JP6820759B2 - Gas sensor element - Google Patents

Description

The present disclosure relates to a gas sensor element that detects the concentration of a specific gas contained in a gas to be measured.

As in Patent Document 1, a NOx sensor that detects the concentration of a specific gas contained in a gas to be measured, for example, a nitrogen oxide concentration (hereinafter, NOx concentration) is known.
In the gas sensor element of the NOx sensor described in Patent Document 1, the gas to be measured is introduced into the first measurement chamber, and the oxygen concentration of the gas to be measured is determined by the first pumping cell composed of the solid electrolyte and the pair of first electrodes. Is adjusted to the concentration of. Then, the gas to be measured whose oxygen concentration is adjusted flows from the first measurement chamber to the second measurement chamber, and NOx in the gas to be measured is generated in the second pumping cell composed of the solid electrolyte and the pair of second electrodes. Is decomposed, and a second pumping current corresponding to the NOx concentration flows between the pair of second electrodes. Further, the gas sensor element of the NOx sensor described in Patent Document 1 includes a heater that heats the NOx sensor to the activation temperature in order to increase the conductivity of oxygen ions in the solid electrolyte layer and stabilize the operation of the NOx sensor. ..

The gas sensor element of the NOx sensor described in Patent Document 1 is formed in the shape of a long plate, and one electrode pad for detecting the second pumping current (hereinafter, on either the front surface or the back surface). , The second pumping current electrode pad) and two electrode pads for energizing the heater are formed.

Japanese Unexamined Patent Publication No. 2010-266429

When the through hole formed inside the gas sensor element for electrically connecting the second electrode and the second pumping current electrode pad is arranged directly under the second pumping current electrode pad, the second electrode is placed. The surface of the pumping current electrode pad may be dented. If the surface of the second pumping current electrode pad is recessed, there is a high possibility that poor contact between the second pumping current electrode pad and the connection terminal connected to the second pumping current electrode pad will occur. It ends up.

An object of the present disclosure is to suppress the occurrence of dents in the electrode pads.

One aspect of the present disclosure is a gas sensor element having a measuring chamber, a first pumping cell, a second pumping cell, and a heater, and having an element main body formed in a long plate shape.
The gas to be measured is introduced into the measurement chamber. The first pumping cell has an oxygen ion conductive first solid electrolyte body and a pair of first electrodes formed on the first solid electrolyte body, and a first pumping current is provided between the pair of first electrodes. Oxygen in the gas to be measured introduced into the measurement chamber is pumped out or pumped out by flowing the flow.

The second pumping cell has an oxygen ion conductive second solid electrolyte body and a pair of second electrodes formed on the second solid electrolyte body, and the oxygen concentration in the measurement chamber is measured in the first pumping cell. A second pumping current whose value changes according to the concentration of the specific gas contained in the adjusted gas to be measured flows between the pair of second electrodes.

The heater has a heat generating resistor and a pair of lead portions connected to both ends of the heat generating resistor, and heats the first pumping cell and the second pumping cell.
The element main body includes a first electrode pad, a second electrode pad, and a third electrode pad formed on the pad forming surface with either the front surface or the back surface as a pad forming surface. The first electrode pad is arranged on the pad forming surface so as to be farther from the first pumping cell and the second pumping cell than the second electrode pad and the third electrode pad.

The element main body includes a first insulating layer having a pad forming surface and a second insulating layer laminated on the first insulating layer on a surface opposite to the pad forming surface. The first electrode pad is electrically connected to either one of the pair of second electrodes via at least a first through hole penetrating the first insulating layer and a second through hole penetrating the second insulating layer. Be connected.

The first through hole is formed on a straight line in the stacking direction, which is a straight line passing through the second through hole along the stacking direction, with the direction in which the first insulating layer and the second insulating layer are laminated as the stacking direction. The pad and the first through hole are arranged so as not to be located. Further, the second through hole is arranged so that the straight line passing through the first through hole is not located along the longitudinal direction of the pad forming surface on the straight line in the stacking direction. Further, the second through hole is arranged so that either one of the first opposite region and the second opposite region is located on the straight line in the stacking direction. The first opposite region is a region on the pad forming surface opposite to the first pumping cell and the second pumping cell being arranged with the second electrode pad interposed therebetween. The second opposite region is a region on the pad forming surface opposite to the area where the first pumping cell and the second pumping cell are arranged with the third electrode pad interposed therebetween.

In the gas sensor element of the present disclosure configured as described above, the first electrode pad, the second electrode pad, and the second electrode pad are formed on their respective straight lines passing through the first electrode pad, the second electrode pad, and the third electrode pad along the stacking direction. And the second through hole is not arranged (directly below the third electrode pad). Therefore, the gas sensor element of the present disclosure can suppress the occurrence of dents in the first electrode pad, the second electrode pad, and the third electrode pad.

It is sectional drawing of NOx sensor 1. It is a figure which shows the schematic structure of the element main body part 31 and the sensor control device 170. It is an exploded perspective view of the element main body 31. It is a figure which shows the upper surface of the insulating layer 118, the lower surface of the insulating layer 119, and the end of the rear end side BE on the upper surface and the lower surface of the insulating layer 120.

The embodiments of the present disclosure will be described below together with the drawings.
The NOx sensor 1 of the present embodiment is mounted on a vehicle and detects nitrogen oxides (hereinafter referred to as NOx) contained in exhaust gas discharged from an internal combustion engine.

