JP2005241540A - Gas concentration measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas concentration measuring apparatus for reducing a development period following the correspondence, reducing working hours, and improving reliability, when performing application measurement in the combination of a plurality of gas sensors. <P>SOLUTION: In the hydrogen concentration measuring apparatus 1, a first extension substrate 9 that is an extension substrate for limiting current type hydrogen sensors is detachably connected to a universal substrate 7 as a main configuration, and a limiting current type hydrogen sensor 17 for measuring hydrogen concentration that is the main measurement target is connected to the first extension substrate 9. Further, a second extension substrate 11 that is an extension substrate for impedance change type moisture sensors is detachably connected to the universal substrate 7 in addition to the main configuration, and an impedance change type moisture sensor 19 for measuring vapor concentration that is a sub measurement target is connected to the second extension substrate 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the present invention, for example, in a gas such as a fuel gas supplied to or discharged from a fuel cell or an exhaust gas of an internal combustion engine, the concentration of a predetermined gas, such as hydrogen gas or ammonia gas, is accurately measured. The present invention relates to a gas concentration measuring apparatus that can measure well.

  Conventionally, in a gas concentration measuring apparatus that is connected to a gas concentration sensor and measures the gas concentration, sufficient measurement accuracy has been obtained when the gas concentration sensor is used in one environment, but in another environment, It is known that sufficient measurement accuracy cannot be obtained due to the influence of the disturbing elements.

For example, what can be measured with high accuracy in an atmospheric environment may be deteriorated in the exhaust gas environment of an automobile due to the influence of interference gas.
As a method for solving this problem, it is conceivable to improve the original measurement accuracy by simultaneously measuring the disturbing element as the second measurement object and performing correction based on the measurement result.

  However, a gas concentration measurement device developed specifically for a single measurement target (for example, hydrogen gas) requires the redevelopment of a measurement circuit by adding a new measurement target (for example, water vapor), and the countermeasures are not easy. Absent.

  Separately from this, for example, with respect to measuring devices that measure clock motors, clock circuits, and other electronic components, and particularly for measuring devices that perform measurement, the development lead time is shortened and the reliability is improved. An improved technique has been proposed (see Patent Document 1).

With this technology, basic performance commonly used for various measurements is given to the parent board, dedicated functions directly related to measurement of a predetermined content are given to the child board, and the child board is mounted on the parent board. One measurement circuit is formed.
JP-A-8-327759 (Page 5, FIG. 9)

  However, in the gas concentration measuring apparatus that measures the gas concentration by using a plurality of gas sensors, there has been no investigation and development of techniques such as how to use the electronic circuit board.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to reduce the development period, man-hour reduction, and reliability associated with the corresponding measurement in the case of application measurement when a plurality of gas sensors are combined. It is providing the gas concentration measuring apparatus which can improve.

  (1) The invention of claim 1 is a gas concentration measuring device for obtaining a concentration of a target gas to be measured by processing a signal of a gas sensor, and a plurality of measurement contents including the concentration of the target gas are different. An electronic circuit unit for inputting a signal of a gas sensor and performing an arithmetic process for obtaining a concentration of the target gas based on a relationship between information obtained from the signal of each gas sensor, and as the electronic circuit unit, Using a general-purpose board having a basic function common to a plurality of different gas sensors and a plurality of extension boards having a dedicated function separately required for each of the different gas sensors, The gist of the gas concentration measuring apparatus is characterized in that the extended substrate is detachably attached.

  In the present invention, since the expansion board corresponding to different gas sensors is detachably attached to the general-purpose board, when applying measurement when combining different gas sensors, the development period associated with the correspondence is reduced, the man-hours are reduced, and Reliability can be improved.

  In other words, it is necessary to change the circuit with the addition of the gas to be measured (and hence the gas sensor) by configuring the general-purpose board and a plurality of expansion boards to form one measurement circuit (electronic circuit unit). In this case, the conventional general-purpose board and the extension board can be used as they are. That is, since it is only necessary to newly develop an expansion board according to the changed contents, the development period can be shortened and the man-hours can be reduced.

  In addition, the general-purpose board and expansion board used before the change have been established for reliability of operation before the change, and when all of them are newly developed by configuring one measurement circuit together Alternatively, the reliability of the measuring apparatus can be improved as compared with the case where a conventional extension board is redeveloped.

