JP2010223626A - Gas detection apparatus and program - Google Patents

Abstract

An object of the present invention is to accurately detect the concentration of a gas component to be detected by reducing the influence of a change in humidity with a simple configuration.
A humidity calculation unit 34 calculates a humidity base value and a peak value from a base value and a peak value of detection values from an alcohol sensor 24A and a gas sensor 24B. The ethanol concentration calculator 32 calculates the base value and peak value of the concentration of ethanol gas from the base value and peak value of the detected value from the alcohol sensor 24A and the gas sensor 24B. The ethanol concentration detector 36 detects the concentration of ethanol gas in exhaled breath based on the calculated change amount of ethanol gas concentration and the calculated ratio of change in humidity.
[Selection] Figure 4

Description

  The present invention relates to a gas detection device and a program, and more particularly to a gas detection device and a program capable of detecting the concentration of alcohol contained in a driver's breath.

  2. Description of the Related Art Conventionally, a technique for correcting errors such as the effects of initial drift and transient drift using two alcohol sensors is known (Patent Document 1). In this technique, air containing exhaled air and air that blocks the exhaled air are taken in, and the sensor output error of alcohol concentration in exhaled air is corrected from the output value deviation of the two sensors.

  In addition, when an oxide semiconductor gas sensor is used, since the sensitivity change due to environmental humidity is large, a technique for correcting the humidity effect using a humidity sensor is known.

JP-A-7-225204

  However, since the alcohol sensor is also affected by humidity in the technique described in Patent Document 1, the humidity change caused by the exhalation input is corrected based on the sensor output with respect to the air that blocks the exhalation. Therefore, there is a problem that the gas concentration cannot be detected accurately.

  In addition, the technique for performing correction using a humidity sensor requires a humidity sensor, and thus has a problem that costs are increased.

  The present invention has been made to solve the above problems, and has a simple configuration, reduces the influence of changes in humidity, and can accurately detect the concentration of a gas component to be detected. And to provide a program.

  In order to achieve the above object, the gas detection device of the present invention has sensitivity to the detection target gas and water vapor contained in the detection target gas, and has different sensitivity to the water vapor, and the detection target is different. A plurality of gas sensors for detecting a physical quantity associated with a gas concentration and a physical quantity corresponding to a physical quantity associated with the humidity of the gas to be detected and outputting a detection value, and the detection value output by each of the plurality of gas sensors Based on the detection values before and after the change of the detection value, humidity calculating means for calculating a physical quantity related to the humidity before and after the change of the detection value, respectively, and the humidity calculation means before and after the change of the detection value Based on the detection value of the gas sensor, a gas concentration calculation that calculates a physical quantity related to the concentration of the detection target gas before and after the change of the detection value, respectively. And a change amount of the physical quantity related to the concentration of the detection target gas calculated by the gas concentration calculation means and a ratio of the change amount of the physical quantity related to the humidity calculated by the humidity calculation means, Gas concentration detecting means for detecting the concentration of the detection target gas.

  The program of the present invention has a computer that has sensitivity to a detection target gas and water vapor contained in a detection target gas, and has different sensitivities to the water vapor, and is associated with a concentration of the detection target gas. And based on the detected value before and after the change of the detected value output by each of a plurality of gas sensors that detect a physical quantity corresponding to the physical quantity related to the humidity of the gas to be detected and output a detected value. A humidity calculating means for calculating a physical quantity related to the humidity before and after the change in the detected value, and a change in the detected value based on the detected value of the gas sensor before and after the change in the detected value. Gas concentration calculating means for calculating a physical quantity related to the concentration of the detection target gas before and after each of the above, and by the gas concentration calculating means The concentration of the detection target gas is detected based on the calculated change amount of the physical quantity related to the concentration of the detection target gas and the ratio of the change amount of the physical quantity related to the humidity calculated by the humidity calculation means. It is a program for functioning as a gas concentration detection means.

  According to the present invention, the physical quantity related to the concentration of the detection target gas by the plurality of gas sensors having sensitivity to the detection target gas and water vapor contained in the detection target gas and having different sensitivity to the water vapor. And a physical quantity corresponding to the physical quantity related to the humidity of the gas to be detected is detected and a detected value is output.

