JP2018124085A - Gas sensor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of a recess of an electrode pad.SOLUTION: An element body part includes electrode pads 37a, 37b and 37c formed on an inferior surface (hereinafter referred to as pad formation surface) of an isolation layer 120. An open hole H12 penetrating an isolation layer 119 is arranged in such a manner that the electrode pat 37a and an open hole H13 penetrating the isolation layer 120 are not positioned on a straight line (hereinafter referred to as lamination direction straight line) passing through the open hole H12 along the lamination direction. The open hole H12 is arranged in such a manner that a straight line passing through the open hole H13 along the longer direction of the pad formation surface is not positioned on the lamination direction straight line. The open hole H12 is arranged in such a manner that either a region R2 or a region R3 is positioned on the lamination direction straight line. The regions R2 and R3 are regions on the opposite side to a place where first and second pumping cells are arranged sandwiching the electrode pads 37b and 37c on the pad formation surface.SELECTED DRAWING: Figure 4

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, for example, nitrogen oxide (hereinafter referred to as NOx concentration) contained in a gas to be measured 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 predetermined by the first pumping cell including the solid electrolyte body and the pair of first electrodes. Is adjusted to the density. Then, the gas to be measured whose oxygen concentration is adjusted flows from the first measurement chamber into the second measurement chamber, and NOx in the gas to be measured in the second pumping cell composed of the solid electrolyte body 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 an 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 a long plate shape, and has one electrode pad (hereinafter referred to as a second pumping current) for detecting the second pumping current on either the front surface or the back surface. , A second pumping current electrode pad) and two electrode pads for energizing the heater.

JP 2010-266429 A

  When a through hole formed in the gas sensor element for electrically connecting the second electrode and the second pumping current electrode pad is disposed immediately below the second pumping current electrode pad, The surface of the pumping current electrode pad may be recessed. If the surface of the second pumping current electrode pad is recessed, there is a high possibility that a contact failure between the second pumping current electrode pad and the connection terminal connected to the second pumping current electrode pad will occur. End up.

  An object of this indication is to suppress generation | occurrence | production of the dent of an electrode pad.

One aspect of the present disclosure is a gas sensor element including a measurement chamber, a first pumping cell, a second pumping cell, and a heater, and an element main body formed in a long plate shape.
A gas to be measured is introduced into the measurement chamber. The first pumping cell includes 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 between the pair of first electrodes. The oxygen in the gas to be measured introduced into the measurement chamber is pumped out or pumped in.

  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 increased 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 heating resistor and a pair of lead portions connected to both ends of the heating resistor, and heats the first pumping cell and the second pumping cell.
The element body includes a first electrode pad, a second electrode pad, and a third electrode pad that are 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 disposed 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 stacked on the first insulating layer on a surface opposite to the pad forming surface. The first electrode pad is electrically connected to any one of the pair of second electrodes through at least a first through hole penetrating the first insulating layer and a second through hole penetrating the second insulating layer. Connected.

  The second through hole has a first electrode on a stacking direction straight line that is a straight line passing through the second through hole along the stacking direction, with the stacking direction being the direction in which the first insulating layer and the second insulating layer are stacked. It arrange | positions so that a pad and a 1st through-hole may not be located. Further, the second through hole is arranged on the straight line in the stacking direction so that a straight line passing through the first through hole is not located along the longitudinal direction of the pad forming surface. 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 side where the first pumping cell and the second pumping cell are disposed with the second electrode pad interposed therebetween. The second opposite region is a region on the pad forming surface opposite to the side where the first pumping cell and the second pumping cell are disposed 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 third electrode pad along the stacking direction on each straight line (that is, the first electrode pad and the second electrode pad). In addition, the second through hole is not disposed immediately below the third electrode pad. For this reason, the gas sensor element of this indication can control generating of the dent of the 1st electrode pad, the 2nd electrode pad, and the 3rd electrode pad.

