JP5524941B2 - Gas sensor and gas sensor manufacturing method - Google Patents

Description

  The present invention relates to a gas sensor suitably used for detecting the gas concentration of a specific gas contained in a combustion gas or exhaust gas of a combustor or an internal combustion engine, for example, and a method for manufacturing the gas sensor.

  2. Description of the Related Art Conventionally, an oxygen sensor that is mounted on an exhaust system such as an exhaust pipe of an engine and has a gas sensor element and a cylindrical metal shell that holds the gas sensor element as a gas sensor that detects the concentration of a specific gas component in the exhaust gas. It has been known. Here, in the case of an all-region air-fuel ratio sensor which is a kind of oxygen sensor, the gas sensor element includes an oxygen concentration detection cell in which a pair of electrodes are formed on the front and back surfaces of the solid electrolyte body, and the front and back surfaces of the solid electrolyte body. It has an oxygen pump cell in which a pair of electrodes are formed, and a measurement chamber is defined between the two cells. The exhaust gas enters and exits the measurement chamber through the porous portion, and the diffusion rate of the exhaust gas is adjusted in the porous portion.

On the other hand, the solid electrolyte body that constitutes the cell of the gas sensor element is generally a flat plate. However, a technology that prevents the bonding failure with the substrate has been developed by bending the solid electrolyte body to optimize the contact angle with the substrate. (For example, refer to Patent Document 1).
In addition, since the measurement chamber for introducing the exhaust gas tends to be small in conjunction with the downsizing of the gas sensor element, there is a technique in which the volume of the measurement chamber is increased by bending the solid electrolyte body to the opposite side of the measurement chamber. It has been developed (see, for example, Patent Document 2).

Japanese Patent No. 3752452 (FIG. 2) JP 2010-261727 A (FIGS. 1 and 3)

By the way, in the case of a gas sensor having an oxygen concentration detection cell and an oxygen pump cell, since the detection accuracy of the gas to be measured is high, there is a problem that if the gas diffusion rate is lowered, the responsiveness is greatly lowered. On the other hand, the gas sensors described in Patent Documents 1 and 2 adopt a configuration in which one electrode of the oxygen concentration detection cell faces the atmospheric reference chamber without providing an oxygen pump cell, so that the responsiveness is not significantly lowered. It doesn't matter. Therefore, in these gas sensors, the solid electrolyte body constituting the cell is curved so as to swell toward the atmosphere reference chamber without considering the responsiveness.
Accordingly, an object of the present invention is to provide a gas sensor and a gas sensor manufacturing method with improved responsiveness in a gas sensor having an oxygen concentration detection cell and an oxygen pump cell.

  In order to solve the above problems, a gas sensor according to the present invention includes a plate-shaped first solid electrolyte body and an oxygen concentration detection cell comprising a pair of electrodes provided on the first solid electrolyte body, and the oxygen concentration detection cell. It consists of a porous part to be laminated, a plate-like second solid electrolyte body and a pair of electrodes provided on the second solid electrolyte body, and is laminated on the oxygen concentration detection cell via the porous part. One of the pair of electrodes of the oxygen concentration detection cell and one of the pair of electrodes of the oxygen pump cell, which is partitioned by an oxygen pump cell, the oxygen concentration detection cell, the porous portion, and the oxygen pump cell A gas sensor having a measurement chamber having electrodes disposed opposite to each other, and a substantially cylindrical metal shell that holds the gas sensor element therein, the gas sensors being disposed opposite to each other. The distance between the first solid electrolyte body and the second solid electrolyte body at the electrode position is shorter than the length in the stacking direction of the first solid electrolyte body and the second solid electrolyte body at the position of the porous portion. The distance between the opposed electrodes is shorter than the length of the porous portion in the stacking direction.