  Furthermore, by making it possible to measure different measurement objects using independent expansion boards corresponding to each gas sensor, the once developed expansion board is a measuring device that requires a corresponding gas sensor. Can be reused and no new development is required.

  (2) The invention of claim 2 is based on the relationship between information obtained from the signals of the plurality of different gas sensors, the gas concentration information by the gas sensor related to the target gas, the gas concentration by another gas sensor or The gist of the gas concentration measuring device according to claim 1, wherein the gas concentration measuring device according to claim 1 is corrected based on gas state information.

  The present invention uses a main gas sensor for determining the concentration of a target gas, measures the gas concentration serving as the base of the target gas, and provides information on the gas concentration serving as the base (for example, hydrogen gas concentration), Even if the measurement atmosphere (measured gas) changes, the accuracy can be improved by correcting it with information on other gas concentrations (for example, water vapor concentration) and gas states (for example, air-fuel ratio and temperature) obtained by other gas sensors. The target gas concentration can be obtained well.

  (3) The invention of claim 3 is characterized in that the hydrogen gas concentration information obtained by the gas sensor related to the target gas is corrected by the water vapor concentration information obtained by the other gas sensor. The gist of the gas concentration measuring device according to Item 2 is used.

  The present invention exemplifies a method for measuring the hydrogen gas concentration. Usually, the hydrogen gas concentration in the gas to be measured is affected by the water vapor concentration, so that by performing this correction, the hydrogen gas concentration can be obtained with high accuracy.

  (4) The invention of claim 4 corrects the ammonia gas concentration information obtained by the gas sensor related to the target gas by the water vapor concentration information or the air-fuel ratio information obtained by the other gas sensor. The gist of the gas concentration measuring apparatus according to claim 2 is characterized.

  The present invention exemplifies a method for measuring the ammonia gas concentration. Usually, the ammonia gas concentration in the gas to be measured is affected by the water vapor concentration or the air-fuel ratio, so that the ammonia gas concentration can be accurately obtained by performing this correction.

  (5) According to the invention of claim 5, the connector mounted on the general-purpose board and the connector mounted on the plurality of expansion boards are directly fitted to electrically connect the general-purpose board and the plurality of expansion boards. The gist of the gas concentration measuring apparatus according to any one of claims 1 to 4, wherein the electronic circuit board is mechanically integrated.

  The present invention exemplifies the configuration of an electronic circuit board. In the present invention, since the connector mounted on the general-purpose board and the connector mounted on the plurality of expansion boards are directly fitted and integrated, the electronic circuit board can be made compact.

  Even if different gas sensors are used, a plurality of the same type (or the same) gas sensors are used, and expansion boards corresponding to the respective gas sensors can be detachably connected to general-purpose boards (for example, fitted and integrated with connectors). Good. Thereby, for example, the hydrogen gas concentration at each position of the fuel cell system can be measured with one electronic circuit board.

  Next, an example (example) of the best mode of the present invention will be described.

In this embodiment, a hydrogen concentration measuring device using a limiting current type hydrogen sensor is taken as an example of the gas concentration measuring device.
a) First, the external configuration of the hydrogen concentration measuring apparatus according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 1A, the hydrogen concentration measuring apparatus 1 according to the present embodiment corresponds to a general-purpose substrate 7 that is a basic measurement function unit and an after-mentioned gas sensor as an electronic circuit unit 5 in a housing 3. The first extension board 9 and the second extension board 11 are provided as the dedicated measurement function unit. As shown in FIG. 1B, a display unit 13 and an operation unit 15 are provided on the front surface of the hydrogen concentration measuring apparatus 1.

  In the first extension board 9 and the second extension board 11, a pair of extension side connectors 16 are arranged on the lower surface side of each of the extension boards 9, 11 (the back side of the paper in FIG. 1A), A total of four general-purpose connectors 18 are arranged on the upper surface side of the general-purpose substrate 7 (the front side in FIG. 1A) corresponding to the expansion-side connector 16. In the figure, these connectors 16 and 18 are shown overlapping.

  Then, the expansion side connector 16 and the general purpose side connector 18 are pressed against the paper thickness side of FIG. 1A and are detachably fitted as shown in FIG. The first extension board 9 and the second extension board 11 are configured as an electrically and mechanically integrated board.

