (ln [Humi ₁ ] −ln [Humi ₂ ])
... (I)

However, G ₁ is the detected value of the gas detector of the first data set, G ₂ is the detected value of the gas detector of the second data set, humi ₁ from the detection value of the humidity detecting means of the first data set The physical quantity related to the required humidity, Humi ₂ is the physical quantity related to the humidity determined from the detection value of the humidity detecting means of the second data set, and b is a constant.

  The sensitivity coefficient calculation apparatus according to the present invention uses the product of the physical quantity related to the concentration of the detection target gas and the first coefficient corresponding to the sensitivity characteristic, and the physical quantity and sensitivity related to the humidity as the detection value of the gas detection means. The sum of the product with the second coefficient corresponding to the characteristic and the sensitivity coefficient that corrects the first coefficient and the second coefficient according to the change of the sensitivity characteristic are used to express the humidity coefficient. The apparatus may further include a concentration calculation means for calculating the concentration of the detection target gas using a physical quantity related to the detected humidity. Accordingly, the concentration of the detection target gas can be calculated with high accuracy using the sensitivity coefficient calculated with high accuracy.

  The detection value of the above gas detection means can be expressed by the following equation (II).

ln (G) = α · (a · ln [Gas] + b · ln [Humi]) + c (II)

  Where G is a detection value of the gas detection means, α is the sensitivity coefficient, [Gas] is a physical quantity related to the concentration of the gas to be detected, [Humi] is a physical quantity related to humidity, a is the first coefficient, b Is the second coefficient, and c is a constant.

  The sensitivity coefficient calculation apparatus according to the present invention may further include notification means for notifying warning information when the sensitivity coefficient calculated by the sensitivity coefficient calculation means is a predetermined value or less. This can warn that the gas detection means should be replaced.

  As described above, according to the present invention, it is possible to obtain an effect that the sensitivity coefficient can be accurately calculated by a simple method.

It is the schematic which shows the state which attached the ethanol concentration detection apparatus of this Embodiment to the steering column of a driver's seat. It is the schematic which shows this Embodiment. It is a block diagram which shows schematic structure of the ethanol concentration detection apparatus of this Embodiment. It is a diagram which shows the relationship between ethanol gas concentration and the detected value of an alcohol sensor. It is a diagram which shows the relationship between temperature and the detected value of an alcohol sensor. It is a flowchart which shows the content of the sensitivity coefficient in the ethanol concentration detection apparatus of this Embodiment, and the ethanol concentration calculation processing routine.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, a case where the present invention is applied to an ethanol concentration detection device that detects the concentration of ethanol, which is a kind of alcohol, from the breath of a driver will be described as an example.

  As shown in FIG. 1, the ethanol concentration detection device 10 according to the present embodiment is attached to a steering column 12 provided in a driver's seat at a position where the driver's breath can reach. The ethanol concentration detection device 10 includes an elongate cylindrical exhalation introduction tube 20 in which a suction port 20A having an enlarged diameter is formed at the tip, and a sensor group 24 is attached to the inside of the exhalation introduction tube 20 inside. ing.

  As shown in FIG. 2, a suction fan 22 that is driven to suck the breath of the driver from the suction port 20 </ b> A is provided inside the breath introduction tube 20 and on the suction port 20 </ b> A side from the sensor group 24. .

  The sensor group 24 includes an alcohol sensor 24A, a humidity sensor 24B, an oxygen sensor 24C, and a temperature sensor 24D that are attached to the inside of the middle part of the exhalation introduction tube 20.

  The alcohol sensor 24 </ b> A is a sensor that detects ethanol gas contained in the gas flowing in the breath introduction pipe 20, and for example, an oxide semiconductor gas sensor can be used. The alcohol sensor 24 </ b> A outputs a detection signal having a higher level as the concentration of ethanol gas contained in the gas flowing in the exhalation introduction tube 20 becomes higher, and the ethanol sensor contained in the gas flowing in the exhalation introduction tube 20. A detection signal with a low level is output as the density decreases. In addition to the ethanol gas, the alcohol sensor 24A has sensitivity to the humidity of the gas flowing in the exhalation introduction tube 20.

  The humidity sensor 24B is a sensor that detects the humidity of the gas represented by the concentration of water vapor in the gas flowing in the exhalation-introducing pipe 20, and for example, a capacitive humidity sensor can be used. The humidity sensor 24B outputs a detection signal having a higher level as the humidity of the gas flowing in the exhalation introduction tube 20 becomes higher, and outputs a detection signal having a lower level as the humidity of the gas flowing in the exhalation introduction tube 20 becomes lower. Output.