  According to this gas sensor, since the distance between the electrodes arranged opposite to each other is shorter than the length of the porous portion in the stacking direction, the volume of the measurement chamber is minimized in the vicinity of the electrodes arranged opposite to each other. The responsiveness is improved by immediately reflecting the change in the atmosphere of the gas to be measured entering and exiting the measurement chamber. In addition, for example, the distance between the first solid electrolyte body and the second solid electrolyte body at the electrode positions arranged opposite to each other is set to the stacking direction of the first solid electrolyte body and the second solid electrolyte body at the position of the porous portion. The volume of the measurement chamber becomes the smallest in the vicinity of the electrodes arranged opposite to each other by increasing the thickness of the electrodes arranged opposite to each other, but in this case, the gas at each electrode is reduced. The diffusion rate is lowered and the responsiveness is lowered. Therefore, the distance between the first solid electrolyte body and the second solid electrolyte body at the electrode positions arranged opposite to each other is made shorter than the length of the porous portion in the stacking direction, so that the thickness of the electrode is not increased. The above effects can be realized.

You may make it the said 1st solid electrolyte body or the said 2nd solid electrolyte body protrude in a step shape rather than the periphery toward each other in the electrode position arrange | positioned facing.
This gas sensor is preferable because the electrodes arranged opposite to each other are flat, and the distance between electrodes (that is, responsiveness) does not change depending on the position of the electrodes.

The first solid electrolyte body and the second solid electrolyte body are curved in the stacking direction so that the first solid electrolyte body or the second solid electrolyte body approaches each other at the opposed electrode positions. It may be.
Even with this gas sensor, the volume of the measurement chamber can be minimized in the vicinity of the electrodes arranged opposite to each other without increasing the thickness of the electrodes, and the responsiveness can be improved.

  The gas sensor manufacturing method of the present invention includes a plate-like first solid electrolyte body and an oxygen concentration detection cell comprising a pair of electrodes provided on the first solid electrolyte body, and a porous layer stacked on the oxygen concentration detection cell. An oxygen pump cell comprising a mass part, a plate-like second solid electrolyte body and a pair of electrodes provided on the second solid electrolyte body, and stacked on the oxygen concentration detection cell via the porous part, The oxygen concentration detection cell, the porous portion, and the oxygen pump cell are partitioned, and one electrode of the pair of electrodes of the oxygen concentration detection cell and one electrode of the pair of electrodes of the oxygen pump cell face each other. A gas sensor manufacturing method comprising: a gas sensor element having a measurement chamber disposed in a gas chamber; and a substantially cylindrical metal shell that holds the gas sensor element therein, wherein the oxygen concentration detection before firing is performed. Between the unsintered oxygen concentration detection cell, which is a catalyst, and the unsintered oxygen pump cell, which is the oxygen pump cell before firing, at a predetermined position communicating with the site serving as the measurement chamber. A porous paste is applied, and a burnable paste mainly composed of carbon is applied to a site serving as the measurement chamber in less than a volume serving as the measurement chamber, and the unsintered oxygen concentration detection cell and the unsintered oxygen pump cell are provided. Is pressed in the laminating direction, and the whole is fired.

  According to the present invention, the responsiveness can be improved in the gas sensors each having the oxygen concentration detection cell and the oxygen pump cell.

It is sectional drawing which follows the axial direction of the gas sensor (oxygen sensor) which concerns on embodiment of this invention. It is a model exploded perspective view of a gas sensor element. It is sectional drawing which follows the AA line of FIG. It is a figure which shows the modification of FIG. It is process drawing which shows an example of the manufacturing method of a gas sensor (gas sensor element).

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a cross-sectional view taken along the longitudinal direction (axis L direction) of a gas sensor (oxygen sensor) 1 according to an embodiment of the present invention, and FIG. 2 is a schematic exploded perspective view of a gas sensor element 100 (detection element unit 300 and heater unit 200). FIG. 3 is a cross-sectional view orthogonal to the direction of the axis L of the gas sensor element 100.
As viewed in the direction of the axis L, the protector 24 side is the “front end” and the rubber cap 52 side is the “rear end”.

  As shown in FIG. 1, the gas sensor 1 includes a detection element unit 300, a gas sensor element 100 including a heater unit 200 stacked on the detection element unit 300, a metal shell 30 that holds the gas sensor element 100 therein, and a metal shell 30. And a protector 24 and the like attached to the front end of the head. The gas sensor element 100 is arranged so as to extend in the direction of the axis L.