As shown in FIG. 1, the NOx sensor 1 includes a main metal fitting 2, a gas sensor element 3, a holding portion 4, a protector 5, an outer cylinder 6, a plurality of lead wires 7, and a plurality of connection terminals 8. A separation unit 9 and a grommet 10 are provided. In FIG. 1, the lower end side of the gas sensor 1 is referred to as a front end side FE, and the upper end side of the gas sensor 1 is referred to as a rear end side BE.

The main metal fitting 2 is a member formed in a tubular shape with a heat-resistant metal such as stainless steel. The main metal fitting 2 includes a main body portion 21 and a mounting portion 22.
The main body 21 is formed in a cylindrical shape extending in the direction of the axis O of the gas sensor 1 (hereinafter, the axial direction DA), and a male screw 21a is formed on the outer periphery thereof. The male screw 21a has a shape that can be fitted into a mounting screw hole provided in the exhaust pipe for mounting the gas sensor 1 to the exhaust pipe of the internal combustion engine. Further, the main body 21 is provided with a through hole 21b penetrating along the axial direction DA. A step portion 21c that projects inward in the radial direction is formed on the inner peripheral wall of the through hole 21b.

The mounting portion 22 extends outward along the radial direction from the outer circumference located on the rear end side BE of the male screw 21a in the main body portion 21, and the outer circumference is formed in a hexagonal plate shape. The mounting portion 22 is a portion for fitting a mounting tool such as a hexagon wrench when mounting the gas sensor 1 on the exhaust pipe.

The gas sensor element 3 includes an element main body 31 and a protective layer 32. The element main body 31 is formed in the shape of a long plate extending in the axial direction DA. Then, the detection that detects the concentration of the specific gas (NOx in this embodiment) contained in the gas to be measured (exhaust gas of the internal combustion engine in this embodiment) to which the gas sensor element 3 is exposed to the tip side FE of the element main body 31. Part 31a is formed. The protective layer 32 is made of porous alumina and is arranged on the tip end side FE of the element main body 31 so as to cover at least the detection unit 31a.

The holding portion 4 includes a ceramic holder 41, talc rings 42, 43, a ceramic sleeve 44, a packing 45, and a metal holder 46.
Inside the through hole 21b of the main metal fitting 2, a ceramic holder 41 which is a tubular member surrounding the radial circumference of the gas sensor element 3 and a powder filling layer are formed in this order from the front end side FE to the rear end side BE. The talc rings 42 and 43 and the ceramic sleeve 44 are laminated.

A packing 45 is arranged between the ceramic sleeve 44 and the end portion of the rear end side BE of the main metal fitting 2. A metal holder 46 is arranged between the ceramic holder 41 and the stepped portion 21c of the main metal fitting 2. The metal holder 46 holds the talc ring 42 and the ceramic holder 41. The end portion of the rear end side BE of the main metal fitting 2 is crimped so as to press the ceramic sleeve 44 toward the front end side FE via the packing 45. As a result, the talc rings 42 and 43 are compression-filled, and in the holding portion 4, the front end side FE of the gas sensor element 3 protrudes from the front end side FE of the main metal fitting 2, and the rear end side BE of the gas sensor element 3 is the main metal fitting 2. The gas sensor element 3 is held in a state of protruding from the rear end side BE.

The protector 5 is a metal member formed in a tubular shape so as to cover the end portion of the FE on the distal end side of the gas sensor element 3 protruding from the main metal fitting 2. A plurality of gas intake holes are formed in the protector 5. The protector 5 is joined to the outer periphery of the FE on the tip end side of the main metal fitting 2 by welding.

The protector 5 has a double structure and includes an outer protector 51 and an inner protector 52. A bottomed cylindrical outer protector 51 is arranged on the outside, and a bottomed cylindrical inner protector 52 is arranged on the inside.

The outer cylinder 6 is a metal member formed in a tubular shape extending in the axial direction DA. The outer cylinder 6 is fixed in a state in which a portion of the main body 21 of the main metal fitting 2 located on the rear end side BE of the main metal fitting 2 is fitted into the opening 6a at the end portion of the front end side FE.

The plurality of lead wires 7 are provided corresponding to the plurality of electrode pads 36a, 36b, 36c, 37a, 37b, 37c formed on the rear end side BE of the element main body 31, respectively, and the element main body 31 And a lead wire for electrically connecting the sensor control device 170 that drives and controls the gas sensor element 3. Note that FIG. 1 shows two lead wires 7. Further, the electrode pads 36a, 36b, 36c, 37a, 37b, 37c are not shown in FIG. 1, but are shown in FIG. Further, the sensor control device 170 is not shown in FIG. 1 but is shown in FIG.

The plurality of connection terminals 8 are provided corresponding to each of the plurality of lead wires 7, and are attached to one end of the corresponding lead wires 7.
The separation unit 9 includes separators 91 and 92 and a holding member 93. The separators 91 and 92 are ceramic members formed in a cylindrical shape extending in the axial direction DA, and the separator 91 and the separator 92 are laminated in this order from the front end side FE to the rear end side BE, and are outside. It is arranged in the cylinder 6.

Inside the separator 91, a space capable of accommodating a plurality of connection terminals 8 and a part of the rear end side BE of the element main body 31 is formed. The separator 91 holds a state in which the rear end side BEs of the plurality of connection terminals 8 protrude from the rear end side BEs of the separator 91 and the plurality of connection terminals 8 do not contact each other, and the plurality of connection terminals 8 are placed inside. To accommodate. Further, the separator 91 holds a state in which the plurality of connection terminals 8 are in contact with the electrode pads 36a, 36b, 36c, 37a, 37b, 37c of the element main body 31, respectively. Further, a flange portion 91a extending outward along the radial direction is formed on the outer peripheral surface of the rear end side BE of the separator 91.

