JP4705005B2 - Gas sensor element and gas sensor - Google Patents

Description

  The present invention relates to a gas sensor element and a gas sensor for detecting the concentration of a specific gas component in a measurement target gas.

  Conventionally, a gas sensor that detects the concentration of a specific gas component in a gas to be measured such as exhaust gas discharged from an automobile is known. Such a gas sensor uses a gas sensor element whose electrical characteristics change according to the concentration of a specific gas component in the gas to be measured. This gas sensor element includes, for example, a solid electrolyte body mainly composed of zirconia, and is laminated with one or a plurality of solid electrolyte bodies, an electrode, an insulating layer, a heater, and the like, and has a plate-like outer diameter as a whole. Such a configuration is known. The heater has, for example, a structure in which a ceramic layer (insulating layer) mainly composed of alumina and a heating resistor are laminated.

  In the gas sensor element as described above, one end (front end) in the plate-like longitudinal direction is a detection unit that is exposed to the gas to be measured, and the other end (rear end) is fixed to the metal shell. It is considered to be a part. For this reason, a reference electrode part, a detection electrode part, etc. are provided on both surfaces on the front end side of the solid electrolyte body formed in a plate shape, and lead parts (reference lead part and detection lead part) for drawing out these electrode parts However, it is known to have a structure formed along the longitudinal direction of the solid electrolyte body (see, for example, Patent Document 1).

Further, in such a gas sensor element, by setting the area of the detection electrode portion to 1.25 times or more of the area of the reference electrode portion, the light off time (the time from the start of power supply until the sensor is activated) ) Can be shortened (see, for example, Patent Document 2).
JP 2003-294687 A JP 2002-202280 A

  However, in the gas sensor element as described above, a pair of electrode portions (reference electrode portion and detection electrode portion) formed on the front and back surfaces of the solid electrolyte body are formed in a slightly shifted position due to tolerances in the manufacturing process. May be. And when the reference electrode part and the detection electrode part are formed in a state of being displaced in this way, the effective area of the electrode part that contributes to the detection of the specific gas (the area of the part where the electrode part faces) is different for each gas sensor. Because of the change, there is a problem that the performance as a gas sensor varies.

  The present invention has been made to solve the above problems. An object of the present invention is to provide a gas sensor element and a gas sensor that can maintain an effective area of an electrode for each gas sensor constant and can achieve uniform performance.

  The gas sensor element of the present invention is formed in a plate shape, a solid electrolyte body whose electrical characteristics change according to the concentration of a specific gas in the gas to be measured, and formed on one side and the other side of the solid electrolyte body A pair of rectangular electrode main body portions opposed to each other through the solid electrolyte body and constituting a detection unit together with the solid electrolyte body, and on one surface of the solid electrolyte body, and the solid electrolyte body and the one side A first insulating layer that is provided between the electrode body portion and covers the outer edges of two opposing sides of the four sides of the one electrode body portion, and the other surface of the solid electrolyte body, And the 2nd insulating layer which is provided between the said solid electrolyte body and the said other electrode main-body part, and covers two sides on the side different from the two sides which the said 1st insulating layer of the other said electrode main-body part covers, The electrode body portion pair is formed by stacking the first insulating layer and the second insulating layer. The first insulating layer and the second insulating layer are provided so that an opening smaller than the electrode main body is formed at a corresponding position of the electrode main body when projected in a direction. To do.

  The gas sensor element of the present invention is provided on one surface of a solid electrolyte body and between the solid electrolyte body and the one electrode main body, and one set of four sides of the one electrode main body. A first insulating layer covering outer edges of two opposing sides, and provided on the other surface of the solid electrolyte body and between the solid electrolyte body and the other electrode main body, and the other electrode main body And a second insulating layer covering two sides on the side different from the first insulating layer, and the first insulating layer and the second insulating layer are overlapped and projected in a direction opposite to the electrode main body. Furthermore, the first insulating layer and the second insulating layer are provided so that an opening smaller than the electrode main body portion is formed at a corresponding position of the electrode main body portion. Thereby, in the first insulating layer and the second insulating layer, the effective area of the electrode can be limited to the area of the opening. For example, it is located on one electrode main body and the other electrode main body on the opposite surface side Even if a deviation occurs, the effective area of these electrode main body portions can be the area of the opening. That is, even if a positional shift occurs between the pair of electrode main bodies for each gas sensor, the effective area between these electrodes can be made constant. Thus, by providing the first insulating layer and the second insulating layer, the effective area of the electrode can be made constant, and the variation in performance of each gas sensor can be reduced.