  As shown in FIG. 2, the heater unit 200 includes a first base 101 and a second base 103 mainly composed of alumina, and a heating element 102 mainly composed of platinum sandwiched between the first base 101 and the second base 103. have. The heating element 102 has a heating part 102a located on the tip side and a pair of heater lead parts 102b extending from the heating part 102a along the longitudinal direction of the first base 101. And the terminal of the heater lead part 102b is electrically connected to the heater part side pad 120 through a conductor formed in the heater part side through hole 101a provided in the first base 101. That is, the heater unit 200 is provided with a heater (heating element 102) that generates heat by energization on an insulating ceramic body in which the first base 101 and the second base 103 are laminated.

The detection element unit 300 includes an oxygen concentration detection cell 130 and an oxygen pump cell 140. The oxygen concentration detection cell 130 includes a first solid electrolyte body 105 mainly composed of zirconia, and a reference electrode (second electrode) 104 and a detection electrode (first electrode) 106 formed on both surfaces of the first solid electrolyte body 105. And is formed from. The reference electrode 104 is formed of a reference electrode portion 104 a and a first lead portion 104 b extending from the reference electrode portion 104 a along the longitudinal direction of the first solid electrolyte body 105. The detection electrode 106 is formed of a detection electrode portion 106 a and a second lead portion 106 b extending from the detection electrode portion 106 a along the longitudinal direction of the first solid electrolyte body 105.
The reference electrode 104 and the detection electrode 106 correspond to “a pair of electrodes (of the oxygen concentration detection cell)” in the claims. The detection electrode 106 corresponds to “one electrode (of oxygen concentration detection cell)” in the claims.

  The terminals of the first lead portion 104b are first through holes 105a provided in the first solid electrolyte body 105, second through holes 107a provided in an insulating layer 107 described later, and second terminals provided in the second solid electrolyte body 109. The detection element unit side pads 121 are electrically connected through conductors formed in the four through holes 109a and the sixth through holes 111a provided in the protective layer 111, respectively. On the other hand, the terminal of the second lead portion 106b is a third through hole 107b provided in the insulating layer 107 described later, a fifth through hole 109b provided in the second solid electrolyte body 109, and a seventh through hole provided in the protective layer 111. It electrically connects with the detection element part side pad 121 through the conductor formed in each of 111b.

On the other hand, the oxygen pump cell 140 is formed of a second solid electrolyte body 109 mainly composed of zirconia, and a third electrode 108 and a fourth electrode 110 formed on both surfaces of the second solid electrolyte body 109. The third electrode 108 is formed of a third electrode portion 108 a and a third lead portion 108 b extending from the third electrode portion 108 a along the longitudinal direction of the second solid electrolyte body 109. The fourth electrode 110 is formed of a fourth electrode portion 110 a and a fourth lead portion 110 b extending from the fourth electrode portion 110 a along the longitudinal direction of the second solid electrolyte body 109.
The third electrode 108 and the fourth electrode 110 correspond to “a pair of electrodes (of the oxygen pump cell)” in the claims. The third electrode 108 corresponds to “one electrode (of oxygen pump cell)” in the claims.

  And the terminal of the 3rd lead part 108b is a detection element part via the conductor formed in each of the 5th through hole 109b provided in the 2nd solid electrolyte body 109, and the 7th through hole 111b provided in protective layer 111. It is electrically connected to the side pad 121. On the other hand, the terminal of the fourth lead part 110b is electrically connected to the detection element part side pad 121 via a conductor formed in an eighth through hole 111c provided in the protective layer 111 described later. The second lead portion 106b and the third lead portion 108b are connected to the common detection element portion side pad 121 and have the same potential.

The first solid electrolyte body 105 and the second solid electrolyte body 109 are partially stabilized zirconia sintered bodies obtained by adding yttria (Y ₂ O ₃ ) or calcia (CaO) as a stabilizer to zirconia (ZrO ₂ ). It is composed of

  The heating element 102, the reference electrode 104, the detection electrode 106, the third electrode 108, the fourth electrode 110, the heater part side pad 120, and the detection element part side pad 121 can be formed of a platinum group element. Pt, Rh, Pd etc. can be mentioned as a suitable platinum group element which forms these, These can also be used individually by 1 type, and can also use 2 or more types together.

