JP2007333660A - Laminated gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable laminated gas sensor that prevents cracks in the manufacturing process from compression bonding to firing. <P>SOLUTION: The laminated gas sensor 1 has a solid electrolyte layer 11, a measured gas diffusion layer 140 and a standard gas intake layer 12. Between a compressed area 11c in which the solid electrolyte layer 11 is held between a measured gas electrode 161 and a standard gas electrode 162 and inevitably compressed by the measured gas electrode 161 and the standard gas electrode 162 under the compression bonding of the solid electrolyte layer 11 with the measured gas diffusion layer 140, and an uncompressed area 11a of the solid electrolyte layer 11 that is not compressed by the measured gas electrode 161 nor the standard gas electrode 162, the solid electrolyte layer 11 has a buffer area 11b for buffering a shearing stress acting on the interface between both areas, along all or part of the outer edges of the measured gas electrode 161 or standard gas electrode 162. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminated gas sensor such as an oxygen sensor or a NOx sensor that detects a specific gas component in, for example, automobile exhaust gas.

  In order to prevent air pollution, regulations on exhaust gas from automobile engines and the like are becoming stricter year by year. As a means for reducing harmful components in exhaust gas, for example, a system that suppresses the generation of harmful components in exhaust gas by controlling combustion of the engine, the combustion state of the engine from the oxygen concentration and nitrogen oxide (NOx) concentration in the exhaust gas, etc. And a system that feeds back to control of fuel injection, air-fuel ratio, and the like is used.

For example, Patent Document 1 discloses a stacked gas sensor in which a pair of measuring unit electrodes, an electrochemical cell made of a solid electrolyte body, and a heater are integrally provided.
JP 2004-309457 A

The stacked gas sensor shown in FIG. 7 includes a sensor unit 16 and a heater unit 15.
The sensor unit 16 includes, for example, a sheet-like solid electrolyte layer 11 made of partially stabilized zirconia, the sheet-like gas shielding layers 17 and 14 made of alumina, and a sheet-like gas made of alumina having a large particle size. The diffusion layer 140 is a sheet made of alumina or the like, and includes a substantially U-shaped reference gas chamber forming layer 12 provided with a groove serving as the reference gas chamber 120.

A pair of measurement electrodes, that is, a measurement gas electrode 161 and a reference gas electrode 162 are formed on the opposing surfaces of the solid electrolyte layer 11 by printing or the like, and a measurement lead portion 163 that is electrically connected to the measurement gas electrode 161; A pair of lead portions 163 and 164 are formed with a reference lead portion 164 that is electrically connected to the reference gas electrode 162.
The heater unit 15 is composed of a sheet-like heater substrate 150 made of alumina or the like formed by printing or the like, and an insulating layer 13 in which a heating element 153 and heater lead parts 152a and 152b that conduct to the heating element 153 are formed. Yes.

  As shown in FIG. 8, the laminated gas sensor is constructed by laminating the sensor unit 16 and the heater unit 15 and firing them integrally. As shown in FIGS. 7 and 8, the heater lead portions 152a and 152b and the electrode terminals 155a and 155b provided on the surface of the heater substrate 150 are through-hole electrodes 154a and 154b provided in the through-holes 151a and 151b. Conducted through.

However, it has been found that in the conventional laminated gas sensor, internal cracks are likely to occur during the lamination and firing processes.
FIGS. 8A to 8C show crack occurrence positions. Inside the solid electrolyte layer 11, the pair of measurement units are arranged along the outer peripheral edges of the pair of measurement unit electrodes 161 and 162. FIG. In a portion sandwiched between the electrodes 161 and 162, a crack having a length of about several millimeters or damage that causes the crack may occur extremely rarely.

The presence of such cracks is difficult to detect from the outside, significantly impairs the reliability of the sensor, and even if it occurs rarely, it must be reliably prevented in the manufacturing process.
In particular, when a laminated gas sensor is used as an oxygen concentration sensor in an automobile exhaust gas, it is rapidly heated to a high temperature of 500 ° C. or higher, so if a crack exists in the sensor element, the crack progresses due to thermal stress, There is also a possibility of destruction of the sensor element.

