Sensor element and gas sensor

Abstract

To provide a sensor element and a gas sensor in which deterioration in responsiveness of a detection cell due to heat of a heater is suppressed.SOLUTION: The sensor device (70) includes an insulating measurement chamber layer (93) having a measurement chamber (91) for measuring the specific gas concentration, a detection cell (81) formed by stacking a first layer (76) and a reference electrode (79), detection electrodes (77) facing the measurement chamber (91), detection-electrode leads (87b) connected to the detection electrodes (77) and extending in an axial direction, and a heater (73) stacked on a side of the first layer (76) opposite the measurement chamber layer (93). And a second layer 97 laminated on the opposite side of the first layer across the measurement chamber layer, wherein the detection electrode lead is arranged in contact with the second layer, and the detection electrode lead is tapered toward the heater when viewing a cross section along the width direction of the detection electrode lead.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sensor element and a gas sensor that are suitably used for detecting the concentration of a specific gas contained in combustion gas or exhaust gas from, for example, a combustor or an internal combustion engine. [Background technology]

[0002] Gas sensors have been used to detect the concentration of specific components (such as oxygen) in exhaust gas from internal combustion engines. These gas sensors contain a sensor element, which has a detection cell consisting of a solid electrolyte body, a detection electrode, and a reference electrode. The detection electrode faces a measurement chamber, which forms the internal space of the sensor element. Furthermore, a heater is stacked on the detection cell to maintain the detection cell at a temperature at which the solid electrolyte body is activated (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-108583 Summary of the Invention [Problem to be solved by the invention]

[0004] A detection electrode lead is connected to the detection electrode along the longitudinal direction of the sensor element, and a detection signal from the detection cell is taken out via the detection electrode lead. However, since the detection electrode lead is located close to the heater, the temperature of the detection electrode lead increases, which may result in an increase in resistance and a decrease in the responsiveness of the detection cell. In particular, in the case of a multi-cell sensor element having an oxygen pump cell in addition to a detection cell, if the response of the detection cell decreases, the response at high frequencies between the two cells may decrease, or the response may decrease so significantly that the correct pump current value is not indicated, and the sensor output may oscillate.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a sensor element and a gas sensor that suppress a decrease in the response of the detection cell due to the heat of the heater. [Means for solving the problem]

[0006] In order to solve the above problems, the sensor element of the present invention is a laminated sensor element that extends in an axial direction and detects the concentration of a specific gas in a measured gas, and includes: an insulating measurement chamber layer that is arranged inside the sensor element and includes a measurement chamber for measuring the concentration of the specific gas; a detection cell that is formed by laminating a detection electrode facing the measurement chamber, a first layer including a solid electrolyte body, and a reference electrode; a detection electrode lead that is connected to the detection electrode and extends in the axial direction; a heater that is laminated on the opposite side of the measurement chamber layer across the first layer; and a second layer that is laminated on the opposite side of the first layer across the measurement chamber layer, wherein the detection electrode lead is arranged in contact with the second layer, and when viewed in a cross section along the width direction of the detection electrode lead, the detection electrode lead tapers toward the heater.

[0007] According to this sensor element, the projected area of ​​the detection electrode lead at the portion closest to the heater is reduced, and accordingly the heat received from the heater is reduced, so that the detection electrode lead is less likely to reach a high temperature. As a result, it is possible to prevent the detection electrode lead from becoming too hot and its resistance from increasing, and to prevent a decrease in the response of the detection cell.

[0008] The sensor element of the present invention may further include an oxygen pump cell formed by laminating a pump electrode facing the measurement chamber, a second solid electrolyte body, and a counter electrode in this order, and a pump electrode lead connected to the pump electrode and extending in the axial direction, wherein the pump electrode lead is disposed in contact with the second layer, and when viewed in a cross section along the width direction of the pump electrode lead, the pump electrode lead may taper toward the heater.

