JP6500547B2 - Gas sensor - Google Patents

Description

  The present invention relates to a gas sensor that measures the concentration of a specific gas contained in a measurement gas.

  As a gas sensor for measuring the concentration of a specific gas contained in a measurement gas, a measurement gas chamber into which the measurement gas is introduced, a reference gas chamber into which a reference gas such as the atmosphere is introduced, and the measurement gas chambers It is known to have a solid electrolyte body interposed between the reference gas chamber and having oxygen ion conductivity (see Patent Document 1 below). The measured gas is, for example, an exhaust gas of a vehicle, and the specific gas is, for example, NOx.

  A plurality of electrodes are formed on the surface of the solid electrolyte body. Further, a heater is provided at a position adjacent to the solid electrolyte body with the reference gas chamber interposed therebetween. The heater is configured to heat the solid electrolyte body and the electrode.

  The electrodes include a pump electrode and a sensor electrode formed on the surface of the solid electrolyte body on the measurement gas chamber side, and a reference electrode formed on the surface of the solid electrolyte body on the reference gas chamber side. The pump electrode, the solid electrolyte body, and the reference electrode form a pump cell for discharging oxygen in the measurement gas chamber to the reference gas chamber. Further, a sensor cell is formed by the sensor electrode, the solid electrolyte body, and the reference electrode. A sensor cell is a cell for measuring the density | concentration of specific gas contained in to-be-measured gas after reducing oxygen concentration by a pump cell.

  In order for the pump cell and the sensor cell to exhibit their functions, it is necessary to heat the solid electrolyte body and each electrode sufficiently. Therefore, in the gas sensor, the solid electrolyte body and the electrode are heated using the heater.

JP 2013-140175 A

  However, the gas sensor has a problem that the power consumption of the heater is large. That is, since the pump electrode is formed on the surface of the solid electrolyte body on the measurement gas chamber side, it is separated from the heater and is difficult to heat. Therefore, in order to heat the pump electrode sufficiently, it is necessary to increase the calorific value of the heater, and there is a problem that the power consumption of the heater tends to increase.

  In the gas sensor, the temperature of the pump electrode is lowered when the engine of the vehicle is idle-stopped or when cold air is hit, and the oxygen discharge capacity of the pump cell is easily reduced. Therefore, there is a problem that it takes time to heat the pump electrode again to discharge the oxygen.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a gas sensor which can further reduce the power consumption of the heater and hardly reduce the temperature of the pump electrode.

One embodiment of the present invention is a gas sensor that measures the concentration of a specific gas contained in a measurement gas,
A plate-like solid electrolyte body having oxygen ion conductivity;
A heater which is provided at a position adjacent to the solid electrolyte body at a predetermined interval in the thickness direction of the solid electrolyte body, and which heats the solid electrolyte body;
A partition portion interposed between the solid electrolyte body and the heater;
A reference gas chamber which is surrounded by the solid electrolyte body, the heater and the partition wall and into which a reference gas is introduced;
A measurement gas chamber formed on the opposite side of the solid electrolyte body to the side on which the reference gas chamber is provided, into which the measurement gas is introduced;
A pump electrode and a sensor electrode formed on the surface of the solid electrolyte body on the measurement gas chamber side;
A reference electrode formed on the surface of the solid electrolyte body on the side of the reference gas chamber;
A pump cell for discharging oxygen contained in the measurement gas to the reference gas chamber is formed by the pump electrode, the solid electrolyte body, and the reference electrode.
The sensor electrode, the solid electrolyte body, and the reference electrode form a sensor cell for measuring the concentration of the specific gas contained in the measurement gas from which oxygen has been exhausted using the pump cell,
When viewed in the thickness direction, at least a portion of the pump electrode overlaps the partition wall, and a portion of the sensor electrode overlaps the partition wall .
On the side of the solid electrolyte body opposite to the side on which the partition portion is disposed, a partition portion surrounding the periphery of the measurement gas chamber is disposed, and both the introduction direction of the measurement gas and the thickness direction are provided. In the width direction orthogonal to the length, the length of the portion of the partition interposed between the measured gas chamber and the external space is the length between the reference gas chamber and the external space of the partition. The gas sensor is characterized in that it is shorter than the length of the portion to be