  In view of this situation, an object of the present invention is to provide a highly reliable multilayer gas sensor by preventing cracks generated in the solid electrolyte layer in the multilayer gas sensor manufacturing process.

According to the first aspect of the present invention, the gas electrode to be measured is provided on one of the opposing surfaces of the solid electrolyte layer and the reference gas electrode is provided on the other to form a pair of measuring portion electrodes, and the gas diffusion layer to be measured is provided on the one surface side. In the laminated gas sensor formed by laminating and pressure bonding the reference gas introduction layer on the other surface side,
The solid electrolyte layer includes a compression region that is inevitably compressed by being sandwiched between the pair of measurement unit electrodes when pressed with the gas diffusion layer to be measured, and is not compressed by any of the pair of measurement unit electrodes. A buffer region for relaxing stress acting on the interface between the two regions was provided between the compression region.

The internal cracks in the solid electrolyte layer are inevitably compressed by the pair of electrodes formed on both surfaces of the solid electrolyte layer in the pressure-bonding step between the solid electrolyte layer and the gas diffusion layer to be measured. This is considered to occur at the interface with the region where the film is not formed and is not compressed.
According to the present invention, by providing a buffer region between the compression region and the non-compression region of the solid electrolyte layer, it acts on the interface between the solid electrolyte layer and the measured gas diffusion layer at the time of pressure bonding. The generation of cracks can be prevented because the shearing stress is reduced. Further, since the density change between the compressed region and the non-compressed region can be moderated by the buffer region, the thermal stress due to the difference in the sintering rate during firing can be alleviated and the progress of cracks can be prevented.

  According to a second aspect of the present invention, the buffer region is provided by forming all or part of the outer peripheral edge of one of the pair of measuring portion electrodes at a position outside the other outer peripheral edge.

  With the above configuration, the solid electrolyte layer is compressed by only one of the pair of measurement unit electrodes along the region outside the compression region where the solid electrolyte layer is compressed by both of the pair of measurement unit electrodes. A region to be formed is formed. Therefore, a region compressed only by the one electrode becomes a buffer region, and the shear stress acting between the compressed region and the non-compressed region is relieved, and the generation of cracks can be prevented.

  In the invention of claim 3, in the width direction of the solid electrolyte layer, the buffer region is provided by forming one of the pair of measurement part electrodes wider than the other.

  The buffer region is formed in the width direction of the pair of measurement unit electrodes, and cracks that progress in the longitudinal direction in the vicinity of both side edges of the pair of measurement unit electrodes can be prevented.

  In the invention of claim 4, in the longitudinal direction of the solid electrolyte layer, the buffer region is provided by forming one of the pair of measurement part electrodes longer than the other.

  The buffer region is formed in the longitudinal direction of the pair of measurement unit electrodes, and cracks that progress in the width direction in the vicinity of the front end edges of the pair of measurement unit electrodes can be prevented.

  According to a fifth aspect of the present invention, lead portions that are electrically connected to the pair of measurement portion electrodes are provided on the surface of the solid electrolyte layer, respectively, and at least one width of the lead portions is provided to be the same width as the electrodes.

  By providing the measurement part electrode and the lead part with the same width, the ratio of the compression region to the whole solid electrolyte layer is increased, and homogenization of the whole element is achieved, so the reliability of the stacked gas sensor is improved. improves.

  According to a sixth aspect of the present invention, a lead portion is provided on the surface of the solid electrolyte layer for conducting the pair of measurement portion electrodes, and one of the lead portions is provided outside the outer periphery of the other electrode and the lead portion. It was.

  Even if the lead part is provided outside the outer peripheral edge of the measuring part electrode, the peripheral part of the pair of measuring part electrodes is provided that the buffer region is formed on the outer peripheral edge of the pair of measuring part electrodes. No cracks occur.