  The size of the opening may be a predetermined size smaller than that of the electrode main body. However, the size of the opening is small enough to allow for a tolerance in the manufacturing process, and at least a size capable of detecting a specific gas. Needless to say, you need.

  The electrode main body portion is connected to an electrode lead portion that extends in the longitudinal direction of the solid electrolyte body and extracts a signal from the electrode main body portion. The first insulating layer and the second insulating layer are connected to the electrode lead portion and the electrode main body portion. It is preferable to extend between the solid electrolyte body. If a position shift occurs in the electrode body on the opposite side of one electrode body, an overlap with the electrode lead connected to the electrode body will occur, the effective area will change, and the performance as a gas sensor will vary. May end up. In addition, electrical leakage may occur between the electrode lead portions, and the performance of the gas sensor may vary. Therefore, by providing an insulating layer between the electrode lead part and the solid electrolyte body, it is possible to suppress changes in the effective area due to the electrode lead part, and furthermore, it is possible to prevent electrical leakage between the electrode lead parts, and as a gas sensor Variation in performance can be suppressed. Moreover, it can produce simultaneously with the insulating layer formed in an electrode main-body part by extending from an electrode main-body part.

  In addition, one of the pair of electrode main body portions is a detection electrode portion that is exposed to the gas to be measured introduced into the measurement chamber via a diffusion rate controlling portion, the other is a reference electrode portion, and the second insulating layer is It is preferable that the detection electrode unit is provided so as to cover the outer edges of a pair of opposing sides along the direction in which the gas to be measured is introduced into the measurement chamber. When the detection electrode portion is arranged in a region that is not covered with the second insulating layer as described above so as to straddle the direction perpendicular to the direction in which the gas to be measured is introduced into the measurement chamber (hereinafter referred to as the gas introduction direction). For example, even if the detection electrode portion varies in a direction perpendicular to the gas introduction direction, when the gas to be measured is introduced into the measurement chamber, the detection electrode is always in contact with the detection electrode except for the second insulating layer. Accuracy is improved. On the other hand, when the detection electrode section covers a pair of opposing outer edges along the direction perpendicular to the gas introduction direction, when the detection electrode varies in the direction perpendicular to the gas introduction direction, the gas to be measured is moved into the measurement chamber. In the case where it is introduced into the sensor electrode, there is a possibility that it is not in contact with the detection electrode even if it is other than the second insulating layer.

  Note that “covering the outer edges of a pair of opposing two sides along the direction in which the gas to be measured in the detection electrode portion is introduced into the measurement chamber” means that, for example, a diffusion rate controlling portion is disposed at the tip of the gas sensor element. In this case, it is in the longitudinal direction of the gas sensor element, and in the case where the diffusion control part is disposed on the side surface of the gas sensor element, the gas sensor element is in the vertical direction.

  In addition, the reference electrode portion is composed of a porous body, the reference electrode portion is covered with the solid electrolyte body and the shield, oxygen is pumped into the reference electrode portion side, and the pumping is performed. The present invention can be applied to a gas sensor element that is a self-generated reference electrode in which a predetermined level of reference oxygen concentration is formed inside itself by the dissolved oxygen. In this case, variation in the light-off time can be reduced by providing the first and second insulating layers to make the effective area of the electrode constant.

  Further, by constructing the gas sensor by incorporating the gas sensor element having the above configuration into the metal shell, the effective area of the electrode can be made constant, and a gas sensor with little variation in performance can be obtained.