The gas sensor is configured such that at least a portion of the pump electrode overlaps the partition wall when viewed in the thickness direction.
In this way, the power consumption of the heater can be reduced, and the pump electrode can be sufficiently heated. That is, the heat of the heater is transmitted mainly to the solid electrolyte body through the above-mentioned partition wall portion. Therefore, in the solid electrolyte body, a portion adjacent to the partition wall (hereinafter, also referred to as a partition adjacent portion) tends to have a higher temperature than a portion adjacent to the reference gas chamber. Therefore, at least a part of the pump electrode may be formed on the partition adjacent to the partition of the solid electrolyte body if the pump electrode is configured such that at least a part of the pump electrode overlaps the partition when viewed from the thickness direction. It becomes easy to heat the pump electrode. Therefore, the power consumption of the heater can be reduced.

  In addition, since the partition wall has a larger heat capacity than the reference gas in the reference gas chamber, the temperature hardly changes. Therefore, the temperature hardly changes also at the portion adjacent to the partition wall. Therefore, if at least a part of the pump electrode is formed in the partition adjacent part, the temperature of the pump electrode can be easily maintained constant. Therefore, even when cold air hits the gas sensor, the temperature of the pump electrode does not easily decrease, and reduction in the oxygen discharge capacity of the pump cell can be suppressed.

  As described above, according to the present invention, it is possible to provide a gas sensor that can further reduce the power consumption of the heater and that the temperature of the pump electrode does not easily decrease.

FIG. 5 is a cross-sectional view of the gas sensor in Example 1, and is a cross-sectional view taken along line II of FIG. 4; II-II sectional drawing of FIG. III-III sectional drawing of FIG. IV-IV sectional drawing of FIG. FIG. 5 is a cross-sectional view taken along line VV of FIG. 4. FIG. 2 is an exploded perspective view of the gas sensor in the first embodiment. The graph showing the relationship between the pump capacity per unit area of a pump electrode in Example 1, and temperature. The graph in the Example 1 showing the relationship between the temperature of the pump electrode, and the distance from the center of the pump electrode in the width direction. The graph showing the relationship between the pump capacity per unit area of a pump electrode in Example 1, and the distance from the center of the pump electrode in the width direction. FIG. 12 is a cross-sectional view of a gas sensor in Example 2, and is a cross-sectional view taken along line XX in FIG. XI-XI sectional drawing of FIG. FIG. 10 is a cross-sectional view of a gas sensor in a third embodiment. FIG. 10 is a cross-sectional view of a gas sensor in a third embodiment.

  The gas sensor may be a NOx sensor for measuring the concentration of NOx contained in the exhaust gas of a vehicle.

Example 1
An embodiment of the gas sensor will be described with reference to FIGS. 1 to 9. As shown in FIGS. 1 to 4, the gas sensor 1 of the present embodiment includes a measurement gas chamber 11, a reference gas chamber 12, a solid electrolyte body 2, a heater 3, a partition portion 4, a pump electrode 5 p, and a sensor An electrode 5s and a reference electrode 5b are provided.
The solid electrolyte body 2 has oxygen ion conductivity and is formed in a plate shape. The solid electrolyte body 2 is made of, for example, zirconia.
As shown in FIG. 1, the heater 3 is provided at a position adjacent to the solid electrolyte body 2 at a predetermined interval in the thickness direction (Z direction) of the solid electrolyte body 2. The heater 3 is provided to heat the solid electrolyte body 2.