1 is a cross-sectional view of a NOx sensor 1. FIG. FIG. 3 is a diagram showing a schematic configuration of an element body 31 and a sensor control device 170. 3 is an exploded perspective view of an element body 31. FIG. It is a figure which shows the edge part of the rear end side BE in the upper surface of the insulating layer 118, the lower surface of the insulating layer 119, and the upper surface and lower surface of the insulating layer 120.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
The NOx sensor 1 of this 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 metal shell 2, a gas sensor element 3, a holding unit 4, a protector 5, an outer cylinder 6, a plurality of lead wires 7, 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 metal shell 2 is a member formed in a cylindrical shape with a heat-resistant metal such as stainless steel. The metal shell 2 includes a main body portion 21 and an attachment 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 referred to as 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 an attachment screw hole provided in the exhaust pipe in order to attach the gas sensor 1 to the exhaust pipe of the internal combustion engine. The main body 21 includes a through hole 21b that penetrates along the axial direction DA. A step portion 21c is formed on the inner peripheral wall of the through hole 21b so as to protrude radially inward.

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

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

The holding unit 4 includes a ceramic holder 41, talc rings 42 and 43, a ceramic sleeve 44, a packing 45, and a metal holder 46.
Inside the through-hole 21b of the metal shell 2, there are a ceramic holder 41 that is a cylindrical member surrounding the circumference of the gas sensor element 3 in order from the front end side FE to the rear end side BE, and a powder-filled layer. The talc rings 42 and 43 and the ceramic sleeve 44 are laminated.

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

  The protector 5 is a metal member formed in a cylindrical shape so as to cover the end portion of the front end side FE of the gas sensor element 3 protruding from the metal shell 2. A plurality of gas intake holes are formed in the protector 5. The protector 5 is joined to the outer periphery of the front end side FE of the metal shell 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 disposed on the outer side, and a bottomed cylindrical inner protector 52 is disposed on the inner side.

  The outer cylinder 6 is a metal member formed in a cylindrical 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 metal shell 2 located on the rear end side BE from the attachment portion 22 is fitted into the opening 6a at the end of the front end side FE.

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

The plurality of connection terminals 8 are provided corresponding to each of the plurality of lead wires 7 and attached to one end of the corresponding lead wire 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. The separators 91 and 92 are stacked in order from the front end side FE to the rear end side BE. It is arranged in the cylinder 6.

  Inside the separator 91, a space capable of accommodating the plurality of connection terminals 8 and a part of the rear end BE of the element main body 31 is formed. The separator 91 maintains the state in which the rear end BE of the plurality of connection terminals 8 protrudes from the rear end BE of the separator 91 and the plurality of connection terminals 8 are not in contact with each other. Accommodate. The separator 91 maintains a state in which the plurality of connection terminals 8 are in contact with the electrode pads 36a, 36b, 36c, 37a, 37b, and 37c of the element main body 31, respectively. In addition, a flange 91a is formed on the outer peripheral surface of the rear end BE of the separator 91 so as to extend outward along the radial direction.

  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, and the corresponding connection terminals 8 are inserted into the plurality of through holes, respectively.

  The holding member 93 includes a main body portion 93a and a bending portion 93b. The main body 93a is a metal member formed in a cylindrical shape extending in the axial direction DA. The curved portion 93b is a member that extends from the rear end BE of the main body portion 93a and is bent into a U shape. The holding member 93 is installed so as to be positioned between the outer cylinder 6 and the separator 91 on the front end side FE from the flange portion 91a. Thereby, the main body portion 93a comes into contact with the inner peripheral surface of the outer cylinder 6, and the curved portion 93b comes into a state of pressing the separator 91 toward the inside thereof. For this reason, the separator 91 is held in the outer cylinder 6 by the holding member 93.

  The separator 92 is in a state where the end of the front end FE and the end of the rear end BE are pressed against the separator 91 and the grommet 10, respectively. Thereby, 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. Grommet 10 is formed with a plurality of through holes penetrating along axial direction DA. The plurality of through holes are provided corresponding to each of the plurality of lead wires 7, and the corresponding lead wires 7 are inserted into the plurality of through holes, respectively.

  The grommet 10 is disposed inside the opening 6 b at the end of the rear end BE in the outer cylinder 6 and is crimped in the radial direction via the outer cylinder 6. Thereby, the opening part 6b of the edge part of the rear end side BE in the outer cylinder 6 is obstruct | occluded.

  As shown in FIG. 2, the element main body 31 of the gas sensor element 3 includes 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 stacked. The layers are sequentially stacked 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 body 31 is exhausted from the outside to the inside of the first measurement chamber 121 via the diffusion resistor 122 disposed 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 diffused resistor 122 is not shown in FIG. 2, but is shown in FIG.