  In other words, as shown in FIG. 3, the hydrogen concentration measuring apparatus 1 of the present embodiment has a main configuration in which a first extension board 9 which is an extension board for a limiting current type hydrogen sensor is connected to a general-purpose board 7, and the first A limiting current type hydrogen sensor 17 for measuring a hydrogen gas concentration (hydrogen concentration) as a main measurement target is connected to one extended substrate 9.

  Further, in addition to the main configuration, a second extension board 11 which is an extension board for an impedance change type humidity sensor is connected to the general-purpose board 7, and the water vapor concentration which is a sub-measurement target is measured on the second extension board 11. Therefore, an impedance change type humidity sensor 19 is connected.

b) Next, the configuration of the hydrogen concentration measuring apparatus 1 will be described in more detail.
As shown in FIG. 4, the general-purpose board 7 includes a microcontroller 21 (which performs gas concentration calculation processing, etc.), a switch input circuit 23, a display output circuit 25, a communication input / output circuit 27, a clock circuit 29, a memory 31, and a power source. The circuit board 33 is provided with I / O 35, A / D converters 37 and 39, D / A converters 41 and 43, and PWM 45 and 47. A computer 49 is connected.

The essential components in the general-purpose board 7 are a microcontroller 21, I / O 35, A / D converters 37 and 39, and D / A converters 41 and 43.
The first extension board 9 includes a signal switching circuit 51, a sensor voltage input circuit 53, a sensor impedance input circuit 55, a pump current input circuit 57, a pump voltage input circuit 59, a pump voltage output circuit 61, and sample hold circuits 63 to 69. A heater voltage output circuit 71 and a measurement signal output circuit 75 (connected to the external measuring device 73).

  The essential components of the first extension board 9 are a signal switching circuit 51, a sensor voltage input circuit 53, a pump current input circuit 57, a pump voltage output circuit 61, sample hold circuits 63 and 67, and a measurement signal output circuit 75.

Further, the limit current type hydrogen sensor 17 includes a limit current type hydrogen sensor element 77 and a heater element 79. The heater element 79 is not essential.
Here, the configuration for measuring the sensor impedance on the limit current type hydrogen sensor 17 side (sensor impedance input circuit 55 and the like) and the configuration for controlling the heater element 79 (heater voltage output circuit 71 and the like) are limited currents. It is used for temperature control for preventing condensation of the hydrogen sensor element 77. The pump voltage input circuit 59 is used to monitor its own output.

  On the other hand, the second expansion board 11 includes a platinum resistance input circuit 81, a sensor impedance input circuit 83, a log conversion circuit 85 (which performs logarithmic conversion of the exponential characteristic of the sensor), an AC voltage output circuit 87, a heater voltage output circuit 89, A measurement signal output circuit 93 (connected to the external measuring device 91) is provided.

The essential components in the second extension substrate 11 are a platinum resistance input circuit 81, a sensor impedance input circuit 83, a log conversion circuit 85, and an AC voltage output circuit 87.
The impedance change humidity sensor 19 further includes a platinum resistor element 95 (for temperature correction), an impedance change humidity sensor element 97, and a heater element 99. The heater element 99 is not essential.

  Here, the configuration (heater voltage output circuit 89 and the like) for controlling the heater element 99 on the impedance change type humidity sensor 19 side is used for heat cleaning (burning removal) of the sensor deposit.

  Note that the measurement signal output circuits 75 and 93 exist on both the expansion boards 9 and 11, respectively, but when used in combination, either one may be provided. In addition, the A / D converters 37 and 39 and the D / A converters 41 and 43 are described with two PWMs 45 and 47 for convenience. However, since the number of channels is actually a problem, they may be shared.

c) Next, the measurement principle of the hydrogen concentration measuring apparatus 1 of the present embodiment will be described.
The limiting current type hydrogen sensor 17 is a sensor that detects the concentration by utilizing the fact that the current flowing when the limiting current type hydrogen sensor element 77 is controlled to a constant voltage is proportional to the hydrogen concentration. It has been found to be concentration dependent.