The partition portion 4 is interposed between the solid electrolyte body 2 and the heater 3.
The reference gas chamber 12 is surrounded by the solid electrolyte body 2, the heater 3 and the partition 4. A reference gas such as the atmosphere is introduced into the reference gas chamber 12.
The measurement gas chamber 11 is formed on the opposite side of the solid electrolyte body 2 to the side where the reference gas chamber 11 is provided. A measurement gas g is introduced into the measurement gas chamber 11.

The pump electrode 5 p and the sensor electrode 5 s are formed on the surface of the solid electrolyte body 2 on the measurement gas chamber 11 side.
The reference electrode 5 b is formed on the surface of the solid electrolyte body 2 on the side of the reference gas chamber 12.
A pump cell 6p is formed by the pump electrode 5p, the solid electrolyte body 2 and the reference electrode 5b. The pump cell 6 is a cell for discharging oxygen contained in the measurement gas g to the reference gas chamber 12.
A sensor cell 6s is formed by the sensor electrode 5s, the solid electrolyte body 2 and the reference electrode 5b. The sensor cell 6s is a cell for measuring the concentration of a specific gas contained in the measurement gas g from which oxygen is exhausted using the pump cell 6p.
As shown in FIGS. 1 and 2, when viewed in the Z direction, a part of the pump electrode 5 p is configured to overlap the partition 4.

  The gas sensor 1 of the present example is a NOx sensor for measuring the concentration of NOx contained in the exhaust gas of a vehicle.

  As shown in FIGS. 2 and 5, on the surface of the solid electrolyte body 2 on the measurement gas chamber 11 side, a monitor electrode 5m is formed in addition to the pump electrode 5p and the sensor electrode 5s. A monitor cell 6m is formed by the monitor electrode 5m, the solid electrolyte body 2 and the reference electrode 5b. The monitor cell 6m is a cell for measuring the concentration A of residual oxygen contained in the measurement gas g after oxygen is reduced by the pump cell 6p.

  The sensor cell 6s has sensitivity to oxygen in addition to the specific gas. Therefore, the sensor cell 6s measures the total concentration B of the residual oxygen and the specific gas contained in the measurement gas g after the oxygen is reduced by the pump cell 6p.

  The monitor cell 6m and the sensor cell 6s are connected to a control circuit unit (not shown). The control circuit unit is configured to subtract the concentration A of the residual oxygen from the total concentration B to calculate the concentration of the specific gas (NOx) in the gas to be measured.

  The gas sensor 1 of this example includes only one solid electrolyte body 2. That is, in this example, the pump cell 6 p, the monitor cell 6 m, and the sensor cell 6 s share the solid electrolyte body 2.

  As shown in FIG. 2, the gas sensor element 1 includes a gas introduction unit 130 for introducing the measurement gas g into the measurement gas chamber 11. The gas introduction unit 130 is provided with a diffusion resistance unit 13 made of alumina or the like. The diffusion resistance portion 13 limits the flow velocity of the measurement gas g introduced into the measurement gas chamber 11.

  The monitor electrode 5m and the sensor electrode 5s are disposed at positions adjacent to the pump electrode 5p in the introduction direction (X direction) of the measurement gas g. The monitor electrode 5m and the sensor electrode 5s are adjacent to each other in the width direction (Y direction) orthogonal to both the X direction and the Z direction. The monitor electrode 5m and the sensor electrode 5s are disposed downstream of the measurement gas g with respect to the pump electrode 5p. Wirings 51 to 53 are connected to the individual electrodes 5p, 5m, 5s.

As shown in FIG. 2, the Y-direction length L ₁ of the measured gas chamber 11 is longer than the Y-direction length L ₂ (see FIG. 3) of the reference gas chamber 12. Both ends 50 of the pump electrode 5p in the Y direction overlap the partition 4 when viewed from the Z direction. Further, in this example, a part of the monitor electrode 5m and a part of the sensor electrode 5s also overlap the partition 4 in the Z direction.

  Moreover, as shown in FIG. 2, the gas sensor 1 of this example is provided with the division part 14 made of a ceramic. The dividing section 14 divides the measurement gas chamber 11 from the external space S.

