Gas sensor testing device, gas sensor testing method, and gas sensor manufacturing method

Abstract

To examine the impact exerted on a gas sensor by the dynamic pressure of gas to be measured.SOLUTION: A gas sensor testing device 200 is a test device for a gas sensor 100a for detecting a specific gas concentration in gas to be measured. The gas sensor testing device 200 comprises a chamber 210, a pressure supply unit 220, and an electromagnetic valve 230. The chamber 210 includes an inner space 210a, an inlet 211 of gas to the inner space 210a, an outlet 212 of gas from the inner space 210a, and a gas sensor attachment unit 213 to which the gas sensor 100a can be attached in such a manner that a specific gas concentration in the gas in the inner space 210a is detectable. The pressure supply unit 220 supplies pressure to the inner space 210a via the inlet 211. The electromagnetic valve 230 is connected to the outlet 212 and opens / closes a discharge path from the outlet 212 of the gas in the inner space 210a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas sensor testing device, a gas sensor testing method, and a gas sensor manufacturing method. [Background technology]

[0002] Conventionally, gas sensors for detecting the concentration of a specific gas, such as NOx, in a measurement gas, such as automobile exhaust gas, have been known. For example, Patent Document 1 (Patent Document 1) describes a gas sensor including a sensor element having an element body, a main pump cell, an auxiliary pump cell, and a measurement pump cell. The element body has a measurement gas flow section therein, which includes an oxygen-ion-conductive solid electrolyte layer and through which the measurement gas is introduced and circulated. The main pump cell has an inner main pump electrode disposed in a first internal space of the measurement gas flow section and an outer main pump electrode disposed in a portion of the element body exposed to the measurement gas outside. The auxiliary pump cell has an inner auxiliary pump electrode disposed in a second internal space of the measurement gas flow section downstream of the first internal space and an outer auxiliary pump electrode disposed in a portion of the element body exposed to the measurement gas outside. The measurement pump cell has an inner measurement electrode disposed in a measurement chamber downstream of the second internal space in the measurement gas flow section, and an outer measurement electrode disposed in a portion of the element body exposed to the measurement gas on the outside. When using this sensor element to detect the NOx concentration, the oxygen concentration of the measurement gas is first adjusted in the first and second internal spaces by the main pump cell and auxiliary pump cell. Then, the NOx in the measurement gas after the oxygen concentration adjustment is reduced in the measurement chamber. The NOx concentration in the measurement gas is detected based on the pump current that flows when the measurement pump cell pumps out the oxygen generated by the reduction of NOx. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-091669 Summary of the Invention [Problem to be solved by the invention]

[0004] In such gas sensors, even if the composition of the measured gas remains the same, changes in the dynamic pressure of the measured gas may cause changes in the operation of the gas sensor (for example, the value of the pump current flowing through the pump cell). As a result, changes in the dynamic pressure of the measured gas may affect the detection accuracy of the concentration of a specific gas. Therefore, it is desirable to investigate the effect of the dynamic pressure of the measured gas on the gas sensor.

[0005] The present invention has been made to solve the above problems, and its main object is to examine the influence of the dynamic pressure of the gas to be measured on the gas sensor. [Means for solving the problem]

[0006] In order to achieve the above-mentioned main object, the present invention employs the following means.

[0007] [1] The gas sensor testing device of the present invention comprises: A testing device for a gas sensor for detecting a specific gas concentration in a measurement gas, comprising: a chamber having an internal space, a gas inlet port into the internal space, a gas outlet port from the internal space, and a gas sensor mounting portion to which the gas sensor can be mounted in a manner that allows the specific gas concentration in the gas in the internal space to be detected; a pressure supply unit that supplies pressure to the internal space through the inlet unit; an opening / closing mechanism connected to the outlet portion and configured to open and close a discharge path for the gas in the internal space from the outlet portion; It is equipped with the following.

[0008] In this testing device, dynamic pressure can be generated in the internal space by opening or repeatedly opening and closing the opening / closing mechanism while supplying pressure from the pressure supply unit to the internal space of the chamber. Therefore, by acquiring information on the operation of the gas sensor attached to the chamber at this time, the relationship between dynamic pressure and gas sensor operation can be investigated. Therefore, by using this gas sensor testing device, it is possible to investigate the effect of the dynamic pressure of the measured gas on the gas sensor (for example, the effect on the detection accuracy of a specific gas concentration).

[0009] [2] The gas sensor testing device described above (the gas sensor testing device described in [1] above) may further include an opening / closing control unit that periodically opens and closes the opening / closing mechanism. In this way, by periodically opening and closing the opening / closing mechanism, a periodic change in dynamic pressure, i.e., pulsation, can be generated in the internal space of the chamber. Therefore, the effect of the pulsation of the measured gas on the gas sensor can be investigated.

[0010] [3] In the gas sensor testing device described above (the gas sensor testing device described in [1] or [2] above), the chamber may include a plurality of outlets, the opening and closing mechanisms may be connected to each of the plurality of outlets, and the testing device may further include an opening and closing control unit that synchronously opens and closes two or more of the plurality of opening and closing mechanisms. This makes it easier to generate a large dynamic pressure in the internal space of the chamber compared to opening or repeatedly opening and closing a single opening and closing mechanism.

[0011] [4] In the gas sensor testing apparatus described above (the gas sensor testing apparatus according to any one of [1] to [3]), the gas sensor may include an element body having an oxygen ion-conductive solid electrolyte and a measurement gas flow section therein through which the measurement gas is introduced from a gas inlet and flows; and a pump cell having an inner electrode provided in the measurement gas flow section and an outer electrode provided on the outer surface of the element body so as to come into contact with the measurement gas. The testing apparatus may further include a gas sensor control unit that applies a voltage between the inner electrode and the outer electrode to cause the pump cell to pump oxygen, and a measurement unit that measures a pump current flowing through the pump cell when the pump cell pumps oxygen. This allows the pump current of the pump cell to be obtained as information on the operation of the gas sensor. This makes it possible to investigate the effect of the dynamic pressure of the measurement gas on the pump current of the gas sensor.

[0012] [5] The method for testing a gas sensor of the present invention comprises: A gas sensor testing method using a gas sensor testing device for detecting a specific gas concentration in a measurement gas, comprising: The test device comprises: a chamber having an internal space, a gas inlet port into the internal space, a gas outlet port from the internal space, and a gas sensor mounting portion to which the gas sensor can be mounted in a manner that allows the specific gas concentration in the gas in the internal space to be detected; a pressure supply unit that supplies pressure to the internal space through the inlet unit; an opening / closing mechanism connected to the outlet portion and configured to open and close a discharge path for the gas in the internal space from the outlet portion; Equipped with The testing method includes a first step of acquiring information about operation of the gas sensor attached to the chamber when the opening / closing mechanism is opened or repeatedly opened and closed while supplying pressure from the pressure supply unit to the internal space, It is something.

[0013] In this testing method, in the first step, dynamic pressure can be generated in the chamber by opening or repeatedly opening and closing the opening / closing mechanism while supplying pressure from the pressure supply unit to the internal space of the chamber. Then, by acquiring information about the operation of the gas sensor attached to the chamber at this time, the relationship between the dynamic pressure and the operation of the gas sensor can be investigated. This makes it possible to investigate the effect of the dynamic pressure of the gas to be measured on the gas sensor (e.g., the effect on the detection accuracy of the concentration of a specific gas). Note that various aspects of the gas sensor testing device of the present invention described above may be employed in the gas sensor testing method of the present invention.

[0014] [6] In the gas sensor testing method described above (the gas sensor testing method described in [5] above), the first step may include periodically opening and closing the opening / closing mechanism. By doing so, a periodic change in dynamic pressure, i.e., pulsation, can be generated in the internal space of the chamber by periodically opening and closing the opening / closing mechanism. This makes it possible to examine the effect of the pulsation of the measured gas on the gas sensor.

[0015] [7] The above-mentioned gas sensor testing method (the gas sensor testing method described in [5] or [6]) may further include a second step of acquiring information about the operation of the gas sensor attached to the chamber when the opening / closing mechanism is continuously closed. In this way, the first step can acquire information about the operation of the gas sensor when dynamic pressure is generated in the internal space of the chamber, and the second step can acquire information about the operation of the gas sensor when dynamic pressure is not generated in the internal space of the chamber. This makes it possible to investigate in more detail the effect of the dynamic pressure of the measured gas on the gas sensor.

[0016] [8] The gas sensor testing method described in [7] may further include a third step of evaluating the dynamic pressure resistance of the gas sensor based on the information acquired in the first step and the information acquired in the second step. In this way, the dynamic pressure resistance of the gas sensor can be evaluated. Note that the dynamic pressure resistance indicates the resistance of a gas sensor to the dynamic pressure of the gas to be measured, and a gas sensor that is less affected by dynamic pressure can be said to have a higher dynamic pressure resistance.

[0017] [9] In the gas sensor testing method described in any one of [5] to [8] above, the gas sensor includes an element body having an oxygen ion-conductive solid electrolyte and a measurement gas flow section therein through which the measurement gas is introduced from a gas inlet and flows; and a pump cell having an inner electrode provided in the measurement gas flow section and an outer electrode provided on the outer surface of the element body so as to come into contact with the measurement gas. The information regarding the operation of the gas sensor may be a pump current flowing when the pump cell pumps oxygen due to a voltage applied between the inner electrode and the outer electrode. This allows the pump current of the pump cell to be obtained as the information regarding the operation of the gas sensor. This makes it possible to investigate the effect of the dynamic pressure of the measurement gas on the pump current of the gas sensor.