  According to the gas sensor element and the gas sensor of the present invention, the effective area of the electrode for each gas sensor can be kept constant, and the performance can be made uniform.

  Hereinafter, a stacked gas sensor element 100 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing the structure of a gas sensor element 100 having a plate shape as a whole. The gas sensor element 100 is configured by laminating a gas sensor element body 1 and a heater 2.

The gas sensor element body 1 includes, for example, an oxygen composed of a zirconia (ZrO ₂ ) -based sintered body or a LaGaO ₃ -based sintered body to which yttria (Y ₂ O ₃ ) or calcia (CaO) is added as a stabilizer. A solid electrolyte body 11 for a concentration battery is provided. In the present embodiment, the solid electrolyte body 11 is configured in which 10-80% by mass of alumina is contained in zirconia to which yttria is added as a stabilizer.

  A reference electrode 13 made of a porous body is formed on the side of the solid electrolyte body 11 facing the heater 2. Similarly, a detection electrode 14 made of a porous body is formed on the surface of the solid electrolyte body 11 located on the side opposite to the reference electrode 13. The reference electrode 13 and the detection electrode 14 are provided so that the reference electrode part 132 and the detection electrode part 142 that constitute the detection part 101 (see FIG. 4) together with the solid electrolyte body 11 are opposed to each other. A reference electrode lead portion 131 and a detection electrode lead portion 141 extend from the electrode portion 142 along the longitudinal direction of the solid electrolyte body 11. The reference electrode part 132, the detection electrode part 142, the reference electrode lead part 131, and the detection electrode lead part 141 are made of, for example, Pt.

  An insulating layer 150 is provided between the solid electrolyte body 11 and the reference electrode 13. As shown in FIG. 2 (B), the insulating layer 150 includes two pairs of opposing sides of the four sides of the rectangular reference electrode portion 132, that is, the front end side (left side in the figure) outer edge and rear end side ( The right side in the figure covers from the outer edge, and the entire outer shape is substantially the same size as the solid electrolyte body 11. Then, at a position corresponding to the reference electrode portion 132, an opening in which the dimension in the front-rear direction (the left-right direction in the figure) is smaller than that of the reference electrode portion 132 and the side dimension perpendicular thereto is larger than that of the reference electrode portion 132. 151 is provided.

  An insulating layer 155 is provided between the solid electrolyte body 11 that is the other surface of the solid electrolyte body 11 and the detection electrode 14. As shown in FIG. 2A, the insulating layer 155 is provided in a line shape on both sides of the side end portion along the longitudinal direction of the solid electrolyte body 11, and the insulating layer 150 of the detection electrode portion 142 described above. 2 sides, that is, the outer edges of the sides (upper and lower sides in the figure) are covered. An opening in which the dimension in the lateral direction (vertical direction in the drawing) is smaller than that of the detection electrode part 142 and the dimension on the side perpendicular to the detection electrode part 142 is larger than that of the detection electrode part 142 at a position corresponding to the detection electrode part 142. A portion 156 is provided.

  Then, as shown in FIG. 2C, the insulating electrode 150 formed on one surface of the solid electrolyte body 11 and the insulating layer 155 formed on the other surface are overlapped to detect the electrode portion 142 and the reference electrode. An opening 159 smaller than the detection electrode part 142 and the reference electrode part 132 is formed at a corresponding position of the detection electrode part 142 and the reference electrode part 132 when projected in the direction opposite to the part 132. .

  As described above, by providing the insulating layers 150 and 155, the effective areas of the detection electrode unit 142 and the reference electrode unit 132 are limited to the area of the opening 159. Thereby, for example, even if a positional deviation occurs between the reference electrode part 132 and the detection electrode part 142 on the opposite surface side, the effective area between these electrodes can be made constant. The relationship between the size of the detection electrode portion 142 and the reference electrode portion 132 and the opening portion 159 is such that the opening portion 159 is the detection electrode even when the positional deviation between the reference electrode portion 132 and the detection electrode portion 142 is maximized. The size may be such that it does not deviate from the portion 142 and the reference electrode portion 132. In the normal case, the amount of positional deviation when printing is about 0.2 mm to 0.3 mm. Therefore, the size of the opening 159 with respect to the outer shape of the detection electrode portion 142 and the reference electrode portion 132. For example, if the height and width are reduced by several millimeters, it is sufficient to satisfy the above condition.