  According to the present invention, in the stacking and thermocompression bonding processes, stress concentration does not occur on the outer peripheral edges of the pair of measurement unit electrodes provided on the opposing surfaces of the solid electrolyte layer, and the generation of cracks inside the solid electrolyte layer is prevented. it can.

A first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1A shows a usage mode of the laminated gas sensor element 1 to which the present invention is applied, and FIG. 1B is a developed perspective view showing a detailed configuration of the laminated gas sensor element 1 of FIG. is there. FIG. 2A is a plan view showing the planar shape and positional relationship of a pair of measurement unit electrodes 161 and 162 formed on the solid electrolyte layer 11 which is a characteristic part of the present invention. FIGS. 2B and 2C are views. FIG. 2A is a schematic cross-sectional view taken along the line AA in FIG. 2A and a schematic cross-sectional view taken along the line BB in FIG.

  As shown in FIG. 1A, the stacked gas sensor element 1 includes a sensor unit 16 and a heater unit 15.

  As shown in FIG. 1B, the sensor section 16 includes gas shielding layers 14 and 17 (hereinafter referred to as shielding layers 14 and 17), a measured gas diffusion layer 140 (hereinafter referred to as diffusion layer 140), Measurement gas electrode 161 (hereinafter referred to as measurement electrode 161), measurement lead portion 163 conducting therewith, solid electrolyte layer 11, reference gas electrode 162 (hereinafter referred to as reference electrode 162), and reference lead conducting therethrough The heater part 15 includes a heater substrate 150, a heating element 153, heater lead parts 152a and 152b that are electrically connected to the heater substrate 150, and the insulating layer 13. It has a laminated structure.

  On the upper surface of the sensor portion 16, terminals 165 and 166 are formed which are electrically connected to the measurement lead portion 163 and the reference lead portion 164 through through-hole electrodes 167 and 168, respectively. A potentiometer 30 shown in FIG.

  Terminals 155a and 155b are formed on the upper surface of the heater portion 15 through the heater lead portions 152a and 152b and through-hole electrodes 154a and 154b. The terminals 155a and 155b have power supplies shown in FIG. 4 is connected via an electronic control unit (ECU) 3 to control energization of the heating element 153 to heat the sensor unit 16 to a predetermined temperature.

  The solid electrolyte layer 11 includes, for example, 100 parts of yttria-stabilized zirconia having an average particle size of 0.5 microns (parts by weight, the same applies hereinafter), 1 part of a sintering aid such as α-alumina, and polyvinyl butyral (PVB). A slurry obtained by dispersing 5 parts of a binder and 10 parts of a plasticizer such as dibutyl phthalate (DBP) in a solvent such as a mixed organic solvent of 10 parts of toluene and 10 parts of ethanol by a doctor blade method or the like (for example, 0 after drying) .2 mm) after being formed into a sheet and dried, it is processed into a rectangle of a predetermined size (for example, 6 mm × 56 mm) by, for example, a punching press, and the reference lead portion 164 and the terminal 166 are electrically connected. It is obtained by drilling a through hole 111 for forming the through hole electrode 168.

The measurement electrode 161 and the measurement lead portion 163 are formed on one surface of the solid electrolyte layer 11 by printing or the like using a platinum paste to which the slurry for solid electrolyte is added, and the reference electrode 162 is formed. And the reference lead part 164 are formed on the other surface so as not to coincide with the outer peripheral edges of the measurement electrode 161 and the measurement lead part 163.
The film thickness of the measurement electrode 161, the measurement lead portion 163, the reference electrode 162, and the reference lead portion 164 is about 10 microns.

  The measurement electrode 161 and the reference electrode 162 are both electrodes formed on the lower surface of the diffusion layer 140, and the measurement lead portion 163 and the reference lead portion 164 are both below the shielding layer 14. The electrode formed in is shown.