[0018]

[10] In the gas sensor testing method described in [8] above, the gas sensor may include an element body having an oxygen-ion conductive solid electrolyte and a measurement gas flow section therein through which the measurement gas is introduced from a gas inlet and flows; and a pump cell having an inner electrode provided in the measurement gas flow section and an outer electrode provided on the outer surface of the element body so as to come into contact with the measurement gas. In the first and second steps, a pump current value that flows when the pump cell pumps oxygen by a voltage applied between the inner and outer electrodes may be acquired as information related to the operation of the gas sensor. In the third step, the dynamic pressure resistance performance may be evaluated based on the difference between the pump current acquired in the first step and the pump current acquired in the second step. Here, the higher the dynamic pressure resistance performance of the gas sensor, the smaller the difference between the pump current acquired in the first step and the pump current acquired in the second step. Therefore, the dynamic pressure resistance performance of the gas sensor can be appropriately evaluated based on the difference between these pump currents.

[0019]

[11] A method for manufacturing a gas sensor according to the present invention includes the steps of: A method for manufacturing a gas sensor including the above-mentioned gas sensor testing method (the gas sensor testing method described in [8] or

[10] above), a manufacturing step of manufacturing the gas sensor; an inspection step of evaluating the dynamic pressure resistance performance of the gas sensor manufactured in the manufacturing step by performing the test method; It includes:

[0020] In this manufacturing method, the dynamic pressure resistance performance is evaluated by carrying out the above-described gas sensor testing method in the inspection step, so that a gas sensor whose dynamic pressure resistance performance has already been evaluated can be manufactured. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is an explanatory diagram showing the outline of the configuration of a gas sensor testing device 200. [Figure 2] FIG. 2 is an explanatory diagram showing the positional relationship between a chamber 210 and a plurality of electromagnetic valves 230. [Figure 3] 1 is a cross-sectional view schematically illustrating an example of the configuration of a gas concentration measurement system 100. FIG. [Figure 4] FIG. 4 is a block diagram showing the electrical connection relationship between a gas sensor control unit 95 and each cell and a heater 72. [Figure 5] 6 is a graph showing the change over time in static pressure in the internal space 210a when the number of times the solenoid valve 230 is opened and closed and the open / closed state are variously changed. [Figure 6] 3A to 3C are process diagrams of a method for manufacturing the gas sensor 100a. DETAILED DESCRIPTION OF THE INVENTION

[0022] Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing the outline of the configuration of a gas sensor testing apparatus 200, which is one embodiment of the gas sensor testing apparatus of the present invention. FIG. 2 is an explanatory diagram showing the positional relationship between a chamber 210 and a plurality of solenoid valves 230. FIG. 2 is a view of the chamber 210 and the solenoid valves 230 as seen from the right side of FIG. 1, and components of the gas sensor testing apparatus 200 other than the chamber 210 and the solenoid valves 230 are not shown. FIG. 3 is a schematic cross-sectional view showing an example of the configuration of a gas concentration measurement system 100. FIG. 4 is a block diagram showing the electrical connection between a gas sensor control unit 95 and each cell and a heater 72.

[0023] 1 also shows a gas concentration measurement system 100 that includes a gas sensor 100a that is to be tested by the gas sensor testing device 200. First, the gas concentration measurement system 100 shown in FIGS. 1, 3, and 4 will be described.

[0024] The gas concentration measurement system 100 includes a gas sensor 100a and a gas sensor control unit 95. The gas sensor 100a is used while attached to a pipe such as an exhaust gas pipe of an internal combustion engine. The gas sensor 100a detects the concentration of a specific gas, such as NOx or ammonia, in the exhaust gas from the internal combustion engine. In this embodiment, the gas sensor 100a measures the NOx concentration as the specific gas concentration. The gas sensor 100a includes a sensor element 101 having an element body 102 in the shape of a long rectangular parallelepiped, a protective cover 110 that protects the front end side (the lower end side in FIG. 1, the left end side in FIG. 3) of the sensor element 101, and a sensor assembly 111 that houses the sensor element 101. 3, the longitudinal direction of the element body 102 (the left-right direction in FIG. 3) is the front-rear direction, the thickness direction of the element body 102 (the up-down direction in FIG. 3) is the up-down direction, and the width direction of the element body 102 (the direction perpendicular to the front-rear direction and the up-down direction) is the left-right direction. The protective cover 110 and the sensor assembly 111 seal the space around the front end of the sensor element 101 exposed to the gas to be measured (the space inside the protective cover 110) and the space around the rear end where the reference gas is sealed. As shown in FIG. 1, the gas inlet 10 of the element body 102 is located in the space inside the protective cover 110, and the inlet portion 49a of the element body 102 is located in the space inside the sensor assembly 111 where the reference gas is sealed.

[0025] The sensor element 101 includes an element body 102, as well as cells 21, 41, 50, 80 to 83, and a heater portion .

[0026] The element body 102 is a laminate formed by stacking six layers, in this order from bottom to top, from the drawing: a first substrate layer 1, a second substrate layer 2, a third substrate layer 3, a first solid electrolyte layer 4, a spacer layer 5, and a second solid electrolyte layer 6, each of which is made of an oxygen-ion conductive solid electrolyte layer such as zirconia (ZrO). The solid electrolyte forming these six layers is dense and airtight. The element body 102 is manufactured, for example, by laminating ceramic green sheets corresponding to each layer after performing predetermined processing and printing a circuit pattern on them, and then firing them to integrate them.

[0027] At the front end side of the sensor element 101 (element body 102), between the lower surface of the second solid electrolyte layer 6 and the upper surface of the first solid electrolyte layer 4, a gas inlet 10, a first diffusion rate-controlling section 11, a buffer space 12, a second diffusion rate-controlling section 13, a first internal space (oxygen concentration adjusting chamber) 20, a third diffusion rate-controlling section 30, a second internal space (oxygen concentration adjusting chamber) 40, a fourth diffusion rate-controlling section 60, and a third internal space (measurement chamber) 61 are formed adjacent to each other and communicate with each other in this order.

[0028] The gas inlet 10, the buffer space 12, the first internal space 20, the second internal space 40, and the third internal space 61 are spaces inside the sensor element 101, which are defined by hollowing out the spacer layer 5, with an upper portion defined by the underside of the second solid electrolyte layer 6, a lower portion defined by the upper surface of the first solid electrolyte layer 4, and sides defined by the side surfaces of the spacer layer 5.

[0029] The first diffusion-controlling section 11, the second diffusion-controlling section 13, and the third diffusion-controlling section 30 are each provided as two horizontally elongated slits (with the opening extending in the direction perpendicular to the drawing). The fourth diffusion-controlling section 60 is provided as a single horizontally elongated slit (with the opening extending in the direction perpendicular to the drawing) formed as a gap with the lower surface of the second solid electrolyte layer 6. The region from the gas inlet 10 to the third internal space 61 is also referred to as a measurement gas flow section.

[0030] The sensor element 101 (element body 102) includes a reference gas inlet 49 that passes a reference gas from the outside of the sensor element 101 to the reference electrode 42 when measuring the NOx concentration. The reference gas inlet 49 includes a reference gas inlet space 43 and a reference gas inlet layer 48. The reference gas inlet space 43 is a space extending inward from the rear end surface of the sensor element 101. The reference gas inlet space 43 is located between the upper surface of the third substrate layer 3 and the lower surface of the spacer layer 5, and is defined laterally by the side surface of the first solid electrolyte layer 4. The reference gas inlet space 43 opens at the rear end surface of the sensor element 101, and this opening functions as an inlet 49a of the reference gas inlet 49. The reference gas is introduced into the reference gas inlet space 43 from the inlet 49a. The reference gas inlet 49 applies a predetermined diffusion resistance to the reference gas introduced from the inlet 49a and introduces the reference gas into the reference electrode 42. In this embodiment, the reference gas is air.

[0031] The reference gas introduction layer 48 is provided between the upper surface of the third substrate layer 3 and the lower surface of the first solid electrolyte layer 4. The reference gas introduction layer 48 is a porous body made of ceramics such as alumina. A portion of the upper surface of the reference gas introduction layer 48 is exposed within the reference gas introduction space 43. The reference gas introduction layer 48 is formed to cover the reference electrode 42. The reference gas introduction layer 48 allows the reference gas to flow from the reference gas introduction space 43 to the reference electrode 42.

[0032] Reference electrode 42 is an electrode formed in a manner sandwiched between the upper surface of third substrate layer 3 and first solid electrolyte layer 4, and as described above, is surrounded by reference gas introduction layer 48 connected to reference gas introduction space 43. As will be described later, reference electrode 42 can be used to measure the oxygen concentration (oxygen partial pressure) in first internal space 20, second internal space 40, and third internal space 61. Reference electrode 42 is formed as a porous cermet electrode (for example, a cermet electrode of Pt and ZrO2).