[0009] This sensor element can also prevent the pump electrode lead from becoming too hot and reducing the responsiveness of the oxygen pump cell.

[0010] In the sensor element of the present invention, the detection electrode lead and the pump electrode lead may be a common lead. With this sensor element, the total area of ​​the leads near the heater is smaller than when the detection electrode lead and pump electrode lead are provided separately, and as a result, less heat is received from the heater, thereby further suppressing a decrease in the responsiveness of the detection cell and oxygen pump cell.

[0011] The sensor element of the present invention may further have a counter electrode lead connected to the counter electrode and extending in the axial direction, the detection electrode lead and the counter electrode lead being arranged on either side of the widthwise center of the sensor element, and when viewed in a cross section along the widthwise direction of the counter electrode lead, the counter electrode lead may taper toward the heater. With this sensor element, when the detection electrode lead and counter electrode lead shrink in the width direction during firing, stress is applied evenly across the widthwise center, so the left and right moments are well balanced and shrinkage is easy to achieve.

[0012] In the sensor element of the present invention, the detection electrode and the detection electrode lead may be connected to each other through a lead connection portion that extends in the stacking direction and penetrates the measurement chamber layer. With this sensor element, the detection electrode lead can be placed farther away from the heater than when the detection electrode lead is extended on the same layer as the detection electrode, which further prevents the detection electrode lead from becoming too hot and further prevents a decrease in the response of the detection cell.

[0013] The gas sensor of the present invention is a gas sensor comprising a sensor element for detecting a specific gas concentration in a gas to be measured and a metallic shell for holding the sensor element, wherein the sensor element is a sensor element as defined in claim 1 or 2. [Effects of the Invention]

[0014] According to the present invention, it is possible to obtain a sensor element and a gas sensor in which a decrease in the response of the detection cell due to the heat of the heater is suppressed. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view taken along the axial direction of a gas sensor (oxygen sensor) according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. 3. [Figure 5] 5 is a cross-sectional view showing a mode of laminating a second-layer green sheet and a measurement chamber layer precursor before firing, as seen from the cross section corresponding to FIG. 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view along the axial direction (axis O direction) of a gas sensor (oxygen sensor) 1 according to an embodiment of the present invention, FIG. 2 is a perspective view of a sensor element 70 (detection element portion 71 and heater 73), and FIG. 3 is an exploded perspective view of the sensor element 70.

[0017] 1, the gas sensor (air-fuel ratio sensor) 1 includes a sensor element (oxygen sensor element) 70 including a detection element portion 71 and a heater 73 laminated on the detection element portion 71, a metal shell 30 that holds the sensor element 70 and other components therein, and a protector 24 that is attached to the tip of the metal shell 30. The sensor element 70 is disposed so as to extend in the direction of the axis O.

[0018] As shown in FIG. 2, electrode pads 125, 127, and 129 are formed on one main surface (insulating substrate) 97 on the rear end side of the sensor element 70, and electrode pads 131 and 133 (see FIG. 3) are formed on the other main surface (not shown). These electrode pads 125, 127, 129, 131, and 133 are electrically connected to the connection terminals 16, which will be described later. The tip side of the sensor element 70 is covered with a porous protective layer 17 .

[0019] As shown in FIG. 3, the sensor element 70 is a laminated type sensor element formed by laminating a detection element portion 71, a heater 73, and other layers. Heater 73 includes insulating substrates 101, 103 made primarily of alumina and a heating element 105 made primarily of platinum and laminated between the insulating substrates 101, 103. Heating element 105 has a pair of heater leads extending from a heating portion located at the tip side along the axial direction of insulating substrate 103. Terminals of the heater leads are electrically connected to electrode pads 131, 133 on the heater side via conductors formed in through holes 181, 182 provided in insulating substrate 103.

