Combustible gas measuring device and combustible gas measurement system

Abstract

To provide a combustible gas measuring device and a combustible gas measurement system that can be miniaturized and improves measurement precision.SOLUTION: A combustible gas measuring device 200 has: a casing section 100 that has a gas introduction opening 100h connected to the outside and allows a measurement chamber 100s into which gas flows from the gas introduction opening to be formed in itself; and a combustible gas sensor 10 that is inside the measurement chamber and detects object gas comprising combustible gas. The combustible gas measuring device 200 further has an oxygen pump cell 20 that separates the measurement chamber and the outside and can load and unload oxygen between the outside and the measurement chamber, and the oxygen pump cell has an oxygen ion conductive solid electrolyte body and a pair of electrodes.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a flammable gas measuring device and a flammable gas measuring system for detecting the concentration of flammable gas present in a detected atmosphere.

Background Art

[0002] As a gas sensor for detecting the gas concentration of flammable gas present in a detected atmosphere, various gas sensors are known, such as a semiconductor gas sensor using a metal oxide semiconductor such as tin oxide (SnO2), a thermal conductivity gas sensor equipped with a heating resistor, and a catalytic combustion gas sensor. In particular, when these gas sensors are manufactured using MEMS technology, the gas sensor and thus the entire flammable gas measuring device can be miniaturized and power-saving.

[0003] By the way, the flammable gas sensor is arranged in the measurement chamber inside the housing of the flammable gas measuring device. However, when the dimensions of the measuring device are miniaturized, the measurement chamber also becomes smaller, making it difficult for the detected gas to flow into the measurement chamber, and the detection accuracy decreases. Therefore, it is conceivable to forcibly introduce the detected gas into the measurement chamber. As such a technology, a gas detection device has been developed in which a suction pump is connected to a gas flow path in which a gas sensor is arranged, and the detected gas is physically sucked into the gas flow path (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when a suction pump is connected to the gas detection device, there is a problem that the entire device becomes large-sized, or the suction pump has to be prepared separately from the gas detection device, which is troublesome for installation and manufacture. In addition, the atmosphere inside the measurement chamber after measuring the detected gas is in a state where the concentration of the detected gas has decreased and the concentration of interfering gases and the like has increased, and there is a problem that it does not reflect the actual external atmosphere (gas concentration) during the next measurement.

[0006] Furthermore, for example, a semiconductor-type gas sensor has a structure in which a pair of detection electrodes is covered with a gas detection layer made of a metal oxide semiconductor such as tin oxide that exhibits gas detection ability. As the flammable gas is detected, oxygen on the surface of the gas detection layer becomes deficient. For this reason, calibration is required to supply oxygen to the surface of the gas detection layer to restore the gas detection ability, but there is a problem that the calibration does not proceed sufficiently simply by sucking the detected gas. That is, an object of the present invention is to provide a flammable gas measuring device and a flammable gas measuring system that can be miniaturized and have improved measurement accuracy.

Means for Solving the Problems

[0007] In order to solve the above problems, a flammable gas measuring device of the present invention includes a housing portion having a gas inlet communicating with the outside, and a measurement chamber into which gas flows from the gas inlet is formed inside the housing portion, and a flammable gas sensor that detects a target gas composed of flammable gas inside the measurement chamber. The flammable gas measuring device further includes an oxygen pump cell that separates the measurement chamber from the outside and allows oxygen to be exchanged between the outside and the measurement chamber, and the oxygen pump cell includes an oxygen ion conductive solid electrolyte body and a pair of electrodes.