  Thus, by providing the insulating layers 150 and 155, the effective area of the electrode main body can be made constant, and variation in performance can be reduced. That is, by making the effective area of the electrode main body portion constant, the output becomes constant, and the resistance between the electrode main body portions becomes constant, so that the temperature control accuracy when the temperature is controlled based on the resistance can be improved. .

  In addition, the insulating layers 150 and 155 can reduce variations in the light-off time by making the area of the effective portion of the reference electrode portion 132 constant. That is, in the case of the self-generated type, a pumping current is applied between the reference electrode part 132 and the detection electrode part 142 in the direction in which oxygen is pumped to the reference electrode part 132 side, and the reference electrode is generated by the pumped oxygen. A reference oxygen concentration of a predetermined level is formed inside the portion 132. By providing the insulating layers 150 and 155, the time until the reference oxygen concentration is formed can be made constant, and variations in the light-off time can be reduced.

  In the present embodiment, the insulating layers 150 and 155 are provided so as to be interposed between the solid electrolyte body 11, the reference electrode lead portion 131 and the detection electrode lead portion 141, and the reference electrode lead portion 131 and the detection electrode are provided. The occurrence of electrical leakage in the lead portion 141 is prevented. That is, the insulating layers 150 and 155 are integrally formed so as to cover the peripheral portions of the reference electrode portion 132 and the detection electrode portion 142 and the reference electrode lead portion 131 and the detection electrode lead portion 141.

  As shown in FIG. 1, the end of the detection electrode lead 141 is connected to a signal extraction terminal 126 for connection to an external terminal through a through hole 124 that penetrates the protective layer 12 described later. In addition, the end of the reference electrode lead 131 is connected to an external terminal through the solid electrolyte body 11 and the insulating layer 150, through holes 110, 152, and 157 that pass through the insulating layer 155 and a through hole 123 that passes through the protective layer 12. It is connected to a signal extraction terminal 126 for connection.

  The protective layer 12 is formed on the surface of the detection electrode part 142 and is formed on the surface of the detection electrode lead part 141 and the porous electrode protective layer 122 for protecting the detection electrode part 142 itself from poisoning. And a reinforced protective layer 121 for protecting the solid electrolyte body 11.

  On the other hand, the heater 2 includes a resistance heating element 21, and the resistance heating element 21 is sandwiched between a first base layer 22 and a second base layer 23 made of a ceramic sintered body having excellent insulating properties. The resistance heating element 21 has a heat generating portion 212 formed in a meandering shape and a pair of heater lead portions 213 connected to the end portions of the heat generating portion 212 and extending along the longitudinal direction. The end of the heater lead 213 opposite to the side connected to the heat generating part 212 is connected to an external terminal for connecting an external circuit via two through holes 231 penetrating the second base layer 23. The pair of heater energization terminals 232 are electrically connected to each other.

  If the said 1st base layer 22 and the 2nd base layer 23 are ceramic sintered compacts, it will not specifically limit, For example, an alumina, a spinel, a mullite, a zirconia etc. can be used as this ceramic. Only one of these can be used, or two or more can be used in combination.

  As the resistance heating element 21, a noble metal, tungsten, molybdenum or the like can be used. Examples of the noble metal include Pt, Au, Ag, Pd, Ir, Ru, Rh and the like, and only one of these may be used, or two or more may be used in combination. The resistance heating element 21 is preferably composed mainly of a noble metal in consideration of heat resistance, oxidation resistance and the like, and more preferably composed mainly of Pt. The resistor heating element 21 may contain a ceramic component in the main noble metal. This ceramic component preferably contains the same component as the main component of the ceramic first base layer 22 and second base layer 23 in which the resistance heating element 21 is embedded from the viewpoint of fixing strength.