  Based on the detected values before and after the change of the detected value output by each of the plurality of gas sensors, the physical quantity related to the humidity before and after the change of the detected value is calculated by the humidity calculating unit. Based on the detection value of the gas sensor before and after the change of the detection value, the physical quantity related to the concentration of the detection target gas before and after the change of the detection value is calculated by the gas concentration calculation means.

  Based on the ratio of the change amount of the physical quantity related to the concentration of the detection target gas calculated by the gas concentration calculation means and the change amount of the physical quantity related to the humidity calculated by the humidity calculation means by the gas concentration detection means. The concentration of the detection target gas is detected.

  As described above, the physical quantity related to the humidity is calculated based on the detection value output by each of the plurality of gas sensors, the change amount of the physical quantity related to the concentration of the detection target gas, and the change of the physical quantity related to the humidity. By detecting the concentration of the detection target gas based on the ratio of the amounts, it is possible to accurately detect the concentration of the gas component to be detected with a simple configuration while reducing the influence of changes in humidity.

  The humidity calculating means according to the present invention is based on the detection value output by each of the plurality of gas sensors, the output characteristics for the humidity determined in advance for each of the plurality of gas sensors, and the output characteristics for the concentration of the detection target gas. A physical quantity related to humidity can be calculated.

  Further, the humidity calculating means can calculate a physical quantity related to humidity according to the following equation.

_However, G A, _{G B} is the detected value of each of the plurality of gas sensors, [humi] is a physical quantity related to the _humidity, a A, _{a B,} the previously obtained detection for each of a plurality of gas sensors _{B A} and b _B are parameters according to output characteristics with respect to humidity determined in advance for each of the plurality of gas sensors, and c _A and c _B are constants. It is.

  The gas concentration calculation means according to the present invention is based on the detection value output by each of the plurality of gas sensors, the output characteristic for humidity determined in advance for each of the plurality of gas sensors, and the output characteristic for the concentration of the detection target gas. The physical quantity related to the concentration of the detection target gas can be calculated.

  In addition, the gas concentration calculation means can calculate a physical quantity related to the concentration of the detection target gas according to the following equation.

  However, [Gas] is a physical quantity related to the concentration of the detection target gas.

  The humidity calculation means according to the present invention calculates a base value of a physical quantity related to humidity before the detection value changes based on a base value before the detection value of each of the plurality of gas sensors changes. Based on the peak value when each detected value changes and becomes a peak, a physical quantity related to the humidity when the detected value changes and becomes a peak is calculated. Based on the base value before the detection value changes, the physical quantity related to the concentration of the detection target gas before the detection value changes is calculated, and the peak value when the detection value of the gas sensor changes to the peak is calculated. Based on this, it is possible to calculate a physical quantity related to the concentration of the detection target gas when the detection value changes and becomes a peak.

  The detection target gas can be ethanol gas. The gas sensor may be an oxide semiconductor gas sensor.

  As described above, according to the present invention, the physical quantity related to the humidity is calculated based on the detection value output from each of the plurality of gas sensors, the amount of change in the physical quantity related to the concentration of the detection target gas, and By detecting the concentration of the detection target gas based on the ratio of the amount of change in the physical quantity related to humidity, the influence of the change in humidity can be reduced with a simple configuration and the concentration of the gas component to be detected can be accurately determined. The effect that it can detect is acquired.

It is the schematic which shows the state which attached the ethanol concentration detection apparatus of the 1st Embodiment of this invention to the steering column of the driver's seat. It is the schematic which shows the 1st Embodiment of this invention. It is a circuit diagram which shows the structure of an alcohol sensor and a gas sensor. It is a block diagram which shows the structure of the ethanol concentration determination device of the 1st Embodiment of this invention. (A) The graph which shows the relationship between the gas concentration and humidity of an alcohol sensor, and a sensor output, and (B) The graph which shows the relationship between the gas concentration and humidity of a gas sensor, and a sensor output. It is a graph which shows the relationship between a humidity estimated value and the set humidity. It is a graph which shows the relationship between the ratio of the variation | change_quantity of the density | concentration of ethanol gas, and the variation | change_quantity of humidity, and the density | concentration of ethanol gas. It is a graph which shows the base value and peak value of the detection signal from an alcohol sensor and a gas sensor. It is a flowchart which shows the content of the ethanol concentration detection process routine in the ethanol concentration determination device of the 1st Embodiment of this invention. It is a graph which shows the relationship between a sensor fixed value and actual gas concentration. It is a flowchart which shows the content of the ethanol concentration detection processing routine in the ethanol concentration determination device of the 2nd Embodiment of this invention.