  However, the heating element 102, the reference electrode 104, the detection electrode 106, the third electrode 108, the fourth electrode 110, the heater part side pad 120, and the detection element part side pad 121 are mainly composed of Pt in consideration of heat resistance and oxidation resistance. It is even more preferable to form it. Further, the heating element 102, the reference electrode 104, the detection electrode 106, the third electrode 108, the fourth electrode 110, the heater part side pad 120, and the detection element part side pad 121 contain ceramic components in addition to the main platinum group element. It is preferable to contain. This ceramic component is preferably the same component as the main material on the side to be laminated (for example, the main component of the first solid electrolyte body 105 and the second solid electrolyte body 109) from the viewpoint of fixation. .

An insulating layer 107 is formed between the oxygen pump cell 140 and the oxygen concentration detection cell 130. The insulating layer 107 includes an insulating part 114 and a porous part 115. In the insulating part 114 of the insulating layer 107, a hollow measurement chamber 107c is formed at a position corresponding to the detection electrode part 106a and the third electrode part 108a. The measurement chamber 107c communicates with the outside in the width direction of the insulating layer 107, and a porous portion 115 that realizes gas diffusion between the outside and the measurement chamber 107c under a predetermined rate-limiting condition. Is arranged.
Note that adhesive layers 116 (see FIG. 3) for attaching the oxygen pump cell 140 and the oxygen concentration detection cell 130 to each other are provided on the front and back of the insulating layer 107, respectively.

  The insulating part 114 and the adhesive layer 116 are not particularly limited as long as they are ceramic sintered bodies having insulating properties, and examples thereof include oxide ceramics such as alumina and mullite.

  The porous part 115 is a porous body made of alumina, for example. The porous portion 115 performs rate control when a measurement gas such as exhaust gas flows into the measurement chamber 107c.

  A protective layer 111 is formed on the surface of the second solid electrolyte body 109 so as to sandwich the fourth electrode 110. The protective layer 111 sandwiches the fourth electrode portion 110a, sandwiches the porous electrode protection portion 113a for protecting the fourth electrode portion 110a from poisoning, and the fourth lead portion 110b. It comprises a reinforcing part 112 for protecting the second solid electrolyte body 109. In the gas sensor element 100 of the present embodiment, the current flowing between the electrodes of the oxygen pump cell 140 so that the voltage (electromotive force) generated between the electrodes of the oxygen concentration detection cell 130 becomes a predetermined value (for example, 450 mV). This corresponds to an oxygen sensor element that linearly detects the oxygen concentration in the gas to be measured corresponding to the current flowing through the oxygen pump cell 140.

  Returning to FIG. 1, the metal shell 30 is made of SUS430, and has a male screw portion 31 for attaching the gas sensor to the exhaust pipe, and a hexagonal portion 32 to which an attachment tool is applied at the time of attachment. Further, the metal shell 30 is provided with a metal side step portion 33 protruding radially inward, and this metal side step portion 33 supports a metal holder 34 for holding the gas sensor element 100. . Inside the metal holder 34, a ceramic holder 35 and a talc 36 are arranged in this order from the tip side. The talc 36 includes a first talc 37 disposed in the metal holder 34 and a second talc 38 disposed over the rear end of the metal holder 34. The gas sensor element 100 is fixed to the metal holder 34 by compressing and filling the first talc 37 in the metal holder 34. Further, the second talc 38 is compressed and filled in the metal shell 30, so that a sealing property between the outer surface of the gas sensor element 100 and the inner surface of the metal shell 30 is ensured. An alumina sleeve 39 is disposed on the rear end side of the second talc 38. The sleeve 39 is formed in a multi-stage cylindrical shape, is provided with a shaft hole 39a along the axis, and the gas sensor element 100 is inserted through the shaft hole 39a. The caulking portion 30 a on the rear end side of the metal shell 30 is bent inward, and the sleeve 39 is pressed to the front end side of the metal shell 30 through the stainless steel ring member 40.