The separator 92 is formed with a plurality of through holes penetrating along the axial direction DA. The plurality of through holes are provided corresponding to each of the plurality of connection terminals 8 described above, and the corresponding connection terminals 8 are inserted into the plurality of through holes.

The holding member 93 includes a main body portion 93a and a curved portion 93b. The main body portion 93a is a metal member formed in a tubular shape extending in the axial direction DA. The curved portion 93b is a member that extends from the rear end side BE of the main body portion 93a and is bent in a U shape. The holding member 93 is installed so as to be located between the outer cylinder 6 and the separator 91 on the tip side FE of the collar portion 91a. As a result, the main body portion 93a is in contact with the inner peripheral surface of the outer cylinder 6, and the curved portion 93b is in a state of pressing the separator 91 toward the inside thereof. Therefore, the separator 91 is held in the outer cylinder 6 by the holding member 93.

Further, the separator 92 is in a state in which the end portion of the front end side FE and the end portion of the rear end side BE are pressed against the separator 91 and the grommet 10, respectively. As a result, the separator 92 is held in the outer cylinder 6.

The grommet 10 is an elastic member made of fluororubber formed in a cylindrical shape extending in the axial direction DA. The grommet 10 is formed with a plurality of through holes penetrating along the axial direction DA. The plurality of through holes are provided corresponding to each of the plurality of lead wires 7 described above, and the corresponding lead wires 7 are inserted into the plurality of through holes.

The grommet 10 is arranged inside the opening 6b at the end of the rear end side BE in the outer cylinder 6, and is crimped in the radial direction via the outer cylinder 6. As a result, the opening 6b at the end of the rear end side BE in the outer cylinder 6 is closed.

As shown in FIG. 2, the element main body 31 of the gas sensor element 3 has an insulating layer 113, a ceramic layer 114, an insulating layer 115, a ceramic layer 116, an insulating layer 117, an insulating layer 118, an insulating layer 119, and an insulating layer 120 laminated. It is configured to be sequentially laminated along the direction SD. The insulating layers 113, 115, 117, 118, 119, 120 are formed mainly of alumina.

The element main body 31 includes a first measurement chamber 121 formed between the ceramic layer 114 and the ceramic layer 116. The element main body 31 is exhausted from the outside to the inside of the first measurement chamber 121 via a diffusion resistor 122 arranged between the ceramic layer 114 and the ceramic layer 116 so as to be adjacent to the first measurement chamber 121. Introduce gas. The diffusion resistor 122 is made of a porous material such as alumina. The diffusion resistor 122 is not shown in FIG. 2, but is shown in FIG.

The element main body 31 includes a first pumping cell 130. The first pumping cell 130 includes a solid electrolyte layer 131 and pumping electrodes 132 and 133.
The solid electrolyte layer 131 is mainly formed of zirconia having oxygen ion conductivity. A part of the ceramic layer 114 in the region in contact with the first measurement chamber 121 is removed, and the solid electrolyte layer 131 is filled in place of the ceramic layer 114.

The pumping electrodes 132 and 133 are formed mainly of platinum. The pumping electrode 132 is arranged on the surface of the solid electrolyte layer 131 in contact with the first measurement chamber 121. The pumping electrode 133 is arranged on the surface of the solid electrolyte layer 131 on the opposite side of the solid electrolyte layer 131 from the pumping electrode 132. The insulating layer 113 in the region where the pumping electrode 133 is arranged and the region around the pumping electrode 133 is removed, and the porous body 134 is filled in place of the insulating layer 113. The porous body 134 allows gas (for example, oxygen) to enter and exit between the pumping electrode 133 and the outside.

The element main body 31 includes an oxygen concentration detection cell 140. The oxygen concentration detection cell 140 includes a solid electrolyte layer 141, a detection electrode 142, and a reference electrode 143.
The solid electrolyte layer 141 is mainly formed of zirconia having oxygen ion conductivity. A part of the ceramic layer 116 in the region on the rear end side (that is, the right side in FIG. 2) of the solid electrolyte layer 131 is removed, and the solid electrolyte layer 141 is filled in place of the ceramic layer 116.

The detection electrode 142 and the reference electrode 143 are formed mainly of platinum. The detection electrode 142 is arranged on the surface of the solid electrolyte layer 141 in contact with the first measurement chamber 121. The reference electrode 143 is arranged on the surface of the solid electrolyte layer 141 on the side opposite to the detection electrode 142 with the solid electrolyte layer 141 interposed therebetween.

The element main body 31 includes a reference oxygen chamber 146. The reference oxygen chamber 146 is a through hole formed by removing the insulating layer 117 in the region where the reference electrode 143 is arranged and the region around the reference electrode 143.

The element main body 31 includes a second measurement chamber 148. The second measurement chamber 148 is formed so as to penetrate the solid electrolyte layer 141 and the insulating layer 117 on the rear end side of the detection electrode 142 and the reference electrode 143. The element main body 31 introduces the exhaust gas discharged from the first measurement chamber 121 into the inside of the second measurement chamber 148.

The element main body 31 includes a second pumping cell 150. The second pumping cell 150 includes a solid electrolyte layer 151 and pumping electrodes 152 and 153.
The solid electrolyte layer 151 is formed mainly of zirconia having oxygen ion conductivity. The solid electrolyte layer 151 is arranged between the insulating layer 117 and the insulating layer 119 so as to be in contact with the reference oxygen chamber 146, the second measurement chamber 148, and the surrounding region. The insulating layer 118 is arranged between the insulating layer 117 and the insulating layer 119 so as to cover the periphery of the solid electrolyte layer 151.