  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 apparatus 10 according to the first embodiment is attached to a steering column 12 provided in a driver's seat at a position where a 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. It has been.

  As shown in FIG. 2, the sensor group 24 includes an alcohol sensor 24 </ b> A and a gas sensor 24 </ b> B that are sensitive to many types of gas components and are attached to face the inside of the middle part of the exhalation introduction tube 20. ing.

  The alcohol sensor 24A is a sensor that detects ethanol gas contained in the gas flowing in the exhalation introduction pipe 20, and is sensitive to ethanol gas and water vapor. As the alcohol sensor 24A, for example, TGS822 (trade name, manufactured by Figaro Giken Co., Ltd.) using a tin oxide semiconductor can be used.

  Unlike the alcohol sensor 24A, the gas sensor 24B has sensitivity to many types of gas components including ethanol gas and water vapor, unlike the alcohol sensor 24A. As the gas sensor 24B, for example, an air quality sensor (a sensor that detects air dirt) can be used, and TGS2600 (trade name, manufactured by Figaro Giken Co., Ltd.) can be used.

  Further, a suction fan 22 that is driven in order to suck the breath of the driver from the suction port 20A is provided inside the breath introduction tube 20 and closer to the suction port 20A than the alcohol sensor 24A and the gas sensor 24B.

The alcohol sensor 24A and the gas sensor 24B are configured by a circuit as shown in FIG. In the alcohol sensor 24A and the gas sensor 24B, the heater voltage V _H and the sensor power source V _C are applied, and the voltage across the load resistor _RL (sensor output voltage) V _S connected in series to the sensor element R _S is used as a detection signal. Output. Accordingly, the alcohol sensor 24A and the gas sensor 24B output a detection signal having a high level because the resistance value of the sensor element changes as the concentration of ethanol gas contained in the gas flowing in the breath introduction pipe 20 increases. Since the resistance value of the sensor element changes as the concentration of ethanol gas contained in the gas flowing through the exhalation introduction tube 20 decreases, a detection signal having a low level is output. In addition, the alcohol sensor 24A and the gas sensor 24B output a detection signal having a high level because the resistance value of the sensor element changes as the humidity of the gas flowing in the exhalation introduction pipe 20 increases. Since the resistance value of the sensor element changes as the humidity of the flowing gas decreases, a detection signal having a low level is output.

  According to this embodiment, when the suction fan 22 is driven, the exhaled air exhaled from the driver is drawn into the exhalation introduction tube 20 from the intake port 20A of the exhalation introduction tube 20, and the exhalation is mixed with the air. As a result, the alcohol sensor 24A and the gas sensor 24B are reached at a constant flow rate. Then, after the exhaled breath comes into contact with the alcohol sensor 24A and the gas sensor 24B, the exhaled breath is discharged out of the exhalation introducing tube 20.

  A gas component (ethanol gas or water vapor) having sensitivity to the alcohol sensor 24A and the gas sensor 24B comes into contact with the alcohol sensor 24A and the gas sensor 24B, so that the alcohol sensor 24A and the gas sensor 24B detect a signal corresponding to the concentration of the gas component in the gas. Is output. Detection signals output from the alcohol sensor 24A and the gas sensor 24B are input to an ethanol concentration determiner described later, and the concentration of the ethanol gas component as a detection target gas component is detected based on the input detection signal. The detection signals output from the alcohol sensor 24A and the gas sensor 24B are simultaneously taken in at regular intervals by the ethanol concentration determiner.