  When the water vapor concentration in the measurement atmosphere (gas to be measured) is fixed to some extent, the dependence is regarded as an allowable error, and the hydrogen concentration is calculated based on the relationship between the fixed current and the hydrogen concentration. In this case, the hydrogen concentration measuring apparatus 1 measures the hydrogen concentration using the functions of the general-purpose substrate 7 and the first extension substrate 9.

  However, when there is a measurement request under conditions in which the water vapor concentration in the gas to be measured fluctuates greatly, the water vapor concentration is measured using a separate impedance change type humidity sensor 19, and the relationship between the current and the hydrogen concentration is obtained. Correction is made accordingly and the hydrogen concentration is detected. In this case, the hydrogen concentration measuring apparatus 1 measures the hydrogen concentration using the functions of the general-purpose substrate 7 and the first and second extension substrates 9 and 11.

Details will be described below.
The limiting current type hydrogen sensor element 77 of the limiting current type hydrogen sensor 17 is mainly composed of a proton conductor 101, a first electrode 103, a second electrode 105, and a reference electrode 107, as shown in FIG. Is sandwiched by a support 111 provided with a diffusion rate-determining portion 109. Note that the second electrode 105 and the reference electrode 107 may be integrated.

  In this limiting current type hydrogen sensor 17, when a pump voltage Vp is applied between the first electrode 103 and the second electrode 105, hydrogen molecules in the gas to be measured introduced through the diffusion rate-determining unit 109 are converted into the first electrode. It decomposes on 103 and becomes proton, is pumped through the proton conductor 101 to the second electrode 105 side, and a circuit current (pump current) Ip flows. Although Ip increases as the applied voltage is increased, diffusion of the introduced gas is hindered by the diffusion rate-determining unit 109, so that it has a region that is constant above a certain voltage level. This constant Ip is called a limiting current. As shown in FIG. 6, since Ip is approximately proportional to the hydrogen concentration in the gas to be measured, the hydrogen concentration can be measured by measuring the limit current.

  Further, as shown in FIG. 7, the limit current type hydrogen sensor 17 increases the sensor output when the water vapor concentration in the gas to be measured increases. That is, since protons move in the proton conductor 101 with water molecules, when the water vapor concentration in the gas to be measured increases, the number of water molecules pumped increases with the movement of protons. The sensor output increases because a new gas to be measured flows into the element in a manner that compensates for water molecules that have escaped by pumping.

On the other hand, in the impedance change type humidity sensor 19, a ceramic type moisture sensitive material such as Al ₂ O ₃ type is used as the moisture sensitive material, but these use the adsorption / desorption reaction of water molecules, Moisture is detected by a change in electrical resistance.

Accordingly, the impedance change type humidity sensor 19 can determine the water vapor concentration in the gas to be measured from the change in impedance.
The hydrogen concentration is corrected by the water vapor concentration using the outputs of the sensors 17 and 19, and the correction is performed according to the following procedures (1) to (8).

(1) The pump current Ip of the limiting current type hydrogen sensor 17 is measured.
(2) The hydrogen concentration H is calculated from the pump current Ip by polynomial approximation.
(3) The sensor impedance Zs of the impedance change type humidity sensor 19 is measured.

(4) The resistance Rpt of the platinum resistor element 95 of the impedance change type humidity sensor 19 is measured.
(5) The temperature T of the gas to be measured is calculated from the resistance Rpt by an approximate polynomial.

(6) From the sensor impedance Zs and temperature T, three-dimensional map conversion (X axis: Zs,
The water vapor concentration Hum is calculated from Y axis: T, Z axis: Hum).
(7) The hydrogen concentration correction gain α is calculated from the water vapor concentration Hum by two-dimensional map conversion.

(8) Using the hydrogen concentration H and the correction gain α, a corrected hydrogen concentration H ′, which is an accurate hydrogen concentration after correction, is calculated by the equation “H ′ = α × H”.
e) As described above, in this embodiment, the limiting current type hydrogen sensor 17 measures the base hydrogen concentration H, and the impedance change type humidity sensor 19 uses the sensor impedance Zs and the temperature T corresponding to the water vapor concentration. Since the more accurate corrected hydrogen concentration H ′ is obtained based on these values, the accurate hydrogen concentration can always be obtained even if the state of the measured gas such as the water vapor concentration fluctuates. .