  The reference gas chamber forming layer 12 is composed of, for example, 98 parts of α-alumina having an average particle size of 0.3 microns, 3 parts of a sintering aid such as yttria partially stabilized zirconia, 10 parts of a binder such as PVB, and plastic such as DBP. A slurry dispersed in a solvent such as a mixed organic solvent such as 30 parts of toluene and 30 parts of ethanol together with 10 parts of the agent is made into an insulating alumina green sheet having a predetermined plate thickness (for example, 0.2 mm after drying) by a doctor blade method or the like. A plurality of (for example, three) alumina green sheets for insulation are stacked, and a substantially U-shaped (for example, 6 mm × 56 mm) having a rectangular groove (2 mm × 53 mm) that becomes the reference gas chamber 120 by a punching press or the like. ) To obtain.

  The shielding layer 17 forms a sheet having a predetermined thickness (for example, 0.2 mm after drying) with the same material and the same manufacturing method as the insulating alumina green sheet, and has a predetermined size (for example, 6 mm × 56 mm). And through holes 141 and 142 for forming through-hole electrodes 167 and 168 for conducting the measurement lead portions 163 and 164 and the terminals 165 and 166, respectively.

  The heater substrate 150 is formed into a sheet having a predetermined plate thickness (for example, 0.2 mm after drying) by using the same material and the same manufacturing method as the insulating alumina green sheet, and a rectangular (for example, 6 mm) having a predetermined size. And through holes 151a and 151b for providing through-hole electrodes 154a and 154b for conducting the heater leads 152a and 152b and the terminals 155a and 155b. .

  The heater 153, the heater leads 152a and 152b, and the terminals 155a and 155b are formed on the heater substrate 150 by thick film printing using, for example, platinum paste added with the alumina slurry. In the through holes 151a and 151b, the heater lead portions 152a and 152b are printed, and at the same time, through hole electrodes 154a and 154b are formed by suction or the like.

  The diffusion layer 140 is made of alumina having a predetermined particle size larger than that of the alumina used for the insulating alumina green sheet, and a binder such as PVB, a plasticizer such as DBP, and a solvent such as a toluene-ethanol mixed organic solvent. Is mixed at a predetermined ratio, and the dispersed slurry is formed into a sheet shape by the doctor blade method and dried to obtain an alumina green sheet for a diffusion layer having a predetermined plate thickness (for example, 0.2 mm after drying). Is punched into a predetermined size (for example, 6 mm × 10 mm).

  The shielding layer 14 is formed by punching the same insulating alumina green sheet as the shielding layer 17 into a rectangle having a predetermined size (for example, 6 mm × 56 mm), and partially (for example, 6 mm × 10 mm). It is obtained by replacing with the diffusion layer 140.

  The insulating layer 13 is obtained by laminating a plurality of (for example, three) alumina green sheets for insulation and punching them into a rectangle having a predetermined size (for example, 6 mm × 56 mm).

  The through-hole electrodes 167 and 168 are formed in the through-holes 111, 141, 142, 171, and 172 by suction printing or the like using the same material as the pair of measurement unit electrodes 161 and 162.

The solid electrolyte layer 11 on which the pair of measurement unit electrodes 161 and 162 are formed is formed by stacking the shielding layer 14 including the diffusion layer 140 and the shielding layer 17 on the upper surface thereof, and then laminating the integrated sensor unit by thermocompression bonding. Form body 16b.
Further, the insulating layer 13 and the reference gas chamber forming layer 12 are laminated on the upper surface of the heater substrate 150 on which the heating element 153 and the heater lead portions 152a and 152b are formed, and then the integrated heater is formed by thermocompression bonding. A partial laminate 15b is formed.

  The sensor section laminate 16b and the heater section laminate 15b thus formed are bonded with an alumina-zirconia adhesive paste 18, which is dried, degreased and fired.

  The solid electrolyte layer 11 is an oxygen ion conductive solid electrolyte layer, and the gas diffusion layer 140 to be measured is a porous body through which the gas to be measured can diffuse, and the shielding layers 14 and 17, the reference gas layer 12, and the insulation. The layer 13 and the heater substrate 150 are sintered bodies having insulating properties.