  As shown in FIG. 4, the ethanol concentration detection apparatus 10 includes an ethanol concentration determination device 30 that is connected to the alcohol sensor 24A and the gas sensor 24B and detects the concentration of the ethanol gas component and displays the ethanol gas component on the display device 40. Yes.

  The ethanol concentration determination unit 30 is configured by a computer including a CPU, a ROM that stores a program for realizing an ethanol concentration detection processing routine that will be described later, a RAM that temporarily stores data, and a storage device such as an HDD. Yes. When the ethanol concentration determination unit 30 is expressed in functional blocks in accordance with the ethanol concentration detection processing routine described below, as shown in FIG. An ethanol concentration calculation unit 32 that calculates a base value and a peak value of the concentration; and a humidity calculation unit 34 that calculates a base value and a peak value of the humidity based on the detection signal from the alcohol sensor 24A and the detection signal from the gas sensor 24B; Based on the calculated change amount of the ethanol gas concentration and the ratio of the calculated change amount of the humidity, the concentration of the ethanol gas in the gas flowing in the breath introduction pipe 20 is calculated and output to the display device 40. And an ethanol concentration detection unit 36.

  Next, the principle of calculating the ethanol gas concentration and humidity in the present embodiment will be described.

First, in the alcohol sensor 24A and the gas sensor 24B, which are oxide semiconductor gas sensors, as shown in FIGS. 5A and 5B, the sensor output is affected by the environmental humidity, so the alcohol sensor 24A and the gas sensor 24B sensor output _(G a, _{G B:} conductance) values were log-transformed, due to the gas concentration ([EtOH]) and humidity ([humi]), is expressed by the following equation (1).

However, a _A is a parameter corresponding to the output characteristics with respect to the concentration of the previously obtained ethanol gas for alcohol sensor 24A, b _A is an parameter corresponding to the output characteristics with respect to previously obtained humidity for alcohol sensor 24A , C _A are constants. Further, a _B is a parameter according to the output characteristic with respect to the concentration of ethanol gas obtained in advance for the gas sensor 24B, b _B is a parameter according to the output characteristic with respect to the humidity obtained in advance for the gas sensor 24B, and c _B is a constant. These parameters may be obtained by measuring the output characteristics as shown in FIG. 5 in advance using experimental gas or the like.

  As represented by the above equation (1), the alcohol sensor 24A and the gas sensor 24B detect a physical quantity corresponding to the concentration and humidity of the ethanol gas and output a detection value.

  Here, from the characteristic that the alcohol sensor 24A and the gas sensor 24B respond stably to humidity, when sensor outputs in the same humidity environment of two sensors having different characteristics are used, the humidity is logarithmically converted from the above equation (1). The values obtained are expressed by the following formulas (2) and (3).

  However, d, e, and f are parameters obtained in advance according to the output characteristics with respect to the concentration of ethanol gas and the output characteristics with respect to humidity in each of the alcohol sensor 24A and the gas sensor 24B.

  When the estimated humidity value calculated from the sensor output value according to the above equation (3) is compared with the actual set humidity, the relationship shown in FIG. 6 is obtained, and the humidity value is accurately calculated using the above equation (3). It turns out that it can be estimated well.

  Further, the following expression (4) is obtained from the above expression (1).

  From the above formulas (3) and (4), the following formula (5) is obtained.

Ethanol concentration calculation unit 32, the base value of the sensor output G _A of the alcohol sensor 24A of the breath input (before the change of the detection signal), and based on the base value of the sensor output G _B of the gas sensor 24B, the expression (5) Accordingly, the base value of the concentration of ethanol gas before the expiration input (before the change of the detection signal) is calculated. Further, the ethanol concentration calculation unit 32, the peak value of the alcohol sensor 24A of the sensor output G _A after expiration input (after the change of the detection signal), and based on the peak value of the sensor output G _B of the gas sensor 24B, the (5 ), The peak value of the concentration of ethanol gas after the exhalation is input (after the detection signal is changed) is calculated.

  As the base value of the ethanol gas concentration, for example, an average value or a minimum value in an arbitrary interval before exhalation input is used. Further, the maximum value in an arbitrary section after exhalation input is used as the peak value of the ethanol gas concentration.