[0033] In the measurement gas flow section, the gas inlet 10 is a section that opens to the external space, and the measurement gas is introduced into the sensor element 101 from the external space through the gas inlet 10. The first diffusion-controlling section 11 is a section that imparts a predetermined diffusion resistance to the measurement gas introduced through the gas inlet 10. The buffer space 12 is a space provided to guide the measurement gas introduced through the first diffusion-controlling section 11 to the second diffusion-controlling section 13. The second diffusion-controlling section 13 is a section that imparts a predetermined diffusion resistance to the measurement gas introduced from the buffer space 12 into the first internal space 20. When the measurement gas is introduced from the outside of the sensor element 101 into the first internal space 20, the measurement gas is suddenly taken into the sensor element 101 through the gas inlet 10 due to pressure fluctuations of the measurement gas in the external space (exhaust pressure pulsations in the case where the measurement gas is automobile exhaust gas). The measurement gas is not introduced directly into the first internal space 20, but is introduced into the first internal space 20 after the pressure fluctuations of the measurement gas are canceled out through the first diffusion-controlling section 11, buffer space 12, and second diffusion-controlling section 13. This makes the pressure fluctuations of the measurement gas introduced into the first internal space 20 almost negligible. The first internal space 20 is provided as a space for adjusting the oxygen partial pressure in the measurement gas introduced through the second diffusion-controlling section 13. The oxygen partial pressure is adjusted by operating the main pump cell 21.

[0034] The main pump cell 21 is an electrochemical pump cell including an inner pump electrode 22 having a ceiling electrode portion 22a provided on almost the entire lower surface of the second solid electrolyte layer 6 facing the first internal space 20, an outer pump electrode 23 provided on the upper surface of the second solid electrolyte layer 6 in a region corresponding to the ceiling electrode portion 22a so as to be exposed to the outside of the sensor element 101, and the second solid electrolyte layer 6, the spacer layer 5, and the first solid electrolyte layer 4 which form a current path between these electrodes.

[0035] The inner pump electrode 22 is formed across the upper and lower solid electrolyte layers (the second solid electrolyte layer 6 and the first solid electrolyte layer 4) that define the first internal space 20 and the spacer layer 5 that provides the side walls. Specifically, a ceiling electrode portion 22a is formed on the lower surface of the second solid electrolyte layer 6 that provides the ceiling surface of the first internal space 20, and a bottom electrode portion 22b is formed on the upper surface of the first solid electrolyte layer 4 that provides the bottom surface. Side electrode portions (not shown) are formed on the side wall surfaces (inner surfaces) of the spacer layer 5 that configure both side wall portions of the first internal space 20 so as to connect the ceiling electrode portion 22a and the bottom electrode portion 22b, and are arranged in a tunnel-like structure at the locations where the side electrode portions are provided.

[0036] The inner pump electrode 22 and the outer pump electrode 23 are formed as porous cermet electrodes (for example, a cermet electrode of Pt and ZrO containing 1% Au). The inner pump electrode 22, which comes into contact with the measurement gas, is formed using a material with a weakened ability to reduce the NOx component in the measurement gas.

[0037] In the main pump cell 21, by applying a desired voltage Vp0 between the inner pump electrode 22 and the outer pump electrode 23 and flowing a pump current Ip0 in a positive or negative direction between the inner pump electrode 22 and the outer pump electrode 23, it is possible to pump oxygen from the first internal space 20 out to the external space, or to pump oxygen from the external space into the first internal space 20.

[0038] In addition, in order to detect the oxygen concentration (oxygen partial pressure) in the atmosphere in the first internal space 20, an electrochemical sensor cell, i.e., an oxygen partial pressure detection sensor cell 80 for controlling the main pump, is configured by the inner pump electrode 22, the second solid electrolyte layer 6, the spacer layer 5, the first solid electrolyte layer 4, the third substrate layer 3, and the reference electrode 42.

[0039] The oxygen concentration (oxygen partial pressure) in the first internal space 20 can be determined by measuring the electromotive force (voltage V0) in the main pump control oxygen partial pressure detection sensor cell 80. Furthermore, the pump current Ip0 is controlled by feedback controlling the voltage Vp0 of the variable power supply 24 so that the voltage V0 becomes a target value. This allows the oxygen concentration in the first internal space 20 to be maintained at a predetermined constant value.

[0040] The third diffusion control section 30 is a section that imparts a predetermined diffusion resistance to the measurement gas whose oxygen concentration (oxygen partial pressure) has been controlled by the operation of the main pump cell 21 in the first internal space 20, and guides the measurement gas to the second internal space 40.

[0041] The second internal space 40 is provided as a space for further adjusting the oxygen partial pressure by the auxiliary pump cell 50 for the measurement gas introduced through the third diffusion-controlling section 30 after the oxygen concentration (oxygen partial pressure) has been adjusted in advance in the first internal space 20. This makes it possible to keep the oxygen concentration in the second internal space 40 constant with high precision, thereby enabling the gas concentration measurement system 100 to measure the NOx concentration with high precision.

[0042] The auxiliary pump cell 50 is an auxiliary electrochemical pump cell that is configured by an auxiliary pump electrode 51 having a ceiling electrode portion 51a provided on substantially the entire lower surface of the second solid electrolyte layer 6 facing the second internal space 40, an outer pump electrode 23 (not limited to the outer pump electrode 23, but any appropriate electrode on the outside of the sensor element 101 will suffice), the second solid electrolyte layer 6, the spacer layer 5, and the first solid electrolyte layer 4.

[0043] The auxiliary pump electrode 51 is disposed in the second internal space 40 in a tunnel-shaped structure similar to the inner pump electrode 22 disposed in the first internal space 20. That is, a ceiling electrode portion 51a is formed on the lower surface of the second solid electrolyte layer 6, which provides the ceiling surface of the second internal space 40, and a bottom electrode portion 51b is formed on the upper surface of the first solid electrolyte layer 4, which provides the bottom surface of the second internal space 40. Side electrodes (not shown) connecting the ceiling electrode portion 51a and the bottom electrode portion 51b are formed on both wall surfaces of the spacer layer 5, which provide the side walls of the second internal space 40. Like the inner pump electrode 22, the auxiliary pump electrode 51 is also formed using a material with a weakened ability to reduce NOx components in the measurement gas.

[0044] In the auxiliary pump cell 50, by applying a desired voltage Vp1 between the auxiliary pump electrode 51 and the outer pump electrode 23, it is possible to pump oxygen in the atmosphere within the second internal space 40 out to the external space or pump oxygen from the external space into the second internal space 40.

[0045] In addition, in order to control the oxygen partial pressure in the atmosphere within the second internal space 40, an electrochemical sensor cell, i.e., an oxygen partial pressure detection sensor cell 81 for controlling the auxiliary pump, is configured by the auxiliary pump electrode 51, the reference electrode 42, the second solid electrolyte layer 6, the spacer layer 5, the first solid electrolyte layer 4, and the third substrate layer 3.

[0046] The auxiliary pump cell 50 performs pumping using a variable power supply 52 whose voltage is controlled based on the electromotive force (voltage V1) detected by the auxiliary pump control oxygen partial pressure detection sensor cell 81. This allows the oxygen partial pressure in the atmosphere within the second internal space 40 to be controlled to a low level that does not substantially affect the measurement of NOx.

[0047] In addition, the pump current Ip1 is used to control the electromotive force of the main pump control oxygen partial pressure detection sensor cell 80. Specifically, the pump current Ip1 is input as a control signal to the main pump control oxygen partial pressure detection sensor cell 80, and the target value of the voltage V0 is controlled to always maintain a constant gradient of the oxygen partial pressure in the measurement gas introduced from the third diffusion-controlling part 30 into the second internal space 40. When used as a NOx sensor, the oxygen concentration in the second internal space 40 is maintained at a constant value of approximately 0.001 ppm by the action of the main pump cell 21 and the auxiliary pump cell 50.

[0048] The fourth diffusion rate-controlling part 60 is a part that applies a predetermined diffusion resistance to the measurement gas, the oxygen concentration (oxygen partial pressure) of which has been controlled by the operation of the auxiliary pump cell 50 in the second internal space 40, and guides the measurement gas to the third internal space 61. The fourth diffusion rate-controlling part 60 serves to limit the amount of NOx that flows into the third internal space 61.

[0049] The third internal space 61 is provided as a space for performing processing related to measurement of the nitrogen oxide (NOx) concentration in the measurement gas, which is introduced through the fourth diffusion-controlling part 60 after the oxygen concentration (oxygen partial pressure) has been adjusted in advance in the second internal space 40. The NOx concentration is measured mainly in the third internal space 61 by the operation of the measurement pump cell 41.

[0050] The measurement pump cell 41 measures the NOx concentration in the measurement gas in the third internal space 61. The measurement pump cell 41 is an electrochemical pump cell including a measurement electrode 44 provided on the upper surface of the first solid electrolyte layer 4 facing the third internal space 61, the outer pump electrode 23, the second solid electrolyte layer 6, the spacer layer 5, and the first solid electrolyte layer 4. The measurement electrode 44 is a porous cermet electrode made of a material that has a higher reduction ability for the NOx component in the measurement gas than the inner pump electrode 22. The measurement electrode 44 also functions as a NOx reduction catalyst that reduces NOx present in the atmosphere in the third internal space 61.

[0051] In the measuring pump cell 41, oxygen produced by decomposition of nitrogen oxides in the atmosphere surrounding the measuring electrode 44 is pumped out, and the amount of oxygen produced can be detected as a pump current Ip2.

[0052] Furthermore, in order to detect the oxygen partial pressure around the measurement electrode 44, the first solid electrolyte layer 4, the third substrate layer 3, the measurement electrode 44, and the reference electrode 42 constitute an electrochemical sensor cell, i.e., an oxygen partial pressure detection sensor cell 82 for controlling the measurement pump. The variable power supply 46 is controlled based on the electromotive force (voltage V2) detected by the oxygen partial pressure detection sensor cell 82 for controlling the measurement pump.