  The oxygen sensor 24 </ b> C is a sensor that detects oxygen contained in the gas flowing through the exhalation introduction tube 20. The oxygen sensor 24C outputs a detection signal having a higher level as the concentration of oxygen contained in the gas flowing in the exhalation introduction tube 20 becomes higher, and the concentration of oxygen contained in the gas flowing in the exhalation introduction tube 20 is reduced. A detection signal with a low level is output as the level decreases.

  The temperature sensor 24D is a sensor that detects the temperature of the gas flowing in the exhalation-introducing tube 20, and for example, a thermistor-type temperature sensor can be used. The temperature sensor 24D outputs a detection signal having a higher level as the temperature of the gas flowing in the exhalation introduction tube 20 becomes higher, and outputs a detection signal having a lower level as the temperature of the gas flowing in the exhalation introduction tube 20 becomes lower. Output.

  According to the present embodiment, when the suction fan 22 is driven, the exhaled air exhaled from the driver is sucked into the exhalation introduction tube 20 from the suction port 20A of the exhalation introduction tube 20, and the exhalation is mixed with the air. As a result, the sensor group 24 is arbitrarily diluted and reaches the sensor group 24 at a constant flow rate. The exhaled breath comes into contact with the sensor group 24 and is then discharged out of the exhalation introducing tube 20.

  When the exhaled breath comes into contact with the alcohol sensor 24A and the humidity sensor 24B, the alcohol sensor 24A detects a detection value related to the concentration and humidity of ethanol gas in the gas containing exhaled gas, and the humidity sensor 24B detects the gas containing exhaled gas. The detected value related to the humidity of is detected. Based on the detection values detected by the alcohol sensor 24A and the humidity sensor 24B, the concentration of ethanol gas as the detection target gas in the expiration is detected.

  Further, when the exhaled breath comes into contact with the oxygen sensor 24C, a detection value related to the concentration of oxygen in the gas containing the exhaled breath is detected by the oxygen sensor 24C.

  As shown in FIG. 3, the ethanol concentration detection apparatus 10 is connected to a display unit 26 such as an alcohol sensor 24A, a humidity sensor 24B, an oxygen sensor 24C, a temperature sensor 24D, and a liquid crystal display, and detects the concentration of ethanol gas. An ethanol concentration detector 30 is provided.

  The ethanol concentration detector 30 is connected to a boarding sensor 28 that detects whether or not the user is on the board. The boarding sensor 28 is configured using, for example, a seat sensor, a human sensor, a pyroelectric sensor, or the like.

  The ethanol concentration detector 30 is a CPU that controls the ethanol concentration detector 10 as a whole, a ROM as a storage medium that stores various programs such as a program for executing a processing routine described later, and temporarily stores data as a work area. It can be constituted by a microcomputer including a RAM to be connected and a bus connecting them.

  The ethanol concentration detector 30 is based on a data acquisition unit 32 that acquires the detection values of the alcohol sensor 24A, the humidity sensor 24B, the oxygen sensor 24C, the temperature sensor 24D, and the ride sensor 28, and the detection result of the ride sensor 28. A boarding determination unit 34 that determines whether or not the vehicle is on board, and an expiration determination unit 36 that determines whether or not exhalation is input based on the detection value of the oxygen sensor 24C when it is determined that the vehicle is on board. When it is determined that exhaled air is input, the gas concentration calculating unit 38 calculates the concentration of ethanol gas in the exhalation based on the detection values of the alcohol sensor 24A and the humidity sensor 24B, and the gas concentration calculating unit 38 A display control unit 40 that controls to display the calculation result on the display unit 26 is provided.

  Here, the principle of calculating the sensitivity coefficient of the alcohol sensor 24A in the ethanol concentration detection apparatus 10 of the present embodiment will be described.