[0020] The detection element section 71 includes an oxygen concentration detection cell (detection cell) 81 and an oxygen pump cell 89. The oxygen concentration detection cell 81 includes an insulating member 76, a solid electrolyte body 75, a porous detection electrode 77, a common lead 87b, a porous reference electrode 79, and a reference electrode lead 79a. The insulating member 76 is a plate-shaped member made primarily of alumina, and has a rectangular through-hole 76a that penetrates the tip end in the thickness direction. The solid electrolyte body 75 is disposed so as to be embedded in the through-hole 76a of the insulating member 76. A pair of electrodes 77, 79 are disposed on the front and back surfaces of the solid electrolyte body 75, respectively, so as to sandwich the solid electrolyte body 75 therebetween.

[0021] The common lead 87b corresponds to the "detection electrode lead" in the claims. In this example, the short lead 77a is connected to a common lead 87b arranged in another layer via a lead connection portion 82, as will be described in more detail later. When the short lead 77a and the common lead 87b connected to the detection electrode 77 are viewed in the direction of the axis O, the common lead 87b is longer and can therefore be regarded as the main lead connected to the detection electrode 77, and therefore the common lead 87b will be regarded as the "detection electrode lead." On the other hand, if there is a single lead connected to the detection electrode 77, that lead becomes the "detection electrode lead."

[0022] In this example, a common lead 87b is used as the lead for both the detection electrode 77 and the pump electrode 87, and as will be described later, the electrodes 77 and 87 are electrically connected at the same potential.

[0023] The insulating member 76 has the same external dimensions as the sensor element 70, and is laminated on the sensor element 70 to form the "first layer" in the claims. In addition, when the solid electrolyte body 75 does not have the insulating member 76 and has the same external dimensions as the sensor element 70 (i.e., the solid electrolyte body 75 constitutes a layer of the sensor element 70), the solid electrolyte body 75 corresponds to the "first layer."

[0024] The short lead 77a has its tip connected to the detection electrode 77 and extends in the direction of the axis O of the detection element portion 71 (left and right direction in FIG. 3), but terminates near the rear end side of the solid electrolyte body 75. On the other hand, the reference electrode lead 79a has a tip connected to the reference electrode 79 and extends to the rear end side of the detection element portion 71 in the axis O direction. The end of the reference electrode lead 79a is electrically connected to the electrode pad 127 via a through-hole 176 provided in the insulating member 76 and conductors formed in through-holes 172, 166, and 162, which will be described later. The method of connecting the short leads 77a will be described later.

[0025] On the other hand, the oxygen pump cell 89 includes a second solid electrolyte body 83, a porous pump electrode 87, pump electrode leads 87a and 87b, a porous counter electrode 85, and a counter electrode lead 85a. A pair of electrodes 85, 87 are arranged on the front and back surfaces of the second solid electrolyte body 83, respectively, so as to sandwich the second solid electrolyte body 83 therebetween.

[0026] The counter electrode lead 85a has a tip connected to the counter electrode 85 and extends to the rear end side of the detection element section 71 in the axis O direction. The pump electrode front lead 87a has a tip connected to the pump electrode 87, extends slightly rearward beyond the solid electrolyte body 75, and is integrally connected to the common lead 87b. The common lead 87b has a tip connected integrally to the counter electrode lead 85a, and extends rearward in the direction of the axis O of the detection element portion 71. Since the pump electrode front lead 87a and the common lead 87b are integrally connected to the pump electrode 87, the pump electrode front lead 87a and the common lead 87b are considered to be the "pump electrode leads."

[0027] The solid electrolyte bodies 75 and 83 are made of zirconia with yttria as a stabilizer. The cross-sectional area of ​​the solid electrolyte body 75 in a plane perpendicular to the stacking direction is larger than that of the second solid electrolyte body 83. The electrodes 77, 79, 85, and 87 and the leads 77a, 79a, 85a, 87a, and 87b are formed mainly from Pt.