[0053] The measurement gas introduced into the second internal space 40 reaches the measurement electrode 44 in the third internal space 61 through the fourth diffusion-controlling part 60 under conditions where the oxygen partial pressure is controlled. Nitrogen oxides in the measurement gas around the measurement electrode 44 are reduced (2NO → N2 + O2) to generate oxygen. This generated oxygen is then pumped by the measurement pump cell 41, and the voltage Vp2 of the variable power supply 46 is controlled so that the voltage V2 detected by the measurement pump control oxygen partial pressure detection sensor cell 82 remains constant (target value). Because the amount of oxygen generated around the measurement electrode 44 is proportional to the nitrogen oxide concentration in the measurement gas, the pump current Ip2 in the measurement pump cell 41 is used to calculate the nitrogen oxide concentration in the measurement gas.

[0054] Furthermore, by combining the measurement electrode 44, the first solid electrolyte layer 4, the third substrate layer 3, and the reference electrode 42 to form an oxygen partial pressure detection means as an electrochemical sensor cell, it is possible to detect an electromotive force corresponding to the difference between the amount of oxygen generated by reduction of the NOx components in the atmosphere around the measurement electrode 44 and the amount of oxygen contained in the reference gas, thereby making it possible to determine the concentration of the NOx components in the measured gas.

[0055] Furthermore, the second solid electrolyte layer 6, the spacer layer 5, the first solid electrolyte layer 4, the third substrate layer 3, the outer pump electrode 23, and the reference electrode 42 constitute an electrochemical sensor cell 83, and the electromotive force (voltage Vref) obtained by this sensor cell 83 makes it possible to detect the oxygen partial pressure in the measurement gas outside the sensor.

[0056] In the gas concentration measurement system 100 having such a configuration, the measurement gas, in which the oxygen partial pressure is always kept at a constant low value (a value that does not substantially affect the measurement of NOx) by operating the main pump cell 21 and the auxiliary pump cell 50, is supplied to the measurement pump cell 41. Therefore, the NOx concentration in the measurement gas can be determined based on the pump current Ip2 that flows when oxygen generated by the reduction of NOx is pumped out of the measurement pump cell 41, which is approximately proportional to the NOx concentration in the measurement gas.

[0057] In order to enhance the oxygen ion conductivity of the solid electrolyte, the sensor element 101 includes a heater unit 70 that adjusts the temperature by heating and maintaining the temperature of the sensor element 101. The heater unit 70 includes a heater connector electrode 71, a heater 72, a through-hole 73, a heater insulating layer 74, and a pressure release hole 75.

[0058] The heater connector electrode 71 is an electrode formed in a manner to contact the lower surface of the first substrate layer 1. By connecting the heater connector electrode 71 to a heater power supply 76 (see FIG. 4), it is possible to supply power from the heater power supply 76 to the heater section 70.

[0059] The heater 72 is an electrical resistor sandwiched between the second substrate layer 2 and the third substrate layer 3. The heater 72 is connected to a heater connector electrode 71 via a through hole 73, and generates heat when power is supplied from a heater power supply 76 through the heater connector electrode 71, thereby heating and keeping warm the solid electrolyte that forms the sensor element 101.

[0060] The heater 72 is embedded throughout the entire area from the first internal space 20 to the third internal space 61, and is capable of adjusting the temperature of the entire sensor element 101 to a temperature at which the solid electrolyte is activated.

[0061] The heater insulating layer 74 is an insulating layer made of an insulator such as alumina and formed on the upper and lower surfaces of the heater 72. The heater insulating layer 74 is formed for the purpose of obtaining electrical insulation between the second substrate layer 2 and the heater 72, and between the third substrate layer 3 and the heater 72.

[0062] The pressure release hole 75 is a portion that penetrates the third substrate layer 3 and the reference gas introduction layer 48 and is provided so as to communicate with the reference gas introduction space 43, and is formed for the purpose of alleviating the increase in internal pressure that accompanies a rise in temperature within the heater insulation layer 74.

[0063] 4, the gas sensor control unit 95 includes the variable power supplies 24, 46, and 52, the heater power supply 76, and a control circuit 96. The control circuit 96 is a microprocessor including a CPU 97 and a storage unit 98. The storage unit 98 is a rewritable nonvolatile memory capable of storing, for example, various programs and data. The control circuit 96 receives the voltage V0 of the oxygen partial pressure detection sensor cell 80 for controlling the main pump, the voltage V1 of the oxygen partial pressure detection sensor cell 81 for controlling the auxiliary pump, the voltage V2 of the oxygen partial pressure detection sensor cell 82 for controlling the measurement pump, the voltage Vref of the sensor cell 83, the pump current Ip0 flowing through the main pump cell 21, the pump current Ip1 flowing through the auxiliary pump cell 50, and the pump current Ip2 flowing through the measurement pump cell 41. The control circuit 96 also outputs control signals to the variable power supplies 24, 46, 52 to control the voltages Vp0, Vp1, Vp2 output by the variable power supplies 24, 46, 52, thereby controlling the main pump cell 21, the measurement pump cell 41, and the auxiliary pump cell 50. The control circuit 96 also outputs control signals to the heater power supply 76 to control the power supplied from the heater power supply 76 to the heater 72. The memory unit 98 also stores target values ​​V0*, V1*, V2*, etc., which will be described later. The CPU 97 of the control circuit 96 controls each of the cells 21, 41, 50 by referring to these target values ​​V0*, V1*, V2*.

[0064] The control circuit 96 performs an auxiliary pump control process to control the auxiliary pump cell 50 so that the oxygen concentration in the second internal space 40 becomes a target concentration. Specifically, the control circuit 96 controls the auxiliary pump cell 50 by feedback-controlling the voltage Vp1 of the variable power supply 52 so that the voltage V1 becomes a constant value (referred to as a target value V1*). The target value V1* is set as a value that makes the oxygen concentration in the second internal space 40 a predetermined low concentration that does not substantially affect the measurement of NOx.

[0065] The control circuit 96 performs a main pump control process to control the main pump cell 21 so that the pump current Ip1 flowing when the auxiliary pump cell 50 adjusts the oxygen concentration in the second internal space 40 by the auxiliary pump control process becomes a target current (referred to as a target value Ip1*). Specifically, the control circuit 96 sets (feedback controls) a target value (referred to as a target value V0*) of the voltage V0 based on the pump current Ip1 so that the pump current Ip1 flowing due to the voltage Vp1 becomes a constant target value Ip1*. The control circuit 96 then feedback controls the voltage Vp0 of the variable power supply 24 so that the voltage V0 becomes the target value V0* (i.e., so that the oxygen concentration in the first internal space 20 becomes the target concentration). This main pump control process ensures that the gradient of the oxygen partial pressure in the measurement gas introduced from the third diffusion rate-controlling section 30 into the second internal space 40 is always constant. The target value V0* is set to a value such that the oxygen concentration in the first internal space 20 is higher but lower than 0%. Furthermore, the pump current Ip0 flowing during this main pump control process varies depending on the oxygen concentration of the measurement gas (i.e., the measurement gas around the sensor element 101) flowing into the measurement gas flow section from the gas inlet 10. Therefore, the control circuit 96 can also detect the oxygen concentration in the measurement gas based on the pump current Ip0.

[0066] The above-described main pump control process and auxiliary pump control process are also collectively referred to as adjustment pump control process. The first internal space 20 and the second internal space 40 are also collectively referred to as the oxygen concentration adjustment chamber. The main pump cell 21 and the auxiliary pump cell 50 are also collectively referred to as the adjustment pump cell. The control circuit 96 performs the adjustment pump control process, causing the adjustment pump cell to adjust the oxygen concentration in the oxygen concentration adjustment chamber.

[0067] Furthermore, the control circuit 96 performs a measurement pump control process to control the measurement pump cell 41 so that the voltage V2 becomes a constant value (referred to as a target value V2*) (i.e., so that the oxygen concentration in the third internal space 61 becomes a predetermined low concentration). Specifically, the control circuit 96 controls the measurement pump cell 41 by feedback-controlling the voltage Vp2 of the variable power supply 46 so that the voltage V2 becomes the target value V2*. Oxygen is pumped out of the third internal space 61 by this measurement pump control process.

[0068] By performing the measurement pump control process, oxygen is pumped out of the third internal space 61 so that the amount of oxygen generated by the reduction of NOx in the measurement gas in the third internal space 61 becomes substantially zero. Then, the control circuit 96 acquires the pump current Ip2 as a detection value corresponding to the oxygen generated in the third internal space 61 due to the specific gas (here, NOx), and calculates the NOx concentration in the measurement gas based on this pump current Ip2.

[0069] The storage unit 98 stores a relational expression (for example, a linear or quadratic function) or a map as a correspondence relationship between the pump current Ip2 and the NOx concentration. Such a relational expression or map can be obtained in advance by experiment.

[0070] The control circuit 96 performs heater control processing, outputting a control signal to the heater power supply 76 to control the temperature of the heater 72 to a target temperature (e.g., 800°C). Here, the temperature of the heater 72 can be expressed as a linear function of the resistance of the heater 72. Therefore, in the heater control processing, the control circuit 96 calculates the resistance of the heater 72 as a value that can be regarded as the temperature of the heater 72 (a value that can be converted to temperature), and feedback-controls the heater power supply 76 so that the calculated resistance becomes the target resistance (the resistance corresponding to the target temperature). The control circuit 96 can, for example, acquire the voltage of the heater 72 and the current flowing through the heater 72 and calculate the resistance of the heater 72 based on the acquired voltage and current. The control circuit 96 may calculate the resistance of the heater 72 using, for example, a three-terminal method or a four-terminal method. When energizing the heater 72, the heater power supply 76 adjusts the power supplied to the heater 72 by, for example, changing the value of the voltage applied to the heater 72 based on a control signal from the control circuit 96.