The pumping electrodes 152 and 153 are formed mainly of platinum. The pumping electrode 152 is arranged on the surface of the solid electrolyte layer 151 in contact with the second measurement chamber 148. The pumping electrode 153 is arranged on the surface of the solid electrolyte layer 151 on the side opposite to the reference electrode 143 with the reference oxygen chamber 146 interposed therebetween. Inside the reference oxygen chamber 146, a porous body 147 is arranged so as to cover the pumping electrode 153.

The element main body 31 includes a heater 160. The heater 160 is a heat-generating resistor formed mainly of platinum and generating heat when energized, and is arranged between the insulating layer 119 and the insulating layer 120.

The element main body 31 is connected to the sensor control device 170. The sensor control device 170 controls the element main body 31 and calculates the NOx concentration in the exhaust gas based on the detection result of the element main body 31.

The sensor control device 170 includes a control circuit 180 and a microcomputer 190 (hereinafter referred to as a microcomputer 190).
The control circuit 180 is an analog circuit arranged on a circuit board. The control circuit 180 includes an Ip1 drive circuit 181, a Vs detection circuit 182, a reference voltage comparison circuit 183, an Icp supply circuit 184, a Vp2 application circuit 185, an Ip2 detection circuit 186, and a heater drive circuit 187.

Then, the pumping electrode 132, the detection electrode 142, and the pumping electrode 152 are connected to the reference potential. The pumping electrode 133 is connected to the Ip1 drive circuit 181. The reference electrode 143 is connected to the Vs detection circuit 182 and the Icp supply circuit 184. The pumping electrode 153 is connected to the Vp2 application circuit 185 and the Ip2 detection circuit 186. The heater 160 is connected to the heater drive circuit 187.

The Ip1 drive circuit 181 applies a voltage Vp1 between the pumping electrode 132 and the pumping electrode 133 to supply the first pumping current Ip1 and detects the supplied first pumping current Ip1.

The Vs detection circuit 182 detects the voltage Vs between the detection electrode 142 and the reference electrode 143, and outputs the detected result to the reference voltage comparison circuit 183.
The reference voltage comparison circuit 183 compares the reference voltage (for example, 425 mV) with the output of the Vs detection circuit 182 (that is, the voltage Vs), and outputs the comparison result to the Ip1 drive circuit 181. Then, the Ip1 drive circuit 181 controls the flow direction of the first pumping current Ip1 and the magnitude of the first pumping current Ip1 so that the voltage Vs becomes equal to the reference voltage, and controls the oxygen concentration in the first measuring chamber 121. , Adjust to a predetermined value so that NOx does not decompose.

The Icp supply circuit 184 causes a weak current Icp to flow between the detection electrode 142 and the reference electrode 143. As a result, oxygen is sent from the first measurement chamber 121 to the reference oxygen chamber 146 via the solid electrolyte layer 141, so that the reference oxygen chamber 146 is set to a predetermined oxygen concentration as a reference.

The Vp2 application circuit 185 applies a constant voltage Vp2 (for example, 450 mV) between the pumping electrode 152 and the pumping electrode 153. As a result, in the second measurement chamber 148, NOx is dissociated by the catalytic action of the pumping electrodes 152 and 153 constituting the second pumping cell 150. The oxygen ion obtained by this dissociation moves through the solid electrolyte layer 151 between the pumping electrode 152 and the pumping electrode 153, so that the second pumping current Ip2 flows. The Ip2 detection circuit 186 detects the second pumping current Ip2.

The heater drive circuit 187 drives the heater 160 by applying a positive voltage for energizing the heater to one end of the heater 160, which is a heat generating resistor, and applying a negative voltage for energizing the heater to the other end of the heater 160. ..

As shown in FIG. 3, three electrode pads 36a, 36b, and 36c are formed at the end of the rear end side BE on the upper surface of the insulating layer 113. Three electrode pads 37a, 37b, and 37c are formed at the end of the rear end side BE on the lower surface of the insulating layer 120.

On the lower surface of the ceramic layer 114, a lead portion 132a that is connected to the pumping electrode 132 by the front end side FE and extends toward the rear end side BE is formed. On the upper surface of the ceramic layer 114, a lead portion 133a that is connected to the pumping electrode 133 by the front end side FE and extends toward the rear end side BE is formed.

On the upper surface of the ceramic layer 116, a lead portion 142a that is connected to the detection electrode 142 by the front end side FE and extends toward the rear end side BE is formed. On the lower surface of the ceramic layer 116, a lead portion 143a which is connected to the reference electrode 143 by the front end side FE and extends toward the rear end side BE is formed.

On the upper surface of the insulating layer 118, a lead portion 152a connected to the pumping electrode 152 by the front end side FE and extending toward the rear end side BE, and a lead portion 152a connected to the pumping electrode 153 by the front end side FE toward the rear end side BE. An extending lead portion 153a is formed.

The heater 160 includes a heat generation resistor 161, a lead portion 162 connected to one end of the heat generation resistor 161 and 163 connected to the other end of the heat generation resistor 161.
The electrode pad 36a is connected to the lead portion 133a by the through-hole conductor L1. The electrode pad 36b is connected to the lead portion 143a by the through-hole conductor L2. The electrode pad 36c is connected to the lead portion 152a by the through-hole conductor L3.

The electrode pad 37a is connected to the lead portion 153a by the through-hole conductors L4 and L5 and the connecting portion CN described later.
The electrode pad 37b is connected to the lead portion 162 by the through-hole conductor L6. The electrode pad 37c is connected to the lead portion 163 by the through-hole conductor L7.