Terminal electrodes 165 and 166 that are electrically connected to the measurement lead 163 and the reference lead 164, respectively, on the upper surface of the shielding layer 17, and terminal electrodes 155a and 155b that are electrically connected to the leads 152a and 152b, respectively, on the lower surface of the heater substrate 150. Is formed by thick film printing or the like.
Thus, the integrated gas sensor element 1 is obtained.

  For example, when measuring a measurement gas such as an automobile exhaust gas, the measurement electrode 161 is obtained by placing the diffusion layer 14 side of the stacked gas sensor element 1 in the measurement gas and placing the inlet of the reference gas chamber 120 in the atmosphere. Is exposed to the gas to be measured through the diffusion layer 140, and the reference electrode 162 is exposed to the reference gas (atmosphere) introduced into the reference gas chamber 120 from the entrance.

  The solid electrolyte layer 11 has oxygen ion conductivity, and generates a potential difference between the measurement electrode 161 and the reference electrode 162 due to the difference between the oxygen concentration in the measurement gas and the oxygen concentration in the reference gas. By measuring this with the potentiometer 30 or the like, the oxygen concentration in the measurement gas can be known.

The shape and arrangement of the pair of measurement part electrodes, which is a feature of the present invention, will be described.
As shown in FIG. 2A, in this embodiment, the width of the measurement electrode 161 and the width of the measurement lead portion 163 are formed to be the same width, and the width of the reference electrode 162 and the reference lead portion 164 are formed. And the outer peripheral edge of the measurement electrode 161 and the outer peripheral edge of the reference electrode 162 are not aligned with each other.

  At this time, as shown in FIG. 2B, both the measurement electrode 161 and the reference electrode 162 are unavoidable by the non-compressed region 11a that is not compressed by either the measurement electrode 161 or the reference electrode 162. A buffer region 11b compressed only by the reference electrode 162 is formed in the longitudinal direction of the solid electrolyte 11 between the compressed region 11c to be compressed.

  Further, as shown in FIG. 2C, the compression is performed by both the uncompressed region 11a that is not compressed by the measurement electrode 161 and the reference electrode 162, and the measurement electrode 161 and the reference electrode 162. Between the region 11 c, a buffer region 11 b that is compressed only by the reference electrode 161 and a buffer region 11 b that is compressed only by the reference electrode 162 are formed in the width direction of the solid electrolyte 11.

Here, the crack generation mechanism of the conventional multilayer gas sensor estimated with reference to FIG. 3 and the effect of the present invention will be described.
In the multilayer gas sensor having a conventional structure, as shown in the left diagram of FIG. 3A (before thermocompression bonding), the solid electrolyte layer is formed such that the outer peripheral edges of the measurement part electrode 161 and the reference electrode 162 are opposed to each other. 11 is formed.

  The shielding layer 17, the shielding layer 14 partially including the diffusion layer 140, and the solid electrolyte layer 11 provided with the electrode to be measured 161 and the reference electrode 162 are laminated. When sandwiched and pressed while heating until the solid electrolyte layer 11 and the shielding layer 14 (including the diffusion layer 140) are in close contact, the measurement electrode 161 and the reference electrode 162 are connected to the solid electrolyte layer 11. The solid electrolyte layer 11 is compressed while being difficult to insert.

As schematically shown in the right diagram of FIG. 3 (A) (after heat compression), the compressed region 11c sandwiched between the measurement electrode 161 and the reference electrode 162 is more than the other non-compressed region 11a. By applying extra pressure by the thickness of the measurement electrode 161 and the thickness of the reference electrode 162 (for example, 10 to 20 microns), the interface between the non-compressed region 11a and the compressed region 11c is strong. Shear stress works, and it takes a lot of damage.
Moreover, the plasticity of the binder (PVB or the like) contained in the solid electrolyte layer 11 is increased by heating, and the raw material particles constituting the solid electrolyte layer 11 can move.
For this reason, rearrangement of the raw material particles occurs due to compression, the compression region 11c has a higher molding density than the non-compression region 11a, and there is a large density difference at the interface between the compression region 11c and the non-compression region 11a. Arise.