  Further, in the resistance heating element 21, the heat generating portion 212 is a portion that generates heat by energization, and the heater lead portion 213 is a portion that supplies a DC voltage supplied from the outside to the heat generating portion 212 and hardly generates heat. The shapes of the heat generating part 212 and the heater lead part 213 are not particularly limited. For example, the heat generating part 212 is narrower than the heater lead part 213 and is meandered so as to form a denser pattern than the heater lead part 213. Can be adopted.

  And in the gas sensor element 100 comprised by laminating | stacking the gas sensor element main body 1 and the heater 2 in this way, in the part at the front end side exposed to measuring gas, a porous protective layer over the circumference | surroundings (Not shown) is formed.

  FIG. 4 is a gas sensor in which the gas sensor element 100 described above is incorporated. Specifically, an overall cross section showing an example of a gas sensor 600 attached to an exhaust pipe of an internal combustion engine and used for measuring the oxygen concentration in the exhaust gas. FIG.

  The metal shell 30 shown in FIG. 4 has a male screw portion 31 for attaching the gas sensor to the exhaust pipe, and a hexagonal portion 32 to which an attachment tool is applied at the time of attachment. Further, the metal shell 30 is provided with a metal side step portion 33 protruding radially inward, and this metal side step portion 33 supports a metal holder 34 for holding the gas sensor element 100. . Inside the metal holder 34, a ceramic holder 35 and a talc 36 for arranging the gas sensor element 100 at a predetermined position are arranged in this order from the tip side.

  The talc 36 includes a first talc 37 disposed in the metal holder 34 and a second talc 38 disposed over the rear end of the metal holder 34. An alumina sleeve 39 is disposed on the rear end side of the second talc 38. The sleeve 39 is formed in a multi-stage cylindrical shape, and is provided with a shaft hole 391 along the axis, and the gas sensor element 100 is inserted through the shaft hole 391. The caulking portion 301 on the rear end side of the metal shell 30 is bent inward, and the sleeve 39 is pressed to the front end side of the metal shell 30 via the stainless steel ring member 40.

  Further, a metal protector 24 having a plurality of gas intake holes 241 is attached to the outer periphery of the metal shell 30 at the front end side thereof by covering the front end portion of the gas sensor element 100 protruding from the tip of the metal shell 30 by welding. . The protector 24 has a double structure, and has a bottomed cylindrical outer protector 41 having a uniform outer diameter on the outer side and an outer diameter of the rear end 421 on the inner side than the outer diameter of the front end 422. An inner protector 42 having a bottomed cylindrical shape that is formed to be larger is also arranged.

  On the other hand, the front end side of the outer cylinder 25 is inserted into the rear end side of the metal shell 30. The outer cylinder 25 has a distal end portion 251 whose diameter is enlarged on the distal end side fixed to the metal shell 30 by laser welding or the like. A separator 50 is disposed inside the rear end side of the outer cylinder 25, and a holding member 51 is interposed in a gap between the separator 50 and the outer cylinder 25. The holding member 51 is fixed to the outer cylinder 25 and the separator 50 by engaging a protruding portion 501 of the separator 50 described later and crimping the outer cylinder 25.

  The separator 50 has a through hole 502 through which the lead wires 111 to 114 of the gas sensor element 100 are inserted from the front end side to the rear end side (note that the lead wire 114 is not shown). A connection terminal 116 that connects the lead wires 111 to 114 and an external terminal of the gas sensor element 100 is accommodated in the through hole 502. Each lead wire 111-114 is connected to a connector (not shown) outside. An electrical signal is input / output between the external device such as the ECU and the lead wires 111 to 114 via the connector. Further, although not shown in detail, each lead wire 111 to 114 has a structure in which a conductive wire is covered with an insulating film made of resin.