The element 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 formed mainly of zirconia having oxygen ion conductivity. A portion of the ceramic layer 114 in the region in contact with the first measurement chamber 121 is removed, and a solid electrolyte layer 131 is filled instead of the ceramic layer 114.

  The pumping electrodes 132 and 133 are formed mainly of platinum. The pumping electrode 132 is disposed on the surface that contacts the first measurement chamber 121 in the solid electrolyte layer 131. The pumping electrode 133 is disposed on the surface of the solid electrolyte layer 131 on the side opposite to the pumping electrode 132 with the solid electrolyte layer 131 interposed therebetween. The insulating layer 113 in the region where the pumping electrode 133 is disposed and the surrounding region is removed, and the porous body 134 is filled instead 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 formed mainly of zirconia having oxygen ion conductivity. A portion of the ceramic layer 116 in the region on the rear end side (that is, the right side in FIG. 2) from the solid electrolyte layer 131 is removed, and the solid electrolyte layer 141 is filled instead of the ceramic layer 116.

  The detection electrode 142 and the reference electrode 143 are formed mainly of platinum. The detection electrode 142 is disposed on the surface in contact with the first measurement chamber 121 in the solid electrolyte layer 141. The reference electrode 143 is disposed 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 disposed and the surrounding region.

  The element body 31 includes a second measurement chamber 148. The second measurement chamber 148 is formed through 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 exhaust gas discharged from the first measurement chamber 121 into the second measurement chamber 148.

The element 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 disposed 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 area. The insulating layer 118 is disposed 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 disposed on the surface in contact with the second measurement chamber 148 in the solid electrolyte layer 151. The pumping electrode 153 is disposed on the surface of the solid electrolyte layer 151 on the side opposite to the reference electrode 143 across the reference oxygen chamber 146. A porous body 147 is disposed inside the reference oxygen chamber 146 so as to cover the pumping electrode 153.

  The element body 31 includes a heater 160. The heater 160 is a heating resistor that is formed mainly of platinum and generates heat when energized. The heater 160 is disposed 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 body 31 and calculates the NOx concentration in the exhaust gas based on the detection result of the element 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 the 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.

  The pumping electrode 132, the detection electrode 142, and the pumping electrode 152 are connected to a 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 supplies the first pumping current Ip1 by applying the voltage Vp1 between the pumping electrode 132 and the pumping electrode 133, 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. 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 also controls the oxygen concentration in the first measurement chamber 121. , And adjust to a predetermined value that does not decompose NOx.

  The Icp supply circuit 184 flows a weak current Icp 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. Thereby, 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. Oxygen ions obtained by this dissociation move through the solid electrolyte layer 151 between the pumping electrode 152 and the pumping electrode 153, whereby a second pumping current Ip2 flows. The Ip2 detection circuit 186 detects the second pumping current Ip2.

  The heater driving circuit 187 drives the heater 160 by applying a positive voltage for energizing the heater to one end of the heater 160 that is a heating 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 36 a, 36 b, and 36 c are formed at the end of the rear end 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 BE on the lower surface of the insulating layer 120.

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

  On the upper surface of the ceramic layer 116, a lead portion 142a connected to the detection electrode 142 at the front end side FE and extending toward the rear end side BE is formed. On the lower surface of the ceramic layer 116, a lead portion 143a connected to the reference electrode 143 at the front end side FE and extending 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 at the front end side FE and extending toward the rear end side BE, and connected to the pumping electrode 153 at the front end side FE toward the rear end side BE. An extending lead portion 153a is formed.

The heater 160 includes a heating resistor 161, a lead portion 162 connected to one end of the heating resistor 161, and 163 connected to the other end of the heating 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 through-hole conductors L4 and L5 and a connection portion CN described later.
The electrode pad 37b is connected to the lead portion 162 by a through-hole conductor L6. The electrode pad 37c is connected to the lead part 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 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 BE in the insulating layers 113 and 115, respectively. The through holes H3 and H5 are formed at the end portions of the rear end BE in 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 end portions of the rear end side BE in the insulating layers 113, 115, and 117, respectively. The through holes H7 and H9 are formed at the end portions of the rear end BE in the ceramic layers 114 and 116, respectively.