Humidity calculating section 34, the base value of the sensor output G _A of the previous breath input alcohol sensor 24A, and based on the base value of the sensor output G _B of the gas sensor 24B, according to the above (3), before expiration input humidity Calculate the base value. Further, the ethanol concentration calculation unit 32, the peak value of the sensor output G _A of the alcohol sensor 24A after exhalation input, and based on the peak value of the sensor output G _B of the gas sensor 24B, according to the above (3), after expiration input The peak value of humidity is calculated.

  As the humidity base value, for example, an average value or a minimum value in an arbitrary interval before exhalation input is used. Further, the maximum value in an arbitrary section after exhalation input is used as the humidity peak value.

  Next, the principle of detecting the concentration of ethanol gas in the present embodiment will be described.

  First, when detecting the concentration of ethanol gas, it is necessary to correct the influence of fluctuations in the amount of exhaled gas in the gas to be detected. In order to correct the influence due to the fluctuation of the inhaled exhalation volume, it is preferable to measure the concentration of a substance proportional to the exhalation volume. As such a substance, water vapor is preferable. The amount of water contained in a person's exhalation is almost constant, and usually corresponds to a saturated vapor pressure of 34 ° C. Therefore, as shown in FIG. 7, the concentration of ethanol gas and (ethanol gas concentration / humidity) are in a proportional relationship. This proportional relationship is considered to be the same even when exhaled air is diluted in air, so this ratio, that is, the amount of change in ethanol gas concentration (Δethanol) and the amount of change in humidity (Δhumidity). If the ratio (Δethanol / Δhumidity) can be measured, the concentration of ethanol gas in exhaled breath can be detected based on the relationship between the ratio of Δethanol and Δhumidity and the concentration of ethanol gas shown in FIG. it can.

The slope of the relationship shown in FIG. 7 corresponds to the reciprocal of the water vapor concentration in exhaled breath. If the saturated water vapor pressure at 34 ° C. (40.04 / mgHg or 55,615 ppm) is adopted as the water vapor concentration in the exhaled breath, the slope is 1 / 40.04 (mgHg) ⁻¹ or 1 / 55,615 (ppm ^-1 ).

  As described above, by measuring the humidity and obtaining the ethanol gas concentration as a function of Δethanol / Δhumidity, it is possible to correct the influence of the change in the expiration amount in the gas to be detected. In addition, it is possible to detect the concentration of ethanol gas by removing the influence of changes in humidity.

  As shown in FIG. 8, the ethanol concentration detection unit 36 is calculated based on the concentration of ethanol gas calculated based on the base value of the sensor output of each of the alcohol sensor 24A and the gas sensor 24B and the peak value of each sensor output. The amount of change in ethanol gas concentration is calculated from the concentration of ethanol gas. Further, the ethanol concentration detection unit 36 calculates the amount of change in humidity from the humidity calculated based on the base value of each sensor output and the humidity calculated based on the peak value of each sensor output. The ethanol concentration detection unit 36 calculates the ratio of the calculated change amount of ethanol gas and the change amount of humidity, and the ratio of change amount obtained in advance and the concentration of ethanol gas as shown in FIG. Based on the correspondence prepared in advance, the concentration of the ethanol gas component contained in the gas flowing in the exhalation introduction tube 20 is detected.

  Next, the operation of the ethanol concentration detection apparatus 10 according to the first embodiment will be described. When the driver is seated on the vehicle seat, the exhalation of the driver is blown into the exhalation introduction tube 20, and when the ignition switch is turned on by the driver, the ethanol concentration determination device 30 of the ethanol concentration detection device 10 performs the ethanol shown in FIG. A concentration detection processing routine is executed.