  Like the oxide semiconductor gas sensor, the value ln (G) obtained by logarithmically converting the detection value G of the alcohol sensor 24A whose detection value changes depending on humidity in addition to the concentration of the ethanol gas that is the detection target gas, and the ethanol concentration [Gas]. The relationship with logarithmically converted value ln [Gas] is as shown in FIG. As shown in FIG. 4, a value ln (G) obtained by logarithmically converting the detection value G of the alcohol sensor 24A indicates a value corresponding to absolute humidity when the concentration of ethanol gas is a constant value. When this ln (G) is expressed by a logarithmically converted value of the water vapor concentration [Humi], which is a physical quantity related to the ethanol concentration [Gas] and humidity, equation (1) is obtained.

ln (G) = a · ln [Gas] + b · ln [Humi] + c (1)

  However, a is a quantitative coefficient related to the sensitivity of the alcohol sensor 24A to ethanol, b is a quantitative coefficient related to the sensitivity of the alcohol sensor 24A to humidity, and c is a constant. The quantitative coefficients a and b and the constant c are values representing the sensitivity characteristics of the alcohol sensor 24A, and for at least four combinations of ethanol concentration 2 and humidity 2 levels with respect to a gas having a known ethanol concentration and humidity. This is a value calculated by measuring the detection value of the alcohol sensor 24A.

  The sensitivity of the alcohol sensor 24A varies depending on the use state and use period. Normally, the sensitivity of the alcohol sensor 24A with respect to ethanol (quantitative coefficient a in the above equation (1)) and the sensitivity with respect to humidity (quantitative coefficient b in the above equation (1)) change in the same way. It can be assumed that a and b in the equation change at the same ratio. Therefore, the above equation (1) is expressed as the following equation (2) using the sensitivity coefficient α for correcting the sensitivity deterioration of the alcohol sensor 24A.

ln (G) = α · (a · ln [Gas] + b · ln [Humi]) + c (2)

  Here, the initial value of the sensitivity coefficient α, that is, the sensitivity coefficient α when the alcohol sensor 24A has not deteriorated in sensitivity is 1, and in the initial state, the above equation (2) coincides with the above equation (1).

The output values G ₁ and G ₂ of the alcohol sensor 24A measured in two environments with different humidity conditions are the following ( 3) It is represented by the formula (4).

ln (G ₁ ) = α · (a · ln [Gas ₁ ] + b · ln [Humi ₁ ]) + c (3)
ln (G ₂ ) = α · (a · ln [Gas ₂ ] + b · ln [Humi ₂ ]) + c (4)

  If the above equation (4) is subtracted from the above equation (3), the sensitivity coefficient α can be calculated from the following equation (5).

α = (ln (G ₁ ) −ln (G ₂ )) / ((a · (ln [Gas ₁ ] −ln [Gas ₂ ])
+ B · (ln [Humi ₁ ] −ln [Humi ₂ ])) (5)

Here, let us consider [Gas ₁ ] and [Gas ₂ ]. The alcohol sensor 24A is sensitive to ethanol gas (and its similar gas), which is a detection target gas, and humidity. Therefore, when the ethanol gas has a constant concentration, the sensor output corresponds to humidity.

Moreover, it is considered that the substance that responds to the alcohol sensor 24A when not in a closed environment such as a passenger compartment is a volatile organic compound (VOC). VOC is a generic name for volatile chemical substances, and includes a gas similar to ethanol gas, which is a detection target gas, and therefore responds to the alcohol sensor 24A. As shown in FIG. 5, since VOC is volatile, its concentration level depends on temperature, and can be estimated to be the same concentration level under the same temperature condition in the same vehicle interior. Therefore, ln [Gas ₁ ] = ln [ It is considered that the relationship of Gas ₂ ] is shown. On the other hand, the humidity is considered to change variously in a short time depending on the atmospheric environment such as the weather.

  Therefore, when the ethanol concentration detector 10 is not used (when the concentration of ethanol gas is not detected), the alcohol sensor 24A is periodically operated to detect the concentration of ethanol gas, and at the same time the humidity and temperature are also detected. Detect and store. The data set that is a combination of the detected ethanol gas concentration, humidity, and temperature indicates the ambient air environment of the ethanol concentration detection apparatus 10.

  Further, a recent data set having the same temperature as that of the data set detected this time and a different humidity condition is searched from the data sets stored in the past. Based on the pair of the data set detected this time and the searched data set, the sensitivity coefficient α is calculated by the following equation (6).

α = (ln (G ₁ ) −ln (G ₂ )) / b · (ln [Humi ₁ ] −ln [Humi ₂ ])
... (6)

However, _{G 1} is the detected value of the alcohol sensor 24A in one of the data sets, _{G 2} is the detected value of the alcohol sensor 24A in the other data sets, humi ₁ is the detected value of the humidity sensor 24B in one data set The value obtained based on this, Humi _2, is a value obtained based on the detected value of the humidity sensor 24B in the other data set.