Further, as shown in FIG. 3, the Y-direction length L ₄ of the partition 4 between the reference gas chamber 12 and the external space S is between the measured gas chamber 11 (see FIG. 2) and the external space S. , And the length L ₃ of the partition 14 is longer. Further, a reference gas inlet 40 for introducing a reference gas into the reference gas chamber 12 is formed in the partition wall 4.

  Further, as shown in FIG. 1 and FIG. 4, the heater 3 of this example includes a first heater plate 31, a heating element 32 that generates heat by energization, and a second heater plate 33. The two heater plates 31 and 33 are made of ceramic such as alumina. A space surrounded by the heater 3, the solid electrolyte body 2, and the partition wall 4 is a reference gas chamber 12.

  Further, a plate-like member 15 is provided at a position adjacent to the solid electrolyte body 2 with the measured gas chamber 11 interposed therebetween. A space surrounded by the plate member 15, the solid electrolyte body 2, the dividing portion 14 and the diffusion resistance portion 13 is a measurement gas chamber 11.

  As shown in FIG. 6, an external connection electrode 151 is formed on the surface of the plate-like member 15. The external connection electrode 151 is electrically connected to the electrodes 5p, 5m, and 5s via the wirings 51 to 53. The gas sensor 1 of the present example is formed by laminating a plate member 15, a partition 14, a solid electrolyte body 2, a partition 4 and a heater 3.

  Next, the composition of each electrode 5 (5p, 5m, 5s) will be described. The pump electrode 5p and the monitor electrode 5m are made of an alloy of Pt and Au. These electrodes 5p and 5m are active to oxygen molecules and inactive to NOx when a DC voltage is applied. That is, oxygen molecules are reduced to oxygen ions, but NOx molecules do not decompose. The sensor electrode 5s is made of an alloy of Pt and Rh, or Pt. The sensor electrode 5s is active for both oxygen molecules and NOx. That is, it has the property of decomposing both oxygen molecules and NOx to generate oxygen ions.

  When discharging oxygen using the pump cell 6p, as shown in FIG. 4, a DC voltage (hereinafter also referred to as a pump voltage) so that the reference electrode 5b has a high potential between the pump electrode 5p and the reference electrode 5b. Is added. When a pump voltage is applied, oxygen contained in the gas to be measured g is reduced to oxygen ions at the pump electrode 5 p and is discharged into the reference gas chamber 12 through the solid electrolyte body 2.

  As shown in FIG. 5, current sensors 81 and 82 are connected to the monitor cell 6m and the sensor cell 6s, respectively. The current sensors 81 and 82 measure a current flowing through the monitor cell 6m (hereinafter, also referred to as a monitor current) and a current flowing through the sensor cell 6s (hereinafter, also referred to as a sensor current).

  The oxygen remaining in the measurement gas g is reduced at the monitor electrode 5m to be oxygen ions, and is discharged to the reference gas chamber 12 through the solid electrolyte body 2. At this time, a monitor current flows to the monitor cell 6m. By measuring this monitor current, the concentration A of residual oxygen in the measurement gas g is measured. Further, the sensor electrode 5s reduces oxygen and NOx remaining in the measurement gas g to generate oxygen ions. Oxygen ions are discharged to the reference gas chamber 12 through the solid electrolyte body 2. At this time, a sensor current flows in the sensor cell 6s. By measuring this sensor current, the total concentration B of residual oxygen in the gas to be measured g and NOx (specific gas) is measured.

  Next, the difference in pump capacity (the ability to discharge oxygen) between the portion overlapping with the partition wall 4 in the Z direction and the portion not overlapping in the Z direction in the pump electrode 5p will be described. FIG. 7 is a graph showing the relationship between the temperature of the pump electrode 5p and the pump capacity per unit area of the pump electrode 5p. As shown in the figure, the higher the temperature of the pump electrode 5p, the higher the pump capacity. This is because the higher the temperature of the pump electrode 5p, the higher the efficiency of reducing oxygen molecules to oxygen ions.