The through-hole conductor L1 is created by forming a conductor on the inner surface of the through hole H1 formed at the end of the rear end side BE in the insulating layer 113.
The through-hole conductor L2 is created by forming a conductor on the inner surface of the through holes H2, H3, H4, and H5. The through holes H2 and H4 are formed at the ends of the rear end side BEs of the insulating layers 113 and 115, respectively. The through holes H3 and H5 are formed at the ends of the rear end side BEs of the ceramic layers 114 and 116, respectively.

The through-hole conductor L3 is created by forming a conductor on the inner surface of the through holes H6, H7, H8, H9, and H10. The through holes H6, H8, and H10 are formed at the ends of the rear end side BEs of the insulating layers 113, 115, and 117, respectively. The through holes H7 and H9 are formed at the ends of the rear end side BEs of the ceramic layers 114 and 116, respectively.

The through-hole conductor L4 is created by forming a conductor on the inner surfaces of the through holes H11 and H12. The through hole H11 is formed at the end of the rear end side BE in the insulating layer 118. The through hole H12 is formed at the end of the rear end side BE in the insulating layer 119.

The through-hole conductor L5 is created by forming a conductor on the inner surface of the through hole H13. The through hole H13 is formed at the end of the rear end side BE in the insulating layer 120.
Through-hole conductors L6 and L7 are created by forming conductors on the inner surfaces of through-holes H14 and H15, respectively. The through holes H14 and H15 are formed at the end of the rear end side BE in the insulating layer 120.

Next, an example of the operation of the gas sensor element 3 will be described.
First, when the sensor control device 170 is activated, the sensor control device 170 supplies electric power to the heater 160. The heater 160 heats the first pumping cell 130, the oxygen concentration detection cell 140, and the second pumping cell 150 to the activation temperature.

Then, when each of the cells 130, 140, and 150 is heated to the activation temperature, the sensor control device 170 causes the first pumping current Ip1 to flow through the first pumping cell 130. As a result, the first pumping cell 130 moves oxygen between the pumping electrode 132 and the pumping electrode 133 via the solid electrolyte layer 131, so that the oxygen contained in the exhaust gas flowing into the first measuring chamber 121 Perform pumping and pumping.

The sensor control device 170 sets a first pumping current Ip1 to be passed through the first pumping cell 130 so that the voltage Vs between the detection electrode 142 and the reference electrode 143 of the oxygen concentration detection cell 140 becomes the reference voltage (for example, 425 mV). Control. The voltage Vs of the oxygen concentration detection cell 140 is a value corresponding to the oxygen concentration in the detection electrode 142 with reference to the oxygen concentration in the reference oxygen chamber 146. By this control, the oxygen concentration inside the first measuring chamber 121 is adjusted so that NOx is not decomposed.

The exhaust gas whose oxygen concentration has been adjusted in the first measurement chamber 121 further flows toward the second measurement chamber 148.
The sensor control device 170 applies a constant voltage Vp2 between the pumping electrode 152 and the pumping electrode 153 of the second pumping cell 150. This voltage is set to such a voltage that the NOx gas in the exhaust gas decomposes into oxygen and nitrogen gas. As a result, NOx in the exhaust gas is decomposed into nitrogen and oxygen. A second pumping current Ip2 flows through the second pumping cell 150 so as to pump oxygen generated by the decomposition of NOx from the second measuring chamber 148. Since there is a proportional relationship between the second pumping current Ip2 and the NOx concentration, the NOx concentration in the exhaust gas can be detected by detecting the current value of the second pumping current Ip2.

Next, a method of manufacturing the gas sensor element 3 will be described.
As shown in FIG. 3, the unfired insulating sheet serving as the ceramic layers 114 and 116 of the element main body 31, the unfired solid electrolyte sheet serving as the solid electrolyte layers 131, 141 and 151, and the unfired insulating layer sheet serving as the insulating layer 113. , An unfired insulating sheet to be the insulating layers 119 and 120 is produced.

Specifically, when forming an unfired insulating sheet to be the ceramic layers 114 and 116, butyral resin and dibutyl phthalate are added to the ceramic powder mainly composed of alumina, and a mixed solvent is further mixed. To generate a slurry. Then, this slurry is made into a sheet by the doctor blade method, and the mixed solvent is volatilized to prepare an unfired insulating sheet.

Then, in each of the unfired insulating sheets to be the ceramic layers 114 and 116, rectangular through holes corresponding to the planar shape of the unfired solid electrolyte sheets of the solid electrolyte layers 131 and 141 are formed. Further, a rectangular through hole corresponding to the porous body 134 is also formed in the unfired insulating sheet serving as the insulating layer 113.

When forming an unfired solid electrolyte sheet to be the solid electrolyte layers 131, 141, 151, first, alumina powder, butyral resin, or the like is added to the ceramic powder mainly composed of zirconia, and a mixed solvent is further added. To produce a slurry. Then, this slurry is made into a sheet by the doctor blade method, and the mixed solvent is volatilized to prepare an unfired solid electrolyte sheet. Then, the unfired solid electrolyte sheet is cut into a rectangular shape corresponding to the solid electrolyte layers 131, 141, 151.

Further, as a material to be the insulating layers 115, 117, 118 after firing, butyral resin and dibutyl phthalate are added to a ceramic powder mainly composed of alumina, and a mixed solvent is further mixed to prepare an alumina slurry. ..

Further, in order to form an unfired porous body which becomes a diffusion resistor 122, a porous body 134, and a porous body 147 after firing, 100% by mass of alumina powder, a heat-burned material (for example, carbon, etc.) and a plasticizer are used. A porous slurry dispersed by wet mixing is prepared. The plasticizer has butyral resin and DBP.