  Here, the water vapor concentration [Humi] is obtained using a detection value detected by the humidity sensor 24B. In the case of an oxide semiconductor type humidity sensor, a value ln (H) obtained by logarithmically converting the detected value H of the humidity sensor 24B is expressed by equation (7).

ln (H) = d · ln [Humi] + e (7)

  However, d is a quantitative coefficient related to the sensitivity of the humidity sensor 24B to humidity, and e is a constant.

  In order to calculate the sensitivity coefficient α according to the principle described above, the ethanol concentration detector 30 of the ethanol concentration detector 10 according to the present embodiment is acquired by the data acquisition unit 32 when it is determined that the vehicle is not on the vehicle. A data storage control unit 42 for storing a data set representing a combination of detected values of the alcohol sensor 24A, the humidity sensor 24B, and the temperature sensor 24D in a data storage unit 44 to be described later, and a data storage storing a plurality of data sets A data search unit 46 that searches the data storage unit 44 for a recent data set that has the same temperature as the data set acquired by the data acquisition unit 32 and has a humidity difference equal to or greater than a predetermined value, Based on the data set acquired by the data acquisition unit 32 and the searched data set, The sensitivity coefficient calculating section 48 for calculating a sensitivity coefficient of the sensor 24A, further includes a sensitivity coefficient storage unit 50 that stores the sensitivity coefficients calculated by the sensitivity coefficient calculating section 48.

  The data storage control unit 42 stores the data set acquired by the data acquisition unit 32 in the data storage unit 44 together with the current time (detection time).

The data search unit 46 has the same data set acquired by the data acquisition unit 32 as the detected value of the temperature sensor 24D, and the difference between the detected values of the humidity sensor 24B is a predetermined value (for example, 1 g / m ³⁾ . The data set is searched from the data storage unit 44 using a search condition that the data is acquired within a predetermined period (for example, within one week to one month).

  The sensitivity coefficient calculation unit 48 detects the detection value of the alcohol sensor 24A and the detection value of the humidity sensor 24B of the data set acquired by the data acquisition unit 32, and the detection value of the alcohol sensor 24A and the detection value of the humidity sensor 24B of the searched data set. Based on the detected value, the sensitivity coefficient α is calculated according to the above equation (6).

  When two or more data sets that match the search conditions are searched by the data search unit 46, the sensitivity coefficient calculation unit 48 sets the data set and the data acquisition unit 32 for each of the searched data sets. The sensitivity coefficient α may be calculated according to the above equation (6) using the data set obtained by the above, and the average value of the sensitivity coefficient α may be used as the calculation result of the sensitivity coefficient α.

  The sensitivity coefficient calculation unit 48 updates the sensitivity coefficient α stored in the sensitivity coefficient storage unit 50 every time the sensitivity coefficient α is calculated.

  The ethanol concentration detector 30 further includes a sensor replacement determination unit 52 that determines whether or not the sensitivity coefficient α calculated by the sensitivity coefficient calculation unit 48 is less than a threshold value.

  The sensitivity coefficient α has an initial value of 1 and decreases as the sensor sensitivity deteriorates. Since the detection accuracy deteriorates as the sensitivity decreases, it is possible to determine whether or not the sensor can be replaced by determining a threshold value as a criterion for α. Therefore, when the sensor replacement determination unit 52 determines that the sensitivity coefficient α calculated by the sensitivity coefficient calculation unit 48 is less than the threshold value, the sensor replacement determination unit 52 determines that the alcohol sensor 24A needs to be replaced. In this case, the display control unit 40 controls the display unit 26 to display the determination result of the sensor replacement determination unit 52 (for example, a sensor replacement warning).

  Next, a processing routine of sensitivity coefficient and ethanol concentration calculation processing in the present embodiment will be described with reference to FIG. This routine is performed by the CPU executing a program stored in the ROM. Further, this routine is executed by the CPU every predetermined period (for example, every 30 minutes).

  In step 100, the alcohol sensor 24A, the humidity sensor 24B, the oxygen sensor 24C, and the temperature sensor 24D are turned on, and the detection values of each of the four sensors are acquired. Further, the boarding sensor 28 is turned on, and the detection result from the boarding sensor 28 is acquired.