[0028] An insulating spacer 93 is formed between the oxygen pump cell 89 and the oxygen concentration detection cell 81. The insulating spacer 93 is a plate-shaped member made mainly of alumina, and like the insulating member 76, the tip end side is penetrated in a rectangular shape in the thickness direction, forming a hollow measurement chamber 91. The electrodes 77 and 87 are arranged inside the measurement chamber 91 so as to be exposed (facing out). The insulating spacer 93 including the measuring chamber 91 corresponds to the "measuring chamber layer" in the claims.

[0029] Two gas inlets 94 are formed on the side surfaces of the element part 71 (side surfaces of the insulating spacer 93) to serve as intake ports for exhaust gas (gas to be measured). The gas inlets 94 communicate with the measurement chamber 91. A diffusion rate-controlling section 95 is formed in each path from the two gas introduction sections 94 to the measurement chamber 91. The diffusion rate-controlling section 95 is made of a porous body made of alumina or the like, and realizes gas diffusion when the measurement gas flows into the measurement chamber 91 under predetermined rate-controlling conditions. The diffusion rate-controlling portion 95 is provided in a state where a part of it is exposed from the gas inlet portion 94. That is, in this sensor element 70, the gas inlet portion 94 is formed on the outermost surface of the sensor element 70 (element body) facing in two different directions, and the diffusion rate-controlling portion 95 is exposed in the two different directions.

[0030] An insulating substrate 97 is disposed on the upper surface of the oxygen pump cell 89 (the surface opposite to the insulating spacer 93). The insulating substrate 97 is a plate-shaped member made mainly of alumina, and like the insulating member 76, has a space 97a that penetrates the tip end in a rectangular shape in the thickness direction. A vent portion 99 made of a porous material similar to the diffusion rate-controlling portion 95 is embedded in the space 97a. This vent portion 99 exposes the electrode 85 of the oxygen pump cell 89 to the gas to be measured.

[0031] The insulating substrate 97 has the same outer dimensions as the sensor element 70, and is laminated on the sensor element 70 to form the main surface 97 of the sensor element 70 (FIG. 2). Moreover, both the leads 85a and the leads 87b are printed on the lower surface of the insulating substrate 97 (the surface on the insulating spacer 93 side). The insulating substrate 97 constitutes the "second layer" in the claims.

[0032] The measurement chamber 91 is formed so as to be located at the tip side (left side in FIG. 3) of the sensor element 70 (more specifically, the detection element portion 71). In the direction of the axis O of the element portion 71, the region where the measurement chamber 91 is formed and the region further to the tip side than the measurement chamber 91 are provided as a detection portion for detecting oxygen.

[0033] Next, as shown in FIG. 3, the electrode pad 129 (the right electrode pad in FIG. 2) is electrically connected to the detection electrode 77 via a through-hole 161 provided in the insulating substrate 97, a common lead 87b (and a counter electrode lead 85a), a lead connection portion 82 described later, and a short lead 77a. The electrode pad 129 is also electrically connected to the pump electrode 87 via the through-hole 161 and the common lead 87b (and the counter electrode lead 85a). Therefore, the electrodes 77 and 87 are electrically connected at the same potential.

[0034] The lead connection portion 82 is mainly made of platinum and is embedded in a through hole 86 of the insulating spacer 93. The lead connection portion 82 electrically connects the short lead 77a of the electrode 77 and the counter electrode lead 85a of the electrode 87. In Figure 3, only the lead connection portion 82 provided in the through hole 86 is shown, but other through holes (e.g., through holes 161, 165, etc.) also have conductors formed on their inner wall surfaces, similar to through hole 86.

[0035] As shown in FIG. 3, the electrode pad 127 (the central electrode pad in FIG. 2) is electrically connected to the reference electrode 79 via a through-hole 162 provided in the insulating substrate 97, a through-hole 172 provided in the insulating spacer 93, a through-hole 176 provided in the insulating member 76, and a reference electrode lead 79a. Still another electrode pad 125 (the electrode pad on the left side in FIG. 2) is electrically connected to the counter electrode 85 via a through-hole 163 provided in the insulating substrate 97 and a lead 85a, as shown in FIG.