  First, in step 100, a detection signal is acquired from each of the alcohol sensor 24A and the gas sensor 24B, and in step 102, whether or not exhalation has been introduced into the exhalation introduction tube 20 from a change in the detection signal from the alcohol sensor 24A. judge. When a change amount of the detection signal less than a predetermined amount is detected, it is determined that exhalation has not been introduced into the exhalation introduction tube 20, and in step 104, each of the alcohol sensor 24A and the gas sensor 24B acquired in step 100 is determined. Based on the detection signal, the concentration of ethanol gas is calculated and stored as a base value before exhalation input according to the above equation (5). In the next step 106, based on the detection signals of the alcohol sensor 24A and the gas sensor 24B acquired in step 100, the humidity is calculated and stored as the base value before exhalation input according to the above equation (3). Return to Step 100 above.

  When the change amount of the detection signal equal to or larger than the predetermined amount is detected in step 102, it is determined that the exhalation is introduced into the exhalation introduction tube 20 and the gas component has changed. In step 108, the change is acquired in step 100. Based on the peak values of the detection signals of the alcohol sensor 24A and the gas sensor 24B, the ethanol gas concentration is calculated and stored as the peak value after exhalation input according to the above equation (5). In the next step 110, based on the peak value of each detection signal of the alcohol sensor 24A and the gas sensor 24B acquired in the step 100, the humidity is calculated as the peak value after exhalation input according to the above equation (3). Remember.

  In step 112, the base value of ethanol gas concentration calculated in steps 104 and 108, the amount of change in ethanol gas concentration obtained from the peak value, and the base value of humidity calculated in steps 106 and 110 above. Based on the amount of change in humidity obtained from the peak value, the ratio between the amount of change in ethanol gas concentration and the amount of change in humidity is obtained. Then, based on the ratio between the amount of change in the concentration of ethanol gas and the amount of change in humidity, and the correspondence between the ratio of the amount of change in ethanol gas concentration and the amount of change in humidity and the concentration of ethanol gas, The concentration of ethanol gas contained in the gas flowing through 20 is detected.

  In the next step 114, the ethanol gas concentration detected in step 112 is displayed on the display device 40, and the ethanol concentration detection processing routine is terminated.

  Comparing the ethanol gas concentration (sensor quantitative value) detected by the above ethanol concentration detection processing routine with the actual ethanol gas concentration, as shown in FIG. It was found that the gas concentration could be detected.

  As described above, according to the ethanol concentration detection apparatus according to the first embodiment, the humidity is calculated based on the detection values output from the alcohol sensor and the gas sensor, and the change in the concentration of ethanol gas is detected. By detecting the concentration of ethanol gas in the expiration based on the ratio of the amount of change and the amount of humidity, the effect of the change in humidity can be reduced with a simple configuration that does not use a humidity sensor, and ethanol in the expiration can be reduced. The gas concentration can be detected with high accuracy. In addition, it is possible to accurately detect the concentration of ethanol gas in exhaled air by correcting the influence of fluctuations in the amount of exhaled air flowing through the exhalation introducing tube.

  In the oxide semiconductor gas sensor, the sensor output (resistance value change) is affected by the environmental humidity, but by utilizing the characteristic that this sensor responds stably to humidity, by using two sensors with different characteristics, The humidity can be accurately estimated from the output characteristics of the two sensors. Moreover, since it is not necessary to use a humidity sensor, cost reduction and size reduction of a sensor can be achieved.

  In addition, it is possible to detect the breath alcohol concentration simply and accurately for the purpose of preventing the drunk driver from driving the car.

  Next, an ethanol concentration detection apparatus according to the second embodiment will be described. In addition, since the ethanol concentration detection apparatus according to the second embodiment has the same configuration as that of the first embodiment, the same reference numerals are given and description thereof is omitted.

  The second embodiment is mainly different from the first embodiment in that the base value is calculated together with the peak value for the concentration and humidity of ethanol gas after the expiration is input.

  The ethanol concentration detection processing routine according to the second embodiment will be described with reference to FIG. Note that the same processes as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  First, in step 200, detection signals are obtained from each of the alcohol sensor 24A and the gas sensor 24B and stored in a memory (not shown), and in step 102, expiration is changed from the change in the detection signal from the alcohol sensor 24A. It is determined whether or not it has been introduced into the system 20. If a change amount of the detection signal less than the predetermined amount is detected, the process returns to step 200. On the other hand, if a change amount of the detection signal greater than the predetermined amount is detected, the process advances to step 202.