  In this embodiment, the first extension board 9 (corresponding to the limiting current type hydrogen sensor 17) and the second extension board 11 (corresponding to the impedance change type humidity sensor 19) are connected to the general-purpose board 7 with the connectors 16, 18 respectively. Since it is detachably mounted via a gas sensor, it is possible to shorten the development period, reduce the man-hours, and improve the reliability in response to applied measurement when a plurality of different types of gas sensors 17 and 19 are combined. Can do.

  For example, first, when the second expansion substrate 11 for the impedance change type humidity sensor 19 is added to the hydrogen concentration measuring apparatus 1 including the general-purpose substrate 7 and the first expansion substrate 9 for the limiting current type hydrogen sensor 17. Therefore, since the general-purpose board 7 and the first extension board 9 can be used as they are, that is, it is only necessary to newly develop the second extension board 11 according to the change contents. Shortening and man-hour reduction can be realized.

  In addition, the general-purpose board 7 and the first extension board 9 used before the change have been established in the reliability of the operation before the change. The reliability of the hydrogen concentration measuring apparatus 1 can be improved as compared with the case of newly developed or the redevelopment of the extended substrate 7.

  Furthermore, by making it possible to measure different measurement objects using the independent expansion boards 9 and 11 (corresponding to the sensors 17 and 19), the expansion boards 9 and 11 that have been developed once are It can be reused in a measuring device that requires a gas sensor corresponding to the measurement object, and no new development is required.

Next, the second embodiment will be described, but the description of the same parts as the first embodiment will be omitted.
In this embodiment, an ammonia concentration measuring device using an impedance change type ammonia sensor is taken as an example of the gas concentration measuring device.

a) First, the configuration of the ammonia concentration measuring apparatus according to the present embodiment will be described with reference to FIG.
As shown in FIG. 8, the ammonia concentration measuring apparatus 201 of the present embodiment has a main configuration in which a first extension board 205, which is an extension board for an impedance change type ammonia sensor, is connected to a general-purpose board 203, and its first extension. The substrate 205 has a configuration in which an impedance change type ammonia sensor 207 for measuring an ammonia concentration as a main measurement target is connected.

  Further, in addition to the main configuration, a second extension board 209 which is an extension board for a limit current type linear A / F (air / fuel ratio) sensor is connected to the general-purpose board 203, and the second extension board 209 is connected to the sub measurement target. The limit current type linear A / F sensor 211 for measuring the air-fuel ratio is connected.

b) Next, the configuration of the ammonia concentration measuring apparatus 201 will be described in more detail.
As shown in FIG. 9, the general-purpose board 203 includes a microcontroller 213 (which performs gas concentration calculation processing, etc.), a switch input circuit 215, a display output circuit 217, a communication input / output circuit 219, a clock circuit 221, a memory 223, a power supply The circuit board 225 includes an I / O 227, A / D converters 229 and 231, D / A converters 233 and 235, PWM 237 and 239, and the general-purpose board 203 is connected to a personal computer via a communication input / output circuit 219. A computer 241 is connected.

  The essential components of the general-purpose board 203 are a microcontroller 213, an I / O 227, an A / D converter 229, 231, a D / A converter 233 235, and a PWM 237 239.

  The first extension board 205 includes a platinum resistance input circuit 243, a sensor impedance input circuit 245, an AC voltage output circuit 249, a heater voltage output circuit 251, and a measurement signal output circuit 255 (connected to the external measuring device 253). (Required configuration)

  Furthermore, the impedance variable ammonia sensor 207 includes a platinum resistor element 257, an impedance variable ammonia sensor element 259, and a heater element 261 (essential configuration).

  On the other hand, the second expansion board 209 includes a sensor voltage input circuit 263, a pump current input circuit 265, a sensor impedance input circuit 267, a pump voltage output circuit 269, a heater voltage output circuit 271, and a measurement (connected to an external measuring device 273). A signal output circuit 275 is provided (required configuration other than the measurement signal output circuit 275).