[0036] As described above, the sensor element 70 has at least a detection cell (oxygen concentration detection cell, etc.) 81 that detects the concentration of a specific gas, and may further have other cells such as a pump cell (oxygen pump cell 89, etc.). These cells have a solid electrolyte body and a pair of electrodes. At least the detection electrode of the detection cell faces the measurement chamber 91 .

[0037] In the sensor element 70 of this embodiment, the direction and magnitude of the current flowing between the electrodes of the oxygen pump cell 89 are adjusted so that the voltage (electromotive force) generated between the electrodes of the oxygen concentration detection cell 81 becomes a predetermined value (e.g., 450 mV), thereby pumping oxygen in the measurement chamber 91. The sensor element 70 constitutes an oxygen sensor element that linearly detects the oxygen concentration in the measurement gas in accordance with the current flowing through the oxygen pump cell 89.

[0038] Returning to FIG. 1 , the metal shell 30 is made of SUS430 and has a male thread portion 31 for attaching the gas sensor to the exhaust pipe and a hexagonal portion 32 to which an installation tool is applied during installation. The metal shell 30 also has a metal-side step 33 that protrudes radially inward, and this metal-side step 33 supports a metal holder 34 for holding a sensor element 70. Inside the metal holder 34, a ceramic holder 35 and talc 36 are arranged, in this order from the front end. The talc 36 consists of a first talc 37 arranged within the metal holder 34 and a second talc 38 arranged across the rear end of the metal holder 34. The first talc 37 is compressed and filled within the metal holder 34, thereby fixing the sensor element 70 to the metal holder 34. The second talc 38 is compressed and filled within the metal shell 30, thereby ensuring a seal between the outer surface of the sensor element 70 and the inner surface of the metal shell 30. An alumina sleeve 39 is disposed on the rear end side of the second talc 38. This sleeve 39 is formed in a multi-stage cylindrical shape, has an axial hole 39a formed along the axis, and has a sensor element 70 inserted therein. The crimped portion 30a on the rear end side of the metal shell 30 is bent inward, and the sleeve 39 is pressed against the front end side of the metal shell 30 via a stainless steel ring member 40.

[0039] A metal protector 24 having a plurality of gas intake holes 24a is attached by welding to the outer periphery on the tip side of the metallic shell 30. The metal protector 24 covers the tip portion of the sensor element 70 protruding from the tip of the metallic shell 30. The protector 24 has a double structure, with an outer protector 41 in the form of a closed-end cylinder having a uniform outer diameter on the outside and an inner protector 42 in the form of a closed-end cylinder with a rear end 42a whose outer diameter is larger than the outer diameter of a tip end 42b on the inside.

[0040] Meanwhile, the front end side of an outer tube 25 made of SUS430 is inserted into the rear end side of the metallic shell 30. The outer tube 25 has an expanded diameter front end portion 25a fixed to the metallic shell 30 by laser welding or the like. A separator 50 is disposed inside the rear end side of the outer tube 25, and a holding member 51 is interposed in the gap between the separator 50 and the outer tube 25. This holding member 51 engages with a protruding portion 50a of the separator 50 (described later) and fixes the outer tube 25 and the separator 50 together by crimping the outer tube 25.

[0041] The separator 50 also has an insertion hole 50b extending from the front end to the rear end thereof for inserting the lead wires 11-15 for the detection element 71 and the heater 73 (the lead wires 14 and 15 are not shown). The insertion hole 50b accommodates connection terminals 16 for connecting the lead wires 11-15 to the electrode pads 125, 127, and 129 of the detection element 71 and the electrode pads 131 and 133 of the heater 73. The lead wires 11-15 are externally connected to connectors (not shown). Electrical signals are input and output between the lead wires 11-15 and external devices such as an ECU via these connectors. Although not shown in detail, the lead wires 11-15 have a structure in which the conductors are covered with an insulating film made of resin.