  Further, the outer periphery on the front end side of the metallic shell 30 protrudes from the distal end of the metallic shell 30 to cover the distal end portion 100s of the gas sensor element 100 exposed to the measured atmosphere (exhaust gas) and has a plurality of gas intake holes 24a. A metal protector 24 is attached by welding. This protector 24 has a double structure, a cylindrical outer protector 41 having a uniform outer diameter on the outer side, and an outer diameter of the rear end part 42a on the inner side from the outer diameter of the front end part 42b. An inner protector 42 having a bottomed cylindrical shape that is formed to be larger is also arranged.

  On the other hand, on the rear end side of the metal shell 30, the front end side of the outer tube 25 made of SUS430 is inserted. The outer cylinder 25 has a distal end portion 25a whose diameter is enlarged on the distal end side fixed to the metal shell 30 by laser welding or the like. A separator 50 is disposed inside the rear end side of the outer cylinder 25, and a holding member 51 is interposed in a gap between the separator 50 and the outer cylinder 25. The holding member 51 is fixed by the outer cylinder 25 and the separator 50 by engaging a protrusion 50 a of the separator 50 described later and caulking the outer cylinder 25.

  The separator 50 is provided with through holes 50b for inserting the lead wires 11 to 15 for the detection element unit 300 and the heater unit 200 from the front end side to the rear end side (note that the lead wires 14, 15 is not shown). The connection holes 16 that connect the lead wires 11 to 15 to the detection element side pads 121 of the detection element unit 300 and the heater side pads 120 of the heater unit 200 are accommodated in the through holes 50b. Each lead wire 11-15 is connected to a connector (not shown) outside. Electric signals are input and output between the external devices such as the ECU and the lead wires 11 to 15 through this connector. Moreover, although not shown in detail in each lead wire 11-15, it has the structure which showed the conducting wire with the insulating film which consists of resin.

  Further, a substantially cylindrical rubber cap 52 for closing the opening 25 b on the rear end side of the outer cylinder 25 is disposed on the rear end side of the separator 50. The rubber cap 52 is fixed to the outer cylinder 25 by caulking the outer periphery of the outer cylinder 25 toward the radially inner side in a state where the rubber cap 52 is mounted in the rear end of the outer cylinder 25. The rubber cap 52 is also provided with through holes 52a for inserting the lead wires 11 to 15 from the front end side to the rear end side.

Next, the interval between the first solid electrolyte body 105 and the second solid electrolyte body 109, which is a characteristic part of the present invention, will be described with reference to FIG. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2, and is a cross-sectional view orthogonal to the axis L direction of the gas sensor element 100.
In FIG. 3, the detection electrode 106 and the third electrode 108 are arranged to face each other while facing the measurement chamber 107c, and the distance between the first solid electrolyte body 105 and the second solid electrolyte body 109 at the position of each electrode. H ₂ is shorter than the length H ₆ in the stacking direction of the first solid electrolyte body 105 and the second solid electrolyte body 109 at the position of the porous portion 115. Further, the distance H ₃ between the detection electrode 106 and the third electrode 108 arranged to face each other is shorter than the length H ₁ of the porous portion 115 in the stacking direction.
Here, in the case of FIG. 3, the first solid electrolyte body 105 and the second solid electrolyte body 109 protrude stepwise from the surroundings toward each other at the electrode positions of the detection electrode 106 and the third electrode 108. .