Next, a heater pattern including a heat generating resistor 161 and lead portions 162 and 163 is formed on the upper surface of the unfired insulating sheet to be the insulating layer 120. As a material for the heater pattern, for example, a platinum paste containing platinum as a main component and a ceramic (for example, alumina) is produced, and this platinum paste is printed to form a heater pattern.

Further, on the lower surface of the unfired insulating sheet to be the insulating layer 120, the patterns of the electrode pads 37a, 37b, and 37c are printed using metallized ink such as platinum.
Further, holes to be through holes H13, H14, and H15 are formed in the unfired insulating sheet to be the insulating layer 120, and metallized ink is applied to the inner peripheral surfaces of the holes.

Since the method of forming the other through holes H1 to H12 and the method of applying the metallized ink are the same, the same description regarding the other through holes H1 to H12 will be omitted below.
Next, the unfired insulating sheet to be the insulating layer 119 is laminated on the upper surface of the unfired insulating sheet to be the insulating layer 120 so as to cover the heater pattern. Further, an unfired solid electrolyte sheet cut into a rectangular shape to be a solid electrolyte layer 151 is laminated on the upper surface of the unfired insulating sheet to be the insulating layer 119.

Next, a layer to be the insulating layer 118 is printed (for example, screen printing) on the upper surface of the unfired insulating sheet to be the insulating layer 119 using an alumina slurry. As a result, the insulating layer 118 is formed so as to embed the step formed between the upper surface of the solid electrolyte layer 151 and the upper surface of the insulating layer 119.

Next, the electrode patterns to be the pumping electrodes 152 and 153 are printed on the upper surfaces of the layers to be the solid electrolyte layer 151 and the insulating layer 118 by using metallized ink. Further, the lead pattern forming the lead portions 152a and 153a is printed using the platinum paste. The materials for the electrode pattern and the lead pattern are the same for the unfired insulating sheets used as the ceramic layers 114 and 116.

Further, the layer to be the insulating layer 117 is printed on the upper surfaces of the layers to be the solid electrolyte layer 151 and the insulating layer 118 by using the alumina slurry.
When this layer is formed, the reference oxygen chamber 146 and the second measurement chamber 148 are opened without forming a layer. Then, a porous slurry to be a porous body 147 is printed on the bottom of the opening to be the reference oxygen chamber 146. Further, carbon paste is printed as a sublimation agent on the upper surface of the porous slurry and the opening serving as the second measurement chamber 148.

Next, the unfired solid electrolyte sheet to be the solid electrolyte layer 141 is embedded in the through hole corresponding to the solid electrolyte layer 141 in the unfired insulating sheet to be the ceramic layer 116.
Next, a through hole serving as an introduction path 141a for connecting the first measurement chamber 121 and the second measurement chamber 148 is formed in the unfired solid electrolyte sheet to be the solid electrolyte layer 141. The through hole is filled with carbon paste.

Then, an electrode pattern to be the detection electrode 142 and a lead pattern to be the lead portion 142a are formed on the upper surface of the unfired insulating sheet to be the ceramic layer 116. On the other hand, an electrode pattern serving as the reference electrode 143 and a lead pattern serving as the lead portion 143a are formed on the lower surface of the unfired insulating sheet serving as the ceramic layer 116.

Next, an unfired insulating sheet to be the ceramic layer 116 is laminated on the upper surface of the layer to be the insulating layer 117.
Further, the layer to be the insulating layer 115 is printed on the upper surface of the unfired insulating sheet to be the ceramic layer 116 using the alumina slurry. In this layer, a first opening is provided at a position where the diffusion resistor 122 is formed, and a second opening is also provided at a position where the first measurement chamber 121 is formed. Then, a porous slurry to be a diffusion resistor 122 is printed on the first opening. In addition, carbon paste is printed on the second opening that becomes the first measurement chamber 121. The first opening and the second opening are connected so that the gas can flow.

Next, the unfired solid electrolyte sheet to be the solid electrolyte layer 131 is embedded in the through holes corresponding to the solid electrolyte layer 131 in the unfired insulating sheet to be the ceramic layer 114.
Then, an electrode pattern to be the pumping electrode 133 and a lead pattern to be the lead portion 133a are formed on the upper surface of the unfired insulating sheet to be the ceramic layer 114. On the other hand, an electrode pattern to be the pumping electrode 132 and a lead pattern to be the lead portion 132a are formed on the lower surface of the unfired insulating sheet to be the ceramic layer 114.

Next, an unfired insulating sheet to be the ceramic layer 114 is laminated on the surface of the layer to be the insulating layer 115. Further, the unfired insulating sheet to be the insulating layer 113 is laminated on the upper surface of the unfired insulating sheet to be the ceramic layer 114. In the unfired insulating sheet serving as the insulating layer 113, the porous slurry is printed in advance in the through holes corresponding to the porous body 134. Further, on the upper surface of the unfired insulating sheet to be the insulating layer 113, metallized ink is used to print the shapes of the electrode pads 36a, 36b, and 36c.

By laminating each layer in this way, an unfired laminate is formed. Then, by pressurizing this uncrimped laminate at 1 MPa, a crimped molded body is obtained. Then, the molded body obtained by pressurization is cut to a predetermined size to obtain a plurality of (for example, 10) unfired laminates having the same size as the gas sensor element 3. Then, the unfired laminate is decalcified and further fired at a firing temperature of 1500 ° C. for 1 hour to obtain a gas sensor element 3.