  The through-hole conductor L4 is created by forming a conductor on the inner surface 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 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.
The through-hole conductors L6 and L7 are created by forming conductors on the inner surfaces of the through holes H14 and H15, respectively. The through holes H <b> 14 and H <b> 15 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 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.

  When each cell 130, 140, 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. Accordingly, 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 measurement chamber 121 is transferred. Pump in and out.

  The sensor control device 170 supplies the first pumping current Ip1 that flows 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 a 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 the oxygen concentration in the reference oxygen chamber 146 as a reference. By this control, the oxygen concentration in the first measurement chamber 121 is adjusted to the extent that NOx is not decomposed.

The exhaust gas whose oxygen concentration is 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 is decomposed into oxygen and nitrogen gas. Thereby, NOx in the exhaust gas is decomposed into nitrogen and oxygen. A second pumping current Ip2 flows through the second pumping cell 150 so that oxygen generated by the decomposition of NOx is pumped out of the second measurement 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 for manufacturing the gas sensor element 3 will be described.
As shown in FIG. 3, an unsintered insulating sheet serving as the ceramic layers 114 and 116 of the element body 31, an unsintered solid electrolyte sheet serving as the solid electrolyte layers 131, 141, and 151, and an unsintered insulating layer sheet serving as the insulating layer 113. Then, an unfired insulating sheet to be the insulating layers 119 and 120 is manufactured.

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

  Then, rectangular through holes corresponding to the planar shape of the unfired solid electrolyte sheets of the solid electrolyte layers 131 and 141 are formed in the unfired insulating sheets to be the ceramic layers 114 and 116. In addition, 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, etc. are added to the ceramic powder mainly composed of zirconia, and a mixed solvent is further added. To produce a slurry. And this slurry is made into a sheet form by a doctor blade method, and an unbaked solid electrolyte sheet is produced by volatilizing the mixed solvent. Then, this unfired solid electrolyte sheet is cut into a rectangular shape corresponding to the solid electrolyte layers 131, 141, 151.

  Further, as a material to become the insulating layers 115, 117, and 118 after firing, a butyral resin and dibutyl phthalate are added to 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 material that becomes the diffusion resistor 122, the porous material 134, and the porous material 147 after firing, 100% by mass of alumina powder, a heat-dissipated material (for example, carbon) and a plasticizer are added. A porous slurry dispersed by wet mixing is prepared. The plasticizer has a butyral resin and DBP.

  Next, a heater pattern including a heating 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 containing ceramic (for example, alumina) is manufactured, and this platinum paste is printed to form a heater pattern.

Further, the pattern of the electrode pads 37a, 37b, and 37c is printed on the lower surface of the unbaked insulating sheet that becomes the insulating layer 120, for example, using a metallized ink such as platinum.
Further, holes that become through holes H13, H14, and H15 are formed in the unfired insulating sheet that becomes the insulating layer 120, and metallized ink is applied to the inner peripheral surface of these holes.

In addition, since the formation method of the other through-holes H1-H12 and the coating method of metallized ink are the same, below, the description regarding the other through-holes H1-H12 is abbreviate | omitted.
Next, an 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 the solid electrolyte layer 151 is laminated on the upper surface of the unfired insulation 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 alumina slurry. Thereby, the insulating layer 118 is formed so as to fill a step formed between the upper surface of the solid electrolyte layer 151 and the upper surface of the insulating layer 119.

  Next, 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 using metallized ink. Moreover, the lead pattern used as the lead parts 152a and 153a is printed using platinum paste. The material of the electrode pattern and the lead pattern is the same for the unfired insulating sheets that become the ceramic layers 114 and 116.