In this way, by setting H ₃ <H ₁ , the volume of the measurement chamber 107c is minimized in the vicinity of the detection electrode 106 and the third electrode 108 that are arranged to face each other, and thus the measurement object that enters and exits the measurement chamber 107c is measured. Responsiveness is improved by immediately reflecting changes in the gas atmosphere. For example, when H ₂ = H ₁ and the thicknesses of the detection electrode 106 and the third electrode 108 are increased, H ₃ <H ₁ is obtained. In this case, however, the gas diffusion rate at the electrode is reduced and the response is reduced. Reduce. Therefore, by setting H ₂ <H ₆ , H ₃ <H ₁ can be realized without increasing the thicknesses of the detection electrode 106 and the third electrode 108.
In the present invention, H ₂ and H ₃ are both values at the center position of the detection electrode 106 and the third electrode 108 (position where the axial direction of the sensor element and the centers in the vertical direction thereof intersect). H ₁ is the value of the porous portion 115 alone at the position facing the measurement chamber 107c in the porous portion 115 where the gas to be measured enters and exits, and the thickness of the adhesive layer 116 from which the gas to be measured does not flow in and out. Is not included. Further, H ₆ is the first solid electrolyte body 105 and the second solid electrolyte body 109 at the position of the porous portion 115 at the position facing the measurement chamber 107c in the porous portion 115 where the gas to be measured enters and exits. Therefore, it is synonymous with the length including the thickness of the porous portion 115 and the thickness of the adhesive layer 116. The “stacking direction” is a direction penetrating the solid electrolyte bodies 105 and 109, and is the vertical direction in FIG.
The thickness of the detection electrode 106 and the third electrode 108 may be about 5 to 30 [mu] _m, the H 1 -H ₃ may be about 0～30Myuemu.

FIG. 4 is a modified example of FIG. 3, and the first solid electrolyte body 105 and the second solid electrolyte body 109 approach each other at the electrode positions of the detection electrode 106 and the third electrode 108. The body 105 and the second solid electrolyte body 109 are curved in the stacking direction.
Also in the case of FIG. 4, since H ₄ <H ₆ and H ₅ <H ₁ , the response can be improved without increasing the thickness of the detection electrode 106 and the third electrode 108. H ₄ corresponds to H ₂ in FIG. 3, and H ₅ has a dimension corresponding to H ₃ in FIG.
However, in the case of the example of FIG. 4, since the detection electrode 106 and the third electrode 108 are also curved, the distance between the electrodes varies between the central portion and the peripheral portion of each electrode, and the responsiveness tends to slightly vary depending on the position of the electrodes. It is in. Therefore, as shown in FIG. 3, when the first solid electrolyte body 105 and the second solid electrolyte body 109 are protruded stepwise from the surroundings, and the detection electrode 106 and the third electrode 108 themselves are flattened, the electrode depends on the position of the electrode. It is preferable because the distance (that is, responsiveness) does not change.

  FIG. 5 is a process diagram showing an example of a manufacturing method of the gas sensor 1 (gas sensor element 100). First, as shown in FIG. 5A, an unfired heating element (only the heating portion 102ax is shown in FIG. 5) is paste-printed on the unfired first substrate, and further sandwiched between unfired second substrates. An unfired heater part 200x is obtained. Similarly, unfired reference electrode 104x and detection electrode 106x are paste-printed on the front and back surfaces of unfired first solid electrolyte body 105x, respectively, to obtain unfired oxygen concentration detection cell 130x. Further, an unsintered insulating layer (only the porous paste 115x serving as the porous portion is displayed in FIG. 5) is paste-printed on both ends of the first solid electrolyte body 105x on the detection electrode 106x side along the longitudinal direction. A pasting paste 116x is applied between the porous portion 115x and the first solid electrolyte body 105x.

Next, a burnout paste mainly composed of carbon is formed in a portion 107cx that is partitioned by the unfired first solid electrolyte body 105x and the unfired insulating layer (only the porous paste 115x is shown in FIG. 5) and becomes a measurement chamber. 400 is applied less than the volume to be the measurement chamber (FIG. 5B). For example, the burnable paste 400 is applied such that the burnable paste 400 is on the lower side (the first solid electrolyte body 105x side) from the upper surface S of the portion 107cx that becomes the measurement chamber.
Next, the unfired third electrode 108x and the fourth electrode 110x are paste-printed on the front and back of the unfired second solid electrolyte body 109x, respectively, to obtain an unfired oxygen pump cell 140x. Further, the unfired protective layer 111x and the electrode protection part 113ax are paste-printed on the second solid electrolyte body 109x on the fourth electrode 110x side (FIG. 5C).
The unfired first base body, second base body, first solid electrolyte body 105x, and second solid electrolyte body 109x are formed from a slurry containing the material of these sheets by, for example, a sheet forming method using a doctor blade device. It can be produced by molding and cutting out. Further, the heating element, each electrode, porous material, and the like can be produced by a printing method using a paste containing these materials.