  FIG. 8 is a graph showing the relationship between the distance from the center O (see FIG. 1) of the pump electrode 5p and the temperature of the pump electrode 5p in the Y direction. As shown in FIG. 1, in the pump electrode 5p, the portion from the center O to the distance r1 does not overlap the partition 4 and the portion from the center O to the distance r1 to r2 is the partition 4 And overlap. Therefore, as shown in FIG. 8, the portion of the pump electrode 5p not overlapping with the partition 4 (the portion from the center O to the distance r1) has a small amount of heat transmitted from the heater 3 and a relatively low temperature. . On the other hand, the heat generated from the heater 3 is efficiently transmitted through the partition portion 4 in the portion overlapping with the partition portion 4 (the portion from the center O to the distance r1 to r2). Is relatively high.

  FIG. 9 is a graph showing the relationship between the distance from the center O of the pump electrode 5p and the pump capacity per unit area of the pump electrode 5p in the Y direction. As shown in the figure, in the pump electrode 5p, a portion up to a distance r1 from the center O does not overlap the partition 4 in the Z direction, so the temperature is low and the pump capacity per unit area is low. Further, in the pump electrode 5p, the portion from the center O to the distance r1 to r2 overlaps the partition 4 in the Z direction, so the temperature is high and the pump performance per unit area is high.

The operation and effect of this example will be described. As shown in FIG. 1 and FIG. 2, the gas sensor 1 of this example is configured such that a part of the pump electrode 5 p overlaps the partition 4 when viewed from the Z direction.
In this way, the power consumption of the heater 3 can be reduced, and the pump electrode 5p can be sufficiently heated. That is, the heat of the heater 3 is transmitted to the solid electrolyte body 2 mainly through the partition wall 4. Therefore, in the solid electrolyte body 2, the temperature (portion adjacent to the partition wall 20) adjacent to the partition wall 4 in the Z direction tends to be higher in temperature than the portion adjacent to the reference gas chamber 12. Therefore, as in the present embodiment, when the pump electrode 5p is partially overlapped with the partition wall 4 when viewed from the Z direction, the pump electrode 5p is partially adjacent to the partition wall of the solid electrolyte body 2 It can be formed in the part 20, and it becomes easy to heat the pump electrode 5p. Therefore, the power consumption of the heater 3 can be reduced.

  Further, since the partition wall portion 4 has a heat capacity larger than that of the reference gas in the reference gas chamber 12, the temperature hardly changes. Therefore, the temperature hardly changes also in the partition adjacent portion 20 of the solid electrolyte body 2. If a portion of the pump electrode 5p is formed on the partition adjacent portion 20 as in this example, the temperature of the pump electrode 5p can be easily maintained constant. Therefore, even when the engine of the vehicle is idle-stopped, or when cold air hits the gas sensor element 1 or the like, the temperature of the pump electrode 5p does not easily decrease, and reduction in the oxygen discharge capacity by the pump cell 6p can be suppressed.

Further, the pump electrode 5p of this example is made of an alloy of Pt and Au.
In this case, the pump electrode 5p can be activated to oxygen and deactivated to NOx.

Further, in this example, as shown in FIGS. 4 and 5, the sensor cell 6s and the pump cell 6p share the same solid electrolyte body 2.
Therefore, it is not necessary to separate the solid electrolyte body 2 for forming the sensor cell 6s and the solid electrolyte body 2 for forming the pump cell 6p, and the number of parts can be reduced. Therefore, the manufacturing cost of the gas sensor 1 can be reduced.

Further, as shown in FIG. 2 and FIG. 5, the gas sensor 1 of this example is configured such that a part of the sensor electrode 5 s overlaps the partition 4 when viewed from the Z direction.
Therefore, a part of the sensor electrode 5s can be formed on the partition adjacent portion 20. Therefore, it is possible to heat the sensor electrode 5s sufficiently while reducing the power consumption of the heater 3. In addition, even when cold air hits the gas sensor 1, the temperature of the sensor electrode 5s does not easily decrease.