[0008] According to this flammable gas measuring device, even without separately providing a suction pump or the like, by pumping out oxygen from the measurement chamber with the oxygen pump cell, gas can be forcibly made to flow into the measurement chamber from the gas inlet by negative pressure. In addition, the atmosphere inside the measurement chamber after measurement is a state in which the concentration of the target gas has decreased and the concentration of interfering gases and the like has increased. Therefore, by pumping oxygen into the measurement chamber with the oxygen pump cell, the gas in the measurement chamber can be discharged from the gas inlet, reducing the influence of interfering gases during the next measurement and reflecting the actual external atmosphere (gas concentration). As a result, it is possible to miniaturize the combustible gas measuring device and the combustible gas measuring system, and improve the measurement accuracy.

[0009] In the combustible gas measuring device of the present invention, an adsorption part for adsorbing the target gas may be arranged inside the measurement chamber. According to this combustible gas measuring device, by measuring the combustible gas sensor while desorbing the target gas from the adsorption part, even if the concentration of the target gas in the gas is low, the target gas adsorbed by the adsorption part and locally increased in concentration can be measured, so that the measurement accuracy is improved and the lower limit concentration of the measurement is reduced.

[0010] In the combustible gas measuring device of the present invention, the oxygen pump cell may be of the MEMS (Micro Electro Mechanical Systems) type. According to this combustible gas measuring device, the oxygen pump cell, and thus the combustible gas measuring device, can be further miniaturized.

[0011] The combustible gas measuring system of the present invention is a combustible gas measuring system including the combustible gas measuring device and a control unit for controlling the combustible gas measuring device, wherein the control unit performs a first process of pumping out the oxygen inside the measurement chamber to the outside with the oxygen pump cell, a second process of measuring the combustible gas sensor after the first process, and a third process of pumping external oxygen into the measurement chamber with the oxygen pump cell after the second process.

[0012] According to this flammable gas measurement system, by performing the first process, oxygen can be pumped out from the measurement chamber by the oxygen pump cell without separately providing a suction pump or the like, and the gas can be forced to flow into the measurement chamber from the gas inlet due to negative pressure. Also, in the second process, the atmosphere inside the measurement chamber after measurement is in a state where the concentration of the target gas has decreased and the concentration of interfering gases or the like has increased. Therefore, by performing the third process to pump oxygen into the measurement chamber, the gas in the measurement chamber can be discharged from the gas inlet, reducing the influence of interfering gases during the next measurement and reflecting the actual external atmosphere (gas concentration). As a result, it is possible to miniaturize the flammable gas measuring device and the flammable gas measurement system, and improve the measurement accuracy.

[0013] The flammable gas measurement system of the present invention further includes the adsorption unit, and the control unit executes a fourth process of causing the oxygen pump cell to pump external oxygen into the measurement chamber after the first process and before the second process, and in the second process, the measurement of the flammable gas sensor may be performed while desorbing the target gas from the adsorption unit.

[0014] According to this flammable gas measurement system, by providing an adsorption unit in the flammable gas measuring device and performing the fourth process, as much interfering gas remaining in the measurement chamber as the target gas adsorbed by the adsorption unit can be excluded from the measurement chamber, reducing the influence of the interfering gas on the measurement. Furthermore, when an adsorption unit is provided, in the second process, by performing the measurement of the flammable gas sensor while desorbing the target gas from the adsorption unit, even if the concentration of the target gas in the gas is low, the target gas adsorbed by the adsorption unit and locally increased in concentration can be measured, so that the measurement accuracy is improved and the lower limit concentration of the measurement is decreased.

Advantages of the Invention

[0015] According to this invention, a flammable gas measuring device and a flammable gas measurement system that can be miniaturized and have improved measurement accuracy can be obtained.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a flammable gas measurement system 300 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line A-A of the flammable gas measurement device 200 in FIG. 1, FIG. 3 is a cross-sectional view showing the configuration of the flammable gas sensor 10, and FIG. 4 is a cross-sectional view showing the configuration of the oxygen pump cell 20. The flammable gas measurement system 300 (flammable gas measurement device 200) detects the concentration of flammable gas and is used, for example, for the health management of humans, animals, and plants, the quality control of food, and the monitoring of air quality.