[0042] Furthermore, a substantially cylindrical rubber cap 52 is disposed on the rear end side of the separator 50 to close an opening 25b on the rear end side of the outer tube 25. This rubber cap 52 is fixed to the outer tube 25 by crimping the outer periphery of the outer tube 25 radially inward while attached to the rear end of the outer tube 25. Through holes 52a are also formed in the rubber cap 52 from the front end side to the rear end side, through which the lead wires 11 to 15 are inserted, respectively.

[0043] Next, the characteristic features of the present invention will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view taken along line AA in Fig. 3, and corresponds to a cross-sectional view perpendicular to the axis O direction of the sensor element 70. As shown in FIG. 4, the common lead (detection electrode lead) 87b is disposed in contact with the second layer 97, and when viewed in a cross section along the width direction of the common lead 87b, the common lead 87b tapers toward the heater 73.

[0044] In this way, the projected area of ​​the portion of the common lead 87b that is close to the heater 73 is reduced, and the heat received from the heater 73 is reduced accordingly, so that the common lead 87b is less likely to reach a high temperature. As a result, the common lead 87b is prevented from becoming too hot and its resistance value is prevented from increasing, and the response of the detection cell 81 is prevented from decreasing.

[0045] In this example, the lead 85a also tapers toward the heater 73 when viewed in cross section along the width direction of the lead 85a. In this way, the leads 85a and 87b tend to shrink neatly during firing, as will be described later.

[0046] In this example, since the insulating spacer 93 and the insulating member 76 have the same composition (mainly alumina), when these layers are stacked and then fired to manufacture the sensor element 70, it becomes impossible to distinguish between the insulating spacer 93 and the insulating member 76. In such a case, the region of the measuring chamber 91 having a thickness t3 in the stacking direction is regarded as an insulating spacer 93.

[0047] FIG. 5 shows a state in which an insulating substrate green sheet 97x and an insulating spacer precursor 93x are laminated before firing. First, the leads 87b (and the leads 85a) are printed on the lower surface (surface on the insulating spacer precursor 93x3 side) of the insulating substrate green sheet 97x. At this time, the printed part will have a tapered shape due to the surface tension of the printing ink, or when using screen printing, the ink at the corners of the mask will be absorbed by the screen (mesh). In this manner, the common lead 87 b can be tapered toward the heater 73 . Next, an insulating substrate green sheet 97x and an insulating spacer precursor 93x are laminated.

[0048] In this example, of the electrodes 85 and 87 that make up the oxygen pump cell 89, the pump electrode lead of the pump electrode 87 that is closest to the heater 73 is also shared as a common lead 87b. The pump electrode lead (common lead 87b) also tapers toward the heater 73. This also prevents the common lead 87b from becoming too hot and causing a decrease in the responsiveness of the oxygen pump cell 89.

[0049] In this example, the detection electrode lead and the pump electrode lead are both shared by the common lead 87b. This reduces the total area of ​​the leads near the heater 73 compared to when the detection electrode lead and the pump electrode lead are provided separately, and therefore reduces the amount of heat received from the heater 73, further suppressing the decrease in responsiveness of the detection cell 81 and the oxygen pump cell 89.

[0050] In this example, the common lead (detection electrode lead) 87b and the counter electrode lead 85a are arranged on either side of the widthwise center Ce of the sensor element 70, and the common lead 87b and the counter electrode lead 85a also have a tapered shape toward the heater 73. In this way, when the common lead 87b and the counter electrode lead 85a shrink in the width direction during firing, stress is applied evenly across the width center Ce, so the left and right moments are well balanced and shrinkage is easy to achieve. Furthermore, among the common lead 87b, the counter electrode lead 85a, and the reference electrode lead 79a, the common lead 87b has the widest width, which makes it possible to suppress oscillation during sensor detection.