Similarly, as shown in FIG. 2 and FIG. 5, the gas sensor 1 of this example is configured such that a part of the monitor electrode 5 m overlaps the partition wall 4 when viewed from the Z direction.
Therefore, a part of the monitor electrode 5m can be formed in the partition adjacent portion 20. Therefore, it is possible to sufficiently heat the monitor electrode 5m while reducing the power consumption of the heater 3. In addition, even when cold air hits the gas sensor 1, the temperature of the monitor electrode 5m does not easily decrease.

  As described above, according to the present embodiment, it is possible to provide a gas sensor that can further reduce the power consumption of the heater and that the temperature of the pump electrode does not easily decrease.

  Although three cells 6 (6p, 6m, 6s) are formed using one solid electrolyte body 2 in this example, the present invention is not limited to this. That is, the solid electrolyte body for forming the pump cell 6p and the solid electrolyte body for forming the monitor cell 6m and the sensor cell 6m may be separately provided.

  Moreover, in this example, although it was comprised so that a part of pump electrode 5p may overlap with the partition part 4 in Z direction, this invention is not limited to this, and all parts of the pump electrode 5p are the partition part 4 and You may comprise so that it may overlap.

(Example 2)
In the following embodiments, among the reference numerals used in the drawings, the same reference numerals as those used in the embodiments indicate the same constituent elements as those of the first embodiment unless otherwise indicated.

  This example is an example in which the shape of the pump electrode 5p is changed. As shown in FIGS. 10 and 11, in the present embodiment, the notch 54 is formed in the portion of the pump electrode 5p overlapping the reference electrode 5b in the Z direction.

The operation and effect of this example will be described. When the notch 54 is formed in the pump electrode 5p, the amount of Au or Pt, which is a constituent material of the pump electrode 5p, can be reduced. Therefore, the manufacturing cost of the gas sensor element 1 can be reduced. In the present example, the notch 54 is formed in the portion of the pump electrode 5p overlapping the reference electrode 5b. Since it is hard to heat this part by heater 3, even if it forms notch 54 in this part, it can control that a pump capacity of pump cell 6p reduces greatly.
The other configurations and effects are the same as those of the first embodiment.

(Example 3)
This example is an example in which the shapes of the monitor electrode 5m and the sensor electrode 5s are changed. As shown in FIG. 12, in this example, a monitor cutout 55 is formed in a portion of the monitor electrode 5m overlapping the reference electrode 5b in the Z direction. Similarly, in the sensor electrode 5s, a sensor cutout portion 56 is formed at a portion overlapping the reference electrode 5b in the Z direction.

The operation and effect of this example will be described. By forming the notches 55 and 56 in the sensor electrode 5s and the monitor electrode 5m, it is possible to reduce the amount of use of Au, Pt or the like which is a constituent material of the electrodes 5s and 5m. Therefore, the manufacturing cost of the gas sensor element 1 can be reduced. In the present embodiment, the notches 55 and 56 are formed in the sensor electrode 5s and the monitor electrode 5m at portions overlapping the reference electrode 5b in the Z direction. Since this portion is not easily heated by the heater 3, even if the notches 55 and 56 are formed in this portion, it is possible to suppress the performance of the monitor cell 6m and the sensor cell 6s from being greatly reduced.
The other configurations and effects are the same as those of the first embodiment.

(Example 4)
This example is an example in which the shape of the pump electrode 5p is changed. As shown in FIG. 13, in the present example, a plurality of notches 54 are formed in a slit shape in the pump electrode 5p. Each notch 54 is formed in a rectangular shape. The plurality of cutouts 54 are arranged in the X direction.