Further, the limit current type linear A / F sensor 211 includes a limit current type linear A / F sensor element 277 and a heater element 279 (essential configuration).
Here, it is necessary to adjust the temperature of the impedance change type ammonia sensor 207 to about 400 ° C. and the limit current type linear A / F sensor 211 to a constant sensor impedance, so that the heater elements 261 and 279 and the heater voltage output circuit 251, A control unit such as 271 is an essential circuit.

c) Next, the measurement principle of the ammonia concentration measuring apparatus 201 of the present embodiment will be described.
The impedance change type ammonia sensor 207 is a sensor that detects the concentration by utilizing the fact that the element impedance is proportional to the ammonia concentration, and is known to be dependent on the water vapor concentration from the characteristics of the element material.

  The correction method is basically the same as that of the hydrogen concentration measuring apparatus of the first embodiment. However, in this embodiment, the target is to measure the ammonia concentration in the exhaust gas of the automobile. Since the water vapor concentration is correlated with the air-fuel ratio (A / F), the signal from the limit current type linear A / F sensor 211 is used to correct the water vapor concentration dependency.

Therefore, in this case, the ammonia concentration measuring apparatus 201 measures the ammonia concentration using the functions of the general-purpose substrate 203 and the first and second expansion substrates 205 and 209.
Details will be described below.

The impedance change-type ammonia sensor 207 uses a solid superacid material whose main component is an oxide such as ZrO ₂ and whose main component is WO ₃ or the like as its sensitive material. As shown in FIG. Then, the sensor output (impedance) decreases.

  The impedance change type ammonia sensor 207 uses a change in impedance caused by adsorption of ammonia on a sensitive material. That is, it is presumed that when ammonia is adsorbed on an acid point of a solid superacid material, proton hopping conduction is assisted, so that impedance is lowered.

In addition, in the impedance change type ammonia sensor 207, when H ₂ O is present, protons are decomposed and generated, and the impedance is changed by hopping conduction in the same manner as that decomposed from ammonia. That is, as shown in FIG. 10, there is a property that the sensor output (impedance) decreases when H ₂ O in the gas to be measured increases, that is, water vapor dependency.

On the other hand, the limit current type linear A / F sensor 211 uses partially stabilized ZrO ₂ , and in addition to the principle of the ZrO ₂ oxygen sensor generally used in the exhaust system, a voltage is applied to the ZrO ₂ solid electrolyte. This is a sensor that can detect the air-fuel ratio in a wide area by combining the function of pumping oxygen in the test gas by applying it.

  The limit current (pump current) Ip of the limit current type linear A / F sensor 211 is proportional to the oxygen concentration (and hence the air-fuel ratio). That is, the pump current Ip is proportional to the air-fuel ratio, and since the air-fuel ratio is correlated with the water vapor concentration, the water vapor concentration can be determined from the pump current Ip.

The ammonia concentration is corrected using the outputs of the sensors 207 and 211. The correction is performed according to the following procedures (1) to (4).
(1) The impedance Zs of the impedance change type ammonia sensor 207 is measured.

(2) The pump current Ip of the limit current type linear A / F sensor 211 is measured.
(3) The air-fuel ratio λ is calculated from the pump current Ip by a polynomial approximation formula.
(4) The ammonia concentration NH ₃ is calculated from the impedance Zs and the air-fuel ratio λ by three-dimensional map conversion (X axis: Zs, Y axis: λ, Z axis: NH ₃ ).

  d) Thus, in this embodiment, the ammonia concentration is obtained based on the impedance Zs of the impedance change type ammonia sensor 207 and the air-fuel ratio λ obtained from the pump current Ip of the limit current type linear A / F sensor 211. Therefore, even if the state of the gas to be measured such as the water vapor concentration fluctuates, an accurate ammonia concentration can always be obtained.

Also in the present embodiment, similar to the first embodiment, there is an effect that the development period can be shortened and the man-hours can be reduced.
In addition, this invention is not limited to the said Example at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from the summary of this invention.

  For example, as shown in FIG. 11, the hydrogen concentration may be measured using a plurality of similar hydrogen concentration sensors 301 and 303. In this case, an extension board corresponding to each of the hydrogen concentration sensors 301 and 303 is prepared, and the extension board is mounted on a general-purpose board.

  For example, in the evaluation of the city gas reforming fuel cell 305, the hydrogen concentration sensors 301 and 303 are arranged at the fuel inlet 315 and the outlet 317 of the anode 319 of the fuel cell 305, respectively, so that the measurement of hydrogen utilization efficiency and the optimum operation are performed. When there is a demand to measure the supply hydrogen concentration in a state (high hydrogen utilization efficiency), the evaluation can be performed by combining a general-purpose substrate and two expansion substrates for limiting current type hydrogen sensors.