[0051] The widths W1, W2, and W3 of the common lead 87b, counter electrode lead 85a, and reference electrode lead 79a are the widths of the widest portions of the respective leads. For example, since the common lead 87b tapers toward the heater 73, the base portion in contact with the second layer 97 is the widest, and the width of this portion is designated as W1.

[0052] In this example, the detection electrode 77 and the common lead 87b are connected across the measurement chamber layer (insulating spacer) 93 via a lead connection portion 82 extending in the stacking direction. In this way, the detection electrode lead (common lead) 87b can be placed farther away from the heater 73 than when the detection electrode lead is extended on the same layer as the detection electrode 77. As a result, the common lead 87b is further prevented from becoming too hot, and a decrease in the responsiveness of the detection cell 81 can be further suppressed.

[0053] The present invention is not limited to the above-described embodiments. As long as the common lead 87b tapers toward the heater 73, its cross-sectional shape is not limited. The detection electrode lead and the pump electrode lead may be provided separately.

[0054] The present invention is applicable to all gas sensors (sensor elements), including the oxygen sensor (oxygen sensor element) of the present embodiment, but is not limited to these applications and covers various modifications and equivalents within the spirit and scope of the present invention. For example, the present invention may be applied to a NOx sensor (NOx sensor element) that detects the NOx concentration in a gas to be measured. The sensor element may have one detection cell. [Explanation of symbols]

[0055] 1 Gas sensor 30 Metal body 70 Sensor element 73 Heater 75 Solid electrolyte body 76 1st layer (insulating material) 77 Detection electrode 79 Reference electrode 79a Reference electrode lead 81 Detection cell (oxygen concentration detection cell) 82 Lead connection 83 Second solid electrolyte body 85 Counter electrode 85a Counter electrode lead 87 Pump Electrode 87a Pump electrode lead 87b Detection electrode lead, pump electrode lead (common lead) 89 Oxygen pump cell 91 Measurement room 93 Measuring chamber layer (insulating spacer) 97 2nd layer (insulating substrate) O axis Ce: Center of the sensor element in the width direction

Claims

1. A laminated sensor element extending in an axial direction for detecting the concentration of a specific gas in a measurement gas, an insulating measurement chamber layer disposed inside the sensor element and including a measurement chamber for measuring the concentration of the specific gas; a detection cell including a detection electrode facing the measurement chamber, a first layer including a solid electrolyte body, and a reference electrode stacked together; a detection electrode lead connected to the detection electrode and extending in the axial direction; a heater laminated on the opposite side of the measurement chamber layer with the first layer interposed therebetween; a second layer laminated on the opposite side of the first layer with the measurement chamber layer interposed therebetween; and the detection electrode lead is disposed in contact with the second layer; A sensor element characterized in that, when viewed in a cross section along the width direction of the detection electrode lead, the detection electrode lead tapers toward the heater.

2. an oxygen pump cell including a pump electrode facing the measurement chamber, a second solid electrolyte body, and a counter electrode stacked in this order; a pump electrode lead connected to the pump electrode and extending in the axial direction; and the pump electrode lead is disposed in contact with the second layer; 2. The sensor element according to claim 1, wherein the pump electrode lead tapers toward the heater when viewed in a cross section along the width direction of the pump electrode lead.

3. 3. The sensor element according to claim 2, wherein the detection electrode lead and the pump electrode lead are common.

4. a counter electrode lead connected to the counter electrode and extending in the axial direction; the detection electrode lead and the counter electrode lead are arranged on either side of the center of the sensor element in the width direction, 4. The sensor element according to claim 2, wherein the counter electrode lead tapers toward the heater when viewed in a cross section along the width direction of the counter electrode lead.

5. 3. The sensor element according to claim 1, wherein the detection electrode and the detection electrode lead are connected to each other through a lead connection portion extending in the stacking direction and penetrating the measurement chamber layer.

6. A gas sensor comprising a sensor element for detecting the concentration of a specific gas in a gas to be measured and a metallic shell for holding the sensor element, 3. A gas sensor comprising the sensor element according to claim 1 or 2.

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