  Further, a substantially cylindrical rubber cap 52 for closing the opening 252 on the rear end side of the outer cylinder 25 is disposed on the rear end side of the separator 50. The rubber cap 52 is fixed to the outer cylinder 25 by caulking the outer periphery of the outer cylinder 25 toward the radially inner side in a state where the rubber cap 52 is mounted in the rear end of the outer cylinder 25. A through hole 521 for inserting the lead wires 111 to 114 is also provided in the rubber cap 52 from the front end side to the rear end side.

  According to the gas sensor 600 in which the gas sensor element 100 configured as described above is incorporated, the effective area of the electrode main body can be made constant, and variations in performance can be reduced. That is, the output becomes constant by making the effective area of the electrode body portion constant. In addition, since the resistance between the electrode main bodies is constant, the temperature control accuracy when the temperature is controlled based on the resistance can be improved. Furthermore, variations in the light-off time can be reduced.

  FIG. 3 shows another example of the patterns of the insulating layers 150 and 155. As shown in FIG. 3A, the insulating tank 155 is provided, and a rectangular opening 158 is provided in the detection electrode portion 142. The other regions may be provided over substantially the entire surface of the solid electrolyte body 11. The insulating layer 150 may also be formed so as to provide a rectangular opening 153 in the reference electrode portion 132, and the insulating layer 150 may be provided on both sides of the solid electrolyte body 11. However, even in this case, the insulating layer 155 extends from the outer edges of both sides (upper and lower sides in the figure) of the detection electrode unit 142, and the opening 158 has a dimension in the side direction (up and down direction in the figure). The size is smaller than the portion 142 and is larger than the detection electrode portion 142 in the direction perpendicular thereto. Further, the insulating layer 150 extends from the outer edge of the reference electrode portion 132 at the front end side (left side in the figure) and the rear end side (right side in the figure), and the opening 153 has dimensions in the front-rear direction (left and right direction in the figure). The size is smaller than the reference electrode portion 132 and the side dimension perpendicular to the reference electrode portion 132 is larger than the reference electrode portion 132. In other words, the insulating layer 155 defines a lateral region of the electrode body, and the insulating layer 150 defines a longitudinal region of the electrode body. As shown in FIG. 3C, when the insulating layer 150 and the insulating layer 155 are overlapped and projected in the opposing direction of the detection electrode portion 142 and the reference electrode portion 132, the detection electrode portion 142 and the reference electrode portion 132 are displayed. An opening 159 smaller than the detection electrode part 142 and the reference electrode part 132 is formed at a position corresponding to.

  Without providing the insulating layers 150 and 155 as described above, for example, when the size of the reference electrode portion 132 is made smaller than the detection electrode portion 142, the overlapping portion of the reference electrode portion 132 and the detection electrode portion 142 due to misalignment is detected. Although the variation of the area can be prevented, the effect of the overlapping portion between the lead portion and the electrode appears, and the effective area cannot be made constant. In addition, a rectangular window-like opening is provided on one surface of the solid electrolyte body 11, for example, the insulating layer provided on the reference electrode part 132 side, and the vertical and horizontal dimensions of the window-like opening are defined as the reference electrode part 132. It is also possible to make the effective area of the electrode main body portion constant by making it smaller. However, in this case, the window-like opening must be made smaller than the insulating layer formed on the lead portion of the other surface (detection electrode portion 142 side) of the solid electrolyte body 11, and in the case of this embodiment, In comparison, the effective area of the electrode main body becomes smaller.

  FIG. 5 shows a configuration of a gas sensor element 400 according to another embodiment, and parts corresponding to those of the gas sensor element 100 shown in FIG. The gas sensor element 400 of the present embodiment is configured by laminating a heater 2 and a gas sensor element body 3.

  The gas sensor element body 3 includes an oxygen concentration detection cell 130 and an oxygen pump cell 140. A gas detection chamber forming layer 160 is provided between the oxygen concentration detection cell 130 and the oxygen pump cell 140, and the protective layer 12 is provided outside the oxygen pump cell 140 (upper side in the drawing).

  The oxygen concentration detection cell 130 includes a solid electrolyte body 11, and a reference electrode 13 and a detection electrode 14 formed on both surfaces of the solid electrolyte body 11. An insulating layer 150 is formed between the solid electrolyte body 11 and the reference electrode 13, and an insulating layer 155 is formed between the solid electrolyte body 11 and the detection electrode 14.