Then, the pasting paste 116x is applied to the upper side (oxygen pump cell 140x side) of the porous portion 115x, and the unfired heater portion 200x, the oxygen concentration detection cell 130x, and the oxygen pump cell 140x are stacked and pressurized in this stacking direction (FIG. 5 (d)). At this time, since the application amount of the burnable paste 400 is smaller than the volume serving as the measurement chamber, the first solid electrolyte body 105x and the second solid electrolyte body 109x protrude in a step shape so as to approach each other in the stacking direction (FIG. 3). reference).
Specifically, the reference electrode 104x located on the opposite side of the detection electrode 106x is pressed by the surface of the heater part 200x and is invaded into the first solid electrolyte body 105x. Accordingly, the portion of the first solid electrolyte body 105x in which the reference electrode 104x is indented protrudes stepwise toward the upper side (the second solid electrolyte body 109x side). Here, since the reference electrode 104x and the detection electrode 106x are arranged at the same size and overlap each other, the portion of the first solid electrolyte body 105x in which the reference electrode 104x is indented is just below the detection electrode 106x.
Similarly, the fourth electrode 110x located on the opposite side of the third electrode 108x is pressed by the surface of the electrode protection part 113ax and intruded into the second solid electrolyte body 109x. Accordingly, the second solid electrolyte body 109x in the portion where the fourth electrode 110x is invaded protrudes stepwise toward the lower side (first solid electrolyte body 105x side). Here, since the fourth electrode 110x and the third electrode 108x have the same dimensions and are arranged at positions where they overlap each other, the portion of the second solid electrolyte body 109x in which the fourth electrode 110x is indented is just the third electrode 108x. Directly below.
And the whole is baked in this state, and the gas sensor 1 (gas sensor element 100) is manufactured.

  Here, when the application amount of the burnable paste 400 is significantly reduced from the volume serving as the measurement chamber, the first solid electrolyte body 105x and the second solid electrolyte body 109x are recessed in a step shape, and the step shape as shown in FIG. Are formed. On the other hand, when the application amount of the burnable paste 400 is increased, the overhang of the first solid electrolyte body 105x and the second solid electrolyte body 109x due to the intrusion of the reference electrode 104x and the fourth electrode 110x becomes gentle, as shown in FIG. A curved portion is formed.

3 and 4, the reference electrode 104 and the fourth electrode 110 located on the opposite sides of the detection electrode 106 and the third electrode 108 are used, respectively, and the stacking pressurization when manufacturing the gas sensor element is used. Thus, the first solid electrolyte body 105 and the second solid electrolyte body 109 are deformed. For this reason, it is not necessary to prepare another process for deforming the first solid electrolyte body 105 and the second solid electrolyte body 109, and manufacturing is possible without increasing the number of processes.
However, the present invention is not limited to the above. For example, after the unfired oxygen pump cell 140x is manufactured, the oxygen pump cell 140x may be embossed and deformed, and this may be laminated with the oxygen concentration detection cell 130x, and the whole may be fired. In this case, only the second solid electrolyte body 109 on the oxygen pump cell 140 side may protrude or curve toward the oxygen concentration detection cell 130 side, and the first solid electrolyte body 105 may be flat or vice versa.

The present invention is not limited to the above embodiment, and can be applied to any gas sensor (gas sensor element) including an oxygen concentration detection cell, a porous portion communicating with a measurement chamber, and an oxygen pump cell. Although it can be applied to a sensor (oxygen sensor element), it is not limited to these uses, and it goes without saying that the present invention covers various modifications and equivalents included in the concept and scope of the present invention. For example, in order to detect the NOx concentration in the gas to be measured, a known NOx sensor (NOx sensor element) in which a second oxygen pump cell is added in addition to the above two cells, or an HC sensor (HC sensor element) that detects the HC concentration ) Etc., the present invention may be applied.
Moreover, in the said embodiment, although the porous part was provided in the transversal direction (direction perpendicular | vertical to an axial direction) of a gas sensor element, you may provide a porous part in the front-end | tip of a gas sensor element. However, since the solid electrolyte body hardly bends in the short direction of the gas sensor element, the present invention is particularly effective when the porous portion is provided in the short direction of the gas sensor element.