Further, a 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 using alumina slurry.
When forming this layer, an opening is formed in the portion that becomes the reference oxygen chamber 146 and the second measurement chamber 148 without forming the layer. And the porous slurry used as the porous body 147 is printed on the bottom part of the opening used as 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 holes 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 141 a for connecting the first measurement chamber 121 and the second measurement chamber 148 is opened in the unfired solid electrolyte sheet serving as the solid electrolyte layer 141. This 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 unsintered insulating sheet to be the ceramic layer 116. On the other hand, an electrode pattern to be the reference electrode 143 and a lead pattern to be the lead portion 143a are formed on the lower surface of the unfired insulating sheet to be 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 that becomes the insulating layer 115 is printed on the upper surface of the unfired insulating sheet that becomes the ceramic layer 116 using 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. And the porous slurry used as the diffusion resistor 122 is printed in the 1st opening. In addition, a carbon paste is printed in 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.
And the electrode pattern used as the pumping electrode 133 and the lead pattern used as the lead part 133a are formed in the upper surface of the unbaking insulating sheet used as the ceramic layer 114. FIG. 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 that becomes the ceramic layer 114 is laminated on the surface of the layer that becomes the insulating layer 115. Further, an unsintered insulating sheet to be the insulating layer 113 is laminated on the upper surface of the unsintered insulating sheet to be the ceramic layer 114. Note that porous slurry is printed in advance in the through holes corresponding to the porous body 134 in the unfired insulating sheet to be the insulating layer 113. In addition, on the upper surface of the unbaked insulating sheet to be the insulating layer 113, it is printed in the shape of the electrode pads 36a, 36b, 36c using metallized ink.

  Thus, an unbaked laminated body is formed by laminating each layer. Then, the uncompressed laminate is pressed at 1 MPa to obtain a compacted product. Thereafter, the molded body obtained by pressurization is cut into a predetermined size, thereby obtaining a plurality (for example, 10) of unfired laminated bodies having the same size as the gas sensor element 3. And this unbaked laminated body is resin-removed, and also this baking is further carried out at a baking temperature of 1500 ° C. for 1 hour to obtain the gas sensor element 3.

As shown in FIG. 4, electrode pads 37 a, 37 b, and 37 c are formed on the lower surface of the insulating layer 120.
Each of the electrode pads 37a, 37b, and 37c includes a through-hole connection portion Ch connected to the through-hole conductor and a terminal connection 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 disposed on the front end side FE with respect to the terminal connection portion Ct.

  The electrode pad 37a is disposed 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 disposed on the front end side FE with respect to the electrode pad 37a. The electrode pad 37b and the electrode pad 37c are respectively disposed on one side and the other side with the center line CL1 interposed therebetween.

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

  On the lower surface of the insulating layer 119, a through hole H12 is disposed on one side across a center line CL3 set so as to bisect the lower surface of the insulating layer 119 along the axial direction DA. The through hole H12 is disposed 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, when the insulating layer 119 and the insulating layer 120 are laminated, the connection pad PD is formed at a position facing the through hole H13. Further, a connection portion CN that extends from the through hole H12 toward the connection pad PD and is electrically connected to the connection pad PD is formed on the lower surface of the insulating layer 119.

  The lead portion 162 and the lead portion 163 of the heater 160 are respectively disposed on one side and the other side with a center line CL4 set so as 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 disposed so as to face the through hole connection portion Ch of the electrode pad 37a, and a through hole H14 disposed so as to face the through hole connection portion Ch of the electrode pad 37b. And a through hole H15 disposed so as to face the through hole connecting portion Ch of the electrode pad 37c. The lead part 162 and the lead part 163 extend to the through hole H14 and the through hole H15, respectively, along the axial direction DA. 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 being bent. The widths of the lead part 162 and the lead part 163 are larger than the widths of the lead part 152a and the lead part 153a.

  The gas sensor element 3 configured as described above includes a first measurement chamber 121, a first pumping cell 130, a second pumping cell 150, and a heater 160, and an element body formed in a long plate shape. The unit 31 is provided.

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

  The second pumping cell 150 includes 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 in accordance with the concentration of nitrogen oxides contained in the exhaust gas in which the oxygen concentration in the first measurement chamber 121 is adjusted in the first pumping cell 130 is generated. It flows between the pair of pumping electrodes 152, 153.

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

  The element body 31 includes electrode pads 37a, 37b, and 37c formed on the lower surface (hereinafter referred to as a pad forming surface) of the insulating layer 120. The electrode pad 37a is disposed 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 stacked on the insulating layer 120 on the surface opposite to the pad forming surface. The electrode pad 37a passes through the through hole H13 that penetrates the insulating layer 120, the connection pad PD, the connection portion CN, the through hole H12 that penetrates the insulating layer 119, and the through hole H11 that penetrates 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 positioned on a straight line SDL (hereinafter, referred to as a “stack 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 a straight line passing through the through hole H13 is not positioned along the longitudinal direction of the pad forming surface (that is, the axial direction DA). Note that the rectangular region R1 shown in FIG. 4 is a region formed by a set of straight lines passing through the through holes 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 positioned on the stacking direction straight line SDL. Regions R2 and R3 are regions opposite to where the first pumping cell 130 and the second pumping cell 150 are disposed across the electrode pads 37b and 37c on the pad formation surface, respectively.