  In step 202, based on the base values of the detection signals of the alcohol sensor 24A and gas sensor 24B stored in step 200, the concentration of ethanol gas is calculated as the base value before exhalation input according to the above equation (5). . Further, based on the peak values of the detection signals of the alcohol sensor 24A and gas sensor 24B stored in step 200, the concentration of ethanol gas is calculated as the peak value after exhalation input according to the above equation (5).

  In step 204, the humidity is calculated as the base value before exhalation input according to the above equation (3) based on the base values of the detection signals of the alcohol sensor 24A and gas sensor 24B stored in step 200. Moreover, based on the peak value of each detection signal of alcohol sensor 24A and gas sensor 24B memorize | stored at the said step 200, according to said (3) Formula, humidity is calculated as a peak value after the expiration input.

  Then, in step 112, the amount of change in the concentration of ethanol gas obtained from the base value and peak value of the ethanol gas concentration calculated in step 202 and the humidity base value and peak value calculated in step 204 are calculated. Based on the obtained humidity change amount, a ratio between the ethanol gas concentration change amount and the humidity change amount is obtained, and the concentration of ethanol gas contained in the gas flowing in the exhalation introduction tube 20 is detected.

  In the next step 114, the ethanol gas concentration detected in step 112 is displayed on the display device 40, and the ethanol concentration detection processing routine is terminated.

  In the first embodiment and the second embodiment described above, the case where an alcohol sensor and a gas sensor such as an air quality sensor are used has been described as an example. However, the present invention is not limited to this. What is necessary is just to comprise using the several gas sensor which has a sensitivity with respect to gas and water vapor | steam, and each has the sensitivity with respect to water vapor | steam. For example, an oxygen sensor, a water vapor sensor, a carbon dioxide sensor, or the like may be combined and an alcohol sensor may not be used.

  In addition, the case where an oxide semiconductor gas sensor is used has been described as an example. However, the present invention is not limited to this, and the present invention is not limited to this as long as the sensor output depends on humidity. Can be applied.

  In the above embodiment, the case where the detected ethanol gas concentration is displayed has been described as an example. However, the present invention is not limited to this. For example, the detected ethanol gas concentration and a predetermined threshold value may be used. The ethanol concentration may be determined to be high when the detected 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.

  Moreover, although the case where ethanol gas was used as the detection target gas was described as an example, the present invention is not limited to this, and other gas components may be used as the detection target gas.

  Moreover, although the case where the ethanol gas concentration is determined using the correspondence relationship between the change rate of the change amount of ethanol gas concentration and the change amount of humidity and the ethanol gas concentration has been described as an example, it is limited to this. Instead, the concentration of ethanol gas may be calculated from the change rate of the ethanol gas concentration and the change rate of the humidity change amount using the above-described equation representing the correspondence.

  Moreover, although the case where the ethanol gas concentration is calculated using the outputs of the alcohol sensor and the gas sensor has been described as an example, the present invention is not limited to this, and the ethanol gas concentration is determined from the sensor output of the alcohol sensor. You may make it calculate. For example, the ethanol gas concentration base value may be calculated from the sensor output base value of the alcohol sensor, and the ethanol gas concentration peak value may be calculated from the alcohol sensor sensor output peak value.

  In the above, the example of detecting the concentration of the ethanol gas component from the exhalation of the driver has been described, but by configuring the ethanol concentration detection device to be portable, the present invention can reduce the concentration of the ethanol gas component from the exhalation of humans other than the driver. The present invention can also be applied to detection.

  The program of the present invention can be provided by being stored in a storage medium.