[0018] As shown in FIG. 1, the flammable gas measurement system 300 includes a flammable gas measurement device 200 and a control unit (controller) 250 that is electrically connected to the flammable gas measurement device 200 and controls the flammable gas measurement device 200. The control unit 250 can be connected to the flammable gas measurement device 200 by, for example, a connector cable 220 and a connector 220c (FIG. 2).

[0019] The flammable gas measuring device 200 generally includes a housing part 100 in a box shape, a flammable gas sensor 10 disposed inside the housing part 100 for detecting a target gas composed of flammable gas, an oxygen pump cell 20 disposed inside the housing part 100, and an adsorption part 30 disposed inside the housing part 100 for adsorbing the target gas. The housing part 100 has a gas inlet 100h communicating with the outside (atmosphere), and a measurement chamber 100s into which gas flows from the gas inlet 100h is formed inside itself. In this example, the gas inlet 100h opens in a rectangular shape on one side surface of the housing part 100, the measurement chamber 100s extends from the gas inlet 100h toward the opposite surface of the housing part 100, and the measurement chamber 100s is a non-through hole that does not penetrate to the opposite surface. The housing part 100 can be formed of an insulator obtained by laminating and firing ceramic green sheets such as alumina.

[0020] The flammable gas sensor 10 and the oxygen pump cell 20 are respectively disposed on the lower surface of the measurement chamber 100s such that the flammable gas sensor 10 is close to the gas inlet 100h. On the other hand, the adsorption part 30 is disposed on the upper surface of the measurement chamber 100s so as to be substantially opposed to the flammable gas sensor 10. Here, as shown in FIG. 2, a rectangular through hole 100h2 opens downward from the lower surface of the measurement chamber 100s. The oxygen pump cell 20 is disposed covering the through hole 100h2, separating the measurement chamber 100s from the outside.

[0021] Also, a heater 32 for heating the adsorption part 30 is embedded in the upper part of the housing part 100 facing the adsorption part 30. Note that the adsorption part 30 can be, for example, Na-Y type zeolite.

[0022] Furthermore, heater electrodes p1, p3, a gas sensor electrode p2, and an oxygen pump cell electrode p4 are exposed on the lower surface of the housing part 100. The heater electrodes p1 and p3 are respectively connected to the combustible gas sensor 10 and the oxygen pump cell 20, and are electrodes for energizing and heating the heaters of the combustible gas sensor 10 and the oxygen pump cell 20 respectively. The gas sensor electrode p2 is connected to the combustible gas sensor 10, and is an electrode for extracting the detection output by the combustible gas sensor 10. The gas sensor electrode p4 is connected to the oxygen pump cell 20, and is an electrode for controlling the operation of the oxygen pump cell 20 to allow oxygen to flow in and out between the measurement chamber 100s and the outside through the through hole 100h2.

[0023] And these electrodes p1 to p4 are connected to the connector 220c, and are electrically connected to the control unit 250 via the connector cable 220. The control unit 250 is composed of, for example, a circuit board on which a microcomputer and various electronic components are mounted, and is connected to a power source (not shown).

[0024] Next, the combustible gas sensor 10 and the oxygen pump cell 20 will be described. The combustible gas sensor 10 and the oxygen pump cell 20 are rectangular in plan view, and FIGS. 3 and 4 are cross-sectional views taken along a plane perpendicular to this plane.

[0025] As shown in FIG. 3, the combustible gas sensor 10 is a MEMS (Micro Electro Mechanical Systems) type semiconductor gas sensor, and has a structure in which a gas detection layer 1 made of tin oxide that exhibits gas detection ability covers a pair of detection electrodes 3. More specifically, the combustible gas sensor 10 includes a silicon substrate 9 having a diaphragm structure, a SiO2 film 5 laminated on the upper surface of the silicon substrate 9, a pair of detection electrodes 3 formed on the upper surface of the SiO2 film 5, and a gas detection layer 1 covering the detection electrodes 3.

[0026] Also, inside the SiO2 film 5, a heater 7 for heating the gas detection layer 1 to the operating temperature is embedded. The diaphragm is formed so as to have a pyramidal (square pyramid) space from the lower surface to the upper surface of the silicon substrate 9. Here, the pair of detection electrodes 3 consists of two Pt electrodes facing each other in a comb shape, and in FIG. 3, the comb teeth portions of the respective electrodes are alternately arranged.

[0027] On the surface of the heated gas detection layer 1, oxygen ions (O - or O 2- )ox are adsorbed. Then, when the target gas G1 (e.g., H2) composed of a combustible gas comes into contact with the gas detection layer 1, it takes away the oxygen ions ox on the surface of the gas detection layer 1 to become a product Gp (e.g., H2O). At this time, since electricity flows through the gas detection layer 1 from which the oxygen ox has been taken away, the gas can be detected.

[0028] As shown in FIG. 4, the oxygen pump cell 20 is of the MEMS type and has an oxygen ion conductive solid electrolyte body 21 and a pair of electrodes 23, 25. More specifically, the oxygen pump cell 20 has a silicon substrate 29 having a diaphragm structure, an oxygen ion conductive solid electrolyte body 21 laminated on the upper surface of the silicon substrate 29, and a pair of electrodes 23, 25 respectively disposed on the upper and lower surfaces of the oxygen ion conductive solid electrolyte body 21. Further, inside the oxygen ion conductive solid electrolyte body 21, a heater 27 for heating the oxygen ion conductive solid electrolyte body 21 to the operating temperature is embedded. Then, a pump current is passed in the positive or negative direction between the pair of electrodes 23, 25 of the oxygen pump cell 20 to take in and out oxygen (pump out or pump in).

[0029] Next, with reference to FIGS. 5 and 6, an example of the control by the control unit 250 will be described. As shown in FIG. 5(a), before measurement, the external gas G contains the target gas G1 (e.g., H2) and the interfering gas G2 (e.g., CH4) which is not the measurement target. On the other hand, as shown in FIG. 2, oxygen ions ox are adsorbed on the surface of the heated gas detection layer 1 of the combustible gas sensor 10.

[0030] In this state, the control unit 250 causes the oxygen pump cell 20 to pump out the oxygen inside the measurement chamber 100s to the outside (FIG. 5(b), the first process). As a result, the negative pressure causes the external gas G to be drawn into the measurement chamber 100s through the gas inlet 100h, and the target gas G1 (for example, H2) is adsorbed by the adsorption unit 30. Note that the heater 32 is turned off, and the adsorption unit 30 is not heated.

[0031] Next, the control unit 250 causes the oxygen pump cell 20 to pump external oxygen into the measurement chamber 100s through the through-hole 100h2 (FIG. 5(c), fourth process). As a result, the target gas G1 and the interference gas G2 that are not adsorbed by the adsorption unit 30 among the gas G in the measurement chamber 100s are discharged to the outside through the gas inlet 100h. In particular, the interference gas G2 that interferes with the measurement can be removed from the measurement chamber 100s, and the influence of the interference gas G2 on the measurement can be reduced.

[0032] After the fourth process, the control unit 250 performs a measurement of the combustible gas sensor 10 (FIG. 5(d), second process). Here, in the second process, the measurement is performed while the adsorption unit 30 is heated to desorb the target gas G1. As a result, the target gas G1, which is a combustible gas, comes into contact with the gas sensing layer 1 of the combustible gas sensor 10, and removes oxygen ox from the surface of the gas sensing layer 1 to become a product Gp (e.g., H2O). At this time, electricity flows through the gas sensing layer 1 from which oxygen ox has been removed, so that the gas can be detected.

[0033] Furthermore, in the second process, if measurement is performed while heating the adsorption section 30 with the heater 32 to desorb the target gas G1, even if the concentration of the target gas G1 in the gas G is low, the target gas G1 that has been adsorbed by the adsorption section 30 and has a locally high concentration will be measured, thereby improving the measurement accuracy and lowering the lower limit measurement concentration. When the target gas G1 is adsorbed in the adsorption section 30 and measured, the measured concentration differs from the actual concentration of the target gas G1 in the gas G. Conversion between the measured concentration and the actual concentration of the target gas G1 can be calculated using the volume of the measurement chamber 100s, the pumping flow rate of oxygen, and the pumping time.

[0034] After the second process, the control unit 250 causes the oxygen pump cell 20 to suck external oxygen into the measurement chamber 100s through the through-hole 100h2 (Fig. 5(e), the third process). As a result, even if oxygen is lacking on the surface of the gas detection layer 1 of the combustible gas sensor 10 due to measurement, oxygen gas can be introduced into the measurement chamber 100s, so that calibration for supplying oxygen to the surface of the gas detection layer 1 and restoring the gas detection ability can proceed sufficiently.

[0035] Fig. 6 is a flowchart of the process by the control unit 250. The control unit 250 activates the combustible gas sensor 10 and activates the heater 27 of the oxygen pump cell 20 to start the process (step S2).

[0036] Next, the control unit 250 passes a pump current between the pair of electrodes 23 and 25 of the oxygen pump cell 20 so that the electrode 23 (on the measurement chamber 100s side) becomes the cathode, and pumps out oxygen in the measurement chamber 100s to the outside (draws in external gas) (step S6). Step S6 corresponds to the first process. Following step S6, the control unit 250 passes a pump current between the pair of electrodes 23 and 25 of the oxygen pump cell 20 so that the electrode 23 (on the measurement chamber 100s side) becomes the anode, and pumps oxygen into the measurement chamber 100s (step S8). As a result, the gas G2 that is not adsorbed by the adsorption unit 30 and interferes with the measurement can be discharged, and calibration can be performed. Step S8 corresponds to the fourth process.

[0037] Following step S8, the control unit 250 stops the oxygen pump cell 20, activates the heater 32 of the adsorption unit 30, heats it, and measures the gas concentration with the combustible gas sensor 10 (step S10). Step S10 corresponds to the second process.

[0038] Next, the control unit 250 passes a pump current between the pair of electrodes 23 and 25 of the oxygen pump cell 20 so that the electrode 23 (on the measurement chamber 100s side) becomes the cathode, and pumps out oxygen from the measurement chamber 100s to the outside. Also, the heater 32 of the adsorption unit 30 is stopped (cooled) (step S12). By pumping out oxygen with the oxygen pump cell 20, external gas can be drawn into the measurement chamber 100s, and the atmosphere in the measurement chamber 100s can be adjusted to the external atmosphere.

[0039] Next, the control unit 250 passes a pump current between the pair of electrodes 23 and 25 of the oxygen pump cell 20 so that the electrode 23 (on the measurement chamber 100s side) becomes the anode, and pumps oxygen into the measurement chamber 100s (step S13). Step S13 corresponds to the third process.

[0040] After step S13, if the measurement is not terminated (the measurement is continued) in step S14, the process returns to step S4 and the measurement is repeated. On the other hand, if it is Yes (the measurement is terminated) in step S14, the combustible gas sensor 10 and the oxygen pump cell 20 are stopped in step S16, and the process ends.

[0041] As described above, by performing the first process, even without separately providing a suction pump or the like, the oxygen pump cell 20 can pump out oxygen from the measurement chamber 100s, and the gas can be forcibly introduced into the measurement chamber 100s from the gas inlet 100h by negative pressure. Also, after the measurement in the second process, the atmosphere inside the measurement chamber 100s is in a state where the concentration of the target gas has decreased and the concentration of interfering gases or the like has increased. Therefore, by performing the third process to pump oxygen into the measurement chamber 100s, the gas in the measurement chamber 100s can be discharged from the gas inlet 100h, the influence of interfering gases can be reduced during the next measurement, and the actual external atmosphere (gas concentration) can be reflected. As a result, the combustible gas measuring device and the combustible gas measuring system can be miniaturized, and the measurement accuracy can be improved.

[0042] Furthermore, by providing the adsorption part 30 in the combustible gas measuring device 200 and performing the fourth process, as much of the interfering gas G2 remaining in the measurement chamber 100s as the target gas G1 adsorbed to the adsorption part 30 can be excluded from the measurement chamber 100s, and the influence of the interfering gas G2 on the measurement can be reduced. Furthermore, when the adsorption part 30 is provided, in the second process, while desorbing the target gas G1 from the adsorption part 30, by measuring with the combustible gas sensor 10, even if the concentration of the target gas G1 in the gas G is low, the target gas G1 adsorbed to the adsorption part 30 and locally increased in concentration can be measured. Therefore, the measurement accuracy is improved and the lower limit concentration of the measurement is decreased.

[0043] Note that by simply electrically switching the polarity of the pump current for pumping out and pumping in oxygen by the oxygen pump cell 20, the direction of gas flow into and out of the measurement chamber can be reversed, and equipment such as switching the flow path of the suction pump to the measurement chamber is not required, and the device can be made more compact.

[0044] The present invention is not limited to the above-described embodiments, and it goes without saying that the present invention extends to various modifications and equivalents included in the spirit and scope of the present invention. For example, in the above-described embodiments, the case of detecting hydrogen gas has been described, but the gas sensor of the present invention can also detect other types of combustible gases.

[0045] Furthermore, for example, as shown in FIG. 7, the oxygen pump cell does not have to be of the MEMS type. Here, the combustible gas measuring device 200B shown in FIG. 7 is the same as the combustible gas measuring devices 200 of FIGS. 1 and 2 except that the housing part 100B is different. Here, the upper surface 100BT of the housing part 100B has a configuration in which an oxygen ion conductive solid electrolyte body 21B is laminated between two insulating layers 111 and 113 such as alumina. Furthermore, in the region of the upper surface 100BT on the back side of the measurement chamber 100s from the combustible gas sensor 10, the insulating layers 111 and 113 each have a rectangular notch 100n, and the oxygen ion conductive solid electrolyte body 21B is exposed at the notch 100n. Then, a pair of electrodes 23B and 25B are respectively disposed on the front and back surfaces of the exposed oxygen ion conductive solid electrolyte 21B, and the oxygen ion conductive solid electrolyte 21B and the electrodes 23B and 25B constitute an oxygen pump cell 20B.

[0046] Further, the adsorption part 32 may be omitted in the combustible gas measuring device. In this case, the control unit 250 performs the first process, the second process, and the third process, but does not perform the fourth process.

Example

[0047] First, on the upper surface of a silicon substrate with a 1 mm square hole opened as a diaphragm part, an SiO2(1000 nm) / SnO2(200 nm) film was laminated, Pt(10 nm) serving as a heater pattern was embedded inside the SiO2, and a pair of electrodes made of comb-shaped Pt(10 nm) having a 20 μm gap at the interface between the SiO2 and the SnO2 were formed. Further, the pair of electrodes were covered with a gas detection layer made of tin oxide, and the combustible gas sensor 10 shown in FIG. 3 was fabricated as a MEMS element. Similarly, on the upper surface of a silicon substrate with a 1 mm square hole opened as a diaphragm part, a Pt(10 nm) / YSZ(1000 nm) / Pt(10 nm) film was laminated, Pt(10 nm) serving as a heater pattern was embedded inside the YSZ, and the oxygen pump cell 20 shown in FIG. 3 was fabricated as a MEMS element.

[0048] Next, as the housing part 100, ceramic green sheets mainly composed of alumina were laminated, a gas inlet 100h, a measurement chamber 100s having a size of 1×5×20 mm, a through hole 100h2, and a heater 32 were formed, and the whole was fired and fabricated. done. The oxygen pump cell 20 was fixed to the back side of the measurement chamber 100s, and the combustible gas sensor 10 was fixed with solder on the gas inlet 100h side. As the adsorption part 30, a paste obtained by mixing zeolite (trade name: HSZ-390HUA, Tosoh) and an alumina binder was printed on the ceramic sheet serving as the upper surface of the measurement chamber 100s and then fired to form it.

[0049] Ethanol gas (concentration 100 ppm) in the atmospheric atmosphere was measured. After starting the flammable gas sensor 10 and the oxygen pump cell 20, as a third process, the oxygen pump cell 20 was activated for 10 minutes to draw in oxygen (step S4 in FIG. 6). Next, as a first process, the oxygen pump cell 20 was activated for 1 minute to pump out oxygen (step S6 in FIG. 6). Next, as a fourth process, the oxygen pump cell 20 was activated for 10 minutes to draw in oxygen (step S8 in FIG. 6).

[0050] Next, as a second process, the oxygen pump cell 20 was stopped, the heater 32 was turned ON to heat the adsorption part 30, and the target gas concentration was measured with the flammable gas sensor 10 (step S10 in FIG. 6). In the concentration measurement, from the average oxygen pumping flow rate of 0.01 mL / min, the oxygen pumping time of 1 minute, and the measurement chamber volume, it was calculated that 10 vol% of the outside air components flowed in. As a result, although the actual ethanol concentration was 100 ppm, the measured concentration was 10 ppm. Thereafter, the heater 32 was turned OFF to stop heating the adsorption part 30, and at the same time, the oxygen pump cell 20 was activated for 10 minutes to pump out oxygen, and the measurement was terminated (steps S12 to S16 in FIG. 6).

Explanation of Signs

[0051] 10 Flammable gas sensor 20 Oxygen pump cell 21, 21B Oxygen ion conductive solid electrolyte 23, 25, 23B, 25B Pair of electrodes 30 Adsorption part 100 Housing part 100h Gas inlet 100s Measurement chamber 200, 200B Flammable gas measuring device 250 Control unit 300 Flammable gas measurement system

Claims

1. A housing portion having a gas inlet communicating with the outside, and a measurement chamber into which gas flows from the gas inlet is formed inside itself; A flammable gas sensor disposed inside the measurement chamber for detecting a target gas composed of flammable gas; A flammable gas measuring device having: Further comprising an oxygen pump cell that separates the measurement chamber from the outside and allows oxygen to be exchanged between the outside and the measurement chamber; The oxygen pump cell has an oxygen ion conductive solid electrolyte body and a pair of electrodes. A flammable gas measuring device characterized by this.

2. The flammable gas measuring device according to claim 1, characterized in that an adsorption portion for adsorbing the target gas is disposed inside the measurement chamber.

3. The flammable gas measuring device according to claim 1 or 2, characterized in that the oxygen pump cell is of the MEMS (Micro Electro Mechanical Systems) type.

4. A flammable gas measuring system comprising the flammable gas measuring device according to claim 1 or 2, And a control unit for controlling the flammable gas measuring device, The flammable gas measuring system is characterized in that: The control unit performs a first process of pumping out the oxygen inside the measurement chamber to the outside by the oxygen pump cell; After the first process, a second process of measuring the flammable gas sensor is performed; After the second process, a third process of pumping external oxygen into the measurement chamber by the oxygen pump cell is executed. A flammable gas measuring system characterized by this.

5. The flammable gas measuring system according to claim 4, The flammable gas measuring device further includes the adsorption portion, The control unit, after the first process and before the second process, executes a fourth process of pumping external oxygen into the measurement chamber by the oxygen pump cell, and In the second process, while desorbing the target gas from the adsorption portion, the flammable gas sensor is measured. A flammable gas measuring system characterized by this.

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