  Thereby, in the gas sensor element 3, the through hole H12 is not disposed on each straight line passing through the electrode pads 37a, 37b, and 37c along the stacking direction SD (that is, directly below the electrode pads 37a, 37b, and 37c). For this reason, the gas sensor element 3 can suppress generation | occurrence | production of the dent of electrode pad 37a, 37b, 37c.

  Furthermore, by adopting the configuration of the present embodiment, in order to reduce the size of the gas sensor element 3, the lead part 162, the lead part 163, the lead part 152a, and the lead part 153a cannot be bent and extend along the longitudinal direction of the gas sensor element. Even if it is a shape, generation | occurrence | production of the dent of an electrode pad can be suppressed. Moreover, even if the electrode pad is provided on the same surface as the electrode pad that is electrically connected to the lead portion of the heater having a relatively large lead width, the occurrence of a dent can be suppressed.

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

  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, the insulating layer 120 corresponds to the first insulating layer, The insulating layer 119 corresponds to a second insulating layer.

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.
As mentioned above, although one embodiment of this indication was described, this indication is not limited to the above-mentioned embodiment, and can carry out various modifications.

  For example, in the above-described embodiment, the electrode pad 37b, the electrode pad 37a, and the electrode pad 37c are arranged in this order from the left to the 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 number of electrode pads is not limited to that in which three electrode pads are arranged on both the front and back surfaces of the element main body 31 as in the present embodiment.

  The functions of one component in each of the above embodiments may be shared by a plurality of components, or the functions of a plurality of components may be exhibited by one component. Moreover, you may abbreviate | omit a part of structure of each said embodiment. In addition, at least a part of the configuration of each of the above embodiments may be added to or replaced with the configuration of the other above embodiments. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

  DESCRIPTION OF SYMBOLS 1 ... Gas sensor, 37a, 37b, 37c ... Electrode pad, 119, 120 ... Insulating layer, 121 ... 1st measurement chamber, 130 ... 1st pumping cell, 131 ... Solid electrolyte layer, 132, 133 ... Pumping electrode, 150 ... 1st 2 pumping cells, 151 ... solid electrolyte layer, 152, 153 ... pumping electrode, 160 ... heater, 161 ... heating resistor, 162, 163 ... lead, H12, H13 ... through hole

Claims (1)

A measurement chamber into which the gas to be measured is introduced;
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 flowing between the pair of first electrodes A first pumping cell for pumping or pumping oxygen in the measurement gas introduced into the measurement chamber;
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 second electrodes;
A heating resistor and a pair of leads connected to both ends of the heating resistor, and a heater for heating the first pumping cell and the second pumping cell. A gas sensor element having a formed element body,
The element body includes a first electrode pad, a second electrode pad, and a third electrode pad formed on the pad forming surface, with either one of the front surface and the back surface being a pad forming surface.
The first electrode pad is disposed 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 body includes a first insulating layer having the pad forming surface, and a second insulating layer stacked 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 through a first through hole penetrating the first insulating layer and a second through hole penetrating the second insulating layer. Electrically connected with
The second through hole is a straight line in the stacking direction that is a straight line passing through the second through hole along the stacking direction, with the stacking direction being the direction in which the first insulating layer and the second insulating layer are stacked. Are arranged such that the first electrode pad and the first through hole are not located, and
The second through hole is arranged on the straight line in the stacking direction so that a straight line passing through the first through hole along the longitudinal direction of the pad forming surface is not located, and
On the pad forming surface, a region opposite to where the first pumping cell and the second pumping cell are disposed across the second electrode pad is defined as a first opposite region, and the third electrode pad is A region opposite to the side where the first pumping cell and the second pumping cell are disposed is a second opposite region, and the second through hole is on the straight line in the stacking direction and the first opposite A gas sensor element disposed such that one of the region and the second opposite region is located.