DESCRIPTION OF SYMBOLS 10 Ethanol concentration detection apparatus 20 Breath introduction pipe | tube 24A Alcohol sensor 24B Gas sensor 30 Ethanol concentration determination device 32 Ethanol concentration calculation part 34 Humidity calculation part 36 Ethanol concentration detection part 40 Display apparatus

Claims (9)

It has sensitivity to the detection target gas and water vapor contained in the detection target gas, and the sensitivity to the water vapor is different, and the physical quantity related to the concentration of the detection target gas and the humidity of the detection target gas A plurality of gas sensors that detect physical quantities corresponding to the relevant physical quantities and output detection values;
Humidity calculation means for calculating a physical quantity related to the humidity before and after the change of the detection value based on the detection value before and after the change of the detection value output by each of the plurality of gas sensors. When,
Gas concentration calculation means for calculating a physical quantity related to the concentration of the detection target gas before and after the change of the detection value based on the detection value of the gas sensor before and after the change of the detection value;
Based on the ratio of the change amount of the physical quantity related to the concentration of the detection target gas calculated by the gas concentration calculation means and the change amount of the physical quantity related to the humidity calculated by the humidity calculation means, the detection target Gas concentration detecting means for detecting the concentration of the gas;
A gas detection device.   The humidity calculating means is based on the detection value output by each of the plurality of gas sensors, the output characteristic for the humidity and the output characteristic for the concentration of the detection target gas, which are obtained in advance for each of the plurality of gas sensors. The gas detection device according to claim 1, wherein a physical quantity related to the humidity is calculated. The gas detection apparatus according to claim 2, wherein the humidity calculating unit calculates a physical quantity related to the humidity according to the following equation.

_However, G A, _{G B} is the detected value of each of the plurality of gas sensors, [humi] is a physical quantity related to the _humidity, a A, _{a B} is obtained in advance for each of the plurality of gas sensors is a parameter corresponding to an output characteristic with respect to the concentration of the detection target gas, b _a, b _B is a parameter corresponding to an output characteristic with respect to previously obtained the humidity for each of the plurality of gas sensors, c _a, c _B is a constant.   The gas concentration calculation means is based on the detection value output by each of the plurality of gas sensors, the output characteristic for the humidity and the output characteristic for the concentration of the detection target gas, which are obtained in advance for each of the plurality of gas sensors. The gas detection device according to claim 1, wherein a physical quantity related to the concentration of the detection target gas is calculated. The gas detection device according to claim 4, wherein the gas concentration calculation unit calculates a physical quantity related to the concentration of the detection target gas according to the following equation.

However, G _A, G _B is the detected value of each of the plurality of gas sensors, [Gas] is a physical quantity relating to the concentration of the target gas, a _A, a _B is a plurality of gas sensors _{B A} and b _B are parameters according to the output characteristics with respect to the humidity determined in advance for each of the plurality of gas sensors. Yes, c _A and c _B are constants. The humidity calculating means calculates a base value of a physical quantity related to the humidity before the detection value changes based on a base value before the detection value of each of the plurality of gas sensors changes, Based on the peak value when the detected value of each of the gas sensors changes and becomes a peak, a physical quantity related to the humidity when the detected value changes and becomes a peak is calculated,
The gas concentration calculation means calculates a physical quantity related to the concentration of the detection target gas before the detection value changes based on the base value before the detection value of the gas sensor changes, and the gas sensor The physical quantity relating to the concentration of the detection target gas when the detected value changes and becomes a peak is calculated based on the peak value when the detected value changes and becomes a peak. The gas detection device according to any one of 5.   The gas detection device according to claim 1, wherein the detection target gas is ethanol gas.   The gas detection device according to any one of claims 1 to 7, wherein the gas sensor is an oxide semiconductor gas sensor. Computer
It has sensitivity to the detection target gas and water vapor contained in the detection target gas, and the sensitivity to the water vapor is different, and the physical quantity related to the concentration of the detection target gas and the humidity of the detection target gas Based on the detection value before and after the change of the detection value output by each of the plurality of gas sensors that detect the physical quantity corresponding to the related physical quantity and output the detection value, before and after the change of the detection value Humidity calculating means for calculating a physical quantity related to the humidity in each;
A gas concentration calculation means for calculating a physical quantity related to the concentration of the detection target gas before and after the change of the detection value based on the detection value of the gas sensor before and after the change of the detection value; and Based on the ratio of the change amount of the physical quantity related to the concentration of the detection target gas calculated by the gas concentration calculation means and the change amount of the physical quantity related to the humidity calculated by the humidity calculation means, the detection target A program for functioning as a gas concentration detection means for detecting the gas concentration.

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