  In step 102, it is determined whether or not the vehicle is on the basis of the detection result from the boarding sensor 28 acquired in step 100. If it is determined that the user has boarded, it is determined in step 104 whether or not exhalation has been input to the exhalation introduction tube 20. If the detected value of the oxygen sensor 24C acquired in step 100 is less than or equal to a predetermined value, it is determined that exhalation has been input.

  If exhalation has been input, the process proceeds to step 106. If not, the process returns to step 100, and steps 100 to 104 are repeated until exhalation is input.

  In step 106, a value ln (G) obtained by logarithmically converting the detection value G of the alcohol sensor 24A into the above equation (1) and a value ln [Humi] obtained by logarithmically converting the water vapor concentration [Humi] obtained from the detection value H of the humidity sensor 24B. ] And the sensitivity coefficient α stored in the sensitivity coefficient storage unit 50 are substituted to calculate the ethanol concentration [Gas]. Note that ln [Humi] is obtained by substituting the detected value H of the humidity sensor 24B into the above equation (7).

  Next, in step 108, the calculation result is displayed on the display unit 26, and the process is terminated.

  On the other hand, if it is determined in step 102 that the vehicle has not been boarded, in step 110, the detected value of the alcohol sensor 24A, the detected value of the humidity sensor 24B, and the detected value of the temperature sensor 24D acquired in step 100 are set. A data set representing the combination is stored in the data storage unit 44 together with the current time.

  Next, in step 112, a predetermined search condition (the same temperature and the difference in humidity is equal to or greater than a predetermined value and the acquisition time is within a predetermined period for the data set stored in step 110 above) ) Is retrieved from the past data sets stored in the data storage unit 44.

  In step 114, it is determined whether or not one or more data sets have been searched in the search in step 112. If no data set that matches the search conditions is found, the processing routine is terminated. On the other hand, when one or more data sets that match the search conditions are searched, in step 116, the sensitivity coefficient is calculated using the data set stored in step 110 and the data set searched in step 112. α is calculated.

  In step 118, the sensitivity coefficient stored in the sensitivity coefficient storage unit 50 is updated to the sensitivity coefficient α calculated in step 116.

  In the next step 120, it is determined whether or not the sensitivity coefficient α calculated in step 116 is less than a threshold value. If the sensitivity coefficient α is equal to or greater than the threshold value, the processing routine is terminated. On the other hand, if the calculated sensitivity coefficient α is less than the threshold value, a sensor replacement warning message is displayed on the display unit 26 in step 122, and the processing routine is terminated.

  As described above, according to the ethanol concentration detection device according to the present embodiment, the temperature among the plurality of data sets representing the combination of the detection value of the alcohol sensor, the detection value of the humidity sensor, and the detection value of the temperature sensor. The detection values of the sensors are the same, the detection values of the humidity sensors are different, and in a plurality of data sets detected within a predetermined period, it is considered that the VOC has the same concentration level. By calculating the sensitivity coefficient of the alcohol sensor from the difference in output, the sensitivity coefficient can be calculated with high accuracy by a simple method.

  In addition, the alcohol sensor has sensitivity other than the target ethanol gas. In particular, since water vapor is present in the air at a high concentration, it is necessary to correct the humidity of the output of the alcohol sensor. In the present embodiment, the influence of humidity is reversely used to correct the change with time of the alcohol sensor, particularly the sensitivity change, so as to maintain the quantitativeness with respect to the ethanol gas concentration. Thereby, it is not necessary to recalibrate the alcohol sensor, and long-term maintenance-free operation can be realized. In particular, it is effective even when the frequency of use is low. In addition, the replacement time of the alcohol sensor can be presented.

  Since the sensor information obtained when the sensor is intermittently applied when not in use (preheating for maintaining performance) is used, the sensitivity coefficient can be updated without any problem even when the sensor is not used for a long time. In addition, since the sensor response when exhalation does not enter is used, the sensitivity coefficient can be accurately calculated without being affected by substances derived from food and drink contained in exhalation.

  Further, since the ethanol gas concentration is calculated using the latest sensitivity coefficient, the ethanol gas concentration can be detected with high accuracy.

  In the above embodiment, the search condition related to temperature is described as an example of searching a data set assuming that the temperature is the same. However, the search condition related to temperature is not limited to this. The data set may be searched as the temperature is close (for example, the temperature difference is within a predetermined range).