  The operation and effect of this example will be described. In this example, since the notch 54 is formed in the pump electrode 5p, the manufacturing cost of the gas sensor 1 can be reduced as in the second embodiment. Moreover, in this example, a part (intervening part 540) of pump electrode 5p remains between two adjacent notch parts 54. As shown in FIG. Therefore, this intervening portion 540 can increase the pump capacity of the entire pump cell 6p. That is, the interposition part 540 is connected to the said both ends 50 of the pump electrode 5p. The both end portions 50 overlap the partition wall 4 in the Z direction, and therefore, are portions where the temperature tends to be high. If a plurality of notches 54 are formed as in this example, the heat from the both ends 50 is locally transmitted to the intervening portion 540 without being transmitted to the entire pump electrode 5p. Therefore, the temperature of the interposition part 540 can be made high and the pump capability of the interposition part 540 can be raised. Therefore, it is possible to increase the pump capacity of the entire pump cell 6p.

Reference Signs List 1 gas sensor 11 measurement gas chamber 12 reference gas chamber 2 solid electrolyte body 3 heater 4 partition wall portion 5p pump electrode 5b reference electrode 6p pump cell

Claims (4)

A gas sensor (1) for measuring the concentration of a specific gas contained in a measurement gas,
A plate-like solid electrolyte body (2) having oxygen ion conductivity;
A heater (3) provided at a position adjacent to the solid electrolyte body (2) at a predetermined interval in the thickness direction of the solid electrolyte body (2), for heating the solid electrolyte body (2);
A partition (4) interposed between the solid electrolyte body (2) and the heater (3);
A reference gas chamber (12) surrounded by the solid electrolyte body (2), the heater (3), and the partition (4) and into which a reference gas is introduced;
A measurement gas chamber (11) formed on the opposite side of the solid electrolyte body (2) to the side where the reference gas chamber (12) is provided, into which the measurement gas is introduced;
A pump electrode (5p) and a sensor electrode (5s) formed on the surface of the solid electrolyte body (2) on the side of the measurement gas chamber (11);
A reference electrode (5b) formed on the surface of the solid electrolyte body (2) on the side of the reference gas chamber (12);
The pump electrode (5p), the solid electrolyte body (2) and the reference electrode (5b) form a pump cell (6p) for discharging oxygen contained in the gas to be measured to the reference gas chamber (12). ,
The concentration of the specific gas contained in the measured gas from which oxygen was discharged using the pump cell (6p) was measured by the sensor electrode (5s), the solid electrolyte body (2) and the reference electrode (5b) Sensor cells (6s) to form the
When viewed in the thickness direction, at least a portion of the pump electrode (5p) overlaps the partition (4), and a portion of the sensor electrode (5s) overlaps the partition (4) Is configured and
A division (14) surrounding the periphery of the measurement gas chamber (11) is disposed on the opposite side of the solid electrolyte body (2) to the side where the partition (4) is disposed, and the measurement In the width direction (Y) orthogonal to both the gas introduction direction (X) and the thickness direction, between the measured gas chamber (11) and the external space (S) in the partition (14) The length (L ₃ ) of the portion intervened in is the length (L ₄ ) of the portion intervened between the reference gas chamber (12) and the external space (S) in the partition (4) The gas sensor (1) characterized in that it is also short .   A monitor electrode (5m) formed on the surface of the solid electrolyte body (2) on the side of the measurement gas chamber (11) is further provided, the monitor electrode (5m), the solid electrolyte body (2) and the standard A monitor cell (6m) for measuring the residual oxygen concentration in the gas to be measured which has exhausted oxygen using the pump cell (6p) is formed by the electrode (5b) and viewed from the thickness direction The gas sensor (1) according to claim 1, characterized in that a part of the monitor electrode (5m) overlaps with the partition (4). The gas sensor according to claim 1 or 2 , wherein a cutout (54) is formed in a portion of the pump electrode (5p) overlapping the reference electrode (5b) in the thickness direction. 1). The gas sensor (1) according to any one of claims 1 to 3 , wherein the pump cell (6p) and the sensor cell (6s) share the same solid electrolyte body (2). .

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