  In general, in firing ceramics, it is known that the higher the molding density, the lower the sintering temperature and the faster the firing rate. Therefore, when the solid electrolyte layer 11 having a difference in molding density as described above is fired, the sintering speed of the compression region 11c is faster than the sintering speed of the non-compression region 11a. It is conceivable that thermal stress due to the difference in sintering speed is applied between the regions, and the damage proceeds to cracks.

  On the other hand, in this embodiment, as shown in FIG. 2, the buffer region 11b for buffering the shear stress acting on the interface between the non-compressed region 11a and the compressed region 11c of the solid electrolyte layer 11 is provided with the measurement electrode 161 or the above-described electrode. The solid electrolyte layer 11 is provided along almost all or part of the outer peripheral edge of the reference electrode 162.

As shown in the left diagram of FIG. 3B (before thermocompression bonding), the solid electrolyte layer 11 and the shielding layer 17 formed so that the outer peripheral edge of the measurement electrode 161 and the outer peripheral edge of the reference electrode 162 do not coincide with each other. And the diffusion layer 140 are stacked and sandwiched between the metal plates 20 and 21 and heated and pressurized.
In this case, as shown in the right figure of FIG. 3B (after thermocompression bonding), the measurement electrode 161 and the reference electrode 162 are compressed into the solid electrolyte layer 11 while being embedded in the solid electrolyte layer 11 as in the conventional case. To do.

However, the solid electrolyte layer 11 includes a compressed region 11c where the measurement electrode 161 and the reference electrode 162 are compressed, and an uncompressed region 11a where the measurement electrode 161 and the reference electrode 162 are not compressed. Since the buffer region 11b compressed by only one of the measurement electrode 161 and the reference electrode 162 is formed between them, the shear stress acting on the interface between the non-compressed region 11a and the compressed region 11b is relieved. Is done.
Therefore, the damage occurring at the interface can be suppressed to a range that does not lead to cracks. Therefore, according to the present invention, the occurrence of cracks can be easily prevented without greatly changing the conventional process.

FIG. 4 is a schematic cross-sectional view of the solid electrolyte layer 11, the measurement electrode 161, the reference electrode 162, the uncompressed region 11a, the buffer region 11b, and the compressed region 11c in the second embodiment of the present invention. .
4A shows the shape and positional relationship of the measurement electrode 161 and the reference electrode 162 formed on the solid electrolyte layer 11, and FIG. 4B shows the solid in the AA cross section in FIG. 4A. 4C schematically shows an enlarged cross-sectional structure of the electrolyte layer 11, and FIG. 4C schematically shows an enlarged cross-sectional structure of the solid electrolyte layer 11 in the BB cross section in FIG. 4A.

In this embodiment, the width of the measurement electrode 161 is wider than the width of the reference electrode 162, and the length of the measurement electrode 161 is the same as the length of the reference electrode 162. As shown in FIG. 4B, when the lengths of the measurement electrode 161 and the reference electrode 162 are the same, the buffer region 11b is not formed, and cracks may occur.
As shown in FIG. 4C, the buffer region 11b is formed between the non-compressed region 11a and the compressed region 11c in the width direction of the solid electrolyte layer 11 to prevent the occurrence of cracks. it can.

FIG. 5 is a schematic cross-sectional view of the solid electrolyte layer 11, the measurement electrode 161, the reference electrode 162, the non-compressed region 11a, the buffer region 11b, and the compressed region 11c in the third embodiment of the present invention. .
5A shows the shape and positional relationship of the measurement electrode 161 and the reference electrode 162 formed on the solid electrolyte layer 11, and FIG. 5B shows the solid in the AA cross section in FIG. The cross-sectional enlarged structure of the electrolyte layer 11 is schematically shown, and FIG. 5C schematically shows the cross-sectional enlarged structure of the solid electrolyte layer 11 in the BB cross section in FIG.