  Specifically, the amount of city gas sent to the reformer 309 is adjusted using a mass flow controller 307 for obtaining constant power. The city gas is converted into a fuel gas containing hydrogen by the reformer 309 and supplied to the fuel inlet 315 of the fuel cell 305. Then, hydrogen is consumed by power generation, and the exhaust gas that is the remaining component is discharged from the fuel outlet 317 and burned by the burner 311.

  Further, if the hydrogen concentration of the hydrogen concentration sensors 301 and 303 is measured by the measuring device 313 with the city gas supply amount to the reformer 309 kept constant, the hydrogen utilization efficiency can be calculated from the difference.

  In other words, if the mass flow controller 307 is controlled so that the hydrogen concentration of the hydrogen concentration sensor 303 is lowered within a range where necessary power can be obtained, and the hydrogen concentration of the hydrogen concentration sensor 301 is measured in this state, the optimum operation state ( The supply hydrogen concentration at high hydrogen utilization efficiency can be measured.

The hydrogen concentration measuring apparatus of Example 1 is shown, (a) is a top view which shows the state which opened the upper part, (b) is the front view. It is explanatory drawing which shows the mounting state of the general purpose board | substrate and expansion board in Example 1. FIG. It is a block diagram which shows the main structures of the hydrogen concentration measuring apparatus of Example 1. FIG. It is a block diagram which shows the detailed structure of the hydrogen concentration measuring apparatus of Example 1. FIG. It is explanatory drawing which shows the limiting current type hydrogen sensor used in Example 1. FIG. 3 is a graph showing characteristics of a limiting current type hydrogen sensor used in Example 1. FIG. 3 is a graph showing characteristics of a limiting current type hydrogen sensor used in Example 1. FIG. It is a block diagram which shows the main structures of the ammonia concentration measuring apparatus of Example 2. FIG. It is a block diagram which shows the detailed structure of the ammonia concentration measuring apparatus of Example 2. FIG. 6 is a graph showing characteristics of an impedance change type ammonia sensor used in Example 2. It is explanatory drawing which shows the example using a pair of hydrogen concentration sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydrogen concentration measuring device 7, 203 ... General-purpose board | substrate 9,205 ... 1st extended board 11,209 ... 2nd extended board 17 ... Limit current type hydrogen sensor 19 ... Impedance change type humidity sensor 201 ... Ammonia concentration measuring apparatus 207 ... Impedance change type ammonia sensor 211 ... Limit current type linear A / F sensor

Claims (5)

In the gas concentration measurement device that determines the concentration of the target gas to be measured by processing the signal of the gas sensor,
Inputs signals of a plurality of gas sensors having different measurement contents including the concentration of the target gas, and performs calculation processing for obtaining the concentration of the target gas based on the relationship between the information obtained from the signals of the gas sensors. With an electronic circuit part,
As the electronic circuit unit, using a general-purpose board having a basic function common to the plurality of different gas sensors, and a plurality of expansion boards having a dedicated function separately required for each of the different gas sensors,
A gas concentration measuring apparatus, wherein the plurality of expansion boards are detachably attached to the general-purpose board.   Based on the relationship between the information obtained from the signals of the different gas sensors, the gas concentration information by the gas sensor related to the target gas is corrected by the gas concentration or gas state information by another gas sensor. The gas concentration measuring apparatus according to claim 1.   3. The gas concentration measuring apparatus according to claim 2, wherein the hydrogen gas concentration information obtained by the gas sensor related to the target gas is corrected by the water vapor concentration information obtained by the other gas sensor.   The information on the ammonia gas concentration obtained by the gas sensor related to the target gas is corrected by the information on the water vapor concentration or the information on the air-fuel ratio obtained by the other gas sensor. Gas concentration measuring device.   The connector mounted on the general-purpose board and the connector mounted on the plurality of extension boards are directly fitted to form an electronic circuit board that is electrically and mechanically integrated with the general-purpose board and the plurality of extension boards. The gas concentration measuring device according to any one of claims 1 to 4, wherein