DESCRIPTION OF SYMBOLS 1 Gas sensor 30 Metal fitting 100 Gas sensor element 105 1st solid electrolyte body 109 2nd solid electrolyte body 104,106 (Oxygen concentration detection cell) pair of electrodes 108,110 (oxygen pump cell) pair of electrodes 106,108 One electrode 107c Measurement chamber 107cx Part to be a constant chamber 115 Porous portion 115x Porous paste 130 Oxygen concentration detection cell 130x Unsintered oxygen concentration detection cell 140 Oxygen pump cell 140x Unsintered oxygen pump cell 400 Burning paste L Axial direction H _{1 of} porous portion distance H _3, H ₅ distance H ₆ porous portion between oppositely disposed electrodes between the first solid electrolyte body in the length H _2, H ₄ electrode positions in the stacking direction and a second solid electrolyte body The length in the stacking direction of the first solid electrolyte body and the second solid electrolyte body at the position

Claims (4)

An oxygen concentration detection cell comprising a plate-like first solid electrolyte body and a pair of electrodes provided on the first solid electrolyte body;
A porous portion laminated on the oxygen concentration detection cell;
An oxygen pump cell comprising a plate-like second solid electrolyte body and a pair of electrodes provided on the second solid electrolyte body, and stacked on the oxygen concentration detection cell via the porous portion;
The oxygen concentration detection cell, the porous portion, and the oxygen pump cell are partitioned, and one electrode of the pair of electrodes of the oxygen concentration detection cell and one electrode of the pair of electrodes of the oxygen pump cell face each other. Measuring chambers
A gas sensor element having
A substantially cylindrical metal shell that holds the gas sensor element therein,
The distance between the first solid electrolyte body and the second solid electrolyte body at the positions of the electrodes arranged opposite to each other is such that the first solid electrolyte body and the second solid electrolyte body at the position of the porous portion are as follows. Shorter than the length in the stacking direction,
A gas sensor in which a distance between the electrodes arranged to face each other is shorter than a length of the porous portion in a stacking direction.   2. The gas sensor according to claim 1, wherein the first solid electrolyte body or the second solid electrolyte body protrudes in a step shape from the periphery toward each other at the electrode positions arranged to face each other.   The first solid electrolyte body and the second solid electrolyte body are curved in the stacking direction so that the first solid electrolyte body or the second solid electrolyte body approaches each other at the opposed electrode positions. Item 2. The gas sensor according to Item 1. An oxygen concentration detection cell comprising a plate-like first solid electrolyte body and a pair of electrodes provided on the first solid electrolyte body;
A porous portion laminated on the oxygen concentration detection cell;
An oxygen pump cell comprising a plate-like second solid electrolyte body and a pair of electrodes provided on the second solid electrolyte body, and stacked on the oxygen concentration detection cell via the porous portion;
The oxygen concentration detection cell, the porous portion, and the oxygen pump cell are partitioned, and one electrode of the pair of electrodes of the oxygen concentration detection cell and one electrode of the pair of electrodes of the oxygen pump cell face each other. Measuring chambers
A gas sensor element having
A substantially cylindrical metal shell for holding the gas sensor element therein, and a gas sensor manufacturing method comprising:
Between the unsintered oxygen concentration detection cell, which is the oxygen concentration detection cell before firing, and the unfired oxygen pump cell, which is the oxygen pump cell before firing, at a predetermined position communicating with the site serving as the measurement chamber, Apply the porous paste that is porous before firing,
Applying a burnable paste mainly composed of carbon to the measurement chamber, less than the volume of the measurement chamber,
After pressurizing the green oxygen concentration detection cell and the green oxygen pump cell in the stacking direction,
A manufacturing method of a gas sensor for firing the whole.

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