In this embodiment, the width of the measurement electrode 161 is wider than the width of the reference electrode 162, and the length of the measurement electrode 161 is longer than the length of the reference electrode 162.
As shown in FIGS. 5B and 5C, also in this embodiment, the buffer region 11b is formed between the uncompressed region 11a and the compressed region 11c in the solid electrolyte layer 11, and cracks are generated. Can be prevented.
In this embodiment, the same effect can be obtained even if the width of the measurement electrode is narrower than the width of the reference electrode and the length of the measurement electrode 161 is shorter than the length of the reference electrode 162.

FIG. 6 is a schematic cross-sectional view of the solid electrolyte layer 11, the measurement electrode 161, the reference electrode 162, the non-compressed region 11a, the buffer region 11b, and the compressed region 11c in the fourth embodiment of the present invention. .
6A shows the shape and positional relationship of the measurement electrode 161 and the reference electrode 162 formed on the solid electrolyte layer 11, and FIG. 6B shows the solid in the AA cross section in FIG. 6A. 6C schematically shows the cross-sectional enlarged structure of the electrolyte layer 11, and FIG. 6C schematically shows the cross-sectional enlarged structure of the solid electrolyte layer 11 in the BB cross section in FIG. 6A. FIG. 6A schematically shows an enlarged cross-sectional structure of the solid electrolyte layer 11 in the CC cross section in FIG.

  In the present embodiment, the reference lead portion 164 that conducts the reference electrode 162 and the terminal 166 is placed outside the outer periphery of the measurement lead portion 163 that conducts the opposing measurement electrode 161 and the terminal 165. Form. As shown in FIGS. 6B and 6C, since the buffer region 11b is formed between the compressed region 11c and the non-compressed region 11a, the reference lead portion 164 serves as the measurement electrode 161. Even if formed outside the outer peripheral edge of the reference lead portion 164, the shear stress is not concentrated on the buffer region 11b, so that cracks are generated in the outer peripheral edge of the measuring electrode 161 and in the vicinity of the outer peripheral edge of the reference electrode 162. There is nothing to do.

Table 1 shows the effect of preventing cracks in the first to fourth embodiments of the present invention in comparison with the conventional configuration shown in FIGS.
The laminated gas sensor element 1 having the configuration shown in each embodiment was manufactured by the manufacturing process described above, and the presence or absence of occurrence of cracks was examined.
The results are shown in Table 1. The case where the crack occurred in three places is indicated as x, the case where the crack occurs in one place is indicated as ◯, and the case where the crack does not occur is indicated as ◎.

As is clear from Table 1, it can be seen that the configuration of the present invention provides a great effect in preventing the occurrence of cracks.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, in the third embodiment of the present invention, the case where the width of the measurement electrode 161 is wider than the width of the reference electrode 162 and the length of the measurement electrode 161 is longer than the length of the reference electrode 162 has been described. However, the same effect can be obtained when the width of the measurement electrode 161 is narrower than the width of the electrode and the length of the measurement electrode 161 is shorter than the length of the reference electrode 162.

  In the embodiment of the present invention, the oxygen concentration sensor consisting of only one cell has been described as an example of the laminated gas sensor. However, the present invention also applies to an oxygen sensor, a NOx sensor, or the like configured by a plurality of cells. It is suitable for preventing the occurrence of cracks at the interface between the region sandwiched between the pair of electrodes and the other region.