  The insulating layer 150 is provided in a line shape on both sides of the side end portion along the longitudinal direction of the solid electrolyte body 11, and covers the outer edges on both sides of the reference electrode portion 132. On the other hand, the insulating layer 155 covers the front end side outer edge and the rear end side outer edge among the four sides of the detection electrode portion 142.

  As described above, one of the pair of electrode portions is the detection electrode portion 142 exposed to the gas to be measured introduced into the gas detection chamber 162 through the diffusion rate controlling portion 163, and the other is the reference electrode portion 132. The layer 155 covers a pair of outer edges of two opposing sides along the direction in which the gas to be measured of the detection electrode unit 142 is introduced into the gas detection chamber 162 (in this embodiment, the width direction of the gas sensor element 400). Therefore, even if the detection electrode portion 142 varies in the longitudinal direction of the gas sensor element 400, when the gas to be measured is introduced into the gas detection chamber 162, the detection electrode portion 142 is always detected except for the second insulating layer. Since it comes into contact with the electrode 142, detection accuracy is improved.

  On the other hand, the oxygen pump cell 140 includes a second solid electrolyte body 181, and a third electrode 170 and a fourth electrode 190 formed on both surfaces of the second solid electrolyte body 181. The 3rd electrode 170 and the 4th electrode 190 are provided so that the 3rd electrode part 172 and the 4th electrode part 192 which constitute a detection part (not shown) with the 2nd solid electrolyte body 181 may face. . The third electrode portion 172 is provided with a third lead portion 171 extending in the longitudinal direction of the second solid electrolyte body 181. The fourth electrode portion 192 is provided with a fourth lead portion 191 that extends in the longitudinal direction of the second solid electrolyte body 181.

  The gas detection chamber forming layer 160 formed between the oxygen pump cell 140 and the oxygen concentration detection cell 130 includes an insulating portion 161 and a diffusion rate controlling portion 163. In the insulating portion 161 of the gas detection chamber forming layer 160, a gas detection chamber 162 is formed at a position corresponding to the detection electrode portion 142 and the third electrode portion 172. The gas detection chamber 162 communicates with the outside in the width direction of the gas detection chamber forming layer 160, and gas diffusion between the outside and the gas detection chamber 162 is realized under a predetermined rate-limiting condition in the communication portion. A diffusion rate limiting unit 163 is disposed.

  The material of the insulating part 161 is not particularly limited as long as it is an insulating ceramic sintered body, and examples thereof include oxide ceramics such as alumina and mullite. The diffusion control part 163 is a porous body made of alumina. The diffusion rate-limiting unit 163 performs rate-limiting when the detection gas flows into the gas detection chamber 162.

  The ends of the reference electrode lead 131 are provided in the through holes 110 and 154 provided in the solid electrolyte body 11 and the insulating layer 155, the through holes 164 provided in the insulating layer 160, and the second solid electrolyte body 181. The through hole 182 and the through hole 123 provided in the protective layer 12 are electrically connected to one of the three signal extraction terminals 126 provided. The terminal of the detection electrode lead portion 141 is for signal extraction through a through hole 165 provided in the insulating layer 160, a through hole 183 provided in the second solid electrolyte body 181 and a through hole 124 provided in the protective layer 12. It is electrically connected to one of the terminals 126.

  The terminal end of the third lead portion 171 is electrically connected to one signal extraction terminal 126 through a through hole 183 provided in the second solid electrolyte body 181 and a through hole 124 provided in the protective layer 12. Has been. The end of the fourth lead portion 191 is electrically connected to one signal extraction terminal 126 via a through hole 125 provided in the protective layer 12. Note that the detection electrode lead portion 141 and the third lead portion 171 have the same potential through the through hole 165.

  As described above, in the gas sensor element 400 including the oxygen pump cell 140 and the oxygen concentration detection cell 130, oxygen contained in the gas to be measured in the gas detection chamber 162 is introduced and derived by the oxygen pump action of the oxygen pump cell 140. The oxygen concentration can be measured by the concentration cell action of the oxygen concentration detection cell 130 and can be used as an air-fuel ratio sensor or the like. The present invention can be applied to such a gas sensor element 400 as in the case of the gas sensor element 100 described above, and similar effects can be obtained.

  In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment and the like, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. For example, the present invention can also be applied to gas sensors other than oxygen sensors and air-fuel ratio sensors, for example, stacked gas sensor elements used for HC sensors, CO sensors, and NOx sensors.

  For example, in the gas sensor element 400, the diffusion rate limiting unit 163 is provided on the side surface of the gas sensor element 400, but the gas sensor element 400 may have a configuration provided at the tip of the gas sensor element 400. In this case, the insulating layer 150 covers the outer edge on the front end side and the outer edge on the rear end side among the four sides of the detection electrode 142, and the insulating layer 155 is disposed on both sides of the side end portion along the longitudinal direction of the solid electrolyte body 11. It is preferably provided in a line shape and covers the outer edges on both sides of the reference electrode portion 132.

The disassembled perspective view which shows typically the structure of the gas sensor element which concerns on embodiment of this invention. The figure which expands and shows the principal part structure of the gas sensor element of FIG. The figure which expands and shows the principal part structure of the gas sensor element which concerns on other embodiment. Sectional drawing which shows the structure of the gas sensor which concerns on embodiment of this invention. The disassembled perspective view which shows typically the structure of the gas sensor element which concerns on other embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Gas sensor element main body, 2 ... Heater, 11 ... Solid electrolyte body, 13 ... Reference electrode, 14 ... Detection electrode, 100 ... Gas sensor element, 150, 155 ... Insulating layer, 151, 156, 159 ……Aperture.

Claims (5)

A solid electrolyte body that is formed in a plate shape and whose electrical characteristics change according to the concentration of a specific gas in the gas to be measured;
A pair of rectangular electrode body portions formed on one surface and the other surface of the solid electrolyte body, facing each other through the solid electrolyte body, and constituting a detection unit together with the solid electrolyte body;
One side of the solid electrolyte body and provided between the solid electrolyte body and one of the electrode main body portions, and one set of outer edges of two opposing sides of the four sides of the electrode main body portion A first insulating layer covering
The other side of the solid electrolyte body is provided between the solid electrolyte body and the other electrode main body, and is different from the two sides covered by the first insulating layer of the other electrode main body. A second insulating layer covering the two sides of
Comprising
When the first insulating layer and the second insulating layer are overlapped and projected in the facing direction of the electrode main body, an opening smaller than the electrode main body is formed at a corresponding position of the electrode main body. A gas sensor element comprising the first insulating layer and the second insulating layer.   The electrode main body portion is connected to an electrode lead portion that extends in the longitudinal direction of the solid electrolyte body and extracts a signal from the electrode main body portion, and the first insulating layer and the second insulating layer are connected to the electrode lead portion. 2. The gas sensor element according to claim 1, wherein the gas sensor element extends between the first and second solid electrolyte bodies.   One of the pair of electrode main body portions is a detection electrode portion exposed to the gas to be measured introduced into the measurement chamber via a diffusion rate limiting portion, the other is a reference electrode portion, and the second insulating layer is the detection electrode 3. The gas sensor element according to claim 1, wherein the gas sensor element is provided so as to cover a pair of opposing outer edges along a direction in which the gas to be measured of the electrode portion is introduced into the measurement chamber.   The reference electrode part is composed of a porous body, and the reference electrode part is covered with the solid electrolyte body and the shield, and oxygen is pumped into the reference electrode part side, and the pump is pumped in. 4. The gas sensor element according to claim 3, wherein the gas sensor element is a self-generated reference electrode in which a reference oxygen concentration of a predetermined level is formed inside itself by oxygen.   A gas sensor, wherein the gas sensor element according to any one of claims 1 to 4 is incorporated in a metal shell.

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