  In addition, the search condition related to humidity has been described by taking an example in which a data set is searched when the humidity difference becomes a predetermined value or more. However, the present invention is not limited to this, and the search condition related to humidity is different in humidity. As a matter of fact, the data set may be searched.

  Alternatively, the sensitivity coefficient may be updated after determining whether the sensitivity coefficient α calculated by the sensitivity coefficient calculation unit is an appropriate value. For example, when the calculated sensitivity coefficient α is 1 or more, the calculated sensitivity coefficient α may not be updated and the sensitivity coefficient may not be updated. In this case, the sensitivity coefficient may be calculated every time a detection value is obtained from each sensor without using the boarding sensor. When a passenger is present, the calculated sensitivity coefficient α is not an appropriate value, and thus the sensitivity coefficient is not updated.

  Moreover, although the case where each sensor was provided in the vehicle interior was demonstrated to the example, it is not limited to this. For example, each sensor may be provided in an office. In this case, it is not necessary to use a sensor that detects whether or not a person exists. For example, the sensitivity coefficient may be calculated using a data set detected from each sensor in a time zone when there are no employees.

  Moreover, although the case where this invention was applied to the alcohol concentration detection apparatus was demonstrated to the example, it is not limited to this, You may apply this invention to an apparatus different from the apparatus provided with each sensor. . For example, the present invention may be applied to a sensor deterioration determination device that determines deterioration of sensitivity of an alcohol sensor. In this case, the sensor deterioration determination device only needs to include the data storage unit 44, the data search unit 46, the sensitivity coefficient calculation unit 48, the sensor replacement determination unit 52, the display control unit 40, and the display unit 26. A plurality of data sets collected by a device provided with each sensor are input to the sensor deterioration determination device. The data storage unit 44 stores a plurality of input data sets. The data search unit 46 uses, as a search condition, two data sets from the data storage unit 44 that have the same temperature and a humidity difference that is equal to or greater than a predetermined value and is acquired within a predetermined period. Search multiple datasets.

  Moreover, although the case where the input of the expiration was determined based on the detection value of the oxygen sensor has been described as an example, the present invention is not limited to this, and any one of the alcohol sensor and the humidity sensor is used without using the oxygen sensor. When the detected value starts to change, it may be determined that exhalation has been input. Further, a flow rate sensor may be provided at the introduction port 20A, and it may be determined whether or not exhalation has been introduced based on the detection result of the flow rate sensor.

  In the above embodiment, the case where the calculated concentration of the ethanol gas in the expiration is displayed has been described. However, the present invention is not limited to this. For example, the calculated ethanol gas concentration and a predetermined threshold value May be determined so that the ethanol concentration is high when the calculated ethanol gas concentration is equal to or greater than the threshold value, and control may be performed so as to prevent fraud such as preventing the engine from starting.

  In the above embodiment, the case where ethanol is detected from the exhalation of the driver has been described. However, the present invention detects ethanol from the exhalation of humans other than the driver by configuring the ethanol concentration detection device to be portable. It can also be applied to cases.

DESCRIPTION OF SYMBOLS 10 Ethanol concentration detection apparatus 12 Steering column 24A Alcohol sensor 24D Temperature sensor 24C Oxygen sensor 24B Humidity sensor 26 Display part 28 Ride sensor 30 Ethanol concentration detector 32 Data acquisition part 34 Boarding determination part 36 Exhalation judgment part 38 Gas concentration calculation part 40 Display Control unit 42 Data storage control unit 44 Data storage unit 46 Data search unit 48 Sensitivity coefficient calculation unit 50 Sensitivity coefficient storage unit 52 Sensor replacement determination unit

Claims (12)