(A) represents the usage aspect of the laminated | stacked gas sensor element to which this invention was applied, (B) is a expansion | deployment perspective view which shows the detailed structure of the laminated | stacked gas sensor element 1 of FIG. 1 (A). (A) is a top view which shows the planar shape and positional relationship of a pair of measurement part electrode formed in the solid electrolyte layer which is the characteristic part of this invention, FIG.2 (B) and (C) are FIG.2 (A), respectively. It is the cross-sectional schematic diagram of the sensor part laminated body in middle AA, and the cross-sectional schematic diagram of the sensor part laminated body in BB in (A). (A) is a cross-sectional schematic diagram showing changes in the expanded structure of the solid electrolyte layer before and after conventional heating and pressure bonding, and (B) is an enlarged structure of the solid electrolyte layer before and after heating and pressure bonding in the embodiment of the present invention. It is a cross-sectional schematic diagram which shows a change. (A) shows the planar shape and positional relationship of a pair of measurement part electrodes formed in the solid electrolyte layer in 2nd Embodiment of this invention, (B) is an AA cross-sectional schematic diagram in FIG. 4 (A), (C) is a BB cross-sectional schematic diagram in FIG. 4 (A). (A) shows the planar shape and positional relationship of a pair of measurement part electrodes formed on the solid electrolyte layer in the third embodiment of the present invention, (B) is a schematic cross-sectional view taken along the line AA in FIG. (C) is a BB cross-sectional schematic diagram in FIG. 5 (A). (A) shows the planar shape and the positional relationship of a pair of measurement part electrodes formed in the solid electrolyte layer in 4th Embodiment of this invention, (B) is an AA cross-sectional schematic diagram in FIG. 6 (A), (C) is a schematic cross-sectional view taken along the line BB in FIG. 6 (A), and (D) is a schematic cross-sectional view taken along the line CC in FIG. 6 (A). The development view of the conventional laminated gas sensor is shown. (A) is a top view which shows the generation | occurrence | production position of the crack of the conventional laminated gas sensor, (B) is an AA cross-sectional schematic diagram in FIG. 8 (A), (C) is B- in FIG. 8 (A). It is a B cross-sectional schematic diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stack type gas sensor 15 Heater part 15b Heater part laminated body 150 Heater board | substrate 151a, 151b Through-hole 152a, 152b Heater lead part 153 Heat generating body 154a, 154b Through-hole electrode 155a, 155b Heater external terminal 13 Insulating layer 16 Sensor part 16b Sensor part Laminated bodies 161 and 162 A pair of measuring part electrodes 161 A gas electrode to be measured (measuring electrode)
162 Reference gas electrode (reference electrode)
163 Measurement lead part 164 Reference lead part 165, 166 External terminal 167, 168 Through-hole electrode 17 Gas shielding layer (shielding layer)
171 and 172 Through hole 14 Gas shielding layer (shielding layer)
140 Gas diffusion layer to be measured (diffusion layer)
141, 142 Through hole 11 Solid electrolyte layer 111 Through hole 18 Alumina-zirconia adhesive layer 12 Reference gas chamber forming layer 120 Reference gas chamber

Claims (6)

A gas electrode to be measured is provided on one of the opposing surfaces of the solid electrolyte layer, and a reference gas electrode is provided on the other to form a pair of measuring part electrodes, and a gas diffusion layer to be measured is provided on the one surface side as a reference In the laminated gas sensor formed by laminating and pressure bonding the gas introduction layer,
The solid electrolyte layer is compressed between the pair of measurement unit electrodes and inevitably compressed when being compressed with the gas diffusion layer to be measured, and is not compressed by any of the pair of measurement unit electrodes. A laminated gas sensor characterized by having a buffer region that relieves stress acting on the interface between the two regions.   2. The stacked gas sensor according to claim 1, wherein the buffer region is provided by forming all or part of the outer peripheral edge of one of the pair of measurement unit electrodes at a position outside the other outer peripheral edge.   3. The stacked gas sensor according to claim 1, wherein the buffer region is provided by forming one of the pair of measurement unit electrodes wider than the other in the width direction of the solid electrolyte layer.   4. The buffer region according to claim 1, wherein in the longitudinal direction of the solid electrolyte layer, the buffer region is provided by forming one of the pair of measurement unit electrodes longer than the other. 5. Multi-layer gas sensor.   The lead part which conduct | electrically_connects to a pair of said measurement-part electrode is provided in the surface of the said solid electrolyte layer, respectively, The width | variety of at least one of this lead part was provided in the same width as the said electrode. The laminated gas sensor according to 1.   6. A lead part for conducting the pair of measurement part electrodes is provided on the surface of the solid electrolyte layer, respectively, and one of the lead parts is provided outside the outer periphery of the other electrode and the lead part. The laminated gas sensor according to any one of the above.