As shown in FIG. 4, electrode pads 37a, 37b, and 37c are formed on the lower surface of the insulating layer 120.
The electrode pads 37a, 37b, and 37c each include a through-hole connecting portion Ch connected to the through-hole conductor and a terminal connecting portion Ct connected to the connection terminal 8. The through-hole connection portion Ch is formed in a substantially circular shape. The terminal connection portion Ct is formed in a substantially rectangular shape. The through-hole connection portion Ch is connected to the terminal connection portion Ct so as to be arranged on the FE on the tip side of the terminal connection portion Ct.

The electrode pad 37a is arranged on the center line CL1 set so as to bisect the lower surface of the insulating layer 120 along the axial direction DA. The electrode pads 37b and 37c are arranged on the tip side FE with respect to the electrode pads 37a. The electrode pads 37b and the electrode pads 37c are arranged on one side and the other side of the center line CL1, respectively.

The lead portion 152a and the lead portion 153a are arranged on one side and the other side, respectively, with the center line CL2 set to bisect the upper surface of the insulating layer 118 along the axial direction DA. The lead portion 153a is arranged so as to be the rear end side BE from the electrode pad 37b on the other side of the center line CL2 from the pumping electrode 153 toward the end portion of the rear end side BE along the axial direction DA. It extends to the through hole H11.

On the lower surface of the insulating layer 119, a through hole H12 is arranged on one side of the center line CL3 set to bisect the lower surface of the insulating layer 119 along the axial direction DA. The through hole H12 is arranged so as to be on the rear end side BE with respect to the electrode pad 37b. Further, on the lower surface of the insulating layer 119, a connection pad PD is formed at a position facing the through hole H13 when the insulating layer 119 and the insulating layer 120 are laminated. Further, on the lower surface of the insulating layer 119, a connecting portion CN extending from the through hole H12 toward the connecting pad PD and electrically connected to the connecting pad PD is formed.

The lead portion 162 and the lead portion 163 of the heater 160 are arranged on one side and the other side, respectively, with a center line CL4 set to bisect the upper surface of the insulating layer 120 along the axial direction DA. .. On the upper surface of the insulating layer 120, a through hole H13 arranged so as to face the through-hole connection portion Ch of the electrode pad 37a and a through hole H14 arranged so as to face the through-hole connection portion Ch of the electrode pad 37b. And a through hole H15 arranged so as to face the through-hole connection portion Ch of the electrode pad 37c. The lead portion 162 and the lead portion 163 extend along the axial direction DA to the through hole H14 and the through hole H15, respectively. As shown in FIG. 4, the lead portion 162, the lead portion 163, the lead portion 152a, and the lead portion 153a extend along the longitudinal direction of the gas sensor element 3 without bending. Further, the widths of the lead portion 162 and the lead portion 163 are wider than the widths of the lead portion 152a and the lead portion 153a.

The gas sensor element 3 configured in this way has a first measuring chamber 121, a first pumping cell 130, a second pumping cell 150, and a heater 160, and is formed in a long plate shape. A unit 31 is provided.

Exhaust gas is introduced into the first measurement chamber 121. The first pumping cell 130 has an oxygen ion conductive solid electrolyte layer 131 and a pair of pumping electrodes 132 and 133 formed on the upper surface and the lower surface of the solid electrolyte layer 131. The first pumping cell 130 pumps or pumps oxygen in the exhaust gas introduced into the first measuring chamber 121 by passing a first pumping current Ip1 between the pair of pumping electrodes 132 and 133.

The second pumping cell 150 has an oxygen ion conductive solid electrolyte layer 151 and a pair of pumping electrodes 152 and 153 formed on the solid electrolyte layer 151. In the second pumping cell 150, the second pumping current Ip2 whose value changes according to the concentration of nitrogen oxides contained in the exhaust gas whose oxygen concentration is adjusted in the first measuring chamber 121 in the first pumping cell 130 It flows between the pair of pumping electrodes 152, 153.

The heater 160 has a heat generating resistor 161 and a pair of lead portions 162, 163 connected to both ends of the heat generating resistor 161 to heat the first pumping cell 130 and the second pumping cell 150.

The element main body 31 includes electrode pads 37a, 37b, and 37c formed on the lower surface (hereinafter, pad forming surface) of the insulating layer 120. The electrode pad 37a is arranged on the pad forming surface so as to be farther from the first pumping cell 130 and the second pumping cell 150 than the electrode pads 37b and 37c.

The element main body 31 includes an insulating layer 120 having a pad forming surface, and an insulating layer 119 laminated on the insulating layer 120 on a surface opposite to the pad forming surface. The electrode pad 37a is provided through a through hole H13 penetrating the insulating layer 120, a connection pad PD, a connecting portion CN, a through hole H12 penetrating the insulating layer 119, and a through hole H11 penetrating the insulating layer 118. , Electrically connected to the pumping electrode 153.

The through hole H12 is arranged so that the electrode pad 37a and the through hole H13 are not located on the straight line SDL (hereinafter, the stacking direction straight line SDL) passing through the through hole H12 along the stacking direction SD. The stacking direction straight line SDL is shown in FIG.

The through hole H12 is arranged on the stacking direction straight line SDL so that the straight line passing through the through hole H13 is not located along the longitudinal direction (that is, the axial direction DA) of the pad forming surface. The rectangular region R1 shown in FIG. 4 is a region formed by a set of straight lines passing through the through hole H13 along the longitudinal direction of the pad forming surface.

The through hole H12 is arranged so that either one of the rectangular region R2 and the region R3 shown in FIG. 4 is located on the stacking direction straight line SDL. The regions R2 and R3 are regions on the pad forming surface on the opposite sides of the electrode pads 37b and 37c from where the first pumping cell 130 and the second pumping cell 150 are arranged, respectively.