It has sensitivity to the detection target gas contained in the detection target gas and the humidity of the detection target gas, and detects a physical quantity related to the concentration of the detection target gas and a physical quantity corresponding to the physical quantity related to the humidity. Gas detection means for outputting the detection value as
Humidity detection means for detecting and outputting a physical quantity related to the humidity of the gas to be detected;
Temperature detecting means for detecting and outputting the temperature of the gas to be detected; and
Storage means storing a plurality of data sets representing combinations of detection values of the gas detection means, detection values of the humidity detection means, and detection values of the temperature detection means;
A sensitivity coefficient calculation unit that calculates a sensitivity coefficient of the gas detection unit based on a plurality of data sets corresponding to detection values of the temperature detection unit among the plurality of data sets stored in the storage unit;
Sensitivity coefficient calculation device including   The sensitivity coefficient calculation unit is based on a plurality of data sets corresponding to detection values of the temperature detection unit and different detection values of the humidity detection unit among the plurality of data sets stored in the storage unit. The sensitivity coefficient calculation apparatus according to claim 1, wherein the sensitivity coefficient of the gas detection means is calculated.   The sensitivity coefficient calculating unit corresponds to a detection value of the temperature detection unit among the plurality of data sets stored in the storage unit, and a difference between detection values of the humidity detection unit is a predetermined value or more. The sensitivity coefficient calculation device according to claim 2, wherein a sensitivity coefficient of the gas detection means is calculated based on a plurality of data sets.   The sensitivity coefficient calculation device according to any one of claims 1 to 3, wherein the sensitivity coefficient calculation unit calculates a sensitivity coefficient of the gas detection unit for each predetermined period. The gas detection means is installed indoors,
The humidity detecting means is installed in the room,
The temperature detecting means is installed in the room,
The storage means stores a plurality of data sets representing combinations of detection values of the gas detection means, detection values of the humidity detection means, and detection values of the temperature detection means when no person is present in the room. The sensitivity coefficient calculation apparatus according to claim 1. The room is a vehicle interior,
The sensitivity coefficient calculation apparatus according to claim 5, wherein the person is an occupant.   The sensitivity coefficient calculating means is based on a plurality of data sets corresponding to detection values of the temperature detecting means among the plurality of data sets stored in the storage means and detected within a predetermined period. The sensitivity coefficient calculation apparatus according to any one of claims 1 to 6, wherein a sensitivity coefficient of the gas detection means is calculated. The sensitivity coefficient calculation means calculates the sensitivity coefficient by the following equation (I) based on the first data set and the second data set corresponding to the detection values of the temperature detection means. The sensitivity coefficient calculation apparatus according to any one of the above.
α = (ln (G ₁ ) −ln (G ₂ )) / b · (ln [Humi ₁ ] −ln [Humi ₂ ])
... (I)
However, G ₁ is the detected value of the gas detector of the first data set, G ₂ is the detected value of the gas detector of the second data set, humi ₁ from the detection value of the humidity detecting means of the first data set The physical quantity related to the required humidity, Humi ₂ is the physical quantity related to the humidity determined from the detection value of the humidity detecting means of the second data set, and b is a constant.   The detection value of the gas detection means is a product of a physical quantity related to the concentration of the detection target gas and a first coefficient corresponding to the sensitivity characteristic, and a second coefficient corresponding to the physical quantity related to the humidity and the sensitivity characteristic. And a physical quantity related to the humidity detected by the humidity detecting means and expressed using the sensitivity coefficient that corrects the first coefficient and the second coefficient in accordance with a change in sensitivity characteristic. The sensitivity coefficient calculation apparatus according to claim 1, further comprising a concentration calculation unit that calculates a concentration of the detection target gas using a gas. The gas detection device according to claim 9, wherein a detection value of the gas detection means is expressed by the following formula (II).
ln (G) = α · (a · ln [Gas] + b · ln [Humi]) + c (II)
Where G is a detection value of the gas detection means, α is the sensitivity coefficient, [Gas] is a physical quantity related to the concentration of the gas to be detected, [Humi] is a physical quantity related to humidity, a is the first coefficient, b Is the second coefficient, and c is a constant.   The sensitivity coefficient calculation device according to any one of claims 1 to 10, further comprising notification means for notifying warning information when the sensitivity coefficient calculated by the sensitivity coefficient calculation means is equal to or less than a predetermined value. It has sensitivity to the detection target gas contained in the detection target gas and the humidity of the detection target gas, and detects a physical quantity related to the concentration of the detection target gas and a physical quantity corresponding to the physical quantity related to the humidity. And detecting the detection value of the gas detection means for outputting the detection value, the detection value of the humidity detection means for detecting and outputting the physical quantity related to the humidity of the detection target gas, and the temperature of the detection target gas A computer including storage means for storing a plurality of data sets representing combinations of detection values of the temperature detection means for output;
Based on a plurality of data sets corresponding to detection values of the temperature detection unit among the plurality of data sets stored in the storage unit, the function is performed as a sensitivity coefficient calculation unit that calculates a sensitivity coefficient of the gas detection unit. Program for.

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