[0071] The gas sensor control unit 95, including the variable power supplies 24, 46, 52 and the heater power supply 76 shown in FIG. 4, is actually connected to each electrode inside the sensor element 101 via lead wires (not shown) formed inside the sensor element 101 and connector electrodes (not shown) formed on the rear end side of the sensor element 101 (only the heater connector electrode 71 is shown in FIG. 3).

[0072] 1 and 2 will be described. The gas sensor testing apparatus 200 includes a chamber 210, a pressure supply unit 220, a solenoid valve 230, a solenoid valve control unit 240, a pressure meter 250, and loggers 261 and 262. In this embodiment, the gas sensor control unit 95 of the gas concentration measurement system 100 also serves as the gas sensor control unit, which is a component of the gas sensor testing apparatus 200.

[0073] The chamber 210 is formed in a substantially cylindrical shape and includes an internal space 210a, an inlet 211, an outlet 212, and a gas sensor attachment portion 213. The internal space 210a is a substantially cylindrical space similar to the external shape of the chamber 210. The inlet 211 is an inlet for gas into the internal space 210a and opens to one bottom surface of the cylinder of the chamber 210 (the left surface of the chamber 210 in FIG. 1). The outlet 212 is an outlet for gas from the internal space 210a and opens to a side surface of the cylinder of the chamber 210. The chamber 210 includes a plurality of outlets 212. More specifically, the chamber 210 includes three outlets 212 corresponding to the three solenoid valves 230 shown in FIG. 2. In this embodiment, all of the plurality of outlets 212 open to the side surface of the cylinder. Therefore, the direction in which gas flows out of the internal space 210a from the multiple outlets 212 is along the radial direction of the cylinder and is perpendicular to the direction in which gas flows into the internal space 210a from the inlet 211 (the axial direction of the cylinder). The gas sensor mounting portion 213 is a member for mounting the gas sensor 100a to the chamber 210 in a manner that allows detection of the concentration of a specific gas in the gas in the internal space 210a. In this embodiment, the gas sensor mounting portion 213 is a ring-shaped member with a female thread on its inner circumferential surface, and is welded to a through-hole formed in the side surface of the cylinder of the chamber 210. By threading the female thread of the gas sensor mounting portion 213 into a male thread formed on the outer circumferential surface of the sensor assembly 111 of the gas sensor 100a, the gas sensor 100a is mounted to the chamber 210 with the protective cover 110 of the gas sensor 100a exposed to the internal space 210a. As a result, the gas sensor 100a is attached to the chamber 210 in a state in which the gas in the internal space 210a can reach the gas inlet 10 of the sensor element 101 in the protective cover 110. Therefore, in this state, the gas in the internal space 210a is used as the measurement gas, and the gas sensor 100a can detect the concentration of a specific gas in this gas. The gas sensor attachment portion 213 is located between the inlet portion 211 and the outlet portion 212 in the left-right direction in FIG. 1. As a result, the gas sensor attachment portion 213 is arranged so that the gas sensor 100a can be attached midway along the gas path from the inlet portion 211 to the outlet portion 212 in the internal space 210a.

[0074] The pressure supply unit 220 supplies pressure to the internal space 210a of the chamber 210 via the inlet unit 211. The pressure supply unit 220 includes a gas supply source 221 and a regulator 222. The gas supply source 221 is a device that compresses and supplies gas, and in this embodiment, is an air compressor that compresses and supplies atmospheric air. The regulator 222 adjusts the pressure of the gas supplied from the gas supply source 221 to a predetermined pressure (a constant pressure value) and supplies the gas to the internal space 210a. The regulator 222 is configured as, for example, a regulator valve (pressure adjustment valve) that adjusts the pressure supplied to the internal space 210a by discharging excess pressure from the gas supply source 221. The pressure supply unit 220 can adjust the pressure supplied to the internal space 210a, for example, within a range of 0 MPa to 0.3 MPa.

[0075] The solenoid valve 230 is connected to the outlet 212 of the chamber 210, and opens and closes a discharge path from the outlet 212 of the gas in the internal space 210a. The solenoid valve 230 is provided midway through the piping that is connected to the outlet 212 and serves as a gas discharge path. The solenoid valve 230 may also be directly connected to the outlet 212. As described above, the chamber 210 has three outlets 212, and three solenoid valves 230 are provided corresponding to the respective outlets 212. The three solenoid valves 230 are arranged at equal intervals (here, at 90° intervals) along the circumferential direction of the cylindrical outer circumferential surface of the chamber 210, as shown in FIG. 2 .

[0076] The solenoid valve control unit 240 controls the opening and closing of the multiple solenoid valves 230. The solenoid valve control unit 240 includes a function generator 241 and a control circuit 242. The function generator 241 generates electrical signals of various frequencies and transmits the electrical signals to the control circuit 242. The control circuit 242 converts the electrical signals from the function generator 241 into control signals for the solenoid valves 230 and transmits them to the solenoid valves 230. In this way, the solenoid valve control unit 240 can periodically open and close the solenoid valves 230 in accordance with the frequency of the electrical signals generated by the function generator 241. In addition, the control circuit 242 can transmit synchronized control signals to the multiple solenoid valves 230, thereby synchronously opening and closing two or more of the multiple solenoid valves 230. The frequency of the electrical signals generated by the function generator 241 can be adjusted, for example, within a range of 0 Hz to 80 Hz.

[0077] The pressure gauge 250 measures the pressure in the internal space 210a. The pressure gauge 250 includes a pressure detection unit 251 and a pressure display unit 252. The pressure detection unit 251 is disposed so as to be exposed to the internal space 210a and detects the pressure in the internal space 210a. In this embodiment, the pressure detection unit 251 detects the static pressure in the internal space 210a. The pressure detection unit 251 is disposed on the other bottom surface of the cylinder (the right surface of the chamber 210 in FIG. 1 ) and is disposed at a position facing the inlet portion 211 of the chamber 210. The pressure detection unit 251 is disposed on an extension of the direction in which gas flows from the inlet portion 211 into the internal space 210a (the direction from left to right in FIG. 1 ). The pressure display unit 252 displays the measured pressure value detected by the pressure detection unit 251 and outputs the measured pressure value to a logger 262.

[0078] The logger 261 is a device that acquires and records information related to the operation of the gas sensor 100a. The logger 261 is connected to the gas sensor 100a and the gas sensor control unit 95, and acquires, as information related to the operation of the gas sensor 100a, for example, pump currents Ip0, Ip1, and Ip2, voltages V0, V1, V2, and Vref, and voltages Vp1 and Vp2. The logger 261 stores the acquired information in association with time. The logger 262 is a device that acquires and records information related to the pressure of the internal space 210a. The logger 262 is connected to the pressure gauge 250, and acquires the static pressure of the internal space 210a measured by the pressure gauge 250 as information related to the pressure of the internal space 210a. The logger 262 stores the acquired information in association with time. It is preferable that the loggers 261 and 262 have a time resolution of, for example, about 1 msec.

[0079] In the gas sensor testing device 200 configured as described above, the pressure in the internal space 210a can be adjusted by the pressure supplied from the pressure supply unit 220 to the internal space 210a of the chamber 210 and by opening and closing the solenoid valve 230. Fig. 5 is a graph showing the change over time in the static pressure in the internal space 210a, measured by the pressure gauge 250, when the number of times the solenoid valve 230 is opened and closed and the open / close state are variously changed.

[0080] 5 shows the change over time in the static pressure in the internal space 210a when the pressure supply unit 220 supplies a pressure of approximately 260 kPa (the sum of atmospheric pressure and 160 kPa of pressure applied by the pressure supply unit 220) to the internal space 210a and all of the multiple solenoid valves 230 included in the gas sensor testing device 200 are continuously closed. As can be seen from the solid line L0, when all of the multiple solenoid valves 230 are continuously closed, the pressure supplied to the internal space 210a by the pressure supply unit 220, i.e., the total pressure (approximately 260 kPa) of the internal space 210a, is equal to the static pressure in the internal space 210a. In other words, since the total pressure is the sum of the dynamic pressure and the static pressure, the dynamic pressure in the internal space 210a is zero when the solid line L0 is measured. Furthermore, the static pressure in the internal space 210a does not change over time and remains an approximately constant value. This is because when all of the electromagnetic valves 230 are continuously closed, the gas in the internal space 210a of the chamber 210 does not flow and the flow rate is zero. If the fluid density is ρ and the fluid flow rate is v, the dynamic pressure is ρ×v 2 / 2. With the solenoid valve 230 closed, it takes a short time from when the pressure supply unit 220 starts to supply pressure until the pressure in the internal space 210a reaches equilibrium (a state where only static pressure remains), as shown by the solid line L0 in FIG. 5. The shorter this time, the better, and for example, it is preferably a few seconds or less, or one second or less. The length of this time can be adjusted, for example, by adjusting the flow path cross-sectional area of ​​the inlet 211 and the volume of the internal space 210a.

[0081] The dashed line L1 in Figure 5 shows the change over time in the static pressure in the internal space 210a when one solenoid valve 230 is periodically opened and closed and the remaining solenoid valves 230 are closed, with the pressure supplied to the internal space 210a by the pressure supply unit 220 set to the same value (approximately 260 kPa) as when the solid line L0 was measured. The dashed-dotted line L3 shows the change over time in the static pressure in the internal space 210a under the same conditions as the dashed line L1, except that the three solenoid valves 230 are synchronously and cyclically opened and closed. The two-dot-dash line L6 shows the change over time in the static pressure in the internal space 210a under the same conditions as the dashed line L1, except that the number of outlets 212 in the chamber 210 and the number of solenoid valves 230 connected thereto are six, and the six solenoid valves 230 are synchronously and cyclically opened and closed. As can be seen from these lines L1, L3, and L6, when the solenoid valve 230 is periodically opened and closed, the static pressure in the internal space 210a is lower than the pressure supplied to the internal space 210a by the pressure supply unit 220, i.e., the total pressure (approximately 260 kPa) in the internal space 210a. Because the total pressure is equal to the sum of the static pressure and the dynamic pressure, it can be seen that dynamic pressure is generated in the internal space 210a when the solenoid valve 230 is periodically opened and closed. This is because, when one or more solenoid valves 230 are repeatedly opened and closed, gas in the internal space 210a of the chamber 210 flows out of the chamber 210 via one or more outlets 212, generating a flow velocity in the gas in the internal space 210a. As described above, the solid line L0 in FIG. 5 is equal to the total pressure in the internal space 210a. Therefore, the difference between the solid line L0 and the dashed line L1 is equal to the dynamic pressure generated in the internal space 210a when the dashed line L1 is measured. The same applies to the dashed-dotted line L3 and the dashed-two-dotted line L6. Furthermore, as can be seen from a comparison of the lines L1, L3, and L6, the greater the number of solenoid valves 230 that are opened and closed, the greater the dynamic pressure generated in the internal space 210a (the smaller the static pressure). Therefore, by adjusting the number of solenoid valves 230 that are opened and closed, it is possible to adjust the magnitude of the dynamic pressure generated in the internal space 210a and the proportion of the dynamic pressure to the total pressure in the internal space 210a (the ratio of dynamic pressure to static pressure). Furthermore, as can be seen from the lines L1, L3, and L6, the dynamic pressure generated in the internal space 210a fluctuates periodically in accordance with the opening and closing cycle of the solenoid valves 230, causing gas pulsation in the internal space 210a.The period of the dynamic pressure (period of the pulsation) can also be adjusted by adjusting the period of opening and closing of the solenoid valves 230. Furthermore, although not shown, even if the number of solenoid valves 230 that open and close is the same, if the period of opening and closing is changed, the value of the dynamic pressure generated in the internal space 210a (e.g., the average value of the periodically fluctuating dynamic pressure) also changes. For example, the shorter the period of opening and closing (the higher the frequency of opening and closing), the greater the dynamic pressure becomes, and the smaller the value of the ratio of static pressure to dynamic pressure (static pressure / dynamic pressure) becomes. Therefore, in the gas sensor testing device 200, various dynamic pressures can be generated in the internal space 210a by adjusting the number and period of opening and closing of the solenoid valves 230. The gas sensor testing device 200 may be able to adjust the ratio of static pressure to dynamic pressure (static pressure / dynamic pressure) during dynamic pressure generation, for example, within a range of 2 to 16. Furthermore, the gas sensor testing device 200 can generate dynamic pressure and pulsation in the internal space 210a using the pressure supply unit 220 and the solenoid valve 230, so that the gas sensor 100a can be tested by simulating the dynamic pressure and pulsation of the exhaust gas of an internal combustion engine without using an internal combustion engine.

[0082] Next, a method for manufacturing the gas sensor 100a, which involves testing using the gas sensor testing apparatus 200, will be described. Fig. 6 is a process chart showing an example of the steps in the method for manufacturing the gas sensor 100a. As shown in Fig. 6, in the method for manufacturing the gas sensor 100a, first, the gas sensor 100a is manufactured (step S100). Next, the manufactured gas sensor 100a is subjected to a test method using the gas sensor testing apparatus 200 to evaluate the dynamic pressure resistance performance of the gas sensor 100a (steps S110 to S130).

[0083] Step S100 will be described. In step S100, first, the sensor element 101 is fabricated. When fabricating the sensor element 101, first, a plurality of (six in this embodiment) unsintered ceramic green sheets corresponding to the element body 102 are prepared. Next, notches, through holes, grooves, etc. are formed in each green sheet by punching or the like, as needed, and the electrodes 22, 23, 42, 44, 51, heater 72, wiring patterns, etc. are formed by screen printing. Each green sheet is then dried, and thereafter, the plurality of green sheets are stacked to form a laminate. The laminate thus obtained includes a plurality of element bodies 102. The laminate is cut into pieces the size of the element bodies 102, and the pieces are fired at a predetermined firing temperature to obtain the element bodies 102 (sensor elements 101). After the element body 102 is obtained by firing, a porous protective layer covering the outer surface of the front end of the element body 102 may be formed by, for example, plasma spraying or dipping, thereby manufacturing the sensor element 101 including the element body 102 and the porous protective layer. After manufacturing the sensor element 101 in this manner, the gas sensor 100a incorporating the sensor element 101 is manufactured. Specifically, the sensor element 101 is housed in a sensor assembly 111 and sealed and fixed therein, and the connector electrodes of the sensor element 101 are electrically connected to the lead wires, and the lead wires are extended from the sensor assembly 111 to the outside. A protective cover 110 is also attached to the front end of the sensor element 101. This completes the gas sensor 100a.

[0084] After fabricating the gas sensor 100a in step S100, the worker mounts the gas sensor 100a in the chamber 210 as shown in FIG. 1 and connects the lead wires drawn from the gas sensor 100a to the gas sensor control unit 95 and the logger 261, and then performs steps S110 to S130.

[0085] Step S110 will now be described. In step S110, the operator acquires the pump current Ip0 of the gas sensor 100a attached to the chamber 210 when the three solenoid valves 230 are continuously closed. Specifically, the operator first operates the pressure supply unit 220 and the gas sensor control unit 95 so that the pressure supply unit 220 supplies pressure to the internal space 210a and the gas sensor control unit 95 executes the heater control process, the adjustment pump control process (the main pump control process and the auxiliary pump control process), and the measurement pump control process. The logger 261 continuously records the value of the pump current Ip0 flowing through the main pump cell 21 in association with time. The operator then acquires, from among the pump current Ip0 recorded in the logger 261, the value of the pump current Ip0 after the pressure in the internal space 210a stabilizes and the temperature of the heater 72 stabilizes near the target temperature as the value of the pump current Ip0 when the three solenoid valves 230 are continuously closed. Thus, in step S110, while the three solenoid valves 230 are continuously closed, the gas sensor control unit 95 controls the gas sensor 100a so that it operates in the same manner as when detecting the concentration of a specific gas in the measurement gas, and obtains the pump current Ip0 (the pump current that flows when the main pump cell 21 pumps oxygen due to the voltage Vp0 applied between the inner pump electrode 22 and the outer pump electrode 23) as information regarding the operation of the gas sensor 100a at that time. In this way, the operator obtains the pump current Ip0 when no dynamic pressure is generated in the internal space 210a of the chamber 210.

[0086] Step S120 will now be described. In step S120, the operator acquires the pump current Ip0 of the gas sensor 100a attached to the chamber 210 when the three solenoid valves 230 are synchronously and periodically opening and closing. This step S120 is performed similarly to step S110, except that the operator operates the solenoid valve control unit 240 so that the solenoid valve control unit 240 synchronously opens and closes the three solenoid valves 230 at a predetermined period. Furthermore, when step S120 is performed subsequent to step S110, the pressure supply unit 220 and the gas sensor control unit 95 only need to continue the same operations and controls as in step S110. Through step S120, the operator acquires the pump current Ip0 when periodic dynamic pressure, i.e., gas pulsation, is generated in the internal space 210a of the chamber 210. The cycle of opening and closing the solenoid valves 230 and the number of solenoid valves 230 to be opened and closed in step S120 are determined in advance through experiments and analysis based on the dynamic pressure value and pulsation cycle of the measured gas expected when the gas sensor 100a is actually used.

[0087] Step S130 will now be described. In step S130, the operator evaluates the dynamic pressure resistance of the gas sensor 100a based on the difference between the pump current Ip0 acquired in step S110 and the pump current Ip0 acquired in step S120. Here, dynamic pressure resistance indicates the gas sensor 100a's resistance to dynamic pressure. A gas sensor 100a that is less susceptible to dynamic pressure can be said to have higher dynamic pressure resistance. For example, even if the composition of the measurement gas is the same, changes in the dynamic pressure of the measurement gas may cause changes in the pump currents Ip0, Ip1, and Ip2 of the gas sensor 100a. Furthermore, changes in the pump currents Ip0, Ip1, and Ip2 due to the presence or absence of dynamic pressure and its magnitude may result in a decrease in the accuracy of detecting the concentration of a specific gas. Furthermore, when detecting the oxygen concentration in the measurement gas based on the pump current Ip0 as described above, changes in the pump current Ip0 due to the presence or absence of dynamic pressure and its magnitude may result in a decrease in the accuracy of detecting the oxygen concentration. Therefore, it can be said that the gas sensor 100a whose pump currents Ip0, Ip1, and Ip2 are less likely to change even when the presence or absence of dynamic pressure or the magnitude of dynamic pressure changes has a higher dynamic pressure resistance performance and is less likely to decrease in the detection accuracy of the specific gas concentration and the detection accuracy of the oxygen concentration. Therefore, in step S130, the operator compares the value of the pump current Ip0 of the pump currents Ip0, Ip1, and Ip2, acquired in step S110, i.e., the value when no dynamic pressure is generated in the internal space 210a, with the value acquired in step S120, i.e., the value when dynamic pressure is generated in the internal space 210a, and if the difference between the two is small, the operator evaluates the gas sensor 100a as having a high dynamic pressure resistance performance. For example, the operator may define the average value of the pump current Ip0 obtained in step S110 over a predetermined time period (e.g., several tens of msec) as the static pressure pump current Ip0s, and the average value of the pump current Ip0 obtained in step S120 over a predetermined time period (e.g., several tens of msec) as the dynamic pressure pump current Ip0d, and derive the dynamic pressure resistance index Ip0error [%] using the following equation (1). The closer this dynamic pressure resistance index Ip0error is to 0%, the smaller the difference between the dynamic pressure pump current Ip0d and the static pressure pump current Ip0s is, and the higher the dynamic pressure resistance performance of the gas sensor 100a can be said to be. For example, the operator may evaluate the dynamic pressure resistance performance of the gas sensor 100a as high when the derived dynamic pressure resistance index Ip0error is equal to or less than a predetermined upper limit.

[0088] Ip0error=100×{(Ip0d / Ip0s)-1} (1)

[0089] By performing steps S110 to S130, the dynamic pressure resistance performance is evaluated and the gas sensor 100a with evaluated dynamic pressure resistance is obtained. Note that the gas sensor 100a evaluated as having low dynamic pressure resistance in step S130 may be investigated for the cause or discarded. For example, if the shape of the measurement gas flow portion of the manufactured sensor element 101 is defective, the dynamic pressure resistance performance may be lower than expected. Therefore, the dynamic pressure resistance performance evaluation test can discover such a defective gas sensor 100a.

[0090] Either step S110 or step S120 may be performed first. Furthermore, at least some of the steps S110 to S130 described above as being performed by an operator may be performed by a test control device (not shown) that controls the entire gas sensor testing apparatus 200. The test control device may be, for example, a microprocessor equipped with a CPU, a memory, and the like. The test control device may control the pressure supply unit 220, the solenoid valve control unit 240, the gas sensor control unit 95, the loggers 261 and 262, acquire information stored in the loggers 261 and 262, and derive the dynamic pressure resistance index Ip0error and evaluate the dynamic pressure resistance performance based on the acquired information.

[0091] Here, the correspondence between the components of this embodiment and the components of the present invention will be clarified. In this embodiment, the chamber 210 corresponds to the chamber of the present invention, the pressure supply unit 220 corresponds to the pressure supply unit, and the solenoid valve 230 corresponds to the opening / closing mechanism. The solenoid valve control unit 240 corresponds to the opening / closing control unit. Furthermore, the element body 102 corresponds to the element body, the inner pump electrode 22 corresponds to the inner electrode, the outer pump electrode 23 corresponds to the outer electrode, the main pump cell 21 corresponds to the pump cell, the gas sensor control unit 95 corresponds to the gas sensor control unit, and the logger 261 corresponds to the measurement unit. Furthermore, step S120 corresponds to the first step, step S110 corresponds to the second step, and step S130 corresponds to the third step. Step S100 corresponds to the fabrication step, and steps S110 to S130 correspond to the inspection steps.

[0092] The gas sensor testing apparatus 200 of this embodiment described above in detail can generate dynamic pressure in the internal space 210a of the chamber 210 by repeatedly opening and closing the solenoid valve 230 while supplying pressure from the pressure supply unit 220 to the internal space 210a of the chamber 210. Therefore, by acquiring information about the operation of the gas sensor 100a attached to the chamber 210 at this time, it is possible to investigate the relationship between the dynamic pressure and the operation of the gas sensor 100a. Therefore, by using this gas sensor testing apparatus 200, it is possible to investigate the effect of the dynamic pressure of the measured gas on the gas sensor 100a (for example, the effect on the detection accuracy of the concentration of a specific gas).

[0093] Furthermore, the solenoid valve control unit 240 periodically opens and closes the solenoid valve 230, thereby generating periodic changes in dynamic pressure, i.e., pulsations, in the internal space 210a of the chamber 210. Therefore, the gas sensor testing device 200 can examine the effect of the pulsations of the measurement gas on the gas sensor 100a.

[0094] Furthermore, the solenoid valve control unit 240 synchronously opens and closes two or more of the multiple solenoid valves 230. Therefore, compared to when one solenoid valve 230 is repeatedly opened and closed (for example, the dashed line L1 in FIG. 5), a large dynamic pressure is more likely to be generated in the internal space 210a of the chamber 210 (for example, the dashed line L3 and the two-dot chain line L6 in FIG. 5).

[0095] In the testing method using the gas sensor testing apparatus 200, the pump current Ip0 of the main pump cell 21 is acquired as information related to the operation of the gas sensor 100a. This allows for investigating the effect of the dynamic pressure of the measurement gas on the pump current Ip0 of the gas sensor 100a. Furthermore, in step S120, information related to the operation of the gas sensor 100a when dynamic pressure is generated in the internal space 210a of the chamber 210 is acquired, and in step S110, information related to the operation of the gas sensor 100a when no dynamic pressure is generated in the internal space 210a of the chamber 210 is acquired. Therefore, compared to performing only step S120 without performing step S110, for example, the effect of the dynamic pressure of the measurement gas on the gas sensor 100a can be investigated in more detail. In step S130, the dynamic pressure resistance of the gas sensor 100a can be evaluated based on the information acquired in steps S110 and S120. Furthermore, by evaluating the dynamic pressure resistance performance based on the difference between the pump current Ip0 acquired in step S110 and the pump current Ip0 acquired in step S120, the dynamic pressure resistance performance of the gas sensor can be appropriately evaluated.

[0096] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention.

[0097] For example, in the above-described embodiment, the solenoid valve control unit 240 periodically opens and closes the solenoid valve 230 in step S120. However, the solenoid valve 230 may be opened and closed repeatedly, without being limited to a periodic pattern. For example, the solenoid valve 230 may be opened and closed randomly, or may be opened and closed according to a predetermined pattern that is not periodic. Furthermore, the solenoid valve control unit 240 may leave the solenoid valve 230 open without repeatedly opening and closing it. In this case, too, the opening of the solenoid valve 230 allows gas to flow within the internal space 210a, thereby generating dynamic pressure in the internal space 210a. Furthermore, in step S120, the solenoid valve control unit 240 synchronously opens and closes two or more solenoid valves 230. However, the present invention is not limited to this. Alternatively, only one solenoid valve 230 may be opened and closed, or one or more of the multiple solenoid valves 230 may be opened and closed asynchronously with the other solenoid valves 230.

[0098] In the above-described embodiment, in steps S110 and S120, the gas sensor control unit 95 controls the gas sensor 100a so that it operates in the same manner as when detecting the concentration of a specific gas in the measurement gas. However, this is not limiting. For example, in steps S110 and S120, the gas sensor control unit 95 may execute the heater control process and the process of applying a predetermined voltage Vp0 between the main pump cell 21 and the outer pump electrode 23 to cause the main pump cell 21 to pump oxygen, but may not execute the adjustment pump control process (main pump control process and auxiliary pump control process) and the measurement pump control process. Even in this case, it is possible to examine the effect of dynamic pressure on the pump current Ip0.

[0099] In the above-described embodiment, the pump current Ip0 is acquired as information related to the operation of the gas sensor in steps S110 and S120. However, this is not limiting. For example, the pump current Ip1 or the pump current Ip2 may be acquired in addition to or instead of the pump current Ip0.

[0100] In the above-described embodiment, step S110 may be omitted. In this case, the pump current Ip0 and the dynamic pressure pump current Ip0d can be obtained in step S120, allowing the relationship between the dynamic pressure and the operation of the gas sensor 100a to be investigated. Furthermore, for example, if an allowable range for the pump current Ip0 and the dynamic pressure pump current Ip0d flowing through the main pump cell 21 in step S120 is determined in advance through experimentation or analysis, the dynamic pressure resistance of the gas sensor 100a may be evaluated based on the allowable range and the pump current Ip0 and the dynamic pressure pump current Ip0d obtained in step S120.

[0101] In the above-described embodiment, in step S130, the dynamic pressure resistance performance of the gas sensor 100a is evaluated by determining whether the dynamic pressure resistance performance is high based on the value of the dynamic pressure resistance index Ip0error. However, this is not limited to this. "Evaluating the dynamic pressure resistance performance" may refer to, for example, deriving an evaluation value representing the dynamic pressure resistance performance of the gas sensor (e.g., the value of the dynamic pressure resistance index Ip0error) based on the information acquired in steps S110 and S120. In other words, "evaluating the dynamic pressure resistance performance" does not have to include determining whether the dynamic pressure resistance performance is high. Furthermore, step S130 may be omitted.

[0102] In the above-described embodiment, the electromagnetic valve 230 opens and closes the exhaust path from the outlet 212 of the gas in the internal space 210a, but the opening and closing mechanism is not limited to the electromagnetic valve 230 and may be any other opening and closing mechanism.

[0103] In the above-described embodiment, the gas sensor control unit 95 of the gas concentration measurement system 100 also serves as a gas sensor control unit as a component of the gas sensor testing device 200, but this is not limiting. The gas sensor testing device 200 may include a gas sensor control unit for testing, separate from the gas sensor control unit 95, instead of the gas sensor control unit 95.

[0104] In the above-described embodiment, the testing method (steps S110 to S130) using the gas sensor testing apparatus 200 is performed as part of the manufacturing method of the gas sensor 100a, but this is not limiting. The above-described testing method may be performed independently of the manufacturing method of the gas sensor 100a, for example, for the purpose of investigating or analyzing the gas sensor 100a.

[0105] In the above-described embodiment, the outer pump electrode 23 serves as an electrode paired with the inner pump electrode 22 in the main pump cell 21 (also referred to as an outer main pump electrode), an electrode paired with the auxiliary pump electrode 51 in the auxiliary pump cell 50 (also referred to as an outer auxiliary pump electrode), and an electrode paired with the measurement electrode 44 in the measurement pump cell 41 (also referred to as an outer measurement electrode), but is not limited to this. Any one or more of the outer main pump electrode, the outer auxiliary pump electrode, and the outer measurement electrode may be provided separately from the outer pump electrode 23 on the outer surface of the element body 102 so as to come into contact with the measurement gas.

[0106] In the above-described embodiment, the outer pump electrode 23 is exposed to the outside of the sensor element 101, but this is not limiting and the outer pump electrode 23 may be provided on the outer surface of the element body 102 so as to be in contact with the measurement gas. For example, the sensor element 101 may be provided with a porous protective layer that covers the element body 102 and allows the measurement gas to pass through, and the outer pump electrode 23 may also be covered with the porous protective layer.

[0107] In the above-described embodiment, the sensor element 101 detects the NOx concentration in the measurement gas. However, this is not limiting, as long as it detects the concentration of a specific gas in the measurement gas. For example, the specific gas concentration may be other oxide concentrations, not just NOx. When the specific gas is an oxide, oxygen is generated when the specific gas itself is reduced in the third internal space 61, as in the above-described embodiment. The measurement pump cell 41 can detect the specific gas concentration by obtaining a detection value corresponding to this oxygen (e.g., pump current Ip2). Alternatively, the specific gas may be a non-oxide, such as ammonia. When the specific gas is a non-oxide, the specific gas is converted to an oxide (e.g., ammonia is converted to NO). When the converted gas is reduced in the third internal space 61, oxygen is generated. The measurement pump cell 41 can detect the specific gas concentration by obtaining a detection value corresponding to this oxygen (e.g., pump current Ip2). For example, the inner pump electrode 22 in the first internal space 20 functions as a catalyst, thereby converting ammonia to NO in the first internal space 20.

[0108] In the above-described embodiment, the control circuit 96 sets (feedback-controls) the target value V0* of the voltage V0 based on the pump current Ip1 so that the pump current Ip1 becomes the target value Ip1*, and feedback-controls the voltage Vp0 so that the voltage V0 becomes the target value V0*. However, other control may be performed. For example, the control circuit 96 may feedback-control the voltage Vp0 based on the pump current Ip1 so that the pump current Ip1 becomes the target value Ip1*. That is, the control circuit 96 may omit obtaining the voltage V0 from the main pump control oxygen partial pressure detection sensor cell 80 and setting the target value V0*, and may directly control the voltage Vp0 (and thus the pump current Ip0) based on the pump current Ip1. [Industrial Applicability]

[0109] The present invention can be used in the manufacturing industry of gas sensors that detect the concentration of specific gases such as NOx in measurement gases such as automobile exhaust gases. [Explanation of symbols]

[0110] 1 first substrate layer, 2 second substrate layer, 3 third substrate layer, 4 first solid electrolyte layer, 5 spacer layer, 6 second solid electrolyte layer, 10 gas inlet, 11 first diffusion rate-controlling section, 12 buffer space, 13 second diffusion rate-controlling section, 20 first internal space, 21 main pump cell, 22 inner pump electrode, 22a ceiling electrode section, 22b bottom electrode section, 23 outer pump electrode, 24 variable power supply, 30 third diffusion rate-controlling section, 40 second internal space, 41 measurement pump cell, 42 reference electrode, 43 reference gas introduction space, 44 measurement electrode, 46 variable power supply, 48 reference gas introduction layer, 49 reference gas introduction section, 49a inlet section, 50 auxiliary pump cell, 51 auxiliary pump electrode, 51a ceiling electrode section, 51b bottom electrode section, 52 variable power supply, 60 fourth diffusion rate-controlling section, 61 Third internal cavity, 70 heater portion, 71 heater connector electrode, 72 heater, 73 through hole, 74 heater insulating layer, 75 pressure release hole, 76 heater power supply, 80 oxygen partial pressure detection sensor cell for controlling main pump, 81 oxygen partial pressure detection sensor cell for controlling auxiliary pump, 82 oxygen partial pressure detection sensor cell for controlling measurement pump, 83 sensor cell, 95 gas sensor control portion, 96 control circuit, 97 CPU, 98 memory portion, 100 gas concentration measurement system, 100a gas sensor, 101 sensor element, 102 element body, 10 protective cover, 111 sensor assembly, 200 gas sensor testing device, 210 chamber, 210a internal space, 211 inlet portion, 212 outlet portion, 213 gas sensor mounting portion, 220 pressure supply portion, 221 gas supply source, 222 regulator, 230 Solenoid valve, 240 solenoid valve control section, 241 function generator, 242 control circuit, 250 pressure gauge, 251 pressure detection section, 252 pressure display section, 261, 262 logger.

Claims

1. A testing device for a gas sensor for detecting a specific gas concentration in a measurement gas, comprising: a chamber having an internal space, a gas inlet port into the internal space, a gas outlet port from the internal space, and a gas sensor mounting portion to which the gas sensor can be mounted in a manner that allows detection of the specific gas concentration in the gas in the internal space; a pressure supply unit that supplies pressure to the internal space through the inlet unit; an opening / closing mechanism connected to the outlet portion and configured to open and close a discharge path for the gas in the internal space from the outlet portion; A gas sensor test device comprising:

2. 2. The gas sensor testing device according to claim 1, an opening / closing control unit that periodically opens and closes the opening / closing mechanism; The gas sensor testing device further comprises:

3. 3. The gas sensor testing device according to claim 1, further comprising: the chamber includes a plurality of outlet portions; the opening and closing mechanism is connected to each of the plurality of outlets, The testing apparatus further includes an opening / closing control unit that synchronously opens and closes two or more of the plurality of opening / closing mechanisms. Gas sensor testing equipment.

4. 3. The gas sensor testing device according to claim 1, further comprising: The gas sensor comprises: an element body having an oxygen ion conductive solid electrolyte body and a measurement gas flow section provided therein through which the measurement gas is introduced from a gas inlet and flows; a pump cell including an inner electrode provided in the measurement gas flow portion and an outer electrode provided on an outer surface of the element body so as to come into contact with the measurement gas; Equipped with The test device comprises: a gas sensor control unit that applies a voltage between the inner electrode and the outer electrode to cause the pump cell to pump oxygen; a measuring unit for measuring a pump current that flows when the pump cell pumps oxygen; Further provided with Gas sensor testing equipment.

5. A gas sensor testing method using a gas sensor testing device for detecting a specific gas concentration in a measurement gas, comprising: The test device comprises: a chamber having an internal space, a gas inlet port into the internal space, a gas outlet port from the internal space, and a gas sensor mounting portion to which the gas sensor can be mounted in a manner that allows detection of the specific gas concentration in the gas in the internal space; a pressure supply unit that supplies pressure to the internal space through the inlet unit; an opening / closing mechanism connected to the outlet portion and configured to open and close a discharge path for the gas in the internal space from the outlet portion; Equipped with The testing method includes a first step of acquiring information about operation of the gas sensor attached to the chamber when the opening / closing mechanism is opened or repeatedly opened and closed while supplying pressure from the pressure supply unit to the internal space, Test methods for gas sensors.

6. 6. A method for testing a gas sensor according to claim 5, comprising: the first step periodically opens and closes the opening and closing mechanism; Test methods for gas sensors.

7. 7. A method for testing a gas sensor according to claim 5 or 6, comprising: a second step of acquiring information regarding the operation of the gas sensor attached to the chamber when the opening / closing mechanism is continuously closed; The gas sensor testing method further comprises:

8. 8. A method for testing a gas sensor according to claim 7, comprising: a third step of evaluating the dynamic pressure resistance performance of the gas sensor based on the information acquired in the first step and the information acquired in the second step; The gas sensor testing method further comprises:

9. 7. A method for testing a gas sensor according to claim 5 or 6, comprising: The gas sensor comprises: an element body having an oxygen ion conductive solid electrolyte body and a measurement gas flow section provided therein through which the measurement gas is introduced from a gas inlet and flows; a pump cell including an inner electrode provided in the measurement gas flow portion and an outer electrode provided on an outer surface of the element body so as to come into contact with the measurement gas; Equipped with the information relating to the operation of the gas sensor is a value of a pump current that flows when the pump cell pumps oxygen in response to a voltage applied between the inner electrode and the outer electrode; Test methods for gas sensors.

10. 9. A gas sensor testing method according to claim 8, comprising: The gas sensor comprises: an element body having an oxygen ion conductive solid electrolyte body and a measurement gas flow section provided therein through which the measurement gas is introduced from a gas inlet and flows; a pump cell including an inner electrode provided in the measurement gas flow portion and an outer electrode provided on an outer surface of the element body so as to come into contact with the measurement gas; Equipped with In the first and second steps, a value of a pump current that flows when the pump cell pumps oxygen due to a voltage applied between the inner electrode and the outer electrode is acquired as information related to the operation of the gas sensor; the third step evaluates the dynamic pressure resistance performance based on a difference between the pump current acquired in the first step and the pump current acquired in the second step. Test methods for gas sensors.

11. A method for manufacturing a gas sensor including the method for testing a gas sensor according to claim 8, comprising the steps of: a manufacturing step of manufacturing the gas sensor; an inspection step of evaluating the dynamic pressure resistance performance of the gas sensor manufactured in the manufacturing step by performing the test method; Including, A method for manufacturing a gas sensor.

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