As a result, in the gas sensor element 3, the through hole H12 is not arranged on each straight line passing through the electrode pads 37a, 37b, 37c along the stacking direction SD (that is, directly below the electrode pads 37a, 37b, 37c). Therefore, the gas sensor element 3 can suppress the occurrence of dents in the electrode pads 37a, 37b, and 37c.

Further, according to the configuration of the present embodiment, in order to reduce the size of the gas sensor element 3, the lead portion 162, the lead portion 163, the lead portion 152a, and the lead portion 153a cannot be bent and extend along the longitudinal direction of the gas sensor element. Even if it has a shape, it is possible to suppress the occurrence of dents in the electrode pads. Further, even if the electrode pad is provided on the same surface as the electrode pad that conducts with the lead portion of the heater having a relatively thick lead width, the occurrence of dents can be suppressed.

The first measurement chamber 121 corresponds to the measurement chamber, the solid electrolyte layer 131 corresponds to the first solid electrolyte body, and the pumping electrodes 132 and 133 correspond to the first electrode.
Further, the solid electrolyte layer 151 corresponds to the second solid electrolyte body, and the pumping electrodes 152 and 153 correspond to the second electrode.

Further, the electrode pad 37a corresponds to the first electrode pad, the electrode pad 37b corresponds to the second electrode pad, the electrode pad 37c corresponds to the third electrode pad, and the insulating layer 120 corresponds to the first insulating layer. The insulating layer 119 corresponds to the second insulating layer.

Further, the through hole H13 corresponds to the first through hole, the through hole H12 corresponds to the second through hole, the region R2 corresponds to the first opposite region, and the region R3 corresponds to the second opposite region.
Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and can be implemented in various modifications.

For example, in the above embodiment, the electrode pads 37b, the electrode pads 37a, and the electrode pads 37c are arranged in this order from left to right in FIG. 4 on the lower surface of the insulating layer 120, but the electrode pads 37a, 37b, The arrangement of 37c is not limited to this. For example, the electrode pads 37a, the electrode pads 37b, and the electrode pads 37c may be arranged in this order from left to right in FIG. 4, or the electrode pads 37b, the electrode pads 37c, and the electrode pads 37a may be arranged in this order. Good. Further, the electrode pads are not limited to those arranged three on each of the front surface and the back surface of the element main body 31 as in the present embodiment.

The function of one component in each of the above embodiments may be shared by a plurality of components, or the function of the plurality of components may be exerted by one component. In addition, a part of the configuration of each of the above embodiments may be omitted. In addition, at least a part of the configuration of each of the above embodiments may be added or replaced with respect to the other configurations of the above embodiment. It should be noted that all aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

1 ... Gas sensor, 37a, 37b, 37c ... Electrode pad, 119, 120 ... Insulation layer, 121 ... First measurement chamber, 130 ... First pumping cell, 131 ... Solid electrolyte layer, 132, 133 ... Pumping electrode, 150 ... First 2 pumping cell, 151 ... solid electrolyte layer, 152, 153 ... pumping electrode, 160 ... heater, 161 ... heat generating resistor, 162, 163 ... lead part, H12, H13 ... through hole

Claims (2)

The measurement room where the gas to be measured is introduced and
By having a first solid electrolyte body having oxygen ion conductivity and a pair of first electrodes formed on the first solid electrolyte body, and passing a first pumping current between the pair of first electrodes. , A first pumping cell that pumps or pumps oxygen in the gas to be measured introduced into the measuring chamber.
It has an oxygen ion conductive second solid electrolyte body and a pair of second electrodes formed on the second solid electrolyte body, and the oxygen concentration in the measurement chamber is adjusted by the first pumping cell. A second pumping cell in which a second pumping current whose value changes according to the concentration of the specific gas contained in the gas to be measured flows between the pair of the second electrodes.
It has a heat-generating resistor and a pair of lead portions connected to both ends of the heat-generating resistor, and has a heater for heating the first pumping cell and the second pumping cell to form a long plate. A gas sensor element provided with a formed element body,
The element main body includes a first electrode pad, a second electrode pad, and a third electrode pad formed on the pad forming surface with either the front surface or the back surface as a pad forming surface.
The first electrode pad is arranged on the pad forming surface so as to be farther from the first pumping cell and the second pumping cell than the second electrode pad and the third electrode pad.
The element main body portion includes a first insulating layer having the pad forming surface and a second insulating layer laminated on the first insulating layer on a surface opposite to the pad forming surface.
The first electrode pad is at least one of a pair of the second electrodes via a first through hole penetrating the first insulating layer and a second through hole penetrating the second insulating layer. Electrically connected to
The second through hole is on a straight line in the stacking direction, which is a straight line passing through the second through hole along the stacking direction, with the direction in which the first insulating layer and the second insulating layer are laminated as the stacking direction. The first electrode pad and the first through hole are arranged so as not to be located in the same direction.
The second through hole is arranged so that the straight line passing through the first through hole is not located along the longitudinal direction of the pad forming surface on the stacking direction straight line, and
On the pad forming surface, a region opposite to the first pumping cell and the second pumping cell arranged on the second electrode pad is defined as a first opposite region, and the third electrode pad is used. The region on the opposite side of the first pumping cell and the second pumping cell from which the second pumping cell is arranged is set as the second opposite region, and the second through hole is formed on the straight line in the stacking direction and is the first opposite. A gas sensor element arranged so that either a region or the second opposite region is located. The gas sensor element according to claim 1, wherein a through hole is not arranged in a straight line passing through the first electrode pad along the stacking